From 8d836581f9b1f57ceaa2b47654754ef1260b410b Mon Sep 17 00:00:00 2001
From: Niklas Cassel <cassel@kernel.org>
Date: Wed, 16 Sep 2026 15:00:32 +0200
Subject: ata: libata-scsi: fix ata_dsm_trim_pages() kernel-doc

make htmldocs fails with:

  Documentation/driver-api/libata:604: ./drivers/ata/libata-scsi.c:2301:
  ERROR: Unexpected indentation. [docutils]

The Return: section of ata_dsm_trim_pages() ends its first sentence with
a colon and continues with an indented bullet list. reStructuredText
requires a blank line before an indented block, so docutils chokes on
the list.

Simply adding the missing blank line does not work either: Return: is a
kernel-doc "special section", which is terminated by the first blank
line, so the bullet list would end up in the Description section,
detached from the sentence introducing it.

Spell the two bounds out as prose instead, so that the Return: section
stays self-contained. Documentation-only change.

Fixes: e64e6b5dc867 ("ata: libata-scsi: scale DSM TRIM payload by MAX PAGES PER DSM COMMAND")
Reported-by: Thomas Huth <thuth@redhat.com>
Closes: https://lore.kernel.org/linux-ide/b0a0b8e8-cc4f-4c7b-8bc5-fee0712d405a@redhat.com/
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20260916130031.29990-2-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 Documentation/admin-guide/LSM/LoadPin.rst          |   31 +
 Documentation/admin-guide/LSM/SELinux.rst          |   44 +
 Documentation/admin-guide/LSM/SafeSetID.rst        |  118 +
 Documentation/admin-guide/LSM/Smack.rst            |  871 ++
 Documentation/admin-guide/LSM/Yama.rst             |   75 +
 Documentation/admin-guide/LSM/apparmor.rst         |   54 +
 Documentation/admin-guide/LSM/index.rst            |   51 +
 Documentation/admin-guide/LSM/ipe.rst              |  835 ++
 Documentation/admin-guide/LSM/landlock.rst         |  298 +
 Documentation/admin-guide/LSM/tomoyo.rst           |   52 +
 .../admin-guide/RAS/address-translation.rst        |   24 +
 Documentation/admin-guide/RAS/error-decoding.rst   |   21 +
 Documentation/admin-guide/RAS/index.rst            |    7 +
 Documentation/admin-guide/RAS/main.rst             | 1087 +++
 Documentation/admin-guide/README.rst               |  360 +
 Documentation/admin-guide/abi-obsolete-files.rst   |    7 +
 Documentation/admin-guide/abi-obsolete.rst         |   13 +
 Documentation/admin-guide/abi-removed-files.rst    |    7 +
 Documentation/admin-guide/abi-removed.rst          |    7 +
 Documentation/admin-guide/abi-stable-files.rst     |    7 +
 Documentation/admin-guide/abi-stable.rst           |   16 +
 Documentation/admin-guide/abi-testing-files.rst    |    7 +
 Documentation/admin-guide/abi-testing.rst          |   22 +
 Documentation/admin-guide/abi.rst                  |   29 +
 Documentation/admin-guide/acpi/cppc_sysfs.rst      |   78 +
 .../admin-guide/acpi/fan_performance_states.rst    |   90 +
 Documentation/admin-guide/acpi/index.rst           |   14 +
 .../admin-guide/acpi/initrd_table_override.rst     |  115 +
 Documentation/admin-guide/acpi/ssdt-overlays.rst   |  181 +
 Documentation/admin-guide/aoe/aoe.rst              |  150 +
 Documentation/admin-guide/aoe/autoload.sh          |   17 +
 Documentation/admin-guide/aoe/examples.rst         |   23 +
 Documentation/admin-guide/aoe/index.rst            |   10 +
 Documentation/admin-guide/aoe/status.sh            |   30 +
 Documentation/admin-guide/aoe/todo.rst             |   17 +
 Documentation/admin-guide/aoe/udev-install.sh      |   33 +
 Documentation/admin-guide/aoe/udev.txt             |   26 +
 .../admin-guide/auxdisplay/cfag12864b.rst          |   98 +
 Documentation/admin-guide/auxdisplay/index.rst     |    9 +
 Documentation/admin-guide/auxdisplay/ks0108.rst    |   50 +
 Documentation/admin-guide/bcache.rst               |  644 ++
 Documentation/admin-guide/binderfs.rst             |   87 +
 Documentation/admin-guide/binfmt-misc.rst          |  391 +
 .../blockdev/drbd/DRBD-8.3-data-packets.svg        |  588 ++
 .../blockdev/drbd/DRBD-data-packets.svg            |  459 ++
 .../admin-guide/blockdev/drbd/conn-states-8.dot    |   18 +
 .../blockdev/drbd/data-structure-v9.rst            |   42 +
 .../admin-guide/blockdev/drbd/disk-states-8.dot    |   16 +
 .../drbd/drbd-connection-state-overview.dot        |   85 +
 .../admin-guide/blockdev/drbd/figures.rst          |   30 +
 Documentation/admin-guide/blockdev/drbd/index.rst  |   19 +
 .../admin-guide/blockdev/drbd/peer-states-8.dot    |    8 +
 Documentation/admin-guide/blockdev/floppy.rst      |  255 +
 Documentation/admin-guide/blockdev/index.rst       |   17 +
 Documentation/admin-guide/blockdev/nbd.rst         |   31 +
 Documentation/admin-guide/blockdev/paride.rst      |  207 +
 Documentation/admin-guide/blockdev/ramdisk.rst     |  153 +
 Documentation/admin-guide/blockdev/zoned_loop.rst  |  191 +
 Documentation/admin-guide/blockdev/zram.rst        |  610 ++
 Documentation/admin-guide/bootconfig.rst           |  416 +
 Documentation/admin-guide/braille-console.rst      |   38 +
 Documentation/admin-guide/btmrvl.rst               |  124 +
 Documentation/admin-guide/bug-bisect.rst           |  165 +
 Documentation/admin-guide/bug-hunting.rst          |  370 +
 .../admin-guide/cgroup-v1/blkio-controller.rst     |  301 +
 Documentation/admin-guide/cgroup-v1/cgroups.rst    |  697 ++
 Documentation/admin-guide/cgroup-v1/cpuacct.rst    |   50 +
 Documentation/admin-guide/cgroup-v1/cpusets.rst    |  874 ++
 Documentation/admin-guide/cgroup-v1/devices.rst    |  132 +
 .../admin-guide/cgroup-v1/freezer-subsystem.rst    |  131 +
 Documentation/admin-guide/cgroup-v1/hugetlb.rst    |  139 +
 Documentation/admin-guide/cgroup-v1/index.rst      |   24 +
 Documentation/admin-guide/cgroup-v1/memcg_test.rst |  342 +
 Documentation/admin-guide/cgroup-v1/memory.rst     |  963 +++
 Documentation/admin-guide/cgroup-v1/misc.rst       |    4 +
 Documentation/admin-guide/cgroup-v1/net_cls.rst    |   44 +
 Documentation/admin-guide/cgroup-v1/net_prio.rst   |   57 +
 Documentation/admin-guide/cgroup-v1/pids.rst       |   93 +
 Documentation/admin-guide/cgroup-v1/rdma.rst       |  191 +
 Documentation/admin-guide/cgroup-v2.rst            | 3575 ++++++++
 Documentation/admin-guide/cifs/authors.rst         |   69 +
 Documentation/admin-guide/cifs/changes.rst         |    9 +
 Documentation/admin-guide/cifs/index.rst           |   14 +
 Documentation/admin-guide/cifs/introduction.rst    |   53 +
 Documentation/admin-guide/cifs/todo.rst            |  133 +
 Documentation/admin-guide/cifs/usage.rst           |  864 ++
 Documentation/admin-guide/cifs/winucase_convert.pl |   62 +
 Documentation/admin-guide/clearing-warn-once.rst   |    9 +
 Documentation/admin-guide/cpu-isolation.rst        |  357 +
 Documentation/admin-guide/cpu-load.rst             |  117 +
 Documentation/admin-guide/cputopology.rst          |  101 +
 Documentation/admin-guide/dell_rbu.rst             |  128 +
 .../admin-guide/device-mapper/cache-policies.rst   |  131 +
 Documentation/admin-guide/device-mapper/cache.rst  |  337 +
 Documentation/admin-guide/device-mapper/delay.rst  |   54 +
 .../admin-guide/device-mapper/dm-clone.rst         |  333 +
 .../admin-guide/device-mapper/dm-crypt.rst         |  212 +
 .../admin-guide/device-mapper/dm-dust.rst          |  305 +
 Documentation/admin-guide/device-mapper/dm-ebs.rst |   51 +
 .../admin-guide/device-mapper/dm-flakey.rst        |   88 +
 Documentation/admin-guide/device-mapper/dm-ima.rst |  718 ++
 .../admin-guide/device-mapper/dm-init.rst          |  133 +
 .../admin-guide/device-mapper/dm-inlinecrypt.rst   |  129 +
 .../admin-guide/device-mapper/dm-integrity.rst     |  321 +
 Documentation/admin-guide/device-mapper/dm-io.rst  |   75 +
 Documentation/admin-guide/device-mapper/dm-log.rst |   57 +
 .../admin-guide/device-mapper/dm-pcache.rst        |  202 +
 .../admin-guide/device-mapper/dm-queue-length.rst  |   48 +
 .../admin-guide/device-mapper/dm-raid.rst          |  489 ++
 .../admin-guide/device-mapper/dm-service-time.rst  |  101 +
 .../admin-guide/device-mapper/dm-uevent.rst        |  110 +
 .../admin-guide/device-mapper/dm-zoned.rst         |  194 +
 Documentation/admin-guide/device-mapper/era.rst    |  116 +
 Documentation/admin-guide/device-mapper/index.rst  |   43 +
 Documentation/admin-guide/device-mapper/kcopyd.rst |   47 +
 Documentation/admin-guide/device-mapper/linear.rst |   63 +
 .../admin-guide/device-mapper/log-writes.rst       |  145 +
 .../admin-guide/device-mapper/persistent-data.rst  |   88 +
 .../admin-guide/device-mapper/snapshot.rst         |  196 +
 .../admin-guide/device-mapper/statistics.rst       |  225 +
 .../admin-guide/device-mapper/striped.rst          |   61 +
 Documentation/admin-guide/device-mapper/switch.rst |  141 +
 .../device-mapper/thin-provisioning.rst            |  427 +
 .../admin-guide/device-mapper/unstriped.rst        |  135 +
 .../admin-guide/device-mapper/vdo-design.rst       |  633 ++
 Documentation/admin-guide/device-mapper/vdo.rst    |  413 +
 Documentation/admin-guide/device-mapper/verity.rst |  349 +
 .../admin-guide/device-mapper/writecache.rst       |  114 +
 Documentation/admin-guide/device-mapper/zero.rst   |   37 +
 Documentation/admin-guide/devices.rst              |  270 +
 Documentation/admin-guide/devices.txt              | 3081 +++++++
 Documentation/admin-guide/dynamic-debug-howto.rst  |  392 +
 Documentation/admin-guide/edid.rst                 |   27 +
 Documentation/admin-guide/efi-stub.rst             |  103 +
 Documentation/admin-guide/ext4.rst                 |  611 ++
 Documentation/admin-guide/features.rst             |    3 +
 .../admin-guide/filesystem-monitoring.rst          |   78 +
 Documentation/admin-guide/gpio/gpio-aggregator.rst |  218 +
 Documentation/admin-guide/gpio/gpio-mockup.rst     |   59 +
 Documentation/admin-guide/gpio/gpio-sim.rst        |  137 +
 Documentation/admin-guide/gpio/gpio-virtuser.rst   |  177 +
 Documentation/admin-guide/gpio/index.rst           |   14 +
 Documentation/admin-guide/gpio/obsolete.rst        |   13 +
 .../admin-guide/hw-vuln/attack_vector_controls.rst |  236 +
 .../admin-guide/hw-vuln/core-scheduling.rst        |  226 +
 .../admin-guide/hw-vuln/cross-thread-rsb.rst       |   91 +
 .../admin-guide/hw-vuln/gather_data_sampling.rst   |  109 +
 Documentation/admin-guide/hw-vuln/index.rst        |   29 +
 .../hw-vuln/indirect-target-selection.rst          |  168 +
 Documentation/admin-guide/hw-vuln/l1d_flush.rst    |   69 +
 Documentation/admin-guide/hw-vuln/l1tf.rst         |  615 ++
 Documentation/admin-guide/hw-vuln/mds.rst          |  303 +
 Documentation/admin-guide/hw-vuln/multihit.rst     |  167 +
 .../admin-guide/hw-vuln/old_microcode.rst          |   21 +
 .../hw-vuln/processor_mmio_stale_data.rst          |  269 +
 .../admin-guide/hw-vuln/reg-file-data-sampling.rst |   96 +
 Documentation/admin-guide/hw-vuln/rsb.rst          |  268 +
 .../special-register-buffer-data-sampling.rst      |  150 +
 Documentation/admin-guide/hw-vuln/spectre.rst      |  725 ++
 Documentation/admin-guide/hw-vuln/srso.rst         |  242 +
 .../admin-guide/hw-vuln/tsx_async_abort.rst        |  270 +
 Documentation/admin-guide/hw-vuln/vmscape.rst      |  110 +
 Documentation/admin-guide/hw_random.rst            |  104 +
 Documentation/admin-guide/index.rst                |  192 +
 Documentation/admin-guide/init.rst                 |   48 +
 Documentation/admin-guide/initrd.rst               |  383 +
 Documentation/admin-guide/iostats.rst              |  187 +
 Documentation/admin-guide/java.rst                 |  423 +
 Documentation/admin-guide/jfs.rst                  |   66 +
 Documentation/admin-guide/kdump/gdbmacros.txt      |  323 +
 Documentation/admin-guide/kdump/index.rst          |   13 +
 Documentation/admin-guide/kdump/kdump.rst          |  612 ++
 Documentation/admin-guide/kdump/vmcoreinfo.rst     |  596 ++
 Documentation/admin-guide/kernel-parameters.rst    |  135 +
 Documentation/admin-guide/kernel-parameters.txt    | 8709 ++++++++++++++++++++
 .../admin-guide/kernel-per-CPU-kthreads.rst        |  325 +
 .../admin-guide/laptops/alienware-wmi.rst          |  127 +
 Documentation/admin-guide/laptops/asus-laptop.rst  |  271 +
 .../admin-guide/laptops/disk-shock-protection.rst  |  151 +
 Documentation/admin-guide/laptops/index.rst        |   19 +
 Documentation/admin-guide/laptops/lg-laptop.rst    |   82 +
 .../admin-guide/laptops/samsung-galaxybook.rst     |  174 +
 Documentation/admin-guide/laptops/sony-laptop.rst  |  174 +
 Documentation/admin-guide/laptops/sonypi.rst       |  158 +
 .../admin-guide/laptops/thinkpad-acpi.rst          | 1773 ++++
 Documentation/admin-guide/laptops/toshiba_haps.rst |   87 +
 .../admin-guide/laptops/uniwill-laptop.rst         |  118 +
 Documentation/admin-guide/lcd-panel-cgram.rst      |   27 +
 Documentation/admin-guide/ldm.rst                  |  121 +
 Documentation/admin-guide/lockup-watchdogs.rst     |  179 +
 Documentation/admin-guide/md.rst                   |  811 ++
 Documentation/admin-guide/media/amdisp4-1.rst      |   63 +
 Documentation/admin-guide/media/amdisp4.dot        |    6 +
 .../admin-guide/media/au0828-cardlist.rst          |   39 +
 Documentation/admin-guide/media/avermedia.rst      |   94 +
 Documentation/admin-guide/media/bt8xx.rst          |  157 +
 Documentation/admin-guide/media/bttv-cardlist.rst  |  683 ++
 Documentation/admin-guide/media/bttv.rst           | 1762 ++++
 Documentation/admin-guide/media/building.rst       |  357 +
 Documentation/admin-guide/media/c3-isp.dot         |   26 +
 Documentation/admin-guide/media/c3-isp.rst         |  101 +
 Documentation/admin-guide/media/cafe_ccic.rst      |   62 +
 Documentation/admin-guide/media/cardlist.rst       |   29 +
 Documentation/admin-guide/media/cec.rst            |  467 ++
 Documentation/admin-guide/media/ci.rst             |   77 +
 Documentation/admin-guide/media/cx18-cardlist.rst  |   17 +
 .../admin-guide/media/cx231xx-cardlist.rst         |   99 +
 .../admin-guide/media/cx23885-cardlist.rst         |  267 +
 Documentation/admin-guide/media/cx88-cardlist.rst  |  383 +
 Documentation/admin-guide/media/cx88.rst           |   58 +
 Documentation/admin-guide/media/dvb-drivers.rst    |   15 +
 .../admin-guide/media/dvb-usb-a800-cardlist.rst    |   16 +
 .../admin-guide/media/dvb-usb-af9005-cardlist.rst  |   20 +
 .../admin-guide/media/dvb-usb-af9015-cardlist.rst  |   80 +
 .../admin-guide/media/dvb-usb-af9035-cardlist.rst  |   74 +
 .../admin-guide/media/dvb-usb-anysee-cardlist.rst  |   16 +
 .../admin-guide/media/dvb-usb-au6610-cardlist.rst  |   16 +
 .../admin-guide/media/dvb-usb-az6007-cardlist.rst  |   20 +
 .../admin-guide/media/dvb-usb-az6027-cardlist.rst  |   24 +
 .../admin-guide/media/dvb-usb-ce6230-cardlist.rst  |   18 +
 .../media/dvb-usb-cinergyT2-cardlist.rst           |   16 +
 .../admin-guide/media/dvb-usb-cxusb-cardlist.rst   |   40 +
 .../admin-guide/media/dvb-usb-dib0700-cardlist.rst |  162 +
 .../media/dvb-usb-dibusb-mb-cardlist.rst           |   42 +
 .../media/dvb-usb-dibusb-mc-cardlist.rst           |   30 +
 .../admin-guide/media/dvb-usb-digitv-cardlist.rst  |   16 +
 .../admin-guide/media/dvb-usb-dtt200u-cardlist.rst |   22 +
 .../admin-guide/media/dvb-usb-dtv5100-cardlist.rst |   16 +
 .../admin-guide/media/dvb-usb-dvbsky-cardlist.rst  |   42 +
 .../admin-guide/media/dvb-usb-dw2102-cardlist.rst  |   56 +
 .../admin-guide/media/dvb-usb-ec168-cardlist.rst   |   16 +
 .../admin-guide/media/dvb-usb-gl861-cardlist.rst   |   20 +
 .../admin-guide/media/dvb-usb-gp8psk-cardlist.rst  |   22 +
 .../admin-guide/media/dvb-usb-lmedm04-cardlist.rst |   20 +
 .../admin-guide/media/dvb-usb-m920x-cardlist.rst   |   26 +
 .../media/dvb-usb-mxl111sf-cardlist.rst            |   36 +
 .../media/dvb-usb-nova-t-usb2-cardlist.rst         |   16 +
 .../admin-guide/media/dvb-usb-opera1-cardlist.rst  |   16 +
 .../media/dvb-usb-pctv452e-cardlist.rst            |   20 +
 .../media/dvb-usb-rtl28xxu-cardlist.rst            |   80 +
 .../media/dvb-usb-technisat-usb2-cardlist.rst      |   16 +
 .../admin-guide/media/dvb-usb-ttusb2-cardlist.rst  |   24 +
 .../admin-guide/media/dvb-usb-umt-010-cardlist.rst |   16 +
 .../admin-guide/media/dvb-usb-vp702x-cardlist.rst  |   16 +
 .../admin-guide/media/dvb-usb-vp7045-cardlist.rst  |   18 +
 .../admin-guide/media/dvb-usb-zd1301-cardlist.rst  |   16 +
 Documentation/admin-guide/media/dvb.rst            |   12 +
 Documentation/admin-guide/media/dvb_intro.rst      |  616 ++
 Documentation/admin-guide/media/dvb_references.rst |   29 +
 .../admin-guide/media/em28xx-cardlist.rst          |  452 +
 Documentation/admin-guide/media/faq.rst            |  216 +
 Documentation/admin-guide/media/fimc.rst           |  153 +
 .../admin-guide/media/frontend-cardlist.rst        |  226 +
 Documentation/admin-guide/media/gspca-cardlist.rst |  451 +
 Documentation/admin-guide/media/i2c-cardlist.rst   |  287 +
 Documentation/admin-guide/media/imx.rst            |  714 ++
 .../admin-guide/media/imx6q-sabreauto.dot          |   51 +
 Documentation/admin-guide/media/imx6q-sabresd.dot  |   56 +
 Documentation/admin-guide/media/imx7.rst           |  221 +
 Documentation/admin-guide/media/index.rst          |   61 +
 Documentation/admin-guide/media/intro.rst          |   27 +
 Documentation/admin-guide/media/ipu3.rst           |  596 ++
 Documentation/admin-guide/media/ipu3_rcb.svg       |  331 +
 Documentation/admin-guide/media/ipu6-isys.rst      |  161 +
 .../admin-guide/media/ipu6_isys_graph.svg          |  548 ++
 Documentation/admin-guide/media/ivtv-cardlist.rst  |  139 +
 Documentation/admin-guide/media/ivtv.rst           |  218 +
 Documentation/admin-guide/media/lmedm04.rst        |  107 +
 Documentation/admin-guide/media/mali-c55-graph.dot |   19 +
 Documentation/admin-guide/media/mali-c55.rst       |  413 +
 Documentation/admin-guide/media/mgb4.rst           |  396 +
 Documentation/admin-guide/media/misc-cardlist.rst  |   28 +
 Documentation/admin-guide/media/omap3isp.rst       |   92 +
 Documentation/admin-guide/media/opera-firmware.rst |   33 +
 .../admin-guide/media/other-usb-cardlist.rst       |   78 +
 Documentation/admin-guide/media/pci-cardlist.rst   |  108 +
 Documentation/admin-guide/media/philips.rst        |  247 +
 .../admin-guide/media/platform-cardlist.rst        |   87 +
 Documentation/admin-guide/media/qcom_camss.rst     |  185 +
 .../admin-guide/media/qcom_camss_8x96_graph.dot    |  106 +
 .../admin-guide/media/qcom_camss_graph.dot         |   43 +
 Documentation/admin-guide/media/radio-cardlist.rst |   43 +
 .../admin-guide/media/raspberrypi-pisp-be.dot      |   20 +
 .../admin-guide/media/raspberrypi-pisp-be.rst      |  109 +
 .../admin-guide/media/raspberrypi-rp1-cfe.dot      |   27 +
 .../admin-guide/media/raspberrypi-rp1-cfe.rst      |   78 +
 Documentation/admin-guide/media/rcar-fdp1.rst      |   39 +
 .../admin-guide/media/remote-controller.rst        |   76 +
 .../admin-guide/media/rkcif-rk3568-vicap.dot       |    8 +
 .../admin-guide/media/rkcif-rk3588-vicap.dot       |   29 +
 Documentation/admin-guide/media/rkcif.rst          |  111 +
 Documentation/admin-guide/media/rkisp1.dot         |   18 +
 Documentation/admin-guide/media/rkisp1.rst         |  204 +
 .../admin-guide/media/saa7134-cardlist.rst         |  803 ++
 Documentation/admin-guide/media/saa7134.rst        |   89 +
 .../admin-guide/media/saa7164-cardlist.rst         |   71 +
 Documentation/admin-guide/media/si470x.rst         |  167 +
 Documentation/admin-guide/media/si4713.rst         |  192 +
 Documentation/admin-guide/media/si476x.rst         |  160 +
 Documentation/admin-guide/media/siano-cardlist.rst |   56 +
 Documentation/admin-guide/media/technisat.rst      |  100 +
 Documentation/admin-guide/media/ttusb-dec.rst      |   45 +
 Documentation/admin-guide/media/tuner-cardlist.rst |  102 +
 Documentation/admin-guide/media/usb-cardlist.rst   |  149 +
 Documentation/admin-guide/media/v4l-drivers.rst    |   39 +
 Documentation/admin-guide/media/vimc.dot           |   26 +
 Documentation/admin-guide/media/vimc.rst           |  110 +
 Documentation/admin-guide/media/visl.rst           |  185 +
 Documentation/admin-guide/media/vivid.rst          | 1361 +++
 Documentation/admin-guide/media/zoran-cardlist.rst |   51 +
 Documentation/admin-guide/mm/cma_debugfs.rst       |   31 +
 Documentation/admin-guide/mm/concepts.rst          |  220 +
 Documentation/admin-guide/mm/damon/index.rst       |   17 +
 Documentation/admin-guide/mm/damon/lru_sort.rst    |  368 +
 Documentation/admin-guide/mm/damon/reclaim.rst     |  349 +
 Documentation/admin-guide/mm/damon/start.rst       |  178 +
 Documentation/admin-guide/mm/damon/stat.rst        |   98 +
 Documentation/admin-guide/mm/damon/usage.rst       |  762 ++
 Documentation/admin-guide/mm/hugetlbpage.rst       |  487 ++
 .../admin-guide/mm/idle_page_tracking.rst          |  118 +
 Documentation/admin-guide/mm/index.rst             |   45 +
 Documentation/admin-guide/mm/kho.rst               |  123 +
 Documentation/admin-guide/mm/ksm.rst               |  323 +
 Documentation/admin-guide/mm/memory-hotplug.rst    |  706 ++
 Documentation/admin-guide/mm/multigen_lru.rst      |  163 +
 Documentation/admin-guide/mm/nommu-mmap.rst        |  283 +
 .../admin-guide/mm/numa_memory_policy.rst          |  523 ++
 Documentation/admin-guide/mm/numaperf.rst          |  176 +
 Documentation/admin-guide/mm/pagemap.rst           |  324 +
 Documentation/admin-guide/mm/shrinker_debugfs.rst  |  133 +
 Documentation/admin-guide/mm/slab.rst              |  469 ++
 Documentation/admin-guide/mm/soft-dirty.rst        |   45 +
 Documentation/admin-guide/mm/transhuge.rst         |  784 ++
 Documentation/admin-guide/mm/userfaultfd.rst       |  687 ++
 Documentation/admin-guide/mm/zswap.rst             |  138 +
 Documentation/admin-guide/module-signing.rst       |  292 +
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diff --git a/Documentation/admin-guide/LSM/LoadPin.rst b/Documentation/admin-guide/LSM/LoadPin.rst
new file mode 100644
index 000000000..dd3ca68b5
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+++ b/Documentation/admin-guide/LSM/LoadPin.rst
@@ -0,0 +1,31 @@
+=======
+LoadPin
+=======
+
+LoadPin is a Linux Security Module that ensures all kernel-loaded files
+(modules, firmware, etc) all originate from the same filesystem, with
+the expectation that such a filesystem is backed by a read-only device
+such as dm-verity or CDROM. This allows systems that have a verified
+and/or unchangeable filesystem to enforce module and firmware loading
+restrictions without needing to sign the files individually.
+
+The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and
+can be controlled at boot-time with the kernel command line option
+"``loadpin.enforce``". By default, it is enabled, but can be disabled at
+boot ("``loadpin.enforce=0``").
+
+LoadPin starts pinning when it sees the first file loaded. If the
+block device backing the filesystem is not read-only, a sysctl is
+created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having
+a mutable filesystem means pinning is mutable too, but having the
+sysctl allows for easy testing on systems with a mutable filesystem.)
+
+It's also possible to exclude specific file types from LoadPin using kernel
+command line option "``loadpin.exclude``". By default, all files are
+included, but they can be excluded using kernel command line option such
+as "``loadpin.exclude=kernel-module,kexec-image``". This allows to use
+different mechanisms such as ``CONFIG_MODULE_SIG`` and
+``CONFIG_KEXEC_VERIFY_SIG`` to verify kernel module and kernel image while
+still use LoadPin to protect the integrity of other files kernel loads. The
+full list of valid file types can be found in ``kernel_read_file_str``
+defined in ``include/linux/kernel_read_file.h``.
diff --git a/Documentation/admin-guide/LSM/SELinux.rst b/Documentation/admin-guide/LSM/SELinux.rst
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+++ b/Documentation/admin-guide/LSM/SELinux.rst
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+=======
+SELinux
+=======
+
+Information about the SELinux kernel subsystem can be found at the
+following links:
+
+	https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux.git/tree/README.md
+
+	https://github.com/selinuxproject/selinux-kernel/wiki
+
+Information about the SELinux userspace can be found at:
+
+	https://github.com/SELinuxProject/selinux/wiki
+
+If you want to use SELinux, chances are you will want
+to use the distro-provided policies, or install the
+latest reference policy release from
+
+	https://github.com/SELinuxProject/refpolicy
+
+However, if you want to install a dummy policy for
+testing, you can do using ``mdp`` provided under
+scripts/selinux.  Note that this requires the selinux
+userspace to be installed - in particular you will
+need checkpolicy to compile a kernel, and setfiles and
+fixfiles to label the filesystem.
+
+	1. Compile the kernel with selinux enabled.
+	2. Type ``make`` to compile ``mdp``.
+	3. Make sure that you are not running with
+	   SELinux enabled and a real policy.  If
+	   you are, reboot with selinux disabled
+	   before continuing.
+	4. Run install_policy.sh::
+
+		cd scripts/selinux
+		sh install_policy.sh
+
+Step 4 will create a new dummy policy valid for your
+kernel, with a single selinux user, role, and type.
+It will compile the policy, will set your ``SELINUXTYPE`` to
+``dummy`` in ``/etc/selinux/config``, install the compiled policy
+as ``dummy``, and relabel your filesystem.
diff --git a/Documentation/admin-guide/LSM/SafeSetID.rst b/Documentation/admin-guide/LSM/SafeSetID.rst
new file mode 100644
index 000000000..6d439c987
--- /dev/null
+++ b/Documentation/admin-guide/LSM/SafeSetID.rst
@@ -0,0 +1,118 @@
+=========
+SafeSetID
+=========
+SafeSetID is an LSM module that gates the setid family of syscalls to restrict
+UID/GID transitions from a given UID/GID to only those approved by a
+system-wide allowlist. These restrictions also prohibit the given UIDs/GIDs
+from obtaining auxiliary privileges associated with CAP_SET{U/G}ID, such as
+allowing a user to set up user namespace UID/GID mappings.
+
+
+Background
+==========
+In absence of file capabilities, processes spawned on a Linux system that need
+to switch to a different user must be spawned with CAP_SETUID privileges.
+CAP_SETUID is granted to programs running as root or those running as a non-root
+user that have been explicitly given the CAP_SETUID runtime capability. It is
+often preferable to use Linux runtime capabilities rather than file
+capabilities, since using file capabilities to run a program with elevated
+privileges opens up possible security holes since any user with access to the
+file can exec() that program to gain the elevated privileges.
+
+While it is possible to implement a tree of processes by giving full
+CAP_SET{U/G}ID capabilities, this is often at odds with the goals of running a
+tree of processes under non-root user(s) in the first place. Specifically,
+since CAP_SETUID allows changing to any user on the system, including the root
+user, it is an overpowered capability for what is needed in this scenario,
+especially since programs often only call setuid() to drop privileges to a
+lesser-privileged user -- not elevate privileges. Unfortunately, there is no
+generally feasible way in Linux to restrict the potential UIDs that a user can
+switch to through setuid() beyond allowing a switch to any user on the system.
+This SafeSetID LSM seeks to provide a solution for restricting setid
+capabilities in such a way.
+
+The main use case for this LSM is to allow a non-root program to transition to
+other untrusted uids without full blown CAP_SETUID capabilities. The non-root
+program would still need CAP_SETUID to do any kind of transition, but the
+additional restrictions imposed by this LSM would mean it is a "safer" version
+of CAP_SETUID since the non-root program cannot take advantage of CAP_SETUID to
+do any unapproved actions (e.g. setuid to uid 0 or create/enter new user
+namespace). The higher level goal is to allow for uid-based sandboxing of system
+services without having to give out CAP_SETUID all over the place just so that
+non-root programs can drop to even-lesser-privileged uids. This is especially
+relevant when one non-root daemon on the system should be allowed to spawn other
+processes as different uids, but it's undesirable to give the daemon a
+basically-root-equivalent CAP_SETUID.
+
+
+Other Approaches Considered
+===========================
+
+Solve this problem in userspace
+-------------------------------
+For candidate applications that would like to have restricted setid capabilities
+as implemented in this LSM, an alternative option would be to simply take away
+setid capabilities from the application completely and refactor the process
+spawning semantics in the application (e.g. by using a privileged helper program
+to do process spawning and UID/GID transitions). Unfortunately, there are a
+number of semantics around process spawning that would be affected by this, such
+as fork() calls where the program doesn't immediately call exec() after the
+fork(), parent processes specifying custom environment variables or command line
+args for spawned child processes, or inheritance of file handles across a
+fork()/exec(). Because of this, as solution that uses a privileged helper in
+userspace would likely be less appealing to incorporate into existing projects
+that rely on certain process-spawning semantics in Linux.
+
+Use user namespaces
+-------------------
+Another possible approach would be to run a given process tree in its own user
+namespace and give programs in the tree setid capabilities. In this way,
+programs in the tree could change to any desired UID/GID in the context of their
+own user namespace, and only approved UIDs/GIDs could be mapped back to the
+initial system user namespace, affectively preventing privilege escalation.
+Unfortunately, it is not generally feasible to use user namespaces in isolation,
+without pairing them with other namespace types, which is not always an option.
+Linux checks for capabilities based off of the user namespace that "owns" some
+entity. For example, Linux has the notion that network namespaces are owned by
+the user namespace in which they were created. A consequence of this is that
+capability checks for access to a given network namespace are done by checking
+whether a task has the given capability in the context of the user namespace
+that owns the network namespace -- not necessarily the user namespace under
+which the given task runs. Therefore spawning a process in a new user namespace
+effectively prevents it from accessing the network namespace owned by the
+initial namespace. This is a deal-breaker for any application that expects to
+retain the CAP_NET_ADMIN capability for the purpose of adjusting network
+configurations. Using user namespaces in isolation causes problems regarding
+other system interactions, including use of pid namespaces and device creation.
+
+Use an existing LSM
+-------------------
+None of the other in-tree LSMs have the capability to gate setid transitions, or
+even employ the security_task_fix_setuid hook at all. SELinux says of that hook:
+"Since setuid only affects the current process, and since the SELinux controls
+are not based on the Linux identity attributes, SELinux does not need to control
+this operation."
+
+
+Directions for use
+==================
+This LSM hooks the setid syscalls to make sure transitions are allowed if an
+applicable restriction policy is in place. Policies are configured through
+securityfs by writing to the safesetid/uid_allowlist_policy and
+safesetid/gid_allowlist_policy files at the location where securityfs is
+mounted. The format for adding a policy is '<UID>:<UID>' or '<GID>:<GID>',
+using literal numbers, and ending with a newline character such as '123:456\n'.
+Writing an empty string "" will flush the policy. Again, configuring a policy
+for a UID/GID will prevent that UID/GID from obtaining auxiliary setid
+privileges, such as allowing a user to set up user namespace UID/GID mappings.
+
+Note on GID policies and setgroups()
+====================================
+In v5.9 we are adding support for limiting CAP_SETGID privileges as was done
+previously for CAP_SETUID. However, for compatibility with common sandboxing
+related code conventions in userspace, we currently allow arbitrary
+setgroups() calls for processes with CAP_SETGID restrictions. Until we add
+support in a future release for restricting setgroups() calls, these GID
+policies add no meaningful security. setgroups() restrictions will be enforced
+once we have the policy checking code in place, which will rely on GID policy
+configuration code added in v5.9.
diff --git a/Documentation/admin-guide/LSM/Smack.rst b/Documentation/admin-guide/LSM/Smack.rst
new file mode 100644
index 000000000..c5ed775f2
--- /dev/null
+++ b/Documentation/admin-guide/LSM/Smack.rst
@@ -0,0 +1,871 @@
+=====
+Smack
+=====
+
+
+    "Good for you, you've decided to clean the elevator!"
+    - The Elevator, from Dark Star
+
+Smack is the Simplified Mandatory Access Control Kernel.
+Smack is a kernel based implementation of mandatory access
+control that includes simplicity in its primary design goals.
+
+Smack is not the only Mandatory Access Control scheme
+available for Linux. Those new to Mandatory Access Control
+are encouraged to compare Smack with the other mechanisms
+available to determine which is best suited to the problem
+at hand.
+
+Smack consists of three major components:
+
+    - The kernel
+    - Basic utilities, which are helpful but not required
+    - Configuration data
+
+The kernel component of Smack is implemented as a Linux
+Security Modules (LSM) module. It requires netlabel and
+works best with file systems that support extended attributes,
+although xattr support is not strictly required.
+It is safe to run a Smack kernel under a "vanilla" distribution.
+
+Smack kernels use the CIPSO IP option. Some network
+configurations are intolerant of IP options and can impede
+access to systems that use them as Smack does.
+
+Smack is used in the Tizen operating system. Please
+go to http://wiki.tizen.org for information about how
+Smack is used in Tizen.
+
+The current git repository for Smack user space is:
+
+	git://github.com/smack-team/smack.git
+
+This should make and install on most modern distributions.
+There are five commands included in smackutil:
+
+chsmack:
+	display or set Smack extended attribute values
+
+smackctl:
+	load the Smack access rules
+
+smackaccess:
+	report if a process with one label has access
+	to an object with another
+
+These two commands are obsolete with the introduction of
+the smackfs/load2 and smackfs/cipso2 interfaces.
+
+smackload:
+	properly formats data for writing to smackfs/load
+
+smackcipso:
+	properly formats data for writing to smackfs/cipso
+
+In keeping with the intent of Smack, configuration data is
+minimal and not strictly required. The most important
+configuration step is mounting the smackfs pseudo filesystem.
+If smackutil is installed the startup script will take care
+of this, but it can be manually as well.
+
+Add this line to ``/etc/fstab``::
+
+    smackfs /sys/fs/smackfs smackfs defaults 0 0
+
+The ``/sys/fs/smackfs`` directory is created by the kernel.
+
+Smack uses extended attributes (xattrs) to store labels on filesystem
+objects. The attributes are stored in the extended attribute security
+name space. A process must have ``CAP_MAC_ADMIN`` to change any of these
+attributes.
+
+The extended attributes that Smack uses are:
+
+SMACK64
+	Used to make access control decisions. In almost all cases
+	the label given to a new filesystem object will be the label
+	of the process that created it.
+
+SMACK64EXEC
+	The Smack label of a process that execs a program file with
+	this attribute set will run with this attribute's value.
+
+SMACK64MMAP
+	Don't allow the file to be mmapped by a process whose Smack
+	label does not allow all of the access permitted to a process
+	with the label contained in this attribute. This is a very
+	specific use case for shared libraries.
+
+SMACK64TRANSMUTE
+	Can only have the value "TRUE". If this attribute is present
+	on a directory when an object is created in the directory and
+	the Smack rule (more below) that permitted the write access
+	to the directory includes the transmute ("t") mode the object
+	gets the label of the directory instead of the label of the
+	creating process. If the object being created is a directory
+	the SMACK64TRANSMUTE attribute is set as well.
+
+SMACK64IPIN
+	This attribute is only available on file descriptors for sockets.
+	Use the Smack label in this attribute for access control
+	decisions on packets being delivered to this socket.
+
+SMACK64IPOUT
+	This attribute is only available on file descriptors for sockets.
+	Use the Smack label in this attribute for access control
+	decisions on packets coming from this socket.
+
+There are multiple ways to set a Smack label on a file::
+
+    # attr -S -s SMACK64 -V "value" path
+    # chsmack -a value path
+
+A process can see the Smack label it is running with by
+reading ``/proc/self/attr/current``. A process with ``CAP_MAC_ADMIN``
+can set the process Smack by writing there.
+
+Most Smack configuration is accomplished by writing to files
+in the smackfs filesystem. This pseudo-filesystem is mounted
+on ``/sys/fs/smackfs``.
+
+access
+	Provided for backward compatibility. The access2 interface
+	is preferred and should be used instead.
+	This interface reports whether a subject with the specified
+	Smack label has a particular access to an object with a
+	specified Smack label. Write a fixed format access rule to
+	this file. The next read will indicate whether the access
+	would be permitted. The text will be either "1" indicating
+	access, or "0" indicating denial.
+
+access2
+	This interface reports whether a subject with the specified
+	Smack label has a particular access to an object with a
+	specified Smack label. Write a long format access rule to
+	this file. The next read will indicate whether the access
+	would be permitted. The text will be either "1" indicating
+	access, or "0" indicating denial.
+
+ambient
+	This contains the Smack label applied to unlabeled network
+	packets.
+
+change-rule
+	This interface allows modification of existing access control rules.
+	The format accepted on write is::
+
+		"%s %s %s %s"
+
+	where the first string is the subject label, the second the
+	object label, the third the access to allow and the fourth the
+	access to deny. The access strings may contain only the characters
+	"rwxat-". If a rule for a given subject and object exists it will be
+	modified by enabling the permissions in the third string and disabling
+	those in the fourth string. If there is no such rule it will be
+	created using the access specified in the third and the fourth strings.
+
+cipso
+	Provided for backward compatibility. The cipso2 interface
+	is preferred and should be used instead.
+	This interface allows a specific CIPSO header to be assigned
+	to a Smack label. The format accepted on write is::
+
+		"%24s%4d%4d"["%4d"]...
+
+	The first string is a fixed Smack label. The first number is
+	the level to use. The second number is the number of categories.
+	The following numbers are the categories::
+
+		"level-3-cats-5-19          3   2   5  19"
+
+cipso2
+	This interface allows a specific CIPSO header to be assigned
+	to a Smack label. The format accepted on write is::
+
+		"%s%4d%4d"["%4d"]...
+
+	The first string is a long Smack label. The first number is
+	the level to use. The second number is the number of categories.
+	The following numbers are the categories::
+
+		"level-3-cats-5-19   3   2   5  19"
+
+direct
+	This contains the CIPSO level used for Smack direct label
+	representation in network packets.
+
+doi
+	This contains the CIPSO domain of interpretation used in
+	network packets.
+
+ipv6host
+	This interface allows specific IPv6 internet addresses to be
+	treated as single label hosts. Packets are sent to single
+	label hosts only from processes that have Smack write access
+	to the host label. All packets received from single label hosts
+	are given the specified label. The format accepted on write is::
+
+		"%h:%h:%h:%h:%h:%h:%h:%h label" or
+		"%h:%h:%h:%h:%h:%h:%h:%h/%d label".
+
+	The "::" address shortcut is not supported.
+	If label is "-DELETE" a matched entry will be deleted.
+
+load
+	Provided for backward compatibility. The load2 interface
+	is preferred and should be used instead.
+	This interface allows access control rules in addition to
+	the system defined rules to be specified. The format accepted
+	on write is::
+
+		"%24s%24s%5s"
+
+	where the first string is the subject label, the second the
+	object label, and the third the requested access. The access
+	string may contain only the characters "rwxat-", and specifies
+	which sort of access is allowed. The "-" is a placeholder for
+	permissions that are not allowed. The string "r-x--" would
+	specify read and execute access. Labels are limited to 23
+	characters in length.
+
+load2
+	This interface allows access control rules in addition to
+	the system defined rules to be specified. The format accepted
+	on write is::
+
+		"%s %s %s"
+
+	where the first string is the subject label, the second the
+	object label, and the third the requested access. The access
+	string may contain only the characters "rwxat-", and specifies
+	which sort of access is allowed. The "-" is a placeholder for
+	permissions that are not allowed. The string "r-x--" would
+	specify read and execute access.
+
+load-self
+	Provided for backward compatibility. The load-self2 interface
+	is preferred and should be used instead.
+	This interface allows process specific access rules to be
+	defined. These rules are only consulted if access would
+	otherwise be permitted, and are intended to provide additional
+	restrictions on the process. The format is the same as for
+	the load interface.
+
+load-self2
+	This interface allows process specific access rules to be
+	defined. These rules are only consulted if access would
+	otherwise be permitted, and are intended to provide additional
+	restrictions on the process. The format is the same as for
+	the load2 interface.
+
+logging
+	This contains the Smack logging state.
+
+mapped
+	This contains the CIPSO level used for Smack mapped label
+	representation in network packets.
+
+netlabel
+	This interface allows specific internet addresses to be
+	treated as single label hosts. Packets are sent to single
+	label hosts without CIPSO headers, but only from processes
+	that have Smack write access to the host label. All packets
+	received from single label hosts are given the specified
+	label. The format accepted on write is::
+
+		"%d.%d.%d.%d label" or "%d.%d.%d.%d/%d label".
+
+	If the label specified is "-CIPSO" the address is treated
+	as a host that supports CIPSO headers.
+
+onlycap
+	This contains labels processes must have for CAP_MAC_ADMIN
+	and ``CAP_MAC_OVERRIDE`` to be effective. If this file is empty
+	these capabilities are effective at for processes with any
+	label. The values are set by writing the desired labels, separated
+	by spaces, to the file or cleared by writing "-" to the file.
+
+ptrace
+	This is used to define the current ptrace policy
+
+	0 - default:
+	    this is the policy that relies on Smack access rules.
+	    For the ``PTRACE_READ`` a subject needs to have a read access on
+	    object. For the ``PTRACE_ATTACH`` a read-write access is required.
+
+	1 - exact:
+	    this is the policy that limits ``PTRACE_ATTACH``. Attach is
+	    only allowed when subject's and object's labels are equal.
+	    ``PTRACE_READ`` is not affected. Can be overridden with ``CAP_SYS_PTRACE``.
+
+	2 - draconian:
+	    this policy behaves like the 'exact' above with an
+	    exception that it can't be overridden with ``CAP_SYS_PTRACE``.
+
+revoke-subject
+	Writing a Smack label here sets the access to '-' for all access
+	rules with that subject label.
+
+unconfined
+	If the kernel is configured with ``CONFIG_SECURITY_SMACK_BRINGUP``
+	a process with ``CAP_MAC_ADMIN`` can write a label into this interface.
+	Thereafter, accesses that involve that label will be logged and
+	the access permitted if it wouldn't be otherwise. Note that this
+	is dangerous and can ruin the proper labeling of your system.
+	It should never be used in production.
+
+relabel-self
+	This interface contains a list of labels to which the process can
+	transition to, by writing to ``/proc/self/attr/current``.
+	Normally a process can change its own label to any legal value, but only
+	if it has ``CAP_MAC_ADMIN``. This interface allows a process without
+	``CAP_MAC_ADMIN`` to relabel itself to one of labels from predefined list.
+	A process without ``CAP_MAC_ADMIN`` can change its label only once. When it
+	does, this list will be cleared.
+	The values are set by writing the desired labels, separated
+	by spaces, to the file or cleared by writing "-" to the file.
+
+If you are using the smackload utility
+you can add access rules in ``/etc/smack/accesses``. They take the form::
+
+    subjectlabel objectlabel access
+
+access is a combination of the letters rwxatb which specify the
+kind of access permitted a subject with subjectlabel on an
+object with objectlabel. If there is no rule no access is allowed.
+
+Look for additional programs on http://schaufler-ca.com
+
+The Simplified Mandatory Access Control Kernel (Whitepaper)
+===========================================================
+
+Casey Schaufler
+casey@schaufler-ca.com
+
+Mandatory Access Control
+------------------------
+
+Computer systems employ a variety of schemes to constrain how information is
+shared among the people and services using the machine. Some of these schemes
+allow the program or user to decide what other programs or users are allowed
+access to pieces of data. These schemes are called discretionary access
+control mechanisms because the access control is specified at the discretion
+of the user. Other schemes do not leave the decision regarding what a user or
+program can access up to users or programs. These schemes are called mandatory
+access control mechanisms because you don't have a choice regarding the users
+or programs that have access to pieces of data.
+
+Bell & LaPadula
+---------------
+
+From the middle of the 1980's until the turn of the century Mandatory Access
+Control (MAC) was very closely associated with the Bell & LaPadula security
+model, a mathematical description of the United States Department of Defense
+policy for marking paper documents. MAC in this form enjoyed a following
+within the Capital Beltway and Scandinavian supercomputer centers but was
+often sited as failing to address general needs.
+
+Domain Type Enforcement
+-----------------------
+
+Around the turn of the century Domain Type Enforcement (DTE) became popular.
+This scheme organizes users, programs, and data into domains that are
+protected from each other. This scheme has been widely deployed as a component
+of popular Linux distributions. The administrative overhead required to
+maintain this scheme and the detailed understanding of the whole system
+necessary to provide a secure domain mapping leads to the scheme being
+disabled or used in limited ways in the majority of cases.
+
+Smack
+-----
+
+Smack is a Mandatory Access Control mechanism designed to provide useful MAC
+while avoiding the pitfalls of its predecessors. The limitations of Bell &
+LaPadula are addressed by providing a scheme whereby access can be controlled
+according to the requirements of the system and its purpose rather than those
+imposed by an arcane government policy. The complexity of Domain Type
+Enforcement and avoided by defining access controls in terms of the access
+modes already in use.
+
+Smack Terminology
+-----------------
+
+The jargon used to talk about Smack will be familiar to those who have dealt
+with other MAC systems and shouldn't be too difficult for the uninitiated to
+pick up. There are four terms that are used in a specific way and that are
+especially important:
+
+  Subject:
+	A subject is an active entity on the computer system.
+	On Smack a subject is a task, which is in turn the basic unit
+	of execution.
+
+  Object:
+	An object is a passive entity on the computer system.
+	On Smack files of all types, IPC, and tasks can be objects.
+
+  Access:
+	Any attempt by a subject to put information into or get
+	information from an object is an access.
+
+  Label:
+	Data that identifies the Mandatory Access Control
+	characteristics of a subject or an object.
+
+These definitions are consistent with the traditional use in the security
+community. There are also some terms from Linux that are likely to crop up:
+
+  Capability:
+	A task that possesses a capability has permission to
+	violate an aspect of the system security policy, as identified by
+	the specific capability. A task that possesses one or more
+	capabilities is a privileged task, whereas a task with no
+	capabilities is an unprivileged task.
+
+  Privilege:
+	A task that is allowed to violate the system security
+	policy is said to have privilege. As of this writing a task can
+	have privilege either by possessing capabilities or by having an
+	effective user of root.
+
+Smack Basics
+------------
+
+Smack is an extension to a Linux system. It enforces additional restrictions
+on what subjects can access which objects, based on the labels attached to
+each of the subject and the object.
+
+Labels
+~~~~~~
+
+Smack labels are ASCII character strings. They can be up to 255 characters
+long, but keeping them to twenty-three characters is recommended.
+Single character labels using special characters, that being anything
+other than a letter or digit, are reserved for use by the Smack development
+team. Smack labels are unstructured, case sensitive, and the only operation
+ever performed on them is comparison for equality. Smack labels cannot
+contain unprintable characters, the "/" (slash), the "\" (backslash), the "'"
+(quote) and '"' (double-quote) characters.
+Smack labels cannot begin with a '-'. This is reserved for special options.
+
+There are some predefined labels::
+
+	_ 	Pronounced "floor", a single underscore character.
+	^ 	Pronounced "hat", a single circumflex character.
+	* 	Pronounced "star", a single asterisk character.
+	? 	Pronounced "huh", a single question mark character.
+	@ 	Pronounced "web", a single at sign character.
+
+Every task on a Smack system is assigned a label. The Smack label
+of a process will usually be assigned by the system initialization
+mechanism.
+
+Access Rules
+~~~~~~~~~~~~
+
+Smack uses the traditional access modes of Linux. These modes are read,
+execute, write, and occasionally append. There are a few cases where the
+access mode may not be obvious. These include:
+
+  Signals:
+	A signal is a write operation from the subject task to
+	the object task.
+
+  Internet Domain IPC:
+	Transmission of a packet is considered a
+	write operation from the source task to the destination task.
+
+Smack restricts access based on the label attached to a subject and the label
+attached to the object it is trying to access. The rules enforced are, in
+order:
+
+	1. Any access requested by a task labeled "*" is denied.
+	2. A read or execute access requested by a task labeled "^"
+	   is permitted.
+	3. A read or execute access requested on an object labeled "_"
+	   is permitted.
+	4. Any access requested on an object labeled "*" is permitted.
+	5. Any access requested by a task on an object with the same
+	   label is permitted.
+	6. Any access requested that is explicitly defined in the loaded
+	   rule set is permitted.
+	7. Any other access is denied.
+
+Smack Access Rules
+~~~~~~~~~~~~~~~~~~
+
+With the isolation provided by Smack access separation is simple. There are
+many interesting cases where limited access by subjects to objects with
+different labels is desired. One example is the familiar spy model of
+sensitivity, where a scientist working on a highly classified project would be
+able to read documents of lower classifications and anything she writes will
+be "born" highly classified. To accommodate such schemes Smack includes a
+mechanism for specifying rules allowing access between labels.
+
+Access Rule Format
+~~~~~~~~~~~~~~~~~~
+
+The format of an access rule is::
+
+	subject-label object-label access
+
+Where subject-label is the Smack label of the task, object-label is the Smack
+label of the thing being accessed, and access is a string specifying the sort
+of access allowed. The access specification is searched for letters that
+describe access modes:
+
+	a: indicates that append access should be granted.
+	r: indicates that read access should be granted.
+	w: indicates that write access should be granted.
+	x: indicates that execute access should be granted.
+	t: indicates that the rule requests transmutation.
+	b: indicates that the rule should be reported for bring-up.
+
+Uppercase values for the specification letters are allowed as well.
+Access mode specifications can be in any order. Examples of acceptable rules
+are::
+
+	TopSecret Secret  rx
+	Secret    Unclass R
+	Manager   Game    x
+	User      HR      w
+	Snap      Crackle rwxatb
+	New       Old     rRrRr
+	Closed    Off     -
+
+Examples of unacceptable rules are::
+
+	Top Secret Secret     rx
+	Ace        Ace        r
+	Odd        spells     waxbeans
+
+Spaces are not allowed in labels. Since a subject always has access to files
+with the same label specifying a rule for that case is pointless. Only
+valid letters (rwxatbRWXATB) and the dash ('-') character are allowed in
+access specifications. The dash is a placeholder, so "a-r" is the same
+as "ar". A lone dash is used to specify that no access should be allowed.
+
+Applying Access Rules
+~~~~~~~~~~~~~~~~~~~~~
+
+The developers of Linux rarely define new sorts of things, usually importing
+schemes and concepts from other systems. Most often, the other systems are
+variants of Unix. Unix has many endearing properties, but consistency of
+access control models is not one of them. Smack strives to treat accesses as
+uniformly as is sensible while keeping with the spirit of the underlying
+mechanism.
+
+File system objects including files, directories, named pipes, symbolic links,
+and devices require access permissions that closely match those used by mode
+bit access. To open a file for reading read access is required on the file. To
+search a directory requires execute access. Creating a file with write access
+requires both read and write access on the containing directory. Deleting a
+file requires read and write access to the file and to the containing
+directory. It is possible that a user may be able to see that a file exists
+but not any of its attributes by the circumstance of having read access to the
+containing directory but not to the differently labeled file. This is an
+artifact of the file name being data in the directory, not a part of the file.
+
+If a directory is marked as transmuting (SMACK64TRANSMUTE=TRUE) and the
+access rule that allows a process to create an object in that directory
+includes 't' access the label assigned to the new object will be that
+of the directory, not the creating process. This makes it much easier
+for two processes with different labels to share data without granting
+access to all of their files.
+
+IPC objects, message queues, semaphore sets, and memory segments exist in flat
+namespaces and access requests are only required to match the object in
+question.
+
+Process objects reflect tasks on the system and the Smack label used to access
+them is the same Smack label that the task would use for its own access
+attempts. Sending a signal via the kill() system call is a write operation
+from the signaler to the recipient. Debugging a process requires both reading
+and writing. Creating a new task is an internal operation that results in two
+tasks with identical Smack labels and requires no access checks.
+
+Sockets are data structures attached to processes and sending a packet from
+one process to another requires that the sender have write access to the
+receiver. The receiver is not required to have read access to the sender.
+
+Setting Access Rules
+~~~~~~~~~~~~~~~~~~~~
+
+The configuration file /etc/smack/accesses contains the rules to be set at
+system startup. The contents are written to the special file
+/sys/fs/smackfs/load2. Rules can be added at any time and take effect
+immediately. For any pair of subject and object labels there can be only
+one rule, with the most recently specified overriding any earlier
+specification.
+
+Task Attribute
+~~~~~~~~~~~~~~
+
+The Smack label of a process can be read from ``/proc/<pid>/attr/current``. A
+process can read its own Smack label from ``/proc/self/attr/current``. A
+privileged process can change its own Smack label by writing to
+``/proc/self/attr/current`` but not the label of another process.
+
+Format of writing is : only the label or the label followed by one of the
+3 trailers: ``\n`` (by common agreement for ``/proc/...`` interfaces),
+``\0`` (because some applications incorrectly include it),
+``\n\0`` (because we think some applications may incorrectly include it).
+
+File Attribute
+~~~~~~~~~~~~~~
+
+The Smack label of a filesystem object is stored as an extended attribute
+named SMACK64 on the file. This attribute is in the security namespace. It can
+only be changed by a process with privilege.
+
+Privilege
+~~~~~~~~~
+
+A process with CAP_MAC_OVERRIDE or CAP_MAC_ADMIN is privileged.
+CAP_MAC_OVERRIDE allows the process access to objects it would
+be denied otherwise. CAP_MAC_ADMIN allows a process to change
+Smack data, including rules and attributes.
+
+Smack Networking
+~~~~~~~~~~~~~~~~
+
+As mentioned before, Smack enforces access control on network protocol
+transmissions. Every packet sent by a Smack process is tagged with its Smack
+label. This is done by adding a CIPSO tag to the header of the IP packet. Each
+packet received is expected to have a CIPSO tag that identifies the label and
+if it lacks such a tag the network ambient label is assumed. Before the packet
+is delivered a check is made to determine that a subject with the label on the
+packet has write access to the receiving process and if that is not the case
+the packet is dropped.
+
+CIPSO Configuration
+~~~~~~~~~~~~~~~~~~~
+
+It is normally unnecessary to specify the CIPSO configuration. The default
+values used by the system handle all internal cases. Smack will compose CIPSO
+label values to match the Smack labels being used without administrative
+intervention. Unlabeled packets that come into the system will be given the
+ambient label.
+
+Smack requires configuration in the case where packets from a system that is
+not Smack that speaks CIPSO may be encountered. Usually this will be a Trusted
+Solaris system, but there are other, less widely deployed systems out there.
+CIPSO provides 3 important values, a Domain Of Interpretation (DOI), a level,
+and a category set with each packet. The DOI is intended to identify a group
+of systems that use compatible labeling schemes, and the DOI specified on the
+Smack system must match that of the remote system or packets will be
+discarded. The DOI is 3 by default. The value can be read from
+/sys/fs/smackfs/doi and can be changed by writing to /sys/fs/smackfs/doi.
+
+The label and category set are mapped to a Smack label as defined in
+/etc/smack/cipso.
+
+A Smack/CIPSO mapping has the form::
+
+	smack level [category [category]*]
+
+Smack does not expect the level or category sets to be related in any
+particular way and does not assume or assign accesses based on them. Some
+examples of mappings::
+
+	TopSecret 7
+	TS:A,B    7 1 2
+	SecBDE    5 2 4 6
+	RAFTERS   7 12 26
+
+The ":" and "," characters are permitted in a Smack label but have no special
+meaning.
+
+The mapping of Smack labels to CIPSO values is defined by writing to
+/sys/fs/smackfs/cipso2.
+
+In addition to explicit mappings Smack supports direct CIPSO mappings. One
+CIPSO level is used to indicate that the category set passed in the packet is
+in fact an encoding of the Smack label. The level used is 250 by default. The
+value can be read from /sys/fs/smackfs/direct and changed by writing to
+/sys/fs/smackfs/direct.
+
+Socket Attributes
+~~~~~~~~~~~~~~~~~
+
+There are two attributes that are associated with sockets. These attributes
+can only be set by privileged tasks, but any task can read them for their own
+sockets.
+
+  SMACK64IPIN:
+	The Smack label of the task object. A privileged
+	program that will enforce policy may set this to the star label.
+
+  SMACK64IPOUT:
+	The Smack label transmitted with outgoing packets.
+	A privileged program may set this to match the label of another
+	task with which it hopes to communicate.
+
+UNIX domain socket (UDS) with a BSD address functions both as a file in a
+filesystem and as a socket. As a file, it carries the SMACK64 attribute. This
+attribute is not involved in Smack security enforcement and is immutably
+assigned the label "*".
+
+Smack Netlabel Exceptions
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You will often find that your labeled application has to talk to the outside,
+unlabeled world. To do this there's a special file /sys/fs/smackfs/netlabel
+where you can add some exceptions in the form of::
+
+	@IP1	   LABEL1 or
+	@IP2/MASK  LABEL2
+
+It means that your application will have unlabeled access to @IP1 if it has
+write access on LABEL1, and access to the subnet @IP2/MASK if it has write
+access on LABEL2.
+
+Entries in the /sys/fs/smackfs/netlabel file are matched by longest mask
+first, like in classless IPv4 routing.
+
+A special label '@' and an option '-CIPSO' can be used there::
+
+	@      means Internet, any application with any label has access to it
+	-CIPSO means standard CIPSO networking
+
+If you don't know what CIPSO is and don't plan to use it, you can just do::
+
+	echo 127.0.0.1 -CIPSO > /sys/fs/smackfs/netlabel
+	echo 0.0.0.0/0 @      > /sys/fs/smackfs/netlabel
+
+If you use CIPSO on your 192.168.0.0/16 local network and need also unlabeled
+Internet access, you can have::
+
+	echo 127.0.0.1      -CIPSO > /sys/fs/smackfs/netlabel
+	echo 192.168.0.0/16 -CIPSO > /sys/fs/smackfs/netlabel
+	echo 0.0.0.0/0      @      > /sys/fs/smackfs/netlabel
+
+Writing Applications for Smack
+------------------------------
+
+There are three sorts of applications that will run on a Smack system. How an
+application interacts with Smack will determine what it will have to do to
+work properly under Smack.
+
+Smack Ignorant Applications
+---------------------------
+
+By far the majority of applications have no reason whatever to care about the
+unique properties of Smack. Since invoking a program has no impact on the
+Smack label associated with the process the only concern likely to arise is
+whether the process has execute access to the program.
+
+Smack Relevant Applications
+---------------------------
+
+Some programs can be improved by teaching them about Smack, but do not make
+any security decisions themselves. The utility ls(1) is one example of such a
+program.
+
+Smack Enforcing Applications
+----------------------------
+
+These are special programs that not only know about Smack, but participate in
+the enforcement of system policy. In most cases these are the programs that
+set up user sessions. There are also network services that provide information
+to processes running with various labels.
+
+File System Interfaces
+----------------------
+
+Smack maintains labels on file system objects using extended attributes. The
+Smack label of a file, directory, or other file system object can be obtained
+using getxattr(2)::
+
+	len = getxattr("/", "security.SMACK64", value, sizeof (value));
+
+will put the Smack label of the root directory into value. A privileged
+process can set the Smack label of a file system object with setxattr(2)::
+
+	len = strlen("Rubble");
+	rc = setxattr("/foo", "security.SMACK64", "Rubble", len, 0);
+
+will set the Smack label of /foo to "Rubble" if the program has appropriate
+privilege.
+
+Socket Interfaces
+-----------------
+
+The socket attributes can be read using fgetxattr(2).
+
+A privileged process can set the Smack label of outgoing packets with
+fsetxattr(2)::
+
+	len = strlen("Rubble");
+	rc = fsetxattr(fd, "security.SMACK64IPOUT", "Rubble", len, 0);
+
+will set the Smack label "Rubble" on packets going out from the socket if the
+program has appropriate privilege::
+
+	rc = fsetxattr(fd, "security.SMACK64IPIN, "*", strlen("*"), 0);
+
+will set the Smack label "*" as the object label against which incoming
+packets will be checked if the program has appropriate privilege.
+
+Administration
+--------------
+
+Smack supports some mount options:
+
+  smackfsdef=label:
+	specifies the label to give files that lack
+	the Smack label extended attribute.
+
+  smackfsroot=label:
+	specifies the label to assign the root of the
+	file system if it lacks the Smack extended attribute.
+
+  smackfshat=label:
+	specifies a label that must have read access to
+	all labels set on the filesystem. Not yet enforced.
+
+  smackfsfloor=label:
+	specifies a label to which all labels set on the
+	filesystem must have read access. Not yet enforced.
+
+  smackfstransmute=label:
+	behaves exactly like smackfsroot except that it also
+	sets the transmute flag on the root of the mount
+
+These mount options apply to all file system types.
+
+Smack auditing
+--------------
+
+If you want Smack auditing of security events, you need to set CONFIG_AUDIT
+in your kernel configuration.
+By default, all denied events will be audited. You can change this behavior by
+writing a single character to the /sys/fs/smackfs/logging file::
+
+	0 : no logging
+	1 : log denied (default)
+	2 : log accepted
+	3 : log denied & accepted
+
+Events are logged as 'key=value' pairs, for each event you at least will get
+the subject, the object, the rights requested, the action, the kernel function
+that triggered the event, plus other pairs depending on the type of event
+audited.
+
+Bringup Mode
+------------
+
+Bringup mode provides logging features that can make application
+configuration and system bringup easier. Configure the kernel with
+CONFIG_SECURITY_SMACK_BRINGUP to enable these features. When bringup
+mode is enabled accesses that succeed due to rules marked with the "b"
+access mode will logged. When a new label is introduced for processes
+rules can be added aggressively, marked with the "b". The logging allows
+tracking of which rules actual get used for that label.
+
+Another feature of bringup mode is the "unconfined" option. Writing
+a label to /sys/fs/smackfs/unconfined makes subjects with that label
+able to access any object, and objects with that label accessible to
+all subjects. Any access that is granted because a label is unconfined
+is logged. This feature is dangerous, as files and directories may
+be created in places they couldn't if the policy were being enforced.
diff --git a/Documentation/admin-guide/LSM/Yama.rst b/Documentation/admin-guide/LSM/Yama.rst
new file mode 100644
index 000000000..d9cd937eb
--- /dev/null
+++ b/Documentation/admin-guide/LSM/Yama.rst
@@ -0,0 +1,75 @@
+====
+Yama
+====
+
+Yama is a Linux Security Module that collects system-wide DAC security
+protections that are not handled by the core kernel itself. This is
+selectable at build-time with ``CONFIG_SECURITY_YAMA``, and can be controlled
+at run-time through sysctls in ``/proc/sys/kernel/yama``:
+
+ptrace_scope
+============
+
+As Linux grows in popularity, it will become a larger target for
+malware. One particularly troubling weakness of the Linux process
+interfaces is that a single user is able to examine the memory and
+running state of any of their processes. For example, if one application
+(e.g. Pidgin) was compromised, it would be possible for an attacker to
+attach to other running processes (e.g. Firefox, SSH sessions, GPG agent,
+etc) to extract additional credentials and continue to expand the scope
+of their attack without resorting to user-assisted phishing.
+
+This is not a theoretical problem. `SSH session hijacking
+<https://www.blackhat.com/presentations/bh-usa-05/bh-us-05-boileau.pdf>`_
+and `arbitrary code injection
+<https://c-skills.blogspot.com/2007/05/injectso.html>`_ attacks already
+exist and remain possible if ptrace is allowed to operate as before.
+Since ptrace is not commonly used by non-developers and non-admins, system
+builders should be allowed the option to disable this debugging system.
+
+For a solution, some applications use ``prctl(PR_SET_DUMPABLE, ...)`` to
+specifically disallow such ptrace attachment (e.g. ssh-agent), but many
+do not. A more general solution is to only allow ptrace directly from a
+parent to a child process (i.e. direct "gdb EXE" and "strace EXE" still
+work), or with ``CAP_SYS_PTRACE`` (i.e. "gdb --pid=PID", and "strace -p PID"
+still work as root).
+
+In mode 1, software that has defined application-specific relationships
+between a debugging process and its inferior (crash handlers, etc),
+``prctl(PR_SET_PTRACER, pid, ...)`` can be used. An inferior can declare which
+other process (and its descendants) are allowed to call ``PTRACE_ATTACH``
+against it. Only one such declared debugging process can exists for
+each inferior at a time. For example, this is used by KDE, Chromium, and
+Firefox's crash handlers, and by Wine for allowing only Wine processes
+to ptrace each other. If a process wishes to entirely disable these ptrace
+restrictions, it can call ``prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, ...)``
+so that any otherwise allowed process (even those in external pid namespaces)
+may attach.
+
+The sysctl settings (writable only with ``CAP_SYS_PTRACE``) are:
+
+0 - classic ptrace permissions:
+    a process can ``PTRACE_ATTACH`` to any other
+    process running under the same uid, as long as it is dumpable (i.e.
+    did not transition uids, start privileged, or have called
+    ``prctl(PR_SET_DUMPABLE...)`` already). Similarly, ``PTRACE_TRACEME`` is
+    unchanged.
+
+1 - restricted ptrace:
+    a process must have a predefined relationship
+    with the inferior it wants to call ``PTRACE_ATTACH`` on. By default,
+    this relationship is that of only its descendants when the above
+    classic criteria is also met. To change the relationship, an
+    inferior can call ``prctl(PR_SET_PTRACER, debugger, ...)`` to declare
+    an allowed debugger PID to call ``PTRACE_ATTACH`` on the inferior.
+    Using ``PTRACE_TRACEME`` is unchanged.
+
+2 - admin-only attach:
+    only processes with ``CAP_SYS_PTRACE`` may use ptrace, either with
+    ``PTRACE_ATTACH`` or through children calling ``PTRACE_TRACEME``.
+
+3 - no attach:
+    no processes may use ptrace with ``PTRACE_ATTACH`` nor via
+    ``PTRACE_TRACEME``. Once set, this sysctl value cannot be changed.
+
+The original children-only logic was based on the restrictions in grsecurity.
diff --git a/Documentation/admin-guide/LSM/apparmor.rst b/Documentation/admin-guide/LSM/apparmor.rst
new file mode 100644
index 000000000..47939ee89
--- /dev/null
+++ b/Documentation/admin-guide/LSM/apparmor.rst
@@ -0,0 +1,54 @@
+========
+AppArmor
+========
+
+What is AppArmor?
+=================
+
+AppArmor is MAC style security extension for the Linux kernel.  It implements
+a task centered policy, with task "profiles" being created and loaded
+from user space.  Tasks on the system that do not have a profile defined for
+them run in an unconfined state which is equivalent to standard Linux DAC
+permissions.
+
+How to enable/disable
+=====================
+
+set ``CONFIG_SECURITY_APPARMOR=y``
+
+If AppArmor should be selected as the default security module then set::
+
+   CONFIG_DEFAULT_SECURITY_APPARMOR=y
+
+The CONFIG_LSM parameter manages the order and selection of LSMs.
+Specify apparmor as the first "major" module (e.g. AppArmor, SELinux, Smack)
+in the list.
+
+Build the kernel
+
+If AppArmor is not the default security module it can be enabled by passing
+``security=apparmor`` on the kernel's command line.
+
+If AppArmor is the default security module it can be disabled by passing
+``apparmor=0, security=XXXX`` (where ``XXXX`` is valid security module), on the
+kernel's command line.
+
+For AppArmor to enforce any restrictions beyond standard Linux DAC permissions
+policy must be loaded into the kernel from user space (see the Documentation
+and tools links).
+
+Documentation
+=============
+
+Documentation can be found on the wiki, linked below.
+
+Links
+=====
+
+Mailing List - apparmor@lists.ubuntu.com
+
+Wiki - http://wiki.apparmor.net
+
+User space tools - https://gitlab.com/apparmor
+
+Kernel module - git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor
diff --git a/Documentation/admin-guide/LSM/index.rst b/Documentation/admin-guide/LSM/index.rst
new file mode 100644
index 000000000..b44ef68f6
--- /dev/null
+++ b/Documentation/admin-guide/LSM/index.rst
@@ -0,0 +1,51 @@
+===========================
+Linux Security Module Usage
+===========================
+
+The Linux Security Module (LSM) framework provides a mechanism for
+various security checks to be hooked by new kernel extensions. The name
+"module" is a bit of a misnomer since these extensions are not actually
+loadable kernel modules. Instead, they are selectable at build-time via
+CONFIG_DEFAULT_SECURITY and can be overridden at boot-time via the
+``"security=..."`` kernel command line argument, in the case where multiple
+LSMs were built into a given kernel.
+
+The primary users of the LSM interface are Mandatory Access Control
+(MAC) extensions which provide a comprehensive security policy. Examples
+include SELinux, Smack, Tomoyo, and AppArmor. In addition to the larger
+MAC extensions, other extensions can be built using the LSM to provide
+specific changes to system operation when these tweaks are not available
+in the core functionality of Linux itself.
+
+The Linux capabilities modules will always be included. This may be
+followed by any number of "minor" modules and at most one "major" module.
+For more details on capabilities, see ``capabilities(7)`` in the Linux
+man-pages project.
+
+A list of the active security modules can be found by reading
+``/sys/kernel/security/lsm``. This is a comma separated list, and
+will always include the capability module. The list reflects the
+order in which checks are made. The capability module will always
+be first, followed by any "minor" modules (e.g. Yama) and then
+the one "major" module (e.g. SELinux) if there is one configured.
+
+Process attributes associated with "major" security modules should
+be accessed and maintained using the special files in ``/proc/.../attr``.
+A security module may maintain a module specific subdirectory there,
+named after the module. ``/proc/.../attr/smack`` is provided by the Smack
+security module and contains all its special files. The files directly
+in ``/proc/.../attr`` remain as legacy interfaces for modules that provide
+subdirectories.
+
+.. toctree::
+   :maxdepth: 1
+
+   apparmor
+   LoadPin
+   SELinux
+   Smack
+   tomoyo
+   Yama
+   SafeSetID
+   ipe
+   landlock
diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst
new file mode 100644
index 000000000..a756d8158
--- /dev/null
+++ b/Documentation/admin-guide/LSM/ipe.rst
@@ -0,0 +1,835 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Integrity Policy Enforcement (IPE)
+==================================
+
+.. NOTE::
+
+   This is the documentation for admins, system builders, or individuals
+   attempting to use IPE. If you're looking for more developer-focused
+   documentation about IPE please see :doc:`the design docs </security/ipe>`.
+
+Overview
+--------
+
+Integrity Policy Enforcement (IPE) is a Linux Security Module that takes a
+complementary approach to access control. Unlike traditional access control
+mechanisms that rely on labels and paths for decision-making, IPE focuses
+on the immutable security properties inherent to system components. These
+properties are fundamental attributes or features of a system component
+that cannot be altered, ensuring a consistent and reliable basis for
+security decisions.
+
+To elaborate, in the context of IPE, system components primarily refer to
+files or the devices these files reside on. However, this is just a
+starting point. The concept of system components is flexible and can be
+extended to include new elements as the system evolves. The immutable
+properties include the origin of a file, which remains constant and
+unchangeable over time. For example, IPE policies can be crafted to trust
+files originating from the initramfs. Since initramfs is typically verified
+by the bootloader, its files are deemed trustworthy; "file is from
+initramfs" becomes an immutable property under IPE's consideration.
+
+The immutable property concept extends to the security features enabled on
+a file's origin, such as dm-verity or fs-verity, which provide a layer of
+integrity and trust. For example, IPE allows the definition of policies
+that trust files from a dm-verity protected device. dm-verity ensures the
+integrity of an entire device by providing a verifiable and immutable state
+of its contents. Similarly, fs-verity offers filesystem-level integrity
+checks, allowing IPE to enforce policies that trust files protected by
+fs-verity. These two features cannot be turned off once established, so
+they are considered immutable properties. These examples demonstrate how
+IPE leverages immutable properties, such as a file's origin and its
+integrity protection mechanisms, to make access control decisions.
+
+For the IPE policy, specifically, it grants the ability to enforce
+stringent access controls by assessing security properties against
+reference values defined within the policy. This assessment can be based on
+the existence of a security property (e.g., verifying if a file originates
+from initramfs) or evaluating the internal state of an immutable security
+property. The latter includes checking the roothash of a dm-verity
+protected device, determining whether dm-verity possesses a valid
+signature, assessing the digest of a fs-verity protected file, or
+determining whether fs-verity possesses a valid built-in signature. This
+nuanced approach to policy enforcement enables a highly secure and
+customizable system defense mechanism, tailored to specific security
+requirements and trust models.
+
+To enable IPE, ensure that ``CONFIG_SECURITY_IPE`` (under
+:menuselection:`Security -> Integrity Policy Enforcement (IPE)`) config
+option is enabled.
+
+Use Cases
+---------
+
+IPE works best in fixed-function devices: devices in which their purpose
+is clearly defined and not supposed to be changed (e.g. network firewall
+device in a data center, an IoT device, etcetera), where all software and
+configuration is built and provisioned by the system owner.
+
+IPE is a long-way off for use in general-purpose computing: the Linux
+community as a whole tends to follow a decentralized trust model (known as
+the web of trust), which IPE has no support for it yet. Instead, IPE
+supports PKI (public key infrastructure), which generally designates a
+set of trusted entities that provide a measure of absolute trust.
+
+Additionally, while most packages are signed today, the files inside
+the packages (for instance, the executables), tend to be unsigned. This
+makes it difficult to utilize IPE in systems where a package manager is
+expected to be functional, without major changes to the package manager
+and ecosystem behind it.
+
+The digest_cache LSM [#digest_cache_lsm]_ is a system that when combined with IPE,
+could be used to enable and support general-purpose computing use cases.
+
+Known Limitations
+-----------------
+
+IPE cannot verify the integrity of anonymous executable memory, such as
+the trampolines created by gcc closures and libffi (<3.4.2), or JIT'd code.
+Unfortunately, as this is dynamically generated code, there is no way
+for IPE to ensure the integrity of this code to form a trust basis.
+
+IPE cannot verify the integrity of programs written in interpreted
+languages when these scripts are invoked by passing these program files
+to the interpreter. This is because the way interpreters execute these
+files; the scripts themselves are not evaluated as executable code
+through one of IPE's hooks, but they are merely text files that are read
+(as opposed to compiled executables). However, with the introduction of the
+``AT_EXECVE_CHECK`` flag (:doc:`AT_EXECVE_CHECK </userspace-api/check_exec>`),
+interpreters can use it to signal the kernel that a script file will be executed,
+and request the kernel to perform LSM security checks on it.
+
+IPE's EXECUTE operation enforcement differs between compiled executables and
+interpreted scripts: For compiled executables, enforcement is triggered
+automatically by the kernel during ``execve()``, ``execveat()``, ``mmap()``
+and ``mprotect()`` syscalls when loading executable content. For interpreted
+scripts, enforcement requires explicit interpreter integration using
+``execveat()`` with ``AT_EXECVE_CHECK`` flag. Unlike exec syscalls that IPE
+intercepts during the execution process, this mechanism needs the interpreter
+to take the initiative, and existing interpreters won't be automatically
+supported unless the signal call is added.
+
+Threat Model
+------------
+
+IPE specifically targets the risk of tampering with user-space executable
+code after the kernel has initially booted, including the kernel modules
+loaded from userspace via ``modprobe`` or ``insmod``.
+
+To illustrate, consider a scenario where an untrusted binary, possibly
+malicious, is downloaded along with all necessary dependencies, including a
+loader and libc. The primary function of IPE in this context is to prevent
+the execution of such binaries and their dependencies.
+
+IPE achieves this by verifying the integrity and authenticity of all
+executable code before allowing them to run. It conducts a thorough
+check to ensure that the code's integrity is intact and that they match an
+authorized reference value (digest, signature, etc) as per the defined
+policy. If a binary does not pass this verification process, either
+because its integrity has been compromised or it does not meet the
+authorization criteria, IPE will deny its execution. Additionally, IPE
+generates audit logs which may be utilized to detect and analyze failures
+resulting from policy violation.
+
+Tampering threat scenarios include modification or replacement of
+executable code by a range of actors including:
+
+-  Actors with physical access to the hardware
+-  Actors with local network access to the system
+-  Actors with access to the deployment system
+-  Compromised internal systems under external control
+-  Malicious end users of the system
+-  Compromised end users of the system
+-  Remote (external) compromise of the system
+
+IPE does not mitigate threats arising from malicious but authorized
+developers (with access to a signing certificate), or compromised
+developer tools used by them (i.e. return-oriented programming attacks).
+Additionally, IPE draws hard security boundary between userspace and
+kernelspace. As a result, kernel-level exploits are considered outside
+the scope of IPE and mitigation is left to other mechanisms.
+
+Policy
+------
+
+IPE policy is a plain-text [#devdoc]_ policy composed of multiple statements
+over several lines. There is one required line, at the top of the
+policy, indicating the policy name, and the policy version, for
+instance::
+
+   policy_name=Ex_Policy policy_version=0.0.0
+
+The policy name is a unique key identifying this policy in a human
+readable name. This is used to create nodes under securityfs as well as
+uniquely identify policies to deploy new policies vs update existing
+policies.
+
+The policy version indicates the current version of the policy (NOT the
+policy syntax version). This is used to prevent rollback of policy to
+potentially insecure previous versions of the policy.
+
+The next portion of IPE policy are rules. Rules are formed by key=value
+pairs, known as properties. IPE rules require two properties: ``action``,
+which determines what IPE does when it encounters a match against the
+rule, and ``op``, which determines when the rule should be evaluated.
+The ordering is significant, a rule must start with ``op``, and end with
+``action``. Thus, a minimal rule is::
+
+   op=EXECUTE action=ALLOW
+
+This example will allow any execution. Additional properties are used to
+assess immutable security properties about the files being evaluated.
+These properties are intended to be descriptions of systems within the
+kernel that can provide a measure of integrity verification, such that IPE
+can determine the trust of the resource based on the value of the property.
+
+Rules are evaluated top-to-bottom. As a result, any revocation rules,
+or denies should be placed early in the file to ensure that these rules
+are evaluated before a rule with ``action=ALLOW``.
+
+IPE policy supports comments. The character '#' will function as a
+comment, ignoring all characters to the right of '#' until the newline.
+
+The default behavior of IPE evaluations can also be expressed in policy,
+through the ``DEFAULT`` statement. This can be done at a global level,
+or a per-operation level::
+
+   # Global
+   DEFAULT action=ALLOW
+
+   # Operation Specific
+   DEFAULT op=EXECUTE action=ALLOW
+
+A default must be set for all known operations in IPE. If you want to
+preserve older policies being compatible with newer kernels that can introduce
+new operations, set a global default of ``ALLOW``, then override the
+defaults on a per-operation basis (as above).
+
+With configurable policy-based LSMs, there's several issues with
+enforcing the configurable policies at startup, around reading and
+parsing the policy:
+
+1. The kernel *should* not read files from userspace, so directly reading
+   the policy file is prohibited.
+2. The kernel command line has a character limit, and one kernel module
+   should not reserve the entire character limit for its own
+   configuration.
+3. There are various boot loaders in the kernel ecosystem, so handing
+   off a memory block would be costly to maintain.
+
+As a result, IPE has addressed this problem through a concept of a "boot
+policy". A boot policy is a minimal policy which is compiled into the
+kernel. This policy is intended to get the system to a state where
+userspace is set up and ready to receive commands, at which point a more
+complex policy can be deployed via securityfs. The boot policy can be
+specified via ``SECURITY_IPE_BOOT_POLICY`` config option, which accepts
+a path to a plain-text version of the IPE policy to apply. This policy
+will be compiled into the kernel. If not specified, IPE will be disabled
+until a policy is deployed and activated through securityfs.
+
+Deploying Policies
+~~~~~~~~~~~~~~~~~~
+
+Policies can be deployed from userspace through securityfs. These policies
+are signed through the PKCS#7 message format to enforce some level of
+authorization of the policies (prohibiting an attacker from gaining
+unconstrained root, and deploying an "allow all" policy). These
+policies must be signed by a certificate that chains to the
+``SYSTEM_TRUSTED_KEYRING``, or to the secondary and/or platform keyrings if
+``CONFIG_IPE_POLICY_SIG_SECONDARY_KEYRING`` and/or
+``CONFIG_IPE_POLICY_SIG_PLATFORM_KEYRING`` are enabled, respectively.
+With openssl, the policy can be signed by::
+
+   openssl smime -sign \
+      -in "$MY_POLICY" \
+      -signer "$MY_CERTIFICATE" \
+      -inkey "$MY_PRIVATE_KEY" \
+      -noattr \
+      -nodetach \
+      -nosmimecap \
+      -outform der \
+      -out "$MY_POLICY.p7b"
+
+Deploying the policies is done through securityfs, through the
+``new_policy`` node. To deploy a policy, simply cat the file into the
+securityfs node::
+
+   cat "$MY_POLICY.p7b" > /sys/kernel/security/ipe/new_policy
+
+Upon success, this will create one subdirectory under
+``/sys/kernel/security/ipe/policies/``. The subdirectory will be the
+``policy_name`` field of the policy deployed, so for the example above,
+the directory will be ``/sys/kernel/security/ipe/policies/Ex_Policy``.
+Within this directory, there will be seven files: ``pkcs7``, ``policy``,
+``name``, ``version``, ``active``, ``update``, and ``delete``.
+
+The ``pkcs7`` file is read-only. Reading it returns the raw PKCS#7 data
+that was provided to the kernel, representing the policy. If the policy being
+read is the boot policy, this will return ``ENOENT``, as it is not signed.
+
+The ``policy`` file is read only. Reading it returns the PKCS#7 inner
+content of the policy, which will be the plain text policy.
+
+The ``active`` file is used to set a policy as the currently active policy.
+This file is rw, and accepts a value of ``"1"`` to set the policy as active.
+Since only a single policy can be active at one time, all other policies
+will be marked inactive. The policy being marked active must have a policy
+version greater or equal to the currently-running version.
+
+The ``update`` file is used to update a policy that is already present
+in the kernel. This file is write-only and accepts a PKCS#7 signed
+policy. Two checks will always be performed on this policy: First, the
+``policy_names`` must match with the updated version and the existing
+version. Second the updated policy must have a policy version greater than
+the currently-running version. This is to prevent rollback attacks.
+
+The ``delete`` file is used to remove a policy that is no longer needed.
+This file is write-only and accepts a value of ``1`` to delete the policy.
+On deletion, the securityfs node representing the policy will be removed.
+However, delete the current active policy is not allowed and will return
+an operation not permitted error.
+
+Similarly, writing to both ``update`` and ``new_policy`` could result in
+bad message(policy syntax error) or file exists error. The latter error happens
+when trying to deploy a policy with a ``policy_name`` while the kernel already
+has a deployed policy with the same ``policy_name``.
+
+Deploying a policy will *not* cause IPE to start enforcing the policy. IPE will
+only enforce the policy marked active. Note that only one policy can be active
+at a time.
+
+Once deployment is successful, the policy can be activated, by writing file
+``/sys/kernel/security/ipe/policies/$policy_name/active``.
+For example, the ``Ex_Policy`` can be activated by::
+
+   echo 1 > "/sys/kernel/security/ipe/policies/Ex_Policy/active"
+
+From above point on, ``Ex_Policy`` is now the enforced policy on the
+system.
+
+IPE also provides a way to delete policies. This can be done via the
+``delete`` securityfs node,
+``/sys/kernel/security/ipe/policies/$policy_name/delete``.
+Writing ``1`` to that file deletes the policy::
+
+   echo 1 > "/sys/kernel/security/ipe/policies/$policy_name/delete"
+
+There is only one requirement to delete a policy: the policy being deleted
+must be inactive.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack), all
+   writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Modes
+~~~~~
+
+IPE supports two modes of operation: permissive (similar to SELinux's
+permissive mode) and enforced. In permissive mode, all events are
+checked and policy violations are logged, but the policy is not really
+enforced. This allows users to test policies before enforcing them.
+
+The default mode is enforce, and can be changed via the kernel command
+line parameter ``ipe.enforce=(0|1)``, or the securityfs node
+``/sys/kernel/security/ipe/enforce``.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
+   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Audit Events
+~~~~~~~~~~~~
+
+1420 AUDIT_IPE_ACCESS
+^^^^^^^^^^^^^^^^^^^^^
+Event Examples::
+
+   type=1420 audit(1653364370.067:61): ipe_op=EXECUTE ipe_hook=MMAP enforcing=1 pid=2241 comm="ld-linux.so" path="/deny/lib/libc.so.6" dev="sda2" ino=14549020 rule="DEFAULT action=DENY"
+   type=1300 audit(1653364370.067:61): SYSCALL arch=c000003e syscall=9 success=no exit=-13 a0=7f1105a28000 a1=195000 a2=5 a3=812 items=0 ppid=2219 pid=2241 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=2 comm="ld-linux.so" exe="/tmp/ipe-test/lib/ld-linux.so" subj=unconfined key=(null)
+   type=1327 audit(1653364370.067:61): 707974686F6E3300746573742F6D61696E2E7079002D6E00
+
+   type=1420 audit(1653364735.161:64): ipe_op=EXECUTE ipe_hook=MMAP enforcing=1 pid=2472 comm="mmap_test" path=? dev=? ino=? rule="DEFAULT action=DENY"
+   type=1300 audit(1653364735.161:64): SYSCALL arch=c000003e syscall=9 success=no exit=-13 a0=0 a1=1000 a2=4 a3=21 items=0 ppid=2219 pid=2472 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=2 comm="mmap_test" exe="/root/overlake_test/upstream_test/vol_fsverity/bin/mmap_test" subj=unconfined key=(null)
+   type=1327 audit(1653364735.161:64): 707974686F6E3300746573742F6D61696E2E7079002D6E00
+
+This event indicates that IPE made an access control decision; the IPE
+specific record (1420) is always emitted in conjunction with a
+``AUDITSYSCALL`` record.
+
+Determining whether IPE is in permissive or enforced mode can be derived
+from ``success`` property and exit code of the ``AUDITSYSCALL`` record.
+
+
+Field descriptions:
+
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| Field     | Value Type | Optional? | Description of Value                                                            |
++===========+============+===========+=================================================================================+
+| ipe_op    | string     | No        | The IPE operation name associated with the log                                  |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| ipe_hook  | string     | No        | The name of the LSM hook that triggered the IPE event                           |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| enforcing | integer    | No        | The current IPE enforcing state 1 is in enforcing mode, 0 is in permissive mode |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| pid       | integer    | No        | The pid of the process that triggered the IPE event.                            |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| comm      | string     | No        | The command line program name of the process that triggered the IPE event       |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| path      | string     | Yes       | The absolute path to the evaluated file                                         |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| ino       | integer    | Yes       | The inode number of the evaluated file                                          |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| dev       | string     | Yes       | The device name of the evaluated file, e.g. vda                                 |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+| rule      | string     | No        | The matched policy rule                                                         |
++-----------+------------+-----------+---------------------------------------------------------------------------------+
+
+1421 AUDIT_IPE_CONFIG_CHANGE
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Event Example::
+
+   type=1421 audit(1653425583.136:54): old_active_pol_name="Allow_All" old_active_pol_version=0.0.0 old_policy_digest=sha256:E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855 new_active_pol_name="boot_verified" new_active_pol_version=0.0.0 new_policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F26765076DD8EED7B8F4DB auid=4294967295 ses=4294967295 lsm=ipe res=1
+   type=1300 audit(1653425583.136:54): SYSCALL arch=c000003e syscall=1 success=yes exit=2 a0=3 a1=5596fcae1fb0 a2=2 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
+   type=1327 audit(1653425583.136:54): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2
+
+This event indicates that IPE switched the active poliy from one to another
+along with the version and the hash digest of the two policies.
+Note IPE can only have one policy active at a time, all access decision
+evaluation is based on the current active policy.
+The normal procedure to deploy a new policy is loading the policy to deploy
+into the kernel first, then switch the active policy to it.
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
+Field descriptions:
+
++------------------------+------------+-----------+---------------------------------------------------+
+| Field                  | Value Type | Optional? | Description of Value                              |
++========================+============+===========+===================================================+
+| old_active_pol_name    | string     | Yes       | The name of previous active policy                |
++------------------------+------------+-----------+---------------------------------------------------+
+| old_active_pol_version | string     | Yes       | The version of previous active policy             |
++------------------------+------------+-----------+---------------------------------------------------+
+| old_policy_digest      | string     | Yes       | The hash of previous active policy                |
++------------------------+------------+-----------+---------------------------------------------------+
+| new_active_pol_name    | string     | No        | The name of current active policy                 |
++------------------------+------------+-----------+---------------------------------------------------+
+| new_active_pol_version | string     | No        | The version of current active policy              |
++------------------------+------------+-----------+---------------------------------------------------+
+| new_policy_digest      | string     | No        | The hash of current active policy                 |
++------------------------+------------+-----------+---------------------------------------------------+
+| auid                   | integer    | No        | The login user ID                                 |
++------------------------+------------+-----------+---------------------------------------------------+
+| ses                    | integer    | No        | The login session ID                              |
++------------------------+------------+-----------+---------------------------------------------------+
+| lsm                    | string     | No        | The lsm name associated with the event            |
++------------------------+------------+-----------+---------------------------------------------------+
+| res                    | integer    | No        | The result of the audited operation(success/fail) |
++------------------------+------------+-----------+---------------------------------------------------+
+
+1422 AUDIT_IPE_POLICY_LOAD
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Event Example::
+
+   type=1422 audit(1653425529.927:53): policy_name="boot_verified" policy_version=0.0.0 policy_digest=sha256:820EEA5B40CA42B51F68962354BA083122A20BB846F26765076DD8EED7B8F4DB auid=4294967295 ses=4294967295 lsm=ipe res=1 errno=0
+   type=1300 audit(1653425529.927:53): arch=c000003e syscall=1 success=yes exit=2567 a0=3 a1=5596fcae1fb0 a2=a07 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
+   type=1327 audit(1653425529.927:53): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2E
+
+This record indicates a new policy has been loaded into the kernel with the policy name, policy version and policy hash.
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
+Field descriptions:
+
++----------------+------------+-----------+-------------------------------------------------------------+
+| Field          | Value Type | Optional? | Description of Value                                        |
++================+============+===========+=============================================================+
+| policy_name    | string     | Yes       | The policy_name                                             |
++----------------+------------+-----------+-------------------------------------------------------------+
+| policy_version | string     | Yes       | The policy_version                                          |
++----------------+------------+-----------+-------------------------------------------------------------+
+| policy_digest  | string     | Yes       | The policy hash                                             |
++----------------+------------+-----------+-------------------------------------------------------------+
+| auid           | integer    | No        | The login user ID                                           |
++----------------+------------+-----------+-------------------------------------------------------------+
+| ses            | integer    | No        | The login session ID                                        |
++----------------+------------+-----------+-------------------------------------------------------------+
+| lsm            | string     | No        | The lsm name associated with the event                      |
++----------------+------------+-----------+-------------------------------------------------------------+
+| res            | integer    | No        | The result of the audited operation(success/fail)           |
++----------------+------------+-----------+-------------------------------------------------------------+
+| errno          | integer    | No        | Error code from policy loading operations (see table below) |
++----------------+------------+-----------+-------------------------------------------------------------+
+
+Policy error codes (errno):
+
+The following table lists the error codes that may appear in the errno field while loading or updating the policy:
+
++----------------+--------------------------------------------------------+
+| Error Code     | Description                                            |
++================+========================================================+
+| 0              | Success                                                |
++----------------+--------------------------------------------------------+
+| -EPERM         | Insufficient permission                                |
++----------------+--------------------------------------------------------+
+| -EEXIST        | Same name policy already deployed                      |
++----------------+--------------------------------------------------------+
+| -EBADMSG       | Policy is invalid                                      |
++----------------+--------------------------------------------------------+
+| -ENOMEM        | Out of memory (OOM)                                    |
++----------------+--------------------------------------------------------+
+| -ERANGE        | Policy version number overflow                         |
++----------------+--------------------------------------------------------+
+| -EINVAL        | Policy version parsing error                           |
++----------------+--------------------------------------------------------+
+| -ENOKEY        | Key used to sign the IPE policy not found in keyring   |
++----------------+--------------------------------------------------------+
+| -EKEYREJECTED  | Policy signature verification failed                   |
++----------------+--------------------------------------------------------+
+| -ESTALE        | Attempting to update an IPE policy with older version  |
++----------------+--------------------------------------------------------+
+| -ENOENT        | Policy was deleted while updating                      |
++----------------+--------------------------------------------------------+
+
+1404 AUDIT_MAC_STATUS
+^^^^^^^^^^^^^^^^^^^^^
+
+Event Examples::
+
+   type=1404 audit(1653425689.008:55): enforcing=0 old_enforcing=1 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
+   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
+   type=1327 audit(1653425689.008:55): proctitle="-bash"
+
+   type=1404 audit(1653425689.008:55): enforcing=1 old_enforcing=0 auid=4294967295 ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
+   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
+   type=1327 audit(1653425689.008:55): proctitle="-bash"
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
+Field descriptions:
+
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| Field         | Value Type | Optional? | Description of Value                                                                            |
++===============+============+===========+=================================================================================================+
+| enforcing     | integer    | No        | The enforcing state IPE is being switched to, 1 is in enforcing mode, 0 is in permissive mode   |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| old_enforcing | integer    | No        | The enforcing state IPE is being switched from, 1 is in enforcing mode, 0 is in permissive mode |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| auid          | integer    | No        | The login user ID                                                                               |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| ses           | integer    | No        | The login session ID                                                                            |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| enabled       | integer    | No        | The new TTY audit enabled setting                                                               |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| old-enabled   | integer    | No        | The old TTY audit enabled setting                                                               |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| lsm           | string     | No        | The lsm name associated with the event                                                          |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+| res           | integer    | No        | The result of the audited operation(success/fail)                                               |
++---------------+------------+-----------+-------------------------------------------------------------------------------------------------+
+
+
+Success Auditing
+^^^^^^^^^^^^^^^^
+
+IPE supports success auditing. When enabled, all events that pass IPE
+policy and are not blocked will emit an audit event. This is disabled by
+default, and can be enabled via the kernel command line
+``ipe.success_audit=(0|1)`` or
+``/sys/kernel/security/ipe/success_audit`` securityfs file.
+
+This is *very* noisy, as IPE will check every userspace binary on the
+system, but is useful for debugging policies.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
+   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Properties
+----------
+
+As explained above, IPE properties are ``key=value`` pairs expressed in IPE
+policy. Two properties are built-into the policy parser: 'op' and 'action'.
+The other properties are used to restrict immutable security properties
+about the files being evaluated. Currently those properties are:
+'``boot_verified``', '``dmverity_signature``', '``dmverity_roothash``',
+'``fsverity_signature``', '``fsverity_digest``'. A description of all
+properties supported by IPE are listed below:
+
+op
+~~
+
+Indicates the operation for a rule to apply to. Must be in every rule,
+as the first token. IPE supports the following operations:
+
+   ``EXECUTE``
+
+      Pertains to any file attempting to be executed, or loaded as an
+      executable.
+
+   ``FIRMWARE``:
+
+      Pertains to firmware being loaded via the firmware_class interface.
+      This covers both the preallocated buffer and the firmware file
+      itself.
+
+   ``KMODULE``:
+
+      Pertains to loading kernel modules via ``modprobe`` or ``insmod``.
+
+   ``KEXEC_IMAGE``:
+
+      Pertains to kernel images loading via ``kexec``.
+
+   ``KEXEC_INITRAMFS``
+
+      Pertains to initrd images loading via ``kexec --initrd``.
+
+   ``POLICY``:
+
+      Controls loading policies via reading a kernel-space initiated read.
+
+      An example of such is loading IMA policies by writing the path
+      to the policy file to ``$securityfs/ima/policy``
+
+   ``X509_CERT``:
+
+      Controls loading IMA certificates through the Kconfigs,
+      ``CONFIG_IMA_X509_PATH`` and ``CONFIG_EVM_X509_PATH``.
+
+action
+~~~~~~
+
+   Determines what IPE should do when a rule matches. Must be in every
+   rule, as the final clause. Can be one of:
+
+   ``ALLOW``:
+
+      If the rule matches, explicitly allow access to the resource to proceed
+      without executing any more rules.
+
+   ``DENY``:
+
+      If the rule matches, explicitly prohibit access to the resource to
+      proceed without executing any more rules.
+
+boot_verified
+~~~~~~~~~~~~~
+
+   This property can be utilized for authorization of files from initramfs.
+   The format of this property is::
+
+         boot_verified=(TRUE|FALSE)
+
+
+   .. WARNING::
+
+      This property will trust files from initramfs(rootfs). It should
+      only be used during early booting stage. Before mounting the real
+      rootfs on top of the initramfs, initramfs script will recursively
+      remove all files and directories on the initramfs. This is typically
+      implemented by using switch_root(8) [#switch_root]_. Therefore the
+      initramfs will be empty and not accessible after the real
+      rootfs takes over. It is advised to switch to a different policy
+      that doesn't rely on the property after this point.
+      This ensures that the trust policies remain relevant and effective
+      throughout the system's operation.
+
+dmverity_roothash
+~~~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization or revocation of
+   specific dm-verity volumes, identified via their root hashes. It has a
+   dependency on the DM_VERITY module. This property is controlled by
+   the ``IPE_PROP_DM_VERITY`` config option, it will be automatically
+   selected when ``SECURITY_IPE`` and ``DM_VERITY`` are all enabled.
+   The format of this property is::
+
+      dmverity_roothash=DigestName:HexadecimalString
+
+   The supported DigestNames for dmverity_roothash are [#dmveritydigests]_
+
+      + blake2b-512
+      + blake2s-256
+      + sha256
+      + sha384
+      + sha512
+      + sha3-224
+      + sha3-256
+      + sha3-384
+      + sha3-512
+      + sm3
+      + rmd160
+
+dmverity_signature
+~~~~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization of all dm-verity
+   volumes that have a signed roothash that validated by a keyring
+   specified by dm-verity's configuration, either the system trusted
+   keyring, or the secondary keyring. It depends on
+   ``DM_VERITY_VERIFY_ROOTHASH_SIG`` config option and is controlled by
+   the ``IPE_PROP_DM_VERITY_SIGNATURE`` config option, it will be automatically
+   selected when ``SECURITY_IPE``, ``DM_VERITY`` and
+   ``DM_VERITY_VERIFY_ROOTHASH_SIG`` are all enabled.
+   The format of this property is::
+
+      dmverity_signature=(TRUE|FALSE)
+
+fsverity_digest
+~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization of specific fsverity
+   enabled files, identified via their fsverity digests.
+   It depends on ``FS_VERITY`` config option and is controlled by
+   the ``IPE_PROP_FS_VERITY`` config option, it will be automatically
+   selected when ``SECURITY_IPE`` and ``FS_VERITY`` are all enabled.
+   The format of this property is::
+
+      fsverity_digest=DigestName:HexadecimalString
+
+   The supported DigestNames for fsverity_digest are [#fsveritydigest]_
+
+      + sha256
+      + sha512
+
+fsverity_signature
+~~~~~~~~~~~~~~~~~~
+
+   This property is used to authorize all fs-verity enabled files that have
+   been verified by fs-verity's built-in signature mechanism. The signature
+   verification relies on a key stored within the ".fs-verity" keyring. It
+   depends on ``FS_VERITY_BUILTIN_SIGNATURES`` config option and
+   it is controlled by the ``IPE_PROP_FS_VERITY`` config option,
+   it will be automatically selected when ``SECURITY_IPE``, ``FS_VERITY``
+   and ``FS_VERITY_BUILTIN_SIGNATURES`` are all enabled.
+   The format of this property is::
+
+      fsverity_signature=(TRUE|FALSE)
+
+Policy Examples
+---------------
+
+Allow all
+~~~~~~~~~
+
+::
+
+   policy_name=Allow_All policy_version=0.0.0
+   DEFAULT action=ALLOW
+
+Allow only initramfs
+~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Allow_Initramfs policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+
+Allow any signed and validated dm-verity volume and the initramfs
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Allow_Signed_DMV_And_Initramfs policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+   op=EXECUTE dmverity_signature=TRUE action=ALLOW
+
+Prohibit execution from a specific dm-verity volume
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Deny_DMV_By_Roothash policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE dmverity_roothash=sha256:cd2c5bae7c6c579edaae4353049d58eb5f2e8be0244bf05345bc8e5ed257baff action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+   op=EXECUTE dmverity_signature=TRUE action=ALLOW
+
+Allow only a specific dm-verity volume
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Allow_DMV_By_Roothash policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE dmverity_roothash=sha256:401fcec5944823ae12f62726e8184407a5fa9599783f030dec146938 action=ALLOW
+
+Allow any fs-verity file with a valid built-in signature
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Allow_Signed_And_Validated_FSVerity policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE fsverity_signature=TRUE action=ALLOW
+
+Allow execution of a specific fs-verity file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=ALLOW_FSV_By_Digest policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE fsverity_digest=sha256:fd88f2b8824e197f850bf4c5109bea5cf0ee38104f710843bb72da796ba5af9e action=ALLOW
+
+Additional Information
+----------------------
+
+- `Github Repository <https://github.com/microsoft/ipe>`_
+- :doc:`Developer and design docs for IPE </security/ipe>`
+
+FAQ
+---
+
+Q:
+   What's the difference between other LSMs which provide a measure of
+   trust-based access control?
+
+A:
+
+   In general, there's two other LSMs that can provide similar functionality:
+   IMA, and Loadpin.
+
+   IMA and IPE are functionally very similar. The significant difference between
+   the two is the policy. [#devdoc]_
+
+   Loadpin and IPE differ fairly dramatically, as Loadpin only covers the IPE's
+   kernel read operations, whereas IPE is capable of controlling execution
+   on top of kernel read. The trust model is also different; Loadpin roots its
+   trust in the initial super-block, whereas trust in IPE is stemmed from kernel
+   itself (via ``SYSTEM_TRUSTED_KEYS``).
+
+-----------
+
+.. [#digest_cache_lsm] https://lore.kernel.org/lkml/20240415142436.2545003-1-roberto.sassu@huaweicloud.com/
+
+.. [#devdoc] Please see :doc:`the design docs </security/ipe>` for more on
+             this topic.
+
+.. [#switch_root] https://man7.org/linux/man-pages/man8/switch_root.8.html
+
+.. [#dmveritydigests] These hash algorithms are based on values accepted by
+                      the Linux crypto API; IPE does not impose any
+                      restrictions on the digest algorithm itself;
+                      thus, this list may be out of date.
+
+.. [#fsveritydigest] These hash algorithms are based on values accepted by the
+                     kernel's fsverity support; IPE does not impose any
+                     restrictions on the digest algorithm itself;
+                     thus, this list may be out of date.
diff --git a/Documentation/admin-guide/LSM/landlock.rst b/Documentation/admin-guide/LSM/landlock.rst
new file mode 100644
index 000000000..2998552bb
--- /dev/null
+++ b/Documentation/admin-guide/LSM/landlock.rst
@@ -0,0 +1,298 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. Copyright © 2025 Microsoft Corporation
+.. Copyright © 2026 Cloudflare, Inc.
+
+================================
+Landlock: system-wide management
+================================
+
+:Author: Mickaël Salaün
+:Date: August 2026
+
+Landlock can leverage the audit framework to log events.
+
+User space documentation can be found here:
+Documentation/userspace-api/landlock.rst.
+
+Audit
+=====
+
+Denied access requests are logged by default for a sandboxed program if `audit`
+is enabled.  This default behavior can be changed with the
+sys_landlock_restrict_self() flags (cf.
+Documentation/userspace-api/landlock.rst), or suppressed on a per-object
+basis by using ``LANDLOCK_ADD_RULE_QUIET`` (ABI 10+).  Landlock logs can
+also be masked thanks to audit rules.  Landlock can generate 2 audit
+record types.
+
+Record types
+------------
+
+AUDIT_LANDLOCK_ACCESS
+    This record type identifies a denied access request to a kernel resource.
+    The ``domain`` field indicates the ID of the domain that blocked the
+    request.  The ``blockers`` field indicates the cause(s) of this denial
+    (separated by a comma), and the following fields identify the kernel object
+    (similar to SELinux).  There may be more than one of this record type per
+    audit event.
+
+    Example with a file link request generating two records in the same event::
+
+        domain=195ba459b blockers=fs.refer path="/usr/bin" dev="vda2" ino=351
+        domain=195ba459b blockers=fs.make_reg,fs.refer path="/usr/local" dev="vda2" ino=365
+
+
+    The ``blockers`` field uses dot-separated prefixes to indicate the type of
+    restriction that caused the denial:
+
+    **fs.*** - Filesystem access rights (ABI 1+):
+        - fs.execute, fs.write_file, fs.read_file, fs.read_dir
+        - fs.remove_dir, fs.remove_file
+        - fs.make_char, fs.make_dir, fs.make_reg, fs.make_sock
+        - fs.make_fifo, fs.make_block, fs.make_sym
+        - fs.refer (ABI 2+)
+        - fs.truncate (ABI 3+)
+        - fs.ioctl_dev (ABI 5+)
+        - fs.resolve_unix (ABI 9+)
+
+    **net.*** - Network access rights (ABI 4+):
+        - net.bind_tcp - TCP port binding was denied
+        - net.connect_tcp - TCP connection was denied
+        - net.bind_udp - UDP port binding was denied
+        - net.connect_send_udp - UDP connection and send was denied
+
+    **scope.*** - IPC scoping restrictions (ABI 6+):
+        - scope.abstract_unix_socket - Abstract UNIX socket connection denied
+        - scope.signal - Signal sending denied
+
+    Multiple blockers can appear in a single event (comma-separated) when
+    multiple access rights are missing. For example, creating a regular file
+    in a directory that lacks both ``make_reg`` and ``refer`` rights would show
+    ``blockers=fs.make_reg,fs.refer``.
+
+    The object identification fields (path, dev, ino for filesystem; opid,
+    ocomm for signals) depend on the type of access being blocked and provide
+    context about what resource was involved in the denial.
+
+
+AUDIT_LANDLOCK_DOMAIN
+    This record type describes the status of a Landlock domain.  The ``status``
+    field can be either ``allocated`` or ``deallocated``.
+
+    The ``allocated`` status is part of the same audit event and follows
+    the first logged ``AUDIT_LANDLOCK_ACCESS`` record of a domain.  It identifies
+    Landlock domain information at the time of the sys_landlock_restrict_self()
+    call with the following fields:
+
+    - the ``domain`` ID
+    - the enforcement ``mode``
+    - the domain creator's ``pid``
+    - the domain creator's ``uid``
+    - the domain creator's executable path (``exe``)
+    - the domain creator's command line (``comm``)
+
+    Example::
+
+        domain=195ba459b status=allocated mode=enforcing pid=300 uid=0 exe="/root/sandboxer" comm="sandboxer"
+
+    The ``deallocated`` status is an event on its own and it identifies a
+    Landlock domain release.  After such event, it is guarantee that the
+    related domain ID will never be reused during the lifetime of the system.
+    The ``domain`` field indicates the ID of the domain which is released, and
+    the ``denials`` field indicates the total number of denied access request,
+    which might not have been logged according to the audit rules and
+    sys_landlock_restrict_self()'s flags.
+
+    Example::
+
+        domain=195ba459b status=deallocated denials=3
+
+
+Event samples
+--------------
+
+Here are two examples of log events (see serial numbers).
+
+In this example a sandboxed program (``kill``) tries to send a signal to the
+init process, which is denied because of the signal scoping restriction
+(``LL_SCOPED=s``)::
+
+  $ LL_FS_RO=/ LL_FS_RW=/ LL_SCOPED=s LL_FORCE_LOG=1 ./sandboxer kill 1
+
+This command generates two events, each identified with a unique serial
+number following a timestamp (``msg=audit(1729738800.268:30)``).  The first
+event (serial ``30``) contains 4 records.  The first record
+(``type=LANDLOCK_ACCESS``) shows an access denied by the domain `1a6fdc66f`.
+The cause of this denial is signal scoping restriction
+(``blockers=scope.signal``).  The process that would have receive this signal
+is the init process (``opid=1 ocomm="systemd"``).
+
+The second record (``type=LANDLOCK_DOMAIN``) describes (``status=allocated``)
+domain `1a6fdc66f`.  This domain was created by process ``286`` executing the
+``/root/sandboxer`` program launched by the root user.
+
+The third record (``type=SYSCALL``) describes the syscall, its provided
+arguments, its result (``success=no exit=-1``), and the process that called it.
+
+The fourth record (``type=PROCTITLE``) shows the command's name as an
+hexadecimal value.  This can be translated with ``python -c
+'print(bytes.fromhex("6B696C6C0031"))'``.
+
+Finally, the last record (``type=LANDLOCK_DOMAIN``) is also the only one from
+the second event (serial ``31``).  It is not tied to a direct user space action
+but an asynchronous one to free resources tied to a Landlock domain
+(``status=deallocated``).  This can be useful to know that the following logs
+will not concern the domain ``1a6fdc66f`` anymore.  This record also summarize
+the number of requests this domain denied (``denials=1``), whether they were
+logged or not.
+
+.. code-block::
+
+  type=LANDLOCK_ACCESS msg=audit(1729738800.268:30): domain=1a6fdc66f blockers=scope.signal opid=1 ocomm="systemd"
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.268:30): domain=1a6fdc66f status=allocated mode=enforcing pid=286 uid=0 exe="/root/sandboxer" comm="sandboxer"
+  type=SYSCALL msg=audit(1729738800.268:30): arch=c000003e syscall=62 success=no exit=-1 [..] ppid=272 pid=286 auid=0 uid=0 gid=0 [...] comm="kill" [...]
+  type=PROCTITLE msg=audit(1729738800.268:30): proctitle=6B696C6C0031
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.324:31): domain=1a6fdc66f status=deallocated denials=1
+
+Here is another example showcasing filesystem access control::
+
+  $ LL_FS_RO=/ LL_FS_RW=/tmp LL_FORCE_LOG=1 ./sandboxer sh -c "echo > /etc/passwd"
+
+The related audit logs contains 8 records from 3 different events (serials 33,
+34 and 35) created by the same domain `1a6fdc679`::
+
+  type=LANDLOCK_ACCESS msg=audit(1729738800.221:33): domain=1a6fdc679 blockers=fs.write_file path="/dev/tty" dev="devtmpfs" ino=9
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.221:33): domain=1a6fdc679 status=allocated mode=enforcing pid=289 uid=0 exe="/root/sandboxer" comm="sandboxer"
+  type=SYSCALL msg=audit(1729738800.221:33): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
+  type=PROCTITLE msg=audit(1729738800.221:33): proctitle=7368002D63006563686F203E202F6574632F706173737764
+  type=LANDLOCK_ACCESS msg=audit(1729738800.221:34): domain=1a6fdc679 blockers=fs.write_file path="/etc/passwd" dev="vda2" ino=143821
+  type=SYSCALL msg=audit(1729738800.221:34): arch=c000003e syscall=257 success=no exit=-13 [...] ppid=272 pid=289 auid=0 uid=0 gid=0 [...] comm="sh" [...]
+  type=PROCTITLE msg=audit(1729738800.221:34): proctitle=7368002D63006563686F203E202F6574632F706173737764
+  type=LANDLOCK_DOMAIN msg=audit(1729738800.261:35): domain=1a6fdc679 status=deallocated denials=2
+
+
+Event filtering
+---------------
+
+If you get spammed with audit logs related to Landlock, this is either an
+attack attempt or a bug in the security policy.  We can put in place some
+filters to limit noise with two complementary ways:
+
+- with sys_landlock_restrict_self()'s flags, or
+  ``LANDLOCK_ADD_RULE_QUIET`` (ABI 10+) if we can fix the sandboxed
+  programs,
+- or with audit rules (see :manpage:`auditctl(8)`).
+
+Tracepoints
+===========
+
+Landlock also provides tracepoints as an alternative to audit for
+debugging and observability.  Tracepoints fire unconditionally,
+independent of audit configuration, ``audit_enabled``, and domain log
+flags.  This makes them suitable for always-on monitoring with eBPF or
+for ad-hoc debugging with ``trace-pipe``.
+
+See Documentation/trace/events-landlock.rst for the complete event
+reference: the full event list, how to enable events and read their
+output, the field formats, the ``check_rule`` interpretation guide,
+worked event samples, ftrace filtering, and eBPF access.
+
+.. _landlock_observability:
+
+When to use tracing vs audit
+-----------------------------
+
+Audit and tracing both help diagnose Landlock policy issues:
+
+**Audit** records denied accesses with the blockers, domain, and object
+identification (path, port).  Audit is the standard Linux mechanism for
+security events, with a stable record format that is well established
+and already supported by log management systems, SIEM platforms, and EDR
+solutions.  Audit is always active when the kernel is built with audit
+support, filtered by the Landlock log flags to reduce noise in
+production, and designed for long-term security monitoring and
+compliance.
+
+**Tracing** provides deeper introspection for policy debugging.  In
+addition to denied accesses, trace events cover the complete lifecycle
+of Landlock objects (rulesets, domains) and intermediate rule matching
+during access checks.  Trace events are disabled by default (zero
+overhead) and fire unconditionally.  eBPF
+programs attached to trace events can access the full kernel context
+(ruleset rules, domain hierarchy, process credentials) via BTF, enabling
+richer analysis than the flat fields in audit records.  For example, an
+eBPF-based live monitoring tool can correlate creation, rule-addition,
+and denial events to build a real-time view of all active Landlock
+domains and their policies.  However, BTF-based access depends on
+internal kernel struct layouts which have no stability guarantee.  CO-RE
+(Compile Once, Run Everywhere) provides best-effort field relocation.
+The ftrace printk format is also not a stable ABI, but is
+self-describing via the per-event ``format`` file, allowing tools to
+adapt dynamically.
+
+Observability guarantees and limitations
+-----------------------------------------
+
+Both audit records and trace events are emitted for every denied access,
+with these exceptions:
+
+- **Landlock log flags** (audit only): ``LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF``,
+  ``LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON``, and
+  ``LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF`` control which denials
+  generate audit records.  Trace events fire regardless of these flags.
+
+- **NOAUDIT hooks**: Some LSM hooks suppress logging for speculative
+  permission probes (e.g., reading ``/proc/<pid>/status`` uses
+  ``PTRACE_MODE_NOAUDIT``).  When NOAUDIT is set, neither audit records
+  nor trace events are emitted, and the denial is not counted in
+  ``denials``.  The denial is still enforced.  This avoids performance
+  overhead and noise from speculative probes that test permissions
+  without performing an actual access.
+
+- **Audit rate limiting**: The audit subsystem may silently drop records
+  when the audit queue is full.  Trace events are not rate-limited.
+
+- **Tracepoint disabled**: When a trace event is disabled (the default
+  state), the tracepoint is a no-op with zero overhead.
+
+When both audit and tracing are active, every denial emits a trace event,
+and a denial that the domain's log policy selects additionally produces an
+audit record (subject to the Landlock log flags).  The ``denials`` count in
+``free_domain`` events is incremented for every denial regardless of the
+log flags, so it can exceed the number of audit records (which the log
+flags and audit-side rate-limiting or exclude rules may suppress).
+
+.. _landlock_observability_security:
+
+Observability security considerations
+---------------------------------------
+
+Both audit records and trace events expose information about all
+Landlock-sandboxed processes on the system, including filesystem paths
+being accessed, network ports, and process identities.  System
+administrators must ensure that access to audit logs (controlled by the
+audit subsystem configuration) and to trace events (requiring
+``CAP_SYS_ADMIN`` or ``CAP_BPF`` + ``CAP_PERFMON``) is restricted to
+trusted users.
+
+eBPF programs attached to Landlock trace events have access to the full
+kernel context of each event (ruleset rules, domain hierarchy, process
+credentials) via BTF, exposing sensitive state about every sandboxed
+process.  Restrict this access to trusted users, as for the audit logs.
+
+Audit logs and kernel trace events require elevated privileges and are
+system-wide; they are not designed for per-sandbox unprivileged
+monitoring.
+
+Additional documentation
+========================
+
+* `Linux Audit Documentation`_
+* Documentation/userspace-api/landlock.rst
+* Documentation/trace/events-landlock.rst
+* Documentation/security/landlock.rst
+* https://landlock.io
+
+.. Links
+.. _Linux Audit Documentation:
+   https://github.com/linux-audit/audit-documentation/wiki
diff --git a/Documentation/admin-guide/LSM/tomoyo.rst b/Documentation/admin-guide/LSM/tomoyo.rst
new file mode 100644
index 000000000..bdb2c2e2a
--- /dev/null
+++ b/Documentation/admin-guide/LSM/tomoyo.rst
@@ -0,0 +1,52 @@
+======
+TOMOYO
+======
+
+What is TOMOYO?
+===============
+
+TOMOYO is a name-based MAC extension (LSM module) for the Linux kernel.
+
+LiveCD-based tutorials are available at
+
+https://tomoyo.sourceforge.net/1.8/ubuntu12.04-live.html
+https://tomoyo.sourceforge.net/1.8/centos6-live.html
+
+Though these tutorials use non-LSM version of TOMOYO, they are useful for you
+to know what TOMOYO is.
+
+How to enable TOMOYO?
+=====================
+
+Build the kernel with ``CONFIG_SECURITY_TOMOYO=y`` and pass ``security=tomoyo`` on
+kernel's command line.
+
+Please see https://tomoyo.sourceforge.net/2.6/ for details.
+
+Where is documentation?
+=======================
+
+User <-> Kernel interface documentation is available at
+https://tomoyo.sourceforge.net/2.6/policy-specification/index.html .
+
+Materials we prepared for seminars and symposiums are available at
+https://sourceforge.net/projects/tomoyo/files/docs/ .
+Below lists are chosen from three aspects.
+
+What is TOMOYO?
+  TOMOYO Linux Overview
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-takeda.pdf
+  TOMOYO Linux: pragmatic and manageable security for Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/freedomhectaipei-tomoyo.pdf
+  TOMOYO Linux: A Practical Method to Understand and Protect Your Own Linux Box
+    https://sourceforge.net/projects/tomoyo/files/docs/PacSec2007-en-no-demo.pdf
+
+What can TOMOYO do?
+  Deep inside TOMOYO Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-kumaneko.pdf
+  The role of "pathname based access control" in security.
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008-bof.pdf
+
+History of TOMOYO?
+  Realities of Mainlining
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008.pdf
diff --git a/Documentation/admin-guide/RAS/address-translation.rst b/Documentation/admin-guide/RAS/address-translation.rst
new file mode 100644
index 000000000..f0ca17b43
--- /dev/null
+++ b/Documentation/admin-guide/RAS/address-translation.rst
@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Address translation
+===================
+
+x86 AMD
+-------
+
+Zen-based AMD systems include a Data Fabric that manages the layout of
+physical memory. Devices attached to the Fabric, like memory controllers,
+I/O, etc., may not have a complete view of the system physical memory map.
+These devices may provide a "normalized", i.e. device physical, address
+when reporting memory errors. Normalized addresses must be translated to
+a system physical address for the kernel to action on the memory.
+
+AMD Address Translation Library (CONFIG_AMD_ATL) provides translation for
+this case.
+
+Glossary of acronyms used in address translation for Zen-based systems
+
+* CCM               = Cache Coherent Moderator
+* COD               = Cluster-on-Die
+* COH_ST            = Coherent Station
+* DF                = Data Fabric
diff --git a/Documentation/admin-guide/RAS/error-decoding.rst b/Documentation/admin-guide/RAS/error-decoding.rst
new file mode 100644
index 000000000..26a72f3fe
--- /dev/null
+++ b/Documentation/admin-guide/RAS/error-decoding.rst
@@ -0,0 +1,21 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Error decoding
+==============
+
+x86
+---
+
+Error decoding on AMD systems should be done using the rasdaemon tool:
+https://github.com/mchehab/rasdaemon/
+
+While the daemon is running, it would automatically log and decode
+errors. If not, one can still decode such errors by supplying the
+hardware information from the error::
+
+        $ rasdaemon -p --status <STATUS> --ipid <IPID> --smca
+
+Also, the user can pass particular family and model to decode the error
+string::
+
+        $ rasdaemon -p --status <STATUS> --ipid <IPID> --smca --family <CPU Family> --model <CPU Model> --bank <BANK_NUM>
diff --git a/Documentation/admin-guide/RAS/index.rst b/Documentation/admin-guide/RAS/index.rst
new file mode 100644
index 000000000..f4087040a
--- /dev/null
+++ b/Documentation/admin-guide/RAS/index.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. toctree::
+   :maxdepth: 2
+
+   main
+   error-decoding
+   address-translation
diff --git a/Documentation/admin-guide/RAS/main.rst b/Documentation/admin-guide/RAS/main.rst
new file mode 100644
index 000000000..5a45db32c
--- /dev/null
+++ b/Documentation/admin-guide/RAS/main.rst
@@ -0,0 +1,1087 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+==================================================
+Reliability, Availability and Serviceability (RAS)
+==================================================
+
+This documents different aspects of the RAS functionality present in the
+kernel.
+
+RAS concepts
+************
+
+Reliability, Availability and Serviceability (RAS) is a concept used on
+servers meant to measure their robustness.
+
+Reliability
+  is the probability that a system will produce correct outputs.
+
+  * Generally measured as Mean Time Between Failures (MTBF)
+  * Enhanced by features that help to avoid, detect and repair hardware faults
+
+Availability
+  is the probability that a system is operational at a given time
+
+  * Generally measured as a percentage of downtime per a period of time
+  * Often uses mechanisms to detect and correct hardware faults in
+    runtime;
+
+Serviceability (or maintainability)
+  is the simplicity and speed with which a system can be repaired or
+  maintained
+
+  * Generally measured on Mean Time Between Repair (MTBR)
+
+Improving RAS
+-------------
+
+In order to reduce systems downtime, a system should be capable of detecting
+hardware errors, and, when possible correcting them in runtime. It should
+also provide mechanisms to detect hardware degradation, in order to warn
+the system administrator to take the action of replacing a component before
+it causes data loss or system downtime.
+
+Among the monitoring measures, the most usual ones include:
+
+* CPU – detect errors at instruction execution and at L1/L2/L3 caches;
+* Memory – add error correction logic (ECC) to detect and correct errors;
+* I/O – add CRC checksums for transferred data;
+* Storage – RAID, journal file systems, checksums,
+  Self-Monitoring, Analysis and Reporting Technology (SMART).
+
+By monitoring the number of occurrences of error detections, it is possible
+to identify if the probability of hardware errors is increasing, and, on such
+case, do a preventive maintenance to replace a degraded component while
+those errors are correctable.
+
+Types of errors
+---------------
+
+Most mechanisms used on modern systems use technologies like Hamming
+Codes that allow error correction when the number of errors on a bit packet
+is below a threshold. If the number of errors is above, those mechanisms
+can indicate with a high degree of confidence that an error happened, but
+they can't correct.
+
+Also, sometimes an error occur on a component that it is not used. For
+example, a part of the memory that it is not currently allocated.
+
+That defines some categories of errors:
+
+* **Correctable Error (CE)** - the error detection mechanism detected and
+  corrected the error. Such errors are usually not fatal, although some
+  Kernel mechanisms allow the system administrator to consider them as fatal.
+
+* **Uncorrected Error (UE)** - the amount of errors happened above the error
+  correction threshold, and the system was unable to auto-correct.
+
+* **Fatal Error** - when an UE error happens on a critical component of the
+  system (for example, a piece of the Kernel got corrupted by an UE), the
+  only reliable way to avoid data corruption is to hang or reboot the machine.
+
+* **Non-fatal Error** - when an UE error happens on an unused component,
+  like a CPU in power down state or an unused memory bank, the system may
+  still run, eventually replacing the affected hardware by a hot spare,
+  if available.
+
+  Also, when an error happens on a userspace process, it is also possible to
+  kill such process and let userspace restart it.
+
+The mechanism for handling non-fatal errors is usually complex and may
+require the help of some userspace application, in order to apply the
+policy desired by the system administrator.
+
+Identifying a bad hardware component
+------------------------------------
+
+Just detecting a hardware flaw is usually not enough, as the system needs
+to pinpoint to the minimal replaceable unit (MRU) that should be exchanged
+to make the hardware reliable again.
+
+So, it requires not only error logging facilities, but also mechanisms that
+will translate the error message to the silkscreen or component label for
+the MRU.
+
+Typically, it is very complex for memory, as modern CPUs interlace memory
+from different memory modules, in order to provide a better performance. The
+DMI BIOS usually have a list of memory module labels, with can be obtained
+using the ``dmidecode`` tool. For example, on a desktop machine, it shows::
+
+	Memory Device
+		Total Width: 64 bits
+		Data Width: 64 bits
+		Size: 16384 MB
+		Form Factor: SODIMM
+		Set: None
+		Locator: ChannelA-DIMM0
+		Bank Locator: BANK 0
+		Type: DDR4
+		Type Detail: Synchronous
+		Speed: 2133 MHz
+		Rank: 2
+		Configured Clock Speed: 2133 MHz
+
+On the above example, a DDR4 SO-DIMM memory module is located at the
+system's memory labeled as "BANK 0", as given by the *bank locator* field.
+Please notice that, on such system, the *total width* is equal to the
+*data width*. It means that such memory module doesn't have error
+detection/correction mechanisms.
+
+Unfortunately, not all systems use the same field to specify the memory
+bank. On this example, from an older server, ``dmidecode`` shows::
+
+	Memory Device
+		Array Handle: 0x1000
+		Error Information Handle: Not Provided
+		Total Width: 72 bits
+		Data Width: 64 bits
+		Size: 8192 MB
+		Form Factor: DIMM
+		Set: 1
+		Locator: DIMM_A1
+		Bank Locator: Not Specified
+		Type: DDR3
+		Type Detail: Synchronous Registered (Buffered)
+		Speed: 1600 MHz
+		Rank: 2
+		Configured Clock Speed: 1600 MHz
+
+There, the DDR3 RDIMM memory module is located at the system's memory labeled
+as "DIMM_A1", as given by the *locator* field. Please notice that this
+memory module has 64 bits of *data width* and 72 bits of *total width*. So,
+it has 8 extra bits to be used by error detection and correction mechanisms.
+Such kind of memory is called Error-correcting code memory (ECC memory).
+
+To make things even worse, it is not uncommon that systems with different
+labels on their system's board to use exactly the same BIOS, meaning that
+the labels provided by the BIOS won't match the real ones.
+
+ECC memory
+----------
+
+As mentioned in the previous section, ECC memory has extra bits to be
+used for error correction. In the above example, a memory module has
+64 bits of *data width*, and 72 bits of *total width*.  The extra 8
+bits which are used for the error detection and correction mechanisms
+are referred to as the *syndrome*\ [#f1]_\ [#f2]_.
+
+So, when the cpu requests the memory controller to write a word with
+*data width*, the memory controller calculates the *syndrome* in real time,
+using Hamming code, or some other error correction code, like SECDED+,
+producing a code with *total width* size. Such code is then written
+on the memory modules.
+
+At read, the *total width* bits code is converted back, using the same
+ECC code used on write, producing a word with *data width* and a *syndrome*.
+The word with *data width* is sent to the CPU, even when errors happen.
+
+The memory controller also looks at the *syndrome* in order to check if
+there was an error, and if the ECC code was able to fix such error.
+If the error was corrected, a Corrected Error (CE) happened. If not, an
+Uncorrected Error (UE) happened.
+
+The information about the CE/UE errors is stored on some special registers
+at the memory controller and can be accessed by reading such registers,
+either by BIOS, by some special CPUs or by Linux EDAC driver. On x86 64
+bit CPUs, such errors can also be retrieved via the Machine Check
+Architecture (MCA)\ [#f3]_.
+
+.. [#f1] Please notice that several memory controllers allow operation on a
+  mode called "Lock-Step", where it groups two memory modules together,
+  doing 128-bit reads/writes. That gives 16 bits for error correction, with
+  significantly improves the error correction mechanism, at the expense
+  that, when an error happens, there's no way to know what memory module is
+  to blame. So, it has to blame both memory modules.
+
+.. [#f2] Some memory controllers also allow using memory in mirror mode.
+  On such mode, the same data is written to two memory modules. At read,
+  the system checks both memory modules, in order to check if both provide
+  identical data. On such configuration, when an error happens, there's no
+  way to know what memory module is to blame. So, it has to blame both
+  memory modules (or 4 memory modules, if the system is also on Lock-step
+  mode).
+
+.. [#f3] For more details about the Machine Check Architecture (MCA),
+  please read Documentation/arch/x86/x86_64/machinecheck.rst at the Kernel tree.
+
+EDAC - Error Detection And Correction
+*************************************
+
+.. note::
+
+   "bluesmoke" was the name for this device driver subsystem when it
+   was "out-of-tree" and maintained at http://bluesmoke.sourceforge.net.
+   That site is mostly archaic now and can be used only for historical
+   purposes.
+
+   When the subsystem was pushed upstream for the first time, on
+   Kernel 2.6.16, it was renamed to ``EDAC``.
+
+Purpose
+-------
+
+The ``edac`` kernel module's goal is to detect and report hardware errors
+that occur within the computer system running under linux.
+
+Memory
+------
+
+Memory Correctable Errors (CE) and Uncorrectable Errors (UE) are the
+primary errors being harvested. These types of errors are harvested by
+the ``edac_mc`` device.
+
+Detecting CE events, then harvesting those events and reporting them,
+**can** but must not necessarily be a predictor of future UE events. With
+CE events only, the system can and will continue to operate as no data
+has been damaged yet.
+
+However, preventive maintenance and proactive part replacement of memory
+modules exhibiting CEs can reduce the likelihood of the dreaded UE events
+and system panics.
+
+Other hardware elements
+-----------------------
+
+A new feature for EDAC, the ``edac_device`` class of device, was added in
+the 2.6.23 version of the kernel.
+
+This new device type allows for non-memory type of ECC hardware detectors
+to have their states harvested and presented to userspace via the sysfs
+interface.
+
+Some architectures have ECC detectors for L1, L2 and L3 caches,
+along with DMA engines, fabric switches, main data path switches,
+interconnections, and various other hardware data paths. If the hardware
+reports it, then an edac_device device probably can be constructed to
+harvest and present that to userspace.
+
+
+PCI bus scanning
+----------------
+
+In addition, PCI devices are scanned for PCI Bus Parity and SERR Errors
+in order to determine if errors are occurring during data transfers.
+
+The presence of PCI Parity errors must be examined with a grain of salt.
+There are several add-in adapters that do **not** follow the PCI specification
+with regards to Parity generation and reporting. The specification says
+the vendor should tie the parity status bits to 0 if they do not intend
+to generate parity.  Some vendors do not do this, and thus the parity bit
+can "float" giving false positives.
+
+There is a PCI device attribute located in sysfs that is checked by
+the EDAC PCI scanning code. If that attribute is set, PCI parity/error
+scanning is skipped for that device. The attribute is::
+
+	broken_parity_status
+
+and is located in ``/sys/devices/pci<XXX>/0000:XX:YY.Z`` directories for
+PCI devices.
+
+
+Versioning
+----------
+
+EDAC is composed of a "core" module (``edac_core.ko``) and several Memory
+Controller (MC) driver modules. On a given system, the CORE is loaded
+and one MC driver will be loaded. Both the CORE and the MC driver (or
+``edac_device`` driver) have individual versions that reflect current
+release level of their respective modules.
+
+Thus, to "report" on what version a system is running, one must report
+both the CORE's and the MC driver's versions.
+
+
+Loading
+-------
+
+If ``edac`` was statically linked with the kernel then no loading
+is necessary. If ``edac`` was built as modules then simply modprobe
+the ``edac`` pieces that you need. You should be able to modprobe
+hardware-specific modules and have the dependencies load the necessary
+core modules.
+
+Example::
+
+	$ modprobe amd76x_edac
+
+loads both the ``amd76x_edac.ko`` memory controller module and the
+``edac_mc.ko`` core module.
+
+
+Sysfs interface
+---------------
+
+EDAC presents a ``sysfs`` interface for control and reporting purposes. It
+lives in the /sys/devices/system/edac directory.
+
+Within this directory there currently reside 2 components:
+
+	======= ==============================
+	mc	memory controller(s) system
+	pci	PCI control and status system
+	======= ==============================
+
+
+
+Memory Controller (mc) Model
+----------------------------
+
+Each ``mc`` device controls a set of memory modules [#f4]_. These modules
+are laid out in a Chip-Select Row (``csrowX``) and Channel table (``chX``).
+There can be multiple csrows and multiple channels.
+
+.. [#f4] Nowadays, the term DIMM (Dual In-line Memory Module) is widely
+  used to refer to a memory module, although there are other memory
+  packaging alternatives, like SO-DIMM, SIMM, etc. The UEFI
+  specification (Version 2.7) defines a memory module in the Common
+  Platform Error Record (CPER) section to be an SMBIOS Memory Device
+  (Type 17). Along this document, and inside the EDAC subsystem, the term
+  "dimm" is used for all memory modules, even when they use a
+  different kind of packaging.
+
+Memory controllers allow for several csrows, with 8 csrows being a
+typical value. Yet, the actual number of csrows depends on the layout of
+a given motherboard, memory controller and memory module characteristics.
+
+Dual channels allow for dual data length (e. g. 128 bits, on 64 bit systems)
+data transfers to/from the CPU from/to memory. Some newer chipsets allow
+for more than 2 channels, like Fully Buffered DIMMs (FB-DIMMs) memory
+controllers. The following example will assume 2 channels:
+
+	+------------+-----------------------+
+	| CS Rows    |       Channels        |
+	+------------+-----------+-----------+
+	|            |  ``ch0``  |  ``ch1``  |
+	+============+===========+===========+
+	|            |**DIMM_A0**|**DIMM_B0**|
+	+------------+-----------+-----------+
+	| ``csrow0`` |   rank0   |   rank0   |
+	+------------+-----------+-----------+
+	| ``csrow1`` |   rank1   |   rank1   |
+	+------------+-----------+-----------+
+	|            |**DIMM_A1**|**DIMM_B1**|
+	+------------+-----------+-----------+
+	| ``csrow2`` |    rank0  |  rank0    |
+	+------------+-----------+-----------+
+	| ``csrow3`` |    rank1  |  rank1    |
+	+------------+-----------+-----------+
+
+In the above example, there are 4 physical slots on the motherboard
+for memory DIMMs:
+
+	+---------+---------+
+	| DIMM_A0 | DIMM_B0 |
+	+---------+---------+
+	| DIMM_A1 | DIMM_B1 |
+	+---------+---------+
+
+Labels for these slots are usually silk-screened on the motherboard.
+Slots labeled ``A`` are channel 0 in this example. Slots labeled ``B`` are
+channel 1. Notice that there are two csrows possible on a physical DIMM.
+These csrows are allocated their csrow assignment based on the slot into
+which the memory DIMM is placed. Thus, when 1 DIMM is placed in each
+Channel, the csrows cross both DIMMs.
+
+Memory DIMMs come single or dual "ranked". A rank is a populated csrow.
+In the example above 2 dual ranked DIMMs are similarly placed. Thus,
+both csrow0 and csrow1 are populated. On the other hand, when 2 single
+ranked DIMMs are placed in slots DIMM_A0 and DIMM_B0, then they will
+have just one csrow (csrow0) and csrow1 will be empty. The pattern
+repeats itself for csrow2 and csrow3. Also note that some memory
+controllers don't have any logic to identify the memory module, see
+``rankX`` directories below.
+
+The representation of the above is reflected in the directory
+tree in EDAC's sysfs interface. Starting in directory
+``/sys/devices/system/edac/mc``, each memory controller will be
+represented by its own ``mcX`` directory, where ``X`` is the
+index of the MC::
+
+	..../edac/mc/
+		   |
+		   |->mc0
+		   |->mc1
+		   |->mc2
+		   ....
+
+Within each of the ``mcX`` directory are several EDAC control and
+attribute files.
+
+``mcX`` directories
+-------------------
+
+In ``mcX`` directories are EDAC control and attribute files for
+this ``X`` instance of the memory controllers.
+
+For a description of the sysfs API, please see:
+
+	Documentation/ABI/testing/sysfs-devices-edac
+
+
+``dimmX`` or ``rankX`` directories
+----------------------------------
+
+The recommended way to use the EDAC subsystem is to look at the information
+provided by the ``dimmX`` or ``rankX`` directories [#f5]_.
+
+A typical EDAC system has the following structure under
+``/sys/devices/system/edac/``\ [#f6]_::
+
+	/sys/devices/system/edac/
+	├── mc
+	│   ├── mc0
+	│   │   ├── ce_count
+	│   │   ├── ce_noinfo_count
+	│   │   ├── dimm0
+	│   │   │   ├── dimm_ce_count
+	│   │   │   ├── dimm_dev_type
+	│   │   │   ├── dimm_edac_mode
+	│   │   │   ├── dimm_label
+	│   │   │   ├── dimm_location
+	│   │   │   ├── dimm_mem_type
+	│   │   │   ├── dimm_ue_count
+	│   │   │   ├── size
+	│   │   │   └── uevent
+	│   │   ├── max_location
+	│   │   ├── mc_name
+	│   │   ├── reset_counters
+	│   │   ├── seconds_since_reset
+	│   │   ├── size_mb
+	│   │   ├── ue_count
+	│   │   ├── ue_noinfo_count
+	│   │   └── uevent
+	│   ├── mc1
+	│   │   ├── ce_count
+	│   │   ├── ce_noinfo_count
+	│   │   ├── dimm0
+	│   │   │   ├── dimm_ce_count
+	│   │   │   ├── dimm_dev_type
+	│   │   │   ├── dimm_edac_mode
+	│   │   │   ├── dimm_label
+	│   │   │   ├── dimm_location
+	│   │   │   ├── dimm_mem_type
+	│   │   │   ├── dimm_ue_count
+	│   │   │   ├── size
+	│   │   │   └── uevent
+	│   │   ├── max_location
+	│   │   ├── mc_name
+	│   │   ├── reset_counters
+	│   │   ├── seconds_since_reset
+	│   │   ├── size_mb
+	│   │   ├── ue_count
+	│   │   ├── ue_noinfo_count
+	│   │   └── uevent
+	│   └── uevent
+	└── uevent
+
+In the ``dimmX`` directories are EDAC control and attribute files for
+this ``X`` memory module:
+
+- ``size`` - Total memory managed by this csrow attribute file
+
+	This attribute file displays, in count of megabytes, the memory
+	that this csrow contains.
+
+- ``dimm_ue_count`` - Uncorrectable Errors count attribute file
+
+	This attribute file displays the total count of uncorrectable
+	errors that have occurred on this DIMM. If panic_on_ue is set
+	this counter will not have a chance to increment, since EDAC
+	will panic the system.
+
+- ``dimm_ce_count`` - Correctable Errors count attribute file
+
+	This attribute file displays the total count of correctable
+	errors that have occurred on this DIMM. This count is very
+	important to examine. CEs provide early indications that a
+	DIMM is beginning to fail. This count field should be
+	monitored for non-zero values and report such information
+	to the system administrator.
+
+- ``dimm_dev_type``  - Device type attribute file
+
+	This attribute file will display what type of DRAM device is
+	being utilized on this DIMM.
+	Examples:
+
+		- x1
+		- x2
+		- x4
+		- x8
+
+- ``dimm_edac_mode`` - EDAC Mode of operation attribute file
+
+	This attribute file will display what type of Error detection
+	and correction is being utilized.
+
+- ``dimm_label`` - memory module label control file
+
+	This control file allows this DIMM to have a label assigned
+	to it. With this label in the module, when errors occur
+	the output can provide the DIMM label in the system log.
+	This becomes vital for panic events to isolate the
+	cause of the UE event.
+
+	DIMM Labels must be assigned after booting, with information
+	that correctly identifies the physical slot with its
+	silk screen label. This information is currently very
+	motherboard specific and determination of this information
+	must occur in userland at this time.
+
+- ``dimm_location`` - location of the memory module
+
+	The location can have up to 3 levels, and describe how the
+	memory controller identifies the location of a memory module.
+	Depending on the type of memory and memory controller, it
+	can be:
+
+		- *csrow* and *channel* - used when the memory controller
+		  doesn't identify a single DIMM - e. g. in ``rankX`` dir;
+		- *branch*, *channel*, *slot* - typically used on FB-DIMM memory
+		  controllers;
+		- *channel*, *slot* - used on Nehalem and newer Intel drivers.
+
+- ``dimm_mem_type`` - Memory Type attribute file
+
+	This attribute file will display what type of memory is currently
+	on this csrow. Normally, either buffered or unbuffered memory.
+	Examples:
+
+		- Registered-DDR
+		- Unbuffered-DDR
+
+.. [#f5] On some systems, the memory controller doesn't have any logic
+  to identify the memory module. On such systems, the directory is called ``rankX``.
+  On modern Intel memory controllers, the memory controller identifies the
+  memory modules directly. On such systems, the directory is called ``dimmX``.
+
+.. [#f6] There are also some ``power`` directories and ``subsystem``
+  symlinks inside the sysfs mapping that are automatically created by
+  the sysfs subsystem. Currently, they serve no purpose.
+
+
+System Logging
+--------------
+
+If logging for UEs and CEs is enabled, then system logs will contain
+information indicating that errors have been detected::
+
+  EDAC MC0: CE page 0x283, offset 0xce0, grain 8, syndrome 0x6ec3, row 0, channel 1 "DIMM_B1": amd76x_edac
+  EDAC MC0: CE page 0x1e5, offset 0xfb0, grain 8, syndrome 0xb741, row 0, channel 1 "DIMM_B1": amd76x_edac
+
+
+The structure of the message is:
+
+	+---------------------------------------+-------------+
+	| Content                               | Example     |
+	+=======================================+=============+
+	| The memory controller                 | MC0         |
+	+---------------------------------------+-------------+
+	| Error type                            | CE          |
+	+---------------------------------------+-------------+
+	| Memory page                           | 0x283       |
+	+---------------------------------------+-------------+
+	| Offset in the page                    | 0xce0       |
+	+---------------------------------------+-------------+
+	| The byte granularity                  | grain 8     |
+	| or resolution of the error            |             |
+	+---------------------------------------+-------------+
+	| The error syndrome                    | 0xb741      |
+	+---------------------------------------+-------------+
+	| Memory row                            | row 0       |
+	+---------------------------------------+-------------+
+	| Memory channel                        | channel 1   |
+	+---------------------------------------+-------------+
+	| DIMM label, if set prior              | DIMM B1     |
+	+---------------------------------------+-------------+
+	| And then an optional, driver-specific |             |
+	| message that may have additional      |             |
+	| information.                          |             |
+	+---------------------------------------+-------------+
+
+Both UEs and CEs with no info will lack all but memory controller, error
+type, a notice of "no info" and then an optional, driver-specific error
+message.
+
+
+PCI Bus Parity Detection
+------------------------
+
+On Header Type 00 devices, the primary status is looked at for any
+parity error regardless of whether parity is enabled on the device or
+not. (The spec indicates parity is generated in some cases). On Header
+Type 01 bridges, the secondary status register is also looked at to see
+if parity occurred on the bus on the other side of the bridge.
+
+
+Sysfs configuration
+-------------------
+
+Under ``/sys/devices/system/edac/pci`` are control and attribute files as
+follows:
+
+
+- ``check_pci_parity`` - Enable/Disable PCI Parity checking control file
+
+	This control file enables or disables the PCI Bus Parity scanning
+	operation. Writing a 1 to this file enables the scanning. Writing
+	a 0 to this file disables the scanning.
+
+	Enable::
+
+		echo "1" >/sys/devices/system/edac/pci/check_pci_parity
+
+	Disable::
+
+		echo "0" >/sys/devices/system/edac/pci/check_pci_parity
+
+
+- ``pci_parity_count`` - Parity Count
+
+	This attribute file will display the number of parity errors that
+	have been detected.
+
+
+Module parameters
+-----------------
+
+- ``edac_mc_panic_on_ue`` - Panic on UE control file
+
+	An uncorrectable error will cause a machine panic.  This is usually
+	desirable.  It is a bad idea to continue when an uncorrectable error
+	occurs - it is indeterminate what was uncorrected and the operating
+	system context might be so mangled that continuing will lead to further
+	corruption. If the kernel has MCE configured, then EDAC will never
+	notice the UE.
+
+	LOAD TIME::
+
+		module/kernel parameter: edac_mc_panic_on_ue=[0|1]
+
+	RUN TIME::
+
+		echo "1" > /sys/module/edac_core/parameters/edac_mc_panic_on_ue
+
+
+- ``edac_mc_log_ue`` - Log UE control file
+
+
+	Generate kernel messages describing uncorrectable errors.  These errors
+	are reported through the system message log system.  UE statistics
+	will be accumulated even when UE logging is disabled.
+
+	LOAD TIME::
+
+		module/kernel parameter: edac_mc_log_ue=[0|1]
+
+	RUN TIME::
+
+		echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ue
+
+
+- ``edac_mc_log_ce`` - Log CE control file
+
+
+	Generate kernel messages describing correctable errors.  These
+	errors are reported through the system message log system.
+	CE statistics will be accumulated even when CE logging is disabled.
+
+	LOAD TIME::
+
+		module/kernel parameter: edac_mc_log_ce=[0|1]
+
+	RUN TIME::
+
+		echo "1" > /sys/module/edac_core/parameters/edac_mc_log_ce
+
+
+- ``edac_mc_poll_msec`` - Polling period control file
+
+
+	The time period, in milliseconds, for polling for error information.
+	Too small a value wastes resources.  Too large a value might delay
+	necessary handling of errors and might loose valuable information for
+	locating the error.  1000 milliseconds (once each second) is the current
+	default. Systems which require all the bandwidth they can get, may
+	increase this.
+
+	LOAD TIME::
+
+		module/kernel parameter: edac_mc_poll_msec=[0|1]
+
+	RUN TIME::
+
+		echo "1000" > /sys/module/edac_core/parameters/edac_mc_poll_msec
+
+
+- ``panic_on_pci_parity`` - Panic on PCI PARITY Error
+
+
+	This control file enables or disables panicking when a parity
+	error has been detected.
+
+
+	module/kernel parameter::
+
+			edac_panic_on_pci_pe=[0|1]
+
+	Enable::
+
+		echo "1" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe
+
+	Disable::
+
+		echo "0" > /sys/module/edac_core/parameters/edac_panic_on_pci_pe
+
+
+
+EDAC device type
+----------------
+
+In the header file, edac_pci.h, there is a series of edac_device structures
+and APIs for the EDAC_DEVICE.
+
+User space access to an edac_device is through the sysfs interface.
+
+At the location ``/sys/devices/system/edac`` (sysfs) new edac_device devices
+will appear.
+
+There is a three level tree beneath the above ``edac`` directory. For example,
+the ``test_device_edac`` device (found at the http://bluesmoke.sourceforget.net
+website) installs itself as::
+
+	/sys/devices/system/edac/test-instance
+
+in this directory are various controls, a symlink and one or more ``instance``
+directories.
+
+The standard default controls are:
+
+	==============	=======================================================
+	log_ce		boolean to log CE events
+	log_ue		boolean to log UE events
+	panic_on_ue	boolean to ``panic`` the system if an UE is encountered
+			(default off, can be set true via startup script)
+	poll_msec	time period between POLL cycles for events
+	==============	=======================================================
+
+The test_device_edac device adds at least one of its own custom control:
+
+	==============	==================================================
+	test_bits	which in the current test driver does nothing but
+			show how it is installed. A ported driver can
+			add one or more such controls and/or attributes
+			for specific uses.
+			One out-of-tree driver uses controls here to allow
+			for ERROR INJECTION operations to hardware
+			injection registers
+	==============	==================================================
+
+The symlink points to the 'struct dev' that is registered for this edac_device.
+
+Instances
+---------
+
+One or more instance directories are present. For the ``test_device_edac``
+case:
+
+	+----------------+
+	| test-instance0 |
+	+----------------+
+
+
+In this directory there are two default counter attributes, which are totals of
+counter in deeper subdirectories.
+
+	==============	====================================
+	ce_count	total of CE events of subdirectories
+	ue_count	total of UE events of subdirectories
+	==============	====================================
+
+Blocks
+------
+
+At the lowest directory level is the ``block`` directory. There can be 0, 1
+or more blocks specified in each instance:
+
+	+-------------+
+	| test-block0 |
+	+-------------+
+
+In this directory the default attributes are:
+
+	==============	================================================
+	ce_count	which is counter of CE events for this ``block``
+			of hardware being monitored
+	ue_count	which is counter of UE events for this ``block``
+			of hardware being monitored
+	==============	================================================
+
+
+The ``test_device_edac`` device adds 4 attributes and 1 control:
+
+	================== ====================================================
+	test-block-bits-0	for every POLL cycle this counter
+				is incremented
+	test-block-bits-1	every 10 cycles, this counter is bumped once,
+				and test-block-bits-0 is set to 0
+	test-block-bits-2	every 100 cycles, this counter is bumped once,
+				and test-block-bits-1 is set to 0
+	test-block-bits-3	every 1000 cycles, this counter is bumped once,
+				and test-block-bits-2 is set to 0
+	================== ====================================================
+
+
+	================== ====================================================
+	reset-counters		writing ANY thing to this control will
+				reset all the above counters.
+	================== ====================================================
+
+
+Use of the ``test_device_edac`` driver should enable any others to create their own
+unique drivers for their hardware systems.
+
+The ``test_device_edac`` sample driver is located at the
+http://bluesmoke.sourceforge.net project site for EDAC.
+
+
+Usage of EDAC APIs on Nehalem and newer Intel CPUs
+--------------------------------------------------
+
+On older Intel architectures, the memory controller was part of the North
+Bridge chipset. Nehalem, Sandy Bridge, Ivy Bridge, Haswell, Sky Lake and
+newer Intel architectures integrated an enhanced version of the memory
+controller (MC) inside the CPUs.
+
+This chapter will cover the differences of the enhanced memory controllers
+found on newer Intel CPUs, such as ``i7core_edac``, ``sb_edac`` and
+``sbx_edac`` drivers.
+
+.. note::
+
+   The Xeon E7 processor families use a separate chip for the memory
+   controller, called Intel Scalable Memory Buffer. This section doesn't
+   apply for such families.
+
+1) There is one Memory Controller per Quick Patch Interconnect
+   (QPI). At the driver, the term "socket" means one QPI. This is
+   associated with a physical CPU socket.
+
+   Each MC have 3 physical read channels, 3 physical write channels and
+   3 logic channels. The driver currently sees it as just 3 channels.
+   Each channel can have up to 3 DIMMs.
+
+   The minimum known unity is DIMMs. There are no information about csrows.
+   As EDAC API maps the minimum unity is csrows, the driver sequentially
+   maps channel/DIMM into different csrows.
+
+   For example, supposing the following layout::
+
+	Ch0 phy rd0, wr0 (0x063f4031): 2 ranks, UDIMMs
+	  dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400
+	  dimm 1 1024 Mb offset: 4, bank: 8, rank: 1, row: 0x4000, col: 0x400
+        Ch1 phy rd1, wr1 (0x063f4031): 2 ranks, UDIMMs
+	  dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400
+	Ch2 phy rd3, wr3 (0x063f4031): 2 ranks, UDIMMs
+	  dimm 0 1024 Mb offset: 0, bank: 8, rank: 1, row: 0x4000, col: 0x400
+
+   The driver will map it as::
+
+	csrow0: channel 0, dimm0
+	csrow1: channel 0, dimm1
+	csrow2: channel 1, dimm0
+	csrow3: channel 2, dimm0
+
+   exports one DIMM per csrow.
+
+   Each QPI is exported as a different memory controller.
+
+2) The MC has the ability to inject errors to test drivers. The drivers
+   implement this functionality via some error injection nodes:
+
+   For injecting a memory error, there are some sysfs nodes, under
+   ``/sys/devices/system/edac/mc/mc?/``:
+
+   - ``inject_addrmatch/*``:
+      Controls the error injection mask register. It is possible to specify
+      several characteristics of the address to match an error code::
+
+         dimm = the affected dimm. Numbers are relative to a channel;
+         rank = the memory rank;
+         channel = the channel that will generate an error;
+         bank = the affected bank;
+         page = the page address;
+         column (or col) = the address column.
+
+      each of the above values can be set to "any" to match any valid value.
+
+      At driver init, all values are set to any.
+
+      For example, to generate an error at rank 1 of dimm 2, for any channel,
+      any bank, any page, any column::
+
+		echo 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm
+		echo 1 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank
+
+	To return to the default behaviour of matching any, you can do::
+
+		echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/dimm
+		echo any >/sys/devices/system/edac/mc/mc0/inject_addrmatch/rank
+
+   - ``inject_eccmask``:
+          specifies what bits will have troubles,
+
+   - ``inject_section``:
+       specifies what ECC cache section will get the error::
+
+		3 for both
+		2 for the highest
+		1 for the lowest
+
+   - ``inject_type``:
+       specifies the type of error, being a combination of the following bits::
+
+		bit 0 - repeat
+		bit 1 - ecc
+		bit 2 - parity
+
+   - ``inject_enable``:
+       starts the error generation when something different than 0 is written.
+
+   All inject vars can be read. root permission is needed for write.
+
+   Datasheet states that the error will only be generated after a write on an
+   address that matches inject_addrmatch. It seems, however, that reading will
+   also produce an error.
+
+   For example, the following code will generate an error for any write access
+   at socket 0, on any DIMM/address on channel 2::
+
+	echo 2 >/sys/devices/system/edac/mc/mc0/inject_addrmatch/channel
+	echo 2 >/sys/devices/system/edac/mc/mc0/inject_type
+	echo 64 >/sys/devices/system/edac/mc/mc0/inject_eccmask
+	echo 3 >/sys/devices/system/edac/mc/mc0/inject_section
+	echo 1 >/sys/devices/system/edac/mc/mc0/inject_enable
+	dd if=/dev/mem of=/dev/null seek=16k bs=4k count=1 >& /dev/null
+
+   For socket 1, it is needed to replace "mc0" by "mc1" at the above
+   commands.
+
+   The generated error message will look like::
+
+	EDAC MC0: UE row 0, channel-a= 0 channel-b= 0 labels "-": NON_FATAL (addr = 0x0075b980, socket=0, Dimm=0, Channel=2, syndrome=0x00000040, count=1, Err=8c0000400001009f:4000080482 (read error: read ECC error))
+
+3) Corrected Error memory register counters
+
+   Those newer MCs have some registers to count memory errors. The driver
+   uses those registers to report Corrected Errors on devices with Registered
+   DIMMs.
+
+   However, those counters don't work with Unregistered DIMM. As the chipset
+   offers some counters that also work with UDIMMs (but with a worse level of
+   granularity than the default ones), the driver exposes those registers for
+   UDIMM memories.
+
+   They can be read by looking at the contents of ``all_channel_counts/``::
+
+     $ for i in /sys/devices/system/edac/mc/mc0/all_channel_counts/*; do echo $i; cat $i; done
+	/sys/devices/system/edac/mc/mc0/all_channel_counts/udimm0
+	0
+	/sys/devices/system/edac/mc/mc0/all_channel_counts/udimm1
+	0
+	/sys/devices/system/edac/mc/mc0/all_channel_counts/udimm2
+	0
+
+   What happens here is that errors on different csrows, but at the same
+   dimm number will increment the same counter.
+   So, in this memory mapping::
+
+	csrow0: channel 0, dimm0
+	csrow1: channel 0, dimm1
+	csrow2: channel 1, dimm0
+	csrow3: channel 2, dimm0
+
+   The hardware will increment udimm0 for an error at the first dimm at either
+   csrow0, csrow2  or csrow3;
+
+   The hardware will increment udimm1 for an error at the second dimm at either
+   csrow0, csrow2  or csrow3;
+
+   The hardware will increment udimm2 for an error at the third dimm at either
+   csrow0, csrow2  or csrow3;
+
+4) Standard error counters
+
+   The standard error counters are generated when an mcelog error is received
+   by the driver. Since, with UDIMM, this is counted by software, it is
+   possible that some errors could be lost. With RDIMM's, they display the
+   contents of the registers
+
+Reference documents used on ``amd64_edac``
+------------------------------------------
+
+``amd64_edac`` module is based on the following documents
+(available from http://support.amd.com/en-us/search/tech-docs):
+
+1. :Title:  BIOS and Kernel Developer's Guide for AMD Athlon 64 and AMD
+	   Opteron Processors
+   :AMD publication #: 26094
+   :Revision: 3.26
+   :Link: http://support.amd.com/TechDocs/26094.PDF
+
+2. :Title:  BIOS and Kernel Developer's Guide for AMD NPT Family 0Fh
+	   Processors
+   :AMD publication #: 32559
+   :Revision: 3.00
+   :Issue Date: May 2006
+   :Link: http://support.amd.com/TechDocs/32559.pdf
+
+3. :Title:  BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h
+	   Processors
+   :AMD publication #: 31116
+   :Revision: 3.00
+   :Issue Date: September 07, 2007
+   :Link: http://support.amd.com/TechDocs/31116.pdf
+
+4. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h
+	  Models 30h-3Fh Processors
+   :AMD publication #: 49125
+   :Revision: 3.06
+   :Issue Date: 2/12/2015 (latest release)
+   :Link: http://support.amd.com/TechDocs/49125_15h_Models_30h-3Fh_BKDG.pdf
+
+5. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 15h
+	  Models 60h-6Fh Processors
+   :AMD publication #: 50742
+   :Revision: 3.01
+   :Issue Date: 7/23/2015 (latest release)
+   :Link: http://support.amd.com/TechDocs/50742_15h_Models_60h-6Fh_BKDG.pdf
+
+6. :Title: BIOS and Kernel Developer's Guide (BKDG) for AMD Family 16h
+	  Models 00h-0Fh Processors
+   :AMD publication #: 48751
+   :Revision: 3.03
+   :Issue Date: 2/23/2015 (latest release)
+   :Link: http://support.amd.com/TechDocs/48751_16h_bkdg.pdf
+
+Credits
+=======
+
+* Written by Doug Thompson <dougthompson@xmission.com>
+
+  - 7 Dec 2005
+  - 17 Jul 2007	Updated
+
+* |copy| Mauro Carvalho Chehab
+
+  - 05 Aug 2009	Nehalem interface
+  - 26 Oct 2016 Converted to ReST and cleanups at the Nehalem section
+
+* EDAC authors/maintainers:
+
+  - Doug Thompson, Dave Jiang, Dave Peterson et al,
+  - Mauro Carvalho Chehab
+  - Borislav Petkov
+  - original author: Thayne Harbaugh
diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst
new file mode 100644
index 000000000..77fec1de6
--- /dev/null
+++ b/Documentation/admin-guide/README.rst
@@ -0,0 +1,360 @@
+.. _readme:
+
+Linux kernel release 6.x <http://kernel.org/>
+=============================================
+
+These are the release notes for Linux version 6.  Read them carefully,
+as they tell you what this is all about, explain how to install the
+kernel, and what to do if something goes wrong.
+
+What is Linux?
+--------------
+
+  Linux is a clone of the operating system Unix, written from scratch by
+  Linus Torvalds with assistance from a loosely-knit team of hackers across
+  the Net. It aims towards POSIX and Single UNIX Specification compliance.
+
+  It has all the features you would expect in a modern fully-fledged Unix,
+  including true multitasking, virtual memory, shared libraries, demand
+  loading, shared copy-on-write executables, proper memory management,
+  and multistack networking including IPv4 and IPv6.
+
+  It is distributed under the GNU General Public License v2 - see the
+  accompanying COPYING file for more details.
+
+On what hardware does it run?
+-----------------------------
+
+  Although originally developed first for 32-bit x86-based PCs (386 or higher),
+  today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
+  UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
+  IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64 Xtensa, and
+  ARC architectures.
+
+  Linux is easily portable to most general-purpose 32- or 64-bit architectures
+  as long as they have a paged memory management unit (PMMU) and a port of the
+  GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
+  also been ported to a number of architectures without a PMMU, although
+  functionality is then obviously somewhat limited.
+  Linux has also been ported to itself. You can now run the kernel as a
+  userspace application - this is called UserMode Linux (UML).
+
+Documentation
+-------------
+
+ - There is a lot of documentation available both in electronic form on
+   the Internet and in books, both Linux-specific and pertaining to
+   general UNIX questions.  I'd recommend looking into the documentation
+   subdirectories on any Linux FTP site for the LDP (Linux Documentation
+   Project) books.  This README is not meant to be documentation on the
+   system: there are much better sources available.
+
+ - There are various README files in the Documentation/ subdirectory:
+   these typically contain kernel-specific installation notes for some
+   drivers for example. Please read the
+   :ref:`Documentation/process/changes.rst <changes>` file, as it
+   contains information about the problems which may result from upgrading
+   your kernel.
+
+Installing the kernel source
+----------------------------
+
+ - If you install the full sources, put the kernel tarball in a
+   directory where you have permissions (e.g. your home directory) and
+   unpack it::
+
+     xz -cd linux-6.x.tar.xz | tar xvf -
+
+   Replace "X" with the version number of the latest kernel.
+
+   Do NOT use the /usr/src/linux area! This area has a (usually
+   incomplete) set of kernel headers that are used by the library header
+   files.  They should match the library, and not get messed up by
+   whatever the kernel-du-jour happens to be.
+
+ - You can also upgrade between 6.x releases by patching.  Patches are
+   distributed in the xz format.  To install by patching, get all the
+   newer patch files, enter the top level directory of the kernel source
+   (linux-6.x) and execute::
+
+     xz -cd ../patch-6.x.xz | patch -p1
+
+   Replace "x" for all versions bigger than the version "x" of your current
+   source tree, **in_order**, and you should be ok.  You may want to remove
+   the backup files (some-file-name~ or some-file-name.orig), and make sure
+   that there are no failed patches (some-file-name# or some-file-name.rej).
+   If there are, either you or I have made a mistake.
+
+   Unlike patches for the 6.x kernels, patches for the 6.x.y kernels
+   (also known as the -stable kernels) are not incremental but instead apply
+   directly to the base 6.x kernel.  For example, if your base kernel is 6.0
+   and you want to apply the 6.0.3 patch, you must not first apply the 6.0.1
+   and 6.0.2 patches. Similarly, if you are running kernel version 6.0.2 and
+   want to jump to 6.0.3, you must first reverse the 6.0.2 patch (that is,
+   patch -R) **before** applying the 6.0.3 patch. You can read more on this in
+   :ref:`Documentation/process/applying-patches.rst <applying_patches>`.
+
+   Alternatively, the script patch-kernel can be used to automate this
+   process.  It determines the current kernel version and applies any
+   patches found::
+
+     linux/scripts/patch-kernel linux
+
+   The first argument in the command above is the location of the
+   kernel source.  Patches are applied from the current directory, but
+   an alternative directory can be specified as the second argument.
+
+ - Make sure you have no stale .o files and dependencies lying around::
+
+     cd linux
+     make mrproper
+
+   You should now have the sources correctly installed.
+
+Software requirements
+---------------------
+
+   Compiling and running the 6.x kernels requires up-to-date
+   versions of various software packages.  Consult
+   :ref:`Documentation/process/changes.rst <changes>` for the minimum version numbers
+   required and how to get updates for these packages.  Beware that using
+   excessively old versions of these packages can cause indirect
+   errors that are very difficult to track down, so don't assume that
+   you can just update packages when obvious problems arise during
+   build or operation.
+
+Build directory for the kernel
+------------------------------
+
+   When compiling the kernel, all output files will per default be
+   stored together with the kernel source code.
+   Using the option ``make O=output/dir`` allows you to specify an alternate
+   place for the output files (including .config).
+   Example::
+
+     kernel source code: /usr/src/linux-6.x
+     build directory:    /home/name/build/kernel
+
+   To configure and build the kernel, use::
+
+     cd /usr/src/linux-6.x
+     make O=/home/name/build/kernel menuconfig
+     make O=/home/name/build/kernel
+     sudo make O=/home/name/build/kernel modules_install install
+
+   Please note: If the ``O=output/dir`` option is used, then it must be
+   used for all invocations of make.
+
+Configuring the kernel
+----------------------
+
+   Do not skip this step even if you are only upgrading one minor
+   version.  New configuration options are added in each release, and
+   odd problems will turn up if the configuration files are not set up
+   as expected.  If you want to carry your existing configuration to a
+   new version with minimal work, use ``make oldconfig``, which will
+   only ask you for the answers to new questions.
+
+ - Alternative configuration commands are::
+
+     "make config"      Plain text interface.
+
+     "make menuconfig"  Text based color menus, radiolists & dialogs.
+
+     "make nconfig"     Enhanced text based color menus.
+
+     "make xconfig"     Qt based configuration tool.
+
+     "make gconfig"     GTK based configuration tool.
+
+     "make oldconfig"   Default all questions based on the contents of
+                        your existing ./.config file and asking about
+                        new config symbols.
+
+     "make olddefconfig"
+                        Like above, but sets new symbols to their default
+                        values without prompting.
+
+     "make defconfig"   Create a ./.config file by using the default
+                        symbol values from either arch/$ARCH/configs/defconfig
+                        or arch/$ARCH/configs/${PLATFORM}_defconfig,
+                        depending on the architecture.
+
+     "make ${PLATFORM}_defconfig"
+                        Create a ./.config file by using the default
+                        symbol values from
+                        arch/$ARCH/configs/${PLATFORM}_defconfig.
+                        Use "make help" to get a list of all available
+                        platforms of your architecture.
+
+     "make allyesconfig"
+                        Create a ./.config file by setting symbol
+                        values to 'y' as much as possible.
+
+     "make allmodconfig"
+                        Create a ./.config file by setting symbol
+                        values to 'm' as much as possible.
+
+     "make allnoconfig" Create a ./.config file by setting symbol
+                        values to 'n' as much as possible.
+
+     "make randconfig"  Create a ./.config file by setting symbol
+                        values to random values.
+
+     "make localmodconfig" Create a config based on current config and
+                           loaded modules (lsmod). Disables any module
+                           option that is not needed for the loaded modules.
+
+                           To create a localmodconfig for another machine,
+                           store the lsmod of that machine into a file
+                           and pass it in as a LSMOD parameter.
+
+                           Also, you can preserve modules in certain folders
+                           or kconfig files by specifying their paths in
+                           parameter LMC_KEEP.
+
+                   target$ lsmod > /tmp/mylsmod
+                   target$ scp /tmp/mylsmod host:/tmp
+
+                   host$ make LSMOD=/tmp/mylsmod \
+                           LMC_KEEP="drivers/usb:drivers/gpu:fs" \
+                           localmodconfig
+
+                           The above also works when cross compiling.
+
+     "make localyesconfig" Similar to localmodconfig, except it will convert
+                           all module options to built in (=y) options. You can
+                           also preserve modules by LMC_KEEP.
+
+     "make kvm_guest.config"   Enable additional options for kvm guest kernel
+                               support.
+
+     "make xen.config"   Enable additional options for xen dom0 guest kernel
+                         support.
+
+     "make tinyconfig"  Configure the tiniest possible kernel.
+
+   You can find more information on using the Linux kernel config tools
+   in Documentation/kbuild/kconfig.rst.
+
+ - NOTES on ``make config``:
+
+    - Having unnecessary drivers will make the kernel bigger, and can
+      under some circumstances lead to problems: probing for a
+      nonexistent controller card may confuse your other controllers.
+
+    - A kernel with math-emulation compiled in will still use the
+      coprocessor if one is present: the math emulation will just
+      never get used in that case.  The kernel will be slightly larger,
+      but will work on different machines regardless of whether they
+      have a math coprocessor or not.
+
+    - The "kernel hacking" configuration details usually result in a
+      bigger or slower kernel (or both), and can even make the kernel
+      less stable by configuring some routines to actively try to
+      break bad code to find kernel problems (kmalloc()).  Thus you
+      should probably answer 'n' to the questions for "development",
+      "experimental", or "debugging" features.
+
+Compiling the kernel
+--------------------
+
+ - Make sure you have at least gcc 8.1 available.
+   For more information, refer to :ref:`Documentation/process/changes.rst <changes>`.
+
+ - Do a ``make`` to create a compressed kernel image. It is also possible to do
+   ``make install`` if you have lilo installed or if your distribution has an
+   install script recognised by the kernel's installer. Most popular
+   distributions will have a recognized install script. You may want to
+   check your distribution's setup first.
+
+   To do the actual install, you have to be root, but none of the normal
+   build should require that. Don't take the name of root in vain.
+
+ - If you configured any of the parts of the kernel as ``modules``, you
+   will also have to do ``make modules_install``.
+
+ - Verbose kernel compile/build output:
+
+   Normally, the kernel build system runs in a fairly quiet mode (but not
+   totally silent).  However, sometimes you or other kernel developers need
+   to see compile, link, or other commands exactly as they are executed.
+   For this, use "verbose" build mode.  This is done by passing
+   ``V=1`` to the ``make`` command, e.g.::
+
+     make V=1 all
+
+   To have the build system also tell the reason for the rebuild of each
+   target, use ``V=2``.  The default is ``V=0``.
+
+ - Keep a backup kernel handy in case something goes wrong.  This is
+   especially true for the development releases, since each new release
+   contains new code which has not been debugged.  Make sure you keep a
+   backup of the modules corresponding to that kernel, as well.  If you
+   are installing a new kernel with the same version number as your
+   working kernel, make a backup of your modules directory before you
+   do a ``make modules_install``.
+
+   Alternatively, before compiling, use the kernel config option
+   "LOCALVERSION" to append a unique suffix to the regular kernel version.
+   LOCALVERSION can be set in the "General Setup" menu.
+
+ - In order to boot your new kernel, you'll need to copy the kernel
+   image (e.g. .../linux/arch/x86/boot/bzImage after compilation)
+   to the place where your regular bootable kernel is found.
+
+ - Booting a kernel directly from a storage device without the assistance
+   of a bootloader such as LILO or GRUB, is no longer supported in BIOS
+   (non-EFI systems). On UEFI/EFI systems, however, you can use EFISTUB
+   which allows the motherboard to boot directly to the kernel.
+   On modern workstations and desktops, it's generally recommended to use a
+   bootloader as difficulties can arise with multiple kernels and secure boot.
+   For more details on EFISTUB,
+   see "Documentation/admin-guide/efi-stub.rst".
+
+ - It's important to note that as of 2016 LILO (LInux LOader) is no longer in
+   active development, though as it was extremely popular, it often comes up
+   in documentation. Popular alternatives include GRUB2, rEFInd, Syslinux,
+   systemd-boot, or EFISTUB. For various reasons, it's not recommended to use
+   software that's no longer in active development.
+
+ - Chances are your distribution includes an install script and running
+   ``make install`` will be all that's needed. Should that not be the case
+   you'll have to identify your bootloader and reference its documentation or
+   configure your EFI.
+
+Legacy LILO Instructions
+------------------------
+
+
+ - If you use LILO the kernel images are specified in the file /etc/lilo.conf.
+   The kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
+   /boot/bzImage. To use the new kernel, save a copy of the old image and copy
+   the new image over the old one. Then, you MUST RERUN LILO to update the
+   loading map! If you don't, you won't be able to boot the new kernel image.
+
+ - Reinstalling LILO is usually a matter of running /sbin/lilo. You may wish
+   to edit /etc/lilo.conf to specify an entry for your old kernel image
+   (say, /vmlinux.old) in case the new one does not work. See the LILO docs
+   for more information.
+
+ - After reinstalling LILO, you should be all set. Shutdown the system,
+   reboot, and enjoy!
+
+ - If you ever need to change the default root device, video mode, etc. in the
+   kernel image, use your bootloader's boot options where appropriate. No need
+   to recompile the kernel to change these parameters.
+
+ - Reboot with the new kernel and enjoy.
+
+
+If something goes wrong
+-----------------------
+
+If you have problems that seem to be due to kernel bugs, please follow the
+instructions at 'Documentation/admin-guide/reporting-issues.rst'.
+
+Hints on understanding kernel bug reports are in
+'Documentation/admin-guide/bug-hunting.rst'. More on debugging the kernel
+with gdb is in 'Documentation/process/debugging/gdb-kernel-debugging.rst' and
+'Documentation/process/debugging/kgdb.rst'.
diff --git a/Documentation/admin-guide/abi-obsolete-files.rst b/Documentation/admin-guide/abi-obsolete-files.rst
new file mode 100644
index 000000000..3061a916b
--- /dev/null
+++ b/Documentation/admin-guide/abi-obsolete-files.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Obsolete ABI Files
+==================
+
+.. kernel-abi:: obsolete
+   :no-symbols:
diff --git a/Documentation/admin-guide/abi-obsolete.rst b/Documentation/admin-guide/abi-obsolete.rst
new file mode 100644
index 000000000..640f3903e
--- /dev/null
+++ b/Documentation/admin-guide/abi-obsolete.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+ABI obsolete symbols
+====================
+
+Documents interfaces that are still remaining in the kernel, but are
+marked to be removed at some later point in time.
+
+The description of the interface will document the reason why it is
+obsolete and when it can be expected to be removed.
+
+.. kernel-abi:: obsolete
+   :no-files:
diff --git a/Documentation/admin-guide/abi-removed-files.rst b/Documentation/admin-guide/abi-removed-files.rst
new file mode 100644
index 000000000..f1bdfadd2
--- /dev/null
+++ b/Documentation/admin-guide/abi-removed-files.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Removed ABI Files
+=================
+
+.. kernel-abi:: removed
+   :no-symbols:
diff --git a/Documentation/admin-guide/abi-removed.rst b/Documentation/admin-guide/abi-removed.rst
new file mode 100644
index 000000000..88832d3ea
--- /dev/null
+++ b/Documentation/admin-guide/abi-removed.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+ABI removed symbols
+===================
+
+.. kernel-abi:: removed
+   :no-files:
diff --git a/Documentation/admin-guide/abi-stable-files.rst b/Documentation/admin-guide/abi-stable-files.rst
new file mode 100644
index 000000000..f867738fc
--- /dev/null
+++ b/Documentation/admin-guide/abi-stable-files.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Stable ABI Files
+================
+
+.. kernel-abi:: stable
+   :no-symbols:
diff --git a/Documentation/admin-guide/abi-stable.rst b/Documentation/admin-guide/abi-stable.rst
new file mode 100644
index 000000000..528c68401
--- /dev/null
+++ b/Documentation/admin-guide/abi-stable.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+ABI stable symbols
+==================
+
+Documents the interfaces that the developer has defined to be stable.
+
+Userspace programs are free to use these interfaces with no
+restrictions, and backward compatibility for them will be guaranteed
+for at least 2 years.
+
+Most interfaces (like syscalls) are expected to never change and always
+be available.
+
+.. kernel-abi:: stable
+   :no-files:
diff --git a/Documentation/admin-guide/abi-testing-files.rst b/Documentation/admin-guide/abi-testing-files.rst
new file mode 100644
index 000000000..1da868e42
--- /dev/null
+++ b/Documentation/admin-guide/abi-testing-files.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Testing ABI Files
+=================
+
+.. kernel-abi:: testing
+   :no-symbols:
diff --git a/Documentation/admin-guide/abi-testing.rst b/Documentation/admin-guide/abi-testing.rst
new file mode 100644
index 000000000..6153ebd38
--- /dev/null
+++ b/Documentation/admin-guide/abi-testing.rst
@@ -0,0 +1,22 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+ABI testing symbols
+===================
+
+Documents interfaces that are felt to be stable,
+as the main development of this interface has been completed.
+
+The interface can be changed to add new features, but the
+current interface will not break by doing this, unless grave
+errors or security problems are found in them.
+
+Userspace programs can start to rely on these interfaces, but they must
+be aware of changes that can occur before these interfaces move to
+be marked stable.
+
+Programs that use these interfaces are strongly encouraged to add their
+name to the description of these interfaces, so that the kernel
+developers can easily notify them if any changes occur.
+
+.. kernel-abi:: testing
+   :no-files:
diff --git a/Documentation/admin-guide/abi.rst b/Documentation/admin-guide/abi.rst
new file mode 100644
index 000000000..c6039359e
--- /dev/null
+++ b/Documentation/admin-guide/abi.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+Linux ABI description
+=====================
+
+.. kernel-abi:: README
+
+ABI symbols
+-----------
+
+.. toctree::
+   :maxdepth: 2
+
+   abi-stable
+   abi-testing
+   abi-obsolete
+   abi-removed
+
+ABI files
+---------
+
+.. toctree::
+   :maxdepth: 2
+
+   abi-stable-files
+   abi-testing-files
+   abi-obsolete-files
+   abi-removed-files
diff --git a/Documentation/admin-guide/acpi/cppc_sysfs.rst b/Documentation/admin-guide/acpi/cppc_sysfs.rst
new file mode 100644
index 000000000..36981c667
--- /dev/null
+++ b/Documentation/admin-guide/acpi/cppc_sysfs.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================================================
+Collaborative Processor Performance Control (CPPC)
+==================================================
+
+.. _cppc_sysfs:
+
+CPPC
+====
+
+CPPC defined in the ACPI spec describes a mechanism for the OS to manage the
+performance of a logical processor on a contiguous and abstract performance
+scale. CPPC exposes a set of registers to describe abstract performance scale,
+to request performance levels and to measure per-cpu delivered performance.
+
+For more details on CPPC please refer to the ACPI specification at:
+
+http://uefi.org/specifications
+
+Some of the CPPC registers are exposed via sysfs under::
+
+  /sys/devices/system/cpu/cpuX/acpi_cppc/
+
+for each cpu X::
+
+  $ ls -lR  /sys/devices/system/cpu/cpu0/acpi_cppc/
+  /sys/devices/system/cpu/cpu0/acpi_cppc/:
+  total 0
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 feedback_ctrs
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 highest_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_freq
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_nonlinear_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 lowest_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 nominal_freq
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 nominal_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 reference_perf
+  -r--r--r-- 1 root root 65536 Mar  5 19:38 wraparound_time
+
+* highest_perf : Highest performance of this processor (abstract scale).
+* nominal_perf : Highest sustained performance of this processor
+  (abstract scale).
+* lowest_nonlinear_perf : Lowest performance of this processor with nonlinear
+  power savings (abstract scale).
+* lowest_perf : Lowest performance of this processor (abstract scale).
+
+* lowest_freq : CPU frequency corresponding to lowest_perf (in MHz).
+* nominal_freq : CPU frequency corresponding to nominal_perf (in MHz).
+  The above frequencies should only be used to report processor performance in
+  frequency instead of abstract scale. These values should not be used for any
+  functional decisions.
+
+* feedback_ctrs : Includes both Reference and delivered performance counter.
+  Reference counter ticks up proportional to processor's reference performance.
+  Delivered counter ticks up proportional to processor's delivered performance.
+* wraparound_time: Minimum time for the feedback counters to wraparound
+  (seconds).
+* reference_perf : Performance level at which reference performance counter
+  accumulates (abstract scale).
+
+
+Computing Average Delivered Performance
+=======================================
+
+Below describes the steps to compute the average performance delivered by
+taking two different snapshots of feedback counters at time T1 and T2.
+
+  T1: Read feedback_ctrs as fbc_t1
+      Wait or run some workload
+
+  T2: Read feedback_ctrs as fbc_t2
+
+::
+
+  delivered_counter_delta = fbc_t2[del] - fbc_t1[del]
+  reference_counter_delta = fbc_t2[ref] - fbc_t1[ref]
+
+  delivered_perf = (reference_perf x delivered_counter_delta) / reference_counter_delta
diff --git a/Documentation/admin-guide/acpi/fan_performance_states.rst b/Documentation/admin-guide/acpi/fan_performance_states.rst
new file mode 100644
index 000000000..b9e4b4d14
--- /dev/null
+++ b/Documentation/admin-guide/acpi/fan_performance_states.rst
@@ -0,0 +1,90 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+ACPI Fan Performance States
+===========================
+
+When the optional _FPS object is present under an ACPI device representing a
+fan (for example, PNP0C0B or INT3404), the ACPI fan driver creates additional
+"state*" attributes in the sysfs directory of the ACPI device in question.
+These attributes list properties of fan performance states.
+
+For more information on _FPS refer to the ACPI specification at:
+
+http://uefi.org/specifications
+
+For instance, the contents of the INT3404 ACPI device sysfs directory
+may look as follows::
+
+ $ ls -l /sys/bus/acpi/devices/INT3404:00/
+ total 0
+ ...
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state0
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state1
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state10
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state11
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state2
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state3
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state4
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state5
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state6
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state7
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state8
+ -r--r--r-- 1 root root 4096 Dec 13 20:38 state9
+ -r--r--r-- 1 root root 4096 Dec 13 01:00 status
+ ...
+
+where each of the "state*" files represents one performance state of the fan
+and contains a colon-separated list of 5 integer numbers (fields) with the
+following interpretation::
+
+  control_percent:trip_point_index:speed_rpm:noise_level_mdb:power_mw
+
+* ``control_percent``: The percent value to be used to set the fan speed to a
+  specific level using the _FSL object (0-100).
+
+* ``trip_point_index``: The active cooling trip point number that corresponds
+  to this performance state (0-9).
+
+* ``speed_rpm``: Speed of the fan in rotations per minute.
+
+* ``noise_level_mdb``: Audible noise emitted by the fan in this state in
+  millidecibels.
+
+* ``power_mw``: Power draw of the fan in this state in milliwatts.
+
+For example::
+
+ $cat /sys/bus/acpi/devices/INT3404:00/state1
+ 25:0:3200:12500:1250
+
+When a given field is not populated or its value provided by the platform
+firmware is invalid, the "not-defined" string is shown instead of the value.
+
+ACPI Fan Fine Grain Control
+=============================
+
+When _FIF object specifies support for fine grain control, then fan speed
+can be set from 0 to 100% with the recommended minimum "step size" via
+_FSL object. User can adjust fan speed using thermal sysfs cooling device.
+
+Here use can look at fan performance states for a reference speed (speed_rpm)
+and set it by changing cooling device cur_state. If the fine grain control
+is supported then user can also adjust to some other speeds which are
+not defined in the performance states.
+
+The support of fine grain control is presented via sysfs attribute
+"fine_grain_control". If fine grain control is present, this attribute
+will show "1" otherwise "0".
+
+This sysfs attribute is presented in the same directory as performance states.
+
+ACPI Fan Performance Feedback
+=============================
+
+The optional _FST object provides status information for the fan device.
+This includes field to provide current fan speed in revolutions per minute
+at which the fan is rotating.
+
+This speed is presented in the sysfs using the attribute "fan_speed_rpm",
+in the same directory as performance states.
diff --git a/Documentation/admin-guide/acpi/index.rst b/Documentation/admin-guide/acpi/index.rst
new file mode 100644
index 000000000..b078fdb8f
--- /dev/null
+++ b/Documentation/admin-guide/acpi/index.rst
@@ -0,0 +1,14 @@
+============
+ACPI Support
+============
+
+Here we document in detail how to interact with various mechanisms in
+the Linux ACPI support.
+
+.. toctree::
+   :maxdepth: 1
+
+   initrd_table_override
+   ssdt-overlays
+   cppc_sysfs
+   fan_performance_states
diff --git a/Documentation/admin-guide/acpi/initrd_table_override.rst b/Documentation/admin-guide/acpi/initrd_table_override.rst
new file mode 100644
index 000000000..bb24fa6b5
--- /dev/null
+++ b/Documentation/admin-guide/acpi/initrd_table_override.rst
@@ -0,0 +1,115 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================================
+Upgrading ACPI tables via initrd
+================================
+
+What is this about
+==================
+
+If the ACPI_TABLE_UPGRADE compile option is true, it is possible to
+upgrade the ACPI execution environment that is defined by the ACPI tables
+via upgrading the ACPI tables provided by the BIOS with an instrumented,
+modified, more recent version one, or installing brand new ACPI tables.
+
+When building initrd with kernel in a single image, option
+ACPI_TABLE_OVERRIDE_VIA_BUILTIN_INITRD should also be true for this
+feature to work.
+
+For a full list of ACPI tables that can be upgraded/installed, take a look
+at the char `*table_sigs[MAX_ACPI_SIGNATURE];` definition in
+drivers/acpi/tables.c.
+
+All ACPI tables iasl (Intel's ACPI compiler and disassembler) knows should
+be overridable, except:
+
+  - ACPI_SIG_RSDP (has a signature of 6 bytes)
+  - ACPI_SIG_FACS (does not have an ordinary ACPI table header)
+
+Both could get implemented as well.
+
+
+What is this for
+================
+
+Complain to your platform/BIOS vendor if you find a bug which is so severe
+that a workaround is not accepted in the Linux kernel. And this facility
+allows you to upgrade the buggy tables before your platform/BIOS vendor
+releases an upgraded BIOS binary.
+
+This facility can be used by platform/BIOS vendors to provide a Linux
+compatible environment without modifying the underlying platform firmware.
+
+This facility also provides a powerful feature to easily debug and test
+ACPI BIOS table compatibility with the Linux kernel by modifying old
+platform provided ACPI tables or inserting new ACPI tables.
+
+It can and should be enabled in any kernel because there is no functional
+change with not instrumented initrds.
+
+
+How does it work
+================
+::
+
+  # Extract the machine's ACPI tables:
+  cd /tmp
+  acpidump >acpidump
+  acpixtract -a acpidump
+  # Disassemble, modify and recompile them:
+  iasl -d *.dat
+  # For example add this statement into a _PRT (PCI Routing Table) function
+  # of the DSDT:
+  Store("HELLO WORLD", debug)
+  # And increase the OEM Revision. For example, before modification:
+  DefinitionBlock ("DSDT.aml", "DSDT", 2, "INTEL ", "TEMPLATE", 0x00000000)
+  # After modification:
+  DefinitionBlock ("DSDT.aml", "DSDT", 2, "INTEL ", "TEMPLATE", 0x00000001)
+  iasl -sa dsdt.dsl
+  # Add the raw ACPI tables to an uncompressed cpio archive.
+  # They must be put into a /kernel/firmware/acpi directory inside the cpio
+  # archive. Note that if the table put here matches a platform table
+  # (similar Table Signature, and similar OEMID, and similar OEM Table ID)
+  # with a more recent OEM Revision, the platform table will be upgraded by
+  # this table. If the table put here doesn't match a platform table
+  # (dissimilar Table Signature, or dissimilar OEMID, or dissimilar OEM Table
+  # ID), this table will be appended.
+  mkdir -p kernel/firmware/acpi
+  cp dsdt.aml kernel/firmware/acpi
+  # A maximum of "NR_ACPI_INITRD_TABLES (64)" tables are currently allowed
+  # (see osl.c):
+  iasl -sa facp.dsl
+  iasl -sa ssdt1.dsl
+  cp facp.aml kernel/firmware/acpi
+  cp ssdt1.aml kernel/firmware/acpi
+  # The uncompressed cpio archive must be the first. Other, typically
+  # compressed cpio archives, must be concatenated on top of the uncompressed
+  # one. Following command creates the uncompressed cpio archive and
+  # concatenates the original initrd on top:
+  find kernel | cpio -H newc --create > /boot/instrumented_initrd
+  cat /boot/initrd >>/boot/instrumented_initrd
+  # reboot with increased acpi debug level, e.g. boot params:
+  acpi.debug_level=0x2 acpi.debug_layer=0xFFFFFFFF
+  # and check your syslog:
+  [    1.268089] ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
+  [    1.272091] [ACPI Debug]  String [0x0B] "HELLO WORLD"
+
+iasl is able to disassemble and recompile quite a lot different,
+also static ACPI tables.
+
+
+Where to retrieve userspace tools
+=================================
+
+iasl and acpixtract are part of Intel's ACPICA project:
+https://acpica.org/
+
+and should be packaged by distributions (for example in the acpica package
+on SUSE).
+
+acpidump can be found in Len Browns pmtools:
+ftp://kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools/acpidump
+
+This tool is also part of the acpica package on SUSE.
+Alternatively, used ACPI tables can be retrieved via sysfs in latest kernels:
+/sys/firmware/acpi/tables
diff --git a/Documentation/admin-guide/acpi/ssdt-overlays.rst b/Documentation/admin-guide/acpi/ssdt-overlays.rst
new file mode 100644
index 000000000..5ea9f4a3b
--- /dev/null
+++ b/Documentation/admin-guide/acpi/ssdt-overlays.rst
@@ -0,0 +1,181 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+SSDT Overlays
+=============
+
+In order to support ACPI open-ended hardware configurations (e.g. development
+boards) we need a way to augment the ACPI configuration provided by the firmware
+image. A common example is connecting sensors on I2C / SPI buses on development
+boards.
+
+Although this can be accomplished by creating a kernel platform driver or
+recompiling the firmware image with updated ACPI tables, neither is practical:
+the former proliferates board specific kernel code while the latter requires
+access to firmware tools which are often not publicly available.
+
+Because ACPI supports external references in AML code a more practical
+way to augment firmware ACPI configuration is by dynamically loading
+user defined SSDT tables that contain the board specific information.
+
+For example, to enumerate a Bosch BMA222E accelerometer on the I2C bus of the
+Minnowboard MAX development board exposed via the LSE connector [1], the
+following ASL code can be used::
+
+    DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003)
+    {
+        External (\_SB.I2C6, DeviceObj)
+
+        Scope (\_SB.I2C6)
+        {
+            Device (STAC)
+            {
+                Name (_HID, "BMA222E")
+                Name (RBUF, ResourceTemplate ()
+                {
+                    I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80,
+                                AddressingMode7Bit, "\\_SB.I2C6", 0x00,
+                                ResourceConsumer, ,)
+                    GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000,
+                            "\\_SB.GPO2", 0x00, ResourceConsumer, , )
+                    { // Pin list
+                        0
+                    }
+                })
+
+                Method (_CRS, 0, Serialized)
+                {
+                    Return (RBUF)
+                }
+            }
+        }
+    }
+
+which can then be compiled to AML binary format::
+
+    $ iasl minnowmax.asl
+
+    Intel ACPI Component Architecture
+    ASL Optimizing Compiler version 20140214-64 [Mar 29 2014]
+    Copyright (c) 2000 - 2014 Intel Corporation
+
+    ASL Input:     minnomax.asl - 30 lines, 614 bytes, 7 keywords
+    AML Output:    minnowmax.aml - 165 bytes, 6 named objects, 1 executable opcodes
+
+[1] https://www.elinux.org/Minnowboard:MinnowMax#Low_Speed_Expansion_.28Top.29
+
+The resulting AML code can then be loaded by the kernel using one of the methods
+below.
+
+Loading ACPI SSDTs from initrd
+==============================
+
+This option allows loading of user defined SSDTs from initrd and it is useful
+when the system does not support EFI or when there is not enough EFI storage.
+
+It works in a similar way with initrd based ACPI tables override/upgrade: SSDT
+AML code must be placed in the first, uncompressed, initrd under the
+"kernel/firmware/acpi" path. Multiple files can be used and this will translate
+in loading multiple tables. Only SSDT and OEM tables are allowed. See
+initrd_table_override.txt for more details.
+
+Here is an example::
+
+    # Add the raw ACPI tables to an uncompressed cpio archive.
+    # They must be put into a /kernel/firmware/acpi directory inside the
+    # cpio archive.
+    # The uncompressed cpio archive must be the first.
+    # Other, typically compressed cpio archives, must be
+    # concatenated on top of the uncompressed one.
+    mkdir -p kernel/firmware/acpi
+    cp ssdt.aml kernel/firmware/acpi
+
+    # Create the uncompressed cpio archive and concatenate the original initrd
+    # on top:
+    find kernel | cpio -H newc --create > /boot/instrumented_initrd
+    cat /boot/initrd >>/boot/instrumented_initrd
+
+Loading ACPI SSDTs from EFI variables
+=====================================
+
+This is the preferred method, when EFI is supported on the platform, because it
+allows a persistent, OS independent way of storing the user defined SSDTs. There
+is also work underway to implement EFI support for loading user defined SSDTs
+and using this method will make it easier to convert to the EFI loading
+mechanism when that will arrive. To enable it, the
+CONFIG_EFI_CUSTOM_SSDT_OVERLAYS should be chosen to y.
+
+In order to load SSDTs from an EFI variable the ``"efivar_ssdt=..."`` kernel
+command line parameter can be used (the name has a limitation of 16 characters).
+The argument for the option is the variable name to use. If there are multiple
+variables with the same name but with different vendor GUIDs, all of them will
+be loaded.
+
+In order to store the AML code in an EFI variable the efivarfs filesystem can be
+used. It is enabled and mounted by default in /sys/firmware/efi/efivars in all
+recent distribution.
+
+Creating a new file in /sys/firmware/efi/efivars will automatically create a new
+EFI variable. Updating a file in /sys/firmware/efi/efivars will update the EFI
+variable. Please note that the file name needs to be specially formatted as
+"Name-GUID" and that the first 4 bytes in the file (little-endian format)
+represent the attributes of the EFI variable (see EFI_VARIABLE_MASK in
+include/linux/efi.h). Writing to the file must also be done with one write
+operation.
+
+For example, you can use the following bash script to create/update an EFI
+variable with the content from a given file::
+
+    #!/bin/sh -e
+
+    while [ -n "$1" ]; do
+            case "$1" in
+            "-f") filename="$2"; shift;;
+            "-g") guid="$2"; shift;;
+            *) name="$1";;
+            esac
+            shift
+    done
+
+    usage()
+    {
+            echo "Syntax: ${0##*/} -f filename [ -g guid ] name"
+            exit 1
+    }
+
+    [ -n "$name" -a -f "$filename" ] || usage
+
+    EFIVARFS="/sys/firmware/efi/efivars"
+
+    [ -d "$EFIVARFS" ] || exit 2
+
+    if stat -tf $EFIVARFS | grep -q -v de5e81e4; then
+            mount -t efivarfs none $EFIVARFS
+    fi
+
+    # try to pick up an existing GUID
+    [ -n "$guid" ] || guid=$(find "$EFIVARFS" -name "$name-*" | head -n1 | cut -f2- -d-)
+
+    # use a randomly generated GUID
+    [ -n "$guid" ] || guid="$(cat /proc/sys/kernel/random/uuid)"
+
+    # efivarfs expects all of the data in one write
+    tmp=$(mktemp)
+    /bin/echo -ne "\007\000\000\000" | cat - $filename > $tmp
+    dd if=$tmp of="$EFIVARFS/$name-$guid" bs=$(stat -c %s $tmp)
+    rm $tmp
+
+Loading ACPI SSDTs from configfs
+================================
+
+This option allows loading of user defined SSDTs from user space via the configfs
+interface. The CONFIG_ACPI_CONFIGFS option must be select and configfs must be
+mounted. In the following examples, we assume that configfs has been mounted in
+/sys/kernel/config.
+
+New tables can be loading by creating new directories in /sys/kernel/config/acpi/table
+and writing the SSDT AML code in the aml attribute::
+
+    cd /sys/kernel/config/acpi/table
+    mkdir my_ssdt
+    cat ~/ssdt.aml > my_ssdt/aml
diff --git a/Documentation/admin-guide/aoe/aoe.rst b/Documentation/admin-guide/aoe/aoe.rst
new file mode 100644
index 000000000..a05e75136
--- /dev/null
+++ b/Documentation/admin-guide/aoe/aoe.rst
@@ -0,0 +1,150 @@
+Introduction
+============
+
+ATA over Ethernet is a network protocol that provides simple access to
+block storage on the LAN.
+
+  http://support.coraid.com/documents/AoEr11.txt
+
+The EtherDrive (R) HOWTO for 2.6 and 3.x kernels is found at ...
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO.html
+
+It has many tips and hints!  Please see, especially, recommended
+tunings for virtual memory:
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
+
+The aoetools are userland programs that are designed to work with this
+driver.  The aoetools are on sourceforge.
+
+  http://aoetools.sourceforge.net/
+
+The scripts in this Documentation/admin-guide/aoe directory are intended to
+document the use of the driver and are not necessary if you install
+the aoetools.
+
+
+Creating Device Nodes
+=====================
+
+  Users of udev should find the block device nodes created
+  automatically, but to create all the necessary device nodes, use the
+  udev configuration rules provided in udev.txt (in this directory).
+
+  There is a udev-install.sh script that shows how to install these
+  rules on your system.
+
+  There is also an autoload script that shows how to edit
+  /etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
+  necessary.  Preloading the aoe module is preferable to autoloading,
+  however, because AoE discovery takes a few seconds.  It can be
+  confusing when an AoE device is not present the first time the a
+  command is run but appears a second later.
+
+Using Device Nodes
+==================
+
+  "cat /dev/etherd/err" blocks, waiting for error diagnostic output,
+  like any retransmitted packets.
+
+  "echo eth2 eth4 > /dev/etherd/interfaces" tells the aoe driver to
+  limit ATA over Ethernet traffic to eth2 and eth4.  AoE traffic from
+  untrusted networks should be ignored as a matter of security.  See
+  also the aoe_iflist driver option described below.
+
+  "echo > /dev/etherd/discover" tells the driver to find out what AoE
+  devices are available.
+
+  In the future these character devices may disappear and be replaced
+  by sysfs counterparts.  Using the commands in aoetools insulates
+  users from these implementation details.
+
+  The block devices are named like this::
+
+	e{shelf}.{slot}
+	e{shelf}.{slot}p{part}
+
+  ... so that "e0.2" is the third blade from the left (slot 2) in the
+  first shelf (shelf address zero).  That's the whole disk.  The first
+  partition on that disk would be "e0.2p1".
+
+Using sysfs
+===========
+
+  Each aoe block device in /sys/block has the extra attributes of
+  state, mac, and netif.  The state attribute is "up" when the device
+  is ready for I/O and "down" if detected but unusable.  The
+  "down,closewait" state shows that the device is still open and
+  cannot come up again until it has been closed.
+
+  The mac attribute is the ethernet address of the remote AoE device.
+  The netif attribute is the network interface on the localhost
+  through which we are communicating with the remote AoE device.
+
+  There is a script in this directory that formats this information in
+  a convenient way.  Users with aoetools should use the aoe-stat
+  command::
+
+    root@makki root# sh Documentation/admin-guide/aoe/status.sh
+       e10.0            eth3              up
+       e10.1            eth3              up
+       e10.2            eth3              up
+       e10.3            eth3              up
+       e10.4            eth3              up
+       e10.5            eth3              up
+       e10.6            eth3              up
+       e10.7            eth3              up
+       e10.8            eth3              up
+       e10.9            eth3              up
+        e4.0            eth1              up
+        e4.1            eth1              up
+        e4.2            eth1              up
+        e4.3            eth1              up
+        e4.4            eth1              up
+        e4.5            eth1              up
+        e4.6            eth1              up
+        e4.7            eth1              up
+        e4.8            eth1              up
+        e4.9            eth1              up
+
+  Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
+  option discussed below) instead of /dev/etherd/interfaces to limit
+  AoE traffic to the network interfaces in the given
+  whitespace-separated list.  Unlike the old character device, the
+  sysfs entry can be read from as well as written to.
+
+  It's helpful to trigger discovery after setting the list of allowed
+  interfaces.  The aoetools package provides an aoe-discover script
+  for this purpose.  You can also directly use the
+  /dev/etherd/discover special file described above.
+
+Driver Options
+==============
+
+  There is a boot option for the built-in aoe driver and a
+  corresponding module parameter, aoe_iflist.  Without this option,
+  all network interfaces may be used for ATA over Ethernet.  Here is a
+  usage example for the module parameter::
+
+    modprobe aoe_iflist="eth1 eth3"
+
+  The aoe_deadsecs module parameter determines the maximum number of
+  seconds that the driver will wait for an AoE device to provide a
+  response to an AoE command.  After aoe_deadsecs seconds have
+  elapsed, the AoE device will be marked as "down".  A value of zero
+  is supported for testing purposes and makes the aoe driver keep
+  trying AoE commands forever.
+
+  The aoe_maxout module parameter has a default of 128.  This is the
+  maximum number of unresponded packets that will be sent to an AoE
+  target at one time.
+
+  The aoe_dyndevs module parameter defaults to 1, meaning that the
+  driver will assign a block device minor number to a discovered AoE
+  target based on the order of its discovery.  With dynamic minor
+  device numbers in use, a greater range of AoE shelf and slot
+  addresses can be supported.  Users with udev will never have to
+  think about minor numbers.  Using aoe_dyndevs=0 allows device nodes
+  to be pre-created using a static minor-number scheme with the
+  aoe-mkshelf script in the aoetools.
diff --git a/Documentation/admin-guide/aoe/autoload.sh b/Documentation/admin-guide/aoe/autoload.sh
new file mode 100644
index 000000000..815dff469
--- /dev/null
+++ b/Documentation/admin-guide/aoe/autoload.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+# set aoe to autoload by installing the
+# aliases in /etc/modprobe.d/
+
+f=/etc/modprobe.d/aoe.conf
+
+if test ! -r $f || test ! -w $f; then
+	echo "cannot configure $f for module autoloading" 1>&2
+	exit 1
+fi
+
+grep major-152 $f >/dev/null
+if [ $? = 1 ]; then
+	echo alias block-major-152 aoe >> $f
+	echo alias char-major-152 aoe >> $f
+fi
+
diff --git a/Documentation/admin-guide/aoe/examples.rst b/Documentation/admin-guide/aoe/examples.rst
new file mode 100644
index 000000000..91f3198e5
--- /dev/null
+++ b/Documentation/admin-guide/aoe/examples.rst
@@ -0,0 +1,23 @@
+Example of udev rules
+---------------------
+
+ .. include:: udev.txt
+    :literal:
+
+Example of udev install rules script
+------------------------------------
+
+ .. literalinclude:: udev-install.sh
+    :language: shell
+
+Example script to get status
+----------------------------
+
+ .. literalinclude:: status.sh
+    :language: shell
+
+Example of AoE autoload script
+------------------------------
+
+ .. literalinclude:: autoload.sh
+    :language: shell
diff --git a/Documentation/admin-guide/aoe/index.rst b/Documentation/admin-guide/aoe/index.rst
new file mode 100644
index 000000000..564354bbc
--- /dev/null
+++ b/Documentation/admin-guide/aoe/index.rst
@@ -0,0 +1,10 @@
+=======================
+ATA over Ethernet (AoE)
+=======================
+
+.. toctree::
+    :maxdepth: 1
+
+    aoe
+    todo
+    examples
diff --git a/Documentation/admin-guide/aoe/status.sh b/Documentation/admin-guide/aoe/status.sh
new file mode 100644
index 000000000..eeec7baae
--- /dev/null
+++ b/Documentation/admin-guide/aoe/status.sh
@@ -0,0 +1,30 @@
+#! /bin/sh
+# collate and present sysfs information about AoE storage
+#
+# A more complete version of this script is aoe-stat, in the
+# aoetools.
+
+set -e
+format="%8s\t%8s\t%8s\n"
+me=`basename $0`
+sysd=${sysfs_dir:-/sys}
+
+# printf "$format" device mac netif state
+
+# Suse 9.1 Pro doesn't put /sys in /etc/mtab
+#test -z "`mount | grep sysfs`" && {
+test ! -d "$sysd/block" && {
+	echo "$me Error: sysfs is not mounted" 1>&2
+	exit 1
+}
+
+for d in `ls -d $sysd/block/etherd* 2>/dev/null | grep -v p` end; do
+	# maybe ls comes up empty, so we use "end"
+	test $d = end && continue
+
+	dev=`echo "$d" | sed 's/.*!//'`
+	printf "$format" \
+		"$dev" \
+		"`cat \"$d/netif\"`" \
+		"`cat \"$d/state\"`"
+done | sort
diff --git a/Documentation/admin-guide/aoe/todo.rst b/Documentation/admin-guide/aoe/todo.rst
new file mode 100644
index 000000000..dea8db5a3
--- /dev/null
+++ b/Documentation/admin-guide/aoe/todo.rst
@@ -0,0 +1,17 @@
+TODO
+====
+
+There is a potential for deadlock when allocating a struct sk_buff for
+data that needs to be written out to aoe storage.  If the data is
+being written from a dirty page in order to free that page, and if
+there are no other pages available, then deadlock may occur when a
+free page is needed for the sk_buff allocation.  This situation has
+not been observed, but it would be nice to eliminate any potential for
+deadlock under memory pressure.
+
+Because ATA over Ethernet is not fragmented by the kernel's IP code,
+the destructor member of the struct sk_buff is available to the aoe
+driver.  By using a mempool for allocating all but the first few
+sk_buffs, and by registering a destructor, we should be able to
+efficiently allocate sk_buffs without introducing any potential for
+deadlock.
diff --git a/Documentation/admin-guide/aoe/udev-install.sh b/Documentation/admin-guide/aoe/udev-install.sh
new file mode 100644
index 000000000..15e86f58c
--- /dev/null
+++ b/Documentation/admin-guide/aoe/udev-install.sh
@@ -0,0 +1,33 @@
+# install the aoe-specific udev rules from udev.txt into 
+# the system's udev configuration
+# 
+
+me="`basename $0`"
+
+# find udev.conf, often /etc/udev/udev.conf
+# (or environment can specify where to find udev.conf)
+#
+if test -z "$conf"; then
+	if test -r /etc/udev/udev.conf; then
+		conf=/etc/udev/udev.conf
+	else
+		conf="`find /etc -type f -name udev.conf 2> /dev/null`"
+		if test -z "$conf" || test ! -r "$conf"; then
+			echo "$me Error: no udev.conf found" 1>&2
+			exit 1
+		fi
+	fi
+fi
+
+# find the directory where udev rules are stored, often
+# /etc/udev/rules.d
+#
+rules_d="`sed -n '/^udev_rules=/{ s!udev_rules=!!; s!\"!!g; p; }' $conf`"
+if test -z "$rules_d" ; then
+	rules_d=/etc/udev/rules.d
+fi
+if test ! -d "$rules_d"; then
+	echo "$me Error: cannot find udev rules directory" 1>&2
+	exit 1
+fi
+sh -xc "cp `dirname $0`/udev.txt $rules_d/60-aoe.rules"
diff --git a/Documentation/admin-guide/aoe/udev.txt b/Documentation/admin-guide/aoe/udev.txt
new file mode 100644
index 000000000..d55ecb411
--- /dev/null
+++ b/Documentation/admin-guide/aoe/udev.txt
@@ -0,0 +1,26 @@
+# These rules tell udev what device nodes to create for aoe support.
+# They may be installed along the following lines.  Check the section
+# 8 udev manpage to see whether your udev supports SUBSYSTEM, and
+# whether it uses one or two equal signs for SUBSYSTEM and KERNEL.
+#
+#   ecashin@makki ~$ su
+#   Password:
+#   bash# find /etc -type f -name udev.conf
+#   /etc/udev/udev.conf
+#   bash# grep udev_rules= /etc/udev/udev.conf
+#   udev_rules="/etc/udev/rules.d/"
+#   bash# ls /etc/udev/rules.d/
+#   10-wacom.rules  50-udev.rules
+#   bash# cp /path/to/linux/Documentation/admin-guide/aoe/udev.txt \
+#           /etc/udev/rules.d/60-aoe.rules
+#
+
+# aoe char devices
+SUBSYSTEM=="aoe", KERNEL=="discover",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="err",	NAME="etherd/%k", GROUP="disk", MODE="0440"
+SUBSYSTEM=="aoe", KERNEL=="interfaces",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="revalidate",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="flush",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+
+# aoe block devices
+KERNEL=="etherd*",       GROUP="disk"
diff --git a/Documentation/admin-guide/auxdisplay/cfag12864b.rst b/Documentation/admin-guide/auxdisplay/cfag12864b.rst
new file mode 100644
index 000000000..da385d851
--- /dev/null
+++ b/Documentation/admin-guide/auxdisplay/cfag12864b.rst
@@ -0,0 +1,98 @@
+===================================
+cfag12864b LCD Driver Documentation
+===================================
+
+:License:		GPLv2
+:Author & Maintainer:	Miguel Ojeda <ojeda@kernel.org>
+:Date:			2006-10-27
+
+
+
+.. INDEX
+
+	1. DRIVER INFORMATION
+	2. DEVICE INFORMATION
+	3. WIRING
+	4. USERSPACE PROGRAMMING
+
+1. Driver Information
+---------------------
+
+This driver supports a cfag12864b LCD.
+
+
+2. Device Information
+---------------------
+
+:Manufacturer:	Crystalfontz
+:Device Name:	Crystalfontz 12864b LCD Series
+:Device Code:	cfag12864b
+:Webpage:	http://www.crystalfontz.com
+:Device Webpage: http://www.crystalfontz.com/products/12864b/
+:Type:		LCD (Liquid Crystal Display)
+:Width:		128
+:Height:	64
+:Colors:	2 (B/N)
+:Controller:	ks0108
+:Controllers:	2
+:Pages:		8 each controller
+:Addresses:	64 each page
+:Data size:	1 byte each address
+:Memory size:	2 * 8 * 64 * 1 = 1024 bytes = 1 Kbyte
+
+
+3. Wiring
+---------
+
+The cfag12864b LCD Series don't have official wiring.
+
+The common wiring is done to the parallel port as shown::
+
+  Parallel Port                          cfag12864b
+
+    Name Pin#                            Pin# Name
+
+  Strobe ( 1)------------------------------(17) Enable
+  Data 0 ( 2)------------------------------( 4) Data 0
+  Data 1 ( 3)------------------------------( 5) Data 1
+  Data 2 ( 4)------------------------------( 6) Data 2
+  Data 3 ( 5)------------------------------( 7) Data 3
+  Data 4 ( 6)------------------------------( 8) Data 4
+  Data 5 ( 7)------------------------------( 9) Data 5
+  Data 6 ( 8)------------------------------(10) Data 6
+  Data 7 ( 9)------------------------------(11) Data 7
+         (10)                      [+5v]---( 1) Vdd
+         (11)                      [GND]---( 2) Ground
+         (12)                      [+5v]---(14) Reset
+         (13)                      [GND]---(15) Read / Write
+    Line (14)------------------------------(13) Controller Select 1
+         (15)
+    Init (16)------------------------------(12) Controller Select 2
+  Select (17)------------------------------(16) Data / Instruction
+  Ground (18)---[GND]              [+5v]---(19) LED +
+  Ground (19)---[GND]
+  Ground (20)---[GND]              E    A             Values:
+  Ground (21)---[GND]       [GND]---[P1]---(18) Vee    - R = Resistor = 22 ohm
+  Ground (22)---[GND]                |                 - P1 = Preset = 10 Kohm
+  Ground (23)---[GND]       ----   S ------( 3) V0     - P2 = Preset = 1 Kohm
+  Ground (24)---[GND]       |  |
+  Ground (25)---[GND] [GND]---[P2]---[R]---(20) LED -
+
+
+4. Userspace Programming
+------------------------
+
+The cfag12864bfb describes a framebuffer device (/dev/fbX).
+
+It has a size of 1024 bytes = 1 Kbyte.
+Each bit represents one pixel. If the bit is high, the pixel will
+turn on. If the pixel is low, the pixel will turn off.
+
+You can use the framebuffer as a file: fopen, fwrite, fclose...
+Although the LCD won't get updated until the next refresh time arrives.
+
+Also, you can mmap the framebuffer: open & mmap, munmap & close...
+which is the best option for most uses.
+
+Check samples/auxdisplay/cfag12864b-example.c
+for a real working userspace complete program with usage examples.
diff --git a/Documentation/admin-guide/auxdisplay/index.rst b/Documentation/admin-guide/auxdisplay/index.rst
new file mode 100644
index 000000000..31eae0825
--- /dev/null
+++ b/Documentation/admin-guide/auxdisplay/index.rst
@@ -0,0 +1,9 @@
+=========================
+Auxiliary Display Support
+=========================
+
+.. toctree::
+    :maxdepth: 1
+
+    ks0108.rst
+    cfag12864b.rst
diff --git a/Documentation/admin-guide/auxdisplay/ks0108.rst b/Documentation/admin-guide/auxdisplay/ks0108.rst
new file mode 100644
index 000000000..a7d3fe509
--- /dev/null
+++ b/Documentation/admin-guide/auxdisplay/ks0108.rst
@@ -0,0 +1,50 @@
+==========================================
+ks0108 LCD Controller Driver Documentation
+==========================================
+
+:License:		GPLv2
+:Author & Maintainer:	Miguel Ojeda <ojeda@kernel.org>
+:Date:			2006-10-27
+
+
+
+.. INDEX
+
+	1. DRIVER INFORMATION
+	2. DEVICE INFORMATION
+	3. WIRING
+
+
+1. Driver Information
+---------------------
+
+This driver supports the ks0108 LCD controller.
+
+
+2. Device Information
+---------------------
+
+:Manufacturer:	Samsung
+:Device Name:	KS0108 LCD Controller
+:Device Code:	ks0108
+:Webpage:	-
+:Device Webpage: -
+:Type:		LCD Controller (Liquid Crystal Display Controller)
+:Width:		64
+:Height:	64
+:Colors:	2 (B/N)
+:Pages:		8
+:Addresses:	64 each page
+:Data size:	1 byte each address
+:Memory size:	8 * 64 * 1 = 512 bytes
+
+
+3. Wiring
+---------
+
+The driver supports data parallel port wiring.
+
+If you aren't building LCD related hardware, you should check
+your LCD specific wiring information in the same folder.
+
+For example, check Documentation/admin-guide/auxdisplay/cfag12864b.rst
diff --git a/Documentation/admin-guide/bcache.rst b/Documentation/admin-guide/bcache.rst
new file mode 100644
index 000000000..325816edb
--- /dev/null
+++ b/Documentation/admin-guide/bcache.rst
@@ -0,0 +1,644 @@
+============================
+A block layer cache (bcache)
+============================
+
+Say you've got a big slow raid 6, and an ssd or three. Wouldn't it be
+nice if you could use them as cache... Hence bcache.
+
+The bcache wiki can be found at:
+  https://bcache.evilpiepirate.org
+
+This is the git repository of bcache-tools:
+  https://git.kernel.org/pub/scm/linux/kernel/git/colyli/bcache-tools.git/
+
+The latest bcache kernel code can be found from mainline Linux kernel:
+  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
+
+It's designed around the performance characteristics of SSDs - it only allocates
+in erase block sized buckets, and it uses a hybrid btree/log to track cached
+extents (which can be anywhere from a single sector to the bucket size). It's
+designed to avoid random writes at all costs.
+
+Both writethrough and writeback caching are supported. Writeback defaults to
+off, but can be switched on and off arbitrarily at runtime. Bcache goes to
+great lengths to protect your data - it reliably handles unclean shutdown. (It
+doesn't even have a notion of a clean shutdown; bcache simply doesn't return
+writes as completed until they're on stable storage).
+
+Writeback caching can use most of the cache for buffering writes - writing
+dirty data to the backing device is always done sequentially, scanning from the
+start to the end of the index.
+
+Since random IO is what SSDs excel at, there generally won't be much benefit
+to caching large sequential IO. Bcache detects sequential IO and skips it;
+it also keeps a rolling average of the IO sizes per task, and as long as the
+average is above the cutoff it will skip all IO from that task - instead of
+caching the first 512k after every seek. Backups and large file copies should
+thus entirely bypass the cache.
+
+In the event of a data IO error on the flash it will try to recover by reading
+from disk or invalidating cache entries.  For unrecoverable errors (meta data
+or dirty data), caching is automatically disabled; if dirty data was present
+in the cache it first disables writeback caching and waits for all dirty data
+to be flushed.
+
+Getting started:
+You'll need bcache util from the bcache-tools repository. Both the cache device
+and backing device must be formatted before use::
+
+  bcache make -B /dev/sdb
+  bcache make -C /dev/sdc
+
+`bcache make` has the ability to format multiple devices at the same time - if
+you format your backing devices and cache device at the same time, you won't
+have to manually attach::
+
+  bcache make -B /dev/sda /dev/sdb -C /dev/sdc
+
+If your bcache-tools is not updated to latest version and does not have the
+unified `bcache` utility, you may use the legacy `make-bcache` utility to format
+bcache device with same -B and -C parameters.
+
+bcache-tools now ships udev rules, and bcache devices are known to the kernel
+immediately.  Without udev, you can manually register devices like this::
+
+  echo /dev/sdb > /sys/fs/bcache/register
+  echo /dev/sdc > /sys/fs/bcache/register
+
+Registering the backing device makes the bcache device show up in /dev; you can
+now format it and use it as normal. But the first time using a new bcache
+device, it'll be running in passthrough mode until you attach it to a cache.
+If you are thinking about using bcache later, it is recommended to setup all your
+slow devices as bcache backing devices without a cache, and you can choose to add
+a caching device later.
+See 'ATTACHING' section below.
+
+The devices show up as::
+
+  /dev/bcache<N>
+
+As well as (with udev)::
+
+  /dev/bcache/by-uuid/<uuid>
+  /dev/bcache/by-label/<label>
+
+To get started::
+
+  mkfs.ext4 /dev/bcache0
+  mount /dev/bcache0 /mnt
+
+You can control bcache devices through sysfs at /sys/block/bcache<N>/bcache .
+You can also control them through /sys/fs//bcache/<cset-uuid>/ .
+
+Cache devices are managed as sets; multiple caches per set isn't supported yet
+but will allow for mirroring of metadata and dirty data in the future. Your new
+cache set shows up as /sys/fs/bcache/<UUID>
+
+Attaching
+---------
+
+After your cache device and backing device are registered, the backing device
+must be attached to your cache set to enable caching. Attaching a backing
+device to a cache set is done thusly, with the UUID of the cache set in
+/sys/fs/bcache::
+
+  echo <CSET-UUID> > /sys/block/bcache0/bcache/attach
+
+This only has to be done once. The next time you reboot, just reregister all
+your bcache devices. If a backing device has data in a cache somewhere, the
+/dev/bcache<N> device won't be created until the cache shows up - particularly
+important if you have writeback caching turned on.
+
+If you're booting up and your cache device is gone and never coming back, you
+can force run the backing device::
+
+  echo 1 > /sys/block/sdb/bcache/running
+
+(You need to use /sys/block/sdb (or whatever your backing device is called), not
+/sys/block/bcache0, because bcache0 doesn't exist yet. If you're using a
+partition, the bcache directory would be at /sys/block/sdb/sdb2/bcache)
+
+The backing device will still use that cache set if it shows up in the future,
+but all the cached data will be invalidated. If there was dirty data in the
+cache, don't expect the filesystem to be recoverable - you will have massive
+filesystem corruption, though ext4's fsck does work miracles.
+
+Error Handling
+--------------
+
+Bcache tries to transparently handle IO errors to/from the cache device without
+affecting normal operation; if it sees too many errors (the threshold is
+configurable, and defaults to 0) it shuts down the cache device and switches all
+the backing devices to passthrough mode.
+
+ - For reads from the cache, if they error we just retry the read from the
+   backing device.
+
+ - For writethrough writes, if the write to the cache errors we just switch to
+   invalidating the data at that lba in the cache (i.e. the same thing we do for
+   a write that bypasses the cache)
+
+ - For writeback writes, we currently pass that error back up to the
+   filesystem/userspace. This could be improved - we could retry it as a write
+   that skips the cache so we don't have to error the write.
+
+ - When we detach, we first try to flush any dirty data (if we were running in
+   writeback mode). It currently doesn't do anything intelligent if it fails to
+   read some of the dirty data, though.
+
+
+Howto/cookbook
+--------------
+
+A) Starting a bcache with a missing caching device
+
+If registering the backing device doesn't help, it's already there, you just need
+to force it to run without the cache::
+
+	host:~# echo /dev/sdb1 > /sys/fs/bcache/register
+	[  119.844831] bcache: register_bcache() error opening /dev/sdb1: device already registered
+
+Next, you try to register your caching device if it's present. However
+if it's absent, or registration fails for some reason, you can still
+start your bcache without its cache, like so::
+
+	host:/sys/block/sdb/sdb1/bcache# echo 1 > running
+
+Note that this may cause data loss if you were running in writeback mode.
+
+
+B) Bcache does not find its cache::
+
+	host:/sys/block/md5/bcache# echo 0226553a-37cf-41d5-b3ce-8b1e944543a8 > attach
+	[ 1933.455082] bcache: bch_cached_dev_attach() Couldn't find uuid for md5 in set
+	[ 1933.478179] bcache: __cached_dev_store() Can't attach 0226553a-37cf-41d5-b3ce-8b1e944543a8
+	[ 1933.478179] : cache set not found
+
+In this case, the caching device was simply not registered at boot
+or disappeared and came back, and needs to be (re-)registered::
+
+	host:/sys/block/md5/bcache# echo /dev/sdh2 > /sys/fs/bcache/register
+
+
+C) Corrupt bcache crashes the kernel at device registration time:
+
+This should never happen.  If it does happen, then you have found a bug!
+Please report it to the bcache development list: linux-bcache@vger.kernel.org
+
+Be sure to provide as much information that you can including kernel dmesg
+output if available so that we may assist.
+
+
+D) Recovering data without bcache:
+
+If bcache is not available in the kernel, a filesystem on the backing
+device is still available at an 8KiB offset. So either via a loopdev
+of the backing device created with --offset 8K, or any value defined by
+--data-offset when you originally formatted bcache with `bcache make`.
+
+For example::
+
+	losetup -o 8192 /dev/loop0 /dev/your_bcache_backing_dev
+
+This should present your unmodified backing device data in /dev/loop0
+
+If your cache is in writethrough mode, then you can safely discard the
+cache device without losing data.
+
+
+E) Wiping a cache device
+
+::
+
+	host:~# wipefs -a /dev/sdh2
+	16 bytes were erased at offset 0x1018 (bcache)
+	they were: c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
+
+After you boot back with bcache enabled, you recreate the cache and attach it::
+
+	host:~# bcache make -C /dev/sdh2
+	UUID:                   7be7e175-8f4c-4f99-94b2-9c904d227045
+	Set UUID:               5bc072a8-ab17-446d-9744-e247949913c1
+	version:                0
+	nbuckets:               106874
+	block_size:             1
+	bucket_size:            1024
+	nr_in_set:              1
+	nr_this_dev:            0
+	first_bucket:           1
+	[  650.511912] bcache: run_cache_set() invalidating existing data
+	[  650.549228] bcache: register_cache() registered cache device sdh2
+
+start backing device with missing cache::
+
+	host:/sys/block/md5/bcache# echo 1 > running
+
+attach new cache::
+
+	host:/sys/block/md5/bcache# echo 5bc072a8-ab17-446d-9744-e247949913c1 > attach
+	[  865.276616] bcache: bch_cached_dev_attach() Caching md5 as bcache0 on set 5bc072a8-ab17-446d-9744-e247949913c1
+
+
+F) Remove or replace a caching device::
+
+	host:/sys/block/sda/sda7/bcache# echo 1 > detach
+	[  695.872542] bcache: cached_dev_detach_finish() Caching disabled for sda7
+
+	host:~# wipefs -a /dev/nvme0n1p4
+	wipefs: error: /dev/nvme0n1p4: probing initialization failed: Device or resource busy
+	Ooops, it's disabled, but not unregistered, so it's still protected
+
+We need to go and unregister it::
+
+	host:/sys/fs/bcache/b7ba27a1-2398-4649-8ae3-0959f57ba128# ls -l cache0
+	lrwxrwxrwx 1 root root 0 Feb 25 18:33 cache0 -> ../../../devices/pci0000:00/0000:00:1d.0/0000:70:00.0/nvme/nvme0/nvme0n1/nvme0n1p4/bcache/
+	host:/sys/fs/bcache/b7ba27a1-2398-4649-8ae3-0959f57ba128# echo 1 > stop
+	kernel: [  917.041908] bcache: cache_set_free() Cache set b7ba27a1-2398-4649-8ae3-0959f57ba128 unregistered
+
+Now we can wipe it::
+
+	host:~# wipefs -a /dev/nvme0n1p4
+	/dev/nvme0n1p4: 16 bytes were erased at offset 0x00001018 (bcache): c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
+
+
+G) dm-crypt and bcache
+
+First setup bcache unencrypted and then install dmcrypt on top of
+/dev/bcache<N> This will work faster than if you dmcrypt both the backing
+and caching devices and then install bcache on top. [benchmarks?]
+
+
+H) Stop/free a registered bcache to wipe and/or recreate it
+
+Suppose that you need to free up all bcache references so that you can
+fdisk run and re-register a changed partition table, which won't work
+if there are any active backing or caching devices left on it:
+
+1) Is it present in /dev/bcache* ? (there are times where it won't be)
+
+   If so, it's easy::
+
+	host:/sys/block/bcache0/bcache# echo 1 > stop
+
+2) But if your backing device is gone, this won't work::
+
+	host:/sys/block/bcache0# cd bcache
+	bash: cd: bcache: No such file or directory
+
+   In this case, you may have to unregister the dmcrypt block device that
+   references this bcache to free it up::
+
+	host:~# dmsetup remove oldds1
+	bcache: bcache_device_free() bcache0 stopped
+	bcache: cache_set_free() Cache set 5bc072a8-ab17-446d-9744-e247949913c1 unregistered
+
+   This causes the backing bcache to be removed from /sys/fs/bcache and
+   then it can be reused.  This would be true of any block device stacking
+   where bcache is a lower device.
+
+3) In other cases, you can also look in /sys/fs/bcache/::
+
+	host:/sys/fs/bcache# ls -l */{cache?,bdev?}
+	lrwxrwxrwx 1 root root 0 Mar  5 09:39 0226553a-37cf-41d5-b3ce-8b1e944543a8/bdev1 -> ../../../devices/virtual/block/dm-1/bcache/
+	lrwxrwxrwx 1 root root 0 Mar  5 09:39 0226553a-37cf-41d5-b3ce-8b1e944543a8/cache0 -> ../../../devices/virtual/block/dm-4/bcache/
+	lrwxrwxrwx 1 root root 0 Mar  5 09:39 5bc072a8-ab17-446d-9744-e247949913c1/cache0 -> ../../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/ata10/host9/target9:0:0/9:0:0:0/block/sdl/sdl2/bcache/
+
+   The device names will show which UUID is relevant, cd in that directory
+   and stop the cache::
+
+	host:/sys/fs/bcache/5bc072a8-ab17-446d-9744-e247949913c1# echo 1 > stop
+
+   This will free up bcache references and let you reuse the partition for
+   other purposes.
+
+
+
+Troubleshooting performance
+---------------------------
+
+Bcache has a bunch of config options and tunables. The defaults are intended to
+be reasonable for typical desktop and server workloads, but they're not what you
+want for getting the best possible numbers when benchmarking.
+
+ - Backing device alignment
+
+   The default metadata size in bcache is 8k.  If your backing device is
+   RAID based, then be sure to align this by a multiple of your stride
+   width using `bcache make --data-offset`. If you intend to expand your
+   disk array in the future, then multiply a series of primes by your
+   raid stripe size to get the disk multiples that you would like.
+
+   For example:  If you have a 64k stripe size, then the following offset
+   would provide alignment for many common RAID5 data spindle counts::
+
+	64k * 2*2*2*3*3*5*7 bytes = 161280k
+
+   That space is wasted, but for only 157.5MB you can grow your RAID 5
+   volume to the following data-spindle counts without re-aligning::
+
+	3,4,5,6,7,8,9,10,12,14,15,18,20,21 ...
+
+ - Bad write performance
+
+   If write performance is not what you expected, you probably wanted to be
+   running in writeback mode, which isn't the default (not due to a lack of
+   maturity, but simply because in writeback mode you'll lose data if something
+   happens to your SSD)::
+
+	# echo writeback > /sys/block/bcache0/bcache/cache_mode
+
+ - Bad performance, or traffic not going to the SSD that you'd expect
+
+   By default, bcache doesn't cache everything. It tries to skip sequential IO -
+   because you really want to be caching the random IO, and if you copy a 10
+   gigabyte file you probably don't want that pushing 10 gigabytes of randomly
+   accessed data out of your cache.
+
+   But if you want to benchmark reads from cache, and you start out with fio
+   writing an 8 gigabyte test file - so you want to disable that::
+
+	# echo 0 > /sys/block/bcache0/bcache/sequential_cutoff
+
+   To set it back to the default (4 mb), do::
+
+	# echo 4M > /sys/block/bcache0/bcache/sequential_cutoff
+
+ - Traffic's still going to the spindle/still getting cache misses
+
+   In the real world, SSDs don't always keep up with disks - particularly with
+   slower SSDs, many disks being cached by one SSD, or mostly sequential IO. So
+   you want to avoid being bottlenecked by the SSD and having it slow everything
+   down.
+
+   To avoid that bcache tracks latency to the cache device, and gradually
+   throttles traffic if the latency exceeds a threshold (it does this by
+   cranking down the sequential bypass).
+
+   You can disable this if you need to by setting the thresholds to 0::
+
+	# echo 0 > /sys/fs/bcache/<cache set>/congested_read_threshold_us
+	# echo 0 > /sys/fs/bcache/<cache set>/congested_write_threshold_us
+
+   The default is 2000 us (2 milliseconds) for reads, and 20000 for writes.
+
+ - Still getting cache misses, of the same data
+
+   One last issue that sometimes trips people up is actually an old bug, due to
+   the way cache coherency is handled for cache misses. If a btree node is full,
+   a cache miss won't be able to insert a key for the new data and the data
+   won't be written to the cache.
+
+   In practice this isn't an issue because as soon as a write comes along it'll
+   cause the btree node to be split, and you need almost no write traffic for
+   this to not show up enough to be noticeable (especially since bcache's btree
+   nodes are huge and index large regions of the device). But when you're
+   benchmarking, if you're trying to warm the cache by reading a bunch of data
+   and there's no other traffic - that can be a problem.
+
+   Solution: warm the cache by doing writes, or use the testing branch (there's
+   a fix for the issue there).
+
+
+Sysfs - backing device
+----------------------
+
+Available at /sys/block/<bdev>/bcache, /sys/block/bcache*/bcache and
+(if attached) /sys/fs/bcache/<cset-uuid>/bdev*
+
+attach
+  Echo the UUID of a cache set to this file to enable caching.
+
+cache_mode
+  Can be one of either writethrough, writeback, writearound or none.
+
+clear_stats
+  Writing to this file resets the running total stats (not the day/hour/5 minute
+  decaying versions).
+
+detach
+  Write to this file to detach from a cache set. If there is dirty data in the
+  cache, it will be flushed first.
+
+dirty_data
+  Amount of dirty data for this backing device in the cache. Continuously
+  updated unlike the cache set's version, but may be slightly off.
+
+label
+  Name of underlying device.
+
+readahead
+  Size of readahead that should be performed.  Defaults to 0.  If set to e.g.
+  1M, it will round cache miss reads up to that size, but without overlapping
+  existing cache entries.
+
+running
+  1 if bcache is running (i.e. whether the /dev/bcache device exists, whether
+  it's in passthrough mode or caching).
+
+sequential_cutoff
+  A sequential IO will bypass the cache once it passes this threshold; the
+  most recent 128 IOs are tracked so sequential IO can be detected even when
+  it isn't all done at once.
+
+sequential_merge
+  If non zero, bcache keeps a list of the last 128 requests submitted to compare
+  against all new requests to determine which new requests are sequential
+  continuations of previous requests for the purpose of determining sequential
+  cutoff. This is necessary if the sequential cutoff value is greater than the
+  maximum acceptable sequential size for any single request.
+
+state
+  The backing device can be in one of four different states:
+
+  no cache: Has never been attached to a cache set.
+
+  clean: Part of a cache set, and there is no cached dirty data.
+
+  dirty: Part of a cache set, and there is cached dirty data.
+
+  inconsistent: The backing device was forcibly run by the user when there was
+  dirty data cached but the cache set was unavailable; whatever data was on the
+  backing device has likely been corrupted.
+
+stop
+  Write to this file to shut down the bcache device and close the backing
+  device.
+
+writeback_delay
+  When dirty data is written to the cache and it previously did not contain
+  any, waits some number of seconds before initiating writeback. Defaults to
+  30.
+
+writeback_percent
+  If nonzero, bcache tries to keep around this percentage of the cache dirty by
+  throttling background writeback and using a PD controller to smoothly adjust
+  the rate.
+
+writeback_rate
+  Rate in sectors per second - if writeback_percent is nonzero, background
+  writeback is throttled to this rate. Continuously adjusted by bcache but may
+  also be set by the user.
+
+writeback_running
+  If off, writeback of dirty data will not take place at all. Dirty data will
+  still be added to the cache until it is mostly full; only meant for
+  benchmarking. Defaults to on.
+
+Sysfs - backing device stats
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are directories with these numbers for a running total, as well as
+versions that decay over the past day, hour and 5 minutes; they're also
+aggregated in the cache set directory as well.
+
+bypassed
+  Amount of IO (both reads and writes) that has bypassed the cache
+
+cache_hits, cache_misses, cache_hit_ratio
+  Hits and misses are counted per individual IO as bcache sees them; a
+  partial hit is counted as a miss.
+
+cache_bypass_hits, cache_bypass_misses
+  Hits and misses for IO that is intended to skip the cache are still counted,
+  but broken out here.
+
+cache_miss_collisions
+  Counts instances where data was going to be inserted into the cache from a
+  cache miss, but raced with a write and data was already present (usually 0
+  since the synchronization for cache misses was rewritten)
+
+Sysfs - cache set
+~~~~~~~~~~~~~~~~~
+
+Available at /sys/fs/bcache/<cset-uuid>
+
+average_key_size
+  Average data per key in the btree.
+
+bdev<0..n>
+  Symlink to each of the attached backing devices.
+
+block_size
+  Block size of the cache devices.
+
+btree_cache_size
+  Amount of memory currently used by the btree cache
+
+bucket_size
+  Size of buckets
+
+cache<0..n>
+  Symlink to each of the cache devices comprising this cache set.
+
+cache_available_percent
+  Percentage of cache device which doesn't contain dirty data, and could
+  potentially be used for writeback.  This doesn't mean this space isn't used
+  for clean cached data; the unused statistic (in priority_stats) is typically
+  much lower.
+
+clear_stats
+  Clears the statistics associated with this cache
+
+dirty_data
+  Amount of dirty data is in the cache (updated when garbage collection runs).
+
+flash_vol_create
+  Echoing a size to this file (in human readable units, k/M/G) creates a thinly
+  provisioned volume backed by the cache set.
+
+io_error_halflife, io_error_limit
+  These determines how many errors we accept before disabling the cache.
+  Each error is decayed by the half life (in # ios).  If the decaying count
+  reaches io_error_limit dirty data is written out and the cache is disabled.
+
+journal_delay_ms
+  Journal writes will delay for up to this many milliseconds, unless a cache
+  flush happens sooner. Defaults to 100.
+
+root_usage_percent
+  Percentage of the root btree node in use.  If this gets too high the node
+  will split, increasing the tree depth.
+
+stop
+  Write to this file to shut down the cache set - waits until all attached
+  backing devices have been shut down.
+
+tree_depth
+  Depth of the btree (A single node btree has depth 0).
+
+unregister
+  Detaches all backing devices and closes the cache devices; if dirty data is
+  present it will disable writeback caching and wait for it to be flushed.
+
+Sysfs - cache set internal
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This directory also exposes timings for a number of internal operations, with
+separate files for average duration, average frequency, last occurrence and max
+duration: garbage collection, btree read, btree node sorts and btree splits.
+
+active_journal_entries
+  Number of journal entries that are newer than the index.
+
+btree_nodes
+  Total nodes in the btree.
+
+btree_used_percent
+  Average fraction of btree in use.
+
+bset_tree_stats
+  Statistics about the auxiliary search trees
+
+btree_cache_max_chain
+  Longest chain in the btree node cache's hash table
+
+cache_read_races
+  Counts instances where while data was being read from the cache, the bucket
+  was reused and invalidated - i.e. where the pointer was stale after the read
+  completed. When this occurs the data is reread from the backing device.
+
+trigger_gc
+  Writing to this file forces garbage collection to run.
+
+Sysfs - Cache device
+~~~~~~~~~~~~~~~~~~~~
+
+Available at /sys/block/<cdev>/bcache
+
+block_size
+  Minimum granularity of writes - should match hardware sector size.
+
+btree_written
+  Sum of all btree writes, in (kilo/mega/giga) bytes
+
+bucket_size
+  Size of buckets
+
+cache_replacement_policy
+  One of either lru, fifo or random.
+
+freelist_percent
+  Size of the freelist as a percentage of nbuckets. Can be written to
+  increase the number of buckets kept on the freelist, which lets you
+  artificially reduce the size of the cache at runtime. Mostly for testing
+  purposes (i.e. testing how different size caches affect your hit rate).
+
+io_errors
+  Number of errors that have occurred, decayed by io_error_halflife.
+
+metadata_written
+  Sum of all non data writes (btree writes and all other metadata).
+
+nbuckets
+  Total buckets in this cache
+
+priority_stats
+  Statistics about how recently data in the cache has been accessed.
+  This can reveal your working set size.  Unused is the percentage of
+  the cache that doesn't contain any data.  Metadata is bcache's
+  metadata overhead.  Average is the average priority of cache buckets.
+  Next is a list of quantiles with the priority threshold of each.
+
+written
+  Sum of all data that has been written to the cache; comparison with
+  btree_written gives the amount of write inflation in bcache.
diff --git a/Documentation/admin-guide/binderfs.rst b/Documentation/admin-guide/binderfs.rst
new file mode 100644
index 000000000..41a4db00d
--- /dev/null
+++ b/Documentation/admin-guide/binderfs.rst
@@ -0,0 +1,87 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The Android binderfs Filesystem
+===============================
+
+Android binderfs is a filesystem for the Android binder IPC mechanism.  It
+allows to dynamically add and remove binder devices at runtime.  Binder devices
+located in a new binderfs instance are independent of binder devices located in
+other binderfs instances.  Mounting a new binderfs instance makes it possible
+to get a set of private binder devices.
+
+Mounting binderfs
+-----------------
+
+Android binderfs can be mounted with::
+
+  mkdir /dev/binderfs
+  mount -t binder binder /dev/binderfs
+
+at which point a new instance of binderfs will show up at ``/dev/binderfs``.
+In a fresh instance of binderfs no binder devices will be present.  There will
+only be a ``binder-control`` device which serves as the request handler for
+binderfs. Mounting another binderfs instance at a different location will
+create a new and separate instance from all other binderfs mounts.  This is
+identical to the behavior of e.g. ``devpts`` and ``tmpfs``. The Android
+binderfs filesystem can be mounted in user namespaces.
+
+Options
+-------
+max
+  binderfs instances can be mounted with a limit on the number of binder
+  devices that can be allocated. The ``max=<count>`` mount option serves as
+  a per-instance limit. If ``max=<count>`` is set then only ``<count>`` number
+  of binder devices can be allocated in this binderfs instance.
+
+stats
+  Using ``stats=global`` enables global binder statistics.
+  ``stats=global`` is only available for a binderfs instance mounted in the
+  initial user namespace. An attempt to use the option to mount a binderfs
+  instance in another user namespace will return a permission error.
+
+Allocating binder Devices
+-------------------------
+
+.. _ioctl: http://man7.org/linux/man-pages/man2/ioctl.2.html
+
+To allocate a new binder device in a binderfs instance a request needs to be
+sent through the ``binder-control`` device node.  A request is sent in the form
+of an `ioctl() <ioctl_>`_.
+
+What a program needs to do is to open the ``binder-control`` device node and
+send a ``BINDER_CTL_ADD`` request to the kernel.  Users of binderfs need to
+tell the kernel which name the new binder device should get.  By default a name
+can only contain up to ``BINDERFS_MAX_NAME`` chars including the terminating
+zero byte.
+
+Once the request is made via an `ioctl() <ioctl_>`_ passing a ``struct
+binder_device`` with the name to the kernel it will allocate a new binder
+device and return the major and minor number of the new device in the struct
+(This is necessary because binderfs allocates a major device number
+dynamically.).  After the `ioctl() <ioctl_>`_ returns there will be a new
+binder device located under /dev/binderfs with the chosen name.
+
+Deleting binder Devices
+-----------------------
+
+.. _unlink: http://man7.org/linux/man-pages/man2/unlink.2.html
+.. _rm: http://man7.org/linux/man-pages/man1/rm.1.html
+
+Binderfs binder devices can be deleted via `unlink() <unlink_>`_.  This means
+that the `rm() <rm_>`_ tool can be used to delete them. Note that the
+``binder-control`` device cannot be deleted since this would make the binderfs
+instance unusable.  The ``binder-control`` device will be deleted when the
+binderfs instance is unmounted and all references to it have been dropped.
+
+Binder features
+---------------
+
+Assuming an instance of binderfs has been mounted at ``/dev/binderfs``, the
+features supported by the binder driver can be located under
+``/dev/binderfs/features/``. The presence of individual files can be tested
+to determine whether a particular feature is supported by the driver.
+
+Example::
+
+        cat /dev/binderfs/features/oneway_spam_detection
+        1
diff --git a/Documentation/admin-guide/binfmt-misc.rst b/Documentation/admin-guide/binfmt-misc.rst
new file mode 100644
index 000000000..d26b63a27
--- /dev/null
+++ b/Documentation/admin-guide/binfmt-misc.rst
@@ -0,0 +1,391 @@
+Kernel Support for miscellaneous Binary Formats (binfmt_misc)
+=============================================================
+
+This Kernel feature allows you to invoke almost (for restrictions see below)
+every program by simply typing its name in the shell.
+This includes for example compiled Java(TM), Python or Emacs programs.
+
+To achieve this you must tell binfmt_misc which interpreter has to be invoked
+with which binary. Binfmt_misc recognises the binary-type by matching some bytes
+at the beginning of the file with a magic byte sequence (masking out specified
+bits) you have supplied. Binfmt_misc can also recognise a filename extension
+aka ``.com`` or ``.exe``.
+
+First you must mount binfmt_misc::
+
+	mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc
+
+To actually register a new binary type, you have to set up a string looking like
+``:name:type:offset:magic:mask:interpreter:flags`` (where you can choose the
+``:`` upon your needs) and echo it to ``/proc/sys/fs/binfmt_misc/register``.
+
+Here is what the fields mean:
+
+- ``name``
+   is an identifier string. A new /proc file will be created with this
+   name below ``/proc/sys/fs/binfmt_misc``; cannot contain slashes ``/`` for
+   obvious reasons.
+- ``type``
+   is the type of recognition. Give ``M`` for magic, ``E`` for extension and
+   ``B`` for a bpf-backed handler (see below).
+- ``offset``
+   is the offset of the magic/mask in the file, counted in bytes. This
+   defaults to 0 if you omit it (i.e. you write ``:name:type::magic...``).
+   Ignored when using filename extension matching.
+- ``magic``
+   is the byte sequence binfmt_misc is matching for. The magic string
+   may contain hex-encoded characters like ``\x0a`` or ``\xA4``. Note that you
+   must escape any NUL bytes; parsing halts at the first one. In a shell
+   environment you might have to write ``\\x0a`` to prevent the shell from
+   eating your ``\``.
+   If you chose filename extension matching, this is the extension to be
+   recognised (without the ``.``, the ``\x0a`` specials are not allowed).
+   Extension    matching is case sensitive, and slashes ``/`` are not allowed!
+- ``mask``
+   is an (optional, defaults to all 0xff) mask. You can mask out some
+   bits from matching by supplying a string like magic and as long as magic.
+   The mask is anded with the byte sequence of the file. Note that you must
+   escape any NUL bytes; parsing halts at the first one. Ignored when using
+   filename extension matching.
+- ``interpreter``
+   is the program that should be invoked with the binary as first
+   argument (specify the full path). For ``B`` entries this field
+   carries the name of the bpf handler instead (see below).
+- ``flags``
+   is an optional field that controls several aspects of the invocation
+   of the interpreter. It is a string of capital letters, each controls a
+   certain aspect. The following flags are supported:
+
+      ``P`` - preserve-argv[0]
+            Legacy behavior of binfmt_misc is to overwrite
+            the original argv[0] with the full path to the binary. When this
+            flag is included, binfmt_misc will add an argument to the argument
+            vector for this purpose, thus preserving the original ``argv[0]``.
+            e.g. If your interp is set to ``/bin/foo`` and you run ``blah``
+            (which is in ``/usr/local/bin``), then the kernel will execute
+            ``/bin/foo`` with ``argv[]`` set to ``["/bin/foo", "/usr/local/bin/blah", "blah"]``.  The interp has to be aware of this so it can
+            execute ``/usr/local/bin/blah``
+            with ``argv[]`` set to ``["blah"]``.
+      ``O`` - open-binary
+	    Legacy behavior of binfmt_misc is to pass the full path
+            of the binary to the interpreter as an argument. When this flag is
+            included, binfmt_misc will open the file for reading and pass its
+            descriptor into the auxilary vector with the key "AT_EXECFD", thus
+            allowing the interpreter to execute non-readable binaries. This
+            feature should be used with care - the interpreter has to be trusted
+            not to emit the contents of the non-readable binary.
+      ``C`` - credentials
+            Currently, the behavior of binfmt_misc is to calculate
+            the credentials and security token of the new process according to
+            the interpreter. When this flag is included, these attributes are
+            calculated according to the binary. It also implies the ``O`` flag.
+            This feature should be used with care as the interpreter
+            will run with root permissions when a setuid binary owned by root
+            is run with binfmt_misc.
+      ``F`` - fix binary
+            The usual behaviour of binfmt_misc is to spawn the
+	    binary lazily when the misc format file is invoked.  However,
+	    this doesn't work very well in the face of mount namespaces and
+	    changeroots, so the ``F`` mode opens the binary as soon as the
+	    emulation is installed and uses the opened image to spawn the
+	    emulator, meaning it is always available once installed,
+	    regardless of how the environment changes.
+      ``T`` - transparent
+            Run the interpreter transparently. The binary is handed to
+            the interpreter through ``AT_EXECFD`` (``T`` implies ``O``),
+            the argument vector is left exactly as the caller built it
+            and the kernel labels ``/proc/pid/exe`` with the binary
+            instead of the interpreter. The interpreter has to load the
+            binary from ``AT_EXECFD`` and follow the
+            ``AT_FLAGS_TRANSPARENT_INTERP`` contract. Combining ``T``
+            with ``P`` is rejected: transparency preserves the whole
+            argument vector, argv[0] included.
+      ``L`` - loader substitution
+            Do not run the interpreter on the binary at all: load the
+            binary itself as a fully native exec and substitute the
+            interpreter for the loader named in the binary's
+            ``PT_INTERP``. See the "Loader substitution" section
+            below. ``L`` rejects ``T``, ``P``, ``O`` and ``C``;
+            ``F`` composes.
+      ``D`` - registered disabled
+            The entry is created disabled instead of being matchable at
+            once, and has to be enabled by writing ``1`` to its file
+            before it dispatches anything. This splits a registration
+            into creating the entry and activating it, leaving room to
+            configure it in between - which is what a ``B`` entry that
+            binds interpreters needs; see the bpf section below. The flag
+            is spent on the registration and is not read back: what an
+            entry file reports afterwards is whether it is enabled.
+
+
+There are some restrictions:
+
+ - the whole register string may not exceed 1920 characters
+ - the magic must reside in the first 128 bytes of the file, i.e.
+   offset+size(magic) has to be less than 128
+ - the interpreter string may not exceed 127 characters
+ - an interpreter used with ``C`` or ``L`` but without ``F`` has to be
+   named by an absolute path. It is opened when the binary is executed, so
+   a relative one would be resolved against the working directory of
+   whoever runs the binary
+ - the amount of pre-opened interpreters by ``F``, or bound to a ``B`` entry
+   is limited by the ``/proc/sys/user/max_binfmt_misc_interpreters`` sysctl. A
+   registration past the limit is refused with ``-ENOSPC``. This limits an
+   unprivileged namespace pinning files. A nested namespace can raise only its
+   own limit and every ancestor is charged too
+
+
+To use binfmt_misc you have to mount it first. You can mount it with
+``mount -t binfmt_misc none /proc/sys/fs/binfmt_misc`` command, or you can add
+a line ``none  /proc/sys/fs/binfmt_misc binfmt_misc defaults 0 0`` to your
+``/etc/fstab`` so it auto mounts on boot.
+
+You may want to add the binary formats in one of your ``/etc/rc`` scripts during
+boot-up. Read the manual of your init program to figure out how to do this
+right.
+
+Think about the order of adding entries! Later added entries are matched first!
+
+
+A few examples (assumed you are in ``/proc/sys/fs/binfmt_misc``):
+
+- enable support for em86 (like binfmt_em86, for Alpha AXP only)::
+
+    echo ':i386:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
+    echo ':i486:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:' > register
+
+- enable support for packed DOS applications (pre-configured dosemu hdimages)::
+
+    echo ':DEXE:M::\x0eDEX::/usr/bin/dosexec:' > register
+
+- enable support for Windows executables using wine::
+
+    echo ':DOSWin:M::MZ::/usr/local/bin/wine:' > register
+
+For java support see Documentation/admin-guide/java.rst
+
+
+You can enable/disable binfmt_misc or one binary type by echoing 0 (to disable)
+or 1 (to enable) to ``/proc/sys/fs/binfmt_misc/status`` or
+``/proc/.../the_name``.
+Catting the file tells you the current status of ``binfmt_misc/the_entry``.
+
+You can remove one entry or all entries by echoing -1 to ``/proc/.../the_name``
+or ``/proc/sys/fs/binfmt_misc/status``. A single entry can also be removed
+by simply unlinking (``rm``) ``/proc/.../the_name``.
+
+
+bpf-backed handlers
+-------------------
+
+With ``CONFIG_BINFMT_MISC_BPF`` both the matching and the interpreter
+selection can be delegated to bpf programs. A handler is an instance of the
+``binfmt_misc_ops`` struct_ops with a ``match`` and a ``load`` program and a
+``name``. Once the struct_ops map is registered the handler can be activated
+with a ``B`` entry that references it by name in the ``interpreter`` field
+and carries neither offset, magic, nor mask::
+
+    echo ':qemu:B::::my_handler:' > register
+
+Both programs receive the ``linux_binprm`` of the binary and both can
+sleep. The ``match`` program decides whether the handler applies: it is
+consulted during the entry walk exactly like magic and extension matching,
+in the same registration order with the same first-match-wins semantics.
+Unlike static matching it is not limited to the prefetched first bytes of
+the file in ``bprm->buf``: it can read the file, e.g. to parse ELF program
+headers whose data sits at arbitrary offsets. It only decides, though: the
+selection kfuncs below are rejected in it. The ``load`` program of the
+matched handler then selects the interpreter: it can equally read the file
+and derive the interpreter from the binary's location. It selects the
+interpreter by calling the ``bpf_binprm_set_interp()`` kfunc with an
+absolute path and returning ``0``. A match is committed: a failing
+``load`` fails the exec with its error instead of falling through to later
+entries; ``-ENOEXEC`` lets the remaining binary formats have a go. A path
+selected this way is opened with the credentials of the task doing the
+exec, exactly as a statically registered interpreter without ``F`` would
+be.
+
+An entry can instead bind the interpreters its handler may use, so that no
+path is resolved at exec time at all. An entry registered with ``D`` is not
+matchable yet, which is what leaves it open to being given them, one
+``+name path`` write at a time::
+
+    echo ':qemu:B::::my_handler:D' > register
+    echo '+aarch64 /usr/bin/qemu-aarch64' > qemu
+    echo '+arm /usr/bin/qemu-arm' > qemu
+    echo 1 > qemu
+
+Each path is opened during its write, in the writing process's context and
+with the credentials the entry file was opened with, exactly the way ``F``
+pre-opens a static entry's interpreter; the paths must be absolute. The
+path is everything past the first space, so there is nothing it cannot
+express, and no interpreter has to fit in a register string. An entry
+binds at most 100 interpreters, and each one is charged against
+``max_binfmt_misc_interpreters`` like any other binding. A write past either
+limit is refused with ``-ENOSPC``.
+
+The ``load`` program then selects one per exec by name with the
+``bpf_binprm_select_interp()`` kfunc, and every exec runs a clone of the
+file that was opened. The path decides which file is bound and nothing
+else: it is not resolved again, in any namespace, so what it holds later -
+or what it holds in the namespace of whoever runs the binary - no longer
+decides anything.
+
+Enabling the entry ends this. Its interpreters are read at exec time with
+nothing but a reference held on the entry, so an entry that has ever been
+matchable can never have its set changed again: the first ``1`` seals it,
+from then on ``+`` is refused with ``-EBUSY``, and an entry registered
+without ``D`` is sealed from the start. Binding a name twice is refused
+with ``-EEXIST``.
+
+Selection is by name so that the configuration and the program need not
+agree on an order, and so that a handler is not tied to where a distribution
+puts its interpreters. A name is a single word of printable ASCII, at most
+32 characters; a name the entry did not bind gives the program ``-ENOENT``,
+which it can act on or return. The interpreter runs under the path it was
+registered under, and the entry reports what it bound::
+
+    $ cat /proc/sys/fs/binfmt_misc/qemu
+    enabled
+    bpf my_handler
+    bpf-interpreter aarch64 /usr/bin/qemu-aarch64
+    bpf-interpreter arm /usr/bin/qemu-arm
+    flags:
+
+The path reported is the one the interpreter was bound under, which named
+the file at that moment; it is not re-resolved, so it is a record of what
+was bound rather than a promise about what that path holds now.
+
+The ``load`` program can also pass a single argument to the interpreter with
+the ``bpf_binprm_set_interp_arg()`` kfunc. It is inserted between the
+interpreter and the binary, exactly like the optional argument of a ``#!``
+interpreter line, e.g. for a handler that resolves ``$ORIGIN`` in a script's
+``#!`` path and needs to preserve the argument that followed it.
+
+The invocation flags a static entry fixes at registration - ``P``, ``C``,
+``O``, ``T`` and ``L`` - are per-exec choices for a bpf handler, made by the
+``load`` program with the ``bpf_binprm_set_flags()`` kfunc, so a single
+handler can decide them differently for each binary it handles:
+
+- ``BPF_BINPRM_PRESERVE_ARGV0`` keeps the caller's ``argv[0]`` (the ``P``
+  flag).
+- ``BPF_BINPRM_CREDENTIALS`` computes credentials from the binary (the ``C``
+  flag), bounded to user namespaces that map the binary's owner just like
+  any other setuid exec.
+- ``BPF_BINPRM_EXECFD`` opens the binary on the interpreter's behalf and
+  passes it through the ``AT_EXECFD`` aux vector entry (the ``O`` flag), so
+  the interpreter can run binaries it could not open by path.
+- ``BPF_BINPRM_TRANSPARENT`` runs the interpreter transparently (the ``T``
+  flag): the binary is handed over through ``AT_EXECFD`` as
+  with ``BPF_BINPRM_EXECFD``, but the argument vector is also left as the
+  caller passed it. An interpreter that loads the binary from ``AT_EXECFD``
+  then appears in ``argv[0]`` and ``/proc/pid/cmdline`` as a direct
+  execution of the binary. ``BPF_BINPRM_PRESERVE_ARGV0`` and a staged
+  interpreter argument are rejected in combination with it, just as ``P``
+  is with ``T``. It also lets a handler
+  run a binary passed as an inaccessible ``O_CLOEXEC`` file descriptor to
+  ``execveat()``, which a path-splicing dispatch cannot: the interpreter
+  has no path by which to open it.
+- ``BPF_BINPRM_LOADER`` substitutes the interpreter for the binary's
+  ``PT_INTERP`` and runs the binary as a fully native exec (the ``L``
+  flag). It excludes the other flags and a staged interpreter argument.
+
+Because these are program choices, a ``B`` entry carries no invocation
+flags in the register string; ``F`` has none to spell for it either, since
+the interpreters it binds already pre-open what ``F`` would. The
+registration directive ``D`` is the exception: it decides how the entry
+starts out, not how the interpreter is invoked.
+
+A handler is looked up only in the user namespace the struct_ops map was
+registered in. Handlers are not inherited, so an entry can only reference a
+handler registered in the same user namespace as its binfmt_misc instance.
+The entry keeps the handler alive; deleting the struct_ops map only prevents
+new activations.
+
+
+Transparent interpreters
+------------------------
+
+With the ``T`` flag or ``BPF_BINPRM_TRANSPARENT`` the dispatch is invisible
+to the resulting process. The argument vector is left exactly as the caller
+built it. The binary is passed through ``AT_EXECFD``. The kernel also labels
+``/proc/pid/exe`` correctly. The binary's file is write-denied while the
+process runs and the interpreter's is not, exactly as if the binary had been
+executed directly. A transparent entry does not change how credentials are
+derived. As
+with any other entry, set*id bits of the binary are only honored with ``C`` (or
+``BPF_BINPRM_CREDENTIALS``).
+
+The interpreter has to be built for this contract. The kernel announces it
+with ``AT_FLAGS_TRANSPARENT_INTERP`` in the ``AT_FLAGS`` aux vector entry
+next to ``AT_EXECFD``. The argument vector belongs entirely to the program,
+nothing was spliced in, so the interpreter doesn't consume arguments and
+simply loads the program from the descriptor. The bit is also the loader's
+license to finish the identity. After mapping the program it may retarget the
+``AT_PHDR``/``AT_ENTRY``/``AT_BASE`` entries of ``/proc/pid/auxv`` and the
+code/data statistics markers via one ``PR_SET_MM_MAP`` which completes
+what attaching debuggers observe.  What remains visibly different from a
+direct execution is the address space layout. The interpreter occupies
+the main-image position and the program lives in the mmap region.
+
+
+Loader substitution
+-------------------
+
+The ``L`` flag turns the execution model around. Instead of running the
+registered interpreter with the binary as its payload the kernel loads
+the matched binary itself as the main image and substitutes the registered
+interpreter for the loader named in the binary's ``PT_INTERP``.
+
+Because the exec is native, there is no dispatch identity to
+reconstruct and no contract the substitute has to implement. A stock
+dynamic loader works unchanged. The argument vector is untouched,
+credentials and ``AT_SECURE`` derive from the binary, there is no
+``AT_EXECFD`` and no marker in the aux vector, the binary sits in the
+main-image slot with the native brk placement so ``/proc/pid/maps``,
+core dumps and perf mmap records have the native shape, and the
+identity is already complete when ``PTRACE_EVENT_EXEC`` stops the
+tracee. So launching under a debugger works, not just attaching. ``L``
+entries are for ELF binaries of a native architecture. Foreign-arch
+emulation and non-ELF payloads remain the domain of the classic and
+transparent modes.
+
+The override applies when the format that finally claims the file is
+ELF with a ``PT_INTERP``. A matched binary without one or an
+interpreter-less ``ET_DYN`` drops the override and runs natively. A file
+claimed by another format - a ``#!`` script, say - is handled by that
+format as if the entry had not matched. ``L`` is therefore not an
+enforcement mechanism: it decides how a binary that asks for a loader is
+run, it does not guarantee that everything matching the entry runs under
+the substitute. A format that cannot consume the override at all instead
+refuses the exec with ``ENOEXEC`` before the point of no return.
+
+A wrong-architecture ELF fails the whole exec with ``ENOEXEC`` exactly
+as if no entry had matched. A substitute that is not ELF of the right
+architecture fails with ``ELIBBAD``. The usual ``PT_INTERP`` sanity
+checks on the binary still apply. But the segment's content is otherwise
+irrelevant.
+
+``L`` rejects the classic-dispatch flags ``T``, ``P``, ``O`` and ``C``
+at registration. ``F`` composes and is valuable: with it the substitute
+is opened at registration time, so later mount namespace or path changes
+cannot redirect it. Without it the substitute is opened when the binary
+is executed, and the path is resolved in the mount namespace and root of
+whoever runs the binary, which is why it has to be absolute. As with
+``C``, register only trusted interpreters. The substituted loader runs
+with credentials derived from the binary.
+
+
+Hints
+-----
+
+If you want to pass special arguments to your interpreter, you can
+write a wrapper script for it.
+See :doc:`Documentation/admin-guide/java.rst <./java>` for an example.
+
+Your interpreter should NOT look in the PATH for the filename; the kernel
+passes it the full filename (or the file descriptor) to use.  Using ``$PATH`` can
+cause unexpected behaviour and can be a security hazard.
+
+
+Richard Günther <rguenth@tat.physik.uni-tuebingen.de>
diff --git a/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg b/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg
new file mode 100644
index 000000000..f87cfa0dc
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/DRBD-8.3-data-packets.svg
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+       y="13877"
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+    <tspan
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+    <tspan
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+    <tspan
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new file mode 100644
index 000000000..48a1e2165
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+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12191 12420 12597 12775 12953 13131 13309 13486 13664 13770 13931 14109 14287 14375 14553 14731 14837 15015 15192 15298"
+       y="20007"
+       id="tspan343">w_e_end_rsdata_req()</tspan>
+  </text>
+  <text
+     id="text357"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4444 4550 4728 4889 5066 5138 5299 5477 5655 5883 6095 6324 6501 6590 6768 6997 7175 7352 7424 7585 7691"
+       y="20507"
+       id="tspan359">receive_RSDataReply()</tspan>
+  </text>
+  <text
+     id="text373"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4457 4635 4741 4918 5096 5274 5452 5630 5807 5879 6057 6235 6464 6569 6641 6730 6908 7086 7247 7425 7585 7691"
+       y="21407"
+       id="tspan375">drbd_endio_write_sec()</tspan>
+  </text>
+  <text
+     id="text389"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4647 4825 5003 5180 5358 5536 5714 5820 5997 6158 6319 6497 6658 6836 7013 7085 7263 7424 7585 7691"
+       y="21907"
+       id="tspan391">e_end_resync_block()</tspan>
+  </text>
+  <path
+     d="M 11999,22601 L 11685,22640 L 11724,22444 L 11999,22601 z"
+     id="path401"
+     style="fill:#000080;visibility:visible" />
+  <path
+     d="M 7999,21801 L 11764,22554"
+     id="path405"
+     style="fill:none;stroke:#000080;visibility:visible" />
+  <text
+     x="4290.3008"
+     y="-2369.6162"
+     transform="matrix(0.9788674,0.2044961,-0.2044961,0.9788674,0,0)"
+     id="text423"
+     style="font-size:318px;font-weight:400;fill:#000080;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="13610.301 13911.301 14016.301 14088.301 14177.301 14355.301 14567.301 14728.301"
+       y="19573.385"
+       id="tspan425">WriteAck</tspan>
+  </text>
+  <text
+     id="text439"
+     style="font-size:318px;font-weight:400;fill:#000080;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12199 12377 12555 12644 12821 13033 13105 13283 13444 13604 13816 13977 14138 14244"
+       y="22559"
+       id="tspan441">got_BlockAck()</tspan>
+  </text>
+  <text
+     id="text455"
+     style="font-size:423px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="7999 8304 8541 8753 8964 9201 9413 9531 9769 9862 10099 10310 10522 10734 10852 10971 11208 11348 11585 11822"
+       y="16877"
+       id="tspan457">Resync blocks, 4-32K</tspan>
+  </text>
+  <path
+     d="M 12000,7601 L 11900,7301 L 12100,7301 L 12000,7601 z"
+     id="path467"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 12000,6801 L 12000,7361"
+     id="path471"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <path
+     d="M 12000,6801 L 11686,6840 L 11725,6644 L 12000,6801 z"
+     id="path483"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 8000,6001 L 11765,6754"
+     id="path487"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <text
+     x="-1288.1796"
+     y="1279.7666"
+     transform="matrix(0.9895258,-0.1443562,0.1443562,0.9895258,0,0)"
+     id="text505"
+     style="font-size:318px;font-weight:400;fill:#000080;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="8174.8208 8475.8203 8580.8203 8652.8203 8741.8203 8919.8203 9131.8203 9292.8203"
+       y="9516.7666"
+       id="tspan507">WriteAck</tspan>
+  </text>
+  <path
+     d="M 8000,8601 L 8282,8458 L 8312,8655 L 8000,8601 z"
+     id="path517"
+     style="fill:#000080;visibility:visible" />
+  <path
+     d="M 12000,8001 L 8237,8565"
+     id="path521"
+     style="fill:none;stroke:#000080;visibility:visible" />
+  <text
+     x="1065.6655"
+     y="-2097.7664"
+     transform="matrix(0.9788674,0.2044961,-0.2044961,0.9788674,0,0)"
+     id="text539"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="10682.666 10911.666 11088.666 11177.666"
+       y="4107.2339"
+       id="tspan541">Data</tspan>
+  </text>
+  <text
+     id="text555"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4746 4924 5030 5207 5385 5563 5826 6003 6164 6342 6520 6626 6803 6981 7159 7337 7498 7587 7692"
+       y="5505"
+       id="tspan557">drbd_make_request()</tspan>
+  </text>
+  <text
+     id="text571"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12200 12306 12484 12645 12822 12894 13055 13233 13411 13639 13817 13906 14084 14190"
+       y="6806"
+       id="tspan573">receive_Data()</tspan>
+  </text>
+  <text
+     id="text587"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12200 12378 12484 12661 12839 13017 13195 13373 13550 13622 13800 13978 14207 14312 14384 14473 14651 14829 14990 15168 15328 15434"
+       y="7606"
+       id="tspan589">drbd_endio_write_sec()</tspan>
+  </text>
+  <text
+     id="text603"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12192 12370 12548 12725 12903 13081 13259 13437 13509 13686 13847 14008 14114"
+       y="8007"
+       id="tspan605">e_end_block()</tspan>
+  </text>
+  <text
+     id="text619"
+     style="font-size:318px;font-weight:400;fill:#000080;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="5647 5825 6003 6092 6269 6481 6553 6731 6892 7052 7264 7425 7586 7692"
+       y="8606"
+       id="tspan621">got_BlockAck()</tspan>
+  </text>
+  <text
+     id="text635"
+     style="font-size:423px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="8000 8305 8542 8779 9016 9109 9346 9486 9604 9956 10049 10189 10328 10565 10705 10942 11179 11298 11603 11742 11835 11954 12191 12310 12428 12665 12902 13139 13279 13516 13753"
+       y="4877"
+       id="tspan637">Regular mirrored write, 512-32K</tspan>
+  </text>
+  <text
+     id="text651"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="5381 5610 5787 5948 6126 6304 6482 6659 6837 7015 7087 7265 7426 7587 7692"
+       y="6003"
+       id="tspan653">w_send_dblock()</tspan>
+  </text>
+  <path
+     d="M 8000,6800 L 7900,6500 L 8100,6500 L 8000,6800 z"
+     id="path663"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 8000,6000 L 8000,6560"
+     id="path667"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <text
+     id="text683"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4602 4780 4886 5063 5241 5419 5597 5775 5952 6024 6202 6380 6609 6714 6786 6875 7053 7231 7409 7515 7587 7692"
+       y="6905"
+       id="tspan685">drbd_endio_write_pri()</tspan>
+  </text>
+  <path
+     d="M 12000,13602 L 11900,13302 L 12100,13302 L 12000,13602 z"
+     id="path695"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 12000,12802 L 12000,13362"
+     id="path699"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <path
+     d="M 12000,12802 L 11686,12841 L 11725,12645 L 12000,12802 z"
+     id="path711"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 8000,12002 L 11765,12755"
+     id="path715"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <text
+     x="-2155.5266"
+     y="1201.5964"
+     transform="matrix(0.9895258,-0.1443562,0.1443562,0.9895258,0,0)"
+     id="text733"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="7202.4736 7431.4736 7608.4736 7697.4736 7875.4736 8104.4736 8282.4736 8459.4736 8531.4736"
+       y="15454.597"
+       id="tspan735">DataReply</tspan>
+  </text>
+  <path
+     d="M 8000,14602 L 8282,14459 L 8312,14656 L 8000,14602 z"
+     id="path745"
+     style="fill:#008000;visibility:visible" />
+  <path
+     d="M 12000,14002 L 8237,14566"
+     id="path749"
+     style="fill:none;stroke:#008000;visibility:visible" />
+  <text
+     x="2280.3804"
+     y="-2103.2141"
+     transform="matrix(0.9788674,0.2044961,-0.2044961,0.9788674,0,0)"
+     id="text767"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="11316.381 11545.381 11722.381 11811.381 11989.381 12218.381 12396.381 12573.381 12751.381 12929.381 13090.381"
+       y="9981.7861"
+       id="tspan769">DataRequest</tspan>
+  </text>
+  <text
+     id="text783"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="4746 4924 5030 5207 5385 5563 5826 6003 6164 6342 6520 6626 6803 6981 7159 7337 7498 7587 7692"
+       y="11506"
+       id="tspan785">drbd_make_request()</tspan>
+  </text>
+  <text
+     id="text799"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12200 12306 12484 12645 12822 12894 13055 13233 13411 13639 13817 13906 14084 14312 14490 14668 14846 15024 15185 15273 15379"
+       y="12807"
+       id="tspan801">receive_DataRequest()</tspan>
+  </text>
+  <text
+     id="text815"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12200 12378 12484 12661 12839 13017 13195 13373 13550 13622 13800 13978 14084 14262 14439 14617 14795 14956 15134 15295 15400"
+       y="13607"
+       id="tspan817">drbd_endio_read_sec()</tspan>
+  </text>
+  <text
+     id="text831"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="12192 12421 12598 12776 12954 13132 13310 13487 13665 13843 14021 14110 14288 14465 14571 14749 14927 15033"
+       y="14008"
+       id="tspan833">w_e_end_data_req()</tspan>
+  </text>
+  <g
+     id="g835"
+     style="visibility:visible">
+    <desc
+       id="desc837">Drawing</desc>
+    <text
+       id="text847"
+       style="font-size:318px;font-weight:400;fill:#008000;font-family:Helvetica embedded">
+      <tspan
+         x="4885 4991 5169 5330 5507 5579 5740 5918 6096 6324 6502 6591 6769 6997 7175 7353 7425 7586 7692"
+         y="14607"
+         id="tspan849">receive_DataReply()</tspan>
+    </text>
+  </g>
+  <text
+     id="text863"
+     style="font-size:423px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="8000 8305 8398 8610 8821 8914 9151 9363 9575 9693 9833 10070 10307 10544 10663 10781 11018 11255 11493 11632 11869 12106"
+       y="10878"
+       id="tspan865">Diskless read, 512-32K</tspan>
+  </text>
+  <text
+     id="text879"
+     style="font-size:318px;font-weight:400;fill:#008000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="5029 5258 5435 5596 5774 5952 6130 6307 6413 6591 6769 6947 7125 7230 7408 7586 7692"
+       y="12004"
+       id="tspan881">w_send_read_req()</tspan>
+  </text>
+  <text
+     id="text895"
+     style="font-size:423px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="6961 7266 7571 7854 8159 8278 8515 8633 8870 9107 9226 9463 9581 9700 9793 10030"
+       y="2806"
+       id="tspan897">DRBD 8 data flow</tspan>
+  </text>
+  <path
+     d="M 3900,5300 L 3700,5300 L 3700,7000 L 3900,7000"
+     id="path907"
+     style="fill:none;stroke:#000000;visibility:visible" />
+  <path
+     d="M 3900,17600 L 3700,17600 L 3700,22000 L 3900,22000"
+     id="path919"
+     style="fill:none;stroke:#000000;visibility:visible" />
+  <path
+     d="M 16100,20000 L 16300,20000 L 16300,18500 L 16100,18500"
+     id="path931"
+     style="fill:none;stroke:#000000;visibility:visible" />
+  <text
+     id="text947"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="2126 2304 2376 2554 2731 2909 3087 3159 3337 3515 3587 3764 3870"
+       y="5202"
+       id="tspan949">al_begin_io()</tspan>
+  </text>
+  <text
+     id="text963"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="1632 1810 1882 2060 2220 2398 2661 2839 2910 3088 3177 3355 3533 3605 3783 3888"
+       y="7331"
+       id="tspan965">al_complete_io()</tspan>
+  </text>
+  <text
+     id="text979"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="2126 2232 2393 2571 2748 2926 3104 3176 3354 3531 3603 3781 3887"
+       y="17431"
+       id="tspan981">rs_begin_io()</tspan>
+  </text>
+  <text
+     id="text995"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="1626 1732 1893 2071 2231 2409 2672 2849 2921 3099 3188 3366 3544 3616 3793 3899"
+       y="22331"
+       id="tspan997">rs_complete_io()</tspan>
+  </text>
+  <text
+     id="text1011"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="16027 16133 16294 16472 16649 16827 17005 17077 17255 17432 17504 17682 17788"
+       y="18402"
+       id="tspan1013">rs_begin_io()</tspan>
+  </text>
+  <text
+     id="text1027"
+     style="font-size:318px;font-weight:400;fill:#000000;visibility:visible;font-family:Helvetica embedded">
+    <tspan
+       x="16115 16221 16382 16560 16720 16898 17161 17338 17410 17588 17677 17855 18033 18105 18282 18388"
+       y="20331"
+       id="tspan1029">rs_complete_io()</tspan>
+  </text>
+</svg>
diff --git a/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot b/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot
new file mode 100644
index 000000000..025e8cf5e
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/conn-states-8.dot
@@ -0,0 +1,18 @@
+digraph conn_states {
+	StandAllone  -> WFConnection   [ label = "ioctl_set_net()" ]
+	WFConnection -> Unconnected    [ label = "unable to bind()" ]
+	WFConnection -> WFReportParams [ label = "in connect() after accept" ]
+	WFReportParams -> StandAllone  [ label = "checks in receive_param()" ]
+	WFReportParams -> Connected    [ label = "in receive_param()" ]
+	WFReportParams -> WFBitMapS    [ label = "sync_handshake()" ]
+	WFReportParams -> WFBitMapT    [ label = "sync_handshake()" ]
+	WFBitMapS -> SyncSource        [ label = "receive_bitmap()" ]
+	WFBitMapT -> SyncTarget        [ label = "receive_bitmap()" ]
+	SyncSource -> Connected
+	SyncTarget -> Connected
+	SyncSource -> PausedSyncS
+	SyncTarget -> PausedSyncT
+	PausedSyncS -> SyncSource
+	PausedSyncT -> SyncTarget
+	Connected   -> WFConnection    [ label = "* on network error" ]
+}
diff --git a/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst b/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst
new file mode 100644
index 000000000..66036b901
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/data-structure-v9.rst
@@ -0,0 +1,42 @@
+================================
+kernel data structure for DRBD-9
+================================
+
+This describes the in kernel data structure for DRBD-9. Starting with
+Linux v3.14 we are reorganizing DRBD to use this data structure.
+
+Basic Data Structure
+====================
+
+A node has a number of DRBD resources.  Each such resource has a number of
+devices (aka volumes) and connections to other nodes ("peer nodes"). Each DRBD
+device is represented by a block device locally.
+
+The DRBD objects are interconnected to form a matrix as depicted below; a
+drbd_peer_device object sits at each intersection between a drbd_device and a
+drbd_connection::
+
+  /--------------+---------------+.....+---------------\
+  |   resource   |    device     |     |    device     |
+  +--------------+---------------+.....+---------------+
+  |  connection  |  peer_device  |     |  peer_device  |
+  +--------------+---------------+.....+---------------+
+  :              :               :     :               :
+  :              :               :     :               :
+  +--------------+---------------+.....+---------------+
+  |  connection  |  peer_device  |     |  peer_device  |
+  \--------------+---------------+.....+---------------/
+
+In this table, horizontally, devices can be accessed from resources by their
+volume number.  Likewise, peer_devices can be accessed from connections by
+their volume number.  Objects in the vertical direction are connected by double
+linked lists.  There are back pointers from peer_devices to their connections a
+devices, and from connections and devices to their resource.
+
+All resources are in the drbd_resources double-linked list.  In addition, all
+devices can be accessed by their minor device number via the drbd_devices idr.
+
+The drbd_resource, drbd_connection, and drbd_device objects are reference
+counted.  The peer_device objects only serve to establish the links between
+devices and connections; their lifetime is determined by the lifetime of the
+device and connection which they reference.
diff --git a/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot b/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot
new file mode 100644
index 000000000..d06cfb46f
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/disk-states-8.dot
@@ -0,0 +1,16 @@
+digraph disk_states {
+	Diskless -> Inconsistent       [ label = "ioctl_set_disk()" ]
+	Diskless -> Consistent         [ label = "ioctl_set_disk()" ]
+	Diskless -> Outdated           [ label = "ioctl_set_disk()" ]
+	Consistent -> Outdated         [ label = "receive_param()" ]
+	Consistent -> UpToDate         [ label = "receive_param()" ]
+	Consistent -> Inconsistent     [ label = "start resync" ]
+	Outdated   -> Inconsistent     [ label = "start resync" ]
+	UpToDate   -> Inconsistent     [ label = "ioctl_replicate" ]
+	Inconsistent -> UpToDate       [ label = "resync completed" ]
+	Consistent -> Failed           [ label = "io completion error" ]
+	Outdated   -> Failed           [ label = "io completion error" ]
+	UpToDate   -> Failed           [ label = "io completion error" ]
+	Inconsistent -> Failed         [ label = "io completion error" ]
+	Failed -> Diskless             [ label = "sending notify to peer" ]
+}
diff --git a/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot b/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot
new file mode 100644
index 000000000..6d9cf0a7b
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/drbd-connection-state-overview.dot
@@ -0,0 +1,85 @@
+// vim: set sw=2 sts=2 :
+digraph {
+  rankdir=BT
+  bgcolor=white
+
+  node [shape=plaintext]
+  node [fontcolor=black]
+
+  StandAlone     [ style=filled,fillcolor=gray,label=StandAlone ]
+
+  node [fontcolor=lightgray]
+
+  Unconnected    [ label=Unconnected ]
+
+  CommTrouble [ shape=record,
+    label="{communication loss|{Timeout|BrokenPipe|NetworkFailure}}" ]
+
+  node [fontcolor=gray]
+
+  subgraph cluster_try_connect {
+    label="try to connect, handshake"
+    rank=max
+    WFConnection   [ label=WFConnection ]
+    WFReportParams [ label=WFReportParams ]
+  }
+
+  TearDown       [ label=TearDown ]
+
+  Connected      [ label=Connected,style=filled,fillcolor=green,fontcolor=black ]
+
+  node [fontcolor=lightblue]
+
+  StartingSyncS  [ label=StartingSyncS ]
+  StartingSyncT  [ label=StartingSyncT ]
+
+  subgraph cluster_bitmap_exchange {
+    node [fontcolor=red]
+    fontcolor=red
+    label="new application (WRITE?) requests blocked\lwhile bitmap is exchanged"
+
+    WFBitMapT      [ label=WFBitMapT ]
+    WFSyncUUID     [ label=WFSyncUUID ]
+    WFBitMapS      [ label=WFBitMapS ]
+  }
+
+  node [fontcolor=blue]
+
+  cluster_resync [ shape=record,label="{<any>resynchronisation process running\l'concurrent' application requests allowed|{{<T>PausedSyncT\nSyncTarget}|{<S>PausedSyncS\nSyncSource}}}" ]
+
+  node [shape=box,fontcolor=black]
+
+  // drbdadm [label="drbdadm connect"]
+  // handshake [label="drbd_connect()\ndrbd_do_handshake\ndrbd_sync_handshake() etc."]
+  // comm_error [label="communication trouble"]
+
+  //
+  // edges
+  // --------------------------------------
+
+  StandAlone -> Unconnected [ label="drbdadm connect" ]
+  Unconnected -> StandAlone  [ label="drbdadm disconnect\lor serious communication trouble" ]
+  Unconnected -> WFConnection [ label="receiver thread is started" ]
+  WFConnection -> WFReportParams [ headlabel="accept()\land/or                        \lconnect()\l" ]
+
+  WFReportParams -> StandAlone [ label="during handshake\lpeers do not agree\labout something essential" ]
+  WFReportParams -> Connected [ label="data identical\lno sync needed",color=green,fontcolor=green ]
+
+    WFReportParams -> WFBitMapS
+    WFReportParams -> WFBitMapT
+    WFBitMapT -> WFSyncUUID [minlen=0.1,constraint=false]
+
+      WFBitMapS -> cluster_resync:S
+      WFSyncUUID -> cluster_resync:T
+
+  edge [color=green]
+  cluster_resync:any -> Connected [ label="resnyc done",fontcolor=green ]
+
+  edge [color=red]
+  WFReportParams -> CommTrouble
+  Connected -> CommTrouble
+  cluster_resync:any -> CommTrouble
+  edge [color=black]
+  CommTrouble -> Unconnected [label="receiver thread is stopped" ]
+
+}
diff --git a/Documentation/admin-guide/blockdev/drbd/figures.rst b/Documentation/admin-guide/blockdev/drbd/figures.rst
new file mode 100644
index 000000000..9f73253ea
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/figures.rst
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. The here included files are intended to help understand the implementation
+
+Data flows that Relate some functions, and write packets
+========================================================
+
+.. kernel-figure:: DRBD-8.3-data-packets.svg
+    :alt:   DRBD-8.3-data-packets.svg
+    :align: center
+
+.. kernel-figure:: DRBD-data-packets.svg
+    :alt:   DRBD-data-packets.svg
+    :align: center
+
+
+Sub graphs of DRBD's state transitions
+======================================
+
+.. kernel-figure:: conn-states-8.dot
+    :alt:   conn-states-8.dot
+    :align: center
+
+.. kernel-figure:: disk-states-8.dot
+    :alt:   disk-states-8.dot
+    :align: center
+
+.. kernel-figure:: peer-states-8.dot
+    :alt:   peer-states-8.dot
+    :align: center
diff --git a/Documentation/admin-guide/blockdev/drbd/index.rst b/Documentation/admin-guide/blockdev/drbd/index.rst
new file mode 100644
index 000000000..561fd1e35
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/index.rst
@@ -0,0 +1,19 @@
+==========================================
+Distributed Replicated Block Device - DRBD
+==========================================
+
+Description
+===========
+
+  DRBD is a shared-nothing, synchronously replicated block device. It
+  is designed to serve as a building block for high availability
+  clusters and in this context, is a "drop-in" replacement for shared
+  storage. Simplistically, you could see it as a network RAID 1.
+
+  Please visit https://www.drbd.org to find out more.
+
+.. toctree::
+   :maxdepth: 1
+
+   data-structure-v9
+   figures
diff --git a/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot b/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot
new file mode 100644
index 000000000..6dc395495
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/drbd/peer-states-8.dot
@@ -0,0 +1,8 @@
+digraph peer_states {
+	Secondary -> Primary           [ label = "recv state packet" ]
+	Primary   -> Secondary 	       [ label = "recv state packet" ]
+	Primary   -> Unknown 	       [ label = "connection lost" ]
+	Secondary  -> Unknown  	       [ label = "connection lost" ]
+	Unknown   -> Primary           [ label = "connected" ]
+	Unknown   -> Secondary         [ label = "connected" ]
+}
diff --git a/Documentation/admin-guide/blockdev/floppy.rst b/Documentation/admin-guide/blockdev/floppy.rst
new file mode 100644
index 000000000..0328438eb
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/floppy.rst
@@ -0,0 +1,255 @@
+=============
+Floppy Driver
+=============
+
+FAQ list:
+=========
+
+A FAQ list may be found in the fdutils package (see below), and also
+at <https://fdutils.linux.lu/faq.html>.
+
+
+LILO configuration options (Thinkpad users, read this)
+======================================================
+
+The floppy driver is configured using the 'floppy=' option in
+lilo. This option can be typed at the boot prompt, or entered in the
+lilo configuration file.
+
+Example: If your kernel is called linux-2.6.9, type the following line
+at the lilo boot prompt (if you have a thinkpad)::
+
+ linux-2.6.9 floppy=thinkpad
+
+You may also enter the following line in /etc/lilo.conf, in the description
+of linux-2.6.9::
+
+ append = "floppy=thinkpad"
+
+Several floppy related options may be given, example::
+
+ linux-2.6.9 floppy=daring floppy=two_fdc
+ append = "floppy=daring floppy=two_fdc"
+
+If you give options both in the lilo config file and on the boot
+prompt, the option strings of both places are concatenated, the boot
+prompt options coming last. That's why there are also options to
+restore the default behavior.
+
+
+Module configuration options
+============================
+
+If you use the floppy driver as a module, use the following syntax::
+
+	modprobe floppy floppy="<options>"
+
+Example::
+
+	modprobe floppy floppy="omnibook messages"
+
+If you need certain options enabled every time you load the floppy driver,
+you can put::
+
+	options floppy floppy="omnibook messages"
+
+in a configuration file in /etc/modprobe.d/.
+
+
+The floppy driver related options are:
+
+ floppy=asus_pci
+	Sets the bit mask to allow only units 0 and 1. (default)
+
+ floppy=daring
+	Tells the floppy driver that you have a well behaved floppy controller.
+	This allows more efficient and smoother operation, but may fail on
+	certain controllers. This may speed up certain operations.
+
+ floppy=0,daring
+	Tells the floppy driver that your floppy controller should be used
+	with caution.
+
+ floppy=one_fdc
+	Tells the floppy driver that you have only one floppy controller.
+	(default)
+
+ floppy=two_fdc / floppy=<address>,two_fdc
+	Tells the floppy driver that you have two floppy controllers.
+	The second floppy controller is assumed to be at <address>.
+	This option is not needed if the second controller is at address
+	0x370, and if you use the 'cmos' option.
+
+ floppy=thinkpad
+	Tells the floppy driver that you have a Thinkpad. Thinkpads use an
+	inverted convention for the disk change line.
+
+ floppy=0,thinkpad
+	Tells the floppy driver that you don't have a Thinkpad.
+
+ floppy=omnibook / floppy=nodma
+	Tells the floppy driver not to use Dma for data transfers.
+	This is needed on HP Omnibooks, which don't have a workable
+	DMA channel for the floppy driver. This option is also useful
+	if you frequently get "Unable to allocate DMA memory" messages.
+	Indeed, dma memory needs to be continuous in physical memory,
+	and is thus harder to find, whereas non-dma buffers may be
+	allocated in virtual memory. However, I advise against this if
+	you have an FDC without a FIFO (8272A or 82072). 82072A and
+	later are OK. You also need at least a 486 to use nodma.
+	If you use nodma mode, I suggest you also set the FIFO
+	threshold to 10 or lower, in order to limit the number of data
+	transfer interrupts.
+
+	If you have a FIFO-able FDC, the floppy driver automatically
+	falls back on non DMA mode if no DMA-able memory can be found.
+	If you want to avoid this, explicitly ask for 'yesdma'.
+
+ floppy=yesdma
+	Tells the floppy driver that a workable DMA channel is available.
+	(default)
+
+ floppy=nofifo
+	Disables the FIFO entirely. This is needed if you get "Bus
+	master arbitration error" messages from your Ethernet card (or
+	from other devices) while accessing the floppy.
+
+ floppy=usefifo
+	Enables the FIFO. (default)
+
+ floppy=<threshold>,fifo_depth
+	Sets the FIFO threshold. This is mostly relevant in DMA
+	mode. If this is higher, the floppy driver tolerates more
+	interrupt latency, but it triggers more interrupts (i.e. it
+	imposes more load on the rest of the system). If this is
+	lower, the interrupt latency should be lower too (faster
+	processor). The benefit of a lower threshold is less
+	interrupts.
+
+	To tune the fifo threshold, switch on over/underrun messages
+	using 'floppycontrol --messages'. Then access a floppy
+	disk. If you get a huge amount of "Over/Underrun - retrying"
+	messages, then the fifo threshold is too low. Try with a
+	higher value, until you only get an occasional Over/Underrun.
+	It is a good idea to compile the floppy driver as a module
+	when doing this tuning. Indeed, it allows to try different
+	fifo values without rebooting the machine for each test. Note
+	that you need to do 'floppycontrol --messages' every time you
+	re-insert the module.
+
+	Usually, tuning the fifo threshold should not be needed, as
+	the default (0xa) is reasonable.
+
+ floppy=<drive>,<type>,cmos
+	Sets the CMOS type of <drive> to <type>. This is mandatory if
+	you have more than two floppy drives (only two can be
+	described in the physical CMOS), or if your BIOS uses
+	non-standard CMOS types. The CMOS types are:
+
+	       ==  ==================================
+		0  Use the value of the physical CMOS
+		1  5 1/4 DD
+		2  5 1/4 HD
+		3  3 1/2 DD
+		4  3 1/2 HD
+		5  3 1/2 ED
+		6  3 1/2 ED
+	       16  unknown or not installed
+	       ==  ==================================
+
+	(Note: there are two valid types for ED drives. This is because 5 was
+	initially chosen to represent floppy *tapes*, and 6 for ED drives.
+	AMI ignored this, and used 5 for ED drives. That's why the floppy
+	driver handles both.)
+
+ floppy=unexpected_interrupts
+	Print a warning message when an unexpected interrupt is received.
+	(default)
+
+ floppy=no_unexpected_interrupts / floppy=L40SX
+	Don't print a message when an unexpected interrupt is received. This
+	is needed on IBM L40SX laptops in certain video modes. (There seems
+	to be an interaction between video and floppy. The unexpected
+	interrupts affect only performance, and can be safely ignored.)
+
+ floppy=broken_dcl
+	Don't use the disk change line, but assume that the disk was
+	changed whenever the device node is reopened. Needed on some
+	boxes where the disk change line is broken or unsupported.
+	This should be regarded as a stopgap measure, indeed it makes
+	floppy operation less efficient due to unneeded cache
+	flushings, and slightly more unreliable. Please verify your
+	cable, connection and jumper settings if you have any DCL
+	problems. However, some older drives, and also some laptops
+	are known not to have a DCL.
+
+ floppy=debug
+	Print debugging messages.
+
+ floppy=messages
+	Print informational messages for some operations (disk change
+	notifications, warnings about over and underruns, and about
+	autodetection).
+
+ floppy=silent_dcl_clear
+	Uses a less noisy way to clear the disk change line (which
+	doesn't involve seeks). Implied by 'daring' option.
+
+ floppy=<nr>,irq
+	Sets the floppy IRQ to <nr> instead of 6.
+
+ floppy=<nr>,dma
+	Sets the floppy DMA channel to <nr> instead of 2.
+
+ floppy=slow
+	Use PS/2 stepping rate::
+
+	   PS/2 floppies have much slower step rates than regular floppies.
+	   It's been recommended that take about 1/4 of the default speed
+	   in some more extreme cases.
+
+
+Supporting utilities and additional documentation:
+==================================================
+
+Additional parameters of the floppy driver can be configured at
+runtime. Utilities which do this can be found in the fdutils package.
+This package also contains a new version of mtools which allows to
+access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
+It also contains additional documentation about the floppy driver.
+
+The latest version can be found at fdutils homepage:
+
+ https://fdutils.linux.lu
+
+The fdutils releases can be found at:
+
+ https://fdutils.linux.lu/download.html
+
+ http://www.tux.org/pub/knaff/fdutils/
+
+ ftp://metalab.unc.edu/pub/Linux/utils/disk-management/
+
+Reporting problems about the floppy driver
+==========================================
+
+If you have a question or a bug report about the floppy driver, mail
+me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
+comp.os.linux.hardware. As the volume in these groups is rather high,
+be sure to include the word "floppy" (or "FLOPPY") in the subject
+line.  If the reported problem happens when mounting floppy disks, be
+sure to mention also the type of the filesystem in the subject line.
+
+Be sure to read the FAQ before mailing/posting any bug reports!
+
+Alain
+
+Changelog
+=========
+
+10-30-2004 :
+		Cleanup, updating, add reference to module configuration.
+		James Nelson <james4765@gmail.com>
+
+6-3-2000 :
+		Original Document
diff --git a/Documentation/admin-guide/blockdev/index.rst b/Documentation/admin-guide/blockdev/index.rst
new file mode 100644
index 000000000..3262397eb
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/index.rst
@@ -0,0 +1,17 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Block Devices
+=============
+
+.. toctree::
+   :maxdepth: 1
+
+   floppy
+   nbd
+   paride
+   ramdisk
+   zoned_loop
+   zram
+
+   drbd/index
diff --git a/Documentation/admin-guide/blockdev/nbd.rst b/Documentation/admin-guide/blockdev/nbd.rst
new file mode 100644
index 000000000..faf2ac4b1
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/nbd.rst
@@ -0,0 +1,31 @@
+==================================
+Network Block Device (TCP version)
+==================================
+
+1) Overview
+-----------
+
+What is it: With this compiled in the kernel (or as a module), Linux
+can use a remote server as one of its block devices. So every time
+the client computer wants to read, e.g., /dev/nb0, it sends a
+request over TCP to the server, which will reply with the data read.
+This can be used for stations with low disk space (or even diskless)
+to borrow disk space from another computer.
+Unlike NFS, it is possible to put any filesystem on it, etc.
+
+For more information, or to download the nbd-client and nbd-server
+tools, go to https://github.com/NetworkBlockDevice/nbd.
+
+The nbd kernel module need only be installed on the client
+system, as the nbd-server is completely in userspace. In fact,
+the nbd-server has been successfully ported to other operating
+systems, including Windows.
+
+A) NBD parameters
+-----------------
+
+max_part
+	Number of partitions per device (default: 0).
+
+nbds_max
+	Number of block devices that should be initialized (default: 16).
diff --git a/Documentation/admin-guide/blockdev/paride.rst b/Documentation/admin-guide/blockdev/paride.rst
new file mode 100644
index 000000000..b2f627d4c
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/paride.rst
@@ -0,0 +1,207 @@
+===================================
+Linux and parallel port IDE devices
+===================================
+
+PARIDE v1.03   (c) 1997-8  Grant Guenther <grant@torque.net>
+PATA_PARPORT   (c) 2023 Ondrej Zary
+
+1. Introduction
+===============
+
+Owing to the simplicity and near universality of the parallel port interface
+to personal computers, many external devices such as portable hard-disk,
+CD-ROM, LS-120 and tape drives use the parallel port to connect to their
+host computer.  While some devices (notably scanners) use ad-hoc methods
+to pass commands and data through the parallel port interface, most
+external devices are actually identical to an internal model, but with
+a parallel-port adapter chip added in.  Some of the original parallel port
+adapters were little more than mechanisms for multiplexing a SCSI bus.
+(The Iomega PPA-3 adapter used in the ZIP drives is an example of this
+approach).  Most current designs, however, take a different approach.
+The adapter chip reproduces a small ISA or IDE bus in the external device
+and the communication protocol provides operations for reading and writing
+device registers, as well as data block transfer functions.  Sometimes,
+the device being addressed via the parallel cable is a standard SCSI
+controller like an NCR 5380.  The "ditto" family of external tape
+drives use the ISA replicator to interface a floppy disk controller,
+which is then connected to a floppy-tape mechanism.  The vast majority
+of external parallel port devices, however, are now based on standard
+IDE type devices, which require no intermediate controller.  If one
+were to open up a parallel port CD-ROM drive, for instance, one would
+find a standard ATAPI CD-ROM drive, a power supply, and a single adapter
+that interconnected a standard PC parallel port cable and a standard
+IDE cable.  It is usually possible to exchange the CD-ROM device with
+any other device using the IDE interface.
+
+The document describes the support in Linux for parallel port IDE
+devices.  It does not cover parallel port SCSI devices, "ditto" tape
+drives or scanners.  Many different devices are supported by the
+parallel port IDE subsystem, including:
+
+	- MicroSolutions backpack CD-ROM
+	- MicroSolutions backpack PD/CD
+	- MicroSolutions backpack hard-drives
+	- MicroSolutions backpack 8000t tape drive
+	- SyQuest EZ-135, EZ-230 & SparQ drives
+	- Avatar Shark
+	- Imation Superdisk LS-120
+	- Maxell Superdisk LS-120
+	- FreeCom Power CD
+	- Hewlett-Packard 5GB and 8GB tape drives
+	- Hewlett-Packard 7100 and 7200 CD-RW drives
+
+as well as most of the clone and no-name products on the market.
+
+To support such a wide range of devices, pata_parport is actually structured
+in two parts. There is a base pata_parport module which provides an interface
+to kernel libata subsystem, registry and some common methods for accessing
+the parallel ports.
+
+The second component is a set of low-level protocol drivers for each of the
+parallel port IDE adapter chips.  Thanks to the interest and encouragement of
+Linux users from many parts of the world, support is available for almost all
+known adapter protocols:
+
+	====    ====================================== ====
+        aten    ATEN EH-100                            (HK)
+        bpck    Microsolutions backpack                (US)
+        comm    DataStor (old-type) "commuter" adapter (TW)
+        dstr    DataStor EP-2000                       (TW)
+        epat    Shuttle EPAT                           (UK)
+        epia    Shuttle EPIA                           (UK)
+	fit2    FIT TD-2000			       (US)
+	fit3    FIT TD-3000			       (US)
+	friq    Freecom IQ cable                       (DE)
+        frpw    Freecom Power                          (DE)
+        kbic    KingByte KBIC-951A and KBIC-971A       (TW)
+	ktti    KT Technology PHd adapter              (SG)
+        on20    OnSpec 90c20                           (US)
+        on26    OnSpec 90c26                           (US)
+	====    ====================================== ====
+
+
+2. Using pata_parport subsystem
+===============================
+
+While configuring the Linux kernel, you may choose either to build
+the pata_parport drivers into your kernel, or to build them as modules.
+
+In either case, you will need to select "Parallel port IDE device support"
+and at least one of the parallel port communication protocols.
+If you do not know what kind of parallel port adapter is used in your drive,
+you could begin by checking the file names and any text files on your DOS
+installation floppy.  Alternatively, you can look at the markings on
+the adapter chip itself.  That's usually sufficient to identify the
+correct device.
+
+You can actually select all the protocol modules, and allow the pata_parport
+subsystem to try them all for you.
+
+For the "brand-name" products listed above, here are the protocol
+and high-level drivers that you would use:
+
+	================	============	========
+	Manufacturer		Model		Protocol
+	================	============	========
+	MicroSolutions		CD-ROM		bpck
+	MicroSolutions		PD drive	bpck
+	MicroSolutions		hard-drive	bpck
+	MicroSolutions          8000t tape      bpck
+	SyQuest			EZ, SparQ	epat
+	Imation			Superdisk	epat
+	Maxell                  Superdisk       friq
+	Avatar			Shark		epat
+	FreeCom			CD-ROM		frpw
+	Hewlett-Packard		5GB Tape	epat
+	Hewlett-Packard		7200e (CD)	epat
+	Hewlett-Packard		7200e (CD-R)	epat
+	================	============	========
+
+All parports and all protocol drivers are probed automatically unless probe=0
+parameter is used. So just "modprobe epat" is enough for an Imation SuperDisk
+drive to work.
+
+Manual device creation::
+
+	# echo "port protocol mode unit delay" >/sys/bus/pata_parport/new_device
+
+where:
+
+	======== ================================================
+	port	 parport name (or "auto" for all parports)
+	protocol protocol name (or "auto" for all protocols)
+	mode	 mode number (protocol-specific) or -1 for probe
+	unit	 unit number (for backpack only, see below)
+	delay	 I/O delay (see troubleshooting section below)
+	======== ================================================
+
+If you happen to be using a MicroSolutions backpack device, you will
+also need to know the unit ID number for each drive.  This is usually
+the last two digits of the drive's serial number (but read MicroSolutions'
+documentation about this).
+
+If you omit the parameters from the end, defaults will be used, e.g.:
+
+Probe all parports with all protocols::
+
+	# echo auto >/sys/bus/pata_parport/new_device
+
+Probe parport0 using protocol epat and mode 4 (EPP-16)::
+
+	# echo "parport0 epat 4" >/sys/bus/pata_parport/new_device
+
+Probe parport0 using all protocols::
+
+	# echo "parport0 auto" >/sys/bus/pata_parport/new_device
+
+Probe all parports using protoocol epat::
+
+	# echo "auto epat" >/sys/bus/pata_parport/new_device
+
+Deleting devices::
+
+	# echo pata_parport.0 >/sys/bus/pata_parport/delete_device
+
+
+3. Troubleshooting
+==================
+
+3.1  Use EPP mode if you can
+----------------------------
+
+The most common problems that people report with the pata_parport drivers
+concern the parallel port CMOS settings.  At this time, none of the
+protocol modules support ECP mode, or any ECP combination modes.
+If you are able to do so, please set your parallel port into EPP mode
+using your CMOS setup procedure.
+
+3.2  Check the port delay
+-------------------------
+
+Some parallel ports cannot reliably transfer data at full speed.  To
+offset the errors, the protocol modules introduce a "port
+delay" between each access to the i/o ports.  Each protocol sets
+a default value for this delay.  In most cases, the user can override
+the default and set it to 0 - resulting in somewhat higher transfer
+rates.  In some rare cases (especially with older 486 systems) the
+default delays are not long enough.  if you experience corrupt data
+transfers, or unexpected failures, you may wish to increase the
+port delay.
+
+3.3  Some drives need a printer reset
+-------------------------------------
+
+There appear to be a number of "noname" external drives on the market
+that do not always power up correctly.  We have noticed this with some
+drives based on OnSpec and older Freecom adapters.  In these rare cases,
+the adapter can often be reinitialised by issuing a "printer reset" on
+the parallel port.  As the reset operation is potentially disruptive in
+multiple device environments, the pata_parport drivers will not do it
+automatically.  You can however, force a printer reset by doing::
+
+	insmod lp reset=1
+	rmmod lp
+
+If you have one of these marginal cases, you should probably build
+your pata_parport drivers as modules, and arrange to do the printer reset
+before loading the pata_parport drivers.
diff --git a/Documentation/admin-guide/blockdev/ramdisk.rst b/Documentation/admin-guide/blockdev/ramdisk.rst
new file mode 100644
index 000000000..9ce6101e8
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/ramdisk.rst
@@ -0,0 +1,153 @@
+==========================================
+Using the RAM disk block device with Linux
+==========================================
+
+.. Contents:
+
+	1) Overview
+	2) Kernel Command Line Parameters
+	3) Using "rdev"
+	4) An Example of Creating a Compressed RAM Disk
+
+
+1) Overview
+-----------
+
+The RAM disk driver is a way to use main system memory as a block device.  It
+is required for initrd, an initial filesystem used if you need to load modules
+in order to access the root filesystem (see Documentation/admin-guide/initrd.rst).  It can
+also be used for a temporary filesystem for crypto work, since the contents
+are erased on reboot.
+
+The RAM disk dynamically grows as more space is required. It does this by using
+RAM from the buffer cache. The driver marks the buffers it is using as dirty
+so that the VM subsystem does not try to reclaim them later.
+
+The RAM disk supports up to 16 RAM disks by default, and can be reconfigured
+to support an unlimited number of RAM disks (at your own risk).  Just change
+the configuration symbol BLK_DEV_RAM_COUNT in the Block drivers config menu
+and (re)build the kernel.
+
+To use RAM disk support with your system, run './MAKEDEV ram' from the /dev
+directory.  RAM disks are all major number 1, and start with minor number 0
+for /dev/ram0, etc.  If used, modern kernels use /dev/ram0 for an initrd.
+
+The new RAM disk also has the ability to load compressed RAM disk images,
+allowing one to squeeze more programs onto an average installation or
+rescue floppy disk.
+
+
+2) Parameters
+---------------------------------
+
+2a) Kernel Command Line Parameters
+
+	ramdisk_size=N
+		Size of the ramdisk.
+
+This parameter tells the RAM disk driver to set up RAM disks of N k size.  The
+default is 4096 (4 MB).
+
+2b) Module parameters
+
+	rd_nr
+		/dev/ramX devices created.
+
+	max_part
+		Maximum partition number.
+
+	rd_size
+		See ramdisk_size.
+
+3) Using "rdev"
+---------------
+
+"rdev" is an obsolete, deprecated, antiquated utility that could be used
+to set the boot device in a Linux kernel image.
+
+Instead of using rdev, just place the boot device information on the
+kernel command line and pass it to the kernel from the bootloader.
+
+You can also pass arguments to the kernel by setting FDARGS in
+arch/x86/boot/Makefile and specify in initrd image by setting FDINITRD in
+arch/x86/boot/Makefile.
+
+Some of the kernel command line boot options that may apply here are::
+
+  ramdisk_start=N
+  ramdisk_size=M
+
+If you make a boot disk that has LILO, then for the above, you would use::
+
+	append = "ramdisk_start=N ramdisk_size=M"
+
+4) An Example of Creating a Compressed RAM Disk
+-----------------------------------------------
+
+To create a RAM disk image, you will need a spare block device to
+construct it on. This can be the RAM disk device itself, or an
+unused disk partition (such as an unmounted swap partition). For this
+example, we will use the RAM disk device, "/dev/ram0".
+
+Note: This technique should not be done on a machine with less than 8 MB
+of RAM. If using a spare disk partition instead of /dev/ram0, then this
+restriction does not apply.
+
+a) Decide on the RAM disk size that you want. Say 2 MB for this example.
+   Create it by writing to the RAM disk device. (This step is not currently
+   required, but may be in the future.) It is wise to zero out the
+   area (esp. for disks) so that maximal compression is achieved for
+   the unused blocks of the image that you are about to create::
+
+	dd if=/dev/zero of=/dev/ram0 bs=1k count=2048
+
+b) Make a filesystem on it. Say ext2fs for this example::
+
+	mke2fs -vm0 /dev/ram0 2048
+
+c) Mount it, copy the files you want to it (eg: /etc/* /dev/* ...)
+   and unmount it again.
+
+d) Compress the contents of the RAM disk. The level of compression
+   will be approximately 50% of the space used by the files. Unused
+   space on the RAM disk will compress to almost nothing::
+
+	dd if=/dev/ram0 bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz
+
+e) Put the kernel onto the floppy::
+
+	dd if=zImage of=/dev/fd0 bs=1k
+
+f) Put the RAM disk image onto the floppy, after the kernel. Use an offset
+   that is slightly larger than the kernel, so that you can put another
+   (possibly larger) kernel onto the same floppy later without overlapping
+   the RAM disk image. An offset of 400 kB for kernels about 350 kB in
+   size would be reasonable. Make sure offset+size of ram_image.gz is
+   not larger than the total space on your floppy (usually 1440 kB)::
+
+	dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400
+
+g) Make sure that you have already specified the boot information in
+   FDARGS and FDINITRD or that you use a bootloader to pass kernel
+   command line boot options to the kernel.
+
+That is it. You now have your boot/root compressed RAM disk floppy. Some
+users may wish to combine steps (d) and (f) by using a pipe.
+
+
+						Paul Gortmaker 12/95
+
+Changelog:
+----------
+
+SEPT-2020 :
+
+                Removed usage of "rdev"
+
+10-22-04 :
+		Updated to reflect changes in command line options, remove
+		obsolete references, general cleanup.
+		James Nelson (james4765@gmail.com)
+
+12-95 :
+		Original Document
diff --git a/Documentation/admin-guide/blockdev/zoned_loop.rst b/Documentation/admin-guide/blockdev/zoned_loop.rst
new file mode 100644
index 000000000..64277494f
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/zoned_loop.rst
@@ -0,0 +1,191 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+Zoned Loop Block Device
+=======================
+
+.. Contents:
+
+	1) Overview
+	2) Creating a Zoned Device
+	3) Deleting a Zoned Device
+	4) Example
+
+
+1) Overview
+-----------
+
+The zoned loop block device driver (zloop) allows a user to create a zoned block
+device using one regular file per zone as backing storage. This driver does not
+directly control any hardware and uses read, write and truncate operations to
+regular files of a file system to emulate a zoned block device.
+
+Using zloop, zoned block devices with a configurable capacity, zone size and
+number of conventional zones can be created. The storage for each zone of the
+device is implemented using a regular file with a maximum size equal to the zone
+size. The size of a file backing a conventional zone is always equal to the zone
+size. The size of a file backing a sequential zone indicates the amount of data
+sequentially written to the file, that is, the size of the file directly
+indicates the position of the write pointer of the zone.
+
+When resetting a sequential zone, its backing file size is truncated to zero.
+Conversely, for a zone finish operation, the backing file is truncated to the
+zone capacity. With this, a zloop zoned block device can be configured with a
+larger capacity than the storage space available on the backing file system. Of
+course, for such configuration, writing more data than the storage space
+available on the backing file system will result in write errors.
+
+The zoned loop block device driver implements a complete zone transition state
+machine. That is, zones can be empty, implicitly opened, explicitly opened,
+closed or full. The current implementation does not support any limits on the
+maximum number of open and active zones.
+
+No user tools are necessary to create and delete zloop devices.
+
+2) Creating a Zoned Device
+--------------------------
+
+Once the zloop module is loaded (or if zloop is compiled in the kernel), the
+character device file /dev/zloop-control can be used to add a zloop device.
+This is done by writing an "add" command directly to the /dev/zloop-control
+device::
+
+	$ modprobe zloop
+        $ ls -l /dev/zloop*
+        crw-------. 1 root root 10, 123 Jan  6 19:18 /dev/zloop-control
+
+        $ mkdir -p <base directory/<device ID>
+        $ echo "add [options]" > /dev/zloop-control
+
+The options available for the add command can be listed by reading the
+/dev/zloop-control device::
+
+	$ cat /dev/zloop-control
+        add id=%d,capacity_mb=%u,zone_size_mb=%u,zone_capacity_mb=%u,conv_zones=%u,max_open_zones=%u,base_dir=%s,nr_queues=%u,queue_depth=%u,buffered_io,zone_append=%u,ordered_zone_append,discard_write_cache
+        remove id=%d
+
+In more details, the options that can be used with the "add" command are as
+follows.
+
+===================   =========================================================
+id                    Device number (the X in /dev/zloopX).
+                      Default: automatically assigned.
+capacity_mb           Device total capacity in MiB. A smaller last zone is not
+                      supported, so a capacity value that is not a multiple of
+                      the zone size is rounded down to the closest multiple of
+                      the zone size.
+                      Default: 16384 MiB (16 GiB).
+zone_size_mb          Device zone size in MiB. Default: 256 MiB.
+zone_capacity_mb      Device zone capacity (must always be equal to or lower
+                      than the zone size. Default: zone size.
+conv_zones            Total number of conventioanl zones starting from
+                      sector 0
+                      Default: 8
+max_open_zones        Maximum number of open sequential write required zones
+                      (0 for no limit).
+                      Default: 0
+base_dir              Path to the base directory where to create the directory
+                      containing the zone files of the device.
+                      Default=/var/local/zloop.
+                      The device directory containing the zone files is always
+                      named with the device ID. E.g. the default zone file
+                      directory for /dev/zloop0 is /var/local/zloop/0.
+nr_queues             Number of I/O queues of the zoned block device. This
+                      value is always capped by the number of online CPUs
+                      Default: 1
+queue_depth           Maximum I/O queue depth per I/O queue.
+                      Default: 64
+buffered_io           Do buffered IOs instead of direct IOs (default: false)
+zone_append           Enable or disable a zloop device native zone append
+                      support.
+                      Default: 1 (enabled).
+                      If native zone append support is disabled, the block layer
+                      will emulate this operation using regular write
+                      operations.
+ordered_zone_append   Enable zloop mitigation of zone append reordering.
+                      Default: disabled.
+                      This is useful for testing file systems file data mapping
+                      (extents), as when enabled, this can significantly reduce
+                      the number of data extents needed to for a file data
+                      mapping.
+discard_write_cache   Discard all data that was not explicitly persisted using a
+                      flush operation when the device is removed by truncating
+                      each zone file to the size recorded during the last flush
+                      operation. This simulates power fail events where
+                      uncommitted data is lost.
+===================   =========================================================
+
+3) Deleting a Zoned Device
+--------------------------
+
+Deleting an unused zoned loop block device is done by issuing the "remove"
+command to /dev/zloop-control, specifying the ID of the device to remove::
+
+        $ echo "remove id=X" > /dev/zloop-control
+
+The remove command does not have any option.
+
+A zoned device that was removed can be re-added again without any change to the
+state of the device zones: the device zones are restored to their last state
+before the device was removed. Adding again a zoned device after it was removed
+must always be done using the same configuration as when the device was first
+added. If a zone configuration change is detected, an error will be returned and
+the zoned device will not be created.
+
+To fully delete a zoned device, after executing the remove operation, the device
+base directory containing the backing files of the device zones must be deleted.
+
+4) Example
+----------
+
+The following sequence of commands creates a 2GB zoned device with zones of 64
+MB and a zone capacity of 63 MB::
+
+        $ modprobe zloop
+        $ mkdir -p /var/local/zloop/0
+        $ echo "add capacity_mb=2048,zone_size_mb=64,zone_capacity_mb=63" > /dev/zloop-control
+
+For the device created (/dev/zloop0), the zone backing files are all created
+under the default base directory (/var/local/zloop)::
+
+        $ ls -l /var/local/zloop/0
+        total 0
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000000
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000001
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000002
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000003
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000004
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000005
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000006
+        -rw-------. 1 root root 67108864 Jan  6 22:23 cnv-000007
+        -rw-------. 1 root root        0 Jan  6 22:23 seq-000008
+        -rw-------. 1 root root        0 Jan  6 22:23 seq-000009
+        ...
+
+The zoned device created (/dev/zloop0) can then be used normally::
+
+        $ lsblk -z
+        NAME   ZONED        ZONE-SZ ZONE-NR ZONE-AMAX ZONE-OMAX ZONE-APP ZONE-WGRAN
+        zloop0 host-managed     64M      32         0         0       1M         4K
+        $ blkzone report /dev/zloop0
+          start: 0x000000000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000020000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000040000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000060000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000080000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000a0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000c0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x0000e0000, len 0x020000, cap 0x020000, wptr 0x000000 reset:0 non-seq:0, zcond: 0(nw) [type: 1(CONVENTIONAL)]
+          start: 0x000100000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)]
+          start: 0x000120000, len 0x020000, cap 0x01f800, wptr 0x000000 reset:0 non-seq:0, zcond: 1(em) [type: 2(SEQ_WRITE_REQUIRED)]
+          ...
+
+Deleting this device is done using the command::
+
+        $ echo "remove id=0" > /dev/zloop-control
+
+The removed device can be re-added again using the same "add" command as when
+the device was first created. To fully delete a zoned device, its backing files
+should also be deleted after executing the remove command::
+
+        $ rm -r /var/local/zloop/0
diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
new file mode 100644
index 000000000..148b7cf3b
--- /dev/null
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -0,0 +1,610 @@
+========================================
+zram: Compressed RAM-based block devices
+========================================
+
+Introduction
+============
+
+The zram module creates RAM-based block devices named /dev/zram<id>
+(<id> = 0, 1, ...). Pages written to these disks are compressed and stored
+in memory itself. These disks allow very fast I/O and compression provides
+good amounts of memory savings. Some of the use cases include /tmp storage,
+use as swap disks, various caches under /var and maybe many more. :)
+
+Statistics for individual zram devices are exported through sysfs nodes at
+/sys/block/zram<id>/
+
+Usage
+=====
+
+There are several ways to configure and manage zram device(-s):
+
+a) using zram and zram_control sysfs attributes
+b) using zramctl utility, provided by util-linux (util-linux@vger.kernel.org).
+
+In this document we will describe only 'manual' zram configuration steps,
+IOW, zram and zram_control sysfs attributes.
+
+In order to get a better idea about zramctl please consult util-linux
+documentation, zramctl man-page or `zramctl --help`. Please be informed
+that zram maintainers do not develop/maintain util-linux or zramctl, should
+you have any questions please contact util-linux@vger.kernel.org
+
+Following shows a typical sequence of steps for using zram.
+
+WARNING
+=======
+
+For the sake of simplicity we skip error checking parts in most of the
+examples below. However, it is your sole responsibility to handle errors.
+
+zram sysfs attributes always return negative values in case of errors.
+The list of possible return codes:
+
+========  =============================================================
+-EBUSY	  an attempt to modify an attribute that cannot be changed once
+	  the device has been initialised. Please reset device first.
+-ENOMEM	  zram was not able to allocate enough memory to fulfil your
+	  needs.
+-EINVAL	  invalid input has been provided.
+-EAGAIN	  re-try operation later (e.g. when attempting to run recompress
+	  and writeback simultaneously).
+========  =============================================================
+
+If you use 'echo', the returned value is set by the 'echo' utility,
+and, in general case, something like::
+
+	echo foo > /sys/block/zram0/comp_algorithm
+	if [ $? -ne 0 ]; then
+		handle_error
+	fi
+
+should suffice.
+
+Load Module
+===========
+
+::
+
+	modprobe zram num_devices=4
+
+This creates 4 devices: /dev/zram{0,1,2,3}
+
+num_devices parameter is optional and tells zram how many devices should be
+pre-created. Default: 1.
+
+Select compression algorithm
+============================
+
+Using comp_algorithm device attribute one can see available and
+currently selected (shown in square brackets) compression algorithms,
+or change the selected compression algorithm (once the device is initialised
+there is no way to change compression algorithm).
+
+Examples::
+
+	#show supported compression algorithms
+	cat /sys/block/zram0/comp_algorithm
+	lzo [lz4]
+
+	#select lzo compression algorithm
+	echo lzo > /sys/block/zram0/comp_algorithm
+
+For the time being, the `comp_algorithm` content shows only compression
+algorithms that are supported by zram.
+
+Set compression algorithm parameters: Optional
+==============================================
+
+Compression algorithms may support specific parameters which can be
+tweaked for particular dataset. ZRAM has an `algorithm_params` device
+attribute which provides a per-algorithm params configuration.
+
+For example, several compression algorithms support `level` parameter.
+In addition, certain compression algorithms support pre-trained dictionaries,
+which significantly change algorithms' characteristics. In order to configure
+compression algorithm to use external pre-trained dictionary, pass full
+path to the `dict` along with other parameters::
+
+	#pass path to pre-trained zstd dictionary
+	echo "algo=zstd dict=/etc/dictionary" > /sys/block/zram0/algorithm_params
+
+	#pass path to pre-trained zstd dictionary and compression level
+	echo "algo=zstd level=8 dict=/etc/dictionary" > \
+		/sys/block/zram0/algorithm_params
+
+	#same, but using algorithm priority
+	echo "algo=zstd priority=1" > /sys/block/zram0/recomp_algorithm
+	echo "priority=1 dict=/etc/dictionary" > \
+		/sys/block/zram0/algorithm_params
+
+Each write to `algorithm_params` replaces the entire set of parameters of
+the corresponding algorithm, parameters that are not listed in the write
+are reset to their default values.  Configure all of the parameters of an
+algorithm in one write::
+
+	#WRONG: the second write resets level back to its default value
+	echo "algo=zstd level=8" > /sys/block/zram0/algorithm_params
+	echo "algo=zstd dict=/etc/dictionary" > /sys/block/zram0/algorithm_params
+
+	#RIGHT
+	echo "algo=zstd level=8 dict=/etc/dictionary" > \
+		/sys/block/zram0/algorithm_params
+
+Select the compression algorithm before configuring its parameters.  The
+parameters of one algorithm are not necessarily valid for another one, so
+changing the algorithm of a particular priority resets that priority's
+parameters::
+
+	#WRONG: comp_algorithm write resets the previously configured level
+	echo "level=8" > /sys/block/zram0/algorithm_params
+	echo zstd > /sys/block/zram0/comp_algorithm
+
+	#RIGHT
+	echo zstd > /sys/block/zram0/comp_algorithm
+	echo "algo=zstd level=8" > /sys/block/zram0/algorithm_params
+
+Parameters are algorithm specific: not all algorithms support pre-trained
+dictionaries, not all algorithms support `level`. Furthermore, for certain
+algorithms `level` controls the compression level (the higher the value the
+better the compression ratio, it even can take negatives values for some
+algorithms), for other algorithms `level` is acceleration level (the higher
+the value the lower the compression ratio).
+
+Parameters are handed over to the compression algorithm when the device is
+initialised, hence invalid parameters (or parameters that the selected
+algorithm does not support) are reported by the `disksize` write, and not
+by the `algorithm_params` write that has configured them.
+
+Set Disksize
+============
+
+Set disk size by writing the value to sysfs node 'disksize'.
+The value can be either in bytes or you can use mem suffixes.
+Examples::
+
+	# Initialize /dev/zram0 with 50MB disksize
+	echo $((50*1024*1024)) > /sys/block/zram0/disksize
+
+	# Using mem suffixes
+	echo 256K > /sys/block/zram0/disksize
+	echo 512M > /sys/block/zram0/disksize
+	echo 1G > /sys/block/zram0/disksize
+
+Note:
+There is little point creating a zram of greater than twice the size of memory
+since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
+size of the disk when not in use so a huge zram is wasteful.
+
+Set memory limit: Optional
+==========================
+
+Set memory limit by writing the value to sysfs node 'mem_limit'.
+The value can be either in bytes or you can use mem suffixes.
+In addition, you could change the value in runtime.
+Examples::
+
+	# limit /dev/zram0 with 50MB memory
+	echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
+
+	# Using mem suffixes
+	echo 256K > /sys/block/zram0/mem_limit
+	echo 512M > /sys/block/zram0/mem_limit
+	echo 1G > /sys/block/zram0/mem_limit
+
+	# To disable memory limit
+	echo 0 > /sys/block/zram0/mem_limit
+
+Activate
+========
+
+::
+
+	mkswap /dev/zram0
+	swapon /dev/zram0
+
+	mkfs.ext4 /dev/zram1
+	mount /dev/zram1 /tmp
+
+Add/remove zram devices
+=======================
+
+zram provides a control interface, which enables dynamic (on-demand) device
+addition and removal.
+
+In order to add a new /dev/zramX device, perform a read operation on the hot_add
+attribute. This will return either the new device's device id (meaning that you
+can use /dev/zram<id>) or an error code.
+
+Example::
+
+	cat /sys/class/zram-control/hot_add
+	1
+
+To remove the existing /dev/zramX device (where X is a device id)
+execute::
+
+	echo X > /sys/class/zram-control/hot_remove
+
+Stats
+=====
+
+Per-device statistics are exported as various nodes under /sys/block/zram<id>/
+
+A brief description of exported device attributes follows. For more details
+please read Documentation/ABI/testing/sysfs-block-zram.
+
+======================  ======  ===============================================
+Name            	access            description
+======================  ======  ===============================================
+disksize          	RW	show and set the device's disk size
+initstate         	RO	shows the initialization state of the device
+reset             	WO	trigger device reset
+mem_used_max      	WO	reset the `mem_used_max` counter (see later)
+mem_limit         	WO	specifies the maximum amount of memory ZRAM can
+				use to store the compressed data
+writeback_limit   	WO	specifies the maximum amount of write IO zram
+				can write out to backing device as 4KB unit
+writeback_limit_enable  RW	show and set writeback_limit feature
+writeback_batch_size	RW	show and set maximum number of in-flight
+				writeback operations
+compressed_writeback	RW	show and set compressed writeback feature
+comp_algorithm    	RW	show and change the compression algorithm
+algorithm_params	WO	setup compression algorithm parameters
+compact           	WO	trigger memory compaction
+debug_stat        	RO	this file is used for zram debugging purposes
+backing_dev	  	RW	set up backend storage for zram to write out
+idle		  	WO	mark allocated slot as idle
+======================  ======  ===============================================
+
+User space is advised to use the following files to read the device statistics.
+
+File /sys/block/zram<id>/stat
+
+Represents block layer statistics. Read Documentation/block/stat.rst for
+details.
+
+File /sys/block/zram<id>/io_stat
+
+The stat file represents device's I/O statistics not accounted by block
+layer and, thus, not available in zram<id>/stat file. It consists of a
+single line of text and contains the following stats separated by
+whitespace:
+
+ =============    =============================================================
+ failed_reads     The number of failed reads
+ failed_writes    The number of failed writes
+ invalid_io       The number of non-page-size-aligned I/O requests
+ notify_free      Depending on device usage scenario it may account
+
+                  a) the number of pages freed because of swap slot free
+                     notifications
+                  b) the number of pages freed because of
+                     REQ_OP_DISCARD requests sent by bio. The former ones are
+                     sent to a swap block device when a swap slot is freed,
+                     which implies that this disk is being used as a swap disk.
+
+                  The latter ones are sent by filesystem mounted with
+                  discard option, whenever some data blocks are getting
+                  discarded.
+ =============    =============================================================
+
+File /sys/block/zram<id>/mm_stat
+
+The mm_stat file represents the device's mm statistics. It consists of a single
+line of text and contains the following stats separated by whitespace:
+
+ ================ =============================================================
+ orig_data_size   uncompressed size of data stored in this disk.
+                  Unit: bytes
+ compr_data_size  compressed size of data stored in this disk
+ mem_used_total   the amount of memory allocated for this disk. This
+                  includes allocator fragmentation and metadata overhead,
+                  allocated for this disk. So, allocator space efficiency
+                  can be calculated using compr_data_size and this statistic.
+                  Unit: bytes
+ mem_limit        the maximum amount of memory ZRAM can use to store
+                  the compressed data
+ mem_used_max     the maximum amount of memory zram has consumed to
+                  store the data
+ same_pages       the number of same element filled pages written to this disk.
+                  No memory is allocated for such pages.
+ pages_compacted  the number of pages freed during compaction
+ huge_pages	  the number of incompressible pages
+ huge_pages_since the number of incompressible pages since zram set up
+ ================ =============================================================
+
+File /sys/block/zram<id>/bd_stat
+
+The bd_stat file represents a device's backing device statistics. It consists of
+a single line of text and contains the following stats separated by whitespace:
+
+ ============== =============================================================
+ bd_count	size of data written in backing device.
+		Unit: 4K bytes
+ bd_reads	the number of reads from backing device
+		Unit: 4K bytes
+ bd_writes	the number of writes to backing device
+		Unit: 4K bytes
+ ============== =============================================================
+
+Deactivate
+==========
+
+::
+
+	swapoff /dev/zram0
+	umount /dev/zram1
+
+Reset
+=====
+
+	Write any positive value to 'reset' sysfs node::
+
+		echo 1 > /sys/block/zram0/reset
+		echo 1 > /sys/block/zram1/reset
+
+	This frees all the memory allocated for the given device and
+	resets the disksize to zero. You must set the disksize again
+	before reusing the device.
+
+Optional Feature
+================
+
+IDLE pages tracking
+-------------------
+
+zram has built-in support for idle pages tracking (that is, allocated but
+not used pages). This feature is useful for e.g. zram writeback and
+recompression. In order to mark pages as idle, execute the following command::
+
+	echo all > /sys/block/zramX/idle
+
+This will mark all allocated zram pages as idle. The idle mark will be
+removed only when the page (block) is accessed (e.g. overwritten or freed).
+Additionally, when CONFIG_ZRAM_TRACK_ENTRY_ACTIME is enabled, pages can be
+marked as idle based on how many seconds have passed since the last access to
+a particular zram page::
+
+	echo 86400 > /sys/block/zramX/idle
+
+In this example, all pages which haven't been accessed in more than 86400
+seconds (one day) will be marked idle.
+
+writeback
+---------
+
+With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page
+to backing storage rather than keeping it in memory.
+To use the feature, admin should set up backing device via::
+
+	echo /dev/sda5 > /sys/block/zramX/backing_dev
+
+before disksize setting. It supports only partitions at this moment.
+If admin wants to use incompressible page writeback, they could do it via::
+
+	echo huge > /sys/block/zramX/writeback
+
+Admin can request writeback of idle pages at right timing via::
+
+	echo idle > /sys/block/zramX/writeback
+
+With the command, zram will writeback idle pages from memory to the storage.
+
+Additionally, if a user choose to writeback only huge and idle pages
+this can be accomplished with::
+
+        echo huge_idle > /sys/block/zramX/writeback
+
+If a user chooses to writeback only incompressible pages (pages that none of
+algorithms can compress) this can be accomplished with::
+
+	echo incompressible > /sys/block/zramX/writeback
+
+If an admin wants to write a specific page in zram device to the backing device,
+they could write a page index into the interface::
+
+	echo "page_index=1251" > /sys/block/zramX/writeback
+
+In Linux 6.16 this interface underwent some rework.  First, the interface
+now supports `key=value` format for all of its parameters (`type=huge_idle`,
+etc.)  Second, the support for `page_indexes` was introduced, which specify
+`LOW-HIGH` range (or ranges) of pages to be written-back.  This reduces the
+number of syscalls, but more importantly this enables optimal post-processing
+target selection strategy. Usage example::
+
+	echo "type=idle" > /sys/block/zramX/writeback
+	echo "page_indexes=1-100 page_indexes=200-300" > \
+		/sys/block/zramX/writeback
+
+We also now permit multiple page_index params per call and a mix of
+single pages and page ranges::
+
+	echo page_index=42 page_index=99 page_indexes=100-200 \
+		page_indexes=500-700 > /sys/block/zramX/writeback
+
+If there are lots of write IO with flash device, potentially, it has
+flash wearout problem so that admin needs to design write limitation
+to guarantee storage health for entire product life.
+
+To overcome the concern, zram supports "writeback_limit" feature.
+The "writeback_limit_enable"'s default value is 0 so that it doesn't limit
+any writeback. IOW, if admin wants to apply writeback budget, they should
+enable writeback_limit_enable via::
+
+	$ echo 1 > /sys/block/zramX/writeback_limit_enable
+
+Once writeback_limit_enable is set, zram doesn't allow any writeback
+until admin sets the budget via /sys/block/zramX/writeback_limit.
+
+(If admin doesn't enable writeback_limit_enable, writeback_limit's value
+assigned via /sys/block/zramX/writeback_limit is meaningless.)
+
+If admin wants to limit writeback as per-day 400M, they could do it
+like below::
+
+	$ MB_SHIFT=20
+	$ 4K_SHIFT=12
+	$ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
+		/sys/block/zram0/writeback_limit.
+	$ echo 1 > /sys/block/zram0/writeback_limit_enable
+
+If admins want to allow further write again once the budget is exhausted,
+they could do it like below::
+
+	$ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
+		/sys/block/zram0/writeback_limit
+
+If an admin wants to see the remaining writeback budget since last set::
+
+	$ cat /sys/block/zramX/writeback_limit
+
+If an admin wants to disable writeback limit, they could do::
+
+	$ echo 0 > /sys/block/zramX/writeback_limit_enable
+
+The writeback_limit count will reset whenever you reset zram (e.g.,
+system reboot, echo 1 > /sys/block/zramX/reset) so keeping how many of
+writeback happened until you reset the zram to allocate extra writeback
+budget in next setting is user's job.
+
+By default zram stores written back pages in decompressed (raw) form, which
+means that writeback operation involves decompression of the page before
+writing it to the backing device.  This behavior can be changed by enabling
+`compressed_writeback` feature, which causes zram to write compressed pages
+to the backing device, thus avoiding decompression overhead.  To enable
+this feature, execute::
+
+	$ echo yes > /sys/block/zramX/compressed_writeback
+
+Note that this feature should be configured before the `zramX` device is
+initialized.
+
+Depending on backing device storage type, writeback operation may benefit
+from a higher number of in-flight write requests (batched writes).  The
+number of maximum in-flight writeback operations can be configured via
+`writeback_batch_size` attribute.  To change the default value (which is 32),
+execute::
+
+	$ echo 64 > /sys/block/zramX/writeback_batch_size
+
+If admin wants to measure writeback count in a certain period, they could
+know it via /sys/block/zram0/bd_stat's 3rd column.
+
+recompression
+-------------
+
+With `CONFIG_ZRAM_MULTI_COMP`, zram can recompress pages using alternative
+(secondary) compression algorithms. The basic idea is that alternative
+compression algorithm can provide better compression ratio at a price of
+(potentially) slower compression/decompression speeds. Alternative compression
+algorithm can, for example, be more successful compressing huge pages (those
+that default algorithm failed to compress). Another application is idle pages
+recompression - pages that are cold and sit in the memory can be recompressed
+using more effective algorithm and, hence, reduce zsmalloc memory usage.
+
+With `CONFIG_ZRAM_MULTI_COMP`, zram supports up to 4 compression algorithms:
+one primary and up to 3 secondary ones. Primary zram compressor is explained
+in "3) Select compression algorithm", secondary algorithms are configured
+using recomp_algorithm device attribute.
+
+Example:::
+
+	#show supported recompression algorithms
+	cat /sys/block/zramX/recomp_algorithm
+	#1: lzo lzo-rle lz4 lz4hc [zstd]
+	#2: lzo lzo-rle lz4 [lz4hc] zstd
+
+Alternative compression algorithms are sorted by priority. In the example
+above, zstd is used as the first alternative algorithm, which has priority
+of 1, while lz4hc is configured as a compression algorithm with priority 2.
+Alternative compression algorithm's priority is provided during algorithms
+configuration:::
+
+	#select zstd recompression algorithm, priority 1
+	echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm
+
+	#select deflate recompression algorithm, priority 2
+	echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm
+
+Another device attribute that `CONFIG_ZRAM_MULTI_COMP` enables is `recompress`,
+which controls recompression.
+
+Examples:::
+
+	#IDLE pages recompression is activated by `idle` mode
+	echo "type=idle priority=1" > /sys/block/zramX/recompress
+
+	#HUGE pages recompression is activated by `huge` mode
+	echo "type=huge priority=2" > /sys/block/zram0/recompress
+
+	#HUGE_IDLE pages recompression is activated by `huge_idle` mode
+	echo "type=huge_idle priority=1" > /sys/block/zramX/recompress
+
+The number of idle pages can be significant, so user-space can pass a size
+threshold (in bytes) to the recompress knob: zram will recompress only pages
+of equal or greater size:::
+
+	#recompress all pages larger than 3000 bytes
+	echo "threshold=3000 priority=1" > /sys/block/zramX/recompress
+
+	#recompress idle pages larger than 2000 bytes
+	echo "type=idle threshold=2000 priority=1" > \
+		/sys/block/zramX/recompress
+
+It is also possible to limit the number of pages zram re-compression will
+attempt to recompress:::
+
+	echo "type=huge_idle priority=1 max_pages=42" > \
+		/sys/block/zramX/recompress
+
+It is advised to always specify `priority` parameter.  While it is also
+possible to specify `algo` parameter, so that `zram` will use algorithm's
+name to determine the priority, it is not recommended, since it can lead to
+unexpected results when the same algorithm is configured with different
+priorities (e.g. different parameters).  `priority` is the only way to
+guarantee that the expected algorithm will be used.
+
+memory tracking
+===============
+
+With CONFIG_ZRAM_MEMORY_TRACKING, user can know information of the
+zram block. It could be useful to catch cold or incompressible
+pages of the process with*pagemap.
+
+If you enable the feature, you could see block state via
+/sys/kernel/debug/zram/zram0/block_state". The output is as follows::
+
+	  300    75.033841 .wh...
+	  301    63.806904 s.....
+	  302    63.806919 ..hi..
+	  303    62.801919 ....r.
+	  304   146.781902 ..hi.n
+
+First column
+	zram's block index.
+Second column
+	access time since the system was booted
+Third column
+	state of the block:
+
+	s:
+		same page
+	w:
+		written page to backing store
+	h:
+		huge page
+	i:
+		idle page
+	r:
+		recompressed page (secondary compression algorithm)
+	n:
+		none (including secondary) of algorithms could compress it
+
+First line of above example says 300th block is accessed at 75.033841sec
+and the block's state is huge so it is written back to the backing
+storage. It's a debugging feature so anyone shouldn't rely on it to work
+properly.
+
+Nitin Gupta
+ngupta@vflare.org
diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
new file mode 100644
index 000000000..3d6412458
--- /dev/null
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -0,0 +1,416 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _bootconfig:
+
+==================
+Boot Configuration
+==================
+
+:Author: Masami Hiramatsu <mhiramat@kernel.org>
+
+Overview
+========
+
+The boot configuration expands the current kernel command line to support
+additional key-value data when booting the kernel in an efficient way.
+This allows administrators to pass a structured-Key config file.
+
+Config File Syntax
+==================
+
+The boot config syntax is a simple structured key-value. Each key consists
+of dot-connected-words, and key and value are connected by ``=``. The value
+string has to be terminated by the following delimiters described below.
+
+Each key word must contain only alphabets, numbers, dash (``-``) or underscore
+(``_``). And each value only contains printable characters or spaces except
+for delimiters such as semi-colon (``;``), new-line (``\n``), comma (``,``),
+hash (``#``) and closing brace (``}``).
+
+If the ``=`` is followed by whitespace up to one of these delimiters, the
+key is assigned an empty value.
+
+For arrays, the array values are comma (``,``) separated, and comments and
+line breaks with newline (``\n``) are allowed between array values for
+readability. Thus the first entry of the array must be on the same line as
+the key.::
+
+  KEY[.WORD[...]] = VALUE[, VALUE2[...]][;]
+
+Unlike the kernel command line syntax, white spaces (including tabs) are
+ignored around the comma and ``=``.
+
+If you want to use those delimiters in a value, you can use either double-
+quotes (``"VALUE"``) or single-quotes (``'VALUE'``) to quote it. Note that
+you can not escape these quotes.
+
+There can be a key which doesn't have value or has an empty value. Those keys
+are used for checking if the key exists or not (like a boolean).
+
+Key-Value Syntax
+----------------
+
+The boot config file syntax allows user to merge partially same word keys
+by brace. For example::
+
+ foo.bar.baz = value1
+ foo.bar.qux.quux = value2
+
+These can be written also in::
+
+ foo.bar {
+    baz = value1
+    qux.quux = value2
+ }
+
+Or more shorter, written as following::
+
+ foo.bar { baz = value1; qux.quux = value2 }
+
+In both styles, same key words are automatically merged when parsing it
+at boot time. So you can append similar trees or key-values.
+
+Same-key Values
+---------------
+
+It is prohibited that two or more values or arrays share a same-key.
+For example,::
+
+ foo = bar, baz
+ foo = qux  # !ERROR! we can not re-define same key
+
+If you want to update the value, you must use the override operator
+``:=`` explicitly. For example::
+
+ foo = bar, baz
+ foo := qux
+
+then, the ``qux`` is assigned to ``foo`` key. This is useful for
+overriding the default value by adding (partial) custom bootconfigs
+without parsing the default bootconfig.
+
+If you want to append the value to existing key as an array member,
+you can use ``+=`` operator. For example::
+
+ foo = bar, baz
+ foo += qux
+
+In this case, the key ``foo`` has ``bar``, ``baz`` and ``qux``.
+
+Moreover, sub-keys and a value can coexist under a parent key.
+For example, following config is allowed.::
+
+ foo = value1
+ foo.bar = value2
+ foo := value3 # This will update foo's value.
+
+Note, since there is no syntax to put a raw value directly under a
+structured key, you have to define it outside of the brace. For example::
+
+ foo {
+     bar = value1
+     bar {
+         baz = value2
+         qux = value3
+     }
+ }
+
+Also, the order of the value node under a key is fixed. If there
+are a value and subkeys, the value is always the first child node
+of the key. Thus if user specifies subkeys first, e.g.::
+
+ foo.bar = value1
+ foo = value2
+
+In the program (and /proc/bootconfig), it will be shown as below::
+
+ foo = value2
+ foo.bar = value1
+
+Comments
+--------
+
+The config syntax accepts shell-script style comments. The comments starting
+with hash ("#") until newline ("\n") will be ignored.
+
+::
+
+ # comment line
+ foo = value # value is set to foo.
+ bar = 1, # 1st element
+       2, # 2nd element
+       3  # 3rd element
+
+This is parsed as below::
+
+ foo = value
+ bar = 1, 2, 3
+
+Note that you can NOT put a comment or a newline between value and delimiter
+(``,`` or ``;``). This means following config has a syntax error ::
+
+ key = 1 # comment
+       ,2
+
+
+/proc/bootconfig
+================
+
+/proc/bootconfig is a user-space interface of the boot config.
+Unlike /proc/cmdline, this file shows the key-value style list.
+Each key-value pair is shown in each line with following style::
+
+ KEY[.WORDS...] = "[VALUE]"[,"VALUE2"...]
+
+
+Boot Kernel With a Boot Config
+==============================
+
+There are two options to boot the kernel with bootconfig: attaching the
+bootconfig to the initrd image or embedding it in the kernel itself.
+
+Attaching a Boot Config to Initrd
+---------------------------------
+
+Since the boot configuration file is loaded with initrd by default,
+it will be added to the end of the initrd (initramfs) image file with
+padding, size, checksum and 12-byte magic word as below.
+
+[initrd][bootconfig][padding][size(le32)][checksum(le32)][#BOOTCONFIG\n]
+
+The size and checksum fields are unsigned 32bit little endian value.
+
+When the boot configuration is added to the initrd image, the total
+file size is aligned to 4 bytes. To fill the gap, null characters
+(``\0``) will be added. Thus the ``size`` is the length of the bootconfig
+file + padding bytes.
+
+The Linux kernel decodes the last part of the initrd image in memory to
+get the boot configuration data.
+Because of this "piggyback" method, there is no need to change or
+update the boot loader and the kernel image itself as long as the boot
+loader passes the correct initrd file size. If by any chance, the boot
+loader passes a longer size, the kernel fails to find the bootconfig data.
+
+To do this operation, Linux kernel provides ``bootconfig`` command under
+tools/bootconfig, which allows admin to apply or delete the config file
+to/from initrd image. You can build it by the following command::
+
+ # make -C tools/bootconfig
+
+To add your boot config file to initrd image, run bootconfig as below
+(Old data is removed automatically if exists)::
+
+ # tools/bootconfig/bootconfig -a your-config /boot/initrd.img-X.Y.Z
+
+To remove the config from the image, you can use -d option as below::
+
+ # tools/bootconfig/bootconfig -d /boot/initrd.img-X.Y.Z
+
+Then add "bootconfig" on the normal kernel command line to tell the
+kernel to look for the bootconfig at the end of the initrd file.
+Alternatively, build your kernel with the ``CONFIG_BOOT_CONFIG_FORCE``
+Kconfig option selected.
+
+Embedding a Boot Config into Kernel
+-----------------------------------
+
+If you can not use initrd, you can also embed the bootconfig file in the
+kernel by Kconfig options. In this case, you need to recompile the kernel
+with the following configs::
+
+ CONFIG_BOOT_CONFIG_EMBED=y
+ CONFIG_BOOT_CONFIG_EMBED_FILE="/PATH/TO/BOOTCONFIG/FILE"
+
+``CONFIG_BOOT_CONFIG_EMBED_FILE`` requires an absolute path or a relative
+path to the bootconfig file from source tree or object tree.
+The kernel will embed it as the default bootconfig.
+
+Just as when attaching the bootconfig to the initrd, you need ``bootconfig``
+option on the kernel command line to enable the embedded bootconfig, or,
+alternatively, build your kernel with the ``CONFIG_BOOT_CONFIG_FORCE``
+Kconfig option selected.
+
+Note that even if you set this option, you can override the embedded
+bootconfig by another bootconfig which attached to the initrd.
+
+Rendering Embedded kernel.* Keys at Build Time
+----------------------------------------------
+
+By default, the embedded bootconfig (``CONFIG_BOOT_CONFIG_EMBED=y``) is
+parsed at runtime, after ``parse_early_param()`` has already run. Early
+parameter handlers (``mem=``, ``earlycon=``, ``loglevel=``, ...) therefore
+cannot see values supplied via the embedded ``kernel`` subtree.
+
+``CONFIG_CMDLINE_FROM_BOOTCONFIG`` resolves this by rendering the
+``kernel`` subtree of ``CONFIG_BOOT_CONFIG_EMBED_FILE`` into a flat cmdline
+string at kernel build time (via ``tools/bootconfig -C``) and prepending
+it to ``boot_command_line`` during early architecture setup, so the keys
+are visible to ``parse_early_param()``.
+
+The option requires ``CONFIG_BOOT_CONFIG_EMBED=y``, a non-empty
+``CONFIG_BOOT_CONFIG_EMBED_FILE``, ``CONFIG_CMDLINE`` to be empty, and
+an architecture that selects ``CONFIG_ARCH_SUPPORTS_CMDLINE_FROM_BOOTCONFIG``.
+Currently only x86 selects it; on other architectures the embedded
+bootconfig still works, but only through the late runtime parser.
+
+The same ``bootconfig`` opt-in applies as elsewhere: the rendered keys
+are prepended only when ``bootconfig`` (in any form) appears on the
+kernel command line, or when ``CONFIG_BOOT_CONFIG_FORCE`` is set, which
+defaults to ``y`` when ``CONFIG_BOOT_CONFIG_EMBED`` is set.
+
+For example, given::
+
+ kernel {
+   loglevel = 7
+   mem = 4G
+ }
+
+the kernel boots as if ``loglevel=7 mem=4G`` had been prepended to the
+bootloader command line, with the values visible to early-parsed
+handlers. Comma-separated values are still expanded into multiple
+cmdline entries per the bootconfig array convention -- the embedded
+``kernel.earlycon = "uart8250,io,0x3f8"`` must be quoted to land as a
+single ``earlycon=`` entry, exactly as for the runtime parser.
+
+If the rendered string would not fit in ``COMMAND_LINE_SIZE`` together
+with the existing command line, the prepend is skipped and an error is
+logged, so an oversized embedded bootconfig cannot brick a boot.
+
+Interaction with other command line and bootconfig sources
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+With ``CONFIG_CMDLINE_FROM_BOOTCONFIG=y`` the rendered ``kernel``
+subtree behaves like a build-time command line (similar to
+``CONFIG_CMDLINE``), not like a bootconfig source. It is prepended to
+``boot_command_line`` in ``setup_arch()``, before ``parse_early_param()``
+and long before the runtime parser looks at an initrd. Options can reach
+the kernel from up to four places:
+
+- Bootloader command line: the arguments the boot loader passes. The
+  embedded cmdline is prepended in front of them, so for last-one-wins
+  parameters a bootloader option still overrides the embedded value.
+  Visible in /proc/cmdline.
+- Embedded cmdline (this option): the rendered ``kernel`` subtree,
+  prepended early so it is seen by ``parse_early_param()``. Visible in
+  /proc/cmdline.
+- Initrd bootconfig: parsed late in ``setup_boot_config()``; its
+  ``kernel`` keys are placed ahead of ``boot_command_line``, i.e. before
+  the embedded cmdline, so last-wins favors the embedded values. As a
+  bootconfig source, an initrd bootconfig still replaces the embedded
+  bootconfig. Visible in /proc/cmdline and /proc/bootconfig.
+- Embedded bootconfig (runtime): parsed late, only when no initrd
+  bootconfig is present. Visible in /proc/cmdline and /proc/bootconfig.
+
+So with this option the embedded ``kernel.*`` values take precedence
+over an initrd bootconfig's ``kernel.*`` values: for early parameters
+the initrd is not parsed yet, and for ordinary parameters the embedded
+keys land later in the command line. If you need an initrd bootconfig to
+override the embedded ``kernel.*`` keys, leave this option off and rely
+on the runtime parser.
+
+The rendered string is part of the command line, so it appears in
+/proc/cmdline. It is deliberately not shown in /proc/bootconfig: that
+file keeps reporting the parsed bootconfig tree -- the initrd bootconfig
+if present, otherwise the embedded bootconfig -- independent of whether
+build-time cmdline rendering is enabled.
+
+Kernel parameters via Boot Config
+=================================
+
+In addition to the kernel command line, the boot config can be used for
+passing the kernel parameters. All the key-value pairs under ``kernel``
+key will be passed to kernel cmdline directly. Moreover, the key-value
+pairs under ``init`` will be passed to init process via the cmdline.
+The parameters are concatenated with user-given kernel cmdline string
+as the following order, so that the command line parameter can override
+bootconfig parameters (this depends on how the subsystem handles parameters
+but in general, earlier parameter will be overwritten by later one.)::
+
+ [bootconfig params][cmdline params] -- [bootconfig init params][cmdline init params]
+
+Here is an example of the bootconfig file for kernel/init parameters.::
+
+ kernel {
+   root = 01234567-89ab-cdef-0123-456789abcd
+ }
+ init {
+  splash
+ }
+
+This will be copied into the kernel cmdline string as the following::
+
+ root="01234567-89ab-cdef-0123-456789abcd" -- splash
+
+If user gives some other command line like,::
+
+ ro bootconfig -- quiet
+
+The final kernel cmdline will be the following::
+
+ root="01234567-89ab-cdef-0123-456789abcd" ro bootconfig -- splash quiet
+
+
+Config File Limitation
+======================
+
+Currently the maximum config size is 32KB and the total key-words (not
+key-value entries) must be under 1024 nodes.
+Note: this is not the number of entries but nodes, an entry must consume
+more than 2 nodes (a key-word and a value). So theoretically, it will be
+up to 512 key-value pairs. If keys contains 3 words in average, it can
+contain 256 key-value pairs. In most cases, the number of config items
+will be under 100 entries and smaller than 8KB, so it would be enough.
+If the node number exceeds 1024, parser returns an error even if the file
+size is smaller than 32KB. (Note that this maximum size is not including
+the padding null characters.)
+Anyway, since bootconfig command verifies it when appending a boot config
+to initrd image, user can notice it before boot.
+
+
+Bootconfig APIs
+===============
+
+User can query or loop on key-value pairs, also it is possible to find
+a root (prefix) key node and find key-values under that node.
+
+If you have a key string, you can query the value directly with the key
+using xbc_find_value(). If you want to know what keys exist in the boot
+config, you can use xbc_for_each_key_value() to iterate key-value pairs.
+Note that you need to use xbc_array_for_each_value() for accessing
+each array's value, e.g.::
+
+ vnode = NULL;
+ xbc_find_value("key.word", &vnode);
+ if (vnode && xbc_node_is_array(vnode))
+    xbc_array_for_each_value(vnode, value) {
+      printk("%s ", value);
+    }
+
+If you want to focus on keys which have a prefix string, you can use
+xbc_find_node() to find a node by the prefix string, and iterate
+keys under the prefix node with xbc_node_for_each_key_value().
+
+But the most typical usage is to get the named value under prefix
+or get the named array under prefix as below::
+
+ root = xbc_find_node("key.prefix");
+ value = xbc_node_find_value(root, "option", &vnode);
+ ...
+ xbc_node_for_each_array_value(root, "array-option", value, anode) {
+    ...
+ }
+
+This accesses a value of "key.prefix.option" and an array of
+"key.prefix.array-option".
+
+Locking is not needed, since after initialization, the config becomes
+read-only. All data and keys must be copied if you need to modify it.
+
+
+Functions and structures
+========================
+
+.. kernel-doc:: include/linux/bootconfig.h
+.. kernel-doc:: lib/bootconfig.c
+
diff --git a/Documentation/admin-guide/braille-console.rst b/Documentation/admin-guide/braille-console.rst
new file mode 100644
index 000000000..153472e93
--- /dev/null
+++ b/Documentation/admin-guide/braille-console.rst
@@ -0,0 +1,38 @@
+Linux Braille Console
+=====================
+
+To get early boot messages on a braille device (before userspace screen
+readers can start), you first need to compile the support for the usual serial
+console (see :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`), and
+for braille device
+(in :menuselection:`Device Drivers --> Accessibility support --> Console on braille device`).
+
+Then you need to specify a ``console=brl``, option on the kernel command line, the
+format is::
+
+	console=brl,serial_options...
+
+where ``serial_options...`` are the same as described in
+:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
+
+So for instance you can use ``console=brl,ttyS0`` if the braille device is connected to the first serial port, and ``console=brl,ttyS0,115200`` to
+override the baud rate to 115200, etc.
+
+By default, the braille device will just show the last kernel message (console
+mode).  To review previous messages, press the Insert key to switch to the VT
+review mode.  In review mode, the arrow keys permit to browse in the VT content,
+`PAGE-UP`/`PAGE-DOWN` keys go at the top/bottom of the screen, and
+the `HOME` key goes back
+to the cursor, hence providing very basic screen reviewing facility.
+
+Sound feedback can be obtained by adding the ``braille_console.sound=1`` kernel
+parameter.
+
+For simplicity, only one braille console can be enabled, other uses of
+``console=brl,...`` will be discarded.  Also note that it does not interfere with
+the console selection mechanism described in
+:ref:`Documentation/admin-guide/serial-console.rst <serial_console>`.
+
+For now, only the VisioBraille device is supported.
+
+Samuel Thibault <samuel.thibault@ens-lyon.org>
diff --git a/Documentation/admin-guide/btmrvl.rst b/Documentation/admin-guide/btmrvl.rst
new file mode 100644
index 000000000..ec57740ea
--- /dev/null
+++ b/Documentation/admin-guide/btmrvl.rst
@@ -0,0 +1,124 @@
+=============
+btmrvl driver
+=============
+
+All commands are used via debugfs interface.
+
+Set/get driver configurations
+=============================
+
+Path:	/debug/btmrvl/config/
+
+gpiogap=[n], hscfgcmd
+	These commands are used to configure the host sleep parameters::
+	bit 8:0  -- Gap
+	bit 16:8 -- GPIO
+
+	where GPIO is the pin number of GPIO used to wake up the host.
+	It could be any valid GPIO pin# (e.g. 0-7) or 0xff (SDIO interface
+	wakeup will be used instead).
+
+	where Gap is the gap in milli seconds between wakeup signal and
+	wakeup event, or 0xff for special host sleep setting.
+
+	Usage::
+
+		# Use SDIO interface to wake up the host and set GAP to 0x80:
+		echo 0xff80 > /debug/btmrvl/config/gpiogap
+		echo 1 > /debug/btmrvl/config/hscfgcmd
+
+		# Use GPIO pin #3 to wake up the host and set GAP to 0xff:
+		echo 0x03ff >  /debug/btmrvl/config/gpiogap
+		echo 1 > /debug/btmrvl/config/hscfgcmd
+
+psmode=[n], pscmd
+	These commands are used to enable/disable auto sleep mode
+
+	where the option is::
+
+			1 	-- Enable auto sleep mode
+			0 	-- Disable auto sleep mode
+
+	Usage::
+
+		# Enable auto sleep mode
+		echo 1 > /debug/btmrvl/config/psmode
+		echo 1 > /debug/btmrvl/config/pscmd
+
+		# Disable auto sleep mode
+		echo 0 > /debug/btmrvl/config/psmode
+		echo 1 > /debug/btmrvl/config/pscmd
+
+
+hsmode=[n], hscmd
+	These commands are used to enable host sleep or wake up firmware
+
+	where the option is::
+
+			1	-- Enable host sleep
+			0	-- Wake up firmware
+
+	Usage::
+
+		# Enable host sleep
+		echo 1 > /debug/btmrvl/config/hsmode
+		echo 1 > /debug/btmrvl/config/hscmd
+
+		# Wake up firmware
+		echo 0 > /debug/btmrvl/config/hsmode
+		echo 1 > /debug/btmrvl/config/hscmd
+
+
+Get driver status
+=================
+
+Path:	/debug/btmrvl/status/
+
+Usage::
+
+	cat /debug/btmrvl/status/<args>
+
+where the args are:
+
+curpsmode
+	This command displays current auto sleep status.
+
+psstate
+	This command display the power save state.
+
+hsstate
+	This command display the host sleep state.
+
+txdnldrdy
+	This command displays the value of Tx download ready flag.
+
+Issuing a raw hci command
+=========================
+
+Use hcitool to issue raw hci command, refer to hcitool manual
+
+Usage::
+
+	Hcitool cmd <ogf> <ocf> [Parameters]
+
+Interface Control Command::
+
+	hcitool cmd 0x3f 0x5b 0xf5 0x01 0x00    --Enable All interface
+	hcitool cmd 0x3f 0x5b 0xf5 0x01 0x01    --Enable Wlan interface
+	hcitool cmd 0x3f 0x5b 0xf5 0x01 0x02    --Enable BT interface
+	hcitool cmd 0x3f 0x5b 0xf5 0x00 0x00    --Disable All interface
+	hcitool cmd 0x3f 0x5b 0xf5 0x00 0x01    --Disable Wlan interface
+	hcitool cmd 0x3f 0x5b 0xf5 0x00 0x02    --Disable BT interface
+
+SD8688 firmware
+===============
+
+Images:
+
+- /lib/firmware/sd8688_helper.bin
+- /lib/firmware/sd8688.bin
+
+
+The images can be downloaded from:
+
+git.infradead.org/users/dwmw2/linux-firmware.git/libertas/
diff --git a/Documentation/admin-guide/bug-bisect.rst b/Documentation/admin-guide/bug-bisect.rst
new file mode 100644
index 000000000..f4f867cab
--- /dev/null
+++ b/Documentation/admin-guide/bug-bisect.rst
@@ -0,0 +1,165 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+.. [see the bottom of this file for redistribution information]
+
+======================
+Bisecting a regression
+======================
+
+This document describes how to use a ``git bisect`` to find the source code
+change that broke something -- for example when some functionality stopped
+working after upgrading from Linux 6.0 to 6.1.
+
+The text focuses on the gist of the process. If you are new to bisecting the
+kernel, better follow Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst
+instead: it depicts everything from start to finish while covering multiple
+aspects even kernel developers occasionally forget. This includes detecting
+situations early where a bisection would be a waste of time, as nobody would
+care about the result -- for example, because the problem happens after the
+kernel marked itself as 'tainted', occurs in an abandoned version, was already
+fixed, or is caused by a .config change you or your Linux distributor performed.
+
+Finding the change causing a kernel issue using a bisection
+===========================================================
+
+*Note: the following process assumes you prepared everything for a bisection.
+This includes having a Git clone with the appropriate sources, installing the
+software required to build and install kernels, as well as a .config file stored
+in a safe place (the following example assumes '~/prepared_kernel_.config') to
+use as pristine base at each bisection step; ideally, you have also worked out
+a fully reliable and straight-forward way to reproduce the regression, too.*
+
+* Preparation: start the bisection and tell Git about the points in the history
+  you consider to be working and broken, which Git calls 'good' and 'bad'::
+
+     git bisect start
+     git bisect good v6.0
+     git bisect bad v6.1
+
+  Instead of Git tags like 'v6.0' and 'v6.1' you can specify commit-ids, too.
+
+1. Copy your prepared .config into the build directory and adjust it to the
+   needs of the codebase Git checked out for testing::
+
+     cp ~/prepared_kernel_.config .config
+     make olddefconfig
+
+2. Now build, install, and boot a kernel. This might fail for unrelated reasons,
+   for example, when a compile error happens at the current stage of the
+   bisection a later change resolves. In such cases run ``git bisect skip`` and
+   go back to step 1.
+
+3. Check if the functionality that regressed works in the kernel you just built.
+
+   If it works, execute::
+
+     git bisect good
+
+   If it is broken, run::
+
+     git bisect bad
+
+   Note, getting this wrong just once will send the rest of the bisection
+   totally off course. To prevent having to start anew later you thus want to
+   ensure what you tell Git is correct; it is thus often wise to spend a few
+   minutes more on testing in case your reproducer is unreliable.
+
+   After issuing one of these two commands, Git will usually check out another
+   bisection point and print something like 'Bisecting: 675 revisions left to
+   test after this (roughly 10 steps)'. In that case go back to step 1.
+
+   If Git instead prints something like 'cafecaca0c0dacafecaca0c0dacafecaca0c0da
+   is the first bad commit', then you have finished the bisection. In that case
+   move to the next point below. Note, right after displaying that line Git will
+   show some details about the culprit including its patch description; this can
+   easily fill your terminal, so you might need to scroll up to see the message
+   mentioning the culprit's commit-id.
+
+   In case you missed Git's output, you can always run ``git bisect log`` to
+   print the status: it will show how many steps remain or mention the result of
+   the bisection.
+
+* Recommended complementary task: put the bisection log and the current .config
+  file aside for the bug report; furthermore tell Git to reset the sources to
+  the state before the bisection::
+
+     git bisect log > ~/bisection-log
+     cp .config ~/bisection-config-culprit
+     git bisect reset
+
+* Recommended optional task: try reverting the culprit on top of the latest
+  codebase and check if that fixes your bug; if that is the case, it validates
+  the bisection and enables developers to resolve the regression through a
+  revert.
+
+  To try this, update your clone and check out latest mainline. Then tell Git
+  to revert the change by specifying its commit-id::
+
+     git revert --no-edit cafec0cacaca0
+
+  Git might reject this, for example when the bisection landed on a merge
+  commit. In that case, abandon the attempt. Do the same, if Git fails to revert
+  the culprit on its own because later changes depend on it -- at least unless
+  you bisected a stable or longterm kernel series, in which case you want to
+  check out its latest codebase and try a revert there.
+
+  If a revert succeeds, build and test another kernel to check if reverting
+  resolved your regression.
+
+With that the process is complete. Now report the regression as described by
+Documentation/admin-guide/reporting-issues.rst.
+
+Bisecting linux-next
+--------------------
+
+If you face a problem only happening in linux-next, bisect between the
+linux-next branches 'stable' and 'master'. The following commands will start
+the process for a linux-next tree you added as a remote called 'next'::
+
+  git bisect start
+  git bisect good next/stable
+  git bisect bad next/master
+
+The 'stable' branch refers to the state of linux-mainline that the current
+linux-next release (found in the 'master' branch) is based on -- the former
+thus should be free of any problems that show up in -next, but not in Linus'
+tree.
+
+This will bisect across a wide range of changes, some of which you might have
+used in earlier linux-next releases without problems. Sadly there is no simple
+way to avoid checking them: bisecting from one linux-next release to a later
+one (say between 'next-20241020' and 'next-20241021') is impossible, as they
+share no common history.
+
+Additional reading material
+---------------------------
+
+* The `man page for 'git bisect' <https://git-scm.com/docs/git-bisect>`_ and
+  `fighting regressions with 'git bisect' <https://git-scm.com/docs/git-bisect-lk2009.html>`_
+  in the Git documentation.
+* `Working with git bisect <https://nathanchance.dev/posts/working-with-git-bisect/>`_
+  from kernel developer Nathan Chancellor.
+* `Using Git bisect to figure out when brokenness was introduced <http://webchick.net/node/99>`_.
+* `Fully automated bisecting with 'git bisect run' <https://lwn.net/Articles/317154>`_.
+
+..
+   end-of-content
+..
+   This document is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If
+   you spot a typo or small mistake, feel free to let him know directly and
+   he'll fix it. You are free to do the same in a mostly informal way if you
+   want to contribute changes to the text -- but for copyright reasons please CC
+   linux-doc@vger.kernel.org and 'sign-off' your contribution as
+   Documentation/process/submitting-patches.rst explains in the section 'Sign
+   your work - the Developer's Certificate of Origin'.
+..
+   This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top
+   of the file. If you want to distribute this text under CC-BY-4.0 only,
+   please use 'The Linux kernel development community' for author attribution
+   and link this as source:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/bug-bisect.rst
+
+..
+   Note: Only the content of this RST file as found in the Linux kernel sources
+   is available under CC-BY-4.0, as versions of this text that were processed
+   (for example by the kernel's build system) might contain content taken from
+   files which use a more restrictive license.
diff --git a/Documentation/admin-guide/bug-hunting.rst b/Documentation/admin-guide/bug-hunting.rst
new file mode 100644
index 000000000..642bf8474
--- /dev/null
+++ b/Documentation/admin-guide/bug-hunting.rst
@@ -0,0 +1,370 @@
+Bug hunting
+===========
+
+Kernel bug reports often come with a stack dump like the one below::
+
+	------------[ cut here ]------------
+	WARNING: CPU: 1 PID: 28102 at kernel/module.c:1108 module_put+0x57/0x70
+	Modules linked in: dvb_usb_gp8psk(-) dvb_usb dvb_core nvidia_drm(PO) nvidia_modeset(PO) snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd soundcore nvidia(PO) [last unloaded: rc_core]
+	CPU: 1 PID: 28102 Comm: rmmod Tainted: P        WC O 4.8.4-build.1 #1
+	Hardware name: MSI MS-7309/MS-7309, BIOS V1.12 02/23/2009
+	 00000000 c12ba080 00000000 00000000 c103ed6a c1616014 00000001 00006dc6
+	 c1615862 00000454 c109e8a7 c109e8a7 00000009 ffffffff 00000000 f13f6a10
+	 f5f5a600 c103ee33 00000009 00000000 00000000 c109e8a7 f80ca4d0 c109f617
+	Call Trace:
+	 [<c12ba080>] ? dump_stack+0x44/0x64
+	 [<c103ed6a>] ? __warn+0xfa/0x120
+	 [<c109e8a7>] ? module_put+0x57/0x70
+	 [<c109e8a7>] ? module_put+0x57/0x70
+	 [<c103ee33>] ? warn_slowpath_null+0x23/0x30
+	 [<c109e8a7>] ? module_put+0x57/0x70
+	 [<f80ca4d0>] ? gp8psk_fe_set_frontend+0x460/0x460 [dvb_usb_gp8psk]
+	 [<c109f617>] ? symbol_put_addr+0x27/0x50
+	 [<f80bc9ca>] ? dvb_usb_adapter_frontend_exit+0x3a/0x70 [dvb_usb]
+	 [<f80bb3bf>] ? dvb_usb_exit+0x2f/0xd0 [dvb_usb]
+	 [<c13d03bc>] ? usb_disable_endpoint+0x7c/0xb0
+	 [<f80bb48a>] ? dvb_usb_device_exit+0x2a/0x50 [dvb_usb]
+	 [<c13d2882>] ? usb_unbind_interface+0x62/0x250
+	 [<c136b514>] ? __pm_runtime_idle+0x44/0x70
+	 [<c13620d8>] ? __device_release_driver+0x78/0x120
+	 [<c1362907>] ? driver_detach+0x87/0x90
+	 [<c1361c48>] ? bus_remove_driver+0x38/0x90
+	 [<c13d1c18>] ? usb_deregister+0x58/0xb0
+	 [<c109fbb0>] ? SyS_delete_module+0x130/0x1f0
+	 [<c1055654>] ? task_work_run+0x64/0x80
+	 [<c1000fa5>] ? exit_to_usermode_loop+0x85/0x90
+	 [<c10013f0>] ? do_fast_syscall_32+0x80/0x130
+	 [<c1549f43>] ? sysenter_past_esp+0x40/0x6a
+	---[ end trace 6ebc60ef3981792f ]---
+
+Such stack traces provide enough information to identify the line inside the
+Kernel's source code where the bug happened. Depending on the severity of
+the issue, it may also contain the word **Oops**, as on this one::
+
+	BUG: unable to handle kernel NULL pointer dereference at   (null)
+	IP: [<c06969d4>] iret_exc+0x7d0/0xa59
+	*pdpt = 000000002258a001 *pde = 0000000000000000
+	Oops: 0002 [#1] PREEMPT SMP
+	...
+
+Despite being an **Oops** or some other sort of stack trace, the offended
+line is usually required to identify and handle the bug. Along this chapter,
+we'll refer to "Oops" for all kinds of stack traces that need to be analyzed.
+
+If the kernel is compiled with ``CONFIG_DEBUG_INFO``, you can enhance the
+quality of the stack trace by using ``scripts/decode_stacktrace.sh``.
+
+Modules linked in
+-----------------
+
+Modules that are tainted or are being loaded or unloaded are marked with
+"(...)", where the taint flags are described in
+Documentation/admin-guide/tainted-kernels.rst, "being loaded" is
+annotated with "+", and "being unloaded" is annotated with "-".
+
+
+Where is the Oops message located?
+----------------------------------
+
+Normally the Oops text is read from the kernel buffers by klogd and
+handed to ``syslogd`` which writes it to a syslog file, typically
+``/var/log/messages`` (depends on ``/etc/syslog.conf``). On systems with
+systemd, it may also be stored by the ``journald`` daemon, and accessed
+by running ``journalctl`` command.
+
+Sometimes ``klogd`` dies, in which case you can run ``dmesg > file`` to
+read the data from the kernel buffers and save it.  Or you can
+``cat /proc/kmsg > file``, however you have to break in to stop the transfer,
+since ``kmsg`` is a "never ending file".
+
+If the machine has crashed so badly that you cannot enter commands or
+the disk is not available then you have three options:
+
+(1) Hand copy the text from the screen and type it in after the machine
+    has restarted.  Messy but it is the only option if you have not
+    planned for a crash. Alternatively, you can take a picture of
+    the screen with a digital camera - not nice, but better than
+    nothing.  If the messages scroll off the top of the console, you
+    may find that booting with a higher resolution (e.g., ``vga=791``)
+    will allow you to read more of the text. (Caveat: This needs ``vesafb``,
+    so won't help for 'early' oopses.)
+
+(2) Boot with a serial console (see
+    :ref:`Documentation/admin-guide/serial-console.rst <serial_console>`),
+    run a null modem to a second machine and capture the output there
+    using your favourite communication program.  Minicom works well.
+
+(3) Use Kdump (see Documentation/admin-guide/kdump/kdump.rst),
+    extract the kernel ring buffer from old memory with using dmesg
+    gdbmacro in Documentation/admin-guide/kdump/gdbmacros.txt.
+
+Finding the bug's location
+--------------------------
+
+Reporting a bug works best if you point the location of the bug at the
+Kernel source file. There are two methods for doing that. Usually, using
+``gdb`` is easier, but the Kernel should be pre-compiled with debug info.
+
+gdb
+^^^
+
+The GNU debugger (``gdb``) is the best way to figure out the exact file and line
+number of the OOPS from the ``vmlinux`` file.
+
+The usage of gdb works best on a kernel compiled with ``CONFIG_DEBUG_INFO``.
+This can be set by running::
+
+  $ ./scripts/config -d COMPILE_TEST -e DEBUG_KERNEL -e DEBUG_INFO
+
+On a kernel compiled with ``CONFIG_DEBUG_INFO``, you can simply copy the
+EIP value from the OOPS::
+
+ EIP:    0060:[<c021e50e>]    Not tainted VLI
+
+And use GDB to translate that to human-readable form::
+
+  $ gdb vmlinux
+  (gdb) l *0xc021e50e
+
+If you don't have ``CONFIG_DEBUG_INFO`` enabled, you use the function
+offset from the OOPS::
+
+ EIP is at vt_ioctl+0xda8/0x1482
+
+And recompile the kernel with ``CONFIG_DEBUG_INFO`` enabled::
+
+  $ ./scripts/config -d COMPILE_TEST -e DEBUG_KERNEL -e DEBUG_INFO
+  $ make vmlinux
+  $ gdb vmlinux
+  (gdb) l *vt_ioctl+0xda8
+  0x1888 is in vt_ioctl (drivers/tty/vt/vt_ioctl.c:293).
+  288	{
+  289		struct vc_data *vc = NULL;
+  290		int ret = 0;
+  291
+  292		console_lock();
+  293		if (VT_BUSY(vc_num))
+  294			ret = -EBUSY;
+  295		else if (vc_num)
+  296			vc = vc_deallocate(vc_num);
+  297		console_unlock();
+
+or, if you want to be more verbose::
+
+  (gdb) p vt_ioctl
+  $1 = {int (struct tty_struct *, unsigned int, unsigned long)} 0xae0 <vt_ioctl>
+  (gdb) l *0xae0+0xda8
+
+You could, instead, use the object file::
+
+  $ make drivers/tty/
+  $ gdb drivers/tty/vt/vt_ioctl.o
+  (gdb) l *vt_ioctl+0xda8
+
+If you have a call trace, such as::
+
+     Call Trace:
+      [<ffffffff8802c8e9>] :jbd:log_wait_commit+0xa3/0xf5
+      [<ffffffff810482d9>] autoremove_wake_function+0x0/0x2e
+      [<ffffffff8802770b>] :jbd:journal_stop+0x1be/0x1ee
+      ...
+
+this shows the problem likely is in the :jbd: module. You can load that module
+in gdb and list the relevant code::
+
+  $ gdb fs/jbd/jbd.ko
+  (gdb) l *log_wait_commit+0xa3
+
+.. note::
+
+     You can also do the same for any function call at the stack trace,
+     like this one::
+
+	 [<f80bc9ca>] ? dvb_usb_adapter_frontend_exit+0x3a/0x70 [dvb_usb]
+
+     The position where the above call happened can be seen with::
+
+	$ gdb drivers/media/usb/dvb-usb/dvb-usb.o
+	(gdb) l *dvb_usb_adapter_frontend_exit+0x3a
+
+objdump
+^^^^^^^
+
+To debug a kernel, use objdump and look for the hex offset from the crash
+output to find the valid line of code/assembler. Without debug symbols, you
+will see the assembler code for the routine shown, but if your kernel has
+debug symbols the C code will also be available. (Debug symbols can be enabled
+in the kernel hacking menu of the menu configuration.) For example::
+
+    $ objdump -r -S -l --disassemble net/ipv4/tcp.o
+
+.. note::
+
+   You need to be at the top level of the kernel tree for this to pick up
+   your C files.
+
+If you don't have access to the source code you can still debug some crash
+dumps using the following method (example crash dump output as shown by
+Dave Miller)::
+
+     EIP is at 	+0x14/0x4c0
+      ...
+     Code: 44 24 04 e8 6f 05 00 00 e9 e8 fe ff ff 8d 76 00 8d bc 27 00 00
+     00 00 55 57  56 53 81 ec bc 00 00 00 8b ac 24 d0 00 00 00 8b 5d 08
+     <8b> 83 3c 01 00 00 89 44  24 14 8b 45 28 85 c0 89 44 24 18 0f 85
+
+     Put the bytes into a "foo.s" file like this:
+
+            .text
+            .globl foo
+     foo:
+            .byte  .... /* bytes from Code: part of OOPS dump */
+
+     Compile it with "gcc -c -o foo.o foo.s" then look at the output of
+     "objdump --disassemble foo.o".
+
+     Output:
+
+     ip_queue_xmit:
+         push       %ebp
+         push       %edi
+         push       %esi
+         push       %ebx
+         sub        $0xbc, %esp
+         mov        0xd0(%esp), %ebp        ! %ebp = arg0 (skb)
+         mov        0x8(%ebp), %ebx         ! %ebx = skb->sk
+         mov        0x13c(%ebx), %eax       ! %eax = inet_sk(sk)->opt
+
+``scripts/decodecode`` can be used to automate most of this, depending
+on what CPU architecture is being debugged.
+
+Reporting the bug
+-----------------
+
+Once you find where the bug happened, by inspecting its location,
+you could either try to fix it yourself or report it upstream.
+
+In order to report it upstream, you should identify the bug tracker, if any, or
+mailing list used for the development of the affected code. This can be done by
+using the ``get_maintainer.pl`` script.
+
+For example, if you find a bug at the gspca's sonixj.c file, you can get
+its maintainers with::
+
+	$ ./scripts/get_maintainer.pl --bug -f drivers/media/usb/gspca/sonixj.c
+	Hans Verkuil <hverkuil@kernel.org> (odd fixer:GSPCA USB WEBCAM DRIVER,commit_signer:1/1=100%)
+	Mauro Carvalho Chehab <mchehab@kernel.org> (maintainer:MEDIA INPUT INFRASTRUCTURE (V4L/DVB),commit_signer:1/1=100%)
+	Tejun Heo <tj@kernel.org> (commit_signer:1/1=100%)
+	Bhaktipriya Shridhar <bhaktipriya96@gmail.com> (commit_signer:1/1=100%,authored:1/1=100%,added_lines:4/4=100%,removed_lines:9/9=100%)
+	linux-media@vger.kernel.org (open list:GSPCA USB WEBCAM DRIVER)
+	linux-kernel@vger.kernel.org (open list)
+
+Please notice that it will point to:
+
+- The last developers that touched the source code (if this is done inside
+  a git tree). On the above example, Tejun and Bhaktipriya (in this
+  specific case, none really involved on the development of this file);
+- The driver maintainer (Hans Verkuil);
+- The subsystem maintainer (Mauro Carvalho Chehab);
+- The driver and/or subsystem mailing list (linux-media@vger.kernel.org);
+- The Linux Kernel mailing list (linux-kernel@vger.kernel.org);
+- The bug reporting URIs for the driver/subsystem (none in the above example).
+
+If the listing contains bug reporting URIs at the end, please prefer them over
+email. Otherwise, please report bugs to the mailing list used for the
+development of the code (linux-media ML) copying the driver maintainer (Hans).
+
+If you are totally stumped as to whom to send the report, and
+``get_maintainer.pl`` didn't provide you anything useful, send it to
+linux-kernel@vger.kernel.org.
+
+Thanks for your help in making Linux as stable as humanly possible.
+
+Fixing the bug
+--------------
+
+If you know programming, you could help us by not only reporting the bug,
+but also providing us with a solution. After all, open source is about
+sharing what you do and don't you want to be recognised for your genius?
+
+If you decide to take this way, once you have worked out a fix please submit
+it upstream.
+
+Please do read
+:ref:`Documentation/process/submitting-patches.rst <submittingpatches>` though
+to help your code get accepted.
+
+
+---------------------------------------------------------------------------
+
+Notes on Oops tracing with ``klogd``
+------------------------------------
+
+In order to help Linus and the other kernel developers there has been
+substantial support incorporated into ``klogd`` for processing protection
+faults.  In order to have full support for address resolution at least
+version 1.3-pl3 of the ``sysklogd`` package should be used.
+
+When a protection fault occurs the ``klogd`` daemon automatically
+translates important addresses in the kernel log messages to their
+symbolic equivalents.  This translated kernel message is then
+forwarded through whatever reporting mechanism ``klogd`` is using.  The
+protection fault message can be simply cut out of the message files
+and forwarded to the kernel developers.
+
+Two types of address resolution are performed by ``klogd``.  The first is
+static translation and the second is dynamic translation.
+Static translation uses the System.map file.
+In order to do static translation the ``klogd`` daemon
+must be able to find a system map file at daemon initialization time.
+See the klogd man page for information on how ``klogd`` searches for map
+files.
+
+Dynamic address translation is important when kernel loadable modules
+are being used.  Since memory for kernel modules is allocated from the
+kernel's dynamic memory pools there are no fixed locations for either
+the start of the module or for functions and symbols in the module.
+
+The kernel supports system calls which allow a program to determine
+which modules are loaded and their location in memory.  Using these
+system calls the klogd daemon builds a symbol table which can be used
+to debug a protection fault which occurs in a loadable kernel module.
+
+At the very minimum klogd will provide the name of the module which
+generated the protection fault.  There may be additional symbolic
+information available if the developer of the loadable module chose to
+export symbol information from the module.
+
+Since the kernel module environment can be dynamic there must be a
+mechanism for notifying the ``klogd`` daemon when a change in module
+environment occurs.  There are command line options available which
+allow klogd to signal the currently executing daemon that symbol
+information should be refreshed.  See the ``klogd`` manual page for more
+information.
+
+A patch is included with the sysklogd distribution which modifies the
+``modules-2.0.0`` package to automatically signal klogd whenever a module
+is loaded or unloaded.  Applying this patch provides essentially
+seamless support for debugging protection faults which occur with
+kernel loadable modules.
+
+The following is an example of a protection fault in a loadable module
+processed by ``klogd``::
+
+	Aug 29 09:51:01 blizard kernel: Unable to handle kernel paging request at virtual address f15e97cc
+	Aug 29 09:51:01 blizard kernel: current->tss.cr3 = 0062d000, %cr3 = 0062d000
+	Aug 29 09:51:01 blizard kernel: *pde = 00000000
+	Aug 29 09:51:01 blizard kernel: Oops: 0002
+	Aug 29 09:51:01 blizard kernel: CPU:    0
+	Aug 29 09:51:01 blizard kernel: EIP:    0010:[oops:_oops+16/3868]
+	Aug 29 09:51:01 blizard kernel: EFLAGS: 00010212
+	Aug 29 09:51:01 blizard kernel: eax: 315e97cc   ebx: 003a6f80   ecx: 001be77b   edx: 00237c0c
+	Aug 29 09:51:01 blizard kernel: esi: 00000000   edi: bffffdb3   ebp: 00589f90   esp: 00589f8c
+	Aug 29 09:51:01 blizard kernel: ds: 0018   es: 0018   fs: 002b   gs: 002b   ss: 0018
+	Aug 29 09:51:01 blizard kernel: Process oops_test (pid: 3374, process nr: 21, stackpage=00589000)
+	Aug 29 09:51:01 blizard kernel: Stack: 315e97cc 00589f98 0100b0b4 bffffed4 0012e38e 00240c64 003a6f80 00000001
+	Aug 29 09:51:01 blizard kernel:        00000000 00237810 bfffff00 0010a7fa 00000003 00000001 00000000 bfffff00
+	Aug 29 09:51:01 blizard kernel:        bffffdb3 bffffed4 ffffffda 0000002b 0007002b 0000002b 0000002b 00000036
+	Aug 29 09:51:01 blizard kernel: Call Trace: [oops:_oops_ioctl+48/80] [_sys_ioctl+254/272] [_system_call+82/128]
+	Aug 29 09:51:01 blizard kernel: Code: c7 00 05 00 00 00 eb 08 90 90 90 90 90 90 90 90 89 ec 5d c3
+
diff --git a/Documentation/admin-guide/cgroup-v1/blkio-controller.rst b/Documentation/admin-guide/cgroup-v1/blkio-controller.rst
new file mode 100644
index 000000000..dabb80cdd
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/blkio-controller.rst
@@ -0,0 +1,301 @@
+===================
+Block IO Controller
+===================
+
+Overview
+========
+cgroup subsys "blkio" implements the block io controller. There seems to be
+a need of various kinds of IO control policies (like proportional BW, max BW)
+both at leaf nodes as well as at intermediate nodes in a storage hierarchy.
+Plan is to use the same cgroup based management interface for blkio controller
+and based on user options switch IO policies in the background.
+
+One IO control policy is throttling policy which can be used to
+specify upper IO rate limits on devices. This policy is implemented in
+generic block layer and can be used on leaf nodes as well as higher
+level logical devices like device mapper.
+
+HOWTO
+=====
+
+Throttling/Upper Limit policy
+-----------------------------
+Enable Block IO controller::
+
+	CONFIG_BLK_CGROUP=y
+
+Enable throttling in block layer::
+
+	CONFIG_BLK_DEV_THROTTLING=y
+
+Mount blkio controller (see cgroups.txt, Why are cgroups needed?)::
+
+        mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
+
+Specify a bandwidth rate on particular device for root group. The format
+for policy is "<major>:<minor>  <bytes_per_second>"::
+
+        echo "8:16  1048576" > /sys/fs/cgroup/blkio/blkio.throttle.read_bps_device
+
+This will put a limit of 1MB/second on reads happening for root group
+on device having major/minor number 8:16.
+
+Run dd to read a file and see if rate is throttled to 1MB/s or not::
+
+        # dd iflag=direct if=/mnt/common/zerofile of=/dev/null bs=4K count=1024
+        1024+0 records in
+        1024+0 records out
+        4194304 bytes (4.2 MB) copied, 4.0001 s, 1.0 MB/s
+
+Limits for writes can be put using blkio.throttle.write_bps_device file.
+
+Hierarchical Cgroups
+====================
+
+Throttling implements hierarchy support; however,
+throttling's hierarchy support is enabled iff "sane_behavior" is
+enabled from cgroup side, which currently is a development option and
+not publicly available.
+
+If somebody created a hierarchy like as follows::
+
+			root
+			/  \
+		     test1 test2
+			|
+		     test3
+
+Throttling with "sane_behavior" will handle the
+hierarchy correctly. For throttling, all limits apply
+to the whole subtree while all statistics are local to the IOs
+directly generated by tasks in that cgroup.
+
+Throttling without "sane_behavior" enabled from cgroup side will
+practically treat all groups at same level as if it looks like the
+following::
+
+				pivot
+			     /  /   \  \
+			root  test1 test2  test3
+
+Various user visible config options
+===================================
+
+  CONFIG_BLK_CGROUP
+	  Block IO controller.
+
+  CONFIG_BFQ_CGROUP_DEBUG
+	  Debug help. Right now some additional stats file show up in cgroup
+	  if this option is enabled.
+
+  CONFIG_BLK_DEV_THROTTLING
+	  Enable block device throttling support in block layer.
+
+Details of cgroup files
+=======================
+
+Proportional weight policy files
+--------------------------------
+
+  blkio.bfq.weight
+	  Specifies per cgroup weight. This is default weight of the group
+	  on all the devices until and unless overridden by per device rule
+	  (see `blkio.bfq.weight_device` below).
+
+	  Currently allowed range of weights is from 1 to 1000. For more details,
+          see Documentation/block/bfq-iosched.rst.
+
+  blkio.bfq.weight_device
+          Specifies per cgroup per device weights, overriding the default group
+          weight. For more details, see Documentation/block/bfq-iosched.rst.
+
+	  Following is the format::
+
+	    # echo dev_maj:dev_minor weight > blkio.bfq.weight_device
+
+	  Configure weight=300 on /dev/sdb (8:16) in this cgroup::
+
+	    # echo 8:16 300 > blkio.bfq.weight_device
+	    # cat blkio.bfq.weight_device
+	    dev     weight
+	    8:16    300
+
+	  Configure weight=500 on /dev/sda (8:0) in this cgroup::
+
+	    # echo 8:0 500 > blkio.bfq.weight_device
+	    # cat blkio.bfq.weight_device
+	    dev     weight
+	    8:0     500
+	    8:16    300
+
+	  Remove specific weight for /dev/sda in this cgroup::
+
+	    # echo 8:0 0 > blkio.bfq.weight_device
+	    # cat blkio.bfq.weight_device
+	    dev     weight
+	    8:16    300
+
+  blkio.time
+	  Disk time allocated to cgroup per device in milliseconds. First
+	  two fields specify the major and minor number of the device and
+	  third field specifies the disk time allocated to group in
+	  milliseconds.
+
+  blkio.sectors
+	  Number of sectors transferred to/from disk by the group. First
+	  two fields specify the major and minor number of the device and
+	  third field specifies the number of sectors transferred by the
+	  group to/from the device.
+
+  blkio.io_service_bytes
+	  Number of bytes transferred to/from the disk by the group. These
+	  are further divided by the type of operation - read or write, sync
+	  or async. First two fields specify the major and minor number of the
+	  device, third field specifies the operation type and the fourth field
+	  specifies the number of bytes.
+
+  blkio.io_serviced
+	  Number of IOs (bio) issued to the disk by the group. These
+	  are further divided by the type of operation - read or write, sync
+	  or async. First two fields specify the major and minor number of the
+	  device, third field specifies the operation type and the fourth field
+	  specifies the number of IOs.
+
+  blkio.io_service_time
+	  Total amount of time between request dispatch and request completion
+	  for the IOs done by this cgroup. This is in nanoseconds to make it
+	  meaningful for flash devices too. For devices with queue depth of 1,
+	  this time represents the actual service time. When queue_depth > 1,
+	  that is no longer true as requests may be served out of order. This
+	  may cause the service time for a given IO to include the service time
+	  of multiple IOs when served out of order which may result in total
+	  io_service_time > actual time elapsed. This time is further divided by
+	  the type of operation - read or write, sync or async. First two fields
+	  specify the major and minor number of the device, third field
+	  specifies the operation type and the fourth field specifies the
+	  io_service_time in ns.
+
+  blkio.io_wait_time
+	  Total amount of time the IOs for this cgroup spent waiting in the
+	  scheduler queues for service. This can be greater than the total time
+	  elapsed since it is cumulative io_wait_time for all IOs. It is not a
+	  measure of total time the cgroup spent waiting but rather a measure of
+	  the wait_time for its individual IOs. For devices with queue_depth > 1
+	  this metric does not include the time spent waiting for service once
+	  the IO is dispatched to the device but till it actually gets serviced
+	  (there might be a time lag here due to re-ordering of requests by the
+	  device). This is in nanoseconds to make it meaningful for flash
+	  devices too. This time is further divided by the type of operation -
+	  read or write, sync or async. First two fields specify the major and
+	  minor number of the device, third field specifies the operation type
+	  and the fourth field specifies the io_wait_time in ns.
+
+  blkio.io_merged
+	  Total number of bios/requests merged into requests belonging to this
+	  cgroup. This is further divided by the type of operation - read or
+	  write, sync or async.
+
+  blkio.io_queued
+	  Total number of requests queued up at any given instant for this
+	  cgroup. This is further divided by the type of operation - read or
+	  write, sync or async.
+
+  blkio.avg_queue_size
+	  Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
+	  The average queue size for this cgroup over the entire time of this
+	  cgroup's existence. Queue size samples are taken each time one of the
+	  queues of this cgroup gets a timeslice.
+
+  blkio.group_wait_time
+	  Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
+	  This is the amount of time the cgroup had to wait since it became busy
+	  (i.e., went from 0 to 1 request queued) to get a timeslice for one of
+	  its queues. This is different from the io_wait_time which is the
+	  cumulative total of the amount of time spent by each IO in that cgroup
+	  waiting in the scheduler queue. This is in nanoseconds. If this is
+	  read when the cgroup is in a waiting (for timeslice) state, the stat
+	  will only report the group_wait_time accumulated till the last time it
+	  got a timeslice and will not include the current delta.
+
+  blkio.empty_time
+	  Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
+	  This is the amount of time a cgroup spends without any pending
+	  requests when not being served, i.e., it does not include any time
+	  spent idling for one of the queues of the cgroup. This is in
+	  nanoseconds. If this is read when the cgroup is in an empty state,
+	  the stat will only report the empty_time accumulated till the last
+	  time it had a pending request and will not include the current delta.
+
+  blkio.idle_time
+	  Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y.
+	  This is the amount of time spent by the IO scheduler idling for a
+	  given cgroup in anticipation of a better request than the existing ones
+	  from other queues/cgroups. This is in nanoseconds. If this is read
+	  when the cgroup is in an idling state, the stat will only report the
+	  idle_time accumulated till the last idle period and will not include
+	  the current delta.
+
+  blkio.dequeue
+	  Debugging aid only enabled if CONFIG_BFQ_CGROUP_DEBUG=y. This
+	  gives the statistics about how many a times a group was dequeued
+	  from service tree of the device. First two fields specify the major
+	  and minor number of the device and third field specifies the number
+	  of times a group was dequeued from a particular device.
+
+  blkio.*_recursive
+	  Recursive version of various stats. These files show the
+          same information as their non-recursive counterparts but
+          include stats from all the descendant cgroups.
+
+Throttling/Upper limit policy files
+-----------------------------------
+  blkio.throttle.read_bps_device
+	  Specifies upper limit on READ rate from the device. IO rate is
+	  specified in bytes per second. Rules are per device. Following is
+	  the format::
+
+	    echo "<major>:<minor>  <rate_bytes_per_second>" > /cgrp/blkio.throttle.read_bps_device
+
+  blkio.throttle.write_bps_device
+	  Specifies upper limit on WRITE rate to the device. IO rate is
+	  specified in bytes per second. Rules are per device. Following is
+	  the format::
+
+	    echo "<major>:<minor>  <rate_bytes_per_second>" > /cgrp/blkio.throttle.write_bps_device
+
+  blkio.throttle.read_iops_device
+	  Specifies upper limit on READ rate from the device. IO rate is
+	  specified in IO per second. Rules are per device. Following is
+	  the format::
+
+	   echo "<major>:<minor>  <rate_io_per_second>" > /cgrp/blkio.throttle.read_iops_device
+
+  blkio.throttle.write_iops_device
+	  Specifies upper limit on WRITE rate to the device. IO rate is
+	  specified in io per second. Rules are per device. Following is
+	  the format::
+
+	    echo "<major>:<minor>  <rate_io_per_second>" > /cgrp/blkio.throttle.write_iops_device
+
+          Note: If both BW and IOPS rules are specified for a device, then IO is
+          subjected to both the constraints.
+
+  blkio.throttle.io_serviced
+	  Number of IOs (bio) issued to the disk by the group. These
+	  are further divided by the type of operation - read or write, sync
+	  or async. First two fields specify the major and minor number of the
+	  device, third field specifies the operation type and the fourth field
+	  specifies the number of IOs.
+
+  blkio.throttle.io_service_bytes
+	  Number of bytes transferred to/from the disk by the group. These
+	  are further divided by the type of operation - read or write, sync
+	  or async. First two fields specify the major and minor number of the
+	  device, third field specifies the operation type and the fourth field
+	  specifies the number of bytes.
+
+Common files among various policies
+-----------------------------------
+  blkio.reset_stats
+	  Writing an int to this file will result in resetting all the stats
+	  for that cgroup.
diff --git a/Documentation/admin-guide/cgroup-v1/cgroups.rst b/Documentation/admin-guide/cgroup-v1/cgroups.rst
new file mode 100644
index 000000000..e501f45ea
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/cgroups.rst
@@ -0,0 +1,697 @@
+==============
+Control Groups
+==============
+
+Written by Paul Menage <menage@google.com> based on
+Documentation/admin-guide/cgroup-v1/cpusets.rst
+
+Original copyright statements from cpusets.txt:
+
+Portions Copyright (C) 2004 BULL SA.
+
+Portions Copyright (c) 2004-2006 Silicon Graphics, Inc.
+
+Modified by Paul Jackson <pj@sgi.com>
+
+Modified by Christoph Lameter <cl@gentwo.org>
+
+.. CONTENTS:
+
+	1. Control Groups
+	1.1 What are cgroups ?
+	1.2 Why are cgroups needed ?
+	1.3 How are cgroups implemented ?
+	1.4 What does notify_on_release do ?
+	1.5 What does clone_children do ?
+	1.6 How do I use cgroups ?
+	2. Usage Examples and Syntax
+	2.1 Basic Usage
+	2.2 Attaching processes
+	2.3 Mounting hierarchies by name
+	3. Kernel API
+	3.1 Overview
+	3.2 Synchronization
+	3.3 Subsystem API
+	4. Extended attributes usage
+	5. Questions
+
+1. Control Groups
+=================
+
+1.1 What are cgroups ?
+----------------------
+
+Control Groups provide a mechanism for aggregating/partitioning sets of
+tasks, and all their future children, into hierarchical groups with
+specialized behaviour.
+
+Definitions:
+
+A *cgroup* associates a set of tasks with a set of parameters for one
+or more subsystems.
+
+A *subsystem* is a module that makes use of the task grouping
+facilities provided by cgroups to treat groups of tasks in
+particular ways. A subsystem is typically a "resource controller" that
+schedules a resource or applies per-cgroup limits, but it may be
+anything that wants to act on a group of processes, e.g. a
+virtualization subsystem.
+
+A *hierarchy* is a set of cgroups arranged in a tree, such that
+every task in the system is in exactly one of the cgroups in the
+hierarchy, and a set of subsystems; each subsystem has system-specific
+state attached to each cgroup in the hierarchy.  Each hierarchy has
+an instance of the cgroup virtual filesystem associated with it.
+
+At any one time there may be multiple active hierarchies of task
+cgroups. Each hierarchy is a partition of all tasks in the system.
+
+User-level code may create and destroy cgroups by name in an
+instance of the cgroup virtual file system, specify and query to
+which cgroup a task is assigned, and list the task PIDs assigned to
+a cgroup. Those creations and assignments only affect the hierarchy
+associated with that instance of the cgroup file system.
+
+On their own, the only use for cgroups is for simple job
+tracking. The intention is that other subsystems hook into the generic
+cgroup support to provide new attributes for cgroups, such as
+accounting/limiting the resources which processes in a cgroup can
+access. For example, cpusets (see Documentation/admin-guide/cgroup-v1/cpusets.rst) allow
+you to associate a set of CPUs and a set of memory nodes with the
+tasks in each cgroup.
+
+.. _cgroups-why-needed:
+
+1.2 Why are cgroups needed ?
+----------------------------
+
+There are multiple efforts to provide process aggregations in the
+Linux kernel, mainly for resource-tracking purposes. Such efforts
+include cpusets, CKRM/ResGroups, UserBeanCounters, and virtual server
+namespaces. These all require the basic notion of a
+grouping/partitioning of processes, with newly forked processes ending
+up in the same group (cgroup) as their parent process.
+
+The kernel cgroup patch provides the minimum essential kernel
+mechanisms required to efficiently implement such groups. It has
+minimal impact on the system fast paths, and provides hooks for
+specific subsystems such as cpusets to provide additional behaviour as
+desired.
+
+Multiple hierarchy support is provided to allow for situations where
+the division of tasks into cgroups is distinctly different for
+different subsystems - having parallel hierarchies allows each
+hierarchy to be a natural division of tasks, without having to handle
+complex combinations of tasks that would be present if several
+unrelated subsystems needed to be forced into the same tree of
+cgroups.
+
+At one extreme, each resource controller or subsystem could be in a
+separate hierarchy; at the other extreme, all subsystems
+would be attached to the same hierarchy.
+
+As an example of a scenario (originally proposed by vatsa@in.ibm.com)
+that can benefit from multiple hierarchies, consider a large
+university server with various users - students, professors, system
+tasks etc. The resource planning for this server could be along the
+following lines::
+
+       CPU :          "Top cpuset"
+                       /       \
+               CPUSet1         CPUSet2
+                  |               |
+               (Professors)    (Students)
+
+               In addition (system tasks) are attached to topcpuset (so
+               that they can run anywhere) with a limit of 20%
+
+       Memory : Professors (50%), Students (30%), system (20%)
+
+       Disk : Professors (50%), Students (30%), system (20%)
+
+       Network : WWW browsing (20%), Network File System (60%), others (20%)
+                               / \
+               Professors (15%)  students (5%)
+
+Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd goes
+into the NFS network class.
+
+At the same time Firefox/Lynx will share an appropriate CPU/Memory class
+depending on who launched it (prof/student).
+
+With the ability to classify tasks differently for different resources
+(by putting those resource subsystems in different hierarchies),
+the admin can easily set up a script which receives exec notifications
+and depending on who is launching the browser he can::
+
+    # echo browser_pid > /sys/fs/cgroup/<restype>/<userclass>/tasks
+
+With only a single hierarchy, he now would potentially have to create
+a separate cgroup for every browser launched and associate it with
+appropriate network and other resource class.  This may lead to
+proliferation of such cgroups.
+
+Also let's say that the administrator would like to give enhanced network
+access temporarily to a student's browser (since it is night and the user
+wants to do online gaming :))  OR give one of the student's simulation
+apps enhanced CPU power.
+
+With ability to write PIDs directly to resource classes, it's just a
+matter of::
+
+       # echo pid > /sys/fs/cgroup/network/<new_class>/tasks
+       (after some time)
+       # echo pid > /sys/fs/cgroup/network/<orig_class>/tasks
+
+Without this ability, the administrator would have to split the cgroup into
+multiple separate ones and then associate the new cgroups with the
+new resource classes.
+
+
+
+1.3 How are cgroups implemented ?
+---------------------------------
+
+Control Groups extends the kernel as follows:
+
+ - Each task in the system has a reference-counted pointer to a
+   css_set.
+
+ - A css_set contains a set of reference-counted pointers to
+   cgroup_subsys_state objects, one for each cgroup subsystem
+   registered in the system. There is no direct link from a task to
+   the cgroup of which it's a member in each hierarchy, but this
+   can be determined by following pointers through the
+   cgroup_subsys_state objects. This is because accessing the
+   subsystem state is something that's expected to happen frequently
+   and in performance-critical code, whereas operations that require a
+   task's actual cgroup assignments (in particular, moving between
+   cgroups) are less common. A linked list runs through the cg_list
+   field of each task_struct using the css_set, anchored at
+   css_set->tasks.
+
+ - A cgroup hierarchy filesystem can be mounted for browsing and
+   manipulation from user space.
+
+ - You can list all the tasks (by PID) attached to any cgroup.
+
+The implementation of cgroups requires a few, simple hooks
+into the rest of the kernel, none in performance-critical paths:
+
+ - in init/main.c, to initialize the root cgroups and initial
+   css_set at system boot.
+
+ - in fork and exit, to attach and detach a task from its css_set.
+
+In addition, a new file system of type "cgroup" may be mounted, to
+enable browsing and modifying the cgroups presently known to the
+kernel.  When mounting a cgroup hierarchy, you may specify a
+comma-separated list of subsystems to mount as the filesystem mount
+options.  By default, mounting the cgroup filesystem attempts to
+mount a hierarchy containing all registered subsystems.
+
+If an active hierarchy with exactly the same set of subsystems already
+exists, it will be reused for the new mount. If no existing hierarchy
+matches, and any of the requested subsystems are in use in an existing
+hierarchy, the mount will fail with -EBUSY. Otherwise, a new hierarchy
+is activated, associated with the requested subsystems.
+
+It's not currently possible to bind a new subsystem to an active
+cgroup hierarchy, or to unbind a subsystem from an active cgroup
+hierarchy. This may be possible in future, but is fraught with nasty
+error-recovery issues.
+
+When a cgroup filesystem is unmounted, if there are any
+child cgroups created below the top-level cgroup, that hierarchy
+will remain active even though unmounted; if there are no
+child cgroups then the hierarchy will be deactivated.
+
+No new system calls are added for cgroups - all support for
+querying and modifying cgroups is via this cgroup file system.
+
+Each task under /proc has an added file named 'cgroup' displaying,
+for each active hierarchy, the subsystem names and the cgroup name
+as the path relative to the root of the cgroup file system.
+
+Each cgroup is represented by a directory in the cgroup file system
+containing the following files describing that cgroup:
+
+ - tasks: list of tasks (by PID) attached to that cgroup.  This list
+   is not guaranteed to be sorted.  Writing a thread ID into this file
+   moves the thread into this cgroup.
+ - cgroup.procs: list of thread group IDs in the cgroup.  This list is
+   not guaranteed to be sorted or free of duplicate TGIDs, and userspace
+   should sort/uniquify the list if this property is required.
+   Writing a thread group ID into this file moves all threads in that
+   group into this cgroup.
+ - notify_on_release flag: run the release agent on exit?
+ - release_agent: the path to use for release notifications (this file
+   exists in the top cgroup only)
+
+Other subsystems such as cpusets may add additional files in each
+cgroup dir.
+
+New cgroups are created using the mkdir system call or shell
+command.  The properties of a cgroup, such as its flags, are
+modified by writing to the appropriate file in that cgroups
+directory, as listed above.
+
+The named hierarchical structure of nested cgroups allows partitioning
+a large system into nested, dynamically changeable, "soft-partitions".
+
+The attachment of each task, automatically inherited at fork by any
+children of that task, to a cgroup allows organizing the work load
+on a system into related sets of tasks.  A task may be re-attached to
+any other cgroup, if allowed by the permissions on the necessary
+cgroup file system directories.
+
+When a task is moved from one cgroup to another, it gets a new
+css_set pointer - if there's an already existing css_set with the
+desired collection of cgroups then that group is reused, otherwise a new
+css_set is allocated. The appropriate existing css_set is located by
+looking into a hash table.
+
+To allow access from a cgroup to the css_sets (and hence tasks)
+that comprise it, a set of cg_cgroup_link objects form a lattice;
+each cg_cgroup_link is linked into a list of cg_cgroup_links for
+a single cgroup on its cgrp_link_list field, and a list of
+cg_cgroup_links for a single css_set on its cg_link_list.
+
+Thus the set of tasks in a cgroup can be listed by iterating over
+each css_set that references the cgroup, and sub-iterating over
+each css_set's task set.
+
+The use of a Linux virtual file system (vfs) to represent the
+cgroup hierarchy provides for a familiar permission and name space
+for cgroups, with a minimum of additional kernel code.
+
+1.4 What does notify_on_release do ?
+------------------------------------
+
+If the notify_on_release flag is enabled (1) in a cgroup, then
+whenever the last task in the cgroup leaves (exits or attaches to
+some other cgroup) and the last child cgroup of that cgroup
+is removed, then the kernel runs the command specified by the contents
+of the "release_agent" file in that hierarchy's root directory,
+supplying the pathname (relative to the mount point of the cgroup
+file system) of the abandoned cgroup.  This enables automatic
+removal of abandoned cgroups.  The default value of
+notify_on_release in the root cgroup at system boot is disabled
+(0).  The default value of other cgroups at creation is the current
+value of their parents' notify_on_release settings. The default value of
+a cgroup hierarchy's release_agent path is empty.
+
+1.5 What does clone_children do ?
+---------------------------------
+
+This flag only affects the cpuset controller. If the clone_children
+flag is enabled (1) in a cgroup, a new cpuset cgroup will copy its
+configuration from the parent during initialization.
+
+1.6 How do I use cgroups ?
+--------------------------
+
+To start a new job that is to be contained within a cgroup, using
+the "cpuset" cgroup subsystem, the steps are something like::
+
+ 1) mount -t tmpfs cgroup_root /sys/fs/cgroup
+ 2) mkdir /sys/fs/cgroup/cpuset
+ 3) mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset
+ 4) Create the new cgroup by doing mkdir's and write's (or echo's) in
+    the /sys/fs/cgroup/cpuset virtual file system.
+ 5) Start a task that will be the "founding father" of the new job.
+ 6) Attach that task to the new cgroup by writing its PID to the
+    /sys/fs/cgroup/cpuset tasks file for that cgroup.
+ 7) fork, exec or clone the job tasks from this founding father task.
+
+For example, the following sequence of commands will setup a cgroup
+named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,
+and then start a subshell 'sh' in that cgroup::
+
+  mount -t tmpfs cgroup_root /sys/fs/cgroup
+  mkdir /sys/fs/cgroup/cpuset
+  mount -t cgroup cpuset -ocpuset /sys/fs/cgroup/cpuset
+  cd /sys/fs/cgroup/cpuset
+  mkdir Charlie
+  cd Charlie
+  /bin/echo 2-3 > cpuset.cpus
+  /bin/echo 1 > cpuset.mems
+  /bin/echo $$ > tasks
+  sh
+  # The subshell 'sh' is now running in cgroup Charlie
+  # The next line should display '/Charlie'
+  cat /proc/self/cgroup
+
+2. Usage Examples and Syntax
+============================
+
+2.1 Basic Usage
+---------------
+
+Creating, modifying, using cgroups can be done through the cgroup
+virtual filesystem.
+
+To mount a cgroup hierarchy with all available subsystems, type::
+
+  # mount -t cgroup xxx /sys/fs/cgroup
+
+The "xxx" is not interpreted by the cgroup code, but will appear in
+/proc/mounts so may be any useful identifying string that you like.
+
+Note: Some subsystems do not work without some user input first.  For instance,
+if cpusets are enabled the user will have to populate the cpus and mems files
+for each new cgroup created before that group can be used.
+
+As explained in section `1.2 Why are cgroups needed?` you should create
+different hierarchies of cgroups for each single resource or group of
+resources you want to control. Therefore, you should mount a tmpfs on
+/sys/fs/cgroup and create directories for each cgroup resource or resource
+group::
+
+  # mount -t tmpfs cgroup_root /sys/fs/cgroup
+  # mkdir /sys/fs/cgroup/rg1
+
+To mount a cgroup hierarchy with just the cpuset and memory
+subsystems, type::
+
+  # mount -t cgroup -o cpuset,memory hier1 /sys/fs/cgroup/rg1
+
+While remounting cgroups is currently supported, it is not recommend
+to use it. Remounting allows changing bound subsystems and
+release_agent. Rebinding is hardly useful as it only works when the
+hierarchy is empty and release_agent itself should be replaced with
+conventional fsnotify. The support for remounting will be removed in
+the future.
+
+To Specify a hierarchy's release_agent::
+
+  # mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \
+    xxx /sys/fs/cgroup/rg1
+
+Note that specifying 'release_agent' more than once will return failure.
+
+Note that changing the set of subsystems is currently only supported
+when the hierarchy consists of a single (root) cgroup. Supporting
+the ability to arbitrarily bind/unbind subsystems from an existing
+cgroup hierarchy is intended to be implemented in the future.
+
+Then under /sys/fs/cgroup/rg1 you can find a tree that corresponds to the
+tree of the cgroups in the system. For instance, /sys/fs/cgroup/rg1
+is the cgroup that holds the whole system.
+
+If you want to change the value of release_agent::
+
+  # echo "/sbin/new_release_agent" > /sys/fs/cgroup/rg1/release_agent
+
+It can also be changed via remount.
+
+If you want to create a new cgroup under /sys/fs/cgroup/rg1::
+
+  # cd /sys/fs/cgroup/rg1
+  # mkdir my_cgroup
+
+Now you want to do something with this cgroup:
+
+  # cd my_cgroup
+
+In this directory you can find several files::
+
+  # ls
+  cgroup.procs notify_on_release tasks
+  (plus whatever files added by the attached subsystems)
+
+Now attach your shell to this cgroup::
+
+  # /bin/echo $$ > tasks
+
+You can also create cgroups inside your cgroup by using mkdir in this
+directory::
+
+  # mkdir my_sub_cs
+
+To remove a cgroup, just use rmdir::
+
+  # rmdir my_sub_cs
+
+This will fail if the cgroup is in use (has cgroups inside, or
+has processes attached, or is held alive by other subsystem-specific
+reference).
+
+2.2 Attaching processes
+-----------------------
+
+::
+
+  # /bin/echo PID > tasks
+
+Note that it is PID, not PIDs. You can only attach ONE task at a time.
+If you have several tasks to attach, you have to do it one after another::
+
+  # /bin/echo PID1 > tasks
+  # /bin/echo PID2 > tasks
+	  ...
+  # /bin/echo PIDn > tasks
+
+You can attach the current shell task by echoing 0::
+
+  # echo 0 > tasks
+
+You can use the cgroup.procs file instead of the tasks file to move all
+threads in a threadgroup at once. Echoing the PID of any task in a
+threadgroup to cgroup.procs causes all tasks in that threadgroup to be
+attached to the cgroup. Writing 0 to cgroup.procs moves all tasks
+in the writing task's threadgroup.
+
+Note: Since every task is always a member of exactly one cgroup in each
+mounted hierarchy, to remove a task from its current cgroup you must
+move it into a new cgroup (possibly the root cgroup) by writing to the
+new cgroup's tasks file.
+
+Note: Due to some restrictions enforced by some cgroup subsystems, moving
+a process to another cgroup can fail.
+
+2.3 Mounting hierarchies by name
+--------------------------------
+
+Passing the name=<x> option when mounting a cgroups hierarchy
+associates the given name with the hierarchy.  This can be used when
+mounting a pre-existing hierarchy, in order to refer to it by name
+rather than by its set of active subsystems.  Each hierarchy is either
+nameless, or has a unique name.
+
+The name should match [\w.-]+
+
+When passing a name=<x> option for a new hierarchy, you need to
+specify subsystems manually; the legacy behaviour of mounting all
+subsystems when none are explicitly specified is not supported when
+you give a subsystem a name.
+
+The name of the subsystem appears as part of the hierarchy description
+in /proc/mounts and /proc/<pid>/cgroups.
+
+
+3. Kernel API
+=============
+
+3.1 Overview
+------------
+
+Each kernel subsystem that wants to hook into the generic cgroup
+system needs to create a cgroup_subsys object. This contains
+various methods, which are callbacks from the cgroup system, along
+with a subsystem ID which will be assigned by the cgroup system.
+
+Other fields in the cgroup_subsys object include:
+
+- subsys_id: a unique array index for the subsystem, indicating which
+  entry in cgroup->subsys[] this subsystem should be managing.
+
+- name: should be initialized to a unique subsystem name. Should be
+  no longer than MAX_CGROUP_TYPE_NAMELEN.
+
+- early_init: indicate if the subsystem needs early initialization
+  at system boot.
+
+Each cgroup object created by the system has an array of pointers,
+indexed by subsystem ID; this pointer is entirely managed by the
+subsystem; the generic cgroup code will never touch this pointer.
+
+3.2 Synchronization
+-------------------
+
+There is a global mutex, cgroup_mutex, used by the cgroup
+system. This should be taken by anything that wants to modify a
+cgroup. It may also be taken to prevent cgroups from being
+modified, but more specific locks may be more appropriate in that
+situation.
+
+See kernel/cgroup/cgroup.c for more details.
+
+Subsystems can take/release the cgroup_mutex via the functions
+cgroup_lock()/cgroup_unlock().
+
+Accessing a task's cgroup pointer may be done in the following ways:
+- while holding cgroup_mutex
+- while holding the task's alloc_lock (via task_lock())
+- inside an rcu_read_lock() section via rcu_dereference()
+
+3.3 Subsystem API
+-----------------
+
+Each subsystem should:
+
+- add an entry in linux/cgroup_subsys.h
+- define a cgroup_subsys object called <name>_cgrp_subsys
+
+Each subsystem may export the following methods. The only mandatory
+methods are css_alloc/free. Any others that are null are presumed to
+be successful no-ops.
+
+``struct cgroup_subsys_state *css_alloc(struct cgroup *cgrp)``
+(cgroup_mutex held by caller)
+
+Called to allocate a subsystem state object for a cgroup. The
+subsystem should allocate its subsystem state object for the passed
+cgroup, returning a pointer to the new object on success or a
+ERR_PTR() value. On success, the subsystem pointer should point to
+a structure of type cgroup_subsys_state (typically embedded in a
+larger subsystem-specific object), which will be initialized by the
+cgroup system. Note that this will be called at initialization to
+create the root subsystem state for this subsystem; this case can be
+identified by the passed cgroup object having a NULL parent (since
+it's the root of the hierarchy) and may be an appropriate place for
+initialization code.
+
+``int css_online(struct cgroup *cgrp)``
+(cgroup_mutex held by caller)
+
+Called after @cgrp successfully completed all allocations and made
+visible to cgroup_for_each_child/descendant_*() iterators. The
+subsystem may choose to fail creation by returning -errno. This
+callback can be used to implement reliable state sharing and
+propagation along the hierarchy. See the comment on
+cgroup_for_each_live_descendant_pre() for details.
+
+``void css_offline(struct cgroup *cgrp);``
+(cgroup_mutex held by caller)
+
+This is the counterpart of css_online() and called iff css_online()
+has succeeded on @cgrp. This signifies the beginning of the end of
+@cgrp. @cgrp is being removed and the subsystem should start dropping
+all references it's holding on @cgrp. When all references are dropped,
+cgroup removal will proceed to the next step - css_free(). After this
+callback, @cgrp should be considered dead to the subsystem.
+
+``void css_free(struct cgroup *cgrp)``
+(cgroup_mutex held by caller)
+
+The cgroup system is about to free @cgrp; the subsystem should free
+its subsystem state object. By the time this method is called, @cgrp
+is completely unused; @cgrp->parent is still valid. (Note - can also
+be called for a newly-created cgroup if an error occurs after this
+subsystem's create() method has been called for the new cgroup).
+
+``int can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)``
+(cgroup_mutex held by caller)
+
+Called prior to moving one or more tasks into a cgroup; if the
+subsystem returns an error, this will abort the attach operation.
+@tset contains the tasks to be attached and is guaranteed to have at
+least one task in it.
+
+If there are multiple tasks in the taskset, then:
+  - it's guaranteed that all are from the same thread group
+  - @tset contains all tasks from the thread group whether or not
+    they're switching cgroups
+  - the first task is the leader
+
+Each @tset entry also contains the task's old cgroup and tasks which
+aren't switching cgroup can be skipped easily using the
+cgroup_taskset_for_each() iterator. Note that this isn't called on a
+fork. If this method returns 0 (success) then this should remain valid
+while the caller holds cgroup_mutex and it is ensured that either
+attach() or cancel_attach() will be called in future.
+
+``void css_reset(struct cgroup_subsys_state *css)``
+(cgroup_mutex held by caller)
+
+An optional operation which should restore @css's configuration to the
+initial state.  This is currently only used on the unified hierarchy
+when a subsystem is disabled on a cgroup through
+"cgroup.subtree_control" but should remain enabled because other
+subsystems depend on it.  cgroup core makes such a css invisible by
+removing the associated interface files and invokes this callback so
+that the hidden subsystem can return to the initial neutral state.
+This prevents unexpected resource control from a hidden css and
+ensures that the configuration is in the initial state when it is made
+visible again later.
+
+``void cancel_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)``
+(cgroup_mutex held by caller)
+
+Called when a task attach operation has failed after can_attach() has succeeded.
+A subsystem whose can_attach() has some side-effects should provide this
+function, so that the subsystem can implement a rollback. If not, not necessary.
+This will be called only about subsystems whose can_attach() operation have
+succeeded. The parameters are identical to can_attach().
+
+``void attach(struct cgroup *cgrp, struct cgroup_taskset *tset)``
+(cgroup_mutex held by caller)
+
+Called after the task has been attached to the cgroup, to allow any
+post-attachment activity that requires memory allocations or blocking.
+The parameters are identical to can_attach().
+
+``void fork(struct task_struct *task)``
+
+Called when a task is forked into a cgroup.
+
+``void exit(struct task_struct *task)``
+
+Called during task exit.
+
+``void free(struct task_struct *task)``
+
+Called when the task_struct is freed.
+
+``void bind(struct cgroup *root)``
+(cgroup_mutex held by caller)
+
+Called when a cgroup subsystem is rebound to a different hierarchy
+and root cgroup. Currently this will only involve movement between
+the default hierarchy (which never has sub-cgroups) and a hierarchy
+that is being created/destroyed (and hence has no sub-cgroups).
+
+4. Extended attribute usage
+===========================
+
+cgroup filesystem supports certain types of extended attributes in its
+directories and files.  The current supported types are:
+
+	- Trusted (XATTR_TRUSTED)
+	- Security (XATTR_SECURITY)
+
+Both require CAP_SYS_ADMIN capability to set.
+
+Like in tmpfs, the extended attributes in cgroup filesystem are stored
+using kernel memory and it's advised to keep the usage at minimum.  This
+is the reason why user defined extended attributes are not supported, since
+any user can do it and there's no limit in the value size.
+
+The current known users for this feature are SELinux to limit cgroup usage
+in containers and systemd for assorted meta data like main PID in a cgroup
+(systemd creates a cgroup per service).
+
+5. Questions
+============
+
+::
+
+  Q: what's up with this '/bin/echo' ?
+  A: bash's builtin 'echo' command does not check calls to write() against
+     errors. If you use it in the cgroup file system, you won't be
+     able to tell whether a command succeeded or failed.
+
+  Q: When I attach processes, only the first of the line gets really attached !
+  A: We can only return one error code per call to write(). So you should also
+     put only ONE PID.
diff --git a/Documentation/admin-guide/cgroup-v1/cpuacct.rst b/Documentation/admin-guide/cgroup-v1/cpuacct.rst
new file mode 100644
index 000000000..d30ed81d2
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/cpuacct.rst
@@ -0,0 +1,50 @@
+=========================
+CPU Accounting Controller
+=========================
+
+The CPU accounting controller is used to group tasks using cgroups and
+account the CPU usage of these groups of tasks.
+
+The CPU accounting controller supports multi-hierarchy groups. An accounting
+group accumulates the CPU usage of all of its child groups and the tasks
+directly present in its group.
+
+Accounting groups can be created by first mounting the cgroup filesystem::
+
+  # mount -t cgroup -ocpuacct none /sys/fs/cgroup
+
+With the above step, the initial or the parent accounting group becomes
+visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in
+the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.
+/sys/fs/cgroup/cpuacct.usage gives the CPU time (in nanoseconds) obtained
+by this group which is essentially the CPU time obtained by all the tasks
+in the system.
+
+New accounting groups can be created under the parent group /sys/fs/cgroup::
+
+  # cd /sys/fs/cgroup
+  # mkdir g1
+  # echo $$ > g1/tasks
+
+The above steps create a new group g1 and move the current shell
+process (bash) into it. CPU time consumed by this bash and its children
+can be obtained from g1/cpuacct.usage and the same is accumulated in
+/sys/fs/cgroup/cpuacct.usage also.
+
+cpuacct.stat file lists a few statistics which further divide the
+CPU time obtained by the cgroup into user and system times. Currently
+the following statistics are supported:
+
+user: Time spent by tasks of the cgroup in user mode.
+system: Time spent by tasks of the cgroup in kernel mode.
+
+user and system are in USER_HZ unit.
+
+cpuacct controller uses percpu_counter interface to collect user and
+system times. This has two side effects:
+
+- It is theoretically possible to see wrong values for user and system times.
+  This is because percpu_counter_read() on 32bit systems isn't safe
+  against concurrent writes.
+- It is possible to see slightly outdated values for user and system times
+  due to the batch processing nature of percpu_counter.
diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst
new file mode 100644
index 000000000..fb3fb6fa8
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst
@@ -0,0 +1,874 @@
+.. _cpusets:
+
+=======
+CPUSETS
+=======
+
+Copyright (C) 2004 BULL SA.
+
+Written by Simon.Derr@bull.net
+
+- Portions Copyright (c) 2004-2006 Silicon Graphics, Inc.
+- Modified by Paul Jackson <pj@sgi.com>
+- Modified by Christoph Lameter <cl@gentwo.org>
+- Modified by Paul Menage <menage@google.com>
+- Modified by Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
+
+.. CONTENTS:
+
+   1. Cpusets
+     1.1 What are cpusets ?
+     1.2 Why are cpusets needed ?
+     1.3 How are cpusets implemented ?
+     1.4 What are exclusive cpusets ?
+     1.5 What is memory_pressure ?
+     1.6 What is memory spread ?
+     1.7 What is sched_load_balance ?
+     1.8 What is sched_relax_domain_level ?
+     1.9 How do I use cpusets ?
+   2. Usage Examples and Syntax
+     2.1 Basic Usage
+     2.2 Adding/removing cpus
+     2.3 Setting flags
+     2.4 Attaching processes
+   3. Questions
+   4. Contact
+
+1. Cpusets
+==========
+
+1.1 What are cpusets ?
+----------------------
+
+Cpusets provide a mechanism for assigning a set of CPUs and Memory
+Nodes to a set of tasks.   In this document "Memory Node" refers to
+an on-line node that contains memory.
+
+Cpusets constrain the CPU and Memory placement of tasks to only
+the resources within a task's current cpuset.  They form a nested
+hierarchy visible in a virtual file system.  These are the essential
+hooks, beyond what is already present, required to manage dynamic
+job placement on large systems.
+
+Cpusets use the generic cgroup subsystem described in
+Documentation/admin-guide/cgroup-v1/cgroups.rst.
+
+Requests by a task, using the sched_setaffinity(2) system call to
+include CPUs in its CPU affinity mask, and using the mbind(2) and
+set_mempolicy(2) system calls to include Memory Nodes in its memory
+policy, are both filtered through that task's cpuset, filtering out any
+CPUs or Memory Nodes not in that cpuset.  The scheduler will not
+schedule a task on a CPU that is not allowed in its cpus_allowed
+vector, and the kernel page allocator will not allocate a page on a
+node that is not allowed in the requesting task's mems_allowed vector.
+
+User level code may create and destroy cpusets by name in the cgroup
+virtual file system, manage the attributes and permissions of these
+cpusets and which CPUs and Memory Nodes are assigned to each cpuset,
+specify and query to which cpuset a task is assigned, and list the
+task pids assigned to a cpuset.
+
+
+1.2 Why are cpusets needed ?
+----------------------------
+
+The management of large computer systems, with many processors (CPUs),
+complex memory cache hierarchies and multiple Memory Nodes having
+non-uniform access times (NUMA) presents additional challenges for
+the efficient scheduling and memory placement of processes.
+
+Frequently more modest sized systems can be operated with adequate
+efficiency just by letting the operating system automatically share
+the available CPU and Memory resources amongst the requesting tasks.
+
+But larger systems, which benefit more from careful processor and
+memory placement to reduce memory access times and contention,
+and which typically represent a larger investment for the customer,
+can benefit from explicitly placing jobs on properly sized subsets of
+the system.
+
+This can be especially valuable on:
+
+    * Web Servers running multiple instances of the same web application,
+    * Servers running different applications (for instance, a web server
+      and a database), or
+    * NUMA systems running large HPC applications with demanding
+      performance characteristics.
+
+These subsets, or "soft partitions" must be able to be dynamically
+adjusted, as the job mix changes, without impacting other concurrently
+executing jobs. The location of the running jobs pages may also be moved
+when the memory locations are changed.
+
+The kernel cpuset patch provides the minimum essential kernel
+mechanisms required to efficiently implement such subsets.  It
+leverages existing CPU and Memory Placement facilities in the Linux
+kernel to avoid any additional impact on the critical scheduler or
+memory allocator code.
+
+
+1.3 How are cpusets implemented ?
+---------------------------------
+
+Cpusets provide a Linux kernel mechanism to constrain which CPUs and
+Memory Nodes are used by a process or set of processes.
+
+The Linux kernel already has a pair of mechanisms to specify on which
+CPUs a task may be scheduled (sched_setaffinity) and on which Memory
+Nodes it may obtain memory (mbind, set_mempolicy).
+
+Cpusets extends these two mechanisms as follows:
+
+ - Cpusets are sets of allowed CPUs and Memory Nodes, known to the
+   kernel.
+ - Each task in the system is attached to a cpuset, via a pointer
+   in the task structure to a reference counted cgroup structure.
+ - Calls to sched_setaffinity are filtered to just those CPUs
+   allowed in that task's cpuset.
+ - Calls to mbind and set_mempolicy are filtered to just
+   those Memory Nodes allowed in that task's cpuset.
+ - The root cpuset contains all the systems CPUs and Memory
+   Nodes.
+ - For any cpuset, one can define child cpusets containing a subset
+   of the parents CPU and Memory Node resources.
+ - The hierarchy of cpusets can be mounted at /dev/cpuset, for
+   browsing and manipulation from user space.
+ - A cpuset may be marked exclusive, which ensures that no other
+   cpuset (except direct ancestors and descendants) may contain
+   any overlapping CPUs or Memory Nodes.
+ - You can list all the tasks (by pid) attached to any cpuset.
+
+The implementation of cpusets requires a few, simple hooks
+into the rest of the kernel, none in performance critical paths:
+
+ - in init/main.c, to initialize the root cpuset at system boot.
+ - in fork and exit, to attach and detach a task from its cpuset.
+ - in sched_setaffinity, to mask the requested CPUs by what's
+   allowed in that task's cpuset.
+ - in sched.c migrate_live_tasks(), to keep migrating tasks within
+   the CPUs allowed by their cpuset, if possible.
+ - in the mbind and set_mempolicy system calls, to mask the requested
+   Memory Nodes by what's allowed in that task's cpuset.
+ - in page_alloc.c, to restrict memory to allowed nodes.
+ - in vmscan.c, to restrict page recovery to the current cpuset.
+
+You should mount the "cgroup" filesystem type in order to enable
+browsing and modifying the cpusets presently known to the kernel.  No
+new system calls are added for cpusets - all support for querying and
+modifying cpusets is via this cpuset file system.
+
+The /proc/<pid>/status file for each task has four added lines,
+displaying the task's cpus_allowed (on which CPUs it may be scheduled)
+and mems_allowed (on which Memory Nodes it may obtain memory),
+in the two formats seen in the following example::
+
+  Cpus_allowed:   ffffffff,ffffffff,ffffffff,ffffffff
+  Cpus_allowed_list:      0-127
+  Mems_allowed:   ffffffff,ffffffff
+  Mems_allowed_list:      0-63
+
+Each cpuset is represented by a directory in the cgroup file system
+containing (on top of the standard cgroup files) the following
+files describing that cpuset:
+
+ - cpuset.cpus: list of CPUs in that cpuset
+ - cpuset.mems: list of Memory Nodes in that cpuset
+ - cpuset.memory_migrate flag: if set, move pages to cpusets nodes
+ - cpuset.cpu_exclusive flag: is cpu placement exclusive?
+ - cpuset.mem_exclusive flag: is memory placement exclusive?
+ - cpuset.mem_hardwall flag:  is memory allocation hardwalled
+ - cpuset.memory_pressure: measure of how much paging pressure in cpuset
+ - cpuset.memory_spread_page flag: if set, spread page cache evenly on allowed nodes
+ - cpuset.memory_spread_slab flag: OBSOLETE. Has no effect on allocation behavior.
+ - cpuset.sched_load_balance flag: if set, load balance within CPUs on that cpuset
+ - cpuset.sched_relax_domain_level: the searching range when migrating tasks
+
+In addition, only the root cpuset has the following file:
+
+ - cpuset.memory_pressure_enabled flag: compute memory_pressure?
+
+New cpusets are created using the mkdir system call or shell
+command.  The properties of a cpuset, such as its flags, allowed
+CPUs and Memory Nodes, and attached tasks, are modified by writing
+to the appropriate file in that cpusets directory, as listed above.
+
+The named hierarchical structure of nested cpusets allows partitioning
+a large system into nested, dynamically changeable, "soft-partitions".
+
+The attachment of each task, automatically inherited at fork by any
+children of that task, to a cpuset allows organizing the work load
+on a system into related sets of tasks such that each set is constrained
+to using the CPUs and Memory Nodes of a particular cpuset.  A task
+may be re-attached to any other cpuset, if allowed by the permissions
+on the necessary cpuset file system directories.
+
+Such management of a system "in the large" integrates smoothly with
+the detailed placement done on individual tasks and memory regions
+using the sched_setaffinity, mbind and set_mempolicy system calls.
+
+The following rules apply to each cpuset:
+
+ - Its CPUs and Memory Nodes must be a subset of its parents.
+ - It can't be marked exclusive unless its parent is.
+ - If its cpu or memory is exclusive, they may not overlap any sibling.
+
+These rules, and the natural hierarchy of cpusets, enable efficient
+enforcement of the exclusive guarantee, without having to scan all
+cpusets every time any of them change to ensure nothing overlaps a
+exclusive cpuset.  Also, the use of a Linux virtual file system (vfs)
+to represent the cpuset hierarchy provides for a familiar permission
+and name space for cpusets, with a minimum of additional kernel code.
+
+The cpus and mems files in the root (top_cpuset) cpuset are
+read-only.  The cpus file automatically tracks the value of
+cpu_online_mask using a CPU hotplug notifier, and the mems file
+automatically tracks the value of node_states[N_MEMORY]--i.e.,
+nodes with memory--using the cpuset_track_online_nodes() hook.
+
+The cpuset.effective_cpus and cpuset.effective_mems files are
+normally read-only copies of cpuset.cpus and cpuset.mems files
+respectively.  If the cpuset cgroup filesystem is mounted with the
+special "cpuset_v2_mode" option, the behavior of these files will become
+similar to the corresponding files in cpuset v2.  In other words, hotplug
+events will not change cpuset.cpus and cpuset.mems.  Those events will
+only affect cpuset.effective_cpus and cpuset.effective_mems which show
+the actual cpus and memory nodes that are currently used by this cpuset.
+See Documentation/admin-guide/cgroup-v2.rst for more information about
+cpuset v2 behavior.
+
+
+1.4 What are exclusive cpusets ?
+--------------------------------
+
+If a cpuset is cpu or mem exclusive, no other cpuset, other than
+a direct ancestor or descendant, may share any of the same CPUs or
+Memory Nodes.
+
+A cpuset that is cpuset.mem_exclusive *or* cpuset.mem_hardwall is "hardwalled",
+i.e. it restricts kernel allocations for page, buffer and other data
+commonly shared by the kernel across multiple users.  All cpusets,
+whether hardwalled or not, restrict allocations of memory for user
+space.  This enables configuring a system so that several independent
+jobs can share common kernel data, such as file system pages, while
+isolating each job's user allocation in its own cpuset.  To do this,
+construct a large mem_exclusive cpuset to hold all the jobs, and
+construct child, non-mem_exclusive cpusets for each individual job.
+Only a small amount of typical kernel memory, such as requests from
+interrupt handlers, is allowed to be taken outside even a
+mem_exclusive cpuset.
+
+
+1.5 What is memory_pressure ?
+-----------------------------
+The memory_pressure of a cpuset provides a simple per-cpuset metric
+of the rate that the tasks in a cpuset are attempting to free up in
+use memory on the nodes of the cpuset to satisfy additional memory
+requests.
+
+This enables batch managers monitoring jobs running in dedicated
+cpusets to efficiently detect what level of memory pressure that job
+is causing.
+
+This is useful both on tightly managed systems running a wide mix of
+submitted jobs, which may choose to terminate or re-prioritize jobs that
+are trying to use more memory than allowed on the nodes assigned to them,
+and with tightly coupled, long running, massively parallel scientific
+computing jobs that will dramatically fail to meet required performance
+goals if they start to use more memory than allowed to them.
+
+This mechanism provides a very economical way for the batch manager
+to monitor a cpuset for signs of memory pressure.  It's up to the
+batch manager or other user code to decide what to do about it and
+take action.
+
+==>
+    Unless this feature is enabled by writing "1" to the special file
+    /dev/cpuset/memory_pressure_enabled, the hook in the rebalance
+    code of the page allocator for this metric reduces to simply noticing
+    that the cpuset_memory_pressure_enabled flag is zero.  So only
+    systems that enable this feature will compute the metric.
+
+Why a per-cpuset, running average:
+
+    Because this meter is per-cpuset, rather than per-task or mm,
+    the system load imposed by a batch scheduler monitoring this
+    metric is sharply reduced on large systems, because a scan of
+    the tasklist can be avoided on each set of queries.
+
+    Because this meter is a running average, instead of an accumulating
+    counter, a batch scheduler can detect memory pressure with a
+    single read, instead of having to read and accumulate results
+    for a period of time.
+
+    Because this meter is per-cpuset rather than per-task or mm,
+    the batch scheduler can obtain the key information, memory
+    pressure in a cpuset, with a single read, rather than having to
+    query and accumulate results over all the (dynamically changing)
+    set of tasks in the cpuset.
+
+A per-cpuset simple digital filter (requires a spinlock and 3 words
+of data per-cpuset) is kept, and updated by any task attached to that
+cpuset, if it enters the synchronous (direct) page reclaim code.
+
+A per-cpuset file provides an integer number representing the recent
+(half-life of 10 seconds) rate of direct page reclaims caused by
+the tasks in the cpuset, in units of reclaims attempted per second,
+times 1000.
+
+
+1.6 What is memory spread ?
+---------------------------
+The 'cpuset.memory_spread_page' boolean flag file controls where the kernel
+allocates page-cache pages.
+The 'cpuset.memory_spread_slab' file is obsolete and has no effect on
+allocation behavior, but is retained for compatibility.
+
+If the per-cpuset boolean flag file 'cpuset.memory_spread_page' is set, then
+the kernel will spread the file system buffers (page cache) evenly
+over all the nodes that the faulting task is allowed to use, instead
+of preferring to put those pages on the node where the task is running.
+
+The setting of this flag does not affect anonymous data segment or
+stack segment pages of a task.
+
+By default, page cache memory spreading is off, and memory
+pages are allocated on the node local to where the task is running,
+except perhaps as modified by the task's NUMA mempolicy or cpuset
+configuration, so long as sufficient free memory pages are available.
+
+When new cpusets are created, they inherit the memory spread settings
+of their parent.
+
+Setting page cache memory spreading causes affected allocations to ignore the
+task's NUMA mempolicy and be spread instead. Tasks using mbind() or
+set_mempolicy() to set NUMA mempolicies will not notice any change as a
+result of their containing task's memory spread settings.  If memory spreading
+is turned off, then the currently specified NUMA mempolicy once again
+applies to memory page allocations.
+
+Both 'cpuset.memory_spread_page' and 'cpuset.memory_spread_slab' are boolean
+flag files. In the root cpuset, both files initially contain "0". Writing "1"
+or "0" to 'cpuset.memory_spread_page' enables or disables page-cache spreading,
+respectively. The value of 'cpuset.memory_spread_slab' is retained, can be read
+back and inherited, but it does not affect allocation behavior.
+
+The implementation is simple.
+
+Setting the flag 'cpuset.memory_spread_page' turns on a per-process flag
+PFA_SPREAD_PAGE for each task that is in that cpuset or subsequently
+joins that cpuset.  The page allocation calls for the page cache
+is modified to perform an inline check for this PFA_SPREAD_PAGE task
+flag, and if set, a call to a new routine cpuset_mem_spread_node()
+returns the node to prefer for the allocation.
+
+The cpuset_mem_spread_node() routine is also simple.  It uses the
+value of a per-task rotor cpuset_mem_spread_rotor to select the next
+node in the current task's mems_allowed to prefer for the allocation.
+
+This memory placement policy is also known (in other contexts) as
+round-robin or interleave.
+
+This policy can provide substantial improvements for jobs that need
+to place thread local data on the corresponding node, but that need
+to access large file system data sets that need to be spread across
+the several nodes in the jobs cpuset in order to fit.  Without this
+policy, especially for jobs that might have one thread reading in the
+data set, the memory allocation across the nodes in the jobs cpuset
+can become very uneven.
+
+1.7 What is sched_load_balance ?
+--------------------------------
+
+The kernel scheduler (kernel/sched/core.c) automatically load balances
+tasks.  If one CPU is underutilized, kernel code running on that
+CPU will look for tasks on other more overloaded CPUs and move those
+tasks to itself, within the constraints of such placement mechanisms
+as cpusets and sched_setaffinity.
+
+The algorithmic cost of load balancing and its impact on key shared
+kernel data structures such as the task list increases more than
+linearly with the number of CPUs being balanced.  So the scheduler
+has support to partition the systems CPUs into a number of sched
+domains such that it only load balances within each sched domain.
+Each sched domain covers some subset of the CPUs in the system;
+no two sched domains overlap; some CPUs might not be in any sched
+domain and hence won't be load balanced.
+
+Put simply, it costs less to balance between two smaller sched domains
+than one big one, but doing so means that overloads in one of the
+two domains won't be load balanced to the other one.
+
+By default, there is one sched domain covering all CPUs, including those
+marked isolated using the kernel boot time "isolcpus=" argument. However,
+the isolated CPUs will not participate in load balancing, and will not
+have tasks running on them unless explicitly assigned.
+
+This default load balancing across all CPUs is not well suited for
+the following two situations:
+
+ 1) On large systems, load balancing across many CPUs is expensive.
+    If the system is managed using cpusets to place independent jobs
+    on separate sets of CPUs, full load balancing is unnecessary.
+ 2) Systems supporting realtime on some CPUs need to minimize
+    system overhead on those CPUs, including avoiding task load
+    balancing if that is not needed.
+
+When the per-cpuset flag "cpuset.sched_load_balance" is enabled (the default
+setting), it requests that all the CPUs in that cpusets allowed 'cpuset.cpus'
+be contained in a single sched domain, ensuring that load balancing
+can move a task (not otherwised pinned, as by sched_setaffinity)
+from any CPU in that cpuset to any other.
+
+When the per-cpuset flag "cpuset.sched_load_balance" is disabled, then the
+scheduler will avoid load balancing across the CPUs in that cpuset,
+--except-- in so far as is necessary because some overlapping cpuset
+has "sched_load_balance" enabled.
+
+So, for example, if the top cpuset has the flag "cpuset.sched_load_balance"
+enabled, then the scheduler will have one sched domain covering all
+CPUs, and the setting of the "cpuset.sched_load_balance" flag in any other
+cpusets won't matter, as we're already fully load balancing.
+
+Therefore in the above two situations, the top cpuset flag
+"cpuset.sched_load_balance" should be disabled, and only some of the smaller,
+child cpusets have this flag enabled.
+
+When doing this, you don't usually want to leave any unpinned tasks in
+the top cpuset that might use non-trivial amounts of CPU, as such tasks
+may be artificially constrained to some subset of CPUs, depending on
+the particulars of this flag setting in descendant cpusets.  Even if
+such a task could use spare CPU cycles in some other CPUs, the kernel
+scheduler might not consider the possibility of load balancing that
+task to that underused CPU.
+
+Of course, tasks pinned to a particular CPU can be left in a cpuset
+that disables "cpuset.sched_load_balance" as those tasks aren't going anywhere
+else anyway.
+
+There is an impedance mismatch here, between cpusets and sched domains.
+Cpusets are hierarchical and nest.  Sched domains are flat; they don't
+overlap and each CPU is in at most one sched domain.
+
+It is necessary for sched domains to be flat because load balancing
+across partially overlapping sets of CPUs would risk unstable dynamics
+that would be beyond our understanding.  So if each of two partially
+overlapping cpusets enables the flag 'cpuset.sched_load_balance', then we
+form a single sched domain that is a superset of both.  We won't move
+a task to a CPU outside its cpuset, but the scheduler load balancing
+code might waste some compute cycles considering that possibility.
+
+This mismatch is why there is not a simple one-to-one relation
+between which cpusets have the flag "cpuset.sched_load_balance" enabled,
+and the sched domain configuration.  If a cpuset enables the flag, it
+will get balancing across all its CPUs, but if it disables the flag,
+it will only be assured of no load balancing if no other overlapping
+cpuset enables the flag.
+
+If two cpusets have partially overlapping 'cpuset.cpus' allowed, and only
+one of them has this flag enabled, then the other may find its
+tasks only partially load balanced, just on the overlapping CPUs.
+This is just the general case of the top_cpuset example given a few
+paragraphs above.  In the general case, as in the top cpuset case,
+don't leave tasks that might use non-trivial amounts of CPU in
+such partially load balanced cpusets, as they may be artificially
+constrained to some subset of the CPUs allowed to them, for lack of
+load balancing to the other CPUs.
+
+CPUs in "cpuset.isolcpus" were excluded from load balancing by the
+isolcpus= kernel boot option, and will never be load balanced regardless
+of the value of "cpuset.sched_load_balance" in any cpuset.
+
+1.7.1 sched_load_balance implementation details.
+------------------------------------------------
+
+The per-cpuset flag 'cpuset.sched_load_balance' defaults to enabled (contrary
+to most cpuset flags.)  When enabled for a cpuset, the kernel will
+ensure that it can load balance across all the CPUs in that cpuset
+(makes sure that all the CPUs in the cpus_allowed of that cpuset are
+in the same sched domain.)
+
+If two overlapping cpusets both have 'cpuset.sched_load_balance' enabled,
+then they will be (must be) both in the same sched domain.
+
+If, as is the default, the top cpuset has 'cpuset.sched_load_balance' enabled,
+then by the above that means there is a single sched domain covering
+the whole system, regardless of any other cpuset settings.
+
+The kernel commits to user space that it will avoid load balancing
+where it can.  It will pick as fine a granularity partition of sched
+domains as it can while still providing load balancing for any set
+of CPUs allowed to a cpuset having 'cpuset.sched_load_balance' enabled.
+
+The internal kernel cpuset to scheduler interface passes from the
+cpuset code to the scheduler code a partition of the load balanced
+CPUs in the system. This partition is a set of subsets (represented
+as an array of struct cpumask) of CPUs, pairwise disjoint, that cover
+all the CPUs that must be load balanced.
+
+The cpuset code builds a new such partition and passes it to the
+scheduler sched domain setup code, to have the sched domains rebuilt
+as necessary, whenever:
+
+ - the 'cpuset.sched_load_balance' flag of a cpuset with non-empty CPUs changes,
+ - or CPUs come or go from a cpuset with this flag enabled,
+ - or 'cpuset.sched_relax_domain_level' value of a cpuset with non-empty CPUs
+   and with this flag enabled changes,
+ - or a cpuset with non-empty CPUs and with this flag enabled is removed,
+ - or a cpu is offlined/onlined.
+
+This partition exactly defines what sched domains the scheduler should
+setup - one sched domain for each element (struct cpumask) in the
+partition.
+
+The scheduler remembers the currently active sched domain partitions.
+When the scheduler routine partition_sched_domains() is invoked from
+the cpuset code to update these sched domains, it compares the new
+partition requested with the current, and updates its sched domains,
+removing the old and adding the new, for each change.
+
+
+1.8 What is sched_relax_domain_level ?
+--------------------------------------
+
+In sched domain, the scheduler migrates tasks in 2 ways; periodic load
+balance on tick, and at time of some schedule events.
+
+When a task is woken up, scheduler try to move the task on idle CPU.
+For example, if a task A running on CPU X activates another task B
+on the same CPU X, and if CPU Y is X's sibling and performing idle,
+then scheduler migrate task B to CPU Y so that task B can start on
+CPU Y without waiting task A on CPU X.
+
+And if a CPU run out of tasks in its runqueue, the CPU try to pull
+extra tasks from other busy CPUs to help them before it is going to
+be idle.
+
+Of course it takes some searching cost to find movable tasks and/or
+idle CPUs, the scheduler might not search all CPUs in the domain
+every time.  In fact, in some architectures, the searching ranges on
+events are limited in the same socket or node where the CPU locates,
+while the load balance on tick searches all.
+
+For example, assume CPU Z is relatively far from CPU X.  Even if CPU Z
+is idle while CPU X and the siblings are busy, scheduler can't migrate
+woken task B from X to Z since it is out of its searching range.
+As the result, task B on CPU X need to wait task A or wait load balance
+on the next tick.  For some applications in special situation, waiting
+1 tick may be too long.
+
+The 'cpuset.sched_relax_domain_level' file allows you to request changing
+this searching range as you like.  This file takes int value which
+indicates size of searching range in levels approximately as follows,
+otherwise initial value -1 that indicates the cpuset has no request.
+
+====== ===========================================================
+  -1   no request. use system default or follow request of others.
+   0   no search.
+   1   search siblings (hyperthreads in a core).
+   2   search cores in a package.
+   3   search cpus in a node [= system wide on non-NUMA system]
+   4   search nodes in a chunk of node [on NUMA system]
+   5   search system wide [on NUMA system]
+====== ===========================================================
+
+Not all levels can be present and values can change depending on the
+system architecture and kernel configuration. Check
+/sys/kernel/debug/sched/domains/cpu*/domain*/ for system-specific
+details.
+
+The system default is architecture dependent.  The system default
+can be changed using the relax_domain_level= boot parameter.
+
+This file is per-cpuset and affect the sched domain where the cpuset
+belongs to.  Therefore if the flag 'cpuset.sched_load_balance' of a cpuset
+is disabled, then 'cpuset.sched_relax_domain_level' have no effect since
+there is no sched domain belonging the cpuset.
+
+If multiple cpusets are overlapping and hence they form a single sched
+domain, the largest value among those is used.  Be careful, if one
+requests 0 and others are -1 then 0 is used.
+
+Note that modifying this file will have both good and bad effects,
+and whether it is acceptable or not depends on your situation.
+Don't modify this file if you are not sure.
+
+If your situation is:
+
+ - The migration costs between each cpu can be assumed considerably
+   small(for you) due to your special application's behavior or
+   special hardware support for CPU cache etc.
+ - The searching cost doesn't have impact(for you) or you can make
+   the searching cost enough small by managing cpuset to compact etc.
+ - The latency is required even it sacrifices cache hit rate etc.
+   then increasing 'sched_relax_domain_level' would benefit you.
+
+
+1.9 How do I use cpusets ?
+--------------------------
+
+In order to minimize the impact of cpusets on critical kernel
+code, such as the scheduler, and due to the fact that the kernel
+does not support one task updating the memory placement of another
+task directly, the impact on a task of changing its cpuset CPU
+or Memory Node placement, or of changing to which cpuset a task
+is attached, is subtle.
+
+If a cpuset has its Memory Nodes modified, then for each task attached
+to that cpuset, the next time that the kernel attempts to allocate
+a page of memory for that task, the kernel will notice the change
+in the task's cpuset, and update its per-task memory placement to
+remain within the new cpusets memory placement.  If the task was using
+mempolicy MPOL_BIND, and the nodes to which it was bound overlap with
+its new cpuset, then the task will continue to use whatever subset
+of MPOL_BIND nodes are still allowed in the new cpuset.  If the task
+was using MPOL_BIND and now none of its MPOL_BIND nodes are allowed
+in the new cpuset, then the task will be essentially treated as if it
+was MPOL_BIND bound to the new cpuset (even though its NUMA placement,
+as queried by get_mempolicy(), doesn't change).  If a task is moved
+from one cpuset to another, then the kernel will adjust the task's
+memory placement, as above, the next time that the kernel attempts
+to allocate a page of memory for that task.
+
+If a cpuset has its 'cpuset.cpus' modified, then each task in that cpuset
+will have its allowed CPU placement changed immediately.  Similarly,
+if a task's pid is written to another cpuset's 'tasks' file, then its
+allowed CPU placement is changed immediately.  If such a task had been
+bound to some subset of its cpuset using the sched_setaffinity() call,
+the task will be allowed to run on any CPU allowed in its new cpuset,
+negating the effect of the prior sched_setaffinity() call.
+
+In summary, the memory placement of a task whose cpuset is changed is
+updated by the kernel, on the next allocation of a page for that task,
+and the processor placement is updated immediately.
+
+Normally, once a page is allocated (given a physical page
+of main memory) then that page stays on whatever node it
+was allocated, so long as it remains allocated, even if the
+cpusets memory placement policy 'cpuset.mems' subsequently changes.
+If the cpuset flag file 'cpuset.memory_migrate' is set true, then when
+tasks are attached to that cpuset, any pages that task had
+allocated to it on nodes in its previous cpuset are migrated
+to the task's new cpuset. The relative placement of the page within
+the cpuset is preserved during these migration operations if possible.
+For example if the page was on the second valid node of the prior cpuset
+then the page will be placed on the second valid node of the new cpuset.
+
+Also if 'cpuset.memory_migrate' is set true, then if that cpuset's
+'cpuset.mems' file is modified, pages allocated to tasks in that
+cpuset, that were on nodes in the previous setting of 'cpuset.mems',
+will be moved to nodes in the new setting of 'mems.'
+Pages that were not in the task's prior cpuset, or in the cpuset's
+prior 'cpuset.mems' setting, will not be moved.
+
+There is an exception to the above.  If hotplug functionality is used
+to remove all the CPUs that are currently assigned to a cpuset,
+then all the tasks in that cpuset will be moved to the nearest ancestor
+with non-empty cpus.  But the moving of some (or all) tasks might fail if
+cpuset is bound with another cgroup subsystem which has some restrictions
+on task attaching.  In this failing case, those tasks will stay
+in the original cpuset, and the kernel will automatically update
+their cpus_allowed to allow all online CPUs.  When memory hotplug
+functionality for removing Memory Nodes is available, a similar exception
+is expected to apply there as well.  In general, the kernel prefers to
+violate cpuset placement, over starving a task that has had all
+its allowed CPUs or Memory Nodes taken offline.
+
+There is a second exception to the above.  GFP_ATOMIC requests are
+kernel internal allocations that must be satisfied, immediately.
+The kernel may drop some request, in rare cases even panic, if a
+GFP_ATOMIC alloc fails.  If the request cannot be satisfied within
+the current task's cpuset, then we relax the cpuset, and look for
+memory anywhere we can find it.  It's better to violate the cpuset
+than stress the kernel.
+
+To start a new job that is to be contained within a cpuset, the steps are:
+
+ 1) mkdir /sys/fs/cgroup/cpuset
+ 2) mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset
+ 3) Create the new cpuset by doing mkdir's and write's (or echo's) in
+    the /sys/fs/cgroup/cpuset virtual file system.
+ 4) Start a task that will be the "founding father" of the new job.
+ 5) Attach that task to the new cpuset by writing its pid to the
+    /sys/fs/cgroup/cpuset tasks file for that cpuset.
+ 6) fork, exec or clone the job tasks from this founding father task.
+
+For example, the following sequence of commands will setup a cpuset
+named "Charlie", containing just CPUs 2 and 3, and Memory Node 1,
+and then start a subshell 'sh' in that cpuset::
+
+  mount -t cgroup -ocpuset cpuset /sys/fs/cgroup/cpuset
+  cd /sys/fs/cgroup/cpuset
+  mkdir Charlie
+  cd Charlie
+  /bin/echo 2-3 > cpuset.cpus
+  /bin/echo 1 > cpuset.mems
+  /bin/echo $$ > tasks
+  sh
+  # The subshell 'sh' is now running in cpuset Charlie
+  # The next line should display '/Charlie'
+  cat /proc/self/cpuset
+
+There are ways to query or modify cpusets:
+
+ - via the cpuset file system directly, using the various cd, mkdir, echo,
+   cat, rmdir commands from the shell, or their equivalent from C.
+ - via the C library libcpuset.
+ - via the C library libcgroup.
+   (https://github.com/libcgroup/libcgroup/)
+ - via the python application cset.
+   (http://code.google.com/p/cpuset/)
+
+The sched_setaffinity calls can also be done at the shell prompt using
+SGI's runon or Robert Love's taskset.  The mbind and set_mempolicy
+calls can be done at the shell prompt using the numactl command
+(part of Andi Kleen's numa package).
+
+2. Usage Examples and Syntax
+============================
+
+2.1 Basic Usage
+---------------
+
+Creating, modifying, using the cpusets can be done through the cpuset
+virtual filesystem.
+
+To mount it, type:
+# mount -t cgroup -o cpuset cpuset /sys/fs/cgroup/cpuset
+
+Then under /sys/fs/cgroup/cpuset you can find a tree that corresponds to the
+tree of the cpusets in the system. For instance, /sys/fs/cgroup/cpuset
+is the cpuset that holds the whole system.
+
+If you want to create a new cpuset under /sys/fs/cgroup/cpuset::
+
+  # cd /sys/fs/cgroup/cpuset
+  # mkdir my_cpuset
+
+Now you want to do something with this cpuset::
+
+  # cd my_cpuset
+
+In this directory you can find several files::
+
+  # ls
+  cgroup.clone_children  cpuset.memory_pressure
+  cgroup.event_control   cpuset.memory_spread_page
+  cgroup.procs           cpuset.memory_spread_slab
+  cpuset.cpu_exclusive   cpuset.mems
+  cpuset.cpus            cpuset.sched_load_balance
+  cpuset.mem_exclusive   cpuset.sched_relax_domain_level
+  cpuset.mem_hardwall    notify_on_release
+  cpuset.memory_migrate  tasks
+
+Reading them will give you information about the state of this cpuset:
+the CPUs and Memory Nodes it can use, the processes that are using
+it, its properties.  By writing to these files you can manipulate
+the cpuset.
+
+Set some flags::
+
+  # /bin/echo 1 > cpuset.cpu_exclusive
+
+Add some cpus::
+
+  # /bin/echo 0-7 > cpuset.cpus
+
+Add some mems::
+
+  # /bin/echo 0-7 > cpuset.mems
+
+Now attach your shell to this cpuset::
+
+  # /bin/echo $$ > tasks
+
+You can also create cpusets inside your cpuset by using mkdir in this
+directory::
+
+  # mkdir my_sub_cs
+
+To remove a cpuset, just use rmdir::
+
+  # rmdir my_sub_cs
+
+This will fail if the cpuset is in use (has cpusets inside, or has
+processes attached).
+
+Note that for legacy reasons, the "cpuset" filesystem exists as a
+wrapper around the cgroup filesystem.
+
+The command::
+
+  mount -t cpuset X /sys/fs/cgroup/cpuset
+
+is equivalent to::
+
+  mount -t cgroup -ocpuset,noprefix X /sys/fs/cgroup/cpuset
+  echo "/sbin/cpuset_release_agent" > /sys/fs/cgroup/cpuset/release_agent
+
+2.2 Adding/removing cpus
+------------------------
+
+This is the syntax to use when writing in the cpus or mems files
+in cpuset directories::
+
+  # /bin/echo 1-4 > cpuset.cpus		-> set cpus list to cpus 1,2,3,4
+  # /bin/echo 1,2,3,4 > cpuset.cpus	-> set cpus list to cpus 1,2,3,4
+
+To add a CPU to a cpuset, write the new list of CPUs including the
+CPU to be added. To add 6 to the above cpuset::
+
+  # /bin/echo 1-4,6 > cpuset.cpus	-> set cpus list to cpus 1,2,3,4,6
+
+Similarly to remove a CPU from a cpuset, write the new list of CPUs
+without the CPU to be removed.
+
+To remove all the CPUs::
+
+  # /bin/echo "" > cpuset.cpus		-> clear cpus list
+
+2.3 Setting flags
+-----------------
+
+The syntax is very simple::
+
+  # /bin/echo 1 > cpuset.cpu_exclusive 	-> set flag 'cpuset.cpu_exclusive'
+  # /bin/echo 0 > cpuset.cpu_exclusive 	-> unset flag 'cpuset.cpu_exclusive'
+
+2.4 Attaching processes
+-----------------------
+
+::
+
+  # /bin/echo PID > tasks
+
+Note that it is PID, not PIDs. You can only attach ONE task at a time.
+If you have several tasks to attach, you have to do it one after another::
+
+  # /bin/echo PID1 > tasks
+  # /bin/echo PID2 > tasks
+	...
+  # /bin/echo PIDn > tasks
+
+
+3. Questions
+============
+
+Q:
+   what's up with this '/bin/echo' ?
+
+A:
+   bash's builtin 'echo' command does not check calls to write() against
+   errors. If you use it in the cpuset file system, you won't be
+   able to tell whether a command succeeded or failed.
+
+Q:
+   When I attach processes, only the first of the line gets really attached !
+
+A:
+   We can only return one error code per call to write(). So you should also
+   put only ONE pid.
+
+4. Contact
+==========
+
+Web: http://www.bullopensource.org/cpuset
diff --git a/Documentation/admin-guide/cgroup-v1/devices.rst b/Documentation/admin-guide/cgroup-v1/devices.rst
new file mode 100644
index 000000000..e18867839
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/devices.rst
@@ -0,0 +1,132 @@
+===========================
+Device Whitelist Controller
+===========================
+
+1. Description
+==============
+
+Implement a cgroup to track and enforce open and mknod restrictions
+on device files.  A device cgroup associates a device access
+whitelist with each cgroup.  A whitelist entry has 4 fields.
+'type' is a (all), c (char), or b (block).  'all' means it applies
+to all types and all major and minor numbers.  Major and minor are
+either an integer or * for all.  Access is a composition of r
+(read), w (write), and m (mknod).
+
+The root device cgroup starts with rwm to 'all'.  A child device
+cgroup gets a copy of the parent.  Administrators can then remove
+devices from the whitelist or add new entries.  A child cgroup can
+never receive a device access which is denied by its parent.
+
+2. User Interface
+=================
+
+An entry is added using devices.allow, and removed using
+devices.deny.  For instance::
+
+	echo 'c 1:3 mr' > /sys/fs/cgroup/1/devices.allow
+
+allows cgroup 1 to read and mknod the device usually known as
+/dev/null.  Doing::
+
+	echo a > /sys/fs/cgroup/1/devices.deny
+
+will remove the default 'a *:* rwm' entry. Doing::
+
+	echo a > /sys/fs/cgroup/1/devices.allow
+
+will add the 'a *:* rwm' entry to the whitelist.
+
+3. Security
+===========
+
+Any task can move itself between cgroups.  This clearly won't
+suffice, but we can decide the best way to adequately restrict
+movement as people get some experience with this.  We may just want
+to require CAP_SYS_ADMIN, which at least is a separate bit from
+CAP_MKNOD.  We may want to just refuse moving to a cgroup which
+isn't a descendant of the current one.  Or we may want to use
+CAP_MAC_ADMIN, since we really are trying to lock down root.
+
+CAP_SYS_ADMIN is needed to modify the whitelist or move another
+task to a new cgroup.  (Again we'll probably want to change that).
+
+A cgroup may not be granted more permissions than the cgroup's
+parent has.
+
+4. Hierarchy
+============
+
+device cgroups maintain hierarchy by making sure a cgroup never has more
+access permissions than its parent.  Every time an entry is written to
+a cgroup's devices.deny file, all its children will have that entry removed
+from their whitelist and all the locally set whitelist entries will be
+re-evaluated.  In case one of the locally set whitelist entries would provide
+more access than the cgroup's parent, it'll be removed from the whitelist.
+
+Example::
+
+      A
+     / \
+        B
+
+    group        behavior	exceptions
+    A            allow		"b 8:* rwm", "c 116:1 rw"
+    B            deny		"c 1:3 rwm", "c 116:2 rwm", "b 3:* rwm"
+
+If a device is denied in group A::
+
+	# echo "c 116:* r" > A/devices.deny
+
+it'll propagate down and after revalidating B's entries, the whitelist entry
+"c 116:2 rwm" will be removed::
+
+    group        whitelist entries                        denied devices
+    A            all                                      "b 8:* rwm", "c 116:* rw"
+    B            "c 1:3 rwm", "b 3:* rwm"                 all the rest
+
+In case parent's exceptions change and local exceptions are not allowed
+anymore, they'll be deleted.
+
+Notice that new whitelist entries will not be propagated::
+
+      A
+     / \
+        B
+
+    group        whitelist entries                        denied devices
+    A            "c 1:3 rwm", "c 1:5 r"                   all the rest
+    B            "c 1:3 rwm", "c 1:5 r"                   all the rest
+
+when adding ``c *:3 rwm``::
+
+	# echo "c *:3 rwm" >A/devices.allow
+
+the result::
+
+    group        whitelist entries                        denied devices
+    A            "c *:3 rwm", "c 1:5 r"                   all the rest
+    B            "c 1:3 rwm", "c 1:5 r"                   all the rest
+
+but now it'll be possible to add new entries to B::
+
+	# echo "c 2:3 rwm" >B/devices.allow
+	# echo "c 50:3 r" >B/devices.allow
+
+or even::
+
+	# echo "c *:3 rwm" >B/devices.allow
+
+Allowing or denying all by writing 'a' to devices.allow or devices.deny will
+not be possible once the device cgroups has children.
+
+4.1 Hierarchy (internal implementation)
+---------------------------------------
+
+device cgroups is implemented internally using a behavior (ALLOW, DENY) and a
+list of exceptions.  The internal state is controlled using the same user
+interface to preserve compatibility with the previous whitelist-only
+implementation.  Removal or addition of exceptions that will reduce the access
+to devices will be propagated down the hierarchy.
+For every propagated exception, the effective rules will be re-evaluated based
+on current parent's access rules.
diff --git a/Documentation/admin-guide/cgroup-v1/freezer-subsystem.rst b/Documentation/admin-guide/cgroup-v1/freezer-subsystem.rst
new file mode 100644
index 000000000..a964aff37
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/freezer-subsystem.rst
@@ -0,0 +1,131 @@
+==============
+Cgroup Freezer
+==============
+
+The cgroup freezer is useful to batch job management system which start
+and stop sets of tasks in order to schedule the resources of a machine
+according to the desires of a system administrator. This sort of program
+is often used on HPC clusters to schedule access to the cluster as a
+whole. The cgroup freezer uses cgroups to describe the set of tasks to
+be started/stopped by the batch job management system. It also provides
+a means to start and stop the tasks composing the job.
+
+The cgroup freezer will also be useful for checkpointing running groups
+of tasks. The freezer allows the checkpoint code to obtain a consistent
+image of the tasks by attempting to force the tasks in a cgroup into a
+quiescent state. Once the tasks are quiescent another task can
+walk /proc or invoke a kernel interface to gather information about the
+quiesced tasks. Checkpointed tasks can be restarted later should a
+recoverable error occur. This also allows the checkpointed tasks to be
+migrated between nodes in a cluster by copying the gathered information
+to another node and restarting the tasks there.
+
+Sequences of SIGSTOP and SIGCONT are not always sufficient for stopping
+and resuming tasks in userspace. Both of these signals are observable
+from within the tasks we wish to freeze. While SIGSTOP cannot be caught,
+blocked, or ignored it can be seen by waiting or ptracing parent tasks.
+SIGCONT is especially unsuitable since it can be caught by the task. Any
+programs designed to watch for SIGSTOP and SIGCONT could be broken by
+attempting to use SIGSTOP and SIGCONT to stop and resume tasks. We can
+demonstrate this problem using nested bash shells::
+
+	$ echo $$
+	16644
+	$ bash
+	$ echo $$
+	16690
+
+	From a second, unrelated bash shell:
+	$ kill -SIGSTOP 16690
+	$ kill -SIGCONT 16690
+
+	<at this point 16690 exits and causes 16644 to exit too>
+
+This happens because bash can observe both signals and choose how it
+responds to them.
+
+Another example of a program which catches and responds to these
+signals is gdb. In fact any program designed to use ptrace is likely to
+have a problem with this method of stopping and resuming tasks.
+
+In contrast, the cgroup freezer uses the kernel freezer code to
+prevent the freeze/unfreeze cycle from becoming visible to the tasks
+being frozen. This allows the bash example above and gdb to run as
+expected.
+
+The cgroup freezer is hierarchical. Freezing a cgroup freezes all
+tasks belonging to the cgroup and all its descendant cgroups. Each
+cgroup has its own state (self-state) and the state inherited from the
+parent (parent-state). Iff both states are THAWED, the cgroup is
+THAWED.
+
+The following cgroupfs files are created by cgroup freezer.
+
+* freezer.state: Read-write.
+
+  When read, returns the effective state of the cgroup - "THAWED",
+  "FREEZING" or "FROZEN". This is the combined self and parent-states.
+  If any is freezing, the cgroup is freezing (FREEZING or FROZEN).
+
+  FREEZING cgroup transitions into FROZEN state when all tasks
+  belonging to the cgroup and its descendants become frozen. Note that
+  a cgroup reverts to FREEZING from FROZEN after a new task is added
+  to the cgroup or one of its descendant cgroups until the new task is
+  frozen.
+
+  When written, sets the self-state of the cgroup. Two values are
+  allowed - "FROZEN" and "THAWED". If FROZEN is written, the cgroup,
+  if not already freezing, enters FREEZING state along with all its
+  descendant cgroups.
+
+  If THAWED is written, the self-state of the cgroup is changed to
+  THAWED.  Note that the effective state may not change to THAWED if
+  the parent-state is still freezing. If a cgroup's effective state
+  becomes THAWED, all its descendants which are freezing because of
+  the cgroup also leave the freezing state.
+
+* freezer.self_freezing: Read only.
+
+  Shows the self-state. 0 if the self-state is THAWED; otherwise, 1.
+  This value is 1 iff the last write to freezer.state was "FROZEN".
+
+* freezer.parent_freezing: Read only.
+
+  Shows the parent-state.  0 if none of the cgroup's ancestors is
+  frozen; otherwise, 1.
+
+The root cgroup is non-freezable and the above interface files don't
+exist.
+
+* Examples of usage::
+
+   # mkdir /sys/fs/cgroup/freezer
+   # mount -t cgroup -ofreezer freezer /sys/fs/cgroup/freezer
+   # mkdir /sys/fs/cgroup/freezer/0
+   # echo $some_pid > /sys/fs/cgroup/freezer/0/tasks
+
+to get status of the freezer subsystem::
+
+   # cat /sys/fs/cgroup/freezer/0/freezer.state
+   THAWED
+
+to freeze all tasks in the container::
+
+   # echo FROZEN > /sys/fs/cgroup/freezer/0/freezer.state
+   # cat /sys/fs/cgroup/freezer/0/freezer.state
+   FREEZING
+   # cat /sys/fs/cgroup/freezer/0/freezer.state
+   FROZEN
+
+to unfreeze all tasks in the container::
+
+   # echo THAWED > /sys/fs/cgroup/freezer/0/freezer.state
+   # cat /sys/fs/cgroup/freezer/0/freezer.state
+   THAWED
+
+This is the basic mechanism which should do the right thing for user space task
+in a simple scenario.
+
+This freezer implementation is affected by shortcomings (see commit
+76f969e8948d8 ("cgroup: cgroup v2 freezer")) and cgroup v2 freezer is
+recommended.
diff --git a/Documentation/admin-guide/cgroup-v1/hugetlb.rst b/Documentation/admin-guide/cgroup-v1/hugetlb.rst
new file mode 100644
index 000000000..b5f3873b7
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/hugetlb.rst
@@ -0,0 +1,139 @@
+==================
+HugeTLB Controller
+==================
+
+HugeTLB controller can be created by first mounting the cgroup filesystem.
+
+# mount -t cgroup -o hugetlb none /sys/fs/cgroup
+
+With the above step, the initial or the parent HugeTLB group becomes
+visible at /sys/fs/cgroup. At bootup, this group includes all the tasks in
+the system. /sys/fs/cgroup/tasks lists the tasks in this cgroup.
+
+New groups can be created under the parent group /sys/fs/cgroup::
+
+  # cd /sys/fs/cgroup
+  # mkdir g1
+  # echo $$ > g1/tasks
+
+The above steps create a new group g1 and move the current shell
+process (bash) into it.
+
+Brief summary of control files::
+
+ hugetlb.<hugepagesize>.rsvd.limit_in_bytes            # set/show limit of "hugepagesize" hugetlb reservations
+ hugetlb.<hugepagesize>.rsvd.max_usage_in_bytes        # show max "hugepagesize" hugetlb reservations and no-reserve faults
+ hugetlb.<hugepagesize>.rsvd.usage_in_bytes            # show current reservations and no-reserve faults for "hugepagesize" hugetlb
+ hugetlb.<hugepagesize>.rsvd.failcnt                   # show the number of allocation failure due to HugeTLB reservation limit
+ hugetlb.<hugepagesize>.limit_in_bytes                 # set/show limit of "hugepagesize" hugetlb faults
+ hugetlb.<hugepagesize>.max_usage_in_bytes             # show max "hugepagesize" hugetlb  usage recorded
+ hugetlb.<hugepagesize>.usage_in_bytes                 # show current usage for "hugepagesize" hugetlb
+ hugetlb.<hugepagesize>.failcnt                        # show the number of allocation failure due to HugeTLB usage limit
+ hugetlb.<hugepagesize>.numa_stat                      # show the numa information of the hugetlb memory charged to this cgroup
+
+For a system supporting three hugepage sizes (64k, 32M and 1G), the control
+files include::
+
+  hugetlb.1GB.limit_in_bytes
+  hugetlb.1GB.max_usage_in_bytes
+  hugetlb.1GB.numa_stat
+  hugetlb.1GB.usage_in_bytes
+  hugetlb.1GB.failcnt
+  hugetlb.1GB.rsvd.limit_in_bytes
+  hugetlb.1GB.rsvd.max_usage_in_bytes
+  hugetlb.1GB.rsvd.usage_in_bytes
+  hugetlb.1GB.rsvd.failcnt
+  hugetlb.64KB.limit_in_bytes
+  hugetlb.64KB.max_usage_in_bytes
+  hugetlb.64KB.numa_stat
+  hugetlb.64KB.usage_in_bytes
+  hugetlb.64KB.failcnt
+  hugetlb.64KB.rsvd.limit_in_bytes
+  hugetlb.64KB.rsvd.max_usage_in_bytes
+  hugetlb.64KB.rsvd.usage_in_bytes
+  hugetlb.64KB.rsvd.failcnt
+  hugetlb.32MB.limit_in_bytes
+  hugetlb.32MB.max_usage_in_bytes
+  hugetlb.32MB.numa_stat
+  hugetlb.32MB.usage_in_bytes
+  hugetlb.32MB.failcnt
+  hugetlb.32MB.rsvd.limit_in_bytes
+  hugetlb.32MB.rsvd.max_usage_in_bytes
+  hugetlb.32MB.rsvd.usage_in_bytes
+  hugetlb.32MB.rsvd.failcnt
+
+
+1. Page fault accounting
+
+::
+
+  hugetlb.<hugepagesize>.limit_in_bytes
+  hugetlb.<hugepagesize>.max_usage_in_bytes
+  hugetlb.<hugepagesize>.usage_in_bytes
+  hugetlb.<hugepagesize>.failcnt
+
+The HugeTLB controller allows users to limit the HugeTLB usage (page fault) per
+control group and enforces the limit during page fault. Since HugeTLB
+doesn't support page reclaim, enforcing the limit at page fault time implies
+that, the application will get SIGBUS signal if it tries to fault in HugeTLB
+pages beyond its limit. Therefore the application needs to know exactly how many
+HugeTLB pages it uses beforehand, and the sysadmin needs to make sure that
+there are enough available on the machine for all the users to avoid processes
+getting SIGBUS.
+
+
+2. Reservation accounting
+
+::
+
+  hugetlb.<hugepagesize>.rsvd.limit_in_bytes
+  hugetlb.<hugepagesize>.rsvd.max_usage_in_bytes
+  hugetlb.<hugepagesize>.rsvd.usage_in_bytes
+  hugetlb.<hugepagesize>.rsvd.failcnt
+
+The HugeTLB controller allows limiting the HugeTLB reservations per control
+group and enforces the controller limit at reservation time and at the fault of
+HugeTLB memory for which no reservation exists. Since reservation limits are
+enforced at reservation time (on mmap or shget), reservation limits never cause
+the application to get SIGBUS signal if the memory was reserved beforehand. For
+MAP_NORESERVE allocations, the reservation limit behaves the same as the fault
+limit, enforcing memory usage at fault time and causing the application to
+receive a SIGBUS if it's crossing its limit.
+
+Reservation limits are superior to page fault limits described above, since
+reservation limits are enforced at reservation time (on mmap or shget), and
+never cause the application to get SIGBUS signal if the memory was reserved
+beforehand. This allows for easier fallback to alternatives such as
+non-HugeTLB memory for example. In the case of page fault accounting, it's very
+hard to avoid processes getting SIGBUS since the sysadmin needs to precisely know
+the HugeTLB usage of all the tasks in the system and make sure there are enough
+pages to satisfy all requests. Avoiding tasks getting SIGBUS on overcommitted
+systems is practically impossible with page fault accounting.
+
+
+3. Caveats with shared memory
+
+For shared HugeTLB memory, both HugeTLB reservation and page faults are charged
+to the first task that causes the memory to be reserved or faulted, and all
+subsequent uses of this reserved or faulted memory is done without charging.
+
+Shared HugeTLB memory is only uncharged when it is unreserved or deallocated.
+This is usually when the HugeTLB file is deleted, and not when the task that
+caused the reservation or fault has exited.
+
+
+4. Caveats with HugeTLB cgroup offline.
+
+When a HugeTLB cgroup goes offline with some reservations or faults still
+charged to it, the behavior is as follows:
+
+- The fault charges are charged to the parent HugeTLB cgroup (reparented),
+- the reservation charges remain on the offline HugeTLB cgroup.
+
+This means that if a HugeTLB cgroup gets offlined while there is still HugeTLB
+reservations charged to it, that cgroup persists as a zombie until all HugeTLB
+reservations are uncharged. HugeTLB reservations behave in this manner to match
+the memory controller whose cgroups also persist as zombie until all charged
+memory is uncharged. Also, the tracking of HugeTLB reservations is a bit more
+complex compared to the tracking of HugeTLB faults, so it is significantly
+harder to reparent reservations at offline time.
diff --git a/Documentation/admin-guide/cgroup-v1/index.rst b/Documentation/admin-guide/cgroup-v1/index.rst
new file mode 100644
index 000000000..14897a8d3
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/index.rst
@@ -0,0 +1,24 @@
+.. _cgroup-v1:
+
+========================
+Control Groups version 1
+========================
+
+.. toctree::
+    :maxdepth: 1
+
+    cgroups
+
+    blkio-controller
+    cpuacct
+    cpusets
+    devices
+    freezer-subsystem
+    hugetlb
+    memcg_test
+    memory
+    misc
+    net_cls
+    net_prio
+    pids
+    rdma
diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
new file mode 100644
index 000000000..d9951c319
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
@@ -0,0 +1,342 @@
+=====================================================
+Memory Resource Controller(Memcg) Implementation Memo
+=====================================================
+
+Last Updated: 2010/2
+
+Base Kernel Version: based on 2.6.33-rc7-mm(candidate for 34).
+
+Because VM is getting complex (one of reasons is memcg...), memcg's behavior
+is complex. This is a document for memcg's internal behavior.
+Please note that implementation details can be changed.
+
+(*) Topics on API should be in Documentation/admin-guide/cgroup-v1/memory.rst
+
+0. How to record usage ?
+========================
+
+   2 objects are used.
+
+   page_cgroup ....an object per page.
+
+	Allocated at boot or memory hotplug. Freed at memory hot removal.
+
+   swap_cgroup ... an entry per swp_entry.
+
+	Allocated at swapon(). Freed at swapoff().
+
+   The page_cgroup has USED bit and double count against a page_cgroup never
+   occurs. swap_cgroup is used only when a charged page is swapped-out.
+
+1. Charge
+=========
+
+   a page/swp_entry may be charged (usage += PAGE_SIZE) at
+
+	mem_cgroup_try_charge()
+
+2. Uncharge
+===========
+
+  a page/swp_entry may be uncharged (usage -= PAGE_SIZE) by
+
+	mem_cgroup_uncharge()
+	  Called when a page's refcount goes down to 0.
+
+	mem_cgroup_uncharge_swap()
+	  Called when swp_entry's refcnt goes down to 0. A charge against swap
+	  disappears.
+
+3. charge-commit
+=======================
+
+	Memcg pages are charged in two steps:
+
+		- mem_cgroup_try_charge()
+		- commit_charge()
+
+	At try_charge(), there are no flags to say "this page is charged".
+	at this point, usage += PAGE_SIZE.
+
+	At commit(), the page is associated with the memcg.
+
+Under below explanation, we assume CONFIG_SWAP=y.
+
+4. Anonymous
+============
+
+	Anonymous page is newly allocated at
+		  - page fault into MAP_ANONYMOUS mapping.
+		  - Copy-On-Write.
+
+	4.1 Swap-in.
+	At swap-in, the page is taken from swap-cache. There are 2 cases.
+
+	(a) If the SwapCache is newly allocated and read, it has no charges.
+	(b) If the SwapCache has been mapped by processes, it has been
+	    charged already.
+
+	4.2 Swap-out.
+	At swap-out, typical state transition is below.
+
+	(a) add to swap cache. (marked as SwapCache)
+	    swp_entry's refcnt += 1.
+	(b) fully unmapped.
+	    swp_entry's refcnt += # of ptes.
+	(c) write back to swap.
+	(d) delete from swap cache. (remove from SwapCache)
+	    swp_entry's refcnt -= 1.
+
+
+	Finally, at task exit,
+	(e) zap_pte() is called and swp_entry's refcnt -=1 -> 0.
+
+5. Page Cache
+=============
+
+	Page Cache is charged at
+	- filemap_add_folio().
+
+	The logic is very clear. (About migration, see below)
+
+	Note:
+	  __filemap_remove_folio() is called by filemap_remove_folio()
+	  and __remove_mapping().
+
+6. Shmem(tmpfs) Page Cache
+===========================
+
+	The best way to understand shmem's page state transition is to read
+	mm/shmem.c.
+
+	But brief explanation of the behavior of memcg around shmem will be
+	helpful to understand the logic.
+
+	Shmem's page (just leaf page, not direct/indirect block) can be on
+
+		- radix-tree of shmem's inode.
+		- SwapCache.
+		- Both on radix-tree and SwapCache. This happens at swap-in
+		  and swap-out,
+
+	It's charged when...
+
+	- A new page is added to shmem's radix-tree.
+	- A swp page is read. (move a charge from swap_cgroup to page_cgroup)
+
+7. Page Migration
+=================
+
+	mem_cgroup_migrate()
+
+8. LRU
+======
+	Each memcg has its own vector of LRUs (inactive anon, active anon,
+	inactive file, active file, unevictable) of pages from each node,
+	each LRU handled under a single lru_lock for that memcg and node.
+
+9. Typical Tests.
+=================
+
+ Tests for racy cases.
+
+9.1 Small limit to memcg.
+-------------------------
+
+	When you do test to do racy case, it's good test to set memcg's limit
+	to be very small rather than GB. Many races found in the test under
+	xKB or xxMB limits.
+
+	(Memory behavior under GB and Memory behavior under MB shows very
+	different situation.)
+
+9.2 Shmem
+---------
+
+	Historically, memcg's shmem handling was poor and we saw some amount
+	of troubles here. This is because shmem is page-cache but can be
+	SwapCache. Test with shmem/tmpfs is always good test.
+
+9.3 Migration
+-------------
+
+	For NUMA, migration is an another special case. To do easy test, cpuset
+	is useful. Following is a sample script to do migration::
+
+		mount -t cgroup -o cpuset none /opt/cpuset
+
+		mkdir /opt/cpuset/01
+		echo 1 > /opt/cpuset/01/cpuset.cpus
+		echo 0 > /opt/cpuset/01/cpuset.mems
+		echo 1 > /opt/cpuset/01/cpuset.memory_migrate
+		mkdir /opt/cpuset/02
+		echo 1 > /opt/cpuset/02/cpuset.cpus
+		echo 1 > /opt/cpuset/02/cpuset.mems
+		echo 1 > /opt/cpuset/02/cpuset.memory_migrate
+
+	In above set, when you moves a task from 01 to 02, page migration to
+	node 0 to node 1 will occur. Following is a script to migrate all
+	under cpuset.::
+
+		--
+		move_task()
+		{
+		for pid in $1
+		do
+			/bin/echo $pid >$2/tasks 2>/dev/null
+			echo -n $pid
+			echo -n " "
+		done
+		echo END
+		}
+
+		G1_TASK=`cat ${G1}/tasks`
+		G2_TASK=`cat ${G2}/tasks`
+		move_task "${G1_TASK}" ${G2} &
+		--
+
+9.4 Memory hotplug
+------------------
+
+	memory hotplug test is one of good test.
+
+	to offline memory, do following::
+
+		# echo offline > /sys/devices/system/memory/memoryXXX/state
+
+	(XXX is the place of memory)
+
+	This is an easy way to test page migration, too.
+
+9.5 nested cgroups
+------------------
+
+	Use tests like the following for testing nested cgroups::
+
+		mkdir /opt/cgroup/01/child_a
+		mkdir /opt/cgroup/01/child_b
+
+		set limit to 01.
+		add limit to 01/child_b
+		run jobs under child_a and child_b
+
+	create/delete following groups at random while jobs are running::
+
+		/opt/cgroup/01/child_a/child_aa
+		/opt/cgroup/01/child_b/child_bb
+		/opt/cgroup/01/child_c
+
+	running new jobs in new group is also good.
+
+9.6 Mount with other subsystems
+-------------------------------
+
+	Mounting with other subsystems is a good test because there is a
+	race and lock dependency with other cgroup subsystems.
+
+	example::
+
+		# mount -t cgroup none /cgroup -o cpuset,memory,cpu,devices
+
+	and do task move, mkdir, rmdir etc...under this.
+
+9.7 swapoff
+-----------
+
+	Besides management of swap is one of complicated parts of memcg,
+	call path of swap-in at swapoff is not same as usual swap-in path..
+	It's worth to be tested explicitly.
+
+	For example, test like following is good:
+
+	(Shell-A)::
+
+		# mount -t cgroup none /cgroup -o memory
+		# mkdir /cgroup/test
+		# echo 40M > /cgroup/test/memory.limit_in_bytes
+		# echo 0 > /cgroup/test/tasks
+
+	Run malloc(100M) program under this. You'll see 60M of swaps.
+
+	(Shell-B)::
+
+		# move all tasks in /cgroup/test to /cgroup
+		# /sbin/swapoff -a
+		# rmdir /cgroup/test
+		# kill malloc task.
+
+	Of course, tmpfs v.s. swapoff test should be tested, too.
+
+9.8 OOM-Killer
+--------------
+
+	Out-of-memory caused by memcg's limit will kill tasks under
+	the memcg. When hierarchy is used, a task under hierarchy
+	will be killed by the kernel.
+
+	In this case, panic_on_oom shouldn't be invoked and tasks
+	in other groups shouldn't be killed.
+
+	It's not difficult to cause OOM under memcg as following.
+
+	Case A) when you can swapoff::
+
+		#swapoff -a
+		#echo 50M > /memory.limit_in_bytes
+
+	run 51M of malloc
+
+	Case B) when you use mem+swap limitation::
+
+		#echo 50M > memory.limit_in_bytes
+		#echo 50M > memory.memsw.limit_in_bytes
+
+	run 51M of malloc
+
+9.9 Move charges at task migration
+----------------------------------
+
+	Charges associated with a task can be moved along with task migration.
+
+	(Shell-A)::
+
+		#mkdir /cgroup/A
+		#echo $$ >/cgroup/A/tasks
+
+	run some programs which uses some amount of memory in /cgroup/A.
+
+	(Shell-B)::
+
+		#mkdir /cgroup/B
+		#echo 1 >/cgroup/B/memory.move_charge_at_immigrate
+		#echo "pid of the program running in group A" >/cgroup/B/tasks
+
+	You can see charges have been moved by reading ``*.usage_in_bytes`` or
+	memory.stat of both A and B.
+
+	See 8.2 of Documentation/admin-guide/cgroup-v1/memory.rst to see what value should
+	be written to move_charge_at_immigrate.
+
+9.10 Memory thresholds
+----------------------
+
+	Memory controller implements memory thresholds using cgroups notification
+	API. You can use samples/cgroup/cgroup_event_listener.c to test it.
+
+	(Shell-A) Create cgroup and run event listener::
+
+		# mkdir /cgroup/A
+		# ./cgroup_event_listener /cgroup/A/memory.usage_in_bytes 5M
+
+	(Shell-B) Add task to cgroup and try to allocate and free memory::
+
+		# echo $$ >/cgroup/A/tasks
+		# a="$(dd if=/dev/zero bs=1M count=10)"
+		# a=
+
+	You will see message from cgroup_event_listener every time you cross
+	the thresholds.
+
+	Use /cgroup/A/memory.memsw.usage_in_bytes to test memsw thresholds.
+
+	It's good idea to test root cgroup as well.
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
new file mode 100644
index 000000000..7db63c002
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -0,0 +1,963 @@
+==========================
+Memory Resource Controller
+==========================
+
+.. caution::
+      This document is hopelessly outdated and it asks for a complete
+      rewrite. It still contains a useful information so we are keeping it
+      here but make sure to check the current code if you need a deeper
+      understanding.
+
+.. note::
+      The Memory Resource Controller has generically been referred to as the
+      memory controller in this document. Do not confuse memory controller
+      used here with the memory controller that is used in hardware.
+
+.. hint::
+      When we mention a cgroup (cgroupfs's directory) with memory controller,
+      we call it "memory cgroup". When you see git-log and source code, you'll
+      see patch's title and function names tend to use "memcg".
+      In this document, we avoid using it.
+
+Benefits and Purpose of the memory controller
+=============================================
+
+The memory controller isolates the memory behaviour of a group of tasks
+from the rest of the system. The article on LWN [12]_ mentions some probable
+uses of the memory controller. The memory controller can be used to
+
+a. Isolate an application or a group of applications
+   Memory-hungry applications can be isolated and limited to a smaller
+   amount of memory.
+b. Create a cgroup with a limited amount of memory; this can be used
+   as a good alternative to booting with mem=XXXX.
+c. Virtualization solutions can control the amount of memory they want
+   to assign to a virtual machine instance.
+d. A CD/DVD burner could control the amount of memory used by the
+   rest of the system to ensure that burning does not fail due to lack
+   of available memory.
+e. There are several other use cases; find one or use the controller just
+   for fun (to learn and hack on the VM subsystem).
+
+Current Status: linux-2.6.34-mmotm(development version of 2010/April)
+
+Features:
+
+ - accounting anonymous pages, file caches, swap caches usage and limiting them.
+ - pages are linked to per-memcg LRU exclusively, and there is no global LRU.
+ - optionally, memory+swap usage can be accounted and limited.
+ - hierarchical accounting
+ - soft limit
+ - moving (recharging) account at moving a task is selectable.
+ - usage threshold notifier
+ - memory pressure notifier
+ - oom-killer disable knob and oom-notifier
+ - Root cgroup has no limit controls.
+
+ Kernel memory support is a work in progress, and the current version provides
+ basically functionality. (See :ref:`section 2.7
+ <cgroup-v1-memory-kernel-extension>`)
+
+Brief summary of control files.
+
+==================================== ==========================================
+ tasks				     attach a task(thread) and show list of
+				     threads
+ cgroup.procs			     show list of processes
+ cgroup.event_control		     an interface for event_fd()
+				     This knob is not available on CONFIG_PREEMPT_RT systems.
+ memory.usage_in_bytes		     show current usage for memory
+				     (See 5.5 for details)
+ memory.memsw.usage_in_bytes	     show current usage for memory+Swap
+				     (See 5.5 for details)
+ memory.limit_in_bytes		     set/show limit of memory usage
+ memory.memsw.limit_in_bytes	     set/show limit of memory+Swap usage
+ memory.failcnt			     show the number of memory usage hits limits
+ memory.memsw.failcnt		     show the number of memory+Swap hits limits
+ memory.max_usage_in_bytes	     show max memory usage recorded
+ memory.memsw.max_usage_in_bytes     show max memory+Swap usage recorded
+ memory.soft_limit_in_bytes	     set/show soft limit of memory usage
+				     This knob is not available on CONFIG_PREEMPT_RT systems.
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.stat			     show various statistics
+ memory.use_hierarchy		     set/show hierarchical account enabled
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.force_empty		     trigger forced page reclaim
+ memory.pressure_level		     set memory pressure notifications
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.swappiness		     set/show swappiness parameter of vmscan
+				     (See sysctl's vm.swappiness)
+				     Per memcg knob does not exist in cgroup v2.
+ memory.move_charge_at_immigrate     This knob is deprecated.
+ memory.oom_control		     set/show oom controls.
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.numa_stat		     show the number of memory usage per numa
+				     node
+ memory.kmem.limit_in_bytes          Deprecated knob to set and read the kernel
+                                     memory hard limit. Kernel hard limit is not
+                                     supported since 5.16. Writing any value to
+                                     do file will not have any effect same as if
+                                     nokmem kernel parameter was specified.
+                                     Kernel memory is still charged and reported
+                                     by memory.kmem.usage_in_bytes.
+ memory.kmem.usage_in_bytes          show current kernel memory allocation
+ memory.kmem.failcnt                 show the number of kernel memory usage
+				     hits limits
+ memory.kmem.max_usage_in_bytes      show max kernel memory usage recorded
+
+ memory.kmem.tcp.limit_in_bytes      set/show hard limit for tcp buf memory
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.kmem.tcp.usage_in_bytes      show current tcp buf memory allocation
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.kmem.tcp.failcnt             show the number of tcp buf memory usage
+				     hits limits
+                                     This knob is deprecated and shouldn't be
+                                     used.
+ memory.kmem.tcp.max_usage_in_bytes  show max tcp buf memory usage recorded
+                                     This knob is deprecated and shouldn't be
+                                     used.
+==================================== ==========================================
+
+1. History
+==========
+
+The memory controller has a long history. A request for comments for the memory
+controller was posted by Balbir Singh [1]_. At the time the RFC was posted
+there were several implementations for memory control. The goal of the
+RFC was to build consensus and agreement for the minimal features required
+for memory control. The first RSS controller was posted by Balbir Singh [2]_
+in Feb 2007. Pavel Emelianov [3]_ [4]_ [5]_ has since posted three versions
+of the RSS controller. At OLS, at the resource management BoF, everyone
+suggested that we handle both page cache and RSS together. Another request was
+raised to allow user space handling of OOM. The current memory controller is
+at version 6; it combines both mapped (RSS) and unmapped Page
+Cache Control [11]_.
+
+2. Memory Control
+=================
+
+Memory is a unique resource in the sense that it is present in a limited
+amount. If a task requires a lot of CPU processing, the task can spread
+its processing over a period of hours, days, months or years, but with
+memory, the same physical memory needs to be reused to accomplish the task.
+
+The memory controller implementation has been divided into phases. These
+are:
+
+1. Memory controller
+2. mlock(2) controller
+3. Kernel user memory accounting and slab control
+4. user mappings length controller
+
+The memory controller is the first controller developed.
+
+2.1. Design
+-----------
+
+The core of the design is a counter called the page_counter. The
+page_counter tracks the current memory usage and limit of the group of
+processes associated with the controller. Each cgroup has a memory controller
+specific data structure (mem_cgroup) associated with it.
+
+2.2. Accounting
+---------------
+
+.. code-block::
+   :caption: Figure 1: Hierarchy of Accounting
+
+		+--------------------+
+		|  mem_cgroup        |
+		|  (page_counter)    |
+		+--------------------+
+		 /            ^      \
+		/             |       \
+           +---------------+  |        +---------------+
+           | mm_struct     |  |....    | mm_struct     |
+           |               |  |        |               |
+           +---------------+  |        +---------------+
+                              |
+                              + --------------+
+                                              |
+           +---------------+           +------+--------+
+           | page          +---------->  page_cgroup|
+           |               |           |               |
+           +---------------+           +---------------+
+
+
+
+Figure 1 shows the important aspects of the controller
+
+1. Accounting happens per cgroup
+2. Each mm_struct knows about which cgroup it belongs to
+3. Each page has a pointer to the page_cgroup, which in turn knows the
+   cgroup it belongs to
+
+The accounting is done as follows: mem_cgroup_charge_common() is invoked to
+set up the necessary data structures and check if the cgroup that is being
+charged is over its limit. If it is, then reclaim is invoked on the cgroup.
+More details can be found in the reclaim section of this document.
+If everything goes well, a page meta-data-structure called page_cgroup is
+updated. page_cgroup has its own LRU on cgroup.
+(*) page_cgroup structure is allocated at boot/memory-hotplug time.
+
+2.2.1 Accounting details
+------------------------
+
+All mapped anon pages (RSS) and cache pages (Page Cache) are accounted.
+Some pages which are never reclaimable and will not be on the LRU
+are not accounted. We just account pages under usual VM management.
+
+RSS pages are accounted at page_fault unless they've already been accounted
+for earlier. A file page will be accounted for as Page Cache when it's
+inserted into inode (xarray). While it's mapped into the page tables of
+processes, duplicate accounting is carefully avoided.
+
+An RSS page is unaccounted when it's fully unmapped. A PageCache page is
+unaccounted when it's removed from xarray. Even if RSS pages are fully
+unmapped (by kswapd), they may exist as SwapCache in the system until they
+are really freed. Such SwapCaches are also accounted.
+A swapped-in page is accounted after adding into swapcache.
+
+Note: The kernel does swapin-readahead and reads multiple swaps at once.
+Since page's memcg recorded into swap whatever memsw enabled, the page will
+be accounted after swapin.
+
+At page migration, accounting information is kept.
+
+Note: we just account pages-on-LRU because our purpose is to control amount
+of used pages; not-on-LRU pages tend to be out-of-control from VM view.
+
+2.3 Shared Page Accounting
+--------------------------
+
+Shared pages are accounted on the basis of the first touch approach. The
+cgroup that first touches a page is accounted for the page. The principle
+behind this approach is that a cgroup that aggressively uses a shared
+page will eventually get charged for it (once it is uncharged from
+the cgroup that brought it in -- this will happen on memory pressure).
+
+2.4 Swap Extension
+--------------------------------------
+
+Swap usage is always recorded for each of cgroup. Swap Extension allows you to
+read and limit it.
+
+When CONFIG_SWAP is enabled, following files are added.
+
+ - memory.memsw.usage_in_bytes.
+ - memory.memsw.limit_in_bytes.
+
+memsw means memory+swap. Usage of memory+swap is limited by
+memsw.limit_in_bytes.
+
+Example: Assume a system with 4G of swap. A task which allocates 6G of memory
+(by mistake) under 2G memory limitation will use all swap.
+In this case, setting memsw.limit_in_bytes=3G will prevent bad use of swap.
+By using the memsw limit, you can avoid system OOM which can be caused by swap
+shortage.
+
+2.4.1 why 'memory+swap' rather than swap
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The global LRU(kswapd) can swap out arbitrary pages. Swap-out means
+to move account from memory to swap...there is no change in usage of
+memory+swap. In other words, when we want to limit the usage of swap without
+affecting global LRU, memory+swap limit is better than just limiting swap from
+an OS point of view.
+
+2.4.2. What happens when a cgroup hits memory.memsw.limit_in_bytes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When a cgroup hits memory.memsw.limit_in_bytes, it's useless to do swap-out
+in this cgroup. Then, swap-out will not be done by cgroup routine and file
+caches are dropped. But as mentioned above, global LRU can do swapout memory
+from it for sanity of the system's memory management state. You can't forbid
+it by cgroup.
+
+2.5 Reclaim
+-----------
+
+Each cgroup maintains a per cgroup LRU which has the same structure as
+global VM. When a cgroup goes over its limit, we first try
+to reclaim memory from the cgroup so as to make space for the new
+pages that the cgroup has touched. If the reclaim is unsuccessful,
+an OOM routine is invoked to select and kill the bulkiest task in the
+cgroup. (See :ref:`10. OOM Control <cgroup-v1-memory-oom-control>` below.)
+
+The reclaim algorithm has not been modified for cgroups, except that
+pages that are selected for reclaiming come from the per-cgroup LRU
+list.
+
+.. note::
+   Reclaim does not work for the root cgroup, since we cannot set any
+   limits on the root cgroup.
+
+.. note::
+   When panic_on_oom is set to "2", the whole system will panic.
+
+When oom event notifier is registered, event will be delivered.
+(See :ref:`oom_control <cgroup-v1-memory-oom-control>` section)
+
+2.6 Locking
+-----------
+
+Lock order is as follows::
+
+  folio_lock
+    mm->page_table_lock or split pte_lock
+      mapping->i_pages lock
+        lruvec->lru_lock.
+
+Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by
+lruvec->lru_lock; the folio LRU flag is cleared before
+isolating a page from its LRU under lruvec->lru_lock.
+
+.. _cgroup-v1-memory-kernel-extension:
+
+2.7 Kernel Memory Extension
+-----------------------------------------------
+
+With the Kernel memory extension, the Memory Controller is able to limit
+the amount of kernel memory used by the system. Kernel memory is fundamentally
+different than user memory, since it can't be swapped out, which makes it
+possible to DoS the system by consuming too much of this precious resource.
+
+Kernel memory accounting is enabled for all memory cgroups by default. But
+it can be disabled system-wide by passing cgroup.memory=nokmem to the kernel
+at boot time. In this case, kernel memory will not be accounted at all.
+
+Kernel memory limits are not imposed for the root cgroup. Usage for the root
+cgroup may or may not be accounted. The memory used is accumulated into
+memory.kmem.usage_in_bytes, or in a separate counter when it makes sense.
+(currently only for tcp).
+
+The main "kmem" counter is fed into the main counter, so kmem charges will
+also be visible from the user counter.
+
+Currently no soft limit is implemented for kernel memory. It is future work
+to trigger slab reclaim when those limits are reached.
+
+2.7.1 Current Kernel Memory resources accounted
+-----------------------------------------------
+
+stack pages:
+  every process consumes some stack pages. By accounting into
+  kernel memory, we prevent new processes from being created when the kernel
+  memory usage is too high.
+
+slab pages:
+  pages allocated by the SLAB or SLUB allocator are tracked. A copy
+  of each kmem_cache is created every time the cache is touched by the first time
+  from inside the memcg. The creation is done lazily, so some objects can still be
+  skipped while the cache is being created. All objects in a slab page should
+  belong to the same memcg. This only fails to hold when a task is migrated to a
+  different memcg during the page allocation by the cache.
+
+sockets memory pressure:
+  some sockets protocols have memory pressure
+  thresholds. The Memory Controller allows them to be controlled individually
+  per cgroup, instead of globally.
+
+tcp memory pressure:
+  sockets memory pressure for the tcp protocol.
+
+2.7.2 Common use cases
+----------------------
+
+Because the "kmem" counter is fed to the main user counter, kernel memory can
+never be limited completely independently of user memory. Say "U" is the user
+limit, and "K" the kernel limit. There are three possible ways limits can be
+set:
+
+U != 0, K = unlimited:
+    This is the standard memcg limitation mechanism already present before kmem
+    accounting. Kernel memory is completely ignored.
+
+U != 0, K < U:
+    Kernel memory is a subset of the user memory. This setup is useful in
+    deployments where the total amount of memory per-cgroup is overcommitted.
+    Overcommitting kernel memory limits is definitely not recommended, since the
+    box can still run out of non-reclaimable memory.
+    In this case, the admin could set up K so that the sum of all groups is
+    never greater than the total memory, and freely set U at the cost of his
+    QoS.
+
+    .. warning::
+       In the current implementation, memory reclaim will NOT be triggered for
+       a cgroup when it hits K while staying below U, which makes this setup
+       impractical.
+
+U != 0, K >= U:
+    Since kmem charges will also be fed to the user counter and reclaim will be
+    triggered for the cgroup for both kinds of memory. This setup gives the
+    admin a unified view of memory, and it is also useful for people who just
+    want to track kernel memory usage.
+
+3. User Interface
+=================
+
+To use the user interface:
+
+1. Enable CONFIG_CGROUPS and CONFIG_MEMCG options
+2. Prepare the cgroups (see :ref:`Why are cgroups needed?
+   <cgroups-why-needed>` for the background information)::
+
+	# mount -t tmpfs none /sys/fs/cgroup
+	# mkdir /sys/fs/cgroup/memory
+	# mount -t cgroup none /sys/fs/cgroup/memory -o memory
+
+3. Make the new group and move bash into it::
+
+	# mkdir /sys/fs/cgroup/memory/0
+	# echo $$ > /sys/fs/cgroup/memory/0/tasks
+
+4. Since now we're in the 0 cgroup, we can alter the memory limit::
+
+	# echo 4M > /sys/fs/cgroup/memory/0/memory.limit_in_bytes
+
+   The limit can now be queried::
+
+	# cat /sys/fs/cgroup/memory/0/memory.limit_in_bytes
+	4194304
+
+.. note::
+   We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
+   mega or gigabytes. (Here, Kilo, Mega, Giga are Kibibytes, Mebibytes,
+   Gibibytes.)
+
+.. note::
+   We can write "-1" to reset the ``*.limit_in_bytes(unlimited)``.
+
+.. note::
+   We cannot set limits on the root cgroup any more.
+
+
+We can check the usage::
+
+  # cat /sys/fs/cgroup/memory/0/memory.usage_in_bytes
+  1216512
+
+A successful write to this file does not guarantee a successful setting of
+this limit to the value written into the file. This can be due to a
+number of factors, such as rounding up to page boundaries or the total
+availability of memory on the system. The user is required to re-read
+this file after a write to guarantee the value committed by the kernel::
+
+  # echo 1 > memory.limit_in_bytes
+  # cat memory.limit_in_bytes
+  4096
+
+The memory.failcnt field gives the number of times that the cgroup limit was
+exceeded.
+
+The memory.stat file gives accounting information. Now, the number of
+caches, RSS and Active pages/Inactive pages are shown.
+
+4. Testing
+==========
+
+For testing features and implementation, see memcg_test.txt.
+
+Performance test is also important. To see pure memory controller's overhead,
+testing on tmpfs will give you good numbers of small overheads.
+Example: do kernel make on tmpfs.
+
+Page-fault scalability is also important. At measuring parallel
+page fault test, multi-process test may be better than multi-thread
+test because it has noise of shared objects/status.
+
+But the above two are testing extreme situations.
+Trying usual test under memory controller is always helpful.
+
+.. _cgroup-v1-memory-test-troubleshoot:
+
+4.1 Troubleshooting
+-------------------
+
+Sometimes a user might find that the application under a cgroup is
+terminated by the OOM killer. There are several causes for this:
+
+1. The cgroup limit is too low (just too low to do anything useful)
+2. The user is using anonymous memory and swap is turned off or too low
+
+A sync followed by echo 1 > /proc/sys/vm/drop_caches will help get rid of
+some of the pages cached in the cgroup (page cache pages).
+
+To know what happens, disabling OOM_Kill as per :ref:`"10. OOM Control"
+<cgroup-v1-memory-oom-control>` (below) and seeing what happens will be
+helpful.
+
+.. _cgroup-v1-memory-test-task-migration:
+
+4.2 Task migration
+------------------
+
+When a task migrates from one cgroup to another, its charge is not
+carried forward by default. The pages allocated from the original cgroup still
+remain charged to it, the charge is dropped when the page is freed or
+reclaimed.
+
+You can move charges of a task along with task migration.
+See :ref:`8. "Move charges at task migration" <cgroup-v1-memory-move-charges>`
+
+4.3 Removing a cgroup
+---------------------
+
+A cgroup can be removed by rmdir, but as discussed in :ref:`sections 4.1
+<cgroup-v1-memory-test-troubleshoot>` and :ref:`4.2
+<cgroup-v1-memory-test-task-migration>`, a cgroup might have some charge
+associated with it, even though all tasks have migrated away from it. (because
+we charge against pages, not against tasks.)
+
+We move the stats to parent, and no change on the charge except uncharging
+from the child.
+
+Charges recorded in swap information is not updated at removal of cgroup.
+Recorded information is discarded and a cgroup which uses swap (swapcache)
+will be charged as a new owner of it.
+
+5. Misc. interfaces
+===================
+
+5.1 force_empty
+---------------
+  memory.force_empty interface is provided to make cgroup's memory usage empty.
+  When writing anything to this::
+
+    # echo 0 > memory.force_empty
+
+  the cgroup will be reclaimed and as many pages reclaimed as possible.
+
+  The typical use case for this interface is before calling rmdir().
+  Though rmdir() offlines memcg, but the memcg may still stay there due to
+  charged file caches. Some out-of-use page caches may keep charged until
+  memory pressure happens. If you want to avoid that, force_empty will be useful.
+
+5.2 stat file
+-------------
+
+memory.stat file includes following statistics:
+
+  * per-memory cgroup local status
+
+    =============== ===============================================================
+    cache           # of bytes of page cache memory.
+    rss             # of bytes of anonymous and swap cache memory (includes
+                    transparent hugepages).
+    rss_huge        # of bytes of anonymous transparent hugepages.
+    mapped_file     # of bytes of mapped file (includes tmpfs/shmem)
+    pgpgin          # of charging events to the memory cgroup. The charging
+                    event happens each time a page is accounted as either mapped
+                    anon page(RSS) or cache page(Page Cache) to the cgroup.
+    pgpgout         # of uncharging events to the memory cgroup. The uncharging
+                    event happens each time a page is unaccounted from the
+                    cgroup.
+    swap            # of bytes of swap usage
+    swapcached      # of bytes of swap cached in memory
+    dirty           # of bytes that are waiting to get written back to the disk.
+    writeback       # of bytes of file/anon cache that are queued for syncing to
+                    disk.
+    inactive_anon   # of bytes of anonymous and swap cache memory on inactive
+                    LRU list.
+    active_anon     # of bytes of anonymous and swap cache memory on active
+                    LRU list.
+    inactive_file   # of bytes of file-backed memory and MADV_FREE anonymous
+                    memory (LazyFree pages) on inactive LRU list.
+    active_file     # of bytes of file-backed memory on active LRU list.
+    unevictable     # of bytes of memory that cannot be reclaimed (mlocked etc).
+    =============== ===============================================================
+
+  * status considering hierarchy (see memory.use_hierarchy settings):
+
+    ========================= ===================================================
+    hierarchical_memory_limit # of bytes of memory limit with regard to
+                              hierarchy
+                              under which the memory cgroup is
+    hierarchical_memsw_limit  # of bytes of memory+swap limit with regard to
+                              hierarchy under which memory cgroup is.
+
+    total_<counter>           # hierarchical version of <counter>, which in
+                              addition to the cgroup's own value includes the
+                              sum of all hierarchical children's values of
+                              <counter>, i.e. total_cache
+    ========================= ===================================================
+
+  * additional vm parameters (depends on CONFIG_DEBUG_VM):
+
+    ========================= ========================================
+    recent_rotated_anon       VM internal parameter. (see mm/vmscan.c)
+    recent_rotated_file       VM internal parameter. (see mm/vmscan.c)
+    recent_scanned_anon       VM internal parameter. (see mm/vmscan.c)
+    recent_scanned_file       VM internal parameter. (see mm/vmscan.c)
+    ========================= ========================================
+
+.. hint::
+	recent_rotated means recent frequency of LRU rotation.
+	recent_scanned means recent # of scans to LRU.
+	showing for better debug please see the code for meanings.
+
+.. note::
+	Only anonymous and swap cache memory is listed as part of 'rss' stat.
+	This should not be confused with the true 'resident set size' or the
+	amount of physical memory used by the cgroup.
+
+	'rss + mapped_file" will give you resident set size of cgroup.
+
+	Note that some kernel configurations might account complete larger
+	allocations (e.g., THP) towards 'rss' and 'mapped_file', even if
+	only some, but not all that memory is mapped.
+
+	(Note: file and shmem may be shared among other cgroups. In that case,
+	mapped_file is accounted only when the memory cgroup is owner of page
+	cache.)
+
+5.3 swappiness
+--------------
+
+Overrides /proc/sys/vm/swappiness for the particular group. The tunable
+in the root cgroup corresponds to the global swappiness setting.
+
+Please note that unlike during the global reclaim, limit reclaim
+enforces that 0 swappiness really prevents from any swapping even if
+there is a swap storage available. This might lead to memcg OOM killer
+if there are no file pages to reclaim.
+
+5.4 failcnt
+-----------
+
+A memory cgroup provides memory.failcnt and memory.memsw.failcnt files.
+This failcnt(== failure count) shows the number of times that a usage counter
+hit its limit. When a memory cgroup hits a limit, failcnt increases and
+memory under it will be reclaimed.
+
+You can reset failcnt by writing 0 to failcnt file::
+
+	# echo 0 > .../memory.failcnt
+
+5.5 usage_in_bytes
+------------------
+
+For efficiency, as other kernel components, memory cgroup uses some optimization
+to avoid unnecessary cacheline false sharing. usage_in_bytes is affected by the
+method and doesn't show 'exact' value of memory (and swap) usage, it's a fuzz
+value for efficient access. (Of course, when necessary, it's synchronized.)
+If you want to know more exact memory usage, you should use RSS+CACHE(+SWAP)
+value in memory.stat(see 5.2).
+
+5.6 numa_stat
+-------------
+
+This is similar to numa_maps but operates on a per-memcg basis.  This is
+useful for providing visibility into the numa locality information within
+an memcg since the pages are allowed to be allocated from any physical
+node.  One of the use cases is evaluating application performance by
+combining this information with the application's CPU allocation.
+
+Each memcg's numa_stat file includes "total", "file", "anon" and "unevictable"
+per-node page counts including "hierarchical_<counter>" which sums up all
+hierarchical children's values in addition to the memcg's own value.
+
+The output format of memory.numa_stat is::
+
+  total=<total pages> N0=<node 0 pages> N1=<node 1 pages> ...
+  file=<total file pages> N0=<node 0 pages> N1=<node 1 pages> ...
+  anon=<total anon pages> N0=<node 0 pages> N1=<node 1 pages> ...
+  unevictable=<total anon pages> N0=<node 0 pages> N1=<node 1 pages> ...
+  hierarchical_<counter>=<counter pages> N0=<node 0 pages> N1=<node 1 pages> ...
+
+The "total" count is sum of file + anon + unevictable.
+
+6. Hierarchy support
+====================
+
+The memory controller supports a deep hierarchy and hierarchical accounting.
+The hierarchy is created by creating the appropriate cgroups in the
+cgroup filesystem. Consider for example, the following cgroup filesystem
+hierarchy::
+
+	       root
+	     /  |   \
+            /	|    \
+	   a	b     c
+		      | \
+		      |  \
+		      d   e
+
+In the diagram above, with hierarchical accounting enabled, all memory
+usage of e, is accounted to its ancestors up until the root (i.e, c and root).
+If one of the ancestors goes over its limit, the reclaim algorithm reclaims
+from the tasks in the ancestor and the children of the ancestor.
+
+6.1 Hierarchical accounting and reclaim
+---------------------------------------
+
+Hierarchical accounting is enabled by default. Disabling the hierarchical
+accounting is deprecated. An attempt to do it will result in a failure
+and a warning printed to dmesg.
+
+For compatibility reasons writing 1 to memory.use_hierarchy will always pass::
+
+	# echo 1 > memory.use_hierarchy
+
+7. Soft limits (DEPRECATED)
+===========================
+
+THIS IS DEPRECATED!
+
+Soft limits allow for greater sharing of memory. The idea behind soft limits
+is to allow control groups to use as much of the memory as needed, provided
+
+a. There is no memory contention
+b. They do not exceed their hard limit
+
+When the system detects memory contention or low memory, control groups
+are pushed back to their soft limits. If the soft limit of each control
+group is very high, they are pushed back as much as possible to make
+sure that one control group does not starve the others of memory.
+
+Please note that soft limits is a best-effort feature; it comes with
+no guarantees, but it does its best to make sure that when memory is
+heavily contended for, memory is allocated based on the soft limit
+hints/setup. Currently soft limit based reclaim is set up such that
+it gets invoked from balance_pgdat (kswapd).
+
+7.1 Interface
+-------------
+
+Soft limits can be setup by using the following commands (in this example we
+assume a soft limit of 256 MiB)::
+
+	# echo 256M > memory.soft_limit_in_bytes
+
+If we want to change this to 1G, we can at any time use::
+
+	# echo 1G > memory.soft_limit_in_bytes
+
+.. note::
+       Soft limits take effect over a long period of time, since they involve
+       reclaiming memory for balancing between memory cgroups
+
+.. note::
+       It is recommended to set the soft limit always below the hard limit,
+       otherwise the hard limit will take precedence.
+
+.. _cgroup-v1-memory-move-charges:
+
+8. Move charges at task migration (DEPRECATED!)
+===============================================
+
+THIS IS DEPRECATED!
+
+Reading memory.move_charge_at_immigrate will always return 0 and writing
+to it will always return -EINVAL.
+
+9. Memory thresholds
+====================
+
+Memory cgroup implements memory thresholds using the cgroups notification
+API (see cgroups.txt). It allows to register multiple memory and memsw
+thresholds and gets notifications when it crosses.
+
+To register a threshold, an application must:
+
+- create an eventfd using eventfd(2);
+- open memory.usage_in_bytes or memory.memsw.usage_in_bytes;
+- write string like "<event_fd> <fd of memory.usage_in_bytes> <threshold>" to
+  cgroup.event_control.
+
+Application will be notified through eventfd when memory usage crosses
+threshold in any direction.
+
+It's applicable for root and non-root cgroup.
+
+.. _cgroup-v1-memory-oom-control:
+
+10. OOM Control (DEPRECATED)
+============================
+
+THIS IS DEPRECATED!
+
+memory.oom_control file is for OOM notification and other controls.
+
+Memory cgroup implements OOM notifier using the cgroup notification
+API (See cgroups.txt). It allows to register multiple OOM notification
+delivery and gets notification when OOM happens.
+
+To register a notifier, an application must:
+
+ - create an eventfd using eventfd(2)
+ - open memory.oom_control file
+ - write string like "<event_fd> <fd of memory.oom_control>" to
+   cgroup.event_control
+
+The application will be notified through eventfd when OOM happens.
+OOM notification doesn't work for the root cgroup.
+
+You can disable the OOM-killer by writing "1" to memory.oom_control file, as:
+
+	#echo 1 > memory.oom_control
+
+If OOM-killer is disabled, tasks under cgroup will hang/sleep
+in memory cgroup's OOM-waitqueue when they request accountable memory.
+
+For running them, you have to relax the memory cgroup's OOM status by
+
+	* enlarge limit or reduce usage.
+
+To reduce usage,
+
+	* kill some tasks.
+	* move some tasks to other group with account migration.
+	* remove some files (on tmpfs?)
+
+Then, stopped tasks will work again.
+
+At reading, current status of OOM is shown.
+
+	- oom_kill_disable 0 or 1
+	  (if 1, oom-killer is disabled)
+	- under_oom	   0 or 1
+	  (if 1, the memory cgroup is under OOM, tasks may be stopped.)
+        - oom_kill         integer counter
+          The number of processes belonging to this cgroup killed by any
+          kind of OOM killer.
+
+11. Memory Pressure (DEPRECATED)
+================================
+
+THIS IS DEPRECATED!
+
+The pressure level notifications can be used to monitor the memory
+allocation cost; based on the pressure, applications can implement
+different strategies of managing their memory resources. The pressure
+levels are defined as following:
+
+The "low" level means that the system is reclaiming memory for new
+allocations. Monitoring this reclaiming activity might be useful for
+maintaining cache level. Upon notification, the program (typically
+"Activity Manager") might analyze vmstat and act in advance (i.e.
+prematurely shutdown unimportant services).
+
+The "medium" level means that the system is experiencing medium memory
+pressure, the system might be making swap, paging out active file caches,
+etc. Upon this event applications may decide to further analyze
+vmstat/zoneinfo/memcg or internal memory usage statistics and free any
+resources that can be easily reconstructed or re-read from a disk.
+
+The "critical" level means that the system is actively thrashing, it is
+about to out of memory (OOM) or even the in-kernel OOM killer is on its
+way to trigger. Applications should do whatever they can to help the
+system. It might be too late to consult with vmstat or any other
+statistics, so it's advisable to take an immediate action.
+
+By default, events are propagated upward until the event is handled, i.e. the
+events are not pass-through. For example, you have three cgroups: A->B->C. Now
+you set up an event listener on cgroups A, B and C, and suppose group C
+experiences some pressure. In this situation, only group C will receive the
+notification, i.e. groups A and B will not receive it. This is done to avoid
+excessive "broadcasting" of messages, which disturbs the system and which is
+especially bad if we are low on memory or thrashing. Group B, will receive
+notification only if there are no event listeners for group C.
+
+There are three optional modes that specify different propagation behavior:
+
+ - "default": this is the default behavior specified above. This mode is the
+   same as omitting the optional mode parameter, preserved by backwards
+   compatibility.
+
+ - "hierarchy": events always propagate up to the root, similar to the default
+   behavior, except that propagation continues regardless of whether there are
+   event listeners at each level, with the "hierarchy" mode. In the above
+   example, groups A, B, and C will receive notification of memory pressure.
+
+ - "local": events are pass-through, i.e. they only receive notifications when
+   memory pressure is experienced in the memcg for which the notification is
+   registered. In the above example, group C will receive notification if
+   registered for "local" notification and the group experiences memory
+   pressure. However, group B will never receive notification, regardless if
+   there is an event listener for group C or not, if group B is registered for
+   local notification.
+
+The level and event notification mode ("hierarchy" or "local", if necessary) are
+specified by a comma-delimited string, i.e. "low,hierarchy" specifies
+hierarchical, pass-through, notification for all ancestor memcgs. Notification
+that is the default, non pass-through behavior, does not specify a mode.
+"medium,local" specifies pass-through notification for the medium level.
+
+The file memory.pressure_level is only used to setup an eventfd. To
+register a notification, an application must:
+
+- create an eventfd using eventfd(2);
+- open memory.pressure_level;
+- write string as "<event_fd> <fd of memory.pressure_level> <level[,mode]>"
+  to cgroup.event_control.
+
+Application will be notified through eventfd when memory pressure is at
+the specific level (or higher). Read/write operations to
+memory.pressure_level are no implemented.
+
+Test:
+
+   Here is a small script example that makes a new cgroup, sets up a
+   memory limit, sets up a notification in the cgroup and then makes child
+   cgroup experience a critical pressure::
+
+	# cd /sys/fs/cgroup/memory/
+	# mkdir foo
+	# cd foo
+	# cgroup_event_listener memory.pressure_level low,hierarchy &
+	# echo 8000000 > memory.limit_in_bytes
+	# echo 8000000 > memory.memsw.limit_in_bytes
+	# echo $$ > tasks
+	# dd if=/dev/zero | read x
+
+   (Expect a bunch of notifications, and eventually, the oom-killer will
+   trigger.)
+
+12. TODO
+========
+
+1. Make per-cgroup scanner reclaim not-shared pages first
+2. Teach controller to account for shared-pages
+3. Start reclamation in the background when the limit is
+   not yet hit but the usage is getting closer
+
+Summary
+=======
+
+Overall, the memory controller has been a stable controller and has been
+commented and discussed quite extensively in the community.
+
+References
+==========
+
+.. [1] Singh, Balbir. RFC: Memory Controller, http://lwn.net/Articles/206697/
+.. [2] Singh, Balbir. Memory Controller (RSS Control),
+   http://lwn.net/Articles/222762/
+.. [3] Emelianov, Pavel. Resource controllers based on process cgroups
+   https://lore.kernel.org/r/45ED7DEC.7010403@sw.ru
+.. [4] Emelianov, Pavel. RSS controller based on process cgroups (v2)
+   https://lore.kernel.org/r/461A3010.90403@sw.ru
+.. [5] Emelianov, Pavel. RSS controller based on process cgroups (v3)
+   https://lore.kernel.org/r/465D9739.8070209@openvz.org
+
+6. Menage, Paul. Control Groups v10, http://lwn.net/Articles/236032/
+7. Vaidyanathan, Srinivasan, Control Groups: Pagecache accounting and control
+   subsystem (v3), http://lwn.net/Articles/235534/
+8. Singh, Balbir. RSS controller v2 test results (lmbench),
+   https://lore.kernel.org/r/464C95D4.7070806@linux.vnet.ibm.com
+9. Singh, Balbir. RSS controller v2 AIM9 results
+   https://lore.kernel.org/r/464D267A.50107@linux.vnet.ibm.com
+10. Singh, Balbir. Memory controller v6 test results,
+    https://lore.kernel.org/r/20070819094658.654.84837.sendpatchset@balbir-laptop
+
+.. [11] Singh, Balbir. Memory controller introduction (v6),
+   https://lore.kernel.org/r/20070817084228.26003.12568.sendpatchset@balbir-laptop
+.. [12] Corbet, Jonathan, Controlling memory use in cgroups,
+   http://lwn.net/Articles/243795/
diff --git a/Documentation/admin-guide/cgroup-v1/misc.rst b/Documentation/admin-guide/cgroup-v1/misc.rst
new file mode 100644
index 000000000..661614c24
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/misc.rst
@@ -0,0 +1,4 @@
+===============
+Misc controller
+===============
+Please refer "Misc" documentation in Documentation/admin-guide/cgroup-v2.rst
diff --git a/Documentation/admin-guide/cgroup-v1/net_cls.rst b/Documentation/admin-guide/cgroup-v1/net_cls.rst
new file mode 100644
index 000000000..a2cf272af
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/net_cls.rst
@@ -0,0 +1,44 @@
+=========================
+Network classifier cgroup
+=========================
+
+The Network classifier cgroup provides an interface to
+tag network packets with a class identifier (classid).
+
+The Traffic Controller (tc) can be used to assign
+different priorities to packets from different cgroups.
+Also, Netfilter (iptables) can use this tag to perform
+actions on such packets.
+
+Creating a net_cls cgroups instance creates a net_cls.classid file.
+This net_cls.classid value is initialized to 0.
+
+You can write hexadecimal values to net_cls.classid; the format for these
+values is 0xAAAABBBB; AAAA is the major handle number and BBBB
+is the minor handle number.
+Reading net_cls.classid yields a decimal result.
+
+Example::
+
+	mkdir /sys/fs/cgroup/net_cls
+	mount -t cgroup -onet_cls net_cls /sys/fs/cgroup/net_cls
+	mkdir /sys/fs/cgroup/net_cls/0
+	echo 0x100001 >  /sys/fs/cgroup/net_cls/0/net_cls.classid
+
+- setting a 10:1 handle::
+
+	cat /sys/fs/cgroup/net_cls/0/net_cls.classid
+	1048577
+
+- configuring tc::
+
+	tc qdisc add dev eth0 root handle 10: htb
+	tc class add dev eth0 parent 10: classid 10:1 htb rate 40mbit
+
+- creating traffic class 10:1::
+
+	tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup
+
+configuring iptables, basic example::
+
+	iptables -A OUTPUT -m cgroup ! --cgroup 0x100001 -j DROP
diff --git a/Documentation/admin-guide/cgroup-v1/net_prio.rst b/Documentation/admin-guide/cgroup-v1/net_prio.rst
new file mode 100644
index 000000000..b40905871
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/net_prio.rst
@@ -0,0 +1,57 @@
+=======================
+Network priority cgroup
+=======================
+
+The Network priority cgroup provides an interface to allow an administrator to
+dynamically set the priority of network traffic generated by various
+applications
+
+Nominally, an application would set the priority of its traffic via the
+SO_PRIORITY socket option.  This however, is not always possible because:
+
+1) The application may not have been coded to set this value
+2) The priority of application traffic is often a site-specific administrative
+   decision rather than an application defined one.
+
+This cgroup allows an administrator to assign a process to a group which defines
+the priority of egress traffic on a given interface. Network priority groups can
+be created by first mounting the cgroup filesystem::
+
+	# mount -t cgroup -onet_prio none /sys/fs/cgroup/net_prio
+
+With the above step, the initial group acting as the parent accounting group
+becomes visible at '/sys/fs/cgroup/net_prio'.  This group includes all tasks in
+the system. '/sys/fs/cgroup/net_prio/tasks' lists the tasks in this cgroup.
+
+Each net_prio cgroup contains two files that are subsystem specific
+
+net_prio.prioidx
+  This file is read-only, and is simply informative.  It contains a unique
+  integer value that the kernel uses as an internal representation of this
+  cgroup.
+
+net_prio.ifpriomap
+  This file contains a map of the priorities assigned to traffic originating
+  from processes in this group and egressing the system on various interfaces.
+  It contains a list of tuples in the form <ifname priority>.  Contents of this
+  file can be modified by echoing a string into the file using the same tuple
+  format. For example::
+
+	echo "eth0 5" > /sys/fs/cgroups/net_prio/iscsi/net_prio.ifpriomap
+
+This command would force any traffic originating from processes belonging to the
+iscsi net_prio cgroup and egressing on interface eth0 to have the priority of
+said traffic set to the value 5. The parent accounting group also has a
+writeable 'net_prio.ifpriomap' file that can be used to set a system default
+priority.
+
+Priorities are set immediately prior to queueing a frame to the device
+queueing discipline (qdisc) so priorities will be assigned prior to the hardware
+queue selection being made.
+
+One usage for the net_prio cgroup is with mqprio qdisc allowing application
+traffic to be steered to hardware/driver based traffic classes. These mappings
+can then be managed by administrators or other networking protocols such as
+DCBX.
+
+A new net_prio cgroup inherits the parent's configuration.
diff --git a/Documentation/admin-guide/cgroup-v1/pids.rst b/Documentation/admin-guide/cgroup-v1/pids.rst
new file mode 100644
index 000000000..0f9f9a7b1
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/pids.rst
@@ -0,0 +1,93 @@
+=========================
+Process Number Controller
+=========================
+
+Abstract
+--------
+
+The process number controller is used to allow a cgroup hierarchy to stop any
+new tasks from being fork()'d or clone()'d after a certain limit is reached.
+
+Since it is trivial to hit the task limit without hitting any kmemcg limits in
+place, PIDs are a fundamental resource. As such, PID exhaustion must be
+preventable in the scope of a cgroup hierarchy by allowing resource limiting of
+the number of tasks in a cgroup.
+
+Usage
+-----
+
+In order to use the `pids` controller, set the maximum number of tasks in
+pids.max (this is not available in the root cgroup for obvious reasons). The
+number of processes currently in the cgroup is given by pids.current.
+
+Organisational operations are not blocked by cgroup policies, so it is possible
+to have pids.current > pids.max. This can be done by either setting the limit to
+be smaller than pids.current, or attaching enough processes to the cgroup such
+that pids.current > pids.max. However, it is not possible to violate a cgroup
+policy through fork() or clone(). fork() and clone() will return -EAGAIN if the
+creation of a new process would cause a cgroup policy to be violated.
+
+To set a cgroup to have no limit, set pids.max to "max". This is the default for
+all new cgroups (N.B. that PID limits are hierarchical, so the most stringent
+limit in the hierarchy is followed).
+
+pids.current tracks all child cgroup hierarchies, so parent/pids.current is a
+superset of parent/child/pids.current.
+
+The pids.events file contains event counters:
+
+  - max: Number of times fork failed in the cgroup because limit was hit in
+    self or ancestors.
+
+Example
+-------
+
+First, we mount the pids controller::
+
+	# mkdir -p /sys/fs/cgroup/pids
+	# mount -t cgroup -o pids none /sys/fs/cgroup/pids
+
+Then we create a hierarchy, set limits and attach processes to it::
+
+	# mkdir -p /sys/fs/cgroup/pids/parent/child
+	# echo 2 > /sys/fs/cgroup/pids/parent/pids.max
+	# echo $$ > /sys/fs/cgroup/pids/parent/cgroup.procs
+	# cat /sys/fs/cgroup/pids/parent/pids.current
+	2
+	#
+
+It should be noted that attempts to overcome the set limit (2 in this case) will
+fail::
+
+	# cat /sys/fs/cgroup/pids/parent/pids.current
+	2
+	# ( /bin/echo "Here's some processes for you." | cat )
+	sh: fork: Resource temporary unavailable
+	#
+
+Even if we migrate to a child cgroup (which doesn't have a set limit), we will
+not be able to overcome the most stringent limit in the hierarchy (in this case,
+parent's)::
+
+	# echo $$ > /sys/fs/cgroup/pids/parent/child/cgroup.procs
+	# cat /sys/fs/cgroup/pids/parent/pids.current
+	2
+	# cat /sys/fs/cgroup/pids/parent/child/pids.current
+	2
+	# cat /sys/fs/cgroup/pids/parent/child/pids.max
+	max
+	# ( /bin/echo "Here's some processes for you." | cat )
+	sh: fork: Resource temporary unavailable
+	#
+
+We can set a limit that is smaller than pids.current, which will stop any new
+processes from being forked at all (note that the shell itself counts towards
+pids.current)::
+
+	# echo 1 > /sys/fs/cgroup/pids/parent/pids.max
+	# /bin/echo "We can't even spawn a single process now."
+	sh: fork: Resource temporary unavailable
+	# echo 0 > /sys/fs/cgroup/pids/parent/pids.max
+	# /bin/echo "We can't even spawn a single process now."
+	sh: fork: Resource temporary unavailable
+	#
diff --git a/Documentation/admin-guide/cgroup-v1/rdma.rst b/Documentation/admin-guide/cgroup-v1/rdma.rst
new file mode 100644
index 000000000..03e1f1b78
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v1/rdma.rst
@@ -0,0 +1,191 @@
+===============
+RDMA Controller
+===============
+
+.. Contents
+
+   1. Overview
+     1-1. What is RDMA controller?
+     1-2. Why RDMA controller needed?
+     1-3. How is RDMA controller implemented?
+   2. Usage Examples
+   3. RDMA Interface Files
+
+1. Overview
+===========
+
+1-1. What is RDMA controller?
+-----------------------------
+
+RDMA controller allows user to limit RDMA/IB specific resources that a given
+set of processes can use. These processes are grouped using RDMA controller.
+
+RDMA controller defines two resources which can be limited for processes of a
+cgroup.
+
+1-2. Why RDMA controller needed?
+--------------------------------
+
+Currently user space applications can easily take away all the rdma verb
+specific resources such as AH, CQ, QP, MR etc. Due to which other applications
+in other cgroup or kernel space ULPs may not even get chance to allocate any
+rdma resources. This can lead to service unavailability.
+
+Therefore RDMA controller is needed through which resource consumption
+of processes can be limited. Through this controller different rdma
+resources can be accounted.
+
+1-3. How is RDMA controller implemented?
+----------------------------------------
+
+RDMA cgroup allows limit configuration of resources. Rdma cgroup maintains
+resource accounting per cgroup, per device using resource pool structure.
+Each such resource pool is limited up to 64 resources in given resource pool
+by rdma cgroup, which can be extended later if required.
+
+This resource pool object is linked to the cgroup css. Typically there
+are 0 to 4 resource pool instances per cgroup, per device in most use cases.
+But nothing limits to have it more. At present hundreds of RDMA devices per
+single cgroup may not be handled optimally, however there is no
+known use case or requirement for such configuration either.
+
+Since RDMA resources can be allocated from any process and can be freed by any
+of the child processes which shares the address space, rdma resources are
+always owned by the creator cgroup css. This allows process migration from one
+to other cgroup without major complexity of transferring resource ownership;
+because such ownership is not really present due to shared nature of
+rdma resources. Linking resources around css also ensures that cgroups can be
+deleted after processes migrated. This allow progress migration as well with
+active resources, even though that is not a primary use case.
+
+Whenever RDMA resource charging occurs, owner rdma cgroup is returned to
+the caller. Same rdma cgroup should be passed while uncharging the resource.
+This also allows process migrated with active RDMA resource to charge
+to new owner cgroup for new resource. It also allows to uncharge resource of
+a process from previously charged cgroup which is migrated to new cgroup,
+even though that is not a primary use case.
+
+Resource pool object is created in following situations.
+(a) User sets the limit and no previous resource pool exist for the device
+of interest for the cgroup.
+(b) No resource limits were configured, but IB/RDMA stack tries to
+charge the resource. So that it correctly uncharge them when applications are
+running without limits and later on when limits are enforced during uncharging,
+otherwise usage count will drop to negative.
+
+Resource pool is destroyed if all the resource limits are set to max and
+it is the last resource getting deallocated.
+
+User should set all the limit to max value if it intents to remove/unconfigure
+the resource pool for a particular device.
+
+IB stack honors limits enforced by the rdma controller. When application
+query about maximum resource limits of IB device, it returns minimum of
+what is configured by user for a given cgroup and what is supported by
+IB device.
+
+Following resources can be accounted by rdma controller.
+
+  ==========    =============================
+  hca_handle	Maximum number of HCA Handles
+  hca_object 	Maximum number of HCA Objects
+  ==========    =============================
+
+RDMA devices from all network namespaces are listed. Each line starts with
+the device name. If more than one device has the same name, ``index=N``
+follows the name, where ``N`` is the system-wide RDMA device index, unique
+among registered devices. When configuring a limit, the index is optional
+for a globally unique name and required for a duplicate name. A write without
+the required index fails with ``-ENOTUNIQ``.
+
+2. Usage Examples
+=================
+
+(a) Configure resource limit::
+
+	echo mlx4_0 hca_handle=2 hca_object=2000 > /sys/fs/cgroup/rdma/1/rdma.max
+	echo ocrdma1 hca_handle=3 > /sys/fs/cgroup/rdma/2/rdma.max
+	echo "rxe0 index=5 hca_handle=2" > /sys/fs/cgroup/rdma/3/rdma.max
+
+(b) Query resource limit::
+
+	cat /sys/fs/cgroup/rdma/2/rdma.max
+	#Output:
+	mlx4_0 hca_handle=2 hca_object=2000
+	ocrdma1 hca_handle=3 hca_object=max
+
+(c) Query current usage::
+
+	cat /sys/fs/cgroup/rdma/2/rdma.current
+	#Output:
+	mlx4_0 hca_handle=1 hca_object=20
+	ocrdma1 hca_handle=1 hca_object=23
+
+(d) Delete resource limit::
+
+	echo mlx4_0 hca_handle=max hca_object=max > /sys/fs/cgroup/rdma/1/rdma.max
+
+3. RDMA Interface Files
+========================
+
+The following interface files are available in each non-root RDMA cgroup.
+
+  rdma.max
+	A read-write file which describes the configured resource limit
+	for an RDMA/IB device.  See the Usage Examples above.
+
+  rdma.current
+	A read-only file which describes the current resource usage.
+
+  rdma.peak
+	A read-only nested-keyed file which shows the historical high
+	watermark of resource usage per device since the cgroup was created.
+
+	An example for mlx4 and ocrdma device follows::
+
+	  mlx4_0 hca_handle=1 hca_object=20
+	  ocrdma1 hca_handle=0 hca_object=23
+
+  rdma.events
+	A read-only nested-keyed file which exists on non-root cgroups
+	and contains the following keys:
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because a rdma.max limit in the subtree
+		was reached.  This is a hierarchical counter propagated
+		upward to all ancestor cgroups.  A value change in this
+		file generates a file modified event.
+
+	  alloc_fail
+		The number of RDMA resource allocation attempts that
+		originated in this cgroup or its descendants and failed
+		due to a rdma.max limit being reached.  This is a
+		hierarchical counter propagated upward.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=3 hca_object.max=0 hca_object.alloc_fail=0
+
+  rdma.events.local
+	Similar to rdma.events but the fields are local to the cgroup,
+	i.e. not hierarchical.  The file modified event generated on this
+	file reflects only the local events.
+
+	The following nested keys are defined.
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because this cgroup's own rdma.max limit
+		was reached.
+
+	  alloc_fail
+		The number of RDMA resource allocation attempts
+		originating from this cgroup that failed due to this
+		cgroup's or an ancestor's rdma.max limit.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=0 hca_object.max=0 hca_object.alloc_fail=0
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
new file mode 100644
index 000000000..7c2a8ed80
--- /dev/null
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -0,0 +1,3575 @@
+.. _cgroup-v2:
+
+================
+Control Group v2
+================
+
+:Date: October, 2015
+:Author: Tejun Heo <tj@kernel.org>
+
+This is the authoritative documentation on the design, interface and
+conventions of cgroup v2.  It describes all userland-visible aspects
+of cgroup including core and specific controller behaviors.  All
+future changes must be reflected in this document.  Documentation for
+v1 is available under :ref:`Documentation/admin-guide/cgroup-v1/index.rst <cgroup-v1>`.
+
+.. CONTENTS
+
+   [Whenever any new section is added to this document, please also add
+    an entry here.]
+
+   1. Introduction
+     1-1. Terminology
+     1-2. What is cgroup?
+   2. Basic Operations
+     2-1. Mounting
+     2-2. Organizing Processes and Threads
+       2-2-1. Processes
+       2-2-2. Threads
+     2-3. [Un]populated Notification
+     2-4. Controlling Controllers
+       2-4-1. Availability
+       2-4-2. Enabling and Disabling
+       2-4-3. Top-down Constraint
+       2-4-4. No Internal Process Constraint
+     2-5. Delegation
+       2-5-1. Model of Delegation
+       2-5-2. Delegation Containment
+     2-6. Guidelines
+       2-6-1. Organize Once and Control
+       2-6-2. Avoid Name Collisions
+   3. Resource Distribution Models
+     3-1. Weights
+     3-2. Limits
+     3-3. Protections
+     3-4. Allocations
+   4. Interface Files
+     4-1. Format
+     4-2. Conventions
+     4-3. Core Interface Files
+   5. Controllers
+     5-1. CPU
+       5-1-1. CPU Interface Files
+     5-2. Memory
+       5-2-1. Memory Interface Files
+       5-2-2. Usage Guidelines
+       5-2-3. Reclaim Protection
+       5-2-4. Memory Ownership
+     5-3. IO
+       5-3-1. IO Interface Files
+       5-3-2. Writeback
+       5-3-3. IO Latency
+         5-3-3-1. How IO Latency Throttling Works
+         5-3-3-2. IO Latency Interface Files
+       5-3-4. IO Priority
+     5-4. PID
+       5-4-1. PID Interface Files
+     5-5. Cpuset
+       5.5-1. Cpuset Interface Files
+     5-6. Device controller
+     5-7. RDMA
+       5-7-1. RDMA Interface Files
+     5-8. DMEM
+       5-8-1. DMEM Interface Files
+     5-9. HugeTLB
+       5.9-1. HugeTLB Interface Files
+     5-10. Misc
+       5.10-1 Misc Interface Files
+       5.10-2 Migration and Ownership
+     5-11. Others
+       5-11-1. perf_event
+     5-N. Non-normative information
+       5-N-1. CPU controller root cgroup process behaviour
+       5-N-2. IO controller root cgroup process behaviour
+   6. Namespace
+     6-1. Basics
+     6-2. The Root and Views
+     6-3. Migration and setns(2)
+     6-4. Interaction with Other Namespaces
+   P. Information on Kernel Programming
+     P-1. Filesystem Support for Writeback
+   D. Deprecated v1 Core Features
+   R. Issues with v1 and Rationales for v2
+     R-1. Multiple Hierarchies
+     R-2. Thread Granularity
+     R-3. Competition Between Inner Nodes and Threads
+     R-4. Other Interface Issues
+     R-5. Controller Issues and Remedies
+       R-5-1. Memory
+
+
+Introduction
+============
+
+Terminology
+-----------
+
+"cgroup" stands for "control group" and is never capitalized.  The
+singular form is used to designate the whole feature and also as a
+qualifier as in "cgroup controllers".  When explicitly referring to
+multiple individual control groups, the plural form "cgroups" is used.
+
+
+What is cgroup?
+---------------
+
+cgroup is a mechanism to organize processes hierarchically and
+distribute system resources along the hierarchy in a controlled and
+configurable manner.
+
+cgroup is largely composed of two parts - the core and controllers.
+cgroup core is primarily responsible for hierarchically organizing
+processes.  A cgroup controller is usually responsible for
+distributing a specific type of system resource along the hierarchy
+although there are utility controllers which serve purposes other than
+resource distribution.
+
+cgroups form a tree structure and every process in the system belongs
+to one and only one cgroup.  All threads of a process belong to the
+same cgroup.  On creation, all processes are put in the cgroup that
+the parent process belongs to at the time.  A process can be migrated
+to another cgroup.  Migration of a process doesn't affect already
+existing descendant processes.
+
+Following certain structural constraints, controllers may be enabled or
+disabled selectively on a cgroup.  All controller behaviors are
+hierarchical - if a controller is enabled on a cgroup, it affects all
+processes which belong to the cgroups consisting the inclusive
+sub-hierarchy of the cgroup.  When a controller is enabled on a nested
+cgroup, it always restricts the resource distribution further.  The
+restrictions set closer to the root in the hierarchy can not be
+overridden from further away.
+
+
+Basic Operations
+================
+
+Mounting
+--------
+
+Unlike v1, cgroup v2 has only single hierarchy.  The cgroup v2
+hierarchy can be mounted with the following mount command::
+
+  # mount -t cgroup2 none $MOUNT_POINT
+
+cgroup2 filesystem has the magic number 0x63677270 ("cgrp").  All
+controllers which support v2 and are not bound to a v1 hierarchy are
+automatically bound to the v2 hierarchy and show up at the root.
+Controllers which are not in active use in the v2 hierarchy can be
+bound to other hierarchies.  This allows mixing v2 hierarchy with the
+legacy v1 multiple hierarchies in a fully backward compatible way.
+
+A controller can be moved across hierarchies only after the controller
+is no longer referenced in its current hierarchy.  Because per-cgroup
+controller states are destroyed asynchronously and controllers may
+have lingering references, a controller may not show up immediately on
+the v2 hierarchy after the final umount of the previous hierarchy.
+Similarly, a controller should be fully disabled to be moved out of
+the unified hierarchy and it may take some time for the disabled
+controller to become available for other hierarchies; furthermore, due
+to inter-controller dependencies, other controllers may need to be
+disabled too.
+
+While useful for development and manual configurations, moving
+controllers dynamically between the v2 and other hierarchies is
+strongly discouraged for production use.  It is recommended to decide
+the hierarchies and controller associations before starting using the
+controllers after system boot.
+
+During transition to v2, system management software might still
+automount the v1 cgroup filesystem and so hijack all controllers
+during boot, before manual intervention is possible. To make testing
+and experimenting easier, the kernel parameter cgroup_no_v1= allows
+disabling controllers in v1 and make them always available in v2.
+
+cgroup v2 currently supports the following mount options.
+
+  nsdelegate
+	Consider cgroup namespaces as delegation boundaries.  This
+	option is system wide and can only be set on mount or modified
+	through remount from the init namespace.  The mount option is
+	ignored on non-init namespace mounts.  Please refer to the
+	Delegation section for details.
+
+  favordynmods
+        Reduce the latencies of dynamic cgroup modifications such as
+        task migrations and controller on/offs at the cost of making
+        hot path operations such as forks and exits more expensive.
+        The static usage pattern of creating a cgroup, enabling
+        controllers, and then seeding it with CLONE_INTO_CGROUP is
+        not affected by this option.
+
+  memory_localevents
+        Only populate memory.events with data for the current cgroup,
+        and not any subtrees. This is legacy behaviour, the default
+        behaviour without this option is to include subtree counts.
+        This option is system wide and can only be set on mount or
+        modified through remount from the init namespace. The mount
+        option is ignored on non-init namespace mounts.
+
+  memory_recursiveprot
+        Recursively apply memory.min and memory.low protection to
+        entire subtrees, without requiring explicit downward
+        propagation into leaf cgroups.  This allows protecting entire
+        subtrees from one another, while retaining free competition
+        within those subtrees.  This should have been the default
+        behavior but is a mount-option to avoid regressing setups
+        relying on the original semantics (e.g. specifying bogusly
+        high 'bypass' protection values at higher tree levels).
+
+  memory_hugetlb_accounting
+        Count HugeTLB memory usage towards the cgroup's overall
+        memory usage for the memory controller (for the purpose of
+        statistics reporting and memory protection). This is a new
+        behavior that could regress existing setups, so it must be
+        explicitly opted in with this mount option.
+
+        A few caveats to keep in mind:
+
+        * There is no HugeTLB pool management involved in the memory
+          controller. The pre-allocated pool does not belong to anyone.
+          Specifically, when a new HugeTLB folio is allocated to
+          the pool, it is not accounted for from the perspective of the
+          memory controller. It is only charged to a cgroup when it is
+          actually used (for e.g at page fault time). Host memory
+          overcommit management has to consider this when configuring
+          hard limits. In general, HugeTLB pool management should be
+          done via other mechanisms (such as the HugeTLB controller).
+        * Failure to charge a HugeTLB folio to the memory controller
+          results in SIGBUS. This could happen even if the HugeTLB pool
+          still has pages available (but the cgroup limit is hit and
+          reclaim attempt fails).
+        * Charging HugeTLB memory towards the memory controller affects
+          memory protection and reclaim dynamics. Any userspace tuning
+          (of low, min limits for e.g) needs to take this into account.
+        * HugeTLB pages utilized while this option is not selected
+          will not be tracked by the memory controller (even if cgroup
+          v2 is remounted later on).
+
+  pids_localevents
+        The option restores v1-like behavior of pids.events:max, that is only
+        local (inside cgroup proper) fork failures are counted. Without this
+        option pids.events.max represents any pids.max enforcemnt across
+        cgroup's subtree.
+
+
+
+Organizing Processes and Threads
+--------------------------------
+
+Processes
+~~~~~~~~~
+
+Initially, only the root cgroup exists to which all processes belong.
+A child cgroup can be created by creating a sub-directory::
+
+  # mkdir $CGROUP_NAME
+
+A given cgroup may have multiple child cgroups forming a tree
+structure.  Each cgroup has a read-writable interface file
+"cgroup.procs".  When read, it lists the PIDs of all processes which
+belong to the cgroup one-per-line.  The PIDs are not ordered and the
+same PID may show up more than once if the process got moved to
+another cgroup and then back or the PID got recycled while reading.
+
+A process can be migrated into a cgroup by writing its PID to the
+target cgroup's "cgroup.procs" file.  Only one process can be migrated
+on a single write(2) call.  If a process is composed of multiple
+threads, writing the PID of any thread migrates all threads of the
+process.
+
+When a process forks a child process, the new process is born into the
+cgroup that the forking process belongs to at the time of the
+operation.  After exit, a process stays associated with the cgroup
+that it belonged to at the time of exit until it's reaped; however, a
+zombie process does not appear in "cgroup.procs" and thus can't be
+moved to another cgroup.
+
+A cgroup which doesn't have any children or live processes can be
+destroyed by removing the directory.  Note that a cgroup which doesn't
+have any children and is associated only with zombie processes is
+considered empty and can be removed::
+
+  # rmdir $CGROUP_NAME
+
+"/proc/$PID/cgroup" lists a process's cgroup membership.  If legacy
+cgroup is in use in the system, this file may contain multiple lines,
+one for each hierarchy.  The entry for cgroup v2 is always in the
+format "0::$PATH"::
+
+  # cat /proc/842/cgroup
+  ...
+  0::/test-cgroup/test-cgroup-nested
+
+If the process becomes a zombie and the cgroup it was associated with
+is removed subsequently, " (deleted)" is appended to the path::
+
+  # cat /proc/842/cgroup
+  ...
+  0::/test-cgroup/test-cgroup-nested (deleted)
+
+
+Threads
+~~~~~~~
+
+cgroup v2 supports thread granularity for a subset of controllers to
+support use cases requiring hierarchical resource distribution across
+the threads of a group of processes.  By default, all threads of a
+process belong to the same cgroup, which also serves as the resource
+domain to host resource consumptions which are not specific to a
+process or thread.  The thread mode allows threads to be spread across
+a subtree while still maintaining the common resource domain for them.
+
+Controllers which support thread mode are called threaded controllers.
+The ones which don't are called domain controllers.
+
+Marking a cgroup threaded makes it join the resource domain of its
+parent as a threaded cgroup.  The parent may be another threaded
+cgroup whose resource domain is further up in the hierarchy.  The root
+of a threaded subtree, that is, the nearest ancestor which is not
+threaded, is called threaded domain or thread root interchangeably and
+serves as the resource domain for the entire subtree.
+
+Inside a threaded subtree, threads of a process can be put in
+different cgroups and are not subject to the no internal process
+constraint - threaded controllers can be enabled on non-leaf cgroups
+whether they have threads in them or not.
+
+As the threaded domain cgroup hosts all the domain resource
+consumptions of the subtree, it is considered to have internal
+resource consumptions whether there are processes in it or not and
+can't have populated child cgroups which aren't threaded.  Because the
+root cgroup is not subject to no internal process constraint, it can
+serve both as a threaded domain and a parent to domain cgroups.
+
+The current operation mode or type of the cgroup is shown in the
+"cgroup.type" file which indicates whether the cgroup is a normal
+domain, a domain which is serving as the domain of a threaded subtree,
+or a threaded cgroup.
+
+On creation, a cgroup is always a domain cgroup and can be made
+threaded by writing "threaded" to the "cgroup.type" file.  The
+operation is single direction::
+
+  # echo threaded > cgroup.type
+
+Once threaded, the cgroup can't be made a domain again.  To enable the
+thread mode, the following conditions must be met.
+
+- As the cgroup will join the parent's resource domain.  The parent
+  must either be a valid (threaded) domain or a threaded cgroup.
+
+- When the parent is an unthreaded domain, it must not have any domain
+  controllers enabled or populated domain children.  The root is
+  exempt from this requirement.
+
+Topology-wise, a cgroup can be in an invalid state.  Please consider
+the following topology::
+
+  A (threaded domain) - B (threaded) - C (domain, just created)
+
+C is created as a domain but isn't connected to a parent which can
+host child domains.  C can't be used until it is turned into a
+threaded cgroup.  "cgroup.type" file will report "domain (invalid)" in
+these cases.  Operations which fail due to invalid topology use
+EOPNOTSUPP as the errno.
+
+A domain cgroup is turned into a threaded domain when one of its child
+cgroup becomes threaded or threaded controllers are enabled in the
+"cgroup.subtree_control" file while there are processes in the cgroup.
+A threaded domain reverts to a normal domain when the conditions
+clear.
+
+When read, "cgroup.threads" contains the list of the thread IDs of all
+threads in the cgroup.  Except that the operations are per-thread
+instead of per-process, "cgroup.threads" has the same format and
+behaves the same way as "cgroup.procs".  While "cgroup.threads" can be
+written to in any cgroup, as it can only move threads inside the same
+threaded domain, its operations are confined inside each threaded
+subtree.
+
+The threaded domain cgroup serves as the resource domain for the whole
+subtree, and, while the threads can be scattered across the subtree,
+all the processes are considered to be in the threaded domain cgroup.
+"cgroup.procs" in a threaded domain cgroup contains the PIDs of all
+processes in the subtree and is not readable in the subtree proper.
+However, "cgroup.procs" can be written to from anywhere in the subtree
+to migrate all threads of the matching process to the cgroup.
+
+Only threaded controllers can be enabled in a threaded subtree.  When
+a threaded controller is enabled inside a threaded subtree, it only
+accounts for and controls resource consumptions associated with the
+threads in the cgroup and its descendants.  All consumptions which
+aren't tied to a specific thread belong to the threaded domain cgroup.
+
+Because a threaded subtree is exempt from no internal process
+constraint, a threaded controller must be able to handle competition
+between threads in a non-leaf cgroup and its child cgroups.  Each
+threaded controller defines how such competitions are handled.
+
+Currently, the following controllers are threaded and can be enabled
+in a threaded cgroup::
+
+- cpu
+- cpuset
+- perf_event
+- pids
+
+[Un]populated Notification
+--------------------------
+
+Each non-root cgroup has a "cgroup.events" file which contains
+"populated" field indicating whether the cgroup's sub-hierarchy has
+live processes in it.  Its value is 0 if there is no live process in
+the cgroup and its descendants; otherwise, 1.  poll and [id]notify
+events are triggered when the value changes.  This can be used, for
+example, to start a clean-up operation after all processes of a given
+sub-hierarchy have exited.  The populated state updates and
+notifications are recursive.  Consider the following sub-hierarchy
+where the numbers in the parentheses represent the numbers of processes
+in each cgroup::
+
+  A(4) - B(0) - C(1)
+              \ D(0)
+
+A, B and C's "populated" fields would be 1 while D's 0.  After the one
+process in C exits, B and C's "populated" fields would flip to "0" and
+file modified events will be generated on the "cgroup.events" files of
+both cgroups.
+
+
+Controlling Controllers
+-----------------------
+
+Availability
+~~~~~~~~~~~~
+
+A controller is available in a cgroup when it is supported by the kernel (i.e.,
+compiled in, not disabled and not attached to a v1 hierarchy) and listed in the
+"cgroup.controllers" file. Availability means the controller's interface files
+are exposed in the cgroup’s directory, allowing the distribution of the target
+resource to be observed or controlled within that cgroup.
+
+Enabling and Disabling
+~~~~~~~~~~~~~~~~~~~~~~
+
+Each cgroup has a "cgroup.controllers" file which lists all
+controllers available for the cgroup to enable::
+
+  # cat cgroup.controllers
+  cpu io memory
+
+No controller is enabled by default.  Controllers can be enabled and
+disabled by writing to the "cgroup.subtree_control" file::
+
+  # echo "+cpu +memory -io" > cgroup.subtree_control
+
+Only controllers which are listed in "cgroup.controllers" can be
+enabled.  When multiple operations are specified as above, either they
+all succeed or fail.  If multiple operations on the same controller
+are specified, the last one is effective.
+
+Enabling a controller in a cgroup indicates that the distribution of
+the target resource across its immediate children will be controlled.
+Consider the following sub-hierarchy.  The enabled controllers are
+listed in parentheses::
+
+  A(cpu,memory) - B(memory) - C()
+                            \ D()
+
+As A has "cpu" and "memory" enabled, A will control the distribution
+of CPU cycles and memory to its children, in this case, B.  As B has
+"memory" enabled but not "CPU", C and D will compete freely on CPU
+cycles but their division of memory available to B will be controlled.
+
+As a controller regulates the distribution of the target resource to
+the cgroup's children, enabling it creates the controller's interface
+files in the child cgroups.  In the above example, enabling "cpu" on B
+would create the "cpu." prefixed controller interface files in C and
+D.  Likewise, disabling "memory" from B would remove the "memory."
+prefixed controller interface files from C and D.  This means that the
+controller interface files - anything which doesn't start with
+"cgroup." are owned by the parent rather than the cgroup itself.
+
+
+Top-down Constraint
+~~~~~~~~~~~~~~~~~~~
+
+Resources are distributed top-down and a cgroup can further distribute
+a resource only if the resource has been distributed to it from the
+parent.  This means that all non-root "cgroup.subtree_control" files
+can only contain controllers which are enabled in the parent's
+"cgroup.subtree_control" file.  A controller can be enabled only if
+the parent has the controller enabled and a controller can't be
+disabled if one or more children have it enabled.
+
+
+No Internal Process Constraint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Non-root cgroups can distribute domain resources to their children
+only when they don't have any processes of their own.  In other words,
+only domain cgroups which don't contain any processes can have domain
+controllers enabled in their "cgroup.subtree_control" files.
+
+This guarantees that, when a domain controller is looking at the part
+of the hierarchy which has it enabled, processes are always only on
+the leaves.  This rules out situations where child cgroups compete
+against internal processes of the parent.
+
+The root cgroup is exempt from this restriction.  Root contains
+processes and anonymous resource consumption which can't be associated
+with any other cgroups and requires special treatment from most
+controllers.  How resource consumption in the root cgroup is governed
+is up to each controller (for more information on this topic please
+refer to the Non-normative information section in the Controllers
+chapter).
+
+Note that the restriction doesn't get in the way if there is no
+enabled controller in the cgroup's "cgroup.subtree_control".  This is
+important as otherwise it wouldn't be possible to create children of a
+populated cgroup.  To control resource distribution of a cgroup, the
+cgroup must create children and transfer all its processes to the
+children before enabling controllers in its "cgroup.subtree_control"
+file.
+
+
+Delegation
+----------
+
+Model of Delegation
+~~~~~~~~~~~~~~~~~~~
+
+A cgroup can be delegated in two ways.  First, to a less privileged
+user by granting write access of the directory and its "cgroup.procs",
+"cgroup.threads" and "cgroup.subtree_control" files to the user.
+Second, if the "nsdelegate" mount option is set, automatically to a
+cgroup namespace on namespace creation.
+
+Because the resource control interface files in a given directory
+control the distribution of the parent's resources, the delegatee
+shouldn't be allowed to write to them.  For the first method, this is
+achieved by not granting access to these files.  For the second, files
+outside the namespace should be hidden from the delegatee by the means
+of at least mount namespacing, and the kernel rejects writes to all
+files on a namespace root from inside the cgroup namespace, except for
+those files listed in "/sys/kernel/cgroup/delegate" (including
+"cgroup.procs", "cgroup.threads", "cgroup.subtree_control", etc.).
+
+The end results are equivalent for both delegation types.  Once
+delegated, the user can build sub-hierarchy under the directory,
+organize processes inside it as it sees fit and further distribute the
+resources it received from the parent.  The limits and other settings
+of all resource controllers are hierarchical and regardless of what
+happens in the delegated sub-hierarchy, nothing can escape the
+resource restrictions imposed by the parent.
+
+Currently, cgroup doesn't impose any restrictions on the number of
+cgroups in or nesting depth of a delegated sub-hierarchy; however,
+this may be limited explicitly in the future.
+
+
+Delegation Containment
+~~~~~~~~~~~~~~~~~~~~~~
+
+A delegated sub-hierarchy is contained in the sense that processes
+can't be moved into or out of the sub-hierarchy by the delegatee.
+
+For delegations to a less privileged user, this is achieved by
+requiring the following conditions for a process with a non-root euid
+to migrate a target process into a cgroup by writing its PID to the
+"cgroup.procs" file.
+
+- The writer must have write access to the "cgroup.procs" file.
+
+- The writer must have write access to the "cgroup.procs" file of the
+  common ancestor of the source and destination cgroups.
+
+The above two constraints ensure that while a delegatee may migrate
+processes around freely in the delegated sub-hierarchy it can't pull
+in from or push out to outside the sub-hierarchy.
+
+For an example, let's assume cgroups C0 and C1 have been delegated to
+user U0 who created C00, C01 under C0 and C10 under C1 as follows and
+all processes under C0 and C1 belong to U0::
+
+  ~~~~~~~~~~~~~ - C0 - C00
+  ~ cgroup    ~      \ C01
+  ~ hierarchy ~
+  ~~~~~~~~~~~~~ - C1 - C10
+
+Let's also say U0 wants to write the PID of a process which is
+currently in C10 into "C00/cgroup.procs".  U0 has write access to the
+file; however, the common ancestor of the source cgroup C10 and the
+destination cgroup C00 is above the points of delegation and U0 would
+not have write access to its "cgroup.procs" files and thus the write
+will be denied with -EACCES.
+
+For delegations to namespaces, containment is achieved by requiring
+that both the source and destination cgroups are reachable from the
+namespace of the process which is attempting the migration.  If either
+is not reachable, the migration is rejected with -ENOENT.
+
+
+Guidelines
+----------
+
+Organize Once and Control
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Migrating a process across cgroups is a relatively expensive operation
+and stateful resources such as memory are not moved together with the
+process.  This is an explicit design decision as there often exist
+inherent trade-offs between migration and various hot paths in terms
+of synchronization cost.
+
+As such, migrating processes across cgroups frequently as a means to
+apply different resource restrictions is discouraged.  A workload
+should be assigned to a cgroup according to the system's logical and
+resource structure once on start-up.  Dynamic adjustments to resource
+distribution can be made by changing controller configuration through
+the interface files.
+
+
+Avoid Name Collisions
+~~~~~~~~~~~~~~~~~~~~~
+
+Interface files for a cgroup and its children cgroups occupy the same
+directory and it is possible to create children cgroups which collide
+with interface files.
+
+All cgroup core interface files are prefixed with "cgroup." and each
+controller's interface files are prefixed with the controller name and
+a dot.  A controller's name is composed of lower case alphabets and
+'_'s but never begins with an '_' so it can be used as the prefix
+character for collision avoidance.  Also, interface file names won't
+start or end with terms which are often used in categorizing workloads
+such as job, service, slice, unit or workload.
+
+cgroup doesn't do anything to prevent name collisions and it's the
+user's responsibility to avoid them.
+
+
+Resource Distribution Models
+============================
+
+cgroup controllers implement several resource distribution schemes
+depending on the resource type and expected use cases.  This section
+describes major schemes in use along with their expected behaviors.
+
+
+Weights
+-------
+
+A parent's resource is distributed by adding up the weights of all
+active children and giving each the fraction matching the ratio of its
+weight against the sum.  As only children which can make use of the
+resource at the moment participate in the distribution, this is
+work-conserving.  Due to the dynamic nature, this model is usually
+used for stateless resources.
+
+All weights are in the range [1, 10000] with the default at 100.  This
+allows symmetric multiplicative biases in both directions at fine
+enough granularity while staying in the intuitive range.
+
+As long as the weight is in range, all configuration combinations are
+valid and there is no reason to reject configuration changes or
+process migrations.
+
+"cpu.weight" proportionally distributes CPU cycles to active children
+and is an example of this type.
+
+
+.. _cgroupv2-limits-distributor:
+
+Limits
+------
+
+A child can only consume up to the configured amount of the resource.
+Limits can be over-committed - the sum of the limits of children can
+exceed the amount of resource available to the parent.
+
+Limits are in the range [0, max] and defaults to "max", which is noop.
+
+As limits can be over-committed, all configuration combinations are
+valid and there is no reason to reject configuration changes or
+process migrations.
+
+"io.max" limits the maximum BPS and/or IOPS that a cgroup can consume
+on an IO device and is an example of this type.
+
+.. _cgroupv2-protections-distributor:
+
+Protections
+-----------
+
+A cgroup is protected up to the configured amount of the resource
+as long as the usages of all its ancestors are under their
+protected levels.  Protections can be hard guarantees or best effort
+soft boundaries.  Protections can also be over-committed in which case
+only up to the amount available to the parent is protected among
+children.
+
+Protections are in the range [0, max] and defaults to 0, which is
+noop.
+
+As protections can be over-committed, all configuration combinations
+are valid and there is no reason to reject configuration changes or
+process migrations.
+
+"memory.low" implements best-effort memory protection and is an
+example of this type.
+
+
+Allocations
+-----------
+
+A cgroup is exclusively allocated a certain amount of a finite
+resource.  Allocations can't be over-committed - the sum of the
+allocations of children can not exceed the amount of resource
+available to the parent.
+
+Allocations are in the range [0, max] and defaults to 0, which is no
+resource.
+
+As allocations can't be over-committed, some configuration
+combinations are invalid and should be rejected.  Also, if the
+resource is mandatory for execution of processes, process migrations
+may be rejected.
+
+
+Interface Files
+===============
+
+Format
+------
+
+All interface files should be in one of the following formats whenever
+possible::
+
+  New-line separated values
+  (when only one value can be written at once)
+
+	VAL0\n
+	VAL1\n
+	...
+
+  Space separated values
+  (when read-only or multiple values can be written at once)
+
+	VAL0 VAL1 ...\n
+
+  Flat keyed
+
+	KEY0 VAL0\n
+	KEY1 VAL1\n
+	...
+
+  Nested keyed
+
+	KEY0 SUB_KEY0=VAL00 SUB_KEY1=VAL01...
+	KEY1 SUB_KEY0=VAL10 SUB_KEY1=VAL11...
+	...
+
+For a writable file, the format for writing should generally match
+reading; however, controllers may allow omitting later fields or
+implement restricted shortcuts for most common use cases.
+
+For both flat and nested keyed files, only the values for a single key
+can be written at a time.  For nested keyed files, the sub key pairs
+may be specified in any order and not all pairs have to be specified.
+
+
+Conventions
+-----------
+
+- Settings for a single feature should be contained in a single file.
+
+- The root cgroup should be exempt from resource control and thus
+  shouldn't have resource control interface files.
+
+- The default time unit is microseconds.  If a different unit is ever
+  used, an explicit unit suffix must be present.
+
+- A parts-per quantity should use a percentage decimal with at least
+  two digit fractional part - e.g. 13.40.
+
+- If a controller implements weight based resource distribution, its
+  interface file should be named "weight" and have the range [1,
+  10000] with 100 as the default.  The values are chosen to allow
+  enough and symmetric bias in both directions while keeping it
+  intuitive (the default is 100%).
+
+- If a controller implements an absolute resource guarantee and/or
+  limit, the interface files should be named "min" and "max"
+  respectively.  If a controller implements best effort resource
+  guarantee and/or limit, the interface files should be named "low"
+  and "high" respectively.
+
+  In the above four control files, the special token "max" should be
+  used to represent upward infinity for both reading and writing.
+
+- If a setting has a configurable default value and keyed specific
+  overrides, the default entry should be keyed with "default" and
+  appear as the first entry in the file.
+
+  The default value can be updated by writing either "default $VAL" or
+  "$VAL".
+
+  When writing to update a specific override, "default" can be used as
+  the value to indicate removal of the override.  Override entries
+  with "default" as the value must not appear when read.
+
+  For example, a setting which is keyed by major:minor device numbers
+  with integer values may look like the following::
+
+    # cat cgroup-example-interface-file
+    default 150
+    8:0 300
+
+  The default value can be updated by::
+
+    # echo 125 > cgroup-example-interface-file
+
+  or::
+
+    # echo "default 125" > cgroup-example-interface-file
+
+  An override can be set by::
+
+    # echo "8:16 170" > cgroup-example-interface-file
+
+  and cleared by::
+
+    # echo "8:0 default" > cgroup-example-interface-file
+    # cat cgroup-example-interface-file
+    default 125
+    8:16 170
+
+- For events which are not very high frequency, an interface file
+  "events" should be created which lists event key value pairs.
+  Whenever a notifiable event happens, file modified event should be
+  generated on the file.
+
+
+Core Interface Files
+--------------------
+
+All cgroup core files are prefixed with "cgroup."
+
+  cgroup.type
+	A read-write single value file which exists on non-root
+	cgroups.
+
+	When read, it indicates the current type of the cgroup, which
+	can be one of the following values.
+
+	- "domain" : A normal valid domain cgroup.
+
+	- "domain threaded" : A threaded domain cgroup which is
+          serving as the root of a threaded subtree.
+
+	- "domain invalid" : A cgroup which is in an invalid state.
+	  It can't be populated or have controllers enabled.  It may
+	  be allowed to become a threaded cgroup.
+
+	- "threaded" : A threaded cgroup which is a member of a
+          threaded subtree.
+
+	A cgroup can be turned into a threaded cgroup by writing
+	"threaded" to this file.
+
+  cgroup.procs
+	A read-write new-line separated values file which exists on
+	all cgroups.
+
+	When read, it lists the PIDs of all processes which belong to
+	the cgroup one-per-line.  The PIDs are not ordered and the
+	same PID may show up more than once if the process got moved
+	to another cgroup and then back or the PID got recycled while
+	reading.
+
+	A PID can be written to migrate the process associated with
+	the PID to the cgroup.  The writer should match all of the
+	following conditions.
+
+	- It must have write access to the "cgroup.procs" file.
+
+	- It must have write access to the "cgroup.procs" file of the
+	  common ancestor of the source and destination cgroups.
+
+	When delegating a sub-hierarchy, write access to this file
+	should be granted along with the containing directory.
+
+	In a threaded cgroup, reading this file fails with EOPNOTSUPP
+	as all the processes belong to the thread root.  Writing is
+	supported and moves every thread of the process to the cgroup.
+
+  cgroup.threads
+	A read-write new-line separated values file which exists on
+	all cgroups.
+
+	When read, it lists the TIDs of all threads which belong to
+	the cgroup one-per-line.  The TIDs are not ordered and the
+	same TID may show up more than once if the thread got moved to
+	another cgroup and then back or the TID got recycled while
+	reading.
+
+	A TID can be written to migrate the thread associated with the
+	TID to the cgroup.  The writer should match all of the
+	following conditions.
+
+	- It must have write access to the "cgroup.threads" file.
+
+	- The cgroup that the thread is currently in must be in the
+          same resource domain as the destination cgroup.
+
+	- It must have write access to the "cgroup.procs" file of the
+	  common ancestor of the source and destination cgroups.
+
+	When delegating a sub-hierarchy, write access to this file
+	should be granted along with the containing directory.
+
+  cgroup.controllers
+	A read-only space separated values file which exists on all
+	cgroups.
+
+	It shows space separated list of all controllers available to
+	the cgroup.  The controllers are not ordered.
+
+  cgroup.subtree_control
+	A read-write space separated values file which exists on all
+	cgroups.  Starts out empty.
+
+	When read, it shows space separated list of the controllers
+	which are enabled to control resource distribution from the
+	cgroup to its children.
+
+	Space separated list of controllers prefixed with '+' or '-'
+	can be written to enable or disable controllers.  A controller
+	name prefixed with '+' enables the controller and '-'
+	disables.  If a controller appears more than once on the list,
+	the last one is effective.  When multiple enable and disable
+	operations are specified, either all succeed or all fail.
+
+  cgroup.events
+	A read-only flat-keyed file which exists on non-root cgroups.
+	The following entries are defined.  Unless specified
+	otherwise, a value change in this file generates a file
+	modified event.
+
+	  populated
+		1 if the cgroup or its descendants contains any live
+		processes; otherwise, 0.
+	  frozen
+		1 if the cgroup is frozen; otherwise, 0.
+
+  cgroup.max.descendants
+	A read-write single value files.  The default is "max".
+
+	Maximum allowed number of descent cgroups.
+	If the actual number of descendants is equal or larger,
+	an attempt to create a new cgroup in the hierarchy will fail.
+
+  cgroup.max.depth
+	A read-write single value files.  The default is "max".
+
+	Maximum allowed descent depth below the current cgroup.
+	If the actual descent depth is equal or larger,
+	an attempt to create a new child cgroup will fail.
+
+  cgroup.stat
+	A read-only flat-keyed file with the following entries:
+
+	  nr_descendants
+		Total number of visible descendant cgroups.
+
+	  nr_dying_descendants
+		Total number of dying descendant cgroups. A cgroup becomes
+		dying after being deleted by a user. The cgroup will remain
+		in dying state for some time undefined time (which can depend
+		on system load) before being completely destroyed.
+
+		A process can't enter a dying cgroup under any circumstances,
+		a dying cgroup can't revive.
+
+		A dying cgroup can consume system resources not exceeding
+		limits, which were active at the moment of cgroup deletion.
+
+	  nr_subsys_<cgroup_subsys>
+		Total number of live cgroup subsystems (e.g memory
+		cgroup) at and beneath the current cgroup.
+
+	  nr_dying_subsys_<cgroup_subsys>
+		Total number of dying cgroup subsystems (e.g. memory
+		cgroup) at and beneath the current cgroup.
+
+  cgroup.stat.local
+	A read-only flat-keyed file which exists in non-root cgroups.
+	The following entry is defined:
+
+	  frozen_usec
+		Cumulative time that this cgroup has spent between freezing and
+		thawing, regardless of whether by self or ancestor groups.
+		NB: (not) reaching "frozen" state is not accounted here.
+
+		Using the following ASCII representation of a cgroup's freezer
+		state, ::
+
+			       1    _____
+			frozen 0 __/     \__
+			          ab    cd
+
+		the duration being measured is the span between a and c.
+
+  cgroup.freeze
+	A read-write single value file which exists on non-root cgroups.
+	Allowed values are "0" and "1". The default is "0".
+
+	Writing "1" to the file causes freezing of the cgroup and all
+	descendant cgroups. This means that all belonging processes will
+	be stopped and will not run until the cgroup will be explicitly
+	unfrozen. Freezing of the cgroup may take some time; when this action
+	is completed, the "frozen" value in the cgroup.events control file
+	will be updated to "1" and the corresponding notification will be
+	issued.
+
+	A cgroup can be frozen either by its own settings, or by settings
+	of any ancestor cgroups. If any of ancestor cgroups is frozen, the
+	cgroup will remain frozen.
+
+	Processes in the frozen cgroup can be killed by a fatal signal.
+	They also can enter and leave a frozen cgroup: either by an explicit
+	move by a user, or if freezing of the cgroup races with fork().
+	If a process is moved to a frozen cgroup, it stops. If a process is
+	moved out of a frozen cgroup, it becomes running.
+
+	Frozen status of a cgroup doesn't affect any cgroup tree operations:
+	it's possible to delete a frozen (and empty) cgroup, as well as
+	create new sub-cgroups.
+
+  cgroup.kill
+	A write-only single value file which exists in non-root cgroups.
+	The only allowed value is "1".
+
+	Writing "1" to the file causes the cgroup and all descendant cgroups to
+	be killed. This means that all processes located in the affected cgroup
+	tree will be killed via SIGKILL.
+
+	Killing a cgroup tree will deal with concurrent forks appropriately and
+	is protected against migrations.
+
+	In a threaded cgroup, writing this file fails with EOPNOTSUPP as
+	killing cgroups is a process directed operation, i.e. it affects
+	the whole thread-group.
+
+  cgroup.pressure
+	A read-write single value file that allowed values are "0" and "1".
+	The default is "1".
+
+	Writing "0" to the file will disable the cgroup PSI accounting.
+	Writing "1" to the file will re-enable the cgroup PSI accounting.
+
+	This control attribute is not hierarchical, so disable or enable PSI
+	accounting in a cgroup does not affect PSI accounting in descendants
+	and doesn't need pass enablement via ancestors from root.
+
+	The reason this control attribute exists is that PSI accounts stalls for
+	each cgroup separately and aggregates it at each level of the hierarchy.
+	This may cause non-negligible overhead for some workloads when under
+	deep level of the hierarchy, in which case this control attribute can
+	be used to disable PSI accounting in the non-leaf cgroups.
+
+  irq.pressure
+	A read-write nested-keyed file.
+
+	Shows pressure stall information for IRQ/SOFTIRQ. See
+	:ref:`Documentation/accounting/psi.rst <psi>` for details.
+
+Controllers
+===========
+
+.. _cgroup-v2-cpu:
+
+CPU
+---
+
+The "cpu" controllers regulates distribution of CPU cycles.  This
+controller implements weight and absolute bandwidth limit models for
+normal scheduling policy and absolute bandwidth allocation model for
+realtime scheduling policy.
+
+In all the above models, cycles distribution is defined only on a temporal
+base and it does not account for the frequency at which tasks are executed.
+The (optional) utilization clamping support allows to hint the schedutil
+cpufreq governor about the minimum desired frequency which should always be
+provided by a CPU, as well as the maximum desired frequency, which should not
+be exceeded by a CPU.
+
+WARNING: cgroup2 cpu controller doesn't yet support the (bandwidth) control of
+realtime processes. For a kernel built with the CONFIG_RT_GROUP_SCHED option
+enabled for group scheduling of realtime processes, the cpu controller can only
+be enabled when all RT processes are in the root cgroup. Be aware that system
+management software may already have placed RT processes into non-root cgroups
+during the system boot process, and these processes may need to be moved to the
+root cgroup before the cpu controller can be enabled with a
+CONFIG_RT_GROUP_SCHED enabled kernel.
+
+With CONFIG_RT_GROUP_SCHED disabled, this limitation does not apply and some of
+the interface files either affect realtime processes or account for them. See
+the following section for details. Only the cpu controller is affected by
+CONFIG_RT_GROUP_SCHED. Other controllers can be used for the resource control of
+realtime processes irrespective of CONFIG_RT_GROUP_SCHED.
+
+
+CPU Interface Files
+~~~~~~~~~~~~~~~~~~~
+
+The interaction of a process with the cpu controller depends on its scheduling
+policy and the underlying scheduler. From the point of view of the cpu controller,
+processes can be categorized as follows:
+
+* Processes under the fair-class scheduler
+* Processes under a BPF scheduler with the ``cgroup_set_weight`` callback
+* Everything else: ``SCHED_{FIFO,RR,DEADLINE}`` and processes under a BPF scheduler
+  without the ``cgroup_set_weight`` callback
+
+For details on when a process is under the fair-class scheduler or a BPF scheduler,
+check out :ref:`Documentation/scheduler/sched-ext.rst <sched-ext>`.
+
+For each of the following interface files, the above categories
+will be referred to. All time durations are in microseconds.
+
+  cpu.stat
+	A read-only flat-keyed file.
+	This file exists whether the controller is enabled or not.
+
+	It always reports the following three stats, which account for all the
+	processes in the cgroup (including those in descendant cgroups):
+
+	- usage_usec
+	- user_usec
+	- system_usec
+
+	and the following five when the controller is enabled, which account for
+	only the processes under the fair-class scheduler:
+
+	- nr_periods
+	- nr_throttled
+	- throttled_usec
+	- nr_bursts
+	- burst_usec
+
+	Note that the above five CFS bandwidth stats are non-hierarchical;
+	they only account for throttling caused by this cgroup's own bandwidth
+	limit, not including throttling inherited from ancestor cgroups.
+
+  cpu.stat.local
+	A read-only flat-keyed file.
+	This file exists whether the controller is enabled or not.
+
+	It reports the following stat when the controller is enabled:
+
+	- throttled_usec
+
+	Unlike the ``throttled_usec`` reported by ``cpu.stat`` which
+	accounts for throttling caused by this cgroup's own CFS
+	bandwidth limit, ``cpu.stat.local`` reports the actual
+	throttling time incurred by this cgroup's own runqueues,
+	which may include throttling inherited from ancestor
+	cgroup bandwidth limits.
+
+	When the controller is not enabled, this stat is not reported.
+
+  cpu.weight
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "100".
+
+	For non idle groups (cpu.idle = 0), the weight is in the
+	range [1, 10000].
+
+	If the cgroup has been configured to be SCHED_IDLE (cpu.idle = 1),
+	then the weight will show as a 0.
+
+	This file affects only processes under the fair-class scheduler and a BPF
+	scheduler with the ``cgroup_set_weight`` callback depending on what the
+	callback actually does.
+
+  cpu.weight.nice
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "0".
+
+	The nice value is in the range [-20, 19].
+
+	This interface file is an alternative interface for
+	"cpu.weight" and allows reading and setting weight using the
+	same values used by nice(2).  Because the range is smaller and
+	granularity is coarser for the nice values, the read value is
+	the closest approximation of the current weight.
+
+	This file affects only processes under the fair-class scheduler and a BPF
+	scheduler with the ``cgroup_set_weight`` callback depending on what the
+	callback actually does.
+
+  cpu.max
+	A read-write two value file which exists on non-root cgroups.
+	The default is "max 100000".
+
+	The maximum bandwidth limit.  It's in the following format::
+
+	  $MAX $PERIOD
+
+	which indicates that the group may consume up to $MAX in each
+	$PERIOD duration.  "max" for $MAX indicates no limit.  If only
+	one number is written, $MAX is updated.
+
+	This file affects only processes under the fair-class scheduler.
+
+  cpu.max.burst
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "0".
+
+	The burst in the range [0, $MAX].
+
+	This file affects only processes under the fair-class scheduler.
+
+  cpu.pressure
+	A read-write nested-keyed file.
+
+	Shows pressure stall information for CPU. See
+	:ref:`Documentation/accounting/psi.rst <psi>` for details.
+
+	This file accounts for all the processes in the cgroup.
+
+  cpu.uclamp.min
+	A read-write single value file which exists on non-root cgroups.
+	The default is "0", i.e. no utilization boosting.
+
+	The requested minimum utilization (protection) as a percentage
+	rational number, e.g. 12.34 for 12.34%.
+
+	This interface allows reading and setting minimum utilization clamp
+	values similar to the sched_setattr(2). This minimum utilization
+	value is used to clamp the task specific minimum utilization clamp,
+	including those of realtime processes.
+
+	The requested minimum utilization (protection) is always capped by
+	the current value for the maximum utilization (limit), i.e.
+	`cpu.uclamp.max`.
+
+	This file affects all the processes in the cgroup.
+
+  cpu.uclamp.max
+	A read-write single value file which exists on non-root cgroups.
+	The default is "max". i.e. no utilization capping
+
+	The requested maximum utilization (limit) as a percentage rational
+	number, e.g. 98.76 for 98.76%.
+
+	This interface allows reading and setting maximum utilization clamp
+	values similar to the sched_setattr(2). This maximum utilization
+	value is used to clamp the task specific maximum utilization clamp,
+	including those of realtime processes.
+
+	This file affects all the processes in the cgroup.
+
+  cpu.idle
+	A read-write single value file which exists on non-root cgroups.
+	The default is 0.
+
+	This is the cgroup analog of the per-task SCHED_IDLE sched policy.
+	Setting this value to a 1 will make the scheduling policy of the
+	cgroup SCHED_IDLE. The threads inside the cgroup will retain their
+	own relative priorities, but the cgroup itself will be treated as
+	very low priority relative to its peers.
+
+	This file affects only processes under the fair-class scheduler.
+
+Memory
+------
+
+The "memory" controller regulates distribution of memory.  Memory is
+stateful and implements both limit and protection models.  Due to the
+intertwining between memory usage and reclaim pressure and the
+stateful nature of memory, the distribution model is relatively
+complex.
+
+While not completely water-tight, all major memory usages by a given
+cgroup are tracked so that the total memory consumption can be
+accounted and controlled to a reasonable extent.  Currently, the
+following types of memory usages are tracked.
+
+- Userland memory - page cache and anonymous memory.
+
+- Kernel data structures such as dentries and inodes.
+
+- TCP socket buffers.
+
+The above list may expand in the future for better coverage.
+
+
+Memory Interface Files
+~~~~~~~~~~~~~~~~~~~~~~
+
+All memory amounts are in bytes.  If a value which is not aligned to
+PAGE_SIZE is written, the value may be rounded up to the closest
+PAGE_SIZE multiple when read back.
+
+  memory.current
+	A read-only single value file which exists on non-root
+	cgroups.
+
+	The total amount of memory currently being used by the cgroup
+	and its descendants.
+
+  memory.min
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "0".
+
+	Hard memory protection.  If the memory usage of a cgroup
+	is within its effective min boundary, the cgroup's memory
+	won't be reclaimed under any conditions. If there is no
+	unprotected reclaimable memory available, OOM killer
+	is invoked. Above the effective min boundary (or
+	effective low boundary if it is higher), pages are reclaimed
+	proportionally to the overage, reducing reclaim pressure for
+	smaller overages.
+
+	Effective min boundary is limited by memory.min values of
+	ancestor cgroups. If there is memory.min overcommitment
+	(child cgroup or cgroups are requiring more protected memory
+	than parent will allow), then each child cgroup will get
+	the part of parent's protection proportional to its
+	actual memory usage below memory.min.
+
+	Putting more memory than generally available under this
+	protection is discouraged and may lead to constant OOMs.
+
+  memory.low
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "0".
+
+	Best-effort memory protection.  If the memory usage of a
+	cgroup is within its effective low boundary, the cgroup's
+	memory won't be reclaimed unless there is no reclaimable
+	memory available in unprotected cgroups.
+	Above the effective low	boundary (or 
+	effective min boundary if it is higher), pages are reclaimed
+	proportionally to the overage, reducing reclaim pressure for
+	smaller overages.
+
+	Effective low boundary is limited by memory.low values of
+	ancestor cgroups. If there is memory.low overcommitment
+	(child cgroup or cgroups are requiring more protected memory
+	than parent will allow), then each child cgroup will get
+	the part of parent's protection proportional to its
+	actual memory usage below memory.low.
+
+	Putting more memory than generally available under this
+	protection is discouraged.
+
+  memory.high
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Memory usage throttle limit.  If a cgroup's usage goes
+	over the high boundary, the processes of the cgroup are
+	throttled and put under heavy reclaim pressure.
+
+	Going over the high limit never invokes the OOM killer and
+	under extreme conditions the limit may be breached. The high
+	limit should be used in scenarios where an external process
+	monitors the limited cgroup to alleviate heavy reclaim
+	pressure.
+
+	If memory.high is opened with O_NONBLOCK then the synchronous
+	reclaim is bypassed. This is useful for admin processes that
+	need to dynamically adjust the job's memory limits without
+	expending their own CPU resources on memory reclamation. The
+	job will trigger the reclaim and/or get throttled on its
+	next charge request.
+
+	Please note that with O_NONBLOCK, there is a chance that the
+	target memory cgroup may take indefinite amount of time to
+	reduce usage below the limit due to delayed charge request or
+	busy-hitting its memory to slow down reclaim.
+
+  memory.max
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Memory usage hard limit.  This is the main mechanism to limit
+	memory usage of a cgroup.  If a cgroup's memory usage reaches
+	this limit and can't be reduced, the OOM killer is invoked in
+	the cgroup. Under certain circumstances, the usage may go
+	over the limit temporarily.
+
+	In default configuration regular 0-order allocations always
+	succeed unless OOM killer chooses current task as a victim.
+
+	Some kinds of allocations don't invoke the OOM killer.
+	Caller could retry them differently, return into userspace
+	as -ENOMEM or silently ignore in cases like disk readahead.
+
+	If memory.max is opened with O_NONBLOCK, then the synchronous
+	reclaim and oom-kill are bypassed. This is useful for admin
+	processes that need to dynamically adjust the job's memory limits
+	without expending their own CPU resources on memory reclamation.
+	The job will trigger the reclaim and/or oom-kill on its next
+	charge request.
+
+	Please note that with O_NONBLOCK, there is a chance that the
+	target memory cgroup may take indefinite amount of time to
+	reduce usage below the limit due to delayed charge request or
+	busy-hitting its memory to slow down reclaim.
+
+  memory.reclaim
+	A write-only nested-keyed file which exists for all cgroups.
+
+	This is a simple interface to trigger memory reclaim in the
+	target cgroup.
+
+	Example::
+
+	  echo "1G" > memory.reclaim
+
+	Please note that the kernel can over or under reclaim from
+	the target cgroup. If less bytes are reclaimed than the
+	specified amount, -EAGAIN is returned.
+
+	Please note that the proactive reclaim (triggered by this
+	interface) is not meant to indicate memory pressure on the
+	memory cgroup. Therefore socket memory balancing triggered by
+	the memory reclaim normally is not exercised in this case.
+	This means that the networking layer will not adapt based on
+	reclaim induced by memory.reclaim.
+
+The following nested keys are defined.
+
+	  ==========            ================================
+	  swappiness            Swappiness value to reclaim with
+	  ==========            ================================
+
+	Specifying a swappiness value instructs the kernel to perform
+	the reclaim with that swappiness value. Note that this has the
+	same semantics as vm.swappiness applied to memcg reclaim with
+	all the existing limitations and potential future extensions.
+
+	The valid range for swappiness is [0-200, max], setting
+	swappiness=max exclusively reclaims anonymous memory.
+
+  memory.peak
+	A read-write single value file which exists on non-root cgroups.
+
+	The max memory usage recorded for the cgroup and its descendants since
+	either the creation of the cgroup or the most recent reset for that FD.
+
+	A write of any non-empty string to this file resets it to the
+	current memory usage for subsequent reads through the same
+	file descriptor.
+
+  memory.oom.group
+	A read-write single value file which exists on non-root
+	cgroups.  The default value is "0".
+
+	Determines whether the cgroup should be treated as
+	an indivisible workload by the OOM killer. If set,
+	all tasks belonging to the cgroup or to its descendants
+	(if the memory cgroup is not a leaf cgroup) are killed
+	together or not at all. This can be used to avoid
+	partial kills to guarantee workload integrity.
+
+	Tasks with the OOM protection (oom_score_adj set to -1000)
+	are treated as an exception and are never killed.
+
+	If the OOM killer is invoked in a cgroup, it's not going
+	to kill any tasks outside of this cgroup, regardless
+	memory.oom.group values of ancestor cgroups.
+
+  memory.events
+	A read-only flat-keyed file which exists on non-root cgroups.
+	The following entries are defined.  Unless specified
+	otherwise, a value change in this file generates a file
+	modified event.
+
+	Note that all fields in this file are hierarchical and the
+	file modified event can be generated due to an event down the
+	hierarchy. For the local events at the cgroup level see
+	memory.events.local.
+
+	  low
+		The number of times the cgroup is reclaimed due to
+		high memory pressure even though its usage is under
+		the low boundary.  This usually indicates that the low
+		boundary is over-committed.
+
+	  high
+		The number of times processes of the cgroup are
+		throttled and routed to perform direct memory reclaim
+		because the high memory boundary was exceeded.  For a
+		cgroup whose memory usage is capped by the high limit
+		rather than global memory pressure, this event's
+		occurrences are expected.
+
+	  max
+		The number of times the cgroup's memory usage was
+		about to go over the max boundary.  If direct reclaim
+		fails to bring it down, the cgroup goes to OOM state.
+
+	  oom
+		The number of time the cgroup's memory usage was
+		reached the limit and allocation was about to fail.
+
+		This event is not raised if the OOM killer is not
+		considered as an option, e.g. for failed high-order
+		allocations or if caller asked to not retry attempts.
+
+	  oom_kill
+		The number of processes belonging to this cgroup
+		killed by any kind of OOM killer.
+
+          oom_group_kill
+                The number of times a group OOM has occurred.
+
+          sock_throttled
+                The number of times network sockets associated with
+                this cgroup are throttled.
+
+  memory.events.local
+	Similar to memory.events but the fields in the file are local
+	to the cgroup i.e. not hierarchical. The file modified event
+	generated on this file reflects only the local events.
+
+  memory.stat
+	A read-only flat-keyed file which exists on non-root cgroups.
+
+	This breaks down the cgroup's memory footprint into different
+	types of memory, type-specific details, and other information
+	on the state and past events of the memory management system.
+
+	All memory amounts are in bytes.
+
+	The entries are ordered to be human readable, and new entries
+	can show up in the middle. Don't rely on items remaining in a
+	fixed position; use the keys to look up specific values!
+
+	If the entry has no per-node counter (or not show in the
+	memory.numa_stat). We use 'npn' (non-per-node) as the tag
+	to indicate that it will not show in the memory.numa_stat.
+
+	  anon
+		Amount of memory used in anonymous mappings such as
+		brk(), sbrk(), and mmap(MAP_ANONYMOUS). Note that
+		some kernel configurations might account complete larger
+		allocations (e.g., THP) if only some, but not all the
+		memory of such an allocation is mapped anymore.
+
+	  file
+		Amount of memory used to cache filesystem data,
+		including tmpfs and shared memory.
+
+	  kernel (npn)
+		Amount of total kernel memory, including
+		(kernel_stack, pagetables, percpu, vmalloc, slab) in
+		addition to other kernel memory use cases.
+
+	  kernel_stack
+		Amount of memory allocated to kernel stacks.
+
+	  pagetables
+                Amount of memory allocated for page tables.
+
+	  sec_pagetables
+		Amount of memory allocated for secondary page tables,
+		this currently includes KVM mmu allocations on x86
+		and arm64 and IOMMU page tables.
+
+	  percpu (npn)
+		Amount of memory used for storing per-cpu kernel
+		data structures.
+
+	  sock (npn)
+		Amount of memory used in network transmission buffers
+
+	  vmalloc
+		Amount of memory used for vmap backed memory.
+
+	  shmem
+		Amount of cached filesystem data that is swap-backed,
+		such as tmpfs, shm segments, shared anonymous mmap()s
+
+	  zswap
+		Amount of memory consumed by the zswap compression backend.
+
+	  zswapped
+		Amount of application memory swapped out to zswap.
+
+	  file_mapped
+		Amount of cached filesystem data mapped with mmap(). Note
+		that some kernel configurations might account complete
+		larger allocations (e.g., THP) if only some, but not
+		not all the memory of such an allocation is mapped.
+
+	  file_dirty
+		Amount of cached filesystem data that was modified but
+		not yet written back to disk
+
+	  file_writeback
+		Amount of cached filesystem data that was modified and
+		is currently being written back to disk
+
+	  swapcached
+		Amount of swap cached in memory. The swapcache is accounted
+		against both memory and swap usage.
+
+	  anon_thp
+		Amount of memory used in anonymous mappings backed by
+		transparent hugepages
+
+	  file_thp
+		Amount of cached filesystem data backed by transparent
+		hugepages
+
+	  shmem_thp
+		Amount of shm, tmpfs, shared anonymous mmap()s backed by
+		transparent hugepages
+
+	  inactive_anon, active_anon, inactive_file, active_file, unevictable
+		Amount of memory, swap-backed and filesystem-backed,
+		on the internal memory management lists used by the
+		page reclaim algorithm.
+
+		As these represent internal list state (eg. shmem pages are on anon
+		memory management lists), inactive_foo + active_foo may not be equal to
+		the value for the foo counter, since the foo counter is type-based, not
+		list-based.
+
+	  slab_reclaimable
+		Part of "slab" that might be reclaimed, such as
+		dentries and inodes.
+
+	  slab_unreclaimable
+		Part of "slab" that cannot be reclaimed on memory
+		pressure.
+
+	  slab (npn)
+		Amount of memory used for storing in-kernel data
+		structures.
+
+	  workingset_refault_anon
+		Number of refaults of previously evicted anonymous pages.
+
+	  workingset_refault_file
+		Number of refaults of previously evicted file pages.
+
+	  workingset_activate_anon
+		Number of refaulted anonymous pages that were immediately
+		activated.
+
+	  workingset_activate_file
+		Number of refaulted file pages that were immediately activated.
+
+	  workingset_restore_anon
+		Number of restored anonymous pages which have been detected as
+		an active workingset before they got reclaimed.
+
+	  workingset_restore_file
+		Number of restored file pages which have been detected as an
+		active workingset before they got reclaimed.
+
+	  workingset_nodereclaim
+		Number of times a shadow node has been reclaimed
+
+	  pswpin (npn)
+		Number of pages swapped into memory
+
+	  pswpout (npn)
+		Number of pages swapped out of memory
+
+	  pgscan (npn)
+		Amount of scanned pages (in an inactive LRU list)
+
+	  pgsteal (npn)
+		Amount of reclaimed pages
+
+	  pgscan_kswapd (npn)
+		Amount of scanned pages by kswapd (in an inactive LRU list)
+
+	  pgscan_direct (npn)
+		Amount of scanned pages directly  (in an inactive LRU list)
+
+	  pgscan_khugepaged (npn)
+		Amount of scanned pages by khugepaged  (in an inactive LRU list)
+
+	  pgscan_proactive (npn)
+		Amount of scanned pages proactively (in an inactive LRU list)
+
+	  pgsteal_kswapd (npn)
+		Amount of reclaimed pages by kswapd
+
+	  pgsteal_direct (npn)
+		Amount of reclaimed pages directly
+
+	  pgsteal_khugepaged (npn)
+		Amount of reclaimed pages by khugepaged
+
+	  pgsteal_proactive (npn)
+		Amount of reclaimed pages proactively
+
+	  pgfault (npn)
+		Total number of page faults incurred
+
+	  pgmajfault (npn)
+		Number of major page faults incurred
+
+	  pgrefill (npn)
+		Amount of scanned pages (in an active LRU list)
+
+	  pgactivate (npn)
+		Amount of pages moved to the active LRU list
+
+	  pgdeactivate (npn)
+		Amount of pages moved to the inactive LRU list
+
+	  pglazyfree (npn)
+		Amount of pages postponed to be freed under memory pressure
+
+	  pglazyfreed (npn)
+		Amount of reclaimed lazyfree pages
+
+	  swpin_zero
+		Number of pages swapped into memory and filled with zero, where I/O
+		was optimized out because the page content was detected to be zero
+		during swapout.
+
+	  swpout_zero
+		Number of zero-filled pages swapped out with I/O skipped due to the
+		content being detected as zero.
+
+	  zswpin
+		Number of pages moved in to memory from zswap.
+
+	  zswpout
+		Number of pages moved out of memory to zswap.
+
+	  zswpwb
+		Number of pages written from zswap to swap.
+
+	  zswap_incomp
+		Amount of memory used by incompressible pages currently stored in zswap
+		without compression. These pages could not be compressed to
+		a size smaller than PAGE_SIZE, so they are stored as-is.
+
+	  thp_fault_alloc (npn)
+		Number of transparent hugepages which were allocated to satisfy
+		a page fault. This counter is not present when CONFIG_TRANSPARENT_HUGEPAGE
+                is not set.
+
+	  thp_collapse_alloc (npn)
+		Number of transparent hugepages which were allocated to allow
+		collapsing an existing range of pages. This counter is not
+		present when CONFIG_TRANSPARENT_HUGEPAGE is not set.
+
+	  thp_swpout (npn)
+		Number of transparent hugepages which are swapout in one piece
+		without splitting.
+
+	  thp_swpout_fallback (npn)
+		Number of transparent hugepages which were split before swapout.
+		Usually because failed to allocate some continuous swap space
+		for the huge page.
+
+	  numa_pages_migrated (npn)
+		Number of pages migrated by NUMA balancing.
+
+	  numa_pte_updates (npn)
+		Number of pages whose page table entries are modified by
+		NUMA balancing to produce NUMA hinting faults on access.
+
+	  numa_hint_faults (npn)
+		Number of NUMA hinting faults.
+
+	  pgdemote_kswapd
+		Number of pages demoted by kswapd.
+
+	  pgdemote_direct
+		Number of pages demoted directly.
+
+	  pgdemote_khugepaged
+		Number of pages demoted by khugepaged.
+
+	  pgdemote_proactive
+		Number of pages demoted by proactively.
+
+	  hugetlb
+		Amount of memory used by hugetlb pages. This metric only shows
+		up if hugetlb usage is accounted for in memory.current (i.e.
+		cgroup is mounted with the memory_hugetlb_accounting option).
+
+  memory.numa_stat
+	A read-only nested-keyed file which exists on non-root cgroups.
+
+	This breaks down the cgroup's memory footprint into different
+	types of memory, type-specific details, and other information
+	per node on the state of the memory management system.
+
+	This is useful for providing visibility into the NUMA locality
+	information within an memcg since the pages are allowed to be
+	allocated from any physical node. One of the use case is evaluating
+	application performance by combining this information with the
+	application's CPU allocation.
+
+	All memory amounts are in bytes.
+
+	The output format of memory.numa_stat is::
+
+	  type N0=<bytes in node 0> N1=<bytes in node 1> ...
+
+	The entries are ordered to be human readable, and new entries
+	can show up in the middle. Don't rely on items remaining in a
+	fixed position; use the keys to look up specific values!
+
+	The entries can refer to the memory.stat.
+
+  memory.swap.current
+	A read-only single value file which exists on non-root
+	cgroups.
+
+	The total amount of swap currently being used by the cgroup
+	and its descendants.
+
+  memory.swap.high
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Swap usage throttle limit.  If a cgroup's swap usage exceeds
+	this limit, all its further allocations will be throttled to
+	allow userspace to implement custom out-of-memory procedures.
+
+	This limit marks a point of no return for the cgroup. It is NOT
+	designed to manage the amount of swapping a workload does
+	during regular operation. Compare to memory.swap.max, which
+	prohibits swapping past a set amount, but lets the cgroup
+	continue unimpeded as long as other memory can be reclaimed.
+
+	Healthy workloads are not expected to reach this limit.
+
+  memory.swap.peak
+	A read-write single value file which exists on non-root cgroups.
+
+	The max swap usage recorded for the cgroup and its descendants since
+	the creation of the cgroup or the most recent reset for that FD.
+
+	A write of any non-empty string to this file resets it to the
+	current memory usage for subsequent reads through the same
+	file descriptor.
+
+  memory.swap.max
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Swap usage hard limit.  If a cgroup's swap usage reaches this
+	limit, anonymous memory of the cgroup will not be swapped out.
+
+  memory.swap.events
+	A read-only flat-keyed file which exists on non-root cgroups.
+	The following entries are defined.  Unless specified
+	otherwise, a value change in this file generates a file
+	modified event.
+
+	  high
+		The number of times the cgroup's swap usage was over
+		the high threshold.
+
+	  max
+		The number of times the cgroup's swap usage was about
+		to go over the max boundary and swap allocation
+		failed.
+
+	  fail
+		The number of times swap allocation failed either
+		because of running out of swap system-wide or max
+		limit.
+
+	When reduced under the current usage, the existing swap
+	entries are reclaimed gradually and the swap usage may stay
+	higher than the limit for an extended period of time.  This
+	reduces the impact on the workload and memory management.
+
+  memory.zswap.current
+	A read-only single value file which exists on non-root
+	cgroups.
+
+	The total amount of memory consumed by the zswap compression
+	backend.
+
+  memory.zswap.max
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Zswap usage hard limit. If a cgroup's zswap pool reaches this
+	limit, it will refuse to take any more stores before existing
+	entries fault back in or are written out to disk.
+
+  memory.zswap.writeback
+	A read-write single value file. The default value is "1".
+	Note that this setting is hierarchical, i.e. the writeback would be
+	implicitly disabled for child cgroups if the upper hierarchy
+	does so.
+
+	When this is set to 0, all swapping attempts to swapping devices
+	are disabled. This included both zswap writebacks, and swapping due
+	to zswap store failures. If the zswap store failures are recurring
+	(for e.g if the pages are incompressible), users can observe
+	reclaim inefficiency after disabling writeback (because the same
+	pages might be rejected again and again).
+
+	Note that this is subtly different from setting memory.swap.max to
+	0, as it still allows for pages to be written to the zswap pool.
+	This setting has no effect if zswap is disabled, and swapping
+	is allowed unless memory.swap.max is set to 0.
+
+  memory.pressure
+	A read-write nested-keyed file.
+
+	Shows pressure stall information for memory. See
+	:ref:`Documentation/accounting/psi.rst <psi>` for details.
+
+
+Usage Guidelines
+~~~~~~~~~~~~~~~~
+
+"memory.high" is the main mechanism to control memory usage.
+Over-committing on high limit (sum of high limits > available memory)
+and letting global memory pressure to distribute memory according to
+usage is a viable strategy.
+
+Because breach of the high limit doesn't trigger the OOM killer but
+throttles the offending cgroup, a management agent has ample
+opportunities to monitor and take appropriate actions such as granting
+more memory or terminating the workload.
+
+Determining whether a cgroup has enough memory is not trivial as
+memory usage doesn't indicate whether the workload can benefit from
+more memory.  For example, a workload which writes data received from
+network to a file can use all available memory but can also operate as
+performant with a small amount of memory.  A measure of memory
+pressure - how much the workload is being impacted due to lack of
+memory - is necessary to determine whether a workload needs more
+memory; unfortunately, memory pressure monitoring mechanism isn't
+implemented yet.
+
+Reclaim Protection
+~~~~~~~~~~~~~~~~~~
+
+The protection configured with "memory.low" or "memory.min" applies relatively
+to the target of the reclaim (i.e. any of memory cgroup limits, proactive
+memory.reclaim or global reclaim apparently located in the root cgroup).
+The protection value configured for B applies unchanged to the reclaim
+targeting A (i.e. caused by competition with the sibling E)::
+
+		root - ... - A - B - C
+		              \    ` D
+		               ` E
+
+When the reclaim targets ancestors of A, the effective protection of B is
+capped by the protection value configured for A (and any other intermediate
+ancestors between A and the target).
+
+To express indifference about relative sibling protection, it is suggested to
+use memory_recursiveprot. Configuring all descendants of a parent with finite
+protection to "max" works but it may unnecessarily skew memory.events:low
+field.
+
+Memory Ownership
+~~~~~~~~~~~~~~~~
+
+A memory area is charged to the cgroup which instantiated it and stays
+charged to the cgroup until the area is released.  Migrating a process
+to a different cgroup doesn't move the memory usages that it
+instantiated while in the previous cgroup to the new cgroup.
+
+A memory area may be used by processes belonging to different cgroups.
+To which cgroup the area will be charged is in-deterministic; however,
+over time, the memory area is likely to end up in a cgroup which has
+enough memory allowance to avoid high reclaim pressure.
+
+If a cgroup sweeps a considerable amount of memory which is expected
+to be accessed repeatedly by other cgroups, it may make sense to use
+POSIX_FADV_DONTNEED to relinquish the ownership of memory areas
+belonging to the affected files to ensure correct memory ownership.
+
+
+IO
+--
+
+The "io" controller regulates the distribution of IO resources.  This
+controller implements both weight based and absolute bandwidth or IOPS
+limit distribution.  Absolute BPS and IOPS limits are enforced by
+blk-throttle and apply to all devices, while weight based proportional
+distribution is provided by the iocost cost model controller
+(CONFIG_BLK_CGROUP_IOCOST) and, when the BFQ I/O scheduler is in use
+for a device, by BFQ's own cgroup support.  Latency-based protection
+(CONFIG_BLK_CGROUP_IOLATENCY) and I/O priority assignment
+(CONFIG_BLK_CGROUP_IOPRIO) are also available.
+
+
+IO Interface Files
+~~~~~~~~~~~~~~~~~~
+
+  io.stat
+	A read-only nested-keyed file.
+
+	Lines are keyed by $MAJ:$MIN device numbers and not ordered.
+	The following nested keys are defined.
+
+	  ======	=====================
+	  rbytes	Bytes read
+	  wbytes	Bytes written
+	  rios		Number of read IOs
+	  wios		Number of write IOs
+	  dbytes	Bytes discarded
+	  dios		Number of discard IOs
+	  ======	=====================
+
+	An example read output follows::
+
+	  8:16 rbytes=1459200 wbytes=314773504 rios=192 wios=353 dbytes=0 dios=0
+	  8:0 rbytes=90430464 wbytes=299008000 rios=8950 wios=1252 dbytes=50331648 dios=3021
+
+  io.cost.qos
+	A read-write nested-keyed file which exists only on the root
+	cgroup.
+
+	This file configures the Quality of Service of the IO cost
+	model based controller (CONFIG_BLK_CGROUP_IOCOST) which
+	currently implements "io.weight" proportional control.  Lines
+	are keyed by $MAJ:$MIN device numbers and not ordered.  The
+	line for a given device is populated on the first write for
+	the device on "io.cost.qos" or "io.cost.model".  The following
+	nested keys are defined.
+
+	  ======	=====================================
+	  enable	Weight-based control enable
+	  ctrl		"auto" or "user"
+	  rpct		Read latency percentile    [0, 100]
+	  rlat		Read latency threshold
+	  wpct		Write latency percentile   [0, 100]
+	  wlat		Write latency threshold
+	  min		Minimum scaling percentage [1, 10000]
+	  max		Maximum scaling percentage [1, 10000]
+	  ======	=====================================
+
+	The controller is disabled by default and can be enabled by
+	setting "enable" to 1.  "rpct" and "wpct" parameters default
+	to zero and the controller uses internal device saturation
+	state to adjust the overall IO rate between "min" and "max".
+
+	When a better control quality is needed, latency QoS
+	parameters can be configured.  For example::
+
+	  8:16 enable=1 ctrl=auto rpct=95.00 rlat=75000 wpct=95.00 wlat=150000 min=50.00 max=150.0
+
+	shows that on sdb, the controller is enabled, will consider
+	the device saturated if the 95th percentile of read completion
+	latencies is above 75ms or write 150ms, and adjust the overall
+	IO issue rate between 50% and 150% accordingly.
+
+	The lower the saturation point, the better the latency QoS at
+	the cost of aggregate bandwidth.  The narrower the allowed
+	adjustment range between "min" and "max", the more conformant
+	to the cost model the IO behavior.  Note that the IO issue
+	base rate may be far off from 100% and setting "min" and "max"
+	blindly can lead to a significant loss of device capacity or
+	control quality.  "min" and "max" are useful for regulating
+	devices which show wide temporary behavior changes - e.g. a
+	ssd which accepts writes at the line speed for a while and
+	then completely stalls for multiple seconds.
+
+	When "ctrl" is "auto", the parameters are controlled by the
+	kernel and may change automatically.  Setting "ctrl" to "user"
+	or setting any of the percentile and latency parameters puts
+	it into "user" mode and disables the automatic changes.  The
+	automatic mode can be restored by setting "ctrl" to "auto".
+
+  io.cost.model
+	A read-write nested-keyed file which exists only on the root
+	cgroup.
+
+	This file configures the cost model of the IO cost model based
+	controller (CONFIG_BLK_CGROUP_IOCOST) which currently
+	implements "io.weight" proportional control.  Lines are keyed
+	by $MAJ:$MIN device numbers and not ordered.  The line for a
+	given device is populated on the first write for the device on
+	"io.cost.qos" or "io.cost.model".  The following nested keys
+	are defined.
+
+	  =====		================================
+	  ctrl		"auto" or "user"
+	  model		The cost model in use - "linear"
+	  =====		================================
+
+	When "ctrl" is "auto", the kernel may change all parameters
+	dynamically.  When "ctrl" is set to "user" or any other
+	parameters are written to, "ctrl" become "user" and the
+	automatic changes are disabled.
+
+	When "model" is "linear", the following model parameters are
+	defined.
+
+	  =============	========================================
+	  [r|w]bps	The maximum sequential IO throughput
+	  [r|w]seqiops	The maximum 4k sequential IOs per second
+	  [r|w]randiops	The maximum 4k random IOs per second
+	  =============	========================================
+
+	From the above, the builtin linear model determines the base
+	costs of a sequential and random IO and the cost coefficient
+	for the IO size.  While simple, this model can cover most
+	common device classes acceptably.
+
+	The IO cost model isn't expected to be accurate in absolute
+	sense and is scaled to the device behavior dynamically.
+
+	If needed, tools/cgroup/iocost_coef_gen.py can be used to
+	generate device-specific coefficients.
+
+  io.weight
+	A read-write flat-keyed file which exists on non-root cgroups.
+	The default is "default 100".
+
+	The first line is the default weight applied to devices
+	without specific override.  The rest are overrides keyed by
+	$MAJ:$MIN device numbers and not ordered.  The weights are in
+	the range [1, 10000] and specifies the relative amount IO time
+	the cgroup can use in relation to its siblings.
+
+	The default weight can be updated by writing either "default
+	$WEIGHT" or simply "$WEIGHT".  Overrides can be set by writing
+	"$MAJ:$MIN $WEIGHT" and unset by writing "$MAJ:$MIN default".
+
+	An example read output follows::
+
+	  default 100
+	  8:16 200
+	  8:0 50
+
+  io.max
+	A read-write nested-keyed file which exists on non-root
+	cgroups.
+
+	BPS and IOPS based IO limit.  Lines are keyed by $MAJ:$MIN
+	device numbers and not ordered.  The following nested keys are
+	defined.
+
+	  =====		==================================
+	  rbps		Max read bytes per second
+	  wbps		Max write bytes per second
+	  riops		Max read IO operations per second
+	  wiops		Max write IO operations per second
+	  =====		==================================
+
+	When writing, any number of nested key-value pairs can be
+	specified in any order.  "max" can be specified as the value
+	to remove a specific limit.  If the same key is specified
+	multiple times, the outcome is undefined.
+
+	BPS and IOPS are measured in each IO direction and IOs are
+	delayed if limit is reached.  Temporary bursts are allowed.
+
+	Setting read limit at 2M BPS and write at 120 IOPS for 8:16::
+
+	  echo "8:16 rbps=2097152 wiops=120" > io.max
+
+	Reading returns the following::
+
+	  8:16 rbps=2097152 wbps=max riops=max wiops=120
+
+	Write IOPS limit can be removed by writing the following::
+
+	  echo "8:16 wiops=max" > io.max
+
+	Reading now returns the following::
+
+	  8:16 rbps=2097152 wbps=max riops=max wiops=max
+
+  io.pressure
+	A read-write nested-keyed file.
+
+	Shows pressure stall information for IO. See
+	:ref:`Documentation/accounting/psi.rst <psi>` for details.
+
+
+Writeback
+~~~~~~~~~
+
+Page cache is dirtied through buffered writes and shared mmaps and
+written asynchronously to the backing filesystem by the writeback
+mechanism.  Writeback sits between the memory and IO domains and
+regulates the proportion of dirty memory by balancing dirtying and
+write IOs.
+
+The io controller, in conjunction with the memory controller,
+implements control of page cache writeback IOs.  The memory controller
+defines the memory domain that dirty memory ratio is calculated and
+maintained for and the io controller defines the io domain which
+writes out dirty pages for the memory domain.  Both system-wide and
+per-cgroup dirty memory states are examined and the more restrictive
+of the two is enforced.
+
+cgroup writeback requires explicit support from the underlying
+filesystem.  Currently, cgroup writeback is implemented on ext2, ext4,
+btrfs, f2fs, and xfs.  On other filesystems, all writeback IOs are 
+attributed to the root cgroup.
+
+There are inherent differences in memory and writeback management
+which affects how cgroup ownership is tracked.  Memory is tracked per
+page while writeback per inode.  For the purpose of writeback, an
+inode is assigned to a cgroup and all IO requests to write dirty pages
+from the inode are attributed to that cgroup.
+
+As cgroup ownership for memory is tracked per page, there can be pages
+which are associated with different cgroups than the one the inode is
+associated with.  These are called foreign pages.  The writeback
+constantly keeps track of foreign pages and, if a particular foreign
+cgroup becomes the majority over a certain period of time, switches
+the ownership of the inode to that cgroup.
+
+While this model is enough for most use cases where a given inode is
+mostly dirtied by a single cgroup even when the main writing cgroup
+changes over time, use cases where multiple cgroups write to a single
+inode simultaneously are not supported well.  In such circumstances, a
+significant portion of IOs are likely to be attributed incorrectly.
+As memory controller assigns page ownership on the first use and
+doesn't update it until the page is released, even if writeback
+strictly follows page ownership, multiple cgroups dirtying overlapping
+areas wouldn't work as expected.  It's recommended to avoid such usage
+patterns.
+
+The sysctl knobs which affect writeback behavior are applied to cgroup
+writeback as follows.
+
+  vm.dirty_background_ratio, vm.dirty_ratio
+	These ratios apply the same to cgroup writeback with the
+	amount of available memory capped by limits imposed by the
+	memory controller and system-wide clean memory.
+
+  vm.dirty_background_bytes, vm.dirty_bytes
+	For cgroup writeback, this is calculated into ratio against
+	total available memory and applied the same way as
+	vm.dirty[_background]_ratio.
+
+
+IO Latency
+~~~~~~~~~~
+
+This is a cgroup v2 controller for IO workload protection.  You provide a group
+with a latency target, and if the group misses its target the controller will
+throttle any peers that have a lower latency target than the protected
+workload.  How a miss is detected depends on the device: on rotational devices
+the average latency over the window must exceed the target, while on
+non-rotational devices a miss is counted once enough of the IOs in the window
+individually exceed the target.
+
+The limits are only applied at the peer level in the hierarchy.  This means that
+in the diagram below, only groups A, B, and C will influence each other, and
+groups D and F will influence each other.  Group G will influence nobody::
+
+			[root]
+		/	   |		\
+		A	   B		C
+	       /  \        |
+	      D    F	   G
+
+
+So the ideal way to configure this is to set io.latency in groups A, B, and C.
+Generally you do not want to set a value lower than the latency your device
+supports.  Experiment to find the value that works best for your workload.
+Start at higher than the expected latency for your device and, with
+blkcg_debug_stats enabled, observe io.stat for your workload group to get an
+idea of the latency you see during normal operation.  On rotational devices,
+use the avg_lat value as a basis for your real setting, setting it 10-15%
+higher.  On non-rotational devices io.stat reports no average latency; set
+the target based on your device and use the missed/total fields to verify it
+is being met.
+
+How IO Latency Throttling Works
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+io.latency is work conserving; so as long as everybody is meeting their latency
+target the controller doesn't do anything.  Once a group starts missing its
+target it begins throttling any peer group that has a higher target than itself.
+This throttling takes 2 forms:
+
+- Queue depth throttling.  This is the number of outstanding IO's a group is
+  allowed to have.  We will clamp down relatively quickly, starting at no limit
+  and going all the way down to 1 IO at a time.
+
+- Artificial delay induction.  There are certain types of IO that cannot be
+  throttled without possibly adversely affecting higher priority groups.  This
+  includes swapping and metadata IO.  These types of IO are allowed to occur
+  normally, however they are "charged" to the originating group.  If the
+  originating group is being throttled you will see the use_delay and delay_nsec
+  fields in io.stat increase.  The delay_nsec value is how many nanoseconds that
+  are being added to any process that runs in this group.  Because this number can
+  grow quite large if there is a lot of swapping or metadata IO occurring we
+  limit the individual delay events to 1 second at a time.
+
+Once the victimized group starts meeting its latency target again it will start
+unthrottling any peer groups that were throttled previously.  If the victimized
+group simply stops doing IO the global counter will unthrottle appropriately.
+
+IO Latency Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  io.latency
+	This takes a similar format as the other controllers.
+
+		"MAJOR:MINOR target=<target time in microseconds>"
+
+  io.stat
+	If the controller is enabled you will see extra stats in io.stat in
+	addition to the normal ones.  These debug stats are only emitted when
+	the blkcg_debug_stats module parameter is enabled (it is disabled by
+	default).
+
+	The reported latency fields depend on the device.  Rotational devices
+	report avg_lat and win; non-rotational devices report missed and total
+	instead.  missed and total are live counters for the current window and
+	may change between reads.
+
+	  depth
+		This is the current queue depth for the group.
+
+	  avg_lat
+		(Rotational devices only.)  This is an exponential moving
+		average with a decay rate of 1/exp bound by the sampling
+		interval.  The decay rate interval can be calculated by
+		multiplying the win value in io.stat by the corresponding number
+		of samples based on the win value.
+
+	  win
+		(Rotational devices only.)  The sampling window size in
+		milliseconds.  This is the minimum duration of time between
+		evaluation events.  Windows only elapse with IO activity.  Idle
+		periods extend the most recent window.
+
+	  missed
+		(Non-rotational devices only.)  The number of IOs in the
+		current window whose latency exceeded the target.  A group is
+		considered to be missing its target once missed reaches a
+		certain ratio of total.
+
+	  total
+		(Non-rotational devices only.)  The total number of IOs
+		accounted in the current window.
+
+IO Priority
+~~~~~~~~~~~
+
+A single attribute controls the behavior of the I/O priority cgroup policy,
+namely the io.prio.class attribute. The following values are accepted for
+that attribute:
+
+  no-change
+	Do not modify the I/O priority class.
+
+  promote-to-rt
+	For requests that have a non-RT I/O priority class, change it into RT.
+	Also change the priority level of these requests to 4. Do not modify
+	the I/O priority of requests that have priority class RT.
+
+  restrict-to-be
+	For requests that do not have an I/O priority class or that have I/O
+	priority class RT, change it into BE. Also change the priority level
+	of these requests to 0. Do not modify the I/O priority class of
+	requests that have priority class IDLE.
+
+  idle
+	Change the I/O priority class of all requests into IDLE, the lowest
+	I/O priority class.
+
+  none-to-rt
+	Deprecated. Just an alias for promote-to-rt.
+
+The following numerical values are associated with the I/O priority policies:
+
++----------------+---+
+| no-change      | 0 |
++----------------+---+
+| promote-to-rt  | 1 |
++----------------+---+
+| restrict-to-be | 2 |
++----------------+---+
+| idle           | 3 |
++----------------+---+
+
+The numerical value that corresponds to each I/O priority class is as follows:
+
++-------------------------------+---+
+| IOPRIO_CLASS_NONE             | 0 |
++-------------------------------+---+
+| IOPRIO_CLASS_RT (real-time)   | 1 |
++-------------------------------+---+
+| IOPRIO_CLASS_BE (best effort) | 2 |
++-------------------------------+---+
+| IOPRIO_CLASS_IDLE             | 3 |
++-------------------------------+---+
+
+The algorithm to set the I/O priority class for a request is as follows:
+
+- If I/O priority class policy is promote-to-rt, change the request I/O
+  priority class to IOPRIO_CLASS_RT and change the request I/O priority
+  level to 4.
+- If I/O priority class policy is not promote-to-rt, translate the I/O priority
+  class policy into a number, then change the request I/O priority class
+  into the maximum of the I/O priority class policy number and the numerical
+  I/O priority class.
+
+PID
+---
+
+The process number controller is used to allow a cgroup to stop any
+new tasks from being fork()'d or clone()'d after a specified limit is
+reached.
+
+The number of tasks in a cgroup can be exhausted in ways which other
+controllers cannot prevent, thus warranting its own controller.  For
+example, a fork bomb is likely to exhaust the number of tasks before
+hitting memory restrictions.
+
+Note that PIDs used in this controller refer to TIDs, process IDs as
+used by the kernel.
+
+
+PID Interface Files
+~~~~~~~~~~~~~~~~~~~
+
+  pids.max
+	A read-write single value file which exists on non-root
+	cgroups.  The default is "max".
+
+	Hard limit of number of processes.
+
+  pids.current
+	A read-only single value file which exists on non-root cgroups.
+
+	The number of processes currently in the cgroup and its
+	descendants.
+
+  pids.peak
+	A read-only single value file which exists on non-root cgroups.
+
+	The maximum value that the number of processes in the cgroup and its
+	descendants has ever reached.
+
+  pids.events
+	A read-only flat-keyed file which exists on non-root cgroups. Unless
+	specified otherwise, a value change in this file generates a file
+	modified event. The following entries are defined.
+
+	  max
+		The number of times the cgroup's total number of processes hit the pids.max
+		limit (see also pids_localevents).
+
+  pids.events.local
+	Similar to pids.events but the fields in the file are local
+	to the cgroup i.e. not hierarchical. The file modified event
+	generated on this file reflects only the local events.
+
+Organisational operations are not blocked by cgroup policies, so it is
+possible to have pids.current > pids.max.  This can be done by either
+setting the limit to be smaller than pids.current, or attaching enough
+processes to the cgroup such that pids.current is larger than
+pids.max.  However, it is not possible to violate a cgroup PID policy
+through fork() or clone(). These will return -EAGAIN if the creation
+of a new process would cause a cgroup policy to be violated.
+
+
+Cpuset
+------
+
+The "cpuset" controller provides a mechanism for constraining
+the CPU and memory node placement of tasks to only the resources
+specified in the cpuset interface files in a task's current cgroup.
+This is especially valuable on large NUMA systems where placing jobs
+on properly sized subsets of the systems with careful processor and
+memory placement to reduce cross-node memory access and contention
+can improve overall system performance.
+
+The "cpuset" controller is hierarchical.  That means the controller
+cannot use CPUs or memory nodes not allowed in its parent.
+
+
+Cpuset Interface Files
+~~~~~~~~~~~~~~~~~~~~~~
+
+  cpuset.cpus
+	A read-write multiple values file which exists on non-root
+	cpuset-enabled cgroups.
+
+	It lists the requested CPUs to be used by tasks within this
+	cgroup.  The actual list of CPUs to be granted, however, is
+	subjected to constraints imposed by its parent and can differ
+	from the requested CPUs.
+
+	The CPU numbers are comma-separated numbers or ranges.
+	For example::
+
+	  # cat cpuset.cpus
+	  0-4,6,8-10
+
+	An empty value indicates that the cgroup is using the same
+	setting as the nearest cgroup ancestor with a non-empty
+	"cpuset.cpus" or all the available CPUs if none is found.
+
+	The value of "cpuset.cpus" stays constant until the next update
+	and won't be affected by any CPU hotplug events.
+
+  cpuset.cpus.effective
+	A read-only multiple values file which exists on all
+	cpuset-enabled cgroups.
+
+	It lists the onlined CPUs that are actually granted to this
+	cgroup by its parent.  These CPUs are allowed to be used by
+	tasks within the current cgroup.
+
+	If "cpuset.cpus" is empty, the "cpuset.cpus.effective" file shows
+	all the CPUs from the parent cgroup that can be available to
+	be used by this cgroup.  Otherwise, it should be a subset of
+	"cpuset.cpus" unless none of the CPUs listed in "cpuset.cpus"
+	can be granted.  In this case, it will be treated just like an
+	empty "cpuset.cpus".
+
+	Its value will be affected by CPU hotplug events.
+
+  cpuset.mems
+	A read-write multiple values file which exists on non-root
+	cpuset-enabled cgroups.
+
+	It lists the requested memory nodes to be used by tasks within
+	this cgroup.  The actual list of memory nodes granted, however,
+	is subjected to constraints imposed by its parent and can differ
+	from the requested memory nodes.
+
+	The memory node numbers are comma-separated numbers or ranges.
+	For example::
+
+	  # cat cpuset.mems
+	  0-1,3
+
+	An empty value indicates that the cgroup is using the same
+	setting as the nearest cgroup ancestor with a non-empty
+	"cpuset.mems" or all the available memory nodes if none
+	is found.
+
+	The value of "cpuset.mems" stays constant until the next update
+	and won't be affected by any memory nodes hotplug events.
+
+	Setting a non-empty value to "cpuset.mems" causes memory of
+	tasks within the cgroup to be migrated to the designated nodes if
+	they are currently using memory outside of the designated nodes.
+
+	There is a cost for this memory migration.  The migration
+	may not be complete and some memory pages may be left behind.
+	So it is recommended that "cpuset.mems" should be set properly
+	before spawning new tasks into the cpuset.  Even if there is
+	a need to change "cpuset.mems" with active tasks, it shouldn't
+	be done frequently.
+
+	For a multithreaded process, the threadgroup leader is
+	considered the owner of the group's memory. Memory policy
+	rebinding and migration will only happen with respect to the
+	threadgroup leader. To avoid unexpected results, non-leading
+	threads shouldn't be put into another cgroup whose "cpuset.mems"
+	doesn't fully overlap that of the threadgroup leader.
+
+  cpuset.mems.effective
+	A read-only multiple values file which exists on all
+	cpuset-enabled cgroups.
+
+	It lists the onlined memory nodes that are actually granted to
+	this cgroup by its parent. These memory nodes are allowed to
+	be used by tasks within the current cgroup.
+
+	If "cpuset.mems" is empty, it shows all the memory nodes from the
+	parent cgroup that will be available to be used by this cgroup.
+	Otherwise, it should be a subset of "cpuset.mems" unless none of
+	the memory nodes listed in "cpuset.mems" can be granted.  In this
+	case, it will be treated just like an empty "cpuset.mems".
+
+	Its value will be affected by memory nodes hotplug events.
+
+  cpuset.cpus.exclusive
+	A read-write multiple values file which exists on non-root
+	cpuset-enabled cgroups.
+
+	It lists all the exclusive CPUs that are allowed to be used
+	to create a new cpuset partition.  Its value is not used
+	unless the cgroup becomes a valid partition root.  See the
+	"cpuset.cpus.partition" section below for a description of what
+	a cpuset partition is.
+
+	When the cgroup becomes a partition root, the actual exclusive
+	CPUs that are allocated to that partition are listed in
+	"cpuset.cpus.exclusive.effective" which may be different
+	from "cpuset.cpus.exclusive".  If "cpuset.cpus.exclusive"
+	has previously been set, "cpuset.cpus.exclusive.effective"
+	is always a subset of it.
+
+	Users can manually set it to a value that is different from
+	"cpuset.cpus".	One constraint in setting it is that the list of
+	CPUs must be exclusive with respect to "cpuset.cpus.exclusive"
+	and "cpuset.cpus.exclusive.effective" of its siblings.	Another
+	constraint is that it cannot be a superset of "cpuset.cpus"
+	of its sibling in order to leave at least one CPU available to
+	that sibling when the exclusive CPUs are taken away.
+
+	For a parent cgroup, any one of its exclusive CPUs can only
+	be distributed to at most one of its child cgroups.  Having an
+	exclusive CPU appearing in two or more of its child cgroups is
+	not allowed (the exclusivity rule).  A value that violates the
+	exclusivity rule will be rejected with a write error.
+
+	The root cgroup is a partition root and all its available CPUs
+	are in its exclusive CPU set.
+
+  cpuset.cpus.exclusive.effective
+	A read-only multiple values file which exists on all non-root
+	cpuset-enabled cgroups.
+
+	This file shows the effective set of exclusive CPUs that
+	can be used to create a partition root.  The content
+	of this file will always be a subset of its parent's
+	"cpuset.cpus.exclusive.effective" if its parent is not the root
+	cgroup.  It will also be a subset of "cpuset.cpus.exclusive"
+	if it is set.  This file should only be non-empty if either
+	"cpuset.cpus.exclusive" is set or when the current cpuset is
+	a valid partition root.
+
+  cpuset.cpus.isolated
+	A read-only and root cgroup only multiple values file.
+
+	This file shows the set of all isolated CPUs used in existing
+	isolated partitions. It will be empty if no isolated partition
+	is created.
+
+  cpuset.cpus.partition
+	A read-write single value file which exists on non-root
+	cpuset-enabled cgroups.  This flag is owned by the parent cgroup
+	and is not delegatable.
+
+	It accepts only the following input values when written to.
+
+	  ==========	=====================================
+	  "member"	Non-root member of a partition
+	  "root"	Partition root
+	  "isolated"	Partition root without load balancing
+	  ==========	=====================================
+
+	A cpuset partition is a collection of cpuset-enabled cgroups with
+	a partition root at the top of the hierarchy and its descendants
+	except those that are separate partition roots themselves and
+	their descendants.  A partition has exclusive access to the
+	set of exclusive CPUs allocated to it.	Other cgroups outside
+	of that partition cannot use any CPUs in that set.
+
+	There are two types of partitions - local and remote.  A local
+	partition is one whose parent cgroup is also a valid partition
+	root.  A remote partition is one whose parent cgroup is not a
+	valid partition root itself.
+
+	Writing to "cpuset.cpus.exclusive" is optional for the creation
+	of a local partition as its "cpuset.cpus.exclusive" file will
+	assume an implicit value that is the same as "cpuset.cpus" if it
+	is not set.  Writing the proper "cpuset.cpus.exclusive" values
+	down the cgroup hierarchy before the target partition root is
+	mandatory for the creation of a remote partition.
+
+	Not all the CPUs requested in "cpuset.cpus.exclusive" can be
+	used to form a new partition.  Only those that were present
+	in its parent's "cpuset.cpus.exclusive.effective" control
+	file can be used.  For partitions created without setting
+	"cpuset.cpus.exclusive", exclusive CPUs specified in sibling's
+	"cpuset.cpus.exclusive" or "cpuset.cpus.exclusive.effective"
+	also cannot be used.
+
+	Currently, a remote partition cannot be created under a local
+	partition.  All the ancestors of a remote partition root except
+	the root cgroup cannot be a partition root.
+
+	The root cgroup is always a partition root and its state cannot
+	be changed.  All other non-root cgroups start out as "member".
+	Even though the "cpuset.cpus.exclusive*" and "cpuset.cpus"
+	control files are not present in the root cgroup, they are
+	implicitly the same as the "/sys/devices/system/cpu/possible"
+	sysfs file.
+
+	When set to "root", the current cgroup is the root of a new
+	partition or scheduling domain.  The set of exclusive CPUs is
+	determined by the value of its "cpuset.cpus.exclusive.effective".
+
+	When set to "isolated", the CPUs in that partition will be in
+	an isolated state without any load balancing from the scheduler
+	and excluded from the unbound workqueues.  Tasks placed in such
+	a partition with multiple CPUs should be carefully distributed
+	and bound to each of the individual CPUs for optimal performance.
+
+	A partition root ("root" or "isolated") can be in one of the
+	two possible states - valid or invalid.  An invalid partition
+	root is in a degraded state where some state information may
+	be retained, but behaves more like a "member".
+
+	All possible state transitions among "member", "root" and
+	"isolated" are allowed.
+
+	On read, the "cpuset.cpus.partition" file can show the following
+	values.
+
+	  =============================	=====================================
+	  "member"			Non-root member of a partition
+	  "root"			Partition root
+	  "isolated"			Partition root without load balancing
+	  "root invalid (<reason>)"	Invalid partition root
+	  "isolated invalid (<reason>)"	Invalid isolated partition root
+	  =============================	=====================================
+
+	In the case of an invalid partition root, a descriptive string on
+	why the partition is invalid is included within parentheses.
+
+	For a local partition root to be valid, the following conditions
+	must be met.
+
+	1) The parent cgroup is a valid partition root.
+	2) The "cpuset.cpus.exclusive.effective" file cannot be empty,
+	   though it may contain offline CPUs.
+	3) The "cpuset.cpus.effective" cannot be empty unless there is
+	   no task associated with this partition.
+
+	For a remote partition root to be valid, all the above conditions
+	except the first one must be met.
+
+	External events like hotplug or changes to "cpuset.cpus" or
+	"cpuset.cpus.exclusive" can cause a valid partition root to
+	become invalid and vice versa.	Note that a task cannot be
+	moved to a cgroup with empty "cpuset.cpus.effective".
+
+	A valid non-root parent partition may distribute out all its CPUs
+	to its child local partitions when there is no task associated
+	with it.
+
+	Care must be taken to change a valid partition root to "member"
+	as all its child local partitions, if present, will become
+	invalid causing disruption to tasks running in those child
+	partitions. These inactivated partitions could be recovered if
+	their parent is switched back to a partition root with a proper
+	value in "cpuset.cpus" or "cpuset.cpus.exclusive".
+
+	Poll and inotify events are triggered whenever the state of
+	"cpuset.cpus.partition" changes.  That includes changes caused
+	by write to "cpuset.cpus.partition", cpu hotplug or other
+	changes that modify the validity status of the partition.
+	This will allow user space agents to monitor unexpected changes
+	to "cpuset.cpus.partition" without the need to do continuous
+	polling.
+
+	A user can pre-configure certain CPUs to an isolated state
+	with load balancing disabled at boot time with the "isolcpus"
+	kernel boot command line option.  If those CPUs are to be put
+	into a partition, they have to be used in an isolated partition.
+
+
+Device controller
+-----------------
+
+Device controller manages access to device files. It includes both
+creation of new device files (using mknod), and access to the
+existing device files.
+
+Cgroup v2 device controller has no interface files and is implemented
+on top of cgroup BPF. To control access to device files, a user may
+create bpf programs of type BPF_PROG_TYPE_CGROUP_DEVICE and attach
+them to cgroups with BPF_CGROUP_DEVICE flag. On an attempt to access a
+device file, corresponding BPF programs will be executed, and depending
+on the return value the attempt will succeed or fail with -EPERM.
+
+A BPF_PROG_TYPE_CGROUP_DEVICE program takes a pointer to the
+bpf_cgroup_dev_ctx structure, which describes the device access attempt:
+access type (mknod/read/write) and device (type, major and minor numbers).
+If the program returns 0, the attempt fails with -EPERM, otherwise it
+succeeds.
+
+An example of BPF_PROG_TYPE_CGROUP_DEVICE program may be found in
+tools/testing/selftests/bpf/progs/dev_cgroup.c in the kernel source tree.
+
+
+RDMA
+----
+
+The "rdma" controller regulates the distribution and accounting of
+RDMA resources.
+
+RDMA devices from all network namespaces are listed. Each line starts with
+the device name. If more than one device has the same name, ``index=N``
+follows the name, where ``N`` is the system-wide RDMA device index, unique
+among registered devices.
+
+RDMA Interface Files
+~~~~~~~~~~~~~~~~~~~~
+
+  rdma.max
+	A readwrite nested-keyed file that exists for all the cgroups
+	except root that describes current configured resource limit
+	for a RDMA/IB device.
+
+	Lines are keyed by device name and are not ordered. A write may
+	include ``index=N`` after the device name. The index is optional
+	when the name is globally unique. If multiple devices have that
+	name, the index is required and a write without it fails with
+	``-ENOTUNIQ``.
+	Each line contains space separated resource name and its configured
+	limit that can be distributed.
+
+	The following nested keys are defined.
+
+	  ==========	=============================
+	  hca_handle	Maximum number of HCA Handles
+	  hca_object 	Maximum number of HCA Objects
+	  ==========	=============================
+
+	An example for mlx4 and ocrdma device follows::
+
+	  mlx4_0 hca_handle=2 hca_object=2000
+	  ocrdma1 hca_handle=3 hca_object=max
+
+	For devices with duplicate names, select the device by index::
+
+	  echo "rxe0 index=5 hca_handle=2" > rdma.max
+
+  rdma.current
+	A read-only file that describes current resource usage.
+	It exists for all the cgroup except root.
+
+	An example for mlx4 and ocrdma device follows::
+
+	  mlx4_0 hca_handle=1 hca_object=20
+	  ocrdma1 hca_handle=1 hca_object=23
+
+  rdma.peak
+	A read-only nested-keyed file that exists for all the cgroups
+	except root.  It shows the historical high watermark of
+	resource usage per device since the cgroup was created.
+
+	An example for mlx4 and ocrdma device follows::
+
+	  mlx4_0 hca_handle=1 hca_object=20
+	  ocrdma1 hca_handle=0 hca_object=23
+
+  rdma.events
+	A read-only nested-keyed file which exists on non-root
+	cgroups.  The following nested keys are defined.
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because a rdma.max limit in the subtree
+		was reached.  This is a hierarchical counter: the event
+		is propagated upward to all ancestor cgroups.  A value
+		change in this file generates a file modified event.
+
+	  alloc_fail
+		The number of RDMA resource allocation attempts that
+		originated in this cgroup or its descendants and failed
+		due to a rdma.max limit being reached.  This is a
+		hierarchical counter propagated upward.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=3 hca_object.max=0 hca_object.alloc_fail=0
+
+  rdma.events.local
+	Similar to rdma.events but the fields in the file are local
+	to the cgroup i.e. not hierarchical.  The file modified event
+	generated on this file reflects only the local events.
+
+	The following nested keys are defined.
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because this cgroup's own rdma.max limit
+		was reached.
+	  alloc_fail
+		The number of RDMA resource allocation attempts
+		originating from this cgroup that failed due to this
+		cgroup's or an ancestor's rdma.max limit.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=0 hca_object.max=0 hca_object.alloc_fail=0
+
+DMEM
+----
+
+The "dmem" controller regulates the distribution and accounting of
+device memory regions. Because each memory region may have its own page size,
+which does not have to be equal to the system page size, the units are always bytes.
+
+DMEM Interface Files
+~~~~~~~~~~~~~~~~~~~~
+
+  dmem.max, dmem.min, dmem.low
+	A readwrite nested-keyed file that exists for all the cgroups
+	except root that describes current configured resource limit
+	for a region.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 1073741824
+	  drm/0000:03:00.0/stolen max
+
+	The semantics are the same as for the memory cgroup controller, and are
+	calculated in the same way.
+
+  dmem.peak
+	A read-only nested-keyed file that exists on non-root cgroups.
+
+	The max device memory usage recorded for the cgroup and its
+	descendants since the creation of the cgroup for each region.
+
+  dmem.capacity
+	A read-only file that describes maximum region capacity.
+	It only exists on the root cgroup. Not all memory can be
+	allocated by cgroups, as the kernel reserves some for
+	internal use.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 8514437120
+	  drm/0000:03:00.0/stolen 67108864
+
+  dmem.current
+	A read-only file that describes current resource usage.
+	It exists for all the cgroup except root.
+
+	An example for xe follows::
+
+	  drm/0000:03:00.0/vram0 12550144
+	  drm/0000:03:00.0/stolen 8650752
+
+HugeTLB
+-------
+
+The HugeTLB controller allows limiting the HugeTLB usage per control group and
+enforces the controller limit during page fault.
+
+HugeTLB Interface Files
+~~~~~~~~~~~~~~~~~~~~~~~
+
+  hugetlb.<hugepagesize>.current
+	Show current usage for "hugepagesize" hugetlb.  It exists for all
+	the cgroup except root.
+
+  hugetlb.<hugepagesize>.max
+	Set/show the hard limit of "hugepagesize" hugetlb usage.
+	The default value is "max".  It exists for all the cgroup except root.
+
+  hugetlb.<hugepagesize>.events
+	A read-only flat-keyed file which exists on non-root cgroups.
+
+	  max
+		The number of allocation failure due to HugeTLB limit
+
+  hugetlb.<hugepagesize>.events.local
+	Similar to hugetlb.<hugepagesize>.events but the fields in the file
+	are local to the cgroup i.e. not hierarchical. The file modified event
+	generated on this file reflects only the local events.
+
+  hugetlb.<hugepagesize>.numa_stat
+	Similar to memory.numa_stat, it shows the numa information of the
+        hugetlb pages of <hugepagesize> in this cgroup.  Only active in
+        use hugetlb pages are included.  The per-node values are in bytes.
+
+Misc
+----
+
+The Miscellaneous cgroup provides the resource limiting and tracking
+mechanism for the scalar resources which cannot be abstracted like the other
+cgroup resources. Controller is enabled by the CONFIG_CGROUP_MISC config
+option.
+
+A resource can be added to the controller via enum misc_res_type{} in the
+include/linux/misc_cgroup.h file and the corresponding name via misc_res_name[]
+in the kernel/cgroup/misc.c file. Provider of the resource must set its
+capacity prior to using the resource by calling misc_cg_set_capacity().
+
+Once a capacity is set then the resource usage can be updated using charge and
+uncharge APIs. All of the APIs to interact with misc controller are in
+include/linux/misc_cgroup.h.
+
+Misc Interface Files
+~~~~~~~~~~~~~~~~~~~~
+
+Miscellaneous controller provides the following interface files. If two misc
+resources (res_a and res_b) are registered then:
+
+  misc.capacity
+        A read-only flat-keyed file shown only in the root cgroup.  It shows
+        miscellaneous scalar resources available on the platform along with
+        their quantities::
+
+	  $ cat misc.capacity
+	  res_a 50
+	  res_b 10
+
+  misc.current
+        A read-only flat-keyed file shown in the all cgroups.  It shows
+        the current usage of the resources in the cgroup and its children.::
+
+	  $ cat misc.current
+	  res_a 3
+	  res_b 0
+
+  misc.peak
+        A read-only flat-keyed file shown in all cgroups.  It shows the
+        historical maximum usage of the resources in the cgroup and its
+        children.::
+
+	  $ cat misc.peak
+	  res_a 10
+	  res_b 8
+
+  misc.max
+        A read-write flat-keyed file shown in the non root cgroups. Allowed
+        maximum usage of the resources in the cgroup and its children.::
+
+	  $ cat misc.max
+	  res_a max
+	  res_b 4
+
+	Limit can be set by::
+
+	  # echo res_a 1 > misc.max
+
+	Limit can be set to max by::
+
+	  # echo res_a max > misc.max
+
+        Limits can be set higher than the capacity value in the misc.capacity
+        file.
+
+  misc.events
+	A read-only flat-keyed file which exists on non-root cgroups. The
+	following entries are defined. Unless specified otherwise, a value
+	change in this file generates a file modified event. All fields in
+	this file are hierarchical.
+
+	  max
+		The number of times the cgroup's resource usage was
+		about to go over the max boundary.
+
+  misc.events.local
+        Similar to misc.events but the fields in the file are local to the
+        cgroup i.e. not hierarchical. The file modified event generated on
+        this file reflects only the local events.
+
+Migration and Ownership
+~~~~~~~~~~~~~~~~~~~~~~~
+
+A miscellaneous scalar resource is charged to the cgroup in which it is used
+first, and stays charged to that cgroup until that resource is freed. Migrating
+a process to a different cgroup does not move the charge to the destination
+cgroup where the process has moved.
+
+Others
+------
+
+perf_event
+~~~~~~~~~~
+
+perf_event controller, if not mounted on a legacy hierarchy, is
+automatically enabled on the v2 hierarchy so that perf events can
+always be filtered by cgroup v2 path.  The controller can still be
+moved to a legacy hierarchy after v2 hierarchy is populated.
+
+
+Non-normative information
+-------------------------
+
+This section contains information that isn't considered to be a part of
+the stable kernel API and so is subject to change.
+
+
+CPU controller root cgroup process behaviour
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When distributing CPU cycles in the root cgroup each thread in this
+cgroup is treated as if it was hosted in a separate child cgroup of the
+root cgroup. This child cgroup weight is dependent on its thread nice
+level.
+
+For details of this mapping see sched_prio_to_weight array in
+kernel/sched/core.c file (values from this array should be scaled
+appropriately so the neutral - nice 0 - value is 100 instead of 1024).
+
+
+IO controller root cgroup process behaviour
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Root cgroup processes are hosted in an implicit leaf child node.
+When distributing IO resources this implicit child node is taken into
+account as if it was a normal child cgroup of the root cgroup with a
+weight value of 200.
+
+
+Namespace
+=========
+
+Basics
+------
+
+cgroup namespace provides a mechanism to virtualize the view of the
+"/proc/$PID/cgroup" file and cgroup mounts.  The CLONE_NEWCGROUP clone
+flag can be used with clone(2) and unshare(2) to create a new cgroup
+namespace.  The process running inside the cgroup namespace will have
+its "/proc/$PID/cgroup" output restricted to cgroupns root.  The
+cgroupns root is the cgroup of the process at the time of creation of
+the cgroup namespace.
+
+Without cgroup namespace, the "/proc/$PID/cgroup" file shows the
+complete path of the cgroup of a process.  In a container setup where
+a set of cgroups and namespaces are intended to isolate processes the
+"/proc/$PID/cgroup" file may leak potential system level information
+to the isolated processes.  For example::
+
+  # cat /proc/self/cgroup
+  0::/batchjobs/container_id1
+
+The path '/batchjobs/container_id1' can be considered as system-data
+and undesirable to expose to the isolated processes.  cgroup namespace
+can be used to restrict visibility of this path.  For example, before
+creating a cgroup namespace, one would see::
+
+  # ls -l /proc/self/ns/cgroup
+  lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835]
+  # cat /proc/self/cgroup
+  0::/batchjobs/container_id1
+
+After unsharing a new namespace, the view changes::
+
+  # ls -l /proc/self/ns/cgroup
+  lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup -> cgroup:[4026532183]
+  # cat /proc/self/cgroup
+  0::/
+
+When some thread from a multi-threaded process unshares its cgroup
+namespace, the new cgroupns gets applied to the entire process (all
+the threads).  This is natural for the v2 hierarchy; however, for the
+legacy hierarchies, this may be unexpected.
+
+A cgroup namespace is alive as long as there are processes inside or
+mounts pinning it.  When the last usage goes away, the cgroup
+namespace is destroyed.  The cgroupns root and the actual cgroups
+remain.
+
+
+The Root and Views
+------------------
+
+The 'cgroupns root' for a cgroup namespace is the cgroup in which the
+process calling unshare(2) is running.  For example, if a process in
+/batchjobs/container_id1 cgroup calls unshare, cgroup
+/batchjobs/container_id1 becomes the cgroupns root.  For the
+init_cgroup_ns, this is the real root ('/') cgroup.
+
+The cgroupns root cgroup does not change even if the namespace creator
+process later moves to a different cgroup::
+
+  # ~/unshare -c # unshare cgroupns in some cgroup
+  # cat /proc/self/cgroup
+  0::/
+  # mkdir sub_cgrp_1
+  # echo 0 > sub_cgrp_1/cgroup.procs
+  # cat /proc/self/cgroup
+  0::/sub_cgrp_1
+
+Each process gets its namespace-specific view of "/proc/$PID/cgroup"
+
+Processes running inside the cgroup namespace will be able to see
+cgroup paths (in /proc/self/cgroup) only inside their root cgroup.
+From within an unshared cgroupns::
+
+  # sleep 100000 &
+  [1] 7353
+  # echo 7353 > sub_cgrp_1/cgroup.procs
+  # cat /proc/7353/cgroup
+  0::/sub_cgrp_1
+
+From the initial cgroup namespace, the real cgroup path will be
+visible::
+
+  $ cat /proc/7353/cgroup
+  0::/batchjobs/container_id1/sub_cgrp_1
+
+From a sibling cgroup namespace (that is, a namespace rooted at a
+different cgroup), the cgroup path relative to its own cgroup
+namespace root will be shown.  For instance, if PID 7353's cgroup
+namespace root is at '/batchjobs/container_id2', then it will see::
+
+  # cat /proc/7353/cgroup
+  0::/../container_id2/sub_cgrp_1
+
+Note that the relative path always starts with '/' to indicate that
+its relative to the cgroup namespace root of the caller.
+
+
+Migration and setns(2)
+----------------------
+
+Processes inside a cgroup namespace can move into and out of the
+namespace root if they have proper access to external cgroups.  For
+example, from inside a namespace with cgroupns root at
+/batchjobs/container_id1, and assuming that the global hierarchy is
+still accessible inside cgroupns::
+
+  # cat /proc/7353/cgroup
+  0::/sub_cgrp_1
+  # echo 7353 > batchjobs/container_id2/cgroup.procs
+  # cat /proc/7353/cgroup
+  0::/../container_id2
+
+Note that this kind of setup is not encouraged.  A task inside cgroup
+namespace should only be exposed to its own cgroupns hierarchy.
+
+setns(2) to another cgroup namespace is allowed when:
+
+(a) the process has CAP_SYS_ADMIN against its current user namespace
+(b) the process has CAP_SYS_ADMIN against the target cgroup
+    namespace's userns
+
+No implicit cgroup changes happen with attaching to another cgroup
+namespace.  It is expected that the someone moves the attaching
+process under the target cgroup namespace root.
+
+
+Interaction with Other Namespaces
+---------------------------------
+
+Namespace specific cgroup hierarchy can be mounted by a process
+running inside a non-init cgroup namespace::
+
+  # mount -t cgroup2 none $MOUNT_POINT
+
+This will mount the unified cgroup hierarchy with cgroupns root as the
+filesystem root.  The process needs CAP_SYS_ADMIN against its user and
+mount namespaces.
+
+The virtualization of /proc/self/cgroup file combined with restricting
+the view of cgroup hierarchy by namespace-private cgroupfs mount
+provides a properly isolated cgroup view inside the container.
+
+
+Information on Kernel Programming
+=================================
+
+This section contains kernel programming information in the areas
+where interacting with cgroup is necessary.  cgroup core and
+controllers are not covered.
+
+
+Filesystem Support for Writeback
+--------------------------------
+
+A filesystem can support cgroup writeback by updating
+address_space_operations->writepages() to annotate bio's using the
+following two functions.
+
+  wbc_init_bio(@wbc, @bio)
+	Should be called for each bio carrying writeback data and
+	associates the bio with the inode's owner cgroup and the
+	corresponding request queue.  This must be called after
+	a queue (device) has been associated with the bio and
+	before submission.
+
+  wbc_account_cgroup_owner(@wbc, @folio, @bytes)
+	Should be called for each data segment being written out.
+	While this function doesn't care exactly when it's called
+	during the writeback session, it's the easiest and most
+	natural to call it as data segments are added to a bio.
+
+With writeback bio's annotated, cgroup support can be enabled per
+super_block by setting SB_I_CGROUPWB in ->s_iflags.  This allows for
+selective disabling of cgroup writeback support which is helpful when
+certain filesystem features, e.g. journaled data mode, are
+incompatible.
+
+wbc_init_bio() binds the specified bio to its cgroup.  Depending on
+the configuration, the bio may be executed at a lower priority and if
+the writeback session is holding shared resources, e.g. a journal
+entry, may lead to priority inversion.  There is no one easy solution
+for the problem.  Filesystems can try to work around specific problem
+cases by skipping wbc_init_bio() and using bio_associate_blkg()
+directly.
+
+
+Deprecated v1 Core Features
+===========================
+
+- Multiple hierarchies including named ones are not supported.
+
+- All v1 mount options are not supported.
+
+- The "tasks" file is removed and "cgroup.procs" is not sorted.
+
+- "cgroup.clone_children" is removed.
+
+- /proc/cgroups is meaningless for v2.  Use "cgroup.controllers" or
+  "cgroup.stat" files at the root instead.
+
+
+Issues with v1 and Rationales for v2
+====================================
+
+Multiple Hierarchies
+--------------------
+
+cgroup v1 allowed an arbitrary number of hierarchies and each
+hierarchy could host any number of controllers.  While this seemed to
+provide a high level of flexibility, it wasn't useful in practice.
+
+For example, as there is only one instance of each controller, utility
+type controllers such as freezer which can be useful in all
+hierarchies could only be used in one.  The issue is exacerbated by
+the fact that controllers couldn't be moved to another hierarchy once
+hierarchies were populated.  Another issue was that all controllers
+bound to a hierarchy were forced to have exactly the same view of the
+hierarchy.  It wasn't possible to vary the granularity depending on
+the specific controller.
+
+In practice, these issues heavily limited which controllers could be
+put on the same hierarchy and most configurations resorted to putting
+each controller on its own hierarchy.  Only closely related ones, such
+as the cpu and cpuacct controllers, made sense to be put on the same
+hierarchy.  This often meant that userland ended up managing multiple
+similar hierarchies repeating the same steps on each hierarchy
+whenever a hierarchy management operation was necessary.
+
+Furthermore, support for multiple hierarchies came at a steep cost.
+It greatly complicated cgroup core implementation but more importantly
+the support for multiple hierarchies restricted how cgroup could be
+used in general and what controllers was able to do.
+
+There was no limit on how many hierarchies there might be, which meant
+that a thread's cgroup membership couldn't be described in finite
+length.  The key might contain any number of entries and was unlimited
+in length, which made it highly awkward to manipulate and led to
+addition of controllers which existed only to identify membership,
+which in turn exacerbated the original problem of proliferating number
+of hierarchies.
+
+Also, as a controller couldn't have any expectation regarding the
+topologies of hierarchies other controllers might be on, each
+controller had to assume that all other controllers were attached to
+completely orthogonal hierarchies.  This made it impossible, or at
+least very cumbersome, for controllers to cooperate with each other.
+
+In most use cases, putting controllers on hierarchies which are
+completely orthogonal to each other isn't necessary.  What usually is
+called for is the ability to have differing levels of granularity
+depending on the specific controller.  In other words, hierarchy may
+be collapsed from leaf towards root when viewed from specific
+controllers.  For example, a given configuration might not care about
+how memory is distributed beyond a certain level while still wanting
+to control how CPU cycles are distributed.
+
+
+Thread Granularity
+------------------
+
+cgroup v1 allowed threads of a process to belong to different cgroups.
+This didn't make sense for some controllers and those controllers
+ended up implementing different ways to ignore such situations but
+much more importantly it blurred the line between API exposed to
+individual applications and system management interface.
+
+Generally, in-process knowledge is available only to the process
+itself; thus, unlike service-level organization of processes,
+categorizing threads of a process requires active participation from
+the application which owns the target process.
+
+cgroup v1 had an ambiguously defined delegation model which got abused
+in combination with thread granularity.  cgroups were delegated to
+individual applications so that they can create and manage their own
+sub-hierarchies and control resource distributions along them.  This
+effectively raised cgroup to the status of a syscall-like API exposed
+to lay programs.
+
+First of all, cgroup has a fundamentally inadequate interface to be
+exposed this way.  For a process to access its own knobs, it has to
+extract the path on the target hierarchy from /proc/self/cgroup,
+construct the path by appending the name of the knob to the path, open
+and then read and/or write to it.  This is not only extremely clunky
+and unusual but also inherently racy.  There is no conventional way to
+define transaction across the required steps and nothing can guarantee
+that the process would actually be operating on its own sub-hierarchy.
+
+cgroup controllers implemented a number of knobs which would never be
+accepted as public APIs because they were just adding control knobs to
+system-management pseudo filesystem.  cgroup ended up with interface
+knobs which were not properly abstracted or refined and directly
+revealed kernel internal details.  These knobs got exposed to
+individual applications through the ill-defined delegation mechanism
+effectively abusing cgroup as a shortcut to implementing public APIs
+without going through the required scrutiny.
+
+This was painful for both userland and kernel.  Userland ended up with
+misbehaving and poorly abstracted interfaces and kernel exposing and
+locked into constructs inadvertently.
+
+
+Competition Between Inner Nodes and Threads
+-------------------------------------------
+
+cgroup v1 allowed threads to be in any cgroups which created an
+interesting problem where threads belonging to a parent cgroup and its
+children cgroups competed for resources.  This was nasty as two
+different types of entities competed and there was no obvious way to
+settle it.  Different controllers did different things.
+
+The cpu controller considered threads and cgroups as equivalents and
+mapped nice levels to cgroup weights.  This worked for some cases but
+fell flat when children wanted to be allocated specific ratios of CPU
+cycles and the number of internal threads fluctuated - the ratios
+constantly changed as the number of competing entities fluctuated.
+There also were other issues.  The mapping from nice level to weight
+wasn't obvious or universal, and there were various other knobs which
+simply weren't available for threads.
+
+The io controller implicitly created a hidden leaf node for each
+cgroup to host the threads.  The hidden leaf had its own copies of all
+the knobs with ``leaf_`` prefixed.  While this allowed equivalent
+control over internal threads, it was with serious drawbacks.  It
+always added an extra layer of nesting which wouldn't be necessary
+otherwise, made the interface messy and significantly complicated the
+implementation.
+
+The memory controller didn't have a way to control what happened
+between internal tasks and child cgroups and the behavior was not
+clearly defined.  There were attempts to add ad-hoc behaviors and
+knobs to tailor the behavior to specific workloads which would have
+led to problems extremely difficult to resolve in the long term.
+
+Multiple controllers struggled with internal tasks and came up with
+different ways to deal with it; unfortunately, all the approaches were
+severely flawed and, furthermore, the widely different behaviors
+made cgroup as a whole highly inconsistent.
+
+This clearly is a problem which needs to be addressed from cgroup core
+in a uniform way.
+
+
+Other Interface Issues
+----------------------
+
+cgroup v1 grew without oversight and developed a large number of
+idiosyncrasies and inconsistencies.  One issue on the cgroup core side
+was how an empty cgroup was notified - a userland helper binary was
+forked and executed for each event.  The event delivery wasn't
+recursive or delegatable.  The limitations of the mechanism also led
+to in-kernel event delivery filtering mechanism further complicating
+the interface.
+
+Controller interfaces were problematic too.  An extreme example is
+controllers completely ignoring hierarchical organization and treating
+all cgroups as if they were all located directly under the root
+cgroup.  Some controllers exposed a large amount of inconsistent
+implementation details to userland.
+
+There also was no consistency across controllers.  When a new cgroup
+was created, some controllers defaulted to not imposing extra
+restrictions while others disallowed any resource usage until
+explicitly configured.  Configuration knobs for the same type of
+control used widely differing naming schemes and formats.  Statistics
+and information knobs were named arbitrarily and used different
+formats and units even in the same controller.
+
+cgroup v2 establishes common conventions where appropriate and updates
+controllers so that they expose minimal and consistent interfaces.
+
+
+Controller Issues and Remedies
+------------------------------
+
+Memory
+~~~~~~
+
+The original lower boundary, the soft limit, is defined as a limit
+that is per default unset.  As a result, the set of cgroups that
+global reclaim prefers is opt-in, rather than opt-out.  The costs for
+optimizing these mostly negative lookups are so high that the
+implementation, despite its enormous size, does not even provide the
+basic desirable behavior.  First off, the soft limit has no
+hierarchical meaning.  All configured groups are organized in a global
+rbtree and treated like equal peers, regardless where they are located
+in the hierarchy.  This makes subtree delegation impossible.  Second,
+the soft limit reclaim pass is so aggressive that it not just
+introduces high allocation latencies into the system, but also impacts
+system performance due to overreclaim, to the point where the feature
+becomes self-defeating.
+
+The memory.low boundary on the other hand is a top-down allocated
+reserve.  A cgroup enjoys reclaim protection when it's within its
+effective low, which makes delegation of subtrees possible. It also
+enjoys having reclaim pressure proportional to its overage when
+above its effective low.
+
+The original high boundary, the hard limit, is defined as a strict
+limit that can not budge, even if the OOM killer has to be called.
+But this generally goes against the goal of making the most out of the
+available memory.  The memory consumption of workloads varies during
+runtime, and that requires users to overcommit.  But doing that with a
+strict upper limit requires either a fairly accurate prediction of the
+working set size or adding slack to the limit.  Since working set size
+estimation is hard and error prone, and getting it wrong results in
+OOM kills, most users tend to err on the side of a looser limit and
+end up wasting precious resources.
+
+The memory.high boundary on the other hand can be set much more
+conservatively.  When hit, it throttles allocations by forcing them
+into direct reclaim to work off the excess, but it never invokes the
+OOM killer.  As a result, a high boundary that is chosen too
+aggressively will not terminate the processes, but instead it will
+lead to gradual performance degradation.  The user can monitor this
+and make corrections until the minimal memory footprint that still
+gives acceptable performance is found.
+
+In extreme cases, with many concurrent allocations and a complete
+breakdown of reclaim progress within the group, the high boundary can
+be exceeded.  But even then it's mostly better to satisfy the
+allocation from the slack available in other groups or the rest of the
+system than killing the group.  Otherwise, memory.max is there to
+limit this type of spillover and ultimately contain buggy or even
+malicious applications.
+
+Setting the original memory.limit_in_bytes below the current usage was
+subject to a race condition, where concurrent charges could cause the
+limit setting to fail. memory.max on the other hand will first set the
+limit to prevent new charges, and then reclaim and OOM kill until the
+new limit is met - or the task writing to memory.max is killed.
+
+The combined memory+swap accounting and limiting is replaced by real
+control over swap space.
+
+The main argument for a combined memory+swap facility in the original
+cgroup design was that global or parental pressure would always be
+able to swap all anonymous memory of a child group, regardless of the
+child's own (possibly untrusted) configuration.  However, untrusted
+groups can sabotage swapping by other means - such as referencing its
+anonymous memory in a tight loop - and an admin can not assume full
+swappability when overcommitting untrusted jobs.
+
+For trusted jobs, on the other hand, a combined counter is not an
+intuitive userspace interface, and it flies in the face of the idea
+that cgroup controllers should account and limit specific physical
+resources.  Swap space is a resource like all others in the system,
+and that's why unified hierarchy allows distributing it separately.
diff --git a/Documentation/admin-guide/cifs/authors.rst b/Documentation/admin-guide/cifs/authors.rst
new file mode 100644
index 000000000..5c1d2f0fa
--- /dev/null
+++ b/Documentation/admin-guide/cifs/authors.rst
@@ -0,0 +1,69 @@
+=======
+Authors
+=======
+
+Original Author
+---------------
+
+Steve French (smfrench@gmail.com, sfrench@samba.org)
+
+The author wishes to express his appreciation and thanks to:
+Andrew Tridgell (Samba team) for his early suggestions about SMB/CIFS VFS
+improvements. Thanks to IBM for allowing me time and test resources to pursue
+this project, to Jim McDonough from IBM (and the Samba Team) for his help, to
+the IBM Linux JFS team for explaining many esoteric Linux filesystem features.
+Jeremy Allison of the Samba team has done invaluable work in adding the server
+side of the original CIFS Unix extensions and reviewing and implementing
+portions of the newer CIFS POSIX extensions into the Samba 3 file server. Thank
+Dave Boutcher of IBM Rochester (author of the OS/400 smb/cifs filesystem client)
+for proving years ago that very good smb/cifs clients could be done on Unix-like
+operating systems.  Volker Lendecke, Andrew Tridgell, Urban Widmark, John
+Newbigin and others for their work on the Linux smbfs module.  Thanks to
+the other members of the Storage Network Industry Association CIFS Technical
+Workgroup for their work specifying this highly complex protocol and finally
+thanks to the Samba team for their technical advice and encouragement.
+
+Patch Contributors
+------------------
+
+- Zwane Mwaikambo
+- Andi Kleen
+- Amrut Joshi
+- Shobhit Dayal
+- Sergey Vlasov
+- Richard Hughes
+- Yury Umanets
+- Mark Hamzy (for some of the early cifs IPv6 work)
+- Domen Puncer
+- Jesper Juhl (in particular for lots of whitespace/formatting cleanup)
+- Vince Negri and Dave Stahl (for finding an important caching bug)
+- Adrian Bunk (kcalloc cleanups)
+- Miklos Szeredi
+- Kazeon team for various fixes especially for 2.4 version.
+- Asser Ferno (Change Notify support)
+- Shaggy (Dave Kleikamp) for innumerable small fs suggestions and some good cleanup
+- Gunter Kukkukk (testing and suggestions for support of old servers)
+- Igor Mammedov (DFS support)
+- Jeff Layton (many, many fixes, as well as great work on the cifs Kerberos code)
+- Scott Lovenberg
+- Pavel Shilovsky (for great work adding SMB2 support, and various SMB3 features)
+- Aurelien Aptel (for DFS SMB3 work and some key bug fixes)
+- Ronnie Sahlberg (for SMB3 xattr work, bug fixes, and lots of great work on compounding)
+- Shirish Pargaonkar (for many ACL patches over the years)
+- Sachin Prabhu (many bug fixes, including for reconnect, copy offload and security)
+- Paulo Alcantara (for some excellent work in DFS, and in booting from SMB3)
+- Long Li (some great work on RDMA, SMB Direct)
+
+
+Test case and Bug Report contributors
+-------------------------------------
+Thanks to those in the community who have submitted detailed bug reports
+and debug of problems they have found:  Jochen Dolze, David Blaine,
+Rene Scharfe, Martin Josefsson, Alexander Wild, Anthony Liguori,
+Lars Muller, Urban Widmark, Massimiliano Ferrero, Howard Owen,
+Olaf Kirch, Kieron Briggs, Nick Millington and others. Also special
+mention to the Stanford Checker (SWAT) which pointed out many minor
+bugs in error paths.  Valuable suggestions also have come from Al Viro
+and Dave Miller.
+
+And thanks to the IBM LTC and Power test teams and SuSE and Citrix and RedHat testers for finding multiple bugs during excellent stress test runs.
diff --git a/Documentation/admin-guide/cifs/changes.rst b/Documentation/admin-guide/cifs/changes.rst
new file mode 100644
index 000000000..8c42c4de5
--- /dev/null
+++ b/Documentation/admin-guide/cifs/changes.rst
@@ -0,0 +1,9 @@
+=======
+Changes
+=======
+
+See https://wiki.samba.org/index.php/LinuxCIFSKernel for summary
+information about fixes/improvements to CIFS/SMB2/SMB3 support (changes
+to cifs.ko module) by kernel version (and cifs internal module version).
+This may be easier to read than parsing the output of
+"git log fs/smb/client" by release.
diff --git a/Documentation/admin-guide/cifs/index.rst b/Documentation/admin-guide/cifs/index.rst
new file mode 100644
index 000000000..58ab58a71
--- /dev/null
+++ b/Documentation/admin-guide/cifs/index.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+CIFS
+====
+
+.. toctree::
+   :maxdepth: 2
+
+   introduction
+   usage
+   todo
+   changes
+   authors
diff --git a/Documentation/admin-guide/cifs/introduction.rst b/Documentation/admin-guide/cifs/introduction.rst
new file mode 100644
index 000000000..ffc6e2564
--- /dev/null
+++ b/Documentation/admin-guide/cifs/introduction.rst
@@ -0,0 +1,53 @@
+============
+Introduction
+============
+
+  This is the client VFS module for the SMB3 NAS protocol as well
+  as for older dialects such as the Common Internet File System (CIFS)
+  protocol which was the successor to the Server Message Block
+  (SMB) protocol, the native file sharing mechanism for most early
+  PC operating systems. New and improved versions of CIFS are now
+  called SMB2 and SMB3. Use of SMB3 (and later, including SMB3.1.1
+  the most current dialect) is strongly preferred over using older
+  dialects like CIFS due to security reasons. All modern dialects,
+  including the most recent, SMB3.1.1, are supported by the CIFS VFS
+  module. The SMB3 protocol is implemented and supported by all major
+  file servers such as Windows (including Windows 2019 Server), as
+  well as by Samba (which provides excellent CIFS/SMB2/SMB3 server
+  support and tools for Linux and many other operating systems).
+  Apple systems also support SMB3 well, as do most Network Attached
+  Storage vendors, so this network filesystem client can mount to a
+  wide variety of systems. It also supports mounting to the cloud
+  (for example Microsoft Azure), including the necessary security
+  features.
+
+  The intent of this module is to provide the most advanced network
+  file system function for SMB3 compliant servers, including advanced
+  security features, excellent parallelized high performance i/o, better
+  POSIX compliance, secure per-user session establishment, encryption,
+  high performance safe distributed caching (leases/oplocks), optional packet
+  signing, large files, Unicode support and other internationalization
+  improvements. Since both Samba server and this filesystem client support the
+  CIFS Unix extensions, and the Linux client also supports SMB3 POSIX extensions,
+  the combination can provide a reasonable alternative to other network and
+  cluster file systems for fileserving in some Linux to Linux environments,
+  not just in Linux to Windows (or Linux to Mac) environments.
+
+  This filesystem has a mount utility (mount.cifs) and various user space
+  tools (including smbinfo and setcifsacl) that can be obtained from
+
+      https://git.samba.org/?p=cifs-utils.git
+
+  or
+
+      git://git.samba.org/cifs-utils.git
+
+  mount.cifs should be installed in the directory with the other mount helpers.
+
+  For more information on the module see the project wiki page at
+
+      https://wiki.samba.org/index.php/LinuxCIFS
+
+  and
+
+      https://wiki.samba.org/index.php/LinuxCIFS_utils
diff --git a/Documentation/admin-guide/cifs/todo.rst b/Documentation/admin-guide/cifs/todo.rst
new file mode 100644
index 000000000..9a65c6707
--- /dev/null
+++ b/Documentation/admin-guide/cifs/todo.rst
@@ -0,0 +1,133 @@
+====
+TODO
+====
+
+As of 6.7 kernel. See https://wiki.samba.org/index.php/LinuxCIFSKernel
+for list of features added by release
+
+A Partial List of Missing Features
+==================================
+
+Contributions are welcome.  There are plenty of opportunities
+for visible, important contributions to this module.  Here
+is a partial list of the known problems and missing features:
+
+a) SMB3 (and SMB3.1.1) missing optional features:
+   multichannel performance optimizations, algorithmic channel selection,
+   directory leases optimizations,
+   support for faster packet signing (GMAC),
+   support for compression over the network,
+   T10 copy offload ie "ODX" (copy chunk, and "Duplicate Extents" ioctl
+   are currently the only two server side copy mechanisms supported)
+
+b) Better optimized compounding and error handling for sparse file support,
+   perhaps addition of new optional SMB3.1.1 fsctls to make collapse range
+   and insert range more atomic
+
+c) Support for SMB3.1.1 over QUIC (and perhaps other socket based protocols
+   like SCTP)
+
+d) quota support (needs minor kernel change since quota calls otherwise
+   won't make it to network filesystems or deviceless filesystems).
+
+e) Additional use cases can be optimized to use "compounding" (e.g.
+   open/query/close and open/setinfo/close) to reduce the number of
+   roundtrips to the server and improve performance. Various cases
+   (stat, statfs, create, unlink, mkdir, xattrs) already have been improved by
+   using compounding but more can be done. In addition we could
+   significantly reduce redundant opens by using deferred close (with
+   handle caching leases) and better using reference counters on file
+   handles.
+
+f) Finish inotify support so kde and gnome file list windows
+   will autorefresh (partially complete by Asser). Needs minor kernel
+   vfs change to support removing D_NOTIFY on a file.
+
+g) Add GUI tool to configure /proc/fs/cifs settings and for display of
+   the CIFS statistics (started)
+
+h) implement support for security and trusted categories of xattrs
+   (requires minor protocol extension) to enable better support for SELINUX
+
+i) Add support for tree connect contexts (see MS-SMB2) a new SMB3.1.1 protocol
+   feature (may be especially useful for virtualization).
+
+j) Create UID mapping facility so server UIDs can be mapped on a per
+   mount or a per server basis to client UIDs or nobody if no mapping
+   exists. Also better integration with winbind for resolving SID owners
+
+k) Add tools to take advantage of more smb3 specific ioctls and features
+   (passthrough ioctl/fsctl is now implemented in cifs.ko to allow
+   sending various SMB3 fsctls and query info and set info calls
+   directly from user space) Add tools to make setting various non-POSIX
+   metadata attributes easier from tools (e.g. extending what was done
+   in smb-info tool).
+
+l) encrypted file support (currently the attribute showing the file is
+   encrypted on the server is reported, but changing the attribute is not
+   supported).
+
+m) improved stats gathering tools (perhaps integration with nfsometer?)
+   to extend and make easier to use what is currently in /proc/fs/cifs/Stats
+
+n) Add support for claims based ACLs ("DAC")
+
+o) mount helper GUI (to simplify the various configuration options on mount)
+
+p) Expand support for witness protocol to allow for notification of share
+   move, and server network adapter changes. Currently only notifications by
+   the witness protocol for server move is supported by the Linux client.
+
+q) Allow mount.cifs to be more verbose in reporting errors with dialect
+   or unsupported feature errors. This would now be easier due to the
+   implementation of the new mount API.
+
+r) updating cifs documentation, and user guide.
+
+s) Addressing bugs found by running a broader set of xfstests in standard
+   file system xfstest suite.
+
+t) split cifs and smb3 support into separate modules so legacy (and less
+   secure) CIFS dialect can be disabled in environments that don't need it
+   and simplify the code.
+
+v) Additional testing of POSIX Extensions for SMB3.1.1
+
+w) Support for the Mac SMB3.1.1 extensions to improve interop with Apple servers
+
+x) Support for additional authentication options (e.g. IAKERB, peer-to-peer
+   Kerberos, SCRAM and others supported by existing servers)
+
+y) Improved tracing, more eBPF trace points, better scripts for performance
+   analysis
+
+Known Bugs
+==========
+
+See https://bugzilla.samba.org - search on product "CifsVFS" for
+current bug list.  Also check http://bugzilla.kernel.org (Product = File System, Component = CIFS)
+and xfstest results e.g. https://wiki.samba.org/index.php/Xfstest-results-smb3
+
+Misc testing to do
+==================
+1) check out max path names and max path name components against various server
+   types. Try nested symlinks (8 deep). Return max path name in stat -f information
+
+2) Improve xfstest's cifs/smb3 enablement and adapt xfstests where needed to test
+   cifs/smb3 better
+
+3) Additional performance testing and optimization using iozone and similar -
+   there are some easy changes that can be done to parallelize sequential writes,
+   and when signing is disabled to request larger read sizes (larger than
+   negotiated size) and send larger write sizes to modern servers.
+
+4) More exhaustively test against less common servers
+
+5) Continue to extend the smb3 "buildbot" which does automated xfstesting
+   against Windows, Samba and Azure currently - to add additional tests and
+   to allow the buildbot to execute the tests faster. The URL for the
+   buildbot is: http://smb3-test-rhel-75.southcentralus.cloudapp.azure.com
+
+6) Address various coverity warnings (most are not bugs per-se, but
+   the more warnings are addressed, the easier it is to spot real
+   problems that static analyzers will point out in the future).
diff --git a/Documentation/admin-guide/cifs/usage.rst b/Documentation/admin-guide/cifs/usage.rst
new file mode 100644
index 000000000..d989ae577
--- /dev/null
+++ b/Documentation/admin-guide/cifs/usage.rst
@@ -0,0 +1,864 @@
+=====
+Usage
+=====
+
+This module supports the SMB3 family of advanced network protocols (as well
+as older dialects, originally called "CIFS" or SMB1).
+
+The CIFS VFS module for Linux supports many advanced network filesystem
+features such as hierarchical DFS like namespace, hardlinks, locking and more.
+It was designed to comply with the SNIA CIFS Technical Reference (which
+supersedes the 1992 X/Open SMB Standard) as well as to perform best practice
+practical interoperability with Windows 2000, Windows XP, Samba and equivalent
+servers.  This code was developed in participation with the Protocol Freedom
+Information Foundation.  CIFS and now SMB3 has now become a defacto
+standard for interoperating between Macs and Windows and major NAS appliances.
+
+Please see
+MS-SMB2 (for detailed SMB2/SMB3/SMB3.1.1 protocol specification)
+or https://samba.org/samba/PFIF/
+for more details.
+
+
+For questions or bug reports please contact:
+
+    smfrench@gmail.com
+
+See the project page at: https://wiki.samba.org/index.php/LinuxCIFS_utils
+
+Build instructions
+==================
+
+For Linux:
+
+1) Download the kernel (e.g. from https://www.kernel.org)
+   and change directory into the top of the kernel directory tree
+   (e.g. /usr/src/linux-2.5.73)
+2) make menuconfig (or make xconfig)
+3) select cifs from within the network filesystem choices
+4) save and exit
+5) make
+
+
+Installation instructions
+=========================
+
+If you have built the CIFS vfs as module (successfully) simply
+type ``make modules_install`` (or if you prefer, manually copy the file to
+the modules directory e.g. /lib/modules/6.3.0-060300-generic/kernel/fs/smb/client/cifs.ko).
+
+If you have built the CIFS vfs into the kernel itself, follow the instructions
+for your distribution on how to install a new kernel (usually you
+would simply type ``make install``).
+
+If you do not have the utility mount.cifs (in the Samba 4.x source tree and on
+the CIFS VFS web site) copy it to the same directory in which mount helpers
+reside (usually /sbin).  Although the helper software is not
+required, mount.cifs is recommended.  Most distros include a ``cifs-utils``
+package that includes this utility so it is recommended to install this.
+
+Note that running the Winbind pam/nss module (logon service) on all of your
+Linux clients is useful in mapping Uids and Gids consistently across the
+domain to the proper network user.  The mount.cifs mount helper can be
+found at cifs-utils.git on git.samba.org
+
+If cifs is built as a module, then the size and number of network buffers
+and maximum number of simultaneous requests to one server can be configured.
+Changing these from their defaults is not recommended. By executing modinfo::
+
+	modinfo <path to cifs.ko>
+
+on kernel/fs/smb/client/cifs.ko the list of configuration changes that can be made
+at module initialization time (by running insmod cifs.ko) can be seen.
+
+Recommendations
+===============
+
+To improve security the SMB2.1 dialect or later (usually will get SMB3.1.1) is now
+the new default. To use old dialects (e.g. to mount Windows XP) use "vers=1.0"
+on mount (or vers=2.0 for Windows Vista).  Note that the CIFS (vers=1.0) is
+much older and less secure than the default dialect SMB3 which includes
+many advanced security features such as downgrade attack detection
+and encrypted shares and stronger signing and authentication algorithms.
+There are additional mount options that may be helpful for SMB3 to get
+improved POSIX behavior (NB: can use vers=3 to force SMB3 or later, never 2.1):
+
+   ``mfsymlinks`` and either ``cifsacl`` or ``modefromsid`` (usually with ``idsfromsid``)
+
+Allowing User Mounts
+====================
+
+To permit users to mount and unmount over directories they own is possible
+with the cifs vfs.  A way to enable such mounting is to mark the mount.cifs
+utility as suid (e.g. ``chmod +s /sbin/mount.cifs``). To enable users to
+umount shares they mount requires
+
+1) mount.cifs version 1.4 or later
+2) an entry for the share in /etc/fstab indicating that a user may
+   unmount it e.g.::
+
+     //server/usersharename  /mnt/username cifs user 0 0
+
+Note that when the mount.cifs utility is run suid (allowing user mounts),
+in order to reduce risks, the ``nosuid`` mount flag is passed in on mount to
+disallow execution of an suid program mounted on the remote target.
+When mount is executed as root, nosuid is not passed in by default,
+and execution of suid programs on the remote target would be enabled
+by default. This can be changed, as with nfs and other filesystems,
+by simply specifying ``nosuid`` among the mount options. For user mounts
+though to be able to pass the suid flag to mount requires rebuilding
+mount.cifs with the following flag: CIFS_ALLOW_USR_SUID
+
+There is a corresponding manual page for cifs mounting in the Samba 3.0 and
+later source tree in docs/manpages/mount.cifs.8
+
+Allowing User Unmounts
+======================
+
+To permit users to unmount directories that they have user mounted (see above),
+the utility umount.cifs may be used.  It may be invoked directly, or if
+umount.cifs is placed in /sbin, umount can invoke the cifs umount helper
+(at least for most versions of the umount utility) for umount of cifs
+mounts, unless umount is invoked with -i (which will avoid invoking a umount
+helper). As with mount.cifs, to enable user unmounts umount.cifs must be marked
+as suid (e.g. ``chmod +s /sbin/umount.cifs``) or equivalent (some distributions
+allow adding entries to a file to the /etc/permissions file to achieve the
+equivalent suid effect).  For this utility to succeed the target path
+must be a cifs mount, and the uid of the current user must match the uid
+of the user who mounted the resource.
+
+Also note that the customary way of allowing user mounts and unmounts is
+(instead of using mount.cifs and unmount.cifs as suid) to add a line
+to the file /etc/fstab for each //server/share you wish to mount, but
+this can become unwieldy when potential mount targets include many
+or  unpredictable UNC names.
+
+Samba Considerations
+====================
+
+Most current servers support SMB2.1 and SMB3 which are more secure,
+but there are useful protocol extensions for the older less secure CIFS
+dialect, so to get the maximum benefit if mounting using the older dialect
+(CIFS/SMB1), we recommend using a server that supports the SNIA CIFS
+Unix Extensions standard (e.g. almost any  version of Samba ie version
+2.2.5 or later) but the CIFS vfs works fine with a wide variety of CIFS servers.
+Note that uid, gid and file permissions will display default values if you do
+not have a server that supports the Unix extensions for CIFS (such as Samba
+2.2.5 or later).  To enable the Unix CIFS Extensions in the Samba server, add
+the line::
+
+	unix extensions = yes
+
+to your smb.conf file on the server.  Note that the following smb.conf settings
+are also useful (on the Samba server) when the majority of clients are Unix or
+Linux::
+
+	case sensitive = yes
+	delete readonly = yes
+	ea support = yes
+
+Note that server ea support is required for supporting xattrs from the Linux
+cifs client, and that EA support is present in later versions of Samba (e.g.
+3.0.6 and later (also EA support works in all versions of Windows, at least to
+shares on NTFS filesystems).  Extended Attribute (xattr) support is an optional
+feature of most Linux filesystems which may require enabling via
+make menuconfig. Client support for extended attributes (user xattr) can be
+disabled on a per-mount basis by specifying ``nouser_xattr`` on mount.
+
+The CIFS client can get and set POSIX ACLs (getfacl, setfacl) to Samba servers
+version 3.10 and later.  Setting POSIX ACLs requires enabling both XATTR and
+then POSIX support in the CIFS configuration options when building the cifs
+module.  POSIX ACL support can be disabled on a per mount basic by specifying
+``noacl`` on mount.
+
+Some administrators may want to change Samba's smb.conf ``map archive`` and
+``create mask`` parameters from the default.  Unless the create mask is changed
+newly created files can end up with an unnecessarily restrictive default mode,
+which may not be what you want, although if the CIFS Unix extensions are
+enabled on the server and client, subsequent setattr calls (e.g. chmod) can
+fix the mode.  Note that creating special devices (mknod) remotely
+may require specifying a mkdev function to Samba if you are not using
+Samba 3.0.6 or later.  For more information on these see the manual pages
+(``man smb.conf``) on the Samba server system.  Note that the cifs vfs,
+unlike the smbfs vfs, does not read the smb.conf on the client system
+(the few optional settings are passed in on mount via -o parameters instead).
+Note that Samba 2.2.7 or later includes a fix that allows the CIFS VFS to delete
+open files (required for strict POSIX compliance).  Windows Servers already
+supported this feature. Samba server does not allow symlinks that refer to files
+outside of the share, so in Samba versions prior to 3.0.6, most symlinks to
+files with absolute paths (ie beginning with slash) such as::
+
+	 ln -s /mnt/foo bar
+
+would be forbidden. Samba 3.0.6 server or later includes the ability to create
+such symlinks safely by converting unsafe symlinks (ie symlinks to server
+files that are outside of the share) to a samba specific format on the server
+that is ignored by local server applications and non-cifs clients and that will
+not be traversed by the Samba server).  This is opaque to the Linux client
+application using the cifs vfs. Absolute symlinks will work to Samba 3.0.5 or
+later, but only for remote clients using the CIFS Unix extensions, and will
+be invisible to Windows clients and typically will not affect local
+applications running on the same server as Samba.
+
+Use instructions
+================
+
+Once the CIFS VFS support is built into the kernel or installed as a module
+(cifs.ko), you can use mount syntax like the following to access Samba or
+Mac or Windows servers::
+
+  mount -t cifs //9.53.216.11/e$ /mnt -o username=myname,password=mypassword
+
+Before -o the option -v may be specified to make the mount.cifs
+mount helper display the mount steps more verbosely.
+After -o the following commonly used cifs vfs specific options
+are supported::
+
+  username=<username>
+  password=<password>
+  domain=<domain name>
+
+Other cifs mount options are described below.  Use of TCP names (in addition to
+ip addresses) is available if the mount helper (mount.cifs) is installed. If
+you do not trust the server to which are mounted, or if you do not have
+cifs signing enabled (and the physical network is insecure), consider use
+of the standard mount options ``noexec`` and ``nosuid`` to reduce the risk of
+running an altered binary on your local system (downloaded from a hostile server
+or altered by a hostile router).
+
+Although mounting using format corresponding to the CIFS URL specification is
+not possible in mount.cifs yet, it is possible to use an alternate format
+for the server and sharename (which is somewhat similar to NFS style mount
+syntax) instead of the more widely used UNC format (i.e. \\server\share)::
+
+  mount -t cifs tcp_name_of_server:share_name /mnt -o user=myname,pass=mypasswd
+
+When using the mount helper mount.cifs, passwords may be specified via alternate
+mechanisms, instead of specifying it after -o using the normal ``pass=`` syntax
+on the command line:
+1) By including it in a credential file. Specify credentials=filename as one
+of the mount options. Credential files contain two lines::
+
+	username=someuser
+	password=your_password
+
+2) By specifying the password in the PASSWD environment variable (similarly
+   the user name can be taken from the USER environment variable).
+3) By specifying the password in a file by name via PASSWD_FILE
+4) By specifying the password in a file by file descriptor via PASSWD_FD
+
+If no password is provided, mount.cifs will prompt for password entry
+
+Restrictions
+============
+
+Servers must support either "pure-TCP" (port 445 TCP/IP CIFS connections) or RFC
+1001/1002 support for "Netbios-Over-TCP/IP." This is not likely to be a
+problem as most servers support this.
+
+Valid filenames differ between Windows and Linux.  Windows typically restricts
+filenames which contain certain reserved characters (e.g.the character :
+which is used to delimit the beginning of a stream name by Windows), while
+Linux allows a slightly wider set of valid characters in filenames. Windows
+servers can remap such characters when an explicit mapping is specified in
+the Server's registry.  Samba starting with version 3.10 will allow such
+filenames (ie those which contain valid Linux characters, which normally
+would be forbidden for Windows/CIFS semantics) as long as the server is
+configured for Unix Extensions (and the client has not disabled
+/proc/fs/cifs/LinuxExtensionsEnabled). In addition the mount option
+``mapposix`` can be used on CIFS (vers=1.0) to force the mapping of
+illegal Windows/NTFS/SMB characters to a remap range (this mount parameter
+is the default for SMB3). This remap (``mapposix``) range is also
+compatible with Mac (and "Services for Mac" on some older Windows).
+When POSIX Extensions for SMB 3.1.1 are negotiated, remapping is automatically
+disabled.
+
+CIFS VFS Mount Options
+======================
+A partial list of the supported mount options follows:
+
+  username
+		The user name to use when trying to establish
+		the CIFS session.
+  password
+		The user password.  If the mount helper is
+		installed, the user will be prompted for password
+		if not supplied.
+  ip
+		The ip address of the target server
+  unc
+		The target server Universal Network Name (export) to
+		mount.
+  domain
+		Set the SMB/CIFS workgroup name prepended to the
+		username during CIFS session establishment
+  forceuid
+		Set the default uid for inodes to the uid
+		passed in on mount. For mounts to servers
+		which do support the CIFS Unix extensions, such as a
+		properly configured Samba server, the server provides
+		the uid, gid and mode so this parameter should not be
+		specified unless the server and clients uid and gid
+		numbering differ.  If the server and client are in the
+		same domain (e.g. running winbind or nss_ldap) and
+		the server supports the Unix Extensions then the uid
+		and gid can be retrieved from the server (and uid
+		and gid would not have to be specified on the mount.
+		For servers which do not support the CIFS Unix
+		extensions, the default uid (and gid) returned on lookup
+		of existing files will be the uid (gid) of the person
+		who executed the mount (root, except when mount.cifs
+		is configured setuid for user mounts) unless the ``uid=``
+		(gid) mount option is specified. Also note that permission
+		checks (authorization checks) on accesses to a file occur
+		at the server, but there are cases in which an administrator
+		may want to restrict at the client as well.  For those
+		servers which do not report a uid/gid owner
+		(such as Windows), permissions can also be checked at the
+		client, and a crude form of client side permission checking
+		can be enabled by specifying file_mode and dir_mode on
+		the client.  (default)
+  forcegid
+		(similar to above but for the groupid instead of uid) (default)
+  noforceuid
+		Fill in file owner information (uid) by requesting it from
+		the server if possible. With this option, the value given in
+		the uid= option (on mount) will only be used if the server
+		can not support returning uids on inodes.
+  noforcegid
+		(similar to above but for the group owner, gid, instead of uid)
+  uid
+		Set the default uid for inodes, and indicate to the
+		cifs kernel driver which local user mounted. If the server
+		supports the unix extensions the default uid is
+		not used to fill in the owner fields of inodes (files)
+		unless the ``forceuid`` parameter is specified.
+  gid
+		Set the default gid for inodes (similar to above).
+  file_mode
+		If CIFS Unix extensions are not supported by the server
+		this overrides the default mode for file inodes.
+  fsc
+		Enable local disk caching using FS-Cache (off by default). This
+		option could be useful to improve performance on a slow link,
+		heavily loaded server and/or network where reading from the
+		disk is faster than reading from the server (over the network).
+		This could also impact scalability positively as the
+		number of calls to the server are reduced. However, local
+		caching is not suitable for all workloads for e.g. read-once
+		type workloads. So, you need to consider carefully your
+		workload/scenario before using this option. Currently, local
+		disk caching is functional for CIFS files opened as read-only.
+  dir_mode
+		If CIFS Unix extensions are not supported by the server
+		this overrides the default mode for directory inodes.
+  port
+		attempt to contact the server on this tcp port, before
+		trying the usual ports (port 445, then 139).
+  iocharset
+		Codepage used to convert local path names to and from
+		Unicode. Unicode is used by default for network path
+		names if the server supports it.  If iocharset is
+		not specified then the nls_default specified
+		during the local client kernel build will be used.
+		If server does not support Unicode, this parameter is
+		unused.
+  rsize
+		default read size (usually 16K). The client currently
+		can not use rsize larger than CIFSMaxBufSize. CIFSMaxBufSize
+		defaults to 16K and may be changed (from 8K to the maximum
+		kmalloc size allowed by your kernel) at module install time
+		for cifs.ko. Setting CIFSMaxBufSize to a very large value
+		will cause cifs to use more memory and may reduce performance
+		in some cases.  To use rsize greater than 127K (the original
+		cifs protocol maximum) also requires that the server support
+		a new Unix Capability flag (for very large read) which some
+		newer servers (e.g. Samba 3.0.26 or later) do. rsize can be
+		set from a minimum of 2048 to a maximum of 130048 (127K or
+		CIFSMaxBufSize, whichever is smaller)
+  wsize
+		default write size (default 57344)
+		maximum wsize currently allowed by CIFS is 57344 (fourteen
+		4096 byte pages)
+  actimeo=n
+		attribute cache timeout in seconds (default 1 second).
+		After this timeout, the cifs client requests fresh attribute
+		information from the server. This option allows to tune the
+		attribute cache timeout to suit the workload needs. Shorter
+		timeouts mean better the cache coherency, but increased number
+		of calls to the server. Longer timeouts mean reduced number
+		of calls to the server at the expense of less stricter cache
+		coherency checks (i.e. incorrect attribute cache for a short
+		period of time).
+  rw
+		mount the network share read-write (note that the
+		server may still consider the share read-only)
+  ro
+		mount network share read-only
+  version
+		used to distinguish different versions of the
+		mount helper utility (not typically needed)
+  sep
+		if first mount option (after the -o), overrides
+		the comma as the separator between the mount
+		parameters. e.g.::
+
+			-o user=myname,password=mypassword,domain=mydom
+
+		could be passed instead with period as the separator by::
+
+			-o sep=.user=myname.password=mypassword.domain=mydom
+
+		this might be useful when comma is contained within username
+		or password or domain. This option is less important
+		when the cifs mount helper cifs.mount (version 1.1 or later)
+		is used.
+  nosuid
+		Do not allow remote executables with the suid bit
+		program to be executed.  This is only meaningful for mounts
+		to servers such as Samba which support the CIFS Unix Extensions.
+		If you do not trust the servers in your network (your mount
+		targets) it is recommended that you specify this option for
+		greater security.
+  exec
+		Permit execution of binaries on the mount.
+  noexec
+		Do not permit execution of binaries on the mount.
+  dev
+		Recognize block devices on the remote mount.
+  nodev
+		Do not recognize devices on the remote mount.
+  suid
+		Allow remote files on this mountpoint with suid enabled to
+		be executed (default for mounts when executed as root,
+		nosuid is default for user mounts).
+  credentials
+		Although ignored by the cifs kernel component, it is used by
+		the mount helper, mount.cifs. When mount.cifs is installed it
+		opens and reads the credential file specified in order
+		to obtain the userid and password arguments which are passed to
+		the cifs vfs.
+  guest
+		Although ignored by the kernel component, the mount.cifs
+		mount helper will not prompt the user for a password
+		if guest is specified on the mount options.  If no
+		password is specified a null password will be used.
+  perm
+		Client does permission checks (vfs_permission check of uid
+		and gid of the file against the mode and desired operation),
+		Note that this is in addition to the normal ACL check on the
+		target machine done by the server software.
+		Client permission checking is enabled by default.
+  noperm
+		Client does not do permission checks.  This can expose
+		files on this mount to access by other users on the local
+		client system. It is typically only needed when the server
+		supports the CIFS Unix Extensions but the UIDs/GIDs on the
+		client and server system do not match closely enough to allow
+		access by the user doing the mount, but it may be useful with
+		non CIFS Unix Extension mounts for cases in which the default
+		mode is specified on the mount but is not to be enforced on the
+		client (e.g. perhaps when MultiUserMount is enabled)
+		Note that this does not affect the normal ACL check on the
+		target machine done by the server software (of the server
+		ACL against the user name provided at mount time).
+  serverino
+		Use server's inode numbers instead of generating automatically
+		incrementing inode numbers on the client.  Although this will
+		make it easier to spot hardlinked files (as they will have
+		the same inode numbers) and inode numbers may be persistent,
+		note that the server does not guarantee that the inode numbers
+		are unique if multiple server side mounts are exported under a
+		single share (since inode numbers on the servers might not
+		be unique if multiple filesystems are mounted under the same
+		shared higher level directory).  Note that some older
+		(e.g. pre-Windows 2000) do not support returning UniqueIDs
+		or the CIFS Unix Extensions equivalent and for those
+		this mount option will have no effect.  Exporting cifs mounts
+		under nfsd requires this mount option on the cifs mount.
+		This is now the default if server supports the
+		required network operation.
+  noserverino
+		Client generates inode numbers (rather than using the actual one
+		from the server). These inode numbers will vary after
+		unmount or reboot which can confuse some applications,
+		but not all server filesystems support unique inode
+		numbers.
+  setuids
+		If the CIFS Unix extensions are negotiated with the server
+		the client will attempt to set the effective uid and gid of
+		the local process on newly created files, directories, and
+		devices (create, mkdir, mknod).  If the CIFS Unix Extensions
+		are not negotiated, for newly created files and directories
+		instead of using the default uid and gid specified on
+		the mount, cache the new file's uid and gid locally which means
+		that the uid for the file can change when the inode is
+		reloaded (or the user remounts the share).
+  nosetuids
+		The client will not attempt to set the uid and gid on
+		on newly created files, directories, and devices (create,
+		mkdir, mknod) which will result in the server setting the
+		uid and gid to the default (usually the server uid of the
+		user who mounted the share).  Letting the server (rather than
+		the client) set the uid and gid is the default. If the CIFS
+		Unix Extensions are not negotiated then the uid and gid for
+		new files will appear to be the uid (gid) of the mounter or the
+		uid (gid) parameter specified on the mount.
+  netbiosname
+		When mounting to servers via port 139, specifies the RFC1001
+		source name to use to represent the client netbios machine
+		name when doing the RFC1001 netbios session initialize.
+  direct
+		Do not do inode data caching on files opened on this mount.
+		This precludes mmapping files on this mount. In some cases
+		with fast networks and little or no caching benefits on the
+		client (e.g. when the application is doing large sequential
+		reads bigger than page size without rereading the same data)
+		this can provide better performance than the default
+		behavior which caches reads (readahead) and writes
+		(writebehind) through the local Linux client pagecache
+		if oplock (caching token) is granted and held. Note that
+		direct allows write operations larger than page size
+		to be sent to the server.
+  strictcache
+		Use for switching on strict cache mode. In this mode the
+		client read from the cache all the time it has Oplock Level II,
+		otherwise - read from the server. All written data are stored
+		in the cache, but if the client doesn't have Exclusive Oplock,
+		it writes the data to the server.
+  rwpidforward
+		Forward pid of a process who opened a file to any read or write
+		operation on that file. This prevent applications like WINE
+		from failing on read and write if we use mandatory brlock style.
+  acl
+		Allow setfacl and getfacl to manage posix ACLs if server
+		supports them.  (default)
+  noacl
+		Do not allow setfacl and getfacl calls on this mount
+  user_xattr
+		Allow getting and setting user xattrs (those attributes whose
+		name begins with ``user.`` or ``os2.``) as OS/2 EAs (extended
+		attributes) to the server.  This allows support of the
+		setfattr and getfattr utilities. (default)
+  nouser_xattr
+		Do not allow getfattr/setfattr to get/set/list xattrs
+  mapchars
+		Translate six of the seven reserved characters (not backslash)::
+
+			*?<>|:
+
+		to the remap range (above 0xF000), which also
+		allows the CIFS client to recognize files created with
+		such characters by Windows's POSIX emulation. This can
+		also be useful when mounting to most versions of Samba
+		(which also forbids creating and opening files
+		whose names contain any of these seven characters).
+		This has no effect if the server does not support
+		Unicode on the wire.
+  nomapchars
+		Do not translate any of these seven characters (default).
+  nocase
+		Request case insensitive path name matching (case
+		sensitive is the default if the server supports it).
+		(mount option ``ignorecase`` is identical to ``nocase``)
+  posixpaths
+		If CIFS Unix extensions are supported, attempt to
+		negotiate posix path name support which allows certain
+		characters forbidden in typical CIFS filenames, without
+		requiring remapping. (default)
+  noposixpaths
+		If CIFS Unix extensions are supported, do not request
+		posix path name support (this may cause servers to
+		reject creatingfile with certain reserved characters).
+  nounix
+		Disable the CIFS Unix Extensions for this mount (tree
+		connection). This is rarely needed, but it may be useful
+		in order to turn off multiple settings all at once (ie
+		posix acls, posix locks, posix paths, symlink support
+		and retrieving uids/gids/mode from the server) or to
+		work around a bug in server which implement the Unix
+		Extensions.
+  nobrl
+		Do not send byte range lock requests to the server.
+		This is necessary for certain applications that break
+		with cifs style mandatory byte range locks (and most
+		cifs servers do not yet support requesting advisory
+		byte range locks).
+  forcemandatorylock
+		Even if the server supports posix (advisory) byte range
+		locking, send only mandatory lock requests.  For some
+		(presumably rare) applications, originally coded for
+		DOS/Windows, which require Windows style mandatory byte range
+		locking, they may be able to take advantage of this option,
+		forcing the cifs client to only send mandatory locks
+		even if the cifs server would support posix advisory locks.
+		``forcemand`` is accepted as a shorter form of this mount
+		option.
+  nostrictsync
+		If this mount option is set, when an application does an
+		fsync call then the cifs client does not send an SMB Flush
+		to the server (to force the server to write all dirty data
+		for this file immediately to disk), although cifs still sends
+		all dirty (cached) file data to the server and waits for the
+		server to respond to the write.  Since SMB Flush can be
+		very slow, and some servers may be reliable enough (to risk
+		delaying slightly flushing the data to disk on the server),
+		turning on this option may be useful to improve performance for
+		applications that fsync too much, at a small risk of server
+		crash.  If this mount option is not set, by default cifs will
+		send an SMB flush request (and wait for a response) on every
+		fsync call.
+  nodfs
+		Disable DFS (global name space support) even if the
+		server claims to support it.  This can help work around
+		a problem with parsing of DFS paths with Samba server
+		versions 3.0.24 and 3.0.25.
+  remount
+		remount the share (often used to change from ro to rw mounts
+		or vice versa)
+  cifsacl
+		Report mode bits (e.g. on stat) based on the Windows ACL for
+		the file. (EXPERIMENTAL)
+  servern
+		Specify the server 's netbios name (RFC1001 name) to use
+		when attempting to setup a session to the server.
+		This is needed for mounting to some older servers (such
+		as OS/2 or Windows 98 and Windows ME) since they do not
+		support a default server name.  A server name can be up
+		to 15 characters long and is usually uppercased.
+  sfu
+		When the CIFS Unix Extensions are not negotiated, attempt to
+		create device files and fifos in a format compatible with
+		Services for Unix (SFU).  In addition retrieve bits 10-12
+		of the mode via the SETFILEBITS extended attribute (as
+		SFU does).  In the future the bottom 9 bits of the
+		mode also will be emulated using queries of the security
+		descriptor (ACL).
+  mfsymlinks
+		Enable support for Minshall+French symlinks
+		(see http://wiki.samba.org/index.php/UNIX_Extensions#Minshall.2BFrench_symlinks)
+		This option is ignored when specified together with the
+		'sfu' option. Minshall+French symlinks are used even if
+		the server supports the CIFS Unix Extensions.
+  sign
+		Must use packet signing (helps avoid unwanted data modification
+		by intermediate systems in the route).  Note that signing
+		does not work with lanman or plaintext authentication.
+  seal
+		Must seal (encrypt) all data on this mounted share before
+		sending on the network.  Requires support for Unix Extensions.
+		Note that this differs from the sign mount option in that it
+		causes encryption of data sent over this mounted share but other
+		shares mounted to the same server are unaffected.
+  locallease
+		This option is rarely needed. Fcntl F_SETLEASE is
+		used by some applications such as Samba and NFSv4 server to
+		check to see whether a file is cacheable.  CIFS has no way
+		to explicitly request a lease, but can check whether a file
+		is cacheable (oplocked).  Unfortunately, even if a file
+		is not oplocked, it could still be cacheable (ie cifs client
+		could grant fcntl leases if no other local processes are using
+		the file) for cases for example such as when the server does not
+		support oplocks and the user is sure that the only updates to
+		the file will be from this client. Specifying this mount option
+		will allow the cifs client to check for leases (only) locally
+		for files which are not oplocked instead of denying leases
+		in that case. (EXPERIMENTAL)
+  sec
+		Security mode.  Allowed values are:
+
+			none
+				attempt to connection as a null user (no name)
+			krb5
+				Use Kerberos version 5 authentication
+			krb5i
+				Use Kerberos authentication and packet signing
+			ntlm
+				Use NTLM password hashing (default)
+			ntlmi
+				Use NTLM password hashing with signing (if
+				/proc/fs/cifs/PacketSigningEnabled on or if
+				server requires signing also can be the default)
+			ntlmv2
+				Use NTLMv2 password hashing
+			ntlmv2i
+				Use NTLMv2 password hashing with packet signing
+			lanman
+				(if configured in kernel config) use older
+				lanman hash
+  hard
+		Retry file operations if server is not responding
+  soft
+		Limit retries to unresponsive servers (usually only
+		one retry) before returning an error.  (default)
+
+The mount.cifs mount helper also accepts a few mount options before -o
+including:
+
+=============== ===============================================================
+	-S      take password from stdin (equivalent to setting the environment
+		variable ``PASSWD_FD=0``
+	-V      print mount.cifs version
+	-?      display simple usage information
+=============== ===============================================================
+
+With most 2.6 kernel versions of modutils, the version of the cifs kernel
+module can be displayed via modinfo.
+
+Misc /proc/fs/cifs Flags and Debug Info
+=======================================
+
+Informational pseudo-files:
+
+======================= =======================================================
+DebugData		Displays information about active CIFS sessions and
+			shares, features enabled as well as the cifs.ko
+			version.
+Stats			Lists summary resource usage information as well as per
+			share statistics.
+open_files		List all the open file handles on all active SMB sessions.
+mount_params            List of all mount parameters available for the module
+======================= =======================================================
+
+Configuration pseudo-files:
+
+======================= =======================================================
+SecurityFlags		Flags which control security negotiation and
+			also packet signing. Authentication (may/must)
+			flags (e.g. for NTLMv2) may be combined with
+			the signing flags.  Specifying two different password
+			hashing mechanisms (as "must use") on the other hand
+			does not make much sense. Default flags are::
+
+				0x00C5
+
+			(NTLMv2 and packet signing allowed).  Some SecurityFlags
+			may require enabling a corresponding menuconfig option.
+
+			  may use packet signing			0x00001
+			  must use packet signing			0x01001
+			  may use NTLMv2				0x00004
+			  must use NTLMv2				0x04004
+			  may use Kerberos security (krb5)		0x00008
+			  must use Kerberos                             0x08008
+			  may use NTLMSSP               		0x00080
+			  must use NTLMSSP           			0x80080
+			  seal (packet encryption)			0x00040
+			  must seal                                     0x40040
+
+cifsFYI			If set to non-zero value, additional debug information
+			will be logged to the system error log.  This field
+			contains three flags controlling different classes of
+			debugging entries.  The maximum value it can be set
+			to is 7 which enables all debugging points (default 0).
+			Some debugging statements are not compiled into the
+			cifs kernel unless CONFIG_CIFS_DEBUG2 is enabled in the
+			kernel configuration. cifsFYI may be set to one or
+			more of the following flags (7 sets them all)::
+
+			  +-----------------------------------------------+------+
+			  | log cifs informational messages		  | 0x01 |
+			  +-----------------------------------------------+------+
+			  | log return codes from cifs entry points	  | 0x02 |
+			  +-----------------------------------------------+------+
+			  | log slow responses				  | 0x04 |
+			  | (ie which take longer than 1 second)	  |      |
+			  |                                               |      |
+			  | CONFIG_CIFS_STATS2 must be enabled in .config |      |
+			  +-----------------------------------------------+------+
+
+traceSMB		If set to one, debug information is logged to the
+			system error log with the start of smb requests
+			and responses (default 0)
+LookupCacheEnable	If set to one, inode information is kept cached
+			for one second improving performance of lookups
+			(default 1)
+LinuxExtensionsEnabled	If set to one then the client will attempt to
+			use the CIFS "UNIX" extensions which are optional
+			protocol enhancements that allow CIFS servers
+			to return accurate UID/GID information as well
+			as support symbolic links. If you use servers
+			such as Samba that support the CIFS Unix
+			extensions but do not want to use symbolic link
+			support and want to map the uid and gid fields
+			to values supplied at mount (rather than the
+			actual values, then set this to zero. (default 1)
+dfscache		List the content of the DFS cache.
+			If set to 0, the client will clear the cache.
+======================= =======================================================
+
+These experimental features and tracing can be enabled by changing flags in
+/proc/fs/cifs (after the cifs module has been installed or built into the
+kernel, e.g.  insmod cifs).  To enable a feature set it to 1 e.g.  to enable
+tracing to the kernel message log type::
+
+	echo 7 > /proc/fs/cifs/cifsFYI
+
+cifsFYI functions as a bit mask. Setting it to 1 enables additional kernel
+logging of various informational messages.  2 enables logging of non-zero
+SMB return codes while 4 enables logging of requests that take longer
+than one second to complete (except for byte range lock requests).
+Setting it to 4 requires CONFIG_CIFS_STATS2 to be set in kernel configuration
+(.config). Setting it to seven enables all three.  Finally, tracing
+the start of smb requests and responses can be enabled via::
+
+	echo 1 > /proc/fs/cifs/traceSMB
+
+Per share (per client mount) statistics are available in /proc/fs/cifs/Stats.
+Additional information is available if CONFIG_CIFS_STATS2 is enabled in the
+kernel configuration (.config).  The statistics returned include counters which
+represent the number of attempted and failed (ie non-zero return code from the
+server) SMB3 (or cifs) requests grouped by request type (read, write, close etc.).
+Also recorded is the total bytes read and bytes written to the server for
+that share.  Note that due to client caching effects this can be less than the
+number of bytes read and written by the application running on the client.
+Statistics can be reset to zero by ``echo 0 > /proc/fs/cifs/Stats`` which may be
+useful if comparing performance of two different scenarios.
+
+Also note that ``cat /proc/fs/cifs/DebugData`` will display information about
+the active sessions and the shares that are mounted.
+
+Enabling Kerberos (extended security) works but requires version 1.2 or later
+of the helper program cifs.upcall to be present and to be configured in the
+/etc/request-key.conf file.  The cifs.upcall helper program is from the Samba
+project(https://www.samba.org). NTLM and NTLMv2 and LANMAN support do not
+require this helper. Note that NTLMv2 security (which does not require the
+cifs.upcall helper program), instead of using Kerberos, is sufficient for
+some use cases.
+
+DFS support allows transparent redirection to shares in an MS-DFS name space.
+In addition, DFS support for target shares which are specified as UNC
+names which begin with host names (rather than IP addresses) requires
+a user space helper (such as cifs.upcall) to be present in order to
+translate host names to ip address, and the user space helper must also
+be configured in the file /etc/request-key.conf.  Samba, Windows servers and
+many NAS appliances support DFS as a way of constructing a global name
+space to ease network configuration and improve reliability.
+
+To use cifs Kerberos and DFS support, the Linux keyutils package should be
+installed and something like the following lines should be added to the
+/etc/request-key.conf file::
+
+  create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
+  create dns_resolver * * /usr/local/sbin/cifs.upcall %k
+
+CIFS kernel module parameters
+=============================
+These module parameters can be specified or modified either during the time of
+module loading or during the runtime by using the interface::
+
+	/sys/module/cifs/parameters/<param>
+
+i.e.::
+
+    echo "value" > /sys/module/cifs/parameters/<param>
+
+More detailed descriptions of the available module parameters and their values
+can be seen by doing:
+
+    modinfo cifs (or modinfo smb3)
+
+================= ==========================================================
+1. enable_oplocks Enable or disable oplocks. Oplocks are enabled by default.
+		  [Y/y/1]. To disable use any of [N/n/0].
+================= ==========================================================
diff --git a/Documentation/admin-guide/cifs/winucase_convert.pl b/Documentation/admin-guide/cifs/winucase_convert.pl
new file mode 100755
index 000000000..993186bee
--- /dev/null
+++ b/Documentation/admin-guide/cifs/winucase_convert.pl
@@ -0,0 +1,62 @@
+#!/usr/bin/perl -w
+#
+# winucase_convert.pl -- convert "Windows 8 Upper Case Mapping Table.txt" to
+#                        a two-level set of C arrays.
+#
+#   Copyright 2013: Jeff Layton <jlayton@redhat.com>
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+
+while(<>) {
+	next if (!/^0x(..)(..)\t0x(....)\t/);
+	$firstchar = hex($1);
+	$secondchar = hex($2);
+	$uppercase = hex($3);
+
+	$top[$firstchar][$secondchar] = $uppercase;
+}
+
+for ($i = 0; $i < 256; $i++) {
+	next if (!$top[$i]);
+
+	printf("static const wchar_t t2_%2.2x[256] = {", $i);
+	for ($j = 0; $j < 256; $j++) {
+		if (($j % 8) == 0) {
+			print "\n\t";
+		} else {
+			print " ";
+		}
+		printf("0x%4.4x,", $top[$i][$j] ? $top[$i][$j] : 0);
+	}
+	print "\n};\n\n";
+}
+
+printf("static const wchar_t *const toplevel[256] = {", $i);
+for ($i = 0; $i < 256; $i++) {
+	if (($i % 8) == 0) {
+		print "\n\t";
+	} elsif ($top[$i]) {
+		print " ";
+	} else {
+		print "  ";
+	}
+
+	if ($top[$i]) {
+		printf("t2_%2.2x,", $i);
+	} else {
+		print "NULL,";
+	}
+}
+print "\n};\n\n";
diff --git a/Documentation/admin-guide/clearing-warn-once.rst b/Documentation/admin-guide/clearing-warn-once.rst
new file mode 100644
index 000000000..211fd926c
--- /dev/null
+++ b/Documentation/admin-guide/clearing-warn-once.rst
@@ -0,0 +1,9 @@
+Clearing WARN_ONCE
+------------------
+
+WARN_ONCE / WARN_ON_ONCE / printk_once only emit a message once.
+
+echo 1 > /sys/kernel/debug/clear_warn_once
+
+clears the state and allows the warnings to print once again.
+This can be useful after test suite runs to reproduce problems.
diff --git a/Documentation/admin-guide/cpu-isolation.rst b/Documentation/admin-guide/cpu-isolation.rst
new file mode 100644
index 000000000..8c65d03fd
--- /dev/null
+++ b/Documentation/admin-guide/cpu-isolation.rst
@@ -0,0 +1,357 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+CPU Isolation
+=============
+
+Introduction
+============
+
+"CPU Isolation" means leaving a CPU exclusive to a given workload
+without any undesired code interference from the kernel.
+
+Those interferences, commonly pointed out as "noise", can be triggered
+by asynchronous events (interrupts, timers, scheduler preemption by
+workqueues and kthreads, ...) or synchronous events (syscalls and page
+faults).
+
+Such noise usually goes unnoticed. After all, synchronous events are a
+component of the requested kernel service. And asynchronous events are
+either sufficiently well-distributed by the scheduler when executed
+as tasks or reasonably fast when executed as interrupt. The timer
+interrupt can even execute 1024 times per seconds without a significant
+and measurable impact most of the time.
+
+However some rare and extreme workloads can be quite sensitive to
+those kinds of noise. This is the case, for example, with high
+bandwidth network processing that can't afford losing a single packet
+or very low latency network processing. Typically those use cases
+involve DPDK, bypassing the kernel networking stack and performing
+direct access to the networking device from userspace.
+
+In order to run a CPU without or with limited kernel noise, the
+related housekeeping work needs to be either shut down, migrated or
+offloaded.
+
+Housekeeping
+============
+
+In the CPU isolation terminology, housekeeping is the work, often
+asynchronous, that the kernel needs to process in order to maintain
+all its services. It matches the noises and disturbances enumerated
+above except when at least one CPU is isolated. Then housekeeping may
+make use of further coping mechanisms if CPU-tied work must be
+offloaded.
+
+Housekeeping CPUs are the non-isolated CPUs where the kernel noise
+is moved away from isolated CPUs.
+
+The isolation can be implemented in several ways depending on the
+nature of the noise:
+
+- Unbound work, where "unbound" means not tied to any CPU, can be
+  simply migrated away from isolated CPUs to housekeeping CPUs.
+  This is the case of unbound workqueues, kthreads and timers.
+
+- Bound work, where "bound" means tied to a specific CPU, usually
+  can't be moved away as-is by nature. Either:
+
+	- The work must switch to a locked implementation. E.g.:
+	  This is the case of RCU with CONFIG_RCU_NOCB_CPU.
+
+	- The related feature must be shut down and considered
+	  incompatible with isolated CPUs. E.g.: Lockup watchdog,
+	  unreliable clocksources, etc...
+
+	- An elaborate and heavyweight coping mechanism stands as a
+	  replacement. E.g.: the timer tick is shut down on nohz_full
+	  CPUs but with the constraint of running a single task on
+	  them. A significant cost penalty is added on kernel entry/exit
+	  and a residual 1Hz scheduler tick is offloaded to housekeeping
+	  CPUs.
+
+In any case, housekeeping work has to be handled, which is why there
+must be at least one housekeeping CPU in the system, preferably more
+if the machine runs a lot of CPUs. For example one per node on NUMA
+systems.
+
+Also CPU isolation often means a tradeoff between noise-free isolated
+CPUs and added overhead on housekeeping CPUs, sometimes even on
+isolated CPUs entering the kernel.
+
+Isolation features
+==================
+
+Different levels of isolation can be configured in the kernel, each of
+which has its own drawbacks and tradeoffs.
+
+Scheduler domain isolation
+--------------------------
+
+This feature isolates a CPU from the scheduler topology. As a result,
+the target isn't part of the load balancing. Tasks won't migrate
+either from or to it unless affined explicitly.
+
+As a side effect the CPU is also isolated from unbound workqueues and
+unbound kthreads.
+
+Requirements
+~~~~~~~~~~~~
+
+- CONFIG_CPUSETS=y for the cpusets-based interface
+
+Tradeoffs
+~~~~~~~~~
+
+By nature, the system load is overall less distributed since some CPUs
+are extracted from the global load balancing.
+
+Interfaces
+~~~~~~~~~~
+
+- Documentation/admin-guide/cgroup-v2.rst cpuset isolated partitions are recommended
+  because they are tunable at runtime.
+
+- The 'isolcpus=' kernel boot parameter with the 'domain' flag is a
+  less flexible alternative that doesn't allow for runtime
+  reconfiguration.
+
+IRQs isolation
+--------------
+
+Isolate the IRQs whenever possible, so that they don't fire on the
+target CPUs.
+
+Interfaces
+~~~~~~~~~~
+
+- The file /proc/irq/\*/smp_affinity as explained in detail in
+  Documentation/core-api/irq/irq-affinity.rst page.
+
+- The "irqaffinity=" kernel boot parameter for a default setting.
+
+- The "managed_irq" flag in the "isolcpus=" kernel boot parameter
+  tries a best effort affinity override for managed IRQs.
+
+Full Dynticks (aka nohz_full)
+-----------------------------
+
+Full dynticks extends the dynticks idle mode, which stops the tick when
+the CPU is idle, to CPUs running a single task in userspace. That is,
+the timer tick is stopped if the environment allows it.
+
+Global timer callbacks are also isolated from the nohz_full CPUs.
+
+Requirements
+~~~~~~~~~~~~
+
+- CONFIG_NO_HZ_FULL=y
+
+Constraints
+~~~~~~~~~~~
+
+- The isolated CPUs must run a single task only. Multitask requires
+  the tick to maintain preemption. This is usually fine since the
+  workload usually can't stand the latency of random context switches.
+
+- No call to the kernel from isolated CPUs, at the risk of triggering
+  random noise.
+
+- No use of POSIX CPU timers on isolated CPUs.
+
+- Architecture must have a stable and reliable clocksource (no
+  unreliable TSC that requires the watchdog).
+
+
+Tradeoffs
+~~~~~~~~~
+
+In terms of cost, this is the most invasive isolation feature. It is
+assumed to be used when the workload spends most of its time in
+userspace and doesn't rely on the kernel except for preparatory
+work because:
+
+- RCU adds more overhead due to the locked, offloaded and threaded
+  callbacks processing (the same that would be obtained with "rcu_nocbs"
+  boot parameter).
+
+- Kernel entry/exit through syscalls, exceptions and IRQs are more
+  costly due to fully ordered RmW operations that maintain userspace
+  as RCU extended quiescent state. Also the CPU time is accounted on
+  kernel boundaries instead of periodically from the tick.
+
+- Housekeeping CPUs must run a 1Hz residual remote scheduler tick
+  on behalf of the isolated CPUs.
+
+Checklist
+=========
+
+You have set up each of the above isolation features but you still
+observe jitters that trash your workload? Make sure to check a few
+elements before proceeding.
+
+Some of these checklist items are similar to those of real-time
+workloads:
+
+- Use mlock() to prevent your pages from being swapped away. Page
+  faults are usually not compatible with jitter sensitive workloads.
+
+- Avoid SMT to prevent your hardware thread from being "preempted"
+  by another one.
+
+- CPU frequency changes may induce subtle sorts of jitter in a
+  workload. Cpufreq should be used and tuned with caution.
+
+- Deep C-states may result in latency issues upon wake-up. If this
+  happens to be a problem, C-states can be limited via kernel boot
+  parameters such as processor.max_cstate or intel_idle.max_cstate.
+  More finegrained tunings are described in
+  Documentation/admin-guide/pm/cpuidle.rst page
+
+- Your system may be subject to firmware-originating interrupts - x86 has
+  System Management Interrupts (SMIs) for example. Check your system BIOS
+  to disable such interference, and with some luck your vendor will have
+  a BIOS tuning guidance for low-latency operations.
+
+
+Full isolation example
+======================
+
+In this example, the system has 8 CPUs and the 8th is to be fully
+isolated. Since CPUs start from 0, the 8th CPU is CPU 7.
+
+Kernel parameters
+-----------------
+
+Set the following kernel boot parameters to disable SMT and setup tick
+and IRQ isolation:
+
+- Full dynticks: nohz_full=7
+
+- IRQs isolation: irqaffinity=0-6
+
+- Managed IRQs isolation: isolcpus=managed_irq,7
+
+- Prevent SMT: nosmt
+
+The full command line is then:
+
+  nohz_full=7 irqaffinity=0-6 isolcpus=managed_irq,7 nosmt
+
+CPUSET configuration (cgroup v2)
+--------------------------------
+
+Assuming cgroup v2 is mounted to /sys/fs/cgroup, the following script
+isolates CPU 7 from scheduler domains.
+
+::
+
+  cd /sys/fs/cgroup
+  # Activate the cpuset subsystem
+  echo +cpuset > cgroup.subtree_control
+  # Create partition to be isolated
+  mkdir test
+  cd test
+  echo +cpuset > cgroup.subtree_control
+  # Isolate CPU 7
+  echo 7 > cpuset.cpus
+  echo "isolated" > cpuset.cpus.partition
+
+The userspace workload
+----------------------
+
+Fake a pure userspace workload, the program below runs a dummy
+userspace loop on the isolated CPU 7.
+
+::
+
+  #include <stdio.h>
+  #include <fcntl.h>
+  #include <unistd.h>
+  #include <errno.h>
+  int main(void)
+  {
+      // Move the current task to the isolated cpuset (bind to CPU 7)
+      int fd = open("/sys/fs/cgroup/test/cgroup.procs", O_WRONLY);
+      if (fd < 0) {
+          perror("Can't open cpuset file...\n");
+          return 0;
+      }
+
+      write(fd, "0\n", 2);
+      close(fd);
+
+      // Run an endless dummy loop until the launcher kills us
+      while (1)
+      ;
+
+      return 0;
+  }
+
+Build it and save for later step:
+
+::
+
+  # gcc user_loop.c -o user_loop
+
+The launcher
+------------
+
+The below launcher runs the above program for 10 seconds and traces
+the noise resulting from preempting tasks and IRQs.
+
+::
+
+  TRACING=/sys/kernel/tracing/
+  # Make sure tracing is off for now
+  echo 0 > $TRACING/tracing_on
+  # Flush previous traces
+  echo > $TRACING/trace
+  # Record disturbance from other tasks
+  echo 1 > $TRACING/events/sched/sched_switch/enable
+  # Record disturbance from interrupts
+  echo 1 > $TRACING/events/irq_vectors/enable
+  # Now we can start tracing
+  echo 1 > $TRACING/tracing_on
+  # Run the dummy user_loop for 10 seconds on CPU 7
+  ./user_loop &
+  USER_LOOP_PID=$!
+  sleep 10
+  kill $USER_LOOP_PID
+  # Disable tracing and save traces from CPU 7 in a file
+  echo 0 > $TRACING/tracing_on
+  cat $TRACING/per_cpu/cpu7/trace > trace.7
+
+If no specific problem arose, the output of trace.7 should look like
+the following:
+
+::
+
+  <idle>-0 [007] d..2. 1980.976624: sched_switch: prev_comm=swapper/7 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=user_loop next_pid=1553 next_prio=120
+  user_loop-1553 [007] d.h.. 1990.946593: reschedule_entry: vector=253
+  user_loop-1553 [007] d.h.. 1990.946593: reschedule_exit: vector=253
+
+That is, no specific noise triggered between the first trace and the
+second during 10 seconds when user_loop was running.
+
+Debugging
+=========
+
+Of course things are never so easy, especially on this matter.
+Chances are that actual noise will be observed in the aforementioned
+trace.7 file.
+
+The best way to investigate further is to enable finer grained
+tracepoints such as those of subsystems producing asynchronous
+events: workqueue, timer, irq_vector, etc... It also can be
+interesting to enable the tick_stop event to diagnose why the tick is
+retained when that happens.
+
+Some tools may also be useful for higher level analysis:
+
+- Documentation/tools/rtla/rtla.rst provides a suite of tools to analyze
+  latency and noise in the system. For example Documentation/tools/rtla/rtla-osnoise.rst
+  runs a kernel tracer that analyzes and output a summary of the noises.
+
+- dynticks-testing does something similar to rtla-osnoise but in userspace. It is available
+  at git://git.kernel.org/pub/scm/linux/kernel/git/frederic/dynticks-testing.git
diff --git a/Documentation/admin-guide/cpu-load.rst b/Documentation/admin-guide/cpu-load.rst
new file mode 100644
index 000000000..21a984337
--- /dev/null
+++ b/Documentation/admin-guide/cpu-load.rst
@@ -0,0 +1,117 @@
+========
+CPU load
+========
+
+Linux exports various bits of information via ``/proc/stat`` and
+``/proc/uptime`` that userland tools, such as top(1), use to calculate
+the average time system spent in a particular state, for example::
+
+    $ iostat
+    Linux 2.6.18.3-exp (linmac)     02/20/2007
+
+    avg-cpu:  %user   %nice %system %iowait  %steal   %idle
+              10.01    0.00    2.92    5.44    0.00   81.63
+
+    ...
+
+Here the system thinks that over the default sampling period the
+system spent 10.01% of the time doing work in user space, 2.92% in the
+kernel, and was overall 81.63% of the time idle.
+
+In most cases the ``/proc/stat``	 information reflects the reality quite
+closely, however due to the nature of how/when the kernel collects
+this data sometimes it can not be trusted at all.
+
+So how is this information collected?  Whenever timer interrupt is
+signalled the kernel looks what kind of task was running at this
+moment and increments the counter that corresponds to this tasks
+kind/state.  The problem with this is that the system could have
+switched between various states multiple times between two timer
+interrupts yet the counter is incremented only for the last state.
+
+
+Example
+-------
+
+If we imagine the system with one task that periodically burns cycles
+in the following manner::
+
+     time line between two timer interrupts
+    |--------------------------------------|
+     ^                                    ^
+     |_ something begins working          |
+                                          |_ something goes to sleep
+                                         (only to be awaken quite soon)
+
+In the above situation the system will be 0% loaded according to the
+``/proc/stat`` (since the timer interrupt will always happen when the
+system is executing the idle handler), but in reality the load is
+closer to 99%.
+
+One can imagine many more situations where this behavior of the kernel
+will lead to quite erratic information inside ``/proc/stat``::
+
+
+	/* gcc -o hog smallhog.c */
+	#include <time.h>
+	#include <limits.h>
+	#include <signal.h>
+	#include <sys/time.h>
+	#define HIST 10
+
+	static volatile sig_atomic_t stop;
+
+	static void sighandler(int signr)
+	{
+		(void) signr;
+		stop = 1;
+	}
+
+	static unsigned long hog (unsigned long niters)
+	{
+		stop = 0;
+		while (!stop && --niters);
+		return niters;
+	}
+
+	int main (void)
+	{
+		int i;
+		struct itimerval it = {
+			.it_interval = { .tv_sec = 0, .tv_usec = 1 },
+			.it_value    = { .tv_sec = 0, .tv_usec = 1 } };
+		sigset_t set;
+		unsigned long v[HIST];
+		double tmp = 0.0;
+		unsigned long n;
+		signal(SIGALRM, &sighandler);
+		setitimer(ITIMER_REAL, &it, NULL);
+
+		hog (ULONG_MAX);
+		for (i = 0; i < HIST; ++i) v[i] = ULONG_MAX - hog(ULONG_MAX);
+		for (i = 0; i < HIST; ++i) tmp += v[i];
+		tmp /= HIST;
+		n = tmp - (tmp / 3.0);
+
+		sigemptyset(&set);
+		sigaddset(&set, SIGALRM);
+
+		for (;;) {
+			hog(n);
+			sigwait(&set, &i);
+		}
+		return 0;
+	}
+
+
+References
+----------
+
+- https://lore.kernel.org/r/loom.20070212T063225-663@post.gmane.org
+- Documentation/filesystems/proc.rst (1.8)
+
+
+Thanks
+------
+
+Con Kolivas, Pavel Machek
diff --git a/Documentation/admin-guide/cputopology.rst b/Documentation/admin-guide/cputopology.rst
new file mode 100644
index 000000000..d29cacc9b
--- /dev/null
+++ b/Documentation/admin-guide/cputopology.rst
@@ -0,0 +1,101 @@
+===========================================
+How CPU topology info is exported via sysfs
+===========================================
+
+CPU topology info is exported via sysfs. Items (attributes) are similar
+to /proc/cpuinfo output of some architectures. They reside in
+/sys/devices/system/cpu/cpuX/topology/. Please refer to the ABI file:
+Documentation/ABI/stable/sysfs-devices-system-cpu.
+
+Architecture-neutral, drivers/base/topology.c, exports these attributes.
+However the die, cluster, book, and drawer hierarchy related sysfs files will
+only be created if an architecture provides the related macros as described
+below.
+
+For an architecture to support this feature, it must define some of
+these macros in include/asm-XXX/topology.h::
+
+	#define topology_physical_package_id(cpu)
+	#define topology_die_id(cpu)
+	#define topology_cluster_id(cpu)
+	#define topology_core_id(cpu)
+	#define topology_book_id(cpu)
+	#define topology_drawer_id(cpu)
+	#define topology_sibling_cpumask(cpu)
+	#define topology_core_cpumask(cpu)
+	#define topology_cluster_cpumask(cpu)
+	#define topology_die_cpumask(cpu)
+	#define topology_book_cpumask(cpu)
+	#define topology_drawer_cpumask(cpu)
+
+The type of ``**_id macros`` is int.
+The type of ``**_cpumask macros`` is ``(const) struct cpumask *``. The latter
+correspond with appropriate ``**_siblings`` sysfs attributes (except for
+topology_sibling_cpumask() which corresponds with thread_siblings).
+
+To be consistent on all architectures, include/linux/topology.h
+provides default definitions for any of the above macros that are
+not defined by include/asm-XXX/topology.h:
+
+1) topology_physical_package_id: -1
+2) topology_die_id: -1
+3) topology_cluster_id: -1
+4) topology_core_id: 0
+5) topology_book_id: -1
+6) topology_drawer_id: -1
+7) topology_sibling_cpumask: just the given CPU
+8) topology_core_cpumask: just the given CPU
+9) topology_cluster_cpumask: just the given CPU
+10) topology_die_cpumask: just the given CPU
+11) topology_book_cpumask:  just the given CPU
+12) topology_drawer_cpumask: just the given CPU
+
+Additionally, CPU topology information is provided under
+/sys/devices/system/cpu and includes these files.  The internal
+source for the output is in brackets ("[]").
+
+    =========== ==========================================================
+    kernel_max: the maximum CPU index allowed by the kernel configuration.
+		[NR_CPUS-1]
+
+    offline:	CPUs that are not online because they have been
+		HOTPLUGGED off or exceed the limit of CPUs allowed by the
+		kernel configuration (kernel_max above).
+		[~cpu_online_mask + cpus >= NR_CPUS]
+
+    online:	CPUs that are online and being scheduled [cpu_online_mask]
+
+    possible:	CPUs that have been allocated resources and can be
+		brought online if they are present. [cpu_possible_mask]
+
+    present:	CPUs that have been identified as being present in the
+		system. [cpu_present_mask]
+    =========== ==========================================================
+
+The format for the above output is compatible with cpulist_parse()
+[see <linux/cpumask.h>].  Some examples follow.
+
+In this example, there are 64 CPUs in the system but cpus 32-63 exceed
+the kernel max which is limited to 0..31 by the NR_CPUS config option
+being 32.  Note also that CPUs 2 and 4-31 are not online but could be
+brought online as they are both present and possible::
+
+     kernel_max: 31
+        offline: 2,4-31,32-63
+         online: 0-1,3
+       possible: 0-31
+        present: 0-31
+
+In this example, the NR_CPUS config option is 128, but the kernel was
+started with possible_cpus=144.  There are 4 CPUs in the system and cpu2
+was manually taken offline (and is the only CPU that can be brought
+online.)::
+
+     kernel_max: 127
+        offline: 2,4-127,128-143
+         online: 0-1,3
+       possible: 0-127
+        present: 0-3
+
+See Documentation/core-api/cpu_hotplug.rst for the possible_cpus=NUM
+kernel start parameter as well as more information on the various cpumasks.
diff --git a/Documentation/admin-guide/dell_rbu.rst b/Documentation/admin-guide/dell_rbu.rst
new file mode 100644
index 000000000..2196caf1b
--- /dev/null
+++ b/Documentation/admin-guide/dell_rbu.rst
@@ -0,0 +1,128 @@
+=========================================
+Dell Remote BIOS Update driver (dell_rbu)
+=========================================
+
+Purpose
+=======
+
+Document demonstrating the use of the Dell Remote BIOS Update driver
+for updating BIOS images on Dell servers and desktops.
+
+Scope
+=====
+
+This document discusses the functionality of the rbu driver only.
+It does not cover the support needed from applications to enable the BIOS to
+update itself with the image downloaded in to the memory.
+
+Overview
+========
+
+This driver works with Dell OpenManage or Dell Update Packages for updating
+the BIOS on Dell servers (starting from servers sold since 1999), desktops
+and notebooks (starting from those sold in 2005).
+
+Please go to  http://support.dell.com register and you can find info on
+OpenManage and Dell Update packages (DUP).
+
+Libsmbios can also be used to update BIOS on Dell systems go to
+https://linux.dell.com/libsmbios/ for details.
+
+Dell_RBU driver supports BIOS update using the monolithic image and packetized
+image methods. In case of monolithic the driver allocates a contiguous chunk
+of physical pages having the BIOS image. In case of packetized the app
+using the driver breaks the image in to packets of fixed sizes and the driver
+would place each packet in contiguous physical memory. The driver also
+maintains a link list of packets for reading them back.
+
+If the dell_rbu driver is unloaded all the allocated memory is freed.
+
+The rbu driver needs to have an application (as mentioned above) which will
+inform the BIOS to enable the update in the next system reboot.
+
+The user should not unload the rbu driver after downloading the BIOS image
+or updating.
+
+The driver load creates the following directories under the /sys file system::
+
+	/sys/class/firmware/dell_rbu/loading
+	/sys/class/firmware/dell_rbu/data
+	/sys/devices/platform/dell_rbu/image_type
+	/sys/devices/platform/dell_rbu/data
+	/sys/devices/platform/dell_rbu/packet_size
+
+The driver supports two types of update mechanism; monolithic and packetized.
+These update mechanism depends upon the BIOS currently running on the system.
+Most of the Dell systems support a monolithic update where the BIOS image is
+copied to a single contiguous block of physical memory.
+
+In case of packet mechanism the single memory can be broken in smaller chunks
+of contiguous memory and the BIOS image is scattered in these packets.
+
+By default the driver uses monolithic memory for the update type. This can be
+changed to packets during the driver load time by specifying the load
+parameter image_type=packet.  This can also be changed later as below::
+
+	echo packet > /sys/devices/platform/dell_rbu/image_type
+
+In packet update mode the packet size has to be given before any packets can
+be downloaded. It is done as below::
+
+	echo XXXX > /sys/devices/platform/dell_rbu/packet_size
+
+In the packet update mechanism, the user needs to create a new file having
+packets of data arranged back to back. It can be done as follows:
+The user creates packets header, gets the chunk of the BIOS image and
+places it next to the packetheader; now, the packetheader + BIOS image chunk
+added together should match the specified packet_size. This makes one
+packet, the user needs to create more such packets out of the entire BIOS
+image file and then arrange all these packets back to back in to one single
+file.
+
+This file is then copied to /sys/class/firmware/dell_rbu/data.
+Once this file gets to the driver, the driver extracts packet_size data from
+the file and spreads it across the physical memory in contiguous packet_sized
+space.
+
+This method makes sure that all the packets get to the driver in a single operation.
+
+In monolithic update the user simply get the BIOS image (.hdr file) and copies
+to the data file as is without any change to the BIOS image itself.
+
+Do the steps below to download the BIOS image.
+
+1) echo 1 > /sys/class/firmware/dell_rbu/loading
+2) cp bios_image.hdr /sys/class/firmware/dell_rbu/data
+3) echo 0 > /sys/class/firmware/dell_rbu/loading
+
+The /sys/class/firmware/dell_rbu/ entries will remain till the following is
+done.
+
+::
+
+	echo -1 > /sys/class/firmware/dell_rbu/loading
+
+Until this step is completed the driver cannot be unloaded.
+
+Also echoing either mono, packet or init in to image_type will free up the
+memory allocated by the driver.
+
+If a user by accident executes steps 1 and 3 above without executing step 2;
+it will make the /sys/class/firmware/dell_rbu/ entries disappear.
+
+The entries can be recreated by doing the following::
+
+	echo init > /sys/devices/platform/dell_rbu/image_type
+
+.. note:: echoing init in image_type does not change its original value.
+
+Also the driver provides /sys/devices/platform/dell_rbu/data readonly file to
+read back the image downloaded.
+
+.. note::
+
+   After updating the BIOS image a user mode application needs to execute
+   code which sends the BIOS update request to the BIOS. So on the next reboot
+   the BIOS knows about the new image downloaded and it updates itself.
+   Also don't unload the rbu driver if the image has to be updated.
+
diff --git a/Documentation/admin-guide/device-mapper/cache-policies.rst b/Documentation/admin-guide/device-mapper/cache-policies.rst
new file mode 100644
index 000000000..13da4d831
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/cache-policies.rst
@@ -0,0 +1,131 @@
+=============================
+Guidance for writing policies
+=============================
+
+Try to keep transactionality out of it.  The core is careful to
+avoid asking about anything that is migrating.  This is a pain, but
+makes it easier to write the policies.
+
+Mappings are loaded into the policy at construction time.
+
+Every bio that is mapped by the target is referred to the policy.
+The policy can return a simple HIT or MISS or issue a migration.
+
+Currently there's no way for the policy to issue background work,
+e.g. to start writing back dirty blocks that are going to be evicted
+soon.
+
+Because we map bios, rather than requests it's easy for the policy
+to get fooled by many small bios.  For this reason the core target
+issues periodic ticks to the policy.  It's suggested that the policy
+doesn't update states (eg, hit counts) for a block more than once
+for each tick.  The core ticks by watching bios complete, and so
+trying to see when the io scheduler has let the ios run.
+
+
+Overview of supplied cache replacement policies
+===============================================
+
+multiqueue (mq)
+---------------
+
+This policy is now an alias for smq (see below).
+
+The following tunables are accepted, but have no effect::
+
+	'sequential_threshold <#nr_sequential_ios>'
+	'random_threshold <#nr_random_ios>'
+	'read_promote_adjustment <value>'
+	'write_promote_adjustment <value>'
+	'discard_promote_adjustment <value>'
+
+Stochastic multiqueue (smq)
+---------------------------
+
+This policy is the default.
+
+The stochastic multi-queue (smq) policy addresses some of the problems
+with the multiqueue (mq) policy.
+
+The smq policy (vs mq) offers the promise of less memory utilization,
+improved performance and increased adaptability in the face of changing
+workloads.  smq also does not have any cumbersome tuning knobs.
+
+Users may switch from "mq" to "smq" simply by appropriately reloading a
+DM table that is using the cache target.  Doing so will cause all of the
+mq policy's hints to be dropped.  Also, performance of the cache may
+degrade slightly until smq recalculates the origin device's hotspots
+that should be cached.
+
+Memory usage
+^^^^^^^^^^^^
+
+The mq policy used a lot of memory; 88 bytes per cache block on a 64
+bit machine.
+
+smq uses 28bit indexes to implement its data structures rather than
+pointers.  It avoids storing an explicit hit count for each block.  It
+has a 'hotspot' queue, rather than a pre-cache, which uses a quarter of
+the entries (each hotspot block covers a larger area than a single
+cache block).
+
+All this means smq uses ~25bytes per cache block.  Still a lot of
+memory, but a substantial improvement nonetheless.
+
+Level balancing
+^^^^^^^^^^^^^^^
+
+mq placed entries in different levels of the multiqueue structures
+based on their hit count (~ln(hit count)).  This meant the bottom
+levels generally had the most entries, and the top ones had very
+few.  Having unbalanced levels like this reduced the efficacy of the
+multiqueue.
+
+smq does not maintain a hit count, instead it swaps hit entries with
+the least recently used entry from the level above.  The overall
+ordering being a side effect of this stochastic process.  With this
+scheme we can decide how many entries occupy each multiqueue level,
+resulting in better promotion/demotion decisions.
+
+Adaptability:
+The mq policy maintained a hit count for each cache block.  For a
+different block to get promoted to the cache its hit count has to
+exceed the lowest currently in the cache.  This meant it could take a
+long time for the cache to adapt between varying IO patterns.
+
+smq doesn't maintain hit counts, so a lot of this problem just goes
+away.  In addition it tracks performance of the hotspot queue, which
+is used to decide which blocks to promote.  If the hotspot queue is
+performing badly then it starts moving entries more quickly between
+levels.  This lets it adapt to new IO patterns very quickly.
+
+Performance
+^^^^^^^^^^^
+
+Testing smq shows substantially better performance than mq.
+
+cleaner
+-------
+
+The cleaner writes back all dirty blocks in a cache to decommission it.
+
+Examples
+========
+
+The syntax for a table is::
+
+	cache <metadata dev> <cache dev> <origin dev> <block size>
+	<#feature_args> [<feature arg>]*
+	<policy> <#policy_args> [<policy arg>]*
+
+The syntax to send a message using the dmsetup command is::
+
+	dmsetup message <mapped device> 0 sequential_threshold 1024
+	dmsetup message <mapped device> 0 random_threshold 8
+
+Using dmsetup::
+
+	dmsetup create blah --table "0 268435456 cache /dev/sdb /dev/sdc \
+	    /dev/sdd 512 0 mq 4 sequential_threshold 1024 random_threshold 8"
+	creates a 128GB large mapped device named 'blah' with the
+	sequential threshold set to 1024 and the random_threshold set to 8.
diff --git a/Documentation/admin-guide/device-mapper/cache.rst b/Documentation/admin-guide/device-mapper/cache.rst
new file mode 100644
index 000000000..f15e5254d
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/cache.rst
@@ -0,0 +1,337 @@
+=====
+Cache
+=====
+
+Introduction
+============
+
+dm-cache is a device mapper target written by Joe Thornber, Heinz
+Mauelshagen, and Mike Snitzer.
+
+It aims to improve performance of a block device (eg, a spindle) by
+dynamically migrating some of its data to a faster, smaller device
+(eg, an SSD).
+
+This device-mapper solution allows us to insert this caching at
+different levels of the dm stack, for instance above the data device for
+a thin-provisioning pool.  Caching solutions that are integrated more
+closely with the virtual memory system should give better performance.
+
+The target reuses the metadata library used in the thin-provisioning
+library.
+
+The decision as to what data to migrate and when is left to a plug-in
+policy module.  Several of these have been written as we experiment,
+and we hope other people will contribute others for specific io
+scenarios (eg. a vm image server).
+
+Glossary
+========
+
+  Migration
+	       Movement of the primary copy of a logical block from one
+	       device to the other.
+  Promotion
+	       Migration from slow device to fast device.
+  Demotion
+	       Migration from fast device to slow device.
+
+The origin device always contains a copy of the logical block, which
+may be out of date or kept in sync with the copy on the cache device
+(depending on policy).
+
+Design
+======
+
+Sub-devices
+-----------
+
+The target is constructed by passing three devices to it (along with
+other parameters detailed later):
+
+1. An origin device - the big, slow one.
+
+2. A cache device - the small, fast one.
+
+3. A small metadata device - records which blocks are in the cache,
+   which are dirty, and extra hints for use by the policy object.
+   This information could be put on the cache device, but having it
+   separate allows the volume manager to configure it differently,
+   e.g. as a mirror for extra robustness.  This metadata device may only
+   be used by a single cache device.
+
+Fixed block size
+----------------
+
+The origin is divided up into blocks of a fixed size.  This block size
+is configurable when you first create the cache.  Typically we've been
+using block sizes of 256KB - 1024KB.  The block size must be between 64
+sectors (32KB) and 2097152 sectors (1GB) and a multiple of 64 sectors (32KB).
+
+Having a fixed block size simplifies the target a lot.  But it is
+something of a compromise.  For instance, a small part of a block may be
+getting hit a lot, yet the whole block will be promoted to the cache.
+So large block sizes are bad because they waste cache space.  And small
+block sizes are bad because they increase the amount of metadata (both
+in core and on disk).
+
+Cache operating modes
+---------------------
+
+The cache has three operating modes: writeback, writethrough and
+passthrough.
+
+If writeback, the default, is selected then a write to a block that is
+cached will go only to the cache and the block will be marked dirty in
+the metadata.
+
+If writethrough is selected then a write to a cached block will not
+complete until it has hit both the origin and cache devices.  Clean
+blocks should remain clean.
+
+If passthrough is selected, useful when the cache contents are not known
+to be coherent with the origin device, then all reads are served from
+the origin device (all reads miss the cache) and all writes are
+forwarded to the origin device; additionally, write hits cause cache
+block invalidates.  To enable passthrough mode the cache must be clean.
+Passthrough mode allows a cache device to be activated without having to
+worry about coherency.  Coherency that exists is maintained, although
+the cache will gradually cool as writes take place.  If the coherency of
+the cache can later be verified, or established through use of the
+"invalidate_cblocks" message, the cache device can be transitioned to
+writethrough or writeback mode while still warm.  Otherwise, the cache
+contents can be discarded prior to transitioning to the desired
+operating mode.
+
+A simple cleaner policy is provided, which will clean (write back) all
+dirty blocks in a cache.  Useful for decommissioning a cache or when
+shrinking a cache.  Shrinking the cache's fast device requires all cache
+blocks, in the area of the cache being removed, to be clean.  If the
+area being removed from the cache still contains dirty blocks the resize
+will fail.  Care must be taken to never reduce the volume used for the
+cache's fast device until the cache is clean.  This is of particular
+importance if writeback mode is used.  Writethrough and passthrough
+modes already maintain a clean cache.  Future support to partially clean
+the cache, above a specified threshold, will allow for keeping the cache
+warm and in writeback mode during resize.
+
+Migration throttling
+--------------------
+
+Migrating data between the origin and cache device uses bandwidth.
+The user can set a throttle to prevent more than a certain amount of
+migration occurring at any one time.  Currently we're not taking any
+account of normal io traffic going to the devices.  More work needs
+doing here to avoid migrating during those peak io moments.
+
+For the time being, a message "migration_threshold <#sectors>"
+can be used to set the maximum number of sectors being migrated,
+the default being 2048 sectors (1MB).
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the cache behaves like a physical disk that has a volatile write
+cache.  If power is lost you may lose some recent writes.  The metadata
+should always be consistent in spite of any crash.
+
+The 'dirty' state for a cache block changes far too frequently for us
+to keep updating it on the fly.  So we treat it as a hint.  In normal
+operation it will be written when the dm device is suspended.  If the
+system crashes all cache blocks will be assumed dirty when restarted.
+
+Per-block policy hints
+----------------------
+
+Policy plug-ins can store a chunk of data per cache block.  It's up to
+the policy how big this chunk is, but it should be kept small.  Like the
+dirty flags this data is lost if there's a crash so a safe fallback
+value should always be possible.
+
+Policy hints affect performance, not correctness.
+
+Policy messaging
+----------------
+
+Policies will have different tunables, specific to each one, so we
+need a generic way of getting and setting these.  Device-mapper
+messages are used.  Refer to cache-policies.txt.
+
+Discard bitset resolution
+-------------------------
+
+We can avoid copying data during migration if we know the block has
+been discarded.  A prime example of this is when mkfs discards the
+whole block device.  We store a bitset tracking the discard state of
+blocks.  However, we allow this bitset to have a different block size
+from the cache blocks.  This is because we need to track the discard
+state for all of the origin device (compare with the dirty bitset
+which is just for the smaller cache device).
+
+Target interface
+================
+
+Constructor
+-----------
+
+  ::
+
+   cache <metadata dev> <cache dev> <origin dev> <block size>
+         <#feature args> [<feature arg>]*
+         <policy> <#policy args> [policy args]*
+
+ ================ =======================================================
+ metadata dev     fast device holding the persistent metadata
+ cache dev	  fast device holding cached data blocks
+ origin dev	  slow device holding original data blocks
+ block size       cache unit size in sectors
+
+ #feature args    number of feature arguments passed
+ feature args     writethrough or passthrough (The default is writeback.)
+
+ policy           the replacement policy to use
+ #policy args     an even number of arguments corresponding to
+                  key/value pairs passed to the policy
+ policy args      key/value pairs passed to the policy
+		  E.g. 'sequential_threshold 1024'
+		  See cache-policies.txt for details.
+ ================ =======================================================
+
+Optional feature arguments are:
+
+
+   ==================== ========================================================
+   writethrough		write through caching that prohibits cache block
+			content from being different from origin block content.
+			Without this argument, the default behaviour is to write
+			back cache block contents later for performance reasons,
+			so they may differ from the corresponding origin blocks.
+
+   passthrough		a degraded mode useful for various cache coherency
+			situations (e.g., rolling back snapshots of
+			underlying storage).	 Reads and writes always go to
+			the origin.	If a write goes to a cached origin
+			block, then the cache block is invalidated.
+			To enable passthrough mode the cache must be clean.
+
+   metadata2		use version 2 of the metadata.  This stores the dirty
+			bits in a separate btree, which improves speed of
+			shutting down the cache.
+
+   no_discard_passdown	disable passing down discards from the cache
+			to the origin's data device.
+   ==================== ========================================================
+
+A policy called 'default' is always registered.  This is an alias for
+the policy we currently think is giving best all round performance.
+
+As the default policy could vary between kernels, if you are relying on
+the characteristics of a specific policy, always request it by name.
+
+Status
+------
+
+::
+
+  <metadata block size> <#used metadata blocks>/<#total metadata blocks>
+  <cache block size> <#used cache blocks>/<#total cache blocks>
+  <#read hits> <#read misses> <#write hits> <#write misses>
+  <#demotions> <#promotions> <#dirty> <#features> <features>*
+  <#core args> <core args>* <policy name> <#policy args> <policy args>*
+  <cache metadata mode>
+
+
+========================= =====================================================
+metadata block size	  Fixed block size for each metadata block in
+			  sectors
+#used metadata blocks	  Number of metadata blocks used
+#total metadata blocks	  Total number of metadata blocks
+cache block size	  Configurable block size for the cache device
+			  in sectors
+#used cache blocks	  Number of blocks resident in the cache
+#total cache blocks	  Total number of cache blocks
+#read hits		  Number of times a READ bio has been mapped
+			  to the cache
+#read misses		  Number of times a READ bio has been mapped
+			  to the origin
+#write hits		  Number of times a WRITE bio has been mapped
+			  to the cache
+#write misses		  Number of times a WRITE bio has been
+			  mapped to the origin
+#demotions		  Number of times a block has been removed
+			  from the cache
+#promotions		  Number of times a block has been moved to
+			  the cache
+#dirty			  Number of blocks in the cache that differ
+			  from the origin
+#feature args		  Number of feature args to follow
+feature args		  'writethrough' (optional)
+#core args		  Number of core arguments (must be even)
+core args		  Key/value pairs for tuning the core
+			  e.g. migration_threshold
+policy name		  Name of the policy
+#policy args		  Number of policy arguments to follow (must be even)
+policy args		  Key/value pairs e.g. sequential_threshold
+cache metadata mode       ro if read-only, rw if read-write
+
+			  In serious cases where even a read-only mode is
+			  deemed unsafe no further I/O will be permitted and
+			  the status will just contain the string 'Fail'.
+			  The userspace recovery tools should then be used.
+needs_check		  'needs_check' if set, '-' if not set
+			  A metadata operation has failed, resulting in the
+			  needs_check flag being set in the metadata's
+			  superblock.  The metadata device must be
+			  deactivated and checked/repaired before the
+			  cache can be made fully operational again.
+			  '-' indicates	needs_check is not set.
+========================= =====================================================
+
+Messages
+--------
+
+Policies will have different tunables, specific to each one, so we
+need a generic way of getting and setting these.  Device-mapper
+messages are used.  (A sysfs interface would also be possible.)
+
+The message format is::
+
+   <key> <value>
+
+E.g.::
+
+   dmsetup message my_cache 0 sequential_threshold 1024
+
+
+Invalidation is removing an entry from the cache without writing it
+back.  Cache blocks can be invalidated via the invalidate_cblocks
+message, which takes an arbitrary number of cblock ranges.  Each cblock
+range's end value is "one past the end", meaning 5-10 expresses a range
+of values from 5 to 9.  Each cblock must be expressed as a decimal
+value, in the future a variant message that takes cblock ranges
+expressed in hexadecimal may be needed to better support efficient
+invalidation of larger caches.  The cache must be in passthrough mode
+when invalidate_cblocks is used::
+
+   invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*
+
+E.g.::
+
+   dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789
+
+Examples
+========
+
+The test suite can be found here:
+
+https://github.com/jthornber/device-mapper-test-suite
+
+::
+
+  dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
+	  /dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
+  dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
+	  /dev/mapper/ssd /dev/mapper/origin 1024 1 writeback \
+	  mq 4 sequential_threshold 1024 random_threshold 8'
diff --git a/Documentation/admin-guide/device-mapper/delay.rst b/Documentation/admin-guide/device-mapper/delay.rst
new file mode 100644
index 000000000..a1e673c0e
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/delay.rst
@@ -0,0 +1,54 @@
+========
+dm-delay
+========
+
+Device-Mapper's "delay" target delays reads and/or writes
+and/or flushes and optionally maps them to different devices.
+
+Arguments::
+
+    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
+			       [<flush_device> <flush_offset> <flush_delay>]]
+
+Table line has to either have 3, 6 or 9 arguments:
+
+3: apply offset and delay to read, write and flush operations on device
+
+6: apply offset and delay to device, also apply write_offset and write_delay
+   to write and flush operations on optionally different write_device with
+   optionally different sector offset
+
+9: same as 6 arguments plus define flush_offset and flush_delay explicitly
+   on/with optionally different flush_device/flush_offset.
+
+Offsets are specified in sectors.
+
+Delays are specified in milliseconds.
+
+
+Example scripts
+===============
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device named "delayed" delaying read, write and flush operations for 500ms.
+	#
+	dmsetup create delayed --table  "0 `blockdev --getsz $1` delay $1 0 500"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying write and flush operations for 400ms and
+	# splitting reads to device $1 but writes and flushes to different device $2
+	# to different offsets of 2048 and 4096 sectors respectively.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying reads for 50ms, writes for 100ms and flushes for 333ms
+	# onto the same backing device at offset 0 sectors.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"
diff --git a/Documentation/admin-guide/device-mapper/dm-clone.rst b/Documentation/admin-guide/device-mapper/dm-clone.rst
new file mode 100644
index 000000000..b43a34c14
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-clone.rst
@@ -0,0 +1,333 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+========
+dm-clone
+========
+
+Introduction
+============
+
+dm-clone is a device mapper target which produces a one-to-one copy of an
+existing, read-only source device into a writable destination device: It
+presents a virtual block device which makes all data appear immediately, and
+redirects reads and writes accordingly.
+
+The main use case of dm-clone is to clone a potentially remote, high-latency,
+read-only, archival-type block device into a writable, fast, primary-type device
+for fast, low-latency I/O. The cloned device is visible/mountable immediately
+and the copy of the source device to the destination device happens in the
+background, in parallel with user I/O.
+
+For example, one could restore an application backup from a read-only copy,
+accessible through a network storage protocol (NBD, Fibre Channel, iSCSI, AoE,
+etc.), into a local SSD or NVMe device, and start using the device immediately,
+without waiting for the restore to complete.
+
+When the cloning completes, the dm-clone table can be removed altogether and be
+replaced, e.g., by a linear table, mapping directly to the destination device.
+
+The dm-clone target reuses the metadata library used by the thin-provisioning
+target.
+
+Glossary
+========
+
+   Hydration
+     The process of filling a region of the destination device with data from
+     the same region of the source device, i.e., copying the region from the
+     source to the destination device.
+
+Once a region gets hydrated we redirect all I/O regarding it to the destination
+device.
+
+Design
+======
+
+Sub-devices
+-----------
+
+The target is constructed by passing three devices to it (along with other
+parameters detailed later):
+
+1. A source device - the read-only device that gets cloned and source of the
+   hydration.
+
+2. A destination device - the destination of the hydration, which will become a
+   clone of the source device.
+
+3. A small metadata device - it records which regions are already valid in the
+   destination device, i.e., which regions have already been hydrated, or have
+   been written to directly, via user I/O.
+
+The size of the destination device must be at least equal to the size of the
+source device.
+
+Regions
+-------
+
+dm-clone divides the source and destination devices in fixed sized regions.
+Regions are the unit of hydration, i.e., the minimum amount of data copied from
+the source to the destination device.
+
+The region size is configurable when you first create the dm-clone device. The
+recommended region size is the same as the file system block size, which usually
+is 4KB. The region size must be between 8 sectors (4KB) and 2097152 sectors
+(1GB) and a power of two.
+
+Reads and writes from/to hydrated regions are serviced from the destination
+device.
+
+A read to a not yet hydrated region is serviced directly from the source device.
+
+A write to a not yet hydrated region will be delayed until the corresponding
+region has been hydrated and the hydration of the region starts immediately.
+
+Note that a write request with size equal to region size will skip copying of
+the corresponding region from the source device and overwrite the region of the
+destination device directly.
+
+Discards
+--------
+
+dm-clone interprets a discard request to a range that hasn't been hydrated yet
+as a hint to skip hydration of the regions covered by the request, i.e., it
+skips copying the region's data from the source to the destination device, and
+only updates its metadata.
+
+If the destination device supports discards, then by default dm-clone will pass
+down discard requests to it.
+
+Background Hydration
+--------------------
+
+dm-clone copies continuously from the source to the destination device, until
+all of the device has been copied.
+
+Copying data from the source to the destination device uses bandwidth. The user
+can set a throttle to prevent more than a certain amount of copying occurring at
+any one time. Moreover, dm-clone takes into account user I/O traffic going to
+the devices and pauses the background hydration when there is I/O in-flight.
+
+A message `hydration_threshold <#regions>` can be used to set the maximum number
+of regions being copied, the default being 1 region.
+
+dm-clone employs dm-kcopyd for copying portions of the source device to the
+destination device. By default, we issue copy requests of size equal to the
+region size. A message `hydration_batch_size <#regions>` can be used to tune the
+size of these copy requests. Increasing the hydration batch size results in
+dm-clone trying to batch together contiguous regions, so we copy the data in
+batches of this many regions.
+
+When the hydration of the destination device finishes, a dm event will be sent
+to user space.
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written. If no
+such requests are made then commits will occur every second. This means the
+dm-clone device behaves like a physical disk that has a volatile write cache. If
+power is lost you may lose some recent writes. The metadata should always be
+consistent in spite of any crash.
+
+Target Interface
+================
+
+Constructor
+-----------
+
+  ::
+
+   clone <metadata dev> <destination dev> <source dev> <region size>
+         [<#feature args> [<feature arg>]* [<#core args> [<core arg>]*]]
+
+ ================ ==============================================================
+ metadata dev     Fast device holding the persistent metadata
+ destination dev  The destination device, where the source will be cloned
+ source dev       Read only device containing the data that gets cloned
+ region size      The size of a region in sectors
+
+ #feature args    Number of feature arguments passed
+ feature args     no_hydration or no_discard_passdown
+
+ #core args       An even number of arguments corresponding to key/value pairs
+                  passed to dm-clone
+ core args        Key/value pairs passed to dm-clone, e.g. `hydration_threshold
+                  256`
+ ================ ==============================================================
+
+Optional feature arguments are:
+
+ ==================== =========================================================
+ no_hydration         Create a dm-clone instance with background hydration
+                      disabled
+ no_discard_passdown  Disable passing down discards to the destination device
+ ==================== =========================================================
+
+Optional core arguments are:
+
+ ================================ ==============================================
+ hydration_threshold <#regions>   Maximum number of regions being copied from
+                                  the source to the destination device at any
+                                  one time, during background hydration.
+ hydration_batch_size <#regions>  During background hydration, try to batch
+                                  together contiguous regions, so we copy data
+                                  from the source to the destination device in
+                                  batches of this many regions.
+ ================================ ==============================================
+
+Status
+------
+
+  ::
+
+   <metadata block size> <#used metadata blocks>/<#total metadata blocks>
+   <region size> <#hydrated regions>/<#total regions> <#hydrating regions>
+   <#feature args> <feature args>* <#core args> <core args>*
+   <clone metadata mode>
+
+ ======================= =======================================================
+ metadata block size     Fixed block size for each metadata block in sectors
+ #used metadata blocks   Number of metadata blocks used
+ #total metadata blocks  Total number of metadata blocks
+ region size             Configurable region size for the device in sectors
+ #hydrated regions       Number of regions that have finished hydrating
+ #total regions          Total number of regions to hydrate
+ #hydrating regions      Number of regions currently hydrating
+ #feature args           Number of feature arguments to follow
+ feature args            Feature arguments, e.g. `no_hydration`
+ #core args              Even number of core arguments to follow
+ core args               Key/value pairs for tuning the core, e.g.
+                         `hydration_threshold 256`
+ clone metadata mode     ro if read-only, rw if read-write
+
+                         In serious cases where even a read-only mode is deemed
+                         unsafe no further I/O will be permitted and the status
+                         will just contain the string 'Fail'. If the metadata
+                         mode changes, a dm event will be sent to user space.
+ ======================= =======================================================
+
+Messages
+--------
+
+  `disable_hydration`
+      Disable the background hydration of the destination device.
+
+  `enable_hydration`
+      Enable the background hydration of the destination device.
+
+  `hydration_threshold <#regions>`
+      Set background hydration threshold.
+
+  `hydration_batch_size <#regions>`
+      Set background hydration batch size.
+
+Examples
+========
+
+Clone a device containing a file system
+---------------------------------------
+
+1. Create the dm-clone device.
+
+   ::
+
+    dmsetup create clone --table "0 1048576000 clone $metadata_dev $dest_dev \
+      $source_dev 8 1 no_hydration"
+
+2. Mount the device and trim the file system. dm-clone interprets the discards
+   sent by the file system and it will not hydrate the unused space.
+
+   ::
+
+    mount /dev/mapper/clone /mnt/cloned-fs
+    fstrim /mnt/cloned-fs
+
+3. Enable background hydration of the destination device.
+
+   ::
+
+    dmsetup message clone 0 enable_hydration
+
+4. When the hydration finishes, we can replace the dm-clone table with a linear
+   table.
+
+   ::
+
+    dmsetup suspend clone
+    dmsetup load clone --table "0 1048576000 linear $dest_dev 0"
+    dmsetup resume clone
+
+   The metadata device is no longer needed and can be safely discarded or reused
+   for other purposes.
+
+Known issues
+============
+
+1. We redirect reads, to not-yet-hydrated regions, to the source device. If
+   reading the source device has high latency and the user repeatedly reads from
+   the same regions, this behaviour could degrade performance. We should use
+   these reads as hints to hydrate the relevant regions sooner. Currently, we
+   rely on the page cache to cache these regions, so we hopefully don't end up
+   reading them multiple times from the source device.
+
+2. Release in-core resources, i.e., the bitmaps tracking which regions are
+   hydrated, after the hydration has finished.
+
+3. During background hydration, if we fail to read the source or write to the
+   destination device, we print an error message, but the hydration process
+   continues indefinitely, until it succeeds. We should stop the background
+   hydration after a number of failures and emit a dm event for user space to
+   notice.
+
+Why not...?
+===========
+
+We explored the following alternatives before implementing dm-clone:
+
+1. Use dm-cache with cache size equal to the source device and implement a new
+   cloning policy:
+
+   * The resulting cache device is not a one-to-one mirror of the source device
+     and thus we cannot remove the cache device once cloning completes.
+
+   * dm-cache writes to the source device, which violates our requirement that
+     the source device must be treated as read-only.
+
+   * Caching is semantically different from cloning.
+
+2. Use dm-snapshot with a COW device equal to the source device:
+
+   * dm-snapshot stores its metadata in the COW device, so the resulting device
+     is not a one-to-one mirror of the source device.
+
+   * No background copying mechanism.
+
+   * dm-snapshot needs to commit its metadata whenever a pending exception
+     completes, to ensure snapshot consistency. In the case of cloning, we don't
+     need to be so strict and can rely on committing metadata every time a FLUSH
+     or FUA bio is written, or periodically, like dm-thin and dm-cache do. This
+     improves the performance significantly.
+
+3. Use dm-mirror: The mirror target has a background copying/mirroring
+   mechanism, but it writes to all mirrors, thus violating our requirement that
+   the source device must be treated as read-only.
+
+4. Use dm-thin's external snapshot functionality. This approach is the most
+   promising among all alternatives, as the thinly-provisioned volume is a
+   one-to-one mirror of the source device and handles reads and writes to
+   un-provisioned/not-yet-cloned areas the same way as dm-clone does.
+
+   Still:
+
+   * There is no background copying mechanism, though one could be implemented.
+
+   * Most importantly, we want to support arbitrary block devices as the
+     destination of the cloning process and not restrict ourselves to
+     thinly-provisioned volumes. Thin-provisioning has an inherent metadata
+     overhead, for maintaining the thin volume mappings, which significantly
+     degrades performance.
+
+   Moreover, cloning a device shouldn't force the use of thin-provisioning. On
+   the other hand, if we wish to use thin provisioning, we can just use a thin
+   LV as dm-clone's destination device.
diff --git a/Documentation/admin-guide/device-mapper/dm-crypt.rst b/Documentation/admin-guide/device-mapper/dm-crypt.rst
new file mode 100644
index 000000000..4467f6d4b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-crypt.rst
@@ -0,0 +1,212 @@
+========
+dm-crypt
+========
+
+Device-Mapper's "crypt" target provides transparent encryption of block devices
+using the kernel crypto API.
+
+For a more detailed description of supported parameters see:
+https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
+
+Parameters::
+
+	      <cipher> <key> <iv_offset> <device path> \
+	      <offset> [<#opt_params> <opt_params>]
+
+<cipher>
+    Encryption cipher, encryption mode and Initial Vector (IV) generator.
+
+    The cipher specifications format is::
+
+       cipher[:keycount]-chainmode-ivmode[:ivopts]
+
+    Examples::
+
+       aes-cbc-essiv:sha256
+       aes-xts-plain64
+       serpent-xts-plain64
+
+    Cipher format also supports direct specification with kernel crypt API
+    format (selected by capi: prefix). The IV specification is the same
+    as for the first format type.
+    This format is mainly used for specification of authenticated modes.
+
+    The crypto API cipher specifications format is::
+
+        capi:cipher_api_spec-ivmode[:ivopts]
+
+    Examples::
+
+        capi:cbc(aes)-essiv:sha256
+        capi:xts(aes)-plain64
+
+    Examples of authenticated modes::
+
+        capi:gcm(aes)-random
+        capi:authenc(hmac(sha256),xts(aes))-random
+        capi:rfc7539(chacha20,poly1305)-random
+
+    The /proc/crypto contains a list of currently loaded crypto modes.
+
+<key>
+    Key used for encryption. It is encoded either as a hexadecimal number
+    or it can be passed as <key_string> prefixed with single colon
+    character (':') for keys residing in kernel keyring service.
+    You can only use key sizes that are valid for the selected cipher
+    in combination with the selected iv mode.
+    Note that for some iv modes the key string can contain additional
+    keys (for example IV seed) so the key contains more parts concatenated
+    into a single string.
+
+<key_string>
+    The kernel keyring key is identified by string in following format:
+    <key_size>:<key_type>:<key_description>.
+
+<key_size>
+    The encryption key size in bytes. The kernel key payload size must match
+    the value passed in <key_size>.
+
+<key_type>
+    Either 'logon', 'user', 'encrypted' or 'trusted' kernel key type.
+
+<key_description>
+    The kernel keyring key description crypt target should look for
+    when loading key of <key_type>.
+
+<keycount>
+    Multi-key compatibility mode. You can define <keycount> keys and
+    then sectors are encrypted according to their offsets (sector 0 uses key0;
+    sector 1 uses key1 etc.).  <keycount> must be a power of two.
+
+<iv_offset>
+    The IV offset is a sector count that is added to the sector number
+    before creating the IV.
+
+<device path>
+    This is the device that is going to be used as backend and contains the
+    encrypted data.  You can specify it as a path like /dev/xxx or a device
+    number <major>:<minor>.
+
+<offset>
+    Starting sector within the device where the encrypted data begins.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        3 allow_discards same_cpu_crypt submit_from_crypt_cpus
+
+allow_discards
+    Block discard requests (a.k.a. TRIM) are passed through the crypt device.
+    The default is to ignore discard requests.
+
+    WARNING: Assess the specific security risks carefully before enabling this
+    option.  For example, allowing discards on encrypted devices may lead to
+    the leak of information about the ciphertext device (filesystem type,
+    used space etc.) if the discarded blocks can be located easily on the
+    device later.
+
+same_cpu_crypt
+    Perform encryption using the same cpu that IO was submitted on.
+    The default is to use an unbound workqueue so that encryption work
+    is automatically balanced between available CPUs.
+
+high_priority
+    Set dm-crypt workqueues and the writer thread to high priority. This
+    improves throughput and latency of dm-crypt while degrading general
+    responsiveness of the system.
+
+submit_from_crypt_cpus
+    Disable offloading writes to a separate thread after encryption.
+    There are some situations where offloading write bios from the
+    encryption threads to a single thread degrades performance
+    significantly.  The default is to offload write bios to the same
+    thread because it benefits CFQ to have writes submitted using the
+    same context.
+
+no_read_workqueue
+    Bypass dm-crypt internal workqueue and process read requests synchronously.
+
+no_write_workqueue
+    Bypass dm-crypt internal workqueue and process write requests synchronously.
+    This option is automatically enabled for host-managed zoned block devices
+    (e.g. host-managed SMR hard-disks).
+
+integrity:<bytes>:<type>
+    The device requires additional <bytes> metadata per-sector stored
+    in per-bio integrity structure. This metadata must by provided
+    by underlying dm-integrity target.
+
+    The <type> can be "none" if metadata is used only for persistent IV.
+
+    For Authenticated Encryption with Additional Data (AEAD)
+    the <type> is "aead". An AEAD mode additionally calculates and verifies
+    integrity for the encrypted device. The additional space is then
+    used for storing authentication tag (and persistent IV if needed).
+
+integrity_key_size:<bytes>
+    Optionally set the integrity key size if it differs from the digest size.
+    It allows the use of wrapped key algorithms where the key size is
+    independent of the cryptographic key size.
+
+sector_size:<bytes>
+    Use <bytes> as the encryption unit instead of 512 bytes sectors.
+    This option can be in range 512 - 4096 bytes and must be power of two.
+    Virtual device will announce this size as a minimal IO and logical sector.
+
+iv_large_sectors
+   IV generators will use sector number counted in <sector_size> units
+   instead of default 512 bytes sectors.
+
+   For example, if <sector_size> is 4096 bytes, plain64 IV for the second
+   sector will be 8 (without flag) and 1 if iv_large_sectors is present.
+   The <iv_offset> must be multiple of <sector_size> (in 512 bytes units)
+   if this flag is specified.
+
+integrity_key_size:<bytes>
+   Use an integrity key of <bytes> size instead of using an integrity key size
+   of the digest size of the used HMAC algorithm.
+
+
+Module parameters::
+   max_read_size
+      Maximum size of read requests. When a request larger than this size
+      is received, dm-crypt will split the request. The splitting improves
+      concurrency (the split requests could be encrypted in parallel by multiple
+      cores), but it also causes overhead. The user should tune this parameters to
+      fit the actual workload.
+
+   max_write_size
+      Maximum size of write requests. When a request larger than this size
+      is received, dm-crypt will split the request. The splitting improves
+      concurrency (the split requests could be encrypted in parallel by multiple
+      cores), but it also causes overhead. The user should tune this parameters to
+      fit the actual workload.
+
+
+Example scripts
+===============
+LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
+encryption with dm-crypt using the 'cryptsetup' utility, see
+https://gitlab.com/cryptsetup/cryptsetup
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using dmsetup
+	dmsetup create crypt1 --table "0 `blockdev --getsz $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using dmsetup when encryption key is stored in keyring service
+	dmsetup create crypt2 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 :32:logon:my_prefix:my_key 0 $1 0"
+
+::
+
+	#!/bin/sh
+	# Create a crypt device using cryptsetup and LUKS header with default cipher
+	cryptsetup luksFormat $1
+	cryptsetup luksOpen $1 crypt1
diff --git a/Documentation/admin-guide/device-mapper/dm-dust.rst b/Documentation/admin-guide/device-mapper/dm-dust.rst
new file mode 100644
index 000000000..e35ec8cd2
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-dust.rst
@@ -0,0 +1,305 @@
+dm-dust
+=======
+
+This target emulates the behavior of bad sectors at arbitrary
+locations, and the ability to enable the emulation of the failures
+at an arbitrary time.
+
+This target behaves similarly to a linear target.  At a given time,
+the user can send a message to the target to start failing read
+requests on specific blocks (to emulate the behavior of a hard disk
+drive with bad sectors).
+
+When the failure behavior is enabled (i.e.: when the output of
+"dmsetup status" displays "fail_read_on_bad_block"), reads of blocks
+in the "bad block list" will fail with EIO ("Input/output error").
+
+Writes of blocks in the "bad block list will result in the following:
+
+1. Remove the block from the "bad block list".
+2. Successfully complete the write.
+
+This emulates the "remapped sector" behavior of a drive with bad
+sectors.
+
+Normally, a drive that is encountering bad sectors will most likely
+encounter more bad sectors, at an unknown time or location.
+With dm-dust, the user can use the "addbadblock" and "removebadblock"
+messages to add arbitrary bad blocks at new locations, and the
+"enable" and "disable" messages to modulate the state of whether the
+configured "bad blocks" will be treated as bad, or bypassed.
+This allows the pre-writing of test data and metadata prior to
+simulating a "failure" event where bad sectors start to appear.
+
+Table parameters
+----------------
+<device_path> <offset> <blksz>
+
+Mandatory parameters:
+    <device_path>:
+        Path to the block device.
+
+    <offset>:
+        Offset to data area from start of device_path
+
+    <blksz>:
+        Block size in bytes
+
+	     (minimum 512, maximum 1073741824, must be a power of 2)
+
+Usage instructions
+------------------
+
+First, find the size (in 512-byte sectors) of the device to be used::
+
+        $ sudo blockdev --getsz /dev/vdb1
+        33552384
+
+Create the dm-dust device:
+(For a device with a block size of 512 bytes)
+
+::
+
+        $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 512'
+
+(For a device with a block size of 4096 bytes)
+
+::
+
+        $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 4096'
+
+Check the status of the read behavior ("bypass" indicates that all I/O
+will be passed through to the underlying device; "verbose" indicates that
+bad block additions, removals, and remaps will be verbosely logged)::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 bypass verbose
+
+        $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=128 iflag=direct
+        128+0 records in
+        128+0 records out
+
+        $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct
+        128+0 records in
+        128+0 records out
+
+Adding and removing bad blocks
+------------------------------
+
+At any time (i.e.: whether the device has the "bad block" emulation
+enabled or disabled), bad blocks may be added or removed from the
+device via the "addbadblock" and "removebadblock" messages::
+
+        $ sudo dmsetup message dust1 0 addbadblock 60
+        kernel: device-mapper: dust: badblock added at block 60
+
+        $ sudo dmsetup message dust1 0 addbadblock 67
+        kernel: device-mapper: dust: badblock added at block 67
+
+        $ sudo dmsetup message dust1 0 addbadblock 72
+        kernel: device-mapper: dust: badblock added at block 72
+
+These bad blocks will be stored in the "bad block list".
+While the device is in "bypass" mode, reads and writes will succeed::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 bypass
+
+Enabling block read failures
+----------------------------
+
+To enable the "fail read on bad block" behavior, send the "enable" message::
+
+        $ sudo dmsetup message dust1 0 enable
+        kernel: device-mapper: dust: enabling read failures on bad sectors
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block
+
+With the device in "fail read on bad block" mode, attempting to read a
+block will encounter an "Input/output error"::
+
+        $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=1 skip=67 iflag=direct
+        dd: error reading '/dev/mapper/dust1': Input/output error
+        0+0 records in
+        0+0 records out
+        0 bytes copied, 0.00040651 s, 0.0 kB/s
+
+...and writing to the bad blocks will remove the blocks from the list,
+therefore emulating the "remap" behavior of hard disk drives::
+
+        $ sudo dd if=/dev/zero of=/dev/mapper/dust1 bs=512 count=128 oflag=direct
+        128+0 records in
+        128+0 records out
+
+        kernel: device-mapper: dust: block 60 removed from badblocklist by write
+        kernel: device-mapper: dust: block 67 removed from badblocklist by write
+        kernel: device-mapper: dust: block 72 removed from badblocklist by write
+        kernel: device-mapper: dust: block 87 removed from badblocklist by write
+
+Bad block add/remove error handling
+-----------------------------------
+
+Attempting to add a bad block that already exists in the list will
+result in an "Invalid argument" error, as well as a helpful message::
+
+        $ sudo dmsetup message dust1 0 addbadblock 88
+        device-mapper: message ioctl on dust1  failed: Invalid argument
+        kernel: device-mapper: dust: block 88 already in badblocklist
+
+Attempting to remove a bad block that doesn't exist in the list will
+result in an "Invalid argument" error, as well as a helpful message::
+
+        $ sudo dmsetup message dust1 0 removebadblock 87
+        device-mapper: message ioctl on dust1  failed: Invalid argument
+        kernel: device-mapper: dust: block 87 not found in badblocklist
+
+Counting the number of bad blocks in the bad block list
+-------------------------------------------------------
+
+To count the number of bad blocks configured in the device, run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 countbadblocks
+
+A message will print with the number of bad blocks currently
+configured on the device::
+
+        countbadblocks: 895 badblock(s) found
+
+Querying for specific bad blocks
+--------------------------------
+
+To find out if a specific block is in the bad block list, run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 queryblock 72
+
+The following message will print if the block is in the list::
+
+        dust_query_block: block 72 found in badblocklist
+
+The following message will print if the block is not in the list::
+
+        dust_query_block: block 72 not found in badblocklist
+
+The "queryblock" message command will work in both the "enabled"
+and "disabled" modes, allowing the verification of whether a block
+will be treated as "bad" without having to issue I/O to the device,
+or having to "enable" the bad block emulation.
+
+Clearing the bad block list
+---------------------------
+
+To clear the bad block list (without needing to individually run
+a "removebadblock" message command for every block), run the
+following message command::
+
+        $ sudo dmsetup message dust1 0 clearbadblocks
+
+After clearing the bad block list, the following message will appear::
+
+        dust_clear_badblocks: badblocks cleared
+
+If there were no bad blocks to clear, the following message will
+appear::
+
+        dust_clear_badblocks: no badblocks found
+
+Listing the bad block list
+--------------------------
+
+To list all bad blocks in the bad block list (using an example device
+with blocks 1 and 2 in the bad block list), run the following message
+command::
+
+        $ sudo dmsetup message dust1 0 listbadblocks
+        1
+        2
+
+If there are no bad blocks in the bad block list, the command will
+execute with no output::
+
+        $ sudo dmsetup message dust1 0 listbadblocks
+
+Message commands list
+---------------------
+
+Below is a list of the messages that can be sent to a dust device:
+
+Operations on blocks (requires a <blknum> argument)::
+
+        addbadblock <blknum>
+        queryblock <blknum>
+        removebadblock <blknum>
+
+...where <blknum> is a block number within range of the device
+(corresponding to the block size of the device.)
+
+Single argument message commands::
+
+        countbadblocks
+        clearbadblocks
+        listbadblocks
+        disable
+        enable
+        quiet
+
+Device removal
+--------------
+
+When finished, remove the device via the "dmsetup remove" command::
+
+        $ sudo dmsetup remove dust1
+
+Quiet mode
+----------
+
+On test runs with many bad blocks, it may be desirable to avoid
+excessive logging (from bad blocks added, removed, or "remapped").
+This can be done by enabling "quiet mode" via the following message::
+
+        $ sudo dmsetup message dust1 0 quiet
+
+This will suppress log messages from add / remove / removed by write
+operations.  Log messages from "countbadblocks" or "queryblock"
+message commands will still print in quiet mode.
+
+The status of quiet mode can be seen by running "dmsetup status"::
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block quiet
+
+To disable quiet mode, send the "quiet" message again::
+
+        $ sudo dmsetup message dust1 0 quiet
+
+        $ sudo dmsetup status dust1
+        0 33552384 dust 252:17 fail_read_on_bad_block verbose
+
+(The presence of "verbose" indicates normal logging.)
+
+"Why not...?"
+-------------
+
+scsi_debug has a "medium error" mode that can fail reads on one
+specified sector (sector 0x1234, hardcoded in the source code), but
+it uses RAM for the persistent storage, which drastically decreases
+the potential device size.
+
+dm-flakey fails all I/O from all block locations at a specified time
+frequency, and not a given point in time.
+
+When a bad sector occurs on a hard disk drive, reads to that sector
+are failed by the device, usually resulting in an error code of EIO
+("I/O error") or ENODATA ("No data available").  However, a write to
+the sector may succeed, and result in the sector becoming readable
+after the device controller no longer experiences errors reading the
+sector (or after a reallocation of the sector).  However, there may
+be bad sectors that occur on the device in the future, in a different,
+unpredictable location.
+
+This target seeks to provide a device that can exhibit the behavior
+of a bad sector at a known sector location, at a known time, based
+on a large storage device (at least tens of gigabytes, not occupying
+system memory).
diff --git a/Documentation/admin-guide/device-mapper/dm-ebs.rst b/Documentation/admin-guide/device-mapper/dm-ebs.rst
new file mode 100644
index 000000000..c09f66db5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ebs.rst
@@ -0,0 +1,51 @@
+======
+dm-ebs
+======
+
+
+This target is similar to the linear target except that it emulates
+a smaller logical block size on a device with a larger logical block
+size.  Its main purpose is to provide emulation of 512 byte sectors on
+devices that do not provide this emulation (i.e. 4K native disks).
+
+Supported emulated logical block sizes 512, 1024, 2048 and 4096.
+
+Underlying block size can be set to > 4K to test buffering larger units.
+
+
+Table parameters
+----------------
+  <dev path> <offset> <emulated sectors> [<underlying sectors>]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device,
+        or a "major:minor" device-number.
+    <offset>:
+        Starting sector within the device;
+        has to be a multiple of <emulated sectors>.
+    <emulated sectors>:
+        Number of sectors defining the logical block size to be emulated;
+        1, 2, 4, 8 sectors of 512 bytes supported.
+
+Optional parameter:
+
+    <underlying sectors>:
+        Number of sectors defining the logical block size of <dev path>.
+        2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB.
+        If not provided, the logical block size of <dev path> will be used.
+
+
+Examples:
+
+Emulate 1 sector = 512 bytes logical block size on /dev/sda starting at
+offset 1024 sectors with underlying devices block size automatically set:
+
+ebs /dev/sda 1024 1
+
+Emulate 2 sector = 1KiB logical block size on /dev/sda starting at
+offset 128 sectors, enforce 2KiB underlying device block size.
+This presumes 2KiB logical blocksize on /dev/sda or less to work:
+
+ebs /dev/sda 128 2 4
diff --git a/Documentation/admin-guide/device-mapper/dm-flakey.rst b/Documentation/admin-guide/device-mapper/dm-flakey.rst
new file mode 100644
index 000000000..f967c5fea
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-flakey.rst
@@ -0,0 +1,88 @@
+=========
+dm-flakey
+=========
+
+This target is the same as the linear target except that it exhibits
+unreliable behaviour periodically.  It's been found useful in simulating
+failing devices for testing purposes.
+
+Starting from the time the table is loaded, the device is available for
+<up interval> seconds, then exhibits unreliable behaviour for <down
+interval> seconds, and then this cycle repeats.
+
+Also, consider using this in combination with the dm-delay target too,
+which can delay reads and writes and/or send them to different
+underlying devices.
+
+Table parameters
+----------------
+
+::
+
+  <dev path> <offset> <up interval> <down interval> \
+    [<num_features> [<feature arguments>]]
+
+Mandatory parameters:
+
+    <dev path>:
+        Full pathname to the underlying block-device, or a
+        "major:minor" device-number.
+    <offset>:
+        Starting sector within the device.
+    <up interval>:
+        Number of seconds device is available.
+    <down interval>:
+        Number of seconds device returns errors.
+
+Optional feature parameters:
+
+  If no feature parameters are present, during the periods of
+  unreliability, all I/O returns errors.
+
+  error_reads:
+	All read I/O is failed with an error signalled.
+	Write I/O is handled correctly.
+
+  drop_writes:
+	All write I/O is silently ignored.
+	Read I/O is handled correctly.
+
+  error_writes:
+	All write I/O is failed with an error signalled.
+	Read I/O is handled correctly.
+
+  corrupt_bio_byte <Nth_byte> <direction> <value> <flags>:
+	During <down interval>, replace <Nth_byte> of the data of
+	each matching bio with <value>.
+
+    <Nth_byte>:
+	The offset of the byte to replace.
+	Counting starts at 1, to replace the first byte.
+    <direction>:
+	Either 'r' to corrupt reads or 'w' to corrupt writes.
+	'w' is incompatible with drop_writes.
+    <value>:
+	The value (from 0-255) to write.
+    <flags>:
+	Perform the replacement only if bio->bi_opf has all the
+	selected flags set.
+
+  random_read_corrupt <probability>
+	During <down interval>, replace random byte in a read bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+  random_write_corrupt <probability>
+	During <down interval>, replace random byte in a write bio
+	with a random value. probability is an integer between
+	0 and 1000000000 meaning 0% to 100% probability of corruption.
+
+Examples:
+
+Replaces the 32nd byte of READ bios with the value 1::
+
+  corrupt_bio_byte 32 r 1 0
+
+Replaces the 224th byte of REQ_META (=32) bios with the value 0::
+
+  corrupt_bio_byte 224 w 0 32
diff --git a/Documentation/admin-guide/device-mapper/dm-ima.rst b/Documentation/admin-guide/device-mapper/dm-ima.rst
new file mode 100644
index 000000000..2a3b50ffb
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-ima.rst
@@ -0,0 +1,718 @@
+======
+dm-ima
+======
+
+For a given system, various external services/infrastructure tools
+(including the attestation service) interact with it - both during the
+setup and during rest of the system run-time.  They share sensitive data
+and/or execute critical workload on that system.  The external services
+may want to verify the current run-time state of the relevant kernel
+subsystems before fully trusting the system with business-critical
+data/workload.
+
+Device mapper plays a critical role on a given system by providing
+various important functionalities to the block devices using various
+target types like crypt, verity, integrity etc.  Each of these target
+types’ functionalities can be configured with various attributes.
+The attributes chosen to configure these target types can significantly
+impact the security profile of the block device, and in-turn, of the
+system itself.  For instance, the type of encryption algorithm and the
+key size determines the strength of encryption for a given block device.
+
+Therefore, verifying the current state of various block devices as well
+as their various target attributes is crucial for external services before
+fully trusting the system with business-critical data/workload.
+
+IMA kernel subsystem provides the necessary functionality for
+device mapper to measure the state and configuration of
+various block devices -
+
+- by device mapper itself, from within the kernel,
+- in a tamper resistant way,
+- and re-measured - triggered on state/configuration change.
+
+Setting the IMA Policy:
+=======================
+For IMA to measure the data on a given system, the IMA policy on the
+system needs to be updated to have following line, and the system needs
+to be restarted for the measurements to take effect.
+
+::
+
+ /etc/ima/ima-policy
+    measure func=CRITICAL_DATA label=device-mapper template=ima-buf
+
+The measurements will be reflected in the IMA logs, which are located at:
+
+::
+
+ /sys/kernel/security/integrity/ima/ascii_runtime_measurements
+ /sys/kernel/security/integrity/ima/binary_runtime_measurements
+
+Then IMA ASCII measurement log has the following format:
+
+::
+
+ <PCR> <TEMPLATE_DATA_DIGEST> <TEMPLATE_NAME> <TEMPLATE_DATA>
+
+ PCR := Platform Configuration Register, in which the values are registered.
+       This is applicable if TPM chip is in use.
+
+ TEMPLATE_DATA_DIGEST := Template data digest of the IMA record.
+ TEMPLATE_NAME := Template name that registered the integrity value (e.g. ima-buf).
+
+ TEMPLATE_DATA := <ALG> ":" <EVENT_DIGEST> <EVENT_NAME> <EVENT_DATA>
+                  It contains data for the specific event to be measured,
+                  in a given template data format.
+
+ ALG := Algorithm to compute event digest
+ EVENT_DIGEST := Digest of the event data
+ EVENT_NAME := Description of the event (e.g. 'dm_table_load').
+ EVENT_DATA := The event data to be measured.
+
+|
+
+| *NOTE #1:*
+| The DM target data measured by IMA subsystem can alternatively
+ be queried from userspace by setting DM_IMA_MEASUREMENT_FLAG with
+ DM_TABLE_STATUS_CMD.
+
+|
+
+| *NOTE #2:*
+| The Kernel configuration CONFIG_IMA_DISABLE_HTABLE allows measurement of duplicate records.
+| To support recording duplicate IMA events in the IMA log, the Kernel needs to be configured with
+ CONFIG_IMA_DISABLE_HTABLE=y.
+
+Supported Device States:
+========================
+Following device state changes will trigger IMA measurements:
+
+ 1. Table load
+ #. Device resume
+ #. Device remove
+ #. Table clear
+ #. Device rename
+
+1. Table load:
+---------------
+When a new table is loaded in a device's inactive table slot,
+the device information and target specific details from the
+targets in the table are measured.
+
+The IMA measurement log has the following format for 'dm_table_load':
+
+::
+
+ EVENT_NAME := "dm_table_load"
+ EVENT_DATA := <dm_version_str> ";" <device_metadata> ";" <table_load_data>
+
+ dm_version_str := "dm_version=" <N> "." <N> "." <N>
+                  Same as Device Mapper driver version.
+ device_metadata := <device_name> "," <device_uuid> "," <device_major> "," <device_minor> ","
+                   <minor_count> "," <num_device_targets> ";"
+
+ device_name := "name=" <dm-device-name>
+ device_uuid := "uuid=" <dm-device-uuid>
+ device_major := "major=" <N>
+ device_minor := "minor=" <N>
+ minor_count := "minor_count=" <N>
+ num_device_targets := "num_targets=" <N>
+ dm-device-name := Name of the device. If it contains special characters like '\', ',', ';',
+                   they are prefixed with '\'.
+ dm-device-uuid := UUID of the device. If it contains special characters like '\', ',', ';',
+                   they are prefixed with '\'.
+
+ table_load_data := <target_data>
+                    Represents the data (as name=value pairs) from various targets in the table,
+                    which is being loaded into the DM device's inactive table slot.
+ target_data := <target_data_row> | <target_data><target_data_row>
+
+ target_data_row := <target_index> "," <target_begin> "," <target_len> "," <target_name> ","
+                    <target_version> "," <target_attributes> ";"
+ target_index := "target_index=" <N>
+                 Represents nth target in the table (from 0 to N-1 targets specified in <num_device_targets>)
+                 If all the data for N targets doesn't fit in the given buffer - then the data that fits
+                 in the buffer (say from target 0 to x) is measured in a given IMA event.
+                 The remaining data from targets x+1 to N-1 is measured in the subsequent IMA events,
+                 with the same format as that of 'dm_table_load'
+                 i.e. <dm_version_str> ";" <device_metadata> ";" <table_load_data>.
+
+ target_begin := "target_begin=" <N>
+ target_len := "target_len=" <N>
+ target_name := Name of the target. 'linear', 'crypt', 'integrity' etc.
+                The targets that are supported for IMA measurements are documented below in the
+                'Supported targets' section.
+ target_version := "target_version=" <N> "." <N> "." <N>
+ target_attributes := Data containing comma separated list of name=value pairs of target specific attributes.
+
+ For instance, if a linear device is created with the following table entries,
+  # dmsetup create linear1
+  0 2 linear /dev/loop0 512
+  2 2 linear /dev/loop0 512
+  4 2 linear /dev/loop0 512
+  6 2 linear /dev/loop0 512
+
+ Then IMA ASCII measurement log will have the following entry:
+ (converted from ASCII to text for readability)
+
+ 10 a8c5ff755561c7a28146389d1514c318592af49a ima-buf sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72
+ dm_table_load
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+ target_index=0,target_begin=0,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=1,target_begin=2,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=2,target_begin=4,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+ target_index=3,target_begin=6,target_len=2,target_name=linear,target_version=1.4.0,device_name=7:0,start=512;
+
+2. Device resume:
+------------------
+When a suspended device is resumed, the device information and the hash of the
+data from previous load of an active table are measured.
+
+The IMA measurement log has the following format for 'dm_device_resume':
+
+::
+
+ EVENT_NAME := "dm_device_resume"
+ EVENT_DATA := <dm_version_str> ";" <device_metadata> ";" <active_table_hash> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_metadata := As described in the 'Table load' section above.
+ active_table_hash := "active_table_hash=" <table_hash_alg> ":" <table_hash>
+                      Rerpresents the hash of the IMA data being measured for the
+                      active table for the device.
+ table_hash_alg := Algorithm used to compute the hash.
+ table_hash := Hash of the (<dm_version_str> ";" <device_metadata> ";" <table_load_data> ";")
+               as described in the 'dm_table_load' above.
+               Note: If the table_load data spans across multiple IMA 'dm_table_load'
+               events for a given device, the hash is computed combining all the event data
+               i.e. (<dm_version_str> ";" <device_metadata> ";" <table_load_data> ";")
+               across all those events.
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device is resumed with the following command,
+ #dmsetup resume linear1
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 56c00cc062ffc24ccd9ac2d67d194af3282b934e ima-buf sha256:e7d12c03b958b4e0e53e7363a06376be88d98a1ac191fdbd3baf5e4b77f329b6
+ dm_device_resume
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=0,minor_count=1,num_targets=4;
+ active_table_hash=sha256:4d73481ecce5eadba8ab084640d85bb9ca899af4d0a122989252a76efadc5b72;current_device_capacity=8;
+
+3. Device remove:
+------------------
+When a device is removed, the device information and a sha256 hash of the
+data from an active and inactive table are measured.
+
+The IMA measurement log has the following format for 'dm_device_remove':
+
+::
+
+ EVENT_NAME := "dm_device_remove"
+ EVENT_DATA := <dm_version_str> ";" <device_active_metadata> ";" <device_inactive_metadata> ";"
+               <active_table_hash> "," <inactive_table_hash> "," <remove_all> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_active_metadata := Device metadata that reflects the currently loaded active table.
+                           The format is same as 'device_metadata' described in the 'Table load' section above.
+ device_inactive_metadata := Device metadata that reflects the inactive table.
+                             The format is same as 'device_metadata' described in the 'Table load' section above.
+ active_table_hash := Hash of the currently loaded active table.
+                      The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ inactive_table_hash :=  Hash of the inactive table.
+                         The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ remove_all := "remove_all=" <yes_no>
+ yes_no := "y" | "n"
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device is removed with the following command,
+  #dmsetup remove l1
+
+ then IMA ASCII measurement log will have the following entry:
+ (converted from ASCII to text for readability)
+
+ 10 790e830a3a7a31590824ac0642b3b31c2d0e8b38 ima-buf sha256:ab9f3c959367a8f5d4403d6ce9c3627dadfa8f9f0e7ec7899299782388de3840
+ dm_device_remove
+ dm_version=4.45.0;
+ device_active_metadata=name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=2;
+ device_inactive_metadata=name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ active_table_hash=sha256:4a7e62efaebfc86af755831998b7db6f59b60d23c9534fb16a4455907957953a,
+ inactive_table_hash=sha256:9d79c175bc2302d55a183e8f50ad4bafd60f7692fd6249e5fd213e2464384b86,remove_all=n;
+ current_device_capacity=2048;
+
+4. Table clear:
+----------------
+When an inactive table is cleared from the device, the device information and a sha256 hash of the
+data from an inactive table are measured.
+
+The IMA measurement log has the following format for 'dm_table_clear':
+
+::
+
+ EVENT_NAME := "dm_table_clear"
+ EVENT_DATA := <dm_version_str> ";" <device_inactive_metadata> ";" <inactive_table_hash> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_inactive_metadata := Device metadata that was captured during the load time inactive table being cleared.
+                             The format is same as 'device_metadata' described in the 'Table load' section above.
+ inactive_table_hash := Hash of the inactive table being cleared from the device.
+                        The format is same as 'active_table_hash' described in the 'Device resume' section above.
+ current_device_capacity := "current_device_capacity=" <N>
+
+ For instance, if a linear device's inactive table is cleared,
+  #dmsetup clear l1
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 77d347408f557f68f0041acb0072946bb2367fe5 ima-buf sha256:42f9ca22163fdfa548e6229dece2959bc5ce295c681644240035827ada0e1db5
+ dm_table_clear
+ dm_version=4.45.0;
+ name=l1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ inactive_table_hash=sha256:75c0dc347063bf474d28a9907037eba060bfe39d8847fc0646d75e149045d545;current_device_capacity=1024;
+
+5. Device rename:
+------------------
+When an device's NAME or UUID is changed, the device information and the new NAME and UUID
+are measured.
+
+The IMA measurement log has the following format for 'dm_device_rename':
+
+::
+
+ EVENT_NAME := "dm_device_rename"
+ EVENT_DATA := <dm_version_str> ";" <device_active_metadata> ";" <new_device_name> "," <new_device_uuid> ";" <current_device_capacity> ";"
+
+ dm_version_str := As described in the 'Table load' section above.
+ device_active_metadata := Device metadata that reflects the currently loaded active table.
+                           The format is same as 'device_metadata' described in the 'Table load' section above.
+ new_device_name := "new_name=" <dm-device-name>
+ dm-device-name := Same as <dm-device-name> described in 'Table load' section above
+ new_device_uuid := "new_uuid=" <dm-device-uuid>
+ dm-device-uuid := Same as <dm-device-uuid> described in 'Table load' section above
+ current_device_capacity := "current_device_capacity=" <N>
+
+ E.g 1: if a linear device's name is changed with the following command,
+  #dmsetup rename linear1 --setuuid 1234-5678
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 8b0423209b4c66ac1523f4c9848c9b51ee332f48 ima-buf sha256:6847b7258134189531db593e9230b257c84f04038b5a18fd2e1473860e0569ac
+ dm_device_rename
+ dm_version=4.45.0;
+ name=linear1,uuid=,major=253,minor=2,minor_count=1,num_targets=1;new_name=linear1,new_uuid=1234-5678;
+ current_device_capacity=1024;
+
+ E.g 2:  if a linear device's name is changed with the following command,
+  # dmsetup rename linear1 linear=2
+
+ then IMA ASCII measurement log will have an entry with:
+ (converted from ASCII to text for readability)
+
+ 10 bef70476b99c2bdf7136fae033aa8627da1bf76f ima-buf sha256:8c6f9f53b9ef9dc8f92a2f2cca8910e622543d0f0d37d484870cb16b95111402
+ dm_device_rename
+ dm_version=4.45.0;
+ name=linear1,uuid=1234-5678,major=253,minor=2,minor_count=1,num_targets=1;
+ new_name=linear\=2,new_uuid=1234-5678;
+ current_device_capacity=1024;
+
+Supported targets:
+==================
+
+Following targets are supported to measure their data using IMA:
+
+ 1. cache
+ #. crypt
+ #. integrity
+ #. linear
+ #. mirror
+ #. multipath
+ #. raid
+ #. snapshot
+ #. striped
+ #. verity
+
+1. cache
+---------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'cache' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <metadata_mode> "," <cache_metadata_device> ","
+                      <cache_device> "," <cache_origin_device> "," <writethrough> "," <writeback> ","
+                      <passthrough> "," <no_discard_passdown> ";"
+
+ target_name := "target_name=cache"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ metadata_mode := "metadata_mode=" <cache_metadata_mode>
+ cache_metadata_mode := "fail" | "ro" | "rw"
+ cache_device := "cache_device=" <cache_device_name_string>
+ cache_origin_device := "cache_origin_device=" <cache_origin_device_string>
+ writethrough := "writethrough=" <yes_no>
+ writeback := "writeback=" <yes_no>
+ passthrough := "passthrough=" <yes_no>
+ no_discard_passdown := "no_discard_passdown=" <yes_no>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'cache' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'cache' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;name=cache1,uuid=cache_uuid,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=28672,target_name=cache,target_version=2.2.0,metadata_mode=rw,
+ cache_metadata_device=253:4,cache_device=253:3,cache_origin_device=253:5,writethrough=y,writeback=n,
+ passthrough=n,metadata2=y,no_discard_passdown=n;
+
+
+2. crypt
+---------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'crypt' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <allow_discards> "," <same_cpu_crypt> ","
+                      <submit_from_crypt_cpus> "," <no_read_workqueue> "," <no_write_workqueue> ","
+                      <iv_large_sectors> "," <iv_large_sectors> "," [<integrity_tag_size> ","] [<cipher_auth> ","]
+                      [<sector_size> ","] [<cipher_string> ","] <key_size> "," <key_parts> ","
+                      <key_extra_size> "," <key_mac_size> ";"
+
+ target_name := "target_name=crypt"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ allow_discards := "allow_discards=" <yes_no>
+ same_cpu_crypt := "same_cpu_crypt=" <yes_no>
+ submit_from_crypt_cpus := "submit_from_crypt_cpus=" <yes_no>
+ no_read_workqueue := "no_read_workqueue=" <yes_no>
+ no_write_workqueue := "no_write_workqueue=" <yes_no>
+ iv_large_sectors := "iv_large_sectors=" <yes_no>
+ integrity_tag_size := "integrity_tag_size=" <N>
+ cipher_auth := "cipher_auth=" <string>
+ sector_size := "sector_size="  <N>
+ cipher_string := "cipher_string="
+ key_size := "key_size="  <N>
+ key_parts := "key_parts="  <N>
+ key_extra_size := "key_extra_size="  <N>
+ key_mac_size := "key_mac_size="  <N>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'crypt' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'crypt' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=crypt1,uuid=crypt_uuid1,major=253,minor=0,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=1953125,target_name=crypt,target_version=1.23.0,
+ allow_discards=y,same_cpu=n,submit_from_crypt_cpus=n,no_read_workqueue=n,no_write_workqueue=n,
+ iv_large_sectors=n,cipher_string=aes-xts-plain64,key_size=32,key_parts=1,key_extra_size=0,key_mac_size=0;
+
+3. integrity
+-------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'integrity' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <dev_name> "," <start>
+                      <tag_size> "," <mode> "," [<meta_device> ","] [<block_size> ","] <recalculate> ","
+                      <allow_discards> "," <allow_discards_keyed> "," <fix_padding> "," <fix_hmac> ","
+                      <legacy_recalculate> ","
+                      <journal_sectors> "," <interleave_sectors> "," <buffer_sectors> ";"
+
+ target_name := "target_name=integrity"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ dev_name := "dev_name=" <device_name_str>
+ start := "start=" <N>
+ tag_size := "tag_size=" <N>
+ mode := "mode=" <integrity_mode_str>
+ integrity_mode_str := "J" | "B" | "D" | "R"
+ meta_device := "meta_device=" <meta_device_str>
+ block_size := "block_size=" <N>
+ recalculate := "recalculate=" <yes_no>
+ allow_discards := "allow_discards=" <yes_no>
+ allow_discards_keyed := "allow_discards_keyed=" <yes_no>
+ fix_padding := "fix_padding=" <yes_no>
+ fix_hmac := "fix_hmac=" <yes_no>
+ legacy_recalculate := "legacy_recalculate=" <yes_no>
+ journal_sectors := "journal_sectors=" <N>
+ interleave_sectors := "interleave_sectors=" <N>
+ buffer_sectors := "buffer_sectors=" <N>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'integrity' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'integrity' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=integrity1,uuid=,major=253,minor=1,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=7856,target_name=integrity,target_version=1.10.0,
+ dev_name=253:0,start=0,tag_size=32,mode=J,recalculate=n,allow_discards=n,
+ allow_discards_keyed=n,fix_padding=n,
+ fix_hmac=n,legacy_recalculate=n,journal_sectors=88,interleave_sectors=32768,buffer_sectors=128;
+
+
+4. linear
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'linear' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <device_name> <,> <start> ";"
+
+ target_name := "target_name=linear"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ device_name := "device_name=" <linear_device_name_str>
+ start := "start=" <N>
+
+ E.g.
+ When a 'linear' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'linear' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=linear1,uuid=linear_uuid1,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=28672,target_name=linear,target_version=1.4.0,
+ device_name=253:1,start=2048;
+
+5. mirror
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'mirror' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <nr_mirrors> ","
+                      <mirror_device_data> "," <handle_errors> "," <keep_log> "," <log_type_status> ";"
+
+ target_name := "target_name=mirror"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ nr_mirrors := "nr_mirrors=" <NR>
+ mirror_device_data := <mirror_device_row> | <mirror_device_data><mirror_device_row>
+                       mirror_device_row is repeated <NR> times - for <NR> described in <nr_mirrors>.
+ mirror_device_row := <mirror_device_name> "," <mirror_device_status>
+ mirror_device_name := "mirror_device_" <X> "=" <mirror_device_name_str>
+                       where <X> ranges from 0 to (<NR> -1) - for <NR> described in <nr_mirrors>.
+ mirror_device_status := "mirror_device_" <X> "_status=" <mirror_device_status_char>
+                         where <X> ranges from 0 to (<NR> -1) - for <NR> described in <nr_mirrors>.
+ mirror_device_status_char := "A" | "F" | "D" | "S" | "R" | "U"
+ handle_errors := "handle_errors=" <yes_no>
+ keep_log := "keep_log=" <yes_no>
+ log_type_status := "log_type_status=" <log_type_status_str>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'mirror' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'mirror' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=mirror1,uuid=mirror_uuid1,major=253,minor=6,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2048,target_name=mirror,target_version=1.14.0,nr_mirrors=2,
+    mirror_device_0=253:4,mirror_device_0_status=A,
+    mirror_device_1=253:5,mirror_device_1_status=A,
+ handle_errors=y,keep_log=n,log_type_status=;
+
+6. multipath
+-------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'multipath' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <nr_priority_groups>
+                      ["," <pg_state> "," <priority_groups> "," <priority_group_paths>] ";"
+
+ target_name := "target_name=multipath"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ nr_priority_groups := "nr_priority_groups=" <NPG>
+ priority_groups := <priority_groups_row>|<priority_groups_row><priority_groups>
+ priority_groups_row := "pg_state_" <X> "=" <pg_state_str> "," "nr_pgpaths_" <X>  "=" <NPGP> ","
+                        "path_selector_name_" <X> "=" <string> "," <priority_group_paths>
+                        where <X> ranges from 0 to (<NPG> -1) - for <NPG> described in <nr_priority_groups>.
+ pg_state_str := "E" | "A" | "D"
+ <priority_group_paths> := <priority_group_paths_row> | <priority_group_paths_row><priority_group_paths>
+ priority_group_paths_row := "path_name_" <X> "_" <Y> "=" <string> "," "is_active_" <X> "_" <Y> "=" <is_active_str>
+                             "fail_count_" <X> "_" <Y> "=" <N> "," "path_selector_status_" <X> "_" <Y> "=" <path_selector_status_str>
+                             where <X> ranges from 0 to (<NPG> -1) - for <NPG> described in <nr_priority_groups>,
+                             and <Y> ranges from 0 to (<NPGP> -1) - for <NPGP> described in <priority_groups_row>.
+ is_active_str := "A" | "F"
+
+ E.g.
+ When a 'multipath' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'multipath' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=mp,uuid=,major=253,minor=0,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2097152,target_name=multipath,target_version=1.14.0,nr_priority_groups=2,
+    pg_state_0=E,nr_pgpaths_0=2,path_selector_name_0=queue-length,
+        path_name_0_0=8:16,is_active_0_0=A,fail_count_0_0=0,path_selector_status_0_0=,
+        path_name_0_1=8:32,is_active_0_1=A,fail_count_0_1=0,path_selector_status_0_1=,
+    pg_state_1=E,nr_pgpaths_1=2,path_selector_name_1=queue-length,
+        path_name_1_0=8:48,is_active_1_0=A,fail_count_1_0=0,path_selector_status_1_0=,
+        path_name_1_1=8:64,is_active_1_1=A,fail_count_1_1=0,path_selector_status_1_1=;
+
+7. raid
+--------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'raid' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <raid_type> "," <raid_disks> "," <raid_state>
+                      <raid_device_status> ["," journal_dev_mode] ";"
+
+ target_name := "target_name=raid"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ raid_type := "raid_type=" <raid_type_str>
+ raid_disks := "raid_disks=" <NRD>
+ raid_state := "raid_state=" <raid_state_str>
+ raid_state_str := "frozen" | "reshape" |"resync" | "check" | "repair" | "recover" | "idle" |"undef"
+ raid_device_status := <raid_device_status_row> | <raid_device_status_row><raid_device_status>
+                       <raid_device_status_row> is repeated <NRD> times - for <NRD> described in <raid_disks>.
+ raid_device_status_row := "raid_device_" <X> "_status=" <raid_device_status_str>
+                           where <X> ranges from 0 to (<NRD> -1) - for <NRD> described in <raid_disks>.
+ raid_device_status_str := "A" | "D" | "a" | "-"
+ journal_dev_mode := "journal_dev_mode=" <journal_dev_mode_str>
+ journal_dev_mode_str := "writethrough" | "writeback" | "invalid"
+
+ E.g.
+ When a 'raid' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'raid' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=raid_LV1,uuid=uuid_raid_LV1,major=253,minor=12,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=2048,target_name=raid,target_version=1.15.1,
+ raid_type=raid10,raid_disks=4,raid_state=idle,
+    raid_device_0_status=A,
+    raid_device_1_status=A,
+    raid_device_2_status=A,
+    raid_device_3_status=A;
+
+
+8. snapshot
+------------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'snapshot' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <snap_origin_name> ","
+                      <snap_cow_name> "," <snap_valid> "," <snap_merge_failed> "," <snapshot_overflowed> ";"
+
+ target_name := "target_name=snapshot"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ snap_origin_name := "snap_origin_name=" <string>
+ snap_cow_name := "snap_cow_name=" <string>
+ snap_valid := "snap_valid=" <yes_no>
+ snap_merge_failed := "snap_merge_failed=" <yes_no>
+ snapshot_overflowed := "snapshot_overflowed=" <yes_no>
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'snapshot' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'snapshot' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=snap1,uuid=snap_uuid1,major=253,minor=13,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=4096,target_name=snapshot,target_version=1.16.0,
+ snap_origin_name=253:11,snap_cow_name=253:12,snap_valid=y,snap_merge_failed=n,snapshot_overflowed=n;
+
+9. striped
+-----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'striped' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <stripes> "," <chunk_size> ","
+                      <stripe_data> ";"
+
+ target_name := "target_name=striped"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ stripes := "stripes=" <NS>
+ chunk_size := "chunk_size=" <N>
+ stripe_data := <stripe_data_row>|<stripe_data><stripe_data_row>
+ stripe_data_row := <stripe_device_name> "," <stripe_physical_start> "," <stripe_status>
+ stripe_device_name := "stripe_" <X> "_device_name=" <stripe_device_name_str>
+                       where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_physical_start := "stripe_" <X> "_physical_start=" <N>
+                           where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_status := "stripe_" <X> "_status=" <stripe_status_str>
+                  where <X> ranges from 0 to (<NS> -1) - for <NS> described in <stripes>.
+ stripe_status_str := "D" | "A"
+
+ E.g.
+ When a 'striped' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'striped' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=striped1,uuid=striped_uuid1,major=253,minor=5,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=640,target_name=striped,target_version=1.6.0,stripes=2,chunk_size=64,
+    stripe_0_device_name=253:0,stripe_0_physical_start=2048,stripe_0_status=A,
+    stripe_1_device_name=253:3,stripe_1_physical_start=2048,stripe_1_status=A;
+
+10. verity
+----------
+The 'target_attributes' (described as part of EVENT_DATA in 'Table load'
+section above) has the following data format for 'verity' target.
+
+::
+
+ target_attributes := <target_name> "," <target_version> "," <hash_failed> "," <verity_version> ","
+                      <data_device_name> "," <hash_device_name> "," <verity_algorithm> "," <root_digest> ","
+                      <salt> "," <ignore_zero_blocks> "," <check_at_most_once> ["," <root_hash_sig_key_desc>]
+                      ["," <verity_mode>] ";"
+
+ target_name := "target_name=verity"
+ target_version := "target_version=" <N> "." <N> "." <N>
+ hash_failed := "hash_failed=" <hash_failed_str>
+ hash_failed_str := "C" | "V"
+ verity_version := "verity_version=" <verity_version_str>
+ data_device_name := "data_device_name=" <data_device_name_str>
+ hash_device_name := "hash_device_name=" <hash_device_name_str>
+ verity_algorithm := "verity_algorithm=" <verity_algorithm_str>
+ root_digest := "root_digest=" <root_digest_str>
+ salt := "salt=" <salt_str>
+ salt_str := "-" <verity_salt_str>
+ ignore_zero_blocks := "ignore_zero_blocks=" <yes_no>
+ check_at_most_once := "check_at_most_once=" <yes_no>
+ root_hash_sig_key_desc := "root_hash_sig_key_desc="
+ verity_mode := "verity_mode=" <verity_mode_str>
+ verity_mode_str := "ignore_corruption" | "restart_on_corruption" | "panic_on_corruption" | "invalid"
+ yes_no := "y" | "n"
+
+ E.g.
+ When a 'verity' target is loaded, then IMA ASCII measurement log will have an entry
+ similar to the following, depicting what 'verity' attributes are measured in EVENT_DATA
+ for 'dm_table_load' event.
+ (converted from ASCII to text for readability)
+
+ dm_version=4.45.0;
+ name=test-verity,uuid=,major=253,minor=2,minor_count=1,num_targets=1;
+ target_index=0,target_begin=0,target_len=1953120,target_name=verity,target_version=1.8.0,hash_failed=V,
+ verity_version=1,data_device_name=253:1,hash_device_name=253:0,verity_algorithm=sha256,
+ root_digest=29cb87e60ce7b12b443ba6008266f3e41e93e403d7f298f8e3f316b29ff89c5e,
+ salt=e48da609055204e89ae53b655ca2216dd983cf3cb829f34f63a297d106d53e2d,
+ ignore_zero_blocks=n,check_at_most_once=n;
diff --git a/Documentation/admin-guide/device-mapper/dm-init.rst b/Documentation/admin-guide/device-mapper/dm-init.rst
new file mode 100644
index 000000000..981d6a907
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-init.rst
@@ -0,0 +1,133 @@
+================================
+Early creation of mapped devices
+================================
+
+It is possible to configure a device-mapper device to act as the root device for
+your system in two ways.
+
+The first is to build an initial ramdisk which boots to a minimal userspace
+which configures the device, then pivot_root(8) in to it.
+
+The second is to create one or more device-mappers using the module parameter
+"dm-mod.create=" through the kernel boot command line argument.
+
+The format is specified as a string of data separated by commas and optionally
+semi-colons, where:
+
+ - a comma is used to separate fields like name, uuid, flags and table
+   (specifies one device)
+ - a semi-colon is used to separate devices.
+
+So the format will look like this::
+
+ dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+]
+
+Where::
+
+	<name>		::= The device name.
+	<uuid>		::= xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx | ""
+	<minor>		::= The device minor number | ""
+	<flags>		::= "ro" | "rw"
+	<table>		::= <start_sector> <num_sectors> <target_type> <target_args>
+	<target_type>	::= "verity" | "linear" | ... (see list below)
+
+The dm line should be equivalent to the one used by the dmsetup tool with the
+`--concise` argument.
+
+Target types
+============
+
+Not all target types are available as there are serious risks in allowing
+activation of certain DM targets without first using userspace tools to check
+the validity of associated metadata.
+
+======================= =======================================================
+`cache`			constrained, userspace should verify cache device
+`crypt`			allowed
+`delay`			allowed
+`era`			constrained, userspace should verify metadata device
+`flakey`		constrained, meant for test
+`linear`		allowed
+`log-writes`		constrained, userspace should verify metadata device
+`mirror`		constrained, userspace should verify main/mirror device
+`raid`			constrained, userspace should verify metadata device
+`snapshot`		constrained, userspace should verify src/dst device
+`snapshot-origin`	allowed
+`snapshot-merge`	constrained, userspace should verify src/dst device
+`striped`		allowed
+`switch`		constrained, userspace should verify dev path
+`thin`			constrained, requires dm target message from userspace
+`thin-pool`		constrained, requires dm target message from userspace
+`verity`		allowed
+`writecache`		constrained, userspace should verify cache device
+`zero`			constrained, not meant for rootfs
+======================= =======================================================
+
+If the target is not listed above, it is constrained by default (not tested).
+
+Examples
+========
+An example of booting to a linear array made up of user-mode linux block
+devices::
+
+  dm-mod.create="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0
+
+This will boot to a rw dm-linear target of 8192 sectors split across two block
+devices identified by their major:minor numbers.  After boot, udev will rename
+this target to /dev/mapper/lroot (depending on the rules). No uuid was assigned.
+
+An example of multiple device-mappers, with the dm-mod.create="..." contents
+is shown here split on multiple lines for readability::
+
+  dm-linear,,1,rw,
+    0 32768 linear 8:1 0,
+    32768 1024000 linear 8:2 0;
+  dm-verity,,3,ro,
+    0 1638400 verity 1 /dev/sdc1 /dev/sdc2 4096 4096 204800 1 sha256
+    ac87db56303c9c1da433d7209b5a6ef3e4779df141200cbd7c157dcb8dd89c42
+    5ebfe87f7df3235b80a117ebc4078e44f55045487ad4a96581d1adb564615b51
+
+Other examples (per target):
+
+"crypt"::
+
+  dm-crypt,,8,ro,
+    0 1048576 crypt aes-xts-plain64
+    babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0
+    /dev/sda 0 1 allow_discards
+
+"delay"::
+
+  dm-delay,,4,ro,0 409600 delay /dev/sda1 0 500
+
+"linear"::
+
+  dm-linear,,,rw,
+    0 32768 linear /dev/sda1 0,
+    32768 1024000 linear /dev/sda2 0,
+    1056768 204800 linear /dev/sda3 0,
+    1261568 512000 linear /dev/sda4 0
+
+"snapshot-origin"::
+
+  dm-snap-orig,,4,ro,0 409600 snapshot-origin 8:2
+
+"striped"::
+
+  dm-striped,,4,ro,0 1638400 striped 4 4096
+  /dev/sda1 0 /dev/sda2 0 /dev/sda3 0 /dev/sda4 0
+
+"verity"::
+
+  dm-verity,,4,ro,
+    0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256
+    fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd
+    51934789604d1b92399c52e7cb149d1b3a1b74bbbcb103b2a0aaacbed5c08584
+
+For setups using device-mapper on top of asynchronously probed block
+devices (MMC, USB, ..), it may be necessary to tell dm-init to
+explicitly wait for them to become available before setting up the
+device-mapper tables. This can be done with the "dm-mod.waitfor="
+module parameter, which takes a list of devices to wait for::
+
+  dm-mod.waitfor=<device1>[,..,<deviceN>]
diff --git a/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst b/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst
new file mode 100644
index 000000000..8258a72f0
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-inlinecrypt.rst
@@ -0,0 +1,129 @@
+==============
+dm-inlinecrypt
+==============
+
+Device-Mapper's "inlinecrypt" target provides transparent encryption of block devices
+using the inline encryption hardware.
+
+For a more detailed description of inline encryption, see:
+https://docs.kernel.org/block/inline-encryption.html
+
+Parameters::
+
+	      <cipher> <key> <iv_offset> <device path> \
+	      <offset> [<#opt_params> <opt_params>]
+
+<cipher>
+    Encryption cipher type.
+
+    The cipher specifications format is::
+
+       cipher
+
+    Examples::
+
+       aes-xts-plain64
+
+    The cipher type corresponds to the encryption modes supported by
+    inline crypto in the block layer. Currently, only
+    BLK_ENCRYPTION_MODE_AES_256_XTS (i.e. aes-xts-plain64) is supported.
+
+<key>
+    Key used for encryption. It is encoded either as a hexadecimal number
+    or it can be passed as <key_string> prefixed with single colon
+    character (':') for keys residing in kernel keyring service.
+    You can only use key sizes that are valid for the selected cipher.
+    Note that the size in bytes of a valid key must be in below range.
+
+        [BLK_CRYPTO_KEY_TYPE_RAW, BLK_CRYPTO_KEY_TYPE_HW_WRAPPED]
+
+<key_string>
+    The kernel keyring key is identified by string in following format:
+    <key_size>:<keyring_type>:<key_description>.
+
+<key_size>
+    The encryption key size in bytes. The kernel key payload size must match
+    the value passed in <key_size>.
+
+<keyring_type>
+    The type of the key inside the kernel keyring. It can be either 'logon',
+    or 'trusted' kernel key type.
+
+<key_description>
+    The kernel keyring key description inlinecrypt target should look for
+    when loading key of <keyring_type>.
+
+<iv_offset>
+    The IV offset is a sector count that is added to the sector number
+    before creating the IV.
+
+<device path>
+    This is the device that is going to be used as backend and contains the
+    encrypted data.  You can specify it as a path like /dev/xxx or a device
+    number <major>:<minor>.
+
+<offset>
+    Starting sector within the device where the encrypted data begins.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        keytype:raw allow_discards sector_size:4096 iv_large_sectors
+
+<key_type>
+    The type of the key as seen by the block layer, either standard or
+    hardware-wrapped. The string is supplied in the table as <keytype:raw>
+    or <keytype:hw-wrapped>.
+
+allow_discards
+    Block discard requests (a.k.a. TRIM) are passed through the inlinecrypt
+    device. The default is to ignore discard requests.
+
+    WARNING: Assess the specific security risks carefully before enabling this
+    option.  For example, allowing discards on encrypted devices may lead to
+    the leak of information about the ciphertext device (filesystem type,
+    used space etc.) if the discarded blocks can be located easily on the
+    device later.
+
+sector_size:<bytes>
+    Use <bytes> as the encryption unit instead of 512 bytes sectors.
+    This option can be in range 512 - 4096 bytes and must be power of two.
+    Virtual device will announce this size as a minimal IO and logical sector.
+
+iv_large_sectors
+    Use <sector_size>-based sector numbers for IV generation instead of
+    512-byte sectors.
+
+    For dm-inlinecrypt, this flag must be specified when <sector_size>
+    is larger than 512 bytes. The legacy 512-byte-based IV behavior is
+    not supported.
+
+    When specified, if <sector_size> is 4096 bytes, plain64 IV for the
+    second sector will be 1, and <iv_offset> must be a multiple of
+    <sector_size> (in 512-byte units).
+
+Example scripts
+===============
+Currently, dm-inlinecrypt devices must be set up directly using dmsetup.
+There is no userspace support yet to integrate dm-inlinecrypt with LUKS
+or cryptsetup. In particular, cryptsetup currently only supports
+dm-crypt, and cannot be used to create dm-inlinecrypt mappings.
+
+The following examples demonstrate how to create dm-inlinecrypt devices
+using dmsetup
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup
+	dmsetup create inlinecrypt1 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 babebabebabebabebabebabebabebabebabebabebabebabebabebabebabebabe 0 0 $1 0 1 keytype:raw"
+
+::
+
+	#!/bin/sh
+	# Create a inlinecrypt device using dmsetup when encryption key is stored in keyring service
+	dmsetup create inlinecrypt2 --table "0 `blockdev --getsz $1` inlinecrypt aes-xts-plain64 :64:logon:fde:dminlinecrypt_test_key 0 0 $1 0 1 keytype:raw"
+
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst
new file mode 100644
index 000000000..9c2130142
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst
@@ -0,0 +1,321 @@
+============
+dm-integrity
+============
+
+The dm-integrity target emulates a block device that has additional
+per-sector tags that can be used for storing integrity information.
+
+A general problem with storing integrity tags with every sector is that
+writing the sector and the integrity tag must be atomic - i.e. in case of
+crash, either both sector and integrity tag or none of them is written.
+
+To guarantee write atomicity, the dm-integrity target uses journal, it
+writes sector data and integrity tags into a journal, commits the journal
+and then copies the data and integrity tags to their respective location.
+
+The dm-integrity target can be used with the dm-crypt target - in this
+situation the dm-crypt target creates the integrity data and passes them
+to the dm-integrity target via bio_integrity_payload attached to the bio.
+In this mode, the dm-crypt and dm-integrity targets provide authenticated
+disk encryption - if the attacker modifies the encrypted device, an I/O
+error is returned instead of random data.
+
+The dm-integrity target can also be used as a standalone target, in this
+mode it calculates and verifies the integrity tag internally. In this
+mode, the dm-integrity target can be used to detect silent data
+corruption on the disk or in the I/O path.
+
+There's an alternate mode of operation where dm-integrity uses a bitmap
+instead of a journal. If a bit in the bitmap is 1, the corresponding
+region's data and integrity tags are not synchronized - if the machine
+crashes, the unsynchronized regions will be recalculated. The bitmap mode
+is faster than the journal mode, because we don't have to write the data
+twice, but it is also less reliable, because if data corruption happens
+when the machine crashes, it may not be detected.
+
+When loading the target for the first time, the kernel driver will format
+the device. But it will only format the device if the superblock contains
+zeroes. If the superblock is neither valid nor zeroed, the dm-integrity
+target can't be loaded.
+
+Accesses to the on-disk metadata area containing checksums (aka tags) are
+buffered using dm-bufio. When an access to any given metadata area
+occurs, each unique metadata area gets its own buffer(s). The buffer size
+is capped at the size of the metadata area, but may be smaller, thereby
+requiring multiple buffers to represent the full metadata area. A smaller
+buffer size will produce a smaller resulting read/write operation to the
+metadata area for small reads/writes. The metadata is still read even in
+a full write to the data covered by a single buffer.
+
+To use the target for the first time:
+
+1. overwrite the superblock with zeroes
+2. load the dm-integrity target with one-sector size, the kernel driver
+   will format the device
+3. unload the dm-integrity target
+4. read the "provided_data_sectors" value from the superblock
+5. load the dm-integrity target with the target size
+   "provided_data_sectors"
+6. if you want to use dm-integrity with dm-crypt, load the dm-crypt target
+   with the size "provided_data_sectors"
+
+
+Target arguments:
+
+1. the underlying block device
+
+2. the number of reserved sector at the beginning of the device - the
+   dm-integrity won't read of write these sectors
+
+3. the size of the integrity tag (if "-" is used, the size is taken from
+   the internal-hash algorithm)
+
+4. mode:
+
+	D - direct writes (without journal)
+		in this mode, journaling is
+		not used and data sectors and integrity tags are written
+		separately. In case of crash, it is possible that the data
+		and integrity tag doesn't match.
+	J - journaled writes
+		data and integrity tags are written to the
+		journal and atomicity is guaranteed. In case of crash,
+		either both data and tag or none of them are written. The
+		journaled mode degrades write throughput twice because the
+		data have to be written twice.
+	B - bitmap mode - data and metadata are written without any
+		synchronization, the driver maintains a bitmap of dirty
+		regions where data and metadata don't match. This mode can
+		only be used with internal hash.
+	R - recovery mode - in this mode, journal is not replayed,
+		checksums are not checked and writes to the device are not
+		allowed. This mode is useful for data recovery if the
+		device cannot be activated in any of the other standard
+		modes.
+	I - inline mode - in this mode, dm-integrity will store integrity
+		data directly in the underlying device sectors.
+		The underlying device must have an integrity profile that
+		allows storing user integrity data and provides enough
+		space for the selected integrity tag.
+
+5. the number of additional arguments
+
+Additional arguments:
+
+journal_sectors:number
+	The size of journal, this argument is used only if formatting the
+	device. If the device is already formatted, the value from the
+	superblock is used.
+
+interleave_sectors:number (default 32768)
+	The number of interleaved sectors. This values is rounded down to
+	a power of two. If the device is already formatted, the value from
+	the superblock is used.
+
+meta_device:device
+	Don't interleave the data and metadata on the device. Use a
+	separate device for metadata.
+
+buffer_sectors:number (default 128)
+	The number of sectors in one metadata buffer. The value is rounded
+	down to a power of two.
+
+journal_watermark:number (default 50)
+	The journal watermark in percents. When the size of the journal
+	exceeds this watermark, the thread that flushes the journal will
+	be started.
+
+commit_time:number (default 10000)
+	Commit time in milliseconds. When this time passes, the journal is
+	written. The journal is also written immediately if the FLUSH
+	request is received.
+
+internal_hash:algorithm(:key)	(the key is optional)
+	Use internal hash or crc.
+	When this argument is used, the dm-integrity target won't accept
+	integrity tags from the upper target, but it will automatically
+	generate and verify the integrity tags.
+
+	You can use a crc algorithm (such as crc32), then integrity target
+	will protect the data against accidental corruption.
+	You can also use a hmac algorithm (for example
+	"hmac(sha256):0123456789abcdef"), in this mode it will provide
+	cryptographic authentication of the data without encryption.
+
+	When this argument is not used, the integrity tags are accepted
+	from an upper layer target, such as dm-crypt. The upper layer
+	target should check the validity of the integrity tags.
+
+recalculate
+	Recalculate the integrity tags automatically. It is only valid
+	when using internal hash.
+
+journal_crypt:algorithm(:key)	(the key is optional)
+	Encrypt the journal using given algorithm to make sure that the
+	attacker can't read the journal. You can use a block cipher here
+	(such as "cbc(aes)") or a stream cipher (for example "chacha20"
+	or "ctr(aes)").
+
+	The journal contains history of last writes to the block device,
+	an attacker reading the journal could see the last sector numbers
+	that were written. From the sector numbers, the attacker can infer
+	the size of files that were written. To protect against this
+	situation, you can encrypt the journal.
+
+journal_mac:algorithm(:key)	(the key is optional)
+	Protect sector numbers in the journal from accidental or malicious
+	modification. To protect against accidental modification, use a
+	crc algorithm, to protect against malicious modification, use a
+	hmac algorithm with a key.
+
+	This option is not needed when using internal-hash because in this
+	mode, the integrity of journal entries is checked when replaying
+	the journal. Thus, modified sector number would be detected at
+	this stage.
+
+block_size:number (default 512)
+	The size of a data block in bytes. The larger the block size the
+	less overhead there is for per-block integrity metadata.
+	Supported values are 512, 1024, 2048 and 4096 bytes.
+
+sectors_per_bit:number
+	In the bitmap mode, this parameter specifies the number of
+	512-byte sectors that corresponds to one bitmap bit.
+
+bitmap_flush_interval:number
+	The bitmap flush interval in milliseconds. The metadata buffers
+	are synchronized when this interval expires.
+
+allow_discards
+	Allow block discard requests (a.k.a. TRIM) for the integrity device.
+	Discards are only allowed to devices using internal hash.
+
+	A discarded block is marked with a constant filler tag that anyone
+	with raw write access to the backing device can forge without the
+	key. Use allow_discards_keyed instead on new volumes.
+
+allow_discards_keyed
+	Like allow_discards, but marks a discarded block with a keyed
+	checksum of the sector number, HMAC_key(salt || sector), instead of
+	the constant filler tag, so it can't be forged without the
+	integrity key.
+
+	Not compatible with volumes that already have discarded blocks
+	marked the old way; only use on a freshly formatted volume.
+
+fix_padding
+	Use a smaller padding of the tag area that is more
+	space-efficient. If this option is not present, large padding is
+	used - that is for compatibility with older kernels.
+
+fix_hmac
+	Improve security of internal_hash and journal_mac:
+
+	- the section number is mixed to the mac, so that an attacker can't
+	  copy sectors from one journal section to another journal section
+	- the superblock is protected by journal_mac
+	- a 16-byte salt stored in the superblock is mixed to the mac, so
+	  that the attacker can't detect that two disks have the same hmac
+	  key and also to disallow the attacker to move sectors from one
+	  disk to another
+
+legacy_recalculate
+	Allow recalculating of volumes with HMAC keys. This is disabled by
+	default for security reasons - an attacker could modify the volume,
+	set recalc_sector to zero, and the kernel would not detect the
+	modification.
+
+The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and
+allow_discards can be changed when reloading the target (load an inactive
+table and swap the tables with suspend and resume). The other arguments
+should not be changed when reloading the target because the layout of disk
+data depend on them and the reloaded target would be non-functional.
+
+For example, on a device using the default interleave_sectors of 32768, a
+block_size of 512, and an internal_hash of crc32c with a tag size of 4
+bytes, it will take 128 KiB of tags to track a full data area, requiring
+256 sectors of metadata per data area. With the default buffer_sectors of
+128, that means there will be 2 buffers per metadata area, or 2 buffers
+per 16 MiB of data.
+
+Status line:
+
+1. the number of integrity mismatches
+2. provided data sectors - that is the number of sectors that the user
+   could use
+3. the current recalculating position (or '-' if we didn't recalculate)
+
+
+The layout of the formatted block device:
+
+* reserved sectors
+    (they are not used by this target, they can be used for
+    storing LUKS metadata or for other purpose), the size of the reserved
+    area is specified in the target arguments
+
+* superblock (4kiB)
+	* magic string - identifies that the device was formatted
+	* version
+	* log2(interleave sectors)
+	* integrity tag size
+	* the number of journal sections
+	* provided data sectors - the number of sectors that this target
+	  provides (i.e. the size of the device minus the size of all
+	  metadata and padding). The user of this target should not send
+	  bios that access data beyond the "provided data sectors" limit.
+	* flags
+	    SB_FLAG_HAVE_JOURNAL_MAC
+		- a flag is set if journal_mac is used
+	    SB_FLAG_RECALCULATING
+		- recalculating is in progress
+	    SB_FLAG_DIRTY_BITMAP
+		- journal area contains the bitmap of dirty
+		  blocks
+	* log2(sectors per block)
+	* a position where recalculating finished
+* journal
+	The journal is divided into sections, each section contains:
+
+	* metadata area (4kiB), it contains journal entries
+
+	  - every journal entry contains:
+
+		* logical sector (specifies where the data and tag should
+		  be written)
+		* last 8 bytes of data
+		* integrity tag (the size is specified in the superblock)
+
+	  - every metadata sector ends with
+
+		* mac (8-bytes), all the macs in 8 metadata sectors form a
+		  64-byte value. It is used to store hmac of sector
+		  numbers in the journal section, to protect against a
+		  possibility that the attacker tampers with sector
+		  numbers in the journal.
+		* commit id
+
+	* data area (the size is variable; it depends on how many journal
+	  entries fit into the metadata area)
+
+	    - every sector in the data area contains:
+
+		* data (504 bytes of data, the last 8 bytes are stored in
+		  the journal entry)
+		* commit id
+
+	To test if the whole journal section was written correctly, every
+	512-byte sector of the journal ends with 8-byte commit id. If the
+	commit id matches on all sectors in a journal section, then it is
+	assumed that the section was written correctly. If the commit id
+	doesn't match, the section was written partially and it should not
+	be replayed.
+
+* one or more runs of interleaved tags and data.
+    Each run contains:
+
+	* tag area - it contains integrity tags. There is one tag for each
+	  sector in the data area. The size of this area is always 4KiB or
+	  greater.
+	* data area - it contains data sectors. The number of data sectors
+	  in one run must be a power of two. log2 of this value is stored
+	  in the superblock.
diff --git a/Documentation/admin-guide/device-mapper/dm-io.rst b/Documentation/admin-guide/device-mapper/dm-io.rst
new file mode 100644
index 000000000..d2492917a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-io.rst
@@ -0,0 +1,75 @@
+=====
+dm-io
+=====
+
+Dm-io provides synchronous and asynchronous I/O services. There are three
+types of I/O services available, and each type has a sync and an async
+version.
+
+The user must set up an io_region structure to describe the desired location
+of the I/O. Each io_region indicates a block-device along with the starting
+sector and size of the region::
+
+   struct io_region {
+      struct block_device *bdev;
+      sector_t sector;
+      sector_t count;
+   };
+
+Dm-io can read from one io_region or write to one or more io_regions. Writes
+to multiple regions are specified by an array of io_region structures.
+
+The first I/O service type takes a list of memory pages as the data buffer for
+the I/O, along with an offset into the first page::
+
+   struct page_list {
+      struct page_list *next;
+      struct page *page;
+   };
+
+   int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
+                  struct page_list *pl, unsigned int offset,
+                  unsigned long *error_bits);
+   int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
+                   struct page_list *pl, unsigned int offset,
+                   io_notify_fn fn, void *context);
+
+The second I/O service type takes an array of bio vectors as the data buffer
+for the I/O. This service can be handy if the caller has a pre-assembled bio,
+but wants to direct different portions of the bio to different devices::
+
+   int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where,
+                       int rw, struct bio_vec *bvec,
+                       unsigned long *error_bits);
+   int dm_io_async_bvec(unsigned int num_regions, struct io_region *where,
+                        int rw, struct bio_vec *bvec,
+                        io_notify_fn fn, void *context);
+
+The third I/O service type takes a pointer to a vmalloc'd memory buffer as the
+data buffer for the I/O. This service can be handy if the caller needs to do
+I/O to a large region but doesn't want to allocate a large number of individual
+memory pages::
+
+   int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
+                     void *data, unsigned long *error_bits);
+   int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
+                      void *data, io_notify_fn fn, void *context);
+
+Callers of the asynchronous I/O services must include the name of a completion
+callback routine and a pointer to some context data for the I/O::
+
+   typedef void (*io_notify_fn)(unsigned long error, void *context);
+
+The "error" parameter in this callback, as well as the `*error` parameter in
+all of the synchronous versions, is a bitset (instead of a simple error value).
+In the case of an write-I/O to multiple regions, this bitset allows dm-io to
+indicate success or failure on each individual region.
+
+Before using any of the dm-io services, the user should call dm_io_get()
+and specify the number of pages they expect to perform I/O on concurrently.
+Dm-io will attempt to resize its mempool to make sure enough pages are
+always available in order to avoid unnecessary waiting while performing I/O.
+
+When the user is finished using the dm-io services, they should call
+dm_io_put() and specify the same number of pages that were given on the
+dm_io_get() call.
diff --git a/Documentation/admin-guide/device-mapper/dm-log.rst b/Documentation/admin-guide/device-mapper/dm-log.rst
new file mode 100644
index 000000000..ba4fce39b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-log.rst
@@ -0,0 +1,57 @@
+=====================
+Device-Mapper Logging
+=====================
+The device-mapper logging code is used by some of the device-mapper
+RAID targets to track regions of the disk that are not consistent.
+A region (or portion of the address space) of the disk may be
+inconsistent because a RAID stripe is currently being operated on or
+a machine died while the region was being altered.  In the case of
+mirrors, a region would be considered dirty/inconsistent while you
+are writing to it because the writes need to be replicated for all
+the legs of the mirror and may not reach the legs at the same time.
+Once all writes are complete, the region is considered clean again.
+
+There is a generic logging interface that the device-mapper RAID
+implementations use to perform logging operations (see
+dm_dirty_log_type in include/linux/dm-dirty-log.h).  Various different
+logging implementations are available and provide different
+capabilities.  The list includes:
+
+==============	==============================================================
+Type		Files
+==============	==============================================================
+disk		drivers/md/dm-log.c
+core		drivers/md/dm-log.c
+userspace	drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h
+==============	==============================================================
+
+The "disk" log type
+-------------------
+This log implementation commits the log state to disk.  This way, the
+logging state survives reboots/crashes.
+
+The "core" log type
+-------------------
+This log implementation keeps the log state in memory.  The log state
+will not survive a reboot or crash, but there may be a small boost in
+performance.  This method can also be used if no storage device is
+available for storing log state.
+
+The "userspace" log type
+------------------------
+This log type simply provides a way to export the log API to userspace,
+so log implementations can be done there.  This is done by forwarding most
+logging requests to userspace, where a daemon receives and processes the
+request.
+
+The structure used for communication between kernel and userspace are
+located in include/linux/dm-log-userspace.h.  Due to the frequency,
+diversity, and 2-way communication nature of the exchanges between
+kernel and userspace, 'connector' is used as the interface for
+communication.
+
+There are currently two userspace log implementations that leverage this
+framework - "clustered-disk" and "clustered-core".  These implementations
+provide a cluster-coherent log for shared-storage.  Device-mapper mirroring
+can be used in a shared-storage environment when the cluster log implementations
+are employed.
diff --git a/Documentation/admin-guide/device-mapper/dm-pcache.rst b/Documentation/admin-guide/device-mapper/dm-pcache.rst
new file mode 100644
index 000000000..09d327ef4
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-pcache.rst
@@ -0,0 +1,202 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================================
+dm-pcache — Persistent Cache
+=================================
+
+*Author: Dongsheng Yang <dongsheng.yang@linux.dev>*
+
+This document describes *dm-pcache*, a Device-Mapper target that lets a
+byte-addressable *DAX* (persistent-memory, “pmem”) region act as a
+high-performance, crash-persistent cache in front of a slower block
+device.  The code lives in `drivers/md/dm-pcache/`.
+
+Quick feature summary
+=====================
+
+* *Write-back* caching (only mode currently supported).
+* *16 MiB segments* allocated on the pmem device.
+* *Data CRC32* verification (optional, per cache).
+* Crash-safe: every metadata structure is duplicated (`PCACHE_META_INDEX_MAX
+  == 2`) and protected with CRC+sequence numbers.
+* *Multi-tree indexing* (indexing trees sharded by logical address) for high PMem parallelism
+* Pure *DAX path* I/O – no extra BIO round-trips
+* *Log-structured write-back* that preserves backend crash-consistency
+
+
+Constructor
+===========
+
+::
+
+    pcache <cache_dev> <backing_dev> [<number_of_optional_arguments> <cache_mode writeback> <data_crc true|false>]
+
+=========================  ====================================================
+``cache_dev``               Any DAX-capable block device (``/dev/pmem0``…).
+                            All metadata *and* cached blocks are stored here.
+
+``backing_dev``             The slow block device to be cached.
+
+``cache_mode``              Optional, Only ``writeback`` is accepted at the
+                            moment.
+
+``data_crc``                Optional, default to ``false``
+
+                            * ``true``  – store CRC32 for every cached entry
+			      and verify on reads
+                            * ``false`` – skip CRC (faster)
+=========================  ====================================================
+
+Example
+-------
+
+.. code-block:: shell
+
+   dmsetup create pcache_sdb --table \
+     "0 $(blockdev --getsz /dev/sdb) pcache /dev/pmem0 /dev/sdb 4 cache_mode writeback data_crc true"
+
+The first time a pmem device is used, dm-pcache formats it automatically
+(super-block, cache_info, etc.).
+
+
+Status line
+===========
+
+``dmsetup status <device>`` (``STATUSTYPE_INFO``) prints:
+
+::
+
+   <sb_flags> <seg_total> <cache_segs> <segs_used> \
+   <gc_percent> <cache_flags> \
+   <key_head_seg>:<key_head_off> \
+   <dirty_tail_seg>:<dirty_tail_off> \
+   <key_tail_seg>:<key_tail_off>
+
+Field meanings
+--------------
+
+===============================  =============================================
+``sb_flags``                     Super-block flags (e.g. endian marker).
+
+``seg_total``                    Number of physical *pmem* segments.
+
+``cache_segs``                   Number of segments used for cache.
+
+``segs_used``                    Segments currently allocated (bitmap weight).
+
+``gc_percent``                   Current GC high-water mark (0-90).
+
+``cache_flags``                  Bit 0 – DATA_CRC enabled
+                                 Bit 1 – INIT_DONE (cache initialised)
+                                 Bits 2-5 – cache mode (0 == WB).
+
+``key_head``                     Where new key-sets are being written.
+
+``dirty_tail``                   First dirty key-set that still needs
+                                 write-back to the backing device.
+
+``key_tail``                     First key-set that may be reclaimed by GC.
+===============================  =============================================
+
+
+Messages
+========
+
+*Change GC trigger*
+
+::
+
+   dmsetup message <dev> 0 gc_percent <0-90>
+
+
+Theory of operation
+===================
+
+Sub-devices
+-----------
+
+====================  =========================================================
+backing_dev             Any block device (SSD/HDD/loop/LVM, etc.).
+cache_dev               DAX device; must expose direct-access memory.
+====================  =========================================================
+
+Segments and key-sets
+---------------------
+
+* The pmem space is divided into *16 MiB segments*.
+* Each write allocates space from a per-CPU *data_head* inside a segment.
+* A *cache-key* records a logical range on the origin and where it lives
+  inside pmem (segment + offset + generation).
+* 128 keys form a *key-set* (kset); ksets are written sequentially in pmem
+  and are themselves crash-safe (CRC).
+* The pair *(key_tail, dirty_tail)* delimit clean/dirty and live/dead ksets.
+
+Write-back
+----------
+
+Dirty keys are queued into a tree; a background worker copies data
+back to the backing_dev and advances *dirty_tail*.  A FLUSH/FUA bio from the
+upper layers forces an immediate metadata commit.
+
+Garbage collection
+------------------
+
+GC starts when ``segs_used >= seg_total * gc_percent / 100``.  It walks
+from *key_tail*, frees segments whose every key has been invalidated, and
+advances *key_tail*.
+
+CRC verification
+----------------
+
+If ``data_crc is enabled`` dm-pcache computes a CRC32 over every cached data
+range when it is inserted and stores it in the on-media key.  Reads
+validate the CRC before copying to the caller.
+
+
+Failure handling
+================
+
+* *pmem media errors* – all metadata copies are read with
+  ``copy_mc_to_kernel``; an uncorrectable error logs and aborts initialisation.
+* *Cache full* – if no free segment can be found, writes return ``-EBUSY``;
+  dm-pcache retries internally (request deferral).
+* *System crash* – on attach, the driver replays ksets from *key_tail* to
+  rebuild the in-core trees; every segment’s generation guards against
+  use-after-free keys.
+
+
+Limitations & TODO
+==================
+
+* Only *write-back* mode; other modes planned.
+* Only FIFO cache invalidate; other (LRU, ARC...) planned.
+* Table reload is not supported currently.
+* Discard planned.
+
+
+Example workflow
+================
+
+.. code-block:: shell
+
+   # 1.  Create devices
+   dmsetup create pcache_sdb --table \
+     "0 $(blockdev --getsz /dev/sdb) pcache /dev/pmem0 /dev/sdb 4 cache_mode writeback data_crc true"
+
+   # 2.  Put a filesystem on top
+   mkfs.ext4 /dev/mapper/pcache_sdb
+   mount /dev/mapper/pcache_sdb /mnt
+
+   # 3.  Tune GC threshold to 80 %
+   dmsetup message pcache_sdb 0 gc_percent 80
+
+   # 4.  Observe status
+   watch -n1 'dmsetup status pcache_sdb'
+
+   # 5.  Shutdown
+   umount /mnt
+   dmsetup remove pcache_sdb
+
+
+``dm-pcache`` is under active development; feedback, bug reports and patches
+are very welcome!
diff --git a/Documentation/admin-guide/device-mapper/dm-queue-length.rst b/Documentation/admin-guide/device-mapper/dm-queue-length.rst
new file mode 100644
index 000000000..d8e381c1c
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-queue-length.rst
@@ -0,0 +1,48 @@
+===============
+dm-queue-length
+===============
+
+dm-queue-length is a path selector module for device-mapper targets,
+which selects a path with the least number of in-flight I/Os.
+The path selector name is 'queue-length'.
+
+Table parameters for each path: [<repeat_count>]
+
+::
+
+	<repeat_count>: The number of I/Os to dispatch using the selected
+			path before switching to the next path.
+			If not given, internal default is used. To check
+			the default value, see the activated table.
+
+Status for each path: <status> <fail-count> <in-flight>
+
+::
+
+	<status>: 'A' if the path is active, 'F' if the path is failed.
+	<fail-count>: The number of path failures.
+	<in-flight>: The number of in-flight I/Os on the path.
+
+
+Algorithm
+=========
+
+dm-queue-length increments/decrements 'in-flight' when an I/O is
+dispatched/completed respectively.
+dm-queue-length selects a path with the minimum 'in-flight'.
+
+
+Examples
+========
+In case that 2 paths (sda and sdb) are used with repeat_count == 128.
+
+::
+
+  # echo "0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 queue-length 0 2 1 8:0 128 8:16 128
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 1 8:0 A 0 0 8:16 A 0 0
diff --git a/Documentation/admin-guide/device-mapper/dm-raid.rst b/Documentation/admin-guide/device-mapper/dm-raid.rst
new file mode 100644
index 000000000..3780f6e6b
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-raid.rst
@@ -0,0 +1,489 @@
+=======
+dm-raid
+=======
+
+The device-mapper RAID (dm-raid) target provides a bridge from DM to MD.
+It allows the MD RAID drivers to be accessed using a device-mapper
+interface.
+
+
+Mapping Table Interface
+-----------------------
+The target is named "raid" and it accepts the following parameters::
+
+  <raid_type> <#raid_params> <raid_params> \
+    <#raid_devs> <metadata_dev0> <dev0> [.. <metadata_devN> <devN>]
+
+<raid_type>:
+
+  ============= ===============================================================
+  raid0		RAID0 striping (no resilience)
+  raid1		RAID1 mirroring
+  raid4		RAID4 with dedicated last parity disk
+  raid5_n 	RAID5 with dedicated last parity disk supporting takeover from/to raid1
+		Same as raid4
+
+		- Transitory layout for takeover from/to raid1
+  raid5_la	RAID5 left asymmetric
+
+		- rotating parity 0 with data continuation
+  raid5_ra	RAID5 right asymmetric
+
+		- rotating parity N with data continuation
+  raid5_ls	RAID5 left symmetric
+
+		- rotating parity 0 with data restart
+  raid5_rs 	RAID5 right symmetric
+
+		- rotating parity N with data restart
+  raid6_zr	RAID6 zero restart
+
+		- rotating parity zero (left-to-right) with data restart
+  raid6_nr	RAID6 N restart
+
+		- rotating parity N (right-to-left) with data restart
+  raid6_nc	RAID6 N continue
+
+		- rotating parity N (right-to-left) with data continuation
+  raid6_n_6	RAID6 with dedicate parity disks
+
+		- parity and Q-syndrome on the last 2 disks;
+		  layout for takeover from/to raid0/raid4/raid5_n
+  raid6_la_6	Same as "raid_la" plus dedicated last Q-syndrome disk supporting takeover from/to raid5
+
+		- layout for takeover from raid5_la from/to raid6
+  raid6_ra_6	Same as "raid5_ra" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_ra from/to raid6
+  raid6_ls_6	Same as "raid5_ls" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_ls from/to raid6
+  raid6_rs_6	Same as "raid5_rs" dedicated last Q-syndrome disk
+
+		- layout for takeover from raid5_rs from/to raid6
+  raid10        Various RAID10 inspired algorithms chosen by additional params
+		(see raid10_format and raid10_copies below)
+
+		- RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
+		- RAID1E: Integrated Adjacent Stripe Mirroring
+		- RAID1E: Integrated Offset Stripe Mirroring
+		- and other similar RAID10 variants
+  ============= ===============================================================
+
+  Reference: Chapter 4 of
+  https://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
+
+<#raid_params>: The number of parameters that follow.
+
+<raid_params> consists of
+
+    Mandatory parameters:
+        <chunk_size>:
+		      Chunk size in sectors.  This parameter is often known as
+		      "stripe size".  It is the only mandatory parameter and
+		      is placed first.
+
+    followed by optional parameters (in any order):
+	[sync|nosync]
+		Force or prevent RAID initialization.
+
+	[rebuild <idx>]
+		Rebuild drive number 'idx' (first drive is 0).
+
+	[daemon_sleep <ms>]
+		Interval between runs of the bitmap daemon that
+		clear bits.  A longer interval means less bitmap I/O but
+		resyncing after a failure is likely to take longer.
+
+	[min_recovery_rate <kB/sec/disk>]
+		Throttle RAID initialization
+	[max_recovery_rate <kB/sec/disk>]
+		Throttle RAID initialization
+	[write_mostly <idx>]
+		Mark drive index 'idx' write-mostly.
+	[max_write_behind <sectors>]
+		See '--write-behind=' (man mdadm)
+	[stripe_cache <sectors>]
+		Stripe cache size (RAID 4/5/6 only)
+	[region_size <sectors>]
+		The region_size multiplied by the number of regions is the
+		logical size of the array.  The bitmap records the device
+		synchronisation state for each region.
+
+        [raid10_copies   <# copies>], [raid10_format   <near|far|offset>]
+		These two options are used to alter the default layout of
+		a RAID10 configuration.  The number of copies is can be
+		specified, but the default is 2.  There are also three
+		variations to how the copies are laid down - the default
+		is "near".  Near copies are what most people think of with
+		respect to mirroring.  If these options are left unspecified,
+		or 'raid10_copies 2' and/or 'raid10_format near' are given,
+		then the layouts for 2, 3 and 4 devices	are:
+
+		========	 ==========	   ==============
+		2 drives         3 drives          4 drives
+		========	 ==========	   ==============
+		A1  A1           A1  A1  A2        A1  A1  A2  A2
+		A2  A2           A2  A3  A3        A3  A3  A4  A4
+		A3  A3           A4  A4  A5        A5  A5  A6  A6
+		A4  A4           A5  A6  A6        A7  A7  A8  A8
+		..  ..           ..  ..  ..        ..  ..  ..  ..
+		========	 ==========	   ==============
+
+		The 2-device layout is equivalent 2-way RAID1.  The 4-device
+		layout is what a traditional RAID10 would look like.  The
+		3-device layout is what might be called a 'RAID1E - Integrated
+		Adjacent Stripe Mirroring'.
+
+		If 'raid10_copies 2' and 'raid10_format far', then the layouts
+		for 2, 3 and 4 devices are:
+
+		========	     ============	  ===================
+		2 drives             3 drives             4 drives
+		========	     ============	  ===================
+		A1  A2               A1   A2   A3         A1   A2   A3   A4
+		A3  A4               A4   A5   A6         A5   A6   A7   A8
+		A5  A6               A7   A8   A9         A9   A10  A11  A12
+		..  ..               ..   ..   ..         ..   ..   ..   ..
+		A2  A1               A3   A1   A2         A2   A1   A4   A3
+		A4  A3               A6   A4   A5         A6   A5   A8   A7
+		A6  A5               A9   A7   A8         A10  A9   A12  A11
+		..  ..               ..   ..   ..         ..   ..   ..   ..
+		========	     ============	  ===================
+
+		If 'raid10_copies 2' and 'raid10_format offset', then the
+		layouts for 2, 3 and 4 devices are:
+
+		========       ==========         ================
+		2 drives       3 drives           4 drives
+		========       ==========         ================
+		A1  A2         A1  A2  A3         A1  A2  A3  A4
+		A2  A1         A3  A1  A2         A2  A1  A4  A3
+		A3  A4         A4  A5  A6         A5  A6  A7  A8
+		A4  A3         A6  A4  A5         A6  A5  A8  A7
+		A5  A6         A7  A8  A9         A9  A10 A11 A12
+		A6  A5         A9  A7  A8         A10 A9  A12 A11
+		..  ..         ..  ..  ..         ..  ..  ..  ..
+		========       ==========         ================
+
+		Here we see layouts closely akin to 'RAID1E - Integrated
+		Offset Stripe Mirroring'.
+
+        [delta_disks <N>]
+		The delta_disks option value (-251 < N < +251) triggers
+		device removal (negative value) or device addition (positive
+		value) to any reshape supporting raid levels 4/5/6 and 10.
+		RAID levels 4/5/6 allow for addition and removal of devices
+                (metadata and data device tuple), raid10_near and raid10_offset
+                only allow for device addition. raid10_far does not support any
+		reshaping at all.
+		A minimum of devices have to be kept to enforce resilience,
+		which is 3 devices for raid4/5 and 4 devices for raid6.
+
+        [data_offset <sectors>]
+		This option value defines the offset into each data device
+		where the data starts. This is used to provide out-of-place
+		reshaping space to avoid writing over data while
+		changing the layout of stripes, hence an interruption/crash
+		may happen at any time without the risk of losing data.
+		E.g. when adding devices to an existing raid set during
+		forward reshaping, the out-of-place space will be allocated
+		at the beginning of each raid device. The kernel raid4/5/6/10
+		MD personalities supporting such device addition will read the data from
+		the existing first stripes (those with smaller number of stripes)
+		starting at data_offset to fill up a new stripe with the larger
+		number of stripes, calculate the redundancy blocks (CRC/Q-syndrome)
+		and write that new stripe to offset 0. Same will be applied to all
+		N-1 other new stripes. This out-of-place scheme is used to change
+		the RAID type (i.e. the allocation algorithm) as well, e.g.
+		changing from raid5_ls to raid5_n.
+
+	[journal_dev <dev>]
+		This option adds a journal device to raid4/5/6 raid sets and
+		uses it to close the 'write hole' caused by the non-atomic updates
+		to the component devices which can cause data loss during recovery.
+		The journal device is used as writethrough thus causing writes to
+		be throttled versus non-journaled raid4/5/6 sets.
+		Takeover/reshape is not possible with a raid4/5/6 journal device;
+		it has to be deconfigured before requesting these.
+
+	[journal_mode <mode>]
+		This option sets the caching mode on journaled raid4/5/6 raid sets
+		(see 'journal_dev <dev>' above) to 'writethrough' or 'writeback'.
+		If 'writeback' is selected the journal device has to be resilient
+		and must not suffer from the 'write hole' problem itself (e.g. use
+		raid1 or raid10) to avoid a single point of failure.
+
+<#raid_devs>: The number of devices composing the array.
+	Each device consists of two entries.  The first is the device
+	containing the metadata (if any); the second is the one containing the
+	data. A Maximum of 64 metadata/data device entries are supported
+	up to target version 1.8.0.
+	1.9.0 supports up to 253 which is enforced by the used MD kernel runtime.
+
+	If a drive has failed or is missing at creation time, a '-' can be
+	given for both the metadata and data drives for a given position.
+
+
+Example Tables
+--------------
+
+::
+
+  # RAID4 - 4 data drives, 1 parity (no metadata devices)
+  # No metadata devices specified to hold superblock/bitmap info
+  # Chunk size of 1MiB
+  # (Lines separated for easy reading)
+
+  0 1960893648 raid \
+          raid4 1 2048 \
+          5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
+
+  # RAID4 - 4 data drives, 1 parity (with metadata devices)
+  # Chunk size of 1MiB, force RAID initialization,
+  #       min recovery rate at 20 kiB/sec/disk
+
+  0 1960893648 raid \
+          raid4 4 2048 sync min_recovery_rate 20 \
+          5 8:17 8:18 8:33 8:34 8:49 8:50 8:65 8:66 8:81 8:82
+
+
+Status Output
+-------------
+'dmsetup table' displays the table used to construct the mapping.
+The optional parameters are always printed in the order listed
+above with "sync" or "nosync" always output ahead of the other
+arguments, regardless of the order used when originally loading the table.
+Arguments that can be repeated are ordered by value.
+
+
+'dmsetup status' yields information on the state and health of the array.
+The output is as follows (normally a single line, but expanded here for
+clarity)::
+
+  1: <s> <l> raid \
+  2:      <raid_type> <#devices> <health_chars> \
+  3:      <sync_ratio> <sync_action> <mismatch_cnt>
+
+Line 1 is the standard output produced by device-mapper.
+
+Line 2 & 3 are produced by the raid target and are best explained by example::
+
+        0 1960893648 raid raid4 5 AAAAA 2/490221568 init 0
+
+Here we can see the RAID type is raid4, there are 5 devices - all of
+which are 'A'live, and the array is 2/490221568 complete with its initial
+recovery.  Here is a fuller description of the individual fields:
+
+	=============== =========================================================
+	<raid_type>     Same as the <raid_type> used to create the array.
+	<health_chars>  One char for each device, indicating:
+
+			- 'A' = alive and in-sync
+			- 'a' = alive but not in-sync
+			- 'D' = dead/failed.
+	<sync_ratio>    The ratio indicating how much of the array has undergone
+			the process described by 'sync_action'.  If the
+			'sync_action' is "check" or "repair", then the process
+			of "resync" or "recover" can be considered complete.
+	<sync_action>   One of the following possible states:
+
+			idle
+				- No synchronization action is being performed.
+			frozen
+				- The current action has been halted.
+			resync
+				- Array is undergoing its initial synchronization
+				  or is resynchronizing after an unclean shutdown
+				  (possibly aided by a bitmap).
+			recover
+				- A device in the array is being rebuilt or
+				  replaced.
+			check
+				- A user-initiated full check of the array is
+				  being performed.  All blocks are read and
+				  checked for consistency.  The number of
+				  discrepancies found are recorded in
+				  <mismatch_cnt>.  No changes are made to the
+				  array by this action.
+			repair
+				- The same as "check", but discrepancies are
+				  corrected.
+			reshape
+				- The array is undergoing a reshape.
+	<mismatch_cnt>  The number of discrepancies found between mirror copies
+			in RAID1/10 or wrong parity values found in RAID4/5/6.
+			This value is valid only after a "check" of the array
+			is performed.  A healthy array has a 'mismatch_cnt' of 0.
+	<data_offset>   The current data offset to the start of the user data on
+			each component device of a raid set (see the respective
+			raid parameter to support out-of-place reshaping).
+	<journal_char>	- 'A' - active write-through journal device.
+			- 'a' - active write-back journal device.
+			- 'D' - dead journal device.
+			- '-' - no journal device.
+	=============== =========================================================
+
+
+Message Interface
+-----------------
+The dm-raid target will accept certain actions through the 'message' interface.
+('man dmsetup' for more information on the message interface.)  These actions
+include:
+
+	========= ================================================
+	"idle"    Halt the current sync action.
+	"frozen"  Freeze the current sync action.
+	"resync"  Initiate/continue a resync.
+	"recover" Initiate/continue a recover process.
+	"check"   Initiate a check (i.e. a "scrub") of the array.
+	"repair"  Initiate a repair of the array.
+	========= ================================================
+
+
+Discard Support
+---------------
+The implementation of discard support among hardware vendors varies.
+When a block is discarded, some storage devices will return zeroes when
+the block is read.  These devices set the 'discard_zeroes_data'
+attribute.  Other devices will return random data.  Confusingly, some
+devices that advertise 'discard_zeroes_data' will not reliably return
+zeroes when discarded blocks are read!  Since RAID 4/5/6 uses blocks
+from a number of devices to calculate parity blocks and (for performance
+reasons) relies on 'discard_zeroes_data' being reliable, it is important
+that the devices be consistent.  Blocks may be discarded in the middle
+of a RAID 4/5/6 stripe and if subsequent read results are not
+consistent, the parity blocks may be calculated differently at any time;
+making the parity blocks useless for redundancy.  It is important to
+understand how your hardware behaves with discards if you are going to
+enable discards with RAID 4/5/6.
+
+Since the behavior of storage devices is unreliable in this respect,
+even when reporting 'discard_zeroes_data', by default RAID 4/5/6
+discard support is disabled -- this ensures data integrity at the
+expense of losing some performance.
+
+Storage devices that properly support 'discard_zeroes_data' are
+increasingly whitelisted in the kernel and can thus be trusted.
+
+For trusted devices, the following dm-raid module parameter can be set
+to safely enable discard support for RAID 4/5/6:
+
+    'devices_handle_discards_safely'
+
+
+Takeover/Reshape Support
+------------------------
+The target natively supports these two types of MDRAID conversions:
+
+o Takeover: Converts an array from one RAID level to another
+
+o Reshape: Changes the internal layout while maintaining the current RAID level
+
+Each operation is only valid under specific constraints imposed by the existing array's layout and configuration.
+
+
+Takeover:
+linear -> raid1 with N >= 2 mirrors
+raid0 -> raid4 (add dedicated parity device)
+raid0 -> raid5 (add dedicated parity device)
+raid0 -> raid10 with near layout and N >= 2 mirror groups (raid0 stripes have to become first member within mirror groups)
+raid1 -> linear
+raid1 -> raid5 with 2 mirrors
+raid4 -> raid5 w/ rotating parity
+raid5 with dedicated parity device -> raid4
+raid5 -> raid6 (with dedicated Q-syndrome)
+raid6 (with dedicated Q-syndrome) -> raid5
+raid10 with near layout and even number of disks -> raid0 (select any in-sync device from each mirror group)
+
+Reshape:
+linear: not possible
+raid0:  not possible
+raid1:  change number of mirrors
+raid4:  add and remove stripes (minimum 3), change stripesize
+raid5:  add and remove stripes (minimum 3, special case 2 for raid1 takeover), change rotating parity algorithms, change stripesize
+raid6:  add and remove stripes (minimum 4), change rotating syndrome algorithms, change stripesize
+raid10 near:   add stripes (minimum 4), change stripesize, no stripe removal possible, change to offset layout
+raid10 offset: add stripes, change stripesize, no stripe removal possible, change to near layout
+raid10 far:    not possible
+
+Table line examples:
+
+### raid1 -> raid5
+#
+# 2 devices limitation in raid1.
+# raid5 personality is able to just map 2 like raid1.
+# Reshape after takeover to change to full raid5 layout
+
+  0 1960886272 raid raid1 3 0 region_size 2048 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+# dm-0 and dm-2 are e.g. 4MiB large metadata devices, dm-1 and dm-3 have to be at least 1960886272 big.
+#
+# Table line to takeover to raid5
+
+  0 1960886272 raid raid5 3 0 region_size 2048 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+# Add required out-of-place reshape space to the beginniong of the given 2 data devices,
+# allocate another metadata/data device tuple with the same sizes for the parity space
+# and zero the first 4K of the metadata device.
+#
+# Example table of the out-of-place reshape space addition for one data device, e.g. dm-1
+
+  0 8192 linear 8:0 0 1960903888 #  <- must be free space segment
+  8192 1960886272 linear 8:0 0 2048 # previous data segment
+
+# Mapping table for e.g. raid5_rs reshape causing the size of the raid device to double-fold once the reshape finishes.
+# Check the status output (e.g. "dmsetup status $RaidDev") for progress.
+
+  0 $((2 * 1960886272)) raid raid5 7 0 region_size 2048 data_offset 8192 delta_disk 1 2 /dev/dm-0 /dev/dm-1 /dev/dm-2 /dev/dm-3
+
+
+Version History
+---------------
+
+::
+
+ 1.0.0	Initial version.  Support for RAID 4/5/6
+ 1.1.0	Added support for RAID 1
+ 1.2.0	Handle creation of arrays that contain failed devices.
+ 1.3.0	Added support for RAID 10
+ 1.3.1	Allow device replacement/rebuild for RAID 10
+ 1.3.2	Fix/improve redundancy checking for RAID10
+ 1.4.0	Non-functional change.  Removes arg from mapping function.
+ 1.4.1	RAID10 fix redundancy validation checks (commit 55ebbb5).
+ 1.4.2	Add RAID10 "far" and "offset" algorithm support.
+ 1.5.0	Add message interface to allow manipulation of the sync_action.
+	New status (STATUSTYPE_INFO) fields: sync_action and mismatch_cnt.
+ 1.5.1	Add ability to restore transiently failed devices on resume.
+ 1.5.2	'mismatch_cnt' is zero unless [last_]sync_action is "check".
+ 1.6.0	Add discard support (and devices_handle_discard_safely module param).
+ 1.7.0	Add support for MD RAID0 mappings.
+ 1.8.0	Explicitly check for compatible flags in the superblock metadata
+	and reject to start the raid set if any are set by a newer
+	target version, thus avoiding data corruption on a raid set
+	with a reshape in progress.
+ 1.9.0	Add support for RAID level takeover/reshape/region size
+	and set size reduction.
+ 1.9.1	Fix activation of existing RAID 4/10 mapped devices
+ 1.9.2	Don't emit '- -' on the status table line in case the constructor
+	fails reading a superblock. Correctly emit 'maj:min1 maj:min2' and
+	'D' on the status line.  If '- -' is passed into the constructor, emit
+	'- -' on the table line and '-' as the status line health character.
+ 1.10.0	Add support for raid4/5/6 journal device
+ 1.10.1	Fix data corruption on reshape request
+ 1.11.0	Fix table line argument order
+	(wrong raid10_copies/raid10_format sequence)
+ 1.11.1	Add raid4/5/6 journal write-back support via journal_mode option
+ 1.12.1	Fix for MD deadlock between mddev_suspend() and md_write_start() available
+ 1.13.0	Fix dev_health status at end of "recover" (was 'a', now 'A')
+ 1.13.1	Fix deadlock caused by early md_stop_writes().  Also fix size an
+	state races.
+ 1.13.2	Fix raid redundancy validation and avoid keeping raid set frozen
+ 1.14.0	Fix reshape race on small devices.  Fix stripe adding reshape
+	deadlock/potential data corruption.  Update superblock when
+	specific devices are requested via rebuild.  Fix RAID leg
+	rebuild errors.
+ 1.15.0 Fix size extensions not being synchronized in case of new MD bitmap
+        pages allocated;  also fix those not occurring after previous reductions
+ 1.15.1 Fix argument count and arguments for rebuild/write_mostly/journal_(dev|mode)
+        on the status line.
diff --git a/Documentation/admin-guide/device-mapper/dm-service-time.rst b/Documentation/admin-guide/device-mapper/dm-service-time.rst
new file mode 100644
index 000000000..facf277fc
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-service-time.rst
@@ -0,0 +1,101 @@
+===============
+dm-service-time
+===============
+
+dm-service-time is a path selector module for device-mapper targets,
+which selects a path with the shortest estimated service time for
+the incoming I/O.
+
+The service time for each path is estimated by dividing the total size
+of in-flight I/Os on a path with the performance value of the path.
+The performance value is a relative throughput value among all paths
+in a path-group, and it can be specified as a table argument.
+
+The path selector name is 'service-time'.
+
+Table parameters for each path:
+
+    [<repeat_count> [<relative_throughput>]]
+	<repeat_count>:
+			The number of I/Os to dispatch using the selected
+			path before switching to the next path.
+			If not given, internal default is used.  To check
+			the default value, see the activated table.
+	<relative_throughput>:
+			The relative throughput value of the path
+			among all paths in the path-group.
+			The valid range is 0-100.
+			If not given, minimum value '1' is used.
+			If '0' is given, the path isn't selected while
+			other paths having a positive value are available.
+
+Status for each path:
+
+    <status> <fail-count> <in-flight-size> <relative_throughput>
+	<status>:
+		'A' if the path is active, 'F' if the path is failed.
+	<fail-count>:
+		The number of path failures.
+	<in-flight-size>:
+		The size of in-flight I/Os on the path.
+	<relative_throughput>:
+		The relative throughput value of the path
+		among all paths in the path-group.
+
+
+Algorithm
+=========
+
+dm-service-time adds the I/O size to 'in-flight-size' when the I/O is
+dispatched and subtracts when completed.
+Basically, dm-service-time selects a path having minimum service time
+which is calculated by::
+
+	('in-flight-size' + 'size-of-incoming-io') / 'relative_throughput'
+
+However, some optimizations below are used to reduce the calculation
+as much as possible.
+
+	1. If the paths have the same 'relative_throughput', skip
+	   the division and just compare the 'in-flight-size'.
+
+	2. If the paths have the same 'in-flight-size', skip the division
+	   and just compare the 'relative_throughput'.
+
+	3. If some paths have non-zero 'relative_throughput' and others
+	   have zero 'relative_throughput', ignore those paths with zero
+	   'relative_throughput'.
+
+If such optimizations can't be applied, calculate service time, and
+compare service time.
+If calculated service time is equal, the path having maximum
+'relative_throughput' may be better.  So compare 'relative_throughput'
+then.
+
+
+Examples
+========
+In case that 2 paths (sda and sdb) are used with repeat_count == 128
+and sda has an average throughput 1GB/s and sdb has 4GB/s,
+'relative_throughput' value may be '1' for sda and '4' for sdb::
+
+  # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 1 8:16 128 4
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 1 8:16 A 0 0 4
+
+
+Or '2' for sda and '8' for sdb would be also true::
+
+  # echo "0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8" \
+    dmsetup create test
+  #
+  # dmsetup table
+  test: 0 10 multipath 0 0 1 1 service-time 0 2 2 8:0 128 2 8:16 128 8
+  #
+  # dmsetup status
+  test: 0 10 multipath 2 0 0 0 1 1 E 0 2 2 8:0 A 0 0 2 8:16 A 0 0 8
diff --git a/Documentation/admin-guide/device-mapper/dm-uevent.rst b/Documentation/admin-guide/device-mapper/dm-uevent.rst
new file mode 100644
index 000000000..4a8ee8d06
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-uevent.rst
@@ -0,0 +1,110 @@
+====================
+device-mapper uevent
+====================
+
+The device-mapper uevent code adds the capability to device-mapper to create
+and send kobject uevents (uevents).  Previously device-mapper events were only
+available through the ioctl interface.  The advantage of the uevents interface
+is the event contains environment attributes providing increased context for
+the event avoiding the need to query the state of the device-mapper device after
+the event is received.
+
+There are two functions currently for device-mapper events.  The first function
+listed creates the event and the second function sends the event(s)::
+
+  void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
+                      const char *path, unsigned nr_valid_paths)
+
+  void dm_send_uevents(struct list_head *events, struct kobject *kobj)
+
+
+The variables added to the uevent environment are:
+
+Variable Name: DM_TARGET
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description:
+:Value: Name of device-mapper target that generated the event.
+
+Variable Name: DM_ACTION
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description:
+:Value: Device-mapper specific action that caused the uevent action.
+	PATH_FAILED - A path has failed;
+	PATH_REINSTATED - A path has been reinstated.
+
+Variable Name: DM_SEQNUM
+------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: unsigned integer
+:Description: A sequence number for this specific device-mapper device.
+:Value: Valid unsigned integer range.
+
+Variable Name: DM_PATH
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: Major and minor number of the path device pertaining to this
+	      event.
+:Value: Path name in the form of "Major:Minor"
+
+Variable Name: DM_NR_VALID_PATHS
+--------------------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: unsigned integer
+:Description:
+:Value: Valid unsigned integer range.
+
+Variable Name: DM_NAME
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: Name of the device-mapper device.
+:Value: Name
+
+Variable Name: DM_UUID
+----------------------
+:Uevent Action(s): KOBJ_CHANGE
+:Type: string
+:Description: UUID of the device-mapper device.
+:Value: UUID. (Empty string if there isn't one.)
+
+An example of the uevents generated as captured by udevmonitor is shown
+below
+
+1.) Path failure::
+
+	UEVENT[1192521009.711215] change@/block/dm-3
+	ACTION=change
+	DEVPATH=/block/dm-3
+	SUBSYSTEM=block
+	DM_TARGET=multipath
+	DM_ACTION=PATH_FAILED
+	DM_SEQNUM=1
+	DM_PATH=8:32
+	DM_NR_VALID_PATHS=0
+	DM_NAME=mpath2
+	DM_UUID=mpath-35333333000002328
+	MINOR=3
+	MAJOR=253
+	SEQNUM=1130
+
+2.) Path reinstate::
+
+	UEVENT[1192521132.989927] change@/block/dm-3
+	ACTION=change
+	DEVPATH=/block/dm-3
+	SUBSYSTEM=block
+	DM_TARGET=multipath
+	DM_ACTION=PATH_REINSTATED
+	DM_SEQNUM=2
+	DM_PATH=8:32
+	DM_NR_VALID_PATHS=1
+	DM_NAME=mpath2
+	DM_UUID=mpath-35333333000002328
+	MINOR=3
+	MAJOR=253
+	SEQNUM=1131
diff --git a/Documentation/admin-guide/device-mapper/dm-zoned.rst b/Documentation/admin-guide/device-mapper/dm-zoned.rst
new file mode 100644
index 000000000..932383fe6
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/dm-zoned.rst
@@ -0,0 +1,194 @@
+========
+dm-zoned
+========
+
+The dm-zoned device mapper target exposes a zoned block device (ZBC and
+ZAC compliant devices) as a regular block device without any write
+pattern constraints. In effect, it implements a drive-managed zoned
+block device which hides from the user (a file system or an application
+doing raw block device accesses) the sequential write constraints of
+host-managed zoned block devices and can mitigate the potential
+device-side performance degradation due to excessive random writes on
+host-aware zoned block devices.
+
+For a more detailed description of the zoned block device models and
+their constraints see (for SCSI devices):
+
+https://www.t10.org/drafts.htm#ZBC_Family
+
+and (for ATA devices):
+
+http://www.t13.org/Documents/UploadedDocuments/docs2015/di537r05-Zoned_Device_ATA_Command_Set_ZAC.pdf
+
+The dm-zoned implementation is simple and minimizes system overhead (CPU
+and memory usage as well as storage capacity loss). For a 10TB
+host-managed disk with 256 MB zones, dm-zoned memory usage per disk
+instance is at most 4.5 MB and as little as 5 zones will be used
+internally for storing metadata and performing reclaim operations.
+
+dm-zoned target devices are formatted and checked using the dmzadm
+utility available at:
+
+https://github.com/hgst/dm-zoned-tools
+
+Algorithm
+=========
+
+dm-zoned implements an on-disk buffering scheme to handle non-sequential
+write accesses to the sequential zones of a zoned block device.
+Conventional zones are used for caching as well as for storing internal
+metadata. It can also use a regular block device together with the zoned
+block device; in that case the regular block device will be split logically
+in zones with the same size as the zoned block device. These zones will be
+placed in front of the zones from the zoned block device and will be handled
+just like conventional zones.
+
+The zones of the device(s) are separated into 2 types:
+
+1) Metadata zones: these are conventional zones used to store metadata.
+Metadata zones are not reported as usable capacity to the user.
+
+2) Data zones: all remaining zones, the vast majority of which will be
+sequential zones used exclusively to store user data. The conventional
+zones of the device may be used also for buffering user random writes.
+Data in these zones may be directly mapped to the conventional zone, but
+later moved to a sequential zone so that the conventional zone can be
+reused for buffering incoming random writes.
+
+dm-zoned exposes a logical device with a sector size of 4096 bytes,
+irrespective of the physical sector size of the backend zoned block
+device being used. This allows reducing the amount of metadata needed to
+manage valid blocks (blocks written).
+
+The on-disk metadata format is as follows:
+
+1) The first block of the first conventional zone found contains the
+super block which describes the on disk amount and position of metadata
+blocks.
+
+2) Following the super block, a set of blocks is used to describe the
+mapping of the logical device blocks. The mapping is done per chunk of
+blocks, with the chunk size equal to the zoned block device size. The
+mapping table is indexed by chunk number and each mapping entry
+indicates the zone number of the device storing the chunk of data. Each
+mapping entry may also indicate if the zone number of a conventional
+zone used to buffer random modification to the data zone.
+
+3) A set of blocks used to store bitmaps indicating the validity of
+blocks in the data zones follows the mapping table. A valid block is
+defined as a block that was written and not discarded. For a buffered
+data chunk, a block is always valid only in the data zone mapping the
+chunk or in the buffer zone of the chunk.
+
+For a logical chunk mapped to a conventional zone, all write operations
+are processed by directly writing to the zone. If the mapping zone is a
+sequential zone, the write operation is processed directly only if the
+write offset within the logical chunk is equal to the write pointer
+offset within of the sequential data zone (i.e. the write operation is
+aligned on the zone write pointer). Otherwise, write operations are
+processed indirectly using a buffer zone. In that case, an unused
+conventional zone is allocated and assigned to the chunk being
+accessed. Writing a block to the buffer zone of a chunk will
+automatically invalidate the same block in the sequential zone mapping
+the chunk. If all blocks of the sequential zone become invalid, the zone
+is freed and the chunk buffer zone becomes the primary zone mapping the
+chunk, resulting in native random write performance similar to a regular
+block device.
+
+Read operations are processed according to the block validity
+information provided by the bitmaps. Valid blocks are read either from
+the sequential zone mapping a chunk, or if the chunk is buffered, from
+the buffer zone assigned. If the accessed chunk has no mapping, or the
+accessed blocks are invalid, the read buffer is zeroed and the read
+operation terminated.
+
+After some time, the limited number of conventional zones available may
+be exhausted (all used to map chunks or buffer sequential zones) and
+unaligned writes to unbuffered chunks become impossible. To avoid this
+situation, a reclaim process regularly scans used conventional zones and
+tries to reclaim the least recently used zones by copying the valid
+blocks of the buffer zone to a free sequential zone. Once the copy
+completes, the chunk mapping is updated to point to the sequential zone
+and the buffer zone freed for reuse.
+
+Metadata Protection
+===================
+
+To protect metadata against corruption in case of sudden power loss or
+system crash, 2 sets of metadata zones are used. One set, the primary
+set, is used as the main metadata region, while the secondary set is
+used as a staging area. Modified metadata is first written to the
+secondary set and validated by updating the super block in the secondary
+set, a generation counter is used to indicate that this set contains the
+newest metadata. Once this operation completes, in place of metadata
+block updates can be done in the primary metadata set. This ensures that
+one of the set is always consistent (all modifications committed or none
+at all). Flush operations are used as a commit point. Upon reception of
+a flush request, metadata modification activity is temporarily blocked
+(for both incoming BIO processing and reclaim process) and all dirty
+metadata blocks are staged and updated. Normal operation is then
+resumed. Flushing metadata thus only temporarily delays write and
+discard requests. Read requests can be processed concurrently while
+metadata flush is being executed.
+
+If a regular device is used in conjunction with the zoned block device,
+a third set of metadata (without the zone bitmaps) is written to the
+start of the zoned block device. This metadata has a generation counter of
+'0' and will never be updated during normal operation; it just serves for
+identification purposes. The first and second copy of the metadata
+are located at the start of the regular block device.
+
+Usage
+=====
+
+A zoned block device must first be formatted using the dmzadm tool. This
+will analyze the device zone configuration, determine where to place the
+metadata sets on the device and initialize the metadata sets.
+
+Ex::
+
+	dmzadm --format /dev/sdxx
+
+
+If two drives are to be used, both devices must be specified, with the
+regular block device as the first device.
+
+Ex::
+
+	dmzadm --format /dev/sdxx /dev/sdyy
+
+
+Formatted device(s) can be started with the dmzadm utility, too.:
+
+Ex::
+
+	dmzadm --start /dev/sdxx /dev/sdyy
+
+
+Information about the internal layout and current usage of the zones can
+be obtained with the 'status' callback from dmsetup:
+
+Ex::
+
+	dmsetup status /dev/dm-X
+
+will return a line
+
+	0 <size> zoned <nr_zones> zones <nr_unmap_rnd>/<nr_rnd> random <nr_unmap_seq>/<nr_seq> sequential
+
+where <nr_zones> is the total number of zones, <nr_unmap_rnd> is the number
+of unmapped (ie free) random zones, <nr_rnd> the total number of zones,
+<nr_unmap_seq> the number of unmapped sequential zones, and <nr_seq> the
+total number of sequential zones.
+
+Normally the reclaim process will be started once there are less than 50
+percent free random zones. In order to start the reclaim process manually
+even before reaching this threshold the 'dmsetup message' function can be
+used:
+
+Ex::
+
+	dmsetup message /dev/dm-X 0 reclaim
+
+will start the reclaim process and random zones will be moved to sequential
+zones.
diff --git a/Documentation/admin-guide/device-mapper/era.rst b/Documentation/admin-guide/device-mapper/era.rst
new file mode 100644
index 000000000..90dd5c670
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/era.rst
@@ -0,0 +1,116 @@
+======
+dm-era
+======
+
+Introduction
+============
+
+dm-era is a target that behaves similar to the linear target.  In
+addition it keeps track of which blocks were written within a user
+defined period of time called an 'era'.  Each era target instance
+maintains the current era as a monotonically increasing 32-bit
+counter.
+
+Use cases include tracking changed blocks for backup software, and
+partially invalidating the contents of a cache to restore cache
+coherency after rolling back a vendor snapshot.
+
+Constructor
+===========
+
+era <metadata dev> <origin dev> <block size>
+
+ ================ ======================================================
+ metadata dev     fast device holding the persistent metadata
+ origin dev	  device holding data blocks that may change
+ block size       block size of origin data device, granularity that is
+		  tracked by the target
+ ================ ======================================================
+
+Messages
+========
+
+None of the dm messages take any arguments.
+
+checkpoint
+----------
+
+Possibly move to a new era.  You shouldn't assume the era has
+incremented.  After sending this message, you should check the
+current era via the status line.
+
+take_metadata_snap
+------------------
+
+Create a clone of the metadata, to allow a userland process to read it.
+
+drop_metadata_snap
+------------------
+
+Drop the metadata snapshot.
+
+Status
+======
+
+<metadata block size> <#used metadata blocks>/<#total metadata blocks>
+<current era> <held metadata root | '-'>
+
+========================= ==============================================
+metadata block size	  Fixed block size for each metadata block in
+			  sectors
+#used metadata blocks	  Number of metadata blocks used
+#total metadata blocks	  Total number of metadata blocks
+current era		  The current era
+held metadata root	  The location, in blocks, of the metadata root
+			  that has been 'held' for userspace read
+			  access. '-' indicates there is no held root
+========================= ==============================================
+
+Detailed use case
+=================
+
+The scenario of invalidating a cache when rolling back a vendor
+snapshot was the primary use case when developing this target:
+
+Taking a vendor snapshot
+------------------------
+
+- Send a checkpoint message to the era target
+- Make a note of the current era in its status line
+- Take vendor snapshot (the era and snapshot should be forever
+  associated now).
+
+Rolling back to an vendor snapshot
+----------------------------------
+
+- Cache enters passthrough mode (see: dm-cache's docs in cache.txt)
+- Rollback vendor storage
+- Take metadata snapshot
+- Ascertain which blocks have been written since the snapshot was taken
+  by checking each block's era
+- Invalidate those blocks in the caching software
+- Cache returns to writeback/writethrough mode
+
+Memory usage
+============
+
+The target uses a bitset to record writes in the current era.  It also
+has a spare bitset ready for switching over to a new era.  Other than
+that it uses a few 4k blocks for updating metadata::
+
+   (4 * nr_blocks) bytes + buffers
+
+Resilience
+==========
+
+Metadata is updated on disk before a write to a previously unwritten
+block is performed.  As such dm-era should not be effected by a hard
+crash such as power failure.
+
+Userland tools
+==============
+
+Userland tools are found in the increasingly poorly named
+thin-provisioning-tools project:
+
+    https://github.com/jthornber/thin-provisioning-tools
diff --git a/Documentation/admin-guide/device-mapper/index.rst b/Documentation/admin-guide/device-mapper/index.rst
new file mode 100644
index 000000000..73c1f2002
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/index.rst
@@ -0,0 +1,43 @@
+=============
+Device Mapper
+=============
+
+.. toctree::
+    :maxdepth: 1
+
+    cache-policies
+    cache
+    delay
+    dm-clone
+    dm-crypt
+    dm-dust
+    dm-ebs
+    dm-flakey
+    dm-ima
+    dm-init
+    dm-inlinecrypt
+    dm-integrity
+    dm-io
+    dm-log
+    dm-pcache
+    dm-queue-length
+    dm-raid
+    dm-service-time
+    dm-uevent
+    dm-zoned
+    era
+    kcopyd
+    linear
+    log-writes
+    persistent-data
+    snapshot
+    statistics
+    striped
+    switch
+    thin-provisioning
+    unstriped
+    vdo-design
+    vdo
+    verity
+    writecache
+    zero
diff --git a/Documentation/admin-guide/device-mapper/kcopyd.rst b/Documentation/admin-guide/device-mapper/kcopyd.rst
new file mode 100644
index 000000000..7651d3951
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/kcopyd.rst
@@ -0,0 +1,47 @@
+======
+kcopyd
+======
+
+Kcopyd provides the ability to copy a range of sectors from one block-device
+to one or more other block-devices, with an asynchronous completion
+notification. It is used by dm-snapshot and dm-mirror.
+
+Users of kcopyd must first create a client and indicate how many memory pages
+to set aside for their copy jobs. This is done with a call to
+kcopyd_client_create()::
+
+   int kcopyd_client_create(unsigned int num_pages,
+                            struct kcopyd_client **result);
+
+To start a copy job, the user must set up io_region structures to describe
+the source and destinations of the copy. Each io_region indicates a
+block-device along with the starting sector and size of the region. The source
+of the copy is given as one io_region structure, and the destinations of the
+copy are given as an array of io_region structures::
+
+   struct io_region {
+      struct block_device *bdev;
+      sector_t sector;
+      sector_t count;
+   };
+
+To start the copy, the user calls kcopyd_copy(), passing in the client
+pointer, pointers to the source and destination io_regions, the name of a
+completion callback routine, and a pointer to some context data for the copy::
+
+   int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
+                   unsigned int num_dests, struct io_region *dests,
+                   unsigned int flags, kcopyd_notify_fn fn, void *context);
+
+   typedef void (*kcopyd_notify_fn)(int read_err, unsigned int write_err,
+				    void *context);
+
+When the copy completes, kcopyd will call the user's completion routine,
+passing back the user's context pointer. It will also indicate if a read or
+write error occurred during the copy.
+
+When a user is done with all their copy jobs, they should call
+kcopyd_client_destroy() to delete the kcopyd client, which will release the
+associated memory pages::
+
+   void kcopyd_client_destroy(struct kcopyd_client *kc);
diff --git a/Documentation/admin-guide/device-mapper/linear.rst b/Documentation/admin-guide/device-mapper/linear.rst
new file mode 100644
index 000000000..9d17fc6e6
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/linear.rst
@@ -0,0 +1,63 @@
+=========
+dm-linear
+=========
+
+Device-Mapper's "linear" target maps a linear range of the Device-Mapper
+device onto a linear range of another device.  This is the basic building
+block of logical volume managers.
+
+Parameters: <dev path> <offset>
+    <dev path>:
+	Full pathname to the underlying block-device, or a
+        "major:minor" device-number.
+    <offset>:
+	Starting sector within the device.
+
+
+Example scripts
+===============
+
+::
+
+  #!/bin/sh
+  # Create an identity mapping for a device
+  echo "0 `blockdev --getsz $1` linear $1 0" | dmsetup create identity
+
+::
+
+  #!/bin/sh
+  # Join 2 devices together
+  size1=`blockdev --getsz $1`
+  size2=`blockdev --getsz $2`
+  echo "0 $size1 linear $1 0
+  $size1 $size2 linear $2 0" | dmsetup create joined
+
+::
+
+  #!/usr/bin/perl -w
+  # Split a device into 4M chunks and then join them together in reverse order.
+
+  my $name = "reverse";
+  my $extent_size = 4 * 1024 * 2;
+  my $dev = $ARGV[0];
+  my $table = "";
+  my $count = 0;
+
+  if (!defined($dev)) {
+          die("Please specify a device.\n");
+  }
+
+  my $dev_size = `blockdev --getsz $dev`;
+  my $extents = int($dev_size / $extent_size) -
+                (($dev_size % $extent_size) ? 1 : 0);
+
+  while ($extents > 0) {
+          my $this_start = $count * $extent_size;
+          $extents--;
+          $count++;
+          my $this_offset = $extents * $extent_size;
+
+          $table .= "$this_start $extent_size linear $dev $this_offset\n";
+  }
+
+  `echo \"$table\" | dmsetup create $name`;
diff --git a/Documentation/admin-guide/device-mapper/log-writes.rst b/Documentation/admin-guide/device-mapper/log-writes.rst
new file mode 100644
index 000000000..23141f2ff
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/log-writes.rst
@@ -0,0 +1,145 @@
+=============
+dm-log-writes
+=============
+
+This target takes 2 devices, one to pass all IO to normally, and one to log all
+of the write operations to.  This is intended for file system developers wishing
+to verify the integrity of metadata or data as the file system is written to.
+There is a log_write_entry written for every WRITE request and the target is
+able to take arbitrary data from userspace to insert into the log.  The data
+that is in the WRITE requests is copied into the log to make the replay happen
+exactly as it happened originally.
+
+Log Ordering
+============
+
+We log things in order of completion once we are sure the write is no longer in
+cache.  This means that normal WRITE requests are not actually logged until the
+next REQ_PREFLUSH request.  This is to make it easier for userspace to replay
+the log in a way that correlates to what is on disk and not what is in cache,
+to make it easier to detect improper waiting/flushing.
+
+This works by attaching all WRITE requests to a list once the write completes.
+Once we see a REQ_PREFLUSH request we splice this list onto the request and once
+the FLUSH request completes we log all of the WRITEs and then the FLUSH.  Only
+completed WRITEs, at the time the REQ_PREFLUSH is issued, are added in order to
+simulate the worst case scenario with regard to power failures.  Consider the
+following example (W means write, C means complete):
+
+	W1,W2,W3,C3,C2,Wflush,C1,Cflush
+
+The log would show the following:
+
+	W3,W2,flush,W1....
+
+Again this is to simulate what is actually on disk, this allows us to detect
+cases where a power failure at a particular point in time would create an
+inconsistent file system.
+
+Any REQ_FUA requests bypass this flushing mechanism and are logged as soon as
+they complete as those requests will obviously bypass the device cache.
+
+Any REQ_OP_DISCARD requests are treated like WRITE requests.  Otherwise we would
+have all the DISCARD requests, and then the WRITE requests and then the FLUSH
+request.  Consider the following example:
+
+	WRITE block 1, DISCARD block 1, FLUSH
+
+If we logged DISCARD when it completed, the replay would look like this:
+
+	DISCARD 1, WRITE 1, FLUSH
+
+which isn't quite what happened and wouldn't be caught during the log replay.
+
+Target interface
+================
+
+i) Constructor
+
+   log-writes <dev_path> <log_dev_path>
+
+   ============= ==============================================
+   dev_path	 Device that all of the IO will go to normally.
+   log_dev_path  Device where the log entries are written to.
+   ============= ==============================================
+
+ii) Status
+
+    <#logged entries> <highest allocated sector>
+
+    =========================== ========================
+    #logged entries	        Number of logged entries
+    highest allocated sector    Highest allocated sector
+    =========================== ========================
+
+iii) Messages
+
+    mark <description>
+
+	You can use a dmsetup message to set an arbitrary mark in a log.
+	For example say you want to fsck a file system after every
+	write, but first you need to replay up to the mkfs to make sure
+	we're fsck'ing something reasonable, you would do something like
+	this::
+
+	  mkfs.btrfs -f /dev/mapper/log
+	  dmsetup message log 0 mark mkfs
+	  <run test>
+
+	This would allow you to replay the log up to the mkfs mark and
+	then replay from that point on doing the fsck check in the
+	interval that you want.
+
+	Every log has a mark at the end labeled "dm-log-writes-end".
+
+Userspace component
+===================
+
+There is a userspace tool that will replay the log for you in various ways.
+It can be found here: https://github.com/josefbacik/log-writes
+
+Example usage
+=============
+
+Say you want to test fsync on your file system.  You would do something like
+this::
+
+  TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
+  dmsetup create log --table "$TABLE"
+  mkfs.btrfs -f /dev/mapper/log
+  dmsetup message log 0 mark mkfs
+
+  mount /dev/mapper/log /mnt/btrfs-test
+  <some test that does fsync at the end>
+  dmsetup message log 0 mark fsync
+  md5sum /mnt/btrfs-test/foo
+  umount /mnt/btrfs-test
+
+  dmsetup remove log
+  replay-log --log /dev/sdc --replay /dev/sdb --end-mark fsync
+  mount /dev/sdb /mnt/btrfs-test
+  md5sum /mnt/btrfs-test/foo
+  <verify md5sum's are correct>
+
+  Another option is to do a complicated file system operation and verify the file
+  system is consistent during the entire operation.  You could do this with:
+
+  TABLE="0 $(blockdev --getsz /dev/sdb) log-writes /dev/sdb /dev/sdc"
+  dmsetup create log --table "$TABLE"
+  mkfs.btrfs -f /dev/mapper/log
+  dmsetup message log 0 mark mkfs
+
+  mount /dev/mapper/log /mnt/btrfs-test
+  <fsstress to dirty the fs>
+  btrfs filesystem balance /mnt/btrfs-test
+  umount /mnt/btrfs-test
+  dmsetup remove log
+
+  replay-log --log /dev/sdc --replay /dev/sdb --end-mark mkfs
+  btrfsck /dev/sdb
+  replay-log --log /dev/sdc --replay /dev/sdb --start-mark mkfs \
+	--fsck "btrfsck /dev/sdb" --check fua
+
+And that will replay the log until it sees a FUA request, run the fsck command
+and if the fsck passes it will replay to the next FUA, until it is completed or
+the fsck command exists abnormally.
diff --git a/Documentation/admin-guide/device-mapper/persistent-data.rst b/Documentation/admin-guide/device-mapper/persistent-data.rst
new file mode 100644
index 000000000..2065c3c5a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/persistent-data.rst
@@ -0,0 +1,88 @@
+===============
+Persistent data
+===============
+
+Introduction
+============
+
+The more-sophisticated device-mapper targets require complex metadata
+that is managed in kernel.  In late 2010 we were seeing that various
+different targets were rolling their own data structures, for example:
+
+- Mikulas Patocka's multisnap implementation
+- Heinz Mauelshagen's thin provisioning target
+- Another btree-based caching target posted to dm-devel
+- Another multi-snapshot target based on a design of Daniel Phillips
+
+Maintaining these data structures takes a lot of work, so if possible
+we'd like to reduce the number.
+
+The persistent-data library is an attempt to provide a re-usable
+framework for people who want to store metadata in device-mapper
+targets.  It's currently used by the thin-provisioning target and an
+upcoming hierarchical storage target.
+
+Overview
+========
+
+The main documentation is in the header files which can all be found
+under drivers/md/persistent-data.
+
+The block manager
+-----------------
+
+dm-block-manager.[hc]
+
+This provides access to the data on disk in fixed sized-blocks.  There
+is a read/write locking interface to prevent concurrent accesses, and
+keep data that is being used in the cache.
+
+Clients of persistent-data are unlikely to use this directly.
+
+The transaction manager
+-----------------------
+
+dm-transaction-manager.[hc]
+
+This restricts access to blocks and enforces copy-on-write semantics.
+The only way you can get hold of a writable block through the
+transaction manager is by shadowing an existing block (ie. doing
+copy-on-write) or allocating a fresh one.  Shadowing is elided within
+the same transaction so performance is reasonable.  The commit method
+ensures that all data is flushed before it writes the superblock.
+On power failure your metadata will be as it was when last committed.
+
+The Space Maps
+--------------
+
+dm-space-map.h
+dm-space-map-metadata.[hc]
+dm-space-map-disk.[hc]
+
+On-disk data structures that keep track of reference counts of blocks.
+Also acts as the allocator of new blocks.  Currently two
+implementations: a simpler one for managing blocks on a different
+device (eg. thinly-provisioned data blocks); and one for managing
+the metadata space.  The latter is complicated by the need to store
+its own data within the space it's managing.
+
+The data structures
+-------------------
+
+dm-btree.[hc]
+dm-btree-remove.c
+dm-btree-spine.c
+dm-btree-internal.h
+
+Currently there is only one data structure, a hierarchical btree.
+There are plans to add more.  For example, something with an
+array-like interface would see a lot of use.
+
+The btree is 'hierarchical' in that you can define it to be composed
+of nested btrees, and take multiple keys.  For example, the
+thin-provisioning target uses a btree with two levels of nesting.
+The first maps a device id to a mapping tree, and that in turn maps a
+virtual block to a physical block.
+
+Values stored in the btrees can have arbitrary size.  Keys are always
+64bits, although nesting allows you to use multiple keys.
diff --git a/Documentation/admin-guide/device-mapper/snapshot.rst b/Documentation/admin-guide/device-mapper/snapshot.rst
new file mode 100644
index 000000000..ccdd8b587
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/snapshot.rst
@@ -0,0 +1,196 @@
+==============================
+Device-mapper snapshot support
+==============================
+
+Device-mapper allows you, without massive data copying:
+
+-  To create snapshots of any block device i.e. mountable, saved states of
+   the block device which are also writable without interfering with the
+   original content;
+-  To create device "forks", i.e. multiple different versions of the
+   same data stream.
+-  To merge a snapshot of a block device back into the snapshot's origin
+   device.
+
+In the first two cases, dm copies only the chunks of data that get
+changed and uses a separate copy-on-write (COW) block device for
+storage.
+
+For snapshot merge the contents of the COW storage are merged back into
+the origin device.
+
+
+There are three dm targets available:
+snapshot, snapshot-origin, and snapshot-merge.
+
+-  snapshot-origin <origin>
+
+which will normally have one or more snapshots based on it.
+Reads will be mapped directly to the backing device. For each write, the
+original data will be saved in the <COW device> of each snapshot to keep
+its visible content unchanged, at least until the <COW device> fills up.
+
+
+-  snapshot <origin> <COW device> <persistent?> <chunksize>
+   [<# feature args> [<arg>]*]
+
+A snapshot of the <origin> block device is created. Changed chunks of
+<chunksize> sectors will be stored on the <COW device>.  Writes will
+only go to the <COW device>.  Reads will come from the <COW device> or
+from <origin> for unchanged data.  <COW device> will often be
+smaller than the origin and if it fills up the snapshot will become
+useless and be disabled, returning errors.  So it is important to monitor
+the amount of free space and expand the <COW device> before it fills up.
+
+<persistent?> is P (Persistent) or N (Not persistent - will not survive
+after reboot).  O (Overflow) can be added as a persistent store option
+to allow userspace to advertise its support for seeing "Overflow" in the
+snapshot status.  So supported store types are "P", "PO" and "N".
+
+The difference between persistent and transient is with transient
+snapshots less metadata must be saved on disk - they can be kept in
+memory by the kernel.
+
+When loading or unloading the snapshot target, the corresponding
+snapshot-origin or snapshot-merge target must be suspended. A failure to
+suspend the origin target could result in data corruption.
+
+Optional features:
+
+   discard_zeroes_cow - a discard issued to the snapshot device that
+   maps to entire chunks to will zero the corresponding exception(s) in
+   the snapshot's exception store.
+
+   discard_passdown_origin - a discard to the snapshot device is passed
+   down to the snapshot-origin's underlying device.  This doesn't cause
+   copy-out to the snapshot exception store because the snapshot-origin
+   target is bypassed.
+
+   The discard_passdown_origin feature depends on the discard_zeroes_cow
+   feature being enabled.
+
+
+-  snapshot-merge <origin> <COW device> <persistent> <chunksize>
+   [<# feature args> [<arg>]*]
+
+takes the same table arguments as the snapshot target except it only
+works with persistent snapshots.  This target assumes the role of the
+"snapshot-origin" target and must not be loaded if the "snapshot-origin"
+is still present for <origin>.
+
+Creates a merging snapshot that takes control of the changed chunks
+stored in the <COW device> of an existing snapshot, through a handover
+procedure, and merges these chunks back into the <origin>.  Once merging
+has started (in the background) the <origin> may be opened and the merge
+will continue while I/O is flowing to it.  Changes to the <origin> are
+deferred until the merging snapshot's corresponding chunk(s) have been
+merged.  Once merging has started the snapshot device, associated with
+the "snapshot" target, will return -EIO when accessed.
+
+
+How snapshot is used by LVM2
+============================
+When you create the first LVM2 snapshot of a volume, four dm devices are used:
+
+1) a device containing the original mapping table of the source volume;
+2) a device used as the <COW device>;
+3) a "snapshot" device, combining #1 and #2, which is the visible snapshot
+   volume;
+4) the "original" volume (which uses the device number used by the original
+   source volume), whose table is replaced by a "snapshot-origin" mapping
+   from device #1.
+
+A fixed naming scheme is used, so with the following commands::
+
+  lvcreate -L 1G -n base volumeGroup
+  lvcreate -L 100M --snapshot -n snap volumeGroup/base
+
+we'll have this situation (with volumes in above order)::
+
+  # dmsetup table|grep volumeGroup
+
+  volumeGroup-base-real: 0 2097152 linear 8:19 384
+  volumeGroup-snap-cow: 0 204800 linear 8:19 2097536
+  volumeGroup-snap: 0 2097152 snapshot 254:11 254:12 P 16
+  volumeGroup-base: 0 2097152 snapshot-origin 254:11
+
+  # ls -lL /dev/mapper/volumeGroup-*
+  brw-------  1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
+  brw-------  1 root root 254, 12 29 ago 18:15 /dev/mapper/volumeGroup-snap-cow
+  brw-------  1 root root 254, 13 29 ago 18:15 /dev/mapper/volumeGroup-snap
+  brw-------  1 root root 254, 10 29 ago 18:14 /dev/mapper/volumeGroup-base
+
+
+How snapshot-merge is used by LVM2
+==================================
+A merging snapshot assumes the role of the "snapshot-origin" while
+merging.  As such the "snapshot-origin" is replaced with
+"snapshot-merge".  The "-real" device is not changed and the "-cow"
+device is renamed to <origin name>-cow to aid LVM2's cleanup of the
+merging snapshot after it completes.  The "snapshot" that hands over its
+COW device to the "snapshot-merge" is deactivated (unless using lvchange
+--refresh); but if it is left active it will simply return I/O errors.
+
+A snapshot will merge into its origin with the following command::
+
+  lvconvert --merge volumeGroup/snap
+
+we'll now have this situation::
+
+  # dmsetup table|grep volumeGroup
+
+  volumeGroup-base-real: 0 2097152 linear 8:19 384
+  volumeGroup-base-cow: 0 204800 linear 8:19 2097536
+  volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16
+
+  # ls -lL /dev/mapper/volumeGroup-*
+  brw-------  1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real
+  brw-------  1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow
+  brw-------  1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base
+
+
+How to determine when a merging is complete
+===========================================
+The snapshot-merge and snapshot status lines end with:
+
+  <sectors_allocated>/<total_sectors> <metadata_sectors>
+
+Both <sectors_allocated> and <total_sectors> include both data and metadata.
+During merging, the number of sectors allocated gets smaller and
+smaller.  Merging has finished when the number of sectors holding data
+is zero, in other words <sectors_allocated> == <metadata_sectors>.
+
+Here is a practical example (using a hybrid of lvm and dmsetup commands)::
+
+  # lvs
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup owi-a- 4.00g
+    snap    volumeGroup swi-a- 1.00g base  18.97
+
+  # dmsetup status volumeGroup-snap
+  0 8388608 snapshot 397896/2097152 1560
+                                    ^^^^ metadata sectors
+
+  # lvconvert --merge -b volumeGroup/snap
+    Merging of volume snap started.
+
+  # lvs volumeGroup/snap
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup Owi-a- 4.00g          17.23
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 281688/2097152 1104
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 180480/2097152 712
+
+  # dmsetup status volumeGroup-base
+  0 8388608 snapshot-merge 16/2097152 16
+
+Merging has finished.
+
+::
+
+  # lvs
+    LV      VG          Attr   LSize Origin  Snap%  Move Log Copy%  Convert
+    base    volumeGroup owi-a- 4.00g
diff --git a/Documentation/admin-guide/device-mapper/statistics.rst b/Documentation/admin-guide/device-mapper/statistics.rst
new file mode 100644
index 000000000..41ded0bc5
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/statistics.rst
@@ -0,0 +1,225 @@
+=============
+DM statistics
+=============
+
+Device Mapper supports the collection of I/O statistics on user-defined
+regions of a DM device.	 If no regions are defined no statistics are
+collected so there isn't any performance impact.  Only bio-based DM
+devices are currently supported.
+
+Each user-defined region specifies a starting sector, length and step.
+Individual statistics will be collected for each step-sized area within
+the range specified.
+
+The I/O statistics counters for each step-sized area of a region are
+in the same format as `/sys/block/*/stat` or `/proc/diskstats` (see:
+Documentation/admin-guide/iostats.rst).  But two extra counters (12 and 13) are
+provided: total time spent reading and writing.  When the histogram
+argument is used, the 14th parameter is reported that represents the
+histogram of latencies.  All these counters may be accessed by sending
+the @stats_print message to the appropriate DM device via dmsetup.
+
+The reported times are in milliseconds and the granularity depends on
+the kernel ticks.  When the option precise_timestamps is used, the
+reported times are in nanoseconds.
+
+Each region has a corresponding unique identifier, which we call a
+region_id, that is assigned when the region is created.	 The region_id
+must be supplied when querying statistics about the region, deleting the
+region, etc.  Unique region_ids enable multiple userspace programs to
+request and process statistics for the same DM device without stepping
+on each other's data.
+
+The creation of DM statistics will allocate memory via kmalloc or
+fallback to using vmalloc space.  At most, 1/4 of the overall system
+memory may be allocated by DM statistics.  The admin can see how much
+memory is used by reading:
+
+	/sys/module/dm_mod/parameters/stats_current_allocated_bytes
+
+Messages
+========
+
+    @stats_create <range> <step> [<number_of_optional_arguments> <optional_arguments>...] [<program_id> [<aux_data>]]
+	Create a new region and return the region_id.
+
+	<range>
+	  "-"
+		whole device
+	  "<start_sector>+<length>"
+		a range of <length> 512-byte sectors
+		starting with <start_sector>.
+
+	<step>
+	  "<area_size>"
+		the range is subdivided into areas each containing
+		<area_size> sectors.
+	  "/<number_of_areas>"
+		the range is subdivided into the specified
+		number of areas.
+
+	<number_of_optional_arguments>
+	  The number of optional arguments
+
+	<optional_arguments>
+	  The following optional arguments are supported:
+
+	  precise_timestamps
+		use precise timer with nanosecond resolution
+		instead of the "jiffies" variable.  When this argument is
+		used, the resulting times are in nanoseconds instead of
+		milliseconds.  Precise timestamps are a little bit slower
+		to obtain than jiffies-based timestamps.
+	  histogram:n1,n2,n3,n4,...
+		collect histogram of latencies.  The
+		numbers n1, n2, etc are times that represent the boundaries
+		of the histogram.  If precise_timestamps is not used, the
+		times are in milliseconds, otherwise they are in
+		nanoseconds.  For each range, the kernel will report the
+		number of requests that completed within this range. For
+		example, if we use "histogram:10,20,30", the kernel will
+		report four numbers a:b:c:d. a is the number of requests
+		that took 0-10 ms to complete, b is the number of requests
+		that took 10-20 ms to complete, c is the number of requests
+		that took 20-30 ms to complete and d is the number of
+		requests that took more than 30 ms to complete.
+
+	<program_id>
+	  An optional parameter.  A name that uniquely identifies
+	  the userspace owner of the range.  This groups ranges together
+	  so that userspace programs can identify the ranges they
+	  created and ignore those created by others.
+	  The kernel returns this string back in the output of
+	  @stats_list message, but it doesn't use it for anything else.
+	  If we omit the number of optional arguments, program id must not
+	  be a number, otherwise it would be interpreted as the number of
+	  optional arguments.
+
+	<aux_data>
+	  An optional parameter.  A word that provides auxiliary data
+	  that is useful to the client program that created the range.
+	  The kernel returns this string back in the output of
+	  @stats_list message, but it doesn't use this value for anything.
+
+    @stats_delete <region_id>
+	Delete the region with the specified id.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+    @stats_clear <region_id>
+	Clear all the counters except the in-flight i/o counters.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+    @stats_list [<program_id>]
+	List all regions registered with @stats_create.
+
+	<program_id>
+	  An optional parameter.
+	  If this parameter is specified, only matching regions
+	  are returned.
+	  If it is not specified, all regions are returned.
+
+	Output format:
+	  <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
+	        precise_timestamps histogram:n1,n2,n3,...
+
+	The strings "precise_timestamps" and "histogram" are printed only
+	if they were specified when creating the region.
+
+    @stats_print <region_id> [<starting_line> <number_of_lines>]
+	Print counters for each step-sized area of a region.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<starting_line>
+	  The index of the starting line in the output.
+	  If omitted, all lines are returned.
+
+	<number_of_lines>
+	  The number of lines to include in the output.
+	  If omitted, all lines are returned.
+
+	Output format for each step-sized area of a region:
+
+	  <start_sector>+<length>
+		counters
+
+	  The first 11 counters have the same meaning as
+	  `/sys/block/*/stat or /proc/diskstats`.
+
+	  Please refer to Documentation/admin-guide/iostats.rst for details.
+
+	  1. the number of reads completed
+	  2. the number of reads merged
+	  3. the number of sectors read
+	  4. the number of milliseconds spent reading
+	  5. the number of writes completed
+	  6. the number of writes merged
+	  7. the number of sectors written
+	  8. the number of milliseconds spent writing
+	  9. the number of I/Os currently in progress
+	  10. the number of milliseconds spent doing I/Os
+	  11. the weighted number of milliseconds spent doing I/Os
+
+	  Additional counters:
+
+	  12. the total time spent reading in milliseconds
+	  13. the total time spent writing in milliseconds
+
+    @stats_print_clear <region_id> [<starting_line> <number_of_lines>]
+	Atomically print and then clear all the counters except the
+	in-flight i/o counters.	 Useful when the client consuming the
+	statistics does not want to lose any statistics (those updated
+	between printing and clearing).
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<starting_line>
+	  The index of the starting line in the output.
+	  If omitted, all lines are printed and then cleared.
+
+	<number_of_lines>
+	  The number of lines to process.
+	  If omitted, all lines are printed and then cleared.
+
+    @stats_set_aux <region_id> <aux_data>
+	Store auxiliary data aux_data for the specified region.
+
+	<region_id>
+	  region_id returned from @stats_create
+
+	<aux_data>
+	  The string that identifies data which is useful to the client
+	  program that created the range.  The kernel returns this
+	  string back in the output of @stats_list message, but it
+	  doesn't use this value for anything.
+
+Examples
+========
+
+Subdivide the DM device 'vol' into 100 pieces and start collecting
+statistics on them::
+
+  dmsetup message vol 0 @stats_create - /100
+
+Set the auxiliary data string to "foo bar baz" (the escape for each
+space must also be escaped, otherwise the shell will consume them)::
+
+  dmsetup message vol 0 @stats_set_aux 0 foo\\ bar\\ baz
+
+List the statistics::
+
+  dmsetup message vol 0 @stats_list
+
+Print the statistics::
+
+  dmsetup message vol 0 @stats_print 0
+
+Delete the statistics::
+
+  dmsetup message vol 0 @stats_delete 0
diff --git a/Documentation/admin-guide/device-mapper/striped.rst b/Documentation/admin-guide/device-mapper/striped.rst
new file mode 100644
index 000000000..e9a8da192
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/striped.rst
@@ -0,0 +1,61 @@
+=========
+dm-stripe
+=========
+
+Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)
+device across one or more underlying devices. Data is written in "chunks",
+with consecutive chunks rotating among the underlying devices. This can
+potentially provide improved I/O throughput by utilizing several physical
+devices in parallel.
+
+Parameters: <num devs> <chunk size> [<dev path> <offset>]+
+    <num devs>:
+	Number of underlying devices.
+    <chunk size>:
+	Size of each chunk of data. Must be at least as
+        large as the system's PAGE_SIZE.
+    <dev path>:
+	Full pathname to the underlying block-device, or a
+	"major:minor" device-number.
+    <offset>:
+	Starting sector within the device.
+
+One or more underlying devices can be specified. The striped device size must
+be a multiple of the chunk size multiplied by the number of underlying devices.
+
+
+Example scripts
+===============
+
+::
+
+  #!/usr/bin/perl -w
+  # Create a striped device across any number of underlying devices. The device
+  # will be called "stripe_dev" and have a chunk-size of 128k.
+
+  my $chunk_size = 128 * 2;
+  my $dev_name = "stripe_dev";
+  my $num_devs = @ARGV;
+  my @devs = @ARGV;
+  my ($min_dev_size, $stripe_dev_size, $i);
+
+  if (!$num_devs) {
+          die("Specify at least one device\n");
+  }
+
+  $min_dev_size = `blockdev --getsz $devs[0]`;
+  for ($i = 1; $i < $num_devs; $i++) {
+          my $this_size = `blockdev --getsz $devs[$i]`;
+          $min_dev_size = ($min_dev_size < $this_size) ?
+                          $min_dev_size : $this_size;
+  }
+
+  $stripe_dev_size = $min_dev_size * $num_devs;
+  $stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);
+
+  $table = "0 $stripe_dev_size striped $num_devs $chunk_size";
+  for ($i = 0; $i < $num_devs; $i++) {
+          $table .= " $devs[$i] 0";
+  }
+
+  `echo $table | dmsetup create $dev_name`;
diff --git a/Documentation/admin-guide/device-mapper/switch.rst b/Documentation/admin-guide/device-mapper/switch.rst
new file mode 100644
index 000000000..7dde06be1
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/switch.rst
@@ -0,0 +1,141 @@
+=========
+dm-switch
+=========
+
+The device-mapper switch target creates a device that supports an
+arbitrary mapping of fixed-size regions of I/O across a fixed set of
+paths.  The path used for any specific region can be switched
+dynamically by sending the target a message.
+
+It maps I/O to underlying block devices efficiently when there is a large
+number of fixed-sized address regions but there is no simple pattern
+that would allow for a compact representation of the mapping such as
+dm-stripe.
+
+Background
+----------
+
+Dell EqualLogic and some other iSCSI storage arrays use a distributed
+frameless architecture.  In this architecture, the storage group
+consists of a number of distinct storage arrays ("members") each having
+independent controllers, disk storage and network adapters.  When a LUN
+is created it is spread across multiple members.  The details of the
+spreading are hidden from initiators connected to this storage system.
+The storage group exposes a single target discovery portal, no matter
+how many members are being used.  When iSCSI sessions are created, each
+session is connected to an eth port on a single member.  Data to a LUN
+can be sent on any iSCSI session, and if the blocks being accessed are
+stored on another member the I/O will be forwarded as required.  This
+forwarding is invisible to the initiator.  The storage layout is also
+dynamic, and the blocks stored on disk may be moved from member to
+member as needed to balance the load.
+
+This architecture simplifies the management and configuration of both
+the storage group and initiators.  In a multipathing configuration, it
+is possible to set up multiple iSCSI sessions to use multiple network
+interfaces on both the host and target to take advantage of the
+increased network bandwidth.  An initiator could use a simple round
+robin algorithm to send I/O across all paths and let the storage array
+members forward it as necessary, but there is a performance advantage to
+sending data directly to the correct member.
+
+A device-mapper table already lets you map different regions of a
+device onto different targets.  However in this architecture the LUN is
+spread with an address region size on the order of 10s of MBs, which
+means the resulting table could have more than a million entries and
+consume far too much memory.
+
+Using this device-mapper switch target we can now build a two-layer
+device hierarchy:
+
+    Upper Tier - Determine which array member the I/O should be sent to.
+    Lower Tier - Load balance amongst paths to a particular member.
+
+The lower tier consists of a single dm multipath device for each member.
+Each of these multipath devices contains the set of paths directly to
+the array member in one priority group, and leverages existing path
+selectors to load balance amongst these paths.  We also build a
+non-preferred priority group containing paths to other array members for
+failover reasons.
+
+The upper tier consists of a single dm-switch device.  This device uses
+a bitmap to look up the location of the I/O and choose the appropriate
+lower tier device to route the I/O.  By using a bitmap we are able to
+use 4 bits for each address range in a 16 member group (which is very
+large for us).  This is a much denser representation than the dm table
+b-tree can achieve.
+
+Construction Parameters
+=======================
+
+    <num_paths> <region_size> <num_optional_args> [<optional_args>...] [<dev_path> <offset>]+
+	<num_paths>
+	    The number of paths across which to distribute the I/O.
+
+	<region_size>
+	    The number of 512-byte sectors in a region. Each region can be redirected
+	    to any of the available paths.
+
+	<num_optional_args>
+	    The number of optional arguments. Currently, no optional arguments
+	    are supported and so this must be zero.
+
+	<dev_path>
+	    The block device that represents a specific path to the device.
+
+	<offset>
+	    The offset of the start of data on the specific <dev_path> (in units
+	    of 512-byte sectors). This number is added to the sector number when
+	    forwarding the request to the specific path. Typically it is zero.
+
+Messages
+========
+
+set_region_mappings <index>:<path_nr> [<index>]:<path_nr> [<index>]:<path_nr>...
+
+Modify the region table by specifying which regions are redirected to
+which paths.
+
+<index>
+    The region number (region size was specified in constructor parameters).
+    If index is omitted, the next region (previous index + 1) is used.
+    Expressed in hexadecimal (WITHOUT any prefix like 0x).
+
+<path_nr>
+    The path number in the range 0 ... (<num_paths> - 1).
+    Expressed in hexadecimal (WITHOUT any prefix like 0x).
+
+R<n>,<m>
+    This parameter allows repetitive patterns to be loaded quickly. <n> and <m>
+    are hexadecimal numbers. The last <n> mappings are repeated in the next <m>
+    slots.
+
+Status
+======
+
+No status line is reported.
+
+Example
+=======
+
+Assume that you have volumes vg1/switch0 vg1/switch1 vg1/switch2 with
+the same size.
+
+Create a switch device with 64kB region size::
+
+    dmsetup create switch --table "0 `blockdev --getsz /dev/vg1/switch0`
+	switch 3 128 0 /dev/vg1/switch0 0 /dev/vg1/switch1 0 /dev/vg1/switch2 0"
+
+Set mappings for the first 7 entries to point to devices switch0, switch1,
+switch2, switch0, switch1, switch2, switch1::
+
+    dmsetup message switch 0 set_region_mappings 0:0 :1 :2 :0 :1 :2 :1
+
+Set repetitive mapping. This command::
+
+    dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10
+
+is equivalent to::
+
+    dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \
+	:1 :2 :1 :2 :1 :2 :1 :2 :1 :2
diff --git a/Documentation/admin-guide/device-mapper/thin-provisioning.rst b/Documentation/admin-guide/device-mapper/thin-provisioning.rst
new file mode 100644
index 000000000..b2fa49a56
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/thin-provisioning.rst
@@ -0,0 +1,427 @@
+=================
+Thin provisioning
+=================
+
+Introduction
+============
+
+This document describes a collection of device-mapper targets that
+between them implement thin-provisioning and snapshots.
+
+The main highlight of this implementation, compared to the previous
+implementation of snapshots, is that it allows many virtual devices to
+be stored on the same data volume.  This simplifies administration and
+allows the sharing of data between volumes, thus reducing disk usage.
+
+Another significant feature is support for an arbitrary depth of
+recursive snapshots (snapshots of snapshots of snapshots ...).  The
+previous implementation of snapshots did this by chaining together
+lookup tables, and so performance was O(depth).  This new
+implementation uses a single data structure to avoid this degradation
+with depth.  Fragmentation may still be an issue, however, in some
+scenarios.
+
+Metadata is stored on a separate device from data, giving the
+administrator some freedom, for example to:
+
+- Improve metadata resilience by storing metadata on a mirrored volume
+  but data on a non-mirrored one.
+
+- Improve performance by storing the metadata on SSD.
+
+Status
+======
+
+These targets are considered safe for production use.  But different use
+cases will have different performance characteristics, for example due
+to fragmentation of the data volume.
+
+If you find this software is not performing as expected please mail
+dm-devel@redhat.com with details and we'll try our best to improve
+things for you.
+
+Userspace tools for checking and repairing the metadata have been fully
+developed and are available as 'thin_check' and 'thin_repair'.  The name
+of the package that provides these utilities varies by distribution (on
+a Red Hat distribution it is named 'device-mapper-persistent-data').
+
+Cookbook
+========
+
+This section describes some quick recipes for using thin provisioning.
+They use the dmsetup program to control the device-mapper driver
+directly.  End users will be advised to use a higher-level volume
+manager such as LVM2 once support has been added.
+
+Pool device
+-----------
+
+The pool device ties together the metadata volume and the data volume.
+It maps I/O linearly to the data volume and updates the metadata via
+two mechanisms:
+
+- Function calls from the thin targets
+
+- Device-mapper 'messages' from userspace which control the creation of new
+  virtual devices amongst other things.
+
+Setting up a fresh pool device
+------------------------------
+
+Setting up a pool device requires a valid metadata device, and a
+data device.  If you do not have an existing metadata device you can
+make one by zeroing the first 4k to indicate empty metadata.
+
+    dd if=/dev/zero of=$metadata_dev bs=4096 count=1
+
+The amount of metadata you need will vary according to how many blocks
+are shared between thin devices (i.e. through snapshots).  If you have
+less sharing than average you'll need a larger-than-average metadata device.
+
+As a guide, we suggest you calculate the number of bytes to use in the
+metadata device as 48 * $data_dev_size / $data_block_size but round it up
+to 2MiB if the answer is smaller.  If you're creating large numbers of
+snapshots which are recording large amounts of change, you may find you
+need to increase this.
+
+The largest size supported is 16GiB: If the device is larger,
+a warning will be issued and the excess space will not be used.
+
+Reloading a pool table
+----------------------
+
+You may reload a pool's table, indeed this is how the pool is resized
+if it runs out of space.  (N.B. While specifying a different metadata
+device when reloading is not forbidden at the moment, things will go
+wrong if it does not route I/O to exactly the same on-disk location as
+previously.)
+
+Using an existing pool device
+-----------------------------
+
+::
+
+    dmsetup create pool \
+	--table "0 20971520 thin-pool $metadata_dev $data_dev \
+		 $data_block_size $low_water_mark"
+
+$data_block_size gives the smallest unit of disk space that can be
+allocated at a time expressed in units of 512-byte sectors.
+$data_block_size must be between 128 (64KiB) and 2097152 (1GiB) and a
+multiple of 128 (64KiB).  $data_block_size cannot be changed after the
+thin-pool is created.  People primarily interested in thin provisioning
+may want to use a value such as 1024 (512KiB).  People doing lots of
+snapshotting may want a smaller value such as 128 (64KiB).  If you are
+not zeroing newly-allocated data, a larger $data_block_size in the
+region of 262144 (128MiB) is suggested.
+
+$low_water_mark is expressed in blocks of size $data_block_size.  If
+free space on the data device drops below this level then a dm event
+will be triggered which a userspace daemon should catch allowing it to
+extend the pool device.  Only one such event will be sent.
+
+No special event is triggered if a just resumed device's free space is below
+the low water mark. However, resuming a device always triggers an
+event; a userspace daemon should verify that free space exceeds the low
+water mark when handling this event.
+
+A low water mark for the metadata device is maintained in the kernel and
+will trigger a dm event if free space on the metadata device drops below
+it.
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the thin-provisioning target behaves like a physical disk that has
+a volatile write cache.  If power is lost you may lose some recent
+writes.  The metadata should always be consistent in spite of any crash.
+
+If data space is exhausted the pool will either error or queue IO
+according to the configuration (see: error_if_no_space).  If metadata
+space is exhausted or a metadata operation fails: the pool will error IO
+until the pool is taken offline and repair is performed to 1) fix any
+potential inconsistencies and 2) clear the flag that imposes repair.
+Once the pool's metadata device is repaired it may be resized, which
+will allow the pool to return to normal operation.  Note that if a pool
+is flagged as needing repair, the pool's data and metadata devices
+cannot be resized until repair is performed.  It should also be noted
+that when the pool's metadata space is exhausted the current metadata
+transaction is aborted.  Given that the pool will cache IO whose
+completion may have already been acknowledged to upper IO layers
+(e.g. filesystem) it is strongly suggested that consistency checks
+(e.g. fsck) be performed on those layers when repair of the pool is
+required.
+
+Thin provisioning
+-----------------
+
+i) Creating a new thinly-provisioned volume.
+
+  To create a new thinly- provisioned volume you must send a message to an
+  active pool device, /dev/mapper/pool in this example::
+
+    dmsetup message /dev/mapper/pool 0 "create_thin 0"
+
+  Here '0' is an identifier for the volume, a 24-bit number.  It's up
+  to the caller to allocate and manage these identifiers.  If the
+  identifier is already in use, the message will fail with -EEXIST.
+
+ii) Using a thinly-provisioned volume.
+
+  Thinly-provisioned volumes are activated using the 'thin' target::
+
+    dmsetup create thin --table "0 2097152 thin /dev/mapper/pool 0"
+
+  The last parameter is the identifier for the thinp device.
+
+Internal snapshots
+------------------
+
+i) Creating an internal snapshot.
+
+  Snapshots are created with another message to the pool.
+
+  N.B.  If the origin device that you wish to snapshot is active, you
+  must suspend it before creating the snapshot to avoid corruption.
+  This is NOT enforced at the moment, so please be careful!
+
+  ::
+
+    dmsetup suspend /dev/mapper/thin
+    dmsetup message /dev/mapper/pool 0 "create_snap 1 0"
+    dmsetup resume /dev/mapper/thin
+
+  Here '1' is the identifier for the volume, a 24-bit number.  '0' is the
+  identifier for the origin device.
+
+ii) Using an internal snapshot.
+
+  Once created, the user doesn't have to worry about any connection
+  between the origin and the snapshot.  Indeed the snapshot is no
+  different from any other thinly-provisioned device and can be
+  snapshotted itself via the same method.  It's perfectly legal to
+  have only one of them active, and there's no ordering requirement on
+  activating or removing them both.  (This differs from conventional
+  device-mapper snapshots.)
+
+  Activate it exactly the same way as any other thinly-provisioned volume::
+
+    dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 1"
+
+External snapshots
+------------------
+
+You can use an external **read only** device as an origin for a
+thinly-provisioned volume.  Any read to an unprovisioned area of the
+thin device will be passed through to the origin.  Writes trigger
+the allocation of new blocks as usual.
+
+One use case for this is VM hosts that want to run guests on
+thinly-provisioned volumes but have the base image on another device
+(possibly shared between many VMs).
+
+You must not write to the origin device if you use this technique!
+Of course, you may write to the thin device and take internal snapshots
+of the thin volume.
+
+i) Creating a snapshot of an external device
+
+  This is the same as creating a thin device.
+  You don't mention the origin at this stage.
+
+  ::
+
+    dmsetup message /dev/mapper/pool 0 "create_thin 0"
+
+ii) Using a snapshot of an external device.
+
+  Append an extra parameter to the thin target specifying the origin::
+
+    dmsetup create snap --table "0 2097152 thin /dev/mapper/pool 0 /dev/image"
+
+  N.B. All descendants (internal snapshots) of this snapshot require the
+  same extra origin parameter.
+
+Deactivation
+------------
+
+All devices using a pool must be deactivated before the pool itself
+can be.
+
+::
+
+    dmsetup remove thin
+    dmsetup remove snap
+    dmsetup remove pool
+
+Reference
+=========
+
+'thin-pool' target
+------------------
+
+i) Constructor
+
+    ::
+
+      thin-pool <metadata dev> <data dev> <data block size (sectors)> \
+	        <low water mark (blocks)> [<number of feature args> [<arg>]*]
+
+    Optional feature arguments:
+
+      skip_block_zeroing:
+	Skip the zeroing of newly-provisioned blocks.
+
+      ignore_discard:
+	Disable discard support.
+
+      no_discard_passdown:
+	Don't pass discards down to the underlying
+	data device, but just remove the mapping.
+
+      read_only:
+		 Don't allow any changes to be made to the pool
+		 metadata.  This mode is only available after the
+		 thin-pool has been created and first used in full
+		 read/write mode.  It cannot be specified on initial
+		 thin-pool creation.
+
+      error_if_no_space:
+	Error IOs, instead of queueing, if no space.
+
+    Data block size must be between 64KiB (128 sectors) and 1GiB
+    (2097152 sectors) inclusive.
+
+
+ii) Status
+
+    ::
+
+      <transaction id> <used metadata blocks>/<total metadata blocks>
+      <used data blocks>/<total data blocks> <held metadata root>
+      ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space
+      needs_check|- metadata_low_watermark
+
+    transaction id:
+	A 64-bit number used by userspace to help synchronise with metadata
+	from volume managers.
+
+    used data blocks / total data blocks
+	If the number of free blocks drops below the pool's low water mark a
+	dm event will be sent to userspace.  This event is edge-triggered and
+	it will occur only once after each resume so volume manager writers
+	should register for the event and then check the target's status.
+
+    held metadata root:
+	The location, in blocks, of the metadata root that has been
+	'held' for userspace read access.  '-' indicates there is no
+	held root.
+
+    discard_passdown|no_discard_passdown
+	Whether or not discards are actually being passed down to the
+	underlying device.  When this is enabled when loading the table,
+	it can get disabled if the underlying device doesn't support it.
+
+    ro|rw|out_of_data_space
+	If the pool encounters certain types of device failures it will
+	drop into a read-only metadata mode in which no changes to
+	the pool metadata (like allocating new blocks) are permitted.
+
+	In serious cases where even a read-only mode is deemed unsafe
+	no further I/O will be permitted and the status will just
+	contain the string 'Fail'.  The userspace recovery tools
+	should then be used.
+
+    error_if_no_space|queue_if_no_space
+	If the pool runs out of data or metadata space, the pool will
+	either queue or error the IO destined to the data device.  The
+	default is to queue the IO until more space is added or the
+	'no_space_timeout' expires.  The 'no_space_timeout' dm-thin-pool
+	module parameter can be used to change this timeout -- it
+	defaults to 60 seconds but may be disabled using a value of 0.
+
+    needs_check
+	A metadata operation has failed, resulting in the needs_check
+	flag being set in the metadata's superblock.  The metadata
+	device must be deactivated and checked/repaired before the
+	thin-pool can be made fully operational again.  '-' indicates
+	needs_check is not set.
+
+    metadata_low_watermark:
+	Value of metadata low watermark in blocks.  The kernel sets this
+	value internally but userspace needs to know this value to
+	determine if an event was caused by crossing this threshold.
+
+iii) Messages
+
+    create_thin <dev id>
+	Create a new thinly-provisioned device.
+	<dev id> is an arbitrary unique 24-bit identifier chosen by
+	the caller.
+
+    create_snap <dev id> <origin id>
+	Create a new snapshot of another thinly-provisioned device.
+	<dev id> is an arbitrary unique 24-bit identifier chosen by
+	the caller.
+	<origin id> is the identifier of the thinly-provisioned device
+	of which the new device will be a snapshot.
+
+    delete <dev id>
+	Deletes a thin device.  Irreversible.
+
+    set_transaction_id <current id> <new id>
+	Userland volume managers, such as LVM, need a way to
+	synchronise their external metadata with the internal metadata of the
+	pool target.  The thin-pool target offers to store an
+	arbitrary 64-bit transaction id and return it on the target's
+	status line.  To avoid races you must provide what you think
+	the current transaction id is when you change it with this
+	compare-and-swap message.
+
+    reserve_metadata_snap
+        Reserve a copy of the data mapping btree for use by userland.
+        This allows userland to inspect the mappings as they were when
+        this message was executed.  Use the pool's status command to
+        get the root block associated with the metadata snapshot.
+
+    release_metadata_snap
+        Release a previously reserved copy of the data mapping btree.
+
+'thin' target
+-------------
+
+i) Constructor
+
+    ::
+
+        thin <pool dev> <dev id> [<external origin dev>]
+
+    pool dev:
+	the thin-pool device, e.g. /dev/mapper/my_pool or 253:0
+
+    dev id:
+	the internal device identifier of the device to be
+	activated.
+
+    external origin dev:
+	an optional block device outside the pool to be treated as a
+	read-only snapshot origin: reads to unprovisioned areas of the
+	thin target will be mapped to this device.
+
+The pool doesn't store any size against the thin devices.  If you
+load a thin target that is smaller than you've been using previously,
+then you'll have no access to blocks mapped beyond the end.  If you
+load a target that is bigger than before, then extra blocks will be
+provisioned as and when needed.
+
+ii) Status
+
+    <nr mapped sectors> <highest mapped sector>
+	If the pool has encountered device errors and failed, the status
+	will just contain the string 'Fail'.  The userspace recovery
+	tools should then be used.
+
+    In the case where <nr mapped sectors> is 0, there is no highest
+    mapped sector and the value of <highest mapped sector> is unspecified.
diff --git a/Documentation/admin-guide/device-mapper/unstriped.rst b/Documentation/admin-guide/device-mapper/unstriped.rst
new file mode 100644
index 000000000..5772ccdd1
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/unstriped.rst
@@ -0,0 +1,135 @@
+================================
+Device-mapper "unstriped" target
+================================
+
+Introduction
+============
+
+The device-mapper "unstriped" target provides a transparent mechanism to
+unstripe a device-mapper "striped" target to access the underlying disks
+without having to touch the true backing block-device.  It can also be
+used to unstripe a hardware RAID-0 to access backing disks.
+
+Parameters:
+<number of stripes> <chunk size> <stripe #> <dev_path> <offset>
+
+<number of stripes>
+        The number of stripes in the RAID 0.
+
+<chunk size>
+	The amount of 512B sectors in the chunk striping.
+
+<dev_path>
+	The block device you wish to unstripe.
+
+<stripe #>
+        The stripe number within the device that corresponds to physical
+        drive you wish to unstripe.  This must be 0 indexed.
+
+
+Why use this module?
+====================
+
+An example of undoing an existing dm-stripe
+-------------------------------------------
+
+This small bash script will setup 4 loop devices and use the existing
+striped target to combine the 4 devices into one.  It then will use
+the unstriped target on top of the striped device to access the
+individual backing loop devices.  We write data to the newly exposed
+unstriped devices and verify the data written matches the correct
+underlying device on the striped array::
+
+  #!/bin/bash
+
+  MEMBER_SIZE=$((128 * 1024 * 1024))
+  NUM=4
+  SEQ_END=$((${NUM}-1))
+  CHUNK=256
+  BS=4096
+
+  RAID_SIZE=$((${MEMBER_SIZE}*${NUM}/512))
+  DM_PARMS="0 ${RAID_SIZE} striped ${NUM} ${CHUNK}"
+  COUNT=$((${MEMBER_SIZE} / ${BS}))
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dd if=/dev/zero of=member-${i} bs=${MEMBER_SIZE} count=1 oflag=direct
+    losetup /dev/loop${i} member-${i}
+    DM_PARMS+=" /dev/loop${i} 0"
+  done
+
+  echo $DM_PARMS | dmsetup create raid0
+  for i in $(seq 0 ${SEQ_END}); do
+    echo "0 1 unstriped ${NUM} ${CHUNK} ${i} /dev/mapper/raid0 0" | dmsetup create set-${i}
+  done;
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dd if=/dev/urandom of=/dev/mapper/set-${i} bs=${BS} count=${COUNT} oflag=direct
+    diff /dev/mapper/set-${i} member-${i}
+  done;
+
+  for i in $(seq 0 ${SEQ_END}); do
+    dmsetup remove set-${i}
+  done
+
+  dmsetup remove raid0
+
+  for i in $(seq 0 ${SEQ_END}); do
+    losetup -d /dev/loop${i}
+    rm -f member-${i}
+  done
+
+Another example
+---------------
+
+Intel NVMe drives contain two cores on the physical device.
+Each core of the drive has segregated access to its LBA range.
+The current LBA model has a RAID 0 128k chunk on each core, resulting
+in a 256k stripe across the two cores::
+
+   Core 0:       Core 1:
+  __________    __________
+  | LBA 512|    | LBA 768|
+  | LBA 0  |    | LBA 256|
+  ----------    ----------
+
+The purpose of this unstriping is to provide better QoS in noisy
+neighbor environments. When two partitions are created on the
+aggregate drive without this unstriping, reads on one partition
+can affect writes on another partition.  This is because the partitions
+are striped across the two cores.  When we unstripe this hardware RAID 0
+and make partitions on each new exposed device the two partitions are now
+physically separated.
+
+With the dm-unstriped target we're able to segregate an fio script that
+has read and write jobs that are independent of each other.  Compared to
+when we run the test on a combined drive with partitions, we were able
+to get a 92% reduction in read latency using this device mapper target.
+
+
+Example dmsetup usage
+=====================
+
+unstriped on top of Intel NVMe device that has 2 cores
+------------------------------------------------------
+
+::
+
+  dmsetup create nvmset0 --table '0 512 unstriped 2 256 0 /dev/nvme0n1 0'
+  dmsetup create nvmset1 --table '0 512 unstriped 2 256 1 /dev/nvme0n1 0'
+
+There will now be two devices that expose Intel NVMe core 0 and 1
+respectively::
+
+  /dev/mapper/nvmset0
+  /dev/mapper/nvmset1
+
+unstriped on top of striped with 4 drives using 128K chunk size
+---------------------------------------------------------------
+
+::
+
+  dmsetup create raid_disk0 --table '0 512 unstriped 4 256 0 /dev/mapper/striped 0'
+  dmsetup create raid_disk1 --table '0 512 unstriped 4 256 1 /dev/mapper/striped 0'
+  dmsetup create raid_disk2 --table '0 512 unstriped 4 256 2 /dev/mapper/striped 0'
+  dmsetup create raid_disk3 --table '0 512 unstriped 4 256 3 /dev/mapper/striped 0'
diff --git a/Documentation/admin-guide/device-mapper/vdo-design.rst b/Documentation/admin-guide/device-mapper/vdo-design.rst
new file mode 100644
index 000000000..faa0ecd4a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/vdo-design.rst
@@ -0,0 +1,633 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+================
+Design of dm-vdo
+================
+
+The dm-vdo (virtual data optimizer) target provides inline deduplication,
+compression, zero-block elimination, and thin provisioning. A dm-vdo target
+can be backed by up to 256TB of storage, and can present a logical size of
+up to 4PB. This target was originally developed at Permabit Technology
+Corp. starting in 2009. It was first released in 2013 and has been used in
+production environments ever since. It was made open-source in 2017 after
+Permabit was acquired by Red Hat. This document describes the design of
+dm-vdo. For usage, see vdo.rst in the same directory as this file.
+
+Because deduplication rates fall drastically as the block size increases, a
+vdo target has a maximum block size of 4K. However, it can achieve
+deduplication rates of 254:1, i.e. up to 254 copies of a given 4K block can
+reference a single 4K of actual storage. It can achieve compression rates
+of 14:1. All zero blocks consume no storage at all.
+
+Theory of Operation
+===================
+
+The design of dm-vdo is based on the idea that deduplication is a two-part
+problem. The first is to recognize duplicate data. The second is to avoid
+storing multiple copies of those duplicates. Therefore, dm-vdo has two main
+parts: a deduplication index (called UDS) that is used to discover
+duplicate data, and a data store with a reference counted block map that
+maps from logical block addresses to the actual storage location of the
+data.
+
+Zones and Threading
+-------------------
+
+Due to the complexity of data optimization, the number of metadata
+structures involved in a single write operation to a vdo target is larger
+than most other targets. Furthermore, because vdo must operate on small
+block sizes in order to achieve good deduplication rates, acceptable
+performance can only be achieved through parallelism. Therefore, vdo's
+design attempts to be lock-free.
+
+Most of a vdo's main data structures are designed to be easily divided into
+"zones" such that any given bio must only access a single zone of any zoned
+structure. Safety with minimal locking is achieved by ensuring that during
+normal operation, each zone is assigned to a specific thread, and only that
+thread will access the portion of the data structure in that zone.
+Associated with each thread is a work queue. Each bio is associated with a
+request object (the "data_vio") which will be added to a work queue when
+the next phase of its operation requires access to the structures in the
+zone associated with that queue.
+
+Another way of thinking about this arrangement is that the work queue for
+each zone has an implicit lock on the structures it manages for all its
+operations, because vdo guarantees that no other thread will alter those
+structures.
+
+Although each structure is divided into zones, this division is not
+reflected in the on-disk representation of each data structure. Therefore,
+the number of zones for each structure, and hence the number of threads,
+can be reconfigured each time a vdo target is started.
+
+The Deduplication Index
+-----------------------
+
+In order to identify duplicate data efficiently, vdo was designed to
+leverage some common characteristics of duplicate data. From empirical
+observations, we gathered two key insights. The first is that in most data
+sets with significant amounts of duplicate data, the duplicates tend to
+have temporal locality. When a duplicate appears, it is more likely that
+other duplicates will be detected, and that those duplicates will have been
+written at about the same time. This is why the index keeps records in
+temporal order. The second insight is that new data is more likely to
+duplicate recent data than it is to duplicate older data and in general,
+there are diminishing returns to looking further back in time. Therefore,
+when the index is full, it should cull its oldest records to make space for
+new ones. Another important idea behind the design of the index is that the
+ultimate goal of deduplication is to reduce storage costs. Since there is a
+trade-off between the storage saved and the resources expended to achieve
+those savings, vdo does not attempt to find every last duplicate block. It
+is sufficient to find and eliminate most of the redundancy.
+
+Each block of data is hashed to produce a 16-byte block name. An index
+record consists of this block name paired with the presumed location of
+that data on the underlying storage. However, it is not possible to
+guarantee that the index is accurate. In the most common case, this occurs
+because it is too costly to update the index when a block is over-written
+or discarded. Doing so would require either storing the block name along
+with the blocks, which is difficult to do efficiently in block-based
+storage, or reading and rehashing each block before overwriting it.
+Inaccuracy can also result from a hash collision where two different blocks
+have the same name. In practice, this is extremely unlikely, but because
+vdo does not use a cryptographic hash, a malicious workload could be
+constructed. Because of these inaccuracies, vdo treats the locations in the
+index as hints, and reads each indicated block to verify that it is indeed
+a duplicate before sharing the existing block with a new one.
+
+Records are collected into groups called chapters. New records are added to
+the newest chapter, called the open chapter. This chapter is stored in a
+format optimized for adding and modifying records, and the content of the
+open chapter is not finalized until it runs out of space for new records.
+When the open chapter fills up, it is closed and a new open chapter is
+created to collect new records.
+
+Closing a chapter converts it to a different format which is optimized for
+reading. The records are written to a series of record pages based on the
+order in which they were received. This means that records with temporal
+locality should be on a small number of pages, reducing the I/O required to
+retrieve them. The chapter also compiles an index that indicates which
+record page contains any given name. This index means that a request for a
+name can determine exactly which record page may contain that record,
+without having to load the entire chapter from storage. This index uses
+only a subset of the block name as its key, so it cannot guarantee that an
+index entry refers to the desired block name. It can only guarantee that if
+there is a record for this name, it will be on the indicated page. Closed
+chapters are read-only structures and their contents are never altered in
+any way.
+
+Once enough records have been written to fill up all the available index
+space, the oldest chapter is removed to make space for new chapters. Any
+time a request finds a matching record in the index, that record is copied
+into the open chapter. This ensures that useful block names remain available
+in the index, while unreferenced block names are forgotten over time.
+
+In order to find records in older chapters, the index also maintains a
+higher level structure called the volume index, which contains entries
+mapping each block name to the chapter containing its newest record. This
+mapping is updated as records for the block name are copied or updated,
+ensuring that only the newest record for a given block name can be found.
+An older record for a block name will no longer be found even though it has
+not been deleted from its chapter. Like the chapter index, the volume index
+uses only a subset of the block name as its key and can not definitively
+say that a record exists for a name. It can only say which chapter would
+contain the record if a record exists. The volume index is stored entirely
+in memory and is saved to storage only when the vdo target is shut down.
+
+From the viewpoint of a request for a particular block name, it will first
+look up the name in the volume index. This search will either indicate that
+the name is new, or which chapter to search. If it returns a chapter, the
+request looks up its name in the chapter index. This will indicate either
+that the name is new, or which record page to search. Finally, if it is not
+new, the request will look for its name in the indicated record page.
+This process may require up to two page reads per request (one for the
+chapter index page and one for the request page). However, recently
+accessed pages are cached so that these page reads can be amortized across
+many block name requests.
+
+The volume index and the chapter indexes are implemented using a
+memory-efficient structure called a delta index. Instead of storing the
+entire block name (the key) for each entry, the entries are sorted by name
+and only the difference between adjacent keys (the delta) is stored.
+Because we expect the hashes to be randomly distributed, the size of the
+deltas follows an exponential distribution. Because of this distribution,
+the deltas are expressed using a Huffman code to take up even less space.
+The entire sorted list of keys is called a delta list. This structure
+allows the index to use many fewer bytes per entry than a traditional hash
+table, but it is slightly more expensive to look up entries, because a
+request must read every entry in a delta list to add up the deltas in order
+to find the record it needs. The delta index reduces this lookup cost by
+splitting its key space into many sub-lists, each starting at a fixed key
+value, so that each individual list is short.
+
+The default index size can hold 64 million records, corresponding to about
+256GB of data. This means that the index can identify duplicate data if the
+original data was written within the last 256GB of writes. This range is
+called the deduplication window. If new writes duplicate data that is older
+than that, the index will not be able to find it because the records of the
+older data have been removed. This means that if an application writes a
+200 GB file to a vdo target and then immediately writes it again, the two
+copies will deduplicate perfectly. Doing the same with a 500 GB file will
+result in no deduplication, because the beginning of the file will no
+longer be in the index by the time the second write begins (assuming there
+is no duplication within the file itself).
+
+If an application anticipates a data workload that will see useful
+deduplication beyond the 256GB threshold, vdo can be configured to use a
+larger index with a correspondingly larger deduplication window. (This
+configuration can only be set when the target is created, not altered
+later. It is important to consider the expected workload for a vdo target
+before configuring it.)  There are two ways to do this.
+
+One way is to increase the memory size of the index, which also increases
+the amount of backing storage required. Doubling the size of the index will
+double the length of the deduplication window at the expense of doubling
+the storage size and the memory requirements.
+
+The other option is to enable sparse indexing. Sparse indexing increases
+the deduplication window by a factor of 10, at the expense of also
+increasing the storage size by a factor of 10. However with sparse
+indexing, the memory requirements do not increase. The trade-off is
+slightly more computation per request and a slight decrease in the amount
+of deduplication detected. For most workloads with significant amounts of
+duplicate data, sparse indexing will detect 97-99% of the deduplication
+that a standard index will detect.
+
+The vio and data_vio Structures
+-------------------------------
+
+A vio (short for Vdo I/O) is conceptually similar to a bio, with additional
+fields and data to track vdo-specific information. A struct vio maintains a
+pointer to a bio but also tracks other fields specific to the operation of
+vdo. The vio is kept separate from its related bio because there are many
+circumstances where vdo completes the bio but must continue to do work
+related to deduplication or compression.
+
+Metadata reads and writes, and other writes that originate within vdo, use
+a struct vio directly. Application reads and writes use a larger structure
+called a data_vio to track information about their progress. A struct
+data_vio contain a struct vio and also includes several other fields
+related to deduplication and other vdo features. The data_vio is the
+primary unit of application work in vdo. Each data_vio proceeds through a
+set of steps to handle the application data, after which it is reset and
+returned to a pool of data_vios for reuse.
+
+There is a fixed pool of 2048 data_vios. This number was chosen to bound
+the amount of work that is required to recover from a crash. In addition,
+benchmarks have indicated that increasing the size of the pool does not
+significantly improve performance.
+
+The Data Store
+--------------
+
+The data store is implemented by three main data structures, all of which
+work in concert to reduce or amortize metadata updates across as many data
+writes as possible.
+
+*The Slab Depot*
+
+Most of the vdo volume belongs to the slab depot. The depot contains a
+collection of slabs. The slabs can be up to 32GB, and are divided into
+three sections. Most of a slab consists of a linear sequence of 4K blocks.
+These blocks are used either to store data, or to hold portions of the
+block map (see below). In addition to the data blocks, each slab has a set
+of reference counters, using 1 byte for each data block. Finally each slab
+has a journal.
+
+Reference updates are written to the slab journal. Slab journal blocks are
+written out either when they are full, or when the recovery journal
+requests they do so in order to allow the main recovery journal (see below)
+to free up space. The slab journal is used both to ensure that the main
+recovery journal can regularly free up space, and also to amortize the cost
+of updating individual reference blocks. The reference counters are kept in
+memory and are written out, a block at a time in oldest-dirtied-order, only
+when there is a need to reclaim slab journal space. The write operations
+are performed in the background as needed so they do not add latency to
+particular I/O operations.
+
+Each slab is independent of every other. They are assigned to "physical
+zones" in round-robin fashion. If there are P physical zones, then slab n
+is assigned to zone n mod P.
+
+The slab depot maintains an additional small data structure, the "slab
+summary," which is used to reduce the amount of work needed to come back
+online after a crash. The slab summary maintains an entry for each slab
+indicating whether or not the slab has ever been used, whether all of its
+reference count updates have been persisted to storage, and approximately
+how full it is. During recovery, each physical zone will attempt to recover
+at least one slab, stopping whenever it has recovered a slab which has some
+free blocks. Once each zone has some space, or has determined that none is
+available, the target can resume normal operation in a degraded mode. Read
+and write requests can be serviced, perhaps with degraded performance,
+while the remainder of the dirty slabs are recovered.
+
+*The Block Map*
+
+The block map contains the logical to physical mapping. It can be thought
+of as an array with one entry per logical address. Each entry is 5 bytes,
+36 bits of which contain the physical block number which holds the data for
+the given logical address. The other 4 bits are used to indicate the nature
+of the mapping. Of the 16 possible states, one represents a logical address
+which is unmapped (i.e. it has never been written, or has been discarded),
+one represents an uncompressed block, and the other 14 states are used to
+indicate that the mapped data is compressed, and which of the compression
+slots in the compressed block contains the data for this logical address.
+
+In practice, the array of mapping entries is divided into "block map
+pages," each of which fits in a single 4K block. Each block map page
+consists of a header and 812 mapping entries. Each mapping page is actually
+a leaf of a radix tree which consists of block map pages at each level.
+There are 60 radix trees which are assigned to "logical zones" in round
+robin fashion. (If there are L logical zones, tree n will belong to zone n
+mod L.) At each level, the trees are interleaved, so logical addresses
+0-811 belong to tree 0, logical addresses 812-1623 belong to tree 1, and so
+on. The interleaving is maintained all the way up to the 60 root nodes.
+Choosing 60 trees results in an evenly distributed number of trees per zone
+for a large number of possible logical zone counts. The storage for the 60
+tree roots is allocated at format time. All other block map pages are
+allocated out of the slabs as needed. This flexible allocation avoids the
+need to pre-allocate space for the entire set of logical mappings and also
+makes growing the logical size of a vdo relatively easy.
+
+In operation, the block map maintains two caches. It is prohibitive to keep
+the entire leaf level of the trees in memory, so each logical zone
+maintains its own cache of leaf pages. The size of this cache is
+configurable at target start time. The second cache is allocated at start
+time, and is large enough to hold all the non-leaf pages of the entire
+block map. This cache is populated as pages are needed.
+
+*The Recovery Journal*
+
+The recovery journal is used to amortize updates across the block map and
+slab depot. Each write request causes an entry to be made in the journal.
+Entries are either "data remappings" or "block map remappings." For a data
+remapping, the journal records the logical address affected and its old and
+new physical mappings. For a block map remapping, the journal records the
+block map page number and the physical block allocated for it. Block map
+pages are never reclaimed or repurposed, so the old mapping is always 0.
+
+Each journal entry is an intent record summarizing the metadata updates
+that are required for a data_vio. The recovery journal issues a flush
+before each journal block write to ensure that the physical data for the
+new block mappings in that block are stable on storage, and journal block
+writes are all issued with the FUA bit set to ensure the recovery journal
+entries themselves are stable. The journal entry and the data write it
+represents must be stable on disk before the other metadata structures may
+be updated to reflect the operation. These entries allow the vdo device to
+reconstruct the logical to physical mappings after an unexpected
+interruption such as a loss of power.
+
+*Write Path*
+
+All write I/O to vdo is asynchronous. Each bio will be acknowledged as soon
+as vdo has done enough work to guarantee that it can complete the write
+eventually. Generally, the data for acknowledged but unflushed write I/O
+can be treated as though it is cached in memory. If an application
+requires data to be stable on storage, it must issue a flush or write the
+data with the FUA bit set like any other asynchronous I/O. Shutting down
+the vdo target will also flush any remaining I/O.
+
+Application write bios follow the steps outlined below.
+
+1.  A data_vio is obtained from the data_vio pool and associated with the
+    application bio. If there are no data_vios available, the incoming bio
+    will block until a data_vio is available. This provides back pressure
+    to the application. The data_vio pool is protected by a spin lock.
+
+    The newly acquired data_vio is reset and the bio's data is copied into
+    the data_vio if it is a write and the data is not all zeroes. The data
+    must be copied because the application bio can be acknowledged before
+    the data_vio processing is complete, which means later processing steps
+    will no longer have access to the application bio. The application bio
+    may also be smaller than 4K, in which case the data_vio will have
+    already read the underlying block and the data is instead copied over
+    the relevant portion of the larger block.
+
+2.  The data_vio places a claim (the "logical lock") on the logical address
+    of the bio. It is vital to prevent simultaneous modifications of the
+    same logical address, because deduplication involves sharing blocks.
+    This claim is implemented as an entry in a hashtable where the key is
+    the logical address and the value is a pointer to the data_vio
+    currently handling that address.
+
+    If a data_vio looks in the hashtable and finds that another data_vio is
+    already operating on that logical address, it waits until the previous
+    operation finishes. It also sends a message to inform the current
+    lock holder that it is waiting. Most notably, a new data_vio waiting
+    for a logical lock will flush the previous lock holder out of the
+    compression packer (step 8d) rather than allowing it to continue
+    waiting to be packed.
+
+    This stage requires the data_vio to get an implicit lock on the
+    appropriate logical zone to prevent concurrent modifications of the
+    hashtable. This implicit locking is handled by the zone divisions
+    described above.
+
+3.  The data_vio traverses the block map tree to ensure that all the
+    necessary internal tree nodes have been allocated, by trying to find
+    the leaf page for its logical address. If any interior tree page is
+    missing, it is allocated at this time out of the same physical storage
+    pool used to store application data.
+
+    a. If any page-node in the tree has not yet been allocated, it must be
+       allocated before the write can continue. This step requires the
+       data_vio to lock the page-node that needs to be allocated. This
+       lock, like the logical block lock in step 2, is a hashtable entry
+       that causes other data_vios to wait for the allocation process to
+       complete.
+
+       The implicit logical zone lock is released while the allocation is
+       happening, in order to allow other operations in the same logical
+       zone to proceed. The details of allocation are the same as in
+       step 4. Once a new node has been allocated, that node is added to
+       the tree using a similar process to adding a new data block mapping.
+       The data_vio journals the intent to add the new node to the block
+       map tree (step 10), updates the reference count of the new block
+       (step 11), and reacquires the implicit logical zone lock to add the
+       new mapping to the parent tree node (step 12). Once the tree is
+       updated, the data_vio proceeds down the tree. Any other data_vios
+       waiting on this allocation also proceed.
+
+    b. In the steady-state case, the block map tree nodes will already be
+       allocated, so the data_vio just traverses the tree until it finds
+       the required leaf node. The location of the mapping (the "block map
+       slot") is recorded in the data_vio so that later steps do not need
+       to traverse the tree again. The data_vio then releases the implicit
+       logical zone lock.
+
+4.  If the block is a zero block, skip to step 9. Otherwise, an attempt is
+    made to allocate a free data block. This allocation ensures that the
+    data_vio can write its data somewhere even if deduplication and
+    compression are not possible. This stage gets an implicit lock on a
+    physical zone to search for free space within that zone.
+
+    The data_vio will search each slab in a zone until it finds a free
+    block or decides there are none. If the first zone has no free space,
+    it will proceed to search the next physical zone by taking the implicit
+    lock for that zone and releasing the previous one until it finds a
+    free block or runs out of zones to search. The data_vio will acquire a
+    struct pbn_lock (the "physical block lock") on the free block. The
+    struct pbn_lock also has several fields to record the various kinds of
+    claims that data_vios can have on physical blocks. The pbn_lock is
+    added to a hashtable like the logical block locks in step 2. This
+    hashtable is also covered by the implicit physical zone lock. The
+    reference count of the free block is updated to prevent any other
+    data_vio from considering it free. The reference counters are a
+    sub-component of the slab and are thus also covered by the implicit
+    physical zone lock.
+
+5.  If an allocation was obtained, the data_vio has all the resources it
+    needs to complete the write. The application bio can safely be
+    acknowledged at this point. The acknowledgment happens on a separate
+    thread to prevent the application callback from blocking other data_vio
+    operations.
+
+    If an allocation could not be obtained, the data_vio continues to
+    attempt to deduplicate or compress the data, but the bio is not
+    acknowledged because the vdo device may be out of space.
+
+6.  At this point vdo must determine where to store the application data.
+    The data_vio's data is hashed and the hash (the "record name") is
+    recorded in the data_vio.
+
+7.  The data_vio reserves or joins a struct hash_lock, which manages all of
+    the data_vios currently writing the same data. Active hash locks are
+    tracked in a hashtable similar to the way logical block locks are
+    tracked in step 2. This hashtable is covered by the implicit lock on
+    the hash zone.
+
+    If there is no existing hash lock for this data_vio's record_name, the
+    data_vio obtains a hash lock from the pool, adds it to the hashtable,
+    and sets itself as the new hash lock's "agent." The hash_lock pool is
+    also covered by the implicit hash zone lock. The hash lock agent will
+    do all the work to decide where the application data will be
+    written. If a hash lock for the data_vio's record_name already exists,
+    and the data_vio's data is the same as the agent's data, the new
+    data_vio will wait for the agent to complete its work and then share
+    its result.
+
+    In the rare case that a hash lock exists for the data_vio's hash but
+    the data does not match the hash lock's agent, the data_vio skips to
+    step 8h and attempts to write its data directly. This can happen if two
+    different data blocks produce the same hash, for example.
+
+8.  The hash lock agent attempts to deduplicate or compress its data with
+    the following steps.
+
+    a. The agent initializes and sends its embedded deduplication request
+       (struct uds_request) to the deduplication index. This does not
+       require the data_vio to get any locks because the index components
+       manage their own locking. The data_vio waits until it either gets a
+       response from the index or times out.
+
+    b. If the deduplication index returns advice, the data_vio attempts to
+       obtain a physical block lock on the indicated physical address, in
+       order to read the data and verify that it is the same as the
+       data_vio's data, and that it can accept more references. If the
+       physical address is already locked by another data_vio, the data at
+       that address may soon be overwritten so it is not safe to use the
+       address for deduplication.
+
+    c. If the data matches and the physical block can add references, the
+       agent and any other data_vios waiting on it will record this
+       physical block as their new physical address and proceed to step 9
+       to record their new mapping. If there are more data_vios in the hash
+       lock than there are references available, one of the remaining
+       data_vios becomes the new agent and continues to step 8d as if no
+       valid advice was returned.
+
+    d. If no usable duplicate block was found, the agent first checks that
+       it has an allocated physical block (from step 3) that it can write
+       to. If the agent does not have an allocation, some other data_vio in
+       the hash lock that does have an allocation takes over as agent. If
+       none of the data_vios have an allocated physical block, these writes
+       are out of space, so they proceed to step 13 for cleanup.
+
+    e. The agent attempts to compress its data. If the data does not
+       compress, the data_vio will continue to step 8h to write its data
+       directly.
+
+       If the compressed size is small enough, the agent will release the
+       implicit hash zone lock and go to the packer (struct packer) where
+       it will be placed in a bin (struct packer_bin) along with other
+       data_vios. All compression operations require the implicit lock on
+       the packer zone.
+
+       The packer can combine up to 14 compressed blocks in a single 4k
+       data block. Compression is only helpful if vdo can pack at least 2
+       data_vios into a single data block. This means that a data_vio may
+       wait in the packer for an arbitrarily long time for other data_vios
+       to fill out the compressed block. There is a mechanism for vdo to
+       evict waiting data_vios when continuing to wait would cause
+       problems. Circumstances causing an eviction include an application
+       flush, device shutdown, or a subsequent data_vio trying to overwrite
+       the same logical block address. A data_vio may also be evicted from
+       the packer if it cannot be paired with any other compressed block
+       before more compressible blocks need to use its bin. An evicted
+       data_vio will proceed to step 8h to write its data directly.
+
+    f. If the agent fills a packer bin, either because all 14 of its slots
+       are used or because it has no remaining space, it is written out
+       using the allocated physical block from one of its data_vios. Step
+       8d has already ensured that an allocation is available.
+
+    g. Each data_vio sets the compressed block as its new physical address.
+       The data_vio obtains an implicit lock on the physical zone and
+       acquires the struct pbn_lock for the compressed block, which is
+       modified to be a shared lock. Then it releases the implicit physical
+       zone lock and proceeds to step 8i.
+
+    h. Any data_vio evicted from the packer will have an allocation from
+       step 3. It will write its data to that allocated physical block.
+
+    i. After the data is written, if the data_vio is the agent of a hash
+       lock, it will reacquire the implicit hash zone lock and share its
+       physical address with as many other data_vios in the hash lock as
+       possible. Each data_vio will then proceed to step 9 to record its
+       new mapping.
+
+    j. If the agent actually wrote new data (whether compressed or not),
+       the deduplication index is updated to reflect the location of the
+       new data. The agent then releases the implicit hash zone lock.
+
+9.  The data_vio determines the previous mapping of the logical address.
+    There is a cache for block map leaf pages (the "block map cache"),
+    because there are usually too many block map leaf nodes to store
+    entirely in memory. If the desired leaf page is not in the cache, the
+    data_vio will reserve a slot in the cache and load the desired page
+    into it, possibly evicting an older cached page. The data_vio then
+    finds the current physical address for this logical address (the "old
+    physical mapping"), if any, and records it. This step requires a lock
+    on the block map cache structures, covered by the implicit logical zone
+    lock.
+
+10. The data_vio makes an entry in the recovery journal containing the
+    logical block address, the old physical mapping, and the new physical
+    mapping. Making this journal entry requires holding the implicit
+    recovery journal lock. The data_vio will wait in the journal until all
+    recovery blocks up to the one containing its entry have been written
+    and flushed to ensure the transaction is stable on storage.
+
+11. Once the recovery journal entry is stable, the data_vio makes two slab
+    journal entries: an increment entry for the new mapping, and a
+    decrement entry for the old mapping. These two operations each require
+    holding a lock on the affected physical slab, covered by its implicit
+    physical zone lock. For correctness during recovery, the slab journal
+    entries in any given slab journal must be in the same order as the
+    corresponding recovery journal entries. Therefore, if the two entries
+    are in different zones, they are made concurrently, and if they are in
+    the same zone, the increment is always made before the decrement in
+    order to avoid underflow. After each slab journal entry is made in
+    memory, the associated reference count is also updated in memory.
+
+12. Once both of the reference count updates are done, the data_vio
+    acquires the implicit logical zone lock and updates the
+    logical-to-physical mapping in the block map to point to the new
+    physical block. At this point the write operation is complete.
+
+13. If the data_vio has a hash lock, it acquires the implicit hash zone
+    lock and releases its hash lock to the pool.
+
+    The data_vio then acquires the implicit physical zone lock and releases
+    the struct pbn_lock it holds for its allocated block. If it had an
+    allocation that it did not use, it also sets the reference count for
+    that block back to zero to free it for use by subsequent data_vios.
+
+    The data_vio then acquires the implicit logical zone lock and releases
+    the logical block lock acquired in step 2.
+
+    The application bio is then acknowledged if it has not previously been
+    acknowledged, and the data_vio is returned to the pool.
+
+*Read Path*
+
+An application read bio follows a much simpler set of steps. It does steps
+1 and 2 in the write path to obtain a data_vio and lock its logical
+address. If there is already a write data_vio in progress for that logical
+address that is guaranteed to complete, the read data_vio will copy the
+data from the write data_vio and return it. Otherwise, it will look up the
+logical-to-physical mapping by traversing the block map tree as in step 3,
+and then read and possibly decompress the indicated data at the indicated
+physical block address. A read data_vio will not allocate block map tree
+nodes if they are missing. If the interior block map nodes do not exist
+yet, the logical block map address must still be unmapped and the read
+data_vio will return all zeroes. A read data_vio handles cleanup and
+acknowledgment as in step 13, although it only needs to release the logical
+lock and return itself to the pool.
+
+*Small Writes*
+
+All storage within vdo is managed as 4KB blocks, but it can accept writes
+as small as 512 bytes. Processing a write that is smaller than 4K requires
+a read-modify-write operation that reads the relevant 4K block, copies the
+new data over the appropriate sectors of the block, and then launches a
+write operation for the modified data block. The read and write stages of
+this operation are nearly identical to the normal read and write
+operations, and a single data_vio is used throughout this operation.
+
+*Recovery*
+
+When a vdo is restarted after a crash, it will attempt to recover from the
+recovery journal. During the pre-resume phase of the next start, the
+recovery journal is read. The increment portion of valid entries are played
+into the block map. Next, valid entries are played, in order as required,
+into the slab journals. Finally, each physical zone attempts to replay at
+least one slab journal to reconstruct the reference counts of one slab.
+Once each zone has some free space (or has determined that it has none),
+the vdo comes back online, while the remainder of the slab journals are
+used to reconstruct the rest of the reference counts in the background.
+
+*Read-only Rebuild*
+
+If a vdo encounters an unrecoverable error, it will enter read-only mode.
+This mode indicates that some previously acknowledged data may have been
+lost. The vdo may be instructed to rebuild as best it can in order to
+return to a writable state. However, this is never done automatically due
+to the possibility that data has been lost. During a read-only rebuild, the
+block map is recovered from the recovery journal as before. However, the
+reference counts are not rebuilt from the slab journals. Instead, the
+reference counts are zeroed, the entire block map is traversed, and the
+reference counts are updated from the block mappings. While this may lose
+some data, it ensures that the block map and reference counts are
+consistent with each other. This allows vdo to resume normal operation and
+accept further writes.
diff --git a/Documentation/admin-guide/device-mapper/vdo.rst b/Documentation/admin-guide/device-mapper/vdo.rst
new file mode 100644
index 000000000..8a67b320a
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/vdo.rst
@@ -0,0 +1,413 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+======
+dm-vdo
+======
+
+The dm-vdo (virtual data optimizer) device mapper target provides
+block-level deduplication, compression, and thin provisioning. As a device
+mapper target, it can add these features to the storage stack, compatible
+with any file system. The vdo target does not protect against data
+corruption, relying instead on integrity protection of the storage below
+it. It is strongly recommended that lvm be used to manage vdo volumes. See
+lvmvdo(7).
+
+Userspace component
+===================
+
+Formatting a vdo volume requires the use of the 'vdoformat' tool, available
+at:
+
+https://github.com/dm-vdo/vdo/
+
+In most cases, a vdo target will recover from a crash automatically the
+next time it is started. In cases where it encountered an unrecoverable
+error (either during normal operation or crash recovery) the target will
+enter or come up in read-only mode. Because read-only mode is indicative of
+data-loss, a positive action must be taken to bring vdo out of read-only
+mode. The 'vdoforcerebuild' tool, available from the same repo, is used to
+prepare a read-only vdo to exit read-only mode. After running this tool,
+the vdo target will rebuild its metadata the next time it is
+started. Although some data may be lost, the rebuilt vdo's metadata will be
+internally consistent and the target will be writable again.
+
+The repo also contains additional userspace tools which can be used to
+inspect a vdo target's on-disk metadata. Fortunately, these tools are
+rarely needed except by dm-vdo developers.
+
+Metadata requirements
+=====================
+
+Each vdo volume reserves 3GB of space for metadata, or more depending on
+its configuration. It is helpful to check that the space saved by
+deduplication and compression is not cancelled out by the metadata
+requirements. An estimation of the space saved for a specific dataset can
+be computed with the vdo estimator tool, which is available at:
+
+https://github.com/dm-vdo/vdoestimator/
+
+Target interface
+================
+
+Table line
+----------
+
+::
+
+	<offset> <logical device size> vdo V4 <storage device>
+	<storage device size> <minimum I/O size> <block map cache size>
+	<block map era length> [optional arguments]
+
+
+Required parameters:
+
+	offset:
+		The offset, in sectors, at which the vdo volume's logical
+		space begins.
+
+	logical device size:
+		The size of the device which the vdo volume will service,
+		in sectors. Must match the current logical size of the vdo
+		volume.
+
+	storage device:
+		The device holding the vdo volume's data and metadata.
+
+	storage device size:
+		The size of the device holding the vdo volume, as a number
+		of 4096-byte blocks. Must match the current size of the vdo
+		volume.
+
+	minimum I/O size:
+		The minimum I/O size for this vdo volume to accept, in
+		bytes. Valid values are 512 or 4096. The recommended value
+		is 4096.
+
+	block map cache size:
+		The size of the block map cache, as a number of 4096-byte
+		blocks. The minimum and recommended value is 32768 blocks.
+		If the logical thread count is non-zero, the cache size
+		must be at least 4096 blocks per logical thread.
+
+	block map era length:
+		The speed with which the block map cache writes out
+		modified block map pages. A smaller era length is likely to
+		reduce the amount of time spent rebuilding, at the cost of
+		increased block map writes during normal operation. The
+		maximum and recommended value is 16380; the minimum value
+		is 1.
+
+Optional parameters:
+--------------------
+Some or all of these parameters may be specified as <key> <value> pairs.
+
+Thread related parameters:
+
+Different categories of work are assigned to separate thread groups, and
+the number of threads in each group can be configured separately.
+
+If <hash>, <logical>, and <physical> are all set to 0, the work handled by
+all three thread types will be handled by a single thread. If any of these
+values are non-zero, all of them must be non-zero.
+
+	ack:
+		The number of threads used to complete bios. Since
+		completing a bio calls an arbitrary completion function
+		outside the vdo volume, threads of this type allow the vdo
+		volume to continue processing requests even when bio
+		completion is slow. The default is 1.
+
+	bio:
+		The number of threads used to issue bios to the underlying
+		storage. Threads of this type allow the vdo volume to
+		continue processing requests even when bio submission is
+		slow. The default is 4.
+
+	bioRotationInterval:
+		The number of bios to enqueue on each bio thread before
+		switching to the next thread. The value must be greater
+		than 0 and not more than 1024; the default is 64.
+
+	cpu:
+		The number of threads used to do CPU-intensive work, such
+		as hashing and compression. The default is 1.
+
+	hash:
+		The number of threads used to manage data comparisons for
+		deduplication based on the hash value of data blocks. The
+		default is 0.
+
+	logical:
+		The number of threads used to manage caching and locking
+		based on the logical address of incoming bios. The default
+		is 0; the maximum is 60.
+
+	physical:
+		The number of threads used to manage administration of the
+		underlying storage device. At format time, a slab size for
+		the vdo is chosen; the vdo storage device must be large
+		enough to have at least 1 slab per physical thread. The
+		default is 0; the maximum is 16.
+
+Miscellaneous parameters:
+
+	maxDiscard:
+		The maximum size of discard bio accepted, in 4096-byte
+		blocks. I/O requests to a vdo volume are normally split
+		into 4096-byte blocks, and processed up to 2048 at a time.
+		However, discard requests to a vdo volume can be
+		automatically split to a larger size, up to <maxDiscard>
+		4096-byte blocks in a single bio, and are limited to 1500
+		at a time. Increasing this value may provide better overall
+		performance, at the cost of increased latency for the
+		individual discard requests. The default and minimum is 1;
+		the maximum is UINT_MAX / 4096.
+
+	deduplication:
+		Whether deduplication is enabled. The default is 'on'; the
+		acceptable values are 'on' and 'off'.
+
+	compression:
+		Whether compression is enabled. The default is 'off'; the
+		acceptable values are 'on' and 'off'.
+
+Device modification
+-------------------
+
+A modified table may be loaded into a running, non-suspended vdo volume.
+The modifications will take effect when the device is next resumed. The
+modifiable parameters are <logical device size>, <physical device size>,
+<maxDiscard>, <compression>, and <deduplication>.
+
+If the logical device size or physical device size are changed, upon
+successful resume vdo will store the new values and require them on future
+startups. These two parameters may not be decreased. The logical device
+size may not exceed 4 PB. The physical device size must increase by at
+least 32832 4096-byte blocks if at all, and must not exceed the size of the
+underlying storage device. Additionally, when formatting the vdo device, a
+slab size is chosen: the physical device size may never increase above the
+size which provides 8192 slabs, and each increase must be large enough to
+add at least one new slab.
+
+Examples:
+
+Start a previously-formatted vdo volume with 1 GB logical space and 1 GB
+physical space, storing to /dev/dm-1 which has more than 1 GB of space.
+
+::
+
+	dmsetup create vdo0 --table \
+	"0 2097152 vdo V4 /dev/dm-1 262144 4096 32768 16380"
+
+Grow the logical size to 4 GB.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 8388608 vdo V4 /dev/dm-1 262144 4096 32768 16380"
+	dmsetup resume vdo0
+
+Grow the physical size to 2 GB.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 8388608 vdo V4 /dev/dm-1 524288 4096 32768 16380"
+	dmsetup resume vdo0
+
+Grow the physical size by 1 GB more and increase max discard sectors.
+
+::
+
+	dmsetup reload vdo0 --table \
+	"0 10485760 vdo V4 /dev/dm-1 786432 4096 32768 16380 maxDiscard 8"
+	dmsetup resume vdo0
+
+Stop the vdo volume.
+
+::
+
+	dmsetup remove vdo0
+
+Start the vdo volume again. Note that the logical and physical device sizes
+must still match, but other parameters can change.
+
+::
+
+	dmsetup create vdo1 --table \
+	"0 10485760 vdo V4 /dev/dm-1 786432 512 65550 5000 hash 1 logical 3 physical 2"
+
+Messages
+--------
+All vdo devices accept messages in the form:
+
+::
+
+        dmsetup message <target-name> 0 <message-name> <message-parameters>
+
+The messages are:
+
+        stats:
+		Outputs the current view of the vdo statistics. Mostly used
+		by the vdostats userspace program to interpret the output
+		buffer.
+
+	config:
+		Outputs useful vdo configuration information. Mostly used
+		by users who want to recreate a similar VDO volume and
+		want to know the creation configuration used.
+
+	dump:
+		Dumps many internal structures to the system log. This is
+		not always safe to run, so it should only be used to debug
+		a hung vdo. Optional parameters to specify structures to
+		dump are:
+
+			viopool: The pool of I/O requests incoming bios
+			pools: A synonym of 'viopool'
+			vdo: Most of the structures managing on-disk data
+			queues: Basic information about each vdo thread
+			threads: A synonym of 'queues'
+			default: Equivalent to 'queues vdo'
+			all: All of the above.
+
+        dump-on-shutdown:
+		Perform a default dump next time vdo shuts down.
+
+
+Status
+------
+
+::
+
+    <device> <operating mode> <in recovery> <index state>
+    <compression state> <physical blocks used> <total physical blocks>
+
+	device:
+		The name of the vdo volume.
+
+	operating mode:
+		The current operating mode of the vdo volume; values may be
+		'normal', 'recovering' (the volume has detected an issue
+		with its metadata and is attempting to repair itself), and
+		'read-only' (an error has occurred that forces the vdo
+		volume to only support read operations and not writes).
+
+	in recovery:
+		Whether the vdo volume is currently in recovery mode;
+		values may be 'recovering' or '-' which indicates not
+		recovering.
+
+	index state:
+		The current state of the deduplication index in the vdo
+		volume; values may be 'closed', 'closing', 'error',
+		'offline', 'online', 'opening', and 'unknown'.
+
+	compression state:
+		The current state of compression in the vdo volume; values
+		may be 'offline' and 'online'.
+
+	used physical blocks:
+		The number of physical blocks in use by the vdo volume.
+
+	total physical blocks:
+		The total number of physical blocks the vdo volume may use;
+		the difference between this value and the
+		<used physical blocks> is the number of blocks the vdo
+		volume has left before being full.
+
+Memory Requirements
+===================
+
+A vdo target requires a fixed 38 MB of RAM along with the following amounts
+that scale with the target:
+
+- 1.15 MB of RAM for each 1 MB of configured block map cache size. The
+  block map cache requires a minimum of 150 MB.
+- 1.6 MB of RAM for each 1 TB of logical space.
+- 268 MB of RAM for each 1 TB of physical storage managed by the volume.
+
+The deduplication index requires additional memory which scales with the
+size of the deduplication window. For dense indexes, the index requires 1
+GB of RAM per 1 TB of window. For sparse indexes, the index requires 1 GB
+of RAM per 10 TB of window. The index configuration is set when the target
+is formatted and may not be modified.
+
+Module Parameters
+=================
+
+The vdo driver has a numeric parameter 'log_level' which controls the
+verbosity of logging from the driver. The default setting is 6
+(LOGLEVEL_INFO and more severe messages).
+
+Run-time Usage
+==============
+
+When using dm-vdo, it is important to be aware of the ways in which its
+behavior differs from other storage targets.
+
+- There is no guarantee that over-writes of existing blocks will succeed.
+  Because the underlying storage may be multiply referenced, over-writing
+  an existing block generally requires a vdo to have a free block
+  available.
+
+- When blocks are no longer in use, sending a discard request for those
+  blocks lets the vdo release references for those blocks. If the vdo is
+  thinly provisioned, discarding unused blocks is essential to prevent the
+  target from running out of space. However, due to the sharing of
+  duplicate blocks, no discard request for any given logical block is
+  guaranteed to reclaim space.
+
+- Assuming the underlying storage properly implements flush requests, vdo
+  is resilient against crashes, however, unflushed writes may or may not
+  persist after a crash.
+
+- Each write to a vdo target entails a significant amount of processing.
+  However, much of the work is paralellizable. Therefore, vdo targets
+  achieve better throughput at higher I/O depths, and can support up 2048
+  requests in parallel.
+
+Tuning
+======
+
+The vdo device has many options, and it can be difficult to make optimal
+choices without perfect knowledge of the workload. Additionally, most
+configuration options must be set when a vdo target is started, and cannot
+be changed without shutting it down completely; the configuration cannot be
+changed while the target is active. Ideally, tuning with simulated
+workloads should be performed before deploying vdo in production
+environments.
+
+The most important value to adjust is the block map cache size. In order to
+service a request for any logical address, a vdo must load the portion of
+the block map which holds the relevant mapping. These mappings are cached.
+Performance will suffer when the working set does not fit in the cache. By
+default, a vdo allocates 128 MB of metadata cache in RAM to support
+efficient access to 100 GB of logical space at a time. It should be scaled
+up proportionally for larger working sets.
+
+The logical and physical thread counts should also be adjusted. A logical
+thread controls a disjoint section of the block map, so additional logical
+threads increase parallelism and can increase throughput. Physical threads
+control a disjoint section of the data blocks, so additional physical
+threads can also increase throughput. However, excess threads can waste
+resources and increase contention.
+
+Bio submission threads control the parallelism involved in sending I/O to
+the underlying storage; fewer threads mean there is more opportunity to
+reorder I/O requests for performance benefit, but also that each I/O
+request has to wait longer before being submitted.
+
+Bio acknowledgment threads are used for finishing I/O requests. This is
+done on dedicated threads since the amount of work required to execute a
+bio's callback can not be controlled by the vdo itself. Usually one thread
+is sufficient but additional threads may be beneficial, particularly when
+bios have CPU-heavy callbacks.
+
+CPU threads are used for hashing and for compression; in workloads with
+compression enabled, more threads may result in higher throughput.
+
+Hash threads are used to sort active requests by hash and determine whether
+they should deduplicate; the most CPU intensive actions done by these
+threads are comparison of 4096-byte data blocks. In most cases, a single
+hash thread is sufficient.
diff --git a/Documentation/admin-guide/device-mapper/verity.rst b/Documentation/admin-guide/device-mapper/verity.rst
new file mode 100644
index 000000000..eb9475d7e
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/verity.rst
@@ -0,0 +1,349 @@
+=========
+dm-verity
+=========
+
+Device-Mapper's "verity" target provides transparent integrity checking of
+block devices using a cryptographic digest provided by the kernel crypto API.
+This target is read-only.
+
+Construction Parameters
+=======================
+
+::
+
+    <version> <dev> <hash_dev>
+    <data_block_size> <hash_block_size>
+    <num_data_blocks> <hash_start_block>
+    <algorithm> <digest> <salt>
+    [<#opt_params> <opt_params>]
+
+<version>
+    This is the type of the on-disk hash format.
+
+    0 is the original format used in the Chromium OS.
+      The salt is appended when hashing, digests are stored continuously and
+      the rest of the block is padded with zeroes.
+
+    1 is the current format that should be used for new devices.
+      The salt is prepended when hashing and each digest is
+      padded with zeroes to the power of two.
+
+<dev>
+    This is the device containing data, the integrity of which needs to be
+    checked.  It may be specified as a path, like /dev/sdaX, or a device number,
+    <major>:<minor>.
+
+<hash_dev>
+    This is the device that supplies the hash tree data.  It may be
+    specified similarly to the device path and may be the same device.  If the
+    same device is used, the hash_start should be outside the configured
+    dm-verity device.
+
+<data_block_size>
+    The block size on a data device in bytes.
+    Each block corresponds to one digest on the hash device.
+
+<hash_block_size>
+    The size of a hash block in bytes.
+
+<num_data_blocks>
+    The number of data blocks on the data device.  Additional blocks are
+    inaccessible.  You can place hashes to the same partition as data, in this
+    case hashes are placed after <num_data_blocks>.
+
+<hash_start_block>
+    This is the offset, in <hash_block_size>-blocks, from the start of hash_dev
+    to the root block of the hash tree.
+
+<algorithm>
+    The cryptographic hash algorithm used for this device.  This should
+    be the name of the algorithm, like "sha1".
+
+<digest>
+    The hexadecimal encoding of the cryptographic hash of the root hash block
+    and the salt.  This hash should be trusted as there is no other authenticity
+    beyond this point.
+
+<salt>
+    The hexadecimal encoding of the salt value.
+
+<#opt_params>
+    Number of optional parameters. If there are no optional parameters,
+    the optional parameters section can be skipped or #opt_params can be zero.
+    Otherwise #opt_params is the number of following arguments.
+
+    Example of optional parameters section:
+        1 ignore_corruption
+
+ignore_corruption
+    Log corrupted blocks, but allow read operations to proceed normally.
+
+restart_on_corruption
+    Restart the system when a corrupted block is discovered. This option is
+    not compatible with ignore_corruption and requires user space support to
+    avoid restart loops.
+
+panic_on_corruption
+    Panic the device when a corrupted block is discovered. This option is
+    not compatible with ignore_corruption and restart_on_corruption.
+
+restart_on_error
+    Restart the system when an I/O error is detected.
+    This option can be combined with the restart_on_corruption option.
+
+panic_on_error
+    Panic the device when an I/O error is detected. This option is
+    not compatible with the restart_on_error option but can be combined
+    with the panic_on_corruption option.
+
+ignore_zero_blocks
+    Do not verify blocks that are expected to contain zeroes and always return
+    zeroes instead. This may be useful if the partition contains unused blocks
+    that are not guaranteed to contain zeroes.
+
+use_fec_from_device <fec_dev>
+    Use forward error correction (FEC) parity data from the specified device to
+    try to automatically recover from corruption and I/O errors.
+
+    If this option is given, then <fec_roots> and <fec_blocks> must also be
+    given.  <hash_block_size> must also be equal to <data_block_size>.
+
+    <fec_dev> can be the same as <dev>, in which case <fec_start> must be
+    outside the data area.  It can also be the same as <hash_dev>, in which case
+    <fec_start> must be outside the hash and optional additional metadata areas.
+
+    If the data <dev> is encrypted, the <fec_dev> should be too.
+
+    For more information, see `Forward error correction`_.
+
+fec_roots <num>
+    The number of parity bytes in each 255-byte Reed-Solomon codeword.  The
+    Reed-Solomon code used will be an RS(255, k) code where k = 255 - fec_roots.
+
+    The supported values are 2 through 24 inclusive.  Higher values provide
+    stronger error correction.  However, the minimum value of 2 already provides
+    strong error correction due to the use of interleaving, so 2 is the
+    recommended value for most users.  fec_roots=2 corresponds to an
+    RS(255, 253) code, which has a space overhead of about 0.8%.
+
+fec_blocks <num>
+    The total number of <data_block_size> blocks that are error-checked using
+    FEC.  This must be at least the sum of <num_data_blocks> and the number of
+    blocks needed by the hash tree.  It can include additional metadata blocks,
+    which are assumed to be accessible on <hash_dev> following the hash blocks.
+
+    Note that this is *not* the number of parity blocks.  The number of parity
+    blocks is inferred from <fec_blocks>, <fec_roots>, and <data_block_size>.
+
+fec_start <offset>
+    This is the offset, in <data_block_size> blocks, from the start of <fec_dev>
+    to the beginning of the parity data.
+
+check_at_most_once
+    Verify data blocks only the first time they are read from the data device,
+    rather than every time.  This reduces the overhead of dm-verity so that it
+    can be used on systems that are memory and/or CPU constrained.  However, it
+    provides a reduced level of security because only offline tampering of the
+    data device's content will be detected, not online tampering.
+
+    Hash blocks are still verified each time they are read from the hash device,
+    since verification of hash blocks is less performance critical than data
+    blocks, and a hash block will not be verified any more after all the data
+    blocks it covers have been verified anyway.
+
+root_hash_sig_key_desc <key_description>
+    This is the description of the USER_KEY that the kernel will lookup to get
+    the pkcs7 signature of the roothash. The pkcs7 signature is used to validate
+    the root hash during the creation of the device mapper block device.
+    Verification of roothash depends on the config DM_VERITY_VERIFY_ROOTHASH_SIG
+    being set in the kernel.  The signatures are checked against the builtin
+    trusted keyring by default, or the secondary trusted keyring if
+    DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING is set.  The secondary
+    trusted keyring includes by default the builtin trusted keyring, and it can
+    also gain new certificates at run time if they are signed by a certificate
+    already in the secondary trusted keyring.
+
+try_verify_in_tasklet
+    If verity hashes are in cache and the IO size does not exceed the limit,
+    verify data blocks in bottom half instead of workqueue. This option can
+    reduce IO latency. The size limits can be configured via
+    /sys/module/dm_verity/parameters/use_bh_bytes. The four parameters
+    correspond to limits for IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT,
+    IOPRIO_CLASS_BE and IOPRIO_CLASS_IDLE in turn.
+    For example:
+    <none>,<rt>,<be>,<idle>
+    4096,4096,4096,4096
+
+Theory of operation
+===================
+
+dm-verity is meant to be set up as part of a verified boot path.  This
+may be anything ranging from a boot using tboot or trustedgrub to just
+booting from a known-good device (like a USB drive or CD).
+
+When a dm-verity device is configured, it is expected that the caller
+has been authenticated in some way (cryptographic signatures, etc).
+After instantiation, all hashes will be verified on-demand during
+disk access.  If they cannot be verified up to the root node of the
+tree, the root hash, then the I/O will fail.  This should detect
+tampering with any data on the device and the hash data.
+
+Cryptographic hashes are used to assert the integrity of the device on a
+per-block basis. This allows for a lightweight hash computation on first read
+into the page cache. Block hashes are stored linearly, aligned to the nearest
+block size.
+
+Hash Tree
+---------
+
+Each node in the tree is a cryptographic hash.  If it is a leaf node, the hash
+of some data block on disk is calculated. If it is an intermediary node,
+the hash of a number of child nodes is calculated.
+
+Each entry in the tree is a collection of neighboring nodes that fit in one
+block.  The number is determined based on block_size and the size of the
+selected cryptographic digest algorithm.  The hashes are linearly-ordered in
+this entry and any unaligned trailing space is ignored but included when
+calculating the parent node.
+
+The tree looks something like:
+
+	alg = sha256, num_blocks = 32768, block_size = 4096
+
+::
+
+                                 [   root    ]
+                                /    . . .    \
+                     [entry_0]                 [entry_1]
+                    /  . . .  \                 . . .   \
+         [entry_0_0]   . . .  [entry_0_127]    . . . .  [entry_1_127]
+           / ... \             /   . . .  \             /           \
+     blk_0 ... blk_127  blk_16256   blk_16383      blk_32640 . . . blk_32767
+
+Forward error correction
+------------------------
+
+dm-verity's optional forward error correction (FEC) support adds strong error
+correction capabilities to dm-verity.  It allows systems that would be rendered
+inoperable by errors to continue operating, albeit with reduced performance.
+
+FEC uses Reed-Solomon (RS) codes that are interleaved across the entire
+device(s), allowing long bursts of corrupt or unreadable blocks to be recovered.
+
+dm-verity validates any FEC-corrected block against the wanted hash before using
+it.  Therefore, FEC doesn't affect the security properties of dm-verity.
+
+The integration of FEC with dm-verity provides significant benefits over a
+separate error correction layer:
+
+- dm-verity invokes FEC only when a block's hash doesn't match the wanted hash
+  or the block cannot be read at all.  As a result, FEC doesn't add overhead to
+  the common case where no error occurs.
+
+- dm-verity hashes are also used to identify erasure locations for RS decoding.
+  This allows correcting twice as many errors.
+
+FEC uses an RS(255, k) code where k = 255 - fec_roots.  fec_roots is usually 2.
+This means that each k (usually 253) message bytes have fec_roots (usually 2)
+bytes of parity data added to get a 255-byte codeword.  (Many external sources
+call RS codewords "blocks".  Since dm-verity already uses the term "block" to
+mean something else, we'll use the clearer term "RS codeword".)
+
+FEC checks fec_blocks blocks of message data in total, consisting of:
+
+1. The data blocks from the data device
+2. The hash blocks from the hash device
+3. Optional additional metadata that follows the hash blocks on the hash device
+
+dm-verity assumes that the FEC parity data was computed as if the following
+procedure were followed:
+
+1. Concatenate the message data from the above sources.
+2. Zero-pad to the next multiple of k blocks.  Let msg be the resulting byte
+   array, and msglen its length in bytes.
+3. For 0 <= i < msglen / k (for each RS codeword):
+     a. Select msg[i + j * msglen / k] for 0 <= j < k.
+        Consider these to be the 'k' message bytes of an RS codeword.
+     b. Compute the corresponding 'fec_roots' parity bytes of the RS codeword,
+        and concatenate them to the FEC parity data.
+
+Step 3a interleaves the RS codewords across the entire device using an
+interleaving degree of data_block_size * ceil(fec_blocks / k).  This is the
+maximal interleaving, such that the message data consists of a region containing
+byte 0 of all the RS codewords, then a region containing byte 1 of all the RS
+codewords, and so on up to the region for byte 'k - 1'.  Note that the number of
+codewords is set to a multiple of data_block_size; thus, the regions are
+block-aligned, and there is an implicit zero padding of up to 'k - 1' blocks.
+
+This interleaving allows long bursts of errors to be corrected.  It provides
+much stronger error correction than storage devices typically provide, while
+keeping the space overhead low.
+
+The cost is slow decoding: correcting a single block usually requires reading
+254 extra blocks spread evenly across the device(s).  However, that is
+acceptable because dm-verity uses FEC only when there is actually an error.
+
+The list below contains additional details about the RS codes used by
+dm-verity's FEC.  Userspace programs that generate the parity data need to use
+these parameters for the parity data to match exactly:
+
+- Field used is GF(256)
+- Bytes are mapped to/from GF(256) elements in the natural way, where bits 0
+  through 7 (low-order to high-order) map to the coefficients of x^0 through x^7
+- Field generator polynomial is x^8 + x^4 + x^3 + x^2 + 1
+- The codes used are systematic, BCH-view codes
+- Primitive element alpha is 'x'
+- First consecutive root of code generator polynomial is 'x^0'
+
+On-disk format
+==============
+
+The verity kernel code does not read the verity metadata on-disk header.
+It only reads the hash blocks which directly follow the header.
+It is expected that a user-space tool will verify the integrity of the
+verity header.
+
+Alternatively, the header can be omitted and the dmsetup parameters can
+be passed via the kernel command-line in a rooted chain of trust where
+the command-line is verified.
+
+Directly following the header (and with sector number padded to the next hash
+block boundary) are the hash blocks which are stored a depth at a time
+(starting from the root), sorted in order of increasing index.
+
+The full specification of kernel parameters and on-disk metadata format
+is available at the cryptsetup project's wiki page
+
+  https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
+
+Status
+======
+1. V (for Valid) is returned if every check performed so far was valid.
+   If any check failed, C (for Corruption) is returned.
+2. Number of corrected blocks by Forward Error Correction.
+   '-' if Forward Error Correction is not enabled.
+
+Example
+=======
+Set up a device::
+
+  # dmsetup create vroot --readonly --table \
+    "0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\
+    "4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
+    "1234000000000000000000000000000000000000000000000000000000000000"
+
+A command line tool veritysetup is available to compute or verify
+the hash tree or activate the kernel device. This is available from
+the cryptsetup upstream repository https://gitlab.com/cryptsetup/cryptsetup/
+(as a libcryptsetup extension).
+
+Create hash on the device::
+
+  # veritysetup format /dev/sda1 /dev/sda2
+  ...
+  Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
+
+Activate the device::
+
+  # veritysetup create vroot /dev/sda1 /dev/sda2 \
+    4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
diff --git a/Documentation/admin-guide/device-mapper/writecache.rst b/Documentation/admin-guide/device-mapper/writecache.rst
new file mode 100644
index 000000000..60c16b7fd
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/writecache.rst
@@ -0,0 +1,114 @@
+=================
+Writecache target
+=================
+
+The writecache target caches writes on persistent memory or on SSD. It
+doesn't cache reads because reads are supposed to be cached in page cache
+in normal RAM.
+
+When the device is constructed, the first sector should be zeroed or the
+first sector should contain valid superblock from previous invocation.
+
+Constructor parameters:
+
+1. type of the cache device - "p" or "s"
+	- p - persistent memory
+	- s - SSD
+2. the underlying device that will be cached
+3. the cache device
+4. block size (4096 is recommended; the maximum block size is the page
+   size)
+5. the number of optional parameters (the parameters with an argument
+   count as two)
+
+	start_sector n		(default: 0)
+		offset from the start of cache device in 512-byte sectors
+	high_watermark n	(default: 50)
+		start writeback when the number of used blocks reach this
+		watermark
+	low_watermark x		(default: 45)
+		stop writeback when the number of used blocks drops below
+		this watermark
+	writeback_jobs n	(default: unlimited)
+		limit the number of blocks that are in flight during
+		writeback. Setting this value reduces writeback
+		throughput, but it may improve latency of read requests
+	autocommit_blocks n	(default: 64 for pmem, 65536 for ssd)
+		when the application writes this amount of blocks without
+		issuing the FLUSH request, the blocks are automatically
+		committed
+	autocommit_time ms	(default: 1000)
+		autocommit time in milliseconds. The data is automatically
+		committed if this time passes and no FLUSH request is
+		received
+	fua			(by default on)
+		applicable only to persistent memory - use the FUA flag
+		when writing data from persistent memory back to the
+		underlying device
+	nofua
+		applicable only to persistent memory - don't use the FUA
+		flag when writing back data and send the FLUSH request
+		afterwards
+
+		- some underlying devices perform better with fua, some
+		  with nofua. The user should test it
+	cleaner
+		when this option is activated (either in the constructor
+		arguments or by a message), the cache will not promote
+		new writes (however, writes to already cached blocks are
+		promoted, to avoid data corruption due to misordered
+		writes) and it will gradually writeback any cached
+		data. The userspace can then monitor the cleaning
+		process with "dmsetup status". When the number of cached
+		blocks drops to zero, userspace can unload the
+		dm-writecache target and replace it with dm-linear or
+		other targets.
+	max_age n
+		specifies the maximum age of a block in milliseconds. If
+		a block is stored in the cache for too long, it will be
+		written to the underlying device and cleaned up.
+	metadata_only
+		only metadata is promoted to the cache. This option
+		improves performance for heavier REQ_META workloads.
+	pause_writeback n	(default: 3000)
+		pause writeback if there was some write I/O redirected to
+		the origin volume in the last n milliseconds
+
+Status:
+
+1. error indicator - 0 if there was no error, otherwise error number
+2. the number of blocks
+3. the number of free blocks
+4. the number of blocks under writeback
+5. the number of read blocks
+6. the number of read blocks that hit the cache
+7. the number of write blocks
+8. the number of write blocks that hit uncommitted block
+9. the number of write blocks that hit committed block
+10. the number of write blocks that bypass the cache
+11. the number of write blocks that are allocated in the cache
+12. the number of write requests that are blocked on the freelist
+13. the number of flush requests
+14. the number of discarded blocks
+
+Messages:
+	flush
+		Flush the cache device. The message returns successfully
+		if the cache device was flushed without an error
+	flush_on_suspend
+		Flush the cache device on next suspend. Use this message
+		when you are going to remove the cache device. The proper
+		sequence for removing the cache device is:
+
+		1. send the "flush_on_suspend" message
+		2. load an inactive table with a linear target that maps
+		   to the underlying device
+		3. suspend the device
+		4. ask for status and verify that there are no errors
+		5. resume the device, so that it will use the linear
+		   target
+		6. the cache device is now inactive and it can be deleted
+	cleaner
+		See above "cleaner" constructor documentation.
+	clear_stats
+		Clear the statistics that are reported on the status line
diff --git a/Documentation/admin-guide/device-mapper/zero.rst b/Documentation/admin-guide/device-mapper/zero.rst
new file mode 100644
index 000000000..11fb5cf45
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/zero.rst
@@ -0,0 +1,37 @@
+=======
+dm-zero
+=======
+
+Device-Mapper's "zero" target provides a block-device that always returns
+zero'd data on reads and silently drops writes. This is similar behavior to
+/dev/zero, but as a block-device instead of a character-device.
+
+Dm-zero has no target-specific parameters.
+
+One very interesting use of dm-zero is for creating "sparse" devices in
+conjunction with dm-snapshot. A sparse device reports a device-size larger
+than the amount of actual storage space available for that device. A user can
+write data anywhere within the sparse device and read it back like a normal
+device. Reads to previously unwritten areas will return a zero'd buffer. When
+enough data has been written to fill up the actual storage space, the sparse
+device is deactivated. This can be very useful for testing device and
+filesystem limitations.
+
+To create a sparse device, start by creating a dm-zero device that's the
+desired size of the sparse device. For this example, we'll assume a 10TB
+sparse device::
+
+  TEN_TERABYTES=`expr 10 \* 1024 \* 1024 \* 1024 \* 2`   # 10 TB in sectors
+  echo "0 $TEN_TERABYTES zero" | dmsetup create zero1
+
+Then create a snapshot of the zero device, using any available block-device as
+the COW device. The size of the COW device will determine the amount of real
+space available to the sparse device. For this example, we'll assume /dev/sdb1
+is an available 10GB partition::
+
+  echo "0 $TEN_TERABYTES snapshot /dev/mapper/zero1 /dev/sdb1 p 128" | \
+     dmsetup create sparse1
+
+This will create a 10TB sparse device called /dev/mapper/sparse1 that has
+10GB of actual storage space available. If more than 10GB of data is written
+to this device, it will start returning I/O errors.
diff --git a/Documentation/admin-guide/devices.rst b/Documentation/admin-guide/devices.rst
new file mode 100644
index 000000000..b103ba527
--- /dev/null
+++ b/Documentation/admin-guide/devices.rst
@@ -0,0 +1,270 @@
+.. _admin_devices:
+
+Linux allocated devices (4.x+ version)
+======================================
+
+This list is the Linux Device List, the official registry of allocated
+device numbers and ``/dev`` directory nodes for the Linux operating
+system.
+
+The version of this document at lanana.org is no longer maintained.  This
+version in the mainline Linux kernel is the master document.  Updates
+shall be sent as patches to the kernel maintainers (see the
+:ref:`Documentation/process/submitting-patches.rst <submittingpatches>` document).
+Specifically explore the sections titled "CHAR and MISC DRIVERS", and
+"BLOCK LAYER" in the MAINTAINERS file to find the right maintainers
+to involve for character and block devices.
+
+This document is included by reference into the Filesystem Hierarchy
+Standard (FHS).	 The FHS is available from https://www.pathname.com/fhs/.
+
+Allocations marked (68k/Amiga) apply to Linux/68k on the Amiga
+platform only.	Allocations marked (68k/Atari) apply to Linux/68k on
+the Atari platform only.
+
+This document is in the public domain.	The authors requests, however,
+that semantically altered versions are not distributed without
+permission of the authors, assuming the authors can be contacted without
+an unreasonable effort.
+
+
+.. attention::
+
+  DEVICE DRIVERS AUTHORS PLEASE READ THIS
+
+  Linux now has extensive support for dynamic allocation of device numbering
+  and can use ``sysfs`` and ``udev`` (``systemd``) to handle the naming needs.
+  There are still some exceptions in the serial and boot device area. Before
+  asking   for a device number make sure you actually need one.
+
+  To have a major number allocated, or a minor number in situations
+  where that applies (e.g. busmice), please submit a patch and send to
+  the authors as indicated above.
+
+  Keep the description of the device *in the same format
+  as this list*. The reason for this is that it is the only way we have
+  found to ensure we have all the requisite information to publish your
+  device and avoid conflicts.
+
+  Finally, sometimes we have to play "namespace police."  Please don't be
+  offended.  We often get submissions for ``/dev`` names that would be bound
+  to cause conflicts down the road.  We are trying to avoid getting in a
+  situation where we would have to suffer an incompatible forward
+  change.  Therefore, please consult with us **before** you make your
+  device names and numbers in any way public, at least to the point
+  where it would be at all difficult to get them changed.
+
+  Your cooperation is appreciated.
+
+.. include:: devices.txt
+   :literal:
+
+Additional ``/dev/`` directory entries
+--------------------------------------
+
+This section details additional entries that should or may exist in
+the /dev directory.  It is preferred that symbolic links use the same
+form (absolute or relative) as is indicated here.  Links are
+classified as "hard" or "symbolic" depending on the preferred type of
+link; if possible, the indicated type of link should be used.
+
+Compulsory links
+++++++++++++++++
+
+These links should exist on all systems:
+
+=============== =============== =============== ===============================
+/dev/fd		/proc/self/fd	symbolic	File descriptors
+/dev/stdin	fd/0		symbolic	stdin file descriptor
+/dev/stdout	fd/1		symbolic	stdout file descriptor
+/dev/stderr	fd/2		symbolic	stderr file descriptor
+/dev/nfsd	socksys		symbolic	Required by iBCS-2
+/dev/X0R	null		symbolic	Required by iBCS-2
+=============== =============== =============== ===============================
+
+Note: ``/dev/X0R`` is <letter X>-<digit 0>-<letter R>.
+
+Recommended links
++++++++++++++++++
+
+It is recommended that these links exist on all systems:
+
+
+=============== =============== =============== ===============================
+/dev/core	/proc/kcore	symbolic	Backward compatibility
+/dev/ramdisk	ram0		symbolic	Backward compatibility
+/dev/ftape	qft0		symbolic	Backward compatibility
+/dev/bttv0	video0		symbolic	Backward compatibility
+/dev/radio	radio0		symbolic	Backward compatibility
+/dev/i2o*	/dev/i2o/*	symbolic	Backward compatibility
+=============== =============== =============== ===============================
+
+Suggested earlier ``/dev/scd?`` alternative names for ``/dev/sr?``
+CD-ROM and other optical drives (using SCSI commands) were removed
+in ``udev`` version 174 that was released in 2011.
+
+Locally defined links
++++++++++++++++++++++
+
+The following links may be established locally to conform to the
+configuration of the system.  This is merely a tabulation of existing
+practice, and does not constitute a recommendation.  However, if they
+exist, they should have the following uses.
+
+=============== =============== =============== ===============================
+/dev/mouse	mouse port	symbolic	Current mouse device
+/dev/tape	tape device	symbolic	Current tape device
+/dev/cdrom	CD-ROM device	symbolic	Current CD-ROM device
+/dev/scanner	scanner		symbolic	Current scanner device
+/dev/modem	modem port	symbolic	Current dialout device
+/dev/root	root device	symbolic	Current root filesystem
+/dev/swap	swap device	symbolic	Current swap device
+=============== =============== =============== ===============================
+
+``/dev/modem`` should not be used for a modem which supports dialin as
+well as dialout, as it tends to cause lock file problems.  If it
+exists, ``/dev/modem`` should point to the appropriate primary TTY device
+(the use of the alternate callout devices is deprecated).
+
+For SCSI devices, ``/dev/tape`` and ``/dev/cdrom`` should point to the
+*cooked* devices (``/dev/st*`` and ``/dev/sr*``, respectively), whereas
+``/dev/scanner`` should point to the appropriate generic
+SCSI device (``/dev/sg*``).
+
+``/dev/mouse`` may point to a primary serial TTY device, a hardware mouse
+device, or a socket for a mouse driver program (e.g. ``/dev/gpmdata``).
+
+Sockets and pipes
++++++++++++++++++
+
+Non-transient sockets and named pipes may exist in /dev.  Common entries are:
+
+=============== =============== ===============================================
+/dev/printer	socket		lpd local socket
+/dev/log	socket		syslog local socket
+/dev/gpmdata	socket		gpm mouse multiplexer
+=============== =============== ===============================================
+
+Mount points
+++++++++++++
+
+The following names are reserved for mounting special filesystems
+under /dev.  These special filesystems provide kernel interfaces that
+cannot be provided with standard device nodes.
+
+=============== =============== ===============================================
+/dev/pts	devpts		PTY slave filesystem
+/dev/shm	tmpfs		POSIX shared memory maintenance access
+=============== =============== ===============================================
+
+Terminal devices
+----------------
+
+Terminal, or TTY devices are a special class of character devices.  A
+terminal device is any device that could act as a controlling terminal
+for a session; this includes virtual consoles, serial ports, and
+pseudoterminals (PTYs).
+
+All terminal devices share a common set of capabilities known as line
+disciplines; these include the common terminal line discipline as well
+as SLIP and PPP modes.
+
+All terminal devices are named similarly; this section explains the
+naming and use of the various types of TTYs.  Note that the naming
+conventions include several historical warts; some of these are
+Linux-specific, some were inherited from other systems, and some
+reflect Linux outgrowing a borrowed convention.
+
+A hash mark (``#``) in a device name is used here to indicate a decimal
+number without leading zeroes.
+
+Virtual consoles and the console device
++++++++++++++++++++++++++++++++++++++++
+
+Virtual consoles are full-screen terminal displays on the system video
+monitor.  Virtual consoles are named ``/dev/tty#``, with numbering
+starting at ``/dev/tty1``; ``/dev/tty0`` is the current virtual console.
+``/dev/tty0`` is the device that should be used to access the system video
+card on those architectures for which the frame buffer devices
+(``/dev/fb*``) are not applicable. Do not use ``/dev/console``
+for this purpose.
+
+The console device, ``/dev/console``, is the device to which system
+messages should be sent, and on which logins should be permitted in
+single-user mode.  Starting with Linux 2.1.71, ``/dev/console`` is managed
+by the kernel; for previous versions it should be a symbolic link to
+either ``/dev/tty0``, a specific virtual console such as ``/dev/tty1``, or to
+a serial port primary (``tty*``, not ``cu*``) device, depending on the
+configuration of the system.
+
+Serial ports
+++++++++++++
+
+Serial ports are RS-232 serial ports and any device which simulates
+one, either in hardware (such as internal modems) or in software (such
+as the ISDN driver.)  Under Linux, each serial ports has two device
+names, the primary or callin device and the alternate or callout one.
+Each kind of device is indicated by a different letter.	 For any
+letter X, the names of the devices are ``/dev/ttyX#`` and ``/dev/cux#``,
+respectively; for historical reasons, ``/dev/ttyS#`` and ``/dev/ttyC#``
+correspond to ``/dev/cua#`` and ``/dev/cub#``. In the future, it should be
+expected that multiple letters will be used; all letters will be upper
+case for the "tty" device (e.g. ``/dev/ttyDP#``) and lower case for the
+"cu" device (e.g. ``/dev/cudp#``).
+
+The names ``/dev/ttyQ#`` and ``/dev/cuq#`` are reserved for local use.
+
+The alternate devices provide for kernel-based exclusion and somewhat
+different defaults than the primary devices.  Their main purpose is to
+allow the use of serial ports with programs with no inherent or broken
+support for serial ports.  Their use is deprecated, and they may be
+removed from a future version of Linux.
+
+Arbitration of serial ports is provided by the use of lock files with
+the names ``/var/lock/LCK..ttyX#``. The contents of the lock file should
+be the PID of the locking process as an ASCII number.
+
+It is common practice to install links such as /dev/modem
+which point to serial ports.  In order to ensure proper locking in the
+presence of these links, it is recommended that software chase
+symlinks and lock all possible names; additionally, it is recommended
+that a lock file be installed with the corresponding alternate
+device.	 In order to avoid deadlocks, it is recommended that the locks
+are acquired in the following order, and released in the reverse:
+
+	1. The symbolic link name, if any (``/var/lock/LCK..modem``)
+	2. The "tty" name (``/var/lock/LCK..ttyS2``)
+	3. The alternate device name (``/var/lock/LCK..cua2``)
+
+In the case of nested symbolic links, the lock files should be
+installed in the order the symlinks are resolved.
+
+Under no circumstances should an application hold a lock while waiting
+for another to be released.  In addition, applications which attempt
+to create lock files for the corresponding alternate device names
+should take into account the possibility of being used on a non-serial
+port TTY, for which no alternate device would exist.
+
+Pseudoterminals (PTYs)
+++++++++++++++++++++++
+
+Pseudoterminals, or PTYs, are used to create login sessions or provide
+other capabilities requiring a TTY line discipline (including SLIP or
+PPP capability) to arbitrary data-generation processes.	 Each PTY has
+a master side, named ``/dev/pty[p-za-e][0-9a-f]``, and a slave side, named
+``/dev/tty[p-za-e][0-9a-f]``.  The kernel arbitrates the use of PTYs by
+allowing each master side to be opened only once.
+
+Once the master side has been opened, the corresponding slave device
+can be used in the same manner as any TTY device.  The master and
+slave devices are connected by the kernel, generating the equivalent
+of a bidirectional pipe with TTY capabilities.
+
+Recent versions of the Linux kernels and GNU libc contain support for
+the System V/Unix98 naming scheme for PTYs, which assigns a common
+device, ``/dev/ptmx``, to all the masters (opening it will automatically
+give you a previously unassigned PTY) and a subdirectory, ``/dev/pts``,
+for the slaves; the slaves are named with decimal integers (``/dev/pts/#``
+in our notation).  This removes the problem of exhausting the
+namespace and enables the kernel to automatically create the device
+nodes for the slaves on demand using the "devpts" filesystem.
diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt
new file mode 100644
index 000000000..f54439967
--- /dev/null
+++ b/Documentation/admin-guide/devices.txt
@@ -0,0 +1,3081 @@
+   0		Unnamed devices (e.g. non-device mounts)
+		  0 = reserved as null device number
+		See block major 144, 145, 146 for expansion areas.
+
+   1 char	Memory devices
+		  1 = /dev/mem		Physical memory access
+		  2 = /dev/kmem		OBSOLETE - replaced by /proc/kcore
+		  3 = /dev/null		Null device
+		  4 = /dev/port		I/O port access
+		  5 = /dev/zero		Null byte source
+		  6 = /dev/core		OBSOLETE - replaced by /proc/kcore
+		  7 = /dev/full		Returns ENOSPC on write
+		  8 = /dev/random	Nondeterministic random number gen.
+		  9 = /dev/urandom	Faster, less secure random number gen.
+		 10 = /dev/aio		Asynchronous I/O notification interface
+		 11 = /dev/kmsg		Writes to this come out as printk's, reads
+					export the buffered printk records.
+		 12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore
+
+   1 block	RAM disk
+		  0 = /dev/ram0		First RAM disk
+		  1 = /dev/ram1		Second RAM disk
+		    ...
+		250 = /dev/initrd	Initial RAM disk
+
+		Older kernels had /dev/ramdisk (1, 1) here.
+		/dev/initrd refers to a RAM disk which was preloaded
+		by the boot loader; newer kernels use /dev/ram0 for
+		the initrd.
+
+   2 char	Pseudo-TTY masters
+		  0 = /dev/ptyp0	First PTY master
+		  1 = /dev/ptyp1	Second PTY master
+		    ...
+		255 = /dev/ptyef	256th PTY master
+
+		Pseudo-tty's are named as follows:
+		* Masters are "pty", slaves are "tty";
+		* the fourth letter is one of pqrstuvwxyzabcde indicating
+		  the 1st through 16th series of 16 pseudo-ttys each, and
+		* the fifth letter is one of 0123456789abcdef indicating
+		  the position within the series.
+
+		These are the old-style (BSD) PTY devices; Unix98
+		devices are on major 128 and above and use the PTY
+		master multiplex (/dev/ptmx) to acquire a PTY on
+		demand.
+
+   2 block	Floppy disks
+		  0 = /dev/fd0		Controller 0, drive 0, autodetect
+		  1 = /dev/fd1		Controller 0, drive 1, autodetect
+		  2 = /dev/fd2		Controller 0, drive 2, autodetect
+		  3 = /dev/fd3		Controller 0, drive 3, autodetect
+		128 = /dev/fd4		Controller 1, drive 0, autodetect
+		129 = /dev/fd5		Controller 1, drive 1, autodetect
+		130 = /dev/fd6		Controller 1, drive 2, autodetect
+		131 = /dev/fd7		Controller 1, drive 3, autodetect
+
+		To specify format, add to the autodetect device number:
+		  0 = /dev/fd?		Autodetect format
+		  4 = /dev/fd?d360	5.25"  360K in a 360K  drive(1)
+		 20 = /dev/fd?h360	5.25"  360K in a 1200K drive(1)
+		 48 = /dev/fd?h410	5.25"  410K in a 1200K drive
+		 64 = /dev/fd?h420	5.25"  420K in a 1200K drive
+		 24 = /dev/fd?h720	5.25"  720K in a 1200K drive
+		 80 = /dev/fd?h880	5.25"  880K in a 1200K drive(1)
+		  8 = /dev/fd?h1200	5.25" 1200K in a 1200K drive(1)
+		 40 = /dev/fd?h1440	5.25" 1440K in a 1200K drive(1)
+		 56 = /dev/fd?h1476	5.25" 1476K in a 1200K drive
+		 72 = /dev/fd?h1494	5.25" 1494K in a 1200K drive
+		 92 = /dev/fd?h1600	5.25" 1600K in a 1200K drive(1)
+
+		 12 = /dev/fd?u360	3.5"   360K Double Density(2)
+		 16 = /dev/fd?u720	3.5"   720K Double Density(1)
+		120 = /dev/fd?u800	3.5"   800K Double Density(2)
+		 52 = /dev/fd?u820	3.5"   820K Double Density
+		 68 = /dev/fd?u830	3.5"   830K Double Density
+		 84 = /dev/fd?u1040	3.5"  1040K Double Density(1)
+		 88 = /dev/fd?u1120	3.5"  1120K Double Density(1)
+		 28 = /dev/fd?u1440	3.5"  1440K High Density(1)
+		124 = /dev/fd?u1600	3.5"  1600K High Density(1)
+		 44 = /dev/fd?u1680	3.5"  1680K High Density(3)
+		 60 = /dev/fd?u1722	3.5"  1722K High Density
+		 76 = /dev/fd?u1743	3.5"  1743K High Density
+		 96 = /dev/fd?u1760	3.5"  1760K High Density
+		116 = /dev/fd?u1840	3.5"  1840K High Density(3)
+		100 = /dev/fd?u1920	3.5"  1920K High Density(1)
+		 32 = /dev/fd?u2880	3.5"  2880K Extra Density(1)
+		104 = /dev/fd?u3200	3.5"  3200K Extra Density
+		108 = /dev/fd?u3520	3.5"  3520K Extra Density
+		112 = /dev/fd?u3840	3.5"  3840K Extra Density(1)
+
+		 36 = /dev/fd?CompaQ	Compaq 2880K drive; obsolete?
+
+		(1) Autodetectable format
+		(2) Autodetectable format in a Double Density (720K) drive only
+		(3) Autodetectable format in a High Density (1440K) drive only
+
+		NOTE: The letter in the device name (d, q, h or u)
+		signifies the type of drive: 5.25" Double Density (d),
+		5.25" Quad Density (q), 5.25" High Density (h) or 3.5"
+		(any model, u).	 The use of the capital letters D, H
+		and E for the 3.5" models have been deprecated, since
+		the drive type is insignificant for these devices.
+
+   3 char	Pseudo-TTY slaves
+		  0 = /dev/ttyp0	First PTY slave
+		  1 = /dev/ttyp1	Second PTY slave
+		    ...
+		255 = /dev/ttyef	256th PTY slave
+
+		These are the old-style (BSD) PTY devices; Unix98
+		devices are on major 136 and above.
+
+   3 block	First MFM, RLL and IDE hard disk/CD-ROM interface
+		  0 = /dev/hda		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdb		Slave: whole disk (or CD-ROM)
+
+		For partitions, add to the whole disk device number:
+		  0 = /dev/hd?		Whole disk
+		  1 = /dev/hd?1		First partition
+		  2 = /dev/hd?2		Second partition
+		    ...
+		 63 = /dev/hd?63	63rd partition
+
+		For Linux/i386, partitions 1-4 are the primary
+		partitions, and 5 and above are logical partitions.
+		Other versions of Linux use partitioning schemes
+		appropriate to their respective architectures.
+
+   4 char	TTY devices
+		  0 = /dev/tty0		Current virtual console
+
+		  1 = /dev/tty1		First virtual console
+		    ...
+		 63 = /dev/tty63	63rd virtual console
+		 64 = /dev/ttyS0	First UART serial port
+		    ...
+		255 = /dev/ttyS191	192nd UART serial port
+
+		UART serial ports refer to 8250/16450/16550 series devices.
+
+		Older versions of the Linux kernel used this major
+		number for BSD PTY devices.  As of Linux 2.1.115, this
+		is no longer supported.	 Use major numbers 2 and 3.
+
+   4 block	Aliases for dynamically allocated major devices to be used
+		when its not possible to create the real device nodes
+		because the root filesystem is mounted read-only.
+
+		   0 = /dev/root
+
+   5 char	Alternate TTY devices
+		  0 = /dev/tty		Current TTY device
+		  1 = /dev/console	System console
+		  2 = /dev/ptmx		PTY master multiplex
+		  3 = /dev/ttyprintk	User messages via printk TTY device
+		 64 = /dev/cua0		Callout device for ttyS0
+		    ...
+		255 = /dev/cua191	Callout device for ttyS191
+
+		(5,1) is /dev/console starting with Linux 2.1.71.  See
+		the section on terminal devices for more information
+		on /dev/console.
+
+   6 char	Parallel printer devices
+		  0 = /dev/lp0		Parallel printer on parport0
+		  1 = /dev/lp1		Parallel printer on parport1
+		    ...
+
+		Current Linux kernels no longer have a fixed mapping
+		between parallel ports and I/O addresses.  Instead,
+		they are redirected through the parport multiplex layer.
+
+   7 char	Virtual console capture devices
+		  0 = /dev/vcs		Current vc text (glyph) contents
+		  1 = /dev/vcs1		tty1 text (glyph) contents
+		    ...
+		 63 = /dev/vcs63	tty63 text (glyph) contents
+		 64 = /dev/vcsu		Current vc text (unicode) contents
+		65 = /dev/vcsu1		tty1 text (unicode) contents
+		    ...
+		127 = /dev/vcsu63	tty63 text (unicode) contents
+		128 = /dev/vcsa		Current vc text/attribute (glyph) contents
+		129 = /dev/vcsa1	tty1 text/attribute (glyph) contents
+		    ...
+		191 = /dev/vcsa63	tty63 text/attribute (glyph) contents
+
+		NOTE: These devices permit both read and write access.
+
+   7 block	Loopback devices
+		  0 = /dev/loop0	First loop device
+		  1 = /dev/loop1	Second loop device
+		    ...
+
+		The loop devices are used to mount filesystems not
+		associated with block devices.	The binding to the
+		loop devices is handled by mount(8) or losetup(8).
+
+   8 block	SCSI disk devices (0-15)
+		  0 = /dev/sda		First SCSI disk whole disk
+		 16 = /dev/sdb		Second SCSI disk whole disk
+		 32 = /dev/sdc		Third SCSI disk whole disk
+		    ...
+		240 = /dev/sdp		Sixteenth SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+   9 char	SCSI tape devices
+		  0 = /dev/st0		First SCSI tape, mode 0
+		  1 = /dev/st1		Second SCSI tape, mode 0
+		    ...
+		 32 = /dev/st0l		First SCSI tape, mode 1
+		 33 = /dev/st1l		Second SCSI tape, mode 1
+		    ...
+		 64 = /dev/st0m		First SCSI tape, mode 2
+		 65 = /dev/st1m		Second SCSI tape, mode 2
+		    ...
+		 96 = /dev/st0a		First SCSI tape, mode 3
+		 97 = /dev/st1a		Second SCSI tape, mode 3
+		      ...
+		128 = /dev/nst0		First SCSI tape, mode 0, no rewind
+		129 = /dev/nst1		Second SCSI tape, mode 0, no rewind
+		    ...
+		160 = /dev/nst0l	First SCSI tape, mode 1, no rewind
+		161 = /dev/nst1l	Second SCSI tape, mode 1, no rewind
+		    ...
+		192 = /dev/nst0m	First SCSI tape, mode 2, no rewind
+		193 = /dev/nst1m	Second SCSI tape, mode 2, no rewind
+		    ...
+		224 = /dev/nst0a	First SCSI tape, mode 3, no rewind
+		225 = /dev/nst1a	Second SCSI tape, mode 3, no rewind
+		    ...
+
+		"No rewind" refers to the omission of the default
+		automatic rewind on device close.  The MTREW or MTOFFL
+		ioctl()'s can be used to rewind the tape regardless of
+		the device used to access it.
+
+   9 block	Metadisk (RAID) devices
+		  0 = /dev/md0		First metadisk group
+		  1 = /dev/md1		Second metadisk group
+		    ...
+
+		The metadisk driver is used to span a
+		filesystem across multiple physical disks.
+
+  10 char	Non-serial mice, misc features
+		  0 = /dev/logibm	Logitech bus mouse
+		  1 = /dev/psaux	PS/2-style mouse port
+		  2 = /dev/inportbm	Microsoft Inport bus mouse
+		  3 = /dev/atibm	ATI XL bus mouse
+		  4 = /dev/jbm		J-mouse
+		  4 = /dev/amigamouse	Amiga mouse (68k/Amiga)
+		  5 = /dev/atarimouse	Atari mouse
+		  6 = /dev/sunmouse	Sun mouse
+		  7 = /dev/amigamouse1	Second Amiga mouse
+		  8 = /dev/smouse	Simple serial mouse driver
+		  9 = /dev/pc110pad	IBM PC-110 digitizer pad
+		 10 = /dev/adbmouse	Apple Desktop Bus mouse
+		 11 = /dev/vrtpanel	Vr41xx embedded touch panel
+		 13 = /dev/vpcmouse	Connectix Virtual PC Mouse
+		 14 = /dev/touchscreen/ucb1x00  UCB 1x00 touchscreen
+		 15 = /dev/touchscreen/mk712	MK712 touchscreen
+		128 = /dev/beep		Fancy beep device
+		129 =
+		130 = /dev/watchdog	Watchdog timer port
+		131 = /dev/temperature	Machine internal temperature
+		132 = /dev/hwtrap	Hardware fault trap
+		133 = /dev/exttrp	External device trap
+		134 = /dev/apm_bios	Advanced Power Management BIOS
+		135 = /dev/rtc		Real Time Clock
+		137 = /dev/vhci		Bluetooth virtual HCI driver
+		139 = /dev/openprom	SPARC OpenBoot PROM
+		140 = /dev/relay8	Berkshire Products Octal relay card
+		141 = /dev/relay16	Berkshire Products ISO-16 relay card
+		142 =
+		143 = /dev/pciconf	PCI configuration space
+		144 = /dev/nvram	Non-volatile configuration RAM
+		145 = /dev/hfmodem	Soundcard shortwave modem control
+		146 = /dev/graphics	Linux/SGI graphics device
+		147 = /dev/opengl	Linux/SGI OpenGL pipe
+		148 = /dev/gfx		Linux/SGI graphics effects device
+		149 = /dev/input/mouse	Linux/SGI Irix emulation mouse
+		150 = /dev/input/keyboard Linux/SGI Irix emulation keyboard
+		151 = /dev/led		Front panel LEDs
+		152 = /dev/kpoll	Kernel Poll Driver
+		153 = /dev/mergemem	Memory merge device
+		154 = /dev/pmu		Macintosh PowerBook power manager
+		155 =
+		156 = /dev/lcd		Front panel LCD display
+		158 = /dev/nwbutton	Netwinder external button
+		159 = /dev/nwdebug	Netwinder debug interface
+		160 = /dev/nwflash	Netwinder flash memory
+		161 = /dev/userdma	User-space DMA access
+		162 = /dev/smbus	System Management Bus
+		163 = /dev/lik		Logitech Internet Keyboard
+		164 = /dev/ipmo		Intel Intelligent Platform Management
+		165 = /dev/vmmon	VMware virtual machine monitor
+		166 = /dev/i2o/ctl	I2O configuration manager
+		167 = /dev/specialix_sxctl Specialix serial control
+		168 = /dev/tcldrv	Technology Concepts serial control
+		169 = /dev/specialix_rioctl Specialix RIO serial control
+		170 = /dev/thinkpad/thinkpad	IBM Thinkpad devices
+		171 = /dev/srripc	QNX4 API IPC manager
+		172 = /dev/usemaclone	Semaphore clone device
+		173 = /dev/ipmikcs	Intelligent Platform Management
+		174 = /dev/uctrl	SPARCbook 3 microcontroller
+		175 = /dev/agpgart	AGP Graphics Address Remapping Table
+		176 = /dev/gtrsc	Gorgy Timing radio clock
+		177 = /dev/cbm		Serial CBM bus
+		178 = /dev/jsflash	JavaStation OS flash SIMM
+		179 = /dev/xsvc		High-speed shared-mem/semaphore service
+		180 = /dev/vrbuttons	Vr41xx button input device
+		181 = /dev/toshiba	Toshiba laptop SMM support
+		182 = /dev/perfctr	Performance-monitoring counters
+		183 = /dev/hwrng	Generic random number generator
+		184 = /dev/cpu/microcode CPU microcode update interface
+		186 = /dev/atomicps	Atomic snapshot of process state data
+		187 = /dev/irnet	IrNET device
+		188 = /dev/smbusbios	SMBus BIOS
+		189 = /dev/ussp_ctl	User space serial port control
+		190 = /dev/crash	Mission Critical Linux crash dump facility
+		191 = /dev/pcl181	<information missing>
+		192 = /dev/nas_xbus	NAS xbus LCD/buttons access
+		193 = /dev/d7s		SPARC 7-segment display
+		194 = /dev/zkshim	Zero-Knowledge network shim control
+		195 = /dev/elographics/e2201	Elographics touchscreen E271-2201
+		196 = /dev/vfio/vfio	VFIO userspace driver interface
+		197 = /dev/pxa3xx-gcu	PXA3xx graphics controller unit driver
+		198 = /dev/sexec	Signed executable interface
+		199 = /dev/scanners/cuecat :CueCat barcode scanner
+		200 = /dev/net/tun	TAP/TUN network device
+		201 = /dev/button/gulpb	Transmeta GULP-B buttons
+		202 = /dev/emd/ctl	Enhanced Metadisk RAID (EMD) control
+		203 = /dev/cuse		Cuse (character device in user-space)
+		204 = /dev/video/em8300		EM8300 DVD decoder control
+		205 = /dev/video/em8300_mv	EM8300 DVD decoder video
+		206 = /dev/video/em8300_ma	EM8300 DVD decoder audio
+		207 = /dev/video/em8300_sp	EM8300 DVD decoder subpicture
+		208 = /dev/compaq/cpqphpc	Compaq PCI Hot Plug Controller
+		209 = /dev/compaq/cpqrid	Compaq Remote Insight Driver
+		210 = /dev/impi/bt	IMPI coprocessor block transfer
+		211 = /dev/impi/smic	IMPI coprocessor stream interface
+		212 = /dev/watchdogs/0	First watchdog device
+		213 = /dev/watchdogs/1	Second watchdog device
+		214 = /dev/watchdogs/2	Third watchdog device
+		215 = /dev/watchdogs/3	Fourth watchdog device
+		216 = /dev/fujitsu/apanel	Fujitsu/Siemens application panel
+		217 = /dev/ni/natmotn		National Instruments Motion
+		218 = /dev/kchuid	Inter-process chuid control
+		219 =
+		220 = /dev/mptctl	Message passing technology (MPT) control
+		221 = /dev/mvista/hssdsi	Montavista PICMG hot swap system driver
+		222 = /dev/mvista/hasi		Montavista PICMG high availability
+		223 = /dev/input/uinput		User level driver support for input
+		224 = /dev/tpm		TCPA TPM driver
+		225 = /dev/pps		Pulse Per Second driver
+		226 = /dev/systrace	Systrace device
+		227 = /dev/mcelog	X86_64 Machine Check Exception driver
+		228 = /dev/hpet		HPET driver
+		229 = /dev/fuse		Fuse (virtual filesystem in user-space)
+		230 = /dev/midishare	MidiShare driver
+		231 = /dev/snapshot	System memory snapshot device
+		232 = /dev/kvm		Kernel-based virtual machine (hardware virtualization extensions)
+		233 = /dev/kmview	View-OS A process with a view
+		234 = /dev/btrfs-control	Btrfs control device
+		235 = /dev/autofs	Autofs control device
+		236 = /dev/mapper/control	Device-Mapper control device
+		237 = /dev/loop-control Loopback control device
+		238 = /dev/vhost-net	Host kernel accelerator for virtio net
+		239 = /dev/uhid		User-space I/O driver support for HID subsystem
+		240 = /dev/userio	Serio driver testing device
+		241 = /dev/vhost-vsock	Host kernel driver for virtio vsock
+		242 = /dev/rfkill	Turning off radio transmissions (rfkill)
+
+		243-254			Reserved for local use
+		255			Reserved for MISC_DYNAMIC_MINOR
+
+  11 char	Raw keyboard device	(Linux/SPARC only)
+		  0 = /dev/kbd		Raw keyboard device
+
+  11 char	Serial Mux device	(Linux/PA-RISC only)
+		  0 = /dev/ttyB0	First mux port
+		  1 = /dev/ttyB1	Second mux port
+		    ...
+
+  11 block	SCSI CD-ROM devices
+		  0 = /dev/sr0		First SCSI CD-ROM
+		  1 = /dev/sr1		Second SCSI CD-ROM
+		    ...
+
+		In the past the prefix /dev/scd (instead of /dev/sr) was used and even recommended.
+
+  12 char	QIC-02 tape
+		  2 = /dev/ntpqic11	QIC-11, no rewind-on-close
+		  3 = /dev/tpqic11	QIC-11, rewind-on-close
+		  4 = /dev/ntpqic24	QIC-24, no rewind-on-close
+		  5 = /dev/tpqic24	QIC-24, rewind-on-close
+		  6 = /dev/ntpqic120	QIC-120, no rewind-on-close
+		  7 = /dev/tpqic120	QIC-120, rewind-on-close
+		  8 = /dev/ntpqic150	QIC-150, no rewind-on-close
+		  9 = /dev/tpqic150	QIC-150, rewind-on-close
+
+		The device names specified are proposed -- if there
+		are "standard" names for these devices, please let me know.
+
+  12 block
+
+  13 char	Input core
+		  0 = /dev/input/js0	First joystick
+		  1 = /dev/input/js1	Second joystick
+		    ...
+		 32 = /dev/input/mouse0	First mouse
+		 33 = /dev/input/mouse1	Second mouse
+		    ...
+		 63 = /dev/input/mice	Unified mouse
+		 64 = /dev/input/event0	First event queue
+		 65 = /dev/input/event1	Second event queue
+		    ...
+
+		Each device type has 5 bits (32 minors).
+
+  13 block	Previously used for the XT disk (/dev/xdN)
+		Deleted in kernel v3.9.
+
+  14 char	Open Sound System (OSS)
+		  0 = /dev/mixer	Mixer control
+		  1 = /dev/sequencer	Audio sequencer
+		  2 = /dev/midi00	First MIDI port
+		  3 = /dev/dsp		Digital audio
+		  4 = /dev/audio	Sun-compatible digital audio
+		  6 =
+		  7 = /dev/audioctl	SPARC audio control device
+		  8 = /dev/sequencer2	Sequencer -- alternate device
+		 16 = /dev/mixer1	Second soundcard mixer control
+		 17 = /dev/patmgr0	Sequencer patch manager
+		 18 = /dev/midi01	Second MIDI port
+		 19 = /dev/dsp1		Second soundcard digital audio
+		 20 = /dev/audio1	Second soundcard Sun digital audio
+		 33 = /dev/patmgr1	Sequencer patch manager
+		 34 = /dev/midi02	Third MIDI port
+		 50 = /dev/midi03	Fourth MIDI port
+
+  14 block
+
+  15 char	Joystick
+		  0 = /dev/js0		First analog joystick
+		  1 = /dev/js1		Second analog joystick
+		    ...
+		128 = /dev/djs0		First digital joystick
+		129 = /dev/djs1		Second digital joystick
+		    ...
+  15 block	Sony CDU-31A/CDU-33A CD-ROM
+		  0 = /dev/sonycd	Sony CDU-31a CD-ROM
+
+  16 char	Non-SCSI scanners
+		  0 = /dev/gs4500	Genius 4500 handheld scanner
+
+  16 block	GoldStar CD-ROM
+		  0 = /dev/gscd		GoldStar CD-ROM
+
+  17 char	OBSOLETE (was Chase serial card)
+		  0 = /dev/ttyH0	First Chase port
+		  1 = /dev/ttyH1	Second Chase port
+		    ...
+  17 block	Optics Storage CD-ROM
+		  0 = /dev/optcd	Optics Storage CD-ROM
+
+  18 char	OBSOLETE (was Chase serial card - alternate devices)
+		  0 = /dev/cuh0		Callout device for ttyH0
+		  1 = /dev/cuh1		Callout device for ttyH1
+		    ...
+  18 block	Sanyo CD-ROM
+		  0 = /dev/sjcd		Sanyo CD-ROM
+
+  19 block	"Double" compressed disk
+		  0 = /dev/double0	First compressed disk
+		    ...
+		  7 = /dev/double7	Eighth compressed disk
+		128 = /dev/cdouble0	Mirror of first compressed disk
+		    ...
+		135 = /dev/cdouble7	Mirror of eighth compressed disk
+
+		See the Double documentation for the meaning of the
+		mirror devices.
+
+  20 block	Hitachi CD-ROM (under development)
+		  0 = /dev/hitcd	Hitachi CD-ROM
+
+  21 char	Generic SCSI access
+		  0 = /dev/sg0		First generic SCSI device
+		  1 = /dev/sg1		Second generic SCSI device
+		    ...
+
+		Most distributions name these /dev/sga, /dev/sgb...;
+		this sets an unnecessary limit of 26 SCSI devices in
+		the system and is counter to standard Linux
+		device-naming practice.
+
+  21 block	Acorn MFM hard drive interface
+		  0 = /dev/mfma		First MFM drive whole disk
+		 64 = /dev/mfmb		Second MFM drive whole disk
+
+		This device is used on the ARM-based Acorn RiscPC.
+		Partitions are handled the same way as for IDE disks
+		(see major number 3).
+
+  22 char	Digiboard serial card
+		  0 = /dev/ttyD0	First Digiboard port
+		  1 = /dev/ttyD1	Second Digiboard port
+		    ...
+  22 block	Second IDE hard disk/CD-ROM interface
+		  0 = /dev/hdc		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdd		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  23 char	Digiboard serial card - alternate devices
+		  0 = /dev/cud0		Callout device for ttyD0
+		  1 = /dev/cud1		Callout device for ttyD1
+		      ...
+  23 block	Mitsumi proprietary CD-ROM
+		  0 = /dev/mcd		Mitsumi CD-ROM
+
+  24 char	Stallion serial card
+		  0 = /dev/ttyE0	Stallion port 0 card 0
+		  1 = /dev/ttyE1	Stallion port 1 card 0
+		    ...
+		 64 = /dev/ttyE64	Stallion port 0 card 1
+		 65 = /dev/ttyE65	Stallion port 1 card 1
+		      ...
+		128 = /dev/ttyE128	Stallion port 0 card 2
+		129 = /dev/ttyE129	Stallion port 1 card 2
+		    ...
+		192 = /dev/ttyE192	Stallion port 0 card 3
+		193 = /dev/ttyE193	Stallion port 1 card 3
+		    ...
+  24 block	Sony CDU-535 CD-ROM
+		  0 = /dev/cdu535	Sony CDU-535 CD-ROM
+
+  25 char	Stallion serial card - alternate devices
+		  0 = /dev/cue0		Callout device for ttyE0
+		  1 = /dev/cue1		Callout device for ttyE1
+		    ...
+		 64 = /dev/cue64	Callout device for ttyE64
+		 65 = /dev/cue65	Callout device for ttyE65
+		    ...
+		128 = /dev/cue128	Callout device for ttyE128
+		129 = /dev/cue129	Callout device for ttyE129
+		    ...
+		192 = /dev/cue192	Callout device for ttyE192
+		193 = /dev/cue193	Callout device for ttyE193
+		      ...
+  25 block	First Matsushita (Panasonic/SoundBlaster) CD-ROM
+		  0 = /dev/sbpcd0	Panasonic CD-ROM controller 0 unit 0
+		  1 = /dev/sbpcd1	Panasonic CD-ROM controller 0 unit 1
+		  2 = /dev/sbpcd2	Panasonic CD-ROM controller 0 unit 2
+		  3 = /dev/sbpcd3	Panasonic CD-ROM controller 0 unit 3
+
+  26 char
+
+  26 block	Second Matsushita (Panasonic/SoundBlaster) CD-ROM
+		  0 = /dev/sbpcd4	Panasonic CD-ROM controller 1 unit 0
+		  1 = /dev/sbpcd5	Panasonic CD-ROM controller 1 unit 1
+		  2 = /dev/sbpcd6	Panasonic CD-ROM controller 1 unit 2
+		  3 = /dev/sbpcd7	Panasonic CD-ROM controller 1 unit 3
+
+  27 char	QIC-117 tape
+		  0 = /dev/qft0		Unit 0, rewind-on-close
+		  1 = /dev/qft1		Unit 1, rewind-on-close
+		  2 = /dev/qft2		Unit 2, rewind-on-close
+		  3 = /dev/qft3		Unit 3, rewind-on-close
+		  4 = /dev/nqft0	Unit 0, no rewind-on-close
+		  5 = /dev/nqft1	Unit 1, no rewind-on-close
+		  6 = /dev/nqft2	Unit 2, no rewind-on-close
+		  7 = /dev/nqft3	Unit 3, no rewind-on-close
+		 16 = /dev/zqft0	Unit 0, rewind-on-close, compression
+		 17 = /dev/zqft1	Unit 1, rewind-on-close, compression
+		 18 = /dev/zqft2	Unit 2, rewind-on-close, compression
+		 19 = /dev/zqft3	Unit 3, rewind-on-close, compression
+		 20 = /dev/nzqft0	Unit 0, no rewind-on-close, compression
+		 21 = /dev/nzqft1	Unit 1, no rewind-on-close, compression
+		 22 = /dev/nzqft2	Unit 2, no rewind-on-close, compression
+		 23 = /dev/nzqft3	Unit 3, no rewind-on-close, compression
+		 32 = /dev/rawqft0	Unit 0, rewind-on-close, no file marks
+		 33 = /dev/rawqft1	Unit 1, rewind-on-close, no file marks
+		 34 = /dev/rawqft2	Unit 2, rewind-on-close, no file marks
+		 35 = /dev/rawqft3	Unit 3, rewind-on-close, no file marks
+		 36 = /dev/nrawqft0	Unit 0, no rewind-on-close, no file marks
+		 37 = /dev/nrawqft1	Unit 1, no rewind-on-close, no file marks
+		 38 = /dev/nrawqft2	Unit 2, no rewind-on-close, no file marks
+		 39 = /dev/nrawqft3	Unit 3, no rewind-on-close, no file marks
+
+  27 block	Third Matsushita (Panasonic/SoundBlaster) CD-ROM
+		  0 = /dev/sbpcd8	Panasonic CD-ROM controller 2 unit 0
+		  1 = /dev/sbpcd9	Panasonic CD-ROM controller 2 unit 1
+		  2 = /dev/sbpcd10	Panasonic CD-ROM controller 2 unit 2
+		  3 = /dev/sbpcd11	Panasonic CD-ROM controller 2 unit 3
+
+  28 char	Stallion serial card - card programming
+		  0 = /dev/staliomem0	First Stallion card I/O memory
+		  1 = /dev/staliomem1	Second Stallion card I/O memory
+		  2 = /dev/staliomem2	Third Stallion card I/O memory
+		  3 = /dev/staliomem3	Fourth Stallion card I/O memory
+
+  28 char	Atari SLM ACSI laser printer (68k/Atari)
+		  0 = /dev/slm0		First SLM laser printer
+		  1 = /dev/slm1		Second SLM laser printer
+		    ...
+  28 block	Fourth Matsushita (Panasonic/SoundBlaster) CD-ROM
+		  0 = /dev/sbpcd12	Panasonic CD-ROM controller 3 unit 0
+		  1 = /dev/sbpcd13	Panasonic CD-ROM controller 3 unit 1
+		  2 = /dev/sbpcd14	Panasonic CD-ROM controller 3 unit 2
+		  3 = /dev/sbpcd15	Panasonic CD-ROM controller 3 unit 3
+
+  28 block	ACSI disk (68k/Atari)
+		  0 = /dev/ada		First ACSI disk whole disk
+		 16 = /dev/adb		Second ACSI disk whole disk
+		 32 = /dev/adc		Third ACSI disk whole disk
+		    ...
+		240 = /dev/adp		16th ACSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15, like SCSI.
+
+  29 char	Universal frame buffer
+		  0 = /dev/fb0		First frame buffer
+		  1 = /dev/fb1		Second frame buffer
+		    ...
+		 31 = /dev/fb31		32nd frame buffer
+
+  29 block	Aztech/Orchid/Okano/Wearnes CD-ROM
+		  0 = /dev/aztcd	Aztech CD-ROM
+
+  30 char	iBCS-2 compatibility devices
+		  0 = /dev/socksys	Socket access
+		  1 = /dev/spx		SVR3 local X interface
+		 32 = /dev/inet/ip	Network access
+		 33 = /dev/inet/icmp
+		 34 = /dev/inet/ggp
+		 35 = /dev/inet/ipip
+		 36 = /dev/inet/tcp
+		 37 = /dev/inet/egp
+		 38 = /dev/inet/pup
+		 39 = /dev/inet/udp
+		 40 = /dev/inet/idp
+		 41 = /dev/inet/rawip
+
+		Additionally, iBCS-2 requires the following links:
+
+		/dev/ip -> /dev/inet/ip
+		/dev/icmp -> /dev/inet/icmp
+		/dev/ggp -> /dev/inet/ggp
+		/dev/ipip -> /dev/inet/ipip
+		/dev/tcp -> /dev/inet/tcp
+		/dev/egp -> /dev/inet/egp
+		/dev/pup -> /dev/inet/pup
+		/dev/udp -> /dev/inet/udp
+		/dev/idp -> /dev/inet/idp
+		/dev/rawip -> /dev/inet/rawip
+		/dev/inet/arp -> /dev/inet/udp
+		/dev/inet/rip -> /dev/inet/udp
+		/dev/nfsd -> /dev/socksys
+		/dev/X0R -> /dev/null (? apparently not required ?)
+
+  30 block	Philips LMS CM-205 CD-ROM
+		  0 = /dev/cm205cd	Philips LMS CM-205 CD-ROM
+
+		/dev/lmscd is an older name for this device.  This
+		driver does not work with the CM-205MS CD-ROM.
+
+  31 char	MPU-401 MIDI
+		  0 = /dev/mpu401data	MPU-401 data port
+		  1 = /dev/mpu401stat	MPU-401 status port
+
+  31 block	ROM/flash memory card
+		  0 = /dev/rom0		First ROM card (rw)
+		      ...
+		  7 = /dev/rom7		Eighth ROM card (rw)
+		  8 = /dev/rrom0	First ROM card (ro)
+		    ...
+		 15 = /dev/rrom7	Eighth ROM card (ro)
+		 16 = /dev/flash0	First flash memory card (rw)
+		    ...
+		 23 = /dev/flash7	Eighth flash memory card (rw)
+		 24 = /dev/rflash0	First flash memory card (ro)
+		    ...
+		 31 = /dev/rflash7	Eighth flash memory card (ro)
+
+		The read-write (rw) devices support back-caching
+		written data in RAM, as well as writing to flash RAM
+		devices.  The read-only devices (ro) support reading
+		only.
+
+  32 char	Specialix serial card
+		  0 = /dev/ttyX0	First Specialix port
+		  1 = /dev/ttyX1	Second Specialix port
+		    ...
+  32 block	Philips LMS CM-206 CD-ROM
+		  0 = /dev/cm206cd	Philips LMS CM-206 CD-ROM
+
+  33 char	Specialix serial card - alternate devices
+		  0 = /dev/cux0		Callout device for ttyX0
+		  1 = /dev/cux1		Callout device for ttyX1
+		    ...
+  33 block	Third IDE hard disk/CD-ROM interface
+		  0 = /dev/hde		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdf		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  34 char	Z8530 HDLC driver
+		  0 = /dev/scc0		First Z8530, first port
+		  1 = /dev/scc1		First Z8530, second port
+		  2 = /dev/scc2		Second Z8530, first port
+		  3 = /dev/scc3		Second Z8530, second port
+		    ...
+
+		In a previous version these devices were named
+		/dev/sc1 for /dev/scc0, /dev/sc2 for /dev/scc1, and so
+		on.
+
+  34 block	Fourth IDE hard disk/CD-ROM interface
+		  0 = /dev/hdg		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdh		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  35 char	tclmidi MIDI driver
+		  0 = /dev/midi0	First MIDI port, kernel timed
+		  1 = /dev/midi1	Second MIDI port, kernel timed
+		  2 = /dev/midi2	Third MIDI port, kernel timed
+		  3 = /dev/midi3	Fourth MIDI port, kernel timed
+		 64 = /dev/rmidi0	First MIDI port, untimed
+		 65 = /dev/rmidi1	Second MIDI port, untimed
+		 66 = /dev/rmidi2	Third MIDI port, untimed
+		 67 = /dev/rmidi3	Fourth MIDI port, untimed
+		128 = /dev/smpte0	First MIDI port, SMPTE timed
+		129 = /dev/smpte1	Second MIDI port, SMPTE timed
+		130 = /dev/smpte2	Third MIDI port, SMPTE timed
+		131 = /dev/smpte3	Fourth MIDI port, SMPTE timed
+
+  35 block	Slow memory ramdisk
+		  0 = /dev/slram	Slow memory ramdisk
+
+  36 char	Netlink support
+		  0 = /dev/route	Routing, device updates, kernel to user
+		  1 = /dev/skip		enSKIP security cache control
+		  3 = /dev/fwmonitor	Firewall packet copies
+		 16 = /dev/tap0		First Ethertap device
+		    ...
+		 31 = /dev/tap15	16th Ethertap device
+
+  36 block	OBSOLETE (was MCA ESDI hard disk)
+
+  37 char	IDE tape
+		  0 = /dev/ht0		First IDE tape
+		  1 = /dev/ht1		Second IDE tape
+		    ...
+		128 = /dev/nht0		First IDE tape, no rewind-on-close
+		129 = /dev/nht1		Second IDE tape, no rewind-on-close
+		    ...
+
+		Currently, only one IDE tape drive is supported.
+
+  37 block	Zorro II ramdisk
+		  0 = /dev/z2ram	Zorro II ramdisk
+
+  38 char	Myricom PCI Myrinet board
+		  0 = /dev/mlanai0	First Myrinet board
+		  1 = /dev/mlanai1	Second Myrinet board
+		    ...
+
+		This device is used for status query, board control
+		and "user level packet I/O."  This board is also
+		accessible as a standard networking "eth" device.
+
+  38 block	OBSOLETE (was Linux/AP+)
+
+  39 char	ML-16P experimental I/O board
+		  0 = /dev/ml16pa-a0	First card, first analog channel
+		  1 = /dev/ml16pa-a1	First card, second analog channel
+		    ...
+		 15 = /dev/ml16pa-a15	First card, 16th analog channel
+		 16 = /dev/ml16pa-d	First card, digital lines
+		 17 = /dev/ml16pa-c0	First card, first counter/timer
+		 18 = /dev/ml16pa-c1	First card, second counter/timer
+		 19 = /dev/ml16pa-c2	First card, third counter/timer
+		 32 = /dev/ml16pb-a0	Second card, first analog channel
+		 33 = /dev/ml16pb-a1	Second card, second analog channel
+		    ...
+		 47 = /dev/ml16pb-a15	Second card, 16th analog channel
+		 48 = /dev/ml16pb-d	Second card, digital lines
+		 49 = /dev/ml16pb-c0	Second card, first counter/timer
+		 50 = /dev/ml16pb-c1	Second card, second counter/timer
+		 51 = /dev/ml16pb-c2	Second card, third counter/timer
+		      ...
+  39 block
+
+  40 char
+
+  40 block
+
+  41 char	Yet Another Micro Monitor
+		  0 = /dev/yamm		Yet Another Micro Monitor
+
+  41 block
+
+  42 char	Demo/sample use
+
+  42 block	Demo/sample use
+
+		This number is intended for use in sample code, as
+		well as a general "example" device number.  It
+		should never be used for a device driver that is being
+		distributed; either obtain an official number or use
+		the local/experimental range.  The sudden addition or
+		removal of a driver with this number should not cause
+		ill effects to the system (bugs excepted.)
+
+		IN PARTICULAR, ANY DISTRIBUTION WHICH CONTAINS A
+		DEVICE DRIVER USING MAJOR NUMBER 42 IS NONCOMPLIANT.
+
+  43 char	isdn4linux virtual modem
+		  0 = /dev/ttyI0	First virtual modem
+		    ...
+		 63 = /dev/ttyI63	64th virtual modem
+
+  43 block	Network block devices
+		  0 = /dev/nb0		First network block device
+		  1 = /dev/nb1		Second network block device
+		    ...
+
+		Network Block Device is somehow similar to loopback
+		devices: If you read from it, it sends packet across
+		network asking server for data. If you write to it, it
+		sends packet telling server to write. It could be used
+		to mounting filesystems over the net, swapping over
+		the net, implementing block device in userland etc.
+
+  44 char	isdn4linux virtual modem - alternate devices
+		  0 = /dev/cui0		Callout device for ttyI0
+		    ...
+		 63 = /dev/cui63	Callout device for ttyI63
+
+  44 block	Flash Translation Layer (FTL) filesystems
+		  0 = /dev/ftla		FTL on first Memory Technology Device
+		 16 = /dev/ftlb		FTL on second Memory Technology Device
+		 32 = /dev/ftlc		FTL on third Memory Technology Device
+		    ...
+		240 = /dev/ftlp		FTL on 16th Memory Technology Device
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the partition
+		limit is 15 rather than 63 per disk (same as SCSI.)
+
+  45 char	isdn4linux ISDN BRI driver
+		  0 = /dev/isdn0	First virtual B channel raw data
+		    ...
+		 63 = /dev/isdn63	64th virtual B channel raw data
+		 64 = /dev/isdnctrl0	First channel control/debug
+		    ...
+		127 = /dev/isdnctrl63	64th channel control/debug
+
+		128 = /dev/ippp0	First SyncPPP device
+		    ...
+		191 = /dev/ippp63	64th SyncPPP device
+
+		255 = /dev/isdninfo	ISDN monitor interface
+
+  45 block	Parallel port IDE disk devices
+		  0 = /dev/pda		First parallel port IDE disk
+		 16 = /dev/pdb		Second parallel port IDE disk
+		 32 = /dev/pdc		Third parallel port IDE disk
+		 48 = /dev/pdd		Fourth parallel port IDE disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the partition
+		limit is 15 rather than 63 per disk.
+
+  46 char	Comtrol Rocketport serial card
+		  0 = /dev/ttyR0	First Rocketport port
+		  1 = /dev/ttyR1	Second Rocketport port
+		    ...
+  46 block	Parallel port ATAPI CD-ROM devices
+		  0 = /dev/pcd0		First parallel port ATAPI CD-ROM
+		  1 = /dev/pcd1		Second parallel port ATAPI CD-ROM
+		  2 = /dev/pcd2		Third parallel port ATAPI CD-ROM
+		  3 = /dev/pcd3		Fourth parallel port ATAPI CD-ROM
+
+  47 char	Comtrol Rocketport serial card - alternate devices
+		  0 = /dev/cur0		Callout device for ttyR0
+		  1 = /dev/cur1		Callout device for ttyR1
+		    ...
+  47 block	Parallel port ATAPI disk devices
+		  0 = /dev/pf0		First parallel port ATAPI disk
+		  1 = /dev/pf1		Second parallel port ATAPI disk
+		  2 = /dev/pf2		Third parallel port ATAPI disk
+		  3 = /dev/pf3		Fourth parallel port ATAPI disk
+
+		This driver is intended for floppy disks and similar
+		devices and hence does not support partitioning.
+
+  48 char	SDL RISCom serial card
+		  0 = /dev/ttyL0	First RISCom port
+		  1 = /dev/ttyL1	Second RISCom port
+		    ...
+  48 block	Mylex DAC960 PCI RAID controller; first controller
+		  0 = /dev/rd/c0d0	First disk, whole disk
+		  8 = /dev/rd/c0d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c0d31	32nd disk, whole disk
+
+		For partitions add:
+		  0 = /dev/rd/c?d?	Whole disk
+		  1 = /dev/rd/c?d?p1	First partition
+		    ...
+		  7 = /dev/rd/c?d?p7	Seventh partition
+
+  49 char	SDL RISCom serial card - alternate devices
+		  0 = /dev/cul0		Callout device for ttyL0
+		  1 = /dev/cul1		Callout device for ttyL1
+		    ...
+  49 block	Mylex DAC960 PCI RAID controller; second controller
+		  0 = /dev/rd/c1d0	First disk, whole disk
+		  8 = /dev/rd/c1d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c1d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  50 char	Reserved for GLINT
+
+  50 block	Mylex DAC960 PCI RAID controller; third controller
+		  0 = /dev/rd/c2d0	First disk, whole disk
+		  8 = /dev/rd/c2d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c2d31	32nd disk, whole disk
+
+  51 char	Baycom radio modem OR Radio Tech BIM-XXX-RS232 radio modem
+		  0 = /dev/bc0		First Baycom radio modem
+		  1 = /dev/bc1		Second Baycom radio modem
+		    ...
+  51 block	Mylex DAC960 PCI RAID controller; fourth controller
+		  0 = /dev/rd/c3d0	First disk, whole disk
+		  8 = /dev/rd/c3d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c3d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  52 char	Spellcaster DataComm/BRI ISDN card
+		  0 = /dev/dcbri0	First DataComm card
+		  1 = /dev/dcbri1	Second DataComm card
+		  2 = /dev/dcbri2	Third DataComm card
+		  3 = /dev/dcbri3	Fourth DataComm card
+
+  52 block	Mylex DAC960 PCI RAID controller; fifth controller
+		  0 = /dev/rd/c4d0	First disk, whole disk
+		  8 = /dev/rd/c4d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c4d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  53 char	BDM interface for remote debugging MC683xx microcontrollers
+		  0 = /dev/pd_bdm0	PD BDM interface on lp0
+		  1 = /dev/pd_bdm1	PD BDM interface on lp1
+		  2 = /dev/pd_bdm2	PD BDM interface on lp2
+		  4 = /dev/icd_bdm0	ICD BDM interface on lp0
+		  5 = /dev/icd_bdm1	ICD BDM interface on lp1
+		  6 = /dev/icd_bdm2	ICD BDM interface on lp2
+
+		This device is used for the interfacing to the MC683xx
+		microcontrollers via Background Debug Mode by use of a
+		Parallel Port interface. PD is the Motorola Public
+		Domain Interface and ICD is the commercial interface
+		by P&E.
+
+  53 block	Mylex DAC960 PCI RAID controller; sixth controller
+		  0 = /dev/rd/c5d0	First disk, whole disk
+		  8 = /dev/rd/c5d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c5d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  54 char	Electrocardiognosis Holter serial card
+		  0 = /dev/holter0	First Holter port
+		  1 = /dev/holter1	Second Holter port
+		  2 = /dev/holter2	Third Holter port
+
+		A custom serial card used by Electrocardiognosis SRL
+		<mseritan@ottonel.pub.ro> to transfer data from Holter
+		24-hour heart monitoring equipment.
+
+  54 block	Mylex DAC960 PCI RAID controller; seventh controller
+		  0 = /dev/rd/c6d0	First disk, whole disk
+		  8 = /dev/rd/c6d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c6d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  55 char	DSP56001 digital signal processor
+		  0 = /dev/dsp56k	First DSP56001
+
+  55 block	Mylex DAC960 PCI RAID controller; eighth controller
+		  0 = /dev/rd/c7d0	First disk, whole disk
+		  8 = /dev/rd/c7d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c7d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+  56 char	Apple Desktop Bus
+		  0 = /dev/adb		ADB bus control
+
+		Additional devices will be added to this number, all
+		starting with /dev/adb.
+
+  56 block	Fifth IDE hard disk/CD-ROM interface
+		  0 = /dev/hdi		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdj		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  57 char	Hayes ESP serial card
+		  0 = /dev/ttyP0	First ESP port
+		  1 = /dev/ttyP1	Second ESP port
+		    ...
+
+  57 block	Sixth IDE hard disk/CD-ROM interface
+		  0 = /dev/hdk		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdl		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  58 char	Hayes ESP serial card - alternate devices
+		  0 = /dev/cup0		Callout device for ttyP0
+		  1 = /dev/cup1		Callout device for ttyP1
+		    ...
+
+  58 block	Reserved for logical volume manager
+
+  59 char	sf firewall package
+		  0 = /dev/firewall	Communication with sf kernel module
+
+  59 block	Generic PDA filesystem device
+		  0 = /dev/pda0		First PDA device
+		  1 = /dev/pda1		Second PDA device
+		    ...
+
+		The pda devices are used to mount filesystems on
+		remote pda's (basically slow handheld machines with
+		proprietary OS's and limited memory and storage
+		running small fs translation drivers) through serial /
+		IRDA / parallel links.
+
+		NAMING CONFLICT -- PROPOSED REVISED NAME /dev/rpda0 etc
+
+  60-63 char	LOCAL/EXPERIMENTAL USE
+
+  60-63 block	LOCAL/EXPERIMENTAL USE
+		Allocated for local/experimental use.  For devices not
+		assigned official numbers, these ranges should be
+		used in order to avoid conflicting with future assignments.
+
+  64 char	ENskip kernel encryption package
+		  0 = /dev/enskip	Communication with ENskip kernel module
+
+  64 block	Scramdisk/DriveCrypt encrypted devices
+		  0 = /dev/scramdisk/master    Master node for ioctls
+		  1 = /dev/scramdisk/1         First encrypted device
+		  2 = /dev/scramdisk/2         Second encrypted device
+		  ...
+		255 = /dev/scramdisk/255       255th encrypted device
+
+		The filename of the encrypted container and the passwords
+		are sent via ioctls (using the sdmount tool) to the master
+		node which then activates them via one of the
+		/dev/scramdisk/x nodes for loop mounting (all handled
+		through the sdmount tool).
+
+		Requested by: andy@scramdisklinux.org
+
+  65 char	Sundance "plink" Transputer boards (obsolete, unused)
+		  0 = /dev/plink0	First plink device
+		  1 = /dev/plink1	Second plink device
+		  2 = /dev/plink2	Third plink device
+		  3 = /dev/plink3	Fourth plink device
+		 64 = /dev/rplink0	First plink device, raw
+		 65 = /dev/rplink1	Second plink device, raw
+		 66 = /dev/rplink2	Third plink device, raw
+		 67 = /dev/rplink3	Fourth plink device, raw
+		128 = /dev/plink0d	First plink device, debug
+		129 = /dev/plink1d	Second plink device, debug
+		130 = /dev/plink2d	Third plink device, debug
+		131 = /dev/plink3d	Fourth plink device, debug
+		192 = /dev/rplink0d	First plink device, raw, debug
+		193 = /dev/rplink1d	Second plink device, raw, debug
+		194 = /dev/rplink2d	Third plink device, raw, debug
+		195 = /dev/rplink3d	Fourth plink device, raw, debug
+
+		This is a commercial driver; contact James Howes
+		<jth@prosig.demon.co.uk> for information.
+
+  65 block	SCSI disk devices (16-31)
+		  0 = /dev/sdq		17th SCSI disk whole disk
+		 16 = /dev/sdr		18th SCSI disk whole disk
+		 32 = /dev/sds		19th SCSI disk whole disk
+		    ...
+		240 = /dev/sdaf		32nd SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  66 char	YARC PowerPC PCI coprocessor card
+		  0 = /dev/yppcpci0	First YARC card
+		  1 = /dev/yppcpci1	Second YARC card
+		    ...
+
+  66 block	SCSI disk devices (32-47)
+		  0 = /dev/sdag		33th SCSI disk whole disk
+		 16 = /dev/sdah		34th SCSI disk whole disk
+		 32 = /dev/sdai		35th SCSI disk whole disk
+		    ...
+		240 = /dev/sdav		48nd SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  67 char	Coda network file system
+		  0 = /dev/cfs0		Coda cache manager
+
+		See http://www.coda.cs.cmu.edu for information about Coda.
+
+  67 block	SCSI disk devices (48-63)
+		  0 = /dev/sdaw		49th SCSI disk whole disk
+		 16 = /dev/sdax		50th SCSI disk whole disk
+		 32 = /dev/sday		51st SCSI disk whole disk
+		    ...
+		240 = /dev/sdbl		64th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  68 char	CAPI 2.0 interface
+		  0 = /dev/capi20	Control device
+		  1 = /dev/capi20.00	First CAPI 2.0 application
+		  2 = /dev/capi20.01	Second CAPI 2.0 application
+		    ...
+		 20 = /dev/capi20.19	19th CAPI 2.0 application
+
+		ISDN CAPI 2.0 driver for use with CAPI 2.0
+		applications; currently supports the AVM B1 card.
+
+  68 block	SCSI disk devices (64-79)
+		  0 = /dev/sdbm		65th SCSI disk whole disk
+		 16 = /dev/sdbn		66th SCSI disk whole disk
+		 32 = /dev/sdbo		67th SCSI disk whole disk
+		    ...
+		240 = /dev/sdcb		80th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  69 char	MA16 numeric accelerator card
+		  0 = /dev/ma16		Board memory access
+
+  69 block	SCSI disk devices (80-95)
+		  0 = /dev/sdcc		81st SCSI disk whole disk
+		 16 = /dev/sdcd		82nd SCSI disk whole disk
+		 32 = /dev/sdce		83th SCSI disk whole disk
+		    ...
+		240 = /dev/sdcr		96th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  70 char	SpellCaster Protocol Services Interface
+		  0 = /dev/apscfg	Configuration interface
+		  1 = /dev/apsauth	Authentication interface
+		  2 = /dev/apslog	Logging interface
+		  3 = /dev/apsdbg	Debugging interface
+		 64 = /dev/apsisdn	ISDN command interface
+		 65 = /dev/apsasync	Async command interface
+		128 = /dev/apsmon	Monitor interface
+
+  70 block	SCSI disk devices (96-111)
+		  0 = /dev/sdcs		97th SCSI disk whole disk
+		 16 = /dev/sdct		98th SCSI disk whole disk
+		 32 = /dev/sdcu		99th SCSI disk whole disk
+		    ...
+		240 = /dev/sddh		112nd SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  71 char	Computone IntelliPort II serial card
+		  0 = /dev/ttyF0	IntelliPort II board 0, port 0
+		  1 = /dev/ttyF1	IntelliPort II board 0, port 1
+		    ...
+		 63 = /dev/ttyF63	IntelliPort II board 0, port 63
+		 64 = /dev/ttyF64	IntelliPort II board 1, port 0
+		 65 = /dev/ttyF65	IntelliPort II board 1, port 1
+		    ...
+		127 = /dev/ttyF127	IntelliPort II board 1, port 63
+		128 = /dev/ttyF128	IntelliPort II board 2, port 0
+		129 = /dev/ttyF129	IntelliPort II board 2, port 1
+		    ...
+		191 = /dev/ttyF191	IntelliPort II board 2, port 63
+		192 = /dev/ttyF192	IntelliPort II board 3, port 0
+		193 = /dev/ttyF193	IntelliPort II board 3, port 1
+		    ...
+		255 = /dev/ttyF255	IntelliPort II board 3, port 63
+
+  71 block	SCSI disk devices (112-127)
+		  0 = /dev/sddi		113th SCSI disk whole disk
+		 16 = /dev/sddj		114th SCSI disk whole disk
+		 32 = /dev/sddk		115th SCSI disk whole disk
+		    ...
+		240 = /dev/sddx		128th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  72 char	Computone IntelliPort II serial card - alternate devices
+		  0 = /dev/cuf0		Callout device for ttyF0
+		  1 = /dev/cuf1		Callout device for ttyF1
+		    ...
+		 63 = /dev/cuf63	Callout device for ttyF63
+		 64 = /dev/cuf64	Callout device for ttyF64
+		 65 = /dev/cuf65	Callout device for ttyF65
+		    ...
+		127 = /dev/cuf127	Callout device for ttyF127
+		128 = /dev/cuf128	Callout device for ttyF128
+		129 = /dev/cuf129	Callout device for ttyF129
+		    ...
+		191 = /dev/cuf191	Callout device for ttyF191
+		192 = /dev/cuf192	Callout device for ttyF192
+		193 = /dev/cuf193	Callout device for ttyF193
+		    ...
+		255 = /dev/cuf255	Callout device for ttyF255
+
+  72 block	Compaq Intelligent Drive Array, first controller
+		  0 = /dev/ida/c0d0	First logical drive whole disk
+		 16 = /dev/ida/c0d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c0d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  73 char	Computone IntelliPort II serial card - control devices
+		  0 = /dev/ip2ipl0	Loadware device for board 0
+		  1 = /dev/ip2stat0	Status device for board 0
+		  4 = /dev/ip2ipl1	Loadware device for board 1
+		  5 = /dev/ip2stat1	Status device for board 1
+		  8 = /dev/ip2ipl2	Loadware device for board 2
+		  9 = /dev/ip2stat2	Status device for board 2
+		 12 = /dev/ip2ipl3	Loadware device for board 3
+		 13 = /dev/ip2stat3	Status device for board 3
+
+  73 block	Compaq Intelligent Drive Array, second controller
+		  0 = /dev/ida/c1d0	First logical drive whole disk
+		 16 = /dev/ida/c1d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c1d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  74 char	SCI bridge
+		  0 = /dev/SCI/0	SCI device 0
+		  1 = /dev/SCI/1	SCI device 1
+		    ...
+
+		Currently for Dolphin Interconnect Solutions' PCI-SCI
+		bridge.
+
+  74 block	Compaq Intelligent Drive Array, third controller
+		  0 = /dev/ida/c2d0	First logical drive whole disk
+		 16 = /dev/ida/c2d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c2d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  75 char	Specialix IO8+ serial card
+		  0 = /dev/ttyW0	First IO8+ port, first card
+		  1 = /dev/ttyW1	Second IO8+ port, first card
+		    ...
+		  8 = /dev/ttyW8	First IO8+ port, second card
+		    ...
+
+  75 block	Compaq Intelligent Drive Array, fourth controller
+		  0 = /dev/ida/c3d0	First logical drive whole disk
+		 16 = /dev/ida/c3d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c3d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  76 char	Specialix IO8+ serial card - alternate devices
+		  0 = /dev/cuw0		Callout device for ttyW0
+		  1 = /dev/cuw1		Callout device for ttyW1
+		    ...
+		  8 = /dev/cuw8		Callout device for ttyW8
+		    ...
+
+  76 block	Compaq Intelligent Drive Array, fifth controller
+		  0 = /dev/ida/c4d0	First logical drive whole disk
+		 16 = /dev/ida/c4d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c4d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+
+  77 char	ComScire Quantum Noise Generator
+		  0 = /dev/qng		ComScire Quantum Noise Generator
+
+  77 block	Compaq Intelligent Drive Array, sixth controller
+		  0 = /dev/ida/c5d0	First logical drive whole disk
+		 16 = /dev/ida/c5d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c5d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  78 char	PAM Software's multimodem boards
+		  0 = /dev/ttyM0	First PAM modem
+		  1 = /dev/ttyM1	Second PAM modem
+		    ...
+
+  78 block	Compaq Intelligent Drive Array, seventh controller
+		  0 = /dev/ida/c6d0	First logical drive whole disk
+		 16 = /dev/ida/c6d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c6d15	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  79 char	PAM Software's multimodem boards - alternate devices
+		  0 = /dev/cum0		Callout device for ttyM0
+		  1 = /dev/cum1		Callout device for ttyM1
+		    ...
+
+  79 block	Compaq Intelligent Drive Array, eighth controller
+		  0 = /dev/ida/c7d0	First logical drive whole disk
+		 16 = /dev/ida/c7d1	Second logical drive whole disk
+		    ...
+		240 = /dev/ida/c715	16th logical drive whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+  80 char	Photometrics AT200 CCD camera
+		  0 = /dev/at200	Photometrics AT200 CCD camera
+
+  80 block	I2O hard disk
+		  0 = /dev/i2o/hda	First I2O hard disk, whole disk
+		 16 = /dev/i2o/hdb	Second I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdp	16th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  81 char	video4linux
+		  0 = /dev/video0	Video capture/overlay device
+		    ...
+		 63 = /dev/video63	Video capture/overlay device
+		 64 = /dev/radio0	Radio device
+		    ...
+		127 = /dev/radio63	Radio device
+		128 = /dev/swradio0	Software Defined Radio device
+		    ...
+		191 = /dev/swradio63	Software Defined Radio device
+		224 = /dev/vbi0		Vertical blank interrupt
+		    ...
+		255 = /dev/vbi31	Vertical blank interrupt
+
+		Minor numbers are allocated dynamically unless
+		CONFIG_VIDEO_FIXED_MINOR_RANGES (default n)
+		configuration option is set.
+
+  81 block	I2O hard disk
+		  0 = /dev/i2o/hdq	17th I2O hard disk, whole disk
+		 16 = /dev/i2o/hdr	18th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdaf	32nd I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  82 char	WiNRADiO communications receiver card
+		  0 = /dev/winradio0	First WiNRADiO card
+		  1 = /dev/winradio1	Second WiNRADiO card
+		    ...
+
+		The driver and documentation may be obtained from
+		https://www.winradio.com/
+
+  82 block	I2O hard disk
+		  0 = /dev/i2o/hdag	33rd I2O hard disk, whole disk
+		 16 = /dev/i2o/hdah	34th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdav	48th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  83 char	Matrox mga_vid video driver
+		 0 = /dev/mga_vid0	1st video card
+		 1 = /dev/mga_vid1	2nd video card
+		 2 = /dev/mga_vid2	3rd video card
+		  ...
+		15 = /dev/mga_vid15	16th video card
+
+  83 block	I2O hard disk
+		  0 = /dev/i2o/hdaw	49th I2O hard disk, whole disk
+		 16 = /dev/i2o/hdax	50th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdbl	64th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  84 char	Ikon 1011[57] Versatec Greensheet Interface
+		  0 = /dev/ihcp0	First Greensheet port
+		  1 = /dev/ihcp1	Second Greensheet port
+
+  84 block	I2O hard disk
+		  0 = /dev/i2o/hdbm	65th I2O hard disk, whole disk
+		 16 = /dev/i2o/hdbn	66th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdcb	80th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  85 char	Linux/SGI shared memory input queue
+		  0 = /dev/shmiq	Master shared input queue
+		  1 = /dev/qcntl0	First device pushed
+		  2 = /dev/qcntl1	Second device pushed
+		    ...
+
+  85 block	I2O hard disk
+		  0 = /dev/i2o/hdcc	81st I2O hard disk, whole disk
+		 16 = /dev/i2o/hdcd	82nd I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hdcr	96th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  86 char	SCSI media changer
+		  0 = /dev/sch0		First SCSI media changer
+		  1 = /dev/sch1		Second SCSI media changer
+		    ...
+
+  86 block	I2O hard disk
+		  0 = /dev/i2o/hdcs	97th I2O hard disk, whole disk
+		 16 = /dev/i2o/hdct	98th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hddh	112th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  87 char	Sony Control-A1 stereo control bus
+		  0 = /dev/controla0	First device on chain
+		  1 = /dev/controla1	Second device on chain
+		    ...
+
+  87 block	I2O hard disk
+		  0 = /dev/i2o/hddi	113rd I2O hard disk, whole disk
+		 16 = /dev/i2o/hddj	114th I2O hard disk, whole disk
+		    ...
+		240 = /dev/i2o/hddx	128th I2O hard disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  88 char	COMX synchronous serial card
+		  0 = /dev/comx0	COMX channel 0
+		  1 = /dev/comx1	COMX channel 1
+		    ...
+
+  88 block	Seventh IDE hard disk/CD-ROM interface
+		  0 = /dev/hdm		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdn		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  89 char	I2C bus interface
+		  0 = /dev/i2c-0	First I2C adapter
+		  1 = /dev/i2c-1	Second I2C adapter
+		    ...
+
+  89 block	Eighth IDE hard disk/CD-ROM interface
+		  0 = /dev/hdo		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdp		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  90 char	Memory Technology Device (RAM, ROM, Flash)
+		  0 = /dev/mtd0		First MTD (rw)
+		  1 = /dev/mtdr0	First MTD (ro)
+		    ...
+		 30 = /dev/mtd15	16th MTD (rw)
+		 31 = /dev/mtdr15	16th MTD (ro)
+
+  90 block	Ninth IDE hard disk/CD-ROM interface
+		  0 = /dev/hdq		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdr		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  91 char	CAN-Bus devices
+		  0 = /dev/can0		First CAN-Bus controller
+		  1 = /dev/can1		Second CAN-Bus controller
+		    ...
+
+  91 block	Tenth IDE hard disk/CD-ROM interface
+		  0 = /dev/hds		Master: whole disk (or CD-ROM)
+		 64 = /dev/hdt		Slave: whole disk (or CD-ROM)
+
+		Partitions are handled the same way as for the first
+		interface (see major number 3).
+
+  92 char	Reserved for ith Kommunikationstechnik MIC ISDN card
+
+  92 block	PPDD encrypted disk driver
+		  0 = /dev/ppdd0	First encrypted disk
+		  1 = /dev/ppdd1	Second encrypted disk
+		    ...
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+  93 char
+
+  93 block	NAND Flash Translation Layer filesystem
+		  0 = /dev/nftla	First NFTL layer
+		 16 = /dev/nftlb	Second NFTL layer
+		    ...
+		240 = /dev/nftlp	16th NTFL layer
+
+  94 char
+
+  94 block	IBM S/390 DASD block storage
+		  0 = /dev/dasda First DASD device, major
+		  1 = /dev/dasda1 First DASD device, block 1
+		  2 = /dev/dasda2 First DASD device, block 2
+		  3 = /dev/dasda3 First DASD device, block 3
+		  4 = /dev/dasdb Second DASD device, major
+		  5 = /dev/dasdb1 Second DASD device, block 1
+		  6 = /dev/dasdb2 Second DASD device, block 2
+		  7 = /dev/dasdb3 Second DASD device, block 3
+		    ...
+
+  95 char	IP filter
+		  0 = /dev/ipl		Filter control device/log file
+		  1 = /dev/ipnat	NAT control device/log file
+		  2 = /dev/ipstate	State information log file
+		  3 = /dev/ipauth	Authentication control device/log file
+		    ...
+
+  96 char	Parallel port ATAPI tape devices
+		  0 = /dev/pt0		First parallel port ATAPI tape
+		  1 = /dev/pt1		Second parallel port ATAPI tape
+		    ...
+		128 = /dev/npt0		First p.p. ATAPI tape, no rewind
+		129 = /dev/npt1		Second p.p. ATAPI tape, no rewind
+		    ...
+
+  96 block	Inverse NAND Flash Translation Layer
+		  0 = /dev/inftla First INFTL layer
+		 16 = /dev/inftlb Second INFTL layer
+		    ...
+		240 = /dev/inftlp	16th INTFL layer
+
+  97 char	Parallel port generic ATAPI interface
+		  0 = /dev/pg0		First parallel port ATAPI device
+		  1 = /dev/pg1		Second parallel port ATAPI device
+		  2 = /dev/pg2		Third parallel port ATAPI device
+		  3 = /dev/pg3		Fourth parallel port ATAPI device
+
+		These devices support the same API as the generic SCSI
+		devices.
+
+  98 char	Control and Measurement Device (comedi)
+		  0 = /dev/comedi0	First comedi device
+		  1 = /dev/comedi1	Second comedi device
+		    ...
+		 47 = /dev/comedi47	48th comedi device
+
+		Minors 48 to 255 are reserved for comedi subdevices with
+		pathnames of the form "/dev/comediX_subdY", where "X" is the
+		minor number of the associated comedi device and "Y" is the
+		subdevice number.  These subdevice minors are assigned
+		dynamically, so there is no fixed mapping from subdevice
+		pathnames to minor numbers.
+
+		See https://www.comedi.org/ for information about the Comedi
+		project.
+
+  98 block	User-mode virtual block device
+		  0 = /dev/ubda		First user-mode block device
+		 16 = /dev/ubdb		Second user-mode block device
+		    ...
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+		This device is used by the user-mode virtual kernel port.
+
+  99 char	Raw parallel ports
+		  0 = /dev/parport0	First parallel port
+		  1 = /dev/parport1	Second parallel port
+		    ...
+
+  99 block	JavaStation flash disk
+		  0 = /dev/jsfd		JavaStation flash disk
+
+ 100 char	Telephony for Linux
+		  0 = /dev/phone0	First telephony device
+		  1 = /dev/phone1	Second telephony device
+		    ...
+
+ 101 char	Motorola DSP 56xxx board
+		  0 = /dev/mdspstat	Status information
+		  1 = /dev/mdsp1	First DSP board I/O controls
+		    ...
+		 16 = /dev/mdsp16	16th DSP board I/O controls
+
+ 101 block	AMI HyperDisk RAID controller
+		  0 = /dev/amiraid/ar0	First array whole disk
+		 16 = /dev/amiraid/ar1	Second array whole disk
+		    ...
+		240 = /dev/amiraid/ar15	16th array whole disk
+
+		For each device, partitions are added as:
+		  0 = /dev/amiraid/ar?	  Whole disk
+		  1 = /dev/amiraid/ar?p1  First partition
+		  2 = /dev/amiraid/ar?p2  Second partition
+		    ...
+		 15 = /dev/amiraid/ar?p15 15th partition
+
+ 102 char
+
+ 102 block	Compressed block device
+		  0 = /dev/cbd/a	First compressed block device, whole device
+		 16 = /dev/cbd/b	Second compressed block device, whole device
+		    ...
+		240 = /dev/cbd/p	16th compressed block device, whole device
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 103 char	Arla network file system
+		  0 = /dev/nnpfs0	First NNPFS device
+		  1 = /dev/nnpfs1	Second NNPFS device
+
+		Arla is a free clone of the Andrew File System, AFS.
+		The NNPFS device gives user mode filesystem
+		implementations a kernel presence for caching and easy
+		mounting.  For more information about the project,
+		write to <arla-drinkers@stacken.kth.se> or see
+		https://www.stacken.kth.se/project/arla/
+
+ 103 block	Audit device
+		  0 = /dev/audit	Audit device
+
+ 104 char	Flash BIOS support
+
+ 104 block	Compaq Next Generation Drive Array, first controller
+		  0 = /dev/cciss/c0d0	First logical drive, whole disk
+		 16 = /dev/cciss/c0d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c0d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 105 char	Comtrol VS-1000 serial controller
+		  0 = /dev/ttyV0	First VS-1000 port
+		  1 = /dev/ttyV1	Second VS-1000 port
+		    ...
+
+ 105 block	Compaq Next Generation Drive Array, second controller
+		  0 = /dev/cciss/c1d0	First logical drive, whole disk
+		 16 = /dev/cciss/c1d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c1d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 106 char	Comtrol VS-1000 serial controller - alternate devices
+		  0 = /dev/cuv0		First VS-1000 port
+		  1 = /dev/cuv1		Second VS-1000 port
+		    ...
+
+ 106 block	Compaq Next Generation Drive Array, third controller
+		  0 = /dev/cciss/c2d0	First logical drive, whole disk
+		 16 = /dev/cciss/c2d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c2d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 107 char	3Dfx Voodoo Graphics device
+		  0 = /dev/3dfx		Primary 3Dfx graphics device
+
+ 107 block	Compaq Next Generation Drive Array, fourth controller
+		  0 = /dev/cciss/c3d0	First logical drive, whole disk
+		 16 = /dev/cciss/c3d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c3d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 108 char	Device independent PPP interface
+		  0 = /dev/ppp		Device independent PPP interface
+
+ 108 block	Compaq Next Generation Drive Array, fifth controller
+		  0 = /dev/cciss/c4d0	First logical drive, whole disk
+		 16 = /dev/cciss/c4d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c4d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 109 char	Reserved for logical volume manager
+
+ 109 block	Compaq Next Generation Drive Array, sixth controller
+		  0 = /dev/cciss/c5d0	First logical drive, whole disk
+		 16 = /dev/cciss/c5d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c5d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 110 char	miroMEDIA Surround board
+		  0 = /dev/srnd0	First miroMEDIA Surround board
+		  1 = /dev/srnd1	Second miroMEDIA Surround board
+		    ...
+
+ 110 block	Compaq Next Generation Drive Array, seventh controller
+		  0 = /dev/cciss/c6d0	First logical drive, whole disk
+		 16 = /dev/cciss/c6d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c6d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 111 char
+
+ 111 block	Compaq Next Generation Drive Array, eighth controller
+		  0 = /dev/cciss/c7d0	First logical drive, whole disk
+		 16 = /dev/cciss/c7d1	Second logical drive, whole disk
+		    ...
+		240 = /dev/cciss/c7d15	16th logical drive, whole disk
+
+		Partitions are handled the same way as for Mylex
+		DAC960 (see major number 48) except that the limit on
+		partitions is 15.
+
+ 112 char	ISI serial card
+		  0 = /dev/ttyM0	First ISI port
+		  1 = /dev/ttyM1	Second ISI port
+		    ...
+
+		There is currently a device-naming conflict between
+		these and PAM multimodems (major 78).
+
+ 112 block	IBM iSeries virtual disk
+		  0 = /dev/iseries/vda	First virtual disk, whole disk
+		  8 = /dev/iseries/vdb	Second virtual disk, whole disk
+		    ...
+		200 = /dev/iseries/vdz	26th virtual disk, whole disk
+		208 = /dev/iseries/vdaa	27th virtual disk, whole disk
+		    ...
+		248 = /dev/iseries/vdaf	32nd virtual disk, whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 7.
+
+ 113 char	ISI serial card - alternate devices
+		  0 = /dev/cum0		Callout device for ttyM0
+		  1 = /dev/cum1		Callout device for ttyM1
+		    ...
+
+ 113 block	IBM iSeries virtual CD-ROM
+		  0 = /dev/iseries/vcda	First virtual CD-ROM
+		  1 = /dev/iseries/vcdb	Second virtual CD-ROM
+		    ...
+
+ 114 char	Picture Elements ISE board
+		  0 = /dev/ise0		First ISE board
+		  1 = /dev/ise1		Second ISE board
+		    ...
+		128 = /dev/isex0	Control node for first ISE board
+		129 = /dev/isex1	Control node for second ISE board
+		    ...
+
+		The ISE board is an embedded computer, optimized for
+		image processing. The /dev/iseN nodes are the general
+		I/O access to the board, the /dev/isex0 nodes command
+		nodes used to control the board.
+
+ 114 block       IDE BIOS powered software RAID interfaces such as the
+		Promise Fastrak
+
+		   0 = /dev/ataraid/d0
+		   1 = /dev/ataraid/d0p1
+		   2 = /dev/ataraid/d0p2
+		  ...
+		  16 = /dev/ataraid/d1
+		  17 = /dev/ataraid/d1p1
+		  18 = /dev/ataraid/d1p2
+		  ...
+		 255 = /dev/ataraid/d15p15
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 115 char	TI link cable devices (115 was formerly the console driver speaker)
+		  0 = /dev/tipar0    Parallel cable on first parallel port
+		  ...
+		  7 = /dev/tipar7    Parallel cable on seventh parallel port
+
+		  8 = /dev/tiser0    Serial cable on first serial port
+		  ...
+		 15 = /dev/tiser7    Serial cable on seventh serial port
+
+		 16 = /dev/tiusb0    First USB cable
+		  ...
+		 47 = /dev/tiusb31   32nd USB cable
+
+ 115 block       NetWare (NWFS) Devices (0-255)
+
+		The NWFS (NetWare) devices are used to present a
+		collection of NetWare Mirror Groups or NetWare
+		Partitions as a logical storage segment for
+		use in mounting NetWare volumes.  A maximum of
+		 256 NetWare volumes can be supported in a single
+		machine.
+
+		http://cgfa.telepac.pt/ftp2/kernel.org/linux/kernel/people/jmerkey/nwfs/
+
+		 0 = /dev/nwfs/v0    First NetWare (NWFS) Logical Volume
+		 1 = /dev/nwfs/v1    Second NetWare (NWFS) Logical Volume
+		 2 = /dev/nwfs/v2    Third NetWare (NWFS) Logical Volume
+		      ...
+		 255 = /dev/nwfs/v255    Last NetWare (NWFS) Logical Volume
+
+ 116 char	Advanced Linux Sound Driver (ALSA)
+
+ 116 block       MicroMemory battery backed RAM adapter (NVRAM)
+		Supports 16 boards, 15 partitions each.
+		Requested by neilb at cse.unsw.edu.au.
+
+		 0 = /dev/umem/d0      Whole of first board
+		 1 = /dev/umem/d0p1    First partition of first board
+		 2 = /dev/umem/d0p2    Second partition of first board
+		15 = /dev/umem/d0p15   15th partition of first board
+
+		16 = /dev/umem/d1      Whole of second board
+		17 = /dev/umem/d1p1    First partition of second board
+		    ...
+		255= /dev/umem/d15p15  15th partition of 16th board.
+
+ 117 char	[REMOVED] COSA/SRP synchronous serial card
+		  0 = /dev/cosa0c0	1st board, 1st channel
+		  1 = /dev/cosa0c1	1st board, 2nd channel
+		    ...
+		 16 = /dev/cosa1c0	2nd board, 1st channel
+		 17 = /dev/cosa1c1	2nd board, 2nd channel
+		    ...
+
+ 117 block       Enterprise Volume Management System (EVMS)
+
+		The EVMS driver uses a layered, plug-in model to provide
+		unparalleled flexibility and extensibility in managing
+		storage.  This allows for easy expansion or customization
+		of various levels of volume management.  Requested by
+		Mark Peloquin (peloquin at us.ibm.com).
+
+		Note: EVMS populates and manages all the devnodes in
+		/dev/evms.
+
+		http://sf.net/projects/evms
+
+		   0 = /dev/evms/block_device   EVMS block device
+		   1 = /dev/evms/legacyname1    First EVMS legacy device
+		   2 = /dev/evms/legacyname2    Second EVMS legacy device
+		    ...
+		    Both ranges can grow (down or up) until they meet.
+		    ...
+		 254 = /dev/evms/EVMSname2      Second EVMS native device
+		 255 = /dev/evms/EVMSname1      First EVMS native device
+
+		Note: legacyname(s) are derived from the normal legacy
+		device names.  For example, /dev/hda5 would become
+		/dev/evms/hda5.
+
+ 118 char	IBM Cryptographic Accelerator
+		  0 = /dev/ica	Virtual interface to all IBM Crypto Accelerators
+		  1 = /dev/ica0	IBMCA Device 0
+		  2 = /dev/ica1	IBMCA Device 1
+		    ...
+
+ 119 char	VMware virtual network control
+		  0 = /dev/vnet0	1st virtual network
+		  1 = /dev/vnet1	2nd virtual network
+		    ...
+
+ 120-127 char	LOCAL/EXPERIMENTAL USE
+
+ 120-127 block	LOCAL/EXPERIMENTAL USE
+		Allocated for local/experimental use.  For devices not
+		assigned official numbers, these ranges should be
+		used in order to avoid conflicting with future assignments.
+
+ 128-135 char	Unix98 PTY masters
+
+		These devices should not have corresponding device
+		nodes; instead they should be accessed through the
+		/dev/ptmx cloning interface.
+
+ 128 block       SCSI disk devices (128-143)
+		   0 = /dev/sddy         129th SCSI disk whole disk
+		  16 = /dev/sddz         130th SCSI disk whole disk
+		  32 = /dev/sdea         131th SCSI disk whole disk
+		    ...
+		 240 = /dev/sden         144th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 129 block       SCSI disk devices (144-159)
+		   0 = /dev/sdeo         145th SCSI disk whole disk
+		  16 = /dev/sdep         146th SCSI disk whole disk
+		  32 = /dev/sdeq         147th SCSI disk whole disk
+		    ...
+		 240 = /dev/sdfd         160th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 130 char 	(Misc devices)
+
+ 130 block       SCSI disk devices (160-175)
+		   0 = /dev/sdfe         161st SCSI disk whole disk
+		  16 = /dev/sdff         162nd SCSI disk whole disk
+		  32 = /dev/sdfg         163rd SCSI disk whole disk
+		    ...
+		 240 = /dev/sdft         176th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 131 block       SCSI disk devices (176-191)
+		   0 = /dev/sdfu         177th SCSI disk whole disk
+		  16 = /dev/sdfv         178th SCSI disk whole disk
+		  32 = /dev/sdfw         179th SCSI disk whole disk
+		    ...
+		 240 = /dev/sdgj         192nd SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 132 block       SCSI disk devices (192-207)
+		   0 = /dev/sdgk         193rd SCSI disk whole disk
+		  16 = /dev/sdgl         194th SCSI disk whole disk
+		  32 = /dev/sdgm         195th SCSI disk whole disk
+		    ...
+		 240 = /dev/sdgz         208th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 133 block       SCSI disk devices (208-223)
+		   0 = /dev/sdha         209th SCSI disk whole disk
+		  16 = /dev/sdhb         210th SCSI disk whole disk
+		  32 = /dev/sdhc         211th SCSI disk whole disk
+		    ...
+		 240 = /dev/sdhp         224th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 134 block       SCSI disk devices (224-239)
+		   0 = /dev/sdhq         225th SCSI disk whole disk
+		  16 = /dev/sdhr         226th SCSI disk whole disk
+		  32 = /dev/sdhs         227th SCSI disk whole disk
+		    ...
+		 240 = /dev/sdif         240th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 135 block       SCSI disk devices (240-255)
+		   0 = /dev/sdig         241st SCSI disk whole disk
+		  16 = /dev/sdih         242nd SCSI disk whole disk
+		  32 = /dev/sdih         243rd SCSI disk whole disk
+		    ...
+		 240 = /dev/sdiv         256th SCSI disk whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 136-143 char	Unix98 PTY slaves
+		  0 = /dev/pts/0	First Unix98 pseudo-TTY
+		  1 = /dev/pts/1	Second Unix98 pseudo-TTY
+		    ...
+
+		These device nodes are automatically generated with
+		the proper permissions and modes by mounting the
+		devpts filesystem onto /dev/pts with the appropriate
+		mount options (distribution dependent, however, on
+		*most* distributions the appropriate options are
+		"mode=0620,gid=<gid of the "tty" group>".)
+
+ 136 block	Mylex DAC960 PCI RAID controller; ninth controller
+		  0 = /dev/rd/c8d0	First disk, whole disk
+		  8 = /dev/rd/c8d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c8d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 137 block	Mylex DAC960 PCI RAID controller; tenth controller
+		  0 = /dev/rd/c9d0	First disk, whole disk
+		  8 = /dev/rd/c9d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c9d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 138 block	Mylex DAC960 PCI RAID controller; eleventh controller
+		  0 = /dev/rd/c10d0	First disk, whole disk
+		  8 = /dev/rd/c10d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c10d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 139 block	Mylex DAC960 PCI RAID controller; twelfth controller
+		  0 = /dev/rd/c11d0	First disk, whole disk
+		  8 = /dev/rd/c11d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c11d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 140 block	Mylex DAC960 PCI RAID controller; thirteenth controller
+		  0 = /dev/rd/c12d0	First disk, whole disk
+		  8 = /dev/rd/c12d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c12d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 141 block	Mylex DAC960 PCI RAID controller; fourteenth controller
+		  0 = /dev/rd/c13d0	First disk, whole disk
+		  8 = /dev/rd/c13d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c13d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 142 block	Mylex DAC960 PCI RAID controller; fifteenth controller
+		  0 = /dev/rd/c14d0	First disk, whole disk
+		  8 = /dev/rd/c14d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c14d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 143 block	Mylex DAC960 PCI RAID controller; sixteenth controller
+		  0 = /dev/rd/c15d0	First disk, whole disk
+		  8 = /dev/rd/c15d1	Second disk, whole disk
+		    ...
+		248 = /dev/rd/c15d31	32nd disk, whole disk
+
+		Partitions are handled as for major 48.
+
+ 144 char	Encapsulated PPP
+		  0 = /dev/pppox0	First PPP over Ethernet
+		    ...
+		 63 = /dev/pppox63	64th PPP over Ethernet
+
+		This is primarily used for ADSL.
+
+		The SST 5136-DN DeviceNet interface driver has been
+		relocated to major 183 due to an unfortunate conflict.
+
+ 144 block	Expansion Area #1 for more non-device (e.g. NFS) mounts
+		  0 = mounted device 256
+		255 = mounted device 511
+
+ 145 char	SAM9407-based soundcard
+		  0 = /dev/sam0_mixer
+		  1 = /dev/sam0_sequencer
+		  2 = /dev/sam0_midi00
+		  3 = /dev/sam0_dsp
+		  4 = /dev/sam0_audio
+		  6 = /dev/sam0_sndstat
+		 18 = /dev/sam0_midi01
+		 34 = /dev/sam0_midi02
+		 50 = /dev/sam0_midi03
+		 64 = /dev/sam1_mixer
+		    ...
+		128 = /dev/sam2_mixer
+		    ...
+		192 = /dev/sam3_mixer
+		    ...
+
+		Device functions match OSS, but offer a number of
+		addons, which are sam9407 specific.  OSS can be
+		operated simultaneously, taking care of the codec.
+
+ 145 block	Expansion Area #2 for more non-device (e.g. NFS) mounts
+		  0 = mounted device 512
+		255 = mounted device 767
+
+ 146 char	SYSTRAM SCRAMNet mirrored-memory network
+		  0 = /dev/scramnet0	First SCRAMNet device
+		  1 = /dev/scramnet1	Second SCRAMNet device
+		    ...
+
+ 146 block	Expansion Area #3 for more non-device (e.g. NFS) mounts
+		  0 = mounted device 768
+		255 = mounted device 1023
+
+ 147 char	Aureal Semiconductor Vortex Audio device
+		  0 = /dev/aureal0	First Aureal Vortex
+		  1 = /dev/aureal1	Second Aureal Vortex
+		    ...
+
+ 147 block	Distributed Replicated Block Device (DRBD)
+		  0 = /dev/drbd0	First DRBD device
+		  1 = /dev/drbd1	Second DRBD device
+		    ...
+
+ 148 char	Technology Concepts serial card
+		  0 = /dev/ttyT0	First TCL port
+		  1 = /dev/ttyT1	Second TCL port
+		    ...
+
+ 149 char	Technology Concepts serial card - alternate devices
+		  0 = /dev/cut0		Callout device for ttyT0
+		  1 = /dev/cut0		Callout device for ttyT1
+		    ...
+
+ 150 char	Real-Time Linux FIFOs
+		  0 = /dev/rtf0		First RTLinux FIFO
+		  1 = /dev/rtf1		Second RTLinux FIFO
+		    ...
+
+ 151 char	DPT I2O SmartRaid V controller
+		  0 = /dev/dpti0	First DPT I2O adapter
+		  1 = /dev/dpti1	Second DPT I2O adapter
+		    ...
+
+ 152 char	EtherDrive Control Device
+		  0 = /dev/etherd/ctl	Connect/Disconnect an EtherDrive
+		  1 = /dev/etherd/err	Monitor errors
+		  2 = /dev/etherd/raw	Raw AoE packet monitor
+
+ 152 block	EtherDrive Block Devices
+		  0 = /dev/etherd/0	EtherDrive 0
+		    ...
+		255 = /dev/etherd/255	EtherDrive 255
+
+ 153 char	SPI Bus Interface (sometimes referred to as MicroWire)
+		  0 = /dev/spi0		First SPI device on the bus
+		  1 = /dev/spi1		Second SPI device on the bus
+		    ...
+		 15 = /dev/spi15	Sixteenth SPI device on the bus
+
+ 153 block	Enhanced Metadisk RAID (EMD) storage units
+		  0 = /dev/emd/0	First unit
+		  1 = /dev/emd/0p1	Partition 1 on First unit
+		  2 = /dev/emd/0p2	Partition 2 on First unit
+		    ...
+		 15 = /dev/emd/0p15	Partition 15 on First unit
+
+		 16 = /dev/emd/1	Second unit
+		 32 = /dev/emd/2	Third unit
+		    ...
+		240 = /dev/emd/15	Sixteenth unit
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 154 char	Specialix RIO serial card
+		  0 = /dev/ttySR0	First RIO port
+		    ...
+		255 = /dev/ttySR255	256th RIO port
+
+ 155 char	Specialix RIO serial card - alternate devices
+		  0 = /dev/cusr0	Callout device for ttySR0
+		    ...
+		255 = /dev/cusr255	Callout device for ttySR255
+
+ 156 char	Specialix RIO serial card
+		  0 = /dev/ttySR256	257th RIO port
+		    ...
+		255 = /dev/ttySR511	512th RIO port
+
+ 157 char	Specialix RIO serial card - alternate devices
+		  0 = /dev/cusr256	Callout device for ttySR256
+		    ...
+		255 = /dev/cusr511	Callout device for ttySR511
+
+ 158 char	Dialogic GammaLink fax driver
+		  0 = /dev/gfax0	GammaLink channel 0
+		  1 = /dev/gfax1	GammaLink channel 1
+		    ...
+
+ 159 char	RESERVED
+
+ 159 block	RESERVED
+
+ 160 char	General Purpose Instrument Bus (GPIB)
+		  0 = /dev/gpib0	First GPIB bus
+		  1 = /dev/gpib1	Second GPIB bus
+		    ...
+
+ 160 block       Carmel 8-port SATA Disks on First Controller
+		  0 = /dev/carmel/0     SATA disk 0 whole disk
+		  1 = /dev/carmel/0p1   SATA disk 0 partition 1
+		    ...
+		 31 = /dev/carmel/0p31  SATA disk 0 partition 31
+
+		 32 = /dev/carmel/1     SATA disk 1 whole disk
+		 64 = /dev/carmel/2     SATA disk 2 whole disk
+		    ...
+		224 = /dev/carmel/7     SATA disk 7 whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 31.
+
+ 161 char	IrCOMM devices (IrDA serial/parallel emulation)
+		  0 = /dev/ircomm0	First IrCOMM device
+		  1 = /dev/ircomm1	Second IrCOMM device
+		    ...
+		 16 = /dev/irlpt0	First IrLPT device
+		 17 = /dev/irlpt1	Second IrLPT device
+		    ...
+
+ 161 block       Carmel 8-port SATA Disks on Second Controller
+		  0 = /dev/carmel/8     SATA disk 8 whole disk
+		  1 = /dev/carmel/8p1   SATA disk 8 partition 1
+		    ...
+		 31 = /dev/carmel/8p31  SATA disk 8 partition 31
+
+		 32 = /dev/carmel/9     SATA disk 9 whole disk
+		 64 = /dev/carmel/10    SATA disk 10 whole disk
+		    ...
+		224 = /dev/carmel/15    SATA disk 15 whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 31.
+
+ 162 char	Used for (now removed) raw block device interface
+
+ 163 char
+
+ 164 char	Chase Research AT/PCI-Fast serial card
+		  0 = /dev/ttyCH0	AT/PCI-Fast board 0, port 0
+		    ...
+		 15 = /dev/ttyCH15	AT/PCI-Fast board 0, port 15
+		 16 = /dev/ttyCH16	AT/PCI-Fast board 1, port 0
+		    ...
+		 31 = /dev/ttyCH31	AT/PCI-Fast board 1, port 15
+		 32 = /dev/ttyCH32	AT/PCI-Fast board 2, port 0
+		    ...
+		 47 = /dev/ttyCH47	AT/PCI-Fast board 2, port 15
+		 48 = /dev/ttyCH48	AT/PCI-Fast board 3, port 0
+		    ...
+		 63 = /dev/ttyCH63	AT/PCI-Fast board 3, port 15
+
+ 165 char	Chase Research AT/PCI-Fast serial card - alternate devices
+		  0 = /dev/cuch0	Callout device for ttyCH0
+		    ...
+		 63 = /dev/cuch63	Callout device for ttyCH63
+
+ 166 char	ACM USB modems
+		  0 = /dev/ttyACM0	First ACM modem
+		  1 = /dev/ttyACM1	Second ACM modem
+		    ...
+
+ 167 char	ACM USB modems - alternate devices
+		  0 = /dev/cuacm0	Callout device for ttyACM0
+		  1 = /dev/cuacm1	Callout device for ttyACM1
+		    ...
+
+ 168 char	Eracom CSA7000 PCI encryption adaptor
+		  0 = /dev/ecsa0	First CSA7000
+		  1 = /dev/ecsa1	Second CSA7000
+		    ...
+
+ 169 char	Eracom CSA8000 PCI encryption adaptor
+		  0 = /dev/ecsa8-0	First CSA8000
+		  1 = /dev/ecsa8-1	Second CSA8000
+		    ...
+
+ 170 char	AMI MegaRAC remote access controller
+		  0 = /dev/megarac0	First MegaRAC card
+		  1 = /dev/megarac1	Second MegaRAC card
+		    ...
+
+ 171 char	Reserved for IEEE 1394 (Firewire)
+
+ 172 char	Moxa Intellio serial card
+		  0 = /dev/ttyMX0	First Moxa port
+		  1 = /dev/ttyMX1	Second Moxa port
+		    ...
+		127 = /dev/ttyMX127	128th Moxa port
+		128 = /dev/moxactl	Moxa control port
+
+ 173 char	Moxa Intellio serial card - alternate devices
+		  0 = /dev/cumx0	Callout device for ttyMX0
+		  1 = /dev/cumx1	Callout device for ttyMX1
+		    ...
+		127 = /dev/cumx127	Callout device for ttyMX127
+
+ 174 char	SmartIO serial card
+		  0 = /dev/ttySI0	First SmartIO port
+		  1 = /dev/ttySI1	Second SmartIO port
+		    ...
+
+ 175 char	SmartIO serial card - alternate devices
+		  0 = /dev/cusi0	Callout device for ttySI0
+		  1 = /dev/cusi1	Callout device for ttySI1
+		    ...
+
+ 176 char	nCipher nFast PCI crypto accelerator
+		  0 = /dev/nfastpci0	First nFast PCI device
+		  1 = /dev/nfastpci1	First nFast PCI device
+		    ...
+
+ 177 char	TI PCILynx memory spaces
+		  0 = /dev/pcilynx/aux0	 AUX space of first PCILynx card
+		    ...
+		 15 = /dev/pcilynx/aux15 AUX space of 16th PCILynx card
+		 16 = /dev/pcilynx/rom0	 ROM space of first PCILynx card
+		    ...
+		 31 = /dev/pcilynx/rom15 ROM space of 16th PCILynx card
+		 32 = /dev/pcilynx/ram0	 RAM space of first PCILynx card
+		    ...
+		 47 = /dev/pcilynx/ram15 RAM space of 16th PCILynx card
+
+ 178 char	Giganet cLAN1xxx virtual interface adapter
+		  0 = /dev/clanvi0	First cLAN adapter
+		  1 = /dev/clanvi1	Second cLAN adapter
+		    ...
+
+ 179 block       MMC block devices
+		  0 = /dev/mmcblk0      First SD/MMC card
+		  1 = /dev/mmcblk0p1    First partition on first MMC card
+		  8 = /dev/mmcblk1      Second SD/MMC card
+		    ...
+
+		The start of next SD/MMC card can be configured with
+		CONFIG_MMC_BLOCK_MINORS, or overridden at boot/modprobe
+		time using the mmcblk.perdev_minors option. That would
+		bump the offset between each card to be the configured
+		value instead of the default 8.
+
+ 179 char	CCube DVXChip-based PCI products
+		  0 = /dev/dvxirq0	First DVX device
+		  1 = /dev/dvxirq1	Second DVX device
+		    ...
+
+ 180 char	USB devices
+		  0 = /dev/usb/lp0	First USB printer
+		    ...
+		 15 = /dev/usb/lp15	16th USB printer
+		 48 = /dev/usb/scanner0	First USB scanner
+		    ...
+		 63 = /dev/usb/scanner15 16th USB scanner
+		 64 = /dev/usb/rio500	Diamond Rio 500
+		 65 = /dev/usb/usblcd	USBLCD Interface (info@usblcd.de)
+		 66 = /dev/usb/cpad0	Synaptics cPad (mouse/LCD)
+		 96 = /dev/usb/hiddev0	1st USB HID device
+		    ...
+		111 = /dev/usb/hiddev15	16th USB HID device
+		112 = /dev/usb/auer0	1st auerswald ISDN device
+		    ...
+		127 = /dev/usb/auer15	16th auerswald ISDN device
+		128 = /dev/usb/brlvgr0	First Braille Voyager device
+		    ...
+		131 = /dev/usb/brlvgr3	Fourth Braille Voyager device
+		132 = /dev/usb/idmouse	ID Mouse (fingerprint scanner) device
+		133 = /dev/usb/sisusbvga1	First SiSUSB VGA device
+		    ...
+		140 = /dev/usb/sisusbvga8	Eighth SISUSB VGA device
+		144 = /dev/usb/lcd	USB LCD device
+		160 = /dev/usb/legousbtower0	1st USB Legotower device
+		    ...
+		175 = /dev/usb/legousbtower15	16th USB Legotower device
+		176 = /dev/usb/usbtmc1	First USB TMC device
+		   ...
+		191 = /dev/usb/usbtmc16	16th USB TMC device
+		192 = /dev/usb/yurex1	First USB Yurex device
+		   ...
+		209 = /dev/usb/yurex16	16th USB Yurex device
+
+ 180 block	USB block devices
+		  0 = /dev/uba		First USB block device
+		  8 = /dev/ubb		Second USB block device
+		 16 = /dev/ubc		Third USB block device
+		    ...
+
+ 181 char	Conrad Electronic parallel port radio clocks
+		  0 = /dev/pcfclock0	First Conrad radio clock
+		  1 = /dev/pcfclock1	Second Conrad radio clock
+		    ...
+
+ 182 char	Picture Elements THR2 binarizer
+		  0 = /dev/pethr0	First THR2 board
+		  1 = /dev/pethr1	Second THR2 board
+		    ...
+
+ 183 char	SST 5136-DN DeviceNet interface
+		  0 = /dev/ss5136dn0	First DeviceNet interface
+		  1 = /dev/ss5136dn1	Second DeviceNet interface
+		    ...
+
+		This device used to be assigned to major number 144.
+		It had to be moved due to an unfortunate conflict.
+
+ 184 char	Picture Elements' video simulator/sender
+		  0 = /dev/pevss0	First sender board
+		  1 = /dev/pevss1	Second sender board
+		    ...
+
+ 185 char	InterMezzo high availability file system
+		  0 = /dev/intermezzo0	First cache manager
+		  1 = /dev/intermezzo1	Second cache manager
+		    ...
+
+		See http://web.archive.org/web/20080115195241/
+		http://inter-mezzo.org/index.html
+
+ 186 char	Object-based storage control device
+		  0 = /dev/obd0		First obd control device
+		  1 = /dev/obd1		Second obd control device
+		    ...
+
+		See ftp://ftp.lustre.org/pub/obd for code and information.
+
+ 187 char	DESkey hardware encryption device
+		  0 = /dev/deskey0	First DES key
+		  1 = /dev/deskey1	Second DES key
+		    ...
+
+ 188 char	USB serial converters
+		  0 = /dev/ttyUSB0	First USB serial converter
+		  1 = /dev/ttyUSB1	Second USB serial converter
+		    ...
+
+ 189 char	USB serial converters - alternate devices
+		  0 = /dev/cuusb0	Callout device for ttyUSB0
+		  1 = /dev/cuusb1	Callout device for ttyUSB1
+		    ...
+
+ 190 char	Kansas City tracker/tuner card
+		  0 = /dev/kctt0	First KCT/T card
+		  1 = /dev/kctt1	Second KCT/T card
+		    ...
+
+ 191 char	Reserved for PCMCIA
+
+ 192 char	Kernel profiling interface
+		  0 = /dev/profile	Profiling control device
+		  1 = /dev/profile0	Profiling device for CPU 0
+		  2 = /dev/profile1	Profiling device for CPU 1
+		    ...
+
+ 193 char	Kernel event-tracing interface
+		  0 = /dev/trace	Tracing control device
+		  1 = /dev/trace0	Tracing device for CPU 0
+		  2 = /dev/trace1	Tracing device for CPU 1
+		    ...
+
+ 194 char	linVideoStreams (LINVS)
+		  0 = /dev/mvideo/status0	Video compression status
+		  1 = /dev/mvideo/stream0	Video stream
+		  2 = /dev/mvideo/frame0	Single compressed frame
+		  3 = /dev/mvideo/rawframe0	Raw uncompressed frame
+		  4 = /dev/mvideo/codec0	Direct codec access
+		  5 = /dev/mvideo/video4linux0	Video4Linux compatibility
+
+		 16 = /dev/mvideo/status1	Second device
+		    ...
+		 32 = /dev/mvideo/status2	Third device
+		    ...
+		    ...
+		240 = /dev/mvideo/status15	16th device
+		    ...
+
+ 195 char	Nvidia graphics devices
+		  0 = /dev/nvidia0		First Nvidia card
+		  1 = /dev/nvidia1		Second Nvidia card
+		    ...
+		255 = /dev/nvidiactl		Nvidia card control device
+
+ 196 char	Tormenta T1 card
+		  0 = /dev/tor/0		Master control channel for all cards
+		  1 = /dev/tor/1		First DS0
+		  2 = /dev/tor/2		Second DS0
+		    ...
+		 48 = /dev/tor/48		48th DS0
+		 49 = /dev/tor/49		First pseudo-channel
+		 50 = /dev/tor/50		Second pseudo-channel
+		    ...
+
+ 197 char	OpenTNF tracing facility
+		  0 = /dev/tnf/t0		Trace 0 data extraction
+		  1 = /dev/tnf/t1		Trace 1 data extraction
+		    ...
+		128 = /dev/tnf/status		Tracing facility status
+		130 = /dev/tnf/trace		Tracing device
+
+ 198 char	Total Impact TPMP2 quad coprocessor PCI card
+		  0 = /dev/tpmp2/0		First card
+		  1 = /dev/tpmp2/1		Second card
+		    ...
+
+ 199 char	Veritas volume manager (VxVM) volumes
+		  0 = /dev/vx/rdsk/*/*		First volume
+		  1 = /dev/vx/rdsk/*/*		Second volume
+		    ...
+
+ 199 block	Veritas volume manager (VxVM) volumes
+		  0 = /dev/vx/dsk/*/*		First volume
+		  1 = /dev/vx/dsk/*/*		Second volume
+		    ...
+
+		The namespace in these directories is maintained by
+		the user space VxVM software.
+
+ 200 char	Veritas VxVM configuration interface
+		   0 = /dev/vx/config		Configuration access node
+		   1 = /dev/vx/trace		Volume i/o trace access node
+		   2 = /dev/vx/iod		Volume i/o daemon access node
+		   3 = /dev/vx/info		Volume information access node
+		   4 = /dev/vx/task		Volume tasks access node
+		   5 = /dev/vx/taskmon		Volume tasks monitor daemon
+
+ 201 char	Veritas VxVM dynamic multipathing driver
+		  0 = /dev/vx/rdmp/*		First multipath device
+		  1 = /dev/vx/rdmp/*		Second multipath device
+		    ...
+ 201 block	Veritas VxVM dynamic multipathing driver
+		  0 = /dev/vx/dmp/*		First multipath device
+		  1 = /dev/vx/dmp/*		Second multipath device
+		    ...
+
+		The namespace in these directories is maintained by
+		the user space VxVM software.
+
+ 202 char	CPU model-specific registers
+		  0 = /dev/cpu/0/msr		MSRs on CPU 0
+		  1 = /dev/cpu/1/msr		MSRs on CPU 1
+		    ...
+
+ 202 block	Xen Virtual Block Device
+		  0 = /dev/xvda       First Xen VBD whole disk
+		  16 = /dev/xvdb      Second Xen VBD whole disk
+		  32 = /dev/xvdc      Third Xen VBD whole disk
+		    ...
+		  240 = /dev/xvdp     Sixteenth Xen VBD whole disk
+
+		Partitions are handled in the same way as for IDE
+		disks (see major number 3) except that the limit on
+		partitions is 15.
+
+ 203 char	CPU CPUID information
+		  0 = /dev/cpu/0/cpuid		CPUID on CPU 0
+		  1 = /dev/cpu/1/cpuid		CPUID on CPU 1
+		    ...
+
+ 204 char	Low-density serial ports
+		  0 = /dev/ttyLU0		LinkUp Systems L72xx UART - port 0
+		  1 = /dev/ttyLU1		LinkUp Systems L72xx UART - port 1
+		  2 = /dev/ttyLU2		LinkUp Systems L72xx UART - port 2
+		  3 = /dev/ttyLU3		LinkUp Systems L72xx UART - port 3
+		  4 = /dev/ttyFB0		Intel Footbridge (ARM)
+		  5 = /dev/ttySA0		StrongARM builtin serial port 0
+		  6 = /dev/ttySA1		StrongARM builtin serial port 1
+		  7 = /dev/ttySA2		StrongARM builtin serial port 2
+		  8 = /dev/ttySC0		SCI serial port (SuperH) - port 0
+		  9 = /dev/ttySC1		SCI serial port (SuperH) - port 1
+		 10 = /dev/ttySC2		SCI serial port (SuperH) - port 2
+		 11 = /dev/ttySC3		SCI serial port (SuperH) - port 3
+		 12 = /dev/ttyFW0		Firmware console - port 0
+		 13 = /dev/ttyFW1		Firmware console - port 1
+		 14 = /dev/ttyFW2		Firmware console - port 2
+		 15 = /dev/ttyFW3		Firmware console - port 3
+		 16 = /dev/ttyAM0		ARM "AMBA" serial port 0
+		    ...
+		 31 = /dev/ttyAM15		ARM "AMBA" serial port 15
+		 32 = /dev/ttyDB0		DataBooster serial port 0
+		    ...
+		 39 = /dev/ttyDB7		DataBooster serial port 7
+		 40 = /dev/ttySG0		SGI Altix console port
+		 41 = /dev/ttySMX0		Motorola i.MX - port 0
+		 42 = /dev/ttySMX1		Motorola i.MX - port 1
+		 43 = /dev/ttySMX2		Motorola i.MX - port 2
+		 44 = /dev/ttyMM0		Marvell MPSC - port 0 (obsolete unused)
+		 45 = /dev/ttyMM1		Marvell MPSC - port 1 (obsolete unused)
+		 46 = /dev/ttyCPM0		PPC CPM (SCC or SMC) - port 0
+		    ...
+		 51 = /dev/ttyCPM5		PPC CPM (SCC or SMC) - port 5
+		 82 = /dev/ttyVR0		NEC VR4100 series SIU
+		 83 = /dev/ttyVR1		NEC VR4100 series DSIU
+		 148 = /dev/ttyPSC0		PPC PSC - port 0
+		    ...
+		 153 = /dev/ttyPSC5		PPC PSC - port 5
+		 154 = /dev/ttyAT0		ATMEL serial port 0
+		    ...
+		 169 = /dev/ttyAT15		ATMEL serial port 15
+		 170 = /dev/ttyNX0		Hilscher netX serial port 0
+		    ...
+		 185 = /dev/ttyNX15		Hilscher netX serial port 15
+		 186 = /dev/ttyJ0		JTAG1 DCC protocol based serial port emulation
+
+		 If maximum number of uartlite serial ports is more than 4, then the driver
+		 uses dynamic allocation instead of static allocation for major number.
+		 187 = /dev/ttyUL0		Xilinx uartlite - port 0
+		    ...
+		 190 = /dev/ttyUL3		Xilinx uartlite - port 3
+		 191 = /dev/xvc0		Xen virtual console - port 0
+		 192 = /dev/ttyPZ0		pmac_zilog - port 0
+		    ...
+		 195 = /dev/ttyPZ3		pmac_zilog - port 3
+		 196 = /dev/ttyTX0		TX39/49 serial port 0
+		    ...
+		 204 = /dev/ttyTX7		TX39/49 serial port 7
+		 205 = /dev/ttySC0		SC26xx serial port 0
+		 206 = /dev/ttySC1		SC26xx serial port 1
+		 207 = /dev/ttySC2		SC26xx serial port 2
+		 208 = /dev/ttySC3		SC26xx serial port 3
+		 209 = /dev/ttyMAX0		MAX3100 serial port 0
+		 210 = /dev/ttyMAX1		MAX3100 serial port 1
+		 211 = /dev/ttyMAX2		MAX3100 serial port 2
+		 212 = /dev/ttyMAX3		MAX3100 serial port 3
+
+ 205 char	Low-density serial ports (alternate device)
+		  0 = /dev/culu0		Callout device for ttyLU0
+		  1 = /dev/culu1		Callout device for ttyLU1
+		  2 = /dev/culu2		Callout device for ttyLU2
+		  3 = /dev/culu3		Callout device for ttyLU3
+		  4 = /dev/cufb0		Callout device for ttyFB0
+		  5 = /dev/cusa0		Callout device for ttySA0
+		  6 = /dev/cusa1		Callout device for ttySA1
+		  7 = /dev/cusa2		Callout device for ttySA2
+		  8 = /dev/cusc0		Callout device for ttySC0
+		  9 = /dev/cusc1		Callout device for ttySC1
+		 10 = /dev/cusc2		Callout device for ttySC2
+		 11 = /dev/cusc3		Callout device for ttySC3
+		 12 = /dev/cufw0		Callout device for ttyFW0
+		 13 = /dev/cufw1		Callout device for ttyFW1
+		 14 = /dev/cufw2		Callout device for ttyFW2
+		 15 = /dev/cufw3		Callout device for ttyFW3
+		 16 = /dev/cuam0		Callout device for ttyAM0
+		    ...
+		 31 = /dev/cuam15		Callout device for ttyAM15
+		 32 = /dev/cudb0		Callout device for ttyDB0
+		    ...
+		 39 = /dev/cudb7		Callout device for ttyDB7
+		 40 = /dev/cusg0		Callout device for ttySG0
+		 41 = /dev/ttycusmx0		Callout device for ttySMX0
+		 42 = /dev/ttycusmx1		Callout device for ttySMX1
+		 43 = /dev/ttycusmx2		Callout device for ttySMX2
+		 46 = /dev/cucpm0		Callout device for ttyCPM0
+		    ...
+		 51 = /dev/cucpm5		Callout device for ttyCPM5
+		 82 = /dev/cuvr0		Callout device for ttyVR0
+		 83 = /dev/cuvr1		Callout device for ttyVR1
+
+ 206 char	OnStream SC-x0 tape devices
+		  0 = /dev/osst0		First OnStream SCSI tape, mode 0
+		  1 = /dev/osst1		Second OnStream SCSI tape, mode 0
+		    ...
+		 32 = /dev/osst0l		First OnStream SCSI tape, mode 1
+		 33 = /dev/osst1l		Second OnStream SCSI tape, mode 1
+		    ...
+		 64 = /dev/osst0m		First OnStream SCSI tape, mode 2
+		 65 = /dev/osst1m		Second OnStream SCSI tape, mode 2
+		    ...
+		 96 = /dev/osst0a		First OnStream SCSI tape, mode 3
+		 97 = /dev/osst1a		Second OnStream SCSI tape, mode 3
+		    ...
+		128 = /dev/nosst0		No rewind version of /dev/osst0
+		129 = /dev/nosst1		No rewind version of /dev/osst1
+		    ...
+		160 = /dev/nosst0l		No rewind version of /dev/osst0l
+		161 = /dev/nosst1l		No rewind version of /dev/osst1l
+		    ...
+		192 = /dev/nosst0m		No rewind version of /dev/osst0m
+		193 = /dev/nosst1m		No rewind version of /dev/osst1m
+		    ...
+		224 = /dev/nosst0a		No rewind version of /dev/osst0a
+		225 = /dev/nosst1a		No rewind version of /dev/osst1a
+		    ...
+
+		The OnStream SC-x0 SCSI tapes do not support the
+		standard SCSI SASD command set and therefore need
+		their own driver "osst". Note that the IDE, USB (and
+		maybe ParPort) versions may be driven via ide-scsi or
+		usb-storage SCSI emulation and this osst device and
+		driver as well.  The ADR-x0 drives are QIC-157
+		compliant and don't need osst.
+
+ 207 char	Compaq ProLiant health feature indicate
+		  0 = /dev/cpqhealth/cpqw	Redirector interface
+		  1 = /dev/cpqhealth/crom	EISA CROM
+		  2 = /dev/cpqhealth/cdt	Data Table
+		  3 = /dev/cpqhealth/cevt	Event Log
+		  4 = /dev/cpqhealth/casr	Automatic Server Recovery
+		  5 = /dev/cpqhealth/cecc	ECC Memory
+		  6 = /dev/cpqhealth/cmca	Machine Check Architecture
+		  7 = /dev/cpqhealth/ccsm	Deprecated CDT
+		  8 = /dev/cpqhealth/cnmi	NMI Handling
+		  9 = /dev/cpqhealth/css	Sideshow Management
+		 10 = /dev/cpqhealth/cram	CMOS interface
+		 11 = /dev/cpqhealth/cpci	PCI IRQ interface
+
+ 208 char	User space serial ports
+		  0 = /dev/ttyU0		First user space serial port
+		  1 = /dev/ttyU1		Second user space serial port
+		    ...
+
+ 209 char	User space serial ports (alternate devices)
+		  0 = /dev/cuu0			Callout device for ttyU0
+		  1 = /dev/cuu1			Callout device for ttyU1
+		    ...
+
+ 210 char	SBE, Inc. sync/async serial card
+		  0 = /dev/sbei/wxcfg0		Configuration device for board 0
+		  1 = /dev/sbei/dld0		Download device for board 0
+		  2 = /dev/sbei/wan00		WAN device, port 0, board 0
+		  3 = /dev/sbei/wan01		WAN device, port 1, board 0
+		  4 = /dev/sbei/wan02		WAN device, port 2, board 0
+		  5 = /dev/sbei/wan03		WAN device, port 3, board 0
+		  6 = /dev/sbei/wanc00		WAN clone device, port 0, board 0
+		  7 = /dev/sbei/wanc01		WAN clone device, port 1, board 0
+		  8 = /dev/sbei/wanc02		WAN clone device, port 2, board 0
+		  9 = /dev/sbei/wanc03		WAN clone device, port 3, board 0
+		 10 = /dev/sbei/wxcfg1		Configuration device for board 1
+		 11 = /dev/sbei/dld1		Download device for board 1
+		 12 = /dev/sbei/wan10		WAN device, port 0, board 1
+		 13 = /dev/sbei/wan11		WAN device, port 1, board 1
+		 14 = /dev/sbei/wan12		WAN device, port 2, board 1
+		 15 = /dev/sbei/wan13		WAN device, port 3, board 1
+		 16 = /dev/sbei/wanc10		WAN clone device, port 0, board 1
+		 17 = /dev/sbei/wanc11		WAN clone device, port 1, board 1
+		 18 = /dev/sbei/wanc12		WAN clone device, port 2, board 1
+		 19 = /dev/sbei/wanc13		WAN clone device, port 3, board 1
+		    ...
+
+		Yes, each board is really spaced 10 (decimal) apart.
+
+ 211 char	Addinum CPCI1500 digital I/O card
+		  0 = /dev/addinum/cpci1500/0	First CPCI1500 card
+		  1 = /dev/addinum/cpci1500/1	Second CPCI1500 card
+		    ...
+
+ 212 char	LinuxTV.org DVB driver subsystem
+		  0 = /dev/dvb/adapter0/video0    first video decoder of first card
+		  1 = /dev/dvb/adapter0/audio0    first audio decoder of first card
+		  2 = /dev/dvb/adapter0/sec0      (obsolete/unused)
+		  3 = /dev/dvb/adapter0/frontend0 first frontend device of first card
+		  4 = /dev/dvb/adapter0/demux0    first demux device of first card
+		  5 = /dev/dvb/adapter0/dvr0      first digital video recoder device of first card
+		  6 = /dev/dvb/adapter0/ca0       first common access port of first card
+		  7 = /dev/dvb/adapter0/net0      first network device of first card
+		  8 = /dev/dvb/adapter0/osd0      first on-screen-display device of first card
+		  9 = /dev/dvb/adapter0/video1    second video decoder of first card
+		    ...
+		 64 = /dev/dvb/adapter1/video0    first video decoder of second card
+		    ...
+		128 = /dev/dvb/adapter2/video0    first video decoder of third card
+		    ...
+		196 = /dev/dvb/adapter3/video0    first video decoder of fourth card
+
+ 216 char	Bluetooth RFCOMM TTY devices
+		  0 = /dev/rfcomm0		First Bluetooth RFCOMM TTY device
+		  1 = /dev/rfcomm1		Second Bluetooth RFCOMM TTY device
+		    ...
+
+ 217 char	Bluetooth RFCOMM TTY devices (alternate devices)
+		  0 = /dev/curf0		Callout device for rfcomm0
+		  1 = /dev/curf1		Callout device for rfcomm1
+		    ...
+
+ 218 char	The Logical Company bus Unibus/Qbus adapters
+		  0 = /dev/logicalco/bci/0	First bus adapter
+		  1 = /dev/logicalco/bci/1	First bus adapter
+		    ...
+
+ 219 char	The Logical Company DCI-1300 digital I/O card
+		  0 = /dev/logicalco/dci1300/0	First DCI-1300 card
+		  1 = /dev/logicalco/dci1300/1	Second DCI-1300 card
+		    ...
+
+ 220 char	Myricom Myrinet "GM" board
+		  0 = /dev/myricom/gm0		First Myrinet GM board
+		  1 = /dev/myricom/gmp0		First board "root access"
+		  2 = /dev/myricom/gm1		Second Myrinet GM board
+		  3 = /dev/myricom/gmp1		Second board "root access"
+		    ...
+
+ 221 char	VME bus
+		  0 = /dev/bus/vme/m0		First master image
+		  1 = /dev/bus/vme/m1		Second master image
+		  2 = /dev/bus/vme/m2		Third master image
+		  3 = /dev/bus/vme/m3		Fourth master image
+		  4 = /dev/bus/vme/s0		First slave image
+		  5 = /dev/bus/vme/s1		Second slave image
+		  6 = /dev/bus/vme/s2		Third slave image
+		  7 = /dev/bus/vme/s3		Fourth slave image
+		  8 = /dev/bus/vme/ctl		Control
+
+		It is expected that all VME bus drivers will use the
+		same interface.  For interface documentation see
+		http://www.vmelinux.org/.
+
+ 224 char	A2232 serial card
+		  0 = /dev/ttyY0		First A2232 port
+		  1 = /dev/ttyY1		Second A2232 port
+		    ...
+
+ 225 char	A2232 serial card (alternate devices)
+		  0 = /dev/cuy0			Callout device for ttyY0
+		  1 = /dev/cuy1			Callout device for ttyY1
+		    ...
+
+ 226 char	Direct Rendering Infrastructure (DRI)
+		  0 = /dev/dri/card0		First graphics card
+		  1 = /dev/dri/card1		Second graphics card
+		    ...
+
+ 227 char	IBM 3270 terminal Unix tty access
+		  1 = /dev/3270/tty1		First 3270 terminal
+		  2 = /dev/3270/tty2		Seconds 3270 terminal
+		    ...
+
+ 228 char	IBM 3270 terminal block-mode access
+		  0 = /dev/3270/tub		Controlling interface
+		  1 = /dev/3270/tub1		First 3270 terminal
+		  2 = /dev/3270/tub2		Second 3270 terminal
+		    ...
+
+ 229 char	IBM iSeries/pSeries virtual console
+		  0 = /dev/hvc0			First console port
+		  1 = /dev/hvc1			Second console port
+		    ...
+
+ 230 char	IBM iSeries virtual tape
+		  0 = /dev/iseries/vt0		First virtual tape, mode 0
+		  1 = /dev/iseries/vt1		Second virtual tape, mode 0
+		    ...
+		 32 = /dev/iseries/vt0l		First virtual tape, mode 1
+		 33 = /dev/iseries/vt1l		Second virtual tape, mode 1
+		    ...
+		 64 = /dev/iseries/vt0m		First virtual tape, mode 2
+		 65 = /dev/iseries/vt1m		Second virtual tape, mode 2
+		    ...
+		 96 = /dev/iseries/vt0a		First virtual tape, mode 3
+		 97 = /dev/iseries/vt1a		Second virtual tape, mode 3
+		      ...
+		128 = /dev/iseries/nvt0		First virtual tape, mode 0, no rewind
+		129 = /dev/iseries/nvt1		Second virtual tape, mode 0, no rewind
+		    ...
+		160 = /dev/iseries/nvt0l	First virtual tape, mode 1, no rewind
+		161 = /dev/iseries/nvt1l	Second virtual tape, mode 1, no rewind
+		    ...
+		192 = /dev/iseries/nvt0m	First virtual tape, mode 2, no rewind
+		193 = /dev/iseries/nvt1m	Second virtual tape, mode 2, no rewind
+		    ...
+		224 = /dev/iseries/nvt0a	First virtual tape, mode 3, no rewind
+		225 = /dev/iseries/nvt1a	Second virtual tape, mode 3, no rewind
+		    ...
+
+		"No rewind" refers to the omission of the default
+		automatic rewind on device close.  The MTREW or MTOFFL
+		ioctl()'s can be used to rewind the tape regardless of
+		the device used to access it.
+
+ 231 char	InfiniBand
+		0 = /dev/infiniband/umad0
+		1 = /dev/infiniband/umad1
+		  ...
+		63 = /dev/infiniband/umad63    63rd InfiniBandMad device
+		64 = /dev/infiniband/issm0     First InfiniBand IsSM device
+		65 = /dev/infiniband/issm1     Second InfiniBand IsSM device
+		  ...
+		127 = /dev/infiniband/issm63    63rd InfiniBand IsSM device
+		192 = /dev/infiniband/uverbs0   First InfiniBand verbs device
+		193 = /dev/infiniband/uverbs1   Second InfiniBand verbs device
+		  ...
+		223 = /dev/infiniband/uverbs31  31st InfiniBand verbs device
+
+ 232 char	Biometric Devices
+		0 = /dev/biometric/sensor0/fingerprint	first fingerprint sensor on first device
+		1 = /dev/biometric/sensor0/iris		first iris sensor on first device
+		2 = /dev/biometric/sensor0/retina	first retina sensor on first device
+		3 = /dev/biometric/sensor0/voiceprint	first voiceprint sensor on first device
+		4 = /dev/biometric/sensor0/facial	first facial sensor on first device
+		5 = /dev/biometric/sensor0/hand		first hand sensor on first device
+		  ...
+		10 = /dev/biometric/sensor1/fingerprint	first fingerprint sensor on second device
+		  ...
+		20 = /dev/biometric/sensor2/fingerprint	first fingerprint sensor on third device
+		  ...
+
+ 233 char	PathScale InfiniPath interconnect
+		0 = /dev/ipath        Primary device for programs (any unit)
+		1 = /dev/ipath0       Access specifically to unit 0
+		2 = /dev/ipath1       Access specifically to unit 1
+		  ...
+		4 = /dev/ipath3       Access specifically to unit 3
+		129 = /dev/ipath_sma    Device used by Subnet Management Agent
+		130 = /dev/ipath_diag   Device used by diagnostics programs
+
+ 234-254	char	RESERVED FOR DYNAMIC ASSIGNMENT
+		Character devices that request a dynamic allocation of major number will
+		take numbers starting from 254 and downward.
+
+ 240-254 block	LOCAL/EXPERIMENTAL USE
+		Allocated for local/experimental use.  For devices not
+		assigned official numbers, these ranges should be
+		used in order to avoid conflicting with future assignments.
+
+ 255 char	RESERVED
+
+ 255 block	RESERVED
+
+		This major is reserved to assist the expansion to a
+		larger number space.  No device nodes with this major
+		should ever be created on the filesystem.
+		(This is probably not true anymore, but I'll leave it
+		for now /Torben)
+
+ ---LARGE MAJORS!!!!!---
+
+ 256 char	Equinox SST multi-port serial boards
+		   0 = /dev/ttyEQ0	First serial port on first Equinox SST board
+		 127 = /dev/ttyEQ127	Last serial port on first Equinox SST board
+		 128 = /dev/ttyEQ128	First serial port on second Equinox SST board
+		  ...
+		1027 = /dev/ttyEQ1027	Last serial port on eighth Equinox SST board
+
+ 256 block	Resident Flash Disk Flash Translation Layer
+		  0 = /dev/rfda		First RFD FTL layer
+		 16 = /dev/rfdb		Second RFD FTL layer
+		  ...
+		240 = /dev/rfdp		16th RFD FTL layer
+
+ 257 char	Phoenix Technologies Cryptographic Services Driver
+		  0 = /dev/ptlsec	Crypto Services Driver
+
+ 257 block	SSFDC Flash Translation Layer filesystem
+		  0 = /dev/ssfdca	First SSFDC layer
+		  8 = /dev/ssfdcb	Second SSFDC layer
+		 16 = /dev/ssfdcc	Third SSFDC layer
+		 24 = /dev/ssfdcd	4th SSFDC layer
+		 32 = /dev/ssfdce	5th SSFDC layer
+		 40 = /dev/ssfdcf	6th SSFDC layer
+		 48 = /dev/ssfdcg	7th SSFDC layer
+		 56 = /dev/ssfdch	8th SSFDC layer
+
+ 258 block	ROM/Flash read-only translation layer
+		  0 = /dev/blockrom0	First ROM card's translation layer interface
+		  1 = /dev/blockrom1	Second ROM card's translation layer interface
+		  ...
+
+ 259 block	Block Extended Major
+		  Used dynamically to hold additional partition minor
+		  numbers and allow large numbers of partitions per device
+
+ 259 char	FPGA configuration interfaces
+		  0 = /dev/icap0	First Xilinx internal configuration
+		  1 = /dev/icap1	Second Xilinx internal configuration
+
+ 260 char	OSD (Object-based-device) SCSI Device
+		  0 = /dev/osd0		First OSD Device
+		  1 = /dev/osd1		Second OSD Device
+		  ...
+		  255 = /dev/osd255	256th OSD Device
+
+ 261 char	Compute Acceleration Devices
+		  0 = /dev/accel/accel0	First acceleration device
+		  1 = /dev/accel/accel1	Second acceleration device
+		    ...
+
+ 384-511 char	RESERVED FOR DYNAMIC ASSIGNMENT
+		Character devices that request a dynamic allocation of major
+		number will take numbers starting from 511 and downward,
+		once the 234-254 range is full.
diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
new file mode 100644
index 000000000..9c2f096ed
--- /dev/null
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -0,0 +1,392 @@
+Dynamic debug
++++++++++++++
+
+
+Introduction
+============
+
+Dynamic debug allows you to dynamically enable/disable kernel
+debug-print code to obtain additional kernel information.
+
+If ``/proc/dynamic_debug/control`` exists, your kernel has dynamic
+debug.  You'll need root access (sudo su) to use this.
+
+Dynamic debug provides:
+
+ * a Catalog of all *prdbgs* in your kernel.
+   ``cat /proc/dynamic_debug/control`` to see them.
+
+ * a Simple query/command language to alter *prdbgs* by selecting on
+   any combination of 0 or 1 of:
+
+   - source filename
+   - function name
+   - line number (including ranges of line numbers)
+   - module name
+   - format string
+   - class name (as known/declared by each module)
+
+NOTE: To actually get the debug-print output on the console, you may
+need to adjust the kernel ``loglevel=``, or use ``ignore_loglevel``.
+Read about these kernel parameters in
+Documentation/admin-guide/kernel-parameters.rst.
+
+Viewing Dynamic Debug Behaviour
+===============================
+
+You can view the currently configured behaviour in the *prdbg* catalog::
+
+  :#> head -n7 /proc/dynamic_debug/control
+  # filename:lineno [module]function flags format
+  init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\n"
+  init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\n"
+  init/main.c:1424 [main]run_init_process =_ "  with arguments:\n"
+  init/main.c:1426 [main]run_init_process =_ "    %s\n"
+  init/main.c:1427 [main]run_init_process =_ "  with environment:\n"
+  init/main.c:1429 [main]run_init_process =_ "    %s\n"
+
+The 3rd space-delimited column shows the current flags, preceded by
+a ``=`` for easy use with grep/cut. ``=p`` shows enabled callsites.
+
+Controlling dynamic debug Behaviour
+===================================
+
+The behaviour of *prdbg* sites are controlled by writing
+query/commands to the control file.  Example::
+
+  # grease the interface
+  :#> alias ddcmd='echo $* > /proc/dynamic_debug/control'
+
+  :#> ddcmd '-p; module main func run* +p'
+  :#> grep =p /proc/dynamic_debug/control
+  init/main.c:1424 [main]run_init_process =p "  with arguments:\n"
+  init/main.c:1426 [main]run_init_process =p "    %s\n"
+  init/main.c:1427 [main]run_init_process =p "  with environment:\n"
+  init/main.c:1429 [main]run_init_process =p "    %s\n"
+
+Error messages go to console/syslog::
+
+  :#> ddcmd mode foo +p
+  dyndbg: unknown keyword "mode"
+  dyndbg: query parse failed
+  bash: echo: write error: Invalid argument
+
+If debugfs is also enabled and mounted, ``dynamic_debug/control`` is
+also under the mount-dir, typically ``/sys/kernel/debug/``.
+
+Command Language Reference
+==========================
+
+At the basic lexical level, a command is a sequence of words separated
+by spaces or tabs.  So these are all equivalent::
+
+  :#> ddcmd file svcsock.c line 1603 +p
+  :#> ddcmd "file svcsock.c line 1603 +p"
+  :#> ddcmd '  file   svcsock.c     line  1603 +p  '
+
+Command submissions are bounded by a write() system call.
+Multiple commands can be written together, separated by ``;`` or ``\n``::
+
+  :#> ddcmd "func pnpacpi_get_resources +p; func pnp_assign_mem +p"
+  :#> ddcmd <<"EOC"
+  func pnpacpi_get_resources +p
+  func pnp_assign_mem +p
+  EOC
+  :#> cat query-batch-file > /proc/dynamic_debug/control
+
+You can also use wildcards in each query term. The match rule supports
+``*`` (matches zero or more characters) and ``?`` (matches exactly one
+character). For example, you can match all usb drivers::
+
+  :#> ddcmd file "drivers/usb/*" +p	# "" to suppress shell expansion
+
+Syntactically, a command is pairs of keyword values, followed by a
+flags change or setting::
+
+  command ::= match-spec* flags-spec
+
+The match-spec's select *prdbgs* from the catalog, upon which to apply
+the flags-spec, all constraints are ANDed together.  An absent keyword
+is the same as keyword "*".
+
+Note that since the match-spec can be empty, the flags are checked 1st,
+then the pairs of keyword and value.  Flag errs will hide keyword errs::
+
+  bash-5.2# ddcmd mod bar +foo
+  dyndbg: read 13 bytes from userspace
+  dyndbg: query 0: "mod bar +foo" mod:*
+  dyndbg: unknown flag 'o'
+  dyndbg: flags parse failed
+  dyndbg: processed 1 queries, with 0 matches, 1 errs
+
+So a match-spec is a keyword, which selects the attribute of the
+callsite to be compared, and a value to compare against.  Possible
+keywords are::
+
+  match-spec ::= 'func' string |
+		 'file' string |
+		 'module' string |
+		 'format' string |
+		 'class' string |
+		 'line' line-range
+
+  line-range ::= lineno |
+		 '-'lineno |
+		 lineno'-' |
+		 lineno'-'lineno
+
+  lineno ::= unsigned-int
+
+.. note::
+
+  ``line-range`` cannot contain space, e.g.
+  "1-30" is valid range but "1 - 30" is not.
+
+
+The meanings of each keyword are:
+
+func
+    The given string is compared against the function name
+    of each callsite.  Example::
+
+	func svc_tcp_accept
+	func *recv*		# in rfcomm, bluetooth, ping, tcp
+
+file
+    The given string is compared against either the src-root relative
+    pathname, or the basename of the source file of each callsite.
+    Examples::
+
+	file svcsock.c
+	file kernel/freezer.c	# ie column 1 of control file
+	file drivers/usb/*	# all callsites under it
+	file inode.c:start_*	# parse :tail as a func (above)
+	file inode.c:1-100	# parse :tail as a line-range (above)
+
+module
+    The given string is compared against the module name
+    of each callsite.  The module name is the string as
+    seen in ``lsmod``, i.e. without the directory or the ``.ko``
+    suffix and with ``-`` changed to ``_``.  Examples::
+
+	module sunrpc
+	module nfsd
+	module drm*	# both drm, drm_kms_helper
+
+format
+    The given string is searched for in the dynamic debug format
+    string.  Note that the string does not need to match the
+    entire format, only some part.  Whitespace and other
+    special characters can be escaped using C octal character
+    escape ``\ooo`` notation, e.g. the space character is ``\040``.
+    Alternatively, the string can be enclosed in double quote
+    characters (``"``) or single quote characters (``'``).
+    Examples::
+
+	format svcrdma:         // many of the NFS/RDMA server pr_debugs
+	format readahead        // some pr_debugs in the readahead cache
+	format nfsd:\040SETATTR // one way to match a format with whitespace
+	format "nfsd: SETATTR"  // a neater way to match a format with whitespace
+	format 'nfsd: SETATTR'  // yet another way to match a format with whitespace
+
+class
+    The given class_name is validated against each module, which may
+    have declared a list of known class_names.  If the class_name is
+    found for a module, callsite & class matching and adjustment
+    proceeds.  Examples::
+
+	class DRM_UT_KMS	# a DRM.debug category
+	class JUNK		# silent non-match
+	// class TLD_*		# NOTICE: no wildcard in class names
+
+line
+    The given line number or range of line numbers is compared
+    against the line number of each ``pr_debug()`` callsite.  A single
+    line number matches the callsite line number exactly.  A
+    range of line numbers matches any callsite between the first
+    and last line number inclusive.  An empty first number means
+    the first line in the file, an empty last line number means the
+    last line number in the file.  Examples::
+
+	line 1603           // exactly line 1603
+	line 1600-1605      // the six lines from line 1600 to line 1605
+	line -1605          // the 1605 lines from line 1 to line 1605
+	line 1600-          // all lines from line 1600 to the end of the file
+
+The flags specification comprises a change operation followed
+by one or more flag characters.  The change operation is one
+of the characters::
+
+  -    remove the given flags
+  +    add the given flags
+  =    set the flags to the given flags
+
+The flags are::
+
+  p    enables the pr_debug() callsite.
+  _    enables no flags.
+
+  Decorator flags add to the message-prefix, in order:
+  t    Include thread ID, or <intr>
+  m    Include module name
+  f    Include the function name
+  s    Include the source file name
+  l    Include line number
+  d    Include call trace
+
+For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
+the ``p`` flag has meaning, other flags are ignored.
+
+Note the regexp ``^[-+=][fslmptd_]+$`` matches a flags specification.
+To clear all flags at once, use ``=_`` or ``-fslmptd``.
+
+
+Debug messages during Boot Process
+==================================
+
+To activate debug messages for core code and built-in modules during
+the boot process, even before userspace and debugfs exists, use
+``dyndbg="QUERY"`` or ``module.dyndbg="QUERY"``.  QUERY follows
+the syntax described above, but must not exceed 1023 characters.  Your
+bootloader may impose lower limits.
+
+These ``dyndbg`` params are processed just after the ddebug tables are
+processed, as part of the early_initcall.  Thus you can enable debug
+messages in all code run after this early_initcall via this boot
+parameter.
+
+On an x86 system for example ACPI enablement is a subsys_initcall and::
+
+   dyndbg="file ec.c +p"
+
+will show early Embedded Controller transactions during ACPI setup if
+your machine (typically a laptop) has an Embedded Controller.
+PCI (or other devices) initialization also is a hot candidate for using
+this boot parameter for debugging purposes.
+
+If ``foo`` module is not built-in, ``foo.dyndbg`` will still be processed at
+boot time, without effect, but will be reprocessed when module is
+loaded later. Bare ``dyndbg=`` is only processed at boot.
+
+
+Debug Messages at Module Initialization Time
+============================================
+
+When ``modprobe foo`` is called, modprobe scans ``/proc/cmdline`` for
+``foo.params``, strips ``foo.``, and passes them to the kernel along with
+params given in modprobe args or ``/etc/modprobe.d/*.conf`` files,
+in the following order:
+
+1. parameters given via ``/etc/modprobe.d/*.conf``::
+
+	options foo dyndbg=+pt
+	options foo dyndbg # defaults to +p
+
+2. ``foo.dyndbg`` as given in boot args, ``foo.`` is stripped and passed::
+
+	foo.dyndbg=" func bar +p; func buz +mp"
+
+3. args to modprobe::
+
+	modprobe foo dyndbg==pmf # override previous settings
+
+These ``dyndbg`` queries are applied in order, with last having final say.
+This allows boot args to override or modify those from ``/etc/modprobe.d``
+(sensible, since 1 is system wide, 2 is kernel or boot specific), and
+modprobe args to override both.
+
+In the ``foo.dyndbg="QUERY"`` form, the query must exclude ``module foo``.
+``foo`` is extracted from the param-name, and applied to each query in
+``QUERY``, and only 1 match-spec of each type is allowed.
+
+The ``dyndbg`` option is a "fake" module parameter, which means:
+
+- modules do not need to define it explicitly
+- every module gets it tacitly, whether they use pr_debug or not
+- it doesn't appear in ``/sys/module/$module/parameters/``
+  To see it, grep the control file, or inspect ``/proc/cmdline.``
+
+For ``CONFIG_DYNAMIC_DEBUG`` kernels, any settings given at boot-time (or
+enabled by ``-DDEBUG`` flag during compilation) can be disabled later via
+the debugfs interface if the debug messages are no longer needed::
+
+   echo "module module_name -p" > /proc/dynamic_debug/control
+
+Examples
+========
+
+::
+
+  // enable the message at line 1603 of file svcsock.c
+  :#> ddcmd 'file svcsock.c line 1603 +p'
+
+  // enable all the messages in file svcsock.c
+  :#> ddcmd 'file svcsock.c +p'
+
+  // enable all the messages in the NFS server module
+  :#> ddcmd 'module nfsd +p'
+
+  // enable all 12 messages in the function svc_process()
+  :#> ddcmd 'func svc_process +p'
+
+  // disable all 12 messages in the function svc_process()
+  :#> ddcmd 'func svc_process -p'
+
+  // enable messages for NFS calls READ, READLINK, READDIR and READDIR+.
+  :#> ddcmd 'format "nfsd: READ" +p'
+
+  // enable messages in files of which the paths include string "usb"
+  :#> ddcmd 'file *usb* +p'
+
+  // enable all messages
+  :#> ddcmd '+p'
+
+  // add module, function to all enabled messages
+  :#> ddcmd '+mf'
+
+  // boot-args example, with newlines and comments for readability
+  Kernel command line: ...
+    // see what's going on in dyndbg=value processing
+    dynamic_debug.verbose=3
+    // enable pr_debugs in the btrfs module (can be builtin or loadable)
+    btrfs.dyndbg="+p"
+    // enable pr_debugs in all files under init/
+    // and the function parse_one, #cmt is stripped
+    dyndbg="file init/* +p #cmt ; func parse_one +p"
+    // enable pr_debugs in 2 functions in a module loaded later
+    pc87360.dyndbg="func pc87360_init_device +p; func pc87360_find +p"
+
+Kernel Configuration
+====================
+
+Dynamic Debug is enabled via kernel config items::
+
+  CONFIG_DYNAMIC_DEBUG=y	# build catalog, enables CORE
+  CONFIG_DYNAMIC_DEBUG_CORE=y	# enable mechanics only, skip catalog
+
+If you do not want to enable dynamic debug globally (i.e. in some embedded
+system), you may set ``CONFIG_DYNAMIC_DEBUG_CORE`` as basic support of dynamic
+debug and add ``ccflags := -DDYNAMIC_DEBUG_MODULE`` into the Makefile of any
+modules which you'd like to dynamically debug later.
+
+
+Kernel *prdbg* API
+==================
+
+The following functions are cataloged and controllable when dynamic
+debug is enabled::
+
+  pr_debug()
+  dev_dbg()
+  print_hex_dump_debug()
+  print_hex_dump_bytes()
+
+Otherwise, they are off by default; ``ccflags += -DDEBUG`` or
+``#define DEBUG`` in a source file will enable them appropriately.
+
+If ``CONFIG_DYNAMIC_DEBUG`` is not set, ``print_hex_dump_debug()`` is
+just a shortcut for ``print_hex_dump(KERN_DEBUG)``.
+
+For ``print_hex_dump_debug()``/``print_hex_dump_bytes()``, format string is
+its ``prefix_str`` argument, if it is constant string; or ``hexdump``
+in case ``prefix_str`` is built dynamically.
diff --git a/Documentation/admin-guide/edid.rst b/Documentation/admin-guide/edid.rst
new file mode 100644
index 000000000..1a9b965aa
--- /dev/null
+++ b/Documentation/admin-guide/edid.rst
@@ -0,0 +1,27 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+EDID
+====
+
+In the good old days when graphics parameters were configured explicitly
+in a file called xorg.conf, even broken hardware could be managed.
+
+Today, with the advent of Kernel Mode Setting, a graphics board is
+either correctly working because all components follow the standards -
+or the computer is unusable, because the screen remains dark after
+booting or it displays the wrong area. Cases when this happens are:
+
+- The graphics board does not recognize the monitor.
+- The graphics board is unable to detect any EDID data.
+- The graphics board incorrectly forwards EDID data to the driver.
+- The monitor sends no or bogus EDID data.
+- A KVM sends its own EDID data instead of querying the connected monitor.
+
+Adding the kernel parameter "nomodeset" helps in most cases, but causes
+restrictions later on.
+
+As a remedy for such situations, the kernel configuration item
+CONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an
+individually prepared or corrected EDID data set in the /lib/firmware
+directory from where it is loaded via the firmware interface.
diff --git a/Documentation/admin-guide/efi-stub.rst b/Documentation/admin-guide/efi-stub.rst
new file mode 100644
index 000000000..f8e740769
--- /dev/null
+++ b/Documentation/admin-guide/efi-stub.rst
@@ -0,0 +1,103 @@
+=================
+The EFI Boot Stub
+=================
+
+On the x86 and ARM platforms, a kernel zImage/bzImage can masquerade
+as a PE/COFF image, thereby convincing EFI firmware loaders to load
+it as an EFI executable. The code that modifies the bzImage header,
+along with the EFI-specific entry point that the firmware loader
+jumps to are collectively known as the "EFI boot stub", and live in
+arch/x86/boot/header.S and drivers/firmware/efi/libstub/x86-stub.c,
+respectively. For ARM the EFI stub is implemented in
+arch/arm/boot/compressed/efi-header.S and
+drivers/firmware/efi/libstub/arm32-stub.c. EFI stub code that is shared
+between architectures is in drivers/firmware/efi/libstub.
+
+For arm64, there is no compressed kernel support, so the Image itself
+masquerades as a PE/COFF image and the EFI stub is linked into the
+kernel. The arm64 EFI stub lives in drivers/firmware/efi/libstub/arm64.c
+and drivers/firmware/efi/libstub/arm64-stub.c.
+
+By using the EFI boot stub it's possible to boot a Linux kernel
+without the use of a conventional EFI boot loader, such as grub or
+elilo. Since the EFI boot stub performs the jobs of a boot loader, in
+a certain sense it *IS* the boot loader.
+
+The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.
+
+
+How to install bzImage.efi
+--------------------------
+
+The bzImage located in arch/x86/boot/bzImage must be copied to the EFI
+System Partition (ESP) and renamed with the extension ".efi". Without
+the extension the EFI firmware loader will refuse to execute it. It's
+not possible to execute bzImage.efi from the usual Linux file systems
+because EFI firmware doesn't have support for them. For ARM the
+arch/arm/boot/zImage should be copied to the system partition, and it
+may not need to be renamed. Similarly for arm64, arch/arm64/boot/Image
+should be copied but not necessarily renamed.
+
+
+Passing kernel parameters from the EFI shell
+--------------------------------------------
+
+Arguments to the kernel can be passed after bzImage.efi, e.g.::
+
+	fs0:> bzImage.efi console=ttyS0 root=/dev/sda4
+
+
+The "initrd=" option
+--------------------
+
+Like most boot loaders, the EFI stub allows the user to specify
+multiple initrd files using the "initrd=" option. This is the only EFI
+stub-specific command line parameter, everything else is passed to the
+kernel when it boots.
+
+The path to the initrd file must be an absolute path from the
+beginning of the ESP, relative path names do not work. Also, the path
+is an EFI-style path and directory elements must be separated with
+backslashes (\). For example, given the following directory layout::
+
+  fs0:>
+	Kernels\
+			bzImage.efi
+			initrd-large.img
+
+	Ramdisks\
+			initrd-small.img
+			initrd-medium.img
+
+to boot with the initrd-large.img file if the current working
+directory is fs0:\Kernels, the following command must be used::
+
+	fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img
+
+Notice how bzImage.efi can be specified with a relative path. That's
+because the image we're executing is interpreted by the EFI shell,
+which understands relative paths, whereas the rest of the command line
+is passed to bzImage.efi.
+
+.. hint::
+   It is also possible to provide an initrd using a Linux-specific UEFI
+   protocol at boot time. See :ref:`pe-coff-entry-point` for details.
+
+The "dtb=" option
+-----------------
+
+For the ARM and arm64 architectures, a device tree must be provided to
+the kernel. Normally firmware shall supply the device tree via the
+EFI CONFIGURATION TABLE. However, the "dtb=" command line option can
+be used to override the firmware supplied device tree, or to supply
+one when firmware is unable to.
+
+Please note: Firmware adds runtime configuration information to the
+device tree before booting the kernel. If dtb= is used to override
+the device tree, then any runtime data provided by firmware will be
+lost. The dtb= option should only be used either as a debug tool, or
+as a last resort when a device tree is not provided in the EFI
+CONFIGURATION TABLE.
+
+"dtb=" is processed in the same manner as the "initrd=" option that is
+described above.
diff --git a/Documentation/admin-guide/ext4.rst b/Documentation/admin-guide/ext4.rst
new file mode 100644
index 000000000..742a48e6f
--- /dev/null
+++ b/Documentation/admin-guide/ext4.rst
@@ -0,0 +1,611 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+ext4 General Information
+========================
+
+Ext4 is an advanced level of the ext3 filesystem which incorporates
+scalability and reliability enhancements for supporting large filesystems
+(64 bit) in keeping with increasing disk capacities and state-of-the-art
+feature requirements.
+
+Mailing list:	linux-ext4@vger.kernel.org
+Web site:	http://ext4.wiki.kernel.org
+
+
+Quick usage instructions
+========================
+
+Note: More extensive information for getting started with ext4 can be
+found at the ext4 wiki site at the URL:
+http://ext4.wiki.kernel.org/index.php/Ext4_Howto
+
+  - The latest version of e2fsprogs can be found at:
+
+    https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/
+
+	or
+
+    http://sourceforge.net/project/showfiles.php?group_id=2406
+
+	or grab the latest git repository from:
+
+   https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git
+
+  - Create a new filesystem using the ext4 filesystem type:
+
+        # mke2fs -t ext4 /dev/hda1
+
+    Or to configure an existing ext3 filesystem to support extents:
+
+	# tune2fs -O extents /dev/hda1
+
+    If the filesystem was created with 128 byte inodes, it can be
+    converted to use 256 byte for greater efficiency via:
+
+        # tune2fs -I 256 /dev/hda1
+
+  - Mounting:
+
+	# mount -t ext4 /dev/hda1 /wherever
+
+  - When comparing performance with other filesystems, it's always
+    important to try multiple workloads; very often a subtle change in a
+    workload parameter can completely change the ranking of which
+    filesystems do well compared to others.  When comparing versus ext3,
+    note that ext4 enables write barriers by default, while ext3 does
+    not enable write barriers by default.  So it is useful to use
+    explicitly specify whether barriers are enabled or not when via the
+    '-o barriers=[0|1]' mount option for both ext3 and ext4 filesystems
+    for a fair comparison.  When tuning ext3 for best benchmark numbers,
+    it is often worthwhile to try changing the data journaling mode; '-o
+    data=writeback' can be faster for some workloads.  (Note however that
+    running mounted with data=writeback can potentially leave stale data
+    exposed in recently written files in case of an unclean shutdown,
+    which could be a security exposure in some situations.)  Configuring
+    the filesystem with a large journal can also be helpful for
+    metadata-intensive workloads.
+
+Features
+========
+
+Currently Available
+-------------------
+
+* ability to use filesystems > 16TB (e2fsprogs support not available yet)
+* extent format reduces metadata overhead (RAM, IO for access, transactions)
+* extent format more robust in face of on-disk corruption due to magics,
+* internal redundancy in tree
+* improved file allocation (multi-block alloc)
+* lift 32000 subdirectory limit imposed by i_links_count[1]
+* nsec timestamps for mtime, atime, ctime, create time
+* inode version field on disk (NFSv4, Lustre)
+* reduced e2fsck time via uninit_bg feature
+* journal checksumming for robustness, performance
+* persistent file preallocation (e.g for streaming media, databases)
+* ability to pack bitmaps and inode tables into larger virtual groups via the
+  flex_bg feature
+* large file support
+* inode allocation using large virtual block groups via flex_bg
+* delayed allocation
+* large block (up to pagesize) support
+* efficient new ordered mode in JBD2 and ext4 (avoid using buffer head to force
+  the ordering)
+* Case-insensitive file name lookups
+* file-based encryption support (fscrypt)
+* file-based verity support (fsverity)
+
+[1] Filesystems with a block size of 1k may see a limit imposed by the
+directory hash tree having a maximum depth of two.
+
+case-insensitive file name lookups
+======================================================
+
+The case-insensitive file name lookup feature is supported on a
+per-directory basis, allowing the user to mix case-insensitive and
+case-sensitive directories in the same filesystem.  It is enabled by
+flipping the +F inode attribute of an empty directory.  The
+case-insensitive string match operation is only defined when we know how
+text in encoded in a byte sequence.  For that reason, in order to enable
+case-insensitive directories, the filesystem must have the
+casefold feature, which stores the filesystem-wide encoding
+model used.  By default, the charset adopted is the latest version of
+Unicode (12.1.0, by the time of this writing), encoded in the UTF-8
+form.  The comparison algorithm is implemented by normalizing the
+strings to the Canonical decomposition form, as defined by Unicode,
+followed by a byte per byte comparison.
+
+The case-awareness is name-preserving on the disk, meaning that the file
+name provided by userspace is a byte-per-byte match to what is actually
+written in the disk.  The Unicode normalization format used by the
+kernel is thus an internal representation, and not exposed to the
+userspace nor to the disk, with the important exception of disk hashes,
+used on large case-insensitive directories with DX feature.  On DX
+directories, the hash must be calculated using the casefolded version of
+the filename, meaning that the normalization format used actually has an
+impact on where the directory entry is stored.
+
+When we change from viewing filenames as opaque byte sequences to seeing
+them as encoded strings we need to address what happens when a program
+tries to create a file with an invalid name.  The Unicode subsystem
+within the kernel leaves the decision of what to do in this case to the
+filesystem, which select its preferred behavior by enabling/disabling
+the strict mode.  When Ext4 encounters one of those strings and the
+filesystem did not require strict mode, it falls back to considering the
+entire string as an opaque byte sequence, which still allows the user to
+operate on that file, but the case-insensitive lookups won't work.
+
+Options
+=======
+
+When mounting an ext4 filesystem, the following option are accepted:
+(*) == default
+
+  ro
+        Mount filesystem read only. Note that ext4 will replay the journal (and
+        thus write to the partition) even when mounted "read only". The mount
+        options "ro,noload" can be used to prevent writes to the filesystem.
+
+  journal_checksum
+        Enable checksumming of the journal transactions.  This will allow the
+        recovery code in e2fsck and the kernel to detect corruption in the
+        kernel.  It is a compatible change and will be ignored by older
+        kernels.
+
+  journal_async_commit
+        Commit block can be written to disk without waiting for descriptor
+        blocks. If enabled older kernels cannot mount the device. This will
+        enable 'journal_checksum' internally.
+
+  journal_path=path, journal_dev=devnum
+        When the external journal device's major/minor numbers have changed,
+        these options allow the user to specify the new journal location.  The
+        journal device is identified through either its new major/minor numbers
+        encoded in devnum, or via a path to the device.
+
+  norecovery, noload
+        Don't load the journal on mounting.  Note that if the filesystem was
+        not unmounted cleanly, skipping the journal replay will lead to the
+        filesystem containing inconsistencies that can lead to any number of
+        problems.
+
+  data=journal
+        All data are committed into the journal prior to being written into the
+        main file system.  Enabling this mode will disable delayed allocation
+        and O_DIRECT support.
+
+  data=ordered	(*)
+        All data are forced directly out to the main file system prior to its
+        metadata being committed to the journal.
+
+  data=writeback
+        Data ordering is not preserved, data may be written into the main file
+        system after its metadata has been committed to the journal.
+
+  commit=nrsec	(*)
+        This setting limits the maximum age of the running transaction to
+        'nrsec' seconds.  The default value is 5 seconds.  This means that if
+        you lose your power, you will lose as much as the latest 5 seconds of
+        metadata changes (your filesystem will not be damaged though, thanks
+        to the journaling). This default value (or any low value) will hurt
+        performance, but it's good for data-safety.  Setting it to 0 will have
+        the same effect as leaving it at the default (5 seconds).  Setting it
+        to very large values will improve performance.  Note that due to
+        delayed allocation even older data can be lost on power failure since
+        writeback of those data begins only after time set in
+        /proc/sys/vm/dirty_expire_centisecs.
+
+  barrier=<0|1(*)>, barrier(*), nobarrier
+        This enables/disables the use of write barriers in the jbd code.
+        barrier=0 disables, barrier=1 enables.  This also requires an IO stack
+        which can support barriers, and if jbd gets an error on a barrier
+        write, it will disable again with a warning.  Write barriers enforce
+        proper on-disk ordering of journal commits, making volatile disk write
+        caches safe to use, at some performance penalty.  If your disks are
+        battery-backed in one way or another, disabling barriers may safely
+        improve performance.  The mount options "barrier" and "nobarrier" can
+        also be used to enable or disable barriers, for consistency with other
+        ext4 mount options.
+
+  inode_readahead_blks=n
+        This tuning parameter controls the maximum number of inode table blocks
+        that ext4's inode table readahead algorithm will pre-read into the
+        buffer cache.  The default value is 32 blocks.
+
+  bsddf	(*)
+        Make 'df' act like BSD.
+
+  minixdf
+        Make 'df' act like Minix.
+
+  debug
+        Extra debugging information is sent to syslog.
+
+  abort
+        Simulate the effects of calling ext4_abort() for debugging purposes.
+        This is normally used while remounting a filesystem which is already
+        mounted.
+
+  errors=remount-ro
+        Remount the filesystem read-only on an error.
+
+  errors=continue
+        Keep going on a filesystem error.
+
+  errors=panic
+        Panic and halt the machine if an error occurs.  (These mount options
+        override the errors behavior specified in the superblock, which can be
+        configured using tune2fs)
+
+  data_err=ignore(*)
+        Just print an error message if an error occurs in a file data buffer.
+
+  data_err=abort
+        Abort the journal if an error occurs in a file data buffer.
+
+  grpid | bsdgroups
+        New objects have the group ID of their parent.
+
+  nogrpid (*) | sysvgroups
+        New objects have the group ID of their creator.
+
+  resgid=n
+        The group ID which may use the reserved blocks.
+
+  resuid=n
+        The user ID which may use the reserved blocks.
+
+  sb=
+        Use alternate superblock at this location.
+
+  quota, noquota, grpquota, usrquota
+        These options are ignored by the filesystem. They are used only by
+        quota tools to recognize volumes where quota should be turned on. See
+        documentation in the quota-tools package for more details
+        (http://sourceforge.net/projects/linuxquota).
+
+  jqfmt=<quota type>, usrjquota=<file>, grpjquota=<file>
+        These options tell filesystem details about quota so that quota
+        information can be properly updated during journal replay. They replace
+        the above quota options. See documentation in the quota-tools package
+        for more details (http://sourceforge.net/projects/linuxquota).
+
+  stripe=n
+        Number of filesystem blocks that mballoc will try to use for allocation
+        size and alignment. For RAID5/6 systems this should be the number of
+        data disks *  RAID chunk size in file system blocks.
+
+  delalloc	(*)
+        Defer block allocation until just before ext4 writes out the block(s)
+        in question.  This allows ext4 to better allocation decisions more
+        efficiently.
+
+  nodelalloc
+        Disable delayed allocation.  Blocks are allocated when the data is
+        copied from userspace to the page cache, either via the write(2) system
+        call or when an mmap'ed page which was previously unallocated is
+        written for the first time.
+
+  max_batch_time=usec
+        Maximum amount of time ext4 should wait for additional filesystem
+        operations to be batch together with a synchronous write operation.
+        Since a synchronous write operation is going to force a commit and then
+        a wait for the I/O complete, it doesn't cost much, and can be a huge
+        throughput win, we wait for a small amount of time to see if any other
+        transactions can piggyback on the synchronous write.   The algorithm
+        used is designed to automatically tune for the speed of the disk, by
+        measuring the amount of time (on average) that it takes to finish
+        committing a transaction.  Call this time the "commit time".  If the
+        time that the transaction has been running is less than the commit
+        time, ext4 will try sleeping for the commit time to see if other
+        operations will join the transaction.   The commit time is capped by
+        the max_batch_time, which defaults to 15000us (15ms).   This
+        optimization can be turned off entirely by setting max_batch_time to 0.
+
+  min_batch_time=usec
+        This parameter sets the commit time (as described above) to be at least
+        min_batch_time.  It defaults to zero microseconds.  Increasing this
+        parameter may improve the throughput of multi-threaded, synchronous
+        workloads on very fast disks, at the cost of increasing latency.
+
+  journal_ioprio=prio
+        The I/O priority (from 0 to 7, where 0 is the highest priority) which
+        should be used for I/O operations submitted by kjournald2 during a
+        commit operation.  This defaults to 3, which is a slightly higher
+        priority than the default I/O priority.
+
+  auto_da_alloc(*), noauto_da_alloc
+        Many broken applications don't use fsync() when replacing existing
+        files via patterns such as fd = open("foo.new")/write(fd,..)/close(fd)/
+        rename("foo.new", "foo"), or worse yet, fd = open("foo",
+        O_TRUNC)/write(fd,..)/close(fd).  If auto_da_alloc is enabled, ext4
+        will detect the replace-via-rename and replace-via-truncate patterns
+        and force that any delayed allocation blocks are allocated such that at
+        the next journal commit, in the default data=ordered mode, the data
+        blocks of the new file are forced to disk before the rename() operation
+        is committed.  This provides roughly the same level of guarantees as
+        ext3, and avoids the "zero-length" problem that can happen when a
+        system crashes before the delayed allocation blocks are forced to disk.
+
+  noinit_itable
+        Do not initialize any uninitialized inode table blocks in the
+        background.  This feature may be used by installation CD's so that the
+        install process can complete as quickly as possible; the inode table
+        initialization process would then be deferred until the next time the
+        file system is unmounted.
+
+  init_itable=n
+        The lazy itable init code will wait n times the number of milliseconds
+        it took to zero out the previous block group's inode table.  This
+        minimizes the impact on the system performance while file system's
+        inode table is being initialized.
+
+  discard, nodiscard(*)
+        Controls whether ext4 should issue discard/TRIM commands to the
+        underlying block device when blocks are freed.  This is useful for SSD
+        devices and sparse/thinly-provisioned LUNs, but it is off by default
+        until sufficient testing has been done.
+
+  nouid32
+        Disables 32-bit UIDs and GIDs.  This is for interoperability  with
+        older kernels which only store and expect 16-bit values.
+
+  block_validity(*), noblock_validity
+        These options enable or disable the in-kernel facility for tracking
+        filesystem metadata blocks within internal data structures.  This
+        allows multi- block allocator and other routines to notice bugs or
+        corrupted allocation bitmaps which cause blocks to be allocated which
+        overlap with filesystem metadata blocks.
+
+  dioread_lock, dioread_nolock
+        Controls whether or not ext4 should use the DIO read locking. If the
+        dioread_nolock option is specified ext4 will allocate uninitialized
+        extent before buffer write and convert the extent to initialized after
+        IO completes. This approach allows ext4 code to avoid using inode
+        mutex, which improves scalability on high speed storages. However this
+        does not work with data journaling and dioread_nolock option will be
+        ignored with kernel warning. Note that dioread_nolock code path is only
+        used for extent-based files.  Because of the restrictions this options
+        comprises it is off by default (e.g. dioread_lock).
+
+  max_dir_size_kb=n
+        This limits the size of directories so that any attempt to expand them
+        beyond the specified limit in kilobytes will cause an ENOSPC error.
+        This is useful in memory constrained environments, where a very large
+        directory can cause severe performance problems or even provoke the Out
+        Of Memory killer.  (For example, if there is only 512mb memory
+        available, a 176mb directory may seriously cramp the system's style.)
+
+  i_version
+        Enable 64-bit inode version support. This option is off by default.
+
+  dax
+        Use direct access (no page cache).  See
+        Documentation/filesystems/dax.rst.  Note that this option is
+        incompatible with data=journal.
+
+  inlinecrypt
+        When possible, encrypt/decrypt the contents of encrypted files using
+        inline encryption hardware rather than the CPU. For more details, see
+        Documentation/filesystems/fscrypt.rst.
+
+Data Mode
+=========
+There are 3 different data modes:
+
+* writeback mode
+
+  In data=writeback mode, ext4 does not journal data at all.  This mode provides
+  a similar level of journaling as that of XFS and JFS in its default
+  mode - metadata journaling.  A crash+recovery can cause incorrect data to
+  appear in files which were written shortly before the crash.  This mode will
+  typically provide the best ext4 performance.
+
+* ordered mode
+
+  In data=ordered mode, ext4 only officially journals metadata, but it logically
+  groups metadata information related to data changes with the data blocks into
+  a single unit called a transaction.  When it's time to write the new metadata
+  out to disk, the associated data blocks are written first.  In general, this
+  mode performs slightly slower than writeback but significantly faster than
+  journal mode.
+
+* journal mode
+
+  data=journal mode provides full data and metadata journaling.  All new data is
+  written to the journal first, and then to its final location.  In the event of
+  a crash, the journal can be replayed, bringing both data and metadata into a
+  consistent state.  This mode is the slowest except when data needs to be read
+  from and written to disk at the same time where it outperforms all others
+  modes.  Enabling this mode will disable delayed allocation and O_DIRECT
+  support.
+
+/proc entries
+=============
+
+Information about mounted ext4 file systems can be found in
+/proc/fs/ext4.  Each mounted filesystem will have a directory in
+/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
+/proc/fs/ext4/dm-0).   The files in each per-device directory are shown
+in table below.
+
+Files in /proc/fs/ext4/<devname>
+
+  mb_groups
+        details of multiblock allocator buddy cache of free blocks
+
+/sys entries
+============
+
+Information about mounted ext4 file systems can be found in
+/sys/fs/ext4.  Each mounted filesystem will have a directory in
+/sys/fs/ext4 based on its device name (i.e., /sys/fs/ext4/hdc or
+/sys/fs/ext4/dm-0).   The files in each per-device directory are shown
+in table below.
+
+Files in /sys/fs/ext4/<devname>:
+
+(see also Documentation/ABI/testing/sysfs-fs-ext4)
+
+  delayed_allocation_blocks
+        This file is read-only and shows the number of blocks that are dirty in
+        the page cache, but which do not have their location in the filesystem
+        allocated yet.
+
+  inode_goal
+        Tuning parameter which (if non-zero) controls the goal inode used by
+        the inode allocator in preference to all other allocation heuristics.
+        This is intended for debugging use only, and should be 0 on production
+        systems.
+
+  inode_readahead_blks
+        Tuning parameter which controls the maximum number of inode table
+        blocks that ext4's inode table readahead algorithm will pre-read into
+        the buffer cache.
+
+  lifetime_write_kbytes
+        This file is read-only and shows the number of kilobytes of data that
+        have been written to this filesystem since it was created.
+
+  max_writeback_mb_bump
+        The maximum number of megabytes the writeback code will try to write
+        out before move on to another inode.
+
+  mb_group_prealloc
+        The multiblock allocator will round up allocation requests to a
+        multiple of this tuning parameter if the stripe size is not set in the
+        ext4 superblock
+
+  mb_max_to_scan
+        The maximum number of extents the multiblock allocator will search to
+        find the best extent.
+
+  mb_min_to_scan
+        The minimum number of extents the multiblock allocator will search to
+        find the best extent.
+
+  mb_order2_req
+        Tuning parameter which controls the minimum size for requests (as a
+        power of 2) where the buddy cache is used.
+
+  mb_stats
+        Controls whether the multiblock allocator should collect statistics,
+        which are shown during the unmount. 1 means to collect statistics, 0
+        means not to collect statistics.
+
+  mb_stream_req
+        Files which have fewer blocks than this tunable parameter will have
+        their blocks allocated out of a block group specific preallocation
+        pool, so that small files are packed closely together.  Each large file
+        will have its blocks allocated out of its own unique preallocation
+        pool.
+
+  session_write_kbytes
+        This file is read-only and shows the number of kilobytes of data that
+        have been written to this filesystem since it was mounted.
+
+  reserved_clusters
+        This is RW file and contains number of reserved clusters in the file
+        system which will be used in the specific situations to avoid costly
+        zeroout, unexpected ENOSPC, or possible data loss. The default is 2% or
+        4096 clusters, whichever is smaller and this can be changed however it
+        can never exceed number of clusters in the file system. If there is not
+        enough space for the reserved space when mounting the file mount will
+        _not_ fail.
+
+Ioctls
+======
+
+Ext4 implements various ioctls which can be used by applications to access
+ext4-specific functionality. An incomplete list of these ioctls is shown in the
+table below. This list includes truly ext4-specific ioctls (``EXT4_IOC_*``) as
+well as ioctls that may have been ext4-specific originally but are now supported
+by some other filesystem(s) too (``FS_IOC_*``).
+
+Table of Ext4 ioctls
+
+  FS_IOC_GETFLAGS
+        Get additional attributes associated with inode.  The ioctl argument is
+        an integer bitfield, with bit values described in ext4.h.
+
+  FS_IOC_SETFLAGS
+        Set additional attributes associated with inode.  The ioctl argument is
+        an integer bitfield, with bit values described in ext4.h.
+
+  EXT4_IOC_GETVERSION, EXT4_IOC_GETVERSION_OLD
+        Get the inode i_generation number stored for each inode. The
+        i_generation number is normally changed only when new inode is created
+        and it is particularly useful for network filesystems. The '_OLD'
+        version of this ioctl is an alias for FS_IOC_GETVERSION.
+
+  EXT4_IOC_SETVERSION, EXT4_IOC_SETVERSION_OLD
+        Set the inode i_generation number stored for each inode. The '_OLD'
+        version of this ioctl is an alias for FS_IOC_SETVERSION.
+
+  EXT4_IOC_GROUP_EXTEND
+        This ioctl has the same purpose as the resize mount option. It allows
+        to resize filesystem to the end of the last existing block group,
+        further resize has to be done with resize2fs, either online, or
+        offline. The argument points to the unsigned logn number representing
+        the filesystem new block count.
+
+  EXT4_IOC_MOVE_EXT
+        Move the block extents from orig_fd (the one this ioctl is pointing to)
+        to the donor_fd (the one specified in move_extent structure passed as
+        an argument to this ioctl). Then, exchange inode metadata between
+        orig_fd and donor_fd.  This is especially useful for online
+        defragmentation, because the allocator has the opportunity to allocate
+        moved blocks better, ideally into one contiguous extent.
+
+  EXT4_IOC_GROUP_ADD
+        Add a new group descriptor to an existing or new group descriptor
+        block. The new group descriptor is described by ext4_new_group_input
+        structure, which is passed as an argument to this ioctl. This is
+        especially useful in conjunction with EXT4_IOC_GROUP_EXTEND, which
+        allows online resize of the filesystem to the end of the last existing
+        block group.  Those two ioctls combined is used in userspace online
+        resize tool (e.g. resize2fs).
+
+  EXT4_IOC_MIGRATE
+        This ioctl operates on the filesystem itself.  It converts (migrates)
+        ext3 indirect block mapped inode to ext4 extent mapped inode by walking
+        through indirect block mapping of the original inode and converting
+        contiguous block ranges into ext4 extents of the temporary inode. Then,
+        inodes are swapped. This ioctl might help, when migrating from ext3 to
+        ext4 filesystem, however suggestion is to create fresh ext4 filesystem
+        and copy data from the backup. Note, that filesystem has to support
+        extents for this ioctl to work.
+
+  EXT4_IOC_ALLOC_DA_BLKS
+        Force all of the delay allocated blocks to be allocated to preserve
+        application-expected ext3 behaviour. Note that this will also start
+        triggering a write of the data blocks, but this behaviour may change in
+        the future as it is not necessary and has been done this way only for
+        sake of simplicity.
+
+  EXT4_IOC_RESIZE_FS
+        Resize the filesystem to a new size.  The number of blocks of resized
+        filesystem is passed in via 64 bit integer argument.  The kernel
+        allocates bitmaps and inode table, the userspace tool thus just passes
+        the new number of blocks.
+
+  EXT4_IOC_SWAP_BOOT
+        Swap i_blocks and associated attributes (like i_blocks, i_size,
+        i_flags, ...) from the specified inode with inode EXT4_BOOT_LOADER_INO
+        (#5). This is typically used to store a boot loader in a secure part of
+        the filesystem, where it can't be changed by a normal user by accident.
+        The data blocks of the previous boot loader will be associated with the
+        given inode.
+
+References
+==========
+
+kernel source:	<file:fs/ext4/>
+		<file:fs/jbd2/>
+
+programs:	http://e2fsprogs.sourceforge.net/
+
+useful links:	https://fedoraproject.org/wiki/ext3-devel
+		http://www.bullopensource.org/ext4/
+		http://ext4.wiki.kernel.org/index.php/Main_Page
+		https://fedoraproject.org/wiki/Features/Ext4
diff --git a/Documentation/admin-guide/features.rst b/Documentation/admin-guide/features.rst
new file mode 100644
index 000000000..7651eca38
--- /dev/null
+++ b/Documentation/admin-guide/features.rst
@@ -0,0 +1,3 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. kernel-feat:: features
diff --git a/Documentation/admin-guide/filesystem-monitoring.rst b/Documentation/admin-guide/filesystem-monitoring.rst
new file mode 100644
index 000000000..ab8dba762
--- /dev/null
+++ b/Documentation/admin-guide/filesystem-monitoring.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================================
+File system Monitoring with fanotify
+====================================
+
+File system Error Reporting
+===========================
+
+Fanotify supports the FAN_FS_ERROR event type for file system-wide error
+reporting.  It is meant to be used by file system health monitoring
+daemons, which listen for these events and take actions (notify
+sysadmin, start recovery) when a file system problem is detected.
+
+By design, a FAN_FS_ERROR notification exposes sufficient information
+for a monitoring tool to know a problem in the file system has happened.
+It doesn't necessarily provide a user space application with semantics
+to verify an IO operation was successfully executed.  That is out of
+scope for this feature.  Instead, it is only meant as a framework for
+early file system problem detection and reporting recovery tools.
+
+When a file system operation fails, it is common for dozens of kernel
+errors to cascade after the initial failure, hiding the original failure
+log, which is usually the most useful debug data to troubleshoot the
+problem.  For this reason, FAN_FS_ERROR tries to report only the first
+error that occurred for a file system since the last notification, and
+it simply counts additional errors.  This ensures that the most
+important pieces of information are never lost.
+
+FAN_FS_ERROR requires the fanotify group to be setup with the
+FAN_REPORT_FID flag.
+
+At the time of this writing, the only file system that emits FAN_FS_ERROR
+notifications is Ext4.
+
+A FAN_FS_ERROR Notification has the following format::
+
+  ::
+
+     [ Notification Metadata (Mandatory) ]
+     [ Generic Error Record  (Mandatory) ]
+     [ FID record            (Mandatory) ]
+
+The order of records is not guaranteed, and new records might be added
+in the future.  Therefore, applications must not rely on the order and
+must be prepared to skip over unknown records. Please refer to
+``samples/fanotify/fs-monitor.c`` for an example parser.
+
+Generic error record
+--------------------
+
+The generic error record provides enough information for a file system
+agnostic tool to learn about a problem in the file system, without
+providing any additional details about the problem.  This record is
+identified by ``struct fanotify_event_info_header.info_type`` being set
+to FAN_EVENT_INFO_TYPE_ERROR.
+
+  ::
+
+     struct fanotify_event_info_error {
+          struct fanotify_event_info_header hdr;
+         __s32 error;
+         __u32 error_count;
+     };
+
+The `error` field identifies the type of error using errno values.
+`error_count` tracks the number of errors that occurred and were
+suppressed to preserve the original error information, since the last
+notification.
+
+FID record
+----------
+
+The FID record can be used to uniquely identify the inode that triggered
+the error through the combination of fsid and file handle.  A file system
+specific application can use that information to attempt a recovery
+procedure.  Errors that are not related to an inode are reported with an
+empty file handle of type FILEID_INVALID.
diff --git a/Documentation/admin-guide/gpio/gpio-aggregator.rst b/Documentation/admin-guide/gpio/gpio-aggregator.rst
new file mode 100644
index 000000000..8374a9df9
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-aggregator.rst
@@ -0,0 +1,218 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+GPIO Aggregator
+===============
+
+The GPIO Aggregator provides a mechanism to aggregate GPIOs, and expose them as
+a new gpio_chip.  This supports the following use cases.
+
+
+Aggregating GPIOs using Sysfs
+-----------------------------
+
+GPIO controllers are exported to userspace using /dev/gpiochip* character
+devices.  Access control to these devices is provided by standard UNIX file
+system permissions, on an all-or-nothing basis: either a GPIO controller is
+accessible for a user, or it is not.
+
+The GPIO Aggregator provides access control for a set of one or more GPIOs, by
+aggregating them into a new gpio_chip, which can be assigned to a group or user
+using standard UNIX file ownership and permissions.  Furthermore, this
+simplifies and hardens exporting GPIOs to a virtual machine, as the VM can just
+grab the full GPIO controller, and no longer needs to care about which GPIOs to
+grab and which not, reducing the attack surface.
+
+Aggregated GPIO controllers are instantiated and destroyed by writing to
+write-only attribute files in sysfs.
+
+    /sys/bus/platform/drivers/gpio-aggregator/
+
+	"new_device" ...
+		Userspace may ask the kernel to instantiate an aggregated GPIO
+		controller by writing a string describing the GPIOs to
+		aggregate to the "new_device" file, using the format
+
+		.. code-block:: none
+
+		    [<gpioA>] [<gpiochipB> <offsets>] ...
+
+		Where:
+
+		    "<gpioA>" ...
+			    is a GPIO line name,
+
+		    "<gpiochipB>" ...
+			    is a GPIO chip label, and
+
+		    "<offsets>" ...
+			    is a comma-separated list of GPIO offsets and/or
+			    GPIO offset ranges denoted by dashes.
+
+		Example: Instantiate a new GPIO aggregator by aggregating GPIO
+		line 19 of "e6052000.gpio" and GPIO lines 20-21 of
+		"e6050000.gpio" into a new gpio_chip:
+
+		.. code-block:: sh
+
+		    $ echo 'e6052000.gpio 19 e6050000.gpio 20-21' > new_device
+
+	"delete_device" ...
+		Userspace may ask the kernel to destroy an aggregated GPIO
+		controller after use by writing its device name to the
+		"delete_device" file.
+
+		Example: Destroy the previously-created aggregated GPIO
+		controller, assumed to be "gpio-aggregator.0":
+
+		.. code-block:: sh
+
+		    $ echo gpio-aggregator.0 > delete_device
+
+
+Aggregating GPIOs using Configfs
+--------------------------------
+
+**Group:** ``/config/gpio-aggregator``
+
+    This is the root directory of the gpio-aggregator configfs tree.
+
+**Group:** ``/config/gpio-aggregator/<example-name>``
+
+    This directory represents a GPIO aggregator device. You can assign any
+    name to ``<example-name>`` (e.g. ``agg0``), except names starting with
+    ``_sysfs`` prefix, which are reserved for auto-generated configfs
+    entries corresponding to devices created via Sysfs.
+
+**Attribute:** ``/config/gpio-aggregator/<example-name>/live``
+
+    The ``live`` attribute allows to trigger the actual creation of the device
+    once it's fully configured. Accepted values are:
+
+    * ``1``, ``yes``, ``true`` : enable the virtual device
+    * ``0``, ``no``, ``false`` : disable the virtual device
+
+**Attribute:** ``/config/gpio-aggregator/<example-name>/dev_name``
+
+    The read-only ``dev_name`` attribute exposes the name of the device as it
+    will appear in the system on the platform bus (e.g. ``gpio-aggregator.0``).
+    This is useful for identifying a character device for the newly created
+    aggregator. If it's ``gpio-aggregator.0``,
+    ``/sys/devices/platform/gpio-aggregator.0/gpiochipX`` path tells you that the
+    GPIO device id is ``X``.
+
+You must create subdirectories for each virtual line you want to
+instantiate, named exactly as ``line0``, ``line1``, ..., ``lineY``, when
+you want to instantiate ``Y+1`` (Y >= 0) lines.  Configure all lines before
+activating the device by setting ``live`` to 1.
+
+**Group:** ``/config/gpio-aggregator/<example-name>/<lineY>/``
+
+    This directory represents a GPIO line to include in the aggregator.
+
+**Attribute:** ``/config/gpio-aggregator/<example-name>/<lineY>/key``
+
+**Attribute:** ``/config/gpio-aggregator/<example-name>/<lineY>/offset``
+
+    The default values after creating the ``<lineY>`` directory are:
+
+    * ``key`` : <empty>
+    * ``offset`` : -1
+
+    ``key`` must always be explicitly configured, while ``offset`` depends.
+    Two configuration patterns exist for each ``<lineY>``:
+
+    (a). For lookup by GPIO line name:
+
+         * Set ``key`` to the line name.
+         * Ensure ``offset`` remains -1 (the default).
+
+    (b). For lookup by GPIO chip name and the line offset within the chip:
+
+         * Set ``key`` to the chip name.
+         * Set ``offset`` to the line offset (0 <= ``offset`` < 65535).
+
+**Attribute:** ``/config/gpio-aggregator/<example-name>/<lineY>/name``
+
+    The ``name`` attribute sets a custom name for lineY. If left unset, the
+    line will remain unnamed.
+
+Once the configuration is done, the ``'live'`` attribute must be set to 1
+in order to instantiate the aggregator device. It can be set back to 0 to
+destroy the virtual device. The module will synchronously wait for the new
+aggregator device to be successfully probed and if this doesn't happen, writing
+to ``'live'`` will result in an error. This is a different behaviour from the
+case when you create it using sysfs ``new_device`` interface.
+
+.. note::
+
+   For aggregators created via Sysfs, the configfs entries are
+   auto-generated and appear as ``/config/gpio-aggregator/_sysfs.<N>/``. You
+   cannot add or remove line directories with mkdir(2)/rmdir(2). To modify
+   lines, you must use the "delete_device" interface to tear down the
+   existing device and reconfigure it from scratch. However, you can still
+   toggle the aggregator with the ``live`` attribute and adjust the
+   ``key``, ``offset``, and ``name`` attributes for each line when ``live``
+   is set to 0 by hand (i.e. it's not waiting for deferred probe).
+
+Sample configuration commands
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: sh
+
+    # Create a directory for an aggregator device
+    $ mkdir /sys/kernel/config/gpio-aggregator/agg0
+
+    # Configure each line
+    $ mkdir /sys/kernel/config/gpio-aggregator/agg0/line0
+    $ echo gpiochip0 > /sys/kernel/config/gpio-aggregator/agg0/line0/key
+    $ echo 6         > /sys/kernel/config/gpio-aggregator/agg0/line0/offset
+    $ echo test0     > /sys/kernel/config/gpio-aggregator/agg0/line0/name
+    $ mkdir /sys/kernel/config/gpio-aggregator/agg0/line1
+    $ echo gpiochip0 > /sys/kernel/config/gpio-aggregator/agg0/line1/key
+    $ echo 7         > /sys/kernel/config/gpio-aggregator/agg0/line1/offset
+    $ echo test1     > /sys/kernel/config/gpio-aggregator/agg0/line1/name
+
+    # Activate the aggregator device
+    $ echo 1         > /sys/kernel/config/gpio-aggregator/agg0/live
+
+
+Generic GPIO Driver
+-------------------
+
+The GPIO Aggregator can also be used as a generic driver for a simple
+GPIO-operated device described in DT, without a dedicated in-kernel driver.
+This is useful in industrial control, and is not unlike e.g. spidev, which
+allows the user to communicate with an SPI device from userspace.
+
+Binding a device to the GPIO Aggregator is performed either by modifying the
+gpio-aggregator driver, or by writing to the "driver_override" file in Sysfs.
+
+Example: If "door" is a GPIO-operated device described in DT, using its own
+compatible value::
+
+	door {
+		compatible = "myvendor,mydoor";
+
+		gpios = <&gpio2 19 GPIO_ACTIVE_HIGH>,
+			<&gpio2 20 GPIO_ACTIVE_LOW>;
+		gpio-line-names = "open", "lock";
+	};
+
+it can be bound to the GPIO Aggregator by either:
+
+1. Adding its compatible value to ``gpio_aggregator_dt_ids[]``,
+2. Binding manually using "driver_override":
+
+.. code-block:: sh
+
+    $ echo gpio-aggregator > /sys/bus/platform/devices/door/driver_override
+    $ echo door > /sys/bus/platform/drivers/gpio-aggregator/bind
+
+After that, a new gpiochip "door" has been created:
+
+.. code-block:: sh
+
+    $ gpioinfo door
+    gpiochip12 - 2 lines:
+	    line   0:       "open"       unused   input  active-high
+	    line   1:       "lock"       unused   input  active-high
diff --git a/Documentation/admin-guide/gpio/gpio-mockup.rst b/Documentation/admin-guide/gpio/gpio-mockup.rst
new file mode 100644
index 000000000..d6e7438a7
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-mockup.rst
@@ -0,0 +1,59 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+GPIO Testing Driver
+===================
+
+.. note::
+
+   This module has been obsoleted by the more flexible gpio-sim.rst.
+   New developments should use that API and existing developments are
+   encouraged to migrate as soon as possible.
+   This module will continue to be maintained but no new features will be
+   added.
+
+The GPIO Testing Driver (gpio-mockup) provides a way to create simulated GPIO
+chips for testing purposes. The lines exposed by these chips can be accessed
+using the standard GPIO character device interface as well as manipulated
+using the dedicated debugfs directory structure.
+
+Creating simulated chips using module params
+--------------------------------------------
+
+When loading the gpio-mockup driver a number of parameters can be passed to the
+module.
+
+    gpio_mockup_ranges
+
+        This parameter takes an argument in the form of an array of integer
+        pairs. Each pair defines the base GPIO number (non-negative integer)
+        and the first number after the last of this chip. If the base GPIO
+        is -1, the gpiolib will assign it automatically. while the following
+        parameter is the number of lines exposed by the chip.
+
+        Example: gpio_mockup_ranges=-1,8,-1,16,405,409
+
+        The line above creates three chips. The first one will expose 8 lines,
+        the second 16 and the third 4. The base GPIO for the third chip is set
+        to 405 while for two first chips it will be assigned automatically.
+
+    gpio_mockup_named_lines
+
+        This parameter doesn't take any arguments. It lets the driver know that
+        GPIO lines exposed by it should be named.
+
+        The name format is: gpio-mockup-X-Y where X is mockup chip's ID
+        and Y is the line offset.
+
+Manipulating simulated lines
+----------------------------
+
+Each mockup chip creates its own subdirectory in /sys/kernel/debug/gpio-mockup/.
+The directory is named after the chip's label. A symlink is also created, named
+after the chip's name, which points to the label directory.
+
+Inside each subdirectory, there's a separate attribute for each GPIO line. The
+name of the attribute represents the line's offset in the chip.
+
+Reading from a line attribute returns the current value. Writing to it (0 or 1)
+changes the configuration of the simulated pull-up/pull-down resistor
+(1 - pull-up, 0 - pull-down).
diff --git a/Documentation/admin-guide/gpio/gpio-sim.rst b/Documentation/admin-guide/gpio/gpio-sim.rst
new file mode 100644
index 000000000..f5135a14e
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-sim.rst
@@ -0,0 +1,137 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Configfs GPIO Simulator
+=======================
+
+The configfs GPIO Simulator (gpio-sim) provides a way to create simulated GPIO
+chips for testing purposes. The lines exposed by these chips can be accessed
+using the standard GPIO character device interface as well as manipulated
+using sysfs attributes.
+
+Creating simulated chips
+------------------------
+
+The gpio-sim module registers a configfs subsystem called ``'gpio-sim'``. For
+details of the configfs filesystem, please refer to the configfs documentation.
+
+The user can create a hierarchy of configfs groups and items as well as modify
+values of exposed attributes. Once the chip is instantiated, this hierarchy
+will be translated to appropriate device properties. The general structure is:
+
+**Group:** ``/config/gpio-sim``
+
+This is the top directory of the gpio-sim configfs tree.
+
+**Group:** ``/config/gpio-sim/gpio-device``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/dev_name``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/live``
+
+This is a directory representing a GPIO platform device. The ``'dev_name'``
+attribute is read-only and allows the user-space to read the platform device
+name (e.g. ``'gpio-sim.0'``). The ``'live'`` attribute allows to trigger the
+actual creation of the device once it's fully configured. The accepted values
+are: ``'1'`` to enable the simulated device and ``'0'`` to disable and tear
+it down.
+
+**Group:** ``/config/gpio-sim/gpio-device/gpio-bankX``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/chip_name``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/num_lines``
+
+This group represents a bank of GPIOs under the top platform device. The
+``'chip_name'`` attribute is read-only and allows the user-space to read the
+device name of the bank device. The ``'num_lines'`` attribute allows to specify
+the number of lines exposed by this bank.
+
+**Group:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/name``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/valid``
+
+This group represents a single line at the offset Y. The ``valid`` attribute
+indicates whether the line can be used as GPIO. The ``name`` attribute allows
+to set the line name as represented by the 'gpio-line-names' property.
+
+**Item:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog/name``
+
+**Attribute:** ``/config/gpio-sim/gpio-device/gpio-bankX/lineY/hog/direction``
+
+This item makes the gpio-sim module hog the associated line. The ``'name'``
+attribute specifies the in-kernel consumer name to use. The ``'direction'``
+attribute specifies the hog direction and must be one of: ``'input'``,
+``'output-high'`` and ``'output-low'``.
+
+Inside each bank directory, there's a set of attributes that can be used to
+configure the new chip. Additionally the user can ``mkdir()`` subdirectories
+inside the chip's directory that allow to pass additional configuration for
+specific lines. The name of those subdirectories must take the form of:
+``'line<offset>'`` (e.g. ``'line0'``, ``'line20'``, etc.) as the name will be
+used by the module to assign the config to the specific line at given offset.
+
+Once the configuration is complete, the ``'live'`` attribute must be set to 1 in
+order to instantiate the chip. It can be set back to 0 to destroy the simulated
+chip. The module will synchronously wait for the new simulated device to be
+successfully probed and if this doesn't happen, writing to ``'live'`` will
+result in an error.
+
+Simulated GPIO chips can also be defined in device-tree. The compatible string
+must be: ``"gpio-simulator"``. Supported properties are:
+
+  ``"gpio-sim,label"`` - chip label
+
+Other standard GPIO properties (like ``"gpio-line-names"``, ``"ngpios"`` or
+``"gpio-hog"``) are also supported. Please refer to the GPIO documentation for
+details.
+
+An example device-tree code defining a GPIO simulator:
+
+.. code-block :: none
+
+    gpio-sim {
+        compatible = "gpio-simulator";
+
+        bank0 {
+            gpio-controller;
+            #gpio-cells = <2>;
+            ngpios = <16>;
+            gpio-sim,label = "dt-bank0";
+            gpio-line-names = "", "sim-foo", "", "sim-bar";
+        };
+
+        bank1 {
+            gpio-controller;
+            #gpio-cells = <2>;
+            ngpios = <8>;
+            gpio-sim,label = "dt-bank1";
+
+            line3 {
+                gpio-hog;
+                gpios = <3 0>;
+                output-high;
+                line-name = "sim-hog-from-dt";
+            };
+        };
+    };
+
+Manipulating simulated lines
+----------------------------
+
+Each simulated GPIO chip creates a separate sysfs group under its device
+directory for each exposed line
+(e.g. ``/sys/devices/platform/gpio-sim.X/gpiochipY/``). The name of each group
+is of the form: ``'sim_gpioX'`` where X is the offset of the line. Inside each
+group there are two attributes:
+
+    ``pull`` - allows to read and set the current simulated pull setting for
+               every line, when writing the value must be one of: ``'pull-up'``,
+               ``'pull-down'``
+
+    ``value`` - allows to read the current value of the line which may be
+                different from the pull if the line is being driven from
+                user-space
diff --git a/Documentation/admin-guide/gpio/gpio-virtuser.rst b/Documentation/admin-guide/gpio/gpio-virtuser.rst
new file mode 100644
index 000000000..7e7c0df51
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-virtuser.rst
@@ -0,0 +1,177 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Virtual GPIO Consumer
+=====================
+
+The virtual GPIO Consumer module allows users to instantiate virtual devices
+that request GPIOs and then control their behavior over debugfs. Virtual
+consumer devices can be instantiated from device-tree or over configfs.
+
+A virtual consumer uses the driver-facing GPIO APIs and allows to cover it with
+automated tests driven by user-space. The GPIOs are requested using
+``gpiod_get_array()`` and so we support multiple GPIOs per connector ID.
+
+Creating GPIO consumers
+-----------------------
+
+The gpio-consumer module registers a configfs subsystem called
+``'gpio-virtuser'``. For details of the configfs filesystem, please refer to
+the configfs documentation.
+
+The user can create a hierarchy of configfs groups and items as well as modify
+values of exposed attributes. Once the consumer is instantiated, this hierarchy
+will be translated to appropriate device properties. The general structure is:
+
+**Group:** ``/config/gpio-virtuser``
+
+This is the top directory of the gpio-consumer configfs tree.
+
+**Group:** ``/config/gpio-consumer/example-name``
+
+**Attribute:** ``/config/gpio-consumer/example-name/live``
+
+**Attribute:** ``/config/gpio-consumer/example-name/dev_name``
+
+This is a directory representing a GPIO consumer device.
+
+The read-only ``dev_name`` attribute exposes the name of the device as it will
+appear in the system on the platform bus. This is useful for locating the
+associated debugfs directory under
+``/sys/kernel/debug/gpio-virtuser/$dev_name``.
+
+The ``'live'`` attribute allows to trigger the actual creation of the device
+once it's fully configured. The accepted values are: ``'1'`` to enable the
+virtual device and ``'0'`` to disable and tear it down.
+
+Creating GPIO lookup tables
+---------------------------
+
+Users can create a number of configfs groups under the device group:
+
+**Group:** ``/config/gpio-consumer/example-name/con_id``
+
+The ``'con_id'`` directory represents a single GPIO lookup and its value maps
+to the ``'con_id'`` argument of the ``gpiod_get()`` function. For example:
+``con_id`` == ``'reset'`` maps to the ``reset-gpios`` device property.
+
+Users can assign a number of GPIOs to each lookup. Each GPIO is a sub-directory
+with a user-defined name under the ``'con_id'`` group.
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/key``
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/offset``
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/drive``
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/pull``
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/active_low``
+
+**Attribute:** ``/config/gpio-consumer/example-name/con_id/0/transitory``
+
+This is a group describing a single GPIO in the ``con_id-gpios`` property.
+
+For virtual consumers created using configfs we use machine lookup tables so
+this group can be considered as a mapping between the filesystem and the fields
+of a single entry in ``'struct gpiod_lookup'``.
+
+The ``'key'`` attribute represents either the name of the chip this GPIO
+belongs to or the GPIO line name. This depends on the value of the ``'offset'``
+attribute: if its value is >= 0, then ``'key'`` represents the label of the
+chip to lookup while ``'offset'`` represents the offset of the line in that
+chip. If ``'offset'`` is < 0, then ``'key'`` represents the name of the line.
+
+The remaining attributes map to the ``'flags'`` field of the GPIO lookup
+struct. The first two take string values as arguments:
+
+**``'drive'``:** ``'push-pull'``, ``'open-drain'``, ``'open-source'``
+**``'pull'``:** ``'pull-up'``, ``'pull-down'``, ``'pull-disabled'``, ``'as-is'``
+
+``'active_low'`` and ``'transitory'`` are boolean attributes.
+
+Activating GPIO consumers
+-------------------------
+
+Once the configuration is complete, the ``'live'`` attribute must be set to 1 in
+order to instantiate the consumer. It can be set back to 0 to destroy the
+virtual device. The module will synchronously wait for the new simulated device
+to be successfully probed and if this doesn't happen, writing to ``'live'`` will
+result in an error.
+
+Device-tree
+-----------
+
+Virtual GPIO consumers can also be defined in device-tree. The compatible string
+must be: ``"gpio-virtuser"`` with at least one property following the
+standardized GPIO pattern.
+
+An example device-tree code defining a virtual GPIO consumer:
+
+.. code-block :: none
+
+    gpio-virt-consumer {
+        compatible = "gpio-virtuser";
+
+        foo-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>, <&gpio1 2 0>;
+        bar-gpios = <&gpio0 6 0>;
+    };
+
+Controlling virtual GPIO consumers
+----------------------------------
+
+Once active, the device will export debugfs attributes for controlling GPIO
+arrays as well as each requested GPIO line separately. Let's consider the
+following device property: ``foo-gpios = <&gpio0 0 0>, <&gpio0 4 0>;``.
+
+The following debugfs attribute groups will be created:
+
+**Group:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo/``
+
+This is the group that will contain the attributes for the entire GPIO array.
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo/values``
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo/values_atomic``
+
+Both attributes allow to read and set arrays of GPIO values. User must pass
+exactly the number of values that the array contains in the form of a string
+containing zeroes and ones representing inactive and active GPIO states
+respectively. In this example: ``echo 11 > values``.
+
+The ``values_atomic`` attribute works the same as ``values`` but the kernel
+will execute the GPIO driver callbacks in interrupt context.
+
+**Group:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/``
+
+This is a group that represents a single GPIO with ``$index`` being its offset
+in the array.
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/consumer``
+
+Allows to set and read the consumer label of the GPIO line.
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/debounce``
+
+Allows to set and read the debounce period of the GPIO line.
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/direction``
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/direction_atomic``
+
+These two attributes allow to set the direction of the GPIO line. They accept
+"input" and "output" as values. The atomic variant executes the driver callback
+in interrupt context.
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/interrupts``
+
+If the line is requested in input mode, writing ``1`` to this attribute will
+make the module listen for edge interrupts on the GPIO. Writing ``0`` disables
+the monitoring. Reading this attribute returns the current number of registered
+interrupts (both edges).
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/value``
+
+**Attribute:** ``/sys/kernel/debug/gpio-virtuser/$dev_name/gpiod:foo:$index/value_atomic``
+
+Both attributes allow to read and set values of individual requested GPIO lines.
+They accept the following values: ``1`` and ``0``.
diff --git a/Documentation/admin-guide/gpio/index.rst b/Documentation/admin-guide/gpio/index.rst
new file mode 100644
index 000000000..082646851
--- /dev/null
+++ b/Documentation/admin-guide/gpio/index.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+GPIO
+====
+
+.. toctree::
+    :maxdepth: 1
+
+    Character Device Userspace API <../../userspace-api/gpio/chardev>
+    gpio-aggregator
+    gpio-sim
+    gpio-virtuser
+    Obsolete APIs <obsolete>
diff --git a/Documentation/admin-guide/gpio/obsolete.rst b/Documentation/admin-guide/gpio/obsolete.rst
new file mode 100644
index 000000000..5adbff02d
--- /dev/null
+++ b/Documentation/admin-guide/gpio/obsolete.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+Obsolete GPIO APIs
+==================
+
+.. toctree::
+    :maxdepth: 1
+
+    Character Device Userspace API (v1) <../../userspace-api/gpio/chardev_v1>
+    Sysfs Interface <../../userspace-api/gpio/sysfs>
+    Mockup Testing Module <gpio-mockup>
+
diff --git a/Documentation/admin-guide/hw-vuln/attack_vector_controls.rst b/Documentation/admin-guide/hw-vuln/attack_vector_controls.rst
new file mode 100644
index 000000000..d0bdbd81d
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/attack_vector_controls.rst
@@ -0,0 +1,236 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Attack Vector Controls
+======================
+
+Attack vector controls provide a simple method to configure only the mitigations
+for CPU vulnerabilities which are relevant given the intended use of a system.
+Administrators are encouraged to consider which attack vectors are relevant and
+disable all others in order to recoup system performance.
+
+When new relevant CPU vulnerabilities are found, they will be added to these
+attack vector controls so administrators will likely not need to reconfigure
+their command line parameters as mitigations will continue to be correctly
+applied based on the chosen attack vector controls.
+
+Attack Vectors
+--------------
+
+There are 5 sets of attack-vector mitigations currently supported by the kernel:
+
+#. :ref:`user_kernel`
+#. :ref:`user_user`
+#. :ref:`guest_host`
+#. :ref:`guest_guest`
+#. :ref:`smt`
+
+To control the enabled attack vectors, see :ref:`cmdline`.
+
+.. _user_kernel:
+
+User-to-Kernel
+^^^^^^^^^^^^^^
+
+The user-to-kernel attack vector involves a malicious userspace program
+attempting to leak kernel data into userspace by exploiting a CPU vulnerability.
+The kernel data involved might be limited to certain kernel memory, or include
+all memory in the system, depending on the vulnerability exploited.
+
+If no untrusted userspace applications are being run, such as with single-user
+systems, consider disabling user-to-kernel mitigations.
+
+Note that the CPU vulnerabilities mitigated by Linux have generally not been
+shown to be exploitable from browser-based sandboxes.  User-to-kernel
+mitigations are therefore mostly relevant if unknown userspace applications may
+be run by untrusted users.
+
+*user-to-kernel mitigations are enabled by default*
+
+.. _user_user:
+
+User-to-User
+^^^^^^^^^^^^
+
+The user-to-user attack vector involves a malicious userspace program attempting
+to influence the behavior of another unsuspecting userspace program in order to
+exfiltrate data.  The vulnerability of a userspace program is based on the
+program itself and the interfaces it provides.
+
+If no untrusted userspace applications are being run, consider disabling
+user-to-user mitigations.
+
+Note that because the Linux kernel contains a mapping of all physical memory,
+preventing a malicious userspace program from leaking data from another
+userspace program requires mitigating user-to-kernel attacks as well for
+complete protection.
+
+*user-to-user mitigations are enabled by default*
+
+.. _guest_host:
+
+Guest-to-Host
+^^^^^^^^^^^^^
+
+The guest-to-host attack vector involves a malicious VM attempting to leak
+hypervisor data into the VM.  The data involved may be limited, or may
+potentially include all memory in the system, depending on the vulnerability
+exploited.
+
+If no untrusted VMs are being run, consider disabling guest-to-host mitigations.
+
+*guest-to-host mitigations are enabled by default if KVM support is present*
+
+.. _guest_guest:
+
+Guest-to-Guest
+^^^^^^^^^^^^^^
+
+The guest-to-guest attack vector involves a malicious VM attempting to influence
+the behavior of another unsuspecting VM in order to exfiltrate data.  The
+vulnerability of a VM is based on the code inside the VM itself and the
+interfaces it provides.
+
+If no untrusted VMs, or only a single VM is being run, consider disabling
+guest-to-guest mitigations.
+
+Similar to the user-to-user attack vector, preventing a malicious VM from
+leaking data from another VM requires mitigating guest-to-host attacks as well
+due to the Linux kernel phys map.
+
+*guest-to-guest mitigations are enabled by default if KVM support is present*
+
+.. _smt:
+
+Cross-Thread
+^^^^^^^^^^^^
+
+The cross-thread attack vector involves a malicious userspace program or
+malicious VM either observing or attempting to influence the behavior of code
+running on the SMT sibling thread in order to exfiltrate data.
+
+Many cross-thread attacks can only be mitigated if SMT is disabled, which will
+result in reduced CPU core count and reduced performance.
+
+If cross-thread mitigations are fully enabled ('auto,nosmt'), all mitigations
+for cross-thread attacks will be enabled.  SMT may be disabled depending on
+which vulnerabilities are present in the CPU.
+
+If cross-thread mitigations are partially enabled ('auto'), mitigations for
+cross-thread attacks will be enabled but SMT will not be disabled.
+
+If cross-thread mitigations are disabled, no mitigations for cross-thread
+attacks will be enabled.
+
+Cross-thread mitigation may not be required if core-scheduling or similar
+techniques are used to prevent untrusted workloads from running on SMT siblings.
+
+*cross-thread mitigations default to partially enabled*
+
+.. _cmdline:
+
+Command Line Controls
+---------------------
+
+Attack vectors are controlled through the mitigations= command line option.  The
+value provided begins with a global option and then may optionally include one
+or more options to disable various attack vectors.
+
+Format:
+	| ``mitigations=[global]``
+	| ``mitigations=[global],[attack vectors]``
+
+Global options:
+
+============ =============================================================
+Option       Description
+============ =============================================================
+'off'        All attack vectors disabled.
+'auto'       All attack vectors enabled, partial cross-thread mitigations.
+'auto,nosmt' All attack vectors enabled, full cross-thread mitigations.
+============ =============================================================
+
+Attack vector options:
+
+================= =======================================
+Option            Description
+================= =======================================
+'no_user_kernel'  Disables user-to-kernel mitigations.
+'no_user_user'    Disables user-to-user mitigations.
+'no_guest_host'   Disables guest-to-host mitigations.
+'no_guest_guest'  Disables guest-to-guest mitigations
+'no_cross_thread' Disables all cross-thread mitigations.
+================= =======================================
+
+Multiple attack vector options may be specified in a comma-separated list.  If
+the global option is not specified, it defaults to 'auto'.  The global option
+'off' is equivalent to disabling all attack vectors.
+
+Examples:
+	| ``mitigations=auto,no_user_kernel``
+
+	Enable all attack vectors except user-to-kernel.  Partial cross-thread
+	mitigations.
+
+	| ``mitigations=auto,nosmt,no_guest_host,no_guest_guest``
+
+	Enable all attack vectors and cross-thread mitigations except for
+	guest-to-host and guest-to-guest mitigations.
+
+	| ``mitigations=,no_cross_thread``
+
+	Enable all attack vectors but not cross-thread mitigations.
+
+Interactions with command-line options
+--------------------------------------
+
+Vulnerability-specific controls (e.g. "retbleed=off") take precedence over all
+attack vector controls.  Mitigations for individual vulnerabilities may be
+turned on or off via their command-line options regardless of the attack vector
+controls.
+
+Summary of attack-vector mitigations
+------------------------------------
+
+When a vulnerability is mitigated due to an attack-vector control, the default
+mitigation option for that particular vulnerability is used.  To use a different
+mitigation, please use the vulnerability-specific command line option.
+
+The table below summarizes which vulnerabilities are mitigated when different
+attack vectors are enabled and assuming the CPU is vulnerable.
+
+=============== ============== ============ ============= ============== ============ ========
+Vulnerability   User-to-Kernel User-to-User Guest-to-Host Guest-to-Guest Cross-Thread Notes
+=============== ============== ============ ============= ============== ============ ========
+BHI                   X                           X
+ITS                   X                           X
+GDS                   X              X            X              X            *       (Note 1)
+L1TF                  X                           X                           *       (Note 2)
+MDS                   X              X            X              X            *       (Note 2)
+MMIO                  X              X            X              X            *       (Note 2)
+Meltdown              X
+Retbleed              X                           X                           *       (Note 3)
+RFDS                  X              X            X              X
+Spectre_v1            X
+Spectre_v2            X                           X
+Spectre_v2_user                      X                           X            *       (Note 1)
+SRBDS                 X              X            X              X
+SRSO                  X              X            X              X
+SSB                                  X
+TAA                   X              X            X              X            *       (Note 2)
+TSA                   X              X            X              X
+VMSCAPE                                           X
+=============== ============== ============ ============= ============== ============ ========
+
+Notes:
+   1 --  Can be mitigated without disabling SMT.
+
+   2 --  Disables SMT if cross-thread mitigations are fully enabled  and the CPU
+   is vulnerable
+
+   3 --  Disables SMT if cross-thread mitigations are fully enabled, the CPU is
+   vulnerable, and STIBP is not supported
+
+When an attack-vector is disabled, all mitigations for the vulnerabilities
+listed in the above table are disabled, unless mitigation is required for a
+different enabled attack-vector or a mitigation is explicitly selected via a
+vulnerability-specific command line option.
diff --git a/Documentation/admin-guide/hw-vuln/core-scheduling.rst b/Documentation/admin-guide/hw-vuln/core-scheduling.rst
new file mode 100644
index 000000000..a92e10ec4
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/core-scheduling.rst
@@ -0,0 +1,226 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Core Scheduling
+===============
+Core scheduling support allows userspace to define groups of tasks that can
+share a core. These groups can be specified either for security usecases (one
+group of tasks don't trust another), or for performance usecases (some
+workloads may benefit from running on the same core as they don't need the same
+hardware resources of the shared core, or may prefer different cores if they
+do share hardware resource needs). This document only describes the security
+usecase.
+
+Security usecase
+----------------
+A cross-HT attack involves the attacker and victim running on different Hyper
+Threads of the same core. MDS and L1TF are examples of such attacks.  The only
+full mitigation of cross-HT attacks is to disable Hyper Threading (HT). Core
+scheduling is a scheduler feature that can mitigate some (not all) cross-HT
+attacks. It allows HT to be turned on safely by ensuring that only tasks in a
+user-designated trusted group can share a core. This increase in core sharing
+can also improve performance, however it is not guaranteed that performance
+will always improve, though that is seen to be the case with a number of real
+world workloads. In theory, core scheduling aims to perform at least as good as
+when Hyper Threading is disabled. In practice, this is mostly the case though
+not always: as synchronizing scheduling decisions across 2 or more CPUs in a
+core involves additional overhead - especially when the system is lightly
+loaded. When ``total_threads <= N_CPUS/2``, the extra overhead may cause core
+scheduling to perform more poorly compared to SMT-disabled, where N_CPUS is the
+total number of CPUs. Please measure the performance of your workloads always.
+
+Usage
+-----
+Core scheduling support is enabled via the ``CONFIG_SCHED_CORE`` config option.
+Using this feature, userspace defines groups of tasks that can be co-scheduled
+on the same core. The core scheduler uses this information to make sure that
+tasks that are not in the same group never run simultaneously on a core, while
+doing its best to satisfy the system's scheduling requirements.
+
+Core scheduling can be enabled via the ``PR_SCHED_CORE`` prctl interface.
+This interface provides support for the creation of core scheduling groups, as
+well as admission and removal of tasks from created groups::
+
+    #include <sys/prctl.h>
+
+    int prctl(int option, unsigned long arg2, unsigned long arg3,
+            unsigned long arg4, unsigned long arg5);
+
+option:
+    ``PR_SCHED_CORE``
+
+arg2:
+    Command for operation, must be one off:
+
+    - ``PR_SCHED_CORE_GET`` -- get core_sched cookie of ``pid``.
+    - ``PR_SCHED_CORE_CREATE`` -- create a new unique cookie for ``pid``.
+    - ``PR_SCHED_CORE_SHARE_TO`` -- push core_sched cookie to ``pid``.
+    - ``PR_SCHED_CORE_SHARE_FROM`` -- pull core_sched cookie from ``pid``.
+
+arg3:
+    ``pid`` of the task for which the operation applies.
+
+arg4:
+    ``pid_type`` for which the operation applies. It is one of
+    ``PR_SCHED_CORE_SCOPE_``-prefixed macro constants.  For example, if arg4
+    is ``PR_SCHED_CORE_SCOPE_THREAD_GROUP``, then the operation of this command
+    will be performed for all tasks in the task group of ``pid``.
+
+arg5:
+    userspace pointer to an unsigned long long for storing the cookie returned
+    by ``PR_SCHED_CORE_GET`` command. Should be 0 for all other commands.
+
+In order for a process to push a cookie to, or pull a cookie from a process, it
+is required to have the ptrace access mode: `PTRACE_MODE_READ_REALCREDS` to the
+process.
+
+Building hierarchies of tasks
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The simplest way to build hierarchies of threads/processes which share a
+cookie and thus a core is to rely on the fact that the core-sched cookie is
+inherited across forks/clones and execs, thus setting a cookie for the
+'initial' script/executable/daemon will place every spawned child in the
+same core-sched group.
+
+Cookie Transferral
+~~~~~~~~~~~~~~~~~~
+Transferring a cookie between the current and other tasks is possible using
+PR_SCHED_CORE_SHARE_FROM and PR_SCHED_CORE_SHARE_TO to inherit a cookie from a
+specified task or a share a cookie with a task. In combination this allows a
+simple helper program to pull a cookie from a task in an existing core
+scheduling group and share it with already running tasks.
+
+Design/Implementation
+---------------------
+Each task that is tagged is assigned a cookie internally in the kernel. As
+mentioned in `Usage`_, tasks with the same cookie value are assumed to trust
+each other and share a core.
+
+The basic idea is that, every schedule event tries to select tasks for all the
+siblings of a core such that all the selected tasks running on a core are
+trusted (same cookie) at any point in time. Kernel threads are assumed trusted.
+The idle task is considered special, as it trusts everything and everything
+trusts it.
+
+During a schedule() event on any sibling of a core, the highest priority task on
+the sibling's core is picked and assigned to the sibling calling schedule(), if
+the sibling has the task enqueued. For rest of the siblings in the core,
+highest priority task with the same cookie is selected if there is one runnable
+in their individual run queues. If a task with same cookie is not available,
+the idle task is selected.  Idle task is globally trusted.
+
+Once a task has been selected for all the siblings in the core, an IPI is sent to
+siblings for whom a new task was selected. Siblings on receiving the IPI will
+switch to the new task immediately. If an idle task is selected for a sibling,
+then the sibling is considered to be in a `forced idle` state. I.e., it may
+have tasks on its on runqueue to run, however it will still have to run idle.
+More on this in the next section.
+
+Forced-idling of hyperthreads
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The scheduler tries its best to find tasks that trust each other such that all
+tasks selected to be scheduled are of the highest priority in a core.  However,
+it is possible that some runqueues had tasks that were incompatible with the
+highest priority ones in the core. Favoring security over fairness, one or more
+siblings could be forced to select a lower priority task if the highest
+priority task is not trusted with respect to the core wide highest priority
+task.  If a sibling does not have a trusted task to run, it will be forced idle
+by the scheduler (idle thread is scheduled to run).
+
+When the highest priority task is selected to run, a reschedule-IPI is sent to
+the sibling to force it into idle. This results in 4 cases which need to be
+considered depending on whether a VM or a regular usermode process was running
+on either HT::
+
+          HT1 (attack)            HT2 (victim)
+   A      idle -> user space      user space -> idle
+   B      idle -> user space      guest -> idle
+   C      idle -> guest           user space -> idle
+   D      idle -> guest           guest -> idle
+
+Note that for better performance, we do not wait for the destination CPU
+(victim) to enter idle mode. This is because the sending of the IPI would bring
+the destination CPU immediately into kernel mode from user space, or VMEXIT
+in the case of guests. At best, this would only leak some scheduler metadata
+which may not be worth protecting. It is also possible that the IPI is received
+too late on some architectures, but this has not been observed in the case of
+x86.
+
+Trust model
+~~~~~~~~~~~
+Core scheduling maintains trust relationships amongst groups of tasks by
+assigning them a tag that is the same cookie value.
+When a system with core scheduling boots, all tasks are considered to trust
+each other. This is because the core scheduler does not have information about
+trust relationships until userspace uses the above mentioned interfaces, to
+communicate them. In other words, all tasks have a default cookie value of 0.
+and are considered system-wide trusted. The forced-idling of siblings running
+cookie-0 tasks is also avoided.
+
+Once userspace uses the above mentioned interfaces to group sets of tasks, tasks
+within such groups are considered to trust each other, but do not trust those
+outside. Tasks outside the group also don't trust tasks within.
+
+Limitations of core-scheduling
+------------------------------
+Core scheduling tries to guarantee that only trusted tasks run concurrently on a
+core. But there could be small window of time during which untrusted tasks run
+concurrently or kernel could be running concurrently with a task not trusted by
+kernel.
+
+IPI processing delays
+~~~~~~~~~~~~~~~~~~~~~
+Core scheduling selects only trusted tasks to run together. IPI is used to notify
+the siblings to switch to the new task. But there could be hardware delays in
+receiving of the IPI on some arch (on x86, this has not been observed). This may
+cause an attacker task to start running on a CPU before its siblings receive the
+IPI. Even though cache is flushed on entry to user mode, victim tasks on siblings
+may populate data in the cache and micro architectural buffers after the attacker
+starts to run and this is a possibility for data leak.
+
+Open cross-HT issues that core scheduling does not solve
+--------------------------------------------------------
+1. For MDS
+~~~~~~~~~~
+Core scheduling cannot protect against MDS attacks between the siblings
+running in user mode and the others running in kernel mode. Even though all
+siblings run tasks which trust each other, when the kernel is executing
+code on behalf of a task, it cannot trust the code running in the
+sibling. Such attacks are possible for any combination of sibling CPU modes
+(host or guest mode).
+
+2. For L1TF
+~~~~~~~~~~~
+Core scheduling cannot protect against an L1TF guest attacker exploiting a
+guest or host victim. This is because the guest attacker can craft invalid
+PTEs which are not inverted due to a vulnerable guest kernel. The only
+solution is to disable EPT (Extended Page Tables).
+
+For both MDS and L1TF, if the guest vCPU is configured to not trust each
+other (by tagging separately), then the guest to guest attacks would go away.
+Or it could be a system admin policy which considers guest to guest attacks as
+a guest problem.
+
+Another approach to resolve these would be to make every untrusted task on the
+system to not trust every other untrusted task. While this could reduce
+parallelism of the untrusted tasks, it would still solve the above issues while
+allowing system processes (trusted tasks) to share a core.
+
+3. Protecting the kernel (IRQ, syscall, VMEXIT)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Unfortunately, core scheduling does not protect kernel contexts running on
+sibling hyperthreads from one another. Prototypes of mitigations have been posted
+to LKML to solve this, but it is debatable whether such windows are practically
+exploitable, and whether the performance overhead of the prototypes are worth
+it (not to mention, the added code complexity).
+
+Other Use cases
+---------------
+The main use case for Core scheduling is mitigating the cross-HT vulnerabilities
+with SMT enabled. There are other use cases where this feature could be used:
+
+- Isolating tasks that needs a whole core: Examples include realtime tasks, tasks
+  that uses SIMD instructions etc.
+- Gang scheduling: Requirements for a group of tasks that needs to be scheduled
+  together could also be realized using core scheduling. One example is vCPUs of
+  a VM.
diff --git a/Documentation/admin-guide/hw-vuln/cross-thread-rsb.rst b/Documentation/admin-guide/hw-vuln/cross-thread-rsb.rst
new file mode 100644
index 000000000..875616d67
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/cross-thread-rsb.rst
@@ -0,0 +1,91 @@
+
+.. SPDX-License-Identifier: GPL-2.0
+
+Cross-Thread Return Address Predictions
+=======================================
+
+Certain AMD and Hygon processors are subject to a cross-thread return address
+predictions vulnerability. When running in SMT mode and one sibling thread
+transitions out of C0 state, the other sibling thread could use return target
+predictions from the sibling thread that transitioned out of C0.
+
+The Spectre v2 mitigations protect the Linux kernel, as it fills the return
+address prediction entries with safe targets when context switching to the idle
+thread. However, KVM does allow a VMM to prevent exiting guest mode when
+transitioning out of C0. This could result in a guest-controlled return target
+being consumed by the sibling thread.
+
+Affected processors
+-------------------
+
+The following CPUs are vulnerable:
+
+    - AMD Family 17h processors
+    - Hygon Family 18h processors
+
+Related CVEs
+------------
+
+The following CVE entry is related to this issue:
+
+   ==============  =======================================
+   CVE-2022-27672  Cross-Thread Return Address Predictions
+   ==============  =======================================
+
+Problem
+-------
+
+Affected SMT-capable processors support 1T and 2T modes of execution when SMT
+is enabled. In 2T mode, both threads in a core are executing code. For the
+processor core to enter 1T mode, it is required that one of the threads
+requests to transition out of the C0 state. This can be communicated with the
+HLT instruction or with an MWAIT instruction that requests non-C0.
+When the thread re-enters the C0 state, the processor transitions back
+to 2T mode, assuming the other thread is also still in C0 state.
+
+In affected processors, the return address predictor (RAP) is partitioned
+depending on the SMT mode. For instance, in 2T mode each thread uses a private
+16-entry RAP, but in 1T mode, the active thread uses a 32-entry RAP. Upon
+transition between 1T/2T mode, the RAP contents are not modified but the RAP
+pointers (which control the next return target to use for predictions) may
+change. This behavior may result in return targets from one SMT thread being
+used by RET predictions in the sibling thread following a 1T/2T switch. In
+particular, a RET instruction executed immediately after a transition to 1T may
+use a return target from the thread that just became idle. In theory, this
+could lead to information disclosure if the return targets used do not come
+from trustworthy code.
+
+Attack scenarios
+----------------
+
+An attack can be mounted on affected processors by performing a series of CALL
+instructions with targeted return locations and then transitioning out of C0
+state.
+
+Mitigation mechanism
+--------------------
+
+Before entering idle state, the kernel context switches to the idle thread. The
+context switch fills the RAP entries (referred to as the RSB in Linux) with safe
+targets by performing a sequence of CALL instructions.
+
+Prevent a guest VM from directly putting the processor into an idle state by
+intercepting HLT and MWAIT instructions.
+
+Both mitigations are required to fully address this issue.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+Use existing Spectre v2 mitigations that will fill the RSB on context switch.
+
+Mitigation control for KVM - module parameter
+---------------------------------------------
+
+By default, the KVM hypervisor mitigates this issue by intercepting guest
+attempts to transition out of C0. A VMM can use the KVM_CAP_X86_DISABLE_EXITS
+capability to override those interceptions, but since this is not common, the
+mitigation that covers this path is not enabled by default.
+
+The mitigation for the KVM_CAP_X86_DISABLE_EXITS capability can be turned on
+using the boolean module parameter mitigate_smt_rsb, e.g. ``kvm.mitigate_smt_rsb=1``.
diff --git a/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst b/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst
new file mode 100644
index 000000000..264bfa937
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/gather_data_sampling.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+GDS - Gather Data Sampling
+==========================
+
+Gather Data Sampling is a hardware vulnerability which allows unprivileged
+speculative access to data which was previously stored in vector registers.
+
+Problem
+-------
+When a gather instruction performs loads from memory, different data elements
+are merged into the destination vector register. However, when a gather
+instruction that is transiently executed encounters a fault, stale data from
+architectural or internal vector registers may get transiently forwarded to the
+destination vector register instead. This will allow a malicious attacker to
+infer stale data using typical side channel techniques like cache timing
+attacks. GDS is a purely sampling-based attack.
+
+The attacker uses gather instructions to infer the stale vector register data.
+The victim does not need to do anything special other than use the vector
+registers. The victim does not need to use gather instructions to be
+vulnerable.
+
+Because the buffers are shared between Hyper-Threads cross Hyper-Thread attacks
+are possible.
+
+Attack scenarios
+----------------
+Without mitigation, GDS can infer stale data across virtually all
+permission boundaries:
+
+	Non-enclaves can infer SGX enclave data
+	Userspace can infer kernel data
+	Guests can infer data from hosts
+	Guest can infer guest from other guests
+	Users can infer data from other users
+
+Because of this, it is important to ensure that the mitigation stays enabled in
+lower-privilege contexts like guests and when running outside SGX enclaves.
+
+The hardware enforces the mitigation for SGX. Likewise, VMMs should  ensure
+that guests are not allowed to disable the GDS mitigation. If a host erred and
+allowed this, a guest could theoretically disable GDS mitigation, mount an
+attack, and re-enable it.
+
+Mitigation mechanism
+--------------------
+This issue is mitigated in microcode. The microcode defines the following new
+bits:
+
+ ================================   ===   ============================
+ IA32_ARCH_CAPABILITIES[GDS_CTRL]   R/O   Enumerates GDS vulnerability
+                                          and mitigation support.
+ IA32_ARCH_CAPABILITIES[GDS_NO]     R/O   Processor is not vulnerable.
+ IA32_MCU_OPT_CTRL[GDS_MITG_DIS]    R/W   Disables the mitigation
+                                          0 by default.
+ IA32_MCU_OPT_CTRL[GDS_MITG_LOCK]   R/W   Locks GDS_MITG_DIS=0. Writes
+                                          to GDS_MITG_DIS are ignored
+                                          Can't be cleared once set.
+ ================================   ===   ============================
+
+GDS can also be mitigated on systems that don't have updated microcode by
+disabling AVX. This can be done by setting gather_data_sampling="force" or
+"clearcpuid=avx" on the kernel command-line.
+
+If used, these options will disable AVX use by turning off XSAVE YMM support.
+However, the processor will still enumerate AVX support.  Userspace that
+does not follow proper AVX enumeration to check both AVX *and* XSAVE YMM
+support will break.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The mitigation can be disabled by setting "gather_data_sampling=off" or
+"mitigations=off" on the kernel command line. Not specifying either will default
+to the mitigation being enabled. Specifying "gather_data_sampling=force" will
+use the microcode mitigation when available or disable AVX on affected systems
+where the microcode hasn't been updated to include the mitigation.
+
+GDS System Information
+------------------------
+The kernel provides vulnerability status information through sysfs. For
+GDS this can be accessed by the following sysfs file:
+
+/sys/devices/system/cpu/vulnerabilities/gather_data_sampling
+
+The possible values contained in this file are:
+
+ ============================== =============================================
+ Not affected                   Processor not vulnerable.
+ Vulnerable                     Processor vulnerable and mitigation disabled.
+ Vulnerable: No microcode       Processor vulnerable and microcode is missing
+                                mitigation.
+ Mitigation: AVX disabled,
+ no microcode                   Processor is vulnerable and microcode is missing
+                                mitigation. AVX disabled as mitigation.
+ Mitigation: Microcode          Processor is vulnerable and mitigation is in
+                                effect.
+ Mitigation: Microcode (locked) Processor is vulnerable and mitigation is in
+                                effect and cannot be disabled.
+ Unknown: Dependent on
+ hypervisor status              Running on a virtual guest processor that is
+                                affected but with no way to know if host
+                                processor is mitigated or vulnerable.
+ ============================== =============================================
+
+GDS Default mitigation
+----------------------
+The updated microcode will enable the mitigation by default. The kernel's
+default action is to leave the mitigation enabled.
diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst
new file mode 100644
index 000000000..55d747511
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/index.rst
@@ -0,0 +1,29 @@
+========================
+Hardware vulnerabilities
+========================
+
+This section describes CPU vulnerabilities and provides an overview of the
+possible mitigations along with guidance for selecting mitigations if they
+are configurable at compile, boot or run time.
+
+.. toctree::
+   :maxdepth: 1
+
+   attack_vector_controls
+   spectre
+   l1tf
+   mds
+   tsx_async_abort
+   multihit
+   special-register-buffer-data-sampling
+   core-scheduling
+   l1d_flush
+   processor_mmio_stale_data
+   cross-thread-rsb
+   srso
+   gather_data_sampling
+   reg-file-data-sampling
+   rsb
+   old_microcode
+   indirect-target-selection
+   vmscape
diff --git a/Documentation/admin-guide/hw-vuln/indirect-target-selection.rst b/Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
new file mode 100644
index 000000000..d9ca64108
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
@@ -0,0 +1,168 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Indirect Target Selection (ITS)
+===============================
+
+ITS is a vulnerability in some Intel CPUs that support Enhanced IBRS and were
+released before Alder Lake. ITS may allow an attacker to control the prediction
+of indirect branches and RETs located in the lower half of a cacheline.
+
+ITS is assigned CVE-2024-28956 with a CVSS score of 4.7 (Medium).
+
+Scope of Impact
+---------------
+- **eIBRS Guest/Host Isolation**: Indirect branches in KVM/kernel may still be
+  predicted with unintended target corresponding to a branch in the guest.
+
+- **Intra-Mode BTI**: In-kernel training such as through cBPF or other native
+  gadgets.
+
+- **Indirect Branch Prediction Barrier (IBPB)**: After an IBPB, indirect
+  branches may still be predicted with targets corresponding to direct branches
+  executed prior to the IBPB. This is fixed by the IPU 2025.1 microcode, which
+  should be available via distro updates. Alternatively microcode can be
+  obtained from Intel's github repository [#f1]_.
+
+Affected CPUs
+-------------
+Below is the list of ITS affected CPUs [#f2]_ [#f3]_:
+
+   ========================  ============  ====================  ===============
+   Common name               Family_Model  eIBRS                 Intra-mode BTI
+                                           Guest/Host Isolation
+   ========================  ============  ====================  ===============
+   SKYLAKE_X (step >= 6)     06_55H        Affected              Affected
+   ICELAKE_X                 06_6AH        Not affected          Affected
+   ICELAKE_D                 06_6CH        Not affected          Affected
+   ICELAKE_L                 06_7EH        Not affected          Affected
+   TIGERLAKE_L               06_8CH        Not affected          Affected
+   TIGERLAKE                 06_8DH        Not affected          Affected
+   KABYLAKE_L (step >= 12)   06_8EH        Affected              Affected
+   KABYLAKE (step >= 13)     06_9EH        Affected              Affected
+   COMETLAKE                 06_A5H        Affected              Affected
+   COMETLAKE_L               06_A6H        Affected              Affected
+   ROCKETLAKE                06_A7H        Not affected          Affected
+   ========================  ============  ====================  ===============
+
+- All affected CPUs enumerate Enhanced IBRS feature.
+- IBPB isolation is affected on all ITS affected CPUs, and need a microcode
+  update for mitigation.
+- None of the affected CPUs enumerate BHI_CTRL which was introduced in Golden
+  Cove (Alder Lake and Sapphire Rapids). This can help guests to determine the
+  host's affected status.
+- Intel Atom CPUs are not affected by ITS.
+
+Mitigation
+----------
+As only the indirect branches and RETs that have their last byte of instruction
+in the lower half of the cacheline are vulnerable to ITS, the basic idea behind
+the mitigation is to not allow indirect branches in the lower half.
+
+This is achieved by relying on existing retpoline support in the kernel, and in
+compilers. ITS-vulnerable retpoline sites are runtime patched to point to newly
+added ITS-safe thunks. These safe thunks consists of indirect branch in the
+second half of the cacheline. Not all retpoline sites are patched to thunks, if
+a retpoline site is evaluated to be ITS-safe, it is replaced with an inline
+indirect branch.
+
+Dynamic thunks
+~~~~~~~~~~~~~~
+From a dynamically allocated pool of safe-thunks, each vulnerable site is
+replaced with a new thunk, such that they get a unique address. This could
+improve the branch prediction accuracy. Also, it is a defense-in-depth measure
+against aliasing.
+
+Note, for simplicity, indirect branches in eBPF programs are always replaced
+with a jump to a static thunk in __x86_indirect_its_thunk_array. If required,
+in future this can be changed to use dynamic thunks.
+
+All vulnerable RETs are replaced with a static thunk, they do not use dynamic
+thunks. This is because RETs get their prediction from RSB mostly that does not
+depend on source address. RETs that underflow RSB may benefit from dynamic
+thunks. But, RETs significantly outnumber indirect branches, and any benefit
+from a unique source address could be outweighed by the increased icache
+footprint and iTLB pressure.
+
+Retpoline
+~~~~~~~~~
+Retpoline sequence also mitigates ITS-unsafe indirect branches. For this
+reason, when retpoline is enabled, ITS mitigation only relocates the RETs to
+safe thunks. Unless user requested the RSB-stuffing mitigation.
+
+RSB Stuffing
+~~~~~~~~~~~~
+RSB-stuffing via Call Depth Tracking is a mitigation for Retbleed RSB-underflow
+attacks. And it also mitigates RETs that are vulnerable to ITS.
+
+Mitigation in guests
+^^^^^^^^^^^^^^^^^^^^
+All guests deploy ITS mitigation by default, irrespective of eIBRS enumeration
+and Family/Model of the guest. This is because eIBRS feature could be hidden
+from a guest. One exception to this is when a guest enumerates BHI_DIS_S, which
+indicates that the guest is running on an unaffected host.
+
+To prevent guests from unnecessarily deploying the mitigation on unaffected
+platforms, Intel has defined ITS_NO bit(62) in MSR IA32_ARCH_CAPABILITIES. When
+a guest sees this bit set, it should not enumerate the ITS bug. Note, this bit
+is not set by any hardware, but is **intended for VMMs to synthesize** it for
+guests as per the host's affected status.
+
+Mitigation options
+^^^^^^^^^^^^^^^^^^
+The ITS mitigation can be controlled using the "indirect_target_selection"
+kernel parameter. The available options are:
+
+   ======== ===================================================================
+   on       (default)  Deploy the "Aligned branch/return thunks" mitigation.
+	    If spectre_v2 mitigation enables retpoline, aligned-thunks are only
+	    deployed for the affected RET instructions. Retpoline mitigates
+	    indirect branches.
+
+   off      Disable ITS mitigation.
+
+   vmexit   Equivalent to "=on" if the CPU is affected by guest/host isolation
+	    part of ITS. Otherwise, mitigation is not deployed. This option is
+	    useful when host userspace is not in the threat model, and only
+	    attacks from guest to host are considered.
+
+   stuff    Deploy RSB-fill mitigation when retpoline is also deployed.
+	    Otherwise, deploy the default mitigation. When retpoline mitigation
+	    is enabled, RSB-stuffing via Call-Depth-Tracking also mitigates
+	    ITS.
+
+   force    Force the ITS bug and deploy the default mitigation.
+   ======== ===================================================================
+
+Sysfs reporting
+---------------
+
+The sysfs file showing ITS mitigation status is:
+
+  /sys/devices/system/cpu/vulnerabilities/indirect_target_selection
+
+Note, microcode mitigation status is not reported in this file.
+
+The possible values in this file are:
+
+.. list-table::
+
+   * - Not affected
+     - The processor is not vulnerable.
+   * - Vulnerable
+     - System is vulnerable and no mitigation has been applied.
+   * - Vulnerable, KVM: Not affected
+     - System is vulnerable to intra-mode BTI, but not affected by eIBRS
+       guest/host isolation.
+   * - Mitigation: Aligned branch/return thunks
+     - The mitigation is enabled, affected indirect branches and RETs are
+       relocated to safe thunks.
+   * - Mitigation: Retpolines, Stuffing RSB
+     - The mitigation is enabled using retpoline and RSB stuffing.
+
+References
+----------
+.. [#f1] Microcode repository - https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files
+
+.. [#f2] Affected Processors list - https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html
+
+.. [#f3] Affected Processors list (machine readable) - https://github.com/intel/Intel-affected-processor-list
diff --git a/Documentation/admin-guide/hw-vuln/l1d_flush.rst b/Documentation/admin-guide/hw-vuln/l1d_flush.rst
new file mode 100644
index 000000000..35dc25159
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/l1d_flush.rst
@@ -0,0 +1,69 @@
+L1D Flushing
+============
+
+With an increasing number of vulnerabilities being reported around data
+leaks from the Level 1 Data cache (L1D) the kernel provides an opt-in
+mechanism to flush the L1D cache on context switch.
+
+This mechanism can be used to address e.g. CVE-2020-0550. For applications
+the mechanism keeps them safe from vulnerabilities, related to leaks
+(snooping of) from the L1D cache.
+
+
+Related CVEs
+------------
+The following CVEs can be addressed by this
+mechanism
+
+    =============       ========================     ==================
+    CVE-2020-0550       Improper Data Forwarding     OS related aspects
+    =============       ========================     ==================
+
+Usage Guidelines
+----------------
+
+Please see document: :ref:`Documentation/userspace-api/spec_ctrl.rst
+<set_spec_ctrl>` for details.
+
+**NOTE**: The feature is disabled by default, applications need to
+specifically opt into the feature to enable it.
+
+Mitigation
+----------
+
+When PR_SPEC_L1D_FLUSH is enabled for a task a flush of the L1D cache is
+performed when the task is scheduled out and the incoming task belongs to a
+different process and therefore to a different address space.
+
+If the underlying CPU supports L1D flushing in hardware, the hardware
+mechanism is used, software fallback for the mitigation, is not supported.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+The kernel command line allows to control the L1D flush mitigations at boot
+time with the option "l1d_flush=". The valid arguments for this option are:
+
+  ============  =============================================================
+  on            Enables the prctl interface, applications trying to use
+                the prctl() will fail with an error if l1d_flush is not
+                enabled
+  ============  =============================================================
+
+By default the mechanism is disabled.
+
+Limitations
+-----------
+
+The mechanism does not mitigate L1D data leaks between tasks belonging to
+different processes which are concurrently executing on sibling threads of
+a physical CPU core when SMT is enabled on the system.
+
+This can be addressed by controlled placement of processes on physical CPU
+cores or by disabling SMT. See the relevant chapter in the L1TF mitigation
+document: :ref:`Documentation/admin-guide/hw-vuln/l1tf.rst <smt_control>`.
+
+**NOTE** : The opt-in of a task for L1D flushing works only when the task's
+affinity is limited to cores running in non-SMT mode. If a task which
+requested L1D flushing is scheduled on a SMT-enabled core the kernel sends
+a SIGBUS to the task.
diff --git a/Documentation/admin-guide/hw-vuln/l1tf.rst b/Documentation/admin-guide/hw-vuln/l1tf.rst
new file mode 100644
index 000000000..3eeeb488d
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/l1tf.rst
@@ -0,0 +1,615 @@
+L1TF - L1 Terminal Fault
+========================
+
+L1 Terminal Fault is a hardware vulnerability which allows unprivileged
+speculative access to data which is available in the Level 1 Data Cache
+when the page table entry controlling the virtual address, which is used
+for the access, has the Present bit cleared or other reserved bits set.
+
+Affected processors
+-------------------
+
+This vulnerability affects a wide range of Intel processors. The
+vulnerability is not present on:
+
+   - Processors from AMD, Centaur and other non Intel vendors
+
+   - Older processor models, where the CPU family is < 6
+
+   - A range of Intel ATOM processors (Cedarview, Cloverview, Lincroft,
+     Penwell, Pineview, Silvermont, Airmont, Merrifield)
+
+   - The Intel XEON PHI family
+
+   - Intel processors which have the ARCH_CAP_RDCL_NO bit set in the
+     IA32_ARCH_CAPABILITIES MSR. If the bit is set the CPU is not affected
+     by the Meltdown vulnerability either. These CPUs should become
+     available by end of 2018.
+
+Whether a processor is affected or not can be read out from the L1TF
+vulnerability file in sysfs. See :ref:`l1tf_sys_info`.
+
+Related CVEs
+------------
+
+The following CVE entries are related to the L1TF vulnerability:
+
+   =============  =================  ==============================
+   CVE-2018-3615  L1 Terminal Fault  SGX related aspects
+   CVE-2018-3620  L1 Terminal Fault  OS, SMM related aspects
+   CVE-2018-3646  L1 Terminal Fault  Virtualization related aspects
+   =============  =================  ==============================
+
+Problem
+-------
+
+If an instruction accesses a virtual address for which the relevant page
+table entry (PTE) has the Present bit cleared or other reserved bits set,
+then speculative execution ignores the invalid PTE and loads the referenced
+data if it is present in the Level 1 Data Cache, as if the page referenced
+by the address bits in the PTE was still present and accessible.
+
+While this is a purely speculative mechanism and the instruction will raise
+a page fault when it is retired eventually, the pure act of loading the
+data and making it available to other speculative instructions opens up the
+opportunity for side channel attacks to unprivileged malicious code,
+similar to the Meltdown attack.
+
+While Meltdown breaks the user space to kernel space protection, L1TF
+allows to attack any physical memory address in the system and the attack
+works across all protection domains. It allows an attack of SGX and also
+works from inside virtual machines because the speculation bypasses the
+extended page table (EPT) protection mechanism.
+
+
+Attack scenarios
+----------------
+
+1. Malicious user space
+^^^^^^^^^^^^^^^^^^^^^^^
+
+   Operating Systems store arbitrary information in the address bits of a
+   PTE which is marked non present. This allows a malicious user space
+   application to attack the physical memory to which these PTEs resolve.
+   In some cases user-space can maliciously influence the information
+   encoded in the address bits of the PTE, thus making attacks more
+   deterministic and more practical.
+
+   The Linux kernel contains a mitigation for this attack vector, PTE
+   inversion, which is permanently enabled and has no performance
+   impact. The kernel ensures that the address bits of PTEs, which are not
+   marked present, never point to cacheable physical memory space.
+
+   A system with an up to date kernel is protected against attacks from
+   malicious user space applications.
+
+2. Malicious guest in a virtual machine
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The fact that L1TF breaks all domain protections allows malicious guest
+   OSes, which can control the PTEs directly, and malicious guest user
+   space applications, which run on an unprotected guest kernel lacking the
+   PTE inversion mitigation for L1TF, to attack physical host memory.
+
+   A special aspect of L1TF in the context of virtualization is symmetric
+   multi threading (SMT). The Intel implementation of SMT is called
+   HyperThreading. The fact that Hyperthreads on the affected processors
+   share the L1 Data Cache (L1D) is important for this. As the flaw allows
+   only to attack data which is present in L1D, a malicious guest running
+   on one Hyperthread can attack the data which is brought into the L1D by
+   the context which runs on the sibling Hyperthread of the same physical
+   core. This context can be host OS, host user space or a different guest.
+
+   If the processor does not support Extended Page Tables, the attack is
+   only possible, when the hypervisor does not sanitize the content of the
+   effective (shadow) page tables.
+
+   While solutions exist to mitigate these attack vectors fully, these
+   mitigations are not enabled by default in the Linux kernel because they
+   can affect performance significantly. The kernel provides several
+   mechanisms which can be utilized to address the problem depending on the
+   deployment scenario. The mitigations, their protection scope and impact
+   are described in the next sections.
+
+   The default mitigations and the rationale for choosing them are explained
+   at the end of this document. See :ref:`default_mitigations`.
+
+.. _l1tf_sys_info:
+
+L1TF system information
+-----------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current L1TF
+status of the system: whether the system is vulnerable, and which
+mitigations are active. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/l1tf
+
+The possible values in this file are:
+
+  ===========================   ===============================
+  'Not affected'		The processor is not vulnerable
+  'Mitigation: PTE Inversion'	The host protection is active
+  ===========================   ===============================
+
+If KVM/VMX is enabled and the processor is vulnerable then the following
+information is appended to the 'Mitigation: PTE Inversion' part:
+
+  - SMT status:
+
+    =====================  ================
+    'VMX: SMT vulnerable'  SMT is enabled
+    'VMX: SMT disabled'    SMT is disabled
+    =====================  ================
+
+  - L1D Flush mode:
+
+    ================================  ====================================
+    'L1D vulnerable'		      L1D flushing is disabled
+
+    'L1D conditional cache flushes'   L1D flush is conditionally enabled
+
+    'L1D cache flushes'		      L1D flush is unconditionally enabled
+    ================================  ====================================
+
+The resulting grade of protection is discussed in the following sections.
+
+
+Host mitigation mechanism
+-------------------------
+
+The kernel is unconditionally protected against L1TF attacks from malicious
+user space running on the host.
+
+
+Guest mitigation mechanisms
+---------------------------
+
+.. _l1d_flush:
+
+1. L1D flush on VMENTER
+^^^^^^^^^^^^^^^^^^^^^^^
+
+   To make sure that a guest cannot attack data which is present in the L1D
+   the hypervisor flushes the L1D before entering the guest.
+
+   Flushing the L1D evicts not only the data which should not be accessed
+   by a potentially malicious guest, it also flushes the guest
+   data. Flushing the L1D has a performance impact as the processor has to
+   bring the flushed guest data back into the L1D. Depending on the
+   frequency of VMEXIT/VMENTER and the type of computations in the guest
+   performance degradation in the range of 1% to 50% has been observed. For
+   scenarios where guest VMEXIT/VMENTER are rare the performance impact is
+   minimal. Virtio and mechanisms like posted interrupts are designed to
+   confine the VMEXITs to a bare minimum, but specific configurations and
+   application scenarios might still suffer from a high VMEXIT rate.
+
+   The kernel provides two L1D flush modes:
+    - conditional ('cond')
+    - unconditional ('always')
+
+   The conditional mode avoids L1D flushing after VMEXITs which execute
+   only audited code paths before the corresponding VMENTER. These code
+   paths have been verified that they cannot expose secrets or other
+   interesting data to an attacker, but they can leak information about the
+   address space layout of the hypervisor.
+
+   Unconditional mode flushes L1D on all VMENTER invocations and provides
+   maximum protection. It has a higher overhead than the conditional
+   mode. The overhead cannot be quantified correctly as it depends on the
+   workload scenario and the resulting number of VMEXITs.
+
+   The general recommendation is to enable L1D flush on VMENTER. The kernel
+   defaults to conditional mode on affected processors.
+
+   **Note**, that L1D flush does not prevent the SMT problem because the
+   sibling thread will also bring back its data into the L1D which makes it
+   attackable again.
+
+   L1D flush can be controlled by the administrator via the kernel command
+   line and sysfs control files. See :ref:`mitigation_control_command_line`
+   and :ref:`mitigation_control_kvm`.
+
+.. _guest_confinement:
+
+2. Guest VCPU confinement to dedicated physical cores
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   To address the SMT problem, it is possible to make a guest or a group of
+   guests affine to one or more physical cores. The proper mechanism for
+   that is to utilize exclusive cpusets to ensure that no other guest or
+   host tasks can run on these cores.
+
+   If only a single guest or related guests run on sibling SMT threads on
+   the same physical core then they can only attack their own memory and
+   restricted parts of the host memory.
+
+   Host memory is attackable, when one of the sibling SMT threads runs in
+   host OS (hypervisor) context and the other in guest context. The amount
+   of valuable information from the host OS context depends on the context
+   which the host OS executes, i.e. interrupts, soft interrupts and kernel
+   threads. The amount of valuable data from these contexts cannot be
+   declared as non-interesting for an attacker without deep inspection of
+   the code.
+
+   **Note**, that assigning guests to a fixed set of physical cores affects
+   the ability of the scheduler to do load balancing and might have
+   negative effects on CPU utilization depending on the hosting
+   scenario. Disabling SMT might be a viable alternative for particular
+   scenarios.
+
+   For further information about confining guests to a single or to a group
+   of cores consult the cpusets documentation:
+
+   https://www.kernel.org/doc/Documentation/admin-guide/cgroup-v1/cpusets.rst
+
+.. _interrupt_isolation:
+
+3. Interrupt affinity
+^^^^^^^^^^^^^^^^^^^^^
+
+   Interrupts can be made affine to logical CPUs. This is not universally
+   true because there are types of interrupts which are truly per CPU
+   interrupts, e.g. the local timer interrupt. Aside of that multi queue
+   devices affine their interrupts to single CPUs or groups of CPUs per
+   queue without allowing the administrator to control the affinities.
+
+   Moving the interrupts, which can be affinity controlled, away from CPUs
+   which run untrusted guests, reduces the attack vector space.
+
+   Whether the interrupts with are affine to CPUs, which run untrusted
+   guests, provide interesting data for an attacker depends on the system
+   configuration and the scenarios which run on the system. While for some
+   of the interrupts it can be assumed that they won't expose interesting
+   information beyond exposing hints about the host OS memory layout, there
+   is no way to make general assumptions.
+
+   Interrupt affinity can be controlled by the administrator via the
+   /proc/irq/$NR/smp_affinity[_list] files. Limited documentation is
+   available at:
+
+   https://www.kernel.org/doc/Documentation/core-api/irq/irq-affinity.rst
+
+.. _smt_control:
+
+4. SMT control
+^^^^^^^^^^^^^^
+
+   To prevent the SMT issues of L1TF it might be necessary to disable SMT
+   completely. Disabling SMT can have a significant performance impact, but
+   the impact depends on the hosting scenario and the type of workloads.
+   The impact of disabling SMT needs also to be weighted against the impact
+   of other mitigation solutions like confining guests to dedicated cores.
+
+   The kernel provides a sysfs interface to retrieve the status of SMT and
+   to control it. It also provides a kernel command line interface to
+   control SMT.
+
+   The kernel command line interface consists of the following options:
+
+     =========== ==========================================================
+     nosmt	 Affects the bring up of the secondary CPUs during boot. The
+		 kernel tries to bring all present CPUs online during the
+		 boot process. "nosmt" makes sure that from each physical
+		 core only one - the so called primary (hyper) thread is
+		 activated. Due to a design flaw of Intel processors related
+		 to Machine Check Exceptions the non primary siblings have
+		 to be brought up at least partially and are then shut down
+		 again.  "nosmt" can be undone via the sysfs interface.
+
+     nosmt=force Has the same effect as "nosmt" but it does not allow to
+		 undo the SMT disable via the sysfs interface.
+     =========== ==========================================================
+
+   The sysfs interface provides two files:
+
+   - /sys/devices/system/cpu/smt/control
+   - /sys/devices/system/cpu/smt/active
+
+   /sys/devices/system/cpu/smt/control:
+
+     This file allows to read out the SMT control state and provides the
+     ability to disable or (re)enable SMT. The possible states are:
+
+	==============  ===================================================
+	on		SMT is supported by the CPU and enabled. All
+			logical CPUs can be onlined and offlined without
+			restrictions.
+
+	off		SMT is supported by the CPU and disabled. Only
+			the so called primary SMT threads can be onlined
+			and offlined without restrictions. An attempt to
+			online a non-primary sibling is rejected
+
+	forceoff	Same as 'off' but the state cannot be controlled.
+			Attempts to write to the control file are rejected.
+
+	notsupported	The processor does not support SMT. It's therefore
+			not affected by the SMT implications of L1TF.
+			Attempts to write to the control file are rejected.
+	==============  ===================================================
+
+     The possible states which can be written into this file to control SMT
+     state are:
+
+     - on
+     - off
+     - forceoff
+
+   /sys/devices/system/cpu/smt/active:
+
+     This file reports whether SMT is enabled and active, i.e. if on any
+     physical core two or more sibling threads are online.
+
+   SMT control is also possible at boot time via the l1tf kernel command
+   line parameter in combination with L1D flush control. See
+   :ref:`mitigation_control_command_line`.
+
+5. Disabling EPT
+^^^^^^^^^^^^^^^^
+
+  Disabling EPT for virtual machines provides full mitigation for L1TF even
+  with SMT enabled, because the effective page tables for guests are
+  managed and sanitized by the hypervisor. Though disabling EPT has a
+  significant performance impact especially when the Meltdown mitigation
+  KPTI is enabled.
+
+  EPT can be disabled in the hypervisor via the 'kvm-intel.ept' parameter.
+
+There is ongoing research and development for new mitigation mechanisms to
+address the performance impact of disabling SMT or EPT.
+
+.. _mitigation_control_command_line:
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+The kernel command line allows to control the L1TF mitigations at boot
+time with the option "l1tf=". The valid arguments for this option are:
+
+  ============  =============================================================
+  full		Provides all available mitigations for the L1TF
+		vulnerability. Disables SMT and enables all mitigations in
+		the hypervisors, i.e. unconditional L1D flushing
+
+		SMT control and L1D flush control via the sysfs interface
+		is still possible after boot.  Hypervisors will issue a
+		warning when the first VM is started in a potentially
+		insecure configuration, i.e. SMT enabled or L1D flush
+		disabled.
+
+  full,force	Same as 'full', but disables SMT and L1D flush runtime
+		control. Implies the 'nosmt=force' command line option.
+		(i.e. sysfs control of SMT is disabled.)
+
+  flush		Leaves SMT enabled and enables the default hypervisor
+		mitigation, i.e. conditional L1D flushing
+
+		SMT control and L1D flush control via the sysfs interface
+		is still possible after boot.  Hypervisors will issue a
+		warning when the first VM is started in a potentially
+		insecure configuration, i.e. SMT enabled or L1D flush
+		disabled.
+
+  flush,nosmt	Disables SMT and enables the default hypervisor mitigation,
+		i.e. conditional L1D flushing.
+
+		SMT control and L1D flush control via the sysfs interface
+		is still possible after boot.  Hypervisors will issue a
+		warning when the first VM is started in a potentially
+		insecure configuration, i.e. SMT enabled or L1D flush
+		disabled.
+
+  flush,nowarn	Same as 'flush', but hypervisors will not warn when a VM is
+		started in a potentially insecure configuration.
+
+  off		Disables hypervisor mitigations and doesn't emit any
+		warnings.
+		It also drops the swap size and available RAM limit restrictions
+		on both hypervisor and bare metal.
+
+  ============  =============================================================
+
+The default is 'flush'. For details about L1D flushing see :ref:`l1d_flush`.
+
+
+.. _mitigation_control_kvm:
+
+Mitigation control for KVM - module parameter
+-------------------------------------------------------------
+
+The KVM hypervisor mitigation mechanism, flushing the L1D cache when
+entering a guest, can be controlled with a module parameter.
+
+The option/parameter is "kvm-intel.vmentry_l1d_flush=". It takes the
+following arguments:
+
+  ============  ==============================================================
+  always	L1D cache flush on every VMENTER.
+
+  cond		Flush L1D on VMENTER only when the code between VMEXIT and
+		VMENTER can leak host memory which is considered
+		interesting for an attacker. This still can leak host memory
+		which allows e.g. to determine the hosts address space layout.
+
+  never		Disables the mitigation
+  ============  ==============================================================
+
+The parameter can be provided on the kernel command line, as a module
+parameter when loading the modules and at runtime modified via the sysfs
+file:
+
+/sys/module/kvm_intel/parameters/vmentry_l1d_flush
+
+The default is 'cond'. If 'l1tf=full,force' is given on the kernel command
+line, then 'always' is enforced and the kvm-intel.vmentry_l1d_flush
+module parameter is ignored and writes to the sysfs file are rejected.
+
+.. _mitigation_selection:
+
+Mitigation selection guide
+--------------------------
+
+1. No virtualization in use
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The system is protected by the kernel unconditionally and no further
+   action is required.
+
+2. Virtualization with trusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   If the guest comes from a trusted source and the guest OS kernel is
+   guaranteed to have the L1TF mitigations in place the system is fully
+   protected against L1TF and no further action is required.
+
+   To avoid the overhead of the default L1D flushing on VMENTER the
+   administrator can disable the flushing via the kernel command line and
+   sysfs control files. See :ref:`mitigation_control_command_line` and
+   :ref:`mitigation_control_kvm`.
+
+
+3. Virtualization with untrusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+3.1. SMT not supported or disabled
+""""""""""""""""""""""""""""""""""
+
+  If SMT is not supported by the processor or disabled in the BIOS or by
+  the kernel, it's only required to enforce L1D flushing on VMENTER.
+
+  Conditional L1D flushing is the default behaviour and can be tuned. See
+  :ref:`mitigation_control_command_line` and :ref:`mitigation_control_kvm`.
+
+3.2. EPT not supported or disabled
+""""""""""""""""""""""""""""""""""
+
+  If EPT is not supported by the processor or disabled in the hypervisor,
+  the system is fully protected. SMT can stay enabled and L1D flushing on
+  VMENTER is not required.
+
+  EPT can be disabled in the hypervisor via the 'kvm-intel.ept' parameter.
+
+3.3. SMT and EPT supported and active
+"""""""""""""""""""""""""""""""""""""
+
+  If SMT and EPT are supported and active then various degrees of
+  mitigations can be employed:
+
+  - L1D flushing on VMENTER:
+
+    L1D flushing on VMENTER is the minimal protection requirement, but it
+    is only potent in combination with other mitigation methods.
+
+    Conditional L1D flushing is the default behaviour and can be tuned. See
+    :ref:`mitigation_control_command_line` and :ref:`mitigation_control_kvm`.
+
+  - Guest confinement:
+
+    Confinement of guests to a single or a group of physical cores which
+    are not running any other processes, can reduce the attack surface
+    significantly, but interrupts, soft interrupts and kernel threads can
+    still expose valuable data to a potential attacker. See
+    :ref:`guest_confinement`.
+
+  - Interrupt isolation:
+
+    Isolating the guest CPUs from interrupts can reduce the attack surface
+    further, but still allows a malicious guest to explore a limited amount
+    of host physical memory. This can at least be used to gain knowledge
+    about the host address space layout. The interrupts which have a fixed
+    affinity to the CPUs which run the untrusted guests can depending on
+    the scenario still trigger soft interrupts and schedule kernel threads
+    which might expose valuable information. See
+    :ref:`interrupt_isolation`.
+
+The above three mitigation methods combined can provide protection to a
+certain degree, but the risk of the remaining attack surface has to be
+carefully analyzed. For full protection the following methods are
+available:
+
+  - Disabling SMT:
+
+    Disabling SMT and enforcing the L1D flushing provides the maximum
+    amount of protection. This mitigation is not depending on any of the
+    above mitigation methods.
+
+    SMT control and L1D flushing can be tuned by the command line
+    parameters 'nosmt', 'l1tf', 'kvm-intel.vmentry_l1d_flush' and at run
+    time with the matching sysfs control files. See :ref:`smt_control`,
+    :ref:`mitigation_control_command_line` and
+    :ref:`mitigation_control_kvm`.
+
+  - Disabling EPT:
+
+    Disabling EPT provides the maximum amount of protection as well. It is
+    not depending on any of the above mitigation methods. SMT can stay
+    enabled and L1D flushing is not required, but the performance impact is
+    significant.
+
+    EPT can be disabled in the hypervisor via the 'kvm-intel.ept'
+    parameter.
+
+3.4. Nested virtual machines
+""""""""""""""""""""""""""""
+
+When nested virtualization is in use, three operating systems are involved:
+the bare metal hypervisor, the nested hypervisor and the nested virtual
+machine.  VMENTER operations from the nested hypervisor into the nested
+guest will always be processed by the bare metal hypervisor. If KVM is the
+bare metal hypervisor it will:
+
+ - Flush the L1D cache on every switch from the nested hypervisor to the
+   nested virtual machine, so that the nested hypervisor's secrets are not
+   exposed to the nested virtual machine;
+
+ - Flush the L1D cache on every switch from the nested virtual machine to
+   the nested hypervisor; this is a complex operation, and flushing the L1D
+   cache avoids that the bare metal hypervisor's secrets are exposed to the
+   nested virtual machine;
+
+ - Instruct the nested hypervisor to not perform any L1D cache flush. This
+   is an optimization to avoid double L1D flushing.
+
+
+.. _default_mitigations:
+
+Default mitigations
+-------------------
+
+  The kernel default mitigations for vulnerable processors are:
+
+  - PTE inversion to protect against malicious user space. This is done
+    unconditionally and cannot be controlled. The swap storage is limited
+    to ~16TB.
+
+  - L1D conditional flushing on VMENTER when EPT is enabled for
+    a guest.
+
+  The kernel does not by default enforce the disabling of SMT, which leaves
+  SMT systems vulnerable when running untrusted guests with EPT enabled.
+
+  The rationale for this choice is:
+
+  - Force disabling SMT can break existing setups, especially with
+    unattended updates.
+
+  - If regular users run untrusted guests on their machine, then L1TF is
+    just an add on to other malware which might be embedded in an untrusted
+    guest, e.g. spam-bots or attacks on the local network.
+
+    There is no technical way to prevent a user from running untrusted code
+    on their machines blindly.
+
+  - It's technically extremely unlikely and from today's knowledge even
+    impossible that L1TF can be exploited via the most popular attack
+    mechanisms like JavaScript because these mechanisms have no way to
+    control PTEs. If this would be possible and not other mitigation would
+    be possible, then the default might be different.
+
+  - The administrators of cloud and hosting setups have to carefully
+    analyze the risk for their scenarios and make the appropriate
+    mitigation choices, which might even vary across their deployed
+    machines and also result in other changes of their overall setup.
+    There is no way for the kernel to provide a sensible default for this
+    kind of scenarios.
diff --git a/Documentation/admin-guide/hw-vuln/mds.rst b/Documentation/admin-guide/hw-vuln/mds.rst
new file mode 100644
index 000000000..754679db0
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/mds.rst
@@ -0,0 +1,303 @@
+MDS - Microarchitectural Data Sampling
+======================================
+
+Microarchitectural Data Sampling is a hardware vulnerability which allows
+unprivileged speculative access to data which is available in various CPU
+internal buffers.
+
+Affected processors
+-------------------
+
+This vulnerability affects a wide range of Intel processors. The
+vulnerability is not present on:
+
+   - Processors from AMD, Centaur and other non Intel vendors
+
+   - Older processor models, where the CPU family is < 6
+
+   - Some Atoms (Bonnell, Saltwell, Goldmont, GoldmontPlus)
+
+   - Intel processors which have the ARCH_CAP_MDS_NO bit set in the
+     IA32_ARCH_CAPABILITIES MSR.
+
+Whether a processor is affected or not can be read out from the MDS
+vulnerability file in sysfs. See :ref:`mds_sys_info`.
+
+Not all processors are affected by all variants of MDS, but the mitigation
+is identical for all of them so the kernel treats them as a single
+vulnerability.
+
+Related CVEs
+------------
+
+The following CVE entries are related to the MDS vulnerability:
+
+   ==============  =====  ===================================================
+   CVE-2018-12126  MSBDS  Microarchitectural Store Buffer Data Sampling
+   CVE-2018-12130  MFBDS  Microarchitectural Fill Buffer Data Sampling
+   CVE-2018-12127  MLPDS  Microarchitectural Load Port Data Sampling
+   CVE-2019-11091  MDSUM  Microarchitectural Data Sampling Uncacheable Memory
+   ==============  =====  ===================================================
+
+Problem
+-------
+
+When performing store, load, L1 refill operations, processors write data
+into temporary microarchitectural structures (buffers). The data in the
+buffer can be forwarded to load operations as an optimization.
+
+Under certain conditions, usually a fault/assist caused by a load
+operation, data unrelated to the load memory address can be speculatively
+forwarded from the buffers. Because the load operation causes a fault or
+assist and its result will be discarded, the forwarded data will not cause
+incorrect program execution or state changes. But a malicious operation
+may be able to forward this speculative data to a disclosure gadget which
+allows in turn to infer the value via a cache side channel attack.
+
+Because the buffers are potentially shared between Hyper-Threads cross
+Hyper-Thread attacks are possible.
+
+Deeper technical information is available in the MDS specific x86
+architecture section: :ref:`Documentation/arch/x86/mds.rst <mds>`.
+
+
+Attack scenarios
+----------------
+
+Attacks against the MDS vulnerabilities can be mounted from malicious non-
+privileged user space applications running on hosts or guest. Malicious
+guest OSes can obviously mount attacks as well.
+
+Contrary to other speculation based vulnerabilities the MDS vulnerability
+does not allow the attacker to control the memory target address. As a
+consequence the attacks are purely sampling based, but as demonstrated with
+the TLBleed attack samples can be postprocessed successfully.
+
+Web-Browsers
+^^^^^^^^^^^^
+
+  It's unclear whether attacks through Web-Browsers are possible at
+  all. The exploitation through Java-Script is considered very unlikely,
+  but other widely used web technologies like Webassembly could possibly be
+  abused.
+
+
+.. _mds_sys_info:
+
+MDS system information
+-----------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current MDS
+status of the system: whether the system is vulnerable, and which
+mitigations are active. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/mds
+
+The possible values in this file are:
+
+  .. list-table::
+
+     * - 'Not affected'
+       - The processor is not vulnerable
+     * - 'Vulnerable'
+       - The processor is vulnerable, but no mitigation enabled
+     * - 'Vulnerable: Clear CPU buffers attempted, no microcode'
+       - The processor is vulnerable but microcode is not updated. The
+         mitigation is enabled on a best effort basis.
+
+         If the processor is vulnerable but the availability of the microcode
+         based mitigation mechanism is not advertised via CPUID, the kernel
+         selects a best effort mitigation mode. This mode invokes the mitigation
+         instructions without a guarantee that they clear the CPU buffers.
+
+         This is done to address virtualization scenarios where the host has the
+         microcode update applied, but the hypervisor is not yet updated to
+         expose the CPUID to the guest. If the host has updated microcode the
+         protection takes effect; otherwise a few CPU cycles are wasted
+         pointlessly.
+     * - 'Mitigation: Clear CPU buffers'
+       - The processor is vulnerable and the CPU buffer clearing mitigation is
+         enabled.
+
+If the processor is vulnerable then the following information is appended
+to the above information:
+
+    ========================  ============================================
+    'SMT vulnerable'          SMT is enabled
+    'SMT mitigated'           SMT is enabled and mitigated
+    'SMT disabled'            SMT is disabled
+    'SMT Host state unknown'  Kernel runs in a VM, Host SMT state unknown
+    ========================  ============================================
+
+Mitigation mechanism
+-------------------------
+
+The kernel detects the affected CPUs and the presence of the microcode
+which is required.
+
+If a CPU is affected and the microcode is available, then the kernel
+enables the mitigation by default. The mitigation can be controlled at boot
+time via a kernel command line option. See
+:ref:`mds_mitigation_control_command_line`.
+
+.. _cpu_buffer_clear:
+
+CPU buffer clearing
+^^^^^^^^^^^^^^^^^^^
+
+  The mitigation for MDS clears the affected CPU buffers on return to user
+  space and when entering a guest.
+
+  If SMT is enabled it also clears the buffers on idle entry when the CPU
+  is only affected by MSBDS and not any other MDS variant, because the
+  other variants cannot be protected against cross Hyper-Thread attacks.
+
+  For CPUs which are only affected by MSBDS the user space, guest and idle
+  transition mitigations are sufficient and SMT is not affected.
+
+.. _virt_mechanism:
+
+Virtualization mitigation
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  The protection for host to guest transition depends on the L1TF
+  vulnerability of the CPU:
+
+  - CPU is affected by L1TF:
+
+    If the L1D flush mitigation is enabled and up to date microcode is
+    available, the L1D flush mitigation is automatically protecting the
+    guest transition.
+
+    If the L1D flush mitigation is disabled then the MDS mitigation is
+    invoked explicit when the host MDS mitigation is enabled.
+
+    For details on L1TF and virtualization see:
+    :ref:`Documentation/admin-guide/hw-vuln//l1tf.rst <mitigation_control_kvm>`.
+
+  - CPU is not affected by L1TF:
+
+    CPU buffers are flushed before entering the guest when the host MDS
+    mitigation is enabled.
+
+  The resulting MDS protection matrix for the host to guest transition:
+
+  ============ ===== ============= ============ =================
+   L1TF         MDS   VMX-L1FLUSH   Host MDS     MDS-State
+
+   Don't care   No    Don't care    N/A          Not affected
+
+   Yes          Yes   Disabled      Off          Vulnerable
+
+   Yes          Yes   Disabled      Full         Mitigated
+
+   Yes          Yes   Enabled       Don't care   Mitigated
+
+   No           Yes   N/A           Off          Vulnerable
+
+   No           Yes   N/A           Full         Mitigated
+  ============ ===== ============= ============ =================
+
+  This only covers the host to guest transition, i.e. prevents leakage from
+  host to guest, but does not protect the guest internally. Guests need to
+  have their own protections.
+
+.. _xeon_phi:
+
+XEON PHI specific considerations
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  The XEON PHI processor family is affected by MSBDS which can be exploited
+  cross Hyper-Threads when entering idle states. Some XEON PHI variants allow
+  to use MWAIT in user space (Ring 3) which opens an potential attack vector
+  for malicious user space. The exposure can be disabled on the kernel
+  command line with the 'ring3mwait=disable' command line option.
+
+  XEON PHI is not affected by the other MDS variants and MSBDS is mitigated
+  before the CPU enters an idle state. As XEON PHI is not affected by L1TF
+  either disabling SMT is not required for full protection.
+
+.. _mds_smt_control:
+
+SMT control
+^^^^^^^^^^^
+
+  All MDS variants except MSBDS can be attacked cross Hyper-Threads. That
+  means on CPUs which are affected by MFBDS or MLPDS it is necessary to
+  disable SMT for full protection. These are most of the affected CPUs; the
+  exception is XEON PHI, see :ref:`xeon_phi`.
+
+  Disabling SMT can have a significant performance impact, but the impact
+  depends on the type of workloads.
+
+  See the relevant chapter in the L1TF mitigation documentation for details:
+  :ref:`Documentation/admin-guide/hw-vuln/l1tf.rst <smt_control>`.
+
+
+.. _mds_mitigation_control_command_line:
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+The kernel command line allows to control the MDS mitigations at boot
+time with the option "mds=". The valid arguments for this option are:
+
+  ============  =============================================================
+  full		If the CPU is vulnerable, enable all available mitigations
+		for the MDS vulnerability, CPU buffer clearing on exit to
+		userspace and when entering a VM. Idle transitions are
+		protected as well if SMT is enabled.
+
+		It does not automatically disable SMT.
+
+  full,nosmt	The same as mds=full, with SMT disabled on vulnerable
+		CPUs.  This is the complete mitigation.
+
+  off		Disables MDS mitigations completely.
+
+  ============  =============================================================
+
+Not specifying this option is equivalent to "mds=full". For processors
+that are affected by both TAA (TSX Asynchronous Abort) and MDS,
+specifying just "mds=off" without an accompanying "tsx_async_abort=off"
+will have no effect as the same mitigation is used for both
+vulnerabilities.
+
+Mitigation selection guide
+--------------------------
+
+1. Trusted userspace
+^^^^^^^^^^^^^^^^^^^^
+
+   If all userspace applications are from a trusted source and do not
+   execute untrusted code which is supplied externally, then the mitigation
+   can be disabled.
+
+
+2. Virtualization with trusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The same considerations as above versus trusted user space apply.
+
+3. Virtualization with untrusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The protection depends on the state of the L1TF mitigations.
+   See :ref:`virt_mechanism`.
+
+   If the MDS mitigation is enabled and SMT is disabled, guest to host and
+   guest to guest attacks are prevented.
+
+.. _mds_default_mitigations:
+
+Default mitigations
+-------------------
+
+  The kernel default mitigations for vulnerable processors are:
+
+  - Enable CPU buffer clearing
+
+  The kernel does not by default enforce the disabling of SMT, which leaves
+  SMT systems vulnerable when running untrusted code. The same rationale as
+  for L1TF applies.
+  See :ref:`Documentation/admin-guide/hw-vuln//l1tf.rst <default_mitigations>`.
diff --git a/Documentation/admin-guide/hw-vuln/multihit.rst b/Documentation/admin-guide/hw-vuln/multihit.rst
new file mode 100644
index 000000000..140e4cec3
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/multihit.rst
@@ -0,0 +1,167 @@
+iTLB multihit
+=============
+
+iTLB multihit is an erratum where some processors may incur a machine check
+error, possibly resulting in an unrecoverable CPU lockup, when an
+instruction fetch hits multiple entries in the instruction TLB. This can
+occur when the page size is changed along with either the physical address
+or cache type. A malicious guest running on a virtualized system can
+exploit this erratum to perform a denial of service attack.
+
+
+Affected processors
+-------------------
+
+Variations of this erratum are present on most Intel Core and Xeon processor
+models. The erratum is not present on:
+
+   - non-Intel processors
+
+   - Some Atoms (Airmont, Bonnell, Goldmont, GoldmontPlus, Saltwell, Silvermont)
+
+   - Intel processors that have the PSCHANGE_MC_NO bit set in the
+     IA32_ARCH_CAPABILITIES MSR.
+
+
+Related CVEs
+------------
+
+The following CVE entry is related to this issue:
+
+   ==============  =================================================
+   CVE-2018-12207  Machine Check Error Avoidance on Page Size Change
+   ==============  =================================================
+
+
+Problem
+-------
+
+Privileged software, including OS and virtual machine managers (VMM), are in
+charge of memory management. A key component in memory management is the control
+of the page tables. Modern processors use virtual memory, a technique that creates
+the illusion of a very large memory for processors. This virtual space is split
+into pages of a given size. Page tables translate virtual addresses to physical
+addresses.
+
+To reduce latency when performing a virtual to physical address translation,
+processors include a structure, called TLB, that caches recent translations.
+There are separate TLBs for instruction (iTLB) and data (dTLB).
+
+Under this errata, instructions are fetched from a linear address translated
+using a 4 KB translation cached in the iTLB. Privileged software modifies the
+paging structure so that the same linear address using large page size (2 MB, 4
+MB, 1 GB) with a different physical address or memory type.  After the page
+structure modification but before the software invalidates any iTLB entries for
+the linear address, a code fetch that happens on the same linear address may
+cause a machine-check error which can result in a system hang or shutdown.
+
+
+Attack scenarios
+----------------
+
+Attacks against the iTLB multihit erratum can be mounted from malicious
+guests in a virtualized system.
+
+
+iTLB multihit system information
+--------------------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current iTLB
+multihit status of the system:whether the system is vulnerable and which
+mitigations are active. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/itlb_multihit
+
+The possible values in this file are:
+
+.. list-table::
+
+     * - Not affected
+       - The processor is not vulnerable.
+     * - KVM: Mitigation: Split huge pages
+       - Software changes mitigate this issue.
+     * - KVM: Mitigation: VMX unsupported
+       - KVM is not vulnerable because Virtual Machine Extensions (VMX) is not supported.
+     * - KVM: Mitigation: VMX disabled
+       - KVM is not vulnerable because Virtual Machine Extensions (VMX) is disabled.
+     * - KVM: Vulnerable
+       - The processor is vulnerable, but no mitigation enabled
+
+
+Enumeration of the erratum
+--------------------------------
+
+A new bit has been allocated in the IA32_ARCH_CAPABILITIES (PSCHANGE_MC_NO) msr
+and will be set on CPU's which are mitigated against this issue.
+
+   =======================================   ===========   ===============================
+   IA32_ARCH_CAPABILITIES MSR                Not present   Possibly vulnerable,check model
+   IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO]    '0'           Likely vulnerable,check model
+   IA32_ARCH_CAPABILITIES[PSCHANGE_MC_NO]    '1'           Not vulnerable
+   =======================================   ===========   ===============================
+
+
+Mitigation mechanism
+-------------------------
+
+This erratum can be mitigated by restricting the use of large page sizes to
+non-executable pages.  This forces all iTLB entries to be 4K, and removes
+the possibility of multiple hits.
+
+In order to mitigate the vulnerability, KVM initially marks all huge pages
+as non-executable. If the guest attempts to execute in one of those pages,
+the page is broken down into 4K pages, which are then marked executable.
+
+If EPT is disabled or not available on the host, KVM is in control of TLB
+flushes and the problematic situation cannot happen.  However, the shadow
+EPT paging mechanism used by nested virtualization is vulnerable, because
+the nested guest can trigger multiple iTLB hits by modifying its own
+(non-nested) page tables.  For simplicity, KVM will make large pages
+non-executable in all shadow paging modes.
+
+Mitigation control on the kernel command line and KVM - module parameter
+------------------------------------------------------------------------
+
+The KVM hypervisor mitigation mechanism for marking huge pages as
+non-executable can be controlled with a module parameter "nx_huge_pages=".
+The kernel command line allows to control the iTLB multihit mitigations at
+boot time with the option "kvm.nx_huge_pages=".
+
+The valid arguments for these options are:
+
+  ==========  ================================================================
+  force       Mitigation is enabled. In this case, the mitigation implements
+              non-executable huge pages in Linux kernel KVM module. All huge
+              pages in the EPT are marked as non-executable.
+              If a guest attempts to execute in one of those pages, the page is
+              broken down into 4K pages, which are then marked executable.
+
+  off	      Mitigation is disabled.
+
+  auto        Enable mitigation only if the platform is affected and the kernel
+              was not booted with the "mitigations=off" command line parameter.
+	      This is the default option.
+  ==========  ================================================================
+
+
+Mitigation selection guide
+--------------------------
+
+1. No virtualization in use
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The system is protected by the kernel unconditionally and no further
+   action is required.
+
+2. Virtualization with trusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   If the guest comes from a trusted source, you may assume that the guest will
+   not attempt to maliciously exploit these errata and no further action is
+   required.
+
+3. Virtualization with untrusted guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   If the guest comes from an untrusted source, the guest host kernel will need
+   to apply iTLB multihit mitigation via the kernel command line or kvm
+   module parameter.
diff --git a/Documentation/admin-guide/hw-vuln/old_microcode.rst b/Documentation/admin-guide/hw-vuln/old_microcode.rst
new file mode 100644
index 000000000..6ded8f86b
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/old_microcode.rst
@@ -0,0 +1,21 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Old Microcode
+=============
+
+The kernel keeps a table of released microcode. Systems that had
+microcode older than this at boot will say "Vulnerable".  This means
+that the system was vulnerable to some known CPU issue. It could be
+security or functional, the kernel does not know or care.
+
+You should update the CPU microcode to mitigate any exposure. This is
+usually accomplished by updating the files in
+/lib/firmware/intel-ucode/ via normal distribution updates. Intel also
+distributes these files in a github repo:
+
+	https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files.git
+
+Just like all the other hardware vulnerabilities, exposure is
+determined at boot. Runtime microcode updates do not change the status
+of this vulnerability.
diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
new file mode 100644
index 000000000..6dba18dbb
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
@@ -0,0 +1,269 @@
+=========================================
+Processor MMIO Stale Data Vulnerabilities
+=========================================
+
+Processor MMIO Stale Data Vulnerabilities are a class of memory-mapped I/O
+(MMIO) vulnerabilities that can expose data. The sequences of operations for
+exposing data range from simple to very complex. Because most of the
+vulnerabilities require the attacker to have access to MMIO, many environments
+are not affected. System environments using virtualization where MMIO access is
+provided to untrusted guests may need mitigation. These vulnerabilities are
+not transient execution attacks. However, these vulnerabilities may propagate
+stale data into core fill buffers where the data can subsequently be inferred
+by an unmitigated transient execution attack. Mitigation for these
+vulnerabilities includes a combination of microcode update and software
+changes, depending on the platform and usage model. Some of these mitigations
+are similar to those used to mitigate Microarchitectural Data Sampling (MDS) or
+those used to mitigate Special Register Buffer Data Sampling (SRBDS).
+
+Data Propagators
+================
+Propagators are operations that result in stale data being copied or moved from
+one microarchitectural buffer or register to another. Processor MMIO Stale Data
+Vulnerabilities are operations that may result in stale data being directly
+read into an architectural, software-visible state or sampled from a buffer or
+register.
+
+Fill Buffer Stale Data Propagator (FBSDP)
+-----------------------------------------
+Stale data may propagate from fill buffers (FB) into the non-coherent portion
+of the uncore on some non-coherent writes. Fill buffer propagation by itself
+does not make stale data architecturally visible. Stale data must be propagated
+to a location where it is subject to reading or sampling.
+
+Sideband Stale Data Propagator (SSDP)
+-------------------------------------
+The sideband stale data propagator (SSDP) is limited to the client (including
+Intel Xeon server E3) uncore implementation. The sideband response buffer is
+shared by all client cores. For non-coherent reads that go to sideband
+destinations, the uncore logic returns 64 bytes of data to the core, including
+both requested data and unrequested stale data, from a transaction buffer and
+the sideband response buffer. As a result, stale data from the sideband
+response and transaction buffers may now reside in a core fill buffer.
+
+Primary Stale Data Propagator (PSDP)
+------------------------------------
+The primary stale data propagator (PSDP) is limited to the client (including
+Intel Xeon server E3) uncore implementation. Similar to the sideband response
+buffer, the primary response buffer is shared by all client cores. For some
+processors, MMIO primary reads will return 64 bytes of data to the core fill
+buffer including both requested data and unrequested stale data. This is
+similar to the sideband stale data propagator.
+
+Vulnerabilities
+===============
+Device Register Partial Write (DRPW) (CVE-2022-21166)
+-----------------------------------------------------
+Some endpoint MMIO registers incorrectly handle writes that are smaller than
+the register size. Instead of aborting the write or only copying the correct
+subset of bytes (for example, 2 bytes for a 2-byte write), more bytes than
+specified by the write transaction may be written to the register. On
+processors affected by FBSDP, this may expose stale data from the fill buffers
+of the core that created the write transaction.
+
+Shared Buffers Data Sampling (SBDS) (CVE-2022-21125)
+----------------------------------------------------
+After propagators may have moved data around the uncore and copied stale data
+into client core fill buffers, processors affected by MFBDS can leak data from
+the fill buffer. It is limited to the client (including Intel Xeon server E3)
+uncore implementation.
+
+Shared Buffers Data Read (SBDR) (CVE-2022-21123)
+------------------------------------------------
+It is similar to Shared Buffer Data Sampling (SBDS) except that the data is
+directly read into the architectural software-visible state. It is limited to
+the client (including Intel Xeon server E3) uncore implementation.
+
+Affected Processors
+===================
+Not all the CPUs are affected by all the variants. For instance, most
+processors for the server market (excluding Intel Xeon E3 processors) are
+impacted by only Device Register Partial Write (DRPW).
+
+Below is the list of affected Intel processors [#f1]_:
+
+   ===================  ============  =========
+   Common name          Family_Model  Steppings
+   ===================  ============  =========
+   HASWELL_X            06_3FH        2,4
+   SKYLAKE_L            06_4EH        3
+   BROADWELL_X          06_4FH        All
+   SKYLAKE_X            06_55H        3,4,6,7,11
+   BROADWELL_D          06_56H        3,4,5
+   SKYLAKE              06_5EH        3
+   ICELAKE_X            06_6AH        4,5,6
+   ICELAKE_D            06_6CH        1
+   ICELAKE_L            06_7EH        5
+   ATOM_TREMONT_D       06_86H        All
+   LAKEFIELD            06_8AH        1
+   KABYLAKE_L           06_8EH        9 to 12
+   ATOM_TREMONT         06_96H        1
+   ATOM_TREMONT_L       06_9CH        0
+   KABYLAKE             06_9EH        9 to 13
+   COMETLAKE            06_A5H        2,3,5
+   COMETLAKE_L          06_A6H        0,1
+   ROCKETLAKE           06_A7H        1
+   ===================  ============  =========
+
+If a CPU is in the affected processor list, but not affected by a variant, it
+is indicated by new bits in MSR IA32_ARCH_CAPABILITIES. As described in a later
+section, mitigation largely remains the same for all the variants, i.e. to
+clear the CPU fill buffers via VERW instruction.
+
+New bits in MSRs
+================
+Newer processors and microcode update on existing affected processors added new
+bits to IA32_ARCH_CAPABILITIES MSR. These bits can be used to enumerate
+specific variants of Processor MMIO Stale Data vulnerabilities and mitigation
+capability.
+
+MSR IA32_ARCH_CAPABILITIES
+--------------------------
+Bit 13 - SBDR_SSDP_NO - When set, processor is not affected by either the
+	 Shared Buffers Data Read (SBDR) vulnerability or the sideband stale
+	 data propagator (SSDP).
+Bit 14 - FBSDP_NO - When set, processor is not affected by the Fill Buffer
+	 Stale Data Propagator (FBSDP).
+Bit 15 - PSDP_NO - When set, processor is not affected by Primary Stale Data
+	 Propagator (PSDP).
+Bit 17 - FB_CLEAR - When set, VERW instruction will overwrite CPU fill buffer
+	 values as part of MD_CLEAR operations. Processors that do not
+	 enumerate MDS_NO (meaning they are affected by MDS) but that do
+	 enumerate support for both L1D_FLUSH and MD_CLEAR implicitly enumerate
+	 FB_CLEAR as part of their MD_CLEAR support.
+Bit 18 - FB_CLEAR_CTRL - Processor supports read and write to MSR
+	 IA32_MCU_OPT_CTRL[FB_CLEAR_DIS]. On such processors, the FB_CLEAR_DIS
+	 bit can be set to cause the VERW instruction to not perform the
+	 FB_CLEAR action. Not all processors that support FB_CLEAR will support
+	 FB_CLEAR_CTRL.
+
+MSR IA32_MCU_OPT_CTRL
+---------------------
+Bit 3 - FB_CLEAR_DIS - When set, VERW instruction does not perform the FB_CLEAR
+action. This may be useful to reduce the performance impact of FB_CLEAR in
+cases where system software deems it warranted (for example, when performance
+is more critical, or the untrusted software has no MMIO access). Note that
+FB_CLEAR_DIS has no impact on enumeration (for example, it does not change
+FB_CLEAR or MD_CLEAR enumeration) and it may not be supported on all processors
+that enumerate FB_CLEAR.
+
+Mitigation
+==========
+Like MDS, all variants of Processor MMIO Stale Data vulnerabilities  have the
+same mitigation strategy to force the CPU to clear the affected buffers before
+an attacker can extract the secrets.
+
+This is achieved by using the otherwise unused and obsolete VERW instruction in
+combination with a microcode update. The microcode clears the affected CPU
+buffers when the VERW instruction is executed.
+
+Kernel does the buffer clearing with x86_clear_cpu_buffers().
+
+On MDS affected CPUs, the kernel already invokes CPU buffer clear on
+kernel/userspace, hypervisor/guest and C-state (idle) transitions. No
+additional mitigation is needed on such CPUs.
+
+For CPUs not affected by MDS or TAA, mitigation is needed only for the attacker
+with MMIO capability. Therefore, VERW is not required for kernel/userspace. For
+virtualization case, VERW is only needed at VMENTER for a guest with MMIO
+capability.
+
+Mitigation points
+-----------------
+Return to user space
+^^^^^^^^^^^^^^^^^^^^
+Same mitigation as MDS when affected by MDS/TAA, otherwise no mitigation
+needed.
+
+C-State transition
+^^^^^^^^^^^^^^^^^^
+Control register writes by CPU during C-state transition can propagate data
+from fill buffer to uncore buffers. Execute VERW before C-state transition to
+clear CPU fill buffers.
+
+Guest entry point
+^^^^^^^^^^^^^^^^^
+Same mitigation as MDS when processor is also affected by MDS/TAA, otherwise
+execute VERW at VMENTER only for MMIO capable guests. On CPUs not affected by
+MDS/TAA, guest without MMIO access cannot extract secrets using Processor MMIO
+Stale Data vulnerabilities, so there is no need to execute VERW for such guests.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The kernel command line allows to control the Processor MMIO Stale Data
+mitigations at boot time with the option "mmio_stale_data=". The valid
+arguments for this option are:
+
+  ==========  =================================================================
+  full        If the CPU is vulnerable, enable mitigation; CPU buffer clearing
+              on exit to userspace and when entering a VM. Idle transitions are
+              protected as well. It does not automatically disable SMT.
+  full,nosmt  Same as full, with SMT disabled on vulnerable CPUs. This is the
+              complete mitigation.
+  off         Disables mitigation completely.
+  ==========  =================================================================
+
+If the CPU is affected and mmio_stale_data=off is not supplied on the kernel
+command line, then the kernel selects the appropriate mitigation.
+
+Mitigation status information
+-----------------------------
+The Linux kernel provides a sysfs interface to enumerate the current
+vulnerability status of the system: whether the system is vulnerable, and
+which mitigations are active. The relevant sysfs file is:
+
+	/sys/devices/system/cpu/vulnerabilities/mmio_stale_data
+
+The possible values in this file are:
+
+  .. list-table::
+
+     * - 'Not affected'
+       - The processor is not vulnerable
+     * - 'Vulnerable'
+       - The processor is vulnerable, but no mitigation enabled
+     * - 'Vulnerable: Clear CPU buffers attempted, no microcode'
+       - The processor is vulnerable but microcode is not updated. The
+         mitigation is enabled on a best effort basis.
+
+         If the processor is vulnerable but the availability of the microcode
+         based mitigation mechanism is not advertised via CPUID, the kernel
+         selects a best effort mitigation mode. This mode invokes the mitigation
+         instructions without a guarantee that they clear the CPU buffers.
+
+         This is done to address virtualization scenarios where the host has the
+         microcode update applied, but the hypervisor is not yet updated to
+         expose the CPUID to the guest. If the host has updated microcode the
+         protection takes effect; otherwise a few CPU cycles are wasted
+         pointlessly.
+     * - 'Mitigation: Clear CPU buffers'
+       - The processor is vulnerable and the CPU buffer clearing mitigation is
+         enabled.
+     * - 'Unknown: No mitigations'
+       - The processor vulnerability status is unknown because it is
+	 out of Servicing period. Mitigation is not attempted.
+
+Definitions:
+------------
+
+Servicing period: The process of providing functional and security updates to
+Intel processors or platforms, utilizing the Intel Platform Update (IPU)
+process or other similar mechanisms.
+
+End of Servicing Updates (ESU): ESU is the date at which Intel will no
+longer provide Servicing, such as through IPU or other similar update
+processes. ESU dates will typically be aligned to end of quarter.
+
+If the processor is vulnerable then the following information is appended to
+the above information:
+
+  ========================  ===========================================
+  'SMT vulnerable'          SMT is enabled
+  'SMT disabled'            SMT is disabled
+  'SMT Host state unknown'  Kernel runs in a VM, Host SMT state unknown
+  ========================  ===========================================
+
+References
+----------
+.. [#f1] Affected Processors
+   https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html
diff --git a/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst b/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
new file mode 100644
index 000000000..ad15417d3
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
@@ -0,0 +1,96 @@
+==================================
+Register File Data Sampling (RFDS)
+==================================
+
+Register File Data Sampling (RFDS) is a microarchitectural vulnerability that
+only affects Intel Atom parts(also branded as E-cores). RFDS may allow
+a malicious actor to infer data values previously used in floating point
+registers, vector registers, or integer registers. RFDS does not provide the
+ability to choose which data is inferred. CVE-2023-28746 is assigned to RFDS.
+
+Affected Processors
+===================
+Below is the list of affected Intel processors [#f1]_:
+
+   ===================  ============
+   Common name          Family_Model
+   ===================  ============
+   ATOM_GOLDMONT           06_5CH
+   ATOM_GOLDMONT_D         06_5FH
+   ATOM_GOLDMONT_PLUS      06_7AH
+   ATOM_TREMONT_D          06_86H
+   ATOM_TREMONT            06_96H
+   ALDERLAKE               06_97H
+   ALDERLAKE_L             06_9AH
+   ATOM_TREMONT_L          06_9CH
+   RAPTORLAKE              06_B7H
+   RAPTORLAKE_P            06_BAH
+   ATOM_GRACEMONT          06_BEH
+   RAPTORLAKE_S            06_BFH
+   ===================  ============
+
+Mitigation
+==========
+Intel released a microcode update that enables software to clear sensitive
+information using the VERW instruction. Like MDS, RFDS deploys the same
+mitigation strategy to force the CPU to clear the affected buffers before an
+attacker can extract the secrets. This is achieved by using the otherwise
+unused and obsolete VERW instruction in combination with a microcode update.
+The microcode clears the affected CPU buffers when the VERW instruction is
+executed.
+
+Mitigation points
+-----------------
+VERW is executed by the kernel before returning to user space, and by KVM
+before VMentry. None of the affected cores support SMT, so VERW is not required
+at C-state transitions.
+
+New bits in IA32_ARCH_CAPABILITIES
+----------------------------------
+Newer processors and microcode update on existing affected processors added new
+bits to IA32_ARCH_CAPABILITIES MSR. These bits can be used to enumerate
+vulnerability and mitigation capability:
+
+- Bit 27 - RFDS_NO - When set, processor is not affected by RFDS.
+- Bit 28 - RFDS_CLEAR - When set, processor is affected by RFDS, and has the
+  microcode that clears the affected buffers on VERW execution.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The kernel command line allows to control RFDS mitigation at boot time with the
+parameter "reg_file_data_sampling=". The valid arguments are:
+
+  ==========  =================================================================
+  on          If the CPU is vulnerable, enable mitigation; CPU buffer clearing
+              on exit to userspace and before entering a VM.
+  off         Disables mitigation.
+  ==========  =================================================================
+
+Mitigation default is selected by CONFIG_MITIGATION_RFDS.
+
+Mitigation status information
+-----------------------------
+The Linux kernel provides a sysfs interface to enumerate the current
+vulnerability status of the system: whether the system is vulnerable, and
+which mitigations are active. The relevant sysfs file is:
+
+	/sys/devices/system/cpu/vulnerabilities/reg_file_data_sampling
+
+The possible values in this file are:
+
+  .. list-table::
+
+     * - 'Not affected'
+       - The processor is not vulnerable
+     * - 'Vulnerable'
+       - The processor is vulnerable, but no mitigation enabled
+     * - 'Vulnerable: No microcode'
+       - The processor is vulnerable but microcode is not updated.
+     * - 'Mitigation: Clear Register File'
+       - The processor is vulnerable and the CPU buffer clearing mitigation is
+	 enabled.
+
+References
+----------
+.. [#f1] Affected Processors
+   https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html
diff --git a/Documentation/admin-guide/hw-vuln/rsb.rst b/Documentation/admin-guide/hw-vuln/rsb.rst
new file mode 100644
index 000000000..21dbf9cf2
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/rsb.rst
@@ -0,0 +1,268 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+RSB-related mitigations
+=======================
+
+.. warning::
+   Please keep this document up-to-date, otherwise you will be
+   volunteered to update it and convert it to a very long comment in
+   bugs.c!
+
+Since 2018 there have been many Spectre CVEs related to the Return Stack
+Buffer (RSB) (sometimes referred to as the Return Address Stack (RAS) or
+Return Address Predictor (RAP) on AMD).
+
+Information about these CVEs and how to mitigate them is scattered
+amongst a myriad of microarchitecture-specific documents.
+
+This document attempts to consolidate all the relevant information in
+once place and clarify the reasoning behind the current RSB-related
+mitigations.  It's meant to be as concise as possible, focused only on
+the current kernel mitigations: what are the RSB-related attack vectors
+and how are they currently being mitigated?
+
+It's *not* meant to describe how the RSB mechanism operates or how the
+exploits work.  More details about those can be found in the references
+below.
+
+Rather, this is basically a glorified comment, but too long to actually
+be one.  So when the next CVE comes along, a kernel developer can
+quickly refer to this as a refresher to see what we're actually doing
+and why.
+
+At a high level, there are two classes of RSB attacks: RSB poisoning
+(Intel and AMD) and RSB underflow (Intel only).  They must each be
+considered individually for each attack vector (and microarchitecture
+where applicable).
+
+----
+
+RSB poisoning (Intel and AMD)
+=============================
+
+SpectreRSB
+~~~~~~~~~~
+
+RSB poisoning is a technique used by SpectreRSB [#spectre-rsb]_ where
+an attacker poisons an RSB entry to cause a victim's return instruction
+to speculate to an attacker-controlled address.  This can happen when
+there are unbalanced CALLs/RETs after a context switch or VMEXIT.
+
+* All attack vectors can potentially be mitigated by flushing out any
+  poisoned RSB entries using an RSB filling sequence
+  [#intel-rsb-filling]_ [#amd-rsb-filling]_ when transitioning between
+  untrusted and trusted domains.  But this has a performance impact and
+  should be avoided whenever possible.
+
+  .. DANGER::
+     **FIXME**: Currently we're flushing 32 entries.  However, some CPU
+     models have more than 32 entries.  The loop count needs to be
+     increased for those.  More detailed information is needed about RSB
+     sizes.
+
+* On context switch, the user->user mitigation requires ensuring the
+  RSB gets filled or cleared whenever IBPB gets written [#cond-ibpb]_
+  during a context switch:
+
+  * AMD:
+	On Zen 4+, IBPB (or SBPB [#amd-sbpb]_ if used) clears the RSB.
+	This is indicated by IBPB_RET in CPUID [#amd-ibpb-rsb]_.
+
+	On Zen < 4, the RSB filling sequence [#amd-rsb-filling]_ must be
+	always be done in addition to IBPB [#amd-ibpb-no-rsb]_.  This is
+	indicated by X86_BUG_IBPB_NO_RET.
+
+  * Intel:
+	IBPB always clears the RSB:
+
+	"Software that executed before the IBPB command cannot control
+	the predicted targets of indirect branches executed after the
+	command on the same logical processor. The term indirect branch
+	in this context includes near return instructions, so these
+	predicted targets may come from the RSB." [#intel-ibpb-rsb]_
+
+* On context switch, user->kernel attacks are prevented by SMEP.  User
+  space can only insert user space addresses into the RSB.  Even
+  non-canonical addresses can't be inserted due to the page gap at the
+  end of the user canonical address space reserved by TASK_SIZE_MAX.
+  A SMEP #PF at instruction fetch prevents the kernel from speculatively
+  executing user space.
+
+  * AMD:
+	"Finally, branches that are predicted as 'ret' instructions get
+	their predicted targets from the Return Address Predictor (RAP).
+	AMD recommends software use a RAP stuffing sequence (mitigation
+	V2-3 in [2]) and/or Supervisor Mode Execution Protection (SMEP)
+	to ensure that the addresses in the RAP are safe for
+	speculation. Collectively, we refer to these mitigations as "RAP
+	Protection"." [#amd-smep-rsb]_
+
+  * Intel:
+	"On processors with enhanced IBRS, an RSB overwrite sequence may
+	not suffice to prevent the predicted target of a near return
+	from using an RSB entry created in a less privileged predictor
+	mode.  Software can prevent this by enabling SMEP (for
+	transitions from user mode to supervisor mode) and by having
+	IA32_SPEC_CTRL.IBRS set during VM exits." [#intel-smep-rsb]_
+
+* On VMEXIT, guest->host attacks are mitigated by eIBRS (and PBRSB
+  mitigation if needed):
+
+  * AMD:
+	"When Automatic IBRS is enabled, the internal return address
+	stack used for return address predictions is cleared on VMEXIT."
+	[#amd-eibrs-vmexit]_
+
+  * Intel:
+	"On processors with enhanced IBRS, an RSB overwrite sequence may
+	not suffice to prevent the predicted target of a near return
+	from using an RSB entry created in a less privileged predictor
+	mode.  Software can prevent this by enabling SMEP (for
+	transitions from user mode to supervisor mode) and by having
+	IA32_SPEC_CTRL.IBRS set during VM exits. Processors with
+	enhanced IBRS still support the usage model where IBRS is set
+	only in the OS/VMM for OSes that enable SMEP. To do this, such
+	processors will ensure that guest behavior cannot control the
+	RSB after a VM exit once IBRS is set, even if IBRS was not set
+	at the time of the VM exit." [#intel-eibrs-vmexit]_
+
+    Note that some Intel CPUs are susceptible to Post-barrier Return
+    Stack Buffer Predictions (PBRSB) [#intel-pbrsb]_, where the last
+    CALL from the guest can be used to predict the first unbalanced RET.
+    In this case the PBRSB mitigation is needed in addition to eIBRS.
+
+AMD RETBleed / SRSO / Branch Type Confusion
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+On AMD, poisoned RSB entries can also be created by the AMD RETBleed
+variant [#retbleed-paper]_ [#amd-btc]_ or by Speculative Return Stack
+Overflow [#amd-srso]_ (Inception [#inception-paper]_).  The kernel
+protects itself by replacing every RET in the kernel with a branch to a
+single safe RET.
+
+----
+
+RSB underflow (Intel only)
+==========================
+
+RSB Alternate (RSBA) ("Intel Retbleed")
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some Intel Skylake-generation CPUs are susceptible to the Intel variant
+of RETBleed [#retbleed-paper]_ (Return Stack Buffer Underflow
+[#intel-rsbu]_).  If a RET is executed when the RSB buffer is empty due
+to mismatched CALLs/RETs or returning from a deep call stack, the branch
+predictor can fall back to using the Branch Target Buffer (BTB).  If a
+user forces a BTB collision then the RET can speculatively branch to a
+user-controlled address.
+
+* Note that RSB filling doesn't fully mitigate this issue.  If there
+  are enough unbalanced RETs, the RSB may still underflow and fall back
+  to using a poisoned BTB entry.
+
+* On context switch, user->user underflow attacks are mitigated by the
+  conditional IBPB [#cond-ibpb]_ on context switch which effectively
+  clears the BTB:
+
+  * "The indirect branch predictor barrier (IBPB) is an indirect branch
+    control mechanism that establishes a barrier, preventing software
+    that executed before the barrier from controlling the predicted
+    targets of indirect branches executed after the barrier on the same
+    logical processor." [#intel-ibpb-btb]_
+
+* On context switch and VMEXIT, user->kernel and guest->host RSB
+  underflows are mitigated by IBRS or eIBRS:
+
+  * "Enabling IBRS (including enhanced IBRS) will mitigate the "RSBU"
+    attack demonstrated by the researchers. As previously documented,
+    Intel recommends the use of enhanced IBRS, where supported. This
+    includes any processor that enumerates RRSBA but not RRSBA_DIS_S."
+    [#intel-rsbu]_
+
+  However, note that eIBRS and IBRS do not mitigate intra-mode attacks.
+  Like RRSBA below, this is mitigated by clearing the BHB on kernel
+  entry.
+
+  As an alternative to classic IBRS, call depth tracking (combined with
+  retpolines) can be used to track kernel returns and fill the RSB when
+  it gets close to being empty.
+
+Restricted RSB Alternate (RRSBA)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some newer Intel CPUs have Restricted RSB Alternate (RRSBA) behavior,
+which, similar to RSBA described above, also falls back to using the BTB
+on RSB underflow.  The only difference is that the predicted targets are
+restricted to the current domain when eIBRS is enabled:
+
+* "Restricted RSB Alternate (RRSBA) behavior allows alternate branch
+  predictors to be used by near RET instructions when the RSB is
+  empty.  When eIBRS is enabled, the predicted targets of these
+  alternate predictors are restricted to those belonging to the
+  indirect branch predictor entries of the current prediction domain.
+  [#intel-eibrs-rrsba]_
+
+When a CPU with RRSBA is vulnerable to Branch History Injection
+[#bhi-paper]_ [#intel-bhi]_, an RSB underflow could be used for an
+intra-mode BTI attack.  This is mitigated by clearing the BHB on
+kernel entry.
+
+However if the kernel uses retpolines instead of eIBRS, it needs to
+disable RRSBA:
+
+* "Where software is using retpoline as a mitigation for BHI or
+  intra-mode BTI, and the processor both enumerates RRSBA and
+  enumerates RRSBA_DIS controls, it should disable this behavior."
+  [#intel-retpoline-rrsba]_
+
+----
+
+References
+==========
+
+.. [#spectre-rsb] `Spectre Returns! Speculation Attacks using the Return Stack Buffer <https://arxiv.org/pdf/1807.07940.pdf>`_
+
+.. [#intel-rsb-filling] "Empty RSB Mitigation on Skylake-generation" in `Retpoline: A Branch Target Injection Mitigation <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/retpoline-branch-target-injection-mitigation.html#inpage-nav-5-1>`_
+
+.. [#amd-rsb-filling] "Mitigation V2-3" in `Software Techniques for Managing Speculation <https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/software-techniques-for-managing-speculation.pdf>`_
+
+.. [#cond-ibpb] Whether IBPB is written depends on whether the prev and/or next task is protected from Spectre attacks.  It typically requires opting in per task or system-wide.  For more details see the documentation for the ``spectre_v2_user`` cmdline option in Documentation/admin-guide/kernel-parameters.txt.
+
+.. [#amd-sbpb] IBPB without flushing of branch type predictions.  Only exists for AMD.
+
+.. [#amd-ibpb-rsb] "Function 8000_0008h -- Processor Capacity Parameters and Extended Feature Identification" in `AMD64 Architecture Programmer's Manual Volume 3: General-Purpose and System Instructions <https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24594.pdf>`_.  SBPB behaves the same way according to `this email <https://lore.kernel.org/5175b163a3736ca5fd01cedf406735636c99a>`_.
+
+.. [#amd-ibpb-no-rsb] `Spectre Attacks: Exploiting Speculative Execution <https://comsec.ethz.ch/wp-content/files/ibpb_sp25.pdf>`_
+
+.. [#intel-ibpb-rsb] "Introduction" in `Post-barrier Return Stack Buffer Predictions / CVE-2022-26373 / INTEL-SA-00706 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/post-barrier-return-stack-buffer-predictions.html>`_
+
+.. [#amd-smep-rsb] "Existing Mitigations" in `Technical Guidance for Mitigating Branch Type Confusion <https://www.amd.com/content/dam/amd/en/documents/resources/technical-guidance-for-mitigating-branch-type-confusion.pdf>`_
+
+.. [#intel-smep-rsb] "Enhanced IBRS" in `Indirect Branch Restricted Speculation <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/indirect-branch-restricted-speculation.html>`_
+
+.. [#amd-eibrs-vmexit] "Extended Feature Enable Register (EFER)" in `AMD64 Architecture Programmer's Manual Volume 2: System Programming <https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/programmer-references/24593.pdf>`_
+
+.. [#intel-eibrs-vmexit] "Enhanced IBRS" in `Indirect Branch Restricted Speculation <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/indirect-branch-restricted-speculation.html>`_
+
+.. [#intel-pbrsb] `Post-barrier Return Stack Buffer Predictions / CVE-2022-26373 / INTEL-SA-00706 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/post-barrier-return-stack-buffer-predictions.html>`_
+
+.. [#retbleed-paper] `RETBleed: Arbitrary Speculative Code Execution with Return Instruction <https://comsec.ethz.ch/wp-content/files/retbleed_sec22.pdf>`_
+
+.. [#amd-btc] `Technical Guidance for Mitigating Branch Type Confusion <https://www.amd.com/content/dam/amd/en/documents/resources/technical-guidance-for-mitigating-branch-type-confusion.pdf>`_
+
+.. [#amd-srso] `Technical Update Regarding Speculative Return Stack Overflow <https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf>`_
+
+.. [#inception-paper] `Inception: Exposing New Attack Surfaces with Training in Transient Execution <https://comsec.ethz.ch/wp-content/files/inception_sec23.pdf>`_
+
+.. [#intel-rsbu] `Return Stack Buffer Underflow / Return Stack Buffer Underflow / CVE-2022-29901, CVE-2022-28693 / INTEL-SA-00702 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/return-stack-buffer-underflow.html>`_
+
+.. [#intel-ibpb-btb] `Indirect Branch Predictor Barrier' <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/indirect-branch-predictor-barrier.html>`_
+
+.. [#intel-eibrs-rrsba] "Guidance for RSBU" in `Return Stack Buffer Underflow / Return Stack Buffer Underflow / CVE-2022-29901, CVE-2022-28693 / INTEL-SA-00702 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/return-stack-buffer-underflow.html>`_
+
+.. [#bhi-paper] `Branch History Injection: On the Effectiveness of Hardware Mitigations Against Cross-Privilege Spectre-v2 Attacks <http://download.vusec.net/papers/bhi-spectre-bhb_sec22.pdf>`_
+
+.. [#intel-bhi] `Branch History Injection and Intra-mode Branch Target Injection / CVE-2022-0001, CVE-2022-0002 / INTEL-SA-00598 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html>`_
+
+.. [#intel-retpoline-rrsba] "Retpoline" in `Branch History Injection and Intra-mode Branch Target Injection / CVE-2022-0001, CVE-2022-0002 / INTEL-SA-00598 <https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html>`_
diff --git a/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst b/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst
new file mode 100644
index 000000000..966c9b329
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst
@@ -0,0 +1,150 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+SRBDS - Special Register Buffer Data Sampling
+=============================================
+
+SRBDS is a hardware vulnerability that allows MDS
+Documentation/admin-guide/hw-vuln/mds.rst techniques to
+infer values returned from special register accesses.  Special register
+accesses are accesses to off core registers.  According to Intel's evaluation,
+the special register reads that have a security expectation of privacy are
+RDRAND, RDSEED and SGX EGETKEY.
+
+When RDRAND, RDSEED and EGETKEY instructions are used, the data is moved
+to the core through the special register mechanism that is susceptible
+to MDS attacks.
+
+Affected processors
+-------------------
+Core models (desktop, mobile, Xeon-E3) that implement RDRAND and/or RDSEED may
+be affected.
+
+A processor is affected by SRBDS if its Family_Model and stepping is
+in the following list, with the exception of the listed processors
+exporting MDS_NO while Intel TSX is available yet not enabled. The
+latter class of processors are only affected when Intel TSX is enabled
+by software using TSX_CTRL_MSR otherwise they are not affected.
+
+  =============  ============  ========
+  common name    Family_Model  Stepping
+  =============  ============  ========
+  IvyBridge      06_3AH        All
+
+  Haswell        06_3CH        All
+  Haswell_L      06_45H        All
+  Haswell_G      06_46H        All
+
+  Broadwell_G    06_47H        All
+  Broadwell      06_3DH        All
+
+  Skylake_L      06_4EH        All
+  Skylake        06_5EH        All
+
+  Kabylake_L     06_8EH        <= 0xC
+  Kabylake       06_9EH        <= 0xD
+  =============  ============  ========
+
+Related CVEs
+------------
+
+The following CVE entry is related to this SRBDS issue:
+
+    ==============  =====  =====================================
+    CVE-2020-0543   SRBDS  Special Register Buffer Data Sampling
+    ==============  =====  =====================================
+
+Attack scenarios
+----------------
+An unprivileged user can extract values returned from RDRAND and RDSEED
+executed on another core or sibling thread using MDS techniques.
+
+
+Mitigation mechanism
+--------------------
+Intel will release microcode updates that modify the RDRAND, RDSEED, and
+EGETKEY instructions to overwrite secret special register data in the shared
+staging buffer before the secret data can be accessed by another logical
+processor.
+
+During execution of the RDRAND, RDSEED, or EGETKEY instructions, off-core
+accesses from other logical processors will be delayed until the special
+register read is complete and the secret data in the shared staging buffer is
+overwritten.
+
+This has three effects on performance:
+
+#. RDRAND, RDSEED, or EGETKEY instructions have higher latency.
+
+#. Executing RDRAND at the same time on multiple logical processors will be
+   serialized, resulting in an overall reduction in the maximum RDRAND
+   bandwidth.
+
+#. Executing RDRAND, RDSEED or EGETKEY will delay memory accesses from other
+   logical processors that miss their core caches, with an impact similar to
+   legacy locked cache-line-split accesses.
+
+The microcode updates provide an opt-out mechanism (RNGDS_MITG_DIS) to disable
+the mitigation for RDRAND and RDSEED instructions executed outside of Intel
+Software Guard Extensions (Intel SGX) enclaves. On logical processors that
+disable the mitigation using this opt-out mechanism, RDRAND and RDSEED do not
+take longer to execute and do not impact performance of sibling logical
+processors memory accesses. The opt-out mechanism does not affect Intel SGX
+enclaves (including execution of RDRAND or RDSEED inside an enclave, as well
+as EGETKEY execution).
+
+IA32_MCU_OPT_CTRL MSR Definition
+--------------------------------
+Along with the mitigation for this issue, Intel added a new thread-scope
+IA32_MCU_OPT_CTRL MSR, (address 0x123). The presence of this MSR and
+RNGDS_MITG_DIS (bit 0) is enumerated by CPUID.(EAX=07H,ECX=0).EDX[SRBDS_CTRL =
+9]==1. This MSR is introduced through the microcode update.
+
+Setting IA32_MCU_OPT_CTRL[0] (RNGDS_MITG_DIS) to 1 for a logical processor
+disables the mitigation for RDRAND and RDSEED executed outside of an Intel SGX
+enclave on that logical processor. Opting out of the mitigation for a
+particular logical processor does not affect the RDRAND and RDSEED mitigations
+for other logical processors.
+
+Note that inside of an Intel SGX enclave, the mitigation is applied regardless
+of the value of RNGDS_MITG_DS.
+
+Mitigation control on the kernel command line
+---------------------------------------------
+The kernel command line allows control over the SRBDS mitigation at boot time
+with the option "srbds=".  The option for this is:
+
+  ============= =============================================================
+  off           This option disables SRBDS mitigation for RDRAND and RDSEED on
+                affected platforms.
+  ============= =============================================================
+
+SRBDS System Information
+------------------------
+The Linux kernel provides vulnerability status information through sysfs.  For
+SRBDS this can be accessed by the following sysfs file:
+/sys/devices/system/cpu/vulnerabilities/srbds
+
+The possible values contained in this file are:
+
+ ============================== =============================================
+ Not affected                   Processor not vulnerable
+ Vulnerable                     Processor vulnerable and mitigation disabled
+ Vulnerable: No microcode       Processor vulnerable and microcode is missing
+                                mitigation
+ Mitigation: Microcode          Processor is vulnerable and mitigation is in
+                                effect.
+ Mitigation: TSX disabled       Processor is only vulnerable when TSX is
+                                enabled while this system was booted with TSX
+                                disabled.
+ Unknown: Dependent on
+ hypervisor status              Running on virtual guest processor that is
+                                affected but with no way to know if host
+                                processor is mitigated or vulnerable.
+ ============================== =============================================
+
+SRBDS Default mitigation
+------------------------
+This new microcode serializes processor access during execution of RDRAND,
+RDSEED ensures that the shared buffer is overwritten before it is released for
+reuse.  Use the "srbds=off" kernel command line to disable the mitigation for
+RDRAND and RDSEED.
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst
new file mode 100644
index 000000000..4bb8549be
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/spectre.rst
@@ -0,0 +1,725 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Spectre Side Channels
+=====================
+
+Spectre is a class of side channel attacks that exploit branch prediction
+and speculative execution on modern CPUs to read memory, possibly
+bypassing access controls. Speculative execution side channel exploits
+do not modify memory but attempt to infer privileged data in the memory.
+
+This document covers Spectre variant 1 and Spectre variant 2.
+
+Affected processors
+-------------------
+
+Speculative execution side channel methods affect a wide range of modern
+high performance processors, since most modern high speed processors
+use branch prediction and speculative execution.
+
+The following CPUs are vulnerable:
+
+    - Intel Core, Atom, Pentium, and Xeon processors
+
+    - AMD Phenom, EPYC, and Zen processors
+
+    - IBM POWER and zSeries processors
+
+    - Higher end ARM processors
+
+    - Apple CPUs
+
+    - Higher end MIPS CPUs
+
+    - Likely most other high performance CPUs. Contact your CPU vendor for details.
+
+Whether a processor is affected or not can be read out from the Spectre
+vulnerability files in sysfs. See :ref:`spectre_sys_info`.
+
+Related CVEs
+------------
+
+The following CVE entries describe Spectre variants:
+
+   =============   =======================  ==========================
+   CVE-2017-5753   Bounds check bypass      Spectre variant 1
+   CVE-2017-5715   Branch target injection  Spectre variant 2
+   CVE-2019-1125   Spectre v1 swapgs        Spectre variant 1 (swapgs)
+   =============   =======================  ==========================
+
+Problem
+-------
+
+CPUs use speculative operations to improve performance. That may leave
+traces of memory accesses or computations in the processor's caches,
+buffers, and branch predictors. Malicious software may be able to
+influence the speculative execution paths, and then use the side effects
+of the speculative execution in the CPUs' caches and buffers to infer
+privileged data touched during the speculative execution.
+
+Spectre variant 1 attacks take advantage of speculative execution of
+conditional branches, while Spectre variant 2 attacks use speculative
+execution of indirect branches to leak privileged memory.
+See :ref:`[1] <spec_ref1>` :ref:`[5] <spec_ref5>` :ref:`[6] <spec_ref6>`
+:ref:`[7] <spec_ref7>` :ref:`[10] <spec_ref10>` :ref:`[11] <spec_ref11>`.
+
+Spectre variant 1 (Bounds Check Bypass)
+---------------------------------------
+
+The bounds check bypass attack :ref:`[2] <spec_ref2>` takes advantage
+of speculative execution that bypasses conditional branch instructions
+used for memory access bounds check (e.g. checking if the index of an
+array results in memory access within a valid range). This results in
+memory accesses to invalid memory (with out-of-bound index) that are
+done speculatively before validation checks resolve. Such speculative
+memory accesses can leave side effects, creating side channels which
+leak information to the attacker.
+
+There are some extensions of Spectre variant 1 attacks for reading data
+over the network, see :ref:`[12] <spec_ref12>`. However such attacks
+are difficult, low bandwidth, fragile, and are considered low risk.
+
+Note that, despite "Bounds Check Bypass" name, Spectre variant 1 is not
+only about user-controlled array bounds checks.  It can affect any
+conditional checks.  The kernel entry code interrupt, exception, and NMI
+handlers all have conditional swapgs checks.  Those may be problematic
+in the context of Spectre v1, as kernel code can speculatively run with
+a user GS.
+
+Spectre variant 2 (Branch Target Injection)
+-------------------------------------------
+
+The branch target injection attack takes advantage of speculative
+execution of indirect branches :ref:`[3] <spec_ref3>`.  The indirect
+branch predictors inside the processor used to guess the target of
+indirect branches can be influenced by an attacker, causing gadget code
+to be speculatively executed, thus exposing sensitive data touched by
+the victim. The side effects left in the CPU's caches during speculative
+execution can be measured to infer data values.
+
+.. _poison_btb:
+
+In Spectre variant 2 attacks, the attacker can steer speculative indirect
+branches in the victim to gadget code by poisoning the branch target
+buffer of a CPU used for predicting indirect branch addresses. Such
+poisoning could be done by indirect branching into existing code,
+with the address offset of the indirect branch under the attacker's
+control. Since the branch prediction on impacted hardware does not
+fully disambiguate branch address and uses the offset for prediction,
+this could cause privileged code's indirect branch to jump to a gadget
+code with the same offset.
+
+The most useful gadgets take an attacker-controlled input parameter (such
+as a register value) so that the memory read can be controlled. Gadgets
+without input parameters might be possible, but the attacker would have
+very little control over what memory can be read, reducing the risk of
+the attack revealing useful data.
+
+One other variant 2 attack vector is for the attacker to poison the
+return stack buffer (RSB) :ref:`[13] <spec_ref13>` to cause speculative
+subroutine return instruction execution to go to a gadget.  An attacker's
+imbalanced subroutine call instructions might "poison" entries in the
+return stack buffer which are later consumed by a victim's subroutine
+return instructions.  This attack can be mitigated by flushing the return
+stack buffer on context switch, or virtual machine (VM) exit.
+
+On systems with simultaneous multi-threading (SMT), attacks are possible
+from the sibling thread, as level 1 cache and branch target buffer
+(BTB) may be shared between hardware threads in a CPU core.  A malicious
+program running on the sibling thread may influence its peer's BTB to
+steer its indirect branch speculations to gadget code, and measure the
+speculative execution's side effects left in level 1 cache to infer the
+victim's data.
+
+Yet another variant 2 attack vector is for the attacker to poison the
+Branch History Buffer (BHB) to speculatively steer an indirect branch
+to a specific Branch Target Buffer (BTB) entry, even if the entry isn't
+associated with the source address of the indirect branch. Specifically,
+the BHB might be shared across privilege levels even in the presence of
+Enhanced IBRS.
+
+Previously the only known real-world BHB attack vector was via unprivileged
+eBPF. Further research has found attacks that don't require unprivileged eBPF.
+For a full mitigation against BHB attacks it is recommended to set BHI_DIS_S or
+use the BHB clearing sequence.
+
+Attack scenarios
+----------------
+
+The following list of attack scenarios have been anticipated, but may
+not cover all possible attack vectors.
+
+1. A user process attacking the kernel
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Spectre variant 1
+~~~~~~~~~~~~~~~~~
+
+   The attacker passes a parameter to the kernel via a register or
+   via a known address in memory during a syscall. Such parameter may
+   be used later by the kernel as an index to an array or to derive
+   a pointer for a Spectre variant 1 attack.  The index or pointer
+   is invalid, but bound checks are bypassed in the code branch taken
+   for speculative execution. This could cause privileged memory to be
+   accessed and leaked.
+
+   For kernel code that has been identified where data pointers could
+   potentially be influenced for Spectre attacks, new "nospec" accessor
+   macros are used to prevent speculative loading of data.
+
+Spectre variant 1 (swapgs)
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+   An attacker can train the branch predictor to speculatively skip the
+   swapgs path for an interrupt or exception.  If they initialize
+   the GS register to a user-space value, if the swapgs is speculatively
+   skipped, subsequent GS-related percpu accesses in the speculation
+   window will be done with the attacker-controlled GS value.  This
+   could cause privileged memory to be accessed and leaked.
+
+   For example:
+
+   ::
+
+     if (coming from user space)
+         swapgs
+     mov %gs:<percpu_offset>, %reg
+     mov (%reg), %reg1
+
+   When coming from user space, the CPU can speculatively skip the
+   swapgs, and then do a speculative percpu load using the user GS
+   value.  So the user can speculatively force a read of any kernel
+   value.  If a gadget exists which uses the percpu value as an address
+   in another load/store, then the contents of the kernel value may
+   become visible via an L1 side channel attack.
+
+   A similar attack exists when coming from kernel space.  The CPU can
+   speculatively do the swapgs, causing the user GS to get used for the
+   rest of the speculative window.
+
+Spectre variant 2
+~~~~~~~~~~~~~~~~~
+
+   A spectre variant 2 attacker can :ref:`poison <poison_btb>` the branch
+   target buffer (BTB) before issuing syscall to launch an attack.
+   After entering the kernel, the kernel could use the poisoned branch
+   target buffer on indirect jump and jump to gadget code in speculative
+   execution.
+
+   If an attacker tries to control the memory addresses leaked during
+   speculative execution, he would also need to pass a parameter to the
+   gadget, either through a register or a known address in memory. After
+   the gadget has executed, he can measure the side effect.
+
+   The kernel can protect itself against consuming poisoned branch
+   target buffer entries by using return trampolines (also known as
+   "retpoline") :ref:`[3] <spec_ref3>` :ref:`[9] <spec_ref9>` for all
+   indirect branches. Return trampolines trap speculative execution paths
+   to prevent jumping to gadget code during speculative execution.
+   x86 CPUs with Enhanced Indirect Branch Restricted Speculation
+   (Enhanced IBRS) available in hardware should use the feature to
+   mitigate Spectre variant 2 instead of retpoline. Enhanced IBRS is
+   more efficient than retpoline.
+
+   There may be gadget code in firmware which could be exploited with
+   Spectre variant 2 attack by a rogue user process. To mitigate such
+   attacks on x86, Indirect Branch Restricted Speculation (IBRS) feature
+   is turned on before the kernel invokes any firmware code.
+
+2. A user process attacking another user process
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   A malicious user process can try to attack another user process,
+   either via a context switch on the same hardware thread, or from the
+   sibling hyperthread sharing a physical processor core on simultaneous
+   multi-threading (SMT) system.
+
+   Spectre variant 1 attacks generally require passing parameters
+   between the processes, which needs a data passing relationship, such
+   as remote procedure calls (RPC).  Those parameters are used in gadget
+   code to derive invalid data pointers accessing privileged memory in
+   the attacked process.
+
+   Spectre variant 2 attacks can be launched from a rogue process by
+   :ref:`poisoning <poison_btb>` the branch target buffer.  This can
+   influence the indirect branch targets for a victim process that either
+   runs later on the same hardware thread, or running concurrently on
+   a sibling hardware thread sharing the same physical core.
+
+   A user process can protect itself against Spectre variant 2 attacks
+   by using the prctl() syscall to disable indirect branch speculation
+   for itself.  An administrator can also cordon off an unsafe process
+   from polluting the branch target buffer by disabling the process's
+   indirect branch speculation. This comes with a performance cost
+   from not using indirect branch speculation and clearing the branch
+   target buffer.  When SMT is enabled on x86, for a process that has
+   indirect branch speculation disabled, Single Threaded Indirect Branch
+   Predictors (STIBP) :ref:`[4] <spec_ref4>` are turned on to prevent the
+   sibling thread from controlling branch target buffer.  In addition,
+   the Indirect Branch Prediction Barrier (IBPB) is issued to clear the
+   branch target buffer when context switching to and from such process.
+
+   On x86, the return stack buffer is stuffed on context switch.
+   This prevents the branch target buffer from being used for branch
+   prediction when the return stack buffer underflows while switching to
+   a deeper call stack. Any poisoned entries in the return stack buffer
+   left by the previous process will also be cleared.
+
+   User programs should use address space randomization to make attacks
+   more difficult (Set /proc/sys/kernel/randomize_va_space = 1 or 2).
+
+3. A virtualized guest attacking the host
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   The attack mechanism is similar to how user processes attack the
+   kernel.  The kernel is entered via hyper-calls or other virtualization
+   exit paths.
+
+   For Spectre variant 1 attacks, rogue guests can pass parameters
+   (e.g. in registers) via hyper-calls to derive invalid pointers to
+   speculate into privileged memory after entering the kernel.  For places
+   where such kernel code has been identified, nospec accessor macros
+   are used to stop speculative memory access.
+
+   For Spectre variant 2 attacks, rogue guests can :ref:`poison
+   <poison_btb>` the branch target buffer or return stack buffer, causing
+   the kernel to jump to gadget code in the speculative execution paths.
+
+   To mitigate variant 2, the host kernel can use return trampolines
+   for indirect branches to bypass the poisoned branch target buffer,
+   and flushing the return stack buffer on VM exit.  This prevents rogue
+   guests from affecting indirect branching in the host kernel.
+
+   To protect host processes from rogue guests, host processes can have
+   indirect branch speculation disabled via prctl().  The branch target
+   buffer is cleared before context switching to such processes.
+
+4. A virtualized guest attacking other guest
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   A rogue guest may attack another guest to get data accessible by the
+   other guest.
+
+   Spectre variant 1 attacks are possible if parameters can be passed
+   between guests.  This may be done via mechanisms such as shared memory
+   or message passing.  Such parameters could be used to derive data
+   pointers to privileged data in guest.  The privileged data could be
+   accessed by gadget code in the victim's speculation paths.
+
+   Spectre variant 2 attacks can be launched from a rogue guest by
+   :ref:`poisoning <poison_btb>` the branch target buffer or the return
+   stack buffer. Such poisoned entries could be used to influence
+   speculation execution paths in the victim guest.
+
+   Linux kernel mitigates attacks to other guests running in the same
+   CPU hardware thread by flushing the return stack buffer on VM exit,
+   and clearing the branch target buffer before switching to a new guest.
+
+   If SMT is used, Spectre variant 2 attacks from an untrusted guest
+   in the sibling hyperthread can be mitigated by the administrator,
+   by turning off the unsafe guest's indirect branch speculation via
+   prctl().  A guest can also protect itself by turning on microcode
+   based mitigations (such as IBPB or STIBP on x86) within the guest.
+
+.. _spectre_sys_info:
+
+Spectre system information
+--------------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current
+mitigation status of the system for Spectre: whether the system is
+vulnerable, and which mitigations are active.
+
+The sysfs file showing Spectre variant 1 mitigation status is:
+
+   /sys/devices/system/cpu/vulnerabilities/spectre_v1
+
+The possible values in this file are:
+
+  .. list-table::
+
+     * - 'Not affected'
+       - The processor is not vulnerable.
+     * - 'Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers'
+       - The swapgs protections are disabled; otherwise it has
+         protection in the kernel on a case by case base with explicit
+         pointer sanitation and usercopy LFENCE barriers.
+     * - 'Mitigation: usercopy/swapgs barriers and __user pointer sanitization'
+       - Protection in the kernel on a case by case base with explicit
+         pointer sanitation, usercopy LFENCE barriers, and swapgs LFENCE
+         barriers.
+
+However, the protections are put in place on a case by case basis,
+and there is no guarantee that all possible attack vectors for Spectre
+variant 1 are covered.
+
+The spectre_v2 kernel file reports if the kernel has been compiled with
+retpoline mitigation or if the CPU has hardware mitigation, and if the
+CPU has support for additional process-specific mitigation.
+
+This file also reports CPU features enabled by microcode to mitigate
+attack between user processes:
+
+1. Indirect Branch Prediction Barrier (IBPB) to add additional
+   isolation between processes of different users.
+2. Single Thread Indirect Branch Predictors (STIBP) to add additional
+   isolation between CPU threads running on the same core.
+
+These CPU features may impact performance when used and can be enabled
+per process on a case-by-case base.
+
+The sysfs file showing Spectre variant 2 mitigation status is:
+
+   /sys/devices/system/cpu/vulnerabilities/spectre_v2
+
+The possible values in this file are:
+
+  - Kernel status:
+
+  ========================================  =================================
+  'Not affected'                            The processor is not vulnerable
+  'Mitigation: None'                        Vulnerable, no mitigation
+  'Mitigation: Retpolines'                  Use Retpoline thunks
+  'Mitigation: LFENCE'                      Use LFENCE instructions
+  'Mitigation: Enhanced IBRS'               Hardware-focused mitigation
+  'Mitigation: Enhanced IBRS + Retpolines'  Hardware-focused + Retpolines
+  'Mitigation: Enhanced IBRS + LFENCE'      Hardware-focused + LFENCE
+  ========================================  =================================
+
+  - Firmware status: Show if Indirect Branch Restricted Speculation (IBRS) is
+    used to protect against Spectre variant 2 attacks when calling firmware (x86 only).
+
+  ========== =============================================================
+  'IBRS_FW'  Protection against user program attacks when calling firmware
+  ========== =============================================================
+
+  - Indirect branch prediction barrier (IBPB) status for protection between
+    processes of different users. This feature can be controlled through
+    prctl() per process, or through kernel command line options. This is
+    an x86 only feature. For more details see below.
+
+  ===================   ========================================================
+  'IBPB: disabled'      IBPB unused
+  'IBPB: always-on'     Use IBPB on all tasks
+  'IBPB: conditional'   Use IBPB on SECCOMP or indirect branch restricted tasks
+  ===================   ========================================================
+
+  - Single threaded indirect branch prediction (STIBP) status for protection
+    between different hyper threads. This feature can be controlled through
+    prctl per process, or through kernel command line options. This is an x86
+    only feature. For more details see below.
+
+  ====================  ========================================================
+  'STIBP: disabled'     STIBP unused
+  'STIBP: forced'       Use STIBP on all tasks
+  'STIBP: conditional'  Use STIBP on SECCOMP or indirect branch restricted tasks
+  ====================  ========================================================
+
+  - Return stack buffer (RSB) protection status:
+
+  =============   ===========================================
+  'RSB filling'   Protection of RSB on context switch enabled
+  =============   ===========================================
+
+  - EIBRS Post-barrier Return Stack Buffer (PBRSB) protection status:
+
+  ===========================  =======================================================
+  'PBRSB-eIBRS: SW sequence'   CPU is affected and protection of RSB on VMEXIT enabled
+  'PBRSB-eIBRS: Vulnerable'    CPU is vulnerable
+  'PBRSB-eIBRS: Not affected'  CPU is not affected by PBRSB
+  ===========================  =======================================================
+
+  - Branch History Injection (BHI) protection status:
+
+.. list-table::
+
+ * - BHI: Not affected
+   - System is not affected
+ * - BHI: Retpoline
+   - System is protected by retpoline
+ * - BHI: BHI_DIS_S
+   - System is protected by BHI_DIS_S
+ * - BHI: SW loop, KVM SW loop
+   - System is protected by software clearing sequence
+ * - BHI: Vulnerable
+   - System is vulnerable to BHI
+ * - BHI: Vulnerable, KVM: SW loop
+   - System is vulnerable; KVM is protected by software clearing sequence
+
+Full mitigation might require a microcode update from the CPU
+vendor. When the necessary microcode is not available, the kernel will
+report vulnerability.
+
+Turning on mitigation for Spectre variant 1 and Spectre variant 2
+-----------------------------------------------------------------
+
+1. Kernel mitigation
+^^^^^^^^^^^^^^^^^^^^
+
+Spectre variant 1
+~~~~~~~~~~~~~~~~~
+
+   For the Spectre variant 1, vulnerable kernel code (as determined
+   by code audit or scanning tools) is annotated on a case by case
+   basis to use nospec accessor macros for bounds clipping :ref:`[2]
+   <spec_ref2>` to avoid any usable disclosure gadgets. However, it may
+   not cover all attack vectors for Spectre variant 1.
+
+   Copy-from-user code has an LFENCE barrier to prevent the access_ok()
+   check from being mis-speculated.  The barrier is done by the
+   barrier_nospec() macro.
+
+   For the swapgs variant of Spectre variant 1, LFENCE barriers are
+   added to interrupt, exception and NMI entry where needed.  These
+   barriers are done by the FENCE_SWAPGS_KERNEL_ENTRY and
+   FENCE_SWAPGS_USER_ENTRY macros.
+
+Spectre variant 2
+~~~~~~~~~~~~~~~~~
+
+   For Spectre variant 2 mitigation, the compiler turns indirect calls or
+   jumps in the kernel into equivalent return trampolines (retpolines)
+   :ref:`[3] <spec_ref3>` :ref:`[9] <spec_ref9>` to go to the target
+   addresses.  Speculative execution paths under retpolines are trapped
+   in an infinite loop to prevent any speculative execution jumping to
+   a gadget.
+
+   To turn on retpoline mitigation on a vulnerable CPU, the kernel
+   needs to be compiled with a gcc compiler that supports the
+   -mindirect-branch=thunk-extern -mindirect-branch-register options.
+   If the kernel is compiled with a Clang compiler, the compiler needs
+   to support -mretpoline-external-thunk option.  The kernel config
+   CONFIG_MITIGATION_RETPOLINE needs to be turned on, and the CPU needs
+   to run with the latest updated microcode.
+
+   On Intel Skylake-era systems the mitigation covers most, but not all,
+   cases. See :ref:`[3] <spec_ref3>` for more details.
+
+   On CPUs with hardware mitigation for Spectre variant 2 (e.g. IBRS
+   or enhanced IBRS on x86), retpoline is automatically disabled at run time.
+
+   Systems which support enhanced IBRS (eIBRS) enable IBRS protection once at
+   boot, by setting the IBRS bit, and they're automatically protected against
+   some Spectre v2 variant attacks. The BHB can still influence the choice of
+   indirect branch predictor entry, and although branch predictor entries are
+   isolated between modes when eIBRS is enabled, the BHB itself is not isolated
+   between modes. Systems which support BHI_DIS_S will set it to protect against
+   BHI attacks.
+
+   On Intel's enhanced IBRS systems, this includes cross-thread branch target
+   injections on SMT systems (STIBP). In other words, Intel eIBRS enables
+   STIBP, too.
+
+   AMD Automatic IBRS does not protect userspace, and Legacy IBRS systems clear
+   the IBRS bit on exit to userspace, therefore both explicitly enable STIBP.
+
+   The retpoline mitigation is turned on by default on vulnerable
+   CPUs. It can be forced on or off by the administrator
+   via the kernel command line and sysfs control files. See
+   :ref:`spectre_mitigation_control_command_line`.
+
+   On x86, indirect branch restricted speculation is turned on by default
+   before invoking any firmware code to prevent Spectre variant 2 exploits
+   using the firmware.
+
+   Using kernel address space randomization (CONFIG_RANDOMIZE_BASE=y
+   and CONFIG_SLAB_FREELIST_RANDOM=y in the kernel configuration) makes
+   attacks on the kernel generally more difficult.
+
+2. User program mitigation
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   User programs can mitigate Spectre variant 1 using LFENCE or "bounds
+   clipping". For more details see :ref:`[2] <spec_ref2>`.
+
+   For Spectre variant 2 mitigation, individual user programs
+   can be compiled with return trampolines for indirect branches.
+   This protects them from consuming poisoned entries in the branch
+   target buffer left by malicious software.
+
+   On legacy IBRS systems, at return to userspace, implicit STIBP is disabled
+   because the kernel clears the IBRS bit. In this case, the userspace programs
+   can disable indirect branch speculation via prctl() (See
+   :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
+   On x86, this will turn on STIBP to guard against attacks from the
+   sibling thread when the user program is running, and use IBPB to
+   flush the branch target buffer when switching to/from the program.
+
+   Restricting indirect branch speculation on a user program will
+   also prevent the program from launching a variant 2 attack
+   on x86.  Administrators can change that behavior via the kernel
+   command line and sysfs control files.
+   See :ref:`spectre_mitigation_control_command_line`.
+
+   Programs that disable their indirect branch speculation will have
+   more overhead and run slower.
+
+   User programs should use address space randomization
+   (/proc/sys/kernel/randomize_va_space = 1 or 2) to make attacks more
+   difficult.
+
+3. VM mitigation
+^^^^^^^^^^^^^^^^
+
+   Within the kernel, Spectre variant 1 attacks from rogue guests are
+   mitigated on a case by case basis in VM exit paths. Vulnerable code
+   uses nospec accessor macros for "bounds clipping", to avoid any
+   usable disclosure gadgets.  However, this may not cover all variant
+   1 attack vectors.
+
+   For Spectre variant 2 attacks from rogue guests to the kernel, the
+   Linux kernel uses retpoline or Enhanced IBRS to prevent consumption of
+   poisoned entries in branch target buffer left by rogue guests.  It also
+   flushes the return stack buffer on every VM exit to prevent a return
+   stack buffer underflow so poisoned branch target buffer could be used,
+   or attacker guests leaving poisoned entries in the return stack buffer.
+
+   To mitigate guest-to-guest attacks in the same CPU hardware thread,
+   the branch target buffer is sanitized by flushing before switching
+   to a new guest on a CPU.
+
+   The above mitigations are turned on by default on vulnerable CPUs.
+
+   To mitigate guest-to-guest attacks from sibling thread when SMT is
+   in use, an untrusted guest running in the sibling thread can have
+   its indirect branch speculation disabled by administrator via prctl().
+
+   The kernel also allows guests to use any microcode based mitigation
+   they choose to use (such as IBPB or STIBP on x86) to protect themselves.
+
+.. _spectre_mitigation_control_command_line:
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+In general the kernel selects reasonable default mitigations for the
+current CPU.
+
+Spectre default mitigations can be disabled or changed at the kernel
+command line with the following options:
+
+	- nospectre_v1
+	- nospectre_v2
+	- spectre_v2={option}
+	- spectre_v2_user={option}
+	- spectre_bhi={option}
+
+For more details on the available options, refer to Documentation/admin-guide/kernel-parameters.txt
+
+Mitigation selection guide
+--------------------------
+
+1. Trusted userspace
+^^^^^^^^^^^^^^^^^^^^
+
+   If all userspace applications are from trusted sources and do not
+   execute externally supplied untrusted code, then the mitigations can
+   be disabled.
+
+2. Protect sensitive programs
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   For security-sensitive programs that have secrets (e.g. crypto
+   keys), protection against Spectre variant 2 can be put in place by
+   disabling indirect branch speculation when the program is running
+   (See :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
+
+3. Sandbox untrusted programs
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+   Untrusted programs that could be a source of attacks can be cordoned
+   off by disabling their indirect branch speculation when they are run
+   (See :ref:`Documentation/userspace-api/spec_ctrl.rst <set_spec_ctrl>`).
+   This prevents untrusted programs from polluting the branch target
+   buffer.  This behavior can be changed via the kernel command line
+   and sysfs control files. See
+   :ref:`spectre_mitigation_control_command_line`.
+
+3. High security mode
+^^^^^^^^^^^^^^^^^^^^^
+
+   All Spectre variant 2 mitigations can be forced on
+   at boot time for all programs (See the "on" option in
+   :ref:`spectre_mitigation_control_command_line`).  This will add
+   overhead as indirect branch speculations for all programs will be
+   restricted.
+
+   On x86, branch target buffer will be flushed with IBPB when switching
+   to a new program. STIBP is left on all the time to protect programs
+   against variant 2 attacks originating from programs running on
+   sibling threads.
+
+   Alternatively, STIBP can be used only when running programs
+   whose indirect branch speculation is explicitly disabled,
+   while IBPB is still used all the time when switching to a new
+   program to clear the branch target buffer (See "ibpb" option in
+   :ref:`spectre_mitigation_control_command_line`).  This "ibpb" option
+   has less performance cost than the "on" option, which leaves STIBP
+   on all the time.
+
+References on Spectre
+---------------------
+
+Intel white papers:
+
+.. _spec_ref1:
+
+[1] `Intel analysis of speculative execution side channels <https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/analysis-of-speculative-execution-side-channels-white-paper.pdf>`_.
+
+.. _spec_ref2:
+
+[2] `Bounds check bypass <https://software.intel.com/security-software-guidance/software-guidance/bounds-check-bypass>`_.
+
+.. _spec_ref3:
+
+[3] `Deep dive: Retpoline: A branch target injection mitigation <https://software.intel.com/security-software-guidance/insights/deep-dive-retpoline-branch-target-injection-mitigation>`_.
+
+.. _spec_ref4:
+
+[4] `Deep Dive: Single Thread Indirect Branch Predictors <https://software.intel.com/security-software-guidance/insights/deep-dive-single-thread-indirect-branch-predictors>`_.
+
+AMD white papers:
+
+.. _spec_ref5:
+
+[5] `AMD64 technology indirect branch control extension <https://www.amd.com/content/dam/amd/en/documents/processor-tech-docs/white-papers/111006-architecture-guidelines-update-amd64-technology-indirect-branch-control-extension.pdf>`_.
+
+.. _spec_ref6:
+
+[6] `Software techniques for managing speculation on AMD processors <https://developer.amd.com/wp-content/resources/Managing-Speculation-on-AMD-Processors.pdf>`_.
+
+ARM white papers:
+
+.. _spec_ref7:
+
+[7] `Cache speculation side-channels <https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/download-the-whitepaper>`_.
+
+.. _spec_ref8:
+
+[8] `Cache speculation issues update <https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/latest-updates/cache-speculation-issues-update>`_.
+
+Google white paper:
+
+.. _spec_ref9:
+
+[9] `Retpoline: a software construct for preventing branch-target-injection <https://support.google.com/faqs/answer/7625886>`_.
+
+MIPS white paper:
+
+.. _spec_ref10:
+
+[10] `MIPS: response on speculative execution and side channel vulnerabilities <https://web.archive.org/web/20220512003005if_/https://www.mips.com/blog/mips-response-on-speculative-execution-and-side-channel-vulnerabilities/>`_.
+
+Academic papers:
+
+.. _spec_ref11:
+
+[11] `Spectre Attacks: Exploiting Speculative Execution <https://spectreattack.com/spectre.pdf>`_.
+
+.. _spec_ref12:
+
+[12] `NetSpectre: Read Arbitrary Memory over Network <https://arxiv.org/abs/1807.10535>`_.
+
+.. _spec_ref13:
+
+[13] `Spectre Returns! Speculation Attacks using the Return Stack Buffer <https://www.usenix.org/system/files/conference/woot18/woot18-paper-koruyeh.pdf>`_.
diff --git a/Documentation/admin-guide/hw-vuln/srso.rst b/Documentation/admin-guide/hw-vuln/srso.rst
new file mode 100644
index 000000000..66af95251
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/srso.rst
@@ -0,0 +1,242 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Speculative Return Stack Overflow (SRSO)
+========================================
+
+This is a mitigation for the speculative return stack overflow (SRSO)
+vulnerability found on AMD processors. The mechanism is by now the well
+known scenario of poisoning CPU functional units - the Branch Target
+Buffer (BTB) and Return Address Predictor (RAP) in this case - and then
+tricking the elevated privilege domain (the kernel) into leaking
+sensitive data.
+
+AMD CPUs predict RET instructions using a Return Address Predictor (aka
+Return Address Stack/Return Stack Buffer). In some cases, a non-architectural
+CALL instruction (i.e., an instruction predicted to be a CALL but is
+not actually a CALL) can create an entry in the RAP which may be used
+to predict the target of a subsequent RET instruction.
+
+The specific circumstances that lead to this varies by microarchitecture
+but the concern is that an attacker can mis-train the CPU BTB to predict
+non-architectural CALL instructions in kernel space and use this to
+control the speculative target of a subsequent kernel RET, potentially
+leading to information disclosure via a speculative side-channel.
+
+The issue is tracked under CVE-2023-20569.
+
+Affected processors
+-------------------
+
+AMD Zen, generations 1-4. That is, all families 0x17 and 0x19. Older
+processors have not been investigated.
+
+System information and options
+------------------------------
+
+First of all, it is required that the latest microcode be loaded for
+mitigations to be effective.
+
+The sysfs file showing SRSO mitigation status is:
+
+  /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow
+
+The possible values in this file are:
+
+ * 'Not affected':
+
+   The processor is not vulnerable
+
+* 'Vulnerable':
+
+   The processor is vulnerable and no mitigations have been applied.
+
+ * 'Vulnerable: No microcode':
+
+   The processor is vulnerable, no microcode extending IBPB
+   functionality to address the vulnerability has been applied.
+
+ * 'Vulnerable: Safe RET, no microcode':
+
+   The "Safe RET" mitigation (see below) has been applied to protect the
+   kernel, but the IBPB-extending microcode has not been applied.  User
+   space tasks may still be vulnerable.
+
+ * 'Vulnerable: Microcode, no safe RET':
+
+   Extended IBPB functionality microcode patch has been applied. It does
+   not address User->Kernel and Guest->Host transitions protection but it
+   does address User->User and VM->VM attack vectors.
+
+   Note that User->User mitigation is controlled by how the IBPB aspect in
+   the Spectre v2 mitigation is selected:
+
+    * conditional IBPB:
+
+      where each process can select whether it needs an IBPB issued
+      around it PR_SPEC_DISABLE/_ENABLE etc, see :doc:`spectre`
+
+    * strict:
+
+      i.e., always on - by supplying spectre_v2_user=on on the kernel
+      command line
+
+   (spec_rstack_overflow=microcode)
+
+ * 'Mitigation: Safe RET':
+
+   Combined microcode/software mitigation. It complements the
+   extended IBPB microcode patch functionality by addressing
+   User->Kernel and Guest->Host transitions protection.
+
+   Selected by default or by spec_rstack_overflow=safe-ret
+
+ * 'Mitigation: IBPB':
+
+   Similar protection as "safe RET" above but employs an IBPB barrier on
+   privilege domain crossings (User->Kernel, Guest->Host).
+
+  (spec_rstack_overflow=ibpb)
+
+ * 'Mitigation: IBPB on VMEXIT':
+
+   Mitigation addressing the cloud provider scenario - the Guest->Host
+   transitions only.
+
+   (spec_rstack_overflow=ibpb-vmexit)
+
+ * 'Mitigation: Reduced Speculation':
+
+   This mitigation gets automatically enabled when the above one "IBPB on
+   VMEXIT" has been selected and the CPU supports the BpSpecReduce bit.
+
+   It gets automatically enabled on machines which have the
+   SRSO_USER_KERNEL_NO=1 CPUID bit. In that case, the code logic is to switch
+   to the above =ibpb-vmexit mitigation because the user/kernel boundary is
+   not affected anymore and thus "safe RET" is not needed.
+
+   After enabling the IBPB on VMEXIT mitigation option, the BpSpecReduce bit
+   is detected (functionality present on all such machines) and that
+   practically overrides IBPB on VMEXIT as it has a lot less performance
+   impact and takes care of the guest->host attack vector too.
+
+In order to exploit vulnerability, an attacker needs to:
+
+ - gain local access on the machine
+
+ - break kASLR
+
+ - find gadgets in the running kernel in order to use them in the exploit
+
+ - potentially create and pin an additional workload on the sibling
+   thread, depending on the microarchitecture (not necessary on fam 0x19)
+
+ - run the exploit
+
+Considering the performance implications of each mitigation type, the
+default one is 'Mitigation: safe RET' which should take care of most
+attack vectors, including the local User->Kernel one.
+
+As always, the user is advised to keep her/his system up-to-date by
+applying software updates regularly.
+
+The default setting will be reevaluated when needed and especially when
+new attack vectors appear.
+
+As one can surmise, 'Mitigation: safe RET' does come at the cost of some
+performance depending on the workload. If one trusts her/his userspace
+and does not want to suffer the performance impact, one can always
+disable the mitigation with spec_rstack_overflow=off.
+
+Similarly, 'Mitigation: IBPB' is another full mitigation type employing
+an indirect branch prediction barrier after having applied the required
+microcode patch for one's system. This mitigation comes also at
+a performance cost.
+
+Mitigation: Safe RET
+--------------------
+
+The mitigation works by ensuring all RET instructions speculate to
+a controlled location, similar to how speculation is controlled in the
+retpoline sequence.  To accomplish this, the __x86_return_thunk forces
+the CPU to mispredict every function return using a 'safe return'
+sequence.
+
+To ensure the safety of this mitigation, the kernel must ensure that the
+safe return sequence is itself free from attacker interference.  In Zen3
+and Zen4, this is accomplished by creating a BTB alias between the
+untraining function srso_alias_untrain_ret() and the safe return
+function srso_alias_safe_ret() which results in evicting a potentially
+poisoned BTB entry and using that safe one for all function returns.
+
+In older Zen1 and Zen2, this is accomplished using a reinterpretation
+technique similar to Retbleed one: srso_untrain_ret() and
+srso_safe_ret().
+
+Checking the safe RET mitigation actually works
+-----------------------------------------------
+
+In case one wants to validate whether the SRSO safe RET mitigation works
+on a kernel, one could use two performance counters
+
+* PMC_0xc8 - Count of RET/RET lw retired
+* PMC_0xc9 - Count of RET/RET lw retired mispredicted
+
+and compare the number of RETs retired properly vs those retired
+mispredicted, in kernel mode. Another way of specifying those events
+is::
+
+        # perf list ex_ret_near_ret
+
+        List of pre-defined events (to be used in -e or -M):
+
+        core:
+          ex_ret_near_ret
+               [Retired Near Returns]
+          ex_ret_near_ret_mispred
+               [Retired Near Returns Mispredicted]
+
+Either the command using the event mnemonics::
+
+        # perf stat -e ex_ret_near_ret:k -e ex_ret_near_ret_mispred:k sleep 10s
+
+or using the raw PMC numbers::
+
+        # perf stat -e cpu/event=0xc8,umask=0/k -e cpu/event=0xc9,umask=0/k sleep 10s
+
+should give the same amount. I.e., every RET retired should be
+mispredicted::
+
+        [root@brent: ~/kernel/linux/tools/perf> ./perf stat -e cpu/event=0xc8,umask=0/k -e cpu/event=0xc9,umask=0/k sleep 10s
+
+         Performance counter stats for 'sleep 10s':
+
+                   137,167      cpu/event=0xc8,umask=0/k
+                   137,173      cpu/event=0xc9,umask=0/k
+
+              10.004110303 seconds time elapsed
+
+               0.000000000 seconds user
+               0.004462000 seconds sys
+
+vs the case when the mitigation is disabled (spec_rstack_overflow=off)
+or not functioning properly, showing usually a lot smaller number of
+mispredicted retired RETs vs the overall count of retired RETs during
+a workload::
+
+       [root@brent: ~/kernel/linux/tools/perf> ./perf stat -e cpu/event=0xc8,umask=0/k -e cpu/event=0xc9,umask=0/k sleep 10s
+
+        Performance counter stats for 'sleep 10s':
+
+                  201,627      cpu/event=0xc8,umask=0/k
+                    4,074      cpu/event=0xc9,umask=0/k
+
+             10.003267252 seconds time elapsed
+
+              0.002729000 seconds user
+              0.000000000 seconds sys
+
+Also, there is a selftest which performs the above, go to
+tools/testing/selftests/x86/ and do::
+
+        make srso
+        ./srso
diff --git a/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
new file mode 100644
index 000000000..444f84e22
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
@@ -0,0 +1,270 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+TAA - TSX Asynchronous Abort
+======================================
+
+TAA is a hardware vulnerability that allows unprivileged speculative access to
+data which is available in various CPU internal buffers by using asynchronous
+aborts within an Intel TSX transactional region.
+
+Affected processors
+-------------------
+
+This vulnerability only affects Intel processors that support Intel
+Transactional Synchronization Extensions (TSX) when the TAA_NO bit (bit 8)
+is 0 in the IA32_ARCH_CAPABILITIES MSR.  On processors where the MDS_NO bit
+(bit 5) is 0 in the IA32_ARCH_CAPABILITIES MSR, the existing MDS mitigations
+also mitigate against TAA.
+
+Whether a processor is affected or not can be read out from the TAA
+vulnerability file in sysfs. See :ref:`tsx_async_abort_sys_info`.
+
+Related CVEs
+------------
+
+The following CVE entry is related to this TAA issue:
+
+   ==============  =====  ===================================================
+   CVE-2019-11135  TAA    TSX Asynchronous Abort (TAA) condition on some
+                          microprocessors utilizing speculative execution may
+                          allow an authenticated user to potentially enable
+                          information disclosure via a side channel with
+                          local access.
+   ==============  =====  ===================================================
+
+Problem
+-------
+
+When performing store, load or L1 refill operations, processors write
+data into temporary microarchitectural structures (buffers). The data in
+those buffers can be forwarded to load operations as an optimization.
+
+Intel TSX is an extension to the x86 instruction set architecture that adds
+hardware transactional memory support to improve performance of multi-threaded
+software. TSX lets the processor expose and exploit concurrency hidden in an
+application due to dynamically avoiding unnecessary synchronization.
+
+TSX supports atomic memory transactions that are either committed (success) or
+aborted. During an abort, operations that happened within the transactional region
+are rolled back. An asynchronous abort takes place, among other options, when a
+different thread accesses a cache line that is also used within the transactional
+region when that access might lead to a data race.
+
+Immediately after an uncompleted asynchronous abort, certain speculatively
+executed loads may read data from those internal buffers and pass it to dependent
+operations. This can be then used to infer the value via a cache side channel
+attack.
+
+Because the buffers are potentially shared between Hyper-Threads cross
+Hyper-Thread attacks are possible.
+
+The victim of a malicious actor does not need to make use of TSX. Only the
+attacker needs to begin a TSX transaction and raise an asynchronous abort
+which in turn potentially leaks data stored in the buffers.
+
+More detailed technical information is available in the TAA specific x86
+architecture section: :ref:`Documentation/arch/x86/tsx_async_abort.rst <tsx_async_abort>`.
+
+
+Attack scenarios
+----------------
+
+Attacks against the TAA vulnerability can be implemented from unprivileged
+applications running on hosts or guests.
+
+As for MDS, the attacker has no control over the memory addresses that can
+be leaked. Only the victim is responsible for bringing data to the CPU. As
+a result, the malicious actor has to sample as much data as possible and
+then postprocess it to try to infer any useful information from it.
+
+A potential attacker only has read access to the data. Also, there is no direct
+privilege escalation by using this technique.
+
+
+.. _tsx_async_abort_sys_info:
+
+TAA system information
+-----------------------
+
+The Linux kernel provides a sysfs interface to enumerate the current TAA status
+of mitigated systems. The relevant sysfs file is:
+
+/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
+
+The possible values in this file are:
+
+.. list-table::
+
+   * - 'Vulnerable'
+     - The CPU is affected by this vulnerability and the microcode and kernel mitigation are not applied.
+   * - 'Vulnerable: Clear CPU buffers attempted, no microcode'
+     - The processor is vulnerable but microcode is not updated. The
+       mitigation is enabled on a best effort basis.
+
+       If the processor is vulnerable but the availability of the microcode
+       based mitigation mechanism is not advertised via CPUID, the kernel
+       selects a best effort mitigation mode. This mode invokes the mitigation
+       instructions without a guarantee that they clear the CPU buffers.
+
+       This is done to address virtualization scenarios where the host has the
+       microcode update applied, but the hypervisor is not yet updated to
+       expose the CPUID to the guest. If the host has updated microcode the
+       protection takes effect; otherwise a few CPU cycles are wasted
+       pointlessly.
+   * - 'Mitigation: Clear CPU buffers'
+     - The microcode has been updated to clear the buffers. TSX is still enabled.
+   * - 'Mitigation: TSX disabled'
+     - TSX is disabled.
+   * - 'Not affected'
+     - The CPU is not affected by this issue.
+
+Mitigation mechanism
+--------------------
+
+The kernel detects the affected CPUs and the presence of the microcode which is
+required. If a CPU is affected and the microcode is available, then the kernel
+enables the mitigation by default.
+
+
+The mitigation can be controlled at boot time via a kernel command line option.
+See :ref:`taa_mitigation_control_command_line`.
+
+Virtualization mitigation
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Affected systems where the host has TAA microcode and TAA is mitigated by
+having disabled TSX previously, are not vulnerable regardless of the status
+of the VMs.
+
+In all other cases, if the host either does not have the TAA microcode or
+the kernel is not mitigated, the system might be vulnerable.
+
+
+.. _taa_mitigation_control_command_line:
+
+Mitigation control on the kernel command line
+---------------------------------------------
+
+The kernel command line allows to control the TAA mitigations at boot time with
+the option "tsx_async_abort=". The valid arguments for this option are:
+
+  ============  =============================================================
+  off		This option disables the TAA mitigation on affected platforms.
+                If the system has TSX enabled (see next parameter) and the CPU
+                is affected, the system is vulnerable.
+
+  full	        TAA mitigation is enabled. If TSX is enabled, on an affected
+                system it will clear CPU buffers on ring transitions. On
+                systems which are MDS-affected and deploy MDS mitigation,
+                TAA is also mitigated. Specifying this option on those
+                systems will have no effect.
+
+  full,nosmt    The same as tsx_async_abort=full, with SMT disabled on
+                vulnerable CPUs that have TSX enabled. This is the complete
+                mitigation. When TSX is disabled, SMT is not disabled because
+                CPU is not vulnerable to cross-thread TAA attacks.
+  ============  =============================================================
+
+Not specifying this option is equivalent to "tsx_async_abort=full". For
+processors that are affected by both TAA and MDS, specifying just
+"tsx_async_abort=off" without an accompanying "mds=off" will have no
+effect as the same mitigation is used for both vulnerabilities.
+
+The kernel command line also allows to control the TSX feature using the
+parameter "tsx=" on CPUs which support TSX control. MSR_IA32_TSX_CTRL is used
+to control the TSX feature and the enumeration of the TSX feature bits (RTM
+and HLE) in CPUID.
+
+The valid options are:
+
+  ============  =============================================================
+  off		Disables TSX on the system.
+
+                Note that this option takes effect only on newer CPUs which are
+                not vulnerable to MDS, i.e., have MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1
+                and which get the new IA32_TSX_CTRL MSR through a microcode
+                update. This new MSR allows for the reliable deactivation of
+                the TSX functionality.
+
+  on		Enables TSX.
+
+                Although there are mitigations for all known security
+                vulnerabilities, TSX has been known to be an accelerator for
+                several previous speculation-related CVEs, and so there may be
+                unknown security risks associated with leaving it enabled.
+
+  auto		Disables TSX if X86_BUG_TAA is present, otherwise enables TSX
+                on the system.
+  ============  =============================================================
+
+Not specifying this option is equivalent to "tsx=off".
+
+The following combinations of the "tsx_async_abort" and "tsx" are possible. For
+affected platforms tsx=auto is equivalent to tsx=off and the result will be:
+
+  =========  ==========================   =========================================
+  tsx=on     tsx_async_abort=full         The system will use VERW to clear CPU
+                                          buffers. Cross-thread attacks are still
+					  possible on SMT machines.
+  tsx=on     tsx_async_abort=full,nosmt   As above, cross-thread attacks on SMT
+                                          mitigated.
+  tsx=on     tsx_async_abort=off          The system is vulnerable.
+  tsx=off    tsx_async_abort=full         TSX might be disabled if microcode
+                                          provides a TSX control MSR. If so,
+					  system is not vulnerable.
+  tsx=off    tsx_async_abort=full,nosmt   Ditto
+  tsx=off    tsx_async_abort=off          ditto
+  =========  ==========================   =========================================
+
+
+For unaffected platforms "tsx=on" and "tsx_async_abort=full" does not clear CPU
+buffers.  For platforms without TSX control (MSR_IA32_ARCH_CAPABILITIES.MDS_NO=0)
+"tsx" command line argument has no effect.
+
+For the affected platforms below table indicates the mitigation status for the
+combinations of CPUID bit MD_CLEAR and IA32_ARCH_CAPABILITIES MSR bits MDS_NO
+and TSX_CTRL_MSR.
+
+  =======  =========  =============  ========================================
+  MDS_NO   MD_CLEAR   TSX_CTRL_MSR   Status
+  =======  =========  =============  ========================================
+    0          0            0        Vulnerable (needs microcode)
+    0          1            0        MDS and TAA mitigated via VERW
+    1          1            0        MDS fixed, TAA vulnerable if TSX enabled
+                                     because MD_CLEAR has no meaning and
+                                     VERW is not guaranteed to clear buffers
+    1          X            1        MDS fixed, TAA can be mitigated by
+                                     VERW or TSX_CTRL_MSR
+  =======  =========  =============  ========================================
+
+Mitigation selection guide
+--------------------------
+
+1. Trusted userspace and guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If all user space applications are from a trusted source and do not execute
+untrusted code which is supplied externally, then the mitigation can be
+disabled. The same applies to virtualized environments with trusted guests.
+
+
+2. Untrusted userspace and guests
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If there are untrusted applications or guests on the system, enabling TSX
+might allow a malicious actor to leak data from the host or from other
+processes running on the same physical core.
+
+If the microcode is available and the TSX is disabled on the host, attacks
+are prevented in a virtualized environment as well, even if the VMs do not
+explicitly enable the mitigation.
+
+
+.. _taa_default_mitigations:
+
+Default mitigations
+-------------------
+
+The kernel's default action for vulnerable processors is:
+
+  - Deploy TSX disable mitigation (tsx_async_abort=full tsx=off).
diff --git a/Documentation/admin-guide/hw-vuln/vmscape.rst b/Documentation/admin-guide/hw-vuln/vmscape.rst
new file mode 100644
index 000000000..d9b9a2b6c
--- /dev/null
+++ b/Documentation/admin-guide/hw-vuln/vmscape.rst
@@ -0,0 +1,110 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+VMSCAPE
+=======
+
+VMSCAPE is a vulnerability that may allow a guest to influence the branch
+prediction in host userspace. It particularly affects hypervisors like QEMU.
+
+Even if a hypervisor may not have any sensitive data like disk encryption keys,
+guest-userspace may be able to attack the guest-kernel using the hypervisor as
+a confused deputy.
+
+Affected processors
+-------------------
+
+The following CPU families are affected by VMSCAPE:
+
+**Intel processors:**
+  - Skylake generation (Parts without Enhanced-IBRS)
+  - Cascade Lake generation - (Parts affected by ITS guest/host separation)
+  - Alder Lake and newer (Parts affected by BHI)
+
+Note that, BHI affected parts that use BHB clearing software mitigation e.g.
+Icelake are not vulnerable to VMSCAPE.
+
+**AMD processors:**
+  - Zen series (families 0x17, 0x19, 0x1a)
+
+** Hygon processors:**
+ - Family 0x18
+
+Mitigation
+----------
+
+Conditional IBPB
+----------------
+
+Kernel tracks when a CPU has run a potentially malicious guest and issues an
+IBPB before the first exit to userspace after VM-exit. If userspace did not run
+between VM-exit and the next VM-entry, no IBPB is issued.
+
+Note that the existing userspace mitigation against Spectre-v2 is effective in
+protecting the userspace. They are insufficient to protect the userspace VMMs
+from a malicious guest. This is because Spectre-v2 mitigations are applied at
+context switch time, while the userspace VMM can run after a VM-exit without a
+context switch.
+
+Vulnerability enumeration and mitigation is not applied inside a guest. This is
+because nested hypervisors should already be deploying IBPB to isolate
+themselves from nested guests.
+
+SMT considerations
+------------------
+
+When Simultaneous Multi-Threading (SMT) is enabled, hypervisors can be
+vulnerable to cross-thread attacks. For complete protection against VMSCAPE
+attacks in SMT environments, STIBP should be enabled.
+
+The kernel will issue a warning if SMT is enabled without adequate STIBP
+protection. Warning is not issued when:
+
+- SMT is disabled
+- STIBP is enabled system-wide
+- Intel eIBRS is enabled (which implies STIBP protection)
+
+System information and options
+------------------------------
+
+The sysfs file showing VMSCAPE mitigation status is:
+
+  /sys/devices/system/cpu/vulnerabilities/vmscape
+
+The possible values in this file are:
+
+ * 'Not affected':
+
+   The processor is not vulnerable to VMSCAPE attacks.
+
+ * 'Vulnerable':
+
+   The processor is vulnerable and no mitigation has been applied.
+
+ * 'Mitigation: IBPB before exit to userspace':
+
+   Conditional IBPB mitigation is enabled. The kernel tracks when a CPU has
+   run a potentially malicious guest and issues an IBPB before the first
+   exit to userspace after VM-exit.
+
+ * 'Mitigation: IBPB on VMEXIT':
+
+   IBPB is issued on every VM-exit. This occurs when other mitigations like
+   RETBLEED or SRSO are already issuing IBPB on VM-exit.
+
+Mitigation control on the kernel command line
+----------------------------------------------
+
+The mitigation can be controlled via the ``vmscape=`` command line parameter:
+
+ * ``vmscape=off``:
+
+   Disable the VMSCAPE mitigation.
+
+ * ``vmscape=ibpb``:
+
+   Enable conditional IBPB mitigation (default when CONFIG_MITIGATION_VMSCAPE=y).
+
+ * ``vmscape=force``:
+
+   Force vulnerability detection and mitigation even on processors that are
+   not known to be affected.
diff --git a/Documentation/admin-guide/hw_random.rst b/Documentation/admin-guide/hw_random.rst
new file mode 100644
index 000000000..bfc39f1cf
--- /dev/null
+++ b/Documentation/admin-guide/hw_random.rst
@@ -0,0 +1,104 @@
+=================================
+Hardware random number generators
+=================================
+
+Introduction
+============
+
+The hw_random framework is software that makes use of a
+special hardware feature on your CPU or motherboard,
+a Random Number Generator (RNG).  The software has two parts:
+a core providing the /dev/hwrng character device and its
+sysfs support, plus a hardware-specific driver that plugs
+into that core.
+
+To make the most effective use of these mechanisms, you
+should download the support software as well.  Download the
+latest version of the "rng-tools" package from:
+
+	https://github.com/nhorman/rng-tools
+
+Those tools use /dev/hwrng to fill the kernel entropy pool,
+which is used internally and exported by the /dev/urandom and
+/dev/random special files.
+
+Theory of operation
+===================
+
+CHARACTER DEVICE.  Using the standard open()
+and read() system calls, you can read random data from
+the hardware RNG device.  This data is NOT CHECKED by any
+fitness tests, and could potentially be bogus (if the
+hardware is faulty or has been tampered with).  Data is only
+output if the hardware "has-data" flag is set, but nevertheless
+a security-conscious person would run fitness tests on the
+data before assuming it is truly random.
+
+The rng-tools package uses such tests in "rngd", and lets you
+run them by hand with a "rngtest" utility.
+
+/dev/hwrng is char device major 10, minor 183.
+
+CLASS DEVICE.  There is a /sys/class/misc/hw_random node with
+two unique attributes, "rng_available" and "rng_current".  The
+"rng_available" attribute lists the hardware-specific drivers
+available, while "rng_current" lists the one which is currently
+connected to /dev/hwrng.  If your system has more than one
+RNG available, you may change the one used by writing a name from
+the list in "rng_available" into "rng_current".
+
+==========================================================================
+
+
+Hardware driver for Intel/AMD/VIA Random Number Generators (RNG)
+	- Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
+	- Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
+
+
+About the Intel RNG hardware, from the firmware hub datasheet
+=============================================================
+
+The Firmware Hub integrates a Random Number Generator (RNG)
+using thermal noise generated from inherently random quantum
+mechanical properties of silicon. When not generating new random
+bits the RNG circuitry will enter a low power state. Intel will
+provide a binary software driver to give third party software
+access to our RNG for use as a security feature. At this time,
+the RNG is only to be used with a system in an OS-present state.
+
+Intel RNG Driver notes
+======================
+
+FIXME: support poll(2)
+
+.. note::
+
+	request_mem_region was removed, for three reasons:
+
+	1) Only one RNG is supported by this driver;
+	2) The location used by the RNG is a fixed location in
+	   MMIO-addressable memory;
+	3) users with properly working BIOS e820 handling will always
+	   have the region in which the RNG is located reserved, so
+	   request_mem_region calls always fail for proper setups.
+	   However, for people who use mem=XX, BIOS e820 information is
+	   **not** in /proc/iomem, and request_mem_region(RNG_ADDR) can
+	   succeed.
+
+Driver details
+==============
+
+Based on:
+	Intel 82802AB/82802AC Firmware Hub (FWH) Datasheet
+	May 1999 Order Number: 290658-002 R
+
+Intel 82802 Firmware Hub:
+	Random Number Generator
+	Programmer's Reference Manual
+	December 1999 Order Number: 298029-001 R
+
+Intel 82802 Firmware HUB Random Number Generator Driver
+	Copyright (c) 2000 Matt Sottek <msottek@quiknet.com>
+
+Special thanks to Matt Sottek.  I did the "guts", he
+did the "brains" and all the testing.
diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
new file mode 100644
index 000000000..cd28dfe91
--- /dev/null
+++ b/Documentation/admin-guide/index.rst
@@ -0,0 +1,192 @@
+=================================================
+The Linux kernel user's and administrator's guide
+=================================================
+
+The following is a collection of user-oriented documents that have been
+added to the kernel over time.  There is, as yet, little overall order or
+organization here — this material was not written to be a single, coherent
+document!  With luck things will improve quickly over time.
+
+General guides to kernel administration
+---------------------------------------
+
+This initial section contains overall information, including the README
+file describing the kernel as a whole, documentation on kernel parameters,
+etc.
+
+.. toctree::
+   :maxdepth: 1
+
+   README
+   devices
+
+   features
+
+A big part of the kernel's administrative interface is the /proc and sysfs
+virtual filesystems; these documents describe how to interact with tem
+
+.. toctree::
+   :maxdepth: 1
+
+   sysfs-rules
+   sysctl/index
+   cputopology
+   abi
+
+Security-related documentation:
+
+.. toctree::
+   :maxdepth: 1
+
+   hw-vuln/index
+   LSM/index
+   perf-security
+
+Booting the kernel
+------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bootconfig
+   kernel-parameters
+   efi-stub
+   initrd
+
+
+Tracking down and identifying problems
+--------------------------------------
+
+Here is a set of documents aimed at users who are trying to track down
+problems and bugs in particular.
+
+.. toctree::
+   :maxdepth: 1
+
+   reporting-issues
+   reporting-regressions
+   quickly-build-trimmed-linux
+   verify-bugs-and-bisect-regressions
+   bug-hunting
+   bug-bisect
+   tainted-kernels
+   ramoops
+   dynamic-debug-howto
+   init
+   kdump/index
+   perf/index
+   pstore-blk
+   clearing-warn-once
+   kernel-per-CPU-kthreads
+   lockup-watchdogs
+   RAS/index
+   sysrq
+
+
+Core-kernel subsystems
+----------------------
+
+These documents describe core-kernel administration interfaces that are
+likely to be of interest on almost any system.
+
+.. toctree::
+   :maxdepth: 1
+
+   cgroup-v2
+   cgroup-v1/index
+   cpu-isolation
+   cpu-load
+   mm/index
+   module-signing
+   namespaces/index
+   numastat
+   pm/index
+   syscall-user-dispatch
+
+Support for non-native binary formats.  Note that some of these
+documents are ... old ...
+
+.. toctree::
+   :maxdepth: 1
+
+   binfmt-misc
+   java
+   mono
+
+
+Block-layer and filesystem administration
+-----------------------------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bcache
+   binderfs
+   blockdev/index
+   cifs/index
+   device-mapper/index
+   ext4
+   filesystem-monitoring
+   nfs/index
+   iostats
+   jfs
+   md
+   ufs
+   xfs
+
+Device-specific guides
+----------------------
+
+How to configure your hardware within your Linux system.
+
+.. toctree::
+   :maxdepth: 1
+
+   acpi/index
+   aoe/index
+   auxdisplay/index
+   braille-console
+   btmrvl
+   dell_rbu
+   edid
+   gpio/index
+   hw_random
+   laptops/index
+   lcd-panel-cgram
+   media/index
+   nvme-multipath
+   parport
+   pnp
+   rapidio
+   rtc
+   serial-console
+   svga
+   thermal/index
+   thunderbolt
+   vga-softcursor
+   video-output
+
+Workload analysis
+-----------------
+
+This is the beginning of a section with information of interest to
+application developers and system integrators doing analysis of the
+Linux kernel for safety critical applications. Documents supporting
+analysis of kernel interactions with applications, and key kernel
+subsystems expectations will be found here.
+
+.. toctree::
+   :maxdepth: 1
+
+   workload-tracing
+
+Everything else
+---------------
+
+A few hard-to-categorize and generally obsolete documents.
+
+.. toctree::
+   :maxdepth: 1
+
+   ldm
+   unicode
diff --git a/Documentation/admin-guide/init.rst b/Documentation/admin-guide/init.rst
new file mode 100644
index 000000000..41f06a091
--- /dev/null
+++ b/Documentation/admin-guide/init.rst
@@ -0,0 +1,48 @@
+Explaining the "No working init found." boot hang message
+=========================================================
+:Authors: Andreas Mohr <andi at lisas period de>
+          Cristian Souza <cristianmsbr at gmail period com>
+
+This document provides some high-level reasons for failure
+(listed roughly in order of execution) to load the init binary.
+
+1) **Unable to mount root FS**: Set "debug" kernel parameter (in bootloader
+   config file or CONFIG_CMDLINE) to get more detailed kernel messages.
+
+2) **init binary doesn't exist on rootfs**: Make sure you have the correct
+   root FS type (and ``root=`` kernel parameter points to the correct
+   partition), required drivers such as storage hardware (such as SCSI or
+   USB!) and filesystem (ext3, jffs2, etc.) are builtin (alternatively as
+   modules, to be pre-loaded by an initrd).
+
+3) **Broken console device**: Possibly a conflict in ``console= setup``
+   --> initial console unavailable. E.g. some serial consoles are unreliable
+   due to serial IRQ issues (e.g. missing interrupt-based configuration).
+   Try using a different ``console= device`` or e.g. ``netconsole=``.
+
+4) **Binary exists but dependencies not available**: E.g. required library
+   dependencies of the init binary such as ``/lib/ld-linux.so.2`` missing or
+   broken. Use ``readelf -d <INIT>|grep NEEDED`` to find out which libraries
+   are required.
+
+5) **Binary cannot be loaded**: Make sure the binary's architecture matches
+   your hardware. E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM
+   hardware. In case you tried loading a non-binary file here (shell script?),
+   you should make sure that the script specifies an interpreter in its
+   shebang header line (``#!/...``) that is fully working (including its
+   library dependencies). And before tackling scripts, better first test a
+   simple non-script binary such as ``/bin/sh`` and confirm its successful
+   execution. To find out more, add code ``to init/main.c`` to display
+   kernel_execve()s return values.
+
+Please extend this explanation whenever you find new failure causes
+(after all loading the init binary is a CRITICAL and hard transition step
+which needs to be made as painless as possible), then submit a patch to LKML.
+Further TODOs:
+
+- Implement the various ``run_init_process()`` invocations via a struct array
+  which can then store the ``kernel_execve()`` result value and on failure
+  log it all by iterating over **all** results (very important usability fix).
+- Try to make the implementation itself more helpful in general, e.g. by
+  providing additional error messages at affected places.
+
diff --git a/Documentation/admin-guide/initrd.rst b/Documentation/admin-guide/initrd.rst
new file mode 100644
index 000000000..6c1660a4c
--- /dev/null
+++ b/Documentation/admin-guide/initrd.rst
@@ -0,0 +1,383 @@
+Using the initial RAM disk (initrd)
+===================================
+
+Written 1996,2000 by Werner Almesberger <werner.almesberger@epfl.ch> and
+Hans Lermen <lermen@fgan.de>
+
+
+initrd provides the capability to load a RAM disk by the boot loader.
+This RAM disk can then be mounted as the root file system and programs
+can be run from it. Afterwards, a new root file system can be mounted
+from a different device. The previous root (from initrd) is then moved
+to a directory and can be subsequently unmounted.
+
+initrd is mainly designed to allow system startup to occur in two phases,
+where the kernel comes up with a minimum set of compiled-in drivers, and
+where additional modules are loaded from initrd.
+
+This document gives a brief overview of the use of initrd. A more detailed
+discussion of the boot process can be found in [#f1]_.
+
+
+Operation
+---------
+
+When using initrd, the system typically boots as follows:
+
+  1) the boot loader loads the kernel and the initial RAM disk
+  2) the kernel converts initrd into a "normal" RAM disk and
+     frees the memory used by initrd
+  3) if the root device is not ``/dev/ram0``, the old (deprecated)
+     change_root procedure is followed. see the "Obsolete root change
+     mechanism" section below.
+  4) root device is mounted. if it is ``/dev/ram0``, the initrd image is
+     then mounted as root
+  5) /sbin/init is executed (this can be any valid executable, including
+     shell scripts; it is run with uid 0 and can do basically everything
+     init can do).
+  6) init mounts the "real" root file system
+  7) init places the root file system at the root directory using the
+     pivot_root system call
+  8) init execs the ``/sbin/init`` on the new root filesystem, performing
+     the usual boot sequence
+  9) the initrd file system is removed
+
+Note that changing the root directory does not involve unmounting it.
+It is therefore possible to leave processes running on initrd during that
+procedure. Also note that file systems mounted under initrd continue to
+be accessible.
+
+
+Boot command-line options
+-------------------------
+
+initrd adds the following new options::
+
+  initrd=<path>    (e.g. LOADLIN)
+
+    Loads the specified file as the initial RAM disk. When using LILO, you
+    have to specify the RAM disk image file in /etc/lilo.conf, using the
+    INITRD configuration variable.
+
+  noinitrd
+
+    initrd data is preserved but it is not converted to a RAM disk and
+    the "normal" root file system is mounted. initrd data can be read
+    from /dev/initrd. Note that the data in initrd can have any structure
+    in this case and doesn't necessarily have to be a file system image.
+    This option is used mainly for debugging.
+
+    Note: /dev/initrd is read-only and it can only be used once. As soon
+    as the last process has closed it, all data is freed and /dev/initrd
+    can't be opened anymore.
+
+  root=/dev/ram0
+
+    initrd is mounted as root, and the normal boot procedure is followed,
+    with the RAM disk mounted as root.
+
+Compressed cpio images
+----------------------
+
+Recent kernels have support for populating a ramdisk from a compressed cpio
+archive. On such systems, the creation of a ramdisk image doesn't need to
+involve special block devices or loopbacks; you merely create a directory on
+disk with the desired initrd content, cd to that directory, and run (as an
+example)::
+
+	find . | cpio --quiet -H newc -o | gzip -9 -n > /boot/imagefile.img
+
+Examining the contents of an existing image file is just as simple::
+
+	mkdir /tmp/imagefile
+	cd /tmp/imagefile
+	gzip -cd /boot/imagefile.img | cpio -imd --quiet
+
+Installation
+------------
+
+First, a directory for the initrd file system has to be created on the
+"normal" root file system, e.g.::
+
+	# mkdir /initrd
+
+The name is not relevant. More details can be found on the
+:manpage:`pivot_root(2)` man page.
+
+If the root file system is created during the boot procedure (i.e. if
+you're building an install floppy), the root file system creation
+procedure should create the ``/initrd`` directory.
+
+If initrd will not be mounted in some cases, its content is still
+accessible if the following device has been created::
+
+	# mknod /dev/initrd b 1 250
+	# chmod 400 /dev/initrd
+
+Second, the kernel has to be compiled with RAM disk support and with
+support for the initial RAM disk enabled. Also, at least all components
+needed to execute programs from initrd (e.g. executable format and file
+system) must be compiled into the kernel.
+
+Third, you have to create the RAM disk image. This is done by creating a
+file system on a block device, copying files to it as needed, and then
+copying the content of the block device to the initrd file. With recent
+kernels, at least three types of devices are suitable for that:
+
+ - a floppy disk (works everywhere but it's painfully slow)
+ - a RAM disk (fast, but allocates physical memory)
+ - a loopback device (the most elegant solution)
+
+We'll describe the loopback device method:
+
+ 1) make sure loopback block devices are configured into the kernel
+ 2) create an empty file system of the appropriate size, e.g.::
+
+	# dd if=/dev/zero of=initrd bs=300k count=1
+	# mke2fs -F -m0 initrd
+
+    (if space is critical, you may want to use the Minix FS instead of Ext2)
+ 3) mount the file system, e.g.::
+
+	# mount -t ext2 -o loop initrd /mnt
+
+ 4) create the console device::
+
+    # mkdir /mnt/dev
+    # mknod /mnt/dev/console c 5 1
+
+ 5) copy all the files that are needed to properly use the initrd
+    environment. Don't forget the most important file, ``/sbin/init``
+
+    .. note:: ``/sbin/init`` permissions must include "x" (execute).
+
+ 6) correct operation the initrd environment can frequently be tested
+    even without rebooting with the command::
+
+	# chroot /mnt /sbin/init
+
+    This is of course limited to initrds that do not interfere with the
+    general system state (e.g. by reconfiguring network interfaces,
+    overwriting mounted devices, trying to start already running demons,
+    etc. Note however that it is usually possible to use pivot_root in
+    such a chroot'ed initrd environment.)
+ 7) unmount the file system::
+
+	# umount /mnt
+
+ 8) the initrd is now in the file "initrd". Optionally, it can now be
+    compressed::
+
+	# gzip -9 initrd
+
+For experimenting with initrd, you may want to take a rescue floppy and
+only add a symbolic link from ``/sbin/init`` to ``/bin/sh``. Alternatively, you
+can try the experimental newlib environment [#f2]_ to create a small
+initrd.
+
+Finally, you have to boot the kernel and load initrd. Almost all Linux
+boot loaders support initrd. Since the boot process is still compatible
+with an older mechanism, the following boot command line parameters
+have to be given::
+
+  root=/dev/ram0 rw
+
+(rw is only necessary if writing to the initrd file system.)
+
+With LOADLIN, you simply execute::
+
+     LOADLIN <kernel> initrd=<disk_image>
+
+e.g.::
+
+	LOADLIN C:\LINUX\BZIMAGE initrd=C:\LINUX\INITRD.GZ root=/dev/ram0 rw
+
+With LILO, you add the option ``INITRD=<path>`` to either the global section
+or to the section of the respective kernel in ``/etc/lilo.conf``, and pass
+the options using APPEND, e.g.::
+
+  image = /bzImage
+    initrd = /boot/initrd.gz
+    append = "root=/dev/ram0 rw"
+
+and run ``/sbin/lilo``
+
+For other boot loaders, please refer to the respective documentation.
+
+Now you can boot and enjoy using initrd.
+
+
+Changing the root device
+------------------------
+
+When finished with its duties, init typically changes the root device
+and proceeds with starting the Linux system on the "real" root device.
+
+The procedure involves the following steps:
+ - mounting the new root file system
+ - turning it into the root file system
+ - removing all accesses to the old (initrd) root file system
+ - unmounting the initrd file system and de-allocating the RAM disk
+
+Mounting the new root file system is easy: it just needs to be mounted on
+a directory under the current root. Example::
+
+	# mkdir /new-root
+	# mount -o ro /dev/hda1 /new-root
+
+The root change is accomplished with the pivot_root system call, which
+is also available via the ``pivot_root`` utility (see :manpage:`pivot_root(8)`
+man page; ``pivot_root`` is distributed with util-linux version 2.10h or higher
+[#f3]_). ``pivot_root`` moves the current root to a directory under the new
+root, and puts the new root at its place. The directory for the old root
+must exist before calling ``pivot_root``. Example::
+
+	# cd /new-root
+	# mkdir initrd
+	# pivot_root . initrd
+
+Now, the init process may still access the old root via its
+executable, shared libraries, standard input/output/error, and its
+current root directory. All these references are dropped by the
+following command::
+
+	# exec chroot . what-follows <dev/console >dev/console 2>&1
+
+Where what-follows is a program under the new root, e.g. ``/sbin/init``
+If the new root file system will be used with udev and has no valid
+``/dev`` directory, udev must be initialized before invoking chroot in order
+to provide ``/dev/console``.
+
+Note: implementation details of pivot_root may change with time. In order
+to ensure compatibility, the following points should be observed:
+
+ - before calling pivot_root, the current directory of the invoking
+   process should point to the new root directory
+ - use . as the first argument, and the _relative_ path of the directory
+   for the old root as the second argument
+ - a chroot program must be available under the old and the new root
+ - chroot to the new root afterwards
+ - use relative paths for dev/console in the exec command
+
+Now, the initrd can be unmounted and the memory allocated by the RAM
+disk can be freed::
+
+	# umount /initrd
+	# blockdev --flushbufs /dev/ram0
+
+It is also possible to use initrd with an NFS-mounted root, see the
+:manpage:`pivot_root(8)` man page for details.
+
+
+Usage scenarios
+---------------
+
+The main motivation for implementing initrd was to allow for modular
+kernel configuration at system installation. The procedure would work
+as follows:
+
+  1) system boots from floppy or other media with a minimal kernel
+     (e.g. support for RAM disks, initrd, a.out, and the Ext2 FS) and
+     loads initrd
+  2) ``/sbin/init`` determines what is needed to (1) mount the "real" root FS
+     (i.e. device type, device drivers, file system) and (2) the
+     distribution media (e.g. CD-ROM, network, tape, ...). This can be
+     done by asking the user, by auto-probing, or by using a hybrid
+     approach.
+  3) ``/sbin/init`` loads the necessary kernel modules
+  4) ``/sbin/init`` creates and populates the root file system (this doesn't
+     have to be a very usable system yet)
+  5) ``/sbin/init`` invokes ``pivot_root`` to change the root file system and
+     execs - via chroot - a program that continues the installation
+  6) the boot loader is installed
+  7) the boot loader is configured to load an initrd with the set of
+     modules that was used to bring up the system (e.g. ``/initrd`` can be
+     modified, then unmounted, and finally, the image is written from
+     ``/dev/ram0`` or ``/dev/rd/0`` to a file)
+  8) now the system is bootable and additional installation tasks can be
+     performed
+
+The key role of initrd here is to reuse the configuration data during
+normal system operation without requiring the use of a bloated "generic"
+kernel or re-compiling or re-linking the kernel.
+
+A second scenario is for installations where Linux runs on systems with
+different hardware configurations in a single administrative domain. In
+such cases, it is desirable to generate only a small set of kernels
+(ideally only one) and to keep the system-specific part of configuration
+information as small as possible. In this case, a common initrd could be
+generated with all the necessary modules. Then, only ``/sbin/init`` or a file
+read by it would have to be different.
+
+A third scenario is more convenient recovery disks, because information
+like the location of the root FS partition doesn't have to be provided at
+boot time, but the system loaded from initrd can invoke a user-friendly
+dialog and it can also perform some sanity checks (or even some form of
+auto-detection).
+
+Last not least, CD-ROM distributors may use it for better installation
+from CD, e.g. by using a boot floppy and bootstrapping a bigger RAM disk
+via initrd from CD; or by booting via a loader like ``LOADLIN`` or directly
+from the CD-ROM, and loading the RAM disk from CD without need of
+floppies.
+
+
+Obsolete root change mechanism
+------------------------------
+
+The following mechanism was used before the introduction of pivot_root.
+Current kernels still support it, but you should _not_ rely on its
+continued availability.
+
+It works by mounting the "real" root device (i.e. the one set with rdev
+in the kernel image or with root=... at the boot command line) as the
+root file system when linuxrc exits. The initrd file system is then
+unmounted, or, if it is still busy, moved to a directory ``/initrd``, if
+such a directory exists on the new root file system.
+
+In order to use this mechanism, you do not have to specify the boot
+command options root, init, or rw. (If specified, they will affect
+the real root file system, not the initrd environment.)
+
+If /proc is mounted, the "real" root device can be changed from within
+linuxrc by writing the number of the new root FS device to the special
+file /proc/sys/kernel/real-root-dev, e.g.::
+
+  # echo 0x301 >/proc/sys/kernel/real-root-dev
+
+Note that the mechanism is incompatible with NFS and similar file
+systems.
+
+This old, deprecated mechanism is commonly called ``change_root``, while
+the new, supported mechanism is called ``pivot_root``.
+
+
+Mixed change_root and pivot_root mechanism
+------------------------------------------
+
+In case you did not want to use ``root=/dev/ram0`` to trigger the pivot_root
+mechanism, you may create both ``/linuxrc`` and ``/sbin/init`` in your initrd
+image.
+
+``/linuxrc`` would contain only the following::
+
+	#! /bin/sh
+	mount -n -t proc proc /proc
+	echo 0x0100 >/proc/sys/kernel/real-root-dev
+	umount -n /proc
+
+Once linuxrc exited, the kernel would mount again your initrd as root,
+this time executing ``/sbin/init``. Again, it would be the duty of this init
+to build the right environment (maybe using the ``root= device`` passed on
+the cmdline) before the final execution of the real ``/sbin/init``.
+
+
+Resources
+---------
+
+.. [#f1] Almesberger, Werner; "Booting Linux: The History and the Future"
+    https://www.almesberger.net/cv/papers/ols2k-9.ps.gz
+.. [#f2] newlib package (experimental), with initrd example
+    https://www.sourceware.org/newlib/
+.. [#f3] util-linux: Miscellaneous utilities for Linux
+    https://www.kernel.org/pub/linux/utils/util-linux/
diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst
new file mode 100644
index 000000000..9453196ad
--- /dev/null
+++ b/Documentation/admin-guide/iostats.rst
@@ -0,0 +1,187 @@
+=====================
+I/O statistics fields
+=====================
+
+The kernel exposes disk statistics via ``/proc/diskstats`` and
+``/sys/block/<device>/stat``. These stats are usually accessed via tools
+such as ``sar`` and ``iostat``.
+
+Here are examples using a disk with two partitions::
+
+   /proc/diskstats:
+     259       0 nvme0n1 255999 814 12369153 47919 996852 81 36123024 425995 0 301795 580470 0 0 0 0 60602 106555
+     259       1 nvme0n1p1 492 813 17572 96 848 81 108288 210 0 76 307 0 0 0 0 0 0
+     259       2 nvme0n1p2 255401 1 12343477 47799 996004 0 36014736 425784 0 344336 473584 0 0 0 0 0 0
+
+   /sys/block/nvme0n1/stat:
+     255999 814 12369153 47919 996858 81 36123056 426009 0 301809 580491 0 0 0 0 60605 106562
+
+   /sys/block/nvme0n1/nvme0n1p1/stat:
+     492 813 17572 96 848 81 108288 210 0 76 307 0 0 0 0 0 0
+
+Both files contain the same 17 statistics. ``/sys/block/<device>/stat``
+contains the fields for ``<device>``. In ``/proc/diskstats`` the fields
+are prefixed with the major and minor device numbers and the device
+name. In the example above, the first stat value for ``nvme0n1`` is
+255999 in both files.
+
+The sysfs ``stat`` file is efficient for monitoring a small, known set
+of disks. If you're tracking a large number of devices,
+``/proc/diskstats`` is often the better choice since it avoids the
+overhead of opening and closing multiple files for each snapshot.
+
+All fields are cumulative, monotonic counters, except for field 9, which
+resets to zero as I/Os complete. The remaining fields reset at boot, on
+device reattachment or reinitialization, or when the underlying counter
+overflows. Applications reading these counters should detect and handle
+resets when comparing stat snapshots.
+
+Each set of stats only applies to the indicated device; if you want
+system-wide stats you'll have to find all the devices and sum them all up.
+
+Field  1 -- # of reads completed (unsigned long)
+    This is the total number of reads completed successfully.
+
+Field  2 -- # of reads merged, field 6 -- # of writes merged (unsigned long)
+    Reads and writes which are adjacent to each other may be merged for
+    efficiency.  Thus two 4K reads may become one 8K read before it is
+    ultimately handed to the disk, and so it will be counted (and queued)
+    as only one I/O.  This field lets you know how often this was done.
+
+Field  3 -- # of sectors read (unsigned long)
+    This is the total number of sectors read successfully.
+
+Field  4 -- # of milliseconds spent reading (unsigned int)
+    This is the total number of milliseconds spent by all reads (as
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
+
+Field  5 -- # of writes completed (unsigned long)
+    This is the total number of writes completed successfully.
+
+Field  6 -- # of writes merged  (unsigned long)
+    See the description of field 2.
+
+Field  7 -- # of sectors written (unsigned long)
+    This is the total number of sectors written successfully.
+
+Field  8 -- # of milliseconds spent writing (unsigned int)
+    This is the total number of milliseconds spent by all writes (as
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
+
+Field  9 -- # of I/Os currently in progress (unsigned int)
+    The only field that should go to zero. Incremented as requests are
+    given to appropriate struct request_queue and decremented as they finish.
+
+Field 10 -- # of milliseconds spent doing I/Os (unsigned int)
+    This field increases so long as field 9 is nonzero.
+
+    Since 5.0 this field counts jiffies when at least one request was
+    started or completed. If request runs more than 2 jiffies then some
+    I/O time might be not accounted in case of concurrent requests.
+
+Field 11 -- weighted # of milliseconds spent doing I/Os (unsigned int)
+    This field is incremented at each I/O start, I/O completion, I/O
+    merge, or read of these stats by the number of I/Os in progress
+    (field 9) times the number of milliseconds spent doing I/O since the
+    last update of this field.  This can provide an easy measure of both
+    I/O completion time and the backlog that may be accumulating.
+
+Field 12 -- # of discards completed (unsigned long)
+    This is the total number of discards completed successfully.
+
+Field 13 -- # of discards merged (unsigned long)
+    See the description of field 2
+
+Field 14 -- # of sectors discarded (unsigned long)
+    This is the total number of sectors discarded successfully.
+
+Field 15 -- # of milliseconds spent discarding (unsigned int)
+    This is the total number of milliseconds spent by all discards (as
+    measured from blk_mq_alloc_request() to __blk_mq_end_request()).
+
+Field 16 -- # of flush requests completed
+    This is the total number of flush requests completed successfully.
+
+    Block layer combines flush requests and executes at most one at a time.
+    This counts flush requests executed by disk. Not tracked for partitions.
+
+Field 17 -- # of milliseconds spent flushing
+    This is the total number of milliseconds spent by all flush requests.
+
+To avoid introducing performance bottlenecks, no locks are held while
+modifying these counters.  This implies that minor inaccuracies may be
+introduced when changes collide, so (for instance) adding up all the
+read I/Os issued per partition should equal those made to the disks ...
+but due to the lack of locking it may only be very close.
+
+In 2.6+, there are counters for each CPU, which make the lack of locking
+almost a non-issue.  When the statistics are read, the per-CPU counters
+are summed (possibly overflowing the unsigned long variable they are
+summed to) and the result given to the user.  There is no convenient
+user interface for accessing the per-CPU counters themselves.
+
+Since 4.19 request times are measured with nanoseconds precision and
+truncated to milliseconds before showing in this interface.
+
+Disks vs Partitions
+-------------------
+
+There were significant changes between 2.4 and 2.6+ in the I/O subsystem.
+As a result, some statistic information disappeared. The translation from
+a disk address relative to a partition to the disk address relative to
+the host disk happens much earlier.  All merges and timings now happen
+at the disk level rather than at both the disk and partition level as
+in 2.4.  Consequently, you'll see a different statistics output on 2.6+ for
+partitions from that for disks.  There are only *four* fields available
+for partitions on 2.6+ machines.  This is reflected in the examples above.
+
+Field  1 -- # of reads issued
+    This is the total number of reads issued to this partition.
+
+Field  2 -- # of sectors read
+    This is the total number of sectors requested to be read from this
+    partition.
+
+Field  3 -- # of writes issued
+    This is the total number of writes issued to this partition.
+
+Field  4 -- # of sectors written
+    This is the total number of sectors requested to be written to
+    this partition.
+
+Note that since the address is translated to a disk-relative one, and no
+record of the partition-relative address is kept, the subsequent success
+or failure of the read cannot be attributed to the partition.  In other
+words, the number of reads for partitions is counted slightly before time
+of queuing for partitions, and at completion for whole disks.  This is
+a subtle distinction that is probably uninteresting for most cases.
+
+More significant is the error induced by counting the numbers of
+reads/writes before merges for partitions and after for disks. Since a
+typical workload usually contains a lot of successive and adjacent requests,
+the number of reads/writes issued can be several times higher than the
+number of reads/writes completed.
+
+In 2.6.25, the full statistic set is again available for partitions and
+disk and partition statistics are consistent again. Since we still don't
+keep record of the partition-relative address, an operation is attributed to
+the partition which contains the first sector of the request after the
+eventual merges. As requests can be merged across partition, this could lead
+to some (probably insignificant) inaccuracy.
+
+Additional notes
+----------------
+
+In 2.6+, sysfs is not mounted by default.  If your distribution of
+Linux hasn't added it already, here's the line you'll want to add to
+your ``/etc/fstab``::
+
+	none /sys sysfs defaults 0 0
+
+
+In 2.6+, all disk statistics were removed from ``/proc/stat``.  In 2.4, they
+appear in both ``/proc/partitions`` and ``/proc/stat``, although the ones in
+``/proc/stat`` take a very different format from those in ``/proc/partitions``
+(see proc(5), if your system has it.)
+
+-- ricklind@us.ibm.com
diff --git a/Documentation/admin-guide/java.rst b/Documentation/admin-guide/java.rst
new file mode 100644
index 000000000..8744e272e
--- /dev/null
+++ b/Documentation/admin-guide/java.rst
@@ -0,0 +1,423 @@
+Java(tm) Binary Kernel Support for Linux v1.03
+----------------------------------------------
+
+Linux beats them ALL! While all other OS's are TALKING about direct
+support of Java Binaries in the OS, Linux is doing it!
+
+You can execute Java applications and Java Applets just like any
+other program after you have done the following:
+
+1) You MUST FIRST install the Java Developers Kit for Linux.
+   The Java on Linux HOWTO gives the details on getting and
+   installing this. This HOWTO can be found at:
+
+	ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/Java-HOWTO
+
+   You should also set up a reasonable CLASSPATH environment
+   variable to use Java applications that make use of any
+   nonstandard classes (not included in the same directory
+   as the application itself).
+
+2) You have to compile BINFMT_MISC either as a module or into
+   the kernel (``CONFIG_BINFMT_MISC``) and set it up properly.
+   If you choose to compile it as a module, you will have
+   to insert it manually with modprobe/insmod, as kmod
+   cannot easily be supported with binfmt_misc.
+   Read the file 'binfmt_misc.txt' in this directory to know
+   more about the configuration process.
+
+3) Add the following configuration items to binfmt_misc
+   (you should really have read ``binfmt_misc.txt`` now):
+   support for Java applications::
+
+     ':Java:M::\xca\xfe\xba\xbe::/usr/local/bin/javawrapper:'
+
+   support for executable Jar files::
+
+     ':ExecutableJAR:E::jar::/usr/local/bin/jarwrapper:'
+
+   support for Java Applets::
+
+     ':Applet:E::html::/usr/bin/appletviewer:'
+
+   or the following, if you want to be more selective::
+
+     ':Applet:M::<!--applet::/usr/bin/appletviewer:'
+
+   Of course you have to fix the path names. The path/file names given in this
+   document match the Debian 2.1 system. (i.e. jdk installed in ``/usr``,
+   custom wrappers from this document in ``/usr/local``)
+
+   Note, that for the more selective applet support you have to modify
+   existing html-files to contain ``<!--applet-->`` in the first line
+   (``<`` has to be the first character!) to let this work!
+
+   For the compiled Java programs you need a wrapper script like the
+   following (this is because Java is broken in case of the filename
+   handling), again fix the path names, both in the script and in the
+   above given configuration string.
+
+   You, too, need the little program after the script. Compile like::
+
+	gcc -O2 -o javaclassname javaclassname.c
+
+   and stick it to ``/usr/local/bin``.
+
+   Both the javawrapper shellscript and the javaclassname program
+   were supplied by Colin J. Watson <cjw44@cam.ac.uk>.
+
+Javawrapper shell script:
+
+.. code-block:: sh
+
+  #!/bin/bash
+  # /usr/local/bin/javawrapper - the wrapper for binfmt_misc/java
+
+  if [ -z "$1" ]; then
+	exec 1>&2
+	echo Usage: $0 class-file
+	exit 1
+  fi
+
+  CLASS=$1
+  FQCLASS=`/usr/local/bin/javaclassname $1`
+  FQCLASSN=`echo $FQCLASS | sed -e 's/^.*\.\([^.]*\)$/\1/'`
+  FQCLASSP=`echo $FQCLASS | sed -e 's-\.-/-g' -e 's-^[^/]*$--' -e 's-/[^/]*$--'`
+
+  # for example:
+  # CLASS=Test.class
+  # FQCLASS=foo.bar.Test
+  # FQCLASSN=Test
+  # FQCLASSP=foo/bar
+
+  unset CLASSBASE
+
+  declare -i LINKLEVEL=0
+
+  while :; do
+	if [ "`basename $CLASS .class`" == "$FQCLASSN" ]; then
+		# See if this directory works straight off
+		cd -L `dirname $CLASS`
+		CLASSDIR=$PWD
+		cd $OLDPWD
+		if echo $CLASSDIR | grep -q "$FQCLASSP$"; then
+			CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."`
+			break;
+		fi
+		# Try dereferencing the directory name
+		cd -P `dirname $CLASS`
+		CLASSDIR=$PWD
+		cd $OLDPWD
+		if echo $CLASSDIR | grep -q "$FQCLASSP$"; then
+			CLASSBASE=`echo $CLASSDIR | sed -e "s.$FQCLASSP$.."`
+			break;
+		fi
+		# If no other possible filename exists
+		if [ ! -L $CLASS ]; then
+			exec 1>&2
+			echo $0:
+			echo "  $CLASS should be in a" \
+			     "directory tree called $FQCLASSP"
+			exit 1
+		fi
+	fi
+	if [ ! -L $CLASS ]; then break; fi
+	# Go down one more level of symbolic links
+	let LINKLEVEL+=1
+	if [ $LINKLEVEL -gt 5 ]; then
+		exec 1>&2
+		echo $0:
+		echo "  Too many symbolic links encountered"
+		exit 1
+	fi
+	CLASS=`ls --color=no -l $CLASS | sed -e 's/^.* \([^ ]*\)$/\1/'`
+  done
+
+  if [ -z "$CLASSBASE" ]; then
+	if [ -z "$FQCLASSP" ]; then
+		GOODNAME=$FQCLASSN.class
+	else
+		GOODNAME=$FQCLASSP/$FQCLASSN.class
+	fi
+	exec 1>&2
+	echo $0:
+	echo "  $FQCLASS should be in a file called $GOODNAME"
+	exit 1
+  fi
+
+  if ! echo $CLASSPATH | grep -q "^\(.*:\)*$CLASSBASE\(:.*\)*"; then
+	# class is not in CLASSPATH, so prepend dir of class to CLASSPATH
+	if [ -z "${CLASSPATH}" ] ; then
+		export CLASSPATH=$CLASSBASE
+	else
+		export CLASSPATH=$CLASSBASE:$CLASSPATH
+	fi
+  fi
+
+  shift
+  /usr/bin/java $FQCLASS "$@"
+
+javaclassname.c:
+
+.. code-block:: c
+
+  /* javaclassname.c
+   *
+   * Extracts the class name from a Java class file; intended for use in a Java
+   * wrapper of the type supported by the binfmt_misc option in the Linux kernel.
+   *
+   * Copyright (C) 1999 Colin J. Watson <cjw44@cam.ac.uk>.
+   *
+   * This program is free software; you can redistribute it and/or modify
+   * it under the terms of the GNU General Public License as published by
+   * the Free Software Foundation; either version 2 of the License, or
+   * (at your option) any later version.
+   *
+   * This program is distributed in the hope that it will be useful,
+   * but WITHOUT ANY WARRANTY; without even the implied warranty of
+   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   * GNU General Public License for more details.
+   *
+   * You should have received a copy of the GNU General Public License
+   * along with this program; if not, write to the Free Software
+   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+   */
+
+  #include <stdlib.h>
+  #include <stdio.h>
+  #include <stdarg.h>
+  #include <sys/types.h>
+
+  /* From Sun's Java VM Specification, as tag entries in the constant pool. */
+
+  #define CP_UTF8 1
+  #define CP_INTEGER 3
+  #define CP_FLOAT 4
+  #define CP_LONG 5
+  #define CP_DOUBLE 6
+  #define CP_CLASS 7
+  #define CP_STRING 8
+  #define CP_FIELDREF 9
+  #define CP_METHODREF 10
+  #define CP_INTERFACEMETHODREF 11
+  #define CP_NAMEANDTYPE 12
+  #define CP_METHODHANDLE 15
+  #define CP_METHODTYPE 16
+  #define CP_INVOKEDYNAMIC 18
+
+  /* Define some commonly used error messages */
+
+  #define seek_error() error("%s: Cannot seek\n", program)
+  #define corrupt_error() error("%s: Class file corrupt\n", program)
+  #define eof_error() error("%s: Unexpected end of file\n", program)
+  #define utf8_error() error("%s: Only ASCII 1-255 supported\n", program);
+
+  char *program;
+
+  long *pool;
+
+  u_int8_t read_8(FILE *classfile);
+  u_int16_t read_16(FILE *classfile);
+  void skip_constant(FILE *classfile, u_int16_t *cur);
+  void error(const char *format, ...);
+  int main(int argc, char **argv);
+
+  /* Reads in an unsigned 8-bit integer. */
+  u_int8_t read_8(FILE *classfile)
+  {
+	int b = fgetc(classfile);
+	if(b == EOF)
+		eof_error();
+	return (u_int8_t)b;
+  }
+
+  /* Reads in an unsigned 16-bit integer. */
+  u_int16_t read_16(FILE *classfile)
+  {
+	int b1, b2;
+	b1 = fgetc(classfile);
+	if(b1 == EOF)
+		eof_error();
+	b2 = fgetc(classfile);
+	if(b2 == EOF)
+		eof_error();
+	return (u_int16_t)((b1 << 8) | b2);
+  }
+
+  /* Reads in a value from the constant pool. */
+  void skip_constant(FILE *classfile, u_int16_t *cur)
+  {
+	u_int16_t len;
+	int seekerr = 1;
+	pool[*cur] = ftell(classfile);
+	switch(read_8(classfile))
+	{
+	case CP_UTF8:
+		len = read_16(classfile);
+		seekerr = fseek(classfile, len, SEEK_CUR);
+		break;
+	case CP_CLASS:
+	case CP_STRING:
+	case CP_METHODTYPE:
+		seekerr = fseek(classfile, 2, SEEK_CUR);
+		break;
+	case CP_METHODHANDLE:
+		seekerr = fseek(classfile, 3, SEEK_CUR);
+		break;
+	case CP_INTEGER:
+	case CP_FLOAT:
+	case CP_FIELDREF:
+	case CP_METHODREF:
+	case CP_INTERFACEMETHODREF:
+	case CP_NAMEANDTYPE:
+	case CP_INVOKEDYNAMIC:
+		seekerr = fseek(classfile, 4, SEEK_CUR);
+		break;
+	case CP_LONG:
+	case CP_DOUBLE:
+		seekerr = fseek(classfile, 8, SEEK_CUR);
+		++(*cur);
+		break;
+	default:
+		corrupt_error();
+	}
+	if(seekerr)
+		seek_error();
+  }
+
+  void error(const char *format, ...)
+  {
+	va_list ap;
+	va_start(ap, format);
+	vfprintf(stderr, format, ap);
+	va_end(ap);
+	exit(1);
+  }
+
+  int main(int argc, char **argv)
+  {
+	FILE *classfile;
+	u_int16_t cp_count, i, this_class, classinfo_ptr;
+	u_int8_t length;
+
+	program = argv[0];
+
+	if(!argv[1])
+		error("%s: Missing input file\n", program);
+	classfile = fopen(argv[1], "rb");
+	if(!classfile)
+		error("%s: Error opening %s\n", program, argv[1]);
+
+	if(fseek(classfile, 8, SEEK_SET))  /* skip magic and version numbers */
+		seek_error();
+	cp_count = read_16(classfile);
+	pool = calloc(cp_count, sizeof(long));
+	if(!pool)
+		error("%s: Out of memory for constant pool\n", program);
+
+	for(i = 1; i < cp_count; ++i)
+		skip_constant(classfile, &i);
+	if(fseek(classfile, 2, SEEK_CUR))	/* skip access flags */
+		seek_error();
+
+	this_class = read_16(classfile);
+	if(this_class < 1 || this_class >= cp_count)
+		corrupt_error();
+	if(!pool[this_class] || pool[this_class] == -1)
+		corrupt_error();
+	if(fseek(classfile, pool[this_class] + 1, SEEK_SET))
+		seek_error();
+
+	classinfo_ptr = read_16(classfile);
+	if(classinfo_ptr < 1 || classinfo_ptr >= cp_count)
+		corrupt_error();
+	if(!pool[classinfo_ptr] || pool[classinfo_ptr] == -1)
+		corrupt_error();
+	if(fseek(classfile, pool[classinfo_ptr] + 1, SEEK_SET))
+		seek_error();
+
+	length = read_16(classfile);
+	for(i = 0; i < length; ++i)
+	{
+		u_int8_t x = read_8(classfile);
+		if((x & 0x80) || !x)
+		{
+			if((x & 0xE0) == 0xC0)
+			{
+				u_int8_t y = read_8(classfile);
+				if((y & 0xC0) == 0x80)
+				{
+					int c = ((x & 0x1f) << 6) + (y & 0x3f);
+					if(c) putchar(c);
+					else utf8_error();
+				}
+				else utf8_error();
+			}
+			else utf8_error();
+		}
+		else if(x == '/') putchar('.');
+		else putchar(x);
+	}
+	putchar('\n');
+	free(pool);
+	fclose(classfile);
+	return 0;
+  }
+
+jarwrapper::
+
+  #!/bin/bash
+  # /usr/local/java/bin/jarwrapper - the wrapper for binfmt_misc/jar
+
+  java -jar $1
+
+
+Now simply ``chmod +x`` the ``.class``, ``.jar`` and/or ``.html`` files you
+want to execute.
+
+To add a Java program to your path best put a symbolic link to the main
+.class file into /usr/bin (or another place you like) omitting the .class
+extension. The directory containing the original .class file will be
+added to your CLASSPATH during execution.
+
+
+To test your new setup, enter in the following simple Java app, and name
+it "HelloWorld.java":
+
+.. code-block:: java
+
+	class HelloWorld {
+		public static void main(String args[]) {
+			System.out.println("Hello World!");
+		}
+	}
+
+Now compile the application with::
+
+	javac HelloWorld.java
+
+Set the executable permissions of the binary file, with::
+
+	chmod 755 HelloWorld.class
+
+And then execute it::
+
+	./HelloWorld.class
+
+
+To execute Java Jar files, simple chmod the ``*.jar`` files to include
+the execution bit, then just do::
+
+       ./Application.jar
+
+
+To execute Java Applets, simple chmod the ``*.html`` files to include
+the execution bit, then just do::
+
+	./Applet.html
+
+
+originally by Brian A. Lantz, brian@lantz.com
+heavily edited for binfmt_misc by Richard Günther
+new scripts by Colin J. Watson <cjw44@cam.ac.uk>
+added executable Jar file support by Kurt Huwig <kurt@iku-netz.de>
diff --git a/Documentation/admin-guide/jfs.rst b/Documentation/admin-guide/jfs.rst
new file mode 100644
index 000000000..9e12d936b
--- /dev/null
+++ b/Documentation/admin-guide/jfs.rst
@@ -0,0 +1,66 @@
+===========================================
+IBM's Journaled File System (JFS) for Linux
+===========================================
+
+JFS Homepage:  http://jfs.sourceforge.net/
+
+The following mount options are supported:
+
+(*) == default
+
+iocharset=name
+                Character set to use for converting from Unicode to
+		ASCII.  The default is to do no conversion.  Use
+		iocharset=utf8 for UTF-8 translations.  This requires
+		CONFIG_NLS_UTF8 to be set in the kernel .config file.
+		iocharset=none specifies the default behavior explicitly.
+
+resize=value
+                Resize the volume to <value> blocks.  JFS only supports
+		growing a volume, not shrinking it.  This option is only
+		valid during a remount, when the volume is mounted
+		read-write.  The resize keyword with no value will grow
+		the volume to the full size of the partition.
+
+nointegrity
+                Do not write to the journal.  The primary use of this option
+		is to allow for higher performance when restoring a volume
+		from backup media.  The integrity of the volume is not
+		guaranteed if the system abnormally abends.
+
+integrity(*)
+                Commit metadata changes to the journal.  Use this option to
+		remount a volume where the nointegrity option was
+		previously specified in order to restore normal behavior.
+
+errors=continue
+                        Keep going on a filesystem error.
+errors=remount-ro(*)
+                        Remount the filesystem read-only on an error.
+errors=panic
+                        Panic and halt the machine if an error occurs.
+
+uid=value
+                Override on-disk uid with specified value
+gid=value
+                Override on-disk gid with specified value
+umask=value
+                Override on-disk umask with specified octal value. For
+                directories, the execute bit will be set if the corresponding
+		read bit is set.
+
+discard=minlen, discard/nodiscard(*)
+                This enables/disables the use of discard/TRIM commands.
+		The discard/TRIM commands are sent to the underlying
+                block device when blocks are freed. This is useful for SSD
+                devices and sparse/thinly-provisioned LUNs.  The FITRIM ioctl
+		command is also available together with the nodiscard option.
+		The value of minlen specifies the minimum blockcount, when
+		a TRIM command to the block device is considered useful.
+		When no value is given to the discard option, it defaults to
+		64 blocks, which means 256KiB in JFS.
+		The minlen value of discard overrides the minlen value given
+		on an FITRIM ioctl().
+
+The JFS mailing list can be subscribed to by using the link labeled
+"Mail list Subscribe" at our web page http://jfs.sourceforge.net/
diff --git a/Documentation/admin-guide/kdump/gdbmacros.txt b/Documentation/admin-guide/kdump/gdbmacros.txt
new file mode 100644
index 000000000..030de95e3
--- /dev/null
+++ b/Documentation/admin-guide/kdump/gdbmacros.txt
@@ -0,0 +1,323 @@
+#
+# This file contains a few gdb macros (user defined commands) to extract
+# useful information from kernel crashdump (kdump) like stack traces of
+# all the processes or a particular process and trapinfo.
+#
+# These macros can be used by copying this file in .gdbinit (put in home
+# directory or current directory) or by invoking gdb command with
+# --command=<command-file-name> option
+#
+# Credits:
+# Alexander Nyberg <alexn@telia.com>
+# V Srivatsa <vatsa@in.ibm.com>
+# Maneesh Soni <maneesh@in.ibm.com>
+#
+
+define bttnobp
+	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+	set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
+	set $init_t=&init_task
+	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+	set var $stacksize = sizeof(union thread_union)
+	while ($next_t != $init_t)
+		set $next_t=(struct task_struct *)$next_t
+		printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+		printf "===================\n"
+		set var $stackp = $next_t.thread.sp
+		set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
+
+		while ($stackp < $stack_top)
+			if (*($stackp) > _stext && *($stackp) < _sinittext)
+				info symbol *($stackp)
+			end
+			set $stackp += 4
+		end
+		set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
+		while ($next_th != $next_t)
+			set $next_th=(struct task_struct *)$next_th
+			printf "\npid %d; comm %s:\n", $next_t.pid, $next_t.comm
+			printf "===================\n"
+			set var $stackp = $next_t.thread.sp
+			set var $stack_top = ($stackp & ~($stacksize - 1)) + stacksize
+
+			while ($stackp < $stack_top)
+				if (*($stackp) > _stext && *($stackp) < _sinittext)
+					info symbol *($stackp)
+				end
+				set $stackp += 4
+			end
+			set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
+		end
+		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+	end
+end
+document bttnobp
+	dump all thread stack traces on a kernel compiled with !CONFIG_FRAME_POINTER
+end
+
+define btthreadstack
+	set var $pid_task = $arg0
+
+	printf "\npid %d; comm %s:\n", $pid_task.pid, $pid_task.comm
+	printf "task struct: "
+	print $pid_task
+	printf "===================\n"
+	set var $stackp = $pid_task.thread.sp
+	set var $stacksize = sizeof(union thread_union)
+	set var $stack_top = ($stackp & ~($stacksize - 1)) + $stacksize
+	set var $stack_bot = ($stackp & ~($stacksize - 1))
+
+	set $stackp = *((unsigned long *) $stackp)
+	while (($stackp < $stack_top) && ($stackp > $stack_bot))
+		set var $addr = *(((unsigned long *) $stackp) + 1)
+		info symbol $addr
+		set $stackp = *((unsigned long *) $stackp)
+	end
+end
+document btthreadstack
+	 dump a thread stack using the given task structure pointer
+end
+
+
+define btt
+	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+	set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
+	set $init_t=&init_task
+	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+	while ($next_t != $init_t)
+		set $next_t=(struct task_struct *)$next_t
+		btthreadstack $next_t
+
+		set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
+		while ($next_th != $next_t)
+			set $next_th=(struct task_struct *)$next_th
+			btthreadstack $next_th
+			set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
+		end
+		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+	end
+end
+document btt
+	dump all thread stack traces on a kernel compiled with CONFIG_FRAME_POINTER
+end
+
+define btpid
+	set var $pid = $arg0
+	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+	set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
+	set $init_t=&init_task
+	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+	set var $pid_task = 0
+
+	while ($next_t != $init_t)
+		set $next_t=(struct task_struct *)$next_t
+
+		if ($next_t.pid == $pid)
+			set $pid_task = $next_t
+		end
+
+		set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
+		while ($next_th != $next_t)
+			set $next_th=(struct task_struct *)$next_th
+			if ($next_th.pid == $pid)
+				set $pid_task = $next_th
+			end
+			set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
+		end
+		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+	end
+
+	btthreadstack $pid_task
+end
+document btpid
+	backtrace of pid
+end
+
+
+define trapinfo
+	set var $pid = $arg0
+	set $tasks_off=((size_t)&((struct task_struct *)0)->tasks)
+	set $pid_off=((size_t)&((struct task_struct *)0)->thread_group.next)
+	set $init_t=&init_task
+	set $next_t=(((char *)($init_t->tasks).next) - $tasks_off)
+	set var $pid_task = 0
+
+	while ($next_t != $init_t)
+		set $next_t=(struct task_struct *)$next_t
+
+		if ($next_t.pid == $pid)
+			set $pid_task = $next_t
+		end
+
+		set $next_th=(((char *)$next_t->thread_group.next) - $pid_off)
+		while ($next_th != $next_t)
+			set $next_th=(struct task_struct *)$next_th
+			if ($next_th.pid == $pid)
+				set $pid_task = $next_th
+			end
+			set $next_th=(((char *)$next_th->thread_group.next) - $pid_off)
+		end
+		set $next_t=(char *)($next_t->tasks.next) - $tasks_off
+	end
+
+	printf "Trapno %ld, cr2 0x%lx, error_code %ld\n", $pid_task.thread.trap_no, \
+				$pid_task.thread.cr2, $pid_task.thread.error_code
+
+end
+document trapinfo
+	Run info threads and lookup pid of thread #1
+	'trapinfo <pid>' will tell you by which trap & possibly
+	address the kernel panicked.
+end
+
+define dump_record
+	set var $desc = $arg0
+	set var $info = $arg1
+	if ($argc > 2)
+		set var $prev_flags = $arg2
+	else
+		set var $prev_flags = 0
+	end
+
+	set var $prefix = 1
+	set var $newline = 1
+
+	set var $begin = $desc->text_blk_lpos.begin % (1U << prb->text_data_ring.size_bits)
+	set var $next = $desc->text_blk_lpos.next % (1U << prb->text_data_ring.size_bits)
+
+	# handle data-less record
+	if ($begin & 1)
+		set var $text_len = 0
+		set var $log = ""
+	else
+		# handle wrapping data block
+		if ($begin > $next)
+			set var $begin = 0
+		end
+
+		# skip over descriptor id
+		set var $begin = $begin + sizeof(long)
+
+		# handle truncated message
+		if ($next - $begin < $info->text_len)
+			set var $text_len = $next - $begin
+		else
+			set var $text_len = $info->text_len
+		end
+
+		set var $log = &prb->text_data_ring.data[$begin]
+	end
+
+	# prev & LOG_CONT && !(info->flags & LOG_PREIX)
+	if (($prev_flags & 8) && !($info->flags & 4))
+		set var $prefix = 0
+	end
+
+	# info->flags & LOG_CONT
+	if ($info->flags & 8)
+		# (prev & LOG_CONT && !(prev & LOG_NEWLINE))
+		if (($prev_flags & 8) && !($prev_flags & 2))
+			set var $prefix = 0
+		end
+		# (!(info->flags & LOG_NEWLINE))
+		if (!($info->flags & 2))
+			set var $newline = 0
+		end
+	end
+
+	if ($prefix)
+		printf "[%5lu.%06lu] ", $info->ts_nsec / 1000000000, $info->ts_nsec % 1000000000
+	end
+	if ($text_len)
+		eval "printf \"%%%d.%ds\", $log", $text_len, $text_len
+	end
+	if ($newline)
+		printf "\n"
+	end
+
+	# handle dictionary data
+
+	set var $dict = &$info->dev_info.subsystem[0]
+	set var $dict_len = sizeof($info->dev_info.subsystem)
+	if ($dict[0] != '\0')
+		printf " SUBSYSTEM="
+		set var $idx = 0
+		while ($idx < $dict_len)
+			set var $c = $dict[$idx]
+			if ($c == '\0')
+				loop_break
+			else
+				if ($c < ' ' || $c >= 127 || $c == '\\')
+					printf "\\x%02x", $c
+				else
+					printf "%c", $c
+				end
+			end
+			set var $idx = $idx + 1
+		end
+		printf "\n"
+	end
+
+	set var $dict = &$info->dev_info.device[0]
+	set var $dict_len = sizeof($info->dev_info.device)
+	if ($dict[0] != '\0')
+		printf " DEVICE="
+		set var $idx = 0
+		while ($idx < $dict_len)
+			set var $c = $dict[$idx]
+			if ($c == '\0')
+				loop_break
+			else
+				if ($c < ' ' || $c >= 127 || $c == '\\')
+					printf "\\x%02x", $c
+				else
+					printf "%c", $c
+				end
+			end
+			set var $idx = $idx + 1
+		end
+		printf "\n"
+	end
+end
+document dump_record
+	Dump a single record. The first parameter is the descriptor,
+	the second parameter is the info, the third parameter is
+	optional and specifies the previous record's flags, used for
+	properly formatting continued lines.
+end
+
+define dmesg
+	# definitions from kernel/printk/printk_ringbuffer.h
+	set var $desc_committed = 1
+	set var $desc_finalized = 2
+	set var $desc_sv_bits = sizeof(long) * 8
+	set var $desc_flags_shift = $desc_sv_bits - 2
+	set var $desc_flags_mask = 3 << $desc_flags_shift
+	set var $id_mask = ~$desc_flags_mask
+
+	set var $desc_count = 1U << prb->desc_ring.count_bits
+	set var $prev_flags = 0
+
+	set var $id = prb->desc_ring.tail_id.counter
+	set var $end_id = prb->desc_ring.head_id.counter
+
+	while (1)
+		set var $desc = &prb->desc_ring.descs[$id % $desc_count]
+		set var $info = &prb->desc_ring.infos[$id % $desc_count]
+
+		# skip non-committed record
+		set var $state = 3 & ($desc->state_var.counter >> $desc_flags_shift)
+		if ($state == $desc_committed || $state == $desc_finalized)
+			dump_record $desc $info $prev_flags
+			set var $prev_flags = $info->flags
+		end
+
+		if ($id == $end_id)
+			loop_break
+		end
+		set var $id = ($id + 1) & $id_mask
+	end
+end
+document dmesg
+	print the kernel ring buffer
+end
diff --git a/Documentation/admin-guide/kdump/index.rst b/Documentation/admin-guide/kdump/index.rst
new file mode 100644
index 000000000..cf5d7c868
--- /dev/null
+++ b/Documentation/admin-guide/kdump/index.rst
@@ -0,0 +1,13 @@
+
+================================================================
+Documentation for Kdump - The kexec-based Crash Dumping Solution
+================================================================
+
+This document includes overview, setup and installation, and analysis
+information.
+
+.. toctree::
+    :maxdepth: 1
+
+    kdump
+    vmcoreinfo
diff --git a/Documentation/admin-guide/kdump/kdump.rst b/Documentation/admin-guide/kdump/kdump.rst
new file mode 100644
index 000000000..7587caadb
--- /dev/null
+++ b/Documentation/admin-guide/kdump/kdump.rst
@@ -0,0 +1,612 @@
+================================================================
+Documentation for Kdump - The kexec-based Crash Dumping Solution
+================================================================
+
+This document includes overview, setup, installation, and analysis
+information.
+
+Overview
+========
+
+Kdump uses kexec to quickly boot to a dump-capture kernel whenever a
+dump of the system kernel's memory needs to be taken (for example, when
+the system panics). The system kernel's memory image is preserved across
+the reboot and is accessible to the dump-capture kernel.
+
+You can use common commands, such as cp, scp or makedumpfile to copy
+the memory image to a dump file on the local disk, or across the network
+to a remote system.
+
+Kdump and kexec are currently supported on the x86, x86_64, ppc64,
+s390x, arm and arm64 architectures.
+
+When the system kernel boots, it reserves a small section of memory for
+the dump-capture kernel. This ensures that ongoing Direct Memory Access
+(DMA) from the system kernel does not corrupt the dump-capture kernel.
+The kexec -p command loads the dump-capture kernel into this reserved
+memory.
+
+On x86 machines, the first 640 KB of physical memory is needed for boot,
+regardless of where the kernel loads. For simpler handling, the whole
+low 1M is reserved to avoid any later kernel or device driver writing
+data into this area. Like this, the low 1M can be reused as system RAM
+by kdump kernel without extra handling.
+
+On PPC64 machines first 32KB of physical memory is needed for booting
+regardless of where the kernel is loaded and to support 64K page size
+kexec backs up the first 64KB memory.
+
+For s390x, when kdump is triggered, the crashkernel region is exchanged
+with the region [0, crashkernel region size] and then the kdump kernel
+runs in [0, crashkernel region size]. Therefore no relocatable kernel is
+needed for s390x.
+
+All of the necessary information about the system kernel's core image is
+encoded in the ELF format, and stored in a reserved area of memory
+before a crash. The physical address of the start of the ELF header is
+passed to the dump-capture kernel through the elfcorehdr= boot
+parameter. Optionally the size of the ELF header can also be passed
+when using the elfcorehdr=[size[KMG]@]offset[KMG] syntax.
+
+With the dump-capture kernel, you can access the memory image through
+/proc/vmcore. This exports the dump as an ELF-format file that you can
+write out using file copy commands such as cp or scp. You can also use
+makedumpfile utility to analyze and write out filtered contents with
+options, e.g with '-d 31' it will only write out kernel data. Further,
+you can use analysis tools such as the GNU Debugger (GDB) and the Crash
+tool to debug the dump file. This method ensures that the dump pages are
+correctly ordered.
+
+Setup and Installation
+======================
+
+Install kexec-tools
+-------------------
+
+1) Login as the root user.
+
+2) Download the kexec-tools user-space package from the following URL:
+
+http://kernel.org/pub/linux/utils/kernel/kexec/kexec-tools.tar.gz
+
+This is a symlink to the latest version.
+
+The latest kexec-tools git tree is available at:
+
+- git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
+- http://www.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git
+
+There is also a gitweb interface available at
+http://www.kernel.org/git/?p=utils/kernel/kexec/kexec-tools.git
+
+More information about kexec-tools can be found at
+http://horms.net/projects/kexec/
+
+3) Unpack the tarball with the tar command, as follows::
+
+	tar xvpzf kexec-tools.tar.gz
+
+4) Change to the kexec-tools directory, as follows::
+
+	cd kexec-tools-VERSION
+
+5) Configure the package, as follows::
+
+	./configure
+
+6) Compile the package, as follows::
+
+	make
+
+7) Install the package, as follows::
+
+	make install
+
+
+Build the system and dump-capture kernels
+-----------------------------------------
+There are two possible methods of using Kdump.
+
+1) Build a separate custom dump-capture kernel for capturing the
+   kernel core dump.
+
+2) Or use the system kernel binary itself as dump-capture kernel and there is
+   no need to build a separate dump-capture kernel. This is possible
+   only with the architectures which support a relocatable kernel. As
+   of today, i386, x86_64, ppc64, arm and arm64 architectures support
+   relocatable kernel.
+
+Building a relocatable kernel is advantageous from the point of view that
+one does not have to build a second kernel for capturing the dump. But
+at the same time one might want to build a custom dump capture kernel
+suitable to his needs.
+
+Following are the configuration setting required for system and
+dump-capture kernels for enabling kdump support.
+
+System kernel config options
+----------------------------
+
+1) Enable "kexec system call" or "kexec file based system call" in
+   "Processor type and features."::
+
+	CONFIG_KEXEC=y or CONFIG_KEXEC_FILE=y
+
+   And both of them will select KEXEC_CORE::
+
+	CONFIG_KEXEC_CORE=y
+
+2) Enable "sysfs file system support" in "Filesystem" -> "Pseudo
+   filesystems." This is usually enabled by default::
+
+	CONFIG_SYSFS=y
+
+   Note that "sysfs file system support" might not appear in the "Pseudo
+   filesystems" menu if "Configure standard kernel features (expert users)"
+   is not enabled in "General Setup." In this case, check the .config file
+   itself to ensure that sysfs is turned on, as follows::
+
+	grep 'CONFIG_SYSFS' .config
+
+3) Enable "Compile the kernel with debug info" in "Kernel hacking."::
+
+	CONFIG_DEBUG_INFO=Y
+
+   This causes the kernel to be built with debug symbols. The dump
+   analysis tools require a vmlinux with debug symbols in order to read
+   and analyze a dump file.
+
+Dump-capture kernel config options (Arch Independent)
+-----------------------------------------------------
+
+1) Enable "kernel crash dumps" support under "Processor type and
+   features"::
+
+	CONFIG_CRASH_DUMP=y
+
+   And this will select VMCORE_INFO and CRASH_RESERVE::
+	CONFIG_VMCORE_INFO=y
+	CONFIG_CRASH_RESERVE=y
+
+2) Enable "/proc/vmcore support" under "Filesystems" -> "Pseudo filesystems"::
+
+	CONFIG_PROC_VMCORE=y
+
+   (CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
+
+Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
+--------------------------------------------------------------------
+
+1) On i386, enable high memory support under "Processor type and
+   features"::
+
+	CONFIG_HIGHMEM4G
+
+2) With CONFIG_SMP=y, usually nr_cpus=1 need specified on the kernel
+   command line when loading the dump-capture kernel because one
+   CPU is enough for kdump kernel to dump vmcore on most of systems.
+
+   However, you can also specify nr_cpus=X to enable multiple processors
+   in kdump kernel.
+
+   With CONFIG_SMP=n, the above things are not related.
+
+3) A relocatable kernel is suggested to be built by default. If not yet,
+   enable "Build a relocatable kernel" support under "Processor type and
+   features"::
+
+	CONFIG_RELOCATABLE=y
+
+4) Use a suitable value for "Physical address where the kernel is
+   loaded" (under "Processor type and features"). This only appears when
+   "kernel crash dumps" is enabled. A suitable value depends upon
+   whether kernel is relocatable or not.
+
+   If you are using a relocatable kernel use CONFIG_PHYSICAL_START=0x100000
+   This will compile the kernel for physical address 1MB, but given the fact
+   kernel is relocatable, it can be run from any physical address hence
+   kexec boot loader will load it in memory region reserved for dump-capture
+   kernel.
+
+   Otherwise it should be the start of memory region reserved for
+   second kernel using boot parameter "crashkernel=Y@X". Here X is
+   start of memory region reserved for dump-capture kernel.
+   Generally X is 16MB (0x1000000). So you can set
+   CONFIG_PHYSICAL_START=0x1000000
+
+5) Make and install the kernel and its modules. DO NOT add this kernel
+   to the boot loader configuration files.
+
+Dump-capture kernel config options (Arch Dependent, ppc64)
+----------------------------------------------------------
+
+1) Enable "Build a kdump crash kernel" support under "Kernel" options::
+
+	CONFIG_CRASH_DUMP=y
+
+2)   Enable "Build a relocatable kernel" support::
+
+	CONFIG_RELOCATABLE=y
+
+   Make and install the kernel and its modules.
+
+Dump-capture kernel config options (Arch Dependent, arm)
+----------------------------------------------------------
+
+-   To use a relocatable kernel,
+    Enable "AUTO_ZRELADDR" support under "Boot" options::
+
+	AUTO_ZRELADDR=y
+
+Dump-capture kernel config options (Arch Dependent, arm64)
+----------------------------------------------------------
+
+- Please note that kvm of the dump-capture kernel will not be enabled
+  on non-VHE systems even if it is configured. This is because the CPU
+  will not be reset to EL2 on panic.
+
+crashkernel syntax
+===========================
+1) crashkernel=size@offset
+
+   Here 'size' specifies how much memory to reserve for the dump-capture kernel
+   and 'offset' specifies the beginning of this reserved memory. For example,
+   "crashkernel=64M@16M" tells the system kernel to reserve 64 MB of memory
+   starting at physical address 0x01000000 (16MB) for the dump-capture kernel.
+
+   The crashkernel region can be automatically placed by the system
+   kernel at run time. This is done by specifying the base address as 0,
+   or omitting it all together::
+
+         crashkernel=256M@0
+
+   or::
+
+         crashkernel=256M
+
+   If the start address is specified, note that the start address of the
+   kernel will be aligned to a value (which is Arch dependent), so if the
+   start address is not then any space below the alignment point will be
+   wasted.
+
+2) range1:size1[,range2:size2,...][@offset]
+
+   While the "crashkernel=size[@offset]" syntax is sufficient for most
+   configurations, sometimes it's handy to have the reserved memory dependent
+   on the value of System RAM -- that's mostly for distributors that pre-setup
+   the kernel command line to avoid a unbootable system after some memory has
+   been removed from the machine.
+
+   The syntax is::
+
+       crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
+       range=start-[end]
+
+   For example::
+
+       crashkernel=512M-2G:64M,2G-:128M
+
+   This would mean:
+
+       1) if the RAM is smaller than 512M, then don't reserve anything
+          (this is the "rescue" case)
+       2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
+       3) if the RAM size is larger than 2G, then reserve 128M
+
+3) crashkernel=size,high and crashkernel=size,low
+
+   If memory above 4G is preferred, crashkernel=size,high can be used to
+   fulfill that. With it, physical memory is allowed to be allocated from top,
+   so could be above 4G if system has more than 4G RAM installed. Otherwise,
+   memory region will be allocated below 4G if available.
+
+   When crashkernel=X,high is passed, kernel could allocate physical memory
+   region above 4G, low memory under 4G is needed in this case. There are
+   three ways to get low memory:
+
+      1) Kernel will allocate at least 256M memory below 4G automatically
+         if crashkernel=Y,low is not specified.
+      2) Let user specify low memory size instead.
+      3) Specified value 0 will disable low memory allocation::
+
+            crashkernel=0,low
+
+4) crashkernel=size,cma
+
+	Reserve additional crash kernel memory from CMA. This reservation is
+	usable by the first system's userspace memory and kernel movable
+	allocations (memory balloon, zswap). Pages allocated from this memory
+	range will not be included in the vmcore so this should not be used if
+	dumping of userspace memory is intended and it has to be expected that
+	some movable kernel pages may be missing from the dump.
+
+	A standard crashkernel reservation, as described above, is still needed
+	to hold the crash kernel and initrd.
+
+	This option increases the risk of a kdump failure: DMA transfers
+	configured by the first kernel may end up corrupting the second
+	kernel's memory.
+
+	This reservation method is intended for systems that can't afford to
+	sacrifice enough memory for standard crashkernel reservation and where
+	less reliable and possibly incomplete kdump is preferable to no kdump at
+	all.
+
+Boot into System Kernel
+-----------------------
+1) Update the boot loader (such as grub, yaboot, or lilo) configuration
+   files as necessary.
+
+2) Boot the system kernel with the boot parameter "crashkernel=Y@X".
+
+   On x86 and x86_64, use "crashkernel=Y[@X]". Most of the time, the
+   start address 'X' is not necessary, kernel will search a suitable
+   area. Unless an explicit start address is expected.
+
+   On ppc64, use "crashkernel=128M@32M".
+
+   On s390x, typically use "crashkernel=xxM". The value of xx is dependent
+   on the memory consumption of the kdump system. In general this is not
+   dependent on the memory size of the production system.
+
+   On arm, the use of "crashkernel=Y@X" is no longer necessary; the
+   kernel will automatically locate the crash kernel image within the
+   first 512MB of RAM if X is not given.
+
+   On arm64, use "crashkernel=Y[@X]".  Note that the start address of
+   the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000).
+
+Load the Dump-capture Kernel
+============================
+
+After booting to the system kernel, dump-capture kernel needs to be
+loaded.
+
+Based on the architecture and type of image (relocatable or not), one
+can choose to load the uncompressed vmlinux or compressed bzImage/vmlinuz
+of dump-capture kernel. Following is the summary.
+
+For i386 and x86_64:
+
+	- Use bzImage/vmlinuz if kernel is relocatable.
+	- Use vmlinux if kernel is not relocatable.
+
+For ppc64:
+
+	- Use vmlinux
+
+For s390x:
+
+	- Use image or bzImage
+
+For arm:
+
+	- Use zImage
+
+For arm64:
+
+	- Use vmlinux or Image
+
+If you are using an uncompressed vmlinux image then use following command
+to load dump-capture kernel::
+
+   kexec -p <dump-capture-kernel-vmlinux-image> \
+   --initrd=<initrd-for-dump-capture-kernel> --args-linux \
+   --append="root=<root-dev> <arch-specific-options>"
+
+If you are using a compressed bzImage/vmlinuz, then use following command
+to load dump-capture kernel::
+
+   kexec -p <dump-capture-kernel-bzImage> \
+   --initrd=<initrd-for-dump-capture-kernel> \
+   --append="root=<root-dev> <arch-specific-options>"
+
+If you are using a compressed zImage, then use following command
+to load dump-capture kernel::
+
+   kexec --type zImage -p <dump-capture-kernel-bzImage> \
+   --initrd=<initrd-for-dump-capture-kernel> \
+   --dtb=<dtb-for-dump-capture-kernel> \
+   --append="root=<root-dev> <arch-specific-options>"
+
+If you are using an uncompressed Image, then use following command
+to load dump-capture kernel::
+
+   kexec -p <dump-capture-kernel-Image> \
+   --initrd=<initrd-for-dump-capture-kernel> \
+   --append="root=<root-dev> <arch-specific-options>"
+
+Following are the arch specific command line options to be used while
+loading dump-capture kernel.
+
+For i386 and x86_64:
+
+	"1 irqpoll nr_cpus=1 reset_devices"
+
+For ppc64:
+
+	"1 maxcpus=1 noirqdistrib reset_devices"
+
+For s390x:
+
+	"1 nr_cpus=1 cgroup_disable=memory"
+
+For arm:
+
+	"1 maxcpus=1 reset_devices"
+
+For arm64:
+
+	"1 nr_cpus=1 reset_devices"
+
+Notes on loading the dump-capture kernel:
+
+* By default, the ELF headers are stored in ELF64 format to support
+  systems with more than 4GB memory. On i386, kexec automatically checks if
+  the physical RAM size exceeds the 4 GB limit and if not, uses ELF32.
+  So, on non-PAE systems, ELF32 is always used.
+
+  The --elf32-core-headers option can be used to force the generation of ELF32
+  headers. This is necessary because GDB currently cannot open vmcore files
+  with ELF64 headers on 32-bit systems.
+
+* The "irqpoll" boot parameter reduces driver initialization failures
+  due to shared interrupts in the dump-capture kernel.
+
+* You must specify <root-dev> in the format corresponding to the root
+  device name in the output of mount command.
+
+* Boot parameter "1" boots the dump-capture kernel into single-user
+  mode without networking. If you want networking, use "3".
+
+* We generally don't have to bring up a SMP kernel just to capture the
+  dump. Hence generally it is useful either to build a UP dump-capture
+  kernel or specify maxcpus=1 option while loading dump-capture kernel.
+  Note, though maxcpus always works, you had better replace it with
+  nr_cpus to save memory if supported by the current ARCH, such as x86.
+
+* You should enable multi-cpu support in dump-capture kernel if you intend
+  to use multi-thread programs with it, such as parallel dump feature of
+  makedumpfile. Otherwise, the multi-thread program may have a great
+  performance degradation. To enable multi-cpu support, you should bring up an
+  SMP dump-capture kernel and specify maxcpus/nr_cpus options while loading it.
+
+* For s390x there are two kdump modes: If an ELF header is specified with
+  the elfcorehdr= kernel parameter, it is used by the kdump kernel as it
+  is done on all other architectures. If no elfcorehdr= kernel parameter is
+  specified, the s390x kdump kernel dynamically creates the header. The
+  second mode has the advantage that for CPU and memory hotplug, kdump has
+  not to be reloaded with kexec_load().
+
+* For s390x systems with many attached devices the "cio_ignore" kernel
+  parameter should be used for the kdump kernel in order to prevent allocation
+  of kernel memory for devices that are not relevant for kdump. The same
+  applies to systems that use SCSI/FCP devices. In that case the
+  "allow_lun_scan" zfcp module parameter should be set to zero before
+  setting FCP devices online.
+
+Kernel Panic
+============
+
+After successfully loading the dump-capture kernel as previously
+described, the system will reboot into the dump-capture kernel if a
+system crash is triggered.  Trigger points are located in panic(),
+die(), die_nmi() and in the sysrq handler (ALT-SysRq-c).
+
+The following conditions will execute a crash trigger point:
+
+If a hard lockup is detected and "NMI watchdog" is configured, the system
+will boot into the dump-capture kernel ( die_nmi() ).
+
+If die() is called, and it happens to be a thread with pid 0 or 1, or die()
+is called inside interrupt context or die() is called and panic_on_oops is set,
+the system will boot into the dump-capture kernel.
+
+On powerpc systems when a soft-reset is generated, die() is called by all cpus
+and the system will boot into the dump-capture kernel.
+
+For testing purposes, you can trigger a crash by using "ALT-SysRq-c",
+"echo c > /proc/sysrq-trigger" or write a module to force the panic.
+
+Write Out the Dump File
+=======================
+
+After the dump-capture kernel is booted, write out the dump file with
+the following command::
+
+   cp /proc/vmcore <dump-file>
+
+or use scp to write out the dump file between hosts on a network, e.g::
+
+   scp /proc/vmcore remote_username@remote_ip:<dump-file>
+
+You can also use makedumpfile utility to write out the dump file
+with specified options to filter out unwanted contents, e.g::
+
+   makedumpfile -l --message-level 1 -d 31 /proc/vmcore <dump-file>
+
+Analysis
+========
+
+Before analyzing the dump image, you should reboot into a stable kernel.
+
+You can do limited analysis using GDB on the dump file copied out of
+/proc/vmcore. Use the debug vmlinux built with -g and run the following
+command::
+
+   gdb vmlinux <dump-file>
+
+Stack trace for the task on processor 0, register display, and memory
+display work fine.
+
+Note: GDB cannot analyze core files generated in ELF64 format for x86.
+On systems with a maximum of 4GB of memory, you can generate
+ELF32-format headers using the --elf32-core-headers kernel option on the
+dump kernel.
+
+You can also use the Crash utility to analyze dump files in Kdump
+format. Crash is available at the following URL:
+
+   https://github.com/crash-utility/crash
+
+Crash document can be found at:
+   https://crash-utility.github.io/
+
+Trigger Kdump on WARN()
+=======================
+
+The kernel parameter, panic_on_warn, calls panic() in all WARN() paths.  This
+will cause a kdump to occur at the panic() call.  In cases where a user wants
+to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1
+to achieve the same behaviour.
+
+Trigger Kdump on add_taint()
+============================
+
+The kernel parameter panic_on_taint facilitates a conditional call to panic()
+from within add_taint() whenever the value set in this bitmask matches with the
+bit flag being set by add_taint().
+This will cause a kdump to occur at the add_taint()->panic() call.
+
+Write the dump file to encrypted disk volume
+============================================
+
+CONFIG_CRASH_DM_CRYPT can be enabled to support saving the dump file to an
+encrypted disk volume (only x86_64 supported for now). User space can interact
+with /sys/kernel/config/crash_dm_crypt_keys for setup,
+
+1. Tell the first kernel what logon keys are needed to unlock the disk volumes,
+    # Add key #1
+    mkdir /sys/kernel/config/crash_dm_crypt_keys/7d26b7b4-e342-4d2d-b660-7426b0996720
+    # Add key #1's description
+    echo cryptsetup:7d26b7b4-e342-4d2d-b660-7426b0996720 > /sys/kernel/config/crash_dm_crypt_keys/description
+
+    # how many keys do we have now?
+    cat /sys/kernel/config/crash_dm_crypt_keys/count
+    1
+
+    # Add key #2 in the same way
+
+    # how many keys do we have now?
+    cat /sys/kernel/config/crash_dm_crypt_keys/count
+    2
+
+    # To support CPU/memory hot-plugging, reuse keys already saved to reserved
+    # memory
+    echo true > /sys/kernel/config/crash_dm_crypt_key/reuse
+
+2. Load the dump-capture kernel
+
+3. After the dump-capture kerne get booted, restore the keys to user keyring
+   echo yes > /sys/kernel/crash_dm_crypt_keys/restore
+
+Contact
+=======
+
+- kexec@lists.infradead.org
+
+GDB macros
+==========
+
+.. include:: gdbmacros.txt
+   :literal:
diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
new file mode 100644
index 000000000..7663c610f
--- /dev/null
+++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
@@ -0,0 +1,596 @@
+==========
+VMCOREINFO
+==========
+
+What is it?
+===========
+
+VMCOREINFO is a special ELF note section. It contains various
+information from the kernel like structure size, page size, symbol
+values, field offsets, etc. These data are packed into an ELF note
+section and used by user-space tools like crash and makedumpfile to
+analyze a kernel's memory layout.
+
+Common variables
+================
+
+init_uts_ns.name.release
+------------------------
+
+The version of the Linux kernel. Used to find the corresponding source
+code from which the kernel has been built. For example, crash uses it to
+find the corresponding vmlinux in order to process vmcore.
+
+PAGE_SIZE
+---------
+
+The size of a page. It is the smallest unit of data used by the memory
+management facilities. It is usually 4096 bytes of size and a page is
+aligned on 4096 bytes. Used for computing page addresses.
+
+init_uts_ns
+-----------
+
+The UTS namespace which is used to isolate two specific elements of the
+system that relate to the uname(2) system call. It is named after the
+data structure used to store information returned by the uname(2) system
+call.
+
+User-space tools can get the kernel name, host name, kernel release
+number, kernel version, architecture name and OS type from it.
+
+(uts_namespace, name)
+---------------------
+
+Offset of the name's member. Crash Utility and Makedumpfile get
+the start address of the init_uts_ns.name from this.
+
+node_online_map
+---------------
+
+An array node_states[N_ONLINE] which represents the set of online nodes
+in a system, one bit position per node number. Used to keep track of
+which nodes are in the system and online.
+
+swapper_pg_dir
+--------------
+
+The global page directory pointer of the kernel. Used to translate
+virtual to physical addresses.
+
+_stext
+------
+
+Defines the beginning of the text section. In general, _stext indicates
+the kernel start address. Used to convert a virtual address from the
+direct kernel map to a physical address.
+
+VMALLOC_START
+-------------
+
+Stores the base address of vmalloc area. makedumpfile gets this value
+since is necessary for vmalloc translation.
+
+mem_map
+-------
+
+Physical addresses are translated to struct pages by treating them as
+an index into the mem_map array. Right-shifting a physical address
+PAGE_SHIFT bits converts it into a page frame number which is an index
+into that mem_map array.
+
+Used to map an address to the corresponding struct page.
+
+contig_page_data
+----------------
+
+Makedumpfile gets the pglist_data structure from this symbol, which is
+used to describe the memory layout.
+
+User-space tools use this to exclude free pages when dumping memory.
+
+mem_section|(mem_section, NR_SECTION_ROOTS)|(mem_section, section_mem_map)
+--------------------------------------------------------------------------
+
+The address of the mem_section array, its length, structure size, and
+the section_mem_map offset.
+
+It exists in the sparse memory mapping model, and it is also somewhat
+similar to the mem_map variable, both of them are used to translate an
+address.
+
+MAX_PHYSMEM_BITS
+----------------
+
+Defines the maximum supported physical address space memory.
+
+page
+----
+
+The size of a page structure. struct page is an important data structure
+and it is widely used to compute contiguous memory.
+
+pglist_data
+-----------
+
+The size of a pglist_data structure. This value is used to check if the
+pglist_data structure is valid. It is also used for checking the memory
+type.
+
+zone
+----
+
+The size of a zone structure. This value is used to check if the zone
+structure has been found. It is also used for excluding free pages.
+
+free_area
+---------
+
+The size of a free_area structure. It indicates whether the free_area
+structure is valid or not. Useful when excluding free pages.
+
+list_head
+---------
+
+The size of a list_head structure. Used when iterating lists in a
+post-mortem analysis session.
+
+nodemask_t
+----------
+
+The size of a nodemask_t type. Used to compute the number of online
+nodes.
+
+(page, flags|_refcount|mapping|lru|_mapcount|private|compound_order|compound_info)
+----------------------------------------------------------------------------------
+
+User-space tools compute their values based on the offset of these
+variables. The variables are used when excluding unnecessary pages.
+
+(pglist_data, node_zones|nr_zones|node_mem_map|node_start_pfn|node_spanned_pages|node_id)
+-----------------------------------------------------------------------------------------
+
+On NUMA machines, each NUMA node has a pg_data_t to describe its memory
+layout. On UMA machines there is a single pglist_data which describes the
+whole memory.
+
+These values are used to check the memory type and to compute the
+virtual address for memory map.
+
+(zone, free_area|vm_stat|spanned_pages)
+---------------------------------------
+
+Each node is divided into a number of blocks called zones which
+represent ranges within memory. A zone is described by a structure zone.
+
+User-space tools compute required values based on the offset of these
+variables.
+
+(free_area, free_list)
+----------------------
+
+Offset of the free_list's member. This value is used to compute the number
+of free pages.
+
+Each zone has a free_area structure array called free_area[NR_PAGE_ORDERS].
+The free_list represents a linked list of free page blocks.
+
+(list_head, next|prev)
+----------------------
+
+Offsets of the list_head's members. list_head is used to define a
+circular linked list. User-space tools need these in order to traverse
+lists.
+
+(vmap_area, va_start|list)
+--------------------------
+
+Offsets of the vmap_area's members. They carry vmalloc-specific
+information. Makedumpfile gets the start address of the vmalloc region
+from this.
+
+(zone.free_area, NR_PAGE_ORDERS)
+--------------------------------
+
+Free areas descriptor. User-space tools use this value to iterate the
+free_area ranges. NR_PAGE_ORDERS is used by the zone buddy allocator.
+
+prb
+---
+
+A pointer to the printk ringbuffer (struct printk_ringbuffer). This
+may be pointing to the static boot ringbuffer or the dynamically
+allocated ringbuffer, depending on when the core dump occurred.
+Used by user-space tools to read the active kernel log buffer.
+
+printk_rb_static
+----------------
+
+A pointer to the static boot printk ringbuffer. If @prb has a
+different value, this is useful for viewing the initial boot messages,
+which may have been overwritten in the dynamically allocated
+ringbuffer.
+
+clear_seq
+---------
+
+The sequence number of the printk() record after the last clear
+command. It indicates the first record after the last
+SYSLOG_ACTION_CLEAR, like issued by 'dmesg -c'. Used by user-space
+tools to dump a subset of the dmesg log.
+
+printk_ringbuffer
+-----------------
+
+The size of a printk_ringbuffer structure. This structure contains all
+information required for accessing the various components of the
+kernel log buffer.
+
+(printk_ringbuffer, desc_ring|text_data_ring|dict_data_ring|fail)
+-----------------------------------------------------------------
+
+Offsets for the various components of the printk ringbuffer. Used by
+user-space tools to view the kernel log buffer without requiring the
+declaration of the structure.
+
+prb_desc_ring
+-------------
+
+The size of the prb_desc_ring structure. This structure contains
+information about the set of record descriptors.
+
+(prb_desc_ring, count_bits|descs|head_id|tail_id)
+-------------------------------------------------
+
+Offsets for the fields describing the set of record descriptors. Used
+by user-space tools to be able to traverse the descriptors without
+requiring the declaration of the structure.
+
+prb_desc
+--------
+
+The size of the prb_desc structure. This structure contains
+information about a single record descriptor.
+
+(prb_desc, info|state_var|text_blk_lpos|dict_blk_lpos)
+------------------------------------------------------
+
+Offsets for the fields describing a record descriptors. Used by
+user-space tools to be able to read descriptors without requiring
+the declaration of the structure.
+
+prb_data_blk_lpos
+-----------------
+
+The size of the prb_data_blk_lpos structure. This structure contains
+information about where the text or dictionary data (data block) is
+located within the respective data ring.
+
+(prb_data_blk_lpos, begin|next)
+-------------------------------
+
+Offsets for the fields describing the location of a data block. Used
+by user-space tools to be able to locate data blocks without
+requiring the declaration of the structure.
+
+printk_info
+-----------
+
+The size of the printk_info structure. This structure contains all
+the meta-data for a record.
+
+(printk_info, seq|ts_nsec|text_len|dict_len|caller_id)
+------------------------------------------------------
+
+Offsets for the fields providing the meta-data for a record. Used by
+user-space tools to be able to read the information without requiring
+the declaration of the structure.
+
+prb_data_ring
+-------------
+
+The size of the prb_data_ring structure. This structure contains
+information about a set of data blocks.
+
+(prb_data_ring, size_bits|data|head_lpos|tail_lpos)
+---------------------------------------------------
+
+Offsets for the fields describing a set of data blocks. Used by
+user-space tools to be able to access the data blocks without
+requiring the declaration of the structure.
+
+atomic_long_t
+-------------
+
+The size of the atomic_long_t structure. Used by user-space tools to
+be able to copy the full structure, regardless of its
+architecture-specific implementation.
+
+(atomic_long_t, counter)
+------------------------
+
+Offset for the long value of an atomic_long_t variable. Used by
+user-space tools to access the long value without requiring the
+architecture-specific declaration.
+
+(free_area.free_list, MIGRATE_TYPES)
+------------------------------------
+
+The number of migrate types for pages. The free_list is described by the
+array. Used by tools to compute the number of free pages.
+
+NR_FREE_PAGES
+-------------
+
+On linux-2.6.21 or later, the number of free pages is in
+vm_stat[NR_FREE_PAGES]. Used to get the number of free pages.
+
+PG_lru|PG_private|PG_swapcache|PG_swapbacked|PG_hwpoison|PG_head_mask
+--------------------------------------------------------------------------
+
+Page attributes. These flags are used to filter various unnecessary for
+dumping pages.
+
+PAGE_SLAB_MAPCOUNT_VALUE|PAGE_BUDDY_MAPCOUNT_VALUE|PAGE_OFFLINE_MAPCOUNT_VALUE|PAGE_HUGETLB_MAPCOUNT_VALUE|PAGE_UNACCEPTED_MAPCOUNT_VALUE
+------------------------------------------------------------------------------------------------------------------------------------------
+
+More page attributes. These flags are used to filter various unnecessary for
+dumping pages.
+
+
+x86_64
+======
+
+phys_base
+---------
+
+Used to convert the virtual address of an exported kernel symbol to its
+corresponding physical address.
+
+init_top_pgt
+------------
+
+Used to walk through the whole page table and convert virtual addresses
+to physical addresses. The init_top_pgt is somewhat similar to
+swapper_pg_dir, but it is only used in x86_64.
+
+pgtable_l5_enabled
+------------------
+
+User-space tools need to know whether the crash kernel was in 5-level
+paging mode.
+
+node_data
+---------
+
+This is a struct pglist_data array and stores all NUMA nodes
+information. Makedumpfile gets the pglist_data structure from it.
+
+(node_data, MAX_NUMNODES)
+-------------------------
+
+The maximum number of nodes in system.
+
+KERNELOFFSET
+------------
+
+The kernel randomization offset. Used to compute the page offset. If
+KASLR is disabled, this value is zero.
+
+KERNEL_IMAGE_SIZE
+-----------------
+
+Currently unused by Makedumpfile. Used to compute the module virtual
+address by Crash.
+
+sme_mask
+--------
+
+AMD-specific with SME support: it indicates the secure memory encryption
+mask. Makedumpfile tools need to know whether the crash kernel was
+encrypted. If SME is enabled in the first kernel, the crash kernel's
+page table entries (pgd/pud/pmd/pte) contain the memory encryption
+mask. This is used to remove the SME mask and obtain the true physical
+address.
+
+Currently, sme_mask stores the value of the C-bit position. If needed,
+additional SME-relevant info can be placed in that variable.
+
+For example::
+
+  [ misc	        ][ enc bit  ][ other misc SME info       ]
+  0000_0000_0000_0000_1000_0000_0000_0000_0000_0000_..._0000
+  63   59   55   51   47   43   39   35   31   27   ... 3
+
+x86_32
+======
+
+X86_PAE
+-------
+
+Denotes whether physical address extensions are enabled. It has the cost
+of a higher page table lookup overhead, and also consumes more page
+table space per process. Used to check whether PAE was enabled in the
+crash kernel when converting virtual addresses to physical addresses.
+
+ARM64
+=====
+
+VA_BITS
+-------
+
+The maximum number of bits for virtual addresses. Used to compute the
+virtual memory ranges.
+
+kimage_voffset
+--------------
+
+The offset between the kernel virtual and physical mappings. Used to
+translate virtual to physical addresses.
+
+PHYS_OFFSET
+-----------
+
+Indicates the physical address of the start of memory. Similar to
+kimage_voffset, which is used to translate virtual to physical
+addresses.
+
+KERNELOFFSET
+------------
+
+The kernel randomization offset. Used to compute the page offset. If
+KASLR is disabled, this value is zero.
+
+KERNELPACMASK
+-------------
+
+The mask to extract the Pointer Authentication Code from a kernel virtual
+address.
+
+TCR_EL1.T1SZ
+------------
+
+Indicates the size offset of the memory region addressed by TTBR1_EL1.
+The region size is 2^(64-T1SZ) bytes.
+
+TTBR1_EL1 is the table base address register specified by ARMv8-A
+architecture which is used to lookup the page-tables for the Virtual
+addresses in the higher VA range (refer to ARMv8 ARM document for
+more details).
+
+MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END
+-----------------------------------------------------------------------------
+
+Used to get the correct ranges:
+	MODULES_VADDR ~ MODULES_END-1 : Kernel module space.
+	VMALLOC_START ~ VMALLOC_END-1 : vmalloc() / ioremap() space.
+	VMEMMAP_START ~ VMEMMAP_END-1 : vmemmap region, used for struct page array.
+
+arm
+===
+
+ARM_LPAE
+--------
+
+It indicates whether the crash kernel supports large physical address
+extensions. Used to translate virtual to physical addresses.
+
+s390
+====
+
+lowcore_ptr
+-----------
+
+An array with a pointer to the lowcore of every CPU. Used to print the
+psw and all registers information.
+
+high_memory
+-----------
+
+Used to get the vmalloc_start address from the high_memory symbol.
+
+(lowcore_ptr, NR_CPUS)
+----------------------
+
+The maximum number of CPUs.
+
+powerpc
+=======
+
+
+node_data|(node_data, MAX_NUMNODES)
+-----------------------------------
+
+See above.
+
+contig_page_data
+----------------
+
+See above.
+
+vmemmap_list
+------------
+
+The vmemmap_list maintains the entire vmemmap physical mapping. Used
+to get vmemmap list count and populated vmemmap regions info. If the
+vmemmap address translation information is stored in the crash kernel,
+it is used to translate vmemmap kernel virtual addresses.
+
+mmu_vmemmap_psize
+-----------------
+
+The size of a page. Used to translate virtual to physical addresses.
+
+mmu_psize_defs
+--------------
+
+Page size definitions, i.e. 4k, 64k, or 16M.
+
+Used to make vtop translations.
+
+vmemmap_backing|(vmemmap_backing, list)|(vmemmap_backing, phys)|(vmemmap_backing, virt_addr)
+--------------------------------------------------------------------------------------------
+
+The vmemmap virtual address space management does not have a traditional
+page table to track which virtual struct pages are backed by a physical
+mapping. The virtual to physical mappings are tracked in a simple linked
+list format.
+
+User-space tools need to know the offset of list, phys and virt_addr
+when computing the count of vmemmap regions.
+
+mmu_psize_def|(mmu_psize_def, shift)
+------------------------------------
+
+The size of a struct mmu_psize_def and the offset of mmu_psize_def's
+member.
+
+Used in vtop translations.
+
+sh
+==
+
+node_data|(node_data, MAX_NUMNODES)
+-----------------------------------
+
+See above.
+
+X2TLB
+-----
+
+Indicates whether the crashed kernel enabled SH extended mode.
+
+RISCV64
+=======
+
+VA_BITS
+-------
+
+The maximum number of bits for virtual addresses. Used to compute the
+virtual memory ranges.
+
+PAGE_OFFSET
+-----------
+
+Indicates the virtual kernel start address of the direct-mapped RAM region.
+
+phys_ram_base
+-------------
+
+Indicates the start physical RAM address.
+
+MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END|KERNEL_LINK_ADDR
+----------------------------------------------------------------------------------------------
+
+Used to get the correct ranges:
+
+  * MODULES_VADDR ~ MODULES_END : Kernel module space.
+  * VMALLOC_START ~ VMALLOC_END : vmalloc() / ioremap() space.
+  * VMEMMAP_START ~ VMEMMAP_END : vmemmap space, used for struct page array.
+  * KERNEL_LINK_ADDR : start address of Kernel link and BPF
+
+va_kernel_pa_offset
+-------------------
+
+Indicates the offset between the kernel virtual and physical mappings.
+Used to translate virtual to physical addresses.
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
new file mode 100644
index 000000000..02a725536
--- /dev/null
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -0,0 +1,135 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _kernelparameters:
+
+The kernel's command-line parameters
+====================================
+
+The following is a consolidated list of the kernel parameters as implemented
+by the __setup(), early_param(), core_param() and module_param() macros
+and sorted into English Dictionary order (defined as ignoring all
+punctuation and sorting digits before letters in a case insensitive
+manner), and with descriptions where known.
+
+The kernel parses parameters from the kernel command line up to "``--``";
+if it doesn't recognize a parameter and it doesn't contain a '.', the
+parameter gets passed to init: parameters with '=' go into init's
+environment, others are passed as command line arguments to init.
+Everything after "``--``" is passed as an argument to init.
+
+Module parameters can be specified in two ways: via the kernel command
+line with a module name prefix, or via modprobe, e.g.::
+
+	(kernel command line) usbcore.blinkenlights=1
+	(modprobe command line) modprobe usbcore blinkenlights=1
+
+Parameters for modules which are built into the kernel need to be
+specified on the kernel command line.  modprobe looks through the
+kernel command line (/proc/cmdline) and collects module parameters
+when it loads a module, so the kernel command line can be used for
+loadable modules too.
+
+This document may not be entirely up to date and comprehensive. The command
+"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
+module. Loadable modules, after being loaded into the running kernel, also
+reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
+parameters may be changed at runtime by the command
+``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``.
+
+Special handling
+----------------
+
+Hyphens (dashes) and underscores are equivalent in parameter names, so::
+
+	log_buf_len=1M print-fatal-signals=1
+
+can also be entered as::
+
+	log-buf-len=1M print_fatal_signals=1
+
+Double-quotes can be used to protect spaces in values, e.g.::
+
+	param="spaces in here"
+
+cpu lists
+~~~~~~~~~
+
+Some kernel parameters take a list of CPUs as a value, e.g.  isolcpus,
+nohz_full, irqaffinity, rcu_nocbs.  The format of this list is:
+
+	<cpu number>,...,<cpu number>
+
+or
+
+	<cpu number>-<cpu number>
+	(must be a positive range in ascending order)
+
+or a mixture
+
+<cpu number>,...,<cpu number>-<cpu number>
+
+Note that for the special case of a range one can split the range into equal
+sized groups and for each group use some amount from the beginning of that
+group:
+
+	<cpu number>-<cpu number>:<used size>/<group size>
+
+For example one can add to the command line following parameter:
+
+	isolcpus=1,2,10-20,100-2000:2/25
+
+where the final item represents CPUs 100,101,125,126,150,151,...
+
+The value "N" can be used to represent the numerically last CPU on the system,
+i.e "foo_cpus=16-N" would be equivalent to "16-31" on a 32 core system.
+
+Keep in mind that "N" is dynamic, so if system changes cause the bitmap width
+to change, such as less cores in the CPU list, then N and any ranges using N
+will also change.  Use the same on a small 4 core system, and "16-N" becomes
+"16-3" and now the same boot input will be flagged as invalid (start > end).
+
+The special case-tolerant group name "all" has a meaning of selecting all CPUs,
+so that "nohz_full=all" is the equivalent of "nohz_full=0-N".
+
+The semantics of "N" and "all" is supported on a level of bitmaps and holds for
+all users of bitmap_parselist().
+
+Metric suffixes
+~~~~~~~~~~~~~~~
+
+The [KMG] suffix is commonly described after a number of kernel
+parameter values. 'K', 'M', 'G', 'T', 'P', and 'E' suffixes are allowed.
+These letters represent the _binary_ multipliers 'Kilo', 'Mega', 'Giga',
+'Tera', 'Peta', and 'Exa', equaling 2^10, 2^20, 2^30, 2^40, 2^50, and
+2^60 bytes respectively. Such letter suffixes can also be entirely omitted.
+
+Kernel Build Options
+--------------------
+
+The parameters listed below are only valid if certain kernel build options
+were enabled and if respective hardware is present. This list should be kept
+in alphabetical order. The text in square brackets at the beginning
+of each description states the restrictions within which a parameter
+is applicable.
+
+Parameters denoted with BOOT are actually interpreted by the boot
+loader, and have no meaning to the kernel directly.
+Do not modify the syntax of boot loader parameters without extreme
+need or coordination with <Documentation/arch/x86/boot.rst>.
+
+There are also arch-specific kernel-parameters not documented here.
+
+Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
+a trailing = on the name of any parameter states that the parameter will
+be entered as an environment variable, whereas its absence indicates that
+it will appear as a kernel argument readable via /proc/cmdline by programs
+running once the system is up.
+
+The number of kernel parameters is not limited, but the length of the
+complete command line (parameters including spaces etc.) is limited to
+a fixed number of characters. This limit depends on the architecture
+and is between 256 and 4096 characters. It is defined in the file
+./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE.
+
+.. include:: kernel-parameters.txt
+   :literal:
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
new file mode 100644
index 000000000..33cd30996
--- /dev/null
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -0,0 +1,8709 @@
+	ACPI	ACPI support is enabled.
+	AGP	AGP (Accelerated Graphics Port) is enabled.
+	ALSA	ALSA sound support is enabled.
+	APIC	APIC support is enabled.
+	APM	Advanced Power Management support is enabled.
+	APPARMOR AppArmor support is enabled.
+	ARM	ARM architecture is enabled.
+	ARM64	ARM64 architecture is enabled.
+	CLK	Common clock infrastructure is enabled.
+	CMA	Contiguous Memory Area support is enabled.
+	CPU_FREQ CPU frequency scaling is enabled.
+	CPU_IDLE CPU idle time management is enabled.
+	DRM	Direct Rendering Management support is enabled.
+	DYNAMIC_DEBUG Build in debug messages and enable them at runtime
+	EARLY	Parameter processed too early to be embedded in initrd.
+	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
+	EFI	EFI Partitioning (GPT) is enabled
+	EVM	Extended Verification Module
+	FB	The frame buffer device is enabled.
+	FTRACE	Function tracing enabled.
+	GCOV	GCOV profiling is enabled.
+	HIBERNATION HIBERNATION is enabled.
+	HW	Appropriate hardware is enabled.
+	HYPER_V HYPERV support is enabled.
+	IMA     Integrity measurement architecture is enabled.
+	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
+	IPV6	IPv6 support is enabled.
+	ISAPNP	ISA PnP code is enabled.
+	ISOL	CPU Isolation is enabled.
+	JOY	Appropriate joystick support is enabled.
+	KGDB	Kernel debugger support is enabled.
+	KVM	Kernel Virtual Machine support is enabled.
+	LIBATA  Libata driver is enabled
+	LOONGARCH LoongArch architecture is enabled.
+	LOOP	Loopback device support is enabled.
+	LP	Printer support is enabled.
+	M68k	M68k architecture is enabled.
+			These options have more detailed description inside of
+			Documentation/arch/m68k/kernel-options.rst.
+	MIPS	MIPS architecture is enabled.
+	MOUSE	Appropriate mouse support is enabled.
+	MSI	Message Signaled Interrupts (PCI).
+	MTD	MTD (Memory Technology Device) support is enabled.
+	NET	Appropriate network support is enabled.
+	NFS	Appropriate NFS support is enabled.
+	NUMA	NUMA support is enabled.
+	OF	Devicetree is enabled.
+	PARISC	The PA-RISC architecture is enabled.
+	PCI	PCI bus support is enabled.
+	PCIE	PCI Express support is enabled.
+	PCMCIA	The PCMCIA subsystem is enabled.
+	PM	Power Management support is enabled.
+	PNP	Plug & Play support is enabled.
+	PPC	PowerPC architecture is enabled.
+	PPT	Parallel port support is enabled.
+	PS2	Appropriate PS/2 support is enabled.
+	PV_OPS	A paravirtualized kernel is enabled.
+	RAM	RAM disk support is enabled.
+	RDT	Intel Resource Director Technology.
+	RISCV	RISCV architecture is enabled.
+	S390	S390 architecture is enabled.
+	SCSI	Appropriate SCSI support is enabled.
+			A lot of drivers have their options described inside
+			the Documentation/scsi/ sub-directory.
+        SDW     SoundWire support is enabled.
+	SECURITY Different security models are enabled.
+	SELINUX SELinux support is enabled.
+	SERIAL	Serial support is enabled.
+	SH	SuperH architecture is enabled.
+	SMP	The kernel is an SMP kernel.
+	SPARC	Sparc architecture is enabled.
+	SUSPEND	System suspend states are enabled.
+	SWSUSP	Software suspend (hibernation) is enabled.
+	TPM	TPM drivers are enabled.
+	UMS	USB Mass Storage support is enabled.
+	USB	USB support is enabled.
+	NVME	NVMe support is enabled
+	USBHID	USB Human Interface Device support is enabled.
+	V4L	Video For Linux support is enabled.
+	VGA	The VGA console has been enabled.
+	VMMIO   Driver for memory mapped virtio devices is enabled.
+	VT	Virtual terminal support is enabled.
+	WDT	Watchdog support is enabled.
+	X86-32	X86-32, aka i386 architecture is enabled.
+	X86-64	X86-64 architecture is enabled.
+	X86	Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
+	X86_UV	SGI UV support is enabled.
+	XEN	Xen support is enabled
+	XTENSA	xtensa architecture is enabled.
+
+In addition, the following text indicates that the option
+
+	BOOT	Is a boot loader parameter.
+	BUGS=	Relates to possible processor bugs on the said processor.
+	KNL	Is a kernel start-up parameter.
+
+
+Kernel parameters
+
+	accept_memory=  [MM]
+			Format: { eager | lazy }
+			default: lazy
+			By default, unaccepted memory is accepted lazily to
+			avoid prolonged boot times. The lazy option will add
+			some runtime overhead until all memory is eventually
+			accepted. In most cases the overhead is negligible.
+			For some workloads or for debugging purposes
+			accept_memory=eager can be used to accept all memory
+			at once during boot.
+
+	acpi=		[HW,ACPI,X86,ARM64,RISCV64,EARLY]
+			Advanced Configuration and Power Interface
+			Format: { force | on | off | strict | noirq | rsdt |
+				  copy_dsdt | nospcr }
+			force -- enable ACPI if default was off
+			on -- enable ACPI but allow fallback to DT [arm64,riscv64]
+			off -- disable ACPI if default was on
+			noirq -- do not use ACPI for IRQ routing
+			strict -- Be less tolerant of platforms that are not
+				strictly ACPI specification compliant.
+			rsdt -- prefer RSDT over (default) XSDT
+			copy_dsdt -- copy DSDT to memory
+			nocmcff -- Disable firmware first mode for corrected
+			errors. This disables parsing the HEST CMC error
+			source to check if firmware has set the FF flag. This
+			may result in duplicate corrected error reports.
+			nospcr -- disable console in ACPI SPCR table as
+				default _serial_ console on ARM64
+			spcr -- enable console in ACPI SPCR table as
+				default _serial_ console on x86
+			For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
+			"acpi=nospcr" are available
+			For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
+			are available
+
+			See also Documentation/power/runtime_pm.rst, pci=noacpi
+
+	acpi_apic_instance=	[ACPI,IOAPIC,EARLY]
+			Format: <int>
+			2: use 2nd APIC table, if available
+			1,0: use 1st APIC table
+			default: 0
+
+	acpi_backlight=	[HW,ACPI]
+			{ vendor | video | native | none }
+			If set to vendor, prefer vendor-specific driver
+			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
+			of the ACPI video.ko driver.
+			If set to video, use the ACPI video.ko driver.
+			If set to native, use the device's native backlight mode.
+			If set to none, disable the ACPI backlight interface.
+
+	acpi_force_32bit_fadt_addr [ACPI,EARLY]
+			force FADT to use 32 bit addresses rather than the
+			64 bit X_* addresses. Some firmware have broken 64
+			bit addresses for force ACPI ignore these and use
+			the older legacy 32 bit addresses.
+
+	acpica_no_return_repair [HW, ACPI]
+			Disable AML predefined validation mechanism
+			This mechanism can repair the evaluation result to make
+			the return objects more ACPI specification compliant.
+			This option is useful for developers to identify the
+			root cause of an AML interpreter issue when the issue
+			has something to do with the repair mechanism.
+
+	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
+	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
+			Format: <int>
+			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
+			debug output.  Bits in debug_layer correspond to a
+			_COMPONENT in an ACPI source file, e.g.,
+			    #define _COMPONENT ACPI_EVENTS
+			Bits in debug_level correspond to a level in
+			ACPI_DEBUG_PRINT statements, e.g.,
+			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
+			The debug_level mask defaults to "info".  See
+			Documentation/firmware-guide/acpi/debug.rst for more information about
+			debug layers and levels.
+
+			Enable processor driver info messages:
+			    acpi.debug_layer=0x20000000
+			Enable AML "Debug" output, i.e., stores to the Debug
+			object while interpreting AML:
+			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
+			Enable all messages related to ACPI hardware:
+			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
+
+			Some values produce so much output that the system is
+			unusable.  The "log_buf_len" parameter may be useful
+			if you need to capture more output.
+
+	acpi.poweroff_on_fatal=	[ACPI]
+			{0 | 1}
+			Causes the system to poweroff when the ACPI bytecode signals
+			a fatal error. The default value of this setting is 1.
+			Overriding this value should only be done for diagnosing
+			ACPI firmware problems, as the system might behave erratically
+			after having encountered a fatal ACPI error.
+
+	acpi_enforce_resources=	[ACPI]
+			{ strict | lax | no }
+			Check for resource conflicts between native drivers
+			and ACPI OperationRegions (SystemIO and SystemMemory
+			only). IO ports and memory declared in ACPI might be
+			used by the ACPI subsystem in arbitrary AML code and
+			can interfere with legacy drivers.
+			strict (default): access to resources claimed by ACPI
+			is denied; legacy drivers trying to access reserved
+			resources will fail to bind to device using them.
+			lax: access to resources claimed by ACPI is allowed;
+			legacy drivers trying to access reserved resources
+			will bind successfully but a warning message is logged.
+			no: ACPI OperationRegions are not marked as reserved,
+			no further checks are performed.
+
+	acpi_force_table_verification	[HW,ACPI,EARLY]
+			Enable table checksum verification during early stage.
+			By default, this is disabled due to x86 early mapping
+			size limitation.
+
+	acpi_irq_balance [HW,ACPI]
+			ACPI will balance active IRQs
+			default in APIC mode
+
+	acpi_irq_nobalance [HW,ACPI]
+			ACPI will not move active IRQs (default)
+			default in PIC mode
+
+	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
+			Format: <irq>,<irq>...
+
+	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
+			use by PCI
+			Format: <irq>,<irq>...
+
+	acpi_mask_gpe=	[HW,ACPI]
+			Due to the existence of _Lxx/_Exx, some GPEs triggered
+			by unsupported hardware/firmware features can result in
+			GPE floodings that cannot be automatically disabled by
+			the GPE dispatcher.
+			This facility can be used to prevent such uncontrolled
+			GPE floodings.
+			Format: <byte> or <bitmap-list>
+
+	acpi_no_auto_serialize	[HW,ACPI]
+			Disable auto-serialization of AML methods
+			AML control methods that contain the opcodes to create
+			named objects will be marked as "Serialized" by the
+			auto-serialization feature.
+			This feature is enabled by default.
+			This option allows to turn off the feature.
+
+	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
+			   kernels.
+
+	acpi_no_static_ssdt	[HW,ACPI,EARLY]
+			Disable installation of static SSDTs at early boot time
+			By default, SSDTs contained in the RSDT/XSDT will be
+			installed automatically and they will appear under
+			/sys/firmware/acpi/tables.
+			This option turns off this feature.
+			Note that specifying this option does not affect
+			dynamic table installation which will install SSDT
+			tables to /sys/firmware/acpi/tables/dynamic.
+
+	acpi_no_watchdog	[HW,ACPI,WDT]
+			Ignore the ACPI-based watchdog interface (WDAT) and let
+			a native driver control the watchdog device instead.
+
+	acpi_rsdp=	[ACPI,EFI,KEXEC,EARLY]
+			Pass the RSDP address to the kernel, mostly used
+			on machines running EFI runtime service to boot the
+			second kernel for kdump.
+
+	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
+			Format: To spoof as Windows 98: ="Microsoft Windows"
+
+	acpi_rev_override [ACPI] Override the _REV object to return 5 (instead
+			of 2 which is mandated by ACPI 6) as the supported ACPI
+			specification revision (when using this switch, it may
+			be necessary to carry out a cold reboot _twice_ in a
+			row to make it take effect on the platform firmware).
+
+	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
+			acpi_osi="string1"	# add string1
+			acpi_osi="!string2"	# remove string2
+			acpi_osi=!*		# remove all strings
+			acpi_osi=!		# disable all built-in OS vendor
+						  strings
+			acpi_osi=!!		# enable all built-in OS vendor
+						  strings
+			acpi_osi=		# disable all strings
+
+			'acpi_osi=!' can be used in combination with single or
+			multiple 'acpi_osi="string1"' to support specific OS
+			vendor string(s).  Note that such command can only
+			affect the default state of the OS vendor strings, thus
+			it cannot affect the default state of the feature group
+			strings and the current state of the OS vendor strings,
+			specifying it multiple times through kernel command line
+			is meaningless.  This command is useful when one do not
+			care about the state of the feature group strings which
+			should be controlled by the OSPM.
+			Examples:
+			  1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent
+			     to 'acpi_osi="Windows 2000" acpi_osi=!', they all
+			     can make '_OSI("Windows 2000")' TRUE.
+
+			'acpi_osi=' cannot be used in combination with other
+			'acpi_osi=' command lines, the _OSI method will not
+			exist in the ACPI namespace.  NOTE that such command can
+			only affect the _OSI support state, thus specifying it
+			multiple times through kernel command line is also
+			meaningless.
+			Examples:
+			  1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)'
+			     FALSE.
+
+			'acpi_osi=!*' can be used in combination with single or
+			multiple 'acpi_osi="string1"' to support specific
+			string(s).  Note that such command can affect the
+			current state of both the OS vendor strings and the
+			feature group strings, thus specifying it multiple times
+			through kernel command line is meaningful.  But it may
+			still not able to affect the final state of a string if
+			there are quirks related to this string.  This command
+			is useful when one want to control the state of the
+			feature group strings to debug BIOS issues related to
+			the OSPM features.
+			Examples:
+			  1. 'acpi_osi="Module Device" acpi_osi=!*' can make
+			     '_OSI("Module Device")' FALSE.
+			  2. 'acpi_osi=!* acpi_osi="Module Device"' can make
+			     '_OSI("Module Device")' TRUE.
+			  3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is
+			     equivalent to
+			     'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"'
+			     and
+			     'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!',
+			     they all will make '_OSI("Windows 2000")' TRUE.
+
+	acpi_pm_good	[X86]
+			Override the pmtimer bug detection: force the kernel
+			to assume that this machine's pmtimer latches its value
+			and always returns good values.
+
+	acpi_sci=	[HW,ACPI,EARLY] ACPI System Control Interrupt trigger mode
+			Format: { level | edge | high | low }
+
+	acpi_skip_timer_override [HW,ACPI,EARLY]
+			Recognize and ignore IRQ0/pin2 Interrupt Override.
+			For broken nForce2 BIOS resulting in XT-PIC timer.
+
+	acpi_sleep=	[HW,ACPI] Sleep options
+			Format: { s3_bios, s3_mode, s3_beep, s4_hwsig,
+				  s4_nohwsig, old_ordering, nonvs,
+				  sci_force_enable, nobl }
+			See Documentation/power/video.rst for information on
+			s3_bios and s3_mode.
+			s3_beep is for debugging; it makes the PC's speaker beep
+			as soon as the kernel's real-mode entry point is called.
+			s4_hwsig causes the kernel to check the ACPI hardware
+			signature during resume from hibernation, and gracefully
+			refuse to resume if it has changed. This complies with
+			the ACPI specification but not with reality, since
+			Windows does not do this and many laptops do change it
+			on docking. So the default behaviour is to allow resume
+			and simply warn when the signature changes, unless the
+			s4_hwsig option is enabled.
+			s4_nohwsig prevents ACPI hardware signature from being
+			used (or even warned about) during resume.
+			old_ordering causes the ACPI 1.0 ordering of the _PTS
+			control method, with respect to putting devices into
+			low power states, to be enforced (the ACPI 2.0 ordering
+			of _PTS is used by default).
+			nonvs prevents the kernel from saving/restoring the
+			ACPI NVS memory during suspend/hibernation and resume.
+			sci_force_enable causes the kernel to set SCI_EN directly
+			on resume from S1/S3 (which is against the ACPI spec,
+			but some broken systems don't work without it).
+			nobl causes the internal blacklist of systems known to
+			behave incorrectly in some ways with respect to system
+			suspend and resume to be ignored (use wisely).
+
+	acpi_use_timer_override [HW,ACPI,EARLY]
+			Use timer override. For some broken Nvidia NF5 boards
+			that require a timer override, but don't have HPET
+
+	add_efi_memmap	[EFI,X86,EARLY] Include EFI memory map in
+			kernel's map of available physical RAM.
+
+	agp=		[AGP]
+			{ off | try_unsupported }
+			off: disable AGP support
+			try_unsupported: try to drive unsupported chipsets
+				(may crash computer or cause data corruption)
+
+	ALSA		[HW,ALSA]
+			See Documentation/sound/alsa-configuration.rst
+
+	alignment=	[KNL,ARM]
+			Allow the default userspace alignment fault handler
+			behaviour to be specified.  Bit 0 enables warnings,
+			bit 1 enables fixups, and bit 2 sends a segfault.
+
+	align_va_addr=	[X86-64]
+			Align virtual addresses by clearing slice [14:12] when
+			allocating a VMA at process creation time. This option
+			gives you up to 3% performance improvement on AMD F15h
+			machines (where it is enabled by default) for a
+			CPU-intensive style benchmark, and it can vary highly in
+			a microbenchmark depending on workload and compiler.
+
+			32: only for 32-bit processes
+			64: only for 64-bit processes
+			on: enable for both 32- and 64-bit processes
+			off: disable for both 32- and 64-bit processes
+
+	alloc_snapshot	[FTRACE]
+			Allocate the ftrace snapshot buffer on boot up when the
+			main buffer is allocated. This is handy if debugging
+			and you need to use tracing_snapshot() on boot up, and
+			do not want to use tracing_snapshot_alloc() as it needs
+			to be done where GFP_KERNEL allocations are allowed.
+
+	allow_mismatched_32bit_el0 [ARM64,EARLY]
+			Allow execve() of 32-bit applications and setting of the
+			PER_LINUX32 personality on systems where only a strict
+			subset of the CPUs support 32-bit EL0. When this
+			parameter is present, the set of CPUs supporting 32-bit
+			EL0 is indicated by /sys/devices/system/cpu/aarch32_el0
+			and hot-unplug operations may be restricted.
+
+			See Documentation/arch/arm64/asymmetric-32bit.rst for more
+			information.
+
+	amd_iommu=	[HW,X86-64]
+			Pass parameters to the AMD IOMMU driver in the system.
+			Possible values are:
+			fullflush - Deprecated, equivalent to iommu.strict=1
+			off	  - do not initialize any AMD IOMMU found in
+				    the system
+			force_isolation - Force device isolation for all
+					  devices. The IOMMU driver is not
+					  allowed anymore to lift isolation
+					  requirements as needed. This option
+					  does not override iommu=pt
+			force_enable    - Force enable the IOMMU on platforms known
+				          to be buggy with IOMMU enabled. Use this
+				          option with care.
+			pgtbl_v1        - Use v1 page table for DMA-API (Default).
+			pgtbl_v2        - Use v2 page table for DMA-API.
+			irtcachedis     - Disable Interrupt Remapping Table (IRT) caching.
+			nohugepages     - Limit page-sizes used for v1 page-tables
+				          to 4 KiB.
+			v2_pgsizes_only - Limit page-sizes used for v1 page-tables
+				          to 4KiB/2Mib/1GiB.
+
+
+	amd_iommu_dump=	[HW,X86-64]
+			Enable AMD IOMMU driver option to dump the ACPI table
+			for AMD IOMMU. With this option enabled, AMD IOMMU
+			driver will print ACPI tables for AMD IOMMU during
+			IOMMU initialization.
+
+	amd_iommu_intr=	[HW,X86-64]
+			Specifies one of the following AMD IOMMU interrupt
+			remapping modes:
+			legacy     - Use legacy interrupt remapping mode.
+			vapic      - Use virtual APIC mode, which allows IOMMU
+			             to inject interrupts directly into guest.
+			             This mode requires kvm-amd.avic=1.
+			             (Default when IOMMU HW support is present.)
+
+	amd_pstate=	[X86,EARLY]
+			disable
+			  Do not enable amd_pstate as the default
+			  scaling driver for the supported processors
+			passive
+			  Use amd_pstate with passive mode as a scaling driver.
+			  In this mode autonomous selection is disabled.
+			  Driver requests a desired performance level and platform
+			  tries to match the same performance level if it is
+			  satisfied by guaranteed performance level.
+			active
+			  Use amd_pstate_epp driver instance as the scaling driver,
+			  driver provides a hint to the hardware if software wants
+			  to bias toward performance (0x0) or energy efficiency (0xff)
+			  to the CPPC firmware. then CPPC power algorithm will
+			  calculate the runtime workload and adjust the realtime cores
+			  frequency.
+			guided
+			  Activate guided autonomous mode. Driver requests minimum and
+			  maximum performance level and the platform autonomously
+			  selects a performance level in this range and appropriate
+			  to the current workload.
+
+	amd_prefcore=
+			[X86]
+			disable
+			  Disable amd-pstate preferred core.
+
+	amd_dynamic_epp=
+			[X86]
+			disable
+			  Disable amd-pstate dynamic EPP.
+			enable
+			  Enable amd-pstate dynamic EPP.
+
+	amijoy.map=	[HW,JOY] Amiga joystick support
+			Map of devices attached to JOY0DAT and JOY1DAT
+			Format: <a>,<b>
+			See also Documentation/input/joydev/joystick.rst
+
+	analog.map=	[HW,JOY] Analog joystick and gamepad support
+			Specifies type or capabilities of an analog joystick
+			connected to one of 16 gameports
+			Format: <type1>,<type2>,..<type16>
+
+	apc=		[HW,SPARC]
+			Power management functions (SPARCstation-4/5 + deriv.)
+			Format: noidle
+			Disable APC CPU standby support. SPARCstation-Fox does
+			not play well with APC CPU idle - disable it if you have
+			APC and your system crashes randomly.
+
+	apic		[APIC,X86-64] Use IO-APIC. Default.
+
+	apic=		[APIC,X86,EARLY] Advanced Programmable Interrupt Controller
+			Change the output verbosity while booting
+			Format: { quiet (default) | verbose | debug }
+			Change the amount of debugging information output
+			when initialising the APIC and IO-APIC components.
+
+	apic_extnmi=	[APIC,X86,EARLY] External NMI delivery setting
+			Format: { bsp (default) | all | none }
+			bsp:  External NMI is delivered only to CPU 0
+			all:  External NMIs are broadcast to all CPUs as a
+			      backup of CPU 0
+			none: External NMI is masked for all CPUs. This is
+			      useful so that a dump capture kernel won't be
+			      shot down by NMI
+
+	apicpmtimer	Do APIC timer calibration using the pmtimer. Implies
+			apicmaintimer. Useful when your PIT timer is totally
+			broken.
+
+	autoconf=	[IPV6]
+			See Documentation/networking/ipv6.rst.
+
+	apm=		[APM] Advanced Power Management
+			See header of arch/x86/kernel/apm_32.c.
+
+	apparmor=	[APPARMOR] Disable or enable AppArmor at boot time
+			Format: { "0" | "1" }
+			See security/apparmor/Kconfig help text
+			0 -- disable.
+			1 -- enable.
+			Default value is set via kernel config option.
+
+	arm64.no32bit_el0 [ARM64] Unconditionally disable the execution of
+			32 bit applications.
+
+	arm64.nobti	[ARM64] Unconditionally disable Branch Target
+			Identification support
+
+	arm64.nogcs	[ARM64] Unconditionally disable Guarded Control Stack
+			support
+
+	arm64.nohaft	[ARM64] Unconditionally disable Hardware managed Access
+			Flag for Table descriptors support
+
+	arm64.nomops	[ARM64] Unconditionally disable Memory Copy and Memory
+			Set instructions support
+
+	arm64.nompam	[ARM64] Unconditionally disable Memory Partitioning And
+			Monitoring support
+
+	arm64.nomte	[ARM64] Unconditionally disable Memory Tagging Extension
+			support
+
+	arm64.nopauth	[ARM64] Unconditionally disable Pointer Authentication
+			support
+
+	arm64.nosme	[ARM64] Unconditionally disable Scalable Matrix
+			Extension support
+
+	arm64.nosve	[ARM64] Unconditionally disable Scalable Vector
+			Extension support
+
+	ataflop=	[HW,M68k]
+
+	atarimouse=	[HW,MOUSE] Atari Mouse
+
+	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
+			EzKey and similar keyboards
+
+	atkbd.reset=	[HW] Reset keyboard during initialization
+
+	atkbd.set=	[HW] Select keyboard code set
+			Format: <int> (2 = AT (default), 3 = PS/2)
+
+	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
+			keyboards
+
+	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
+			Format: <bool> (0 = real, 1 = synthetic (default))
+
+	atkbd.softrepeat= [HW]
+			Use software keyboard repeat
+
+	audit=		[KNL] Enable the audit sub-system
+			Format: { "0" | "1" | "off" | "on" }
+			0 | off - kernel audit is disabled and can not be
+			    enabled until the next reboot
+			unset - kernel audit is initialized but disabled and
+			    will be fully enabled by the userspace auditd.
+			1 | on - kernel audit is initialized and partially
+			    enabled, storing at most audit_backlog_limit
+			    messages in RAM until it is fully enabled by the
+			    userspace auditd.
+			Default: unset
+
+	audit_backlog_limit= [KNL] Set the audit queue size limit.
+			Format: <int> (must be >=0)
+			Default: 64
+
+	bau=		[X86_UV] Enable the BAU on SGI UV.  The default
+			behavior is to disable the BAU (i.e. bau=0).
+			Format: { "0" | "1" }
+			0 - Disable the BAU.
+			1 - Enable the BAU.
+			unset - Disable the BAU.
+
+	bdev_allow_write_mounted=
+			Format: <bool>
+			Control the ability to open a mounted block device
+			for writing, i.e., allow / disallow writes that bypass
+			the FS. This was implemented as a means to prevent
+			fuzzers from crashing the kernel by overwriting the
+			metadata underneath a mounted FS without its awareness.
+			This also prevents destructive formatting of mounted
+			filesystems by naive storage tooling that don't use
+			O_EXCL. Default is Y and can be changed through the
+			Kconfig option CONFIG_BLK_DEV_WRITE_MOUNTED.
+
+	bert_disable	[ACPI]
+			Disable BERT OS support on buggy BIOSes.
+
+	bgrt_disable	[ACPI,X86,EARLY]
+			Disable BGRT to avoid flickering OEM logo.
+
+	blkdevparts=	Manual partition parsing of block device(s) for
+			embedded devices based on command line input.
+			See Documentation/block/cmdline-partition.rst
+
+	boot_delay=	[KNL,EARLY]
+			Milliseconds to delay each printk during boot.
+			Only works if CONFIG_BOOT_PRINTK_DELAY is enabled,
+			and you may also have to specify "lpj=".  Boot_delay
+			values larger than 10 seconds (10000) are assumed
+			erroneous and ignored.
+			Format: integer
+
+	bootconfig	[KNL,EARLY]
+			Extended command line options can be added to an initrd
+			and this will cause the kernel to look for it.
+
+			See Documentation/admin-guide/bootconfig.rst
+
+	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
+	bttv.radio=	Most important insmod options are available as
+			kernel args too.
+	bttv.pll=	See Documentation/admin-guide/media/bttv.rst
+	bttv.tuner=
+
+	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
+			firmware feature for flushing multiple hpte entries
+			at a time.
+
+	c101=		[NET] Moxa C101 synchronous serial card
+
+	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
+			Sometimes CPU hardware bugs make them report the cache
+			size incorrectly. The kernel will attempt work arounds
+			to fix known problems, but for some CPUs it is not
+			possible to determine what the correct size should be.
+			This option provides an override for these situations.
+
+	carrier_timeout=
+			[NET] Specifies amount of time (in seconds) that
+			the kernel should wait for a network carrier. By default
+			it waits 120 seconds.
+
+	ca_keys=	[KEYS] This parameter identifies a specific key(s) on
+			the system trusted keyring to be used for certificate
+			trust validation.
+			format: { id:<keyid> | builtin }
+
+	cca=		[MIPS,EARLY] Override the kernel pages' cache coherency
+			algorithm.  Accepted values range from 0 to 7
+			inclusive. See arch/mips/include/asm/pgtable-bits.h
+			for platform specific values (SB1, Loongson3 and
+			others).
+
+	ccw_timeout_log	[S390]
+			See Documentation/arch/s390/common_io.rst for details.
+
+	cfi=		[X86-64] Set Control Flow Integrity checking features
+			when CONFIG_FINEIBT is enabled.
+			Format: feature[,feature...]
+			Default: auto
+
+			auto:	  Use FineIBT if IBT available, otherwise kCFI.
+				  Under FineIBT, enable "paranoid" mode when
+				  FRED is not available.
+			off:	  Turn off CFI checking.
+			kcfi:	  Use kCFI (disable FineIBT).
+			fineibt:  Use FineIBT (even if IBT not available).
+			norand:   Do not re-randomize CFI hashes.
+			paranoid: Add caller hash checking under FineIBT.
+			bhi:	  Enable register poisoning to stop speculation
+				  across FineIBT. (Disabled by default.)
+			warn:	  Do not enforce CFI checking: warn only.
+			debug:    Report CFI initialization details.
+
+	cgroup_disable=	[KNL] Disable a particular controller or optional feature
+			Format: {name of the controller(s) or feature(s) to disable}
+			The effects of cgroup_disable=foo are:
+			- foo isn't auto-mounted if you mount all cgroups in
+			  a single hierarchy
+			- foo isn't visible as an individually mountable
+			  subsystem
+			- if foo is an optional feature then the feature is
+			  disabled and corresponding cgroup files are not
+			  created
+			{Currently only "memory" controller deal with this and
+			cut the overhead, others just disable the usage. So
+			only cgroup_disable=memory is actually worthy}
+			Specifying "pressure" disables per-cgroup pressure
+			stall information accounting feature
+
+	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1
+			Format: { { controller | "all" | "named" }
+			          [,{ controller | "all" | "named" }...] }
+			Like cgroup_disable, but only applies to cgroup v1;
+			the blacklisted controllers remain available in cgroup2.
+			"all" blacklists all controllers and "named" disables
+			named mounts. Specifying both "all" and "named" disables
+			all v1 hierarchies.
+
+	cgroup_v1_proc=	[KNL] Show also missing controllers in /proc/cgroups
+			Format: { "true" | "false" }
+			/proc/cgroups lists only v1 controllers by default.
+			This compatibility option enables listing also v2
+			controllers (whose v1 code is not compiled!), so that
+			semi-legacy software can check this file to decide
+			about usage of v2 (sic) controllers.
+
+	cgroup_favordynmods= [KNL] Enable or Disable favordynmods.
+			Format: { "true" | "false" }
+			Defaults to the value of CONFIG_CGROUP_FAVOR_DYNMODS.
+
+	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
+			Format: <string>
+			nosocket -- Disable socket memory accounting.
+			nokmem -- Disable kernel memory accounting.
+			nobpf -- Disable BPF memory accounting.
+
+	check_pages=	[MM,EARLY] Enable sanity checking of pages after
+			allocations / before freeing. This adds checks to catch
+			double-frees, use-after-frees, and other sources of
+			page corruption by inspecting page internals (flags,
+			mapcount/refcount, memcg_data, etc.).
+			Format: { "0" | "1" }
+			Default: 0 (1 if CONFIG_DEBUG_VM is set)
+
+	checkreqprot=	[SELINUX] Set initial checkreqprot flag value.
+			Format: { "0" | "1" }
+			See security/selinux/Kconfig help text.
+			0 -- check protection applied by kernel (includes
+				any implied execute protection).
+			1 -- check protection requested by application.
+			Default value is set via a kernel config option.
+			Value can be changed at runtime via
+				/sys/fs/selinux/checkreqprot.
+			Setting checkreqprot to 1 is deprecated.
+
+	cio_ignore=	[S390]
+			See Documentation/arch/s390/common_io.rst for details.
+
+	clk_ignore_unused
+			[CLK]
+			Prevents the clock framework from automatically gating
+			clocks that have not been explicitly enabled by a Linux
+			device driver but are enabled in hardware at reset or
+			by the bootloader/firmware. Note that this does not
+			force such clocks to be always-on nor does it reserve
+			those clocks in any way. This parameter is useful for
+			debug and development, but should not be needed on a
+			platform with proper driver support.  For more
+			information, see Documentation/driver-api/clk.rst.
+
+	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
+			[Deprecated]
+			Forces specified clocksource (if available) to be used
+			when calculating gettimeofday(). If specified
+			clocksource is not available, it defaults to PIT.
+			Format: { pit | tsc | cyclone | pmtmr }
+
+	clocksource=	Override the default clocksource
+			Format: <string>
+			Override the default clocksource and use the clocksource
+			with the name specified.
+			Some clocksource names to choose from, depending on
+			the platform:
+			[all] jiffies (this is the base, fallback clocksource)
+			[ACPI] acpi_pm
+			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
+				pxa_timer,timer3,32k_counter,timer0_1
+			[X86-32] pit,hpet,tsc;
+				scx200_hrt on Geode; cyclone on IBM x440
+			[MIPS] MIPS
+			[PARISC] cr16
+			[S390] tod
+			[SH] SuperH
+			[SPARC64] tick
+			[X86-64] hpet,tsc
+
+	clocksource.arm_arch_timer.evtstrm=
+			[ARM,ARM64,EARLY]
+			Format: <bool>
+			Enable/disable the eventstream feature of the ARM
+			architected timer so that code using WFE-based polling
+			loops can be debugged more effectively on production
+			systems.
+
+	clocksource.verify_n_cpus= [KNL]
+			Limit the number of CPUs checked for clocksources
+			marked with CLOCK_SOURCE_VERIFY_PERCPU that
+			are marked unstable due to excessive skew.
+			A negative value says to check all CPUs, while
+			zero says not to check any.  Values larger than
+			nr_cpu_ids are silently truncated to nr_cpu_ids.
+			The actual CPUs are chosen randomly, with
+			no replacement if the same CPU is chosen twice.
+
+	clocksource-wdtest.holdoff= [KNL]
+			Set the time in seconds that the clocksource
+			watchdog test waits before commencing its tests.
+			Defaults to zero when built as a module and to
+			10 seconds when built into the kernel.
+
+	cma=nn[MG]@[start[MG][-end[MG]]]
+			[KNL,CMA,EARLY]
+			Sets the size of kernel global memory area for
+			contiguous memory allocations and optionally the
+			placement constraint by the physical address range of
+			memory allocations. A value of 0 disables CMA
+			altogether. For more information, see
+			kernel/dma/contiguous.c
+
+	cma_pernuma=nn[MG]
+			[KNL,CMA,EARLY]
+			Sets the size of kernel per-numa memory area for
+			contiguous memory allocations. A value of 0 disables
+			per-numa CMA altogether. And If this option is not
+			specified, the default value is 0.
+			With per-numa CMA enabled, DMA users on node nid will
+			first try to allocate buffer from the pernuma area
+			which is located in node nid, if the allocation fails,
+			they will fallback to the global default memory area.
+
+	numa_cma=<node>:nn[MG][,<node>:nn[MG]]
+			[KNL,CMA,EARLY]
+			Sets the size of kernel numa memory area for
+			contiguous memory allocations. It will reserve CMA
+			area for the specified node.
+
+			If it is setup together with upper 'cmd_pernuma='
+			(unlikely), its size setting takes priority for the
+			specified numa nodes.
+
+			With numa CMA enabled, DMA users on node nid will
+			first try to allocate buffer from the numa area
+			which is located in node nid, if the allocation fails,
+			they will fallback to the global default memory area.
+
+	cmo_free_hint=	[PPC] Format: { yes | no }
+			Specify whether pages are marked as being inactive
+			when they are freed.  This is used in CMO environments
+			to determine OS memory pressure for page stealing by
+			a hypervisor.
+			Default: yes
+
+	coherent_pool=nn[KMG]	[ARM,KNL,EARLY]
+			Sets the size of memory pool for coherent, atomic dma
+			allocations, by default set to 256K.
+
+	condev=		[HW,S390] console device
+	conmode=
+
+	con3215_drop=	[S390,EARLY] 3215 console drop mode.
+			Format: y|n|Y|N|1|0
+			When set to true, drop data on the 3215 console when
+			the console buffer is full. In this case the
+			operator using a 3270 terminal emulator (for example
+			x3270) does not have to enter the clear key for the
+			console output to advance and the kernel to continue.
+			This leads to a much faster boot time when a 3270
+			terminal emulator is active. If no 3270 terminal
+			emulator is used, this parameter has no effect.
+
+	console=	[KNL] Output console device and options.
+
+		tty<n>	Use the virtual console device <n>.
+
+		ttyS<n>[,options]
+		ttyUSB0[,options]
+			Use the specified serial port.  The options are of
+			the form "bbbbpnf", where "bbbb" is the baud rate,
+			"p" is parity ("n", "o", or "e"), "n" is number of
+			bits, and "f" is flow control ("r" for RTS or
+			omit it).  Default is "9600n8".
+
+			See Documentation/admin-guide/serial-console.rst for more
+			information.  See
+			Documentation/networking/netconsole.rst for an
+			alternative.
+
+		<DEVNAME>:<n>.<n>[,options]
+			Use the specified serial port on the serial core bus.
+			The addressing uses DEVNAME of the physical serial port
+			device, followed by the serial core controller instance,
+			and the serial port instance. The options are the same
+			as documented for the ttyS addressing above.
+
+			The mapping of the serial ports to the tty instances
+			can be viewed with:
+
+			$ ls -d /sys/bus/serial-base/devices/*:*.*/tty/*
+			/sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0
+
+			In the above example, the console can be addressed with
+			console=00:04:0.0. Note that a console addressed this
+			way will only get added when the related device driver
+			is ready. The use of an earlycon parameter in addition to
+			the console may be desired for console output early on.
+
+		uart[8250],io,<addr>[,options]
+		uart[8250],mmio,<addr>[,options]
+		uart[8250],mmio16,<addr>[,options]
+		uart[8250],mmio32,<addr>[,options]
+		uart[8250],0x<addr>[,options]
+			Start an early, polled-mode console on the 8250/16550
+			UART at the specified I/O port or MMIO address,
+			switching to the matching ttyS device later.
+			MMIO inter-register address stride is either 8-bit
+			(mmio), 16-bit (mmio16), or 32-bit (mmio32).
+			If none of [io|mmio|mmio16|mmio32], <addr> is assumed
+			to be equivalent to 'mmio'. 'options' are specified in
+			the same format described for ttyS above; if unspecified,
+			the h/w is not re-initialized.
+
+		hvc<n>	Use the hypervisor console device <n>. This is for
+			both Xen and PowerPC hypervisors.
+
+		{ null | "" }
+			Use to disable console output, i.e., to have kernel
+			console messages discarded.
+			This must be the only console= parameter used on the
+			kernel command line.
+
+		If the device connected to the port is not a TTY but a braille
+		device, prepend "brl," before the device type, for instance
+			console=brl,ttyS0
+		For now, only VisioBraille is supported.
+
+	console_msg_format=
+			[KNL] Change console messages format
+		default
+			By default we print messages on consoles in
+			"[time stamp] text\n" format (time stamp may not be
+			printed, depending on CONFIG_PRINTK_TIME or
+			`printk_time' param).
+		syslog
+			Switch to syslog format: "<%u>[time stamp] text\n"
+			IOW, each message will have a facility and loglevel
+			prefix. The format is similar to one used by syslog()
+			syscall, or to executing "dmesg -S --raw" or to reading
+			from /proc/kmsg.
+
+	consoleblank=	[KNL] The console blank (screen saver) timeout in
+			seconds. A value of 0 disables the blank timer.
+			Defaults to 0.
+
+	coredump_filter=
+			[KNL] Change the default value for
+			/proc/<pid>/coredump_filter.
+			See also Documentation/filesystems/proc.rst.
+
+	coresight_cpu_debug.enable
+			[ARM,ARM64]
+			Format: <bool>
+			Enable/disable the CPU sampling based debugging.
+			0: default value, disable debugging
+			1: enable debugging at boot time
+
+	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
+			Format:
+			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
+
+	cpuidle.off=1	[CPU_IDLE]
+			disable the cpuidle sub-system
+
+	cpuidle.governor=
+			[CPU_IDLE] Name of the cpuidle governor to use.
+
+	cpufreq.off=1	[CPU_FREQ]
+			disable the cpufreq sub-system
+
+	cpufreq.default_governor=
+			[CPU_FREQ] Name of the default cpufreq governor or
+			policy to use. This governor must be registered in the
+			kernel before the cpufreq driver probes.
+
+	cpu_init_udelay=N
+			[X86,EARLY] Delay for N microsec between assert and de-assert
+			of APIC INIT to start processors.  This delay occurs
+			on every CPU online, such as boot, and resume from suspend.
+			Default: 10000
+
+	cpuhp.parallel=
+			[SMP] Enable/disable parallel bringup of secondary CPUs
+			Format: <bool>
+			Default is enabled if CONFIG_HOTPLUG_PARALLEL=y. Otherwise
+			the parameter has no effect.
+
+	crash_kexec_post_notifiers
+			Only jump to kdump kernel after running the panic
+			notifiers and dumping kmsg. This option increases
+			the risks of a kdump failure, since some panic
+			notifiers can make the crashed kernel more unstable.
+			In configurations where kdump may not be reliable,
+			running the panic notifiers could allow collecting
+			more data on dmesg, like stack traces from other CPUS
+			or extra data dumped by panic_print. Note that some
+			configurations enable this option unconditionally,
+			like Hyper-V, PowerPC (fadump) and AMD SEV-SNP.
+
+	crashkernel=size[KMG][@offset[KMG]]
+			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
+			upon panic. This parameter reserves the physical
+			memory region [offset, offset + size] for that kernel
+			image. If '@offset' is omitted, then a suitable offset
+			is selected automatically.
+			[KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
+			under 4G first, and fall back to reserve region above
+			4G when '@offset' hasn't been specified.
+			See Documentation/admin-guide/kdump/kdump.rst for further details.
+
+	crashkernel=range1:size1[,range2:size2,...][@offset]
+			[KNL] Same as above, but depends on the memory
+			in the running system. The syntax of range is
+			start-[end] where start and end are both
+			a memory unit (amount[KMG]). See also
+			Documentation/admin-guide/kdump/kdump.rst for an example.
+
+	crashkernel=size[KMG],high
+			[KNL, X86-64, ARM64, RISCV, LoongArch] range could be
+			above 4G.
+			Allow kernel to allocate physical memory region from top,
+			so could be above 4G if system have more than 4G ram
+			installed. Otherwise memory region will be allocated
+			below 4G, if available.
+			It will be ignored if crashkernel=X is specified.
+	crashkernel=size[KMG],low
+			[KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
+			When crashkernel=X,high is passed, kernel could allocate
+			physical memory region above 4G, that cause second kernel
+			crash on system that require some amount of low memory,
+			e.g. swiotlb requires at least 64M+32K low memory, also
+			enough extra low memory is needed to make sure DMA buffers
+			for 32-bit devices won't run out. Kernel would try to allocate
+			default	size of memory below 4G automatically. The default
+			size is	platform dependent.
+			  --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
+			  --> arm64: 128MiB
+			  --> riscv: 128MiB
+			  --> loongarch: 128MiB
+			This one lets the user specify own low range under 4G
+			for second kernel instead.
+			0: to disable low allocation.
+			It will be ignored when crashkernel=X,high is not used
+			or memory reserved is below 4G.
+	crashkernel=size[KMG],cma
+			[KNL, X86, ARM64, RISCV, PPC] Reserve additional crash
+			kernel memory from CMA. This reservation is usable by
+			the first system's userspace memory and kernel movable
+			allocations (memory balloon, zswap). Pages allocated
+			from this memory range will not be included in the vmcore
+			so this should not be used if dumping of userspace memory
+			is intended and it has to be expected that some movable
+			kernel pages may be missing from the dump.
+
+			A standard crashkernel reservation, as described above,
+			is still needed to hold the crash kernel and initrd.
+
+			This option increases the risk of a kdump failure: DMA
+			transfers configured by the first kernel may end up
+			corrupting the second kernel's memory.
+
+			This reservation method is intended for systems that
+			can't afford to sacrifice enough memory for standard
+			crashkernel reservation and where less reliable and
+			possibly incomplete kdump is preferable to no kdump at
+			all.
+
+	cryptomgr.notests
+			[KNL] Disable crypto self-tests
+
+	cs89x0_dma=	[HW,NET]
+			Format: <dma>
+
+	cs89x0_media=	[HW,NET]
+			Format: { rj45 | aui | bnc }
+
+	csdlock_debug=	[KNL] Enable or disable debug add-ons of cross-CPU
+			function call handling. When switched on,
+			additional debug data is printed to the console
+			in case a hanging CPU is detected, and that
+			CPU is pinged again in order to try to resolve
+			the hang situation.  The default value of this
+			option depends on the CSD_LOCK_WAIT_DEBUG_DEFAULT
+			Kconfig option.
+
+	dasd=		[HW,NET]
+			See header of drivers/s390/block/dasd_devmap.c.
+
+	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
+			(one device per port)
+			Format: <port#>,<type>
+			See also Documentation/input/devices/joystick-parport.rst
+
+	debug		[KNL,EARLY] Enable kernel debugging (events log level).
+
+	debug_boot_weak_hash
+			[KNL,EARLY] Enable printing [hashed] pointers early in the
+			boot sequence.  If enabled, we use a weak hash instead
+			of siphash to hash pointers.  Use this option if you are
+			seeing instances of '(___ptrval___)') and need to see a
+			value (hashed pointer) instead. Cryptographically
+			insecure, please do not use on production kernels.
+
+	debug_locks_verbose=
+			[KNL] verbose locking self-tests
+			Format: <int>
+			Print debugging info while doing the locking API
+			self-tests.
+			Bitmask for the various LOCKTYPE_ tests. Defaults to 0
+			(no extra messages), setting it to -1 (all bits set)
+			will print _a_lot_ more information - normally only
+			useful to lockdep developers.
+
+	debug_objects	[KNL,EARLY] Enable object debugging
+
+	debug_guardpage_minorder=
+			[KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this
+			parameter allows control of the order of pages that will
+			be intentionally kept free (and hence protected) by the
+			buddy allocator. Bigger value increase the probability
+			of catching random memory corruption, but reduce the
+			amount of memory for normal system use. The maximum
+			possible value is MAX_PAGE_ORDER/2.  Setting this
+			parameter to 1 or 2 should be enough to identify most
+			random memory corruption problems caused by bugs in
+			kernel or driver code when a CPU writes to (or reads
+			from) a random memory location. Note that there exists
+			a class of memory corruptions problems caused by buggy
+			H/W or F/W or by drivers badly programming DMA
+			(basically when memory is written at bus level and the
+			CPU MMU is bypassed) which are not detectable by
+			CONFIG_DEBUG_PAGEALLOC, hence this option will not
+			help tracking down these problems.
+
+	debug_pagealloc=
+			[KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
+			enables the feature at boot time. By default, it is
+			disabled and the system will work mostly the same as a
+			kernel built without CONFIG_DEBUG_PAGEALLOC.
+			Note: to get most of debug_pagealloc error reports, it's
+			useful to also enable the page_owner functionality.
+			on: enable the feature
+
+	debugfs=    	[KNL,EARLY] This parameter enables what is exposed to
+			userspace and debugfs internal clients.
+			Format: { on, off }
+			on: 	All functions are enabled.
+			off: 	Filesystem is not registered and clients
+			        get a -EPERM as result when trying to register files
+				or directories within debugfs.
+				This is equivalent of the runtime functionality if
+				debugfs was not enabled in the kernel at all.
+			Default value is set in build-time with a kernel configuration.
+
+	debugpat	[X86] Enable PAT debugging
+
+	default_hugepagesz=
+			[HW] The size of the default HugeTLB page. This is
+			the size represented by the legacy /proc/ hugepages
+			APIs.  In addition, this is the default hugetlb size
+			used for shmget(), mmap() and mounting hugetlbfs
+			filesystems.  If not specified, defaults to the
+			architecture's default huge page size.  Huge page
+			sizes are architecture dependent.  See also
+			Documentation/admin-guide/mm/hugetlbpage.rst.
+			Format: size[KMG]
+
+	deferred_probe_timeout=
+			[KNL] Debugging option to set a timeout in seconds for
+			deferred probe to give up waiting on dependencies to
+			probe. Only specific dependencies (subsystems or
+			drivers) that have opted in will be ignored. A timeout
+			of 0 will timeout at the end of initcalls; a negative
+			value is treated as an infinite timeout value. If the
+			timeout hasn't expired, it'll be restarted by each
+			successful driver registration. This option will also
+			dump out devices still on the deferred probe list after
+			retrying.
+
+	delayacct	[KNL] Enable per-task delay accounting
+
+	dell_smm_hwmon.ignore_dmi=
+			[HW] Continue probing hardware even if DMI data
+			indicates that the driver is running on unsupported
+			hardware.
+
+	dell_smm_hwmon.force=
+			[HW] Activate driver even if SMM BIOS signature does
+			not match list of supported models and enable otherwise
+			blacklisted features.
+
+	dell_smm_hwmon.power_status=
+			[HW] Report power status in /proc/i8k
+			(disabled by default).
+
+	dell_smm_hwmon.restricted=
+			[HW] Allow controlling fans only if SYS_ADMIN
+			capability is set.
+
+	dell_smm_hwmon.fan_mult=
+			[HW] Factor to multiply fan speed with.
+
+	dell_smm_hwmon.fan_max=
+			[HW] Maximum configurable fan speed.
+
+	dfltcc=		[HW,S390]
+			Format: { on | off | def_only | inf_only | always }
+			on:       s390 zlib hardware support for compression on
+			          level 1 and decompression (default)
+			off:      No s390 zlib hardware support
+			def_only: s390 zlib hardware support for deflate
+			          only (compression on level 1)
+			inf_only: s390 zlib hardware support for inflate
+			          only (decompression)
+			always:   Same as 'on' but ignores the selected compression
+			          level always using hardware support (used for debugging)
+
+	dhash_entries=	[KNL]
+			Set number of hash buckets for dentry cache.
+
+	disable_1tb_segments [PPC,EARLY]
+			Disables the use of 1TB hash page table segments. This
+			causes the kernel to fall back to 256MB segments which
+			can be useful when debugging issues that require an SLB
+			miss to occur.
+
+	disable=	[IPV6]
+			See Documentation/networking/ipv6.rst.
+
+	disable_radix	[PPC,EARLY]
+			Disable RADIX MMU mode on POWER9
+
+	disable_tlbie	[PPC]
+			Disable TLBIE instruction. Currently does not work
+			with KVM, with HASH MMU, or with coherent accelerators.
+
+	disable_ddw	[PPC/PSERIES,EARLY]
+			Disable Dynamic DMA Window support. Use this
+			to workaround buggy firmware.
+
+	disable_ipv6=	[IPV6]
+			See Documentation/networking/ipv6.rst.
+
+	disable_mtrr_cleanup [X86,EARLY]
+			The kernel tries to adjust MTRR layout from continuous
+			to discrete, to make X server driver able to add WB
+			entry later. This parameter disables that.
+
+	disable_mtrr_trim [X86, Intel and AMD only,EARLY]
+			By default the kernel will trim any uncacheable
+			memory out of your available memory pool based on
+			MTRR settings.  This parameter disables that behavior,
+			possibly causing your machine to run very slowly.
+
+	disable_timer_pin_1 [X86,EARLY]
+			Disable PIN 1 of APIC timer
+			Can be useful to work around chipset bugs.
+
+	dis_ucode_ldr	[X86] Disable the microcode loader.
+
+	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
+			this option disables the debugging code at boot.
+
+	dma_debug_entries=<number>
+			This option allows to tune the number of preallocated
+			entries for DMA-API debugging code. One entry is
+			required per DMA-API allocation. Use this if the
+			DMA-API debugging code disables itself because the
+			architectural default is too low.
+
+	dma_debug_driver=<driver_name>
+			With this option the DMA-API debugging driver
+			filter feature can be enabled at boot time. Just
+			pass the driver to filter for as the parameter.
+			The filter can be disabled or changed to another
+			driver later using sysfs.
+
+	reg_file_data_sampling=
+			[X86] Controls mitigation for Register File Data
+			Sampling (RFDS) vulnerability. RFDS is a CPU
+			vulnerability which may allow userspace to infer
+			kernel data values previously stored in floating point
+			registers, vector registers, or integer registers.
+			RFDS only affects Intel Atom processors.
+
+			on:	Turns ON the mitigation.
+			off:	Turns OFF the mitigation.
+
+			This parameter overrides the compile time default set
+			by CONFIG_MITIGATION_RFDS. Mitigation cannot be
+			disabled when other VERW based mitigations (like MDS)
+			are enabled. In order to disable RFDS mitigation all
+			VERW based mitigations need to be disabled.
+
+			For details see:
+			Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst
+
+	dm_verity.keyring_unsealed=
+			[KNL] When set to 1, leave the dm-verity keyring
+			unsealed after initialization so userspace can
+			provision keys. Once the keyring is restricted
+			it becomes active and is searched during signature
+			verification.
+
+	driver_async_probe=  [KNL]
+			List of driver names to be probed asynchronously. *
+			matches with all driver names. If * is specified, the
+			rest of the listed driver names are those that will NOT
+			match the *.
+			Format: <driver_name1>,<driver_name2>...
+
+	drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
+			Broken monitors, graphic adapters, KVMs and EDIDless
+			panels may send no or incorrect EDID data sets.
+			This parameter allows to specify an EDID data sets
+			in the /lib/firmware directory that are used instead.
+			An EDID data set will only be used for a particular
+			connector, if its name and a colon are prepended to
+			the EDID name. Each connector may use a unique EDID
+			data set by separating the files with a comma. An EDID
+			data set with no connector name will be used for
+			any connectors not explicitly specified.
+
+	dscc4.setup=	[NET]
+
+	dt_cpu_ftrs=	[PPC,EARLY]
+			Format: {"off" | "known"}
+			Control how the dt_cpu_ftrs device-tree binding is
+			used for CPU feature discovery and setup (if it
+			exists).
+			off: Do not use it, fall back to legacy cpu table.
+			known: Do not pass through unknown features to guests
+			or userspace, only those that the kernel is aware of.
+
+	dump_apple_properties	[X86]
+			Dump name and content of EFI device properties on
+			x86 Macs.  Useful for driver authors to determine
+			what data is available or for reverse-engineering.
+
+	dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
+	<module>.dyndbg[="val"]
+			Enable debug messages at boot time.  See
+			Documentation/admin-guide/dynamic-debug-howto.rst
+			for details.
+
+	early_ioremap_debug [KNL,EARLY]
+			Enable debug messages in early_ioremap support. This
+			is useful for tracking down temporary early mappings
+			which are not unmapped.
+
+	earlycon=	[KNL,EARLY] Output early console device and options.
+
+			When used with no options, the early console is
+			determined by stdout-path property in device tree's
+			chosen node or the ACPI SPCR table if supported by
+			the platform.
+
+		cdns,<addr>[,options]
+			Start an early, polled-mode console on a Cadence
+			(xuartps) serial port at the specified address. Only
+			supported option is baud rate. If baud rate is not
+			specified, the serial port must already be setup and
+			configured.
+
+		uart[8250],io,<addr>[,options[,uartclk]]
+		uart[8250],mmio,<addr>[,options[,uartclk]]
+		uart[8250],mmio32,<addr>[,options[,uartclk]]
+		uart[8250],mmio32be,<addr>[,options[,uartclk]]
+		uart[8250],0x<addr>[,options]
+			Start an early, polled-mode console on the 8250/16550
+			UART at the specified I/O port or MMIO address.
+			MMIO inter-register address stride is either 8-bit
+			(mmio) or 32-bit (mmio32 or mmio32be).
+			If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
+			to be equivalent to 'mmio'. 'options' are specified
+			in the same format described for "console=ttyS<n>"; if
+			unspecified, the h/w is not initialized. 'uartclk' is
+			the uart clock frequency; if unspecified, it is set
+			to 'BASE_BAUD' * 16.
+
+		pl011,<addr>
+		pl011,mmio32,<addr>
+			Start an early, polled-mode console on a pl011 serial
+			port at the specified address. The pl011 serial port
+			must already be setup and configured. Options are not
+			yet supported.  If 'mmio32' is specified, then only
+			the driver will use only 32-bit accessors to read/write
+			the device registers.
+
+		liteuart,<addr>
+			Start an early console on a litex serial port at the
+			specified address. The serial port must already be
+			setup and configured. Options are not yet supported.
+
+		meson,<addr>
+			Start an early, polled-mode console on a meson serial
+			port at the specified address. The serial port must
+			already be setup and configured. Options are not yet
+			supported.
+
+		msm_serial,<addr>
+			Start an early, polled-mode console on an msm serial
+			port at the specified address. The serial port
+			must already be setup and configured. Options are not
+			yet supported.
+
+		msm_serial_dm,<addr>
+			Start an early, polled-mode console on an msm serial
+			dm port at the specified address. The serial port
+			must already be setup and configured. Options are not
+			yet supported.
+
+		owl,<addr>
+			Start an early, polled-mode console on a serial port
+			of an Actions Semi SoC, such as S500 or S900, at the
+			specified address. The serial port must already be
+			setup and configured. Options are not yet supported.
+
+		rda,<addr>
+			Start an early, polled-mode console on a serial port
+			of an RDA Micro SoC, such as RDA8810PL, at the
+			specified address. The serial port must already be
+			setup and configured. Options are not yet supported.
+
+		sbi
+			Use RISC-V SBI (Supervisor Binary Interface) for early
+			console.
+
+		smh	Use ARM semihosting calls for early console.
+
+		s3c2410,<addr>
+		s3c2412,<addr>
+		s3c2440,<addr>
+		s3c6400,<addr>
+		s5pv210,<addr>
+		exynos4210,<addr>
+			Use early console provided by serial driver available
+			on Samsung SoCs, requires selecting proper type and
+			a correct base address of the selected UART port. The
+			serial port must already be setup and configured.
+			Options are not yet supported.
+
+		lantiq,<addr>
+			Start an early, polled-mode console on a lantiq serial
+			(lqasc) port at the specified address. The serial port
+			must already be setup and configured. Options are not
+			yet supported.
+
+		lpuart,<addr>
+		lpuart32,<addr>
+			Use early console provided by Freescale LP UART driver
+			found on Freescale Vybrid and QorIQ LS1021A processors.
+			A valid base address must be provided, and the serial
+			port must already be setup and configured.
+
+		ec_imx21,<addr>
+		ec_imx6q,<addr>
+			Start an early, polled-mode, output-only console on the
+			Freescale i.MX UART at the specified address. The UART
+			must already be setup and configured.
+
+		ar3700_uart,<addr>
+			Start an early, polled-mode console on the
+			Armada 3700 serial port at the specified
+			address. The serial port must already be setup
+			and configured. Options are not yet supported.
+
+		qcom_geni,<addr>
+			Start an early, polled-mode console on a Qualcomm
+			Generic Interface (GENI) based serial port at the
+			specified address. The serial port must already be
+			setup and configured. Options are not yet supported.
+
+		efifb,[options]
+			Start an early, unaccelerated console on the EFI
+			memory mapped framebuffer (if available). On cache
+			coherent non-x86 systems that use system memory for
+			the framebuffer, pass the 'ram' option so that it is
+			mapped with the correct attributes.
+
+		linflex,<addr>
+			Use early console provided by Freescale LINFlexD UART
+			serial driver for NXP S32V234 SoCs. A valid base
+			address must be provided, and the serial port must
+			already be setup and configured.
+
+	earlyprintk=	[X86,SH,ARM,M68k,S390,UM,EARLY]
+			earlyprintk=vga
+			earlyprintk=sclp
+			earlyprintk=xen
+			earlyprintk=serial[,ttySn[,baudrate]]
+			earlyprintk=serial[,0x...[,baudrate]]
+			earlyprintk=ttySn[,baudrate]
+			earlyprintk=dbgp[debugController#]
+			earlyprintk=mmio32,membase[,{nocfg|baudrate}]
+			earlyprintk=pciserial[,force],bus:device.function[,{nocfg|baudrate}]
+			earlyprintk=xdbc[xhciController#]
+			earlyprintk=bios
+
+			earlyprintk is useful when the kernel crashes before
+			the normal console is initialized. It is not enabled by
+			default because it has some cosmetic problems.
+
+			Use "nocfg" to skip UART configuration, assume
+			BIOS/firmware has configured UART correctly.
+
+			Append ",keep" to not disable it when the real console
+			takes over.
+
+			Only one of vga, serial, or usb debug port can
+			be used at a time.
+
+			Currently only ttyS0 and ttyS1 may be specified by
+			name.  Other I/O ports may be explicitly specified
+			on some architectures (x86 and arm at least) by
+			replacing ttySn with an I/O port address, like this:
+				earlyprintk=serial,0x1008,115200
+			You can find the port for a given device in
+			/proc/tty/driver/serial:
+				2: uart:ST16650V2 port:00001008 irq:18 ...
+
+			Interaction with the standard serial driver is not
+			very good.
+
+			The VGA output is eventually overwritten by
+			the real console.
+
+			The xen option can only be used in Xen domains.
+
+			The sclp output can only be used on s390.
+
+			The bios output can only be used on SuperH.
+
+			The optional "force" to "pciserial" enables use of a
+			PCI device even when its classcode is not of the
+			UART class.
+
+	edac_report=	[HW,EDAC] Control how to report EDAC event
+			Format: {"on" | "off" | "force"}
+			on: enable EDAC to report H/W event. May be overridden
+			by other higher priority error reporting module.
+			off: disable H/W event reporting through EDAC.
+			force: enforce the use of EDAC to report H/W event.
+			default: on.
+
+	edd=		[EDD]
+			Format: {"off" | "on" | "skip[mbr]"}
+
+	efi=		[EFI,EARLY]
+			Format: { "debug", "disable_early_pci_dma",
+				  "nochunk", "noruntime", "nosoftreserve",
+				  "novamap", "no_disable_early_pci_dma" }
+			debug: enable misc debug output.
+			disable_early_pci_dma: disable the busmaster bit on all
+			PCI bridges while in the EFI boot stub.
+			nochunk: disable reading files in "chunks" in the EFI
+			boot stub, as chunking can cause problems with some
+			firmware implementations.
+			noruntime : disable EFI runtime services support
+			nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
+			attribute may cause the kernel to reserve the
+			memory range for a memory mapping driver to
+			claim. Specify efi=nosoftreserve to disable this
+			reservation and treat the memory by its base type
+			(i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
+			novamap: do not call SetVirtualAddressMap().
+			no_disable_early_pci_dma: Leave the busmaster bit set
+			on all PCI bridges while in the EFI boot stub
+
+	efi_no_storage_paranoia [EFI,X86,EARLY]
+			The kernel reserves 5KB of EFI variable storage for
+			safety, because some UEFI implementation may fail to
+			boot if there's insufficient space in the EFI variable
+			storage.
+
+			Using this parameter, you can use the 5KB reservation
+			in the EFI variable storage.
+
+			However, Use this parameter only if you are really
+			sure that your UEFI does sane gc and fulfills the spec
+			otherwise your board may brick.
+
+	efivar_ssdt=	[EFI; X86] Name of an EFI variable that contains an SSDT
+			that is to be dynamically loaded by Linux. If there are
+			multiple variables with the same name but with different
+			vendor GUIDs, all of them will be loaded. See
+			Documentation/admin-guide/acpi/ssdt-overlays.rst for details.
+
+
+	eisa_irq_edge=	[PARISC,HW]
+			See header of drivers/parisc/eisa.c.
+
+	ekgdboc=	[X86,KGDB,EARLY] Allow early kernel console debugging
+			Format: ekgdboc=kbd
+
+			This is designed to be used in conjunction with
+			the boot argument: earlyprintk=vga
+
+			This parameter works in place of the kgdboc parameter
+			but can only be used if the backing tty is available
+			very early in the boot process. For early debugging
+			via a serial port see kgdboc_earlycon instead.
+
+	elfcorehdr=[size[KMG]@]offset[KMG] [PPC,SH,X86,S390,EARLY]
+			Specifies physical address of start of kernel core
+			image elf header and optionally the size. Generally
+			kexec loader will pass this option to capture kernel.
+			See Documentation/admin-guide/kdump/kdump.rst for details.
+
+	enable_mtrr_cleanup [X86,EARLY]
+			The kernel tries to adjust MTRR layout from continuous
+			to discrete, to make X server driver able to add WB
+			entry later. This parameter enables that.
+
+	enable_timer_pin_1 [X86]
+			Enable PIN 1 of APIC timer
+			Can be useful to work around chipset bugs
+			(in particular on some ATI chipsets).
+			The kernel tries to set a reasonable default.
+
+	enforcing=	[SELINUX] Set initial enforcing status.
+			Format: {"0" | "1"}
+			See security/selinux/Kconfig help text.
+			0 -- permissive (log only, no denials).
+			1 -- enforcing (deny and log).
+			Default value is 0.
+			Value can be changed at runtime via
+			/sys/fs/selinux/enforce.
+
+	erst_disable	[ACPI]
+			Disable Error Record Serialization Table (ERST)
+			support.
+
+	ether=		[HW,NET] Ethernet cards parameters
+			This option is obsoleted by the "netdev=" option, which
+			has equivalent usage. See its documentation for details.
+
+	evm=		[EVM]
+			Format: { "fix" }
+			Permit 'security.evm' to be updated regardless of
+			current integrity status.
+
+	early_page_ext [KNL,EARLY] Enforces page_ext initialization to earlier
+			stages so cover more early boot allocations.
+			Please note that as side effect some optimizations
+			might be disabled to achieve that (e.g. parallelized
+			memory initialization is disabled) so the boot process
+			might take longer, especially on systems with a lot of
+			memory. Available with CONFIG_PAGE_EXTENSION=y.
+
+	failslab=
+	fail_usercopy=
+	fail_page_alloc=
+	fail_skb_realloc=
+	fail_make_request=[KNL]
+			General fault injection mechanism.
+			Format: <interval>,<probability>,<space>,<times>
+			See also Documentation/fault-injection/.
+
+	fb_tunnels=	[NET]
+			Format: { initns | none }
+			See Documentation/admin-guide/sysctl/net.rst for
+			fb_tunnels_only_for_init_ns
+
+	floppy=		[HW]
+			See Documentation/admin-guide/blockdev/floppy.rst.
+
+	forcepae	[X86-32]
+			Forcefully enable Physical Address Extension (PAE).
+			Many Pentium M systems disable PAE but may have a
+			functionally usable PAE implementation.
+			Warning: use of this parameter will taint the kernel
+			and may cause unknown problems.
+
+	fred=		[X86-64]
+			Enable/disable Flexible Return and Event Delivery.
+			Format: { on | off }
+			on: enable FRED when it's present, the default setting.
+			off: disable FRED.
+
+	ftrace=[tracer]
+			[FTRACE] will set and start the specified tracer
+			as early as possible in order to facilitate early
+			boot debugging.
+
+	ftrace_boot_snapshot
+			[FTRACE] On boot up, a snapshot will be taken of the
+			ftrace ring buffer that can be read at:
+			/sys/kernel/tracing/snapshot.
+			This is useful if you need tracing information from kernel
+			boot up that is likely to be overridden by user space
+			start up functionality.
+
+			Optionally, the snapshot can also be defined for a tracing
+			instance that was created by the trace_instance= command
+			line parameter.
+
+			trace_instance=foo,sched_switch ftrace_boot_snapshot=foo
+
+			The above will cause the "foo" tracing instance to trigger
+			a snapshot at the end of boot up.
+
+	ftrace_dump_on_oops[=2(orig_cpu) | =<instance>][,<instance> |
+			  ,<instance>=2(orig_cpu)]
+			[FTRACE] will dump the trace buffers on oops.
+			If no parameter is passed, ftrace will dump global
+			buffers of all CPUs, if you pass 2 or orig_cpu, it
+			will dump only the buffer of the CPU that triggered
+			the oops, or the specific instance will be dumped if
+			its name is passed. Multiple instance dump is also
+			supported, and instances are separated by commas. Each
+			instance supports only dump on CPU that triggered the
+			oops by passing 2 or orig_cpu to it.
+
+			ftrace_dump_on_oops=foo=orig_cpu
+
+			The above will dump only the buffer of "foo" instance
+			on CPU that triggered the oops.
+
+			ftrace_dump_on_oops,foo,bar=orig_cpu
+
+			The above will dump global buffer on all CPUs, the
+			buffer of "foo" instance on all CPUs and the buffer
+			of "bar" instance on CPU that triggered the oops.
+
+	ftrace_filter=[function-list]
+			[FTRACE] Limit the functions traced by the function
+			tracer at boot up. function-list is a comma-separated
+			list of functions. This list can be changed at run
+			time by the set_ftrace_filter file in the debugfs
+			tracing directory.
+
+	ftrace_notrace=[function-list]
+			[FTRACE] Do not trace the functions specified in
+			function-list. This list can be changed at run time
+			by the set_ftrace_notrace file in the debugfs
+			tracing directory.
+
+	ftrace_graph_filter=[function-list]
+			[FTRACE] Limit the top level callers functions traced
+			by the function graph tracer at boot up.
+			function-list is a comma-separated list of functions
+			that can be changed at run time by the
+			set_graph_function file in the debugfs tracing directory.
+
+	ftrace_graph_notrace=[function-list]
+			[FTRACE] Do not trace from the functions specified in
+			function-list.  This list is a comma-separated list of
+			functions that can be changed at run time by the
+			set_graph_notrace file in the debugfs tracing directory.
+
+	ftrace_graph_max_depth=<uint>
+			[FTRACE] Used with the function graph tracer. This is
+			the max depth it will trace into a function. This value
+			can be changed at run time by the max_graph_depth file
+			in the tracefs tracing directory. default: 0 (no limit)
+
+	fw_devlink=	[KNL,EARLY] Create device links between consumer and supplier
+			devices by scanning the firmware to infer the
+			consumer/supplier relationships. This feature is
+			especially useful when drivers are loaded as modules as
+			it ensures proper ordering of tasks like device probing
+			(suppliers first, then consumers), supplier boot state
+			clean up (only after all consumers have probed),
+			suspend/resume & runtime PM (consumers first, then
+			suppliers).
+			Format: { off | permissive | on | rpm }
+			off --	Don't create device links from firmware info.
+			permissive -- Create device links from firmware info
+				but use it only for ordering boot state clean
+				up (sync_state() calls).
+			on -- 	Create device links from firmware info and use it
+				to enforce probe and suspend/resume ordering.
+			rpm --	Like "on", but also use to order runtime PM.
+
+	fw_devlink.strict=<bool>
+			[KNL,EARLY] Treat all inferred dependencies as mandatory
+			dependencies. This only applies for fw_devlink=on|rpm.
+			Format: <bool>
+
+	fw_devlink.sync_state =
+			[KNL,EARLY] When all devices that could probe have finished
+			probing, this parameter controls what to do with
+			devices that haven't yet received their sync_state()
+			calls.
+			Format: { strict | timeout }
+			strict -- Default. Continue waiting on consumers to
+				probe successfully.
+			timeout -- Give up waiting on consumers and call
+				sync_state() on any devices that haven't yet
+				received their sync_state() calls after
+				deferred_probe_timeout has expired or by
+				late_initcall() if !CONFIG_MODULES.
+
+	gamecon.map[2|3]=
+			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
+			support via parallel port (up to 5 devices per port)
+			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
+			See also Documentation/input/devices/joystick-parport.rst
+
+	gamma=		[HW,DRM]
+
+	gart_fix_e820=	[X86-64,EARLY] disable the fix e820 for K8 GART
+			Format: off | on
+			default: on
+
+	gather_data_sampling=
+			[X86,INTEL,EARLY] Control the Gather Data Sampling (GDS)
+			mitigation.
+
+			Gather Data Sampling is a hardware vulnerability which
+			allows unprivileged speculative access to data which was
+			previously stored in vector registers.
+
+			This issue is mitigated by default in updated microcode.
+			The mitigation may have a performance impact but can be
+			disabled. On systems without the microcode mitigation
+			disabling AVX serves as a mitigation.
+
+			force:	Disable AVX to mitigate systems without
+				microcode mitigation. No effect if the microcode
+				mitigation is present. Known to cause crashes in
+				userspace with buggy AVX enumeration.
+
+			off:	Disable GDS mitigation.
+
+	gbpages		[X86] Use GB pages for kernel direct mappings.
+
+	gcov_persist=	[GCOV] When non-zero (default), profiling data for
+			kernel modules is saved and remains accessible via
+			debugfs, even when the module is unloaded/reloaded.
+			When zero, profiling data is discarded and associated
+			debugfs files are removed at module unload time.
+
+	goldfish	[X86] Enable the goldfish android emulator platform.
+			Don't use this when you are not running on the
+			android emulator
+
+	gpio-mockup.gpio_mockup_ranges
+			[HW] Sets the ranges of gpiochip of for this device.
+			Format: <start1>,<end1>,<start2>,<end2>...
+	gpio-mockup.gpio_mockup_named_lines
+			[HW] Let the driver know GPIO lines should be named.
+
+	gpt		[EFI] Forces disk with valid GPT signature but
+			invalid Protective MBR to be treated as GPT. If the
+			primary GPT is corrupted, it enables the backup/alternate
+			GPT to be used instead.
+
+	grcan.enable0=	[HW] Configuration of physical interface 0. Determines
+			the "Enable 0" bit of the configuration register.
+			Format: 0 | 1
+			Default: 0
+	grcan.enable1=	[HW] Configuration of physical interface 1. Determines
+			the "Enable 0" bit of the configuration register.
+			Format: 0 | 1
+			Default: 0
+	grcan.select=	[HW] Select which physical interface to use.
+			Format: 0 | 1
+			Default: 0
+	grcan.txsize=	[HW] Sets the size of the tx buffer.
+			Format: <unsigned int> such that (txsize & ~0x1fffc0) == 0.
+			Default: 1024
+	grcan.rxsize=	[HW] Sets the size of the rx buffer.
+			Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0.
+			Default: 1024
+
+	hardened_usercopy=
+			[KNL] Under CONFIG_HARDENED_USERCOPY, whether
+			hardening is enabled for this boot. Hardened
+			usercopy checking is used to protect the kernel
+			from reading or writing beyond known memory
+			allocation boundaries as a proactive defense
+			against bounds-checking flaws in the kernel's
+			copy_to_user()/copy_from_user() interface.
+			The default is determined by
+			CONFIG_HARDENED_USERCOPY_DEFAULT_ON.
+		on	Perform hardened usercopy checks.
+		off	Disable hardened usercopy checks.
+
+	hardlockup_all_cpu_backtrace=
+			[KNL] Should the hard-lockup detector generate
+			backtraces on all cpus.
+			Format: 0 | 1
+
+	hash_pointers=
+			[KNL,EARLY]
+			By default, when pointers are printed to the console
+			or buffers via the %p format string, that pointer is
+			"hashed", i.e. obscured by hashing the pointer value.
+			This is a security feature that hides actual kernel
+			addresses from unprivileged users, but it also makes
+			debugging the kernel more difficult since unequal
+			pointers can no longer be compared. The choices are:
+			Format: { auto | always | never }
+			Default: auto
+
+			auto   - Hash pointers unless slab_debug is enabled.
+			always - Always hash pointers (even if slab_debug is
+				 enabled).
+			never  - Never hash pointers. This option should only
+				 be specified when debugging the kernel. Do
+				 not use on production kernels. The boot
+				 param "no_hash_pointers" is an alias for
+				 this mode.
+
+			For controlling hashing dynamically at runtime,
+			use the "kernel.kptr_restrict" sysctl instead.
+
+	hashdist=	[KNL,NUMA] Large hashes allocated during boot
+			are distributed across NUMA nodes.  Defaults on
+			for 64-bit NUMA, off otherwise.
+			Format: 0 | 1 (for off | on)
+
+	hd=		[EIDE] (E)IDE hard drive subsystem geometry
+			Format: <cyl>,<head>,<sect>
+
+	hest_disable	[ACPI]
+			Disable Hardware Error Source Table (HEST) support;
+			corresponding firmware-first mode error processing
+			logic will be disabled.
+
+	hibernate=	[HIBERNATION]
+		noresume	Don't check if there's a hibernation image
+				present during boot.
+		nocompress	Don't compress/decompress hibernation images.
+		no		Disable hibernation and resume.
+		protect_image	Turn on image protection during restoration
+				(that will set all pages holding image data
+				during restoration read-only).
+
+	hibernate.compressor= 	[HIBERNATION] Compression algorithm to be
+				used with hibernation.
+				Format: { lzo | lz4 }
+				Default: lzo
+
+				lzo: Select LZO compression algorithm to
+				compress/decompress hibernation image.
+
+				lz4: Select LZ4 compression algorithm to
+				compress/decompress hibernation image.
+
+	hibernate.pm_test_delay=
+			[HIBERNATION]
+			Sets the number of seconds to remain in a hibernation test
+			mode before resuming the system (see
+			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
+			is set. Default value is 5.
+
+	hibernate_compression_threads=
+			[HIBERNATION]
+			Set the number of threads used for compressing or decompressing
+			hibernation images.
+
+			Format: <integer>
+			Default: 3
+			Minimum: 1
+			Example: hibernate_compression_threads=4
+
+	highmem=nn[KMG]	[KNL,BOOT,EARLY] forces the highmem zone to have an exact
+			size of <nn>. This works even on boxes that have no
+			highmem otherwise. This also works to reduce highmem
+			size on bigger boxes.
+
+	highres=	[KNL] Enable/disable high resolution timer mode.
+			Valid parameters: "on", "off"
+			Default: "on"
+
+	hlt		[BUGS=ARM,SH]
+
+	hostname=	[KNL,EARLY] Set the hostname (aka UTS nodename).
+			Format: <string>
+			This allows setting the system's hostname during early
+			startup. This sets the name returned by gethostname.
+			Using this parameter to set the hostname makes it
+			possible to ensure the hostname is correctly set before
+			any userspace processes run, avoiding the possibility
+			that a process may call gethostname before the hostname
+			has been explicitly set, resulting in the calling
+			process getting an incorrect result. The string must
+			not exceed the maximum allowed hostname length (usually
+			64 characters) and will be truncated otherwise.
+
+	hpet=		[X86-32,HPET] option to control HPET usage
+			Format: { enable (default) | disable | force |
+				verbose }
+			disable: disable HPET and use PIT instead
+			force: allow force enabled of undocumented chips (ICH4,
+				VIA, nVidia)
+			verbose: show contents of HPET registers during setup
+
+	hpet_mmap=	[X86, HPET_MMAP] Allow userspace to mmap HPET
+			registers.  Default set by CONFIG_HPET_MMAP_DEFAULT.
+
+	hugepages=	[HW,EARLY] Number of HugeTLB pages to allocate at boot.
+			If this follows hugepagesz (below), it specifies
+			the number of pages of hugepagesz to be allocated.
+			If this is the first HugeTLB parameter on the command
+			line, it specifies the number of pages to allocate for
+			the default huge page size. If using node format, the
+			number of pages to allocate per-node can be specified.
+			See also Documentation/admin-guide/mm/hugetlbpage.rst.
+			Format: <integer> or (node format)
+				<node>:<integer>[,<node>:<integer>]
+
+	hugepagesz=
+			[HW,EARLY] The size of the HugeTLB pages.  This is
+			used in conjunction with hugepages (above) to
+			allocate huge pages of a specific size at boot. The
+			pair hugepagesz=X hugepages=Y can be specified once
+			for each supported huge page size. Huge page sizes
+			are architecture dependent. See also
+			Documentation/admin-guide/mm/hugetlbpage.rst.
+			Format: size[KMG]
+
+	hugepage_alloc_threads=
+			[HW] The number of threads that should be used to
+			allocate hugepages during boot. This option can be
+			used to improve system bootup time when allocating
+			a large amount of huge pages.
+			The default value is 25% of the available hardware threads.
+
+			Note that this parameter only applies to non-gigantic huge pages.
+
+	hugetlb_cma=	[HW,CMA,EARLY] The size of a CMA area used for allocation
+			of gigantic hugepages. Or using node format, the size
+			of a CMA area per node can be specified.
+			The size can be an absolute value (e.g., 2G) or a
+			percentage of the total memory or node memory (e.g., 20%).
+			Percentage-derived sizes are rounded down to a multiple of
+			the architecture's gigantic hugepage size and may become
+			zero.
+			Format: nn[KMGTPE] or nn% or (node format)
+				<node>:nn[KMGTPE][,<node>:nn[KMGTPE]] or
+				<node>:nn%[,<node>:nn%]
+
+			The size must be a multiple of the gigantic page size.
+			When using node format, this applies to each per-node size.
+			Missaligned values are dropped with a warning.
+
+			Reserve a CMA area of given size and allocate gigantic
+			hugepages using the CMA allocator. If enabled, the
+			boot-time allocation of gigantic hugepages is skipped.
+
+	hugetlb_cma_only=
+			[HW,CMA,EARLY] When allocating new HugeTLB pages, only
+			try to allocate from the CMA areas.
+
+			This option does nothing if hugetlb_cma= is not also
+			specified.
+
+	hugetlb_free_vmemmap=
+			[KNL] Requires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+			enabled.
+			Control if HugeTLB Vmemmap Optimization (HVO) is enabled.
+			Allows heavy hugetlb users to free up some more
+			memory (7 * PAGE_SIZE for each 2MB hugetlb page).
+			Format: { on | off (default) }
+
+			on: enable HVO
+			off: disable HVO
+
+			Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y,
+			the default is on.
+
+			Note that the vmemmap pages may be allocated from the added
+			memory block itself when memory_hotplug.memmap_on_memory is
+			enabled, those vmemmap pages cannot be optimized even if this
+			feature is enabled.  Other vmemmap pages not allocated from
+			the added memory block itself do not be affected.
+
+	hung_task_panic=
+			[KNL] Number of hung tasks to trigger kernel panic.
+			Format: <int>
+
+			When set to a non-zero value, a kernel panic will be triggered if
+			the number of detected hung tasks reaches this value.
+
+			0: don't panic
+			1: panic immediately on first hung task
+			N: panic after N hung tasks are detected in a single scan
+
+			The default value is controlled by the
+			CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time option. The value
+			selected by this boot parameter can be changed later by the
+			kernel.hung_task_panic sysctl.
+
+	hvc_iucv=	[S390]	Number of z/VM IUCV hypervisor console (HVC)
+				terminal devices. Valid values: 0..8
+	hvc_iucv_allow=	[S390]	Comma-separated list of z/VM user IDs.
+				If specified, z/VM IUCV HVC accepts connections
+				from listed z/VM user IDs only.
+
+	hv_nopvspin	[X86,HYPER_V,EARLY]
+			Disables the paravirt spinlock optimizations
+			which allow the hypervisor to 'idle' the guest
+			on lock contention.
+
+	hw_protection=	[HW]
+			Format: reboot | shutdown
+
+			Hardware protection action taken on critical events like
+			overtemperature or imminent voltage loss.
+
+	i2c_bus=	[HW]	Override the default board specific I2C bus speed
+				or register an additional I2C bus that is not
+				registered from board initialization code.
+				Format:
+				<bus_id>,<clkrate>
+
+	i2c_touchscreen_props= [HW,ACPI,X86]
+			Set device-properties for ACPI-enumerated I2C-attached
+			touchscreen, to e.g. fix coordinates of upside-down
+			mounted touchscreens. If you need this option please
+			submit a drivers/platform/x86/touchscreen_dmi.c patch
+			adding a DMI quirk for this.
+
+			Format:
+			<ACPI_HW_ID>:<prop_name>=<val>[:prop_name=val][:...]
+			Where <val> is one of:
+			Omit "=<val>" entirely	Set a boolean device-property
+			Unsigned number		Set a u32 device-property
+			Anything else		Set a string device-property
+
+			Examples (split over multiple lines):
+			i2c_touchscreen_props=GDIX1001:touchscreen-inverted-x:
+			touchscreen-inverted-y
+
+			i2c_touchscreen_props=MSSL1680:touchscreen-size-x=1920:
+			touchscreen-size-y=1080:touchscreen-inverted-y:
+			firmware-name=gsl1680-vendor-model.fw:silead,home-button
+
+	i8042.debug	[HW] Toggle i8042 debug mode
+	i8042.unmask_kbd_data
+			[HW] Enable printing of interrupt data from the KBD port
+			     (disabled by default, and as a pre-condition
+			     requires that i8042.debug=1 be enabled)
+	i8042.direct	[HW] Put keyboard port into non-translated mode
+	i8042.dumbkbd	[HW] Pretend that controller can only read data from
+			     keyboard and cannot control its state
+			     (Don't attempt to blink the leds)
+	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
+	i8042.nokbd	[HW] Don't check/create keyboard port
+	i8042.noloop	[HW] Disable the AUX Loopback command while probing
+			     for the AUX port
+	i8042.nomux	[HW] Don't check presence of an active multiplexing
+			     controller
+	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
+			     controllers
+	i8042.notimeout	[HW] Ignore timeout condition signalled by controller
+	i8042.reset	[HW] Reset the controller during init, cleanup and
+			     suspend-to-ram transitions, only during s2r
+			     transitions, or never reset
+			Format: { 1 | Y | y | 0 | N | n }
+			1, Y, y: always reset controller
+			0, N, n: don't ever reset controller
+			Default: only on s2r transitions on x86; most other
+			architectures force reset to be always executed
+	i8042.unlock	[HW] Unlock (ignore) the keylock
+	i8042.kbdreset	[HW] Reset device connected to KBD port
+	i8042.probe_defer
+			[HW] Allow deferred probing upon i8042 probe errors
+
+	i810=		[HW,DRM]
+
+	i915.invert_brightness=
+			[DRM] Invert the sense of the variable that is used to
+			set the brightness of the panel backlight. Normally a
+			brightness value of 0 indicates backlight switched off,
+			and the maximum of the brightness value sets the backlight
+			to maximum brightness. If this parameter is set to 0
+			(default) and the machine requires it, or this parameter
+			is set to 1, a brightness value of 0 sets the backlight
+			to maximum brightness, and the maximum of the brightness
+			value switches the backlight off.
+			-1 -- never invert brightness
+			 0 -- machine default
+			 1 -- force brightness inversion
+
+	ia32_emulation=	[X86-64]
+			Format: <bool>
+			When true, allows loading 32-bit programs and executing 32-bit
+			syscalls, essentially overriding IA32_EMULATION_DEFAULT_DISABLED at
+			boot time. When false, unconditionally disables IA32 emulation.
+
+
+	idle=		[X86,EARLY]
+			Format: idle=poll, idle=halt, idle=nomwait
+
+			idle=poll:  Don't do power saving in the idle loop
+			using HLT, but poll for rescheduling event. This will
+			make the CPUs eat a lot more power, but may be useful
+			to get slightly better performance in multiprocessor
+			benchmarks. It also makes some profiling using
+			performance counters more accurate.  Please note that
+			on systems with MONITOR/MWAIT support (like Intel
+			EM64T CPUs) this option has no performance advantage
+			over the normal idle loop.  It may also interact badly
+			with hyperthreading.
+
+			idle=halt: Halt is forced to be used for CPU idle.
+			In such case C2/C3 won't be used again.
+
+			idle=nomwait: Disable mwait for CPU C-states
+
+			[ARM64,EARLY]
+			Format: idle=wfi, idle=yield, idle=nop
+
+			idle=wfi: Use the WFI (Wait For Interrupt) hint
+			instruction in the idle loop. This is the default and
+			allows the CPU to enter a low-power state until an
+			interrupt arrives.
+
+			idle=yield: Use the YIELD hint instruction instead of
+			WFI. CPUs supporting simultaneous multi-threading (SMT),
+			can continue executing another thread when the current
+			thread reaches the idle loop. This will make the CPUs
+			eat more power, but may be useful to get slightly better
+			performance in some applications, since the CPUs will
+			not enter a low-power state.
+
+			idle=nop: Do not execute any idle instruction in the
+			idle loop. This is useful on platforms where WFI
+			misbehaves, leading to system instability or loss of CPU
+			state. This will make the CPUs eat more power, but may
+			give slightly better performance in some applications,
+			since the CPUs will not enter a low-power state.
+
+	idxd.sva=	[HW]
+			Format: <bool>
+			Allow force disabling of Shared Virtual Memory (SVA)
+			support for the idxd driver. By default it is set to
+			true (1).
+
+	idxd.tc_override= [HW]
+			Format: <bool>
+			Allow override of default traffic class configuration
+			for the device. By default it is set to false (0).
+
+	ieee754=	[MIPS] Select IEEE Std 754 conformance mode
+			Format: { strict | legacy | 2008 | relaxed | emulated }
+			Default: strict
+
+			Choose which programs will be accepted for execution
+			based on the IEEE 754 NaN encoding(s) supported by
+			the FPU and the NaN encoding requested with the value
+			of an ELF file header flag individually set by each
+			binary.  Hardware implementations are permitted to
+			support either or both of the legacy and the 2008 NaN
+			encoding mode.
+
+			Available settings are as follows:
+			strict	accept binaries that request a NaN encoding
+				supported by the FPU
+			legacy	only accept legacy-NaN binaries, if supported
+				by the FPU
+			2008	only accept 2008-NaN binaries, if supported
+				by the FPU
+			relaxed	accept any binaries regardless of whether
+				supported by the FPU
+			emulated accept any binaries but enable FPU emulator
+				if binary mode is unsupported by the FPU.
+
+			The FPU emulator is always able to support both NaN
+			encodings, so if no FPU hardware is present or it has
+			been disabled with 'nofpu', then the settings of
+			'legacy' and '2008' strap the emulator accordingly,
+			'relaxed' straps the emulator for both legacy-NaN and
+			2008-NaN, whereas 'strict' enables legacy-NaN only on
+			legacy processors and both NaN encodings on MIPS32 or
+			MIPS64 CPUs.
+
+			The setting for ABS.fmt/NEG.fmt instruction execution
+			mode generally follows that for the NaN encoding,
+			except where unsupported by hardware.
+
+	ignore_loglevel	[KNL,EARLY]
+			Ignore loglevel setting - this will print /all/
+			kernel messages to the console. Useful for debugging.
+			We also add it as printk module parameter, so users
+			could change it dynamically, usually by
+			/sys/module/printk/parameters/ignore_loglevel.
+
+	ignore_rlimit_data
+			Ignore RLIMIT_DATA setting for data mappings,
+			print warning at first misuse.  Can be changed via
+			/sys/module/kernel/parameters/ignore_rlimit_data.
+
+	ihash_entries=	[KNL]
+			Set number of hash buckets for inode cache.
+
+	ima_appraise=	[IMA] appraise integrity measurements
+			Format: { "off" | "enforce" | "fix" | "log" }
+			default: "enforce"
+
+	ima_appraise_tcb [IMA] Deprecated.  Use ima_policy= instead.
+			The builtin appraise policy appraises all files
+			owned by uid=0.
+
+	ima_canonical_fmt [IMA]
+			Use the canonical format for the binary runtime
+			measurements, instead of host native format.
+
+	ima_flush_htable  [IMA]
+			Flush the IMA hash table when deleting all the
+			staged measurement records, to achieve maximum
+			memory saving at the cost of having duplicate
+			records across the staged measurement lists.
+
+	ima_hash=	[IMA]
+			Format: { md5 | sha1 | rmd160 | sha256 | sha384
+				   | sha512 | ... }
+			default: "sha1"
+
+			The list of supported hash algorithms is defined
+			in crypto/hash_info.h.
+
+	ima_policy=	[IMA]
+			The builtin policies to load during IMA setup.
+			Format: "tcb | appraise_tcb | secure_boot |
+				 fail_securely | critical_data"
+
+			The "tcb" policy measures all programs exec'd, files
+			mmap'd for exec, and all files opened with the read
+			mode bit set by either the effective uid (euid=0) or
+			uid=0.
+
+			The "appraise_tcb" policy appraises the integrity of
+			all files owned by root.
+
+			The "secure_boot" policy appraises the integrity
+			of files (eg. kexec kernel image, kernel modules,
+			firmware, policy, etc) based on file signatures.
+
+			The "fail_securely" policy forces file signature
+			verification failure also on privileged mounted
+			filesystems with the SB_I_UNVERIFIABLE_SIGNATURE
+			flag.
+
+			The "critical_data" policy measures kernel integrity
+			critical data.
+
+	ima_tcb		[IMA] Deprecated.  Use ima_policy= instead.
+			Load a policy which meets the needs of the Trusted
+			Computing Base.  This means IMA will measure all
+			programs exec'd, files mmap'd for exec, and all files
+			opened for read by uid=0.
+
+	ima_template=	[IMA]
+			Select one of defined IMA measurements template formats.
+			Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" |
+				   "ima-sigv2" }
+			Default: "ima-ng"
+
+	ima_template_fmt=
+			[IMA] Define a custom template format.
+			Format: { "field1|...|fieldN" }
+
+	ima=		[IMA] Enable or disable IMA
+			Format: { "off" | "on" }
+			Default: "on"
+			Note that disabling IMA is limited to kdump kernel.
+
+	indirect_target_selection= [X86,Intel] Mitigation control for Indirect
+			Target Selection(ITS) bug in Intel CPUs. Updated
+			microcode is also required for a fix in IBPB.
+
+			on:     Enable mitigation (default).
+			off:    Disable mitigation.
+			force:	Force the ITS bug and deploy default
+				mitigation.
+			vmexit: Only deploy mitigation if CPU is affected by
+				guest/host isolation part of ITS.
+			stuff:	Deploy RSB-fill mitigation when retpoline is
+				also deployed. Otherwise, deploy the default
+				mitigation.
+
+			For details see:
+			Documentation/admin-guide/hw-vuln/indirect-target-selection.rst
+
+	init=		[KNL]
+			Format: <full_path>
+			Run specified binary instead of /sbin/init as init
+			process.
+
+	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
+			for working out where the kernel is dying during
+			startup.
+
+	initcall_blacklist=  [KNL] Do not execute a comma-separated list of
+			initcall functions.  Useful for debugging built-in
+			modules and initcalls.
+
+	initramfs_async= [KNL]
+			Format: <bool>
+			Default: 1
+			This parameter controls whether the initramfs
+			image is unpacked asynchronously, concurrently
+			with devices being probed and
+			initialized. This should normally just work,
+			but as a debugging aid, one can get the
+			historical behaviour of the initramfs
+			unpacking being completed before device_ and
+			late_ initcalls.
+
+	initrd=		[BOOT,EARLY] Specify the location of the initial ramdisk
+
+	initrdmem=	[KNL,EARLY] Specify a physical address and size from which to
+			load the initrd. If an initrd is compiled in or
+			specified in the bootparams, it takes priority over this
+			setting.
+			Format: ss[KMG],nn[KMG]
+			Default is 0, 0
+
+	init_on_alloc=	[MM,EARLY] Fill newly allocated pages and heap objects with
+			zeroes.
+			Format: 0 | 1
+			Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.
+
+	init_on_free=	[MM,EARLY] Fill freed pages and heap objects with zeroes.
+			Format: 0 | 1
+			Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
+
+	init_pkru=	[X86] Specify the default memory protection keys rights
+			register contents for all processes.  0x55555554 by
+			default (disallow access to all but pkey 0).  Can
+			override in debugfs after boot.
+
+	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
+			Format: <irq>
+
+	int_pln_enable	[X86] Enable power limit notification interrupt
+
+	integrity_audit=[IMA]
+			Format: { "0" | "1" }
+			0 -- basic integrity auditing messages. (Default)
+			1 -- additional integrity auditing messages.
+
+	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
+		on
+			Enable intel iommu driver.
+		off
+			Disable intel iommu driver.
+		igfx_off [Default Off]
+			By default, gfx is mapped as normal device. If a gfx
+			device has a dedicated DMAR unit, the DMAR unit is
+			bypassed by not enabling DMAR with this option. In
+			this case, gfx device will use physical address for
+			DMA.
+		strict [Default Off]
+			Deprecated, equivalent to iommu.strict=1.
+		sp_off [Default Off]
+			By default, super page will be supported if Intel IOMMU
+			has the capability. With this option, super page will
+			not be supported.
+		sm_on
+			Enable the Intel IOMMU scalable mode if the hardware
+			advertises that it has support for the scalable mode
+			translation.
+		sm_off
+			Disallow use of the Intel IOMMU scalable mode.
+		tboot_noforce [Default Off]
+			Do not force the Intel IOMMU enabled under tboot.
+			By default, tboot will force Intel IOMMU on, which
+			could harm performance of some high-throughput
+			devices like 40GBit network cards, even if identity
+			mapping is enabled.
+			Note that using this option lowers the security
+			provided by tboot because it makes the system
+			vulnerable to DMA attacks.
+
+	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
+			0	disables intel_idle and fall back on acpi_idle.
+			1 to 9	specify maximum depth of C-state.
+
+	intel_pstate=	[X86,EARLY]
+			disable
+			  Do not enable intel_pstate as the default
+			  scaling driver for the supported processors
+                        active
+                          Use intel_pstate driver to bypass the scaling
+                          governors layer of cpufreq and provides it own
+                          algorithms for p-state selection. There are two
+                          P-state selection algorithms provided by
+                          intel_pstate in the active mode: powersave and
+                          performance.  The way they both operate depends
+                          on whether or not the hardware managed P-states
+                          (HWP) feature has been enabled in the processor
+                          and possibly on the processor model.
+			passive
+			  Use intel_pstate as a scaling driver, but configure it
+			  to work with generic cpufreq governors (instead of
+			  enabling its internal governor).  This mode cannot be
+			  used along with the hardware-managed P-states (HWP)
+			  feature.
+			force
+			  Enable intel_pstate on systems that prohibit it by default
+			  in favor of acpi-cpufreq. Forcing the intel_pstate driver
+			  instead of acpi-cpufreq may disable platform features, such
+			  as thermal controls and power capping, that rely on ACPI
+			  P-States information being indicated to OSPM and therefore
+			  should be used with caution. This option does not work with
+			  processors that aren't supported by the intel_pstate driver
+			  or on platforms that use pcc-cpufreq instead of acpi-cpufreq.
+			no_hwp
+			  Do not enable hardware P state control (HWP)
+			  if available.
+			hwp_only
+			  Only load intel_pstate on systems which support
+			  hardware P state control (HWP) if available.
+			support_acpi_ppc
+			  Enforce ACPI _PPC performance limits. If the Fixed ACPI
+			  Description Table, specifies preferred power management
+			  profile as "Enterprise Server" or "Performance Server",
+			  then this feature is turned on by default.
+			per_cpu_perf_limits
+			  Allow per-logical-CPU P-State performance control limits using
+			  cpufreq sysfs interface
+			no_cas
+			  Do not enable capacity-aware scheduling (CAS) on
+			  hybrid systems
+
+	intremap=	[X86-64,Intel-IOMMU,EARLY]
+			on	enable Interrupt Remapping (default)
+			off	disable Interrupt Remapping
+			nosid	disable Source ID checking
+			no_x2apic_optout
+				BIOS x2APIC opt-out request will be ignored
+			nopost	disable Interrupt Posting
+			posted_msi
+				enable MSIs delivered as posted interrupts
+
+	iomem=		Disable strict checking of access to MMIO memory
+		strict	regions from userspace.
+		relaxed
+
+	iommu=		[X86,EARLY]
+
+		off
+			Don't initialize and use any kind of IOMMU.
+
+		force
+			Force the use of the hardware IOMMU even when
+			it is not actually needed (e.g. because < 3 GB
+			memory).
+
+		noforce
+			Don't force hardware IOMMU usage when it is not
+			needed. (default).
+
+		merge
+			Do scatter-gather (SG) merging. Implies "force"
+			(experimental).
+
+		nomerge
+			Don't do scatter-gather (SG) merging.
+
+		biomerge
+			Do scatter-gather (SG) merging. Implies "force"
+			(experimental). [same as "merge"]
+
+		panic
+			Always panic when IOMMU overflows.
+
+		nopanic
+			Don't panic on IOMMU overflows.
+
+		pt
+			Use passththrough mode by default
+			(Equivalent to iommu.passthrough=1)
+
+		nopt
+			Use translated mode for DMA by default
+			(Equivalent to iommu.passthrough=0)
+
+		soft
+			Use software bounce buffering (SWIOTLB) (default for
+			Intel machines). This can be used to prevent the usage
+			of an available hardware IOMMU.
+
+		usedac
+			Use the DAC on VIA PCI bridge
+			(default: disable the VIA PCI bridge DAC)
+
+	    AMD Gart HW IOMMU-specific options: (CONFIG_GART_IOMMU)
+
+		<size>
+			Set the size of the remapping area in bytes.
+
+		allowed
+			Overwrite iommu off workarounds for specific chipsets
+
+		force
+			Overwrite iommu off workarounds for specific chipsets
+
+		fullflush
+			Flush IOMMU on each allocation (default).
+
+		nofullflush
+			Don't use IOMMU fullflush.
+
+		memaper[=<order>]
+			Allocate an own aperture over RAM with size
+			32MB<<order.  (default: order=1, i.e. 64MB)
+
+		noaperture
+			Ask the IOMMU not to touch the aperture for AGP.
+
+		noagp
+			Don't initialize the AGP driver and use full aperture.
+
+	iommu=		[PPC/POWERNV]
+
+		nobypass
+			Disable IOMMU bypass, using IOMMU for PCI devices.
+
+	iommu.forcedac=	[ARM64,X86,EARLY] Control IOVA allocation for PCI devices.
+			Format: { "0" | "1" }
+			0 - Try to allocate a 32-bit DMA address first, before
+			  falling back to the full range if needed.
+			1 - Allocate directly from the full usable range,
+			  forcing Dual Address Cycle for PCI cards supporting
+			  greater than 32-bit addressing.
+
+	iommu.strict=	[ARM64,X86,S390,EARLY] Configure TLB invalidation behaviour
+			Format: { "0" | "1" }
+			0 - Lazy mode.
+			  Request that DMA unmap operations use deferred
+			  invalidation of hardware TLBs, for increased
+			  throughput at the cost of reduced device isolation.
+			  Will fall back to strict mode if not supported by
+			  the relevant IOMMU driver.
+			1 - Strict mode.
+			  DMA unmap operations invalidate IOMMU hardware TLBs
+			  synchronously.
+			unset - Use value of CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT}.
+			Note: on x86, strict mode specified via one of the
+			legacy driver-specific options takes precedence.
+
+	iommu.passthrough=
+			[ARM64,X86,EARLY] Configure DMA to bypass the IOMMU by default.
+			Format: { "0" | "1" }
+			0 - Use IOMMU translation for DMA.
+			1 - Bypass the IOMMU for DMA.
+			unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH.
+
+	iommu.debug_pagealloc=
+			[KNL,EARLY] When CONFIG_IOMMU_DEBUG_PAGEALLOC is set, this
+			parameter enables the feature at boot time. By default, it
+			is disabled and the system behaves the same way as a kernel
+			built without CONFIG_IOMMU_DEBUG_PAGEALLOC.
+			Format: { "0" | "1" }
+			0 - Sanitizer disabled.
+			1 - Sanitizer enabled, expect runtime overhead.
+
+	io7=		[HW] IO7 for Marvel-based Alpha systems
+			See comment before marvel_specify_io7 in
+			arch/alpha/kernel/core_marvel.c.
+
+	io_delay=	[X86,EARLY] I/O delay method
+		0x80
+			Standard port 0x80 based delay
+		0xed
+			Alternate port 0xed based delay (needed on some systems)
+		udelay
+			Simple two microseconds delay
+		none
+			No delay
+
+	ip=		[IP_PNP]
+			See Documentation/admin-guide/nfs/nfsroot.rst.
+
+	ipcmni_extend	[KNL,EARLY] Extend the maximum number of unique System V
+			IPC identifiers from 32,768 to 16,777,216.
+
+	ipe.enforce=	[IPE]
+			Format: <bool>
+			Determine whether IPE starts in permissive (0) or
+			enforce (1) mode. The default is enforce.
+
+	ipe.success_audit=
+			[IPE]
+			Format: <bool>
+			Start IPE with success auditing enabled, emitting
+			an audit event when a binary is allowed. The default
+			is 0.
+
+	irqaffinity=	[SMP] Set the default irq affinity mask
+			The argument is a cpu list, as described above.
+
+	irqchip.gicv2_force_probe=
+			[ARM,ARM64,EARLY]
+			Format: <bool>
+			Force the kernel to look for the second 4kB page
+			of a GICv2 controller even if the memory range
+			exposed by the device tree is too small.
+
+	irqchip.gicv3_nolpi=
+			[ARM,ARM64,EARLY]
+			Force the kernel to ignore the availability of
+			LPIs (and by consequence ITSs). Intended for system
+			that use the kernel as a bootloader, and thus want
+			to let secondary kernels in charge of setting up
+			LPIs.
+
+	irqchip.gicv3_pseudo_nmi= [ARM64,EARLY]
+			Enables support for pseudo-NMIs in the kernel. This
+			requires the kernel to be built with
+			CONFIG_ARM64_PSEUDO_NMI.
+
+	irqchip.riscv_imsic_noipi
+			[RISC-V,EARLY]
+			Force the kernel to not use IMSIC software injected MSIs
+			as IPIs. Intended for system where IMSIC is trap-n-emulated,
+			and thus want to reduce MMIO traps when triggering IPIs
+			to multiple harts.
+
+	irqfixup	[HW]
+			When an interrupt is not handled search all handlers
+			for it. Intended to get systems with badly broken
+			firmware running.
+
+	irqhandler.duration_warn_us= [KNL]
+			Warn if an IRQ handler exceeds the specified duration
+			threshold in microseconds. Useful for identifying
+			long-running IRQs in the system.
+
+	irqpoll		[HW]
+			When an interrupt is not handled search all handlers
+			for it. Also check all handlers each timer
+			interrupt. Intended to get systems with badly broken
+			firmware running.
+
+	isapnp=		[ISAPNP]
+			Format: <RDP>,<reset>,<pci_scan>,<verbosity>
+
+	isolcpus=	[KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
+			Format: [flag-list,]<cpu-list>
+
+			Specify one or more CPUs to isolate from disturbances
+			specified in the flag list (default: domain):
+
+			nohz
+			  Disable the tick when a single task runs as well as
+			  disabling other kernel noises like having RCU callbacks
+			  offloaded. This is equivalent to the nohz_full parameter.
+
+			  A residual 1Hz tick is offloaded to workqueues, which you
+			  need to affine to housekeeping through the global
+			  workqueue's affinity configured via the
+			  /sys/devices/virtual/workqueue/cpumask sysfs file, or
+			  by using the 'domain' flag described below.
+
+			  NOTE: by default the global workqueue runs on all CPUs,
+			  so to protect individual CPUs the 'cpumask' file has to
+			  be configured manually after bootup.
+
+			domain
+			  Isolate from the general SMP balancing and scheduling
+			  algorithms. Note that performing domain isolation this way
+			  is irreversible: it's not possible to bring back a CPU to
+			  the domains once isolated through this boot time
+			  configuration. Use cpusets for a dynamic configuration
+			  which can be altered at runtime. For details see
+			  Documentation/admin-guide/cpu-isolation.rst.
+
+			  You can move a process onto or off an "isolated" CPU via
+			  the CPU affinity syscalls or cpuset.
+			  <cpu number> begins at 0 and the maximum value is
+			  "number of CPUs in system - 1".
+
+			managed_irq
+
+			  Isolate from being targeted by managed interrupts
+			  which have an interrupt mask containing isolated
+			  CPUs. The affinity of managed interrupts is
+			  handled by the kernel and cannot be changed via
+			  the /proc/irq/* interfaces.
+
+			  This isolation is best effort and only effective
+			  if the automatically assigned interrupt mask of a
+			  device queue contains isolated and housekeeping
+			  CPUs. If housekeeping CPUs are online then such
+			  interrupts are directed to the housekeeping CPU
+			  so that IO submitted on the housekeeping CPU
+			  cannot disturb the isolated CPU.
+
+			  If a queue's affinity mask contains only isolated
+			  CPUs then this parameter has no effect on the
+			  interrupt routing decision, though interrupts are
+			  only delivered when tasks running on those
+			  isolated CPUs submit IO. IO submitted on
+			  housekeeping CPUs has no influence on those
+			  queues.
+
+			The format of <cpu-list> is described above.
+
+	iucv=		[HW,NET]
+
+	ivrs_ioapic	[HW,X86-64]
+			Provide an override to the IOAPIC-ID<->DEVICE-ID
+			mapping provided in the IVRS ACPI table.
+			By default, PCI segment is 0, and can be omitted.
+
+			For example, to map IOAPIC-ID decimal 10 to
+			PCI segment 0x1 and PCI device 00:14.0,
+			write the parameter as:
+				ivrs_ioapic=10@0001:00:14.0
+
+			Deprecated formats:
+			* To map IOAPIC-ID decimal 10 to PCI device 00:14.0
+			  write the parameter as:
+				ivrs_ioapic[10]=00:14.0
+			* To map IOAPIC-ID decimal 10 to PCI segment 0x1 and
+			  PCI device 00:14.0 write the parameter as:
+				ivrs_ioapic[10]=0001:00:14.0
+
+	ivrs_hpet	[HW,X86-64]
+			Provide an override to the HPET-ID<->DEVICE-ID
+			mapping provided in the IVRS ACPI table.
+			By default, PCI segment is 0, and can be omitted.
+
+			For example, to map HPET-ID decimal 10 to
+			PCI segment 0x1 and PCI device 00:14.0,
+			write the parameter as:
+				ivrs_hpet=10@0001:00:14.0
+
+			Deprecated formats:
+			* To map HPET-ID decimal 0 to PCI device 00:14.0
+			  write the parameter as:
+				ivrs_hpet[0]=00:14.0
+			* To map HPET-ID decimal 10 to PCI segment 0x1 and
+			  PCI device 00:14.0 write the parameter as:
+				ivrs_ioapic[10]=0001:00:14.0
+
+	ivrs_acpihid	[HW,X86-64]
+			Provide an override to the ACPI-HID:UID<->DEVICE-ID
+			mapping provided in the IVRS ACPI table.
+			By default, PCI segment is 0, and can be omitted.
+
+			For example, to map UART-HID:UID AMD0020:0 to
+			PCI segment 0x1 and PCI device ID 00:14.5,
+			write the parameter as:
+				ivrs_acpihid=AMD0020:0@0001:00:14.5
+
+			Deprecated formats:
+			* To map UART-HID:UID AMD0020:0 to PCI segment is 0,
+			  PCI device ID 00:14.5, write the parameter as:
+				ivrs_acpihid[00:14.5]=AMD0020:0
+			* To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and
+			  PCI device ID 00:14.5, write the parameter as:
+				ivrs_acpihid[0001:00:14.5]=AMD0020:0
+
+	js=		[HW,JOY] Analog joystick
+			See Documentation/input/joydev/joystick.rst.
+
+	kasan_multi_shot
+			[KNL] Enforce KASAN (Kernel Address Sanitizer) to print
+			report on every invalid memory access. Without this
+			parameter KASAN will print report only for the first
+			invalid access.
+
+	keep_bootcon	[KNL,EARLY]
+			Do not unregister boot console at start. This is only
+			useful for debugging when something happens in the window
+			between unregistering the boot console and initializing
+			the real console.
+
+	keepinitrd	[HW,ARM] See retain_initrd.
+
+	kernelcore=	[KNL,X86,PPC,EARLY]
+			Format: nn[KMGTPE] | nn% | "mirror"
+			This parameter specifies the amount of memory usable by
+			the kernel for non-movable allocations.  The requested
+			amount is spread evenly throughout all nodes in the
+			system as ZONE_NORMAL.  The remaining memory is used for
+			movable memory in its own zone, ZONE_MOVABLE.  In the
+			event, a node is too small to have both ZONE_NORMAL and
+			ZONE_MOVABLE, kernelcore memory will take priority and
+			other nodes will have a larger ZONE_MOVABLE.
+
+			ZONE_MOVABLE is used for the allocation of pages that
+			may be reclaimed or moved by the page migration
+			subsystem.  Note that allocations like PTEs-from-HighMem
+			still use the HighMem zone if it exists, and the Normal
+			zone if it does not.
+
+			It is possible to specify the exact amount of memory in
+			the form of "nn[KMGTPE]", a percentage of total system
+			memory in the form of "nn%", or "mirror".  If "mirror"
+			option is specified, mirrored (reliable) memory is used
+			for non-movable allocations and remaining memory is used
+			for Movable pages.  "nn[KMGTPE]", "nn%", and "mirror"
+			are exclusive, so you cannot specify multiple forms.
+
+	kfence.burst=	[MM,KFENCE] The number of additional successive
+			allocations to be attempted through KFENCE for each
+			sample interval.
+			Format: <unsigned integer>
+			Default: 0
+
+	kfence.check_on_panic=
+			[MM,KFENCE] Whether to check all KFENCE-managed objects'
+			canaries on panic.
+			Format: <bool>
+			Default: false
+
+	kfence.deferrable=
+			[MM,KFENCE] Whether to use a deferrable timer to trigger
+			allocations. This avoids forcing CPU wake-ups if the
+			system is idle, at the risk of a less predictable
+			sample interval.
+			Format: <bool>
+			Default: CONFIG_KFENCE_DEFERRABLE
+
+	kfence.fault=	[MM,KFENCE] Controls the behavior when a KFENCE
+			error is detected.
+			report - print the error report and continue (default).
+			oops   - print the error report and oops.
+			panic  - print the error report and panic.
+
+	kfence.sample_interval=
+			[MM,KFENCE] KFENCE's sample interval in milliseconds.
+			Format: <unsigned integer>
+			 0 - Disable KFENCE.
+			>0 - Enabled KFENCE with given sample interval.
+			Default: CONFIG_KFENCE_SAMPLE_INTERVAL
+
+	kfence.skip_covered_thresh=
+			[MM,KFENCE] If pool utilization reaches this threshold
+			(pool usage%), KFENCE limits currently covered
+			allocations of the same source from further filling
+			up the pool.
+			Format: <unsigned integer>
+			Default: 75
+
+	kgdbdbgp=	[KGDB,HW,EARLY] kgdb over EHCI usb debug port.
+			Format: <Controller#>[,poll interval]
+			The controller # is the number of the ehci usb debug
+			port as it is probed via PCI.  The poll interval is
+			optional and is the number seconds in between
+			each poll cycle to the debug port in case you need
+			the functionality for interrupting the kernel with
+			gdb or control-c on the dbgp connection.  When
+			not using this parameter you use sysrq-g to break into
+			the kernel debugger.
+
+	kgdboc=		[KGDB,HW] kgdb over consoles.
+			Requires a tty driver that supports console polling,
+			or a supported polling keyboard driver (non-usb).
+			 Serial only format: <serial_device>[,baud]
+			 keyboard only format: kbd
+			 keyboard and serial format: kbd,<serial_device>[,baud]
+			Optional Kernel mode setting:
+			 kms, kbd format: kms,kbd
+			 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
+
+	kgdboc_earlycon=	[KGDB,HW,EARLY]
+			If the boot console provides the ability to read
+			characters and can work in polling mode, you can use
+			this parameter to tell kgdb to use it as a backend
+			until the normal console is registered. Intended to
+			be used together with the kgdboc parameter which
+			specifies the normal console to transition to.
+
+			The name of the early console should be specified
+			as the value of this parameter. Note that the name of
+			the early console might be different than the tty
+			name passed to kgdboc. It's OK to leave the value
+			blank and the first boot console that implements
+			read() will be picked.
+
+	kgdbwait	[KGDB,EARLY] Stop kernel execution and enter the
+			kernel debugger at the earliest opportunity.
+
+	kho=		[KEXEC,EARLY]
+			Format: { "0" | "1" | "off" | "on" | "y" | "n" }
+			Enables or disables Kexec HandOver.
+			"0" | "off" | "n" - kexec handover is disabled
+			"1" | "on" | "y" - kexec handover is enabled
+
+	kho_scratch=	[KEXEC,EARLY]
+			Format: ll[KMG],mm[KMG],nn[KMG] | nn%
+			Defines the size of the KHO scratch region. The KHO
+			scratch regions are physically contiguous memory
+			ranges that can only be used for non-kernel
+			allocations. That way, even when memory is heavily
+			fragmented with handed over memory, the kexeced
+			kernel will always have enough contiguous ranges to
+			bootstrap itself.
+
+			It is possible to specify the exact amount of
+			memory in the form of "ll[KMG],mm[KMG],nn[KMG]"
+			where the first parameter defines the size of a low
+			memory scratch area, the second parameter defines
+			the size of a global scratch area and the third
+			parameter defines the size of additional per-node
+			scratch areas.  The form "nn%" defines scale factor
+			(in percents) of memory that was used during boot.
+
+	kmac=		[MIPS] Korina ethernet MAC address.
+			Configure the RouterBoard 532 series on-chip
+			Ethernet adapter MAC address.
+
+	kmemleak=	[KNL,EARLY] Boot-time kmemleak enable/disable
+			Valid arguments: on, off
+			Default: on
+			Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
+			the default is off.
+
+	kprobe_event=[probe-list]
+			[FTRACE] Add kprobe events and enable at boot time.
+			The probe-list is a semicolon delimited list of probe
+			definitions. Each definition is same as kprobe_events
+			interface, but the parameters are comma delimited.
+			For example, to add a kprobe event on vfs_read with
+			arg1 and arg2, add to the command line;
+
+			      kprobe_event=p,vfs_read,$arg1,$arg2
+
+			See also Documentation/trace/kprobetrace.rst "Kernel
+			Boot Parameter" section.
+
+	kpti=		[ARM64,EARLY] Control page table isolation of
+			user and kernel address spaces.
+			Default: enabled on cores which need mitigation.
+			0: force disabled
+			1: force enabled
+
+	kunit.enable=	[KUNIT] Enable executing KUnit tests. Requires
+			CONFIG_KUNIT to be set to be fully enabled. The
+			default value can be overridden via
+			KUNIT_DEFAULT_ENABLED.
+			Default is 1 (enabled)
+
+	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
+			Default is 0 (don't ignore, but inject #GP)
+
+	kvm.eager_page_split=
+			[KVM,X86,RISCV] Controls whether or not KVM will try to
+			proactively split all huge pages during dirty logging.
+			Eager page splitting reduces interruptions to vCPU
+			execution by eliminating the write-protection faults
+			and MMU lock contention that would otherwise be
+			required to split huge pages lazily.
+
+			VM workloads that rarely perform writes or that write
+			only to a small region of VM memory may benefit from
+			disabling eager page splitting to allow huge pages to
+			still be used for reads.
+
+			The behavior of eager page splitting depends on whether
+			KVM_DIRTY_LOG_INITIALLY_SET is enabled or disabled. If
+			disabled, all huge pages in a memslot will be eagerly
+			split when dirty logging is enabled on that memslot. If
+			enabled, eager page splitting will be performed during
+			the KVM_CLEAR_DIRTY ioctl, and only for the pages being
+			cleared.
+
+			On x86, eager page splitting is only supported when
+			kvm.tdp_mmu=Y.
+
+			On RISCV, eager page splitting is supported by default.
+
+			Default is Y (on).
+
+	kvm.enable_pmu=[KVM,X86]
+			If enabled, KVM will virtualize PMU functionality based
+			on the virtual CPU model defined by userspace.  This
+			can be overridden on a per-VM basis via
+			KVM_CAP_PMU_CAPABILITY.
+
+			If disabled, KVM will not virtualize PMU functionality,
+			e.g. MSRs, PMCs, PMIs, etc., even if userspace defines
+			a virtual CPU model that contains PMU assets.
+
+			Note, KVM's vPMU support implicitly requires running
+			with an in-kernel local APIC, e.g. to deliver PMIs to
+			the guest.  Running without an in-kernel local APIC is
+			not supported, though KVM will allow such a combination
+			(with severely degraded functionality).
+
+			See also enable_mediated_pmu.
+
+			Default is Y (on).
+
+	kvm.enable_virt_at_load=[KVM,ARM64,LOONGARCH,MIPS,RISCV,X86]
+			If enabled, KVM will enable virtualization in hardware
+			when KVM is loaded, and disable virtualization when KVM
+			is unloaded (if KVM is built as a module).
+
+			If disabled, KVM will dynamically enable and disable
+			virtualization on-demand when creating and destroying
+			VMs, i.e. on the 0=>1 and 1=>0 transitions of the
+			number of VMs.
+
+			Enabling virtualization at module load avoids potential
+			latency for creation of the 0=>1 VM, as KVM serializes
+			virtualization enabling across all online CPUs.  The
+			"cost" of enabling virtualization when KVM is loaded,
+			is that doing so may interfere with using out-of-tree
+			hypervisors that want to "own" virtualization hardware.
+
+	kvm.enable_vmware_backdoor=[KVM] Support VMware backdoor PV interface.
+				   Default is false (don't support).
+
+	kvm.nx_huge_pages=
+			[KVM] Controls the software workaround for the
+			X86_BUG_ITLB_MULTIHIT bug.
+			force	: Always deploy workaround.
+			off	: Never deploy workaround.
+			auto    : Deploy workaround based on the presence of
+				  X86_BUG_ITLB_MULTIHIT.
+
+			Default is 'auto'.
+
+			If the software workaround is enabled for the host,
+			guests do need not to enable it for nested guests.
+
+	kvm.nx_huge_pages_recovery_ratio=
+			[KVM] Controls how many 4KiB pages are periodically zapped
+			back to huge pages.  0 disables the recovery, otherwise if
+			the value is N KVM will zap 1/Nth of the 4KiB pages every
+			period (see below).  The default is 60.
+
+	kvm.nx_huge_pages_recovery_period_ms=
+			[KVM] Controls the time period at which KVM zaps 4KiB pages
+			back to huge pages. If the value is a non-zero N, KVM will
+			zap a portion (see ratio above) of the pages every N msecs.
+			If the value is 0 (the default), KVM will pick a period based
+			on the ratio, such that a page is zapped after 1 hour on average.
+
+	kvm-{amd,intel}.enable_mediated_pmu=[KVM,AMD,INTEL]
+			If enabled, KVM will provide a mediated virtual PMU,
+			instead of the default perf-based virtual PMU (if
+			kvm.enable_pmu is true and PMU is enumerated via the
+			virtual CPU model).
+
+			With a perf-based vPMU, KVM operates as a user of perf,
+			i.e. emulates guest PMU counters using perf events.
+			KVM-created perf events are managed by perf as regular
+			(guest-only) events, e.g. are scheduled in/out, contend
+			for hardware resources, etc.  Using a perf-based vPMU
+			allows guest and host usage of the PMU to co-exist, but
+			incurs non-trivial overhead and can result in silently
+			dropped guest events (due to resource contention).
+
+			With a mediated vPMU, hardware PMU state is context
+			switched around the world switch to/from the guest.
+			KVM mediates which events the guest can utilize, but
+			gives the guest direct access to all other PMU assets
+			when possible (KVM may intercept some accesses if the
+			virtual CPU model provides a subset of hardware PMU
+			functionality).  Using a mediated vPMU significantly
+			reduces PMU virtualization overhead and eliminates lost
+			guest events, but is mutually exclusive with using perf
+			to profile KVM guests and adds latency to most VM-Exits
+			(to context switch PMU state).
+
+			Default is N (off).
+
+	kvm-amd.nested=	[KVM,AMD] Control nested virtualization feature in
+			KVM/SVM. Default is 1 (enabled).
+
+	kvm-amd.npt=	[KVM,AMD] Control KVM's use of Nested Page Tables,
+			a.k.a. Two-Dimensional Page Tables. Default is 1
+			(enabled). Disable by KVM if hardware lacks support
+			for NPT.
+
+	kvm-amd.ciphertext_hiding_asids=
+			[KVM,AMD] Ciphertext hiding prevents disallowed accesses
+			to SNP private memory from reading ciphertext.  Instead,
+			reads will see constant default values (0xff).
+
+			If ciphertext hiding is enabled, the joint SEV-ES and
+			SEV-SNP ASID space is partitioned into separate SEV-ES
+			and SEV-SNP ASID ranges, with the SEV-SNP range being
+			[1..max_snp_asid] and the SEV-ES range being
+			(max_snp_asid..min_sev_asid), where min_sev_asid is
+			enumerated by CPUID.0x.8000_001F[EDX].
+
+			A non-zero value enables SEV-SNP ciphertext hiding and
+			adjusts the ASID ranges for SEV-ES and SEV-SNP guests.
+			KVM caps the number of SEV-SNP ASIDs at the maximum
+			possible value, e.g. specifying -1u will assign all
+			joint SEV-ES and SEV-SNP ASIDs to SEV-SNP.  Note,
+			assigning all joint ASIDs to SEV-SNP, i.e. configuring
+			max_snp_asid == min_sev_asid-1, will effectively make
+			SEV-ES unusable.
+
+	kvm-arm.mode=
+			[KVM,ARM,EARLY] Select one of KVM/arm64's modes of
+			operation.
+
+			none: Forcefully disable KVM.
+
+			nvhe: Standard nVHE-based mode, without support for
+			      protected guests.
+
+			protected: Mode with support for guests whose state is
+				   kept private from the host, using VHE or
+				   nVHE depending on HW support.
+
+			nested: VHE-based mode with support for nested
+				virtualization. Requires at least ARMv8.4
+				hardware (with FEAT_NV2).
+
+			Defaults to VHE/nVHE based on hardware support. Setting
+			mode to "protected" will disable kexec and hibernation
+			for the host. To force nVHE on VHE hardware, add
+			"arm64_sw.hvhe=0 id_aa64mmfr1.vh=0" to the
+			command-line.
+			"nested" and "protected" are experimental and should be
+			used with extreme caution.
+
+	kvm-arm.vgic_v3_group0_trap=
+			[KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
+			system registers
+
+	kvm-arm.vgic_v3_group1_trap=
+			[KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
+			system registers
+
+	kvm-arm.vgic_v3_common_trap=
+			[KVM,ARM,EARLY] Trap guest accesses to GICv3 common
+			system registers
+
+	kvm-arm.vgic_v4_enable=
+			[KVM,ARM,EARLY] Allow use of GICv4 for direct
+			injection of LPIs.
+
+	kvm-arm.wfe_trap_policy=
+			[KVM,ARM] Control when to set WFE instruction trap for
+			KVM VMs. Traps are allowed but not guaranteed by the
+			CPU architecture.
+
+			trap: set WFE instruction trap
+
+			notrap: clear WFE instruction trap
+
+	kvm-arm.wfi_trap_policy=
+			[KVM,ARM] Control when to set WFI instruction trap for
+			KVM VMs. Traps are allowed but not guaranteed by the
+			CPU architecture.
+
+			trap: set WFI instruction trap
+
+			notrap: clear WFI instruction trap
+
+	kvm_cma_resv_ratio=n [PPC,EARLY]
+			Reserves given percentage from system memory area for
+			contiguous memory allocation for KVM hash pagetable
+			allocation.
+			By default it reserves 5% of total system memory.
+			Format: <integer>
+			Default: 5
+
+	kvm-intel.ept=	[KVM,Intel] Control KVM's use of Extended Page Tables,
+			a.k.a. Two-Dimensional Page Tables.  Default is 1
+			(enabled). Disable by KVM if hardware lacks support
+			for EPT.
+
+	kvm-intel.emulate_invalid_guest_state=
+			[KVM,Intel] Control whether to emulate invalid guest
+			state. Ignored if kvm-intel.enable_unrestricted_guest=1,
+			as guest state is never invalid for unrestricted
+			guests. This param doesn't apply to nested guests (L2),
+			as KVM never emulates invalid L2 guest state.
+			Default is 1 (enabled).
+
+	kvm-intel.flexpriority=
+			[KVM,Intel] Control KVM's use of FlexPriority feature
+			(TPR shadow). Default is 1 (enabled). Disable by KVM if
+			hardware lacks support for it.
+
+	kvm-intel.nested=
+			[KVM,Intel] Control nested virtualization feature in
+			KVM/VMX. Default is 1 (enabled).
+
+	kvm-intel.unrestricted_guest=
+			[KVM,Intel] Control KVM's use of unrestricted guest
+			feature (virtualized real and unpaged mode). Default
+			is 1 (enabled). Disable by KVM if EPT is disabled or
+			hardware lacks support for it.
+
+	kvm-intel.vmentry_l1d_flush=[KVM,Intel] Mitigation for L1 Terminal Fault
+			CVE-2018-3620.
+
+			Valid arguments: never, cond, always
+
+			always: L1D cache flush on every VMENTER.
+			cond:	Flush L1D on VMENTER only when the code between
+				VMEXIT and VMENTER can leak host memory.
+			never:	Disables the mitigation
+
+			Default is cond (do L1 cache flush in specific instances)
+
+	kvm-intel.vpid=	[KVM,Intel] Control KVM's use of Virtual Processor
+			Identification feature (tagged TLBs). Default is 1
+			(enabled). Disable by KVM if hardware lacks support
+			for it.
+
+	l1d_flush=	[X86,INTEL,EARLY]
+			Control mitigation for L1D based snooping vulnerability.
+
+			Certain CPUs are vulnerable to an exploit against CPU
+			internal buffers which can forward information to a
+			disclosure gadget under certain conditions.
+
+			In vulnerable processors, the speculatively
+			forwarded data can be used in a cache side channel
+			attack, to access data to which the attacker does
+			not have direct access.
+
+			This parameter controls the mitigation. The
+			options are:
+
+			on         - enable the interface for the mitigation
+
+	l1tf=           [X86,EARLY] Control mitigation of the L1TF vulnerability on
+			      affected CPUs
+
+			The kernel PTE inversion protection is unconditionally
+			enabled and cannot be disabled.
+
+			full
+				Provides all available mitigations for the
+				L1TF vulnerability. Disables SMT and
+				enables all mitigations in the
+				hypervisors, i.e. unconditional L1D flush.
+
+				SMT control and L1D flush control via the
+				sysfs interface is still possible after
+				boot.  Hypervisors will issue a warning
+				when the first VM is started in a
+				potentially insecure configuration,
+				i.e. SMT enabled or L1D flush disabled.
+
+			full,force
+				Same as 'full', but disables SMT and L1D
+				flush runtime control. Implies the
+				'nosmt=force' command line option.
+				(i.e. sysfs control of SMT is disabled.)
+
+			flush
+				Leaves SMT enabled and enables the default
+				hypervisor mitigation, i.e. conditional
+				L1D flush.
+
+				SMT control and L1D flush control via the
+				sysfs interface is still possible after
+				boot.  Hypervisors will issue a warning
+				when the first VM is started in a
+				potentially insecure configuration,
+				i.e. SMT enabled or L1D flush disabled.
+
+			flush,nosmt
+
+				Disables SMT and enables the default
+				hypervisor mitigation.
+
+				SMT control and L1D flush control via the
+				sysfs interface is still possible after
+				boot.  Hypervisors will issue a warning
+				when the first VM is started in a
+				potentially insecure configuration,
+				i.e. SMT enabled or L1D flush disabled.
+
+			flush,nowarn
+				Same as 'flush', but hypervisors will not
+				warn when a VM is started in a potentially
+				insecure configuration.
+
+			off
+				Disables hypervisor mitigations and doesn't
+				emit any warnings.
+				It also drops the swap size and available
+				RAM limit restriction on both hypervisor and
+				bare metal.
+
+			Default is 'flush'.
+
+			For details see: Documentation/admin-guide/hw-vuln/l1tf.rst
+
+	l2cr=		[PPC]
+
+	l3cr=		[PPC]
+
+	lapic		[X86-32,APIC,EARLY] Enable the local APIC even if BIOS
+			disabled it.
+
+	lapic=		[X86,APIC] Do not use TSC deadline
+			value for LAPIC timer one-shot implementation. Default
+			back to the programmable timer unit in the LAPIC.
+			Format: notscdeadline
+
+	lapic_timer_c2_ok	[X86,APIC,EARLY] trust the local apic timer
+			in C2 power state.
+
+	libata.dma=	[LIBATA] DMA control
+			libata.dma=0	  Disable all PATA and SATA DMA
+			libata.dma=1	  PATA and SATA Disk DMA only
+			libata.dma=2	  ATAPI (CDROM) DMA only
+			libata.dma=4	  Compact Flash DMA only
+			Combinations also work, so libata.dma=3 enables DMA
+			for disks and CDROMs, but not CFs.
+
+	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
+			libata.ignore_hpa=0	  keep BIOS limits (default)
+			libata.ignore_hpa=1	  ignore limits, using full disk
+
+	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
+			when set.
+			Format: <int>
+
+	libata.force=	[LIBATA] Force configurations.  The format is a comma-
+			separated list of "[ID:]VAL" where ID is PORT[.DEVICE].
+			PORT and DEVICE are decimal numbers matching port, link
+			or device.  Basically, it matches the ATA ID string
+			printed on console by libata.  If the whole ID part is
+			omitted, the last PORT and DEVICE values are used.  If
+			ID hasn't been specified yet, the configuration applies
+			to all ports, links and devices.
+
+			If only DEVICE is omitted, the parameter applies to
+			the port and all links and devices behind it.  DEVICE
+			number of 0 either selects the first device or the
+			first fan-out link behind PMP device.  It does not
+			select the host link.  DEVICE number of 15 selects the
+			host link and device attached to it.
+
+			The VAL specifies the configuration to force.  As long
+			as there is no ambiguity, shortcut notation is allowed.
+			For example, both 1.5 and 1.5G would work for 1.5Gbps.
+			The following configurations can be forced.
+
+			* Cable type: 40c, 80c, short40c, unk, ign or sata.
+			  Any ID with matching PORT is used.
+
+			* SATA link speed limit: 1.5Gbps or 3.0Gbps.
+
+			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
+			  udma[/][16,25,33,44,66,100,133] notation is also
+			  allowed.
+
+			* nohrst, nosrst, norst: suppress hard, soft and both
+			  resets.
+
+			* rstonce: only attempt one reset during hot-unplug
+			  link recovery.
+
+			* [no]dbdelay: Enable or disable the extra 200ms delay
+			  before debouncing a link PHY and device presence
+			  detection.
+
+			* [no]ncq: Turn on or off NCQ.
+
+			* [no]ncqtrim: Enable or disable queued DSM TRIM.
+
+			* [no]ncqati: Enable or disable NCQ trim on ATI chipset.
+
+			* [no]trim: Enable or disable (unqueued) TRIM.
+
+			* trim_zero: Indicate that TRIM command zeroes data.
+
+			* max_trim_128m: Set 128M maximum trim size limit.
+
+			* [no]dma: Turn on or off DMA transfers.
+
+			* atapi_dmadir: Enable ATAPI DMADIR bridge support.
+
+			* atapi_mod16_dma: Enable the use of ATAPI DMA for
+			  commands that are not a multiple of 16 bytes.
+
+			* [no]dmalog: Enable or disable the use of the
+			  READ LOG DMA EXT command to access logs.
+
+			* [no]iddevlog: Enable or disable access to the
+			  identify device data log.
+
+			* [no]logdir: Enable or disable access to the general
+			  purpose log directory.
+
+			* max_sec=<sectors>: Set the transfer size limit, in
+			  number of 512-byte sectors, to the value specified in
+			  <sectors>. The value specified in <sectors> has to be
+			  a non-zero positive integer.
+
+			* max_sec_128: Set transfer size limit to 128 sectors.
+
+			* max_sec_1024: Set or clear transfer size limit to
+			  1024 sectors.
+
+			* max_sec_lba48: Set or clear transfer size limit to
+			  65535 sectors.
+
+			* external: Mark port as external (hotplug-capable).
+
+			* [no]lpm: Enable or disable link power management.
+
+			* [no]setxfer: Indicate if transfer speed mode setting
+			  should be skipped.
+
+			* [no]fua: Disable or enable FUA (Force Unit Access)
+			  support for devices supporting this feature.
+
+			* dump_id: Dump IDENTIFY data.
+
+			* disable: Disable this device.
+
+			If there are multiple matching configurations changing
+			the same attribute, the last one is used.
+
+	liveupdate=	[KNL,EARLY]
+			Format: <bool>
+			Enable Live Update Orchestrator (LUO).
+			Default: off.
+
+	lockd.nlm_grace_period=P  [NFS] Assign grace period.
+			Format: <integer>
+
+	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
+			Format: <integer>
+
+	lockd.nlm_timeout=T	[NFS] Assign timeout value.
+			Format: <integer>
+
+	lockd.nlm_udpport=M	[NFS] Assign UDP port.
+			Format: <integer>
+
+	lockdown=	[SECURITY,EARLY]
+			{ integrity | confidentiality }
+			Enable the kernel lockdown feature. If set to
+			integrity, kernel features that allow userland to
+			modify the running kernel are disabled. If set to
+			confidentiality, kernel features that allow userland
+			to extract confidential information from the kernel
+			are also disabled.
+
+	locktorture.acq_writer_lim= [KNL]
+			Set the time limit in jiffies for a lock
+			acquisition.  Acquisitions exceeding this limit
+			will result in a splat once they do complete.
+
+	locktorture.bind_readers= [KNL]
+			Specify the list of CPUs to which the readers are
+			to be bound.
+
+	locktorture.bind_writers= [KNL]
+			Specify the list of CPUs to which the writers are
+			to be bound.
+
+	locktorture.call_rcu_chains= [KNL]
+			Specify the number of self-propagating call_rcu()
+			chains to set up.  These are used to ensure that
+			there is a high probability of an RCU grace period
+			in progress at any given time.	Defaults to 0,
+			which disables these call_rcu() chains.
+
+	locktorture.long_hold= [KNL]
+			Specify the duration in milliseconds for the
+			occasional long-duration lock hold time.  Defaults
+			to 100 milliseconds.  Select 0 to disable.
+
+	locktorture.nested_locks= [KNL]
+			Specify the maximum lock nesting depth that
+			locktorture is to exercise, up to a limit of 8
+			(MAX_NESTED_LOCKS).  Specify zero to disable.
+			Note that this parameter is ineffective on types
+			of locks that do not support nested acquisition.
+
+	locktorture.nreaders_stress= [KNL]
+			Set the number of locking read-acquisition kthreads.
+			Defaults to being automatically set based on the
+			number of online CPUs.
+
+	locktorture.nwriters_stress= [KNL]
+			Set the number of locking write-acquisition kthreads.
+
+	locktorture.onoff_holdoff= [KNL]
+			Set time (s) after boot for CPU-hotplug testing.
+
+	locktorture.onoff_interval= [KNL]
+			Set time (s) between CPU-hotplug operations, or
+			zero to disable CPU-hotplug testing.
+
+	locktorture.rt_boost= [KNL]
+			Do periodic testing of real-time lock priority
+			boosting.  Select 0 to disable, 1 to boost
+			only rt_mutex, and 2 to boost unconditionally.
+			Defaults to 2, which might seem to be an
+			odd choice, but which should be harmless for
+			non-real-time spinlocks, due to their disabling
+			of preemption.	Note that non-realtime mutexes
+			disable boosting.
+
+	locktorture.rt_boost_factor= [KNL]
+			Number that determines how often and for how
+			long priority boosting is exercised.  This is
+			scaled down by the number of writers, so that the
+			number of boosts per unit time remains roughly
+			constant as the number of writers increases.
+			On the other hand, the duration of each boost
+			increases with the number of writers.
+
+	locktorture.shuffle_interval= [KNL]
+			Set task-shuffle interval (jiffies).  Shuffling
+			tasks allows some CPUs to go into dyntick-idle
+			mode during the locktorture test.
+
+	locktorture.shutdown_secs= [KNL]
+			Set time (s) after boot system shutdown.  This
+			is useful for hands-off automated testing.
+
+	locktorture.stat_interval= [KNL]
+			Time (s) between statistics printk()s.
+
+	locktorture.stutter= [KNL]
+			Time (s) to stutter testing, for example,
+			specifying five seconds causes the test to run for
+			five seconds, wait for five seconds, and so on.
+			This tests the locking primitive's ability to
+			transition abruptly to and from idle.
+
+	locktorture.torture_type= [KNL]
+			Specify the locking implementation to test.
+
+	locktorture.verbose= [KNL]
+			Enable additional printk() statements.
+
+	locktorture.writer_fifo= [KNL]
+			Run the write-side locktorture kthreads at
+			sched_set_fifo() real-time priority.
+
+	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
+			Format: <irq>
+
+	loglevel=	[KNL,EARLY]
+			All Kernel Messages with a loglevel smaller than the
+			console loglevel will be printed to the console. It can
+			also be changed with klogd or other programs. The
+			loglevels are defined as follows:
+
+			0 (KERN_EMERG)		system is unusable
+			1 (KERN_ALERT)		action must be taken immediately
+			2 (KERN_CRIT)		critical conditions
+			3 (KERN_ERR)		error conditions
+			4 (KERN_WARNING)	warning conditions
+			5 (KERN_NOTICE)		normal but significant condition
+			6 (KERN_INFO)		informational
+			7 (KERN_DEBUG)		debug-level messages
+
+	log_buf_len=n[KMG] [KNL,EARLY]
+			Sets the size of the printk ring buffer, in bytes.
+			n must be a power of two and greater than the
+			minimal size. The minimal size is defined by
+			LOG_BUF_SHIFT kernel config parameter. There
+			is also CONFIG_LOG_CPU_MAX_BUF_SHIFT config
+			parameter that allows to increase the default size
+			depending on the number of CPUs. See init/Kconfig
+			for more details.
+
+	logo.nologo	[FB] Disables display of the built-in Linux logo.
+			This may be used to provide more screen space for
+			kernel log messages and is useful when debugging
+			kernel boot problems.
+
+	lp=0		[LP]	Specify parallel ports to use, e.g,
+	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
+	lp=reset		first parallel port). 'lp=0' disables the
+	lp=auto			printer driver. 'lp=reset' (which can be
+				specified in addition to the ports) causes
+				attached printers to be reset. Using
+				lp=port1,port2,... specifies the parallel ports
+				to associate lp devices with, starting with
+				lp0. A port specification may be 'none' to skip
+				that lp device, or a parport name such as
+				'parport0'. Specifying 'lp=auto' instead of a
+				port specification list means that device IDs
+				from each port should be examined, to see if
+				an IEEE 1284-compliant printer is attached; if
+				so, the driver will manage that printer.
+				See also header of drivers/char/lp.c.
+
+	lpj=n		[KNL]
+			Sets loops_per_jiffy to given constant, thus avoiding
+			time-consuming boot-time autodetection (up to 250 ms per
+			CPU). 0 enables autodetection (default). To determine
+			the correct value for your kernel, boot with normal
+			autodetection and see what value is printed. Note that
+			on SMP systems the preset will be applied to all CPUs,
+			which is likely to cause problems if your CPUs need
+			significantly divergent settings. An incorrect value
+			will cause delays in the kernel to be wrong, leading to
+			unpredictable I/O errors and other breakage. Although
+			unlikely, in the extreme case this might damage your
+			hardware.
+
+	lsm.debug	[SECURITY] Enable LSM initialization debugging output.
+
+	lsm=lsm1,...,lsmN
+			[SECURITY] Choose order of LSM initialization. This
+			overrides CONFIG_LSM, and the "security=" parameter.
+
+	machtype=	[Loongson] Share the same kernel image file between
+			different yeeloong laptops.
+			Example: machtype=lemote-yeeloong-2f-7inch
+
+	maxcpus=	[SMP,EARLY] Maximum number of processors that an SMP kernel
+			will bring up during bootup.  maxcpus=n : n >= 0 limits
+			the kernel to bring up 'n' processors. Surely after
+			bootup you can bring up the other plugged cpu by executing
+			"echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
+			only takes effect during system bootup.
+			While n=0 is a special case, it is equivalent to "nosmp",
+			which also disables the IO APIC.
+
+	max_loop=	[LOOP] The number of loop block devices that get
+	(loop.max_loop)	unconditionally pre-created at init time. The default
+			number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
+			of statically allocating a predefined number, loop
+			devices can be requested on-demand with the
+			/dev/loop-control interface.
+
+	mce=		[X86-{32,64}]
+
+			Please see Documentation/arch/x86/x86_64/machinecheck.rst for sysfs runtime tunables.
+
+		off
+			disable machine check
+
+		no_cmci
+			disable CMCI(Corrected Machine Check Interrupt) that
+			Intel processor supports.  Usually this disablement is
+			not recommended, but it might be handy if your
+			hardware is misbehaving.
+
+			Note that you'll get more problems without CMCI than
+			with due to the shared banks, i.e. you might get
+			duplicated error logs.
+
+		dont_log_ce
+			don't make logs for corrected errors.  All events
+			reported as corrected are silently cleared by OS. This
+			option will be useful if you have no interest in any
+			of corrected errors.
+
+		ignore_ce
+			disable features for corrected errors, e.g.
+			polling timer and CMCI.  All events reported as
+			corrected are not cleared by OS and remained in its
+			error banks.
+
+			Usually this disablement is not recommended, however
+			if there is an agent checking/clearing corrected
+			errors (e.g. BIOS or hardware monitoring
+			applications), conflicting with OS's error handling,
+			and you cannot deactivate the agent, then this option
+			will be a help.
+
+		no_lmce
+			do not opt-in to Local MCE delivery. Use legacy method
+			to broadcast MCEs.
+
+		bootlog
+			enable logging of machine checks left over from
+			booting. Disabled by default on AMD Fam10h and older
+			because some BIOS leave bogus ones.
+
+			If your BIOS doesn't do that it's a good idea to
+			enable though to make sure you log even machine check
+			events that result in a reboot. On Intel systems it is
+			enabled by default.
+
+		nobootlog
+			disable boot machine check logging.
+
+		print_all
+			print all machine check logs to the console.
+
+		monarchtimeout (number)
+			sets the time in us to wait for other CPUs on machine
+			checks. 0 to disable.
+
+		bios_cmci_threshold
+			don't overwrite the bios-set CMCI threshold. This boot
+			option prevents Linux from overwriting the CMCI
+			threshold set by the bios.  Without this option, Linux
+			always sets the CMCI threshold to 1. Enabling this may
+			make memory predictive failure analysis less effective
+			if the bios sets thresholds for memory errors since we
+			will not see details for all errors.
+
+		recovery
+			force-enable recoverable machine check code paths
+
+			Everything else is in sysfs now.
+
+
+	md=		[HW] RAID subsystems devices and level
+			See Documentation/admin-guide/md.rst.
+
+	mds=		[X86,INTEL,EARLY]
+			Control mitigation for the Micro-architectural Data
+			Sampling (MDS) vulnerability.
+
+			Certain CPUs are vulnerable to an exploit against CPU
+			internal buffers which can forward information to a
+			disclosure gadget under certain conditions.
+
+			In vulnerable processors, the speculatively
+			forwarded data can be used in a cache side channel
+			attack, to access data to which the attacker does
+			not have direct access.
+
+			This parameter controls the MDS mitigation. The
+			options are:
+
+			full       - Enable MDS mitigation on vulnerable CPUs
+			full,nosmt - Enable MDS mitigation and disable
+				     SMT on vulnerable CPUs
+			off        - Unconditionally disable MDS mitigation
+
+			On TAA-affected machines, mds=off can be prevented by
+			an active TAA mitigation as both vulnerabilities are
+			mitigated with the same mechanism so in order to disable
+			this mitigation, you need to specify tsx_async_abort=off
+			too.
+
+			Not specifying this option is equivalent to
+			mds=full.
+
+			For details see: Documentation/admin-guide/hw-vuln/mds.rst
+
+	mem=nn[KMG]	[HEXAGON,EARLY] Set the memory size.
+			Must be specified, otherwise memory size will be 0.
+
+	mem=nn[KMG]	[KNL,BOOT,EARLY] Force usage of a specific amount
+			of memory Amount of memory to be used in cases
+			as follows:
+
+			1 for test;
+			2 when the kernel is not able to see the whole system memory;
+			3 memory that lies after 'mem=' boundary is excluded from
+			 the hypervisor, then assigned to KVM guests.
+			4 to limit the memory available for kdump kernel.
+
+			[ARC,MICROBLAZE] - the limit applies only to low memory,
+			high memory is not affected.
+
+			[ARM64] - only limits memory covered by the linear
+			mapping. The NOMAP regions are not affected.
+
+			[X86] Work as limiting max address. Use together
+			with memmap= to avoid physical address space collisions.
+			Without memmap= PCI devices could be placed at addresses
+			belonging to unused RAM.
+
+			Note that this only takes effects during boot time since
+			in above case 3, memory may need be hot added after boot
+			if system memory of hypervisor is not sufficient.
+
+	mem=nn[KMG]@ss[KMG]
+			[ARM,MIPS,EARLY] - override the memory layout
+			reported by firmware.
+			Define a memory region of size nn[KMG] starting at
+			ss[KMG].
+			Multiple different regions can be specified with
+			multiple mem= parameters on the command line.
+
+	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
+			memory.
+
+	memblock=debug	[KNL,EARLY] Enable memblock debug messages.
+
+	memchunk=nn[KMG]
+			[KNL,SH] Allow user to override the default size for
+			per-device physically contiguous DMA buffers.
+
+	memhp_default_state=online/offline/online_kernel/online_movable
+			[KNL] Set the initial state for the memory hotplug
+			onlining policy. If not specified, the default value is
+			set according to the
+			CONFIG_MHP_DEFAULT_ONLINE_TYPE kernel config
+			options.
+			See Documentation/admin-guide/mm/memory-hotplug.rst.
+
+	memmap=exactmap	[KNL,X86,EARLY] Enable setting of an exact
+			E820 memory map, as specified by the user.
+			Such memmap=exactmap lines can be constructed based on
+			BIOS output or other requirements. See the memmap=nn@ss
+			option description.
+
+	memmap=nn[KMG]@ss[KMG]
+			[KNL, X86,MIPS,XTENSA,EARLY] Force usage of a specific region of memory.
+			Region of memory to be used is from ss to ss+nn.
+			If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
+			which limits max address to nn[KMG].
+			Multiple different regions can be specified,
+			comma delimited.
+			Example:
+				memmap=100M@2G,100M#3G,1G!1024G
+
+	memmap=nn[KMG]#ss[KMG]
+			[KNL,ACPI,EARLY] Mark specific memory as ACPI data.
+			Region of memory to be marked is from ss to ss+nn.
+
+	memmap=nn[KMG]$ss[KMG]
+			[KNL,ACPI,EARLY] Mark specific memory as reserved.
+			Region of memory to be reserved is from ss to ss+nn.
+			Example: Exclude memory from 0x18690000-0x1869ffff
+			         memmap=64K$0x18690000
+			         or
+			         memmap=0x10000$0x18690000
+			Some bootloaders may need an escape character before '$',
+			like Grub2, otherwise '$' and the following number
+			will be eaten.
+
+	memmap=nn[KMG]!ss[KMG,EARLY]
+			[KNL,X86] Mark specific memory as protected.
+			Region of memory to be used, from ss to ss+nn.
+			The memory region may be marked as e820 type 12 (0xc)
+			and is NVDIMM or ADR memory.
+
+	memmap=<size>%<offset>-<oldtype>+<newtype>
+			[KNL,ACPI,EARLY] Convert memory within the specified region
+			from <oldtype> to <newtype>. If "-<oldtype>" is left
+			out, the whole region will be marked as <newtype>,
+			even if previously unavailable. If "+<newtype>" is left
+			out, matching memory will be removed. Types are
+			specified as e820 types, e.g., 1 = RAM, 2 = reserved,
+			3 = ACPI, 12 = PRAM.
+
+	memory_corruption_check=0/1 [X86,EARLY]
+			Some BIOSes seem to corrupt the first 64k of
+			memory when doing things like suspend/resume.
+			Setting this option will scan the memory
+			looking for corruption.  Enabling this will
+			both detect corruption and prevent the kernel
+			from using the memory being corrupted.
+			However, it's intended as a diagnostic tool; if
+			repeatable BIOS-originated corruption always
+			affects the same memory, you can use memmap=
+			to prevent the kernel from using that memory.
+
+	memory_corruption_check_size=size [X86,EARLY]
+			By default it checks for corruption in the low
+			64k, making this memory unavailable for normal
+			use.  Use this parameter to scan for
+			corruption in more or less memory.
+
+	memory_corruption_check_period=seconds [X86,EARLY]
+			By default it checks for corruption every 60
+			seconds.  Use this parameter to check at some
+			other rate.  0 disables periodic checking.
+
+	memory_hotplug.memmap_on_memory
+			[KNL,X86,ARM] Boolean flag to enable this feature.
+			Format: {on | off (default)}
+			When enabled, runtime hotplugged memory will
+			allocate its internal metadata (struct pages,
+			those vmemmap pages cannot be optimized even
+			if hugetlb_free_vmemmap is enabled) from the
+			hotadded memory which will allow to hotadd a
+			lot of memory without requiring additional
+			memory to do so.
+			This feature is disabled by default because it
+			has some implication on large (e.g. GB)
+			allocations in some configurations (e.g. small
+			memory blocks).
+			The state of the flag can be read in
+			/sys/module/memory_hotplug/parameters/memmap_on_memory.
+			Note that even when enabled, there are a few cases where
+			the feature is not effective.
+
+	mempool_debug	[MM]
+			Enable mempool debugging. This enables element
+			poison checking when freeing elements back to the
+			pool. Useful for debugging mempool corruption.
+
+	memtest=	[KNL,X86,ARM,M68K,PPC,RISCV,EARLY] Enable memtest
+			Format: <integer>
+			default : 0 <disable>
+			Specifies the number of memtest passes to be
+			performed. Each pass selects another test
+			pattern from a given set of patterns. Memtest
+			fills the memory with this pattern, validates
+			memory contents and reserves bad memory
+			regions that are detected.
+
+	mem_encrypt=	[X86-64] AMD Secure Memory Encryption (SME) control
+			Valid arguments: on, off
+			Default: off
+			mem_encrypt=on:		Activate SME
+			mem_encrypt=off:	Do not activate SME
+
+			Refer to Documentation/virt/kvm/x86/amd-memory-encryption.rst
+			for details on when memory encryption can be activated.
+
+	mem_sleep_default=	[SUSPEND] Default system suspend mode:
+			s2idle  - Suspend-To-Idle
+			shallow - Power-On Suspend or equivalent (if supported)
+			deep    - Suspend-To-RAM or equivalent (if supported)
+			See Documentation/admin-guide/pm/sleep-states.rst.
+
+	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
+			the BIOS has incorrectly applied a workaround. TinyBIOS
+			version 0.98 is known to be affected, 0.99 fixes the
+			problem by letting the user disable the workaround.
+
+	mga=		[HW,DRM]
+
+	microcode=      [X86] Control the behavior of the microcode loader.
+	                Available options, comma separated:
+
+			base_rev=X - with <X> with format: <u32>
+			Set the base microcode revision of each thread when in
+			debug mode.
+
+			dis_ucode_ldr: disable the microcode loader
+
+			force_minrev:
+			Enable or disable the microcode minimal revision
+			enforcement for the runtime microcode loader.
+
+	mini2440=	[ARM,HW,KNL]
+			Format:[0..2][b][c][t]
+			Default: "0tb"
+			MINI2440 configuration specification:
+			0 - The attached screen is the 3.5" TFT
+			1 - The attached screen is the 7" TFT
+			2 - The VGA Shield is attached (1024x768)
+			Leaving out the screen size parameter will not load
+			the TFT driver, and the framebuffer will be left
+			unconfigured.
+			b - Enable backlight. The TFT backlight pin will be
+			linked to the kernel VESA blanking code and a GPIO
+			LED. This parameter is not necessary when using the
+			VGA shield.
+			c - Enable the s3c camera interface.
+			t - Reserved for enabling touchscreen support. The
+			touchscreen support is not enabled in the mainstream
+			kernel as of 2.6.30, a preliminary port can be found
+			in the "bleeding edge" mini2440 support kernel at
+			https://repo.or.cz/w/linux-2.6/mini2440.git
+
+	mitigations=
+			[X86,PPC,S390,ARM64,EARLY] Control optional mitigations for
+			CPU vulnerabilities.  This is a set of curated,
+			arch-independent options, each of which is an
+			aggregation of existing arch-specific options.
+
+			Note, "mitigations" is supported if and only if the
+			kernel was built with CPU_MITIGATIONS=y.
+
+			off
+				Disable all optional CPU mitigations.  This
+				improves system performance, but it may also
+				expose users to several CPU vulnerabilities.
+				Equivalent to: if nokaslr then kpti=0 [ARM64]
+					       gather_data_sampling=off [X86]
+					       indirect_target_selection=off [X86]
+					       kvm.nx_huge_pages=off [X86]
+					       l1tf=off [X86]
+					       mds=off [X86]
+					       mmio_stale_data=off [X86]
+					       no_entry_flush [PPC]
+					       no_uaccess_flush [PPC]
+					       nobp=0 [S390]
+					       nopti [X86,PPC]
+					       nospectre_bhb [ARM64]
+					       nospectre_v1 [X86,PPC]
+					       nospectre_v2 [X86,PPC,S390,ARM64]
+					       reg_file_data_sampling=off [X86]
+					       retbleed=off [X86]
+					       spec_rstack_overflow=off [X86]
+					       spec_store_bypass_disable=off [X86,PPC]
+					       spectre_bhi=off [X86]
+					       spectre_v2_user=off [X86]
+					       srbds=off [X86,INTEL]
+					       ssbd=force-off [ARM64]
+					       tsa=off [X86,AMD]
+					       tsx_async_abort=off [X86]
+					       vmscape=off [X86]
+
+				Exceptions:
+					       This does not have any effect on
+					       kvm.nx_huge_pages when
+					       kvm.nx_huge_pages=force.
+
+			auto (default)
+				Mitigate all CPU vulnerabilities, but leave SMT
+				enabled, even if it's vulnerable.  This is for
+				users who don't want to be surprised by SMT
+				getting disabled across kernel upgrades, or who
+				have other ways of avoiding SMT-based attacks.
+				Equivalent to: (default behavior)
+
+			auto,nosmt
+				Mitigate all CPU vulnerabilities, disabling SMT
+				if needed.  This is for users who always want to
+				be fully mitigated, even if it means losing SMT.
+				Equivalent to: l1tf=flush,nosmt [X86]
+					       mds=full,nosmt [X86]
+					       tsx_async_abort=full,nosmt [X86]
+					       mmio_stale_data=full,nosmt [X86]
+					       retbleed=auto,nosmt [X86]
+
+			[X86] After one of the above options, additionally
+			supports attack-vector based controls as documented in
+			Documentation/admin-guide/hw-vuln/attack_vector_controls.rst
+
+	mminit_loglevel=
+			[KNL,EARLY] When CONFIG_DEBUG_MEMORY_INIT is set, this
+			parameter allows control of the logging verbosity for
+			the additional memory initialisation checks. A value
+			of 0 disables mminit logging and a level of 4 will
+			log everything. Information is printed at KERN_DEBUG
+			so loglevel=8 may also need to be specified.
+
+	mmio_stale_data=
+			[X86,INTEL,EARLY] Control mitigation for the Processor
+			MMIO Stale Data vulnerabilities.
+
+			Processor MMIO Stale Data is a class of
+			vulnerabilities that may expose data after an MMIO
+			operation. Exposed data could originate or end in
+			the same CPU buffers as affected by MDS and TAA.
+			Therefore, similar to MDS and TAA, the mitigation
+			is to clear the affected CPU buffers.
+
+			This parameter controls the mitigation. The
+			options are:
+
+			full       - Enable mitigation on vulnerable CPUs
+
+			full,nosmt - Enable mitigation and disable SMT on
+				     vulnerable CPUs.
+
+			off        - Unconditionally disable mitigation
+
+			On MDS or TAA affected machines,
+			mmio_stale_data=off can be prevented by an active
+			MDS or TAA mitigation as these vulnerabilities are
+			mitigated with the same mechanism so in order to
+			disable this mitigation, you need to specify
+			mds=off and tsx_async_abort=off too.
+
+			Not specifying this option is equivalent to
+			mmio_stale_data=full.
+
+			For details see:
+			Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst
+
+	<module>.async_probe[=<bool>] [KNL]
+			If no <bool> value is specified or if the value
+			specified is not a valid <bool>, enable asynchronous
+			probe on this module.  Otherwise, enable/disable
+			asynchronous probe on this module as indicated by the
+			<bool> value. See also: module.async_probe
+
+	module.async_probe=<bool>
+			[KNL] When set to true, modules will use async probing
+			by default. To enable/disable async probing for a
+			specific module, use the module specific control that
+			is documented under <module>.async_probe. When both
+			module.async_probe and <module>.async_probe are
+			specified, <module>.async_probe takes precedence for
+			the specific module.
+
+	module.enable_dups_trace
+			[KNL] When CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS is set,
+			this means that duplicate request_module() calls will
+			trigger a WARN_ON() instead of a pr_warn(). Note that
+			if MODULE_DEBUG_AUTOLOAD_DUPS_TRACE is set, WARN_ON()s
+			will always be issued and this option does nothing.
+	module.sig_enforce
+			[KNL] When CONFIG_MODULE_SIG is set, this means that
+			modules without (valid) signatures will fail to load.
+			Note that if CONFIG_MODULE_SIG_FORCE is set, that
+			is always true, so this option does nothing.
+
+	module_blacklist=  [KNL] Do not load a comma-separated list of
+			modules.  Useful for debugging problem modules.
+
+	mousedev.tap_time=
+			[MOUSE] Maximum time between finger touching and
+			leaving touchpad surface for touch to be considered
+			a tap and be reported as a left button click (for
+			touchpads working in absolute mode only).
+			Format: <msecs>
+	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
+			reporting absolute coordinates, such as tablets
+	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
+			reporting absolute coordinates, such as tablets
+
+	movablecore=	[KNL,X86,PPC,EARLY]
+			Format: nn[KMGTPE] | nn%
+			This parameter is the complement to kernelcore=, it
+			specifies the amount of memory used for migratable
+			allocations.  If both kernelcore and movablecore is
+			specified, then kernelcore will be at *least* the
+			specified value but may be more.  If movablecore on its
+			own is specified, the administrator must be careful
+			that the amount of memory usable for all allocations
+			is not too small.
+
+	movable_node	[KNL,EARLY] Boot-time switch to make hotplugable memory
+			NUMA nodes to be movable. This means that the memory
+			of such nodes will be usable only for movable
+			allocations which rules out almost all kernel
+			allocations. Use with caution!
+
+	MTD_Partition=	[MTD]
+			Format: <name>,<region-number>,<size>,<offset>
+
+	MTD_Region=	[MTD] Format:
+			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
+
+	mtdparts=	[MTD]
+			See drivers/mtd/parsers/cmdlinepart.c
+
+	mtouchusb.raw_coordinates=
+			[HW] Make the MicroTouch USB driver use raw coordinates
+			('y', default) or cooked coordinates ('n')
+
+	mtrr=debug	[X86,EARLY]
+			Enable printing debug information related to MTRR
+			registers at boot time.
+
+	mtrr_chunk_size=nn[KMG,X86,EARLY]
+			used for mtrr cleanup. It is largest continuous chunk
+			that could hold holes aka. UC entries.
+
+	mtrr_gran_size=nn[KMG,X86,EARLY]
+			Used for mtrr cleanup. It is granularity of mtrr block.
+			Default is 1.
+			Large value could prevent small alignment from
+			using up MTRRs.
+
+	mtrr_spare_reg_nr=n [X86,EARLY]
+			Format: <integer>
+			Range: 0,7 : spare reg number
+			Default : 1
+			Used for mtrr cleanup. It is spare mtrr entries number.
+			Set to 2 or more if your graphical card needs more.
+
+	multitce=off	[PPC]  This parameter disables the use of the pSeries
+			firmware feature for updating multiple TCE entries
+			at a time.
+
+	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card
+
+	netdev=		[NET] NE2000 ISA network devices parameters
+			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
+
+	netpoll.carrier_timeout=
+			[NET] Specifies amount of time (in seconds) that
+			netpoll should wait for a carrier. By default netpoll
+			waits 4 seconds.
+
+	nf_conntrack.acct=
+			[NETFILTER] Enable connection tracking flow accounting
+			0 to disable accounting
+			1 to enable accounting
+			Default value is 0.
+
+	nfs.cache_getent=
+			[NFS] sets the pathname to the program which is used
+			to update the NFS client cache entries.
+
+	nfs.cache_getent_timeout=
+			[NFS] sets the timeout after which an attempt to
+			update a cache entry is deemed to have failed.
+
+	nfs.callback_nr_threads=
+			[NFSv4] set the total number of threads that the
+			NFS client will assign to service NFSv4 callback
+			requests.
+
+	nfs.callback_tcpport=
+			[NFS] set the TCP port on which the NFSv4 callback
+			channel should listen.
+
+	nfs.delay_retrans=
+			[NFS] specifies the number of times the NFSv4 client
+			retries the request before returning an EAGAIN error,
+			after a reply of NFS4ERR_DELAY from the server.
+			Only applies if the softerr mount option is enabled,
+			and the specified value is >= 0.
+
+	nfs.idmap_cache_timeout=
+			[NFS] set the maximum lifetime for idmapper cache
+			entries.
+
+	nfs.max_session_cb_slots=
+			[NFSv4.1] Sets the maximum number of session
+			slots the client will assign to the callback
+			channel. This determines the maximum number of
+			callbacks the client will process in parallel for
+			a particular server.
+
+	nfs.max_session_slots=
+			[NFSv4.1] Sets the maximum number of session slots
+			the client will attempt to negotiate with the server.
+			This limits the number of simultaneous RPC requests
+			that the client can send to the NFSv4.1 server.
+			Note that there is little point in setting this
+			value higher than the max_tcp_slot_table_limit.
+
+	nfs.nfs4_disable_idmapping=
+			[NFSv4] When set to the default of '1', this option
+			ensures that both the RPC level authentication
+			scheme and the NFS level operations agree to use
+			numeric uids/gids if the mount is using the
+			'sec=sys' security flavour. In effect it is
+			disabling idmapping, which can make migration from
+			legacy NFSv2/v3 systems to NFSv4 easier.
+			Servers that do not support this mode of operation
+			will be autodetected by the client, and it will fall
+			back to using the idmapper.
+			To turn off this behaviour, set the value to '0'.
+
+	nfs.nfs4_unique_id=
+			[NFS4] Specify an additional fixed unique ident-
+			ification string that NFSv4 clients can insert into
+			their nfs_client_id4 string.  This is typically a
+			UUID that is generated at system install time.
+
+	nfs.recover_lost_locks=
+			[NFSv4] Attempt to recover locks that were lost due
+			to a lease timeout on the server. Please note that
+			doing this risks data corruption, since there are
+			no guarantees that the file will remain unchanged
+			after the locks are lost.
+			If you want to enable the kernel legacy behaviour of
+			attempting to recover these locks, then set this
+			parameter to '1'.
+			The default parameter value of '0' causes the kernel
+			not to attempt recovery of lost locks.
+
+	nfs.send_implementation_id=
+			[NFSv4.1] Send client implementation identification
+			information in exchange_id requests.
+			If zero, no implementation identification information
+			will be sent.
+			The default is to send the implementation identification
+			information.
+
+	nfs4.layoutstats_timer=
+			[NFSv4.2] Change the rate at which the kernel sends
+			layoutstats to the pNFS metadata server.
+
+			Setting this to value to 0 causes the kernel to use
+			whatever value is the default set by the layout
+			driver. A non-zero value sets the minimum interval
+			in seconds between layoutstats transmissions.
+
+	nfsd.inter_copy_offload_enable=
+			[NFSv4.2] When set to 1, the server will support
+			server-to-server copies for which this server is
+			the destination of the copy.
+
+	nfsd.nfs4_disable_idmapping=
+			[NFSv4] When set to the default of '1', the NFSv4
+			server will return only numeric uids and gids to
+			clients using auth_sys, and will accept numeric uids
+			and gids from such clients.  This is intended to ease
+			migration from NFSv2/v3.
+
+	nfsd.nfsd4_ssc_umount_timeout=
+			[NFSv4.2] When used as the destination of a
+			server-to-server copy, knfsd temporarily mounts
+			the source server.  It caches the mount in case
+			it will be needed again, and discards it if not
+			used for the number of milliseconds specified by
+			this parameter.
+
+	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
+			See Documentation/admin-guide/nfs/nfsroot.rst.
+
+	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
+			See Documentation/admin-guide/nfs/nfsroot.rst.
+
+	nfsrootdebug	[NFS] enable nfsroot debugging messages.
+			See Documentation/admin-guide/nfs/nfsroot.rst.
+
+	nmi_backtrace.backtrace_idle [KNL]
+			Dump stacks even of idle CPUs in response to an
+			NMI stack-backtrace request.
+
+	nmi_debug=	[KNL,SH] Specify one or more actions to take
+			when a NMI is triggered.
+			Format: [state][,regs][,debounce][,die]
+
+	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
+			Format: [panic,][nopanic,][rNNN,][num]
+			Valid num: 0 or 1
+			0 - turn hardlockup detector in nmi_watchdog off
+			1 - turn hardlockup detector in nmi_watchdog on
+			rNNN - configure the watchdog with raw perf event 0xNNN
+
+			When panic is specified, panic when an NMI watchdog
+			timeout occurs (or 'nopanic' to not panic on an NMI
+			watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set)
+			To disable both hard and soft lockup detectors,
+			please see 'nowatchdog'.
+			This is useful when you use a panic=... timeout and
+			need the box quickly up again.
+
+			These settings can be accessed at runtime via
+			the nmi_watchdog and hardlockup_panic sysctls.
+
+	no4lvl		[RISCV,EARLY] Disable 4-level and 5-level paging modes.
+			Forces kernel to use 3-level paging instead.
+
+	no5lvl		[X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
+			kernel to use 4-level paging instead.
+
+	noalign		[KNL,ARM]
+
+	noapic		[SMP,APIC,EARLY] Tells the kernel to not make use of any
+			IOAPICs that may be present in the system.
+
+	noapictimer	[APIC,X86] Don't set up the APIC timer
+
+	noautogroup	Disable scheduler automatic task group creation.
+
+	nocache		[ARM,EARLY]
+
+	no_console_suspend
+			[HW] Never suspend the console
+			Disable suspending of consoles during suspend and
+			hibernate operations.  Once disabled, debugging
+			messages can reach various consoles while the rest
+			of the system is being put to sleep (ie, while
+			debugging driver suspend/resume hooks).  This may
+			not work reliably with all consoles, but is known
+			to work with serial and VGA consoles.
+			To facilitate more flexible debugging, we also add
+			console_suspend, a printk module parameter to control
+			it. Users could use console_suspend (usually
+			/sys/module/printk/parameters/console_suspend) to
+			turn on/off it dynamically.
+
+	no_debug_objects
+			[KNL,EARLY] Disable object debugging
+
+	nodsp		[SH] Disable hardware DSP at boot time.
+
+	noefi		[EFI,EARLY] Disable EFI runtime services support.
+
+	no_entry_flush  [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
+
+	noexec32	[X86-64]
+			This affects only 32-bit executables.
+			noexec32=on: enable non-executable mappings (default)
+				read doesn't imply executable mappings
+			noexec32=off: disable non-executable mappings
+				read implies executable mappings
+
+	no_file_caps	Tells the kernel not to honor file capabilities.  The
+			only way then for a file to be executed with privilege
+			is to be setuid root or executed by root.
+
+	nofpu		[MIPS,SH] Disable hardware FPU at boot time.
+
+	nofsgsbase	[X86] Disables FSGSBASE instructions.
+
+	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
+			register save and restore. The kernel will only save
+			legacy floating-point registers on task switch.
+
+	nogbpages	[X86] Do not use GB pages for kernel direct mappings.
+
+	no_hash_pointers
+			[KNL,EARLY]
+			Alias for "hash_pointers=never".
+
+	nohibernate	[HIBERNATION] Disable hibernation and resume.
+
+	nohlt		[ARM,ARM64,MICROBLAZE,MIPS,PPC,RISCV,SH] Forces the kernel to
+			busy wait in do_idle() and not use the arch_cpu_idle()
+			implementation; requires CONFIG_GENERIC_IDLE_POLL_SETUP
+			to be effective. This is useful on platforms where the
+			sleep(SH) or wfi(ARM,ARM64) instructions do not work
+			correctly or when doing power measurements to evaluate
+			the impact of the sleep instructions. This is also
+			useful when using JTAG debugger.
+
+	nohpet		[X86] Don't use the HPET timer.
+
+	nohugeiomap	[KNL,X86,PPC,ARM64,EARLY] Disable kernel huge I/O mappings.
+
+	nohugevmalloc	[KNL,X86,PPC,ARM64,EARLY] Disable kernel huge vmalloc mappings.
+
+	nohz=		[KNL] Boottime enable/disable dynamic ticks
+			Valid arguments: on, off
+			Default: on
+
+	nohz_full=	[KNL,BOOT,SMP,ISOL]
+			The argument is a cpu list, as described above.
+			In kernels built with CONFIG_NO_HZ_FULL=y, set
+			the specified list of CPUs whose tick will be stopped
+			whenever possible. The boot CPU will be forced outside
+			the range to maintain the timekeeping.  Any CPUs
+			in this list will have their RCU callbacks offloaded,
+			just as if they had also been called out in the
+			rcu_nocbs= boot parameter.
+
+			Note that this argument takes precedence over
+			the CONFIG_RCU_NOCB_CPU_DEFAULT_ALL option.
+
+	noinitrd	[Deprecated,RAM] Tells the kernel not to load any configured
+			initial RAM disk. Currently this parameter applies to
+			initrd only, not to initramfs. But it applies to both
+			in EFI mode.
+
+	nointremap	[X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
+			remapping.
+			[Deprecated - use intremap=off]
+
+	noinvpcid	[X86,EARLY] Disable the INVPCID cpu feature.
+
+	noiotrap	[SH] Disables trapped I/O port accesses.
+
+	noirqdebug	[X86-32] Disables the code which attempts to detect and
+			disable unhandled interrupt sources.
+
+	noisapnp	[ISAPNP] Disables ISA PnP code.
+
+	nokaslr		[KNL,EARLY]
+			When CONFIG_RANDOMIZE_BASE is set, this disables
+			kernel and module base offset ASLR (Address Space
+			Layout Randomization).
+
+	no-kvmapf	[X86,KVM,EARLY] Disable paravirtualized asynchronous page
+			fault handling.
+
+	no-kvmclock	[X86,KVM,EARLY] Disable paravirtualized KVM clock driver
+
+	nolapic		[X86-32,APIC,EARLY] Do not enable or use the local APIC.
+
+	nolapic_timer	[X86-32,APIC,EARLY] Do not use the local APIC timer.
+
+	nomce		[X86-32] Disable Machine Check Exception
+
+	nomfgpt		[X86-32] Disable Multi-Function General Purpose
+			Timer usage (for AMD Geode machines).
+
+	nomodeset	Disable kernel modesetting. Most systems' firmware
+			sets up a display mode and provides framebuffer memory
+			for output. With nomodeset, DRM and fbdev drivers will
+			not load if they could possibly displace the pre-
+			initialized output. Only the system framebuffer will
+			be available for use. The respective drivers will not
+			perform display-mode changes or accelerated rendering.
+
+			Useful as error fallback, or for testing and debugging.
+
+	nomodule	Disable module load
+
+	nonmi_ipi	[X86] Disable using NMI IPIs during panic/reboot to
+			shutdown the other cpus.  Instead use the REBOOT_VECTOR
+			irq.
+
+	nopat		[X86,EARLY] Disable PAT (page attribute table extension of
+			pagetables) support.
+
+	nopcid		[X86-64,EARLY] Disable the PCID cpu feature.
+
+	nopku		[X86] Disable Memory Protection Keys CPU feature found
+			in some Intel CPUs.
+
+	nopti		[X86-64,EARLY]
+			Equivalent to pti=off
+
+	nopv=		[X86,XEN,KVM,HYPER_V,VMWARE,EARLY]
+			Disables the PV optimizations forcing the guest to run
+			as generic guest with no PV drivers. Currently support
+			XEN HVM, KVM, HYPER_V and VMWARE guest.
+
+	nopvspin	[X86,XEN,KVM,EARLY]
+			Disables the qspinlock slow path using PV optimizations
+			which allow the hypervisor to 'idle' the guest on lock
+			contention.
+
+	norandmaps	Don't use address space randomization.  Equivalent to
+			echo 0 > /proc/sys/kernel/randomize_va_space
+
+	noresume	[SWSUSP] Disables resume and restores original swap
+			space.
+
+	no-scroll	[VGA] Disables scrollback.
+			This is required for the Braillex ib80-piezo Braille
+			reader made by F.H. Papenmeier (Germany).
+
+	nosgx		[X86-64,SGX,EARLY] Disables Intel SGX kernel support.
+
+	nosmap		[PPC,EARLY]
+			Disable SMAP (Supervisor Mode Access Prevention)
+			even if it is supported by processor.
+
+	nosmep		[PPC64s,EARLY]
+			Disable SMEP (Supervisor Mode Execution Prevention)
+			even if it is supported by processor.
+
+	nosmp		[SMP,EARLY] Tells an SMP kernel to act as a UP kernel,
+			and disable the IO APIC.  legacy for "maxcpus=0".
+
+	nosmt		[KNL,MIPS,PPC,EARLY] Disable symmetric multithreading (SMT).
+			Equivalent to smt=1.
+
+			[KNL,LOONGARCH,X86,ARM64,PPC,S390] Disable symmetric multithreading (SMT).
+			nosmt=force: Force disable SMT, cannot be undone
+				     via the sysfs control file.
+
+	nosoftlockup	[KNL] Disable the soft-lockup detector.
+
+	nospec_store_bypass_disable
+			[HW,EARLY] Disable all mitigations for the Speculative
+			Store Bypass vulnerability
+
+	nospectre_bhb	[ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
+			history injection) vulnerability. System may allow data leaks
+			with this option.
+
+	nospectre_v1	[X86,PPC,EARLY] Disable mitigations for Spectre Variant 1
+			(bounds check bypass). With this option data leaks are
+			possible in the system.
+
+	nospectre_v2	[X86,PPC_E500,ARM64,EARLY] Disable all mitigations
+			for the Spectre variant 2 (indirect branch
+			prediction) vulnerability. System may allow data
+			leaks with this option.
+
+	no-steal-acc	[X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY]
+			Disable paravirtualized steal time accounting. steal time
+			is computed, but won't influence scheduler behaviour
+
+	nosync		[HW,M68K] Disables sync negotiation for all devices.
+
+	no_timer_check	[X86,APIC] Disables the code which tests for broken
+			timer IRQ sources, i.e., the IO-APIC timer. This can
+			work around problems with incorrect timer
+			initialization on some boards.
+
+	no_uaccess_flush
+	                [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
+
+	novmcoredd	[KNL,KDUMP]
+			Disable device dump. Device dump allows drivers to
+			append dump data to vmcore so you can collect driver
+			specified debug info.  Drivers can append the data
+			without any limit and this data is stored in memory,
+			so this may cause significant memory stress.  Disabling
+			device dump can help save memory but the driver debug
+			data will be no longer available.  This parameter
+			is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP
+			is set.
+
+	no-vmw-sched-clock
+			[X86,PV_OPS,EARLY] Disable paravirtualized VMware
+			scheduler clock and use the default one.
+
+	nowatchdog	[KNL] Disable both lockup detectors, i.e.
+			soft-lockup and NMI watchdog (hard-lockup).
+
+	nowb		[ARM,EARLY]
+
+	nox2apic	[X86-64,APIC,EARLY] Do not enable x2APIC mode.
+
+			NOTE: this parameter will be ignored on systems with the
+			LEGACY_XAPIC_DISABLED bit set in the
+			IA32_XAPIC_DISABLE_STATUS MSR.
+
+	noxsave		[BUGS=X86] Disables x86 extended register state save
+			and restore using xsave. The kernel will fallback to
+			enabling legacy floating-point and sse state.
+
+	noxsaveopt	[X86] Disables xsaveopt used in saving x86 extended
+			register states. The kernel will fall back to use
+			xsave to save the states. By using this parameter,
+			performance of saving the states is degraded because
+			xsave doesn't support modified optimization while
+			xsaveopt supports it on xsaveopt enabled systems.
+
+	noxsaves	[X86] Disables xsaves and xrstors used in saving and
+			restoring x86 extended register state in compacted
+			form of xsave area. The kernel will fall back to use
+			xsaveopt and xrstor to save and restore the states
+			in standard form of xsave area. By using this
+			parameter, xsave area per process might occupy more
+			memory on xsaves enabled systems.
+
+	nr_cpus=	[SMP,EARLY] Maximum number of processors that an SMP kernel
+			could support.  nr_cpus=n : n >= 1 limits the kernel to
+			support 'n' processors. It could be larger than the
+			number of already plugged CPU during bootup, later in
+			runtime you can physically add extra cpu until it reaches
+			n. So during boot up some boot time memory for per-cpu
+			variables need be pre-allocated for later physical cpu
+			hot plugging.
+
+	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.
+
+	numa=off 	[KNL, ARM64, PPC, RISCV, SPARC, X86, EARLY]
+			Disable NUMA, Only set up a single NUMA node
+			spanning all memory.
+
+	numa=fake=<size>[MG]
+			[KNL, ARM64, RISCV, X86, EARLY]
+			If given as a memory unit, fills all system RAM with
+			nodes of size interleaved over physical nodes.
+
+	numa=fake=<N>
+			[KNL, ARM64, RISCV, X86, EARLY]
+			If given as an integer, fills all system RAM with N
+			fake nodes interleaved over physical nodes.
+
+	numa=fake=<N>U
+			[KNL, ARM64, RISCV, X86, EARLY]
+			If given as an integer followed by 'U', it will
+			divide each physical node into N emulated nodes.
+
+	numa=noacpi	[X86] Don't parse the SRAT table for NUMA setup
+
+	numa=nohmat	[X86] Don't parse the HMAT table for NUMA setup, or
+			soft-reserved memory partitioning.
+
+	numa_balancing=	[KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
+			NUMA balancing.
+			Allowed values are enable and disable
+
+	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
+			'node', 'default' can be specified
+			This can be set from sysctl after boot.
+			See Documentation/admin-guide/sysctl/vm.rst for details.
+
+	nvme.quirks=    [NVME] A list of quirk entries to augment the built-in
+			nvme quirk list. List entries are separated by a
+			'-' character.
+			Each entry has the form VendorID:ProductID:quirk_names.
+			The IDs are 4-digits hex numbers and quirk_names is a
+			list of quirk names separated by commas. A quirk name
+			can be prefixed by '^', meaning that the specified
+			quirk must be disabled.
+
+			Example:
+			nvme.quirks=7710:2267:bogus_nid,^identify_cns-9900:7711:broken_msi
+
+	ohci1394_dma=early	[HW,EARLY] enable debugging via the ohci1394 driver.
+			See Documentation/core-api/debugging-via-ohci1394.rst for more
+			info.
+
+	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
+			Rather than timing out after 20 ms if an EC
+			command is not properly ACKed, override the length
+			of the timeout.  We have interrupts disabled while
+			waiting for the ACK, so if this is set too high
+			interrupts *may* be lost!
+
+	omap_mux=	[OMAP] Override bootloader pin multiplexing.
+			Format: <mux_mode0.mode_name=value>...
+			For example, to override I2C bus2:
+			omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
+
+	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
+
+			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
+
+			boundary - index of last SLC block on Flex-OneNAND.
+				   The remaining blocks are configured as MLC blocks.
+			lock	 - Configure if Flex-OneNAND boundary should be locked.
+				   Once locked, the boundary cannot be changed.
+				   1 indicates lock status, 0 indicates unlock status.
+
+	oops=panic	[KNL,EARLY]
+			Always panic on oopses. Default is to just kill the
+			process, but there is a small probability of
+			deadlocking the machine.
+			This will also cause panics on machine check exceptions.
+			Useful together with panic=30 to trigger a reboot.
+
+	page_alloc.shuffle=
+			[KNL] Boolean flag to control whether the page allocator
+			should randomize its free lists. This parameter can be
+			used to enable/disable page randomization. The state of
+			the flag can be read from sysfs at:
+			/sys/module/page_alloc/parameters/shuffle.
+			This parameter is only available if CONFIG_SHUFFLE_PAGE_ALLOCATOR=y.
+
+	page_owner=	[KNL,EARLY] Boot-time page_owner enabling option.
+			Storage of the information about who allocated
+			each page is disabled in default. With this switch,
+			we can turn it on.
+			on: enable the feature
+
+	page_poison=	[KNL,EARLY] Boot-time parameter changing the state of
+			poisoning on the buddy allocator, available with
+			CONFIG_PAGE_POISONING=y.
+			off: turn off poisoning (default)
+			on: turn on poisoning
+
+	page_reporting.page_reporting_order=
+			[KNL] Minimal page reporting order
+			Format: <integer>
+			Adjust the minimal page reporting order. The page
+			reporting is disabled when it exceeds MAX_PAGE_ORDER.
+
+	page_reporting.page_reporting_delay_ms=
+			[KNL] Free page reporting delay in milliseconds
+			Format: <unsigned integer>
+			Adjust the delay in milliseconds between free page
+			reporting intervals. Default is 2000 (2 seconds).
+
+	panic=		[KNL] Kernel behaviour on panic: delay <timeout>
+			timeout > 0: seconds before rebooting
+			timeout = 0: wait forever
+			timeout < 0: reboot immediately
+			Format: <timeout>
+
+	panic_on_taint=	[KNL,EARLY]
+			Bitmask for conditionally calling panic() in add_taint()
+			Format: <hex>[,nousertaint]
+			Hexadecimal bitmask representing the set of TAINT flags
+			that will cause the kernel to panic when add_taint() is
+			called with any of the flags in this set.
+			The optional switch "nousertaint" can be utilized to
+			prevent userspace forced crashes by writing to sysctl
+			/proc/sys/kernel/tainted any flagset matching with the
+			bitmask set on panic_on_taint.
+			See Documentation/admin-guide/tainted-kernels.rst for
+			extra details on the taint flags that users can pick
+			to compose the bitmask to assign to panic_on_taint.
+
+	panic_on_warn=1	panic() instead of WARN().  Useful to cause kdump
+			on a WARN().
+
+	panic_force_cpu=
+			[KNL,SMP] Force panic handling to execute on a specific CPU.
+			Format: <cpu number>
+			Some platforms require panic handling to occur on a
+			specific CPU for the crash kernel to function correctly.
+			This can be due to firmware limitations, interrupt routing
+			constraints, or platform-specific requirements where only
+			a particular CPU can safely enter the crash kernel.
+			When set, panic() will redirect execution to the specified
+			CPU before proceeding with the normal panic and kexec flow.
+			If the target CPU is offline or unavailable, panic proceeds
+			on the current CPU.
+			This option should only be used for systems with the above
+			constraints as it might cause the panic operation to be less reliable.
+
+	panic_print=	Bitmask for printing system info when panic happens.
+			User can chose combination of the following bits:
+
+			bit 0: print all tasks info
+			bit 1: print system memory info
+			bit 2: print timer info
+			bit 3: print locks info if CONFIG_LOCKDEP is on
+			bit 4: print ftrace buffer
+			bit 5: replay all kernel messages on consoles at the end of panic
+			bit 6: print all CPUs backtrace (if available in the arch)
+			bit 7: print only tasks in uninterruptible (blocked) state
+
+			*Be aware* that this option may print a _lot_ of lines.
+
+			There is an increased risk of losing older messages in
+			the log. Maybe worth to setup a	bigger log buffer with
+			"log_buf_len" along with this.
+
+			Also consider using "printk.console_no_auto_verbose=Y"
+			if using this along with pstore, to avoid extra delays
+			due to increased console verbosity during panic.
+
+	panic_sys_info= A comma separated list of extra information to be dumped
+                        on panic.
+                        Format: val[,val...]
+                        Where @val can be any of the following:
+
+                        tasks:          print all tasks info
+                        mem:            print system memory info
+			timers:         print timers info
+                        locks:          print locks info if CONFIG_LOCKDEP is on
+                        ftrace:         print ftrace buffer
+                        all_bt:         print all CPUs backtrace (if available in the arch)
+                        blocked_tasks:  print only tasks in uninterruptible (blocked) state
+
+			This is a human readable alternative to the 'panic_print'
+			option above. Please be aware of the caveats using this,
+			check the 'panic_print' parameter for more details.
+
+	panic_console_replay
+			When panic happens, replay all kernel messages on
+			consoles at the end of panic.
+
+	parkbd.port=	[HW] Parallel port number the keyboard adapter is
+			connected to, default is 0.
+			Format: <parport#>
+	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
+			0 for XT, 1 for AT (default is AT).
+			Format: <mode>
+
+	parport=	[HW,PPT] Specify parallel ports. 0 disables.
+			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
+			Use 'auto' to force the driver to use any
+			IRQ/DMA settings detected (the default is to
+			ignore detected IRQ/DMA settings because of
+			possible conflicts). You can specify the base
+			address, IRQ, and DMA settings; IRQ and DMA
+			should be numbers, or 'auto' (for using detected
+			settings on that particular port), or 'nofifo'
+			(to avoid using a FIFO even if it is detected).
+			Parallel ports are assigned in the order they
+			are specified on the command line, starting
+			with parport0.
+
+	parport_init_mode=	[HW,PPT]
+			Configure VIA parallel port to operate in
+			a specific mode. This is necessary on Pegasos
+			computer where firmware has no options for setting
+			up parallel port mode and sets it to spp.
+			Currently this function knows 686a and 8231 chips.
+			Format: [spp|ps2|epp|ecp|ecpepp]
+
+	pata_legacy.all=	[HW,LIBATA]
+			Format: <int>
+			Set to non-zero to probe primary and secondary ISA
+			port ranges on PCI systems where no PCI PATA device
+			has been found at either range.  Disabled by default.
+
+	pata_legacy.autospeed=	[HW,LIBATA]
+			Format: <int>
+			Set to non-zero if a chip is present that snoops speed
+			changes.  Disabled by default.
+
+	pata_legacy.iordy_mask=	[HW,LIBATA]
+			Format: <int>
+			IORDY enable mask.  Set individual bits to allow IORDY
+			for the respective channel.  Bit 0 is for the first
+			legacy channel handled by this driver, bit 1 is for
+			the second channel, and so on.  The sequence will often
+			correspond to the primary legacy channel, the secondary
+			legacy channel, and so on, but the handling of a PCI
+			bus and the use of other driver options may interfere
+			with the sequence.  By default IORDY is allowed across
+			all channels.
+
+	pata_legacy.pio_mask=	[HW,LIBATA]
+			Format: <int>
+			PIO mode mask for autospeed devices.  Set individual
+			bits to allow the use of the respective PIO modes.
+			Bit 0 is for mode 0, bit 1 is for mode 1, and so on.
+			All modes allowed by default.
+
+	pata_legacy.probe_all=	[HW,LIBATA]
+			Format: <int>
+			Set to non-zero to probe tertiary and further ISA
+			port ranges on PCI systems.  Disabled by default.
+
+	pata_legacy.probe_mask=	[HW,LIBATA]
+			Format: <int>
+			Probe mask for legacy ISA PATA ports.  Depending on
+			platform configuration and the use of other driver
+			options up to 6 legacy ports are supported: 0x1f0,
+			0x170, 0x1e8, 0x168, 0x1e0, 0x160, however probing
+			of individual ports can be disabled by setting the
+			corresponding bits in the mask to 1.  Bit 0 is for
+			the first port in the list above (0x1f0), and so on.
+			By default all supported ports are probed.
+
+	pata_platform.pio_mask=	[HW,LIBATA]
+			Format: <int>
+			Supported PIO mode mask.  Set individual bits to allow
+			the use of the respective PIO modes.  Bit 0 is for
+			mode 0, bit 1 is for mode 1, and so on.  Mode 0 only
+			allowed by default.
+
+	pause_on_oops=<int>
+			Halt all CPUs after the first oops has been printed for
+			the specified number of seconds.  This is to be used if
+			your oopses keep scrolling off the screen.
+
+	pci=option[,option...]	[PCI,EARLY] various PCI subsystem options.
+
+				Some options herein operate on a specific device
+				or a set of devices (<pci_dev>). These are
+				specified in one of the following formats:
+
+				[<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]*
+				pci:<vendor>:<device>[:<subvendor>:<subdevice>]
+
+				Note: the first format specifies a PCI
+				bus/device/function address which may change
+				if new hardware is inserted, if motherboard
+				firmware changes, or due to changes caused
+				by other kernel parameters. If the
+				domain is left unspecified, it is
+				taken to be zero. Optionally, a path
+				to a device through multiple device/function
+				addresses can be specified after the base
+				address (this is more robust against
+				renumbering issues).  The second format
+				selects devices using IDs from the
+				configuration space which may match multiple
+				devices in the system.
+
+		earlydump	dump PCI config space before the kernel
+				changes anything
+		off		[X86] don't probe for the PCI bus
+		bios		[X86-32] force use of PCI BIOS, don't access
+				the hardware directly. Use this if your machine
+				has a non-standard PCI host bridge.
+		nobios		[X86-32] disallow use of PCI BIOS, only direct
+				hardware access methods are allowed. Use this
+				if you experience crashes upon bootup and you
+				suspect they are caused by the BIOS.
+		conf1		[X86] Force use of PCI Configuration Access
+				Mechanism 1 (config address in IO port 0xCF8,
+				data in IO port 0xCFC, both 32-bit).
+		conf2		[X86] Force use of PCI Configuration Access
+				Mechanism 2 (IO port 0xCF8 is an 8-bit port for
+				the function, IO port 0xCFA, also 8-bit, sets
+				bus number. The config space is then accessed
+				through ports 0xC000-0xCFFF).
+				See http://wiki.osdev.org/PCI for more info
+				on the configuration access mechanisms.
+		noaer		[PCIE] If the PCIEAER kernel config parameter is
+				enabled, this kernel boot option can be used to
+				disable the use of PCIE advanced error reporting.
+		nodomains	[PCI] Disable support for multiple PCI
+				root domains (aka PCI segments, in ACPI-speak).
+		nommconf	[X86] Disable use of MMCONFIG for PCI
+				Configuration
+		check_enable_amd_mmconf [X86] check for and enable
+				properly configured MMIO access to PCI
+				config space on AMD family 10h CPU
+		nomsi		[MSI] If the PCI_MSI kernel config parameter is
+				enabled, this kernel boot option can be used to
+				disable the use of MSI interrupts system-wide.
+		noioapicquirk	[APIC] Disable all boot interrupt quirks.
+				Safety option to keep boot IRQs enabled. This
+				should never be necessary.
+		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
+				primary IO-APIC for bridges that cannot disable
+				boot IRQs. This fixes a source of spurious IRQs
+				when the system masks IRQs.
+		noioapicreroute	[APIC] Disable workaround that uses the
+				boot IRQ equivalent of an IRQ that connects to
+				a chipset where boot IRQs cannot be disabled.
+				The opposite of ioapicreroute.
+		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
+				routing table. These calls are known to be buggy
+				on several machines and they hang the machine
+				when used, but on other computers it's the only
+				way to get the interrupt routing table. Try
+				this option if the kernel is unable to allocate
+				IRQs or discover secondary PCI buses on your
+				motherboard.
+		rom		[X86] Assign address space to expansion ROMs.
+				Use with caution as certain devices share
+				address decoders between ROMs and other
+				resources.
+		norom		[X86] Do not assign address space to
+				expansion ROMs that do not already have
+				BIOS assigned address ranges.
+		nobar		[X86] Do not assign address space to the
+				BARs that weren't assigned by the BIOS.
+		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
+				assigned automatically to PCI devices. You can
+				make the kernel exclude IRQs of your ISA cards
+				this way.
+		pirqaddr=0xAAAAA	[X86] Specify the physical address
+				of the PIRQ table (normally generated
+				by the BIOS) if it is outside the
+				F0000h-100000h range.
+		lastbus=N	[X86] Scan all buses thru bus #N. Can be
+				useful if the kernel is unable to find your
+				secondary buses and you want to tell it
+				explicitly which ones they are.
+		assign-busses	[X86] Always assign all PCI bus
+				numbers ourselves, overriding
+				whatever the firmware may have done.
+		usepirqmask	[X86] Honor the possible IRQ mask stored
+				in the BIOS $PIR table. This is needed on
+				some systems with broken BIOSes, notably
+				some HP Pavilion N5400 and Omnibook XE3
+				notebooks. This will have no effect if ACPI
+				IRQ routing is enabled.
+		noacpi		[X86] Do not use ACPI for IRQ routing
+				or for PCI scanning.
+		use_crs		[X86] Use PCI host bridge window information
+				from ACPI.  On BIOSes from 2008 or later, this
+				is enabled by default.  If you need to use this,
+				please report a bug.
+		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
+				If you need to use this, please report a bug.
+		use_e820	[X86] Use E820 reservations to exclude parts of
+				PCI host bridge windows. This is a workaround
+				for BIOS defects in host bridge _CRS methods.
+				If you need to use this, please report a bug to
+				<linux-pci@vger.kernel.org>.
+		no_e820		[X86] Ignore E820 reservations for PCI host
+				bridge windows. This is the default on modern
+				hardware. If you need to use this, please report
+				a bug to <linux-pci@vger.kernel.org>.
+		routeirq	Do IRQ routing for all PCI devices.
+				This is normally done in pci_enable_device(),
+				so this option is a temporary workaround
+				for broken drivers that don't call it.
+		skip_isa_align	[X86] do not align io start addr, so can
+				handle more pci cards
+		noearly		[X86] Don't do any early type 1 scanning.
+				This might help on some broken boards which
+				machine check when some devices' config space
+				is read. But various workarounds are disabled
+				and some IOMMU drivers will not work.
+		bfsort		Sort PCI devices into breadth-first order.
+				This sorting is done to get a device
+				order compatible with older (<= 2.4) kernels.
+		nobfsort	Don't sort PCI devices into breadth-first order.
+		pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
+				tuning and use the BIOS-configured MPS defaults.
+		pcie_bus_safe	Set every device's MPS to the largest value
+				supported by all devices below the root complex.
+		pcie_bus_perf	Set device MPS to the largest allowable MPS
+				based on its parent bus. Also set MRRS (Max
+				Read Request Size) to the largest supported
+				value (no larger than the MPS that the device
+				or bus can support) for best performance.
+		pcie_bus_peer2peer	Set every device's MPS to 128B, which
+				every device is guaranteed to support. This
+				configuration allows peer-to-peer DMA between
+				any pair of devices, possibly at the cost of
+				reduced performance.  This also guarantees
+				that hot-added devices will work.
+		cbiosize=nn[KMG]	The fixed amount of bus space which is
+				reserved for the CardBus bridge's IO window.
+				The default value is 256 bytes.
+		cbmemsize=nn[KMG]	The fixed amount of bus space which is
+				reserved for the CardBus bridge's memory
+				window. The default value is 64 megabytes.
+		resource_alignment=
+				Format:
+				[<order of align>@]<pci_dev>[; ...]
+				Specifies alignment and device to reassign
+				aligned memory resources. How to
+				specify the device is described above.
+				If <order of align> is not specified,
+				PAGE_SIZE is used as alignment.
+				A PCI-PCI bridge can be specified if resource
+				windows need to be expanded.
+				To specify the alignment for several
+				instances of a device, the PCI vendor,
+				device, subvendor, and subdevice may be
+				specified, e.g., 12@pci:8086:9c22:103c:198f
+				for 4096-byte alignment.
+		ecrc=		Enable/disable PCIe ECRC (transaction layer
+				end-to-end CRC checking). Only effective if
+				OS has native AER control (either granted by
+				ACPI _OSC or forced via "pcie_ports=native")
+				bios: Use BIOS/firmware settings. This is the
+				the default.
+				off: Turn ECRC off
+				on: Turn ECRC on.
+		hpiosize=nn[KMG]	The fixed amount of bus space which is
+				reserved for hotplug bridge's IO window.
+				Default size is 256 bytes.
+		hpmmiosize=nn[KMG]	The fixed amount of bus space which is
+				reserved for hotplug bridge's MMIO window.
+				Default size is 2 megabytes.
+		hpmmioprefsize=nn[KMG]	The fixed amount of bus space which is
+				reserved for hotplug bridge's MMIO_PREF window.
+				Default size is 2 megabytes.
+		hpmemsize=nn[KMG]	The fixed amount of bus space which is
+				reserved for hotplug bridge's MMIO and
+				MMIO_PREF window.
+				Default size is 2 megabytes.
+		hpbussize=nn	The minimum amount of additional bus numbers
+				reserved for buses below a hotplug bridge.
+				Default is 1.
+		realloc=	Enable/disable reallocating PCI bridge resources
+				if allocations done by BIOS are too small to
+				accommodate resources required by all child
+				devices.
+				off: Turn realloc off
+				on: Turn realloc on
+		realloc		same as realloc=on
+		noari		do not use PCIe ARI.
+		noats		[PCIE, Intel-IOMMU, AMD-IOMMU]
+				do not use PCIe ATS (and IOMMU device IOTLB).
+		pcie_scan_all	Scan all possible PCIe devices.  Otherwise we
+				only look for one device below a PCIe downstream
+				port.
+		big_root_window	Try to add a big 64bit memory window to the PCIe
+				root complex on AMD CPUs. Some GFX hardware
+				can resize a BAR to allow access to all VRAM.
+				Adding the window is slightly risky (it may
+				conflict with unreported devices), so this
+				taints the kernel.
+		disable_acs_redir=<pci_dev>[; ...]
+				Specify one or more PCI devices (in the format
+				specified above) separated by semicolons.
+				Each device specified will have the PCI ACS
+				redirect capabilities forced off which will
+				allow P2P traffic between devices through
+				bridges without forcing it upstream. Note:
+				this removes isolation between devices and
+				may put more devices in an IOMMU group.
+		config_acs=
+				Format:
+				<ACS flags>@<pci_dev>[; ...]
+				Specify one or more PCI devices (in the format
+				specified above) optionally prepended with flags
+				and separated by semicolons. The respective
+				capabilities will be enabled, disabled or
+				unchanged based on what is specified in
+				flags.
+
+				ACS Flags is defined as follows:
+				  bit-0 : ACS Source Validation
+				  bit-1 : ACS Translation Blocking
+				  bit-2 : ACS P2P Request Redirect
+				  bit-3 : ACS P2P Completion Redirect
+				  bit-4 : ACS Upstream Forwarding
+				  bit-5 : ACS P2P Egress Control
+				  bit-6 : ACS Direct Translated P2P
+				Each bit can be marked as:
+				  '0' – force disabled
+				  '1' – force enabled
+				  'x' – unchanged
+				For example,
+				  pci=config_acs=10x@pci:0:0
+				would configure all devices that support
+				ACS to enable P2P Request Redirect, disable
+				Translation Blocking, and leave Source
+				Validation unchanged from whatever power-up
+				or firmware set it to.
+
+				Note: this may remove isolation between devices
+				and may put more devices in an IOMMU group.
+		force_floating	[S390] Force usage of floating interrupts.
+		nomio		[S390] Do not use MIO instructions.
+		norid		[S390] ignore the RID field and force use of
+				one PCI domain per PCI function
+		notph		[PCIE] If the PCIE_TPH kernel config parameter
+				is enabled, this kernel boot option can be used
+				to disable PCIe TLP Processing Hints support
+				system-wide.
+
+	pcie_aspm=	[PCIE] Forcibly enable or ignore PCIe Active State Power
+			Management.
+		off	Don't touch ASPM configuration at all.  Leave any
+			configuration done by firmware unchanged.
+		force	Enable ASPM even on devices that claim not to support it.
+			WARNING: Forcing ASPM on may cause system lockups.
+
+	pcie_ports=	[PCIE] PCIe port services handling:
+		native	Use native PCIe services (PME, AER, DPC, PCIe hotplug)
+			even if the platform doesn't give the OS permission to
+			use them.  This may cause conflicts if the platform
+			also tries to use these services.
+		dpc-native	Use native PCIe service for DPC only.  May
+				cause conflicts if firmware uses AER or DPC.
+		compat	Disable native PCIe services (PME, AER, DPC, PCIe
+			hotplug).
+
+	pcie_port_pm=	[PCIE] PCIe port power management handling:
+		off	Disable power management of all PCIe ports
+		force	Forcibly enable power management of all PCIe ports
+
+	pcie_pme=	[PCIE,PM] Native PCIe PME signaling options:
+		nomsi	Do not use MSI for native PCIe PME signaling (this makes
+			all PCIe root ports use INTx for all services).
+
+	pcmv=		[HW,PCMCIA] BadgePAD 4
+
+	pd_ignore_unused
+			[PM]
+			Keep all power-domains already enabled by bootloader on,
+			even if no driver has claimed them. This is useful
+			for debug and development, but should not be
+			needed on a platform with proper driver support.
+
+	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
+			boot time.
+			Format: { 0 | 1 }
+			See arch/parisc/kernel/pdc_chassis.c
+
+	percpu_alloc=	[MM,EARLY]
+			Select which percpu first chunk allocator to use.
+			Currently supported values are "embed" and "page".
+			Archs may support subset or none of the	selections.
+			See comments in mm/percpu.c for details on each
+			allocator.  This parameter is primarily	for debugging
+			and performance comparison.
+
+	pirq=		[SMP,APIC] Manual mp-table setup
+			See Documentation/arch/x86/i386/IO-APIC.rst.
+
+	plip=		[PPT,NET] Parallel port network link
+			Format: { parport<nr> | timid | 0 }
+			See also Documentation/admin-guide/parport.rst.
+
+	pmtmr=		[X86] Manual setup of pmtmr I/O Port.
+			Override pmtimer IOPort with a hex value.
+			e.g. pmtmr=0x508
+
+	pmu_override=	[PPC] Override the PMU.
+			This option takes over the PMU facility, so it is no
+			longer usable by perf. Setting this option starts the
+			PMU counters by setting MMCR0 to 0 (the FC bit is
+			cleared). If a number is given, then MMCR1 is set to
+			that number, otherwise (e.g., 'pmu_override=on'), MMCR1
+			remains 0.
+
+	pm_async=	[PM]
+			Format: off
+			This parameter sets the initial value of the
+			/sys/power/pm_async sysfs knob at boot time.
+			If set to "off", disables asynchronous suspend and
+			resume of devices during system-wide power transitions.
+			This can be useful on platforms where device
+			dependencies are not well-defined, or for debugging
+			power management issues. Asynchronous operations are
+			enabled by default.
+
+
+	pm_debug_messages	[SUSPEND,KNL]
+			Enable suspend/resume debug messages during boot up.
+
+	pm.dpm_watchdog_enabled=
+			[PM] Enable or disable the DPM watchdog.  Requires
+			CONFIG_PM_SLEEP and CONFIG_DPM_WATCHDOG enabled.
+			Format: <bool>
+			Default value is set by CONFIG_DPM_WATCHDOG_ENABLED.
+
+	pnp.debug=1	[PNP]
+			Enable PNP debug messages (depends on the
+			CONFIG_PNP_DEBUG_MESSAGES option).  Change at run-time
+			via /sys/module/pnp/parameters/debug.  We always show
+			current resource usage; turning this on also shows
+			possible settings and some assignment information.
+
+	pnpacpi=	[ACPI]
+			{ off }
+
+	pnpbios=	[ISAPNP]
+			{ on | off | curr | res | no-curr | no-res }
+
+	pnp_reserve_irq=
+			[ISAPNP] Exclude IRQs for the autoconfiguration
+
+	pnp_reserve_dma=
+			[ISAPNP] Exclude DMAs for the autoconfiguration
+
+	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
+			Ranges are in pairs (I/O port base and size).
+
+	pnp_reserve_mem=
+			[ISAPNP] Exclude memory regions for the
+			autoconfiguration.
+			Ranges are in pairs (memory base and size).
+
+	ports=		[IP_VS_FTP] IPVS ftp helper module
+			Default is 21.
+			Up to 8 (IP_VS_APP_MAX_PORTS) ports
+			may be specified.
+			Format: <port>,<port>....
+
+	possible_cpus=  [SMP,S390,X86]
+			Format: <unsigned int>
+			Set the number of possible CPUs, overriding the
+			regular discovery mechanisms (such as ACPI/FW, etc).
+
+	powersave=off	[PPC] This option disables power saving features.
+			It specifically disables cpuidle and sets the
+			platform machine description specific power_save
+			function to NULL. On Idle the CPU just reduces
+			execution priority.
+
+	ppc_strict_facility_enable
+			[PPC,ENABLE] This option catches any kernel floating point,
+			Altivec, VSX and SPE outside of regions specifically
+			allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
+			There is some performance impact when enabling this.
+
+	ppc_tm=		[PPC,EARLY]
+			Format: {"off"}
+			Disable Hardware Transactional Memory
+
+	preempt=	[KNL]
+			Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC
+			none - Limited to cond_resched() calls
+			voluntary - Limited to cond_resched() and might_sleep() calls
+			full - Any section that isn't explicitly preempt disabled
+			       can be preempted anytime.  Tasks will also yield
+			       contended spinlocks (if the critical section isn't
+			       explicitly preempt disabled beyond the lock itself).
+			lazy - Scheduler controlled. Similar to full but instead
+			       of preempting the task immediately, the task gets
+			       one HZ tick time to yield itself before the
+			       preemption will be forced. One preemption is when the
+			       task returns to user space.
+
+	print-fatal-signals=
+			[KNL] debug: print fatal signals
+
+			If enabled, warn about various signal handling
+			related application anomalies: too many signals,
+			too many POSIX.1 timers, fatal signals causing a
+			coredump - etc.
+
+			If you hit the warning due to signal overflow,
+			you might want to try "ulimit -i unlimited".
+
+			default: off.
+
+	printk.always_kmsg_dump=
+			Trigger kmsg_dump for cases other than kernel oops or
+			panics
+			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
+			default: disabled
+
+	printk.console_no_auto_verbose=
+			Disable console loglevel raise on oops, panic
+			or lockdep-detected issues (only if lock debug is on).
+			With an exception to setups with low baudrate on
+			serial console, keeping this 0 is a good choice
+			in order to provide more debug information.
+			Format: <bool>
+			default: 0 (auto_verbose is enabled)
+
+	printk.debug_non_panic_cpus=
+			Allows storing messages from non-panic CPUs into
+			the printk log buffer during panic(). They are
+			flushed to consoles by the panic-CPU on
+			a best-effort basis.
+			Format: <bool> (1/Y/y=enable, 0/N/n=disable)
+			Default: disabled
+
+	printk.devkmsg={on,off,ratelimit}
+			Control writing to /dev/kmsg.
+			on - unlimited logging to /dev/kmsg from userspace
+			off - logging to /dev/kmsg disabled
+			ratelimit - ratelimit the logging
+			Default: ratelimit
+
+	printk.time=	Show timing data prefixed to each printk message line
+			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
+
+	proc_mem.force_override= [KNL]
+			Format: {always | ptrace | never}
+			Traditionally /proc/pid/mem allows memory permissions to be
+			overridden without restrictions. This option may be set to
+			restrict that. Can be one of:
+			- 'always': traditional behavior always allows mem overrides.
+			- 'ptrace': only allow mem overrides for active ptracers.
+			- 'never':  never allow mem overrides.
+			If not specified, default is the CONFIG_PROC_MEM_* choice.
+
+	processor.max_cstate=	[HW,ACPI]
+			Limit processor to maximum C-state
+			max_cstate=9 overrides any DMI blacklist limit.
+
+	processor.nocst	[HW,ACPI]
+			Ignore the _CST method to determine C-states,
+			instead using the legacy FADT method
+
+	profile=	[KNL] Enable kernel profiling via /proc/profile
+			Format: [<profiletype>,]<number>
+			Param: <profiletype>: "schedule" or "kvm"
+				[defaults to kernel profiling]
+			Param: "schedule" - profile schedule points.
+			Param: "kvm" - profile VM exits.
+			Param: <number> - step/bucket size as a power of 2 for
+				statistical time based profiling.
+
+	prot_virt=	[S390] enable hosting protected virtual machines
+			isolated from the hypervisor (if hardware supports
+			that). If enabled, the default kernel base address
+			might be overridden even when Kernel Address Space
+			Layout Randomization is disabled.
+			Format: <bool>
+
+	psi=		[KNL] Enable or disable pressure stall information
+			tracking.
+			Format: <bool>
+
+	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
+			probe for; one of (bare|imps|exps|lifebook|any).
+	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
+			per second.
+	psmouse.resetafter=	[HW,MOUSE]
+			Try to reset the device after so many bad packets
+			(0 = never).
+	psmouse.resolution=
+			[HW,MOUSE] Set desired mouse resolution, in dpi.
+	psmouse.smartscroll=
+			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
+			0 = disabled, 1 = enabled (default).
+
+	pstore.backend=	Specify the name of the pstore backend to use
+
+	pti=		[X86-64] Control Page Table Isolation of user and
+			kernel address spaces.  Disabling this feature
+			removes hardening, but improves performance of
+			system calls and interrupts.
+
+			on   - unconditionally enable
+			off  - unconditionally disable
+			auto - kernel detects whether your CPU model is
+			       vulnerable to issues that PTI mitigates
+
+			Not specifying this option is equivalent to pti=auto.
+
+	pty.legacy_count=
+			[KNL] Number of legacy pty's. Overwrites compiled-in
+			default number.
+
+	quiet		[KNL,EARLY] Disable most log messages
+
+	r128=		[HW,DRM]
+
+	radix_hcall_invalidate=on  [PPC/PSERIES]
+			Disable RADIX GTSE feature and use hcall for TLB
+			invalidate.
+
+	raid=		[HW,RAID]
+			See Documentation/admin-guide/md.rst.
+
+	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
+			See Documentation/admin-guide/blockdev/ramdisk.rst.
+
+	ramdisk_start=	[Deprecated,RAM] RAM disk image start address
+
+	random.trust_cpu=off
+			[KNL,EARLY] Disable trusting the use of the CPU's
+			random number generator (if available) to
+			initialize the kernel's RNG.
+
+	random.trust_bootloader=off
+			[KNL,EARLY] Disable trusting the use of the a seed
+			passed by the bootloader (if available) to
+			initialize the kernel's RNG.
+
+	randomize_kstack_offset=
+			[KNL,EARLY] Enable or disable kernel stack offset
+			randomization, which provides roughly 5 bits of
+			entropy, frustrating memory corruption attacks
+			that depend on stack address determinism or
+			cross-syscall address exposures. This is only
+			available on architectures that have defined
+			CONFIG_HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET.
+			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
+			Default is CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT.
+
+	ras=option[,option,...]	[KNL] RAS-specific options
+
+		cec_disable	[X86]
+				Disable the Correctable Errors Collector,
+				see CONFIG_RAS_CEC help text.
+
+	rcu_nocbs[=cpu-list]
+			[KNL] The optional argument is a cpu list,
+			as described above.
+
+			In kernels built with CONFIG_RCU_NOCB_CPU=y,
+			enable the no-callback CPU mode, which prevents
+			such CPUs' callbacks from being invoked in
+			softirq context.  Invocation of such CPUs' RCU
+			callbacks will instead be offloaded to "rcuox/N"
+			kthreads created for that purpose, where "x" is
+			"p" for RCU-preempt, "s" for RCU-sched, and "g"
+			for the kthreads that mediate grace periods; and
+			"N" is the CPU number. This reduces OS jitter on
+			the offloaded CPUs, which can be useful for HPC
+			and real-time workloads.  It can also improve
+			energy efficiency for asymmetric multiprocessors.
+
+			If a cpulist is passed as an argument, the specified
+			list of	CPUs is set to no-callback mode from boot.
+
+			Otherwise, if the '=' sign and the cpulist
+			arguments are omitted, no CPU will be set to
+			no-callback mode from boot but the mode may be
+			toggled at runtime via cpusets.
+
+			Note that this argument takes precedence over
+			the CONFIG_RCU_NOCB_CPU_DEFAULT_ALL option.
+
+	rcu_nocb_poll	[KNL]
+			Rather than requiring that offloaded CPUs
+			(specified by rcu_nocbs= above) explicitly
+			awaken the corresponding "rcuoN" kthreads,
+			make these kthreads poll for callbacks.
+			This improves the real-time response for the
+			offloaded CPUs by relieving them of the need to
+			wake up the corresponding kthread, but degrades
+			energy efficiency by requiring that the kthreads
+			periodically wake up to do the polling.
+
+	rcutree.blimit=	[KNL]
+			Set maximum number of finished RCU callbacks to
+			process in one batch.
+
+	rcutree.csd_lock_suppress_rcu_stall=	[KNL]
+			Do only a one-line RCU CPU stall warning when
+			there is an ongoing too-long CSD-lock wait.
+
+	rcutree.do_rcu_barrier=	[KNL]
+			Request a call to rcu_barrier().  This is
+			throttled so that userspace tests can safely
+			hammer on the sysfs variable if they so choose.
+			If triggered before the RCU grace-period machinery
+			is fully active, this will error out with EAGAIN.
+
+	rcutree.dump_tree=	[KNL]
+			Dump the structure of the rcu_node combining tree
+			out at early boot.  This is used for diagnostic
+			purposes, to verify correct tree setup.
+
+	rcutree.gp_cleanup_delay=	[KNL]
+			Set the number of jiffies to delay each step of
+			RCU grace-period cleanup.
+
+	rcutree.gp_init_delay=	[KNL]
+			Set the number of jiffies to delay each step of
+			RCU grace-period initialization.
+
+	rcutree.gp_preinit_delay=	[KNL]
+			Set the number of jiffies to delay each step of
+			RCU grace-period pre-initialization, that is,
+			the propagation of recent CPU-hotplug changes up
+			the rcu_node combining tree.
+
+	rcutree.jiffies_till_first_fqs= [KNL]
+			Set delay from grace-period initialization to
+			first attempt to force quiescent states.
+			Units are jiffies, minimum value is zero,
+			and maximum value is HZ.
+
+	rcutree.jiffies_till_next_fqs= [KNL]
+			Set delay between subsequent attempts to force
+			quiescent states.  Units are jiffies, minimum
+			value is one, and maximum value is HZ.
+
+	rcutree.jiffies_till_sched_qs= [KNL]
+			Set required age in jiffies for a
+			given grace period before RCU starts
+			soliciting quiescent-state help from
+			rcu_note_context_switch() and cond_resched().
+			If not specified, the kernel will calculate
+			a value based on the most recent settings
+			of rcutree.jiffies_till_first_fqs
+			and rcutree.jiffies_till_next_fqs.
+			This calculated value may be viewed in
+			rcutree.jiffies_to_sched_qs.  Any attempt to set
+			rcutree.jiffies_to_sched_qs will be cheerfully
+			overwritten.
+
+	rcutree.kthread_prio= 	 [KNL,BOOT]
+			Set the SCHED_FIFO priority of the RCU per-CPU
+			kthreads (rcuc/N). This value is also used for
+			the priority of the RCU boost threads (rcub/N)
+			and for the RCU grace-period kthreads (rcu_bh,
+			rcu_preempt, and rcu_sched). If RCU_BOOST is
+			set, valid values are 1-99 and the default is 1
+			(the least-favored priority).  Otherwise, when
+			RCU_BOOST is not set, valid values are 0-99 and
+			the default is zero (non-realtime operation).
+			When RCU_NOCB_CPU is set, also adjust the
+			priority of NOCB callback kthreads.
+
+	rcutree.nocb_nobypass_lim_per_jiffy= [KNL]
+			On callback-offloaded (rcu_nocbs) CPUs,
+			RCU reduces the lock contention that would
+			otherwise be caused by callback floods through
+			use of the ->nocb_bypass list.	However, in the
+			common non-flooded case, RCU queues directly to
+			the main ->cblist in order to avoid the extra
+			overhead of the ->nocb_bypass list and its lock.
+			But if there are too many callbacks queued during
+			a single jiffy, RCU pre-queues the callbacks into
+			the ->nocb_bypass queue.  The definition of "too
+			many" is supplied by this kernel boot parameter.
+
+	rcutree.nohz_full_patience_delay= [KNL]
+			On callback-offloaded (rcu_nocbs) CPUs, avoid
+			disturbing RCU unless the grace period has
+			reached the specified age in milliseconds.
+			Defaults to zero.  Large values will be capped
+			at five seconds.  All values will be rounded down
+			to the nearest value representable by jiffies.
+
+	rcutree.qhimark= [KNL]
+			Set threshold of queued RCU callbacks beyond which
+			batch limiting is disabled.
+
+	rcutree.qlowmark= [KNL]
+			Set threshold of queued RCU callbacks below which
+			batch limiting is re-enabled.
+
+	rcutree.qovld= [KNL]
+			Set threshold of queued RCU callbacks beyond which
+			RCU's force-quiescent-state scan will aggressively
+			enlist help from cond_resched() and sched IPIs to
+			help CPUs more quickly reach quiescent states.
+			Set to less than zero to make this be set based
+			on rcutree.qhimark at boot time and to zero to
+			disable more aggressive help enlistment.
+
+	rcutree.rcu_delay_page_cache_fill_msec= [KNL]
+			Set the page-cache refill delay (in milliseconds)
+			in response to low-memory conditions.  The range
+			of permitted values is in the range 0:100000.
+
+	rcutree.rcu_divisor= [KNL]
+			Set the shift-right count to use to compute
+			the callback-invocation batch limit bl from
+			the number of callbacks queued on this CPU.
+			The result will be bounded below by the value of
+			the rcutree.blimit kernel parameter.  Every bl
+			callbacks, the softirq handler will exit in
+			order to allow the CPU to do other work.
+
+			Please note that this callback-invocation batch
+			limit applies only to non-offloaded callback
+			invocation.  Offloaded callbacks are instead
+			invoked in the context of an rcuoc kthread, which
+			scheduler will preempt as it does any other task.
+
+	rcutree.rcu_fanout_exact= [KNL]
+			Disable autobalancing of the rcu_node combining
+			tree.  This is used by rcutorture, and might
+			possibly be useful for architectures having high
+			cache-to-cache transfer latencies.
+
+	rcutree.rcu_fanout_leaf= [KNL]
+			Change the number of CPUs assigned to each
+			leaf rcu_node structure.  Useful for very
+			large systems, which will choose the value 64,
+			and for NUMA systems with large remote-access
+			latencies, which will choose a value aligned
+			with the appropriate hardware boundaries.
+
+	rcutree.rcu_min_cached_objs= [KNL]
+			Minimum number of objects which are cached and
+			maintained per one CPU. Object size is equal
+			to PAGE_SIZE. The cache allows to reduce the
+			pressure to page allocator, also it makes the
+			whole algorithm to behave better in low memory
+			condition.
+
+	rcutree.rcu_nocb_gp_stride= [KNL]
+			Set the number of NOCB callback kthreads in
+			each group, which defaults to the square root
+			of the number of CPUs.	Larger numbers reduce
+			the wakeup overhead on the global grace-period
+			kthread, but increases that same overhead on
+			each group's NOCB grace-period kthread.
+
+	rcutree.rcu_kick_kthreads= [KNL]
+			Cause the grace-period kthread to get an extra
+			wake_up() if it sleeps three times longer than
+			it should at force-quiescent-state time.
+			This wake_up() will be accompanied by a
+			WARN_ONCE() splat and an ftrace_dump().
+
+	rcutree.rcu_resched_ns= [KNL]
+			Limit the time spend invoking a batch of RCU
+			callbacks to the specified number of nanoseconds.
+			By default, this limit is checked only once
+			every 32 callbacks in order to limit the pain
+			inflicted by local_clock() overhead.
+
+	rcutree.rcu_unlock_delay= [KNL]
+			In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
+			this specifies an rcu_read_unlock()-time delay
+			in microseconds.  This defaults to zero.
+			Larger delays increase the probability of
+			catching RCU pointer leaks, that is, buggy use
+			of RCU-protected pointers after the relevant
+			rcu_read_unlock() has completed.
+
+	rcutree.sysrq_rcu= [KNL]
+			Commandeer a sysrq key to dump out Tree RCU's
+			rcu_node tree with an eye towards determining
+			why a new grace period has not yet started.
+
+	rcutree.use_softirq=	[KNL]
+			If set to zero, move all RCU_SOFTIRQ processing to
+			per-CPU rcuc kthreads.  Defaults to a non-zero
+			value, meaning that RCU_SOFTIRQ is used by default.
+			Specify rcutree.use_softirq=0 to use rcuc kthreads.
+
+			But note that CONFIG_PREEMPT_RT=y kernels disable
+			this kernel boot parameter, forcibly setting it
+			to zero.
+
+	rcutree.enable_rcu_lazy= [KNL]
+			To save power, batch RCU callbacks and flush after
+			delay, memory pressure or callback list growing too
+			big.
+
+	rcutree.rcu_normal_wake_from_gp= [KNL]
+			Reduces a latency of synchronize_rcu() call. This approach
+			maintains its own track of synchronize_rcu() callers, so it
+			does not interact with regular callbacks because it does not
+			use a call_rcu[_hurry]() path. Please note, this is for a
+			normal grace period.
+
+			How to disable it:
+
+			echo 0 > /sys/module/rcutree/parameters/rcu_normal_wake_from_gp
+			or pass a boot parameter "rcutree.rcu_normal_wake_from_gp=0"
+
+			Default is 1 if it is not explicitly disabled by the boot parameter
+			passing 0.
+
+	rcuscale.gp_async= [KNL]
+			Measure performance of asynchronous
+			grace-period primitives such as call_rcu().
+
+	rcuscale.gp_async_max= [KNL]
+			Specify the maximum number of outstanding
+			callbacks per writer thread.  When a writer
+			thread exceeds this limit, it invokes the
+			corresponding flavor of rcu_barrier() to allow
+			previously posted callbacks to drain.
+
+	rcuscale.gp_exp= [KNL]
+			Measure performance of expedited synchronous
+			grace-period primitives.
+
+	rcuscale.holdoff= [KNL]
+			Set test-start holdoff period.  The purpose of
+			this parameter is to delay the start of the
+			test until boot completes in order to avoid
+			interference.
+
+	rcuscale.kfree_by_call_rcu= [KNL]
+			In kernels built with CONFIG_RCU_LAZY=y, test
+			call_rcu() instead of kfree_rcu().
+
+	rcuscale.kfree_mult= [KNL]
+			Instead of allocating an object of size kfree_obj,
+			allocate one of kfree_mult * sizeof(kfree_obj).
+			Defaults to 1.
+
+	rcuscale.kfree_rcu_test= [KNL]
+			Set to measure performance of kfree_rcu() flooding.
+
+	rcuscale.kfree_rcu_test_double= [KNL]
+			Test the double-argument variant of kfree_rcu().
+			If this parameter has the same value as
+			rcuscale.kfree_rcu_test_single, both the single-
+			and double-argument variants are tested.
+
+	rcuscale.kfree_rcu_test_single= [KNL]
+			Test the single-argument variant of kfree_rcu().
+			If this parameter has the same value as
+			rcuscale.kfree_rcu_test_double, both the single-
+			and double-argument variants are tested.
+
+	rcuscale.kfree_nthreads= [KNL]
+			The number of threads running loops of kfree_rcu().
+
+	rcuscale.kfree_alloc_num= [KNL]
+			Number of allocations and frees done in an iteration.
+
+	rcuscale.kfree_loops= [KNL]
+			Number of loops doing rcuscale.kfree_alloc_num number
+			of allocations and frees.
+
+	rcuscale.minruntime= [KNL]
+			Set the minimum test run time in seconds.  This
+			does not affect the data-collection interval,
+			but instead allows better measurement of things
+			like CPU consumption.
+
+	rcuscale.nreaders= [KNL]
+			Set number of RCU readers.  The value -1 selects
+			N, where N is the number of CPUs.  A value
+			"n" less than -1 selects N-n+1, where N is again
+			the number of CPUs.  For example, -2 selects N
+			(the number of CPUs), -3 selects N+1, and so on.
+			A value of "n" less than or equal to -N selects
+			a single reader.
+
+	rcuscale.nwriters= [KNL]
+			Set number of RCU writers.  The values operate
+			the same as for rcuscale.nreaders.
+			N, where N is the number of CPUs
+
+	rcuscale.scale_type= [KNL]
+			Specify the RCU implementation to test.
+
+	rcuscale.shutdown= [KNL]
+			Shut the system down after performance tests
+			complete.  This is useful for hands-off automated
+			testing.
+
+	rcuscale.verbose= [KNL]
+			Enable additional printk() statements.
+
+	rcuscale.writer_holdoff= [KNL]
+			Write-side holdoff between grace periods,
+			in microseconds.  The default of zero says
+			no holdoff.
+
+	rcuscale.writer_holdoff_jiffies= [KNL]
+			Additional write-side holdoff between grace
+			periods, but in jiffies.  The default of zero
+			says no holdoff.
+
+	rcutorture.fqs_duration= [KNL]
+			Set duration of force_quiescent_state bursts
+			in microseconds.
+
+	rcutorture.fqs_holdoff= [KNL]
+			Set holdoff time within force_quiescent_state bursts
+			in microseconds.
+
+	rcutorture.fqs_stutter= [KNL]
+			Set wait time between force_quiescent_state bursts
+			in seconds.
+
+	rcutorture.fwd_progress= [KNL]
+			Specifies the number of kthreads to be used
+			for  RCU grace-period forward-progress testing
+			for the types of RCU supporting this notion.
+			Defaults to 1 kthread, values less than zero or
+			greater than the number of CPUs cause the number
+			of CPUs to be used.
+
+	rcutorture.fwd_progress_div= [KNL]
+			Specify the fraction of a CPU-stall-warning
+			period to do tight-loop forward-progress testing.
+
+	rcutorture.fwd_progress_holdoff= [KNL]
+			Number of seconds to wait between successive
+			forward-progress tests.
+
+	rcutorture.fwd_progress_need_resched= [KNL]
+			Enclose cond_resched() calls within checks for
+			need_resched() during tight-loop forward-progress
+			testing.
+
+	rcutorture.gp_cond= [KNL]
+			Use conditional/asynchronous update-side
+			normal-grace-period primitives, if available.
+
+	rcutorture.gp_cond_exp= [KNL]
+			Use conditional/asynchronous update-side
+			expedited-grace-period primitives, if available.
+
+	rcutorture.gp_cond_full= [KNL]
+			Use conditional/asynchronous update-side
+			normal-grace-period primitives that also take
+			concurrent expedited grace periods into account,
+			if available.
+
+	rcutorture.gp_cond_exp_full= [KNL]
+			Use conditional/asynchronous update-side
+			expedited-grace-period primitives that also take
+			concurrent normal grace periods into account,
+			if available.
+
+	rcutorture.gp_cond_wi= [KNL]
+			Nominal wait interval for normal conditional
+			grace periods (specified by rcutorture's
+			gp_cond and gp_cond_full module parameters),
+			in microseconds.  The actual wait interval will
+			be randomly selected to nanosecond granularity up
+			to this wait interval.	Defaults to 16 jiffies,
+			for example, 16,000 microseconds on a system
+			with HZ=1000.
+
+	rcutorture.gp_cond_wi_exp= [KNL]
+			Nominal wait interval for expedited conditional
+			grace periods (specified by rcutorture's
+			gp_cond_exp and gp_cond_exp_full module
+			parameters), in microseconds.  The actual wait
+			interval will be randomly selected to nanosecond
+			granularity up to this wait interval.  Defaults to
+			128 microseconds.
+
+	rcutorture.gp_exp= [KNL]
+			Use expedited update-side primitives, if available.
+
+	rcutorture.gp_normal= [KNL]
+			Use normal (non-expedited) asynchronous
+			update-side primitives, if available.
+
+	rcutorture.gp_poll= [KNL]
+			Use polled update-side normal-grace-period
+			primitives, if available.
+
+	rcutorture.gp_poll_exp= [KNL]
+			Use polled update-side expedited-grace-period
+			primitives, if available.
+
+	rcutorture.gp_poll_full= [KNL]
+			Use polled update-side normal-grace-period
+			primitives that also take concurrent expedited
+			grace periods into account, if available.
+
+	rcutorture.gp_poll_exp_full= [KNL]
+			Use polled update-side expedited-grace-period
+			primitives that also take concurrent normal
+			grace periods into account, if available.
+
+	rcutorture.gp_poll_wi= [KNL]
+			Nominal wait interval for normal conditional
+			grace periods (specified by rcutorture's
+			gp_poll and gp_poll_full module parameters),
+			in microseconds.  The actual wait interval will
+			be randomly selected to nanosecond granularity up
+			to this wait interval.	Defaults to 16 jiffies,
+			for example, 16,000 microseconds on a system
+			with HZ=1000.
+
+	rcutorture.gp_poll_wi_exp= [KNL]
+			Nominal wait interval for expedited conditional
+			grace periods (specified by rcutorture's
+			gp_poll_exp and gp_poll_exp_full module
+			parameters), in microseconds.  The actual wait
+			interval will be randomly selected to nanosecond
+			granularity up to this wait interval.  Defaults to
+			128 microseconds.
+
+	rcutorture.gp_sync= [KNL]
+			Use normal (non-expedited) synchronous
+			update-side primitives, if available.  If all
+			of rcutorture.gp_cond=, rcutorture.gp_exp=,
+			rcutorture.gp_normal=, and rcutorture.gp_sync=
+			are zero, rcutorture acts as if is interpreted
+			they are all non-zero.
+
+	rcutorture.gpwrap_lag= [KNL]
+			Enable grace-period wrap lag testing. Setting
+			to false prevents the gpwrap lag test from
+			running. Default is true.
+
+	rcutorture.gpwrap_lag_gps= [KNL]
+			Set the value for grace-period wrap lag during
+			active lag testing periods. This controls how many
+			grace periods differences we tolerate between
+			rdp and rnp's gp_seq before setting overflow flag.
+			The default is always set to 8.
+
+	rcutorture.gpwrap_lag_cycle_mins= [KNL]
+			Set the total cycle duration for gpwrap lag
+			testing in minutes. This is the total time for
+			one complete cycle of active and inactive
+			testing periods. Default is 30 minutes.
+
+	rcutorture.gpwrap_lag_active_mins= [KNL]
+			Set the duration for which gpwrap lag is active
+			within each cycle, in minutes. During this time,
+			the grace-period wrap lag will be set to the
+			value specified by gpwrap_lag_gps. Default is
+			5 minutes.
+
+	rcutorture.irqreader= [KNL]
+			Run RCU readers from irq handlers, or, more
+			accurately, from a timer handler.  Not all RCU
+			flavors take kindly to this sort of thing.
+
+	rcutorture.leakpointer= [KNL]
+			Leak an RCU-protected pointer out of the reader.
+			This can of course result in splats, and is
+			intended to test the ability of things like
+			CONFIG_RCU_STRICT_GRACE_PERIOD=y to detect
+			such leaks.
+
+	rcutorture.n_barrier_cbs= [KNL]
+			Set callbacks/threads for rcu_barrier() testing.
+
+	rcutorture.nfakewriters= [KNL]
+			Set number of concurrent RCU writers.  These just
+			stress RCU, they don't participate in the actual
+			test, hence the "fake".
+
+	rcutorture.nocbs_nthreads= [KNL]
+			Set number of RCU callback-offload togglers.
+			Zero (the default) disables toggling.
+
+	rcutorture.nocbs_toggle= [KNL]
+			Set the delay in milliseconds between successive
+			callback-offload toggling attempts.
+
+	rcutorture.nreaders= [KNL]
+			Set number of RCU readers.  The value -1 selects
+			N-1, where N is the number of CPUs.  A value
+			"n" less than -1 selects N-n-2, where N is again
+			the number of CPUs.  For example, -2 selects N
+			(the number of CPUs), -3 selects N+1, and so on.
+
+	rcutorture.nwriters= [KNL]
+			Set number of RCU writers, which must be either
+			zero or one.  For additional writers, use instead
+			the rcutorture.nfakewriters parameter.
+
+	rcutorture.object_debug= [KNL]
+			Enable debug-object double-call_rcu() testing.
+
+	rcutorture.onoff_holdoff= [KNL]
+			Set time (s) after boot for CPU-hotplug testing.
+
+	rcutorture.onoff_interval= [KNL]
+			Set time (jiffies) between CPU-hotplug operations,
+			or zero to disable CPU-hotplug testing.
+
+	rcutorture.preempt_duration= [KNL]
+			Set duration (in milliseconds) of preemptions
+			by a high-priority FIFO real-time task.  Set to
+			zero (the default) to disable.	The CPUs to
+			preempt are selected randomly from the set that
+			are online at a given point in time.  Races with
+			CPUs going offline are ignored, with that attempt
+			at preemption skipped.
+
+	rcutorture.preempt_interval= [KNL]
+			Set interval (in milliseconds, defaulting to one
+			second) between preemptions by a high-priority
+			FIFO real-time task.  This delay is mediated
+			by an hrtimer and is further fuzzed to avoid
+			inadvertent synchronizations.
+
+	rcutorture.read_exit_burst= [KNL]
+			The number of times in a given read-then-exit
+			episode that a set of read-then-exit kthreads
+			is spawned.
+
+	rcutorture.read_exit_delay= [KNL]
+			The delay, in seconds, between successive
+			read-then-exit testing episodes.
+
+	rcutorture.reader_flavor= [KNL]
+			A bit mask indicating which readers to use.
+			If there is more than one bit set, the readers
+			are entered from low-order bit up, and are
+			exited in the opposite order.  For SRCU, the
+			0x1 bit is normal readers, 0x2 NMI-safe readers,
+			and 0x4 light-weight readers.
+
+	rcutorture.shuffle_interval= [KNL]
+			Set task-shuffle interval (s).  Shuffling tasks
+			allows some CPUs to go into dyntick-idle mode
+			during the rcutorture test.
+
+	rcutorture.shutdown_secs= [KNL]
+			Set time (s) after boot system shutdown.  This
+			is useful for hands-off automated testing.
+
+	rcutorture.stall_cpu= [KNL]
+			Duration of CPU stall (s) to test RCU CPU stall
+			warnings, zero to disable.
+
+	rcutorture.stall_cpu_block= [KNL]
+			Sleep while stalling if set.  This will result
+			in warnings from preemptible RCU in addition to
+			any other stall-related activity.  Note that
+			in kernels built with CONFIG_PREEMPTION=n and
+			CONFIG_PREEMPT_COUNT=y, this parameter will
+			cause the CPU to pass through a quiescent state.
+			Given CONFIG_PREEMPTION=n, this will suppress
+			RCU CPU stall warnings, but will instead result
+			in scheduling-while-atomic splats.
+
+			Use of this module parameter results in splats.
+
+
+	rcutorture.stall_cpu_holdoff= [KNL]
+			Time to wait (s) after boot before inducing stall.
+
+	rcutorture.stall_cpu_irqsoff= [KNL]
+			Disable interrupts while stalling if set, but only
+			on the first stall in the set.
+
+	rcutorture.stall_cpu_repeat= [KNL]
+			Number of times to repeat the stall sequence,
+			so that rcutorture.stall_cpu_repeat=3 will result
+			in four stall sequences.
+
+	rcutorture.stall_gp_kthread= [KNL]
+			Duration (s) of forced sleep within RCU
+			grace-period kthread to test RCU CPU stall
+			warnings, zero to disable.  If both stall_cpu
+			and stall_gp_kthread are specified, the
+			kthread is starved first, then the CPU.
+
+	rcutorture.stall_only= [KNL]
+			Shut off all rcutorture kthreads other than the
+			RCU CPU stall-warning test kthreads.  The purpose
+			of this is to test production applictions'
+			reactions to CPU stalls, and with minimal
+			additional overhead.  Or you can omit the
+			stall-warning tests as well and get a heavy
+			no-op, your choice!
+
+	rcutorture.stat_interval= [KNL]
+			Time (s) between statistics printk()s.
+
+	rcutorture.stutter= [KNL]
+			Time (s) to stutter testing, for example, specifying
+			five seconds causes the test to run for five seconds,
+			wait for five seconds, and so on.  This tests RCU's
+			ability to transition abruptly to and from idle.
+
+	rcutorture.test_boost= [KNL]
+			Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
+			"Maybe" means test if the RCU implementation
+			under test support RCU priority boosting.
+
+	rcutorture.test_boost_duration= [KNL]
+			Duration (s) of each individual boost test.
+
+	rcutorture.test_boost_holdoff= [KNL]
+			Holdoff time (s) from start of test to the start
+			of RCU priority-boost testing.	Defaults to zero,
+			that is, no holdoff.
+
+	rcutorture.test_boost_interval= [KNL]
+			Interval (s) between each boost test.
+
+	rcutorture.test_no_idle_hz= [KNL]
+			Test RCU's dyntick-idle handling.  See also the
+			rcutorture.shuffle_interval parameter.
+
+	rcutorture.torture_type= [KNL]
+			Specify the RCU implementation to test.
+
+	rcutorture.verbose= [KNL]
+			Enable additional printk() statements.
+
+	rcupdate.rcu_cpu_stall_ftrace_dump= [KNL]
+			Dump ftrace buffer after reporting RCU CPU
+			stall warning.
+
+	rcupdate.rcu_cpu_stall_notifiers= [KNL]
+			Provide RCU CPU stall notifiers, but see the
+			warnings in the RCU_CPU_STALL_NOTIFIER Kconfig
+			option's help text.  TL;DR:  You almost certainly
+			do not want rcupdate.rcu_cpu_stall_notifiers.
+
+	rcupdate.rcu_cpu_stall_suppress= [KNL]
+			Suppress RCU CPU stall warning messages.
+
+	rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL]
+			Suppress RCU CPU stall warning messages and
+			rcutorture writer stall warnings that occur
+			during early boot, that is, during the time
+			before the init task is spawned.
+
+	rcupdate.rcu_cpu_stall_timeout= [KNL]
+			Set timeout for RCU CPU stall warning messages.
+			The value is in seconds and the maximum allowed
+			value is 300 seconds.
+
+	rcupdate.rcu_exp_cpu_stall_timeout= [KNL]
+			Set timeout for expedited RCU CPU stall warning
+			messages.  The value is in milliseconds
+			and the maximum allowed value is 21000
+			milliseconds. Please note that this value is
+			adjusted to an arch timer tick resolution.
+			Setting this to zero causes the value from
+			rcupdate.rcu_cpu_stall_timeout to be used (after
+			conversion from seconds to milliseconds).
+
+	rcupdate.rcu_cpu_stall_cputime= [KNL]
+			Provide statistics on the cputime and count of
+			interrupts and tasks during the sampling period. For
+			multiple continuous RCU stalls, all sampling periods
+			begin at half of the first RCU stall timeout.
+
+	rcupdate.rcu_exp_stall_task_details= [KNL]
+			Print stack dumps of any tasks blocking the
+			current expedited RCU grace period during an
+			expedited RCU CPU stall warning.
+
+	rcupdate.rcu_expedited= [KNL]
+			Use expedited grace-period primitives, for
+			example, synchronize_rcu_expedited() instead
+			of synchronize_rcu().  This reduces latency,
+			but can increase CPU utilization, degrade
+			real-time latency, and degrade energy efficiency.
+			No effect on CONFIG_TINY_RCU kernels.
+
+	rcupdate.rcu_normal= [KNL]
+			Use only normal grace-period primitives,
+			for example, synchronize_rcu() instead of
+			synchronize_rcu_expedited().  This improves
+			real-time latency, CPU utilization, and
+			energy efficiency, but can expose users to
+			increased grace-period latency.  This parameter
+			overrides rcupdate.rcu_expedited.  No effect on
+			CONFIG_TINY_RCU kernels.
+
+	rcupdate.rcu_normal_after_boot= [KNL]
+			Once boot has completed (that is, after
+			rcu_end_inkernel_boot() has been invoked), use
+			only normal grace-period primitives.  No effect
+			on CONFIG_TINY_RCU kernels.
+
+			But note that CONFIG_PREEMPT_RT=y kernels enables
+			this kernel boot parameter, forcibly setting
+			it to the value one, that is, converting any
+			post-boot attempt at an expedited RCU grace
+			period to instead use normal non-expedited
+			grace-period processing.
+
+	rcupdate.rcu_task_collapse_lim= [KNL]
+			Set the maximum number of callbacks present
+			at the beginning of a grace period that allows
+			the RCU Tasks flavors to collapse back to using
+			a single callback queue.  This switching only
+			occurs when rcupdate.rcu_task_enqueue_lim is
+			set to the default value of -1.
+
+	rcupdate.rcu_task_contend_lim= [KNL]
+			Set the minimum number of callback-queuing-time
+			lock-contention events per jiffy required to
+			cause the RCU Tasks flavors to switch to per-CPU
+			callback queuing.  This switching only occurs
+			when rcupdate.rcu_task_enqueue_lim is set to
+			the default value of -1.
+
+	rcupdate.rcu_task_enqueue_lim= [KNL]
+			Set the number of callback queues to use for the
+			RCU Tasks family of RCU flavors.  The default
+			of -1 allows this to be automatically (and
+			dynamically) adjusted.	This parameter is intended
+			for use in testing.
+
+	rcupdate.rcu_task_lazy_lim= [KNL]
+			Number of callbacks on a given CPU that will
+			cancel laziness on that CPU.  Use -1 to disable
+			cancellation of laziness, but be advised that
+			doing so increases the danger of OOM due to
+			callback flooding.
+
+	rcupdate.rcu_task_stall_info= [KNL]
+			Set initial timeout in jiffies for RCU task stall
+			informational messages, which give some indication
+			of the problem for those not patient enough to
+			wait for ten minutes.  Informational messages are
+			only printed prior to the stall-warning message
+			for a given grace period. Disable with a value
+			less than or equal to zero.  Defaults to ten
+			seconds.  A change in value does not take effect
+			until the beginning of the next grace period.
+
+	rcupdate.rcu_task_stall_info_mult= [KNL]
+			Multiplier for time interval between successive
+			RCU task stall informational messages for a given
+			RCU tasks grace period.  This value is clamped
+			to one through ten, inclusive.	It defaults to
+			the value three, so that the first informational
+			message is printed 10 seconds into the grace
+			period, the second at 40 seconds, the third at
+			160 seconds, and then the stall warning at 600
+			seconds would prevent a fourth at 640 seconds.
+
+	rcupdate.rcu_task_stall_timeout= [KNL]
+			Set timeout in jiffies for RCU task stall
+			warning messages.  Disable with a value less
+			than or equal to zero.	Defaults to ten minutes.
+			A change in value does not take effect until
+			the beginning of the next grace period.
+
+	rcupdate.rcu_tasks_lazy_ms= [KNL]
+			Set timeout in milliseconds RCU Tasks asynchronous
+			callback batching for call_rcu_tasks().
+			A negative value will take the default.  A value
+			of zero will disable batching.	Batching is
+			always disabled for synchronize_rcu_tasks().
+
+	rcupdate.rcu_self_test= [KNL]
+			Run the RCU early boot self tests
+
+	rdinit=		[KNL]
+			Format: <full_path>
+			Run specified binary instead of /init from the ramdisk,
+			used for early userspace startup. See initrd.
+
+	rdrand=		[X86,EARLY]
+			force - Override the decision by the kernel to hide the
+				advertisement of RDRAND support (this affects
+				certain AMD processors because of buggy BIOS
+				support, specifically around the suspend/resume
+				path).
+
+	rdt=		[HW,X86,RDT]
+			Turn on/off individual RDT features. List is:
+			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
+			mba, smba, bmec, abmc, sdciae, energy[:guid],
+			perf[:guid].
+			E.g. to turn on cmt and turn off mba use:
+				rdt=cmt,!mba
+			To turn off all energy telemetry monitoring and ensure that
+			perf telemetry monitoring associated with guid 0x12345
+			is enabled use:
+				rdt=!energy,perf:0x12345
+
+	reboot=		[KNL]
+			Format (x86 or x86_64):
+				[w[arm] | c[old] | h[ard] | s[oft] | g[pio]] | d[efault] \
+				[[,]s[mp]####] \
+				[[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \
+				[[,]f[orce]]
+			Where reboot_mode is one of warm (soft) or cold (hard) or gpio
+					(prefix with 'panic_' to set mode for panic
+					reboot only),
+			      reboot_type is one of bios, acpi, kbd, triple, efi, or pci,
+			      reboot_force is either force or not specified,
+			      reboot_cpu is s[mp]#### with #### being the processor
+					to be used for rebooting.
+
+		acpi
+			Use the ACPI RESET_REG in the FADT. If ACPI is not
+			configured or the ACPI reset does not work, the reboot
+			path attempts the reset using the keyboard controller.
+
+		bios
+			Use the CPU reboot vector for warm reset
+
+		cold
+			Set the cold reboot flag
+
+		default
+			There are some built-in platform specific "quirks"
+			- you may see: "reboot: <name> series board detected.
+			Selecting <type> for reboots." In the case where you
+			think the quirk is in error (e.g. you have newer BIOS,
+			or newer board) using this option will ignore the
+			built-in quirk table, and use the generic default
+			reboot actions.
+
+		efi
+			Use efi reset_system runtime service. If EFI is not
+			configured or the EFI reset does not work, the reboot
+			path attempts the reset using the keyboard controller.
+
+		force
+			Don't stop other CPUs on reboot. This can make reboot
+			more reliable in some cases.
+
+		kbd
+			Use the keyboard controller. cold reset (default)
+
+		pci
+			Use a write to the PCI config space register 0xcf9 to
+			trigger reboot.
+
+		triple
+			Force a triple fault (init)
+
+		warm
+			Don't set the cold reboot flag
+
+			Using warm reset will be much faster especially on big
+			memory systems because the BIOS will not go through
+			the memory check.  Disadvantage is that not all
+			hardware will be completely reinitialized on reboot so
+			there may be boot problems on some systems.
+
+
+	refscale.holdoff= [KNL]
+			Set test-start holdoff period.  The purpose of
+			this parameter is to delay the start of the
+			test until boot completes in order to avoid
+			interference.
+
+	refscale.lookup_instances= [KNL]
+			Number of data elements to use for the forms of
+			SLAB_TYPESAFE_BY_RCU testing.  A negative number
+			is negated and multiplied by nr_cpu_ids, while
+			zero specifies nr_cpu_ids.
+
+	refscale.loops= [KNL]
+			Set the number of loops over the synchronization
+			primitive under test.  Increasing this number
+			reduces noise due to loop start/end overhead,
+			but the default has already reduced the per-pass
+			noise to a handful of picoseconds on ca. 2020
+			x86 laptops.
+
+	refscale.nreaders= [KNL]
+			Set number of readers.  The default value of -1
+			selects N, where N is roughly 75% of the number
+			of CPUs.  A value of zero is an interesting choice.
+
+	refscale.nruns= [KNL]
+			Set number of runs, each of which is dumped onto
+			the console log.
+
+	refscale.readdelay= [KNL]
+			Set the read-side critical-section duration,
+			measured in microseconds.
+
+	refscale.scale_type= [KNL]
+			Specify the read-protection implementation to test.
+
+	refscale.shutdown= [KNL]
+			Shut down the system at the end of the performance
+			test.  This defaults to 1 (shut it down) when
+			refscale is built into the kernel and to 0 (leave
+			it running) when refscale is built as a module.
+
+	refscale.verbose= [KNL]
+			Enable additional printk() statements.
+
+	refscale.verbose_batched= [KNL]
+			Batch the additional printk() statements.  If zero
+			(the default) or negative, print everything.  Otherwise,
+			print every Nth verbose statement, where N is the value
+			specified.
+
+	regulator_ignore_unused
+			[REGULATOR]
+			Prevents regulator framework from disabling regulators
+			that are unused, due no driver claiming them. This may
+			be useful for debug and development, but should not be
+			needed on a platform with proper driver support.
+
+	relax_domain_level=
+			[KNL, SMP] Set scheduler's default relax_domain_level.
+			See Documentation/admin-guide/cgroup-v1/cpusets.rst.
+
+	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory
+			Format: <base1>,<size1>[,<base2>,<size2>,...]
+			Reserve I/O ports or memory so the kernel won't use
+			them.  If <base> is less than 0x10000, the region
+			is assumed to be I/O ports; otherwise it is memory.
+
+	reserve_mem=	[RAM]
+			Format: nn[KMG]:<align>:<label>
+			Reserve physical memory and label it with a name that
+			other subsystems can use to access it. This is typically
+			used for systems that do not wipe the RAM, and this command
+			line will try to reserve the same physical memory on
+			soft reboots. Note, it is not guaranteed to be the same
+			location. For example, if anything about the system changes
+			or if booting a different kernel. It can also fail if KASLR
+			places the kernel at the location of where the RAM reservation
+			was from a previous boot, the new reservation will be at a
+			different location.
+			Any subsystem using this feature must add a way to verify
+			that the contents of the physical memory is from a previous
+			boot, as there may be cases where the memory will not be
+			located at the same location.
+
+			The format is size:align:label for example, to request
+			12 megabytes of 4096 alignment for ramoops:
+
+			reserve_mem=12M:4096:oops ramoops.mem_name=oops
+
+	reservetop=	[X86-32,EARLY]
+			Format: nn[KMG]
+			Reserves a hole at the top of the kernel virtual
+			address space.
+
+	reset_devices	[KNL] Force drivers to reset the underlying device
+			during initialization.
+
+	resume=		[SWSUSP]
+			Specify the partition device for software suspend
+			Format:
+			{/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
+
+	resume_offset=	[SWSUSP]
+			Specify the offset from the beginning of the partition
+			given by "resume=" at which the swap header is located,
+			in <PAGE_SIZE> units (needed only for swap files).
+			See  Documentation/power/swsusp-and-swap-files.rst
+
+	resumedelay=	[HIBERNATION] Delay (in seconds) to pause before attempting to
+			read the resume files
+
+	resumewait	[HIBERNATION] Wait (indefinitely) for resume device to show up.
+			Useful for devices that are detected asynchronously
+			(e.g. USB and MMC devices).
+
+	retain_initrd	[RAM] Keep initrd memory after extraction. After boot, it will
+			be accessible via /sys/firmware/initrd.
+
+	retbleed=	[X86] Control mitigation of RETBleed (Arbitrary
+			Speculative Code Execution with Return Instructions)
+			vulnerability.
+
+			AMD-based UNRET and IBPB mitigations alone do not stop
+			sibling threads from influencing the predictions of other
+			sibling threads. For that reason, STIBP is used on pro-
+			cessors that support it, and mitigate SMT on processors
+			that don't.
+
+			off          - no mitigation
+			auto         - automatically select a mitigation
+			auto,nosmt   - automatically select a mitigation,
+				       disabling SMT if necessary for
+				       the full mitigation (only on Zen1
+				       and older without STIBP).
+			ibpb         - On AMD, mitigate short speculation
+				       windows on basic block boundaries too.
+				       Safe, highest perf impact. It also
+				       enables STIBP if present. Not suitable
+				       on Intel.
+			ibpb,nosmt   - Like "ibpb" above but will disable SMT
+				       when STIBP is not available. This is
+				       the alternative for systems which do not
+				       have STIBP.
+			unret        - Force enable untrained return thunks,
+				       only effective on AMD f15h-f17h based
+				       systems.
+			unret,nosmt  - Like unret, but will disable SMT when STIBP
+				       is not available. This is the alternative for
+				       systems which do not have STIBP.
+
+			Selecting 'auto' will choose a mitigation method at run
+			time according to the CPU.
+
+			Not specifying this option is equivalent to retbleed=auto.
+
+	rfkill.default_state=
+		0	"airplane mode".  All wifi, bluetooth, wimax, gps, fm,
+			etc. communication is blocked by default.
+		1	Unblocked.
+
+	rfkill.master_switch_mode=
+		0	The "airplane mode" button does nothing.
+		1	The "airplane mode" button toggles between everything
+			blocked and the previous configuration.
+		2	The "airplane mode" button toggles between everything
+			blocked and everything unblocked.
+
+	ring3mwait=disable
+			[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
+			CPUs.
+
+	riscv_isa_fallback [RISCV,EARLY]
+			When CONFIG_RISCV_ISA_FALLBACK is not enabled, permit
+			falling back to detecting extension support by parsing
+			"riscv,isa" property on devicetree systems when the
+			replacement properties are not found. See the Kconfig
+			entry for RISCV_ISA_FALLBACK.
+
+	riscv_nousercfi=
+		all	Disable user CFI ABI to userspace even if cpu extension
+			are available.
+		bcfi	Disable user backward CFI ABI to userspace even if
+			the shadow stack extension is available.
+		fcfi	Disable user forward CFI ABI to userspace even if the
+			landing pad extension is available.
+
+	ro		[KNL] Mount root device read-only on boot
+
+	rodata=		[KNL,EARLY]
+		on	Mark read-only kernel memory as read-only (default).
+		off	Leave read-only kernel memory writable for debugging.
+		noalias	Mark read-only kernel memory as read-only but retain
+			writable aliases in the direct map for regions outside
+			of the kernel image. [arm64]
+
+	rockchip.usb_uart
+			[EARLY]
+			Enable the uart passthrough on the designated usb port
+			on Rockchip SoCs. When active, the signals of the
+			debug-uart get routed to the D+ and D- pins of the usb
+			port and the regular usb controller gets disabled.
+
+	root=		[KNL] Root filesystem
+			Usually this is a block device specifier of some kind,
+			see the early_lookup_bdev comment in
+			block/early-lookup.c for details.
+			Alternatively this can be "ram" for the legacy initial
+			ramdisk, "nfs" and "cifs" for root on a network file
+			system, or "mtd" and "ubi" for mounting from raw flash.
+
+	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
+			mount the root filesystem
+
+	rootflags=	[KNL] Set root filesystem mount option string
+
+	rseq_slice_ext= [KNL] RSEQ based time slice extension
+			Format: boolean
+			Control enablement of RSEQ based time slice extension.
+			Default is 'on'.
+
+	initramfs_options= [KNL]
+			Specify mount options for the initramfs mount.
+
+	rootfstype=	[KNL] Set root filesystem type
+
+	rootwait	[KNL] Wait (indefinitely) for root device to show up.
+			Useful for devices that are detected asynchronously
+			(e.g. USB and MMC devices).
+
+	rootwait=	[KNL] Maximum time (in seconds) to wait for root device
+			to show up before attempting to mount the root
+			filesystem.
+
+	rproc_mem=nn[KMG][@address]
+			[KNL,ARM,CMA] Remoteproc physical memory block.
+			Memory area to be used by remote processor image,
+			managed by CMA.
+
+	rseq_debug=	[KNL] Enable or disable restartable sequence
+			debug mode. Defaults to CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE.
+			Format: <bool>
+
+	rt_group_sched=	[KNL] Enable or disable SCHED_RR/FIFO group scheduling
+			when CONFIG_RT_GROUP_SCHED=y. Defaults to
+			!CONFIG_RT_GROUP_SCHED_DEFAULT_DISABLED.
+			Format: <bool>
+
+	rw		[KNL] Mount root device read-write on boot
+
+	S		[KNL] Run init in single mode
+
+	s390_iommu=	[HW,S390]
+			Set s390 IOTLB flushing mode
+		strict
+			With strict flushing every unmap operation will result
+			in an IOTLB flush. Default is lazy flushing before
+			reuse, which is faster. Deprecated, equivalent to
+			iommu.strict=1.
+
+	s390_iommu_aperture=	[KNL,S390]
+			Specifies the size of the per device DMA address space
+			accessible through the DMA and IOMMU APIs as a decimal
+			factor of the size of main memory.
+			The default is 1 meaning that one can concurrently use
+			as many DMA addresses as physical memory is installed,
+			if supported by hardware, and thus map all of memory
+			once. With a value of 2 one can map all of memory twice
+			and so on. As a special case a factor of 0 imposes no
+			restrictions other than those given by hardware at the
+			cost of significant additional memory use for tables.
+
+
+	sched_proxy_exec= [KNL]
+			Enables or disables "proxy execution" style
+			solution to mutex-based priority inversion.
+			Format: <bool>
+
+	sched_verbose	[KNL,EARLY] Enables verbose scheduler debug messages.
+
+	schedstats=	[KNL,X86] Enable or disable scheduled statistics.
+			Allowed values are enable and disable. This feature
+			incurs a small amount of overhead in the scheduler
+			but is useful for debugging and performance tuning.
+
+	sched_thermal_decay_shift=
+			[Deprecated]
+			[KNL, SMP] Set a decay shift for scheduler thermal
+			pressure signal. Thermal pressure signal follows the
+			default decay period of other scheduler pelt
+			signals(usually 32 ms but configurable). Setting
+			sched_thermal_decay_shift will left shift the decay
+			period for the thermal pressure signal by the shift
+			value.
+			i.e. with the default pelt decay period of 32 ms
+			sched_thermal_decay_shift   thermal pressure decay pr
+				1			64 ms
+				2			128 ms
+			and so on.
+			Format: integer between 0 and 10
+			Default is 0.
+
+	scftorture.holdoff= [KNL]
+			Number of seconds to hold off before starting
+			test.  Defaults to zero for module insertion and
+			to 10 seconds for built-in smp_call_function()
+			tests.
+
+	scftorture.longwait= [KNL]
+			Request ridiculously long waits randomly selected
+			up to the chosen limit in seconds.  Zero (the
+			default) disables this feature.  Please note
+			that requesting even small non-zero numbers of
+			seconds can result in RCU CPU stall warnings,
+			softlockup complaints, and so on.
+
+	scftorture.nthreads= [KNL]
+			Number of kthreads to spawn to invoke the
+			smp_call_function() family of functions.
+			The default of -1 specifies a number of kthreads
+			equal to the number of CPUs.
+
+	scftorture.onoff_holdoff= [KNL]
+			Number seconds to wait after the start of the
+			test before initiating CPU-hotplug operations.
+
+	scftorture.onoff_interval= [KNL]
+			Number seconds to wait between successive
+			CPU-hotplug operations.  Specifying zero (which
+			is the default) disables CPU-hotplug operations.
+
+	scftorture.shutdown_secs= [KNL]
+			The number of seconds following the start of the
+			test after which to shut down the system.  The
+			default of zero avoids shutting down the system.
+			Non-zero values are useful for automated tests.
+
+	scftorture.stat_interval= [KNL]
+			The number of seconds between outputting the
+			current test statistics to the console.  A value
+			of zero disables statistics output.
+
+	scftorture.stutter_cpus= [KNL]
+			The number of jiffies to wait between each change
+			to the set of CPUs under test.
+
+	scftorture.use_cpus_read_lock= [KNL]
+			Use use_cpus_read_lock() instead of the default
+			preempt_disable() to disable CPU hotplug
+			while invoking one of the smp_call_function*()
+			functions.
+
+	scftorture.verbose= [KNL]
+			Enable additional printk() statements.
+
+	scftorture.weight_single= [KNL]
+			The probability weighting to use for the
+			smp_call_function_single() function with a zero
+			"wait" parameter.  A value of -1 selects the
+			default if all other weights are -1.  However,
+			if at least one weight has some other value, a
+			value of -1 will instead select a weight of zero.
+
+	scftorture.weight_single_wait= [KNL]
+			The probability weighting to use for the
+			smp_call_function_single() function with a
+			non-zero "wait" parameter.  See weight_single.
+
+	scftorture.weight_many= [KNL]
+			The probability weighting to use for the
+			smp_call_function_many() function with a zero
+			"wait" parameter.  See weight_single.
+			Note well that setting a high probability for
+			this weighting can place serious IPI load
+			on the system.
+
+	scftorture.weight_many_wait= [KNL]
+			The probability weighting to use for the
+			smp_call_function_many() function with a
+			non-zero "wait" parameter.  See weight_single
+			and weight_many.
+
+	scftorture.weight_all= [KNL]
+			The probability weighting to use for the
+			smp_call_function_all() function with a zero
+			"wait" parameter.  See weight_single and
+			weight_many.
+
+	scftorture.weight_all_wait= [KNL]
+			The probability weighting to use for the
+			smp_call_function_all() function with a
+			non-zero "wait" parameter.  See weight_single
+			and weight_many.
+
+	sdw_mclk_divider=[SDW]
+			Specify the MCLK divider for Intel SoundWire buses in
+			case the BIOS does not provide the clock rate properly.
+
+	skew_tick=	[KNL,EARLY] Offset the periodic timer tick per cpu to mitigate
+			xtime_lock contention on larger systems, and/or RCU lock
+			contention on all systems with CONFIG_MAXSMP set.
+			Format: { "0" | "1" }
+			0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1")
+			1 -- enable.
+			Note: increases power consumption, thus should only be
+			enabled if running jitter sensitive (HPC/RT) workloads.
+
+	security=	[SECURITY] Choose a legacy "major" security module to
+			enable at boot. This has been deprecated by the
+			"lsm=" parameter.
+
+	selinux=	[SELINUX] Disable or enable SELinux at boot time.
+			Format: { "0" | "1" }
+			See security/selinux/Kconfig help text.
+			0 -- disable.
+			1 -- enable.
+			Default value is 1.
+
+	serialnumber	[BUGS=X86-32]
+
+	sev=option[,option...] [X86-64]
+
+		debug
+			Enable debug messages.
+
+		nosnp
+			Do not enable SEV-SNP (applies to host/hypervisor
+			only). Setting 'nosnp' avoids the RMP check overhead
+			in memory accesses when users do not want to run
+			SEV-SNP guests.
+
+	shapers=	[NET]
+			Maximal number of shapers.
+
+	show_lapic=	[APIC,X86] Advanced Programmable Interrupt Controller
+			Limit apic dumping. The parameter defines the maximal
+			number of local apics being dumped. Also it is possible
+			to set it to "all" by meaning -- no limit here.
+			Format: { 1 (default) | 2 | ... | all }.
+			The parameter valid if only apic=debug or
+			apic=verbose is specified.
+			Example: apic=debug show_lapic=all
+
+	slab_debug[=options[,slabs][;[options[,slabs]]...]]	[MM]
+			Enabling slab_debug allows one to determine the
+			culprit if slab objects become corrupted. Enabling
+			slab_debug can create guard zones around objects and
+			may poison objects when not in use. Also tracks the
+			last alloc / free. For more information see
+			Documentation/admin-guide/mm/slab.rst.
+			(slub_debug legacy name also accepted for now)
+
+			Using this option implies the "no_hash_pointers"
+			option which can be undone by adding the
+			"hash_pointers=always" option.
+
+	slab_max_order= [MM]
+			Determines the maximum allowed order for slabs.
+			A high setting may cause OOMs due to memory
+			fragmentation. For more information see
+			Documentation/admin-guide/mm/slab.rst.
+			(slub_max_order legacy name also accepted for now)
+
+	slab_merge	[MM]
+			Enable merging of slabs with similar size when the
+			kernel is built without CONFIG_SLAB_MERGE_DEFAULT.
+			(slub_merge legacy name also accepted for now)
+
+	slab_min_objects=	[MM]
+			The minimum number of objects per slab. SLUB will
+			increase the slab order up to slab_max_order to
+			generate a sufficiently large slab able to contain
+			the number of objects indicated. The higher the number
+			of objects the smaller the overhead of tracking slabs
+			and the less frequently locks need to be acquired.
+			For more information see
+			Documentation/admin-guide/mm/slab.rst.
+			(slub_min_objects legacy name also accepted for now)
+
+	slab_min_order=	[MM]
+			Determines the minimum page order for slabs. Must be
+			lower or equal to slab_max_order. For more information see
+			Documentation/admin-guide/mm/slab.rst.
+			(slub_min_order legacy name also accepted for now)
+
+	slab_nomerge	[MM]
+			Disable merging of slabs with similar size. May be
+			necessary if there is some reason to distinguish
+			allocs to different slabs, especially in hardened
+			environments where the risk of heap overflows and
+			layout control by attackers can usually be
+			frustrated by disabling merging. This will reduce
+			most of the exposure of a heap attack to a single
+			cache (risks via metadata attacks are mostly
+			unchanged). Debug options disable merging on their
+			own.
+			For more information see
+			Documentation/admin-guide/mm/slab.rst.
+			(slub_nomerge legacy name also accepted for now)
+
+	slab_strict_numa	[MM]
+			Support memory policies on a per object level
+			in the slab allocator. The default is for memory
+			policies to be applied at the folio level when
+			a new folio is needed or a partial folio is
+			retrieved from the lists. Increases overhead
+			in the slab fastpaths but gains more accurate
+			NUMA kernel object placement which helps with slow
+			interconnects in NUMA systems.
+
+	slram=		[HW,MTD]
+
+	smart2=		[HW]
+			Format: <io1>[,<io2>[,...,<io8>]]
+
+	smp.csd_lock_timeout= [KNL]
+			Specify the period of time in milliseconds
+			that smp_call_function() and friends will wait
+			for a CPU to release the CSD lock.  This is
+			useful when diagnosing bugs involving CPUs
+			disabling interrupts for extended periods
+			of time.  Defaults to 5,000 milliseconds, and
+			setting a value of zero disables this feature.
+			This feature may be more efficiently disabled
+			using the csdlock_debug- kernel parameter.
+
+	smp.panic_on_ipistall= [KNL]
+			If a csd_lock_timeout extends for more than
+			the specified number of milliseconds, panic the
+			system.  By default, let CSD-lock acquisition
+			take as long as they take.  Specifying 300,000
+			for this value provides a 5-minute timeout.
+
+	smt=		[KNL,MIPS,S390,EARLY] Set the maximum number of threads
+			(logical CPUs) to use per physical CPU on systems
+			capable of symmetric multithreading (SMT). Will
+			be capped to the actual hardware limit.
+			Format: <integer>
+			Default: -1 (no limit)
+
+	softlockup_panic=
+			[KNL] Should the soft-lockup detector generate panics.
+			Format: <int>
+
+			A value of non-zero instructs the soft-lockup detector
+			to panic the machine when a soft-lockup duration exceeds
+			N thresholds. It is also controlled by the kernel.softlockup_panic
+			sysctl and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the
+			respective build-time switch to that functionality.
+
+	softlockup_all_cpu_backtrace=
+			[KNL] Should the soft-lockup detector generate
+			backtraces on all cpus.
+			Format: 0 | 1
+
+	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
+			See Documentation/admin-guide/laptops/sonypi.rst
+
+	spectre_bhi=	[X86] Control mitigation of Branch History Injection
+			(BHI) vulnerability.  This setting affects the
+			deployment of the HW BHI control and the SW BHB
+			clearing sequence.
+
+			on     - (default) Enable the HW or SW mitigation as
+				 needed.  This protects the kernel from
+				 both syscalls and VMs.
+			vmexit - On systems which don't have the HW mitigation
+				 available, enable the SW mitigation on vmexit
+				 ONLY.  On such systems, the host kernel is
+				 protected from VM-originated BHI attacks, but
+				 may still be vulnerable to syscall attacks.
+			off    - Disable the mitigation.
+
+	spectre_v2=	[X86,EARLY] Control mitigation of Spectre variant 2
+			(indirect branch speculation) vulnerability.
+			The default operation protects the kernel from
+			user space attacks.
+
+			on   - unconditionally enable, implies
+			       spectre_v2_user=on
+			off  - unconditionally disable, implies
+			       spectre_v2_user=off
+			auto - kernel detects whether your CPU model is
+			       vulnerable
+
+			Selecting 'on' will, and 'auto' may, choose a
+			mitigation method at run time according to the
+			CPU, the available microcode, the setting of the
+			CONFIG_MITIGATION_RETPOLINE configuration option,
+			and the compiler with which the kernel was built.
+
+			Selecting 'on' will also enable the mitigation
+			against user space to user space task attacks.
+			Selecting specific mitigation does not force enable
+			user mitigations.
+
+			Selecting 'off' will disable both the kernel and
+			the user space protections.
+
+			Specific mitigations can also be selected manually:
+
+			retpoline	  - replace indirect branches
+			retpoline,generic - Retpolines
+			retpoline,lfence  - LFENCE; indirect branch
+			retpoline,amd     - alias for retpoline,lfence
+			eibrs		  - Enhanced/Auto IBRS
+			eibrs,retpoline   - Enhanced/Auto IBRS + Retpolines
+			eibrs,lfence      - Enhanced/Auto IBRS + LFENCE
+			ibrs		  - use IBRS to protect kernel
+
+			Not specifying this option is equivalent to
+			spectre_v2=auto.
+
+	spectre_v2_user=
+			[X86] Control mitigation of Spectre variant 2
+		        (indirect branch speculation) vulnerability between
+		        user space tasks
+
+			on	- Unconditionally enable mitigations. Is
+				  enforced by spectre_v2=on
+
+			off     - Unconditionally disable mitigations. Is
+				  enforced by spectre_v2=off
+
+			prctl   - Indirect branch speculation is enabled,
+				  but mitigation can be enabled via prctl
+				  per thread.  The mitigation control state
+				  is inherited on fork.
+
+			prctl,ibpb
+				- Like "prctl" above, but only STIBP is
+				  controlled per thread. IBPB is issued
+				  always when switching between different user
+				  space processes.
+
+			seccomp
+				- Same as "prctl" above, but all seccomp
+				  threads will enable the mitigation unless
+				  they explicitly opt out.
+
+			seccomp,ibpb
+				- Like "seccomp" above, but only STIBP is
+				  controlled per thread. IBPB is issued
+				  always when switching between different
+				  user space processes.
+
+			auto    - Kernel selects the mitigation depending on
+				  the available CPU features and vulnerability.
+
+			Default mitigation: "prctl"
+
+			Not specifying this option is equivalent to
+			spectre_v2_user=auto.
+
+	spec_rstack_overflow=
+			[X86,EARLY] Control RAS overflow mitigation on AMD Zen CPUs
+
+			off		- Disable mitigation
+			microcode	- Enable microcode mitigation only
+			safe-ret	- Enable sw-only safe RET mitigation (default)
+			ibpb		- Enable mitigation by issuing IBPB on
+					  kernel entry
+			ibpb-vmexit	- Issue IBPB only on VMEXIT
+					  (cloud-specific mitigation)
+
+	spec_store_bypass_disable=
+			[HW,EARLY] Control Speculative Store Bypass (SSB) Disable mitigation
+			(Speculative Store Bypass vulnerability)
+
+			Certain CPUs are vulnerable to an exploit against a
+			a common industry wide performance optimization known
+			as "Speculative Store Bypass" in which recent stores
+			to the same memory location may not be observed by
+			later loads during speculative execution. The idea
+			is that such stores are unlikely and that they can
+			be detected prior to instruction retirement at the
+			end of a particular speculation execution window.
+
+			In vulnerable processors, the speculatively forwarded
+			store can be used in a cache side channel attack, for
+			example to read memory to which the attacker does not
+			directly have access (e.g. inside sandboxed code).
+
+			This parameter controls whether the Speculative Store
+			Bypass optimization is used.
+
+			On x86 the options are:
+
+			on      - Unconditionally disable Speculative Store Bypass
+			off     - Unconditionally enable Speculative Store Bypass
+			auto    - Kernel detects whether the CPU model contains an
+				  implementation of Speculative Store Bypass and
+				  picks the most appropriate mitigation. If the
+				  CPU is not vulnerable, "off" is selected. If the
+				  CPU is vulnerable the default mitigation is
+				  architecture and Kconfig dependent. See below.
+			prctl   - Control Speculative Store Bypass per thread
+				  via prctl. Speculative Store Bypass is enabled
+				  for a process by default. The state of the control
+				  is inherited on fork.
+			seccomp - Same as "prctl" above, but all seccomp threads
+				  will disable SSB unless they explicitly opt out.
+
+			Default mitigations:
+			X86:	"prctl"
+
+			On powerpc the options are:
+
+			on,auto - On Power8 and Power9 insert a store-forwarding
+				  barrier on kernel entry and exit. On Power7
+				  perform a software flush on kernel entry and
+				  exit.
+			off	- No action.
+
+			Not specifying this option is equivalent to
+			spec_store_bypass_disable=auto.
+
+	split_llc=
+			[X86,EARLY] Split the LLC N-ways
+
+			When set, the LLC is split this many ways by matching
+			'core_id % n'. This is setup before SMP bringup and
+			used during SMP bringup before it knows the full
+			topology. If your core count doesn't nicely divide by
+			the number given, you get to keep the pieces.
+
+			This is mostly a debug feature to emulate multiple LLCs
+			on hardware that only have a single LLC.
+
+	split_lock_detect=
+			[X86] Enable split lock detection or bus lock detection
+
+			When enabled (and if hardware support is present), atomic
+			instructions that access data across cache line
+			boundaries will result in an alignment check exception
+			for split lock detection or a debug exception for
+			bus lock detection.
+
+			off	- not enabled
+
+			warn	- the kernel will emit rate-limited warnings
+				  about applications triggering the #AC
+				  exception or the #DB exception. This mode is
+				  the default on CPUs that support split lock
+				  detection or bus lock detection. Default
+				  behavior is by #AC if both features are
+				  enabled in hardware.
+
+			fatal	- the kernel will send SIGBUS to applications
+				  that trigger the #AC exception or the #DB
+				  exception. Default behavior is by #AC if
+				  both features are enabled in hardware.
+
+			ratelimit:N -
+				  Set system wide rate limit to N bus locks
+				  per second for bus lock detection.
+				  0 < N <= 1000.
+
+				  N/A for split lock detection.
+
+
+			If an #AC exception is hit in the kernel or in
+			firmware (i.e. not while executing in user mode)
+			the kernel will oops in either "warn" or "fatal"
+			mode.
+
+			#DB exception for bus lock is triggered only when
+			CPL > 0.
+
+	srbds=		[X86,INTEL,EARLY]
+			Control the Special Register Buffer Data Sampling
+			(SRBDS) mitigation.
+
+			Certain CPUs are vulnerable to an MDS-like
+			exploit which can leak bits from the random
+			number generator.
+
+			By default, this issue is mitigated by
+			microcode.  However, the microcode fix can cause
+			the RDRAND and RDSEED instructions to become
+			much slower.  Among other effects, this will
+			result in reduced throughput from /dev/urandom.
+
+			The microcode mitigation can be disabled with
+			the following option:
+
+			off:    Disable mitigation and remove
+				performance impact to RDRAND and RDSEED
+
+	srcutree.big_cpu_lim [KNL]
+			Specifies the number of CPUs constituting a
+			large system, such that srcu_struct structures
+			should immediately allocate an srcu_node array.
+			This kernel-boot parameter defaults to 128,
+			but takes effect only when the low-order four
+			bits of srcutree.convert_to_big is equal to 3
+			(decide at boot).
+
+	srcutree.convert_to_big [KNL]
+			Specifies under what conditions an SRCU tree
+			srcu_struct structure will be converted to big
+			form, that is, with an rcu_node tree:
+
+				   0:  Never.
+				   1:  At init_srcu_struct() time.
+				   2:  When rcutorture decides to.
+				   3:  Decide at boot time (default).
+				0x1X:  Above plus if high contention.
+
+			Either way, the srcu_node tree will be sized based
+			on the actual runtime number of CPUs (nr_cpu_ids)
+			instead of the compile-time CONFIG_NR_CPUS.
+
+	srcutree.counter_wrap_check [KNL]
+			Specifies how frequently to check for
+			grace-period sequence counter wrap for the
+			srcu_data structure's ->srcu_gp_seq_needed field.
+			The greater the number of bits set in this kernel
+			parameter, the less frequently counter wrap will
+			be checked for.  Note that the bottom two bits
+			are ignored.
+
+	srcutree.exp_holdoff [KNL]
+			Specifies how many nanoseconds must elapse
+			since the end of the last SRCU grace period for
+			a given srcu_struct until the next normal SRCU
+			grace period will be considered for automatic
+			expediting.  Set to zero to disable automatic
+			expediting.
+
+	srcutree.srcu_max_nodelay [KNL]
+			Specifies the number of no-delay instances
+			per jiffy for which the SRCU grace period
+			worker thread will be rescheduled with zero
+			delay. Beyond this limit, worker thread will
+			be rescheduled with a sleep delay of one jiffy.
+
+	srcutree.srcu_max_nodelay_phase [KNL]
+			Specifies the per-grace-period phase, number of
+			non-sleeping polls of readers. Beyond this limit,
+			grace period worker thread will be rescheduled
+			with a sleep delay of one jiffy, between each
+			rescan of the readers, for a grace period phase.
+
+	srcutree.srcu_retry_check_delay [KNL]
+			Specifies number of microseconds of non-sleeping
+			delay between each non-sleeping poll of readers.
+
+	srcutree.small_contention_lim [KNL]
+			Specifies the number of update-side contention
+			events per jiffy will be tolerated before
+			initiating a conversion of an srcu_struct
+			structure to big form.	Note that the value of
+			srcutree.convert_to_big must have the 0x10 bit
+			set for contention-based conversions to occur.
+
+	ssbd=		[ARM64,HW,EARLY]
+			Speculative Store Bypass Disable control
+
+			On CPUs that are vulnerable to the Speculative
+			Store Bypass vulnerability and offer a
+			firmware based mitigation, this parameter
+			indicates how the mitigation should be used:
+
+			force-on:  Unconditionally enable mitigation for
+				   for both kernel and userspace
+			force-off: Unconditionally disable mitigation for
+				   for both kernel and userspace
+			kernel:    Always enable mitigation in the
+				   kernel, and offer a prctl interface
+				   to allow userspace to register its
+				   interest in being mitigated too.
+
+	stack_guard_gap=	[MM]
+			override the default stack gap protection. The value
+			is in page units and it defines how many pages prior
+			to (for stacks growing down) resp. after (for stacks
+			growing up) the main stack are reserved for no other
+			mapping. Default value is 256 pages.
+
+	stack_depot_disable= [KNL,EARLY]
+			Setting this to true through kernel command line will
+			disable the stack depot thereby saving the static memory
+			consumed by the stack hash table. By default this is set
+			to false.
+
+	stack_depot_max_pools= [KNL,EARLY]
+			Specify the maximum number of pools to use for storing
+			stack traces. Pools are allocated on-demand up to this
+			limit. Default value is 8191 pools.
+
+	stacktrace	[FTRACE]
+			Enable the stack tracer on boot up.
+
+	stacktrace_filter=[function-list]
+			[FTRACE] Limit the functions that the stack tracer
+			will trace at boot up. function-list is a comma-separated
+			list of functions. This list can be changed at run
+			time by the stack_trace_filter file in the debugfs
+			tracing directory. Note, this enables stack tracing
+			and the stacktrace above is not needed.
+
+	sti=		[PARISC,HW]
+			Format: <num>
+			Set the STI (builtin display/keyboard on the HP-PARISC
+			machines) console (graphic card) which should be used
+			as the initial boot-console.
+			See also comment in drivers/video/sticore.c.
+
+	sti_font=	[HW]
+			See comment in drivers/video/sticore.c.
+
+	stifb=		[HW]
+			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
+
+        strict_sas_size=
+			[X86]
+			Format: <bool>
+			Enable or disable strict sigaltstack size checks
+			against the required signal frame size which
+			depends on the supported FPU features. This can
+			be used to filter out binaries which have
+			not yet been made aware of AT_MINSIGSTKSZ.
+
+	stress_hpt	[PPC,EARLY]
+			Limits the number of kernel HPT entries in the hash
+			page table to increase the rate of hash page table
+			faults on kernel addresses.
+
+	stress_slb	[PPC,EARLY]
+			Limits the number of kernel SLB entries, and flushes
+			them frequently to increase the rate of SLB faults
+			on kernel addresses.
+
+	no_slb_preload	[PPC,EARLY]
+			Disables slb preloading for userspace.
+
+	sunrpc.min_resvport=
+	sunrpc.max_resvport=
+			[NFS,SUNRPC]
+			SunRPC servers often require that client requests
+			originate from a privileged port (i.e. a port in the
+			range 0 < portnr < 1024).
+			An administrator who wishes to reserve some of these
+			ports for other uses may adjust the range that the
+			kernel's sunrpc client considers to be privileged
+			using these two parameters to set the minimum and
+			maximum port values.
+
+	sunrpc.svc_rpc_per_connection_limit=
+			[NFS,SUNRPC]
+			Limit the number of requests that the server will
+			process in parallel from a single connection.
+			The default value is 0 (no limit).
+
+	sunrpc.pool_mode=
+			[NFS]
+			Deprecated.  The NFS server now always uses one
+			service thread pool per NUMA node (equivalent to a
+			single global pool on non-NUMA machines).  All of
+			the previously accepted values (auto, global,
+			percpu, pernode) are still accepted for backward
+			compatibility but are ignored: the mode is always
+			pernode, and reads always return "pernode".
+
+	sunrpc.tcp_slot_table_entries=
+	sunrpc.udp_slot_table_entries=
+			[NFS,SUNRPC]
+			Sets the upper limit on the number of simultaneous
+			RPC calls that can be sent from the client to a
+			server. Increasing these values may allow you to
+			improve throughput, but will also increase the
+			amount of memory reserved for use by the client.
+
+	suspend.pm_test_delay=
+			[SUSPEND]
+			Sets the number of seconds to remain in a suspend test
+			mode before resuming the system (see
+			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
+			is set. Default value is 5.
+
+	svm=		[PPC]
+			Format: { on | off | y | n | 1 | 0 }
+			This parameter controls use of the Protected
+			Execution Facility on pSeries.
+
+	swiotlb=	[ARM,PPC,MIPS,X86,S390,EARLY]
+			Format: { <int> [,<int>] | force | noforce | track_hiwater}
+			<int> -- Number of I/O TLB slabs
+			<int> -- Second integer after comma. Number of swiotlb
+				 areas with their own lock. Will be rounded up
+				 to a power of 2.
+			force -- force using of bounce buffers even if they
+			         wouldn't be automatically used by the kernel
+			noforce -- Never use bounce buffers (for debugging)
+			track_hiwater -- Track high watermark of swiotlb buffers.
+			                 Only available when CONFIG_DEBUG_FS is set.
+
+	switches=	[HW,M68k,EARLY]
+
+	sysctl.*=	[KNL]
+			Set a sysctl parameter, right before loading the init
+			process, as if the value was written to the respective
+			/proc/sys/... file. Both '.' and '/' are recognized as
+			separators. Unrecognized parameters and invalid values
+			are reported in the kernel log. Sysctls registered
+			later by a loaded module cannot be set this way.
+			Example: sysctl.vm.swappiness=40
+
+	sysrq_always_enabled
+			[KNL]
+			Ignore sysrq setting - this boot parameter will
+			neutralize any effect of /proc/sys/kernel/sysrq.
+			Useful for debugging.
+
+	tcpmhash_entries= [KNL,NET]
+			Set the number of tcp_metrics_hash slots.
+			Default value is 8192 or 16384 depending on total
+			ram pages. This is used to specify the TCP metrics
+			cache size. See Documentation/networking/ip-sysctl.rst
+			"tcp_no_metrics_save" section for more details.
+
+	tdfx=		[HW,DRM]
+
+	test_suspend=	[SUSPEND]
+			Format: { "mem" | "standby" | "freeze" }[,N]
+			Specify "mem" (for Suspend-to-RAM) or "standby" (for
+			standby suspend) or "freeze" (for suspend type freeze)
+			as the system sleep state during system startup with
+			the optional capability to repeat N number of times.
+			The system is woken from this state using a
+			wakeup-capable RTC alarm.
+
+	thash_entries=	[KNL,NET]
+			Set number of hash buckets for TCP connection
+
+	thermal.act=	[HW,ACPI]
+			-1: disable all active trip points in all thermal zones
+			<degrees C>: override all lowest active trip points
+
+	thermal.crt=	[HW,ACPI]
+			-1: disable all critical trip points in all thermal zones
+			<degrees C>: override all critical trip points
+
+	thermal.off=	[HW,ACPI]
+			1: disable ACPI thermal control
+
+	thermal.psv=	[HW,ACPI]
+			-1: disable all passive trip points
+			<degrees C>: override all passive trip points to this
+			value
+
+	thermal.tzp=	[HW,ACPI]
+			Specify global default ACPI thermal zone polling rate
+			<deci-seconds>: poll all this frequency
+			0: no polling (default)
+
+	thp_anon=	[KNL]
+			Format: <size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>
+			state is one of "always", "madvise", "never" or "inherit".
+			Control the default behavior of the system with respect
+			to anonymous transparent hugepages.
+			Can be used multiple times for multiple anon THP sizes.
+			See Documentation/admin-guide/mm/transhuge.rst for more
+			details.
+
+	threadirqs	[KNL,EARLY]
+			Force threading of all interrupt handlers except those
+			marked explicitly IRQF_NO_THREAD.
+
+	thp_shmem=	[KNL]
+			Format: <size>[KMG],<size>[KMG]:<policy>;<size>[KMG]-<size>[KMG]:<policy>
+			Control the default policy of each hugepage size for the
+			internal shmem mount. <policy> is one of policies available
+			for the shmem mount ("always", "inherit", "never", "within_size",
+			and "advise").
+			It can be used multiple times for multiple shmem THP sizes.
+			See Documentation/admin-guide/mm/transhuge.rst for more
+			details.
+
+	tlbi=		[X86-64]
+			Format: {ipi}
+			ipi: switch to IPI-based TLB flushing
+
+	topology=	[S390,EARLY]
+			Format: {off | on}
+			Specify if the kernel should make use of the cpu
+			topology information if the hardware supports this.
+			The scheduler will make use of this information and
+			e.g. base its process migration decisions on it.
+			Default is on.
+
+	torture.disable_onoff_at_boot= [KNL]
+			Prevent the CPU-hotplug component of torturing
+			until after init has spawned.
+
+	torture.ftrace_dump_at_shutdown= [KNL]
+			Dump the ftrace buffer at torture-test shutdown,
+			even if there were no errors.  This can be a
+			very costly operation when many torture tests
+			are running concurrently, especially on systems
+			with rotating-rust storage.
+
+	torture.verbose_sleep_frequency= [KNL]
+			Specifies how many verbose printk()s should be
+			emitted between each sleep.  The default of zero
+			disables verbose-printk() sleeping.
+
+	torture.verbose_sleep_duration= [KNL]
+			Duration of each verbose-printk() sleep in jiffies.
+
+	tpm.disable_pcr_integrity= [HW,TPM]
+			Do not protect PCR registers from unintended physical
+			access, or interposers in the bus by the means of
+			having an integrity protected session wrapped around
+			TPM2_PCR_Extend command. Consider this in a situation
+			where TPM is heavily utilized by IMA, thus protection
+			causing a major performance hit, and the space where
+			machines are deployed is by other means guarded.
+
+	tpm_crb_ffa.busy_timeout_ms= [ARM64,TPM]
+			Maximum time in milliseconds to retry sending a message
+			to the TPM service before giving up. This parameter controls
+			how long the system will continue retrying when the TPM
+			service is busy.
+			Format: <unsigned int>
+			Default: 2000 (2 seconds)
+
+	tpm_suspend_pcr=[HW,TPM]
+			Format: integer pcr id
+			Specify that at suspend time, the tpm driver
+			should extend the specified pcr with zeros,
+			as a workaround for some chips which fail to
+			flush the last written pcr on TPM_SaveState.
+			This will guarantee that all the other pcrs
+			are saved.
+
+	tpm_tis.interrupts= [HW,TPM]
+			Enable interrupts for the MMIO based physical layer
+			for the FIFO interface. By default it is set to false
+			(0). For more information about TPM hardware interfaces
+			defined by Trusted Computing Group (TCG) see
+			https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
+
+	tp_printk	[FTRACE]
+			Have the tracepoints sent to printk as well as the
+			tracing ring buffer. This is useful for early boot up
+			where the system hangs or reboots and does not give the
+			option for reading the tracing buffer or performing a
+			ftrace_dump_on_oops.
+
+			To turn off having tracepoints sent to printk,
+			 echo 0 > /proc/sys/kernel/tracepoint_printk
+			Note, echoing 1 into this file without the
+			tp_printk kernel cmdline option has no effect.
+
+			The tp_printk_stop_on_boot (see below) can also be used
+			to stop the printing of events to console at
+			late_initcall_sync.
+
+			** CAUTION **
+
+			Having tracepoints sent to printk() and activating high
+			frequency tracepoints such as irq or sched, can cause
+			the system to live lock.
+
+	tp_printk_stop_on_boot [FTRACE]
+			When tp_printk (above) is set, it can cause a lot of noise
+			on the console. It may be useful to only include the
+			printing of events during boot up, as user space may
+			make the system inoperable.
+
+			This command line option will stop the printing of events
+			to console at the late_initcall_sync() time frame.
+
+	trace_buf_size=nn[KMG]
+			[FTRACE] will set tracing buffer size on each cpu.
+
+	trace_clock=	[FTRACE] Set the clock used for tracing events
+			at boot up.
+			local - Use the per CPU time stamp counter
+				(converted into nanoseconds). Fast, but
+				depending on the architecture, may not be
+				in sync between CPUs.
+			global - Event time stamps are synchronized across
+				CPUs. May be slower than the local clock,
+				but better for some race conditions.
+			counter - Simple counting of events (1, 2, ..)
+				note, some counts may be skipped due to the
+				infrastructure grabbing the clock more than
+				once per event.
+			uptime - Use jiffies as the time stamp.
+			perf - Use the same clock that perf uses.
+			mono - Use ktime_get_mono_fast_ns() for time stamps.
+			mono_raw - Use ktime_get_raw_fast_ns() for time
+				stamps.
+			boot - Use ktime_get_boot_fast_ns() for time stamps.
+			Architectures may add more clocks. See
+			Documentation/trace/ftrace.rst for more details.
+
+	trace_event=[event-list]
+			[FTRACE] Set and start specified trace events in order
+			to facilitate early boot debugging. The event-list is a
+			comma-separated list of trace events to enable. See
+			also Documentation/trace/events.rst
+
+			To enable modules, use :mod: keyword:
+
+			trace_event=:mod:<module>
+
+			The value before :mod: will only enable specific events
+			that are part of the module. See the above mentioned
+			document for more information.
+
+	trace_instance=[instance-info]
+			[FTRACE] Create a ring buffer instance early in boot up.
+			This will be listed in:
+
+				/sys/kernel/tracing/instances
+
+			Events can be enabled at the time the instance is created
+			via:
+
+				trace_instance=<name>,<system1>:<event1>,<system2>:<event2>
+
+			Note, the "<system*>:" portion is optional if the event is
+			unique.
+
+				trace_instance=foo,sched:sched_switch,irq_handler_entry,initcall
+
+			will enable the "sched_switch" event (note, the "sched:" is optional, and
+			the same thing would happen if it was left off). The irq_handler_entry
+			event, and all events under the "initcall" system.
+
+			Flags can be added to the instance to modify its behavior when it is
+			created. The flags are separated by '^'.
+
+			The available flags are:
+
+			    traceoff	- Have the tracing instance tracing disabled after it is created.
+			    traceprintk	- Have trace_printk() write into this trace instance
+					  (note, "printk" and "trace_printk" can also be used)
+
+				trace_instance=foo^traceoff^traceprintk,sched,irq
+
+			The flags must come before the defined events.
+
+			If memory has been reserved (see memmap for x86), the instance
+			can use that memory:
+
+				memmap=12M$0x284500000 trace_instance=boot_map@0x284500000:12M
+
+			The above will create a "boot_map" instance that uses the physical
+			memory at 0x284500000 that is 12Megs. The per CPU buffers of that
+			instance will be split up accordingly.
+
+			Alternatively, the memory can be reserved by the reserve_mem option:
+
+				reserve_mem=12M:4096:trace trace_instance=boot_map@trace
+
+			This will reserve 12 megabytes at boot up with a 4096 byte alignment
+			and place the ring buffer in this memory. Note that due to KASLR, the
+			memory may not be the same location each time, which will not preserve
+			the buffer content.
+
+			Also note that the layout of the ring buffer data may change between
+			kernel versions where the validator will fail and reset the ring buffer
+			if the layout is not the same as the previous kernel.
+
+			If the ring buffer is used for persistent bootups and has events enabled,
+			it is recommend to disable tracing so that events from a previous boot do not
+			mix with events of the current boot (unless you are debugging a random crash
+			at boot up).
+
+				reserve_mem=12M:4096:trace trace_instance=boot_map^traceoff^traceprintk@trace,sched,irq
+
+			Note, saving the trace buffer across reboots does require that the system
+			is set up to not wipe memory. For instance, CONFIG_RESET_ATTACK_MITIGATION
+			can force a memory reset on boot which will clear any trace that was stored.
+			This is just one of many ways that can clear memory. Make sure your system
+			keeps the content of memory across reboots before relying on this option.
+
+			NB: Both the mapped address and size must be page aligned for the architecture.
+
+			See also Documentation/trace/debugging.rst
+
+
+	trace_options=[option-list]
+			[FTRACE] Enable or disable tracer options at boot.
+			The option-list is a comma delimited list of options
+			that can be enabled or disabled just as if you were
+			to echo the option name into
+
+			    /sys/kernel/tracing/trace_options
+
+			For example, to enable stacktrace option (to dump the
+			stack trace of each event), add to the command line:
+
+			      trace_options=stacktrace
+
+			See also Documentation/trace/ftrace.rst "trace options"
+			section.
+
+	trace_trigger=[trigger-list]
+			[FTRACE] Add an event trigger on specific events.
+			Set a trigger on top of a specific event, with an optional
+			filter.
+
+			The format is "trace_trigger=<event>.<trigger>[ if <filter>],..."
+			Where more than one trigger may be specified that are comma delimited.
+
+			For example:
+
+			  trace_trigger="sched_switch.stacktrace if prev_state == 2"
+
+			The above will enable the "stacktrace" trigger on the "sched_switch"
+			event but only trigger it if the "prev_state" of the "sched_switch"
+			event is "2" (TASK_UNINTERRUPTIBLE).
+
+			See also "Event triggers" in Documentation/trace/events.rst
+
+
+	traceoff_after_boot
+			[FTRACE] Sometimes tracing is used to debug issues
+			during the boot process. Since the trace buffer has a
+			limited amount of storage, it may be prudent to
+			disable tracing after the boot is finished, otherwise
+			the critical information may be overwritten.  With this
+			option, the main tracing buffer will be turned off at
+			the end of the boot process.
+
+	traceoff_on_warning
+			[FTRACE] enable this option to disable tracing when a
+			warning is hit. This turns off "tracing_on". Tracing can
+			be enabled again by echoing '1' into the "tracing_on"
+			file located in /sys/kernel/tracing/
+
+			This option is useful, as it disables the trace before
+			the WARNING dump is called, which prevents the trace to
+			be filled with content caused by the warning output.
+
+			This option can also be set at run time via the sysctl
+			option:  kernel/traceoff_on_warning
+
+	transparent_hugepage=
+			[KNL]
+			Format: [always|madvise|never]
+			Can be used to control the default behavior of the system
+			with respect to transparent hugepages.
+			See Documentation/admin-guide/mm/transhuge.rst
+			for more details.
+
+	transparent_hugepage_shmem= [KNL]
+			Format: [always|within_size|advise|never|deny|force]
+			Can be used to control the hugepage allocation policy for
+			the internal shmem mount.
+			See Documentation/admin-guide/mm/transhuge.rst
+			for more details.
+
+	transparent_hugepage_tmpfs= [KNL]
+			Format: [always|within_size|advise|never]
+			Can be used to control the default hugepage allocation policy
+			for the tmpfs mount.
+			See Documentation/admin-guide/mm/transhuge.rst
+			for more details.
+
+	trusted.source=	[KEYS]
+			Format: <string>
+			This parameter identifies the trust source as a backend
+			for trusted keys implementation. Supported trust
+			sources:
+			- "tpm"
+			- "tee"
+			- "caam"
+			- "dcp"
+			- "pkwm"
+			If not specified then it defaults to iterating through
+			the trust source list starting with TPM and assigns the
+			first trust source as a backend which is initialized
+			successfully during iteration.
+
+	trusted.debug=	[KEYS]
+			Format: <bool>
+			Enable trusted keys debug traces at runtime when
+			CONFIG_TRUSTED_KEYS_DEBUG=y.
+
+			To make the traces visible after enabling the option,
+			use trusted.dyndbg='+p' as needed. By convention,
+			the subsystem uses pr_debug() for these traces.
+
+			SAFETY: The traces can leak sensitive data, so be
+			cautious before enabling this. They remain inactive
+			unless this parameter is set this option to  a true
+			value.
+
+			Default: false
+
+	trusted.rng=	[KEYS]
+			Format: <string>
+			The RNG used to generate key material for trusted keys.
+			Can be one of:
+			- "kernel"
+			- the same value as trusted.source: "tpm" or "tee"
+			- "default"
+			If not specified, "default" is used. In this case,
+			the RNG's choice is left to each individual trust source.
+
+	trusted.dcp_use_otp_key
+			This is intended to be used in combination with
+			trusted.source=dcp and will select the DCP OTP key
+			instead of the DCP UNIQUE key blob encryption.
+
+	trusted.dcp_skip_zk_test
+			This is intended to be used in combination with
+			trusted.source=dcp and will disable the check if the
+			blob key is all zeros. This is helpful for situations where
+			having this key zero'ed is acceptable. E.g. in testing
+			scenarios.
+
+	tsa=		[X86] Control mitigation for Transient Scheduler
+			Attacks on AMD CPUs. Search the following in your
+			favourite search engine for more details:
+
+			"Technical guidance for mitigating transient scheduler
+			attacks".
+
+			off		- disable the mitigation
+			on		- enable the mitigation (default)
+			user		- mitigate only user/kernel transitions
+			vm		- mitigate only guest/host transitions
+
+
+	tsc=		Disable clocksource stability checks for TSC.
+			Format: <string>
+			[x86] reliable: mark tsc clocksource as reliable, this
+			disables clocksource verification at runtime, as well
+			as the stability checks done at bootup.	Used to enable
+			high-resolution timer mode on older hardware, and in
+			virtualized environment.
+			[x86] noirqtime: Do not use TSC to do irq accounting.
+			Used to run time disable IRQ_TIME_ACCOUNTING on any
+			platforms where RDTSC is slow and this accounting
+			can add overhead.
+			[x86] unstable: mark the TSC clocksource as unstable, this
+			marks the TSC unconditionally unstable at bootup and
+			avoids any further wobbles once the TSC watchdog notices.
+			[x86] nowatchdog: disable clocksource watchdog. Used
+			in situations with strict latency requirements (where
+			interruptions from clocksource watchdog are not
+			acceptable).
+			[x86] recalibrate: force recalibration against a HW timer
+			(HPET or PM timer) on systems whose TSC frequency was
+			obtained from HW or FW using either an MSR or CPUID(0x15).
+			Warn if the difference is more than 500 ppm.
+			[x86] watchdog: Enforce the clocksource watchdog on TSC
+
+	tsc_early_khz=  [X86,EARLY] Skip early TSC calibration and use the given
+			value instead. Useful when the early TSC frequency discovery
+			procedure is not reliable, such as on overclocked systems
+			with CPUID.16h support and partial CPUID.15h support.
+			Format: <unsigned int>
+
+	tsx=		[X86] Control Transactional Synchronization
+			Extensions (TSX) feature in Intel processors that
+			support TSX control.
+
+			This parameter controls the TSX feature. The options are:
+
+			on	- Enable TSX on the system. Although there are
+				mitigations for all known security vulnerabilities,
+				TSX has been known to be an accelerator for
+				several previous speculation-related CVEs, and
+				so there may be unknown	security risks associated
+				with leaving it enabled.
+
+			off	- Disable TSX on the system. (Note that this
+				option takes effect only on newer CPUs which are
+				not vulnerable to MDS, i.e., have
+				MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
+				the new IA32_TSX_CTRL MSR through a microcode
+				update. This new MSR allows for the reliable
+				deactivation of the TSX functionality.)
+
+			auto	- Disable TSX if X86_BUG_TAA is present,
+				  otherwise enable TSX on the system.
+
+			Not specifying this option is equivalent to tsx=off.
+
+			See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+			for more details.
+
+	tsx_async_abort= [X86,INTEL,EARLY] Control mitigation for the TSX Async
+			Abort (TAA) vulnerability.
+
+			Similar to Micro-architectural Data Sampling (MDS)
+			certain CPUs that support Transactional
+			Synchronization Extensions (TSX) are vulnerable to an
+			exploit against CPU internal buffers which can forward
+			information to a disclosure gadget under certain
+			conditions.
+
+			In vulnerable processors, the speculatively forwarded
+			data can be used in a cache side channel attack, to
+			access data to which the attacker does not have direct
+			access.
+
+			This parameter controls the TAA mitigation.  The
+			options are:
+
+			full       - Enable TAA mitigation on vulnerable CPUs
+				     if TSX is enabled.
+
+			full,nosmt - Enable TAA mitigation and disable SMT on
+				     vulnerable CPUs. If TSX is disabled, SMT
+				     is not disabled because CPU is not
+				     vulnerable to cross-thread TAA attacks.
+			off        - Unconditionally disable TAA mitigation
+
+			On MDS-affected machines, tsx_async_abort=off can be
+			prevented by an active MDS mitigation as both vulnerabilities
+			are mitigated with the same mechanism so in order to disable
+			this mitigation, you need to specify mds=off too.
+
+			Not specifying this option is equivalent to
+			tsx_async_abort=full.  On CPUs which are MDS affected
+			and deploy MDS mitigation, TAA mitigation is not
+			required and doesn't provide any additional
+			mitigation.
+
+			For details see:
+			Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+
+	turbografx.map[2|3]=	[HW,JOY]
+			TurboGraFX parallel port interface
+			Format:
+			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
+			See also Documentation/input/devices/joystick-parport.rst
+
+	udbg-immortal	[PPC] When debugging early kernel crashes that
+			happen after console_init() and before a proper
+			console driver takes over, this boot options might
+			help "seeing" what's going on.
+
+	uhash_entries=	[KNL,NET]
+			Set number of hash buckets for UDP/UDP-Lite connections
+
+	uhci-hcd.ignore_oc=
+			[USB] Ignore overcurrent events (default N).
+			Some badly-designed motherboards generate lots of
+			bogus events, for ports that aren't wired to
+			anything.  Set this parameter to avoid log spamming.
+			Note that genuine overcurrent events won't be
+			reported either.
+
+	unaligned_scalar_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping scalar unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same scalar unaligned access speed.
+
+	unaligned_vector_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping vector unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same vector unaligned access speed.
+
+	unknown_nmi_panic
+			[X86] Cause panic on unknown NMI.
+
+	unwind_debug	[X86-64,EARLY]
+			Enable unwinder debug output.  This can be
+			useful for debugging certain unwinder error
+			conditions, including corrupt stacks and
+			bad/missing unwinder metadata.
+
+	usbcore.authorized_default=
+			[USB] Default USB device authorization:
+			(default -1 = authorized (same as 1),
+			0 = not authorized, 1 = authorized, 2 = authorized
+			if device connected to internal port)
+
+	usbcore.autosuspend=
+			[USB] The autosuspend time delay (in seconds) used
+			for newly-detected USB devices (default 2).  This
+			is the time required before an idle device will be
+			autosuspended.  Devices for which the delay is set
+			to a negative value won't be autosuspended at all.
+
+	usbcore.usbfs_snoop=
+			[USB] Set to log all usbfs traffic (default 0 = off).
+
+	usbcore.usbfs_snoop_max=
+			[USB] Maximum number of bytes to snoop in each URB
+			(default = 65536).
+
+	usbcore.blinkenlights=
+			[USB] Set to cycle leds on hubs (default 0 = off).
+
+	usbcore.old_scheme_first=
+			[USB] Start with the old device initialization
+			scheme (default 0 = off).
+
+	usbcore.usbfs_memory_mb=
+			[USB] Memory limit (in MB) for buffers allocated by
+			usbfs (default = 16, 0 = max = 2047).
+
+	usbcore.use_both_schemes=
+			[USB] Try the other device initialization scheme
+			if the first one fails (default 1 = enabled).
+
+	usbcore.initial_descriptor_timeout=
+			[USB] Specifies timeout for the initial 64-byte
+			USB_REQ_GET_DESCRIPTOR request in milliseconds
+			(default 5000 = 5.0 seconds).
+
+	usbcore.nousb	[USB] Disable the USB subsystem
+
+	usbcore.quirks=
+			[USB] A list of quirk entries to augment the built-in
+			usb core quirk list. List entries are separated by
+			commas. Each entry has the form
+			VendorID:ProductID:Flags. The IDs are 4-digit hex
+			numbers and Flags is a set of letters. Each letter
+			will change the built-in quirk; setting it if it is
+			clear and clearing it if it is set. The letters have
+			the following meanings:
+				a = USB_QUIRK_STRING_FETCH_255 (string
+					descriptors must not be fetched using
+					a 255-byte read);
+				b = USB_QUIRK_RESET_RESUME (device can't resume
+					correctly so reset it instead);
+				c = USB_QUIRK_NO_SET_INTF (device can't handle
+					Set-Interface requests);
+				d = USB_QUIRK_CONFIG_INTF_STRINGS (device can't
+					handle its Configuration or Interface
+					strings);
+				e = USB_QUIRK_RESET (device can't be reset
+					(e.g morph devices), don't use reset);
+				f = USB_QUIRK_HONOR_BNUMINTERFACES (device has
+					more interface descriptions than the
+					bNumInterfaces count, and can't handle
+					talking to these interfaces);
+				g = USB_QUIRK_DELAY_INIT (device needs a pause
+					during initialization, after we read
+					the device descriptor);
+				h = USB_QUIRK_LINEAR_UFRAME_INTR_BINTERVAL (For
+					high speed and super speed interrupt
+					endpoints, the USB 2.0 and USB 3.0 spec
+					require the interval in microframes (1
+					microframe = 125 microseconds) to be
+					calculated as interval = 2 ^
+					(bInterval-1).
+					Devices with this quirk report their
+					bInterval as the result of this
+					calculation instead of the exponent
+					variable used in the calculation);
+				i = USB_QUIRK_DEVICE_QUALIFIER (device can't
+					handle device_qualifier descriptor
+					requests);
+				j = USB_QUIRK_IGNORE_REMOTE_WAKEUP (device
+					generates spurious wakeup, ignore
+					remote wakeup capability);
+				k = USB_QUIRK_NO_LPM (device can't handle Link
+					Power Management);
+				l = USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL
+					(Device reports its bInterval as linear
+					frames instead of the USB 2.0
+					calculation);
+				m = USB_QUIRK_DISCONNECT_SUSPEND (Device needs
+					to be disconnected before suspend to
+					prevent spurious wakeup);
+				n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
+					pause after every control message);
+				o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
+					delay after resetting its port);
+				p = USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT
+					(Reduce timeout of the SET_ADDRESS
+					request from 5000 ms to 500 ms);
+				q = USB_QUIRK_FORCE_ONE_CONFIG (Device
+					claims zero configurations,
+					forcing to 1);
+				r = USB_QUIRK_WINDOWS_CONFIG_REQ_SIZE (Device
+					fails during initialization when asked for
+					9-bytes configuration descriptor request.
+					Ask for 255-bytes request instead to mirror
+					Windows' behavior);
+			Example: quirks=0781:5580:bk,0a5c:5834:gij
+
+	usbhid.mousepoll=
+			[USBHID] The interval which mice are to be polled at.
+
+	usbhid.jspoll=
+			[USBHID] The interval which joysticks are to be polled at.
+
+	usbhid.kbpoll=
+			[USBHID] The interval which keyboards are to be polled at.
+
+	usb-storage.delay_use=
+			[UMS] The delay in seconds before a new device is
+			scanned for Logical Units (default 1).
+			Optionally the delay in milliseconds if the value has
+			suffix with "ms".
+			Example: delay_use=2567ms
+
+	usb-storage.quirks=
+			[UMS] A list of quirks entries to supplement or
+			override the built-in unusual_devs list.  List
+			entries are separated by commas.  Each entry has
+			the form VID:PID:Flags where VID and PID are Vendor
+			and Product ID values (4-digit hex numbers) and
+			Flags is a set of characters, each corresponding
+			to a common usb-storage quirk flag as follows:
+				a = SANE_SENSE (collect more than 18 bytes
+					of sense data, not on uas);
+				b = BAD_SENSE (don't collect more than 18
+					bytes of sense data, not on uas);
+				c = FIX_CAPACITY (decrease the reported
+					device capacity by one sector);
+				d = NO_READ_DISC_INFO (don't use
+					READ_DISC_INFO command, not on uas);
+				e = NO_READ_CAPACITY_16 (don't use
+					READ_CAPACITY_16 command);
+				f = NO_REPORT_OPCODES (don't use report opcodes
+					command, uas only);
+				g = MAX_SECTORS_240 (don't transfer more than
+					240 sectors at a time, uas only);
+				h = CAPACITY_HEURISTICS (decrease the
+					reported device capacity by one
+					sector if the number is odd);
+				i = IGNORE_DEVICE (don't bind to this
+					device);
+				j = NO_REPORT_LUNS (don't use report luns
+					command, uas only);
+				k = NO_SAME (do not use WRITE_SAME, uas only)
+				l = NOT_LOCKABLE (don't try to lock and
+					unlock ejectable media, not on uas);
+				m = MAX_SECTORS_64 (don't transfer more
+					than 64 sectors = 32 KB at a time,
+					not on uas);
+				n = INITIAL_READ10 (force a retry of the
+					initial READ(10) command, not on uas);
+				o = CAPACITY_OK (accept the capacity
+					reported by the device, not on uas);
+				p = WRITE_CACHE (the device cache is ON
+					by default, not on uas);
+				r = IGNORE_RESIDUE (the device reports
+					bogus residue values, not on uas);
+				s = SINGLE_LUN (the device has only one
+					Logical Unit);
+				t = NO_ATA_1X (don't allow ATA(12) and ATA(16)
+					commands, uas only);
+				u = IGNORE_UAS (don't bind to the uas driver);
+				w = NO_WP_DETECT (don't test whether the
+					medium is write-protected).
+				y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE
+					even if the device claims no cache,
+					not on uas)
+			Example: quirks=0419:aaf5:rl,0421:0433:rc
+
+	user_debug=	[KNL,ARM]
+			Format: <int>
+			See arch/arm/Kconfig.debug help text.
+				 1 - undefined instruction events
+				 2 - system calls
+				 4 - invalid data aborts
+				 8 - SIGSEGV faults
+				16 - SIGBUS faults
+			Example: user_debug=31
+
+	vdso=		[X86,SH,SPARC]
+			On X86_32, this is an alias for vdso32=.  Otherwise:
+
+			vdso=1: enable VDSO (the default)
+			vdso=0: disable VDSO mapping
+
+	vdso32=		[X86] Control the 32-bit vDSO
+			vdso32=1: enable 32-bit VDSO
+			vdso32=0 or vdso32=2: disable 32-bit VDSO
+
+			See the help text for CONFIG_COMPAT_VDSO for more
+			details.  If CONFIG_COMPAT_VDSO is set, the default is
+			vdso32=0; otherwise, the default is vdso32=1.
+
+			For compatibility with older kernels, vdso32=2 is an
+			alias for vdso32=0.
+
+			Try vdso32=0 if you encounter an error that says:
+			dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
+
+	video=		[FB,EARLY] Frame buffer configuration
+			See Documentation/fb/modedb.rst.
+
+	video.brightness_switch_enabled= [ACPI]
+			Format: [0|1]
+			If set to 1, on receiving an ACPI notify event
+			generated by hotkey, video driver will adjust brightness
+			level and then send out the event to user space through
+			the allocated input device. If set to 0, video driver
+			will only send out the event without touching backlight
+			brightness level.
+			default: 1
+
+	virtio_mmio.device=
+			[VMMIO] Memory mapped virtio (platform) device.
+
+				<size>@<baseaddr>:<irq>[:<id>]
+			where:
+				<size>     := size (can use standard suffixes
+						like K, M and G)
+				<baseaddr> := physical base address
+				<irq>      := interrupt number (as passed to
+						request_irq())
+				<id>       := (optional) platform device id
+			example:
+				virtio_mmio.device=1K@0x100b0000:48:7
+
+			Can be used multiple times for multiple devices.
+
+	vga=		[BOOT,X86-32] Select a particular video mode
+			See Documentation/arch/x86/boot.rst and
+			Documentation/admin-guide/svga.rst.
+			Use vga=ask for menu.
+			This is actually a boot loader parameter; the value is
+			passed to the kernel using a special protocol.
+
+	vm_debug[=options]	[KNL] Available with CONFIG_DEBUG_VM=y.
+			May slow down system boot speed, especially when
+			enabled on systems with a large amount of memory.
+			All options are enabled by default, and this
+			interface is meant to allow for selectively
+			enabling or disabling specific virtual memory
+			debugging features.
+
+			Available options are:
+			  P	Enable page structure init time poisoning
+			  -	Disable all of the above options
+
+	vmalloc=nn[KMG]	[KNL,BOOT,EARLY] Forces the vmalloc area to have an
+			exact size of <nn>. This can be used to increase
+			the minimum size (128MB on x86, arm32 platforms).
+			It can also be used to decrease the size and leave more room
+			for directly mapped kernel RAM. Note that this parameter does
+			not exist on many other platforms (including arm64, alpha,
+			loongarch, arc, csky, hexagon, microblaze, mips, nios2, openrisc,
+			parisc, m64k, powerpc, riscv, sh, um, xtensa, s390, sparc).
+
+	vmcp_cma=nn[MG]	[KNL,S390,EARLY]
+			Sets the memory size reserved for contiguous memory
+			allocations for the vmcp device driver.
+
+	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
+			Format: <command>
+
+	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
+			Format: <command>
+
+	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
+			Format: <command>
+
+	vmscape=	[X86] Controls mitigation for VMscape attacks.
+			VMscape attacks can leak information from a userspace
+			hypervisor to a guest via speculative side-channels.
+
+			off		- disable the mitigation
+			ibpb		- use Indirect Branch Prediction Barrier
+					  (IBPB) mitigation (default)
+			force		- force vulnerability detection even on
+					  unaffected processors
+
+	vsyscall=	[X86-64,EARLY]
+			Controls the behavior of vsyscalls (i.e. calls to
+			fixed addresses of 0xffffffffff600x00 from legacy
+			code).  Most statically-linked binaries and older
+			versions of glibc use these calls.  Because these
+			functions are at fixed addresses, they make nice
+			targets for exploits that can control RIP.
+
+			emulate     Vsyscalls turn into traps and are emulated
+			            reasonably safely.  The vsyscall page is
+				    readable.  This disables the Linear
+				    Address Space Separation (LASS) security
+				    feature and makes the system less secure.
+
+			xonly       [default] Vsyscalls turn into traps and are
+			            emulated reasonably safely.  The vsyscall
+				    page is not readable.
+
+			none        Vsyscalls don't work at all.  This makes
+			            them quite hard to use for exploits but
+			            might break your system.
+
+	vt.color=	[VT] Default text color.
+			Format: 0xYX, X = foreground, Y = background.
+			Default: 0x07 = light gray on black.
+
+	vt.cur_default=	[VT] Default cursor shape.
+			Format: 0xCCBBAA, where AA, BB, and CC are the same as
+			the parameters of the <Esc>[?A;B;Cc escape sequence;
+			see vga-softcursor.rst. Default: 2 = underline.
+
+	vt.default_blu=	[VT]
+			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
+			Change the default blue palette of the console.
+			This is a 16-member array composed of values
+			ranging from 0-255.
+
+	vt.default_grn=	[VT]
+			Format: <green0>,<green1>,<green2>,...,<green15>
+			Change the default green palette of the console.
+			This is a 16-member array composed of values
+			ranging from 0-255.
+
+	vt.default_red=	[VT]
+			Format: <red0>,<red1>,<red2>,...,<red15>
+			Change the default red palette of the console.
+			This is a 16-member array composed of values
+			ranging from 0-255.
+
+	vt.default_utf8=
+			[VT]
+			Format=<0|1>
+			Set system-wide default UTF-8 mode for all tty's.
+			Default is 1, i.e. UTF-8 mode is enabled for all
+			newly opened terminals.
+
+	vt.global_cursor_default=
+			[VT]
+			Format=<-1|0|1>
+			Set system-wide default for whether a cursor
+			is shown on new VTs. Default is -1,
+			i.e. cursors will be created by default unless
+			overridden by individual drivers. 0 will hide
+			cursors, 1 will display them.
+
+	vt.italic=	[VT] Default color for italic text; 0-15.
+			Default: 2 = green.
+
+	vt.underline=	[VT] Default color for underlined text; 0-15.
+			Default: 3 = cyan.
+
+	watchdog timers	[HW,WDT] For information on watchdog timers,
+			see Documentation/watchdog/watchdog-parameters.rst
+			or other driver-specific files in the
+			Documentation/watchdog/ directory.
+
+	watchdog_thresh=
+			[KNL]
+			Set the hard lockup detector stall duration
+			threshold in seconds. The soft lockup detector
+			threshold is set to twice the value. A value of 0
+			disables both lockup detectors. Default is 10
+			seconds.
+
+	workqueue.unbound_cpus=
+			[KNL,SMP] Specify to constrain one or some CPUs
+			to use in unbound workqueues.
+			Format: <cpu-list>
+			By default, all online CPUs are available for
+			unbound workqueues.
+
+	workqueue.watchdog_thresh=
+			If CONFIG_WQ_WATCHDOG is configured, workqueue can
+			warn stall conditions and dump internal state to
+			help debugging.  0 disables workqueue stall
+			detection; otherwise, it's the stall threshold
+			duration in seconds.  The default value is 30 and
+			it can be updated at runtime by writing to the
+			corresponding sysfs file.
+
+	workqueue.panic_on_stall=<uint>
+			Panic when workqueue stall is detected by
+			CONFIG_WQ_WATCHDOG. It sets the number times of the
+			stall to trigger panic.
+
+			The default is set by CONFIG_BOOTPARAM_WQ_STALL_PANIC,
+			which is 0 (disabled) if not configured.
+
+	workqueue.panic_on_stall_time=<uint>
+			Panic when a workqueue stall has been continuous for
+			the specified number of seconds. Unlike panic_on_stall
+			which counts accumulated stall events, this triggers
+			based on the duration of a single continuous stall.
+
+			The default is 0, which disables the time-based panic.
+
+	workqueue.cpu_intensive_thresh_us=
+			Per-cpu work items which run for longer than this
+			threshold are automatically considered CPU intensive
+			and excluded from concurrency management to prevent
+			them from noticeably delaying other per-cpu work
+			items. Default is 10000 (10ms).
+
+			If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
+			will report the work functions which violate this
+			threshold repeatedly. They are likely good
+			candidates for using WQ_UNBOUND workqueues instead.
+
+	workqueue.cpu_intensive_warning_thresh=<uint>
+			If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel
+			will report the work functions which violate the
+			intensive_threshold_us repeatedly. In order to prevent
+			spurious warnings, start printing only after a work
+			function has violated this threshold number of times.
+
+			The default is 4 times. 0 disables the warning.
+
+	workqueue.power_efficient
+			Per-cpu workqueues are generally preferred because
+			they show better performance thanks to cache
+			locality; unfortunately, per-cpu workqueues tend to
+			be more power hungry than unbound workqueues.
+
+			Enabling this makes the per-cpu workqueues which
+			were observed to contribute significantly to power
+			consumption unbound, leading to measurably lower
+			power usage at the cost of small performance
+			overhead.
+
+			The default value of this parameter is determined by
+			the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT.
+
+        workqueue.default_affinity_scope=
+			Select the default affinity scope to use for unbound
+			workqueues. Can be one of "cpu", "smt", "cache",
+			"cache_shard", "numa" and "system". Default is
+			"cache_shard". For more
+			information, see the Affinity Scopes section in
+			Documentation/core-api/workqueue.rst.
+
+			This can be changed after boot by writing to the
+			matching /sys/module/workqueue/parameters file. All
+			workqueues with the "default" affinity scope will be
+			updated accordingly.
+
+	workqueue.debug_force_rr_cpu
+			Workqueue used to implicitly guarantee that work
+			items queued without explicit CPU specified are put
+			on the local CPU.  This guarantee is no longer true
+			and while local CPU is still preferred work items
+			may be put on foreign CPUs.  This debug option
+			forces round-robin CPU selection to flush out
+			usages which depend on the now broken guarantee.
+			When enabled, memory and cache locality will be
+			impacted.
+
+	writecombine=	[LOONGARCH,EARLY] Control the MAT (Memory Access
+			Type) of ioremap_wc().
+
+			on   - Enable writecombine, use WUC for ioremap_wc()
+			off  - Disable writecombine, use SUC for ioremap_wc()
+
+	x2apic_phys	[X86-64,APIC,EARLY] Use x2apic physical mode instead of
+			default x2apic cluster mode on platforms
+			supporting x2apic.
+
+	xen_512gb_limit		[KNL,X86-64,XEN]
+			Restricts the kernel running paravirtualized under Xen
+			to use only up to 512 GB of RAM. The reason to do so is
+			crash analysis tools and Xen tools for doing domain
+			save/restore/migration must be enabled to handle larger
+			domains.
+
+	xen_console_io	[XEN,EARLY]
+			Boolean option to enable/disable the usage of the Xen
+			console_io hypercalls to read and write to the console.
+			Mostly useful for debugging and development.
+
+	xen_emul_unplug=		[HW,X86,XEN,EARLY]
+			Unplug Xen emulated devices
+			Format: [unplug0,][unplug1]
+			ide-disks -- unplug primary master IDE devices
+			aux-ide-disks -- unplug non-primary-master IDE devices
+			nics -- unplug network devices
+			all -- unplug all emulated devices (NICs and IDE disks)
+			unnecessary -- unplugging emulated devices is
+				unnecessary even if the host did not respond to
+				the unplug protocol
+			never -- do not unplug even if version check succeeds
+
+	xen_legacy_crash	[X86,XEN,EARLY]
+			Crash from Xen panic notifier, without executing late
+			panic() code such as dumping handler.
+
+	xen_mc_debug	[X86,XEN,EARLY]
+			Enable multicall debugging when running as a Xen PV guest.
+			Enabling this feature will reduce performance a little
+			bit, so it should only be enabled for obtaining extended
+			debug data in case of multicall errors.
+
+	xen_msr_safe=	[X86,XEN,EARLY]
+			Format: <bool>
+			Select whether to always use non-faulting (safe) MSR
+			access functions when running as Xen PV guest. The
+			default value is controlled by CONFIG_XEN_PV_MSR_SAFE.
+
+	xen_nopv	[X86]
+			Disables the PV optimizations forcing the HVM guest to
+			run as generic HVM guest with no PV drivers.
+			This option is obsoleted by the "nopv" option, which
+			has equivalent effect for XEN platform.
+
+	xen_no_vector_callback
+			[KNL,X86,XEN,EARLY] Disable the vector callback for Xen
+			event channel interrupts.
+
+	xen_scrub_pages=	[XEN]
+			Boolean option to control scrubbing pages before giving them back
+			to Xen, for use by other domains. Can be also changed at runtime
+			with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
+			Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
+
+	xen_timer_slop=	[X86-64,XEN,EARLY]
+			Set the timer slop (in nanoseconds) for the virtual Xen
+			timers (default is 100000). This adjusts the minimum
+			delta of virtualized Xen timers, where lower values
+			improve timer resolution at the expense of processing
+			more timer interrupts.
+
+	xen.balloon_boot_timeout= [XEN]
+			The time (in seconds) to wait before giving up to boot
+			in case initial ballooning fails to free enough memory.
+			Applies only when running as HVM or PVH guest and
+			started with less memory configured than allowed at
+			max. Default is 180.
+
+	xen.event_eoi_delay=	[XEN]
+			How long to delay EOI handling in case of event
+			storms (jiffies). Default is 10.
+
+	xen.event_loop_timeout=	[XEN]
+			After which time (jiffies) the event handling loop
+			should start to delay EOI handling. Default is 2.
+
+	xen.fifo_events=	[XEN]
+			Boolean parameter to disable using fifo event handling
+			even if available. Normally fifo event handling is
+			preferred over the 2-level event handling, as it is
+			fairer and the number of possible event channels is
+			much higher. Default is on (use fifo events).
+
+	xirc2ps_cs=	[NET,PCMCIA]
+			Format:
+			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
+
+	xive=		[PPC]
+			By default on POWER9 and above, the kernel will
+			natively use the XIVE interrupt controller. This option
+			allows the fallback firmware mode to be used:
+
+			off       Fallback to firmware control of XIVE interrupt
+				  controller on both pseries and powernv
+				  platforms. Only useful on POWER9 and above.
+
+	xive.store-eoi=off	[PPC]
+			By default on POWER10 and above, the kernel will use
+			stores for EOI handling when the XIVE interrupt mode
+			is active. This option allows the XIVE driver to use
+			loads instead, as on POWER9.
+
+	xhci-hcd.quirks		[USB,KNL]
+			A hex value specifying bitmask with supplemental xhci
+			host controller quirks. Meaning of each bit can be
+			consulted in header drivers/usb/host/xhci.h.
+
+	xmon		[PPC,EARLY]
+			Format: { early | on | rw | ro | off }
+			Controls if xmon debugger is enabled. Default is off.
+			Passing only "xmon" is equivalent to "xmon=early".
+			early	Call xmon as early as possible on boot; xmon
+				debugger is called from setup_arch().
+			on	xmon debugger hooks will be installed so xmon
+				is only called on a kernel crash. Default mode,
+				i.e. either "ro" or "rw" mode, is controlled
+				with CONFIG_XMON_DEFAULT_RO_MODE.
+			rw	xmon debugger hooks will be installed so xmon
+				is called only on a kernel crash, mode is write,
+				meaning SPR registers, memory and, other data
+				can be written using xmon commands.
+			ro 	same as "rw" option above but SPR registers,
+				memory, and other data can't be written using
+				xmon commands.
+			off	xmon is disabled.
diff --git a/Documentation/admin-guide/kernel-per-CPU-kthreads.rst b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
new file mode 100644
index 000000000..ee9a6c94f
--- /dev/null
+++ b/Documentation/admin-guide/kernel-per-CPU-kthreads.rst
@@ -0,0 +1,325 @@
+==========================================
+Reducing OS jitter due to per-cpu kthreads
+==========================================
+
+This document lists per-CPU kthreads in the Linux kernel and presents
+options to control their OS jitter.  Note that non-per-CPU kthreads are
+not listed here.  To reduce OS jitter from non-per-CPU kthreads, bind
+them to a "housekeeping" CPU dedicated to such work.
+
+References
+==========
+
+-	Documentation/core-api/irq/irq-affinity.rst:  Binding interrupts to sets of CPUs.
+
+-	Documentation/admin-guide/cgroup-v1:  Using cgroups to bind tasks to sets of CPUs.
+
+-	man taskset:  Using the taskset command to bind tasks to sets
+	of CPUs.
+
+-	man sched_setaffinity:  Using the sched_setaffinity() system
+	call to bind tasks to sets of CPUs.
+
+-	/sys/devices/system/cpu/cpuN/online:  Control CPU N's hotplug state,
+	writing "0" to offline and "1" to online.
+
+-	In order to locate kernel-generated OS jitter on CPU N:
+
+		cd /sys/kernel/tracing
+		echo 1 > max_graph_depth # Increase the "1" for more detail
+		echo function_graph > current_tracer
+		# run workload
+		cat per_cpu/cpuN/trace
+
+kthreads
+========
+
+Name:
+  ehca_comp/%u
+
+Purpose:
+  Periodically process Infiniband-related work.
+
+To reduce its OS jitter, do any of the following:
+
+1.	Don't use eHCA Infiniband hardware, instead choosing hardware
+	that does not require per-CPU kthreads.  This will prevent these
+	kthreads from being created in the first place.  (This will
+	work for most people, as this hardware, though important, is
+	relatively old and is produced in relatively low unit volumes.)
+2.	Do all eHCA-Infiniband-related work on other CPUs, including
+	interrupts.
+3.	Rework the eHCA driver so that its per-CPU kthreads are
+	provisioned only on selected CPUs.
+
+
+Name:
+  irq/%d-%s
+
+Purpose:
+  Handle threaded interrupts.
+
+To reduce its OS jitter, do the following:
+
+1.	Use irq affinity to force the irq threads to execute on
+	some other CPU.
+
+Name:
+  kcmtpd_ctr_%d
+
+Purpose:
+  Handle Bluetooth work.
+
+To reduce its OS jitter, do one of the following:
+
+1.	Don't use Bluetooth, in which case these kthreads won't be
+	created in the first place.
+2.	Use irq affinity to force Bluetooth-related interrupts to
+	occur on some other CPU and furthermore initiate all
+	Bluetooth activity on some other CPU.
+
+Name:
+  ksoftirqd/%u
+
+Purpose:
+  Execute softirq handlers when threaded or when under heavy load.
+
+To reduce its OS jitter, each softirq vector must be handled
+separately as follows:
+
+TIMER_SOFTIRQ
+-------------
+
+Do all of the following:
+
+1.	To the extent possible, keep the CPU out of the kernel when it
+	is non-idle, for example, by avoiding system calls and by forcing
+	both kernel threads and interrupts to execute elsewhere.
+2.	Build with CONFIG_HOTPLUG_CPU=y.  After boot completes, force
+	the CPU offline, then bring it back online.  This forces
+	recurring timers to migrate elsewhere.	If you are concerned
+	with multiple CPUs, force them all offline before bringing the
+	first one back online.  Once you have onlined the CPUs in question,
+	do not offline any other CPUs, because doing so could force the
+	timer back onto one of the CPUs in question.
+
+NET_TX_SOFTIRQ and NET_RX_SOFTIRQ
+---------------------------------
+
+Do all of the following:
+
+1.	Force networking interrupts onto other CPUs.
+2.	Initiate any network I/O on other CPUs.
+3.	Once your application has started, prevent CPU-hotplug operations
+	from being initiated from tasks that might run on the CPU to
+	be de-jittered.  (It is OK to force this CPU offline and then
+	bring it back online before you start your application.)
+
+BLOCK_SOFTIRQ
+-------------
+
+Do all of the following:
+
+1.	Force block-device interrupts onto some other CPU.
+2.	Initiate any block I/O on other CPUs.
+3.	Once your application has started, prevent CPU-hotplug operations
+	from being initiated from tasks that might run on the CPU to
+	be de-jittered.  (It is OK to force this CPU offline and then
+	bring it back online before you start your application.)
+
+IRQ_POLL_SOFTIRQ
+----------------
+
+Do all of the following:
+
+1.	Force block-device interrupts onto some other CPU.
+2.	Initiate any block I/O and block-I/O polling on other CPUs.
+3.	Once your application has started, prevent CPU-hotplug operations
+	from being initiated from tasks that might run on the CPU to
+	be de-jittered.  (It is OK to force this CPU offline and then
+	bring it back online before you start your application.)
+
+TASKLET_SOFTIRQ
+---------------
+
+Do one or more of the following:
+
+1.	Avoid use of drivers that use tasklets.  (Such drivers will contain
+	calls to things like tasklet_schedule().)
+2.	Convert all drivers that you must use from tasklets to workqueues.
+3.	Force interrupts for drivers using tasklets onto other CPUs,
+	and also do I/O involving these drivers on other CPUs.
+
+SCHED_SOFTIRQ
+-------------
+
+Do all of the following:
+
+1.	Avoid sending scheduler IPIs to the CPU to be de-jittered,
+	for example, ensure that at most one runnable kthread is present
+	on that CPU.  If a thread that expects to run on the de-jittered
+	CPU awakens, the scheduler will send an IPI that can result in
+	a subsequent SCHED_SOFTIRQ.
+2.	CONFIG_NO_HZ_FULL=y and ensure that the CPU to be de-jittered
+	is marked as an adaptive-ticks CPU using the "nohz_full="
+	boot parameter.  This reduces the number of scheduler-clock
+	interrupts that the de-jittered CPU receives, minimizing its
+	chances of being selected to do the load balancing work that
+	runs in SCHED_SOFTIRQ context.
+3.	To the extent possible, keep the CPU out of the kernel when it
+	is non-idle, for example, by avoiding system calls and by
+	forcing both kernel threads and interrupts to execute elsewhere.
+	This further reduces the number of scheduler-clock interrupts
+	received by the de-jittered CPU.
+
+HRTIMER_SOFTIRQ
+---------------
+
+Do all of the following:
+
+1.	To the extent possible, keep the CPU out of the kernel when it
+	is non-idle.  For example, avoid system calls and force both
+	kernel threads and interrupts to execute elsewhere.
+2.	Build with CONFIG_HOTPLUG_CPU=y.  Once boot completes, force the
+	CPU offline, then bring it back online.  This forces recurring
+	timers to migrate elsewhere.  If you are concerned with multiple
+	CPUs, force them all offline before bringing the first one
+	back online.  Once you have onlined the CPUs in question, do not
+	offline any other CPUs, because doing so could force the timer
+	back onto one of the CPUs in question.
+
+RCU_SOFTIRQ
+-----------
+
+Do at least one of the following:
+
+1.	Offload callbacks and keep the CPU in either dyntick-idle or
+	adaptive-ticks state by doing all of the following:
+
+	a.	CONFIG_NO_HZ_FULL=y and ensure that the CPU to be
+		de-jittered is marked as an adaptive-ticks CPU using the
+		"nohz_full=" boot parameter.  Bind the rcuo kthreads to
+		housekeeping CPUs, which can tolerate OS jitter.
+	b.	To the extent possible, keep the CPU out of the kernel
+		when it is non-idle, for example, by avoiding system
+		calls and by forcing both kernel threads and interrupts
+		to execute elsewhere.
+
+2.	Enable RCU to do its processing remotely via dyntick-idle by
+	doing all of the following:
+
+	a.	Build with CONFIG_NO_HZ=y.
+	b.	Ensure that the CPU goes idle frequently, allowing other
+		CPUs to detect that it has passed through an RCU quiescent
+		state.	If the kernel is built with CONFIG_NO_HZ_FULL=y,
+		userspace execution also allows other CPUs to detect that
+		the CPU in question has passed through a quiescent state.
+	c.	To the extent possible, keep the CPU out of the kernel
+		when it is non-idle, for example, by avoiding system
+		calls and by forcing both kernel threads and interrupts
+		to execute elsewhere.
+
+Name:
+  kworker/%u:%d%s (cpu, id, priority)
+
+Purpose:
+  Execute workqueue requests
+
+To reduce its OS jitter, do any of the following:
+
+1.	Run your workload at a real-time priority, which will allow
+	preempting the kworker daemons.
+2.	A given workqueue can be made visible in the sysfs filesystem
+	by passing the WQ_SYSFS to that workqueue's alloc_workqueue().
+	Such a workqueue can be confined to a given subset of the
+	CPUs using the ``/sys/devices/virtual/workqueue/*/cpumask`` sysfs
+	files.	The set of WQ_SYSFS workqueues can be displayed using
+	"ls /sys/devices/virtual/workqueue".  That said, the workqueues
+	maintainer would like to caution people against indiscriminately
+	sprinkling WQ_SYSFS across all the workqueues.	The reason for
+	caution is that it is easy to add WQ_SYSFS, but because sysfs is
+	part of the formal user/kernel API, it can be nearly impossible
+	to remove it, even if its addition was a mistake.
+3.	Do any of the following needed to avoid jitter that your
+	application cannot tolerate:
+
+	a.	Avoid using oprofile, thus avoiding OS jitter from
+		wq_sync_buffer().
+	b.	Limit your CPU frequency so that a CPU-frequency
+		governor is not required, possibly enlisting the aid of
+		special heatsinks or other cooling technologies.  If done
+		correctly, and if you CPU architecture permits, you should
+		be able to build your kernel with CONFIG_CPU_FREQ=n to
+		avoid the CPU-frequency governor periodically running
+		on each CPU, including cs_dbs_timer() and od_dbs_timer().
+
+		WARNING:  Please check your CPU specifications to
+		make sure that this is safe on your particular system.
+	c.	As of v3.18, Christoph Lameter's on-demand vmstat workers
+		commit prevents OS jitter due to vmstat_update() on
+		CONFIG_SMP=y systems.  Before v3.18, is not possible
+		to entirely get rid of the OS jitter, but you can
+		decrease its frequency by writing a large value to
+		/proc/sys/vm/stat_interval.  The default value is HZ,
+		for an interval of one second.	Of course, larger values
+		will make your virtual-memory statistics update more
+		slowly.  Of course, you can also run your workload at
+		a real-time priority, thus preempting vmstat_update(),
+		but if your workload is CPU-bound, this is a bad idea.
+		However, there is an RFC patch from Christoph Lameter
+		(based on an earlier one from Gilad Ben-Yossef) that
+		reduces or even eliminates vmstat overhead for some
+		workloads at https://lore.kernel.org/r/00000140e9dfd6bd-40db3d4f-c1be-434f-8132-7820f81bb586-000000@email.amazonses.com.
+	d.	If running on high-end powerpc servers, build with
+		CONFIG_PPC_RTAS_DAEMON=n.  This prevents the RTAS
+		daemon from running on each CPU every second or so.
+		(This will require editing Kconfig files and will defeat
+		this platform's RAS functionality.)  This avoids jitter
+		due to the rtas_event_scan() function.
+		WARNING:  Please check your CPU specifications to
+		make sure that this is safe on your particular system.
+	e.	If running on PowerMAC, build your kernel with
+		CONFIG_PMAC_RACKMETER=n to disable the CPU-meter,
+		avoiding OS jitter from rackmeter_do_timer().
+
+Name:
+  rcuc/%u
+
+Purpose:
+  Execute RCU callbacks in CONFIG_RCU_BOOST=y kernels.
+
+To reduce its OS jitter, do at least one of the following:
+
+1.	Build the kernel with CONFIG_PREEMPT=n.  This prevents these
+	kthreads from being created in the first place, and also obviates
+	the need for RCU priority boosting.  This approach is feasible
+	for workloads that do not require high degrees of responsiveness.
+2.	Build the kernel with CONFIG_RCU_BOOST=n.  This prevents these
+	kthreads from being created in the first place.  This approach
+	is feasible only if your workload never requires RCU priority
+	boosting, for example, if you ensure frequent idle time on all
+	CPUs that might execute within the kernel.
+3.	Build with CONFIG_RCU_NOCB_CPU=y and boot with the rcu_nocbs=
+	boot parameter offloading RCU callbacks from all CPUs susceptible
+	to OS jitter.  This approach prevents the rcuc/%u kthreads from
+	having any work to do, so that they are never awakened.
+4.	Ensure that the CPU never enters the kernel, and, in particular,
+	avoid initiating any CPU hotplug operations on this CPU.  This is
+	another way of preventing any callbacks from being queued on the
+	CPU, again preventing the rcuc/%u kthreads from having any work
+	to do.
+
+Name:
+  rcuop/%d, rcuos/%d, and rcuog/%d
+
+Purpose:
+  Offload RCU callbacks from the corresponding CPU.
+
+To reduce its OS jitter, do at least one of the following:
+
+1.	Use affinity, cgroups, or other mechanism to force these kthreads
+	to execute on some other CPU.
+2.	Build with CONFIG_RCU_NOCB_CPU=n, which will prevent these
+	kthreads from being created in the first place.  However, please
+	note that this will not eliminate OS jitter, but will instead
+	shift it to RCU_SOFTIRQ.
diff --git a/Documentation/admin-guide/laptops/alienware-wmi.rst b/Documentation/admin-guide/laptops/alienware-wmi.rst
new file mode 100644
index 000000000..e532c60db
--- /dev/null
+++ b/Documentation/admin-guide/laptops/alienware-wmi.rst
@@ -0,0 +1,127 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+====================
+Alienware WMI Driver
+====================
+
+Kurt Borja <kuurtb@gmail.com>
+
+This is a driver for the "WMAX" WMI device, which is found in most Dell gaming
+laptops and controls various special features.
+
+Before the launch of M-Series laptops (~2018), the "WMAX" device controlled
+basic RGB lighting, deep sleep mode, HDMI mode and amplifier status.
+
+Later, this device was completely repurpused. Now it mostly deals with thermal
+profiles, sensor monitoring and overclocking. This interface is named "AWCC" and
+is known to be used by the AWCC OEM application to control these features.
+
+The alienware-wmi driver controls both interfaces.
+
+AWCC Interface
+==============
+
+WMI device documentation: Documentation/wmi/devices/alienware-wmi.rst
+
+Supported devices
+-----------------
+
+- Alienware M-Series laptops
+- Alienware X-Series laptops
+- Alienware Aurora Desktops
+- Dell G-Series laptops
+
+If you believe your device supports the AWCC interface and you don't have any of
+the features described in this document, try the following alienware-wmi module
+parameters:
+
+- ``force_platform_profile=1``: Forces probing for platform profile support
+- ``force_hwmon=1``: Forces probing for HWMON support
+
+If the module loads successfully with these parameters, consider submitting a
+patch adding your model to the ``awcc_dmi_table`` located in
+``drivers/platform/x86/dell/alienware-wmi-wmax.c`` or contacting the maintainer
+for further guidance.
+
+Status
+------
+
+The following features are currently supported:
+
+- :ref:`Platform Profile <platform-profile>`:
+
+  - Thermal profile control
+
+  - G-Mode toggling
+
+- :ref:`HWMON <hwmon>`:
+
+  - Sensor monitoring
+
+  - Manual fan control
+
+.. _platform-profile:
+
+Platform Profile
+----------------
+
+The AWCC interface exposes various firmware defined thermal profiles. These are
+exposed to user-space through the Platform Profile class interface. Refer to
+:ref:`sysfs-class-platform-profile <abi_file_testing_sysfs_class_platform_profile>`
+for more information.
+
+The name of the platform-profile class device exported by this driver is
+"alienware-wmi" and it's path can be found with:
+
+::
+
+ grep -l "alienware-wmi" /sys/class/platform-profile/platform-profile-*/name | sed 's|/[^/]*$||'
+
+If the device supports G-Mode, it is also toggled when selecting the
+``performance`` profile.
+
+.. note::
+   You may set the ``force_gmode`` module parameter to always try to toggle this
+   feature, without checking if your model supports it.
+
+.. _hwmon:
+
+HWMON
+-----
+
+The AWCC interface also supports sensor monitoring and manual fan control. Both
+of these features are exposed to user-space through the HWMON interface.
+
+The name of the hwmon class device exported by this driver is "alienware_wmi"
+and it's path can be found with:
+
+::
+
+ grep -l "alienware_wmi" /sys/class/hwmon/hwmon*/name | sed 's|/[^/]*$||'
+
+Sensor monitoring is done through the standard HWMON interface. Refer to
+:ref:`sysfs-class-hwmon <abi_file_testing_sysfs_class_hwmon>` for more
+information.
+
+Manual fan control on the other hand, is not exposed directly by the AWCC
+interface. Instead it let's us control a fan `boost` value. This `boost` value
+has the following approximate behavior over the fan pwm:
+
+::
+
+ pwm = pwm_base + (fan_boost / 255) * (pwm_max - pwm_base)
+
+Due to the above behavior, the fan `boost` control is exposed to user-space
+through the following, custom hwmon sysfs attribute:
+
+=============================== ======= =======================================
+Name				Perm	Description
+=============================== ======= =======================================
+fan[1-4]_boost			RW	Fan boost value.
+
+					Integer value between 0 and 255
+=============================== ======= =======================================
+
+.. note::
+   In some devices, manual fan control only works reliably if the ``custom``
+   platform profile is selected.
diff --git a/Documentation/admin-guide/laptops/asus-laptop.rst b/Documentation/admin-guide/laptops/asus-laptop.rst
new file mode 100644
index 000000000..95176321a
--- /dev/null
+++ b/Documentation/admin-guide/laptops/asus-laptop.rst
@@ -0,0 +1,271 @@
+==================
+Asus Laptop Extras
+==================
+
+Version 0.1
+
+August 6, 2009
+
+Corentin Chary <corentincj@iksaif.net>
+http://acpi4asus.sf.net/
+
+ This driver provides support for extra features of ACPI-compatible ASUS laptops.
+ It may also support some MEDION, JVC or VICTOR laptops (such as MEDION 9675 or
+ VICTOR XP7210 for example). It makes all the extra buttons generate input
+ events (like keyboards).
+
+ On some models adds support for changing the display brightness and output,
+ switching the LCD backlight on and off, and most importantly, allows you to
+ blink those fancy LEDs intended for reporting mail and wireless status.
+
+This driver supersedes the old asus_acpi driver.
+
+Requirements
+------------
+
+  Kernel 2.6.X sources, configured for your computer, with ACPI support.
+  You also need CONFIG_INPUT and CONFIG_ACPI.
+
+Status
+------
+
+ The features currently supported are the following (see below for
+ detailed description):
+
+ - Fn key combinations
+ - Bluetooth enable and disable
+ - Wlan enable and disable
+ - GPS enable and disable
+ - Video output switching
+ - Ambient Light Sensor on and off
+ - LED control
+ - LED Display control
+ - LCD brightness control
+ - LCD on and off
+
+ A compatibility table by model and feature is maintained on the web
+ site, http://acpi4asus.sf.net/.
+
+Usage
+-----
+
+  Try "modprobe asus-laptop". Check your dmesg (simply type dmesg). You should
+  see some lines like this :
+
+      Asus Laptop Extras version 0.42
+        - L2D model detected.
+
+  If it is not the output you have on your laptop, send it (and the laptop's
+  DSDT) to me.
+
+  That's all, now, all the events generated by the hotkeys of your laptop
+  should be reported via netlink events. You can check with
+  "acpi_genl monitor" (part of the acpica project).
+
+  Hotkeys are also reported as input keys (like keyboards) you can check
+  which key are supported using "xev" under X11.
+
+  You can get information on the version of your DSDT table by reading the
+  /sys/devices/platform/asus-laptop/infos entry. If you have a question or a
+  bug report to do, please include the output of this entry.
+
+LEDs
+----
+
+  You can modify LEDs be echoing values to `/sys/class/leds/asus/*/brightness`::
+
+    echo 1 >  /sys/class/leds/asus::mail/brightness
+
+  will switch the mail LED on.
+
+  You can also know if they are on/off by reading their content and use
+  kernel triggers like disk-activity or heartbeat.
+
+Backlight
+---------
+
+  You can control lcd backlight power and brightness with
+  /sys/class/backlight/asus-laptop/. Brightness Values are between 0 and 15.
+
+Wireless devices
+----------------
+
+  You can turn the internal Bluetooth adapter on/off with the bluetooth entry
+  (only on models with Bluetooth). This usually controls the associated LED.
+  Same for Wlan adapter.
+
+Display switching
+-----------------
+
+  Note: the display switching code is currently considered EXPERIMENTAL.
+
+  Switching works for the following models:
+
+    - L3800C
+    - A2500H
+    - L5800C
+    - M5200N
+    - W1000N (albeit with some glitches)
+    - M6700R
+    - A6JC
+    - F3J
+
+  Switching doesn't work for the following:
+
+    - M3700N
+    - L2X00D (locks the laptop under certain conditions)
+
+  To switch the displays, echo values from 0 to 15 to
+  /sys/devices/platform/asus-laptop/display. The significance of those values
+  is as follows:
+
+  +-------+-----+-----+-----+-----+-----+
+  | Bin   | Val | DVI | TV  | CRT | LCD |
+  +-------+-----+-----+-----+-----+-----+
+  | 0000  |   0 |     |     |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0001  |   1 |     |     |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 0010  |   2 |     |     |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0011  |   3 |     |     |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 0100  |   4 |     |  X  |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0101  |   5 |     |  X  |     | X   |
+  +-------+-----+-----+-----+-----+-----+
+  | 0110  |   6 |     |  X  |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 0111  |   7 |     |  X  |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1000  |   8 |  X  |     |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1001  |   9 |  X  |     |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1010  |  10 |  X  |     |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1011  |  11 |  X  |     |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1100  |  12 |  X  |  X  |     |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1101  |  13 |  X  |  X  |     |  X  |
+  +-------+-----+-----+-----+-----+-----+
+  | 1110  |  14 |  X  |  X  |  X  |     |
+  +-------+-----+-----+-----+-----+-----+
+  | 1111  |  15 |  X  |  X  |  X  |  X  |
+  +-------+-----+-----+-----+-----+-----+
+
+  In most cases, the appropriate displays must be plugged in for the above
+  combinations to work. TV-Out may need to be initialized at boot time.
+
+  Debugging:
+
+  1) Check whether the Fn+F8 key:
+
+     a) does not lock the laptop (try a boot with noapic / nolapic if it does)
+     b) generates events (0x6n, where n is the value corresponding to the
+        configuration above)
+     c) actually works
+
+     Record the disp value at every configuration.
+  2) Echo values from 0 to 15 to /sys/devices/platform/asus-laptop/display.
+     Record its value, note any change. If nothing changes, try a broader range,
+     up to 65535.
+  3) Send ANY output (both positive and negative reports are needed, unless your
+     machine is already listed above) to the acpi4asus-user mailing list.
+
+  Note: on some machines (e.g. L3C), after the module has been loaded, only 0x6n
+  events are generated and no actual switching occurs. In such a case, a line
+  like::
+
+    echo $((10#$arg-60)) > /sys/devices/platform/asus-laptop/display
+
+  will usually do the trick ($arg is the 0000006n-like event passed to acpid).
+
+  Note: there is currently no reliable way to read display status on xxN
+  (Centrino) models.
+
+LED display
+-----------
+
+  Some models like the W1N have a LED display that can be used to display
+  several items of information.
+
+  LED display works for the following models:
+
+    - W1000N
+    - W1J
+
+  To control the LED display, use the following::
+
+    echo 0x0T000DDD > /sys/devices/platform/asus-laptop/
+
+  where T control the 3 letters display, and DDD the 3 digits display,
+  according to the tables below::
+
+         DDD (digits)
+         000 to 999 = display digits
+         AAA        = ---
+         BBB to FFF = turn-off
+
+         T  (type)
+         0 = off
+         1 = dvd
+         2 = vcd
+         3 = mp3
+         4 = cd
+         5 = tv
+         6 = cpu
+         7 = vol
+
+  For example "echo 0x01000001 >/sys/devices/platform/asus-laptop/ledd"
+  would display "DVD001".
+
+Driver options
+--------------
+
+ Options can be passed to the asus-laptop driver using the standard
+ module argument syntax (<param>=<value> when passing the option to the
+ module or asus-laptop.<param>=<value> on the kernel boot line when
+ asus-laptop is statically linked into the kernel).
+
+	     wapf: WAPF defines the behavior of the Fn+Fx wlan key
+		   The significance of values is yet to be found, but
+		   most of the time:
+
+		   - 0x0 should do nothing
+		   - 0x1 should allow to control the device with Fn+Fx key.
+		   - 0x4 should send an ACPI event (0x88) while pressing the Fn+Fx key
+		   - 0x5 like 0x1 or 0x4
+
+ The default value is 0x1.
+
+Unsupported models
+------------------
+
+ These models will never be supported by this module, as they use a completely
+ different mechanism to handle LEDs and extra stuff (meaning we have no clue
+ how it works):
+
+ - ASUS A1300 (A1B), A1370D
+ - ASUS L7300G
+ - ASUS L8400
+
+Patches, Errors, Questions
+--------------------------
+
+ I appreciate any success or failure
+ reports, especially if they add to or correct the compatibility table.
+ Please include the following information in your report:
+
+ - Asus model name
+ - a copy of your ACPI tables, using the "acpidump" utility
+ - a copy of /sys/devices/platform/asus-laptop/infos
+ - which driver features work and which don't
+ - the observed behavior of non-working features
+
+ Any other comments or patches are also more than welcome.
+
+ acpi4asus-user@lists.sourceforge.net
+
+ http://sourceforge.net/projects/acpi4asus
diff --git a/Documentation/admin-guide/laptops/disk-shock-protection.rst b/Documentation/admin-guide/laptops/disk-shock-protection.rst
new file mode 100644
index 000000000..22c7ec3e8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/disk-shock-protection.rst
@@ -0,0 +1,151 @@
+==========================
+Hard disk shock protection
+==========================
+
+Author: Elias Oltmanns <eo@nebensachen.de>
+
+Last modified: 2008-10-03
+
+
+.. 0. Contents
+
+   1. Intro
+   2. The interface
+   3. References
+   4. CREDITS
+
+
+1. Intro
+--------
+
+ATA/ATAPI-7 specifies the IDLE IMMEDIATE command with unload feature.
+Issuing this command should cause the drive to switch to idle mode and
+unload disk heads. This feature is being used in modern laptops in
+conjunction with accelerometers and appropriate software to implement
+a shock protection facility. The idea is to stop all I/O operations on
+the internal hard drive and park its heads on the ramp when critical
+situations are anticipated. The desire to have such a feature
+available on GNU/Linux systems has been the original motivation to
+implement a generic disk head parking interface in the Linux kernel.
+Please note, however, that other components have to be set up on your
+system in order to get disk shock protection working (see
+section 3. References below for pointers to more information about
+that).
+
+
+2. The interface
+----------------
+
+For each ATA device, the kernel exports the file
+`block/*/device/unload_heads` in sysfs (here assumed to be mounted under
+/sys). Access to `/sys/block/*/device/unload_heads` is denied with
+-EOPNOTSUPP if the device does not support the unload feature.
+Otherwise, writing an integer value to this file will take the heads
+of the respective drive off the platter and block all I/O operations
+for the specified number of milliseconds. When the timeout expires and
+no further disk head park request has been issued in the meantime,
+normal operation will be resumed. The maximal value accepted for a
+timeout is 30000 milliseconds. Exceeding this limit will return
+-EOVERFLOW, but heads will be parked anyway and the timeout will be
+set to 30 seconds. However, you can always change a timeout to any
+value between 0 and 30000 by issuing a subsequent head park request
+before the timeout of the previous one has expired. In particular, the
+total timeout can exceed 30 seconds and, more importantly, you can
+cancel a previously set timeout and resume normal operation
+immediately by specifying a timeout of 0. Values below -2 are rejected
+with -EINVAL (see below for the special meaning of -1 and -2). If the
+timeout specified for a recent head park request has not yet expired,
+reading from `/sys/block/*/device/unload_heads` will report the number
+of milliseconds remaining until normal operation will be resumed;
+otherwise, reading the unload_heads attribute will return 0.
+
+For example, do the following in order to park the heads of drive
+/dev/sda and stop all I/O operations for five seconds::
+
+	# echo 5000 > /sys/block/sda/device/unload_heads
+
+A simple::
+
+	# cat /sys/block/sda/device/unload_heads
+
+will show you how many milliseconds are left before normal operation
+will be resumed.
+
+A word of caution: The fact that the interface operates on a basis of
+milliseconds may raise expectations that cannot be satisfied in
+reality. In fact, the ATA specs clearly state that the time for an
+unload operation to complete is vendor specific. The hint in ATA-7
+that this will typically be within 500 milliseconds apparently has
+been dropped in ATA-8.
+
+There is a technical detail of this implementation that may cause some
+confusion and should be discussed here. When a head park request has
+been issued to a device successfully, all I/O operations on the
+controller port this device is attached to will be deferred. That is
+to say, any other device that may be connected to the same port will
+be affected too. The only exception is that a subsequent head unload
+request to that other device will be executed immediately. Further
+operations on that port will be deferred until the timeout specified
+for either device on the port has expired. As far as PATA (old style
+IDE) configurations are concerned, there can only be two devices
+attached to any single port. In SATA world we have port multipliers
+which means that a user-issued head parking request to one device may
+actually result in stopping I/O to a whole bunch of devices. However,
+since this feature is supposed to be used on laptops and does not seem
+to be very useful in any other environment, there will be mostly one
+device per port. Even if the CD/DVD writer happens to be connected to
+the same port as the hard drive, it generally *should* recover just
+fine from the occasional buffer under-run incurred by a head park
+request to the HD. Actually, when you are using an ide driver rather
+than its libata counterpart (i.e. your disk is called /dev/hda
+instead of /dev/sda), then parking the heads of one drive (drive X)
+will generally not affect the mode of operation of another drive
+(drive Y) on the same port as described above. It is only when a port
+reset is required to recover from an exception on drive Y that further
+I/O operations on that drive (and the reset itself) will be delayed
+until drive X is no longer in the parked state.
+
+Finally, there are some hard drives that only comply with an earlier
+version of the ATA standard than ATA-7, but do support the unload
+feature nonetheless. Unfortunately, there is no safe way Linux can
+detect these devices, so you won't be able to write to the
+unload_heads attribute. If you know that your device really does
+support the unload feature (for instance, because the vendor of your
+laptop or the hard drive itself told you so), then you can tell the
+kernel to enable the usage of this feature for that drive by writing
+the special value -1 to the unload_heads attribute::
+
+	# echo -1 > /sys/block/sda/device/unload_heads
+
+will enable the feature for /dev/sda, and giving -2 instead of -1 will
+disable it again.
+
+
+3. References
+-------------
+
+There are several laptops from different vendors featuring shock
+protection capabilities. As manufacturers have refused to support open
+source development of the required software components so far, Linux
+support for shock protection varies considerably between different
+hardware implementations. Ideally, this section should contain a list
+of pointers at different projects aiming at an implementation of shock
+protection on different systems. Unfortunately, I only know of a
+single project which, although still considered experimental, is fit
+for use. Please feel free to add projects that have been the victims
+of my ignorance.
+
+- https://www.thinkwiki.org/wiki/HDAPS
+
+  See this page for information about Linux support of the hard disk
+  active protection system as implemented in IBM/Lenovo Thinkpads.
+
+
+4. CREDITS
+----------
+
+This implementation of disk head parking has been inspired by a patch
+originally published by Jon Escombe <lists@dresco.co.uk>. My efforts
+to develop an implementation of this feature that is fit to be merged
+into mainline have been aided by various kernel developers, in
+particular by Tejun Heo and Bartlomiej Zolnierkiewicz.
diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst
new file mode 100644
index 000000000..c0b911d05
--- /dev/null
+++ b/Documentation/admin-guide/laptops/index.rst
@@ -0,0 +1,19 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+Laptop Drivers
+==============
+
+.. toctree::
+   :maxdepth: 1
+
+   alienware-wmi
+   asus-laptop
+   disk-shock-protection
+   lg-laptop
+   samsung-galaxybook
+   sony-laptop
+   sonypi
+   thinkpad-acpi
+   toshiba_haps
+   uniwill-laptop
diff --git a/Documentation/admin-guide/laptops/lg-laptop.rst b/Documentation/admin-guide/laptops/lg-laptop.rst
new file mode 100644
index 000000000..c4dd534f9
--- /dev/null
+++ b/Documentation/admin-guide/laptops/lg-laptop.rst
@@ -0,0 +1,82 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+
+LG Gram laptop extra features
+=============================
+
+By Matan Ziv-Av <matan@svgalib.org>
+
+
+Hotkeys
+-------
+
+The following FN keys are ignored by the kernel without this driver:
+
+- FN-F1 (LG control panel)   - Generates F15
+- FN-F5 (Touchpad toggle)    - Generates F21
+- FN-F6 (Airplane mode)      - Generates RFKILL
+- FN-F9 (Reader mode)        - Generates F14
+
+The rest of the FN keys work without a need for a special driver.
+
+
+Reader mode
+-----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/reader_mode disables/enables
+reader mode. In this mode the screen colors change (blue color reduced),
+and the reader mode indicator LED (on F9 key) turns on.
+
+
+FN Lock
+-------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/fn_lock disables/enables
+FN lock.
+
+
+Battery care limit
+------------------
+
+Writing 80/100 to /sys/class/power_supply/CMB0/charge_control_end_threshold
+sets the maximum capacity to charge the battery. Limiting the charge
+reduces battery capacity loss over time.
+
+This value is reset to 100 when the kernel boots.
+
+
+Fan mode
+--------
+
+Writing 0/1/2 to /sys/devices/platform/lg-laptop/fan_mode sets fan mode to
+Optimal/Silent/Performance respectively.
+
+
+USB charge
+----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/usb_charge disables/enables
+charging another device from the USB port while the device is turned off.
+
+This value is reset to 0 when the kernel boots.
+
+
+LEDs
+~~~~
+
+The are two LED devices supported by the driver:
+
+Keyboard backlight
+------------------
+
+A led device named kbd_led controls the keyboard backlight. There are three
+lighting level: off (0), low (127) and high (255).
+
+The keyboard backlight is also controlled by the key combination FN-F8
+which cycles through those levels.
+
+
+Touchpad indicator LED
+----------------------
+
+On the F5 key. Controlled by led device names tpad_led.
diff --git a/Documentation/admin-guide/laptops/samsung-galaxybook.rst b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
new file mode 100644
index 000000000..752b8f1a4
--- /dev/null
+++ b/Documentation/admin-guide/laptops/samsung-galaxybook.rst
@@ -0,0 +1,174 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==========================
+Samsung Galaxy Book Driver
+==========================
+
+Joshua Grisham <josh@joshuagrisham.com>
+
+This is a Linux x86 platform driver for Samsung Galaxy Book series notebook
+devices which utilizes Samsung's ``SCAI`` ACPI device in order to control
+extra features and receive various notifications.
+
+Supported devices
+=================
+
+Any device with one of the supported ACPI device IDs should be supported. This
+covers most of the "Samsung Galaxy Book" series notebooks that are currently
+available as of this writing, and could include other Samsung notebook devices
+as well.
+
+Status
+======
+
+The following features are currently supported:
+
+- :ref:`Keyboard backlight <keyboard-backlight>` control
+- :ref:`Performance mode <performance-mode>` control implemented using the
+  platform profile interface
+- :ref:`Battery charge control end threshold
+  <battery-charge-control-end-threshold>` (stop charging battery at given
+  percentage value) implemented as a battery hook
+- :ref:`Firmware Attributes <firmware-attributes>` to allow control of various
+  device settings
+- :ref:`Handling of Fn hotkeys <keyboard-hotkey-actions>` for various actions
+- :ref:`Handling of ACPI notifications and hotkeys
+  <acpi-notifications-and-hotkey-actions>`
+
+Because different models of these devices can vary in their features, there is
+logic built within the driver which attempts to test each implemented feature
+for a valid response before enabling its support (registering additional devices
+or extensions, adding sysfs attributes, etc). Therefore, it can be important to
+note that not all features may be supported for your particular device.
+
+The following features might be possible to implement but will require
+additional investigation and are therefore not supported at this time:
+
+- "Dolby Atmos" mode for the speakers
+- "Outdoor Mode" for increasing screen brightness on models with ``SAM0427``
+- "Silent Mode" on models with ``SAM0427``
+
+.. _keyboard-backlight:
+
+Keyboard backlight
+==================
+
+A new LED class named ``samsung-galaxybook::kbd_backlight`` is created which
+will then expose the device using the standard sysfs-based LED interface at
+``/sys/class/leds/samsung-galaxybook::kbd_backlight``. Brightness can be
+controlled by writing the desired value to the ``brightness`` sysfs attribute or
+with any other desired userspace utility.
+
+.. note::
+  Most of these devices have an ambient light sensor which also turns
+  off the keyboard backlight under well-lit conditions. This behavior does not
+  seem possible to control at this time, but can be good to be aware of.
+
+.. _performance-mode:
+
+Performance mode
+================
+
+This driver implements the
+Documentation/userspace-api/sysfs-platform_profile.rst interface for working
+with the "performance mode" function of the Samsung ACPI device.
+
+Mapping of each Samsung "performance mode" to its respective platform profile is
+performed dynamically by the driver, as not all models support all of the same
+performance modes. Your device might have one or more of the following mappings:
+
+- "Silent" maps to ``low-power``
+- "Quiet" maps to ``quiet``
+- "Optimized" maps to ``balanced``
+- "High performance" maps to ``performance``
+
+The result of the mapping can be printed in the kernel log when the module is
+loaded. Supported profiles can also be retrieved from
+``/sys/firmware/acpi/platform_profile_choices``, while
+``/sys/firmware/acpi/platform_profile`` can be used to read or write the
+currently selected profile.
+
+The ``balanced`` platform profile will be set during module load if no profile
+has been previously set.
+
+.. _battery-charge-control-end-threshold:
+
+Battery charge control end threshold
+====================================
+
+This platform driver will add the ability to set the battery's charge control
+end threshold, but does not have the ability to set a start threshold.
+
+This feature is typically called "Battery Saver" by the various Samsung
+applications in Windows, but in Linux we have implemented the standardized
+"charge control threshold" sysfs interface on the battery device to allow for
+controlling this functionality from the userspace.
+
+The sysfs attribute
+``/sys/class/power_supply/BAT1/charge_control_end_threshold`` can be used to
+read or set the desired charge end threshold.
+
+If you wish to maintain interoperability with the Samsung Settings application
+in Windows, then you should set the value to 100 to represent "off", or enable
+the feature using only one of the following values: 50, 60, 70, 80, or 90.
+Otherwise, the driver will accept any value between 1 and 100 as the percentage
+that you wish the battery to stop charging at.
+
+.. note::
+  Some devices have been observed as automatically "turning off" the charge
+  control end threshold if an input value of less than 30 is given.
+
+.. _firmware-attributes:
+
+Firmware Attributes
+===================
+
+The following enumeration-typed firmware attributes are set up by this driver
+and should be accessible under
+``/sys/class/firmware-attributes/samsung-galaxybook/attributes/`` if your device
+supports them:
+
+- ``power_on_lid_open`` (device should power on when the lid is opened)
+- ``usb_charging``  (USB ports can deliver power to connected devices even when
+  the device is powered off or in a low sleep state)
+- ``block_recording`` (blocks access to camera and microphone)
+
+All of these attributes are simple boolean-like enumeration values which use 0
+to represent "off" and 1 to represent "on". Use the ``current_value`` attribute
+to get or change the setting on the device.
+
+Note that when ``block_recording`` is updated, the input device "Samsung Galaxy
+Book Lens Cover" will receive a ``SW_CAMERA_LENS_COVER`` switch event which
+reflects the current state.
+
+.. _keyboard-hotkey-actions:
+
+Keyboard hotkey actions (i8042 filter)
+======================================
+
+The i8042 filter will swallow the keyboard events for the Fn+F9 hotkey (Multi-
+level keyboard backlight toggle) and Fn+F10 hotkey (Block recording toggle)
+and instead execute their actions within the driver itself.
+
+Fn+F9 will cycle through the brightness levels of the keyboard backlight. A
+notification will be sent using ``led_classdev_notify_brightness_hw_changed``
+so that the userspace can be aware of the change. This mimics the behavior of
+other existing devices where the brightness level is cycled internally by the
+embedded controller and then reported via a notification.
+
+Fn+F10 will toggle the value of the "block recording" setting, which blocks
+or allows usage of the built-in camera and microphone (and generates the same
+Lens Cover switch event mentioned above).
+
+.. _acpi-notifications-and-hotkey-actions:
+
+ACPI notifications and hotkey actions
+=====================================
+
+ACPI notifications will generate ACPI netlink events under the device class
+``samsung-galaxybook`` and bus ID matching the Samsung ACPI device ID found on
+your device. The events can be received using userspace tools such as
+``acpi_listen`` and ``acpid``.
+
+The Fn+F11 Performance mode hotkey will be handled by the driver; each keypress
+will cycle to the next available platform profile.
diff --git a/Documentation/admin-guide/laptops/sony-laptop.rst b/Documentation/admin-guide/laptops/sony-laptop.rst
new file mode 100644
index 000000000..9edcc7f66
--- /dev/null
+++ b/Documentation/admin-guide/laptops/sony-laptop.rst
@@ -0,0 +1,174 @@
+=========================================
+Sony Notebook Control Driver (SNC) Readme
+=========================================
+
+	- Copyright (C) 2004- 2005 Stelian Pop <stelian@popies.net>
+	- Copyright (C) 2007 Mattia Dongili <malattia@linux.it>
+
+This mini-driver drives the SNC and SPIC device present in the ACPI BIOS of the
+Sony Vaio laptops. This driver mixes both devices functions under the same
+(hopefully consistent) interface. This also means that the sonypi driver is
+obsoleted by sony-laptop now.
+
+Fn keys (hotkeys):
+------------------
+
+Some models report hotkeys through the SNC or SPIC devices, such events are
+reported both through the ACPI subsystem as acpi events and through the INPUT
+subsystem. See the logs of /proc/bus/input/devices to find out what those
+events are and which input devices are created by the driver.
+Additionally, loading the driver with the debug option will report all events
+in the kernel log.
+
+The "scancodes" passed to the input system (that can be remapped with udev)
+are indexes to the table "sony_laptop_input_keycode_map" in the sony-laptop.c
+module.  For example the "FN/E" key combination (EJECTCD on some models)
+generates the scancode 20 (0x14).
+
+Backlight control:
+------------------
+If your laptop model supports it, you will find sysfs files in the
+/sys/class/backlight/sony/
+directory. You will be able to query and set the current screen
+brightness:
+
+	======================	=========================================
+	brightness		get/set screen brightness (an integer
+				between 0 and 7)
+	actual_brightness	reading from this file will query the HW
+				to get real brightness value
+	max_brightness		the maximum brightness value
+	======================	=========================================
+
+
+Platform specific:
+------------------
+Loading the sony-laptop module will create a
+/sys/devices/platform/sony-laptop/
+directory populated with some files.
+
+You then read/write integer values from/to those files by using
+standard UNIX tools.
+
+The files are:
+
+	======================	==========================================
+	brightness_default	screen brightness which will be set
+				when the laptop will be rebooted
+	cdpower			power on/off the internal CD drive
+	audiopower		power on/off the internal sound card
+	lanpower		power on/off the internal ethernet card
+				(only in debug mode)
+	bluetoothpower		power on/off the internal bluetooth device
+	fanspeed		get/set the fan speed
+	======================	==========================================
+
+Note that some files may be missing if they are not supported
+by your particular laptop model.
+
+Example usage::
+
+	# echo "1" > /sys/devices/platform/sony-laptop/brightness_default
+
+sets the lowest screen brightness for the next and later reboots
+
+::
+
+	# echo "8" > /sys/devices/platform/sony-laptop/brightness_default
+
+sets the highest screen brightness for the next and later reboots
+
+::
+
+	# cat /sys/devices/platform/sony-laptop/brightness_default
+
+retrieves the value
+
+::
+
+	# echo "0" > /sys/devices/platform/sony-laptop/audiopower
+
+powers off the sound card
+
+::
+
+	# echo "1" > /sys/devices/platform/sony-laptop/audiopower
+
+powers on the sound card.
+
+
+RFkill control:
+---------------
+More recent Vaio models expose a consistent set of ACPI methods to
+control radio frequency emitting devices. If you are a lucky owner of
+such a laptop you will find the necessary rfkill devices under
+/sys/class/rfkill. Check those starting with sony-* in::
+
+	# grep . /sys/class/rfkill/*/{state,name}
+
+
+Development:
+------------
+
+If you want to help with the development of this driver (and
+you are not afraid of any side effects doing strange things with
+your ACPI BIOS could have on your laptop), load the driver and
+pass the option 'debug=1'.
+
+REPEAT:
+	**DON'T DO THIS IF YOU DON'T LIKE RISKY BUSINESS.**
+
+In your kernel logs you will find the list of all ACPI methods
+the SNC device has on your laptop.
+
+* For new models you will see a long list of meaningless method names,
+  reading the DSDT table source should reveal that:
+
+(1) the SNC device uses an internal capability lookup table
+(2) SN00 is used to find values in the lookup table
+(3) SN06 and SN07 are used to call into the real methods based on
+    offsets you can obtain iterating the table using SN00
+(4) SN02 used to enable events.
+
+Some values in the capability lookup table are more or less known, see
+the code for all sony_call_snc_handle calls, others are more obscure.
+
+* For old models you can see the GCDP/GCDP methods used to pwer on/off
+  the CD drive, but there are others and they are usually different from
+  model to model.
+
+**I HAVE NO IDEA WHAT THOSE METHODS DO.**
+
+The sony-laptop driver creates, for some of those methods (the most
+current ones found on several Vaio models), an entry under
+/sys/devices/platform/sony-laptop, just like the 'cdpower' one.
+You can create other entries corresponding to your own laptop methods by
+further editing the source (see the 'sony_nc_values' table, and add a new
+entry to this table with your get/set method names using the
+SNC_HANDLE_NAMES macro).
+
+Your mission, should you accept it, is to try finding out what
+those entries are for, by reading/writing random values from/to those
+files and find out what is the impact on your laptop.
+
+Should you find anything interesting, please report it back to me,
+I will not disavow all knowledge of your actions :)
+
+See also http://www.linux.it/~malattia/wiki/index.php/Sony_drivers for other
+useful info.
+
+Bugs/Limitations:
+-----------------
+
+* This driver is not based on official documentation from Sony
+  (because there is none), so there is no guarantee this driver
+  will work at all, or do the right thing. Although this hasn't
+  happened to me, this driver could do very bad things to your
+  laptop, including permanent damage.
+
+* The sony-laptop and sonypi drivers do not interact at all. In the
+  future, sonypi will be removed and replaced by sony-laptop.
+
+* spicctrl, which is the userspace tool used to communicate with the
+  sonypi driver (through /dev/sonypi) is deprecated as well since all
+  its features are now available under the sysfs tree via sony-laptop.
diff --git a/Documentation/admin-guide/laptops/sonypi.rst b/Documentation/admin-guide/laptops/sonypi.rst
new file mode 100644
index 000000000..fb8f4a30d
--- /dev/null
+++ b/Documentation/admin-guide/laptops/sonypi.rst
@@ -0,0 +1,158 @@
+==================================================
+Sony Programmable I/O Control Device Driver Readme
+==================================================
+
+	- Copyright (C) 2001-2004 Stelian Pop <stelian@popies.net>
+	- Copyright (C) 2001-2002 Alcôve <www.alcove.com>
+	- Copyright (C) 2001 Michael Ashley <m.ashley@unsw.edu.au>
+	- Copyright (C) 2001 Junichi Morita <jun1m@mars.dti.ne.jp>
+	- Copyright (C) 2000 Takaya Kinjo <t-kinjo@tc4.so-net.ne.jp>
+	- Copyright (C) 2000 Andrew Tridgell <tridge@samba.org>
+
+This driver enables access to the Sony Programmable I/O Control Device which
+can be found in many Sony Vaio laptops. Some newer Sony laptops (seems to be
+limited to new FX series laptops, at least the FX501 and the FX702) lack a
+sonypi device and are not supported at all by this driver.
+
+It will give access (through a user space utility) to some events those laptops
+generate, like:
+
+	- jogdial events (the small wheel on the side of Vaios)
+	- capture button events (only on Vaio Picturebook series)
+	- Fn keys
+	- bluetooth button (only on C1VR model)
+	- programmable keys, back, help, zoom, thumbphrase buttons, etc.
+	  (when available)
+
+Those events (see linux/sonypi.h) can be polled using the character device node
+/dev/sonypi (major 10, minor auto allocated or specified as an option).
+A simple daemon which translates the jogdial movements into mouse wheel events
+can be downloaded at: <http://popies.net/sonypi/>
+
+Another option to intercept the events is to get them directly through the
+input layer.
+
+This driver supports also some ioctl commands for setting the LCD screen
+brightness and querying the batteries charge information (some more
+commands may be added in the future).
+
+This driver can also be used to set the camera controls on Picturebook series
+(brightness, contrast etc), and is used by the video4linux driver for the
+Motion Eye camera.
+
+Please note that this driver was created by reverse engineering the Windows
+driver and the ACPI BIOS, because Sony doesn't agree to release any programming
+specs for its laptops. If someone convinces them to do so, drop me a note.
+
+Driver options:
+---------------
+
+Several options can be passed to the sonypi driver using the standard
+module argument syntax (<param>=<value> when passing the option to the
+module or sonypi.<param>=<value> on the kernel boot line when sonypi is
+statically linked into the kernel). Those options are:
+
+	=============== =======================================================
+	minor:		minor number of the misc device /dev/sonypi,
+			default is -1 (automatic allocation, see /proc/misc
+			or kernel logs)
+
+	camera:		if you have a PictureBook series Vaio (with the
+			integrated MotionEye camera), set this parameter to 1
+			in order to let the driver access to the camera
+
+	fnkeyinit:	on some Vaios (C1VE, C1VR etc), the Fn key events don't
+			get enabled unless you set this parameter to 1.
+			Do not use this option unless it's actually necessary,
+			some Vaio models don't deal well with this option.
+			This option is available only if the kernel is
+			compiled without ACPI support (since it conflicts
+			with it and it shouldn't be required anyway if
+			ACPI is already enabled).
+
+	verbose:	set to 1 to print unknown events received from the
+			sonypi device.
+			set to 2 to print all events received from the
+			sonypi device.
+
+	compat:		uses some compatibility code for enabling the sonypi
+			events. If the driver worked for you in the past
+			(prior to version 1.5) and does not work anymore,
+			add this option and report to the author.
+
+	mask:		event mask telling the driver what events will be
+			reported to the user. This parameter is required for
+			some Vaio models where the hardware reuses values
+			used in other Vaio models (like the FX series who does
+			not have a jogdial but reuses the jogdial events for
+			programmable keys events). The default event mask is
+			set to 0xffffffff, meaning that all possible events
+			will be tried. You can use the following bits to
+			construct your own event mask (from
+			include/linux/sonypi.h)::
+
+				SONYPI_JOGGER_MASK		0x0001
+				SONYPI_CAPTURE_MASK		0x0002
+				SONYPI_FNKEY_MASK		0x0004
+				SONYPI_BLUETOOTH_MASK		0x0008
+				SONYPI_PKEY_MASK		0x0010
+				SONYPI_BACK_MASK		0x0020
+				SONYPI_HELP_MASK		0x0040
+				SONYPI_LID_MASK			0x0080
+				SONYPI_ZOOM_MASK		0x0100
+				SONYPI_THUMBPHRASE_MASK		0x0200
+				SONYPI_MEYE_MASK		0x0400
+				SONYPI_MEMORYSTICK_MASK		0x0800
+				SONYPI_BATTERY_MASK		0x1000
+				SONYPI_WIRELESS_MASK		0x2000
+
+	useinput:	if set (which is the default) two input devices are
+			created, one which interprets the jogdial events as
+			mouse events, the other one which acts like a
+			keyboard reporting the pressing of the special keys.
+	=============== =======================================================
+
+Module use:
+-----------
+
+In order to automatically load the sonypi module on use, you can put those
+lines a configuration file in /etc/modprobe.d/::
+
+	alias char-major-10-250 sonypi
+	options sonypi minor=250
+
+This supposes the use of minor 250 for the sonypi device::
+
+	# mknod /dev/sonypi c 10 250
+
+Bugs:
+-----
+
+	- several users reported that this driver disables the BIOS-managed
+	  Fn-keys which put the laptop in sleeping state, or switch the
+	  external monitor on/off. There is no workaround yet, since this
+	  driver disables all APM management for those keys, by enabling the
+	  ACPI management (and the ACPI core stuff is not complete yet). If
+	  you have one of those laptops with working Fn keys and want to
+	  continue to use them, don't use this driver.
+
+	- some users reported that the laptop speed is lower (dhrystone
+	  tested) when using the driver with the fnkeyinit parameter. I cannot
+	  reproduce it on my laptop and not all users have this problem.
+	  This happens because the fnkeyinit parameter enables the ACPI
+	  mode (but without additional ACPI control, like processor
+	  speed handling etc). Use ACPI instead of APM if it works on your
+	  laptop.
+
+	- sonypi lacks the ability to distinguish between certain key
+	  events on some models.
+
+	- some models with the nvidia card (geforce go 6200 tc) uses a
+	  different way to adjust the backlighting of the screen. There
+	  is a userspace utility to adjust the brightness on those models,
+	  which can be downloaded from
+	  https://www.acc.umu.se/~erikw/program/smartdimmer-0.1.tar.bz2
+
+	- since all development was done by reverse engineering, there is
+	  *absolutely no guarantee* that this driver will not crash your
+	  laptop. Permanently.
diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
new file mode 100644
index 000000000..db4588af0
--- /dev/null
+++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
@@ -0,0 +1,1773 @@
+===========================
+ThinkPad ACPI Extras Driver
+===========================
+
+Version 0.25
+
+October 16th,  2013
+
+- Borislav Deianov <borislav@users.sf.net>
+- Henrique de Moraes Holschuh <hmh@hmh.eng.br>
+
+http://ibm-acpi.sf.net/
+
+This is a Linux driver for the IBM and Lenovo ThinkPad laptops. It
+supports various features of these laptops which are accessible
+through the ACPI and ACPI EC framework, but not otherwise fully
+supported by the generic Linux ACPI drivers.
+
+This driver used to be named ibm-acpi until kernel 2.6.21 and release
+0.13-20070314.  It used to be in the drivers/acpi tree, but it was
+moved to the drivers/misc tree and renamed to thinkpad-acpi for kernel
+2.6.22, and release 0.14.  It was moved to drivers/platform/x86 for
+kernel 2.6.29 and release 0.22.
+
+The driver is named "thinkpad-acpi".  In some places, like module
+names and log messages, "thinkpad_acpi" is used because of userspace
+issues.
+
+"tpacpi" is used as a shorthand where "thinkpad-acpi" would be too
+long due to length limitations on some Linux kernel versions.
+
+Status
+------
+
+The features currently supported are the following (see below for
+detailed description):
+
+	- Fn key combinations
+	- Bluetooth enable and disable
+	- video output switching, expansion control
+	- ThinkLight on and off
+	- CMOS/UCMS control
+	- LED control
+	- ACPI sounds
+	- temperature sensors
+	- Experimental: embedded controller register dump
+	- LCD brightness control
+	- Volume control
+	- Fan control and monitoring: fan speed, fan enable/disable
+	- WAN enable and disable
+	- UWB enable and disable
+	- LCD Shadow (PrivacyGuard) enable and disable
+	- Lap mode sensor
+	- Setting keyboard language
+	- WWAN Antenna type
+	- Auxmac
+	- Hardware damage detection capability
+
+A compatibility table by model and feature is maintained on the web
+site, http://ibm-acpi.sf.net/. I appreciate any success or failure
+reports, especially if they add to or correct the compatibility table.
+Please include the following information in your report:
+
+	- ThinkPad model name
+	- a copy of your ACPI tables, using the "acpidump" utility
+	- a copy of the output of dmidecode, with serial numbers
+	  and UUIDs masked off
+	- which driver features work and which don't
+	- the observed behavior of non-working features
+
+Any other comments or patches are also more than welcome.
+
+
+Installation
+------------
+
+If you are compiling this driver as included in the Linux kernel
+sources, look for the CONFIG_THINKPAD_ACPI Kconfig option.
+It is located on the menu path: "Device Drivers" -> "X86 Platform
+Specific Device Drivers" -> "ThinkPad ACPI Laptop Extras".
+
+
+Features
+--------
+
+The driver exports two different interfaces to userspace, which can be
+used to access the features it provides.  One is a legacy procfs-based
+interface, which will be removed at some time in the future.  The other
+is a new sysfs-based interface which is not complete yet.
+
+The procfs interface creates the /proc/acpi/ibm directory.  There is a
+file under that directory for each feature it supports.  The procfs
+interface is mostly frozen, and will change very little if at all: it
+will not be extended to add any new functionality in the driver, instead
+all new functionality will be implemented on the sysfs interface.
+
+The sysfs interface tries to blend in the generic Linux sysfs subsystems
+and classes as much as possible.  Since some of these subsystems are not
+yet ready or stabilized, it is expected that this interface will change,
+and any and all userspace programs must deal with it.
+
+
+Notes about the sysfs interface
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unlike what was done with the procfs interface, correctness when talking
+to the sysfs interfaces will be enforced, as will correctness in the
+thinkpad-acpi's implementation of sysfs interfaces.
+
+Also, any bugs in the thinkpad-acpi sysfs driver code or in the
+thinkpad-acpi's implementation of the sysfs interfaces will be fixed for
+maximum correctness, even if that means changing an interface in
+non-compatible ways.  As these interfaces mature both in the kernel and
+in thinkpad-acpi, such changes should become quite rare.
+
+Applications interfacing to the thinkpad-acpi sysfs interfaces must
+follow all sysfs guidelines and correctly process all errors (the sysfs
+interface makes extensive use of errors).  File descriptors and open /
+close operations to the sysfs inodes must also be properly implemented.
+
+The version of thinkpad-acpi's sysfs interface is exported by the driver
+as a driver attribute (see below).
+
+Sysfs driver attributes are on the driver's sysfs attribute space,
+for 2.6.23+ this is /sys/bus/platform/drivers/thinkpad_acpi/ and
+/sys/bus/platform/drivers/thinkpad_hwmon/
+
+Sysfs device attributes are on the thinkpad_acpi device sysfs attribute
+space, for 2.6.23+ this is /sys/devices/platform/thinkpad_acpi/.
+
+Sysfs device attributes for the sensors and fan are on the
+thinkpad_hwmon device's sysfs attribute space, but you should locate it
+looking for a hwmon device with the name attribute of "thinkpad", or
+better yet, through libsensors. For 4.14+ sysfs attributes were moved to the
+hwmon device (/sys/bus/platform/devices/thinkpad_hwmon/hwmon/hwmon? or
+/sys/class/hwmon/hwmon?).
+
+Driver version
+--------------
+
+procfs: /proc/acpi/ibm/driver
+
+sysfs driver attribute: version
+
+The driver name and version. No commands can be written to this file.
+
+
+Sysfs interface version
+-----------------------
+
+sysfs driver attribute: interface_version
+
+Version of the thinkpad-acpi sysfs interface, as an unsigned long
+(output in hex format: 0xAAAABBCC), where:
+
+	AAAA
+	  - major revision
+	BB
+	  - minor revision
+	CC
+	  - bugfix revision
+
+The sysfs interface version changelog for the driver can be found at the
+end of this document.  Changes to the sysfs interface done by the kernel
+subsystems are not documented here, nor are they tracked by this
+attribute.
+
+Changes to the thinkpad-acpi sysfs interface are only considered
+non-experimental when they are submitted to Linux mainline, at which
+point the changes in this interface are documented and interface_version
+may be updated.  If you are using any thinkpad-acpi features not yet
+sent to mainline for merging, you do so on your own risk: these features
+may disappear, or be implemented in a different and incompatible way by
+the time they are merged in Linux mainline.
+
+Changes that are backwards-compatible by nature (e.g. the addition of
+attributes that do not change the way the other attributes work) do not
+always warrant an update of interface_version.  Therefore, one must
+expect that an attribute might not be there, and deal with it properly
+(an attribute not being there *is* a valid way to make it clear that a
+feature is not available in sysfs).
+
+
+Hot keys
+--------
+
+procfs: /proc/acpi/ibm/hotkey
+
+sysfs device attribute: hotkey_*
+
+In a ThinkPad, the ACPI HKEY handler is responsible for communicating
+some important events and also keyboard hot key presses to the operating
+system.  Enabling the hotkey functionality of thinkpad-acpi signals the
+firmware that such a driver is present, and modifies how the ThinkPad
+firmware will behave in many situations.
+
+The driver enables the HKEY ("hot key") event reporting automatically
+when loaded, and disables it when it is removed.
+
+The driver will report HKEY events in the following format::
+
+	ibm/hotkey HKEY 00000080 0000xxxx
+
+Some of these events refer to hot key presses, but not all of them.
+
+The driver will generate events over the input layer for hot keys and
+radio switches, and over the ACPI netlink layer for other events.  The
+input layer support accepts the standard IOCTLs to remap the keycodes
+assigned to each hot key.
+
+The hot key bit mask allows some control over which hot keys generate
+events.  If a key is "masked" (bit set to 0 in the mask), the firmware
+will handle it.  If it is "unmasked", it signals the firmware that
+thinkpad-acpi would prefer to handle it, if the firmware would be so
+kind to allow it (and it often doesn't!).
+
+Not all bits in the mask can be modified.  Not all bits that can be
+modified do anything.  Not all hot keys can be individually controlled
+by the mask.  Some models do not support the mask at all.  The behaviour
+of the mask is, therefore, highly dependent on the ThinkPad model.
+
+The driver will filter out any unmasked hotkeys, so even if the firmware
+doesn't allow disabling an specific hotkey, the driver will not report
+events for unmasked hotkeys.
+
+Note that unmasking some keys prevents their default behavior.  For
+example, if Fn+F5 is unmasked, that key will no longer enable/disable
+Bluetooth by itself in firmware.
+
+Note also that not all Fn key combinations are supported through ACPI
+depending on the ThinkPad model and firmware version.  On those
+ThinkPads, it is still possible to support some extra hotkeys by
+polling the "CMOS NVRAM" at least 10 times per second.  The driver
+attempts to enables this functionality automatically when required.
+
+procfs notes
+^^^^^^^^^^^^
+
+The following commands can be written to the /proc/acpi/ibm/hotkey file::
+
+	echo 0xffffffff > /proc/acpi/ibm/hotkey -- enable all hot keys
+	echo 0 > /proc/acpi/ibm/hotkey -- disable all possible hot keys
+	... any other 8-hex-digit mask ...
+	echo reset > /proc/acpi/ibm/hotkey -- restore the recommended mask
+
+The following commands have been deprecated and will cause the kernel
+to log a warning::
+
+	echo enable > /proc/acpi/ibm/hotkey -- does nothing
+	echo disable > /proc/acpi/ibm/hotkey -- returns an error
+
+The procfs interface does not support NVRAM polling control.  So as to
+maintain maximum bug-to-bug compatibility, it does not report any masks,
+nor does it allow one to manipulate the hot key mask when the firmware
+does not support masks at all, even if NVRAM polling is in use.
+
+sysfs notes
+^^^^^^^^^^^
+
+	hotkey_bios_enabled:
+		DEPRECATED, WILL BE REMOVED SOON.
+
+		Returns 0.
+
+	hotkey_bios_mask:
+		DEPRECATED, DON'T USE, WILL BE REMOVED IN THE FUTURE.
+
+		Returns the hot keys mask when thinkpad-acpi was loaded.
+		Upon module unload, the hot keys mask will be restored
+		to this value.   This is always 0x80c, because those are
+		the hotkeys that were supported by ancient firmware
+		without mask support.
+
+	hotkey_enable:
+		DEPRECATED, WILL BE REMOVED SOON.
+
+		0: returns -EPERM
+		1: does nothing
+
+	hotkey_mask:
+		bit mask to enable reporting (and depending on
+		the firmware, ACPI event generation) for each hot key
+		(see above).  Returns the current status of the hot keys
+		mask, and allows one to modify it.
+
+	hotkey_all_mask:
+		bit mask that should enable event reporting for all
+		supported hot keys, when echoed to hotkey_mask above.
+		Unless you know which events need to be handled
+		passively (because the firmware *will* handle them
+		anyway), do *not* use hotkey_all_mask.  Use
+		hotkey_recommended_mask, instead. You have been warned.
+
+	hotkey_recommended_mask:
+		bit mask that should enable event reporting for all
+		supported hot keys, except those which are always
+		handled by the firmware anyway.  Echo it to
+		hotkey_mask above, to use.  This is the default mask
+		used by the driver.
+
+	hotkey_source_mask:
+		bit mask that selects which hot keys will the driver
+		poll the NVRAM for.  This is auto-detected by the driver
+		based on the capabilities reported by the ACPI firmware,
+		but it can be overridden at runtime.
+
+		Hot keys whose bits are set in hotkey_source_mask are
+		polled for in NVRAM, and reported as hotkey events if
+		enabled in hotkey_mask.  Only a few hot keys are
+		available through CMOS NVRAM polling.
+
+		Warning: when in NVRAM mode, the volume up/down/mute
+		keys are synthesized according to changes in the mixer,
+		which uses a single volume up or volume down hotkey
+		press to unmute, as per the ThinkPad volume mixer user
+		interface.  When in ACPI event mode, volume up/down/mute
+		events are reported by the firmware and can behave
+		differently (and that behaviour changes with firmware
+		version -- not just with firmware models -- as well as
+		OSI(Linux) state).
+
+	hotkey_poll_freq:
+		frequency in Hz for hot key polling. It must be between
+		0 and 25 Hz.  Polling is only carried out when strictly
+		needed.
+
+		Setting hotkey_poll_freq to zero disables polling, and
+		will cause hot key presses that require NVRAM polling
+		to never be reported.
+
+		Setting hotkey_poll_freq too low may cause repeated
+		pressings of the same hot key to be misreported as a
+		single key press, or to not even be detected at all.
+		The recommended polling frequency is 10Hz.
+
+	hotkey_radio_sw:
+		If the ThinkPad has a hardware radio switch, this
+		attribute will read 0 if the switch is in the "radios
+		disabled" position, and 1 if the switch is in the
+		"radios enabled" position.
+
+		This attribute has poll()/select() support.
+
+	hotkey_tablet_mode:
+		If the ThinkPad has tablet capabilities, this attribute
+		will read 0 if the ThinkPad is in normal mode, and
+		1 if the ThinkPad is in tablet mode.
+
+		This attribute has poll()/select() support.
+
+	wakeup_reason:
+		Set to 1 if the system is waking up because the user
+		requested a bay ejection.  Set to 2 if the system is
+		waking up because the user requested the system to
+		undock.  Set to zero for normal wake-ups or wake-ups
+		due to unknown reasons.
+
+		This attribute has poll()/select() support.
+
+	wakeup_hotunplug_complete:
+		Set to 1 if the system was waken up because of an
+		undock or bay ejection request, and that request
+		was successfully completed.  At this point, it might
+		be useful to send the system back to sleep, at the
+		user's choice.  Refer to HKEY events 0x4003 and
+		0x3003, below.
+
+		This attribute has poll()/select() support.
+
+input layer notes
+^^^^^^^^^^^^^^^^^
+
+A Hot key is mapped to a single input layer EV_KEY event, possibly
+followed by an EV_MSC MSC_SCAN event that shall contain that key's scan
+code.  An EV_SYN event will always be generated to mark the end of the
+event block.
+
+Do not use the EV_MSC MSC_SCAN events to process keys.  They are to be
+used as a helper to remap keys, only.  They are particularly useful when
+remapping KEY_UNKNOWN keys.
+
+The events are available in an input device, with the following id:
+
+	==============  ==============================
+	Bus		BUS_HOST
+	vendor		0x1014 (PCI_VENDOR_ID_IBM)  or
+			0x17aa (PCI_VENDOR_ID_LENOVO)
+	product		0x5054 ("TP")
+	version		0x4101
+	==============  ==============================
+
+The version will have its LSB incremented if the keymap changes in a
+backwards-compatible way.  The MSB shall always be 0x41 for this input
+device.  If the MSB is not 0x41, do not use the device as described in
+this section, as it is either something else (e.g. another input device
+exported by a thinkpad driver, such as HDAPS) or its functionality has
+been changed in a non-backwards compatible way.
+
+Adding other event types for other functionalities shall be considered a
+backwards-compatible change for this input device.
+
+Thinkpad-acpi Hot Key event map (version 0x4101):
+
+=======	=======	==============	==============================================
+ACPI	Scan
+event	code	Key		Notes
+=======	=======	==============	==============================================
+0x1001	0x00	FN+F1		-
+
+0x1002	0x01	FN+F2		IBM: battery (rare)
+				Lenovo: Screen lock
+
+0x1003	0x02	FN+F3		Many IBM models always report
+				this hot key, even with hot keys
+				disabled or with Fn+F3 masked
+				off
+				IBM: screen lock, often turns
+				off the ThinkLight as side-effect
+				Lenovo: battery
+
+0x1004	0x03	FN+F4		Sleep button (ACPI sleep button
+				semantics, i.e. sleep-to-RAM).
+				It always generates some kind
+				of event, either the hot key
+				event or an ACPI sleep button
+				event. The firmware may
+				refuse to generate further FN+F4
+				key presses until a S3 or S4 ACPI
+				sleep cycle is performed or some
+				time passes.
+
+0x1005	0x04	FN+F5		Radio.  Enables/disables
+				the internal Bluetooth hardware
+				and W-WAN card if left in control
+				of the firmware.  Does not affect
+				the WLAN card.
+				Should be used to turn on/off all
+				radios (Bluetooth+W-WAN+WLAN),
+				really.
+
+0x1006	0x05	FN+F6		-
+
+0x1007	0x06	FN+F7		Video output cycle.
+				Do you feel lucky today?
+
+0x1008	0x07	FN+F8		IBM: toggle screen expand
+				Lenovo: configure UltraNav,
+				or toggle screen expand.
+				On 2024 platforms replaced by
+				0x131f (see below) and on newer
+				platforms (2025 +) keycode is
+				replaced by 0x1401 (see below).
+
+0x1009	0x08	FN+F9		-
+
+...	...	...		...
+
+0x100B	0x0A	FN+F11		-
+
+0x100C	0x0B	FN+F12		Sleep to disk.  You are always
+				supposed to handle it yourself,
+				either through the ACPI event,
+				or through a hotkey event.
+				The firmware may refuse to
+				generate further FN+F12 key
+				press events until a S3 or S4
+				ACPI sleep cycle is performed,
+				or some time passes.
+
+0x100D	0x0C	FN+BACKSPACE	-
+0x100E	0x0D	FN+INSERT	-
+0x100F	0x0E	FN+DELETE	-
+
+0x1010	0x0F	FN+HOME		Brightness up.  This key is
+				always handled by the firmware
+				in IBM ThinkPads, even when
+				unmasked.  Just leave it alone.
+				For Lenovo ThinkPads with a new
+				BIOS, it has to be handled either
+				by the ACPI OSI, or by userspace.
+				The driver does the right thing,
+				never mess with this.
+0x1011	0x10	FN+END		Brightness down.  See brightness
+				up for details.
+
+0x1012	0x11	FN+PGUP		ThinkLight toggle.  This key is
+				always handled by the firmware,
+				even when unmasked.
+
+0x1013	0x12	FN+PGDOWN	-
+
+0x1014	0x13	FN+SPACE	Zoom key
+
+0x1015	0x14	VOLUME UP	Internal mixer volume up. This
+				key is always handled by the
+				firmware, even when unmasked.
+				NOTE: Lenovo seems to be changing
+				this.
+0x1016	0x15	VOLUME DOWN	Internal mixer volume up. This
+				key is always handled by the
+				firmware, even when unmasked.
+				NOTE: Lenovo seems to be changing
+				this.
+0x1017	0x16	MUTE		Mute internal mixer. This
+				key is always handled by the
+				firmware, even when unmasked.
+
+0x1018	0x17	THINKPAD	ThinkPad/Access IBM/Lenovo key
+
+0x1019	0x18	unknown
+
+0x131f	...	FN+F8		Platform Mode change (2024 systems).
+				Implemented in driver.
+
+0x1401	...	FN+F8		Platform Mode change (2025 + systems).
+				Implemented in driver.
+...	...	...
+
+0x1020	0x1F	unknown
+=======	=======	==============	==============================================
+
+The ThinkPad firmware does not allow one to differentiate when most hot
+keys are pressed or released (either that, or we don't know how to, yet).
+For these keys, the driver generates a set of events for a key press and
+immediately issues the same set of events for a key release.  It is
+unknown by the driver if the ThinkPad firmware triggered these events on
+hot key press or release, but the firmware will do it for either one, not
+both.
+
+If a key is mapped to KEY_RESERVED, it generates no input events at all.
+If a key is mapped to KEY_UNKNOWN, it generates an input event that
+includes an scan code.  If a key is mapped to anything else, it will
+generate input device EV_KEY events.
+
+In addition to the EV_KEY events, thinkpad-acpi may also issue EV_SW
+events for switches:
+
+==============	==============================================
+SW_RFKILL_ALL	T60 and later hardware rfkill rocker switch
+SW_TABLET_MODE	Tablet ThinkPads HKEY events 0x5009 and 0x500A
+==============	==============================================
+
+Non hotkey ACPI HKEY event map
+------------------------------
+
+Events that are never propagated by the driver:
+
+======		==================================================
+0x2304		System is waking up from suspend to undock
+0x2305		System is waking up from suspend to eject bay
+0x2404		System is waking up from hibernation to undock
+0x2405		System is waking up from hibernation to eject bay
+0x5001		Lid closed
+0x5002		Lid opened
+0x5009		Tablet swivel: switched to tablet mode
+0x500A		Tablet swivel: switched to normal mode
+0x5010		Brightness level changed/control event
+0x6000		KEYBOARD: Numlock key pressed
+0x6005		KEYBOARD: Fn key pressed (TO BE VERIFIED)
+0x7000		Radio Switch may have changed state
+======		==================================================
+
+
+Events that are propagated by the driver to userspace:
+
+======		=====================================================
+0x2313		ALARM: System is waking up from suspend because
+		the battery is nearly empty
+0x2413		ALARM: System is waking up from hibernation because
+		the battery is nearly empty
+0x3003		Bay ejection (see 0x2x05) complete, can sleep again
+0x3006		Bay hotplug request (hint to power up SATA link when
+		the optical drive tray is ejected)
+0x4003		Undocked (see 0x2x04), can sleep again
+0x4010		Docked into hotplug port replicator (non-ACPI dock)
+0x4011		Undocked from hotplug port replicator (non-ACPI dock)
+0x500B		Tablet pen inserted into its storage bay
+0x500C		Tablet pen removed from its storage bay
+0x6011		ALARM: battery is too hot
+0x6012		ALARM: battery is extremely hot
+0x6021		ALARM: a sensor is too hot
+0x6022		ALARM: a sensor is extremely hot
+0x6030		System thermal table changed
+0x6032		Thermal Control command set completion  (DYTC, Windows)
+0x6040		Nvidia Optimus/AC adapter related (TO BE VERIFIED)
+0x60C0		X1 Yoga 2016, Tablet mode status changed
+0x60F0		Thermal Transformation changed (GMTS, Windows)
+======		=====================================================
+
+Battery nearly empty alarms are a last resort attempt to get the
+operating system to hibernate or shutdown cleanly (0x2313), or shutdown
+cleanly (0x2413) before power is lost.  They must be acted upon, as the
+wake up caused by the firmware will have negated most safety nets...
+
+When any of the "too hot" alarms happen, according to Lenovo the user
+should suspend or hibernate the laptop (and in the case of battery
+alarms, unplug the AC adapter) to let it cool down.  These alarms do
+signal that something is wrong, they should never happen on normal
+operating conditions.
+
+The "extremely hot" alarms are emergencies.  According to Lenovo, the
+operating system is to force either an immediate suspend or hibernate
+cycle, or a system shutdown.  Obviously, something is very wrong if this
+happens.
+
+
+Brightness hotkey notes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+Don't mess with the brightness hotkeys in a Thinkpad.  If you want
+notifications for OSD, use the sysfs backlight class event support.
+
+The driver will issue KEY_BRIGHTNESS_UP and KEY_BRIGHTNESS_DOWN events
+automatically for the cases were userspace has to do something to
+implement brightness changes.  When you override these events, you will
+either fail to handle properly the ThinkPads that require explicit
+action to change backlight brightness, or the ThinkPads that require
+that no action be taken to work properly.
+
+
+Bluetooth
+---------
+
+procfs: /proc/acpi/ibm/bluetooth
+
+sysfs device attribute: bluetooth_enable (deprecated)
+
+sysfs rfkill class: switch "tpacpi_bluetooth_sw"
+
+This feature shows the presence and current state of a ThinkPad
+Bluetooth device in the internal ThinkPad CDC slot.
+
+If the ThinkPad supports it, the Bluetooth state is stored in NVRAM,
+so it is kept across reboots and power-off.
+
+Procfs notes
+^^^^^^^^^^^^
+
+If Bluetooth is installed, the following commands can be used::
+
+	echo enable > /proc/acpi/ibm/bluetooth
+	echo disable > /proc/acpi/ibm/bluetooth
+
+Sysfs notes
+^^^^^^^^^^^
+
+	If the Bluetooth CDC card is installed, it can be enabled /
+	disabled through the "bluetooth_enable" thinkpad-acpi device
+	attribute, and its current status can also be queried.
+
+	enable:
+
+		- 0: disables Bluetooth / Bluetooth is disabled
+		- 1: enables Bluetooth / Bluetooth is enabled.
+
+	Note: this interface has been superseded by the	generic rfkill
+	class.  It has been deprecated, and it will be removed in year
+	2010.
+
+	rfkill controller switch "tpacpi_bluetooth_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+Video output control -- /proc/acpi/ibm/video
+--------------------------------------------
+
+This feature allows control over the devices used for video output -
+LCD, CRT or DVI (if available). The following commands are available::
+
+	echo lcd_enable > /proc/acpi/ibm/video
+	echo lcd_disable > /proc/acpi/ibm/video
+	echo crt_enable > /proc/acpi/ibm/video
+	echo crt_disable > /proc/acpi/ibm/video
+	echo dvi_enable > /proc/acpi/ibm/video
+	echo dvi_disable > /proc/acpi/ibm/video
+	echo auto_enable > /proc/acpi/ibm/video
+	echo auto_disable > /proc/acpi/ibm/video
+	echo expand_toggle > /proc/acpi/ibm/video
+	echo video_switch > /proc/acpi/ibm/video
+
+NOTE:
+  Access to this feature is restricted to processes owning the
+  CAP_SYS_ADMIN capability for safety reasons, as it can interact badly
+  enough with some versions of X.org to crash it.
+
+Each video output device can be enabled or disabled individually.
+Reading /proc/acpi/ibm/video shows the status of each device.
+
+Automatic video switching can be enabled or disabled.  When automatic
+video switching is enabled, certain events (e.g. opening the lid,
+docking or undocking) cause the video output device to change
+automatically. While this can be useful, it also causes flickering
+and, on the X40, video corruption. By disabling automatic switching,
+the flickering or video corruption can be avoided.
+
+The video_switch command cycles through the available video outputs
+(it simulates the behavior of Fn-F7).
+
+Video expansion can be toggled through this feature. This controls
+whether the display is expanded to fill the entire LCD screen when a
+mode with less than full resolution is used. Note that the current
+video expansion status cannot be determined through this feature.
+
+Note that on many models (particularly those using Radeon graphics
+chips) the X driver configures the video card in a way which prevents
+Fn-F7 from working. This also disables the video output switching
+features of this driver, as it uses the same ACPI methods as
+Fn-F7. Video switching on the console should still work.
+
+UPDATE: refer to https://bugs.freedesktop.org/show_bug.cgi?id=2000
+
+
+ThinkLight control
+------------------
+
+procfs: /proc/acpi/ibm/light
+
+sysfs attributes: as per LED class, for the "tpacpi::thinklight" LED
+
+procfs notes
+^^^^^^^^^^^^
+
+The ThinkLight status can be read and set through the procfs interface.  A
+few models which do not make the status available will show the ThinkLight
+status as "unknown". The available commands are::
+
+	echo on  > /proc/acpi/ibm/light
+	echo off > /proc/acpi/ibm/light
+
+sysfs notes
+^^^^^^^^^^^
+
+The ThinkLight sysfs interface is documented by the LED class
+documentation, in Documentation/leds/leds-class.rst.  The ThinkLight LED name
+is "tpacpi::thinklight".
+
+Due to limitations in the sysfs LED class, if the status of the ThinkLight
+cannot be read or if it is unknown, thinkpad-acpi will report it as "off".
+It is impossible to know if the status returned through sysfs is valid.
+
+
+CMOS/UCMS control
+-----------------
+
+procfs: /proc/acpi/ibm/cmos
+
+sysfs device attribute: cmos_command
+
+This feature is mostly used internally by the ACPI firmware to keep the legacy
+CMOS NVRAM bits in sync with the current machine state, and to record this
+state so that the ThinkPad will retain such settings across reboots.
+
+Some of these commands actually perform actions in some ThinkPad models, but
+this is expected to disappear more and more in newer models.  As an example, in
+a T43 and in a X40, commands 12 and 13 still control the ThinkLight state for
+real, but commands 0 to 2 don't control the mixer anymore (they have been
+phased out) and just update the NVRAM.
+
+The range of valid cmos command numbers is 0 to 21, but not all have an
+effect and the behavior varies from model to model.  Here is the behavior
+on the X40 (tpb is the ThinkPad Buttons utility):
+
+	- 0 - Related to "Volume down" key press
+	- 1 - Related to "Volume up" key press
+	- 2 - Related to "Mute on" key press
+	- 3 - Related to "Access IBM" key press
+	- 4 - Related to "LCD brightness up" key press
+	- 5 - Related to "LCD brightness down" key press
+	- 11 - Related to "toggle screen expansion" key press/function
+	- 12 - Related to "ThinkLight on"
+	- 13 - Related to "ThinkLight off"
+	- 14 - Related to "ThinkLight" key press (toggle ThinkLight)
+
+The cmos command interface is prone to firmware split-brain problems, as
+in newer ThinkPads it is just a compatibility layer.  Do not use it, it is
+exported just as a debug tool.
+
+
+LED control
+-----------
+
+procfs: /proc/acpi/ibm/led
+sysfs attributes: as per LED class, see below for names
+
+Some of the LED indicators can be controlled through this feature.  On
+some older ThinkPad models, it is possible to query the status of the
+LED indicators as well.  Newer ThinkPads cannot query the real status
+of the LED indicators.
+
+Because misuse of the LEDs could induce an unaware user to perform
+dangerous actions (like undocking or ejecting a bay device while the
+buses are still active), or mask an important alarm (such as a nearly
+empty battery, or a broken battery), access to most LEDs is
+restricted.
+
+Unrestricted access to all LEDs requires that thinkpad-acpi be
+compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
+Distributions must never enable this option.  Individual users that
+are aware of the consequences are welcome to enabling it.
+
+Audio mute and microphone mute LEDs are supported, but currently not
+visible to userspace. They are used by the snd-hda-intel audio driver.
+
+procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+	echo '<LED number> on' >/proc/acpi/ibm/led
+	echo '<LED number> off' >/proc/acpi/ibm/led
+	echo '<LED number> blink' >/proc/acpi/ibm/led
+
+The <LED number> range is 0 to 15. The set of LEDs that can be
+controlled varies from model to model. Here is the common ThinkPad
+mapping:
+
+	- 0 - power
+	- 1 - battery (orange)
+	- 2 - battery (green)
+	- 3 - UltraBase/dock
+	- 4 - UltraBay
+	- 5 - UltraBase battery slot
+	- 6 - (unknown)
+	- 7 - standby
+	- 8 - dock status 1
+	- 9 - dock status 2
+	- 10, 11 - (unknown)
+	- 12 - thinkvantage
+	- 13, 14, 15 - (unknown)
+
+All of the above can be turned on and off and can be made to blink.
+
+sysfs notes
+^^^^^^^^^^^
+
+The ThinkPad LED sysfs interface is described in detail by the LED class
+documentation, in Documentation/leds/leds-class.rst.
+
+The LEDs are named (in LED ID order, from 0 to 12):
+"tpacpi::power", "tpacpi:orange:batt", "tpacpi:green:batt",
+"tpacpi::dock_active", "tpacpi::bay_active", "tpacpi::dock_batt",
+"tpacpi::unknown_led", "tpacpi::standby", "tpacpi::dock_status1",
+"tpacpi::dock_status2", "tpacpi::unknown_led2", "tpacpi::unknown_led3",
+"tpacpi::thinkvantage".
+
+Due to limitations in the sysfs LED class, if the status of the LED
+indicators cannot be read due to an error, thinkpad-acpi will report it as
+a brightness of zero (same as LED off).
+
+If the thinkpad firmware doesn't support reading the current status,
+trying to read the current LED brightness will just return whatever
+brightness was last written to that attribute.
+
+These LEDs can blink using hardware acceleration.  To request that a
+ThinkPad indicator LED should blink in hardware accelerated mode, use the
+"timer" trigger, and leave the delay_on and delay_off parameters set to
+zero (to request hardware acceleration autodetection).
+
+LEDs that are known not to exist in a given ThinkPad model are not
+made available through the sysfs interface.  If you have a dock and you
+notice there are LEDs listed for your ThinkPad that do not exist (and
+are not in the dock), or if you notice that there are missing LEDs,
+a report to ibm-acpi-devel@lists.sourceforge.net is appreciated.
+
+
+ACPI sounds -- /proc/acpi/ibm/beep
+----------------------------------
+
+The BEEP method is used internally by the ACPI firmware to provide
+audible alerts in various situations. This feature allows the same
+sounds to be triggered manually.
+
+The commands are non-negative integer numbers::
+
+	echo <number> >/proc/acpi/ibm/beep
+
+The valid <number> range is 0 to 17. Not all numbers trigger sounds
+and the sounds vary from model to model. Here is the behavior on the
+X40:
+
+	- 0 - stop a sound in progress (but use 17 to stop 16)
+	- 2 - two beeps, pause, third beep ("low battery")
+	- 3 - single beep
+	- 4 - high, followed by low-pitched beep ("unable")
+	- 5 - single beep
+	- 6 - very high, followed by high-pitched beep ("AC/DC")
+	- 7 - high-pitched beep
+	- 9 - three short beeps
+	- 10 - very long beep
+	- 12 - low-pitched beep
+	- 15 - three high-pitched beeps repeating constantly, stop with 0
+	- 16 - one medium-pitched beep repeating constantly, stop with 17
+	- 17 - stop 16
+
+
+Temperature sensors
+-------------------
+
+procfs: /proc/acpi/ibm/thermal
+
+sysfs device attributes: (hwmon "thinkpad") temp*_input
+
+Most ThinkPads include six or more separate temperature sensors but only
+expose the CPU temperature through the standard ACPI methods.  This
+feature shows readings from up to eight different sensors on older
+ThinkPads, and up to sixteen different sensors on newer ThinkPads.
+
+For example, on the X40, a typical output may be:
+
+temperatures:
+	42 42 45 41 36 -128 33 -128
+
+On the T43/p, a typical output may be:
+
+temperatures:
+	48 48 36 52 38 -128 31 -128 48 52 48 -128 -128 -128 -128 -128
+
+The mapping of thermal sensors to physical locations varies depending on
+system-board model (and thus, on ThinkPad model).
+
+https://thinkwiki.org/wiki/Thermal_Sensors is a public wiki page that
+tries to track down these locations for various models.
+
+Most (newer?) models seem to follow this pattern:
+
+- 1:  CPU
+- 2:  (depends on model)
+- 3:  (depends on model)
+- 4:  GPU
+- 5:  Main battery: main sensor
+- 6:  Bay battery: main sensor
+- 7:  Main battery: secondary sensor
+- 8:  Bay battery: secondary sensor
+- 9-15: (depends on model)
+
+For the R51 (source: Thomas Gruber):
+
+- 2:  Mini-PCI
+- 3:  Internal HDD
+
+For the T43, T43/p (source: Shmidoax/Thinkwiki.org)
+https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_T43.2C_T43p
+
+- 2:  System board, left side (near PCMCIA slot), reported as HDAPS temp
+- 3:  PCMCIA slot
+- 9:  MCH (northbridge) to DRAM Bus
+- 10: Clock-generator, mini-pci card and ICH (southbridge), under Mini-PCI
+      card, under touchpad
+- 11: Power regulator, underside of system board, below F2 key
+
+The A31 has a very atypical layout for the thermal sensors
+(source: Milos Popovic, https://thinkwiki.org/wiki/Thermal_Sensors#ThinkPad_A31)
+
+- 1:  CPU
+- 2:  Main Battery: main sensor
+- 3:  Power Converter
+- 4:  Bay Battery: main sensor
+- 5:  MCH (northbridge)
+- 6:  PCMCIA/ambient
+- 7:  Main Battery: secondary sensor
+- 8:  Bay Battery: secondary sensor
+
+
+Procfs notes
+^^^^^^^^^^^^
+
+	Readings from sensors that are not available return -128.
+	No commands can be written to this file.
+
+Sysfs notes
+^^^^^^^^^^^
+
+	Sensors that are not available return the ENXIO error.  This
+	status may change at runtime, as there are hotplug thermal
+	sensors, like those inside the batteries and docks.
+
+	thinkpad-acpi thermal sensors are reported through the hwmon
+	subsystem, and follow all of the hwmon guidelines at
+	Documentation/hwmon.
+
+EXPERIMENTAL: Embedded controller register dump
+-----------------------------------------------
+
+This feature is not included in the thinkpad driver anymore.
+Instead the EC can be accessed through /sys/kernel/debug/ec with
+a userspace tool which can be found here:
+ftp://ftp.suse.com/pub/people/trenn/sources/ec
+
+Use it to determine the register holding the fan
+speed on some models. To do that, do the following:
+
+	- make sure the battery is fully charged
+	- make sure the fan is running
+	- use above mentioned tool to read out the EC
+
+Often fan and temperature values vary between
+readings. Since temperatures don't change vary fast, you can take
+several quick dumps to eliminate them.
+
+You can use a similar method to figure out the meaning of other
+embedded controller registers - e.g. make sure nothing else changes
+except the charging or discharging battery to determine which
+registers contain the current battery capacity, etc. If you experiment
+with this, do send me your results (including some complete dumps with
+a description of the conditions when they were taken.)
+
+
+LCD brightness control
+----------------------
+
+procfs: /proc/acpi/ibm/brightness
+
+sysfs backlight device "thinkpad_screen"
+
+This feature allows software control of the LCD brightness on ThinkPad
+models which don't have a hardware brightness slider.
+
+It has some limitations: the LCD backlight cannot be actually turned
+on or off by this interface, it just controls the backlight brightness
+level.
+
+On IBM (and some of the earlier Lenovo) ThinkPads, the backlight control
+has eight brightness levels, ranging from 0 to 7.  Some of the levels
+may not be distinct.  Later Lenovo models that implement the ACPI
+display backlight brightness control methods have 16 levels, ranging
+from 0 to 15.
+
+For IBM ThinkPads, there are two interfaces to the firmware for direct
+brightness control, EC and UCMS (or CMOS).  To select which one should be
+used, use the brightness_mode module parameter: brightness_mode=1 selects
+EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
+mode with NVRAM backing (so that brightness changes are remembered across
+shutdown/reboot).
+
+The driver tries to select which interface to use from a table of
+defaults for each ThinkPad model.  If it makes a wrong choice, please
+report this as a bug, so that we can fix it.
+
+Lenovo ThinkPads only support brightness_mode=2 (UCMS).
+
+When display backlight brightness controls are available through the
+standard ACPI interface, it is best to use it instead of this direct
+ThinkPad-specific interface.  The driver will disable its native
+backlight brightness control interface if it detects that the standard
+ACPI interface is available in the ThinkPad.
+
+If you want to use the thinkpad-acpi backlight brightness control
+instead of the generic ACPI video backlight brightness control for some
+reason, you should use the acpi_backlight=vendor kernel parameter.
+
+The brightness_enable module parameter can be used to control whether
+the LCD brightness control feature will be enabled when available.
+brightness_enable=0 forces it to be disabled.  brightness_enable=1
+forces it to be enabled when available, even if the standard ACPI
+interface is also available.
+
+Procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+	echo up   >/proc/acpi/ibm/brightness
+	echo down >/proc/acpi/ibm/brightness
+	echo 'level <level>' >/proc/acpi/ibm/brightness
+
+Sysfs notes
+^^^^^^^^^^^
+
+The interface is implemented through the backlight sysfs class, which is
+poorly documented at this time.
+
+Locate the thinkpad_screen device under /sys/class/backlight, and inside
+it there will be the following attributes:
+
+	max_brightness:
+		Reads the maximum brightness the hardware can be set to.
+		The minimum is always zero.
+
+	actual_brightness:
+		Reads what brightness the screen is set to at this instant.
+
+	brightness:
+		Writes request the driver to change brightness to the
+		given value.  Reads will tell you what brightness the
+		driver is trying to set the display to when "power" is set
+		to zero and the display has not been dimmed by a kernel
+		power management event.
+
+	power:
+		power management mode, where 0 is "display on", and 1 to 3
+		will dim the display backlight to brightness level 0
+		because thinkpad-acpi cannot really turn the backlight
+		off.  Kernel power management events can temporarily
+		increase the current power management level, i.e. they can
+		dim the display.
+
+
+WARNING:
+
+    Whatever you do, do NOT ever call thinkpad-acpi backlight-level change
+    interface and the ACPI-based backlight level change interface
+    (available on newer BIOSes, and driven by the Linux ACPI video driver)
+    at the same time.  The two will interact in bad ways, do funny things,
+    and maybe reduce the life of the backlight lamps by needlessly kicking
+    its level up and down at every change.
+
+
+Volume control (Console Audio control)
+--------------------------------------
+
+procfs: /proc/acpi/ibm/volume
+
+ALSA: "ThinkPad Console Audio Control", default ID: "ThinkPadEC"
+
+NOTE: by default, the volume control interface operates in read-only
+mode, as it is supposed to be used for on-screen-display purposes.
+The read/write mode can be enabled through the use of the
+"volume_control=1" module parameter.
+
+NOTE: distros are urged to not enable volume_control by default, this
+should be done by the local admin only.  The ThinkPad UI is for the
+console audio control to be done through the volume keys only, and for
+the desktop environment to just provide on-screen-display feedback.
+Software volume control should be done only in the main AC97/HDA
+mixer.
+
+
+About the ThinkPad Console Audio control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+ThinkPads have a built-in amplifier and muting circuit that drives the
+console headphone and speakers.  This circuit is after the main AC97
+or HDA mixer in the audio path, and under exclusive control of the
+firmware.
+
+ThinkPads have three special hotkeys to interact with the console
+audio control: volume up, volume down and mute.
+
+It is worth noting that the normal way the mute function works (on
+ThinkPads that do not have a "mute LED") is:
+
+1. Press mute to mute.  It will *always* mute, you can press it as
+   many times as you want, and the sound will remain mute.
+
+2. Press either volume key to unmute the ThinkPad (it will _not_
+   change the volume, it will just unmute).
+
+This is a very superior design when compared to the cheap software-only
+mute-toggle solution found on normal consumer laptops:  you can be
+absolutely sure the ThinkPad will not make noise if you press the mute
+button, no matter the previous state.
+
+The IBM ThinkPads, and the earlier Lenovo ThinkPads have variable-gain
+amplifiers driving the speakers and headphone output, and the firmware
+also handles volume control for the headphone and speakers on these
+ThinkPads without any help from the operating system (this volume
+control stage exists after the main AC97 or HDA mixer in the audio
+path).
+
+The newer Lenovo models only have firmware mute control, and depend on
+the main HDA mixer to do volume control (which is done by the operating
+system).  In this case, the volume keys are filtered out for unmute
+key press (there are some firmware bugs in this area) and delivered as
+normal key presses to the operating system (thinkpad-acpi is not
+involved).
+
+
+The ThinkPad-ACPI volume control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The preferred way to interact with the Console Audio control is the
+ALSA interface.
+
+The legacy procfs interface allows one to read the current state,
+and if volume control is enabled, accepts the following commands::
+
+	echo up   >/proc/acpi/ibm/volume
+	echo down >/proc/acpi/ibm/volume
+	echo mute >/proc/acpi/ibm/volume
+	echo unmute >/proc/acpi/ibm/volume
+	echo 'level <level>' >/proc/acpi/ibm/volume
+
+The <level> number range is 0 to 14 although not all of them may be
+distinct. To unmute the volume after the mute command, use either the
+up or down command (the level command will not unmute the volume), or
+the unmute command.
+
+You can use the volume_capabilities parameter to tell the driver
+whether your thinkpad has volume control or mute-only control:
+volume_capabilities=1 for mixers with mute and volume control,
+volume_capabilities=2 for mixers with only mute control.
+
+If the driver misdetects the capabilities for your ThinkPad model,
+please report this to ibm-acpi-devel@lists.sourceforge.net, so that we
+can update the driver.
+
+There are two strategies for volume control.  To select which one
+should be used, use the volume_mode module parameter: volume_mode=1
+selects EC mode, and volume_mode=3 selects EC mode with NVRAM backing
+(so that volume/mute changes are remembered across shutdown/reboot).
+
+The driver will operate in volume_mode=3 by default. If that does not
+work well on your ThinkPad model, please report this to
+ibm-acpi-devel@lists.sourceforge.net.
+
+The driver supports the standard ALSA module parameters.  If the ALSA
+mixer is disabled, the driver will disable all volume functionality.
+
+
+Fan control and monitoring: fan speed, fan enable/disable
+---------------------------------------------------------
+
+procfs: /proc/acpi/ibm/fan
+
+sysfs device attributes: (hwmon "thinkpad") fan1_input, pwm1, pwm1_enable, fan2_input
+
+sysfs hwmon driver attributes: fan_watchdog
+
+NOTE NOTE NOTE:
+   fan control operations are disabled by default for
+   safety reasons.  To enable them, the module parameter "fan_control=1"
+   must be given to thinkpad-acpi.
+
+This feature attempts to show the current fan speed, control mode and
+other fan data that might be available.  The speed is read directly
+from the hardware registers of the embedded controller.  This is known
+to work on later R, T, X and Z series ThinkPads but may show a bogus
+value on other models.
+
+Some Lenovo ThinkPads support a secondary fan.  This fan cannot be
+controlled separately, it shares the main fan control.
+
+Fan levels
+^^^^^^^^^^
+
+Most ThinkPad fans work in "levels" at the firmware interface.  Level 0
+stops the fan.  The higher the level, the higher the fan speed, although
+adjacent levels often map to the same fan speed.  7 is the highest
+level, where the fan reaches the maximum recommended speed.
+
+Level "auto" means the EC changes the fan level according to some
+internal algorithm, usually based on readings from the thermal sensors.
+
+There is also a "full-speed" level, also known as "disengaged" level.
+In this level, the EC disables the speed-locked closed-loop fan control,
+and drives the fan as fast as it can go, which might exceed hardware
+limits, so use this level with caution.
+
+The fan usually ramps up or down slowly from one speed to another, and
+it is normal for the EC to take several seconds to react to fan
+commands.  The full-speed level may take up to two minutes to ramp up to
+maximum speed, and in some ThinkPads, the tachometer readings go stale
+while the EC is transitioning to the full-speed level.
+
+WARNING WARNING WARNING: do not leave the fan disabled unless you are
+monitoring all of the temperature sensor readings and you are ready to
+enable it if necessary to avoid overheating.
+
+An enabled fan in level "auto" may stop spinning if the EC decides the
+ThinkPad is cool enough and doesn't need the extra airflow.  This is
+normal, and the EC will spin the fan up if the various thermal readings
+rise too much.
+
+On the X40, this seems to depend on the CPU and HDD temperatures.
+Specifically, the fan is turned on when either the CPU temperature
+climbs to 56 degrees or the HDD temperature climbs to 46 degrees.  The
+fan is turned off when the CPU temperature drops to 49 degrees and the
+HDD temperature drops to 41 degrees.  These thresholds cannot
+currently be controlled.
+
+The ThinkPad's ACPI DSDT code will reprogram the fan on its own when
+certain conditions are met.  It will override any fan programming done
+through thinkpad-acpi.
+
+The thinkpad-acpi kernel driver can be programmed to revert the fan
+level to a safe setting if userspace does not issue one of the procfs
+fan commands: "enable", "disable", "level" or "watchdog", or if there
+are no writes to pwm1_enable (or to pwm1 *if and only if* pwm1_enable is
+set to 1, manual mode) within a configurable amount of time of up to
+120 seconds.  This functionality is called fan safety watchdog.
+
+Note that the watchdog timer stops after it enables the fan.  It will be
+rearmed again automatically (using the same interval) when one of the
+above mentioned fan commands is received.  The fan watchdog is,
+therefore, not suitable to protect against fan mode changes made through
+means other than the "enable", "disable", and "level" procfs fan
+commands, or the hwmon fan control sysfs interface.
+
+Procfs notes
+^^^^^^^^^^^^
+
+The fan may be enabled or disabled with the following commands::
+
+	echo enable  >/proc/acpi/ibm/fan
+	echo disable >/proc/acpi/ibm/fan
+
+Placing a fan on level 0 is the same as disabling it.  Enabling a fan
+will try to place it in a safe level if it is too slow or disabled.
+
+The fan level can be controlled with the command::
+
+	echo 'level <level>' > /proc/acpi/ibm/fan
+
+Where <level> is an integer from 0 to 7, or one of the words "auto" or
+"full-speed" (without the quotes).  Not all ThinkPads support the "auto"
+and "full-speed" levels.  The driver accepts "disengaged" as an alias for
+"full-speed", and reports it as "disengaged" for backwards
+compatibility.
+
+On the X31 and X40 (and ONLY on those models), the fan speed can be
+controlled to a certain degree.  Once the fan is running, it can be
+forced to run faster or slower with the following command::
+
+	echo 'speed <speed>' > /proc/acpi/ibm/fan
+
+The sustainable range of fan speeds on the X40 appears to be from about
+3700 to about 7350. Values outside this range either do not have any
+effect or the fan speed eventually settles somewhere in that range.  The
+fan cannot be stopped or started with this command.  This functionality
+is incomplete, and not available through the sysfs interface.
+
+To program the safety watchdog, use the "watchdog" command::
+
+	echo 'watchdog <interval in seconds>' > /proc/acpi/ibm/fan
+
+If you want to disable the watchdog, use 0 as the interval.
+
+Sysfs notes
+^^^^^^^^^^^
+
+The sysfs interface follows the hwmon subsystem guidelines for the most
+part, and the exception is the fan safety watchdog.
+
+Writes to any of the sysfs attributes may return the EINVAL error if
+that operation is not supported in a given ThinkPad or if the parameter
+is out-of-bounds, and EPERM if it is forbidden.  They may also return
+EINTR (interrupted system call), and EIO (I/O error while trying to talk
+to the firmware).
+
+Features not yet implemented by the driver return ENOSYS.
+
+hwmon device attribute pwm1_enable:
+	- 0: PWM offline (fan is set to full-speed mode)
+	- 1: Manual PWM control (use pwm1 to set fan level)
+	- 2: Hardware PWM control (EC "auto" mode)
+	- 3: reserved (Software PWM control, not implemented yet)
+
+	Modes 0 and 2 are not supported by all ThinkPads, and the
+	driver is not always able to detect this.  If it does know a
+	mode is unsupported, it will return -EINVAL.
+
+hwmon device attribute pwm1:
+	Fan level, scaled from the firmware values of 0-7 to the hwmon
+	scale of 0-255.  0 means fan stopped, 255 means highest normal
+	speed (level 7).
+
+	This attribute only commands the fan if pmw1_enable is set to 1
+	(manual PWM control).
+
+hwmon device attribute fan1_input:
+	Fan tachometer reading, in RPM.  May go stale on certain
+	ThinkPads while the EC transitions the PWM to offline mode,
+	which can take up to two minutes.  May return rubbish on older
+	ThinkPads.
+
+hwmon device attribute fan2_input:
+	Fan tachometer reading, in RPM, for the secondary fan.
+	Available only on some ThinkPads.  If the secondary fan is
+	not installed, will always read 0.
+
+hwmon driver attribute fan_watchdog:
+	Fan safety watchdog timer interval, in seconds.  Minimum is
+	1 second, maximum is 120 seconds.  0 disables the watchdog.
+
+To stop the fan: set pwm1 to zero, and pwm1_enable to 1.
+
+To start the fan in a safe mode: set pwm1_enable to 2.  If that fails
+with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255
+would be the safest choice, though).
+
+
+WAN
+---
+
+procfs: /proc/acpi/ibm/wan
+
+sysfs device attribute: wwan_enable (deprecated)
+
+sysfs rfkill class: switch "tpacpi_wwan_sw"
+
+This feature shows the presence and current state of the built-in
+Wireless WAN device.
+
+If the ThinkPad supports it, the WWAN state is stored in NVRAM,
+so it is kept across reboots and power-off.
+
+It was tested on a Lenovo ThinkPad X60. It should probably work on other
+ThinkPad models which come with this module installed.
+
+Procfs notes
+^^^^^^^^^^^^
+
+If the W-WAN card is installed, the following commands can be used::
+
+	echo enable > /proc/acpi/ibm/wan
+	echo disable > /proc/acpi/ibm/wan
+
+Sysfs notes
+^^^^^^^^^^^
+
+	If the W-WAN card is installed, it can be enabled /
+	disabled through the "wwan_enable" thinkpad-acpi device
+	attribute, and its current status can also be queried.
+
+	enable:
+		- 0: disables WWAN card / WWAN card is disabled
+		- 1: enables WWAN card / WWAN card is enabled.
+
+	Note: this interface has been superseded by the	generic rfkill
+	class.  It has been deprecated, and it will be removed in year
+	2010.
+
+	rfkill controller switch "tpacpi_wwan_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+LCD Shadow control
+------------------
+
+procfs: /proc/acpi/ibm/lcdshadow
+
+Some newer T480s and T490s ThinkPads provide a feature called
+PrivacyGuard. By turning this feature on, the usable vertical and
+horizontal viewing angles of the LCD can be limited (as if some privacy
+screen was applied manually in front of the display).
+
+procfs notes
+^^^^^^^^^^^^
+
+The available commands are::
+
+	echo '0' >/proc/acpi/ibm/lcdshadow
+	echo '1' >/proc/acpi/ibm/lcdshadow
+
+The first command ensures the best viewing angle and the latter one turns
+on the feature, restricting the viewing angles.
+
+
+DYTC Lapmode sensor
+-------------------
+
+sysfs: dytc_lapmode
+
+Newer thinkpads and mobile workstations have the ability to determine if
+the device is in deskmode or lapmode. This feature is used by user space
+to decide if WWAN transmission can be increased to maximum power and is
+also useful for understanding the different thermal modes available as
+they differ between desk and lap mode.
+
+The property is read-only. If the platform doesn't have support the sysfs
+class is not created.
+
+EXPERIMENTAL: UWB
+-----------------
+
+This feature is considered EXPERIMENTAL because it has not been extensively
+tested and validated in various ThinkPad models yet.  The feature may not
+work as expected. USE WITH CAUTION! To use this feature, you need to supply
+the experimental=1 parameter when loading the module.
+
+sysfs rfkill class: switch "tpacpi_uwb_sw"
+
+This feature exports an rfkill controller for the UWB device, if one is
+present and enabled in the BIOS.
+
+Sysfs notes
+^^^^^^^^^^^
+
+	rfkill controller switch "tpacpi_uwb_sw": refer to
+	Documentation/driver-api/rfkill.rst for details.
+
+
+Setting keyboard language
+-------------------------
+
+sysfs: keyboard_lang
+
+This feature is used to set keyboard language to ECFW using ASL interface.
+Fewer thinkpads models like T580 , T590 , T15 Gen 1 etc.. has "=", "(',
+")" numeric keys, which are not displaying correctly, when keyboard language
+is other than "english". This is because the default keyboard language in ECFW
+is set as "english". Hence using this sysfs, user can set the correct keyboard
+language to ECFW and then these key's will work correctly.
+
+Example of command to set keyboard language is mentioned below::
+
+        echo jp > /sys/devices/platform/thinkpad_acpi/keyboard_lang
+
+Text corresponding to keyboard layout to be set in sysfs are: be(Belgian),
+cz(Czech), da(Danish), de(German), en(English), es(Spain), et(Estonian),
+fr(French), fr-ch(French(Switzerland)), hu(Hungarian), it(Italy), jp (Japan),
+nl(Dutch), nn(Norway), pl(Polish), pt(portuguese), sl(Slovenian), sv(Sweden),
+tr(Turkey)
+
+WWAN Antenna type
+-----------------
+
+sysfs: wwan_antenna_type
+
+On some newer Thinkpads we need to set SAR value based on the antenna
+type. This interface will be used by userspace to get the antenna type
+and set the corresponding SAR value, as is required for FCC certification.
+
+The available commands are::
+
+        cat /sys/devices/platform/thinkpad_acpi/wwan_antenna_type
+
+Currently 2 antenna types are supported as mentioned below:
+- type a
+- type b
+
+The property is read-only. If the platform doesn't have support the sysfs
+class is not created.
+
+doubletap_enable
+----------------
+
+sysfs: doubletap_enable
+
+Controls whether TrackPoint doubletap events are filtered out. Doubletap is a
+feature where quickly tapping the TrackPoint twice triggers a special function key event.
+
+The available commands are::
+
+                cat /sys/devices/platform/thinkpad_acpi/doubletap_enable
+                echo 1 | sudo tee /sys/devices/platform/thinkpad_acpi/doubletap_enable
+                echo 0 | sudo tee /sys/devices/platform/thinkpad_acpi/doubletap_enable
+
+Values:
+
+	* 1 - doubletap events are processed (default)
+	* 0 - doubletap events are filtered out (ignored)
+
+	This setting can also be toggled via the Fn+doubletap hotkey.
+
+USB-C Security
+--------------
+
+sysfs: usb_c_security
+
+Reports the current state of the USB-C Security (Restricted Mode) feature
+on supported ThinkPad systems. When enabled, USB-C data connections are
+disabled while power delivery is preserved.
+
+The available command is::
+
+        cat /sys/devices/platform/thinkpad_acpi/usb_c_security
+
+Values:
+
+	* ``enabled``  - USB-C data connections are currently blocked
+	* ``disabled`` - USB-C data connections are currently allowed
+
+The attribute is read-only. The USB-C Security state can only be toggled
+via the Fn+U followed by Fn+S hotkey chord.
+
+The sysfs attribute is not created on platforms that do not support this
+feature.
+
+Auxmac
+------
+
+sysfs: auxmac
+
+Some newer Thinkpads have a feature called MAC Address Pass-through. This
+feature is implemented by the system firmware to provide a system unique MAC,
+that can override a dock or USB ethernet dongle MAC, when connected to a
+network. This property enables user-space to easily determine the MAC address
+if the feature is enabled.
+
+The values of this auxiliary MAC are:
+
+        cat /sys/devices/platform/thinkpad_acpi/auxmac
+
+If the feature is disabled, the value will be 'disabled'.
+
+This property is read-only.
+
+Adaptive keyboard
+-----------------
+
+sysfs device attribute: adaptive_kbd_mode
+
+This sysfs attribute controls the keyboard "face" that will be shown on the
+Lenovo X1 Carbon 2nd gen (2014)'s adaptive keyboard. The value can be read
+and set.
+
+- 0 = Home mode
+- 1 = Web-browser mode
+- 2 = Web-conference mode
+- 3 = Function mode
+- 4 = Layflat mode
+
+For more details about which buttons will appear depending on the mode, please
+review the laptop's user guide:
+https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/x1carbon_2_ug_en.pdf
+
+Battery charge control
+----------------------
+
+sysfs attributes:
+/sys/class/power_supply/BAT*/charge_control_{start,end}_threshold
+
+These two attributes are created for those batteries that are supported by the
+driver. They enable the user to control the battery charge thresholds of the
+given battery. Both values may be read and set. `charge_control_start_threshold`
+accepts an integer between 0 and 99 (inclusive); this value represents a battery
+percentage level, below which charging will begin. `charge_control_end_threshold`
+accepts an integer between 1 and 100 (inclusive); this value represents a battery
+percentage level, above which charging will stop.
+
+The exact semantics of the attributes may be found in
+Documentation/ABI/testing/sysfs-class-power.
+
+Hardware damage detection capability
+------------------------------------
+
+sysfs attributes: hwdd_status, hwdd_detail
+
+Thinkpads are adding the ability to detect and report hardware damage.
+Add new sysfs interface to identify the damaged device status.
+Initial support is available for the USB-C replaceable connector.
+
+The command to check device damaged status is::
+
+        cat /sys/devices/platform/thinkpad_acpi/hwdd_status
+
+This value displays status of device damaged.
+
+- 0 = Not Damaged
+- 1 = Damaged
+
+The command to check location of damaged device is::
+
+        cat /sys/devices/platform/thinkpad_acpi/hwdd_detail
+
+This value displays location of damaged device having 1 line per damaged "item".
+For example:
+
+if no damage is detected:
+
+- No damage detected
+
+if damage detected:
+
+- TYPE-C: Base, Right side, Center port
+
+The property is read-only. If feature is not supported then sysfs
+attribute is not created.
+
+Multiple Commands, Module Parameters
+------------------------------------
+
+Multiple commands can be written to the proc files in one shot by
+separating them with commas, for example::
+
+	echo enable,0xffff > /proc/acpi/ibm/hotkey
+	echo lcd_disable,crt_enable > /proc/acpi/ibm/video
+
+Commands can also be specified when loading the thinkpad-acpi module,
+for example::
+
+	modprobe thinkpad_acpi hotkey=enable,0xffff video=auto_disable
+
+
+Enabling debugging output
+-------------------------
+
+The module takes a debug parameter which can be used to selectively
+enable various classes of debugging output, for example::
+
+	 modprobe thinkpad_acpi debug=0xffff
+
+will enable all debugging output classes.  It takes a bitmask, so
+to enable more than one output class, just add their values.
+
+	=============		======================================
+	Debug bitmask		Description
+	=============		======================================
+	0x8000			Disclose PID of userspace programs
+				accessing some functions of the driver
+	0x0001			Initialization and probing
+	0x0002			Removal
+	0x0004			RF Transmitter control (RFKILL)
+				(bluetooth, WWAN, UWB...)
+	0x0008			HKEY event interface, hotkeys
+	0x0010			Fan control
+	0x0020			Backlight brightness
+	0x0040			Audio mixer/volume control
+	=============		======================================
+
+There is also a kernel build option to enable more debugging
+information, which may be necessary to debug driver problems.
+
+The level of debugging information output by the driver can be changed
+at runtime through sysfs, using the driver attribute debug_level.  The
+attribute takes the same bitmask as the debug module parameter above.
+
+
+Force loading of module
+-----------------------
+
+If thinkpad-acpi refuses to detect your ThinkPad, you can try to specify
+the module parameter force_load=1.  Regardless of whether this works or
+not, please contact ibm-acpi-devel@lists.sourceforge.net with a report.
+
+
+Sysfs interface changelog
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+=========	===============================================================
+0x000100:	Initial sysfs support, as a single platform driver and
+		device.
+0x000200:	Hot key support for 32 hot keys, and radio slider switch
+		support.
+0x010000:	Hot keys are now handled by default over the input
+		layer, the radio switch generates input event EV_RADIO,
+		and the driver enables hot key handling by default in
+		the firmware.
+
+0x020000:	ABI fix: added a separate hwmon platform device and
+		driver, which must be located by name (thinkpad)
+		and the hwmon class for libsensors4 (lm-sensors 3)
+		compatibility.  Moved all hwmon attributes to this
+		new platform device.
+
+0x020100:	Marker for thinkpad-acpi with hot key NVRAM polling
+		support.  If you must, use it to know you should not
+		start a userspace NVRAM poller (allows to detect when
+		NVRAM is compiled out by the user because it is
+		unneeded/undesired in the first place).
+0x020101:	Marker for thinkpad-acpi with hot key NVRAM polling
+		and proper hotkey_mask semantics (version 8 of the
+		NVRAM polling patch).  Some development snapshots of
+		0.18 had an earlier version that did strange things
+		to hotkey_mask.
+
+0x020200:	Add poll()/select() support to the following attributes:
+		hotkey_radio_sw, wakeup_hotunplug_complete, wakeup_reason
+
+0x020300:	hotkey enable/disable support removed, attributes
+		hotkey_bios_enabled and hotkey_enable deprecated and
+		marked for removal.
+
+0x020400:	Marker for 16 LEDs support.  Also, LEDs that are known
+		to not exist in a given model are not registered with
+		the LED sysfs class anymore.
+
+0x020500:	Updated hotkey driver, hotkey_mask is always available
+		and it is always able to disable hot keys.  Very old
+		thinkpads are properly supported.  hotkey_bios_mask
+		is deprecated and marked for removal.
+
+0x020600:	Marker for backlight change event support.
+
+0x020700:	Support for mute-only mixers.
+		Volume control in read-only mode by default.
+		Marker for ALSA mixer support.
+
+0x030000:	Thermal and fan sysfs attributes were moved to the hwmon
+		device instead of being attached to the backing platform
+		device.
+=========	===============================================================
diff --git a/Documentation/admin-guide/laptops/toshiba_haps.rst b/Documentation/admin-guide/laptops/toshiba_haps.rst
new file mode 100644
index 000000000..0226225b8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/toshiba_haps.rst
@@ -0,0 +1,87 @@
+====================================
+Toshiba HDD Active Protection Sensor
+====================================
+
+Kernel driver: toshiba_haps
+
+Author: Azael Avalos <coproscefalo@gmail.com>
+
+
+.. 0. Contents
+
+   1. Description
+   2. Interface
+   3. Accelerometer axes
+   4. Supported devices
+   5. Usage
+
+
+1. Description
+--------------
+
+This driver provides support for the accelerometer found in various Toshiba
+laptops, being called "Toshiba HDD Protection - Shock Sensor" officially,
+and detects laptops automatically with this device.
+On Windows, Toshiba provided software monitors this device and provides
+automatic HDD protection (head unload) on sudden moves or harsh vibrations,
+however, this driver only provides a notification via a sysfs file to let
+userspace tools or daemons act accordingly, as well as providing a sysfs
+file to set the desired protection level or sensor sensibility.
+
+
+2. Interface
+------------
+
+This device comes with 3 methods:
+
+====	=====================================================================
+_STA    Checks existence of the device, returning Zero if the device does not
+	exists or is not supported.
+PTLV    Sets the desired protection level.
+RSSS    Shuts down the HDD protection interface for a few seconds,
+	then restores normal operation.
+====	=====================================================================
+
+Note:
+  The presence of Solid State Drives (SSD) can cause this driver to fail loading,
+  given the fact that such drives have no movable parts, and thus, not requiring
+  any "protection" as well as failing during the evaluation of the _STA method
+  found under this device.
+
+
+3. Accelerometer axes
+---------------------
+
+This device does not report any axes, however, to query the sensor position
+a couple HCI (Hardware Configuration Interface) calls (0x6D and 0xA6) are
+provided to query such information, handled by the kernel module toshiba_acpi
+since kernel version 3.15.
+
+
+4. Supported devices
+--------------------
+
+This driver binds itself to the ACPI device TOS620A, and any Toshiba laptop
+with this device is supported, given the fact that they have the presence of
+conventional HDD and not only SSD, or a combination of both HDD and SSD.
+
+
+5. Usage
+--------
+
+The sysfs files under /sys/devices/LNXSYSTM:00/LNXSYBUS:00/TOS620A:00/ are:
+
+================   ============================================================
+protection_level   The protection_level is readable and writeable, and
+		   provides a way to let userspace query the current protection
+		   level, as well as set the desired protection level, the
+		   available protection levels are::
+
+		     ============   =======   ==========   ========
+		     0 - Disabled   1 - Low   2 - Medium   3 - High
+		     ============   =======   ==========   ========
+
+reset_protection   The reset_protection entry is writeable only, being "1"
+		   the only parameter it accepts, it is used to trigger
+		   a reset of the protection interface.
+================   ============================================================
diff --git a/Documentation/admin-guide/laptops/uniwill-laptop.rst b/Documentation/admin-guide/laptops/uniwill-laptop.rst
new file mode 100644
index 000000000..be50b45b8
--- /dev/null
+++ b/Documentation/admin-guide/laptops/uniwill-laptop.rst
@@ -0,0 +1,118 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Uniwill laptop extra features
+=============================
+
+On laptops manufactured by Uniwill (either directly or as ODM), the ``uniwill-laptop`` driver
+handles various platform-specific features.
+
+Module Loading
+--------------
+
+The ``uniwill-laptop`` driver relies on a DMI table to automatically load on supported devices.
+When using the ``force`` module parameter, this DMI check will be omitted, allowing the driver
+to be loaded on unsupported devices for testing purposes.
+
+Hotkeys
+-------
+
+Usually the FN keys work without a special driver. However as soon as the ``uniwill-laptop`` driver
+is loaded, the FN keys need to be handled manually. This is done automatically by the driver itself.
+
+Keyboard settings
+-----------------
+
+The ``uniwill-laptop`` driver allows the user to enable/disable:
+
+ - the FN lock and super key of the integrated keyboard
+ - the touchpad toggle functionality of the integrated touchpad
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+Hwmon interface
+---------------
+
+The ``uniwill-laptop`` driver supports reading of the CPU and GPU temperature and supports up to
+two fans. Userspace applications can access sensor readings over the hwmon sysfs interface.
+
+Platform profile
+----------------
+
+Support for changing the platform performance mode is currently not implemented.
+
+Battery Charging Control
+------------------------
+
+.. warning:: Some devices do not properly implement the charging threshold interface. Forcing
+             the driver to enable access to said interface on such devices might damage the
+             battery [1]_. Because of this the driver will not enable said feature even when
+             using the ``force`` module parameter. The charging profile interface will be
+             available instead.
+
+The ``uniwill-laptop`` driver supports controlling the battery charge limit. This either happens
+over the standard ``charge_control_end_threshold`` or ``charge_types`` power supply sysfs attribute,
+depending on the device. When using the ``charge_control_end_threshold`` sysfs attribute, all values
+between 1 and 100 percent are supported. When using the ``charge_types`` sysfs attribute, the driver
+supports switching between the ``Standard``, ``Trickle`` and ``Long Life`` profiles.
+
+Keep in mind that when using the ``charge_types`` sysfs attribute, the EC firmware will hide the
+true charging status of the battery from the operating system, potentially misleading users into
+thinking that the charging profile does not work. Checking the ``current_now`` sysfs attribute
+tells you the true charging status of the battery even when using the ``charge_types`` sysfs
+attribute (0 means that the battery is currently not charging).
+
+Additionally the driver signals the presence of battery charging issues through the standard
+``health`` power supply sysfs attribute.
+
+It also lets you set whether a USB-C power source should prioritise charging the battery or
+delivering immediate power to the cpu. See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for
+details.
+
+Lightbar
+--------
+
+The ``uniwill-laptop`` driver exposes the lightbar found on some models as a standard multicolor
+LED class device. The default name of this LED class device is ``uniwill:multicolor:status``.
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details on how to control the various
+animation modes of the lightbar.
+
+Keyboard Backlight
+------------------
+
+The ``uniwill-laptop`` driver supports controlling the keyboard backlight using the standard
+LED class interface. The default name of this LED class device is ``uniwill:white:kbd_backlight``
+when the keyboard backlight supports only a single color, or ``uniwill:multicolor:kbd_backlight``
+when the keyboard backlight supports RGB colors. The maximum intensity for each color channel
+in RGB mode is 50.
+
+Keep in mind that due to hardware design choices, the driver does not support the RGB value
+``0x000000`` (black), instead it will fall back to ``0x010101`` (faint white). In order to
+disable the keyboard backlight, the standard LED brightness setting has to be used instead.
+
+Configurable TGP
+----------------
+
+The ``uniwill-laptop`` driver allows to set the configurable TGP for devices with NVIDIA GPUs that
+allow it.
+
+See Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+AC Auto Boot
+------------
+
+The ``uniwill-laptop`` driver allows the user to configure if the system should automatically
+boot when being connected to a power source, see
+Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+USB Powershare
+--------------
+
+The ``uniwill-laptop`` driver allows the user to configure if the system should continue to
+provide power via the USB ports when hibernating or powered off, see
+Documentation/ABI/testing/sysfs-driver-uniwill-laptop for details.
+
+References
+==========
+
+.. [1] https://www.reddit.com/r/XMG_gg/comments/ld9yyf/battery_limit_hidden_function_discovered_on/
diff --git a/Documentation/admin-guide/lcd-panel-cgram.rst b/Documentation/admin-guide/lcd-panel-cgram.rst
new file mode 100644
index 000000000..a3eb00c62
--- /dev/null
+++ b/Documentation/admin-guide/lcd-panel-cgram.rst
@@ -0,0 +1,27 @@
+======================================
+Parallel port LCD/Keypad Panel support
+======================================
+
+Some LCDs allow you to define up to 8 characters, mapped to ASCII
+characters 0 to 7. The escape code to define a new character is
+'\e[LG' followed by one digit from 0 to 7, representing the character
+number, and up to 8 couples of hex digits terminated by a semi-colon
+(';'). Each couple of digits represents a line, with 1-bits for each
+illuminated pixel with LSB on the right. Lines are numbered from the
+top of the character to the bottom. On a 5x7 matrix, only the 5 lower
+bits of the 7 first bytes are used for each character. If the string
+is incomplete, only complete lines will be redefined. Here are some
+examples::
+
+  printf "\e[LG0010101050D1F0C04;"  => 0 = [enter]
+  printf "\e[LG1040E1F0000000000;"  => 1 = [up]
+  printf "\e[LG2000000001F0E0400;"  => 2 = [down]
+  printf "\e[LG3040E1F001F0E0400;"  => 3 = [up-down]
+  printf "\e[LG40002060E1E0E0602;"  => 4 = [left]
+  printf "\e[LG500080C0E0F0E0C08;"  => 5 = [right]
+  printf "\e[LG60016051516141400;"  => 6 = "IP"
+
+  printf "\e[LG00103071F1F070301;"  => big speaker
+  printf "\e[LG00002061E1E060200;"  => small speaker
+
+Willy
diff --git a/Documentation/admin-guide/ldm.rst b/Documentation/admin-guide/ldm.rst
new file mode 100644
index 000000000..12c571368
--- /dev/null
+++ b/Documentation/admin-guide/ldm.rst
@@ -0,0 +1,121 @@
+==========================================
+LDM - Logical Disk Manager (Dynamic Disks)
+==========================================
+
+:Author: Originally Written by FlatCap - Richard Russon <ldm@flatcap.org>.
+:Last Updated: Anton Altaparmakov on 30 March 2007 for Windows Vista.
+
+Overview
+--------
+
+Windows 2000, XP, and Vista use a new partitioning scheme.  It is a complete
+replacement for the MSDOS style partitions.  It stores its information in a
+1MiB journalled database at the end of the physical disk.  The size of
+partitions is limited only by disk space.  The maximum number of partitions is
+nearly 2000.
+
+Any partitions created under the LDM are called "Dynamic Disks".  There are no
+longer any primary or extended partitions.  Normal MSDOS style partitions are
+now known as Basic Disks.
+
+If you wish to use Spanned, Striped, Mirrored or RAID 5 Volumes, you must use
+Dynamic Disks.  The journalling allows Windows to make changes to these
+partitions and filesystems without the need to reboot.
+
+Once the LDM driver has divided up the disk, you can use the MD driver to
+assemble any multi-partition volumes, e.g.  Stripes, RAID5.
+
+To prevent legacy applications from repartitioning the disk, the LDM creates a
+dummy MSDOS partition containing one disk-sized partition.  This is what is
+supported with the Linux LDM driver.
+
+A newer approach that has been implemented with Vista is to put LDM on top of a
+GPT label disk.  This is not supported by the Linux LDM driver yet.
+
+
+Example
+-------
+
+Below we have a 50MiB disk, divided into seven partitions.
+
+.. note::
+
+   The missing 1MiB at the end of the disk is where the LDM database is
+   stored.
+
++-------++--------------+---------+-----++--------------+---------+----+
+|Device || Offset Bytes | Sectors | MiB || Size   Bytes | Sectors | MiB|
++=======++==============+=========+=====++==============+=========+====+
+|hda    ||            0 |       0 |   0 ||     52428800 |  102400 |  50|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda1   ||     51380224 |  100352 |  49 ||      1048576 |    2048 |   1|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda2   ||        16384 |      32 |   0 ||      6979584 |   13632 |   6|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda3   ||      6995968 |   13664 |   6 ||     10485760 |   20480 |  10|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda4   ||     17481728 |   34144 |  16 ||      4194304 |    8192 |   4|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda5   ||     21676032 |   42336 |  20 ||      5242880 |   10240 |   5|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda6   ||     26918912 |   52576 |  25 ||     10485760 |   20480 |  10|
++-------++--------------+---------+-----++--------------+---------+----+
+|hda7   ||     37404672 |   73056 |  35 ||     13959168 |   27264 |  13|
++-------++--------------+---------+-----++--------------+---------+----+
+
+The LDM Database may not store the partitions in the order that they appear on
+disk, but the driver will sort them.
+
+When Linux boots, you will see something like::
+
+  hda: 102400 sectors w/32KiB Cache, CHS=50/64/32
+  hda: [LDM] hda1 hda2 hda3 hda4 hda5 hda6 hda7
+
+
+Compiling LDM Support
+---------------------
+
+To enable LDM, choose the following two options: 
+
+  - "Advanced partition selection" CONFIG_PARTITION_ADVANCED
+  - "Windows Logical Disk Manager (Dynamic Disk) support" CONFIG_LDM_PARTITION
+
+If you believe the driver isn't working as it should, you can enable the extra
+debugging code.  This will produce a LOT of output.  The option is:
+
+  - "Windows LDM extra logging" CONFIG_LDM_DEBUG
+
+N.B. The partition code cannot be compiled as a module.
+
+As with all the partition code, if the driver doesn't see signs of its type of
+partition, it will pass control to another driver, so there is no harm in
+enabling it.
+
+If you have Dynamic Disks but don't enable the driver, then all you will see
+is a dummy MSDOS partition filling the whole disk.  You won't be able to mount
+any of the volumes on the disk.
+
+
+Booting
+-------
+
+If you enable LDM support, then lilo is capable of booting from any of the
+discovered partitions.  However, grub does not understand the LDM partitioning
+and cannot boot from a Dynamic Disk.
+
+
+More Documentation
+------------------
+
+There is an Overview of the LDM together with complete Technical Documentation.
+It is available for download.
+
+  http://www.linux-ntfs.org/
+
+If you have any LDM questions that aren't answered in the documentation, email
+me.
+
+Cheers,
+    FlatCap - Richard Russon
+    ldm@flatcap.org
+
diff --git a/Documentation/admin-guide/lockup-watchdogs.rst b/Documentation/admin-guide/lockup-watchdogs.rst
new file mode 100644
index 000000000..8f245f4a9
--- /dev/null
+++ b/Documentation/admin-guide/lockup-watchdogs.rst
@@ -0,0 +1,179 @@
+===============================================================
+Softlockup detector and hardlockup detector (aka nmi_watchdog)
+===============================================================
+
+The Linux kernel can act as a watchdog to detect both soft and hard
+lockups.
+
+A 'softlockup' is defined as a bug that causes the kernel to loop in
+kernel mode for more than 20 seconds (see "Implementation" below for
+details), without giving other tasks a chance to run. The current
+stack trace is displayed upon detection and, by default, the system
+will stay locked up. Alternatively, the kernel can be configured to
+panic; a sysctl, "kernel.softlockup_panic", a kernel parameter,
+"softlockup_panic" (see "Documentation/admin-guide/kernel-parameters.rst" for
+details), and a compile option, "BOOTPARAM_SOFTLOCKUP_PANIC", are
+provided for this.
+
+A 'hardlockup' is defined as a bug that causes the CPU to loop in
+kernel mode for several seconds (see "Implementation" below for
+details), without letting other interrupts have a chance to run.
+Similarly to the softlockup case, the current stack trace is displayed
+upon detection and the system will stay locked up unless the default
+behavior is changed, which can be done through a sysctl,
+'hardlockup_panic', a compile time knob, "BOOTPARAM_HARDLOCKUP_PANIC",
+and a kernel parameter, "nmi_watchdog"
+(see "Documentation/admin-guide/kernel-parameters.rst" for details).
+
+The panic option can be used in combination with panic_timeout (this
+timeout is set through the confusingly named "kernel.panic" sysctl),
+to cause the system to reboot automatically after a specified amount
+of time.
+
+Configuration
+=============
+
+A kernel knob is provided that allows administrators to configure
+this period. The "watchdog_thresh" parameter (default 10 seconds)
+controls the threshold. The right value for a particular environment
+is a trade-off between fast response to lockups and detection overhead.
+
+Implementation
+==============
+
+The soft and hard lockup detectors are built around an hrtimer.
+In addition, the softlockup detector regularly schedules a job, and
+the hard lockup detector might use Perf/NMI events on architectures
+that support it.
+
+Frequency and Heartbeats
+------------------------
+
+The core of the detectors is an hrtimer. It serves multiple purposes:
+
+- schedules watchdog job for the softlockup detector
+- bumps the interrupt counter for hardlockup detectors (heartbeat)
+- detects softlockups
+- detects hardlockups in Buddy mode
+
+The period of this hrtimer is 2*watchdog_thresh/5, which is 4 seconds
+by default. The hrtimer has two or three chances to generate an interrupt
+(heartbeat) before the hardlockup detector kicks in.
+
+Softlockup Detector
+-------------------
+
+The watchdog job is scheduled by the hrtimer and runs in a stop scheduling
+thread. It updates a timestamp every time it is scheduled. If that timestamp
+is not updated for 2*watchdog_thresh seconds (the softlockup threshold) the
+'softlockup detector' (coded inside the hrtimer callback function)
+will dump useful debug information to the system log, after which it
+will call panic if it was instructed to do so or resume execution of
+other kernel code.
+
+Hardlockup Detector (NMI/Perf)
+------------------------------
+
+On architectures that support NMI (Non-Maskable Interrupt) perf events,
+a periodic NMI is generated every "watchdog_thresh" seconds.
+
+If any CPU in the system does not receive any hrtimer interrupt
+(heartbeat) during the "watchdog_thresh" window, the 'hardlockup
+detector' (the handler for the NMI perf event) will generate a kernel
+warning or call panic.
+
+**Detection Overhead (NMI):**
+
+The time to detect a lockup can vary depending on when the lockup
+occurs relative to the NMI check window. Examples below assume a watchdog_thresh of 10.
+
+* **Best Case:** The lockup occurs just before the first heartbeat is
+  due. The detector will notice the missing hrtimer interrupt almost
+  immediately during the next check.
+
+  ::
+
+    Time 100.0: cpu 1 heartbeat
+    Time 100.1: hardlockup_check, cpu1 stores its state
+    Time 103.9: Hard Lockup on cpu1
+    Time 104.0: cpu 1 heartbeat never comes
+    Time 110.1: hardlockup_check, cpu1 checks the state again, should be the same, declares lockup
+
+    Time to detection: ~6 seconds
+
+* **Worst Case:** The lockup occurs shortly after a valid interrupt
+  (heartbeat) which itself happened just after the NMI check. The next
+  NMI check sees that the interrupt count has changed (due to that one
+  heartbeat), assumes the CPU is healthy, and resets the baseline. The
+  lockup is only detected at the subsequent check.
+
+  ::
+
+    Time 100.0: hardlockup_check, cpu1 stores its state
+    Time 100.1: cpu 1 heartbeat
+    Time 100.2: Hard Lockup on cpu1
+    Time 110.0: hardlockup_check, cpu1 stores its state (misses lockup as state changed)
+    Time 120.0: hardlockup_check, cpu1 checks the state again, should be the same, declares lockup
+
+    Time to detection: ~20 seconds
+
+Hardlockup Detector (Buddy)
+---------------------------
+
+On architectures or configurations where NMI perf events are not
+available (or disabled), the kernel may use the "buddy" hardlockup
+detector. This mechanism requires SMP (Symmetric Multi-Processing).
+
+In this mode, each CPU is assigned a "buddy" CPU to monitor. The
+monitoring CPU runs its own hrtimer (the same one used for softlockup
+detection) and checks if the buddy CPU's hrtimer interrupt count has
+increased.
+
+To ensure timeliness and avoid false positives, the buddy system performs
+checks at every hrtimer interval (2*watchdog_thresh/5, which is 4 seconds
+by default). It uses a missed-interrupt threshold of 3. If the buddy's
+interrupt count has not changed for 3 consecutive checks, it is assumed
+that the buddy CPU is hardlocked (interrupts disabled). The monitoring
+CPU will then trigger the hardlockup response (warning or panic).
+
+**Detection Overhead (Buddy):**
+
+With a default check interval of 4 seconds (watchdog_thresh = 10):
+
+* **Best case:** Lockup occurs just before a check.
+    Detected in ~8s (0s till 1st check + 4s till 2nd + 4s till 3rd).
+* **Worst case:** Lockup occurs just after a check.
+    Detected in ~12s (4s till 1st check + 4s till 2nd + 4s till 3rd).
+
+**Limitations of the Buddy Detector:**
+
+1.  **All-CPU Lockup:** If all CPUs lock up simultaneously, the buddy
+    detector cannot detect the condition because the monitoring CPUs
+    are also frozen.
+2.  **Stack Traces:** Unlike the NMI detector, the buddy detector
+    cannot directly interrupt the locked CPU to grab a stack trace.
+    It relies on architecture-specific mechanisms (like NMI backtrace
+    support) to try and retrieve the status of the locked CPU. If
+    such support is missing, the log may only show that a lockup
+    occurred without providing the locked CPU's stack.
+
+Watchdog Core Exclusion
+=======================
+
+By default, the watchdog runs on all online cores.  However, on a
+kernel configured with NO_HZ_FULL, by default the watchdog runs only
+on the housekeeping cores, not the cores specified in the "nohz_full"
+boot argument.  If we allowed the watchdog to run by default on
+the "nohz_full" cores, we would have to run timer ticks to activate
+the scheduler, which would prevent the "nohz_full" functionality
+from protecting the user code on those cores from the kernel.
+Of course, disabling it by default on the nohz_full cores means that
+when those cores do enter the kernel, by default we will not be
+able to detect if they lock up.  However, allowing the watchdog
+to continue to run on the housekeeping (non-tickless) cores means
+that we will continue to detect lockups properly on those cores.
+
+In either case, the set of cores excluded from running the watchdog
+may be adjusted via the kernel.watchdog_cpumask sysctl.  For
+nohz_full cores, this may be useful for debugging a case where the
+kernel seems to be hanging on the nohz_full cores.
diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
new file mode 100644
index 000000000..003fd34f7
--- /dev/null
+++ b/Documentation/admin-guide/md.rst
@@ -0,0 +1,811 @@
+RAID arrays
+===========
+
+Boot time assembly of RAID arrays
+---------------------------------
+
+Tools that manage md devices can be found at
+   https://www.kernel.org/pub/linux/utils/raid/
+
+
+You can boot with your md device with the following kernel command
+lines:
+
+for old raid arrays without persistent superblocks::
+
+  md=<md device no.>,<raid level>,<chunk size factor>,<fault level>,dev0,dev1,...,devn
+
+for raid arrays with persistent superblocks::
+
+  md=<md device no.>,dev0,dev1,...,devn
+
+or, to assemble a partitionable array::
+
+  md=d<md device no.>,dev0,dev1,...,devn
+
+``md device no.``
++++++++++++++++++
+
+The number of the md device
+
+================= =========
+``md device no.`` device
+================= =========
+              0		md0
+	      1		md1
+	      2		md2
+	      3		md3
+	      4		md4
+================= =========
+
+``raid level``
+++++++++++++++
+
+level of the RAID array
+
+=============== =============
+``raid level``  level
+=============== =============
+-1		linear mode
+0		striped mode
+=============== =============
+
+other modes are only supported with persistent super blocks
+
+``chunk size factor``
++++++++++++++++++++++
+
+(raid-0 and raid-1 only)
+
+Set  the chunk size as 4k << n.
+
+``fault level``
++++++++++++++++
+
+Totally ignored
+
+``dev0`` to ``devn``
+++++++++++++++++++++
+
+e.g. ``/dev/hda1``, ``/dev/hdc1``, ``/dev/sda1``, ``/dev/sdb1``
+
+A possible loadlin line (Harald Hoyer <HarryH@Royal.Net>)  looks like this::
+
+	e:\loadlin\loadlin e:\zimage root=/dev/md0 md=0,0,4,0,/dev/hdb2,/dev/hdc3 ro
+
+
+Boot time autodetection of RAID arrays
+--------------------------------------
+
+When md is compiled into the kernel (not as module), partitions of
+type 0xfd are scanned and automatically assembled into RAID arrays.
+This autodetection may be suppressed with the kernel parameter
+``raid=noautodetect``.  As of kernel 2.6.9, only drives with a type 0
+superblock can be autodetected and run at boot time.
+
+The kernel parameter ``raid=partitionable`` (or ``raid=part``) means
+that all auto-detected arrays are assembled as partitionable.
+
+Boot time assembly of degraded/dirty arrays
+-------------------------------------------
+
+If a raid5 or raid6 array is both dirty and degraded, it could have
+undetectable data corruption.  This is because the fact that it is
+``dirty`` means that the parity cannot be trusted, and the fact that it
+is degraded means that some datablocks are missing and cannot reliably
+be reconstructed (due to no parity).
+
+For this reason, md will normally refuse to start such an array.  This
+requires the sysadmin to take action to explicitly start the array
+despite possible corruption.  This is normally done with::
+
+   mdadm --assemble --force ....
+
+This option is not really available if the array has the root
+filesystem on it.  In order to support this booting from such an
+array, md supports a module parameter ``start_dirty_degraded`` which,
+when set to 1, bypassed the checks and will allows dirty degraded
+arrays to be started.
+
+So, to boot with a root filesystem of a dirty degraded raid 5 or 6, use::
+
+   md-mod.start_dirty_degraded=1
+
+
+Superblock formats
+------------------
+
+The md driver can support a variety of different superblock formats.
+Currently, it supports superblock formats ``0.90.0`` and the ``md-1`` format
+introduced in the 2.5 development series.
+
+The kernel will autodetect which format superblock is being used.
+
+Superblock format ``0`` is treated differently to others for legacy
+reasons - it is the original superblock format.
+
+
+General Rules - apply for all superblock formats
+------------------------------------------------
+
+An array is ``created`` by writing appropriate superblocks to all
+devices.
+
+It is ``assembled`` by associating each of these devices with an
+particular md virtual device.  Once it is completely assembled, it can
+be accessed.
+
+An array should be created by a user-space tool.  This will write
+superblocks to all devices.  It will usually mark the array as
+``unclean``, or with some devices missing so that the kernel md driver
+can create appropriate redundancy (copying in raid 1, parity
+calculation in raid 4/5).
+
+When an array is assembled, it is first initialized with the
+SET_ARRAY_INFO ioctl.  This contains, in particular, a major and minor
+version number.  The major version number selects which superblock
+format is to be used.  The minor number might be used to tune handling
+of the format, such as suggesting where on each device to look for the
+superblock.
+
+Then each device is added using the ADD_NEW_DISK ioctl.  This
+provides, in particular, a major and minor number identifying the
+device to add.
+
+The array is started with the RUN_ARRAY ioctl.
+
+Once started, new devices can be added.  They should have an
+appropriate superblock written to them, and then be passed in with
+ADD_NEW_DISK.
+
+Devices that have failed or are not yet active can be detached from an
+array using HOT_REMOVE_DISK.
+
+
+Specific Rules that apply to format-0 super block arrays, and arrays with no superblock (non-persistent)
+--------------------------------------------------------------------------------------------------------
+
+An array can be ``created`` by describing the array (level, chunksize
+etc) in a SET_ARRAY_INFO ioctl.  This must have ``major_version==0`` and
+``raid_disks != 0``.
+
+Then uninitialized devices can be added with ADD_NEW_DISK.  The
+structure passed to ADD_NEW_DISK must specify the state of the device
+and its role in the array.
+
+Once started with RUN_ARRAY, uninitialized spares can be added with
+HOT_ADD_DISK.
+
+
+MD devices in sysfs
+-------------------
+
+md devices appear in sysfs (``/sys``) as regular block devices,
+e.g.::
+
+   /sys/block/md0
+
+Each ``md`` device will contain a subdirectory called ``md`` which
+contains further md-specific information about the device.
+
+All md devices contain:
+
+  level
+     a text file indicating the ``raid level``. e.g. raid0, raid1,
+     raid5, linear, multipath, faulty.
+     If no raid level has been set yet (array is still being
+     assembled), the value will reflect whatever has been written
+     to it, which may be a name like the above, or may be a number
+     such as ``0``, ``5``, etc.
+
+  raid_disks
+     a text file with a simple number indicating the number of devices
+     in a fully functional array.  If this is not yet known, the file
+     will be empty.  If an array is being resized this will contain
+     the new number of devices.
+     Some raid levels allow this value to be set while the array is
+     active.  This will reconfigure the array.   Otherwise it can only
+     be set while assembling an array.
+     A change to this attribute will not be permitted if it would
+     reduce the size of the array.  To reduce the number of drives
+     in an e.g. raid5, the array size must first be reduced by
+     setting the ``array_size`` attribute.
+
+  chunk_size
+     This is the size in bytes for ``chunks`` and is only relevant to
+     raid levels that involve striping (0,4,5,6,10). The address space
+     of the array is conceptually divided into chunks and consecutive
+     chunks are striped onto neighbouring devices.
+     The size should be at least PAGE_SIZE (4k) and should be a power
+     of 2.  This can only be set while assembling an array
+
+  layout
+     The ``layout`` for the array for the particular level.  This is
+     simply a number that is interpreted differently by different
+     levels.  It can be written while assembling an array.
+
+  array_size
+     This can be used to artificially constrain the available space in
+     the array to be less than is actually available on the combined
+     devices.  Writing a number (in Kilobytes) which is less than
+     the available size will set the size.  Any reconfiguration of the
+     array (e.g. adding devices) will not cause the size to change.
+     Writing the word ``default`` will cause the effective size of the
+     array to be whatever size is actually available based on
+     ``level``, ``chunk_size`` and ``component_size``.
+
+     This can be used to reduce the size of the array before reducing
+     the number of devices in a raid4/5/6, or to support external
+     metadata formats which mandate such clipping.
+
+  logical_block_size
+     Configure the array's logical block size in bytes. This attribute
+     is only supported for 1.x meta. Write the value before starting
+     array. The final array LBS uses the maximum between this
+     configuration and LBS of all combined devices. Note that
+     LBS cannot exceed PAGE_SIZE before RAID supports folio.
+     WARNING: Arrays created on new kernel cannot be assembled at old
+     kernel due to padding check, Set module parameter 'check_new_feature'
+     to false to bypass, but data loss may occur.
+
+  reshape_position
+     This is either ``none`` or a sector number within the devices of
+     the array where ``reshape`` is up to.  If this is set, the three
+     attributes mentioned above (raid_disks, chunk_size, layout) can
+     potentially have 2 values, an old and a new value.  If these
+     values differ, reading the attribute returns::
+
+        new (old)
+
+     and writing will effect the ``new`` value, leaving the ``old``
+     unchanged.
+
+  component_size
+     For arrays with data redundancy (i.e. not raid0, linear, faulty,
+     multipath), all components must be the same size - or at least
+     there must a size that they all provide space for.  This is a key
+     part or the geometry of the array.  It is measured in sectors
+     and can be read from here.  Writing to this value may resize
+     the array if the personality supports it (raid1, raid5, raid6),
+     and if the component drives are large enough.
+
+  metadata_version
+     This indicates the format that is being used to record metadata
+     about the array.  It can be 0.90 (traditional format), 1.0, 1.1,
+     1.2 (newer format in varying locations) or ``none`` indicating that
+     the kernel isn't managing metadata at all.
+     Alternately it can be ``external:`` followed by a string which
+     is set by user-space.  This indicates that metadata is managed
+     by a user-space program.  Any device failure or other event that
+     requires a metadata update will cause array activity to be
+     suspended until the event is acknowledged.
+
+  resync_start
+     The point at which resync should start.  If no resync is needed,
+     this will be a very large number (or ``none`` since 2.6.30-rc1).  At
+     array creation it will default to 0, though starting the array as
+     ``clean`` will set it much larger.
+
+  new_dev
+     This file can be written but not read.  The value written should
+     be a block device number as major:minor.  e.g. 8:0
+     This will cause that device to be attached to the array, if it is
+     available.  It will then appear at md/dev-XXX (depending on the
+     name of the device) and further configuration is then possible.
+
+  safe_mode_delay
+     When an md array has seen no write requests for a certain period
+     of time, it will be marked as ``clean``.  When another write
+     request arrives, the array is marked as ``dirty`` before the write
+     commences.  This is known as ``safe_mode``.
+     The ``certain period`` is controlled by this file which stores the
+     period as a number of seconds.  The default is 200msec (0.200).
+     Writing a value of 0 disables safemode.
+
+  array_state
+     This file contains a single word which describes the current
+     state of the array.  In many cases, the state can be set by
+     writing the word for the desired state, however some states
+     cannot be explicitly set, and some transitions are not allowed.
+
+     Select/poll works on this file.  All changes except between
+     Active_idle and active (which can be frequent and are not
+     very interesting) are notified.  active->active_idle is
+     reported if the metadata is externally managed.
+
+     clear
+         No devices, no size, no level
+
+         Writing is equivalent to STOP_ARRAY ioctl
+
+     inactive
+         May have some settings, but array is not active
+         all IO results in error
+
+         When written, doesn't tear down array, but just stops it
+
+     suspended (not supported yet)
+         All IO requests will block. The array can be reconfigured.
+
+         Writing this, if accepted, will block until array is quiescent
+
+     readonly
+         no resync can happen.  no superblocks get written.
+
+         Write requests fail
+
+     read-auto
+         like readonly, but behaves like ``clean`` on a write request.
+
+     clean
+         no pending writes, but otherwise active.
+
+         When written to inactive array, starts without resync
+
+         If a write request arrives then
+         if metadata is known, mark ``dirty`` and switch to ``active``.
+         if not known, block and switch to write-pending
+
+         If written to an active array that has pending writes, then fails.
+     active
+         fully active: IO and resync can be happening.
+         When written to inactive array, starts with resync
+
+     write-pending
+         clean, but writes are blocked waiting for ``active`` to be written.
+
+     active-idle
+         like active, but no writes have been seen for a while (safe_mode_delay).
+
+  consistency_policy
+     This indicates how the array maintains consistency in case of unexpected
+     shutdown. It can be:
+
+     none
+       Array has no redundancy information, e.g. raid0, linear.
+
+     resync
+       Full resync is performed and all redundancy is regenerated when the
+       array is started after unclean shutdown.
+
+     bitmap
+       Resync assisted by a write-intent bitmap.
+
+     journal
+       For raid4/5/6, journal device is used to log transactions and replay
+       after unclean shutdown.
+
+     ppl
+       For raid5 only, Partial Parity Log is used to close the write hole and
+       eliminate resync.
+
+     The accepted values when writing to this file are ``ppl`` and ``resync``,
+     used to enable and disable PPL.
+
+  uuid
+     This indicates the UUID of the array in the following format:
+     xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+
+  bitmap_type
+     [RW] When read, this file will display the current and available
+     bitmap for this array. The currently active bitmap will be enclosed
+     in [] brackets. Writing an bitmap name or ID to this file will switch
+     control of this array to that new bitmap. Note that writing a new
+     bitmap for created array is forbidden.
+
+     none
+         No bitmap
+     bitmap
+         The default internal bitmap
+     llbitmap
+         The lockless internal bitmap
+
+If bitmap_type is not none, then additional bitmap attributes bitmap/xxx or
+llbitmap/xxx will be created after md device KOBJ_CHANGE event.
+
+If bitmap_type is bitmap, then the md device will also contain:
+
+  bitmap/location
+     This indicates where the write-intent bitmap for the array is
+     stored.
+
+     It can be one of ``none``, ``file`` or ``[+-]N``.
+     ``file`` may later be extended to ``file:/file/name``
+     ``[+-]N`` means that many sectors from the start of the metadata.
+
+     This is replicated on all devices.  For arrays with externally
+     managed metadata, the offset is from the beginning of the
+     device.
+
+  bitmap/chunksize
+     The size, in bytes, of the chunk which will be represented by a
+     single bit.  For RAID456, it is a portion of an individual
+     device. For RAID10, it is a portion of the array.  For RAID1, it
+     is both (they come to the same thing).
+
+  bitmap/time_base
+     The time, in seconds, between looking for bits in the bitmap to
+     be cleared. In the current implementation, a bit will be cleared
+     between 2 and 3 times ``time_base`` after all the covered blocks
+     are known to be in-sync.
+
+  bitmap/backlog
+     When write-mostly devices are active in a RAID1, write requests
+     to those devices proceed in the background - the filesystem (or
+     other user of the device) does not have to wait for them.
+     ``backlog`` sets a limit on the number of concurrent background
+     writes.  If there are more than this, new writes will by
+     synchronous.
+
+  bitmap/metadata
+     This can be either ``internal`` or ``external``.
+
+     ``internal``
+       is the default and means the metadata for the bitmap
+       is stored in the first 256 bytes of the allocated space and is
+       managed by the md module.
+
+     ``external``
+       means that bitmap metadata is managed externally to
+       the kernel (i.e. by some userspace program)
+
+  bitmap/can_clear
+     This is either ``true`` or ``false``.  If ``true``, then bits in the
+     bitmap will be cleared when the corresponding blocks are thought
+     to be in-sync.  If ``false``, bits will never be cleared.
+     This is automatically set to ``false`` if a write happens on a
+     degraded array, or if the array becomes degraded during a write.
+     When metadata is managed externally, it should be set to true
+     once the array becomes non-degraded, and this fact has been
+     recorded in the metadata.
+
+If bitmap_type is llbitmap, then the md device will also contain:
+
+  llbitmap/bits
+     This is read-only, show status of bitmap bits, the number of each
+     value.
+
+  llbitmap/metadata
+     This is read-only, show bitmap metadata, include chunksize, chunkshift,
+     chunks, offset and daemon_sleep.
+
+  llbitmap/daemon_sleep
+     This is read-write, time in seconds that daemon function will be
+     triggered to clear dirty bits.
+
+  llbitmap/barrier_idle
+     This is read-write, time in seconds that page barrier will be idled,
+     means dirty bits in the page will be cleared.
+
+As component devices are added to an md array, they appear in the ``md``
+directory as new directories named::
+
+      dev-XXX
+
+where ``XXX`` is a name that the kernel knows for the device, e.g. hdb1.
+Each directory contains:
+
+      block
+        a symlink to the block device in /sys/block, e.g.::
+
+	     /sys/block/md0/md/dev-hdb1/block -> ../../../../block/hdb/hdb1
+
+      super
+        A file containing an image of the superblock read from, or
+        written to, that device.
+
+      state
+	A file recording the current state of the device in the array
+	which can be a comma separated list of:
+
+	      faulty
+			device has been kicked from active use due to
+			a detected fault, or it has unacknowledged bad
+			blocks
+
+	      in_sync
+			device is a fully in-sync member of the array
+
+	      writemostly
+			device will only be subject to read
+			requests if there are no other options.
+
+			This applies only to raid1 arrays.
+
+	      blocked
+			device has failed, and the failure hasn't been
+			acknowledged yet by the metadata handler.
+
+			Writes that would write to this device if
+			it were not faulty are blocked.
+
+	      spare
+			device is working, but not a full member.
+
+			This includes spares that are in the process
+			of being recovered to
+
+	      write_error
+			device has ever seen a write error.
+
+	      want_replacement
+			device is (mostly) working but probably
+			should be replaced, either due to errors or
+			due to user request.
+
+	      replacement
+			device is a replacement for another active
+			device with same raid_disk.
+
+
+	This list may grow in future.
+
+	This can be written to.
+
+	Writing ``faulty``  simulates a failure on the device.
+
+	Writing ``remove`` removes the device from the array.
+
+	Writing ``writemostly`` sets the writemostly flag.
+
+	Writing ``-writemostly`` clears the writemostly flag.
+
+	Writing ``blocked`` sets the ``blocked`` flag.
+
+	Writing ``-blocked`` clears the ``blocked`` flags and allows writes
+	to complete and possibly simulates an error.
+
+	Writing ``in_sync`` sets the in_sync flag.
+
+	Writing ``write_error`` sets writeerrorseen flag.
+
+	Writing ``-write_error`` clears writeerrorseen flag.
+
+	Writing ``want_replacement`` is allowed at any time except to a
+	replacement device or a spare.  It sets the flag.
+
+	Writing ``-want_replacement`` is allowed at any time.  It clears
+	the flag.
+
+	Writing ``replacement`` or ``-replacement`` is only allowed before
+	starting the array.  It sets or clears the flag.
+
+
+	This file responds to select/poll. Any change to ``faulty``
+	or ``blocked`` causes an event.
+
+      errors
+	An approximate count of read errors that have been detected on
+	this device but have not caused the device to be evicted from
+	the array (either because they were corrected or because they
+	happened while the array was read-only).  When using version-1
+	metadata, this value persists across restarts of the array.
+
+	This value can be written while assembling an array thus
+	providing an ongoing count for arrays with metadata managed by
+	userspace.
+
+      slot
+        This gives the role that the device has in the array.  It will
+	either be ``none`` if the device is not active in the array
+        (i.e. is a spare or has failed) or an integer less than the
+	``raid_disks`` number for the array indicating which position
+	it currently fills.  This can only be set while assembling an
+	array.  A device for which this is set is assumed to be working.
+
+      offset
+        This gives the location in the device (in sectors from the
+        start) where data from the array will be stored.  Any part of
+        the device before this offset is not touched, unless it is
+        used for storing metadata (Formats 1.1 and 1.2).
+
+      size
+        The amount of the device, after the offset, that can be used
+        for storage of data.  This will normally be the same as the
+	component_size.  This can be written while assembling an
+        array.  If a value less than the current component_size is
+        written, it will be rejected.
+
+      recovery_start
+        When the device is not ``in_sync``, this records the number of
+	sectors from the start of the device which are known to be
+	correct.  This is normally zero, but during a recovery
+	operation it will steadily increase, and if the recovery is
+	interrupted, restoring this value can cause recovery to
+	avoid repeating the earlier blocks.  With v1.x metadata, this
+	value is saved and restored automatically.
+
+	This can be set whenever the device is not an active member of
+	the array, either before the array is activated, or before
+	the ``slot`` is set.
+
+	Setting this to ``none`` is equivalent to setting ``in_sync``.
+	Setting to any other value also clears the ``in_sync`` flag.
+
+      bad_blocks
+	This gives the list of all known bad blocks in the form of
+	start address and length (in sectors respectively). If output
+	is too big to fit in a page, it will be truncated. Writing
+	``sector length`` to this file adds new acknowledged (i.e.
+	recorded to disk safely) bad blocks.
+
+      unacknowledged_bad_blocks
+	This gives the list of known-but-not-yet-saved-to-disk bad
+	blocks in the same form of ``bad_blocks``. If output is too big
+	to fit in a page, it will be truncated. Writing to this file
+	adds bad blocks without acknowledging them. This is largely
+	for testing.
+
+      ppl_sector, ppl_size
+        Location and size (in sectors) of the space used for Partial Parity Log
+        on this device.
+
+
+An active md device will also contain an entry for each active device
+in the array.  These are named::
+
+    rdNN
+
+where ``NN`` is the position in the array, starting from 0.
+So for a 3 drive array there will be rd0, rd1, rd2.
+These are symbolic links to the appropriate ``dev-XXX`` entry.
+Thus, for example::
+
+       cat /sys/block/md*/md/rd*/state
+
+will show ``in_sync`` on every line.
+
+
+
+Active md devices for levels that support data redundancy (1,4,5,6,10)
+also have
+
+   sync_action
+     a text file that can be used to monitor and control the rebuild
+     process.  It contains one word which can be one of:
+
+       resync
+		redundancy is being recalculated after unclean
+                shutdown or creation
+
+       recover
+		a hot spare is being built to replace a
+		failed/missing device
+
+       idle
+		nothing is happening
+       check
+		A full check of redundancy was requested and is
+                happening.  This reads all blocks and checks
+                them. A repair may also happen for some raid
+                levels.
+
+       repair
+		A full check and repair is happening.  This is
+		similar to ``resync``, but was requested by the
+                user, and the write-intent bitmap is NOT used to
+		optimise the process.
+
+      This file is writable, and each of the strings that could be
+      read are meaningful for writing.
+
+	``idle`` will stop an active resync/recovery etc.  There is no
+	guarantee that another resync/recovery may not be automatically
+	started again, though some event will be needed to trigger
+	this.
+
+	``resync`` or ``recovery`` can be used to restart the
+        corresponding operation if it was stopped with ``idle``.
+
+	``check`` and ``repair`` will start the appropriate process
+	providing the current state is ``idle``.
+
+      This file responds to select/poll.  Any important change in the value
+      triggers a poll event.  Sometimes the value will briefly be
+      ``recover`` if a recovery seems to be needed, but cannot be
+      achieved. In that case, the transition to ``recover`` isn't
+      notified, but the transition away is.
+
+   degraded
+      This contains a count of the number of devices by which the
+      arrays is degraded.  So an optimal array will show ``0``.  A
+      single failed/missing drive will show ``1``, etc.
+
+      This file responds to select/poll, any increase or decrease
+      in the count of missing devices will trigger an event.
+
+   mismatch_count
+      When performing ``check`` and ``repair``, and possibly when
+      performing ``resync``, md will count the number of errors that are
+      found.  The count in ``mismatch_cnt`` is the number of sectors
+      that were re-written, or (for ``check``) would have been
+      re-written.  As most raid levels work in units of pages rather
+      than sectors, this may be larger than the number of actual errors
+      by a factor of the number of sectors in a page.
+
+   bitmap_set_bits
+      If the array has a write-intent bitmap, then writing to this
+      attribute can set bits in the bitmap, indicating that a resync
+      would need to check the corresponding blocks. Either individual
+      numbers or start-end pairs can be written.  Multiple numbers
+      can be separated by a space.
+
+      Note that the numbers are ``bit`` numbers, not ``block`` numbers.
+      They should be scaled by the bitmap_chunksize.
+
+   sync_speed_min, sync_speed_max
+     These are similar to ``/proc/sys/dev/raid/speed_limit_{min,max}``
+     however they only apply to the particular array.
+
+     If no value has been written to these, or if the word ``system``
+     is written, then the system-wide value is used.  If a value,
+     in kibibytes-per-second is written, then it is used.
+
+     When the files are read, they show the currently active value
+     followed by ``(local)`` or ``(system)`` depending on whether it is
+     a locally set or system-wide value.
+
+   sync_completed
+     This shows the number of sectors that have been completed of
+     whatever the current sync_action is, followed by the number of
+     sectors in total that could need to be processed.  The two
+     numbers are separated by a ``/``  thus effectively showing one
+     value, a fraction of the process that is complete.
+
+     A ``select`` on this attribute will return when resync completes,
+     when it reaches the current sync_max (below) and possibly at
+     other times.
+
+   sync_speed
+     This shows the current actual speed, in K/sec, of the current
+     sync_action.  It is averaged over the last 30 seconds.
+
+   suspend_lo, suspend_hi
+     The two values, given as numbers of sectors, indicate a range
+     within the array where IO will be blocked.  This is currently
+     only supported for raid4/5/6.
+
+   sync_min, sync_max
+     The two values, given as numbers of sectors, indicate a range
+     within the array where ``check``/``repair`` will operate. Must be
+     a multiple of chunk_size. When it reaches ``sync_max`` it will
+     pause, rather than complete.
+     You can use ``select`` or ``poll`` on ``sync_completed`` to wait for
+     that number to reach sync_max.  Then you can either increase
+     ``sync_max``, or can write ``idle`` to ``sync_action``.
+
+     The value of ``max`` for ``sync_max`` effectively disables the limit.
+     When a resync is active, the value can only ever be increased,
+     never decreased.
+     The value of ``0`` is the minimum for ``sync_min``.
+
+
+
+Each active md device may also have attributes specific to the
+personality module that manages it.
+These are specific to the implementation of the module and could
+change substantially if the implementation changes.
+
+These currently include:
+
+  stripe_cache_size  (currently raid5 only)
+      number of entries in the stripe cache.  This is writable, but
+      there are upper and lower limits (32768, 17).  Default is 256.
+
+  strip_cache_active (currently raid5 only)
+      number of active entries in the stripe cache
+
+  preread_bypass_threshold (currently raid5 only)
+      number of times a stripe requiring preread will be bypassed by
+      a stripe that does not require preread.  For fairness defaults
+      to 1.  Setting this to 0 disables bypass accounting and
+      requires preread stripes to wait until all full-width stripe-
+      writes are complete.  Valid values are 0 to stripe_cache_size.
+
+  journal_mode (currently raid5 only)
+      The cache mode for raid5. raid5 could include an extra disk for
+      caching. The mode can be "write-through" or "write-back". The
+      default is "write-through".
+
+  ppl_write_hint
+      NVMe stream ID to be set for each PPL write request.
diff --git a/Documentation/admin-guide/media/amdisp4-1.rst b/Documentation/admin-guide/media/amdisp4-1.rst
new file mode 100644
index 000000000..878141154
--- /dev/null
+++ b/Documentation/admin-guide/media/amdisp4-1.rst
@@ -0,0 +1,63 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+====================================
+AMD Image Signal Processor (amdisp4)
+====================================
+
+Introduction
+============
+
+This file documents the driver for the AMD ISP4 that is part of
+AMD Ryzen AI Max 300 Series.
+
+The driver is located under drivers/media/platform/amd/isp4 and uses
+the Media-Controller API.
+
+The driver exposes one video capture device to userspace and provide
+web camera like interface. Internally the video device is connected
+to the isp4 sub-device responsible for communication with the CCPU FW.
+
+Topology
+========
+
+.. _amdisp4_topology_graph:
+
+.. kernel-figure:: amdisp4.dot
+     :alt:   Diagram of the media pipeline topology
+     :align: center
+
+
+
+The driver has 1 sub-device: Representing isp4 image signal processor.
+The driver has 1 video device: Capture device for retrieving images.
+
+- ISP4 Image Signal Processing Subdevice Node
+
+---------------------------------------------
+
+The isp4 is represented as a single V4L2 subdev, the sub-device does not
+provide interface to the user space. The sub-device is connected to one video node
+(isp4_capture) with immutable active link. The sub-device represents ISP with
+connected sensor similar to smart cameras (sensors with integrated ISP).
+sub-device has only one link to the video device for capturing the frames.
+The sub-device communicates with CCPU FW for streaming configuration and
+buffer management.
+
+
+- isp4_capture - Frames Capture Video Node
+
+------------------------------------------
+
+Isp4_capture is a capture device to capture frames to memory.
+The entity is connected to isp4 sub-device. The video device
+provides web camera like interface to userspace. It supports
+mmap and dma buf types of memory.
+
+Capturing Video Frames Example
+==============================
+
+.. code-block:: bash
+
+         v4l2-ctl "-d" "/dev/video0" "--set-fmt-video=width=1920,height=1080,pixelformat=NV12" "--stream-mmap" "--stream-count=10"
diff --git a/Documentation/admin-guide/media/amdisp4.dot b/Documentation/admin-guide/media/amdisp4.dot
new file mode 100644
index 000000000..978f30c1a
--- /dev/null
+++ b/Documentation/admin-guide/media/amdisp4.dot
@@ -0,0 +1,6 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{} | amd isp4\n | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port0 -> n00000003 [style=bold]
+	n00000003 [label="Preview\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+}
diff --git a/Documentation/admin-guide/media/au0828-cardlist.rst b/Documentation/admin-guide/media/au0828-cardlist.rst
new file mode 100644
index 000000000..aaaadc934
--- /dev/null
+++ b/Documentation/admin-guide/media/au0828-cardlist.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+AU0828 cards list
+=================
+
+.. tabularcolumns:: |p{1.4cm}|p{6.5cm}|p{10.0cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - USB IDs
+
+   * - 0
+     - Unknown board
+     -
+
+   * - 1
+     - Hauppauge HVR950Q
+     - 2040:7200, 2040:7210, 2040:7217, 2040:721b, 2040:721e, 2040:721f, 2040:7280, 0fd9:0008, 2040:7260, 2040:7213, 2040:7270
+
+   * - 2
+     - Hauppauge HVR850
+     - 2040:7240
+
+   * - 3
+     - DViCO FusionHDTV USB
+     - 0fe9:d620
+
+   * - 4
+     - Hauppauge HVR950Q rev xxF8
+     - 2040:7201, 2040:7211, 2040:7281
+
+   * - 5
+     - Hauppauge Woodbury
+     - 05e1:0480, 2040:8200
diff --git a/Documentation/admin-guide/media/avermedia.rst b/Documentation/admin-guide/media/avermedia.rst
new file mode 100644
index 000000000..93ff74002
--- /dev/null
+++ b/Documentation/admin-guide/media/avermedia.rst
@@ -0,0 +1,94 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+Avermedia DVB-T on BT878 Release Notes
+======================================
+
+February 14th 2006
+
+.. note::
+
+   Several other Avermedia devices are supported. For a more
+   broader and updated content about that, please check:
+
+   https://linuxtv.org/wiki/index.php/AVerMedia
+
+The Avermedia DVB-T
+~~~~~~~~~~~~~~~~~~~
+
+The Avermedia DVB-T is a budget PCI DVB card. It has 3 inputs:
+
+* RF Tuner Input
+* Composite Video Input (RCA Jack)
+* SVIDEO Input (Mini-DIN)
+
+The  RF  Tuner  Input  is the input to the tuner module of the
+card.  The  Tuner  is  otherwise known as the "Frontend" . The
+Frontend of the Avermedia DVB-T is a Microtune 7202D. A timely
+post  to  the  linux-dvb  mailing  list  ascertained  that the
+Microtune  7202D  is  supported  by the sp887x driver which is
+found in the dvb-hw CVS module.
+
+The  DVB-T card is based around the BT878 chip which is a very
+common multimedia bridge and often found on Analogue TV cards.
+There is no on-board MPEG2 decoder, which means that all MPEG2
+decoding  must  be done in software, or if you have one, on an
+MPEG2 hardware decoding card or chipset.
+
+
+Getting the card going
+~~~~~~~~~~~~~~~~~~~~~~
+
+At  this  stage,  it  has  not  been  able  to  ascertain  the
+functionality  of the remaining device nodes in respect of the
+Avermedia  DVBT.  However,  full  functionality  in respect of
+tuning,  receiving  and  supplying  the  MPEG2  data stream is
+possible  with the currently available versions of the driver.
+It  may be possible that additional functionality is available
+from  the  card  (i.e.  viewing the additional analogue inputs
+that  the card presents), but this has not been tested yet. If
+I get around to this, I'll update the document with whatever I
+find.
+
+To  power  up  the  card,  load  the  following modules in the
+following order:
+
+* modprobe bttv (normally loaded automatically)
+* modprobe dvb-bt8xx (or place dvb-bt8xx in /etc/modules)
+
+Insertion  of  these  modules  into  the  running  kernel will
+activate the appropriate DVB device nodes. It is then possible
+to start accessing the card with utilities such as scan, tzap,
+dvbstream etc.
+
+The frontend module sp887x.o, requires an external   firmware.
+Please use  the  command "get_dvb_firmware sp887x" to download
+it. Then copy it to /usr/lib/hotplug/firmware or /lib/firmware/
+(depending on configuration of firmware hotplug).
+
+Known Limitations
+~~~~~~~~~~~~~~~~~
+
+At  present  I can say with confidence that the frontend tunes
+via /dev/dvb/adapter{x}/frontend0 and supplies an MPEG2 stream
+via   /dev/dvb/adapter{x}/dvr0.   I   have   not   tested  the
+functionality  of any other part of the card yet. I will do so
+over time and update this document.
+
+There  are some limitations in the i2c layer due to a returned
+error message inconsistency. Although this generates errors in
+dmesg  and  the  system logs, it does not appear to affect the
+ability of the frontend to function correctly.
+
+Further Update
+~~~~~~~~~~~~~~
+
+dvbstream  and  VideoLAN  Client on windows works a treat with
+DVB,  in  fact  this  is  currently  serving as my main way of
+viewing  DVB-T  at  the  moment.  Additionally, VLC is happily
+decoding  HDTV  signals,  although  the PC is dropping the odd
+frame here and there - I assume due to processing capability -
+as all the decoding is being done under windows in software.
+
+Many  thanks to Nigel Pearson for the updates to this document
+since the recent revision of the driver.
diff --git a/Documentation/admin-guide/media/bt8xx.rst b/Documentation/admin-guide/media/bt8xx.rst
new file mode 100644
index 000000000..3589f6ab7
--- /dev/null
+++ b/Documentation/admin-guide/media/bt8xx.rst
@@ -0,0 +1,157 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+How to get the bt8xx cards working
+==================================
+
+Authors:
+	 Richard Walker,
+	 Jamie Honan,
+	 Michael Hunold,
+	 Manu Abraham,
+	 Uwe Bugla,
+	 Michael Krufky
+
+General information
+-------------------
+
+This class of cards has a bt878a as the PCI interface, and require the bttv
+driver for accessing the i2c bus and the gpio pins of the bt8xx chipset.
+
+Please see Documentation/admin-guide/media/bttv-cardlist.rst for a complete
+list of Cards based on the Conexant Bt8xx PCI bridge supported by the
+Linux Kernel.
+
+In order to be able to compile the kernel, some config options should be
+enabled::
+
+    ./scripts/config -e PCI
+    ./scripts/config -e INPUT
+    ./scripts/config -m I2C
+    ./scripts/config -m MEDIA_SUPPORT
+    ./scripts/config -e MEDIA_PCI_SUPPORT
+    ./scripts/config -e MEDIA_ANALOG_TV_SUPPORT
+    ./scripts/config -e MEDIA_DIGITAL_TV_SUPPORT
+    ./scripts/config -e MEDIA_RADIO_SUPPORT
+    ./scripts/config -e RC_CORE
+    ./scripts/config -m VIDEO_BT848
+    ./scripts/config -m DVB_BT8XX
+
+If you want to automatically support all possible variants of the Bt8xx
+cards, you should also do::
+
+    ./scripts/config -e MEDIA_SUBDRV_AUTOSELECT
+
+.. note::
+
+   Please use the following options with care as deselection of drivers which
+   are in fact necessary may result in DVB devices that cannot be tuned due
+   to lack of driver support.
+
+If your goal is to just support an specific board, you may, instead,
+disable MEDIA_SUBDRV_AUTOSELECT and manually select the frontend drivers
+required by your board. With that, you can save some RAM.
+
+You can do that by calling make xconfig/qconfig/menuconfig and look at
+the options on those menu options (only enabled if
+``Autoselect ancillary drivers`` is disabled:
+
+#) ``Device drivers`` => ``Multimedia support`` => ``Customize TV tuners``
+#) ``Device drivers`` => ``Multimedia support`` => ``Customize DVB frontends``
+
+Then, on each of the above menu, please select your card-specific
+frontend and tuner modules.
+
+
+Loading Modules
+---------------
+
+Regular case: If the bttv driver detects a bt8xx-based DVB card, all
+frontend and backend modules will be loaded automatically.
+
+Exceptions are:
+
+- Old TV cards without EEPROMs, sharing a common PCI subsystem ID;
+- Old TwinHan DST cards or clones with or without CA slot and not
+  containing an Eeprom.
+
+In the following cases overriding the PCI type detection for bttv and
+for dvb-bt8xx drivers by passing modprobe parameters may be necessary.
+
+Running TwinHan and Clones
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As shown at Documentation/admin-guide/media/bttv-cardlist.rst, TwinHan and
+clones use ``card=113`` modprobe parameter. So, in order to properly
+detect it for devices without EEPROM, you should use::
+
+	$ modprobe bttv card=113
+	$ modprobe dst
+
+Useful parameters for verbosity level and debugging the dst module::
+
+	verbose=0:		messages are disabled
+		1:		only error messages are displayed
+		2:		notifications are displayed
+		3:		other useful messages are displayed
+		4:		debug setting
+	dst_addons=0:		card is a free to air (FTA) card only
+		0x20:	card has a conditional access slot for scrambled channels
+	dst_algo=0:		(default) Software tuning algorithm
+	         1:		Hardware tuning algorithm
+
+
+The autodetected values are determined by the cards' "response string".
+
+In your logs see f. ex.: dst_get_device_id: Recognize [DSTMCI].
+
+For bug reports please send in a complete log with verbose=4 activated.
+Please also see Documentation/admin-guide/media/ci.rst.
+
+Running multiple cards
+~~~~~~~~~~~~~~~~~~~~~~
+
+See Documentation/admin-guide/media/bttv-cardlist.rst for a complete list of
+Card ID. Some examples:
+
+	===========================	===
+	Brand name			ID
+	===========================	===
+	Pinnacle PCTV Sat		 94
+	Nebula Electronics Digi TV	104
+	pcHDTV HD-2000 TV		112
+	Twinhan DST and clones		113
+	Avermedia AverTV DVB-T 77:	123
+	Avermedia AverTV DVB-T 761	124
+	DViCO FusionHDTV DVB-T Lite	128
+	DViCO FusionHDTV 5 Lite		135
+	===========================	===
+
+.. note::
+
+   When you have multiple cards, the order of the card ID should
+   match the order where they're detected by the system. Please notice
+   that removing/inserting other PCI cards may change the detection
+   order.
+
+Example::
+
+	$ modprobe bttv card=113 card=135
+
+In case of further problems please subscribe and send questions to
+the mailing list: linux-media@vger.kernel.org.
+
+Probing the cards with broken PCI subsystem ID
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are some TwinHan cards whose EEPROM has become corrupted for some
+reason. The cards do not have a correct PCI subsystem ID.
+Still, it is possible to force probing the cards with::
+
+	$ echo 109e 0878 $subvendor $subdevice > \
+		/sys/bus/pci/drivers/bt878/new_id
+
+The two numbers there are::
+
+	109e: PCI_VENDOR_ID_BROOKTREE
+	0878: PCI_DEVICE_ID_BROOKTREE_878
diff --git a/Documentation/admin-guide/media/bttv-cardlist.rst b/Documentation/admin-guide/media/bttv-cardlist.rst
new file mode 100644
index 000000000..8671d4f7b
--- /dev/null
+++ b/Documentation/admin-guide/media/bttv-cardlist.rst
@@ -0,0 +1,683 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+BTTV cards list
+===============
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     -  *** UNKNOWN/GENERIC ***
+     -
+
+   * - 1
+     - MIRO PCTV
+     -
+
+   * - 2
+     - Hauppauge (bt848)
+     -
+
+   * - 3
+     - STB, Gateway P/N 6000699 (bt848)
+     -
+
+   * - 4
+     - Intel Create and Share PCI/ Smart Video Recorder III
+     -
+
+   * - 5
+     - Diamond DTV2000
+     -
+
+   * - 6
+     - AVerMedia TVPhone
+     -
+
+   * - 7
+     - MATRIX-Vision MV-Delta
+     -
+
+   * - 8
+     - Lifeview FlyVideo II (Bt848) LR26 / MAXI TV Video PCI2 LR26
+     -
+
+   * - 9
+     - IMS/IXmicro TurboTV
+     -
+
+   * - 10
+     - Hauppauge (bt878)
+     - 0070:13eb, 0070:3900, 2636:10b4
+
+   * - 11
+     - MIRO PCTV pro
+     -
+
+   * - 12
+     - ADS Technologies Channel Surfer TV (bt848)
+     -
+
+   * - 13
+     - AVerMedia TVCapture 98
+     - 1461:0002, 1461:0004, 1461:0300
+
+   * - 14
+     - Aimslab Video Highway Xtreme (VHX)
+     -
+
+   * - 15
+     - Zoltrix TV-Max
+     - a1a0:a0fc
+
+   * - 16
+     - Prolink Pixelview PlayTV (bt878)
+     -
+
+   * - 17
+     - Leadtek WinView 601
+     -
+
+   * - 18
+     - AVEC Intercapture
+     -
+
+   * - 19
+     - Lifeview FlyVideo II EZ /FlyKit LR38 Bt848 (capture only)
+     -
+
+   * - 20
+     - CEI Raffles Card
+     -
+
+   * - 21
+     - Lifeview FlyVideo 98/ Lucky Star Image World ConferenceTV LR50
+     -
+
+   * - 22
+     - Askey CPH050/ Phoebe Tv Master + FM
+     - 14ff:3002
+
+   * - 23
+     - Modular Technology MM201/MM202/MM205/MM210/MM215 PCTV, bt878
+     - 14c7:0101
+
+   * - 24
+     - Askey CPH05X/06X (bt878) [many vendors]
+     - 144f:3002, 144f:3005, 144f:5000, 14ff:3000
+
+   * - 25
+     - Terratec TerraTV+ Version 1.0 (Bt848)/ Terra TValue Version 1.0/ Vobis TV-Boostar
+     -
+
+   * - 26
+     - Hauppauge WinCam newer (bt878)
+     -
+
+   * - 27
+     - Lifeview FlyVideo 98/ MAXI TV Video PCI2 LR50
+     -
+
+   * - 28
+     - Terratec TerraTV+ Version 1.1 (bt878)
+     - 153b:1127, 1852:1852
+
+   * - 29
+     - Imagenation PXC200
+     - 1295:200a
+
+   * - 30
+     - Lifeview FlyVideo 98 LR50
+     - 1f7f:1850
+
+   * - 31
+     - Formac iProTV, Formac ProTV I (bt848)
+     -
+
+   * - 32
+     - Intel Create and Share PCI/ Smart Video Recorder III
+     -
+
+   * - 33
+     - Terratec TerraTValue Version Bt878
+     - 153b:1117, 153b:1118, 153b:1119, 153b:111a, 153b:1134, 153b:5018
+
+   * - 34
+     - Leadtek WinFast 2000/ WinFast 2000 XP
+     - 107d:6606, 107d:6609, 6606:217d, f6ff:fff6
+
+   * - 35
+     - Lifeview FlyVideo 98 LR50 / Chronos Video Shuttle II
+     - 1851:1850, 1851:a050
+
+   * - 36
+     - Lifeview FlyVideo 98FM LR50 / Typhoon TView TV/FM Tuner
+     - 1852:1852
+
+   * - 37
+     - Prolink PixelView PlayTV pro
+     -
+
+   * - 38
+     - Askey CPH06X TView99
+     - 144f:3000, 144f:a005, a04f:a0fc
+
+   * - 39
+     - Pinnacle PCTV Studio/Rave
+     - 11bd:0012, bd11:1200, bd11:ff00, 11bd:ff12
+
+   * - 40
+     - STB TV PCI FM, Gateway P/N 6000704 (bt878), 3Dfx VoodooTV 100
+     - 10b4:2636, 10b4:2645, 121a:3060
+
+   * - 41
+     - AVerMedia TVPhone 98
+     - 1461:0001, 1461:0003
+
+   * - 42
+     - ProVideo PV951
+     - aa0c:146c
+
+   * - 43
+     - Little OnAir TV
+     -
+
+   * - 44
+     - Sigma TVII-FM
+     -
+
+   * - 45
+     - MATRIX-Vision MV-Delta 2
+     -
+
+   * - 46
+     - Zoltrix Genie TV/FM
+     - 15b0:4000, 15b0:400a, 15b0:400d, 15b0:4010, 15b0:4016
+
+   * - 47
+     - Terratec TV/Radio+
+     - 153b:1123
+
+   * - 48
+     - Askey CPH03x/ Dynalink Magic TView
+     -
+
+   * - 49
+     - IODATA GV-BCTV3/PCI
+     - 10fc:4020
+
+   * - 50
+     - Prolink PV-BT878P+4E / PixelView PlayTV PAK / Lenco MXTV-9578 CP
+     -
+
+   * - 51
+     - Eagle Wireless Capricorn2 (bt878A)
+     -
+
+   * - 52
+     - Pinnacle PCTV Studio Pro
+     -
+
+   * - 53
+     - Typhoon TView RDS + FM Stereo / KNC1 TV Station RDS
+     -
+
+   * - 54
+     - Lifeview FlyVideo 2000 /FlyVideo A2/ Lifetec LT 9415 TV [LR90]
+     -
+
+   * - 55
+     - Askey CPH031/ BESTBUY Easy TV
+     -
+
+   * - 56
+     - Lifeview FlyVideo 98FM LR50
+     - a051:41a0
+
+   * - 57
+     - GrandTec 'Grand Video Capture' (Bt848)
+     - 4344:4142
+
+   * - 58
+     - Askey CPH060/ Phoebe TV Master Only (No FM)
+     -
+
+   * - 59
+     - Askey CPH03x TV Capturer
+     -
+
+   * - 60
+     - Modular Technology MM100PCTV
+     -
+
+   * - 61
+     - AG Electronics GMV1
+     - 15cb:0101
+
+   * - 62
+     - Askey CPH061/ BESTBUY Easy TV (bt878)
+     -
+
+   * - 63
+     - ATI TV-Wonder
+     - 1002:0001
+
+   * - 64
+     - ATI TV-Wonder VE
+     - 1002:0003
+
+   * - 65
+     - Lifeview FlyVideo 2000S LR90
+     -
+
+   * - 66
+     - Terratec TValueRadio
+     - 153b:1135, 153b:ff3b
+
+   * - 67
+     - IODATA GV-BCTV4/PCI
+     - 10fc:4050
+
+   * - 68
+     - 3Dfx VoodooTV FM (Euro)
+     - 10b4:2637
+
+   * - 69
+     - Active Imaging AIMMS
+     -
+
+   * - 70
+     - Prolink Pixelview PV-BT878P+ (Rev.4C,8E)
+     -
+
+   * - 71
+     - Lifeview FlyVideo 98EZ (capture only) LR51
+     - 1851:1851
+
+   * - 72
+     - Prolink Pixelview PV-BT878P+9B (PlayTV Pro rev.9B FM+NICAM)
+     - 1554:4011
+
+   * - 73
+     - Sensoray 311/611
+     - 6000:0311, 6000:0611
+
+   * - 74
+     - RemoteVision MX (RV605)
+     -
+
+   * - 75
+     - Powercolor MTV878/ MTV878R/ MTV878F
+     -
+
+   * - 76
+     - Canopus WinDVR PCI (COMPAQ Presario 3524JP, 5112JP)
+     - 0e11:0079
+
+   * - 77
+     - GrandTec Multi Capture Card (Bt878)
+     -
+
+   * - 78
+     - Jetway TV/Capture JW-TV878-FBK, Kworld KW-TV878RF
+     - 0a01:17de
+
+   * - 79
+     - DSP Design TCVIDEO
+     -
+
+   * - 80
+     - Hauppauge WinTV PVR
+     - 0070:4500
+
+   * - 81
+     - IODATA GV-BCTV5/PCI
+     - 10fc:4070, 10fc:d018
+
+   * - 82
+     - Osprey 100/150 (878)
+     - 0070:ff00
+
+   * - 83
+     - Osprey 100/150 (848)
+     -
+
+   * - 84
+     - Osprey 101 (848)
+     -
+
+   * - 85
+     - Osprey 101/151
+     -
+
+   * - 86
+     - Osprey 101/151 w/ svid
+     -
+
+   * - 87
+     - Osprey 200/201/250/251
+     -
+
+   * - 88
+     - Osprey 200/250
+     - 0070:ff01
+
+   * - 89
+     - Osprey 210/220/230
+     -
+
+   * - 90
+     - Osprey 500
+     - 0070:ff02
+
+   * - 91
+     - Osprey 540
+     - 0070:ff04
+
+   * - 92
+     - Osprey 2000
+     - 0070:ff03
+
+   * - 93
+     - IDS Eagle
+     -
+
+   * - 94
+     - Pinnacle PCTV Sat
+     - 11bd:001c
+
+   * - 95
+     - Formac ProTV II (bt878)
+     -
+
+   * - 96
+     - MachTV
+     -
+
+   * - 97
+     - Euresys Picolo
+     -
+
+   * - 98
+     - ProVideo PV150
+     - aa00:1460, aa01:1461, aa02:1462, aa03:1463, aa04:1464, aa05:1465, aa06:1466, aa07:1467
+
+   * - 99
+     - AD-TVK503
+     -
+
+   * - 100
+     - Hercules Smart TV Stereo
+     -
+
+   * - 101
+     - Pace TV & Radio Card
+     -
+
+   * - 102
+     - IVC-200
+     - 0000:a155, 0001:a155, 0002:a155, 0003:a155, 0100:a155, 0101:a155, 0102:a155, 0103:a155, 0800:a155, 0801:a155, 0802:a155, 0803:a155
+
+   * - 103
+     - Grand X-Guard / Trust 814PCI
+     - 0304:0102
+
+   * - 104
+     - Nebula Electronics DigiTV
+     - 0071:0101
+
+   * - 105
+     - ProVideo PV143
+     - aa00:1430, aa00:1431, aa00:1432, aa00:1433, aa03:1433
+
+   * - 106
+     - PHYTEC VD-009-X1 VD-011 MiniDIN (bt878)
+     -
+
+   * - 107
+     - PHYTEC VD-009-X1 VD-011 Combi (bt878)
+     -
+
+   * - 108
+     - PHYTEC VD-009 MiniDIN (bt878)
+     -
+
+   * - 109
+     - PHYTEC VD-009 Combi (bt878)
+     -
+
+   * - 110
+     - IVC-100
+     - ff00:a132
+
+   * - 111
+     - IVC-120G
+     - ff00:a182, ff01:a182, ff02:a182, ff03:a182, ff04:a182, ff05:a182, ff06:a182, ff07:a182, ff08:a182, ff09:a182, ff0a:a182, ff0b:a182, ff0c:a182, ff0d:a182, ff0e:a182, ff0f:a182
+
+   * - 112
+     - pcHDTV HD-2000 TV
+     - 7063:2000
+
+   * - 113
+     - Twinhan DST + clones
+     - 11bd:0026, 1822:0001, 270f:fc00, 1822:0026
+
+   * - 114
+     - Winfast VC100
+     - 107d:6607
+
+   * - 115
+     - Teppro TEV-560/InterVision IV-560
+     -
+
+   * - 116
+     - SIMUS GVC1100
+     - aa6a:82b2
+
+   * - 117
+     - NGS NGSTV+
+     -
+
+   * - 118
+     - LMLBT4
+     -
+
+   * - 119
+     - Tekram M205 PRO
+     -
+
+   * - 120
+     - Conceptronic CONTVFMi
+     -
+
+   * - 121
+     - Euresys Picolo Tetra
+     - 1805:0105, 1805:0106, 1805:0107, 1805:0108
+
+   * - 122
+     - Spirit TV Tuner
+     -
+
+   * - 123
+     - AVerMedia AVerTV DVB-T 771
+     - 1461:0771
+
+   * - 124
+     - AverMedia AverTV DVB-T 761
+     - 1461:0761
+
+   * - 125
+     - MATRIX Vision Sigma-SQ
+     -
+
+   * - 126
+     - MATRIX Vision Sigma-SLC
+     -
+
+   * - 127
+     - APAC Viewcomp 878(AMAX)
+     -
+
+   * - 128
+     - DViCO FusionHDTV DVB-T Lite
+     - 18ac:db10, 18ac:db11
+
+   * - 129
+     - V-Gear MyVCD
+     -
+
+   * - 130
+     - Super TV Tuner
+     -
+
+   * - 131
+     - Tibet Systems 'Progress DVR' CS16
+     -
+
+   * - 132
+     - Kodicom 4400R (master)
+     -
+
+   * - 133
+     - Kodicom 4400R (slave)
+     -
+
+   * - 134
+     - Adlink RTV24
+     -
+
+   * - 135
+     - DViCO FusionHDTV 5 Lite
+     - 18ac:d500
+
+   * - 136
+     - Acorp Y878F
+     - 9511:1540
+
+   * - 137
+     - Conceptronic CTVFMi v2
+     - 036e:109e
+
+   * - 138
+     - Prolink Pixelview PV-BT878P+ (Rev.2E)
+     -
+
+   * - 139
+     - Prolink PixelView PlayTV MPEG2 PV-M4900
+     -
+
+   * - 140
+     - Osprey 440
+     - 0070:ff07
+
+   * - 141
+     - Asound Skyeye PCTV
+     -
+
+   * - 142
+     - Sabrent TV-FM (bttv version)
+     -
+
+   * - 143
+     - Hauppauge ImpactVCB (bt878)
+     - 0070:13eb
+
+   * - 144
+     - MagicTV
+     -
+
+   * - 145
+     - SSAI Security Video Interface
+     - 4149:5353
+
+   * - 146
+     - SSAI Ultrasound Video Interface
+     - 414a:5353
+
+   * - 147
+     - VoodooTV 200 (USA)
+     - 121a:3000
+
+   * - 148
+     - DViCO FusionHDTV 2
+     - dbc0:d200
+
+   * - 149
+     - Typhoon TV-Tuner PCI (50684)
+     -
+
+   * - 150
+     - Geovision GV-600
+     - 008a:763c
+
+   * - 151
+     - Kozumi KTV-01C
+     -
+
+   * - 152
+     - Encore ENL TV-FM-2
+     - 1000:1801
+
+   * - 153
+     - PHYTEC VD-012 (bt878)
+     -
+
+   * - 154
+     - PHYTEC VD-012-X1 (bt878)
+     -
+
+   * - 155
+     - PHYTEC VD-012-X2 (bt878)
+     -
+
+   * - 156
+     - IVCE-8784
+     - 0000:f050, 0001:f050, 0002:f050, 0003:f050
+
+   * - 157
+     - Geovision GV-800(S) (master)
+     - 800a:763d
+
+   * - 158
+     - Geovision GV-800(S) (slave)
+     - 800b:763d, 800c:763d, 800d:763d
+
+   * - 159
+     - ProVideo PV183
+     - 1830:1540, 1831:1540, 1832:1540, 1833:1540, 1834:1540, 1835:1540, 1836:1540, 1837:1540
+
+   * - 160
+     - Tongwei Video Technology TD-3116
+     - f200:3116
+
+   * - 161
+     - Aposonic W-DVR
+     - 0279:0228
+
+   * - 162
+     - Adlink MPG24
+     -
+
+   * - 163
+     - Bt848 Capture 14MHz
+     -
+
+   * - 164
+     - CyberVision CV06 (SV)
+     -
+
+   * - 165
+     - Kworld V-Stream Xpert TV PVR878
+     -
+
+   * - 166
+     - PCI-8604PW
+     -
diff --git a/Documentation/admin-guide/media/bttv.rst b/Documentation/admin-guide/media/bttv.rst
new file mode 100644
index 000000000..78c3e560b
--- /dev/null
+++ b/Documentation/admin-guide/media/bttv.rst
@@ -0,0 +1,1762 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+The bttv driver
+===============
+
+Release notes for bttv
+----------------------
+
+You'll need at least these config options for bttv::
+
+    ./scripts/config -e PCI
+    ./scripts/config -m I2C
+    ./scripts/config -m INPUT
+    ./scripts/config -m MEDIA_SUPPORT
+    ./scripts/config -e MEDIA_PCI_SUPPORT
+    ./scripts/config -e MEDIA_ANALOG_TV_SUPPORT
+    ./scripts/config -e MEDIA_DIGITAL_TV_SUPPORT
+    ./scripts/config -e MEDIA_RADIO_SUPPORT
+    ./scripts/config -e RC_CORE
+    ./scripts/config -m VIDEO_BT848
+
+If your board has digital TV, you'll also need::
+
+    ./scripts/config -m DVB_BT8XX
+
+In this case, please see Documentation/admin-guide/media/bt8xx.rst
+for additional notes.
+
+Make bttv work with your card
+-----------------------------
+
+If you have bttv compiled and installed, just booting the Kernel
+should be enough for it to try probing it. However, depending
+on the model, the Kernel may require additional information about
+the hardware, as the device may not be able to provide such info
+directly to the Kernel.
+
+If it doesn't bttv likely could not autodetect your card and needs some
+insmod options.  The most important insmod option for bttv is "card=n"
+to select the correct card type.  If you get video but no sound you've
+very likely specified the wrong (or no) card type.  A list of supported
+cards is in Documentation/admin-guide/media/bttv-cardlist.rst.
+
+If bttv takes very long to load (happens sometimes with the cheap
+cards which have no tuner), try adding this to your modules configuration
+file (usually, it is either ``/etc/modules.conf`` or some file at
+``/etc/modules-load.d/``, but the actual place depends on your
+distribution)::
+
+	options i2c-algo-bit bit_test=1
+
+Some cards may require an extra firmware file to work. For example,
+for the WinTV/PVR you need one firmware file from its driver CD,
+called: ``hcwamc.rbf``. It is inside a self-extracting zip file
+called ``pvr45xxx.exe``.  Just placing it at the ``/etc/firmware``
+directory should be enough for it to be autoload during the driver's
+probing mode (e. g. when the Kernel boots or when the driver is
+manually loaded via ``modprobe`` command).
+
+If your card isn't listed in Documentation/admin-guide/media/bttv-cardlist.rst
+or if you have trouble making audio work, please read :ref:`still_doesnt_work`.
+
+
+Autodetecting cards
+-------------------
+
+bttv uses the PCI Subsystem ID to autodetect the card type.  lspci lists
+the Subsystem ID in the second line, looks like this:
+
+.. code-block:: none
+
+	00:0a.0 Multimedia video controller: Brooktree Corporation Bt878 (rev 02)
+		Subsystem: Hauppauge computer works Inc. WinTV/GO
+		Flags: bus master, medium devsel, latency 32, IRQ 5
+		Memory at e2000000 (32-bit, prefetchable) [size=4K]
+
+only bt878-based cards can have a subsystem ID (which does not mean
+that every card really has one).  bt848 cards can't have a Subsystem
+ID and therefore can't be autodetected.  There is a list with the ID's
+at Documentation/admin-guide/media/bttv-cardlist.rst
+(in case you are interested or want to mail patches with updates).
+
+
+.. _still_doesnt_work:
+
+Still doesn't work?
+-------------------
+
+I do NOT have a lab with 30+ different grabber boards and a
+PAL/NTSC/SECAM test signal generator at home, so I often can't
+reproduce your problems.  This makes debugging very difficult for me.
+
+If you have some knowledge and spare time, please try to fix this
+yourself (patches very welcome of course...)  You know: The linux
+slogan is "Do it yourself".
+
+There is a mailing list at
+http://vger.kernel.org/vger-lists.html#linux-media
+
+If you have trouble with some specific TV card, try to ask there
+instead of mailing me directly.  The chance that someone with the
+same card listens there is much higher...
+
+For problems with sound:  There are a lot of different systems used
+for TV sound all over the world.  And there are also different chips
+which decode the audio signal.  Reports about sound problems ("stereo
+doesn't work") are pretty useless unless you include some details
+about your hardware and the TV sound scheme used in your country (or
+at least the country you are living in).
+
+Modprobe options
+----------------
+
+.. note::
+
+
+   The following argument list can be outdated, as we might add more
+   options if ever needed. In case of doubt, please check with
+   ``modinfo <module>``.
+
+   This command prints various information about a kernel
+   module, among them a complete and up-to-date list of insmod options.
+
+
+
+bttv
+	The bt848/878 (grabber chip) driver
+
+    insmod args::
+
+	    card=n		card type, see CARDLIST for a list.
+	    tuner=n		tuner type, see CARDLIST for a list.
+	    radio=0/1	card supports radio
+	    pll=0/1/2	pll settings
+
+			    0: don't use PLL
+			    1: 28 MHz crystal installed
+			    2: 35 MHz crystal installed
+
+	    triton1=0/1     for Triton1 (+others) compatibility
+	    vsfx=0/1	yet another chipset bug compatibility bit
+			    see README.quirks for details on these two.
+
+	    bigendian=n	Set the endianness of the gfx framebuffer.
+			    Default is native endian.
+	    fieldnr=0/1	Count fields.  Some TV descrambling software
+			    needs this, for others it only generates
+			    50 useless IRQs/sec.  default is 0 (off).
+	    autoload=0/1	autoload helper modules (tuner, audio).
+			    default is 1 (on).
+	    bttv_verbose=0/1/2  verbose level (at insmod time, while
+			    looking at the hardware).  default is 1.
+	    bttv_debug=0/1	debug messages (for capture).
+			    default is 0 (off).
+	    irq_debug=0/1	irq handler debug messages.
+			    default is 0 (off).
+	    gbuffers=2-32	number of capture buffers for mmap'ed capture.
+			    default is 4.
+	    gbufsize=	size of capture buffers. default and
+			    maximum value is 0x208000 (~2MB)
+	    no_overlay=0	Enable overlay on broken hardware.  There
+			    are some chipsets (SIS for example) which
+			    are known to have problems with the PCI DMA
+			    push used by bttv.  bttv will disable overlay
+			    by default on this hardware to avoid crashes.
+			    With this insmod option you can override this.
+	    no_overlay=1	Disable overlay. It should be used by broken
+			    hardware that doesn't support PCI2PCI direct
+			    transfers.
+	    automute=0/1	Automatically mutes the sound if there is
+			    no TV signal, on by default.  You might try
+			    to disable this if you have bad input signal
+			    quality which leading to unwanted sound
+			    dropouts.
+	    chroma_agc=0/1	AGC of chroma signal, off by default.
+	    adc_crush=0/1	Luminance ADC crush, on by default.
+	    i2c_udelay=     Allow reduce I2C speed. Default is 5 usecs
+			    (meaning 66,67 Kbps). The default is the
+			    maximum supported speed by kernel bitbang
+			    algorithm. You may use lower numbers, if I2C
+			    messages are lost (16 is known to work on
+			    all supported cards).
+
+	    bttv_gpio=0/1
+	    gpiomask=
+	    audioall=
+	    audiomux=
+			    See Sound-FAQ for a detailed description.
+
+	remap, card, radio and pll accept up to four comma-separated arguments
+	(for multiple boards).
+
+tuner
+	The tuner driver.  You need this unless you want to use only
+	with a camera or the board doesn't provide analog TV tuning.
+
+	insmod args::
+
+		debug=1		print some debug info to the syslog
+		type=n		type of the tuner chip. n as follows:
+				see CARDLIST for a complete list.
+		pal=[bdgil]	select PAL variant (used for some tuners
+				only, important for the audio carrier).
+
+tvaudio
+	Provide a single driver for all simple i2c audio control
+	chips (tda/tea*).
+
+	insmod args::
+
+		tda8425  = 1	enable/disable the support for the
+		tda9840  = 1	various chips.
+		tda9850  = 1	The tea6300 can't be autodetected and is
+		tda9855  = 1	therefore off by default, if you have
+		tda9873  = 1	this one on your card (STB uses these)
+		tda9874a = 1	you have to enable it explicitly.
+		tea6300  = 0	The two tda985x chips use the same i2c
+		tea6420  = 1	address and can't be disturgished from
+		pic16c54 = 1	each other, you might have to disable
+				the wrong one.
+		debug = 1	print debug messages
+
+msp3400
+	The driver for the msp34xx sound processor chips. If you have a
+	stereo card, you probably want to insmod this one.
+
+	insmod args::
+
+		debug=1/2	print some debug info to the syslog,
+				2 is more verbose.
+		simple=1	Use the "short programming" method.  Newer
+				msp34xx versions support this.  You need this
+				for dbx stereo.  Default is on if supported by
+				the chip.
+		once=1		Don't check the TV-stations Audio mode
+				every few seconds, but only once after
+				channel switches.
+		amsound=1	Audio carrier is AM/NICAM at 6.5 Mhz.  This
+				should improve things for french people, the
+				carrier autoscan seems to work with FM only...
+
+If the box freezes hard with bttv
+---------------------------------
+
+It might be a bttv driver bug.  It also might be bad hardware.  It also
+might be something else ...
+
+Just mailing me "bttv freezes" isn't going to help much.  This README
+has a few hints how you can help to pin down the problem.
+
+
+bttv bugs
+~~~~~~~~~
+
+If some version works and another doesn't it is likely to be a driver
+bug.  It is very helpful if you can tell where exactly it broke
+(i.e. the last working and the first broken version).
+
+With a hard freeze you probably doesn't find anything in the logfiles.
+The only way to capture any kernel messages is to hook up a serial
+console and let some terminal application log the messages.  /me uses
+screen.  See Documentation/admin-guide/serial-console.rst for details on
+setting up a serial console.
+
+Read Documentation/admin-guide/bug-hunting.rst to learn how to get any useful
+information out of a register+stack dump printed by the kernel on
+protection faults (so-called "kernel oops").
+
+If you run into some kind of deadlock, you can try to dump a call trace
+for each process using sysrq-t (see Documentation/admin-guide/sysrq.rst).
+This way it is possible to figure where *exactly* some process in "D"
+state is stuck.
+
+I've seen reports that bttv 0.7.x crashes whereas 0.8.x works rock solid
+for some people.  Thus probably a small buglet left somewhere in bttv
+0.7.x.  I have no idea where exactly, it works stable for me and a lot of
+other people.  But in case you have problems with the 0.7.x versions you
+can give 0.8.x a try ...
+
+
+hardware bugs
+~~~~~~~~~~~~~
+
+Some hardware can't deal with PCI-PCI transfers (i.e. grabber => vga).
+Sometimes problems show up with bttv just because of the high load on
+the PCI bus. The bt848/878 chips have a few workarounds for known
+incompatibilities, see README.quirks.
+
+Some folks report that increasing the pci latency helps too,
+althrought I'm not sure whenever this really fixes the problems or
+only makes it less likely to happen.  Both bttv and btaudio have a
+insmod option to set the PCI latency of the device.
+
+Some mainboard have problems to deal correctly with multiple devices
+doing DMA at the same time.  bttv + ide seems to cause this sometimes,
+if this is the case you likely see freezes only with video and hard disk
+access at the same time.  Updating the IDE driver to get the latest and
+greatest workarounds for hardware bugs might fix these problems.
+
+
+other
+~~~~~
+
+If you use some binary-only yunk (like nvidia module) try to reproduce
+the problem without.
+
+IRQ sharing is known to cause problems in some cases.  It works just
+fine in theory and many configurations.  Neverless it might be worth a
+try to shuffle around the PCI cards to give bttv another IRQ or make
+it share the IRQ with some other piece of hardware.  IRQ sharing with
+VGA cards seems to cause trouble sometimes.  I've also seen funny
+effects with bttv sharing the IRQ with the ACPI bridge (and
+apci-enabled kernel).
+
+Bttv quirks
+-----------
+
+Below is what the bt878 data book says about the PCI bug compatibility
+modes of the bt878 chip.
+
+The triton1 insmod option sets the EN_TBFX bit in the control register.
+The vsfx insmod option does the same for EN_VSFX bit.  If you have
+stability problems you can try if one of these options makes your box
+work solid.
+
+drivers/pci/quirks.c knows about these issues, this way these bits are
+enabled automagically for known-buggy chipsets (look at the kernel
+messages, bttv tells you).
+
+Normal PCI Mode
+~~~~~~~~~~~~~~~
+
+The PCI REQ signal is the logical-or of the incoming function requests.
+The inter-nal GNT[0:1] signals are gated asynchronously with GNT and
+demultiplexed by the audio request signal. Thus the arbiter defaults to
+the video function at power-up and parks there during no requests for
+bus access. This is desirable since the video will request the bus more
+often. However, the audio will have highest bus access priority. Thus
+the audio will have first access to the bus even when issuing a request
+after the video request but before the PCI external arbiter has granted
+access to the Bt879. Neither function can preempt the other once on the
+bus. The duration to empty the entire video PCI FIFO onto the PCI bus is
+very short compared to the bus access latency the audio PCI FIFO can
+tolerate.
+
+
+430FX Compatibility Mode
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+When using the 430FX PCI, the following rules will ensure
+compatibility:
+
+ (1) Deassert REQ at the same time as asserting FRAME.
+ (2) Do not reassert REQ to request another bus transaction until after
+     finish-ing the previous transaction.
+
+Since the individual bus masters do not have direct control of REQ, a
+simple logical-or of video and audio requests would violate the rules.
+Thus, both the arbiter and the initiator contain 430FX compatibility
+mode logic. To enable 430FX mode, set the EN_TBFX bit as indicated in
+Device Control Register on page 104.
+
+When EN_TBFX is enabled, the arbiter ensures that the two compatibility
+rules are satisfied. Before GNT is asserted by the PCI arbiter, this
+internal arbiter may still logical-or the two requests. However, once
+the GNT is issued, this arbiter must lock in its decision and now route
+only the granted request to the REQ pin. The arbiter decision lock
+happens regardless of the state of FRAME because it does not know when
+FRAME will be asserted (typically - each initiator will assert FRAME on
+the cycle following GNT). When FRAME is asserted, it is the initiator s
+responsibility to remove its request at the same time. It is the
+arbiters responsibility to allow this request to flow through to REQ and
+not allow the other request to hold REQ asserted. The decision lock may
+be removed at the end of the transaction: for example, when the bus is
+idle (FRAME and IRDY). The arbiter decision may then continue
+asynchronously until GNT is again asserted.
+
+
+Interfacing with Non-PCI 2.1 Compliant Core Logic
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A small percentage of core logic devices may start a bus transaction
+during the same cycle that GNT is de-asserted. This is non PCI 2.1
+compliant. To ensure compatibility when using PCs with these PCI
+controllers, the EN_VSFX bit must be enabled (refer to Device Control
+Register on page 104). When in this mode, the arbiter does not pass GNT
+to the internal functions unless REQ is asserted. This prevents a bus
+transaction from starting the same cycle as GNT is de-asserted. This
+also has the side effect of not being able to take advantage of bus
+parking, thus lowering arbitration performance. The Bt879 drivers must
+query for these non-compliant devices, and set the EN_VSFX bit only if
+required.
+
+
+Other elements of the tvcards array
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you are trying to make a new card work you might find it useful to
+know what the other elements in the tvcards array are good for::
+
+	video_inputs    - # of video inputs the card has
+	audio_inputs    - historical cruft, not used any more.
+	tuner           - which input is the tuner
+	svhs            - which input is svhs (all others are labeled composite)
+	muxsel          - video mux, input->registervalue mapping
+	pll             - same as pll= insmod option
+	tuner_type      - same as tuner= insmod option
+	*_modulename    - hint whenever some card needs this or that audio
+			module loaded to work properly.
+	has_radio	- whenever this TV card has a radio tuner.
+	no_msp34xx	- "1" disables loading of msp3400.o module
+	no_tda9875	- "1" disables loading of tda9875.o module
+	needs_tvaudio	- set to "1" to load tvaudio.o module
+
+If some config item is specified both from the tvcards array and as
+insmod option, the insmod option takes precedence.
+
+Cards
+-----
+
+.. note::
+
+   For a more updated list, please check
+   https://linuxtv.org/wiki/index.php/Hardware_Device_Information
+
+Supported cards: Bt848/Bt848a/Bt849/Bt878/Bt879 cards
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+All cards with Bt848/Bt848a/Bt849/Bt878/Bt879 and normal
+Composite/S-VHS inputs are supported.  Teletext and Intercast support
+(PAL only) for ALL cards via VBI sample decoding in software.
+
+Some cards with additional multiplexing of inputs or other additional
+fancy chips are only partially supported (unless specifications by the
+card manufacturer are given).  When a card is listed here it isn't
+necessarily fully supported.
+
+All other cards only differ by additional components as tuners, sound
+decoders, EEPROMs, teletext decoders ...
+
+
+MATRIX Vision
+~~~~~~~~~~~~~
+
+MV-Delta
+- Bt848A
+- 4 Composite inputs, 1 S-VHS input (shared with 4th composite)
+- EEPROM
+
+http://www.matrix-vision.de/
+
+This card has no tuner but supports all 4 composite (1 shared with an
+S-VHS input) of the Bt848A.
+Very nice card if you only have satellite TV but several tuners connected
+to the card via composite.
+
+Many thanks to Matrix-Vision for giving us 2 cards for free which made
+Bt848a/Bt849 single crystal operation support possible!!!
+
+
+
+Miro/Pinnacle PCTV
+~~~~~~~~~~~~~~~~~~
+
+- Bt848
+  some (all??) come with 2 crystals for PAL/SECAM and NTSC
+- PAL, SECAM or NTSC TV tuner (Philips or TEMIC)
+- MSP34xx sound decoder on add on board
+  decoder is supported but AFAIK does not yet work
+  (other sound MUX setting in GPIO port needed??? somebody who fixed this???)
+- 1 tuner, 1 composite and 1 S-VHS input
+- tuner type is autodetected
+
+http://www.miro.de/
+http://www.miro.com/
+
+
+Many thanks for the free card which made first NTSC support possible back
+in 1997!
+
+
+Hauppauge Win/TV pci
+~~~~~~~~~~~~~~~~~~~~
+
+There are many different versions of the Hauppauge cards with different
+tuners (TV+Radio ...), teletext decoders.
+Note that even cards with same model numbers have (depending on the revision)
+different chips on it.
+
+- Bt848 (and others but always in 2 crystal operation???)
+  newer cards have a Bt878
+
+- PAL, SECAM, NTSC or tuner with or without Radio support
+
+e.g.:
+
+- PAL:
+
+  - TDA5737: VHF, hyperband and UHF mixer/oscillator for TV and VCR 3-band tuners
+  - TSA5522: 1.4 GHz I2C-bus controlled synthesizer, I2C 0xc2-0xc3
+
+- NTSC:
+
+  - TDA5731: VHF, hyperband and UHF mixer/oscillator for TV and VCR 3-band tuners
+  - TSA5518: no datasheet available on Philips site
+
+- Philips SAA5246 or SAA5284 ( or no) Teletext decoder chip
+  with buffer RAM (e.g. Winbond W24257AS-35: 32Kx8 CMOS static RAM)
+  SAA5246 (I2C 0x22) is supported
+
+- 256 bytes EEPROM: Microchip 24LC02B or Philips 8582E2Y
+  with configuration information
+  I2C address 0xa0 (24LC02B also responds to 0xa2-0xaf)
+
+- 1 tuner, 1 composite and (depending on model) 1 S-VHS input
+
+- 14052B: mux for selection of sound source
+
+- sound decoder: TDA9800, MSP34xx (stereo cards)
+
+
+Askey CPH-Series
+~~~~~~~~~~~~~~~~
+Developed by TelSignal(?), OEMed by many vendors (Typhoon, Anubis, Dynalink)
+
+- Card series:
+  - CPH01x: BT848 capture only
+  - CPH03x: BT848
+  - CPH05x: BT878 with FM
+  - CPH06x: BT878 (w/o FM)
+  - CPH07x: BT878 capture only
+
+- TV standards:
+  - CPH0x0: NTSC-M/M
+  - CPH0x1: PAL-B/G
+  - CPH0x2: PAL-I/I
+  - CPH0x3: PAL-D/K
+  - CPH0x4: SECAM-L/L
+  - CPH0x5: SECAM-B/G
+  - CPH0x6: SECAM-D/K
+  - CPH0x7: PAL-N/N
+  - CPH0x8: PAL-B/H
+  - CPH0x9: PAL-M/M
+
+- CPH03x was often sold as "TV capturer".
+
+Identifying:
+
+  #) 878 cards can be identified by PCI Subsystem-ID:
+     - 144f:3000 = CPH06x
+     - 144F:3002 = CPH05x w/ FM
+     - 144F:3005 = CPH06x_LC (w/o remote control)
+  #) The cards have a sticker with "CPH"-model on the back.
+  #) These cards have a number printed on the PCB just above the tuner metal box:
+     - "80-CP2000300-x" = CPH03X
+     - "80-CP2000500-x" = CPH05X
+     - "80-CP2000600-x" = CPH06X / CPH06x_LC
+
+  Askey sells these cards as "Magic TView series", Brand "MagicXpress".
+  Other OEM often call these "Tview", "TView99" or else.
+
+Lifeview Flyvideo Series:
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The naming of these series differs in time and space.
+
+Identifying:
+  #) Some models can be identified by PCI subsystem ID:
+
+     - 1852:1852 = Flyvideo 98 FM
+     - 1851:1850 = Flyvideo 98
+     - 1851:1851 = Flyvideo 98 EZ (capture only)
+
+  #) There is a print on the PCB:
+
+     - LR25       = Flyvideo (Zoran ZR36120, SAA7110A)
+     - LR26 Rev.N = Flyvideo II (Bt848)
+     - LR26 Rev.O = Flyvideo II (Bt878)
+     - LR37 Rev.C = Flyvideo EZ (Capture only, ZR36120 + SAA7110)
+     - LR38 Rev.A1= Flyvideo II EZ (Bt848 capture only)
+     - LR50 Rev.Q = Flyvideo 98 (w/eeprom and PCI subsystem ID)
+     - LR50 Rev.W = Flyvideo 98 (no eeprom)
+     - LR51 Rev.E = Flyvideo 98 EZ (capture only)
+     - LR90       = Flyvideo 2000 (Bt878)
+     - LR90 Flyvideo 2000S (Bt878) w/Stereo TV (Package incl. LR91 daughterboard)
+     - LR91       = Stereo daughter card for LR90
+     - LR97       = Flyvideo DVBS
+     - LR99 Rev.E = Low profile card for OEM integration (only internal audio!) bt878
+     - LR136	 = Flyvideo 2100/3100 (Low profile, SAA7130/SAA7134)
+     - LR137      = Flyvideo DV2000/DV3000 (SAA7130/SAA7134 + IEEE1394)
+     - LR138 Rev.C= Flyvideo 2000 (SAA7130)
+     - LR138 Flyvideo 3000 (SAA7134) w/Stereo TV
+
+	- These exist in variations w/FM and w/Remote sometimes denoted
+	  by suffixes "FM" and "R".
+
+  #) You have a laptop (miniPCI card):
+
+      - Product    = FlyTV Platinum Mini
+      - Model/Chip = LR212/saa7135
+
+      - Lifeview.com.tw states (Feb. 2002):
+        "The FlyVideo2000 and FlyVideo2000s product name have renamed to FlyVideo98."
+        Their Bt8x8 cards are listed as discontinued.
+      - Flyvideo 2000S was probably sold as Flyvideo 3000 in some countries(Europe?).
+        The new Flyvideo 2000/3000 are SAA7130/SAA7134 based.
+
+"Flyvideo II" had been the name for the 848 cards, nowadays (in Germany)
+this name is re-used for LR50 Rev.W.
+
+The Lifeview website mentioned Flyvideo III at some time, but such a card
+has not yet been seen (perhaps it was the german name for LR90 [stereo]).
+These cards are sold by many OEMs too.
+
+FlyVideo A2 (Elta 8680)= LR90 Rev.F (w/Remote, w/o FM, stereo TV by tda9821) {Germany}
+
+Lifeview 3000 (Elta 8681) as sold by Plus(April 2002), Germany = LR138 w/ saa7134
+
+lifeview config coding on gpio pins 0-9
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+- LR50 rev. Q ("PARTS: 7031505116), Tuner wurde als Nr. 5 erkannt, Eingänge
+  SVideo, TV, Composite, Audio, Remote:
+
+ - CP9..1=100001001 (1: 0-Ohm-Widerstand gegen GND unbestückt; 0: bestückt)
+
+
+Typhoon TV card series:
+~~~~~~~~~~~~~~~~~~~~~~~
+
+These can be CPH, Flyvideo, Pixelview or KNC1 series.
+
+Typhoon is the brand of Anubis.
+
+Model 50680 got re-used, some model no. had different contents over time.
+
+Models:
+
+  - 50680 "TV Tuner PCI Pal BG"(old,red package)=can be CPH03x(bt848) or CPH06x(bt878)
+  - 50680 "TV Tuner Pal BG" (blue package)= Pixelview PV-BT878P+ (Rev 9B)
+  - 50681 "TV Tuner PCI Pal I" (variant of 50680)
+  - 50682 "TView TV/FM Tuner Pal BG"       = Flyvideo 98FM (LR50 Rev.Q)
+
+  .. note::
+
+	 The package has a picture of CPH05x (which would be a real TView)
+
+  - 50683 "TV Tuner PCI SECAM" (variant of 50680)
+  - 50684 "TV Tuner Pal BG"                = Pixelview 878TV(Rev.3D)
+  - 50686 "TV Tuner"                       = KNC1 TV Station
+  - 50687 "TV Tuner stereo"                = KNC1 TV Station pro
+  - 50688 "TV Tuner RDS" (black package)   = KNC1 TV Station RDS
+  - 50689  TV SAT DVB-S CARD CI PCI (SAA7146AH, SU1278?) = "KNC1 TV Station DVB-S"
+  - 50692 "TV/FM Tuner" (small PCB)
+  - 50694  TV TUNER CARD RDS (PHILIPS CHIPSET SAA7134HL)
+  - 50696  TV TUNER STEREO (PHILIPS CHIPSET SAA7134HL, MK3ME Tuner)
+  - 50804  PC-SAT TV/Audio Karte = Techni-PC-Sat (ZORAN 36120PQC, Tuner:Alps)
+  - 50866  TVIEW SAT RECEIVER+ADR
+  - 50868 "TV/FM Tuner Pal I" (variant of 50682)
+  - 50999 "TV/FM Tuner Secam" (variant of 50682)
+
+Guillemot
+~~~~~~~~~
+
+Models:
+
+- Maxi-TV PCI (ZR36120)
+- Maxi TV Video 2 = LR50 Rev.Q (FI1216MF, PAL BG+SECAM)
+- Maxi TV Video 3 = CPH064 (PAL BG + SECAM)
+
+Mentor
+~~~~~~
+
+Mentor TV card ("55-878TV-U1") = Pixelview 878TV(Rev.3F) (w/FM w/Remote)
+
+Prolink
+~~~~~~~
+
+- TV cards:
+
+  - PixelView Play TV pro - (Model: PV-BT878P+ REV 8E)
+  - PixelView Play TV pro - (Model: PV-BT878P+ REV 9D)
+  - PixelView Play TV pro - (Model: PV-BT878P+ REV 4C / 8D / 10A )
+  - PixelView Play TV - (Model: PV-BT848P+)
+  - 878TV - (Model: PV-BT878TV)
+
+- Multimedia TV packages (card + software pack):
+
+  - PixelView Play TV Theater - (Model: PV-M4200) =  PixelView Play TV pro + Software
+  - PixelView Play TV PAK -     (Model: PV-BT878P+ REV 4E)
+  - PixelView Play TV/VCR -     (Model: PV-M3200 REV 4C / 8D / 10A )
+  - PixelView Studio PAK -      (Model:    M2200 REV 4C / 8D / 10A )
+  - PixelView PowerStudio PAK - (Model: PV-M3600 REV 4E)
+  - PixelView DigitalVCR PAK -  (Model: PV-M2400 REV 4C / 8D / 10A )
+  - PixelView PlayTV PAK II (TV/FM card + usb camera)  PV-M3800
+  - PixelView PlayTV XP PV-M4700,PV-M4700(w/FM)
+  - PixelView PlayTV DVR PV-M4600  package contents:PixelView PlayTV pro, windvr & videoMail s/w
+
+- Further Cards:
+
+  - PV-BT878P+rev.9B (Play TV Pro, opt. w/FM w/NICAM)
+  - PV-BT878P+rev.2F
+  - PV-BT878P Rev.1D (bt878, capture only)
+
+  - XCapture PV-CX881P (cx23881)
+  - PlayTV HD PV-CX881PL+, PV-CX881PL+(w/FM) (cx23881)
+
+  - DTV3000 PV-DTV3000P+ DVB-S CI = Twinhan VP-1030
+  - DTV2000 DVB-S = Twinhan VP-1020
+
+- Video Conferencing:
+
+  - PixelView Meeting PAK - (Model: PV-BT878P)
+  - PixelView Meeting PAK Lite - (Model: PV-BT878P)
+  - PixelView Meeting PAK plus - (Model: PV-BT878P+rev 4C/8D/10A)
+  - PixelView Capture - (Model: PV-BT848P)
+  - PixelView PlayTV USB pro
+  - Model No. PV-NT1004+, PV-NT1004+ (w/FM) = NT1004 USB decoder chip + SAA7113 video decoder chip
+
+Dynalink
+~~~~~~~~
+
+These are CPH series.
+
+Phoebemicro
+~~~~~~~~~~~
+
+- TV Master    = CPH030 or CPH060
+- TV Master FM = CPH050
+
+Genius/Kye
+~~~~~~~~~~
+
+- Video Wonder/Genius Internet Video Kit = LR37 Rev.C
+- Video Wonder Pro II (848 or 878) = LR26
+
+Tekram
+~~~~~~
+
+- VideoCap C205 (Bt848)
+- VideoCap C210 (zr36120 +Philips)
+- CaptureTV M200 (ISA)
+- CaptureTV M205 (Bt848)
+
+Lucky Star
+~~~~~~~~~~
+
+- Image World Conference TV = LR50 Rev. Q
+
+Leadtek
+~~~~~~~
+
+- WinView 601 (Bt848)
+- WinView 610 (Zoran)
+- WinFast2000
+- WinFast2000 XP
+
+Support for the Leadtek WinView 601 TV/FM
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Author of this section: Jon Tombs <jon@gte.esi.us.es>
+
+This card is basically the same as all the rest (Bt484A, Philips tuner),
+the main difference is that they have attached a programmable attenuator to 3
+GPIO lines in order to give some volume control. They have also stuck an
+infra-red remote control decoded on the board, I will add support for this
+when I get time (it simple generates an interrupt for each key press, with
+the key code is placed in the GPIO port).
+
+I don't yet have any application to test the radio support. The tuner
+frequency setting should work but it is possible that the audio multiplexer
+is wrong. If it doesn't work, send me email.
+
+
+- No Thanks to Leadtek they refused to answer any questions about their
+  hardware. The driver was written by visual inspection of the card. If you
+  use this driver, send an email insult to them, and tell them you won't
+  continue buying their hardware unless they support Linux.
+
+- Little thanks to Princeton Technology Corp (http://www.princeton.com.tw)
+  who make the audio attenuator. Their publicly available data-sheet available
+  on their web site doesn't include the chip programming information! Hidden
+  on their server are the full data-sheets, but don't ask how I found it.
+
+To use the driver I use the following options, the tuner and pll settings might
+be different in your country. You can force it via modprobe parameters.
+For example::
+
+    modprobe bttv  tuner=1 pll=28 radio=1 card=17
+
+Sets tuner type 1 (Philips PAL_I), PLL with a 28 MHz crystal, enables
+FM radio and selects bttv card ID 17 (Leadtek WinView 601).
+
+
+KNC One
+~~~~~~~
+
+- TV-Station
+- TV-Station SE (+Software Bundle)
+- TV-Station pro (+TV stereo)
+- TV-Station FM (+Radio)
+- TV-Station RDS (+RDS)
+- TV Station SAT (analog satellite)
+- TV-Station DVB-S
+
+.. note:: newer Cards have saa7134, but model name stayed the same?
+
+Provideo
+~~~~~~~~
+
+-  PV951 or PV-951, now named PV-951T
+   (also are sold as:
+   Boeder TV-FM Video Capture Card,
+   Titanmedia Supervision TV-2400,
+   Provideo PV951 TF,
+   3DeMon PV951,
+   MediaForte TV-Vision PV951,
+   Yoko PV951,
+   Vivanco Tuner Card PCI Art.-Nr.: 68404
+   )
+
+- Surveillance Series:
+
+ - PV-141
+ - PV-143
+ - PV-147
+ - PV-148 (capture only)
+ - PV-150
+ - PV-151
+
+- TV-FM Tuner Series:
+
+ - PV-951TDV (tv tuner + 1394)
+ - PV-951T/TF
+ - PV-951PT/TF
+ - PV-956T/TF Low Profile
+ - PV-911
+
+Highscreen
+~~~~~~~~~~
+
+Models:
+
+- TV Karte = LR50 Rev.S
+- TV-Boostar = Terratec Terra TV+ Version 1.0 (Bt848, tda9821) "ceb105.pcb"
+
+Zoltrix
+~~~~~~~
+
+Models:
+
+- Face to Face Capture (Bt848 capture only) (PCB "VP-2848")
+- Face To Face TV MAX (Bt848) (PCB "VP-8482 Rev1.3")
+- Genie TV (Bt878) (PCB "VP-8790 Rev 2.1")
+- Genie Wonder Pro
+
+AVerMedia
+~~~~~~~~~
+
+- AVer FunTV Lite (ISA, AV3001 chipset)  "M101.C"
+- AVerTV
+- AVerTV Stereo
+- AVerTV Studio (w/FM)
+- AVerMedia TV98 with Remote
+- AVerMedia TV/FM98 Stereo
+- AVerMedia TVCAM98
+- TVCapture (Bt848)
+- TVPhone (Bt848)
+- TVCapture98 (="AVerMedia TV98" in USA) (Bt878)
+- TVPhone98 (Bt878, w/FM)
+
+======== =========== =============== ======= ====== ======== =======================
+PCB      PCI-ID      Model-Name      Eeprom  Tuner  Sound    Country
+======== =========== =============== ======= ====== ======== =======================
+M101.C   ISA !
+M108-B      Bt848                     --     FR1236		 US   [#f2]_, [#f3]_
+M1A8-A      Bt848    AVer TV-Phone           FM1216  --
+M168-T   1461:0003   AVerTV Studio   48:17   FM1216 TDA9840T  D    [#f1]_ w/FM w/Remote
+M168-U   1461:0004   TVCapture98     40:11   FI1216   --      D    w/Remote
+M168II-B 1461:0003   Medion MD9592   48:16   FM1216 TDA9873H  D    w/FM
+======== =========== =============== ======= ====== ======== =======================
+
+.. [#f1] Daughterboard MB68-A with TDA9820T and TDA9840T
+.. [#f2] Sony NE41S soldered (stereo sound?)
+.. [#f3] Daughterboard M118-A w/ pic 16c54 and 4 MHz quartz
+
+- US site has different drivers for (as of 09/2002):
+
+  - EZ Capture/InterCam PCI (BT-848 chip)
+  - EZ Capture/InterCam PCI (BT-878 chip)
+  - TV-Phone (BT-848 chip)
+  - TV98 (BT-848 chip)
+  - TV98 With Remote (BT-848 chip)
+  - TV98 (BT-878 chip)
+  - TV98 With Remote (BT-878)
+  - TV/FM98 (BT-878 chip)
+  - AVerTV
+  - AverTV Stereo
+  - AVerTV Studio
+
+DE hat diverse Treiber fuer diese Modelle (Stand 09/2002):
+
+  - TVPhone (848) mit Philips tuner FR12X6 (w/ FM radio)
+  - TVPhone (848) mit Philips tuner FM12X6 (w/ FM radio)
+  - TVCapture (848) w/Philips tuner FI12X6
+  - TVCapture (848) non-Philips tuner
+  - TVCapture98 (Bt878)
+  - TVPhone98 (Bt878)
+  - AVerTV und TVCapture98 w/VCR (Bt 878)
+  - AVerTVStudio und TVPhone98 w/VCR (Bt878)
+  - AVerTV GO Series (Kein SVideo Input)
+  - AVerTV98 (BT-878 chip)
+  - AVerTV98 mit Fernbedienung (BT-878 chip)
+  - AVerTV/FM98 (BT-878 chip)
+
+  - VDOmate (www.averm.com.cn) = M168U ?
+
+Aimslab
+~~~~~~~
+
+Models:
+
+- Video Highway or "Video Highway TR200" (ISA)
+- Video Highway Xtreme (aka "VHX") (Bt848, FM w/ TEA5757)
+
+IXMicro (former: IMS=Integrated Micro Solutions)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- IXTV BT848 (=TurboTV)
+- IXTV BT878
+- IMS TurboTV (Bt848)
+
+Lifetec/Medion/Tevion/Aldi
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- LT9306/MD9306 = CPH061
+- LT9415/MD9415 = LR90 Rev.F or Rev.G
+- MD9592 = Avermedia TVphone98 (PCI_ID=1461:0003), PCB-Rev=M168II-B (w/TDA9873H)
+- MD9717 = KNC One (Rev D4, saa7134, FM1216 MK2 tuner)
+- MD5044 = KNC One (Rev D4, saa7134, FM1216ME MK3 tuner)
+
+Modular Technologies (www.modulartech.com) UK
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- MM100 PCTV (Bt848)
+- MM201 PCTV (Bt878, Bt832) w/ Quartzsight camera
+- MM202 PCTV (Bt878, Bt832, tda9874)
+- MM205 PCTV (Bt878)
+- MM210 PCTV (Bt878) (Galaxy TV, Galaxymedia ?)
+
+Terratec
+~~~~~~~~
+
+Models:
+
+- Terra TV+ Version 1.0 (Bt848), "ceb105.PCB" printed on the PCB, TDA9821
+- Terra TV+ Version 1.1 (Bt878), "LR74 Rev.E" printed on the PCB, TDA9821
+- Terra TValueRadio,             "LR102 Rev.C" printed on the PCB
+- Terra TV/Radio+ Version 1.0,   "80-CP2830100-0" TTTV3 printed on the PCB,
+  "CPH010-E83" on the back, SAA6588T, TDA9873H
+- Terra TValue Version BT878,    "80-CP2830110-0 TTTV4" printed on the PCB,
+  "CPH011-D83" on back
+- Terra TValue Version 1.0       "ceb105.PCB" (really identical to Terra TV+ Version 1.0)
+- Terra TValue New Revision	  "LR102 Rec.C"
+- Terra Active Radio Upgrade (tea5757h, saa6588t)
+
+- LR74 is a newer PCB revision of ceb105 (both incl. connector for Active Radio Upgrade)
+
+- Cinergy 400 (saa7134), "E877 11(S)", "PM820092D" printed on PCB
+- Cinergy 600 (saa7134)
+
+Technisat
+~~~~~~~~~
+
+Models:
+
+- Discos ADR PC-Karte ISA (no TV!)
+- Discos ADR PC-Karte PCI (probably no TV?)
+- Techni-PC-Sat (Sat. analog)
+  Rev 1.2 (zr36120, vpx3220, stv0030, saa5246, BSJE3-494A)
+- Mediafocus I (zr36120/zr36125, drp3510, Sat. analog + ADR Radio)
+- Mediafocus II (saa7146, Sat. analog)
+- SatADR Rev 2.1 (saa7146a, saa7113h, stv0056a, msp3400c, drp3510a, BSKE3-307A)
+- SkyStar 1 DVB  (AV7110) = Technotrend Premium
+- SkyStar 2 DVB  (B2C2) (=Sky2PC)
+
+Siemens
+~~~~~~~
+
+Multimedia eXtension Board (MXB) (SAA7146, SAA7111)
+
+Powercolor
+~~~~~~~~~~
+
+Models:
+
+- MTV878
+       Package comes with different contents:
+
+           a) pcb "MTV878" (CARD=75)
+           b) Pixelview Rev. 4\_
+
+- MTV878R w/Remote Control
+- MTV878F w/Remote Control w/FM radio
+
+Pinnacle
+~~~~~~~~
+
+PCTV models:
+
+- Mirovideo PCTV (Bt848)
+- Mirovideo PCTV SE (Bt848)
+- Mirovideo PCTV Pro (Bt848 + Daughterboard for TV Stereo and FM)
+- Studio PCTV Rave (Bt848 Version = Mirovideo PCTV)
+- Studio PCTV Rave (Bt878 package w/o infrared)
+- Studio PCTV      (Bt878)
+- Studio PCTV Pro  (Bt878 stereo w/ FM)
+- Pinnacle PCTV    (Bt878, MT2032)
+- Pinnacle PCTV Pro (Bt878, MT2032)
+- Pinncale PCTV Sat (bt878a, HM1821/1221) ["Conexant CX24110 with CX24108 tuner, aka HM1221/HM1811"]
+- Pinnacle PCTV Sat XE
+
+M(J)PEG capture and playback models:
+
+- DC1+ (ISA)
+- DC10  (zr36057,     zr36060,      saa7110, adv7176)
+- DC10+ (zr36067,     zr36060,      saa7110, adv7176)
+- DC20  (ql16x24b,zr36050, zr36016, saa7110, saa7187 ...)
+- DC30  (zr36057, zr36050, zr36016, vpx3220, adv7176, ad1843, tea6415, miro FST97A1)
+- DC30+ (zr36067, zr36050, zr36016, vpx3220, adv7176)
+- DC50  (zr36067, zr36050, zr36016, saa7112, adv7176 (2 pcs.?), ad1843, miro FST97A1, Lattice ???)
+
+Lenco
+~~~~~
+
+Models:
+
+- MXR-9565 (=Technisat Mediafocus?)
+- MXR-9571 (Bt848) (=CPH031?)
+- MXR-9575
+- MXR-9577 (Bt878) (=Prolink 878TV Rev.3x)
+- MXTV-9578CP (Bt878) (= Prolink PV-BT878P+4E)
+
+Iomega
+~~~~~~
+
+Buz (zr36067, zr36060, saa7111, saa7185)
+
+LML
+~~~
+   LML33 (zr36067, zr36060, bt819, bt856)
+
+Grandtec
+~~~~~~~~
+
+Models:
+
+- Grand Video Capture (Bt848)
+- Multi Capture Card  (Bt878)
+
+Koutech
+~~~~~~~
+
+Models:
+
+- KW-606 (Bt848)
+- KW-607 (Bt848 capture only)
+- KW-606RSF
+- KW-607A (capture only)
+- KW-608 (Zoran capture only)
+
+IODATA (jp)
+~~~~~~~~~~~
+
+Models:
+
+- GV-BCTV/PCI
+- GV-BCTV2/PCI
+- GV-BCTV3/PCI
+- GV-BCTV4/PCI
+- GV-VCP/PCI (capture only)
+- GV-VCP2/PCI (capture only)
+
+Canopus (jp)
+~~~~~~~~~~~~
+
+WinDVR	= Kworld "KW-TVL878RF"
+
+www.sigmacom.co.kr
+~~~~~~~~~~~~~~~~~~
+
+Sigma Cyber TV II
+
+www.sasem.co.kr
+~~~~~~~~~~~~~~~
+
+Litte OnAir TV
+
+hama
+~~~~
+
+TV/Radio-Tuner Card, PCI (Model 44677) = CPH051
+
+Sigma Designs
+~~~~~~~~~~~~~
+
+Hollywood plus (em8300, em9010, adv7175), (PCB "M340-10") MPEG DVD decoder
+
+Formac
+~~~~~~
+
+Models:
+
+- iProTV (Card for iMac Mezzanine slot, Bt848+SCSI)
+- ProTV (Bt848)
+- ProTV II = ProTV Stereo (Bt878) ["stereo" means FM stereo, tv is still mono]
+
+ATI
+~~~
+
+Models:
+
+- TV-Wonder
+- TV-Wonder VE
+
+Diamond Multimedia
+~~~~~~~~~~~~~~~~~~
+
+DTV2000 (Bt848, tda9875)
+
+Aopen
+~~~~~
+
+- VA1000 Plus (w/ Stereo)
+- VA1000 Lite
+- VA1000 (=LR90)
+
+Intel
+~~~~~
+
+Models:
+
+- Smart Video Recorder (ISA full-length)
+- Smart Video Recorder pro (ISA half-length)
+- Smart Video Recorder III (Bt848)
+
+STB
+~~~
+
+Models:
+
+- STB Gateway 6000704 (bt878)
+- STB Gateway 6000699 (bt848)
+- STB Gateway 6000402 (bt848)
+- STB TV130 PCI
+
+Videologic
+~~~~~~~~~~
+
+Models:
+
+- Captivator Pro/TV (ISA?)
+- Captivator PCI/VC (Bt848 bundled with camera) (capture only)
+
+Technotrend
+~~~~~~~~~~~~
+
+Models:
+
+- TT-SAT PCI (PCB "Sat-PCI Rev.:1.3.1"; zr36125, vpx3225d, stc0056a, Tuner:BSKE6-155A
+- TT-DVB-Sat
+   - revisions 1.1, 1.3, 1.5, 1.6 and 2.1
+   - This card is sold as OEM from:
+
+	- Siemens DVB-s Card
+	- Hauppauge WinTV DVB-S
+	- Technisat SkyStar 1 DVB
+	- Galaxis DVB Sat
+
+   - Now this card is called TT-PCline Premium Family
+   - TT-Budget (saa7146, bsru6-701a)
+     This card is sold as OEM from:
+
+	- Hauppauge WinTV Nova
+	- Satelco Standard PCI (DVB-S)
+   - TT-DVB-C PCI
+
+Teles
+~~~~~
+
+ DVB-s (Rev. 2.2, BSRV2-301A, data only?)
+
+Remote Vision
+~~~~~~~~~~~~~
+
+MX RV605 (Bt848 capture only)
+
+Boeder
+~~~~~~
+
+Models:
+
+- PC ChatCam (Model 68252) (Bt848 capture only)
+- Tv/Fm Capture Card  (Model 68404) = PV951
+
+Media-Surfer  (esc-kathrein.de)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Sat-Surfer (ISA)
+- Sat-Surfer PCI = Techni-PC-Sat
+- Cable-Surfer 1
+- Cable-Surfer 2
+- Cable-Surfer PCI (zr36120)
+- Audio-Surfer (ISA Radio card)
+
+Jetway (www.jetway.com.tw)
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- JW-TV 878M
+- JW-TV 878  = KWorld KW-TV878RF
+
+Galaxis
+~~~~~~~
+
+Models:
+
+- Galaxis DVB Card S CI
+- Galaxis DVB Card C CI
+- Galaxis DVB Card S
+- Galaxis DVB Card C
+- Galaxis plug.in S [new Name: Galaxis DVB Card S CI]
+
+Hauppauge
+~~~~~~~~~
+
+Models:
+
+- many many WinTV models ...
+- WinTV DVBs = Technotrend Premium 1.3
+- WinTV NOVA = Technotrend Budget 1.1 "S-DVB DATA"
+- WinTV NOVA-CI "SDVBACI"
+- WinTV Nova USB (=Technotrend USB 1.0)
+- WinTV-Nexus-s (=Technotrend Premium 2.1 or 2.2)
+- WinTV PVR
+- WinTV PVR 250
+- WinTV PVR 450
+
+US models
+
+-990 WinTV-PVR-350 (249USD) (iTVC15 chipset + radio)
+-980 WinTV-PVR-250 (149USD) (iTVC15 chipset)
+-880 WinTV-PVR-PCI (199USD) (KFIR chipset + bt878)
+-881 WinTV-PVR-USB
+-190 WinTV-GO
+-191 WinTV-GO-FM
+-404 WinTV
+-401 WinTV-radio
+-495 WinTV-Theater
+-602 WinTV-USB
+-621 WinTV-USB-FM
+-600 USB-Live
+-698 WinTV-HD
+-697 WinTV-D
+-564 WinTV-Nexus-S
+
+Deutsche Modelle:
+
+-603 WinTV GO
+-719 WinTV Primio-FM
+-718 WinTV PCI-FM
+-497 WinTV Theater
+-569 WinTV USB
+-568 WinTV USB-FM
+-882 WinTV PVR
+-981 WinTV PVR 250
+-891 WinTV-PVR-USB
+-541 WinTV Nova
+-488 WinTV Nova-Ci
+-564 WinTV-Nexus-s
+-727 WinTV-DVB-c
+-545 Common Interface
+-898 WinTV-Nova-USB
+
+UK models:
+
+-607 WinTV Go
+-693,793 WinTV Primio FM
+-647,747 WinTV PCI FM
+-498 WinTV Theater
+-883 WinTV PVR
+-893 WinTV PVR USB  (Duplicate entry)
+-566 WinTV USB (UK)
+-573 WinTV USB FM
+-429 Impact VCB (bt848)
+-600 USB Live (Video-In 1x Comp, 1xSVHS)
+-542 WinTV Nova
+-717 WinTV DVB-S
+-909 Nova-t PCI
+-893 Nova-t USB   (Duplicate entry)
+-802 MyTV
+-804 MyView
+-809 MyVideo
+-872 MyTV2Go FM
+-546 WinTV Nova-S CI
+-543 WinTV Nova
+-907 Nova-S USB
+-908 Nova-T USB
+-717 WinTV Nexus-S
+-157 DEC3000-s Standalone + USB
+
+Spain:
+
+-685 WinTV-Go
+-690 WinTV-PrimioFM
+-416 WinTV-PCI Nicam Estereo
+-677 WinTV-PCI-FM
+-699 WinTV-Theater
+-683 WinTV-USB
+-678 WinTV-USB-FM
+-983 WinTV-PVR-250
+-883 WinTV-PVR-PCI
+-993 WinTV-PVR-350
+-893 WinTV-PVR-USB
+-728 WinTV-DVB-C PCI
+-832 MyTV2Go
+-869 MyTV2Go-FM
+-805 MyVideo (USB)
+
+
+Matrix-Vision
+~~~~~~~~~~~~~
+
+Models:
+
+- MATRIX-Vision MV-Delta
+- MATRIX-Vision MV-Delta 2
+- MVsigma-SLC (Bt848)
+
+Conceptronic (.net)
+~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- TVCON FM,  TV card w/ FM = CPH05x
+- TVCON = CPH06x
+
+BestData
+~~~~~~~~
+
+Models:
+
+- HCC100 = VCC100rev1 + camera
+- VCC100 rev1 (bt848)
+- VCC100 rev2 (bt878)
+
+Gallant  (www.gallantcom.com) www.minton.com.tw
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Intervision IV-510 (capture only bt8x8)
+- Intervision IV-550 (bt8x8)
+- Intervision IV-100 (zoran)
+- Intervision IV-1000 (bt8x8)
+
+Asonic (www.asonic.com.cn) (website down)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+SkyEye tv 878
+
+Hoontech
+~~~~~~~~
+
+878TV/FM
+
+Teppro (www.itcteppro.com.tw)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- ITC PCITV (Card Ver 1.0) "Teppro TV1/TVFM1 Card"
+- ITC PCITV (Card Ver 2.0)
+- ITC PCITV (Card Ver 3.0) = "PV-BT878P+ (REV.9D)"
+- ITC PCITV (Card Ver 4.0)
+- TEPPRO IV-550 (For BT848 Main Chip)
+- ITC DSTTV (bt878, satellite)
+- ITC VideoMaker (saa7146, StreamMachine sm2110, tvtuner) "PV-SM2210P+ (REV:1C)"
+
+Kworld (www.kworld.com.tw)
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+PC TV Station:
+
+- KWORLD KW-TV878R  TV (no radio)
+- KWORLD KW-TV878RF TV (w/ radio)
+- KWORLD KW-TVL878RF (low profile)
+- KWORLD KW-TV713XRF (saa7134)
+
+
+ MPEG TV Station (same cards as above plus WinDVR Software MPEG en/decoder)
+
+- KWORLD KW-TV878R -Pro   TV (no Radio)
+- KWORLD KW-TV878RF-Pro   TV (w/ Radio)
+- KWORLD KW-TV878R -Ultra TV (no Radio)
+- KWORLD KW-TV878RF-Ultra TV (w/ Radio)
+
+JTT/ Justy Corp.(http://www.jtt.ne.jp/)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+JTT-02 (JTT TV) "TV watchmate pro" (bt848)
+
+ADS www.adstech.com
+~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Channel Surfer TV ( CHX-950 )
+- Channel Surfer TV+FM ( CHX-960FM )
+
+AVEC www.prochips.com
+~~~~~~~~~~~~~~~~~~~~~
+
+AVEC Intercapture (bt848, tea6320)
+
+NoBrand
+~~~~~~~
+
+TV Excel = Australian Name for "PV-BT878P+ 8E" or "878TV Rev.3\_"
+
+Mach www.machspeed.com
+~~~~~~~~~~~~~~~~~~~~~~
+
+Mach TV 878
+
+Eline www.eline-net.com/
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Eline Vision TVMaster / TVMaster FM (ELV-TVM/ ELV-TVM-FM) = LR26  (bt878)
+- Eline Vision TVMaster-2000 (ELV-TVM-2000, ELV-TVM-2000-FM)= LR138 (saa713x)
+
+Spirit
+~~~~~~
+
+- Spirit TV Tuner/Video Capture Card (bt848)
+
+Boser www.boser.com.tw
+~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- HS-878 Mini PCI Capture Add-on Card
+- HS-879 Mini PCI 3D Audio and Capture Add-on Card (w/ ES1938 Solo-1)
+
+Satelco www.citycom-gmbh.de, www.satelco.de
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- TV-FM =KNC1 saa7134
+- Standard PCI (DVB-S) = Technotrend Budget
+- Standard PCI (DVB-S) w/ CI
+- Satelco Highend PCI (DVB-S) = Technotrend Premium
+
+
+Sensoray www.sensoray.com
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Sensoray 311 (PC/104 bus)
+- Sensoray 611 (PCI)
+
+CEI (Chartered Electronics Industries Pte Ltd [CEI] [FCC ID HBY])
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- TV Tuner  -  HBY-33A-RAFFLES  Brooktree Bt848KPF + Philips
+- TV Tuner MG9910  -  HBY33A-TVO  CEI + Philips SAA7110 + OKI M548262 + ST STV8438CV
+- Primetime TV (ISA)
+
+  - acquired by Singapore Technologies
+  - now operating as Chartered Semiconductor Manufacturing
+  - Manufacturer of video cards is listed as:
+
+    - Cogent Electronics Industries [CEI]
+
+AITech
+~~~~~~
+
+Models:
+
+- Wavewatcher TV (ISA)
+- AITech WaveWatcher TV-PCI = can be LR26 (Bt848) or LR50 (BT878)
+- WaveWatcher TVR-202 TV/FM Radio Card (ISA)
+
+MAXRON
+~~~~~~
+
+Maxron MaxTV/FM Radio (KW-TV878-FNT) = Kworld or JW-TV878-FBK
+
+www.ids-imaging.de
+~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Falcon Series (capture only)
+
+In USA: http://www.theimagingsource.com/
+- DFG/LC1
+
+www.sknet-web.co.jp
+~~~~~~~~~~~~~~~~~~~
+
+SKnet Monster TV (saa7134)
+
+A-Max www.amaxhk.com (Colormax, Amax, Napa)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+APAC Viewcomp 878
+
+Cybertainment
+~~~~~~~~~~~~~
+
+Models:
+
+- CyberMail AV Video Email Kit w/ PCI Capture Card (capture only)
+- CyberMail Xtreme
+
+These are Flyvideo
+
+VCR (http://www.vcrinc.com/)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Video Catcher 16
+
+Twinhan
+~~~~~~~
+
+Models:
+
+- DST Card/DST-IP (bt878, twinhan asic) VP-1020
+  - Sold as:
+
+    - KWorld DVBS Satellite TV-Card
+    - Powercolor DSTV Satellite Tuner Card
+    - Prolink Pixelview DTV2000
+    - Provideo PV-911 Digital Satellite TV Tuner Card With Common Interface ?
+
+- DST-CI Card (DVB Satellite) VP-1030
+- DCT Card (DVB cable)
+
+MSI
+~~~
+
+Models:
+
+- MSI TV@nywhere Tuner Card (MS-8876) (CX23881/883) Not Bt878 compatible.
+- MS-8401 DVB-S
+
+Focus www.focusinfo.com
+~~~~~~~~~~~~~~~~~~~~~~~
+
+InVideo PCI (bt878)
+
+Sdisilk www.sdisilk.com/
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- SDI Silk 100
+- SDI Silk 200 SDI Input Card
+
+www.euresys.com
+~~~~~~~~~~~~~~~
+
+PICOLO series
+
+PMC/Pace
+~~~~~~~~
+
+www.pacecom.co.uk website closed
+
+Mercury www.kobian.com (UK and FR)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- LR50
+- LR138RBG-Rx  == LR138
+
+TEC sound
+~~~~~~~~~
+
+TV-Mate = Zoltrix VP-8482
+
+Though educated googling found: www.techmakers.com
+
+(package and manuals don't have any other manufacturer info) TecSound
+
+Lorenzen www.lorenzen.de
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+SL DVB-S PCI = Technotrend Budget PCI (su1278 or bsru version)
+
+Origo (.uk) www.origo2000.com
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+PC TV Card = LR50
+
+I/O Magic www.iomagic.com
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+PC PVR - Desktop TV Personal Video Recorder DR-PCTV100 = Pinnacle ROB2D-51009464 4.0 + Cyberlink PowerVCR II
+
+Arowana
+~~~~~~~
+
+TV-Karte / Poso Power TV (?) = Zoltrix VP-8482 (?)
+
+iTVC15 boards
+~~~~~~~~~~~~~
+
+kuroutoshikou.com ITVC15
+yuan.com MPG160 PCI TV (Internal PCI MPEG2 encoder card plus TV-tuner)
+
+Asus www.asuscom.com
+~~~~~~~~~~~~~~~~~~~~
+
+Models:
+
+- Asus TV Tuner Card 880 NTSC (low profile, cx23880)
+- Asus TV (saa7134)
+
+Hoontech
+~~~~~~~~
+
+http://www.hoontech.de/
+
+- HART Vision 848 (H-ART Vision 848)
+- HART Vision 878 (H-Art Vision 878)
+
+
+
+Chips used at bttv devices
+--------------------------
+
+- all boards:
+
+  - Brooktree Bt848/848A/849/878/879: video capture chip
+
+- Board specific
+
+  - Miro PCTV:
+
+    - Philips or Temic Tuner
+
+  - Hauppauge Win/TV pci (version 405):
+
+    - Microchip 24LC02B or Philips 8582E2Y:
+
+       - 256 Byte EEPROM with configuration information
+       - I2C 0xa0-0xa1, (24LC02B also responds to 0xa2-0xaf)
+
+    - Philips SAA5246AGP/E: Videotext decoder chip, I2C 0x22-0x23
+
+    - TDA9800: sound decoder
+
+    - Winbond W24257AS-35: 32Kx8 CMOS static RAM (Videotext buffer mem)
+
+    - 14052B: analog switch for selection of sound source
+
+- PAL:
+
+  - TDA5737: VHF, hyperband and UHF mixer/oscillator for TV and VCR 3-band tuners
+  - TSA5522: 1.4 GHz I2C-bus controlled synthesizer, I2C 0xc2-0xc3
+
+- NTSC:
+
+  - TDA5731: VHF, hyperband and UHF mixer/oscillator for TV and VCR 3-band tuners
+  - TSA5518: no datasheet available on Philips site
+
+- STB TV pci:
+
+  - ???
+  - if you want better support for STB cards send me info!
+    Look at the board! What chips are on it?
+
+
+
+
+Specs
+-----
+
+Philips		http://www.Semiconductors.COM/pip/
+
+Conexant	http://www.conexant.com/
+
+Micronas	http://www.micronas.com/en/home/index.html
+
+Thanks
+------
+
+Many thanks to:
+
+- Markus Schroeder <schroedm@uni-duesseldorf.de> for information on the Bt848
+  and tuner programming and his control program xtvc.
+
+- Martin Buck <martin-2.buck@student.uni-ulm.de> for his great Videotext
+  package.
+
+- Gerd Hoffmann for the MSP3400 support and the modular
+  I2C, tuner, ... support.
+
+
+- MATRIX Vision for giving us 2 cards for free, which made support of
+  single crystal operation possible.
+
+- MIRO for providing a free PCTV card and detailed information about the
+  components on their cards. (E.g. how the tuner type is detected)
+  Without their card I could not have debugged the NTSC mode.
+
+- Hauppauge for telling how the sound input is selected and what components
+  they do and will use on their radio cards.
+  Also many thanks for faxing me the FM1216 data sheet.
+
+Contributors
+------------
+
+Michael Chu <mmchu@pobox.com>
+  AverMedia fix and more flexible card recognition
+
+Alan Cox <alan@lxorguk.ukuu.org.uk>
+  Video4Linux interface and 2.1.x kernel adaptation
+
+Chris Kleitsch
+  Hardware I2C
+
+Gerd Hoffmann
+  Radio card (ITT sound processor)
+
+bigfoot <bigfoot@net-way.net>
+
+Ragnar Hojland Espinosa <ragnar@macula.net>
+  ConferenceTV card
+
+
++ many more (please mail me if you are missing in this list and would
+	     like to be mentioned)
diff --git a/Documentation/admin-guide/media/building.rst b/Documentation/admin-guide/media/building.rst
new file mode 100644
index 000000000..7a413ba07
--- /dev/null
+++ b/Documentation/admin-guide/media/building.rst
@@ -0,0 +1,357 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================================
+Building support for a media device
+===================================
+
+The first step is to download the Kernel's source code, either via a
+distribution-specific source file or via the Kernel's main git tree\ [1]_.
+
+Please notice, however, that, if:
+
+- you're a braveheart and want to experiment with new stuff;
+- if you want to report a bug;
+- if you're developing new patches
+
+you should use the main media development tree ``master`` branch:
+
+    https://git.linuxtv.org/media.git/
+
+In this case, you may find some useful information at the
+`LinuxTv wiki pages <https://linuxtv.org/wiki>`_:
+
+    https://linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers
+
+.. [1] The upstream Linux Kernel development tree is located at
+
+       https://git.kernel.org/pub/scm/li  nux/kernel/git/torvalds/linux.git/
+
+Configuring the Linux Kernel
+============================
+
+You can access a menu of Kernel building options with::
+
+    $ make menuconfig
+
+Then, select all desired options and exit it, saving the configuration.
+
+The changed configuration will be at the ``.config`` file. It would
+look like::
+
+    ...
+    # CONFIG_RC_CORE is not set
+    # CONFIG_CEC_CORE is not set
+    CONFIG_MEDIA_SUPPORT=m
+    CONFIG_MEDIA_SUPPORT_FILTER=y
+    ...
+
+The media subsystem is controlled by those menu configuration options::
+
+    Device Drivers --->
+	<M> Remote Controller support  --->
+	[ ] HDMI CEC RC integration
+	[ ] Enable CEC error injection support
+	[*] HDMI CEC drivers  --->
+	<*> Multimedia support  --->
+
+The ``Remote Controller support`` option enables the core support for
+remote controllers\ [2]_.
+
+The ``HDMI CEC RC integration`` option enables integration of HDMI CEC
+with Linux, allowing to receive data via HDMI CEC as if it were produced
+by a remote controller directly connected to the machine.
+
+The ``HDMI CEC drivers`` option allow selecting platform and USB drivers
+that receives and/or transmits CEC codes via HDMI interfaces\ [3]_.
+
+The last option (``Multimedia support``) enables support for cameras,
+audio/video grabbers and TV.
+
+The media subsystem support can either be built together with the main
+Kernel or as a module. For most use cases, it is preferred to have it
+built as modules.
+
+.. note::
+
+   Instead of using a menu, the Kernel provides a script with allows
+   enabling configuration options directly. To enable media support
+   and remote controller support using Kernel modules, you could use::
+
+	$ scripts/config -m RC_CORE
+	$ scripts/config -m MEDIA_SUPPORT
+
+.. [2] ``Remote Controller support`` should also be enabled if you
+       want to use some TV card drivers that may depend on the remote
+       controller core support.
+
+.. [3] Please notice that the DRM subsystem also have drivers for GPUs
+       that use the media HDMI CEC support.
+
+       Those GPU-specific drivers are selected via the ``Graphics support``
+       menu, under ``Device Drivers``.
+
+       When a GPU driver supports HDMI CEC, it will automatically
+       enable the CEC core support at the media subsystem.
+
+Media dependencies
+------------------
+
+It should be noticed that enabling the above from a clean config is
+usually not enough. The media subsystem depends on several other Linux
+core support in order to work.
+
+For example, most media devices use a serial communication bus in
+order to talk with some peripherals. Such bus is called I²C
+(Inter-Integrated Circuit). In order to be able to build support
+for such hardware, the I²C bus support should be enabled, either via
+menu or with::
+
+    ./scripts/config -m I2C
+
+Another example: the remote controller core requires support for
+input devices, with can be enabled with::
+
+    ./scripts/config -m INPUT
+
+Other core functionality may also be needed (like PCI and/or USB support),
+depending on the specific driver(s) you would like to enable.
+
+Enabling Remote Controller Support
+----------------------------------
+
+The remote controller menu allows selecting drivers for specific devices.
+It's menu looks like this::
+
+         --- Remote Controller support
+         <M>   Compile Remote Controller keymap modules
+         [*]   LIRC user interface
+         [*]     Support for eBPF programs attached to lirc devices
+         [*]   Remote controller decoders  --->
+         [*]   Remote Controller devices  --->
+
+The ``Compile Remote Controller keymap modules`` option creates key maps for
+several popular remote controllers.
+
+The ``LIRC user interface`` option adds enhanced functionality when using the
+``lirc`` program, by enabling an API that allows userspace to receive raw data
+from remote controllers.
+
+The ``Support for eBPF programs attached to lirc devices`` option allows
+the usage of special programs (called eBPF) that would allow applications
+to add extra remote controller decoding functionality to the Linux Kernel.
+
+The ``Remote controller decoders`` option allows selecting the
+protocols that will be recognized by the Linux Kernel. Except if you
+want to disable some specific decoder, it is suggested to keep all
+sub-options enabled.
+
+The ``Remote Controller devices`` allows you to select the drivers
+that would be needed to support your device.
+
+The same configuration can also be set via the ``script/config``
+script. So, for instance, in order to support the ITE remote controller
+driver (found on Intel NUCs and on some ASUS x86 desktops), you could do::
+
+	$ scripts/config -e INPUT
+	$ scripts/config -e ACPI
+	$ scripts/config -e MODULES
+	$ scripts/config -m RC_CORE
+	$ scripts/config -e RC_DEVICES
+	$ scripts/config -e RC_DECODERS
+	$ scripts/config -m IR_RC5_DECODER
+	$ scripts/config -m IR_ITE_CIR
+
+Enabling HDMI CEC Support
+-------------------------
+
+The HDMI CEC support is set automatically when a driver requires it. So,
+all you need to do is to enable support either for a graphics card
+that needs it or by one of the existing HDMI drivers.
+
+The HDMI-specific drivers are available at the ``HDMI CEC drivers``
+menu\ [4]_::
+
+	--- HDMI CEC drivers
+	< >   ChromeOS EC CEC driver
+	< >   Amlogic Meson AO CEC driver
+	< >   Amlogic Meson G12A AO CEC driver
+	< >   Generic GPIO-based CEC driver
+	< >   Samsung S5P CEC driver
+	< >   STMicroelectronics STiH4xx HDMI CEC driver
+	< >   STMicroelectronics STM32 HDMI CEC driver
+	< >   Tegra HDMI CEC driver
+	< >   SECO Boards HDMI CEC driver
+	[ ]     SECO Boards IR RC5 support
+	< >   Pulse Eight HDMI CEC
+	< >   RainShadow Tech HDMI CEC
+
+.. [4] The above contents is just an example. The actual options for
+       HDMI devices depends on the system's architecture and may vary
+       on new Kernels.
+
+Enabling Media Support
+----------------------
+
+The Media menu has a lot more options than the remote controller menu.
+Once selected, you should see the following options::
+
+	--- Media support
+	[ ] Filter media drivers
+	[*] Autoselect ancillary drivers
+	    Media device types --->
+	    Media core support --->
+	    Video4Linux options --->
+	    Media controller options --->
+	    Digital TV options --->
+	    HDMI CEC options --->
+	    Media drivers --->
+	    Media ancillary drivers --->
+
+Except if you know exactly what you're doing, or if you want to build
+a driver for a SoC platform, it is strongly recommended to keep the
+``Autoselect ancillary drivers`` option turned on, as it will auto-select
+the needed I²C ancillary drivers.
+
+There are now two ways to select media device drivers, as described
+below.
+
+``Filter media drivers`` menu
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This menu is meant to easy setup for PC and Laptop hardware. It works
+by letting the user to specify what kind of media drivers are desired,
+with those options::
+
+	[ ] Cameras and video grabbers
+	[ ] Analog TV
+	[ ] Digital TV
+	[ ] AM/FM radio receivers/transmitters
+	[ ] Software defined radio
+	[ ] Platform-specific devices
+	[ ] Test drivers
+
+So, if you want to add support to a camera or video grabber only,
+select just the first option. Multiple options are allowed.
+
+Once the options on this menu are selected, the building system will
+auto-select the needed core drivers in order to support the selected
+functionality.
+
+.. note::
+
+   Most TV cards are hybrid: they support both Analog TV and Digital TV.
+
+   If you have an hybrid card, you may need to enable both ``Analog TV``
+   and ``Digital TV`` at the menu.
+
+When using this option, the defaults for the media support core
+functionality are usually good enough to provide the basic functionality
+for the driver. Yet, you could manually enable some desired extra (optional)
+functionality using the settings under each of the following
+``Media support`` sub-menus::
+
+	    Media core support --->
+	    Video4Linux options --->
+	    Media controller options --->
+	    Digital TV options --->
+	    HDMI CEC options --->
+
+Once you select the desired filters, the drivers that matches the filtering
+criteria will be available at the ``Media support->Media drivers`` sub-menu.
+
+``Media Core Support`` menu without filtering
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If you disable the ``Filter media drivers`` menu, all drivers available
+for your system whose dependencies are met should be shown at the
+``Media drivers`` menu.
+
+Please notice, however, that you should first ensure that the
+``Media Core Support`` menu has all the core functionality your drivers
+would need, as otherwise the corresponding device drivers won't be shown.
+
+Example
+-------
+
+In order to enable modular support for one of the boards listed on
+:doc:`this table <cx231xx-cardlist>`, with modular media core modules, the
+``.config`` file should contain those lines::
+
+    CONFIG_MODULES=y
+    CONFIG_USB=y
+    CONFIG_I2C=y
+    CONFIG_INPUT=y
+    CONFIG_RC_CORE=m
+    CONFIG_MEDIA_SUPPORT=m
+    CONFIG_MEDIA_SUPPORT_FILTER=y
+    CONFIG_MEDIA_ANALOG_TV_SUPPORT=y
+    CONFIG_MEDIA_DIGITAL_TV_SUPPORT=y
+    CONFIG_MEDIA_USB_SUPPORT=y
+    CONFIG_VIDEO_CX231XX=y
+    CONFIG_VIDEO_CX231XX_DVB=y
+
+Building and installing a new Kernel
+====================================
+
+Once the ``.config`` file has everything needed, all it takes to build
+is to run the ``make`` command::
+
+    $ make
+
+And then install the new Kernel and its modules::
+
+    $ sudo make modules_install
+    $ sudo make install
+
+Building just the new media drivers and core
+============================================
+
+Running a new development Kernel from the development tree is usually risky,
+because it may have experimental changes that may have bugs. So, there are
+some ways to build just the new drivers, using alternative trees.
+
+There is the `Linux Kernel backports project
+<https://backports.wiki.kernel.org/index.php/Main_Page>`_, with contains
+newer drivers meant to be compiled against stable Kernels.
+
+The LinuxTV developers, with are responsible for maintaining the media
+subsystem also maintains a backport tree, with just the media drivers
+daily updated from the newest kernel. Such tree is available at:
+
+https://git.linuxtv.org/media_build.git/
+
+It should be noticed that, while it should be relatively safe to use the
+``media_build`` tree for testing purposes, there are not warranties that
+it would work (or even build) on a random Kernel. This tree is maintained
+using a "best-efforts" principle, as time permits us to fix issues there.
+
+If you notice anything wrong on it, feel free to submit patches at the
+Linux media subsystem's mailing list: media@vger.kernel.org. Please
+add ``[PATCH media-build]`` at the e-mail's subject if you submit a new
+patch for the media-build.
+
+Before using it, you should run::
+
+    $ ./build
+
+.. note::
+
+    1) you may need to run it twice if the ``media-build`` tree gets
+       updated;
+    2) you may need to do a ``make distclean`` if you had built it
+       in the past for a different Kernel version than the one you're
+       currently using;
+    3) by default, it will use the same config options for media as
+       the ones defined on the Kernel you're running.
+
+In order to select different drivers or different config options,
+use::
+
+    $ make menuconfig
+
+Then, you can build and install the new drivers::
+
+    $ make && sudo make install
+
+This will override the previous media drivers that your Kernel were
+using.
diff --git a/Documentation/admin-guide/media/c3-isp.dot b/Documentation/admin-guide/media/c3-isp.dot
new file mode 100644
index 000000000..42dc931ee
--- /dev/null
+++ b/Documentation/admin-guide/media/c3-isp.dot
@@ -0,0 +1,26 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0 | <port1> 1} | c3-isp-core\n/dev/v4l-subdev0 | {<port2> 2 | <port3> 3 | <port4> 4 | <port5> 5}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port3 -> n00000008:port0
+	n00000001:port4 -> n0000000b:port0
+	n00000001:port5 -> n0000000e:port0
+	n00000001:port2 -> n00000027
+	n00000008 [label="{{<port0> 0} | c3-isp-resizer0\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000008:port1 -> n00000016 [style=bold]
+	n0000000b [label="{{<port0> 0} | c3-isp-resizer1\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000b:port1 -> n0000001a [style=bold]
+	n0000000e [label="{{<port0> 0} | c3-isp-resizer2\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000e:port1 -> n00000023 [style=bold]
+	n00000011 [label="{{<port0> 0} | c3-mipi-adapter\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000011:port1 -> n00000001:port0 [style=bold]
+	n00000016 [label="c3-isp-cap0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000001a [label="c3-isp-cap1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n0000001e [label="{{<port0> 0} | c3-mipi-csi2\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001e:port1 -> n00000011:port0 [style=bold]
+	n00000023 [label="c3-isp-cap2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n00000027 [label="c3-isp-stats\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n0000002b [label="c3-isp-params\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n0000002b -> n00000001:port1
+	n0000003f [label="{{} | imx290 2-001a\n/dev/v4l-subdev6 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003f:port0 -> n0000001e:port0 [style=bold]
+}
diff --git a/Documentation/admin-guide/media/c3-isp.rst b/Documentation/admin-guide/media/c3-isp.rst
new file mode 100644
index 000000000..ac508b8c6
--- /dev/null
+++ b/Documentation/admin-guide/media/c3-isp.rst
@@ -0,0 +1,101 @@
+.. SPDX-License-Identifier: (GPL-2.0-only OR MIT)
+
+.. include:: <isonum.txt>
+
+=================================================
+Amlogic C3 Image Signal Processing (C3ISP) driver
+=================================================
+
+Introduction
+============
+
+This file documents the Amlogic C3ISP driver located under
+drivers/media/platform/amlogic/c3/isp.
+
+The current version of the driver supports the C3ISP found on
+Amlogic C308L processor.
+
+The driver implements V4L2, Media controller and V4L2 subdev interfaces.
+Camera sensor using V4L2 subdev interface in the kernel is supported.
+
+The driver has been tested on AW419-C308L-Socket platform.
+
+Amlogic C3 ISP
+==============
+
+The Camera hardware found on C308L processors and supported by
+the driver consists of:
+
+- 1 MIPI-CSI-2 module: handles the physical layer of the MIPI CSI-2 receiver and
+  receives data from the connected camera sensor.
+- 1 MIPI-ADAPTER module: organizes MIPI data to meet ISP input requirements and
+  send MIPI data to ISP.
+- 1 ISP (Image Signal Processing) module: contains a pipeline of image processing
+  hardware blocks. The ISP pipeline contains three resizers at the end each of
+  them connected to a DMA interface which writes the output data to memory.
+
+A high-level functional view of the C3 ISP is presented below.::
+
+                                                                   +----------+    +-------+
+                                                                   | Resizer  |--->| WRMIF |
+  +---------+    +------------+    +--------------+    +-------+   |----------+    +-------+
+  | Sensor  |--->| MIPI CSI-2 |--->| MIPI ADAPTER |--->|  ISP  |---|----------+    +-------+
+  +---------+    +------------+    +--------------+    +-------+   | Resizer  |--->| WRMIF |
+                                                                   +----------+    +-------+
+                                                                   |----------+    +-------+
+                                                                   | Resizer  |--->| WRMIF |
+                                                                   +----------+    +-------+
+
+Driver architecture and design
+==============================
+
+With the goal to model the hardware links between the modules and to expose a
+clean, logical and usable interface, the driver registers the following V4L2
+sub-devices:
+
+- 1 `c3-mipi-csi2` sub-device - the MIPI CSI-2 receiver
+- 1 `c3-mipi-adapter` sub-device - the MIPI adapter
+- 1 `c3-isp-core` sub-device - the ISP core
+- 3 `c3-isp-resizer` sub-devices - the ISP resizers
+
+The `c3-isp-core` sub-device is linked to 2 video device nodes for statistics
+capture and parameters programming:
+
+- the `c3-isp-stats` capture video device node for statistics capture
+- the `c3-isp-params` output video device for parameters programming
+
+Each `c3-isp-resizer` sub-device is linked to a capture video device node where
+frames are captured from:
+
+- `c3-isp-resizer0` is linked to the `c3-isp-cap0` capture video device
+- `c3-isp-resizer1` is linked to the `c3-isp-cap1` capture video device
+- `c3-isp-resizer2` is linked to the `c3-isp-cap2` capture video device
+
+The media controller pipeline graph is as follows (with connected a
+IMX290 camera sensor):
+
+.. _isp_topology_graph:
+
+.. kernel-figure:: c3-isp.dot
+    :alt:   c3-isp.dot
+    :align: center
+
+    Media pipeline topology
+
+Implementation
+==============
+
+Runtime configuration of the ISP hardware is performed on the `c3-isp-params`
+video device node using the :ref:`V4L2_META_FMT_C3ISP_PARAMS
+<v4l2-meta-fmt-c3isp-params>` as data format. The buffer structure is defined by
+:c:type:`c3_isp_params_cfg`.
+
+Statistics are captured from the `c3-isp-stats` video device node using the
+:ref:`V4L2_META_FMT_C3ISP_STATS <v4l2-meta-fmt-c3isp-stats>` data format.
+
+The final picture size and format is configured using the V4L2 video
+capture interface on the `c3-isp-cap[0, 2]` video device nodes.
+
+The Amlogic C3 ISP is supported by `libcamera <https://libcamera.org>`_ with a
+dedicated pipeline handler and algorithms that perform run-time image correction
+and enhancement.
diff --git a/Documentation/admin-guide/media/cafe_ccic.rst b/Documentation/admin-guide/media/cafe_ccic.rst
new file mode 100644
index 000000000..ff7fbce13
--- /dev/null
+++ b/Documentation/admin-guide/media/cafe_ccic.rst
@@ -0,0 +1,62 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The cafe_ccic driver
+====================
+
+Author: Jonathan Corbet <corbet@lwn.net>
+
+Introduction
+------------
+
+"cafe_ccic" is a driver for the Marvell 88ALP01 "cafe" CMOS camera
+controller.  This is the controller found in first-generation OLPC systems,
+and this driver was written with support from the OLPC project.
+
+Current status: the core driver works.  It can generate data in YUV422,
+RGB565, and RGB444 formats.  (Anybody looking at the code will see RGB32 as
+well, but that is a debugging aid which will be removed shortly).  VGA and
+QVGA modes work; CIF is there but the colors remain funky.  Only the OV7670
+sensor is known to work with this controller at this time.
+
+To try it out: either of these commands will work:
+
+.. code-block:: none
+
+     $ mplayer tv:// -tv driver=v4l2:width=640:height=480 -nosound
+     $ mplayer tv:// -tv driver=v4l2:width=640:height=480:outfmt=bgr16 -nosound
+
+The "xawtv" utility also works; gqcam does not, for unknown reasons.
+
+Load time options
+-----------------
+
+There are a few load-time options, most of which can be changed after
+loading via sysfs as well:
+
+ - alloc_bufs_at_load:  Normally, the driver will not allocate any DMA
+   buffers until the time comes to transfer data.  If this option is set,
+   then worst-case-sized buffers will be allocated at module load time.
+   This option nails down the memory for the life of the module, but
+   perhaps decreases the chances of an allocation failure later on.
+
+ - dma_buf_size: The size of DMA buffers to allocate.  Note that this
+   option is only consulted for load-time allocation; when buffers are
+   allocated at run time, they will be sized appropriately for the current
+   camera settings.
+
+ - n_dma_bufs: The controller can cycle through either two or three DMA
+   buffers.  Normally, the driver tries to use three buffers; on faster
+   systems, however, it will work well with only two.
+
+ - min_buffers: The minimum number of streaming I/O buffers that the driver
+   will consent to work with.  Default is one, but, on slower systems,
+   better behavior with mplayer can be achieved by setting to a higher
+   value (like six).
+
+ - max_buffers: The maximum number of streaming I/O buffers; default is
+   ten.  That number was carefully picked out of a hat and should not be
+   assumed to actually mean much of anything.
+
+ - flip: If this boolean parameter is set, the sensor will be instructed to
+   invert the video image.  Whether it makes sense is determined by how
+   your particular camera is mounted.
diff --git a/Documentation/admin-guide/media/cardlist.rst b/Documentation/admin-guide/media/cardlist.rst
new file mode 100644
index 000000000..5b38bfd6a
--- /dev/null
+++ b/Documentation/admin-guide/media/cardlist.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+Cards List
+==========
+
+The media subsystem provide support for lots of PCI and USB drivers, plus
+platform-specific drivers. It also contains several ancillary I²C drivers.
+
+The platform-specific drivers are usually present on embedded systems,
+or are supported by the main board. Usually, setting them is done via
+OpenFirmware or ACPI.
+
+The PCI and USB drivers, however, are independent of the system's board,
+and may be added/removed by the user.
+
+You may also take a look at
+https://linuxtv.org/wiki/index.php/Hardware_Device_Information
+for more details about supported cards.
+
+.. toctree::
+	:maxdepth: 2
+
+	usb-cardlist
+	pci-cardlist
+	platform-cardlist
+	radio-cardlist
+	i2c-cardlist
+	misc-cardlist
diff --git a/Documentation/admin-guide/media/cec.rst b/Documentation/admin-guide/media/cec.rst
new file mode 100644
index 000000000..b2e7a3004
--- /dev/null
+++ b/Documentation/admin-guide/media/cec.rst
@@ -0,0 +1,467 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========
+HDMI CEC
+========
+
+Supported hardware in mainline
+==============================
+
+HDMI Transmitters:
+
+- Exynos4
+- Exynos5
+- STIH4xx HDMI CEC
+- V4L2 adv7511 (same HW, but a different driver from the drm adv7511)
+- stm32
+- Allwinner A10 (sun4i)
+- Raspberry Pi
+- dw-hdmi (Synopsis IP)
+- amlogic (meson ao-cec and ao-cec-g12a)
+- drm adv7511/adv7533
+- omap4
+- tegra
+- rk3288, rk3399
+- tda998x
+- DisplayPort CEC-Tunneling-over-AUX on i915, nouveau and amdgpu
+- ChromeOS EC CEC
+- CEC for SECO boards (UDOO x86).
+- Chrontel CH7322
+
+
+HDMI Receivers:
+
+- adv7604/11/12
+- adv7842
+- tc358743
+
+USB Dongles (see below for additional information on how to use these
+dongles):
+
+- Pulse-Eight: the pulse8-cec driver implements the following module option:
+  ``persistent_config``: by default this is off, but when set to 1 the driver
+  will store the current settings to the device's internal eeprom and restore
+  it the next time the device is connected to the USB port.
+
+- RainShadow Tech. Note: this driver does not support the persistent_config
+  module option of the Pulse-Eight driver. The hardware supports it, but I
+  have no plans to add this feature. But I accept patches :-)
+
+- Extron DA HD 4K PLUS HDMI Distribution Amplifier. See
+  :ref:`extron_da_hd_4k_plus` for more information.
+
+Miscellaneous:
+
+- vivid: emulates a CEC receiver and CEC transmitter.
+  Can be used to test CEC applications without actual CEC hardware.
+
+- cec-gpio. If the CEC pin is hooked up to a GPIO pin then
+  you can control the CEC line through this driver. This supports error
+  injection as well.
+
+- cec-gpio and Allwinner A10 (or any other driver that uses the CEC pin
+  framework to drive the CEC pin directly): the CEC pin framework uses
+  high-resolution timers. These timers are affected by NTP daemons that
+  speed up or slow down the clock to sync with the official time. The
+  chronyd server will by default increase or decrease the clock by
+  1/12th. This will cause the CEC timings to go out of spec. To fix this,
+  add a 'maxslewrate 40000' line to chronyd.conf. This limits the clock
+  frequency change to 1/25th, which keeps the CEC timings within spec.
+
+
+Utilities
+=========
+
+Utilities are available here: https://git.linuxtv.org/v4l-utils.git
+
+``utils/cec-ctl``: control a CEC device
+
+``utils/cec-compliance``: test compliance of a remote CEC device
+
+``utils/cec-follower``: emulate a CEC follower device
+
+Note that ``cec-ctl`` has support for the CEC Hospitality Profile as is
+used in some hotel displays. See http://www.htng.org.
+
+Note that the libcec library (https://github.com/Pulse-Eight/libcec) supports
+the linux CEC framework.
+
+If you want to get the CEC specification, then look at the References of
+the HDMI wikipedia page: https://en.wikipedia.org/wiki/HDMI. CEC is part
+of the HDMI specification. HDMI 1.3 is freely available (very similar to
+HDMI 1.4 w.r.t. CEC) and should be good enough for most things.
+
+
+DisplayPort to HDMI Adapters with working CEC
+=============================================
+
+Background: most adapters do not support the CEC Tunneling feature,
+and of those that do many did not actually connect the CEC pin.
+Unfortunately, this means that while a CEC device is created, it
+is actually all alone in the world and will never be able to see other
+CEC devices.
+
+This is a list of known working adapters that have CEC Tunneling AND
+that properly connected the CEC pin. If you find adapters that work
+but are not in this list, then drop me a note.
+
+To test: hook up your DP-to-HDMI adapter to a CEC capable device
+(typically a TV), then run::
+
+	cec-ctl --playback	# Configure the PC as a CEC Playback device
+	cec-ctl -S		# Show the CEC topology
+
+The ``cec-ctl -S`` command should show at least two CEC devices,
+ourselves and the CEC device you are connected to (i.e. typically the TV).
+
+General note: I have only seen this work with the Parade PS175, PS176 and
+PS186 chipsets and the MegaChips 2900. While MegaChips 28x0 claims CEC support,
+I have never seen it work.
+
+USB-C to HDMI
+-------------
+
+Samsung Multiport Adapter EE-PW700: https://www.samsung.com/ie/support/model/EE-PW700BBEGWW/
+
+Kramer ADC-U31C/HF: https://www.kramerav.com/product/ADC-U31C/HF
+
+Club3D CAC-2504: https://www.club-3d.com/en/detail/2449/usb_3.1_type_c_to_hdmi_2.0_uhd_4k_60hz_active_adapter/
+
+DisplayPort to HDMI
+-------------------
+
+Club3D CAC-1080: https://www.club-3d.com/en/detail/2442/displayport_1.4_to_hdmi_2.0b_hdr/
+
+CableCreation (SKU: CD0712): https://www.cablecreation.com/products/active-displayport-to-hdmi-adapter-4k-hdr
+
+HP DisplayPort to HDMI True 4k Adapter (P/N 2JA63AA): https://www.hp.com/us-en/shop/pdp/hp-displayport-to-hdmi-true-4k-adapter
+
+Mini-DisplayPort to HDMI
+------------------------
+
+Club3D CAC-1180: https://www.club-3d.com/en/detail/2443/mini_displayport_1.4_to_hdmi_2.0b_hdr/
+
+Note that passive adapters will never work, you need an active adapter.
+
+The Club3D adapters in this list are all MegaChips 2900 based. Other Club3D adapters
+are PS176 based and do NOT have the CEC pin hooked up, so only the three Club3D
+adapters above are known to work.
+
+I suspect that MegaChips 2900 based designs in general are likely to work
+whereas with the PS176 it is more hit-and-miss (mostly miss). The PS186 is
+likely to have the CEC pin hooked up, it looks like they changed the reference
+design for that chipset.
+
+
+USB CEC Dongles
+===============
+
+These dongles appear as ``/dev/ttyACMX`` devices and need the ``inputattach``
+utility to create the ``/dev/cecX`` devices. Support for the Pulse-Eight
+has been added to ``inputattach`` 1.6.0. Support for the Rainshadow Tech has
+been added to ``inputattach`` 1.6.1.
+
+You also need udev rules to automatically start systemd services::
+
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="2548", ATTRS{idProduct}=="1002", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="pulse8-cec-inputattach@%k.service"
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="2548", ATTRS{idProduct}=="1001", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="pulse8-cec-inputattach@%k.service"
+	SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="ff59", ACTION=="add", TAG+="systemd", ENV{SYSTEMD_WANTS}+="rainshadow-cec-inputattach@%k.service"
+
+and these systemd services:
+
+For Pulse-Eight make /lib/systemd/system/pulse8-cec-inputattach@.service::
+
+	[Unit]
+	Description=inputattach for pulse8-cec device on %I
+
+	[Service]
+	Type=simple
+	ExecStart=/usr/bin/inputattach --pulse8-cec /dev/%I
+
+For the RainShadow Tech make /lib/systemd/system/rainshadow-cec-inputattach@.service::
+
+	[Unit]
+	Description=inputattach for rainshadow-cec device on %I
+
+	[Service]
+	Type=simple
+	ExecStart=/usr/bin/inputattach --rainshadow-cec /dev/%I
+
+
+For proper suspend/resume support create: /lib/systemd/system/restart-cec-inputattach.service::
+
+	[Unit]
+	Description=restart inputattach for cec devices
+	After=suspend.target
+
+	[Service]
+	Type=forking
+	ExecStart=/bin/bash -c 'for d in /dev/serial/by-id/usb-Pulse-Eight*; do /usr/bin/inputattach --daemon --pulse8-cec $d; done; for d in /dev/serial/by-id/usb-RainShadow_Tech*; do /usr/bin/inputattach --daemon --rainshadow-cec $d; done'
+
+	[Install]
+	WantedBy=suspend.target
+
+And run ``systemctl enable restart-cec-inputattach``.
+
+To automatically set the physical address of the CEC device whenever the
+EDID changes, you can use ``cec-ctl`` with the ``-E`` option::
+
+	cec-ctl -E /sys/class/drm/card0-DP-1/edid
+
+This assumes the dongle is connected to the card0-DP-1 output (``xrandr`` will tell
+you which output is used) and it will poll for changes to the EDID and update
+the Physical Address whenever they occur.
+
+To automatically run this command you can use cron. Edit crontab with
+``crontab -e`` and add this line::
+
+	@reboot /usr/local/bin/cec-ctl -E /sys/class/drm/card0-DP-1/edid
+
+This only works for display drivers that expose the EDID in ``/sys/class/drm``,
+such as the i915 driver.
+
+
+CEC Without HPD
+===============
+
+Some displays when in standby mode have no HDMI Hotplug Detect signal, but
+CEC is still enabled so connected devices can send an <Image View On> CEC
+message in order to wake up such displays. Unfortunately, not all CEC
+adapters can support this. An example is the Odroid-U3 SBC that has a
+level-shifter that is powered off when the HPD signal is low, thus
+blocking the CEC pin. Even though the SoC can use CEC without a HPD,
+the level-shifter will prevent this from functioning.
+
+There is a CEC capability flag to signal this: ``CEC_CAP_NEEDS_HPD``.
+If set, then the hardware cannot wake up displays with this behavior.
+
+Note for CEC application implementers: the <Image View On> message must
+be the first message you send, don't send any other messages before.
+Certain very bad but unfortunately not uncommon CEC implementations
+get very confused if they receive anything else but this message and
+they won't wake up.
+
+When writing a driver it can be tricky to test this. There are two
+ways to do this:
+
+1) Get a Pulse-Eight USB CEC dongle, connect an HDMI cable from your
+   device to the Pulse-Eight, but do not connect the Pulse-Eight to
+   the display.
+
+   Now configure the Pulse-Eight dongle::
+
+	cec-ctl -p0.0.0.0 --tv
+
+   and start monitoring::
+
+	sudo cec-ctl -M
+
+   On the device you are testing run::
+
+	cec-ctl --playback
+
+   It should report a physical address of f.f.f.f. Now run this
+   command::
+
+	cec-ctl -t0 --image-view-on
+
+   The Pulse-Eight should see the <Image View On> message. If not,
+   then something (hardware and/or software) is preventing the CEC
+   message from going out.
+
+   To make sure you have the wiring correct just connect the
+   Pulse-Eight to a CEC-enabled display and run the same command
+   on your device: now there is a HPD, so you should see the command
+   arriving at the Pulse-Eight.
+
+2) If you have another linux device supporting CEC without HPD, then
+   you can just connect your device to that device. Yes, you can connect
+   two HDMI outputs together. You won't have a HPD (which is what we
+   want for this test), but the second device can monitor the CEC pin.
+
+   Otherwise use the same commands as in 1.
+
+If CEC messages do not come through when there is no HPD, then you
+need to figure out why. Typically it is either a hardware restriction
+or the software powers off the CEC core when the HPD goes low. The
+first cannot be corrected of course, the second will likely required
+driver changes.
+
+
+Microcontrollers & CEC
+======================
+
+We have seen some CEC implementations in displays that use a microcontroller
+to sample the bus. This does not have to be a problem, but some implementations
+have timing issues. This is hard to discover unless you can hook up a low-level
+CEC debugger (see the next section).
+
+You will see cases where the CEC transmitter holds the CEC line high or low for
+a longer time than is allowed. For directed messages this is not a problem since
+if that happens the message will not be Acked and it will be retransmitted.
+For broadcast messages no such mechanism exists.
+
+It's not clear what to do about this. It is probably wise to transmit some
+broadcast messages twice to reduce the chance of them being lost. Specifically
+<Standby> and <Active Source> are candidates for that.
+
+
+Making a CEC debugger
+=====================
+
+By using a Raspberry Pi 4B and some cheap components you can make
+your own low-level CEC debugger.
+
+The critical component is one of these HDMI female-female passthrough connectors
+(full soldering type 1):
+
+https://elabbay.myshopify.com/collections/camera/products/hdmi-af-af-v1a-hdmi-type-a-female-to-hdmi-type-a-female-pass-through-adapter-breakout-board?variant=45533926147
+
+The video quality is variable and certainly not enough to pass-through 4kp60
+(594 MHz) video. You might be able to support 4kp30, but more likely you will
+be limited to 1080p60 (148.5 MHz). But for CEC testing that is fine.
+
+You need a breadboard and some breadboard wires:
+
+http://www.dx.com/p/diy-40p-male-to-female-male-to-male-female-to-female-dupont-line-wire-3pcs-356089#.WYLOOXWGN7I
+
+If you want to monitor the HPD and/or 5V lines as well, then you need one of
+these 5V to 3.3V level shifters:
+
+https://www.adafruit.com/product/757
+
+(This is just where I got these components, there are many other places you
+can get similar things).
+
+The ground pin of the HDMI connector needs to be connected to a ground
+pin of the Raspberry Pi, of course.
+
+The CEC pin of the HDMI connector needs to be connected to these pins:
+GPIO 6 and GPIO 7. The optional HPD pin of the HDMI connector should
+be connected via the level shifter to these pins: GPIO 23 and GPIO 12.
+The optional 5V pin of the HDMI connector should be connected via the
+level shifter to these pins: GPIO 25 and GPIO 22. Monitoring the HPD and
+5V lines is not necessary, but it is helpful.
+
+This device tree addition in ``arch/arm/boot/dts/bcm2711-rpi-4-b.dts``
+will hook up the cec-gpio driver correctly::
+
+	cec@6 {
+		compatible = "cec-gpio";
+		cec-gpios = <&gpio 6 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+		hpd-gpios = <&gpio 23 GPIO_ACTIVE_HIGH>;
+		v5-gpios = <&gpio 25 GPIO_ACTIVE_HIGH>;
+	};
+
+	cec@7 {
+		compatible = "cec-gpio";
+		cec-gpios = <&gpio 7 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
+		hpd-gpios = <&gpio 12 GPIO_ACTIVE_HIGH>;
+		v5-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>;
+	};
+
+If you haven't hooked up the HPD and/or 5V lines, then just delete those
+lines.
+
+This dts change will enable two cec GPIO devices: I typically use one to
+send/receive CEC commands and the other to monitor. If you monitor using
+an unconfigured CEC adapter then it will use GPIO interrupts which makes
+monitoring very accurate.
+
+If you just want to monitor traffic, then a single instance is sufficient.
+The minimum configuration is one HDMI female-female passthrough connector
+and two female-female breadboard wires: one for connecting the HDMI ground
+pin to a ground pin on the Raspberry Pi, and the other to connect the HDMI
+CEC pin to GPIO 6 on the Raspberry Pi.
+
+The documentation on how to use the error injection is here: :ref:`cec_pin_error_inj`.
+
+``cec-ctl --monitor-pin`` will do low-level CEC bus sniffing and analysis.
+You can also store the CEC traffic to file using ``--store-pin`` and analyze
+it later using ``--analyze-pin``.
+
+You can also use this as a full-fledged CEC device by configuring it
+using ``cec-ctl --tv -p0.0.0.0`` or ``cec-ctl --playback -p1.0.0.0``.
+
+.. _extron_da_hd_4k_plus:
+
+Extron DA HD 4K PLUS CEC Adapter driver
+=======================================
+
+This driver is for the Extron DA HD 4K PLUS series of HDMI Distribution
+Amplifiers: https://www.extron.com/product/dahd4kplusseries
+
+The 2, 4 and 6 port models are supported.
+
+Firmware version 1.02.0001 or higher is required.
+
+Note that older Extron hardware revisions have a problem with the CEC voltage,
+which may mean that CEC will not work. This is fixed in hardware revisions
+E34814 and up.
+
+The CEC support has two modes: the first is a manual mode where userspace has
+to manually control CEC for the HDMI Input and all HDMI Outputs. While this gives
+full control, it is also complicated.
+
+The second mode is an automatic mode, which is selected if the module option
+``vendor_id`` is set. In that case the driver controls CEC and CEC messages
+received in the input will be distributed to the outputs. It is still possible
+to use the /dev/cecX devices to talk to the connected devices directly, but it is
+the driver that configures everything and deals with things like Hotplug Detect
+changes.
+
+The driver also takes care of the EDIDs: /dev/videoX devices are created to
+read the EDIDs and (for the HDMI Input port) to set the EDID.
+
+By default userspace is responsible to set the EDID for the HDMI Input
+according to the EDIDs of the connected displays. But if the ``manufacturer_name``
+module option is set, then the driver will take care of setting the EDID
+of the HDMI Input based on the supported resolutions of the connected displays.
+Currently the driver only supports resolutions 1080p60 and 4kp60: if all connected
+displays support 4kp60, then it will advertise 4kp60 on the HDMI input, otherwise
+it will fall back to an EDID that just reports 1080p60.
+
+The status of the Extron is reported in ``/sys/kernel/debug/cec/cecX/status``.
+
+The extron-da-hd-4k-plus driver implements the following module options:
+
+``debug``
+---------
+
+If set to 1, then all serial port traffic is shown.
+
+``vendor_id``
+-------------
+
+The CEC Vendor ID to report to connected displays.
+
+If set, then the driver will take care of distributing CEC messages received
+on the input to the HDMI outputs. This is done for the following CEC messages:
+
+- <Standby>
+- <Image View On> and <Text View On>
+- <Give Device Power Status>
+- <Set System Audio Mode>
+- <Request Current Latency>
+
+If not set, then userspace is responsible for this, and it will have to
+configure the CEC devices for HDMI Input and the HDMI Outputs manually.
+
+``manufacturer_name``
+---------------------
+
+A three character manufacturer name that is used in the EDID for the HDMI
+Input. If not set, then userspace is responsible for configuring an EDID.
+If set, then the driver will update the EDID automatically based on the
+resolutions supported by the connected displays, and it will not be possible
+anymore to manually set the EDID for the HDMI Input.
+
+``hpd_never_low``
+-----------------
+
+If set, then the Hotplug Detect pin of the HDMI Input will always be high,
+even if nothing is connected to the HDMI Outputs. If not set (the default)
+then the Hotplug Detect pin of the HDMI input will go low if all the detected
+Hotplug Detect pins of the HDMI Outputs are also low.
+
+This option may be changed dynamically.
diff --git a/Documentation/admin-guide/media/ci.rst b/Documentation/admin-guide/media/ci.rst
new file mode 100644
index 000000000..ded4d8fbb
--- /dev/null
+++ b/Documentation/admin-guide/media/ci.rst
@@ -0,0 +1,77 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Conditional Access Interface
+=======================================
+
+
+.. note::
+
+   This documentation is outdated.
+
+This document describes the usage of the high level CI API as
+in accordance to the Linux DVB API. This is a not a documentation for the,
+existing low level CI API.
+
+.. note::
+
+   For the Twinhan/Twinhan clones, the dst_ca module handles the CI
+   hardware handling. This module is loaded automatically if a CI
+   (Common Interface, that holds the CAM (Conditional Access Module)
+   is detected.
+
+ca_zap
+~~~~~~
+
+A userspace application, like ``ca_zap`` is required to handle encrypted
+MPEG-TS streams.
+
+The ``ca_zap`` userland application is in charge of sending the
+descrambling related information to the Conditional Access Module (CAM).
+
+This application requires the following to function properly as of now.
+
+a) Tune to a valid channel, with szap.
+
+  eg: $ szap -c channels.conf -r "TMC" -x
+
+b) a channels.conf containing a valid PMT PID
+
+  eg: TMC:11996:h:0:27500:278:512:650:321
+
+  here 278 is a valid PMT PID. the rest of the values are the
+  same ones that szap uses.
+
+c) after running a szap, you have to run ca_zap, for the
+   descrambler to function,
+
+  eg: $ ca_zap channels.conf "TMC"
+
+d) Hopefully enjoy your favourite subscribed channel as you do with
+   a FTA card.
+
+.. note::
+
+  Currently ca_zap, and dst_test, both are meant for demonstration
+  purposes only, they can become full fledged applications if necessary.
+
+
+Cards that fall in this category
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+At present the cards that fall in this category are the Twinhan and its
+clones, these cards are available as VVMER, Tomato, Hercules, Orange and
+so on.
+
+CI modules that are supported
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The CI module support is largely dependent upon the firmware on the cards
+Some cards do support almost all of the available CI modules. There is
+nothing much that can be done in order to make additional CI modules
+working with these cards.
+
+Modules that have been tested by this driver at present are
+
+(1) Irdeto 1 and 2 from SCM
+(2) Viaccess from SCM
+(3) Dragoncam
diff --git a/Documentation/admin-guide/media/cx18-cardlist.rst b/Documentation/admin-guide/media/cx18-cardlist.rst
new file mode 100644
index 000000000..26f2da9aa
--- /dev/null
+++ b/Documentation/admin-guide/media/cx18-cardlist.rst
@@ -0,0 +1,17 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+CX18 cards list
+===============
+
+Those cards are supported by cx18 driver:
+
+- Hauppauge HVR-1600 (ESMT memory)
+- Hauppauge HVR-1600 (Samsung memory)
+- Compro VideoMate H900
+- Yuan MPC718 MiniPCI DVB-T/Analog
+- Conexant Raptor PAL/SECAM
+- Toshiba Qosmio DVB-T/Analog
+- Leadtek WinFast PVR2100
+- Leadtek WinFast DVR3100
+- GoTView PCI DVD3 Hybrid
+- Hauppauge HVR-1600 (s5h1411/tda18271)
diff --git a/Documentation/admin-guide/media/cx231xx-cardlist.rst b/Documentation/admin-guide/media/cx231xx-cardlist.rst
new file mode 100644
index 000000000..d374101be
--- /dev/null
+++ b/Documentation/admin-guide/media/cx231xx-cardlist.rst
@@ -0,0 +1,99 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+cx231xx cards list
+==================
+
+.. tabularcolumns:: |p{1.4cm}|p{10.0cm}|p{6.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 12 19
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - USB IDs
+   * - 0
+     - Unknown CX231xx video grabber
+     - 0572:5A3C
+   * - 1
+     - Conexant Hybrid TV - CARRAERA
+     - 0572:58A2
+   * - 2
+     - Conexant Hybrid TV - SHELBY
+     - 0572:58A1
+   * - 3
+     - Conexant Hybrid TV - RDE253S
+     - 0572:58A4
+   * - 4
+     - Conexant Hybrid TV - RDU253S
+     - 0572:58A5
+   * - 5
+     - Conexant VIDEO GRABBER
+     - 0572:58A6, 07ca:c039
+   * - 6
+     - Conexant Hybrid TV - rde 250
+     - 0572:589E
+   * - 7
+     - Conexant Hybrid TV - RDU 250
+     - 0572:58A0
+   * - 8
+     - Hauppauge EXETER
+     - 2040:b120, 2040:b140
+   * - 9
+     - Hauppauge USB Live 2
+     - 2040:c200
+   * - 10
+     - Pixelview PlayTV USB Hybrid
+     - 4000:4001
+   * - 11
+     - Pixelview Xcapture USB
+     - 1D19:6109, 4000:4001
+   * - 12
+     - Kworld UB430 USB Hybrid
+     - 1b80:e424
+   * - 13
+     - Iconbit Analog Stick U100 FM
+     - 1f4d:0237
+   * - 14
+     - Hauppauge WinTV USB2 FM (PAL)
+     - 2040:b110
+   * - 15
+     - Hauppauge WinTV USB2 FM (NTSC)
+     - 2040:b111
+   * - 16
+     - Elgato Video Capture V2
+     - 0fd9:0037
+   * - 17
+     - Geniatech OTG102
+     - 1f4d:0102
+   * - 18
+     - Kworld UB445 USB Hybrid
+     - 1b80:e421
+   * - 19
+     - Hauppauge WinTV 930C-HD (1113xx) / HVR-900H (111xxx) / PCTV QuatroStick 521e
+     - 2040:b130, 2040:b138, 2013:0259
+   * - 20
+     - Hauppauge WinTV 930C-HD (1114xx) / HVR-901H (1114xx) / PCTV QuatroStick 522e
+     - 2040:b131, 2040:b139, 2013:025e
+   * - 21
+     - Hauppauge WinTV-HVR-955Q (111401)
+     - 2040:b123, 2040:b124
+   * - 22
+     - Terratec Grabby
+     - 1f4d:0102
+   * - 23
+     - Evromedia USB Full Hybrid Full HD
+     - 1b80:d3b2
+   * - 24
+     - Astrometa T2hybrid
+     - 15f4:0135
+   * - 25
+     - The Imaging Source DFG/USB2pro
+     - 199e:8002
+   * - 26
+     - Hauppauge WinTV-HVR-935C
+     - 2040:b151
+   * - 27
+     - Hauppauge WinTV-HVR-975
+     - 2040:b150
diff --git a/Documentation/admin-guide/media/cx23885-cardlist.rst b/Documentation/admin-guide/media/cx23885-cardlist.rst
new file mode 100644
index 000000000..c47514fea
--- /dev/null
+++ b/Documentation/admin-guide/media/cx23885-cardlist.rst
@@ -0,0 +1,267 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+cx23885 cards list
+==================
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - UNKNOWN/GENERIC
+     - 0070:3400
+
+   * - 1
+     - Hauppauge WinTV-HVR1800lp
+     - 0070:7600
+
+   * - 2
+     - Hauppauge WinTV-HVR1800
+     - 0070:7800, 0070:7801, 0070:7809
+
+   * - 3
+     - Hauppauge WinTV-HVR1250
+     - 0070:7911
+
+   * - 4
+     - DViCO FusionHDTV5 Express
+     - 18ac:d500
+
+   * - 5
+     - Hauppauge WinTV-HVR1500Q
+     - 0070:7790, 0070:7797
+
+   * - 6
+     - Hauppauge WinTV-HVR1500
+     - 0070:7710, 0070:7717
+
+   * - 7
+     - Hauppauge WinTV-HVR1200
+     - 0070:71d1, 0070:71d3
+
+   * - 8
+     - Hauppauge WinTV-HVR1700
+     - 0070:8101
+
+   * - 9
+     - Hauppauge WinTV-HVR1400
+     - 0070:8010
+
+   * - 10
+     - DViCO FusionHDTV7 Dual Express
+     - 18ac:d618
+
+   * - 11
+     - DViCO FusionHDTV DVB-T Dual Express
+     - 18ac:db78
+
+   * - 12
+     - Leadtek Winfast PxDVR3200 H
+     - 107d:6681
+
+   * - 13
+     - Compro VideoMate E650F
+     - 185b:e800
+
+   * - 14
+     - TurboSight TBS 6920
+     - 6920:8888
+
+   * - 15
+     - TeVii S470
+     - d470:9022
+
+   * - 16
+     - DVBWorld DVB-S2 2005
+     - 0001:2005
+
+   * - 17
+     - NetUP Dual DVB-S2 CI
+     - 1b55:2a2c
+
+   * - 18
+     - Hauppauge WinTV-HVR1270
+     - 0070:2211
+
+   * - 19
+     - Hauppauge WinTV-HVR1275
+     - 0070:2215, 0070:221d, 0070:22f2
+
+   * - 20
+     - Hauppauge WinTV-HVR1255
+     - 0070:2251, 0070:22f1
+
+   * - 21
+     - Hauppauge WinTV-HVR1210
+     - 0070:2291, 0070:2295, 0070:2299, 0070:229d, 0070:22f0, 0070:22f3, 0070:22f4, 0070:22f5
+
+   * - 22
+     - Mygica X8506 DMB-TH
+     - 14f1:8651
+
+   * - 23
+     - Magic-Pro ProHDTV Extreme 2
+     - 14f1:8657
+
+   * - 24
+     - Hauppauge WinTV-HVR1850
+     - 0070:8541
+
+   * - 25
+     - Compro VideoMate E800
+     - 1858:e800
+
+   * - 26
+     - Hauppauge WinTV-HVR1290
+     - 0070:8551
+
+   * - 27
+     - Mygica X8558 PRO DMB-TH
+     - 14f1:8578
+
+   * - 28
+     - LEADTEK WinFast PxTV1200
+     - 107d:6f22
+
+   * - 29
+     - GoTView X5 3D Hybrid
+     - 5654:2390
+
+   * - 30
+     - NetUP Dual DVB-T/C-CI RF
+     - 1b55:e2e4
+
+   * - 31
+     - Leadtek Winfast PxDVR3200 H XC4000
+     - 107d:6f39
+
+   * - 32
+     - MPX-885
+     -
+
+   * - 33
+     - Mygica X8502/X8507 ISDB-T
+     - 14f1:8502
+
+   * - 34
+     - TerraTec Cinergy T PCIe Dual
+     - 153b:117e
+
+   * - 35
+     - TeVii S471
+     - d471:9022
+
+   * - 36
+     - Hauppauge WinTV-HVR1255
+     - 0070:2259
+
+   * - 37
+     - Prof Revolution DVB-S2 8000
+     - 8000:3034
+
+   * - 38
+     - Hauppauge WinTV-HVR4400/HVR5500
+     - 0070:c108, 0070:c138, 0070:c1f8
+
+   * - 39
+     - AVerTV Hybrid Express Slim HC81R
+     - 1461:d939
+
+   * - 40
+     - TurboSight TBS 6981
+     - 6981:8888
+
+   * - 41
+     - TurboSight TBS 6980
+     - 6980:8888
+
+   * - 42
+     - Leadtek Winfast PxPVR2200
+     - 107d:6f21
+
+   * - 43
+     - Hauppauge ImpactVCB-e
+     - 0070:7133, 0070:7137
+
+   * - 44
+     - DViCO FusionHDTV DVB-T Dual Express2
+     - 18ac:db98
+
+   * - 45
+     - DVBSky T9580
+     - 4254:9580
+
+   * - 46
+     - DVBSky T980C
+     - 4254:980c
+
+   * - 47
+     - DVBSky S950C
+     - 4254:950c
+
+   * - 48
+     - Technotrend TT-budget CT2-4500 CI
+     - 13c2:3013
+
+   * - 49
+     - DVBSky S950
+     - 4254:0950
+
+   * - 50
+     - DVBSky S952
+     - 4254:0952
+
+   * - 51
+     - DVBSky T982
+     - 4254:0982
+
+   * - 52
+     - Hauppauge WinTV-HVR5525
+     - 0070:f038
+
+   * - 53
+     - Hauppauge WinTV Starburst
+     - 0070:c12a
+
+   * - 54
+     - ViewCast 260e
+     - 1576:0260
+
+   * - 55
+     - ViewCast 460e
+     - 1576:0460
+
+   * - 56
+     - Hauppauge WinTV-QuadHD-DVB
+     - 0070:6a28, 0070:6b28
+
+   * - 57
+     - Hauppauge WinTV-QuadHD-ATSC
+     - 0070:6a18, 0070:6b18
+
+   * - 58
+     - Hauppauge WinTV-HVR-1265(161111)
+     - 0070:2a18
+
+   * - 59
+     - Hauppauge WinTV-Starburst2
+     - 0070:f02a
+
+   * - 60
+     - Hauppauge WinTV-QuadHD-DVB(885)
+     -
+
+   * - 61
+     - Hauppauge WinTV-QuadHD-ATSC(885)
+     -
+
+   * - 62
+     - AVerMedia CE310B
+     - 1461:3100
diff --git a/Documentation/admin-guide/media/cx88-cardlist.rst b/Documentation/admin-guide/media/cx88-cardlist.rst
new file mode 100644
index 000000000..76dc9a14c
--- /dev/null
+++ b/Documentation/admin-guide/media/cx88-cardlist.rst
@@ -0,0 +1,383 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+CX88 cards list
+===============
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - UNKNOWN/GENERIC
+     -
+
+   * - 1
+     - Hauppauge WinTV 34xxx models
+     - 0070:3400, 0070:3401
+
+   * - 2
+     - GDI Black Gold
+     - 14c7:0106, 14c7:0107
+
+   * - 3
+     - PixelView
+     - 1554:4811
+
+   * - 4
+     - ATI TV Wonder Pro
+     - 1002:00f8, 1002:00f9
+
+   * - 5
+     - Leadtek Winfast 2000XP Expert
+     - 107d:6611, 107d:6613
+
+   * - 6
+     - AverTV Studio 303 (M126)
+     - 1461:000b
+
+   * - 7
+     - MSI TV-@nywhere Master
+     - 1462:8606
+
+   * - 8
+     - Leadtek Winfast DV2000
+     - 107d:6620, 107d:6621
+
+   * - 9
+     - Leadtek PVR 2000
+     - 107d:663b, 107d:663c, 107d:6632, 107d:6630, 107d:6638, 107d:6631, 107d:6637, 107d:663d
+
+   * - 10
+     - IODATA GV-VCP3/PCI
+     - 10fc:d003
+
+   * - 11
+     - Prolink PlayTV PVR
+     -
+
+   * - 12
+     - ASUS PVR-416
+     - 1043:4823, 1461:c111
+
+   * - 13
+     - MSI TV-@nywhere
+     -
+
+   * - 14
+     - KWorld/VStream XPert DVB-T
+     - 17de:08a6
+
+   * - 15
+     - DViCO FusionHDTV DVB-T1
+     - 18ac:db00
+
+   * - 16
+     - KWorld LTV883RF
+     -
+
+   * - 17
+     - DViCO FusionHDTV 3 Gold-Q
+     - 18ac:d810, 18ac:d800
+
+   * - 18
+     - Hauppauge Nova-T DVB-T
+     - 0070:9002, 0070:9001, 0070:9000
+
+   * - 19
+     - Conexant DVB-T reference design
+     - 14f1:0187
+
+   * - 20
+     - Provideo PV259
+     - 1540:2580
+
+   * - 21
+     - DViCO FusionHDTV DVB-T Plus
+     - 18ac:db10, 18ac:db11
+
+   * - 22
+     - pcHDTV HD3000 HDTV
+     - 7063:3000
+
+   * - 23
+     - digitalnow DNTV Live! DVB-T
+     - 17de:a8a6
+
+   * - 24
+     - Hauppauge WinTV 28xxx (Roslyn) models
+     - 0070:2801
+
+   * - 25
+     - Digital-Logic MICROSPACE Entertainment Center (MEC)
+     - 14f1:0342
+
+   * - 26
+     - IODATA GV/BCTV7E
+     - 10fc:d035
+
+   * - 27
+     - PixelView PlayTV Ultra Pro (Stereo)
+     -
+
+   * - 28
+     - DViCO FusionHDTV 3 Gold-T
+     - 18ac:d820
+
+   * - 29
+     - ADS Tech Instant TV DVB-T PCI
+     - 1421:0334
+
+   * - 30
+     - TerraTec Cinergy 1400 DVB-T
+     - 153b:1166
+
+   * - 31
+     - DViCO FusionHDTV 5 Gold
+     - 18ac:d500
+
+   * - 32
+     - AverMedia UltraTV Media Center PCI 550
+     - 1461:8011
+
+   * - 33
+     - Kworld V-Stream Xpert DVD
+     -
+
+   * - 34
+     - ATI HDTV Wonder
+     - 1002:a101
+
+   * - 35
+     - WinFast DTV1000-T
+     - 107d:665f
+
+   * - 36
+     - AVerTV 303 (M126)
+     - 1461:000a
+
+   * - 37
+     - Hauppauge Nova-S-Plus DVB-S
+     - 0070:9201, 0070:9202
+
+   * - 38
+     - Hauppauge Nova-SE2 DVB-S
+     - 0070:9200
+
+   * - 39
+     - KWorld DVB-S 100
+     - 17de:08b2, 1421:0341
+
+   * - 40
+     - Hauppauge WinTV-HVR1100 DVB-T/Hybrid
+     - 0070:9400, 0070:9402
+
+   * - 41
+     - Hauppauge WinTV-HVR1100 DVB-T/Hybrid (Low Profile)
+     - 0070:9800, 0070:9802
+
+   * - 42
+     - digitalnow DNTV Live! DVB-T Pro
+     - 1822:0025, 1822:0019
+
+   * - 43
+     - KWorld/VStream XPert DVB-T with cx22702
+     - 17de:08a1, 12ab:2300
+
+   * - 44
+     - DViCO FusionHDTV DVB-T Dual Digital
+     - 18ac:db50, 18ac:db54
+
+   * - 45
+     - KWorld HardwareMpegTV XPert
+     - 17de:0840, 1421:0305
+
+   * - 46
+     - DViCO FusionHDTV DVB-T Hybrid
+     - 18ac:db40, 18ac:db44
+
+   * - 47
+     - pcHDTV HD5500 HDTV
+     - 7063:5500
+
+   * - 48
+     - Kworld MCE 200 Deluxe
+     - 17de:0841
+
+   * - 49
+     - PixelView PlayTV P7000
+     - 1554:4813
+
+   * - 50
+     - NPG Tech Real TV FM Top 10
+     - 14f1:0842
+
+   * - 51
+     - WinFast DTV2000 H
+     - 107d:665e
+
+   * - 52
+     - Geniatech DVB-S
+     - 14f1:0084
+
+   * - 53
+     - Hauppauge WinTV-HVR3000 TriMode Analog/DVB-S/DVB-T
+     - 0070:1404, 0070:1400, 0070:1401, 0070:1402
+
+   * - 54
+     - Norwood Micro TV Tuner
+     -
+
+   * - 55
+     - Shenzhen Tungsten Ages Tech TE-DTV-250 / Swann OEM
+     - c180:c980
+
+   * - 56
+     - Hauppauge WinTV-HVR1300 DVB-T/Hybrid MPEG Encoder
+     - 0070:9600, 0070:9601, 0070:9602
+
+   * - 57
+     - ADS Tech Instant Video PCI
+     - 1421:0390
+
+   * - 58
+     - Pinnacle PCTV HD 800i
+     - 11bd:0051
+
+   * - 59
+     - DViCO FusionHDTV 5 PCI nano
+     - 18ac:d530
+
+   * - 60
+     - Pinnacle Hybrid PCTV
+     - 12ab:1788
+
+   * - 61
+     - Leadtek TV2000 XP Global
+     - 107d:6f18, 107d:6618, 107d:6619
+
+   * - 62
+     - PowerColor RA330
+     - 14f1:ea3d
+
+   * - 63
+     - Geniatech X8000-MT DVBT
+     - 14f1:8852
+
+   * - 64
+     - DViCO FusionHDTV DVB-T PRO
+     - 18ac:db30
+
+   * - 65
+     - DViCO FusionHDTV 7 Gold
+     - 18ac:d610
+
+   * - 66
+     - Prolink Pixelview MPEG 8000GT
+     - 1554:4935
+
+   * - 67
+     - Kworld PlusTV HD PCI 120 (ATSC 120)
+     - 17de:08c1
+
+   * - 68
+     - Hauppauge WinTV-HVR4000 DVB-S/S2/T/Hybrid
+     - 0070:6900, 0070:6904, 0070:6902
+
+   * - 69
+     - Hauppauge WinTV-HVR4000(Lite) DVB-S/S2
+     - 0070:6905, 0070:6906
+
+   * - 70
+     - TeVii S460 DVB-S/S2
+     - d460:9022
+
+   * - 71
+     - Omicom SS4 DVB-S/S2 PCI
+     - A044:2011
+
+   * - 72
+     - TBS 8920 DVB-S/S2
+     - 8920:8888
+
+   * - 73
+     - TeVii S420 DVB-S
+     - d420:9022
+
+   * - 74
+     - Prolink Pixelview Global Extreme
+     - 1554:4976
+
+   * - 75
+     - PROF 7300 DVB-S/S2
+     - B033:3033
+
+   * - 76
+     - SATTRADE ST4200 DVB-S/S2
+     - b200:4200
+
+   * - 77
+     - TBS 8910 DVB-S
+     - 8910:8888
+
+   * - 78
+     - Prof 6200 DVB-S
+     - b022:3022
+
+   * - 79
+     - Terratec Cinergy HT PCI MKII
+     - 153b:1177
+
+   * - 80
+     - Hauppauge WinTV-IR Only
+     - 0070:9290
+
+   * - 81
+     - Leadtek WinFast DTV1800 Hybrid
+     - 107d:6654
+
+   * - 82
+     - WinFast DTV2000 H rev. J
+     - 107d:6f2b
+
+   * - 83
+     - Prof 7301 DVB-S/S2
+     - b034:3034
+
+   * - 84
+     - Samsung SMT 7020 DVB-S
+     - 18ac:dc00, 18ac:dccd
+
+   * - 85
+     - Twinhan VP-1027 DVB-S
+     - 1822:0023
+
+   * - 86
+     - TeVii S464 DVB-S/S2
+     - d464:9022
+
+   * - 87
+     - Leadtek WinFast DTV2000 H PLUS
+     - 107d:6f42
+
+   * - 88
+     - Leadtek WinFast DTV1800 H (XC4000)
+     - 107d:6f38
+
+   * - 89
+     - Leadtek TV2000 XP Global (SC4100)
+     - 107d:6f36
+
+   * - 90
+     - Leadtek TV2000 XP Global (XC4100)
+     - 107d:6f43
+
+   * - 91
+     - NotOnlyTV LV3H
+     -
diff --git a/Documentation/admin-guide/media/cx88.rst b/Documentation/admin-guide/media/cx88.rst
new file mode 100644
index 000000000..e4badb181
--- /dev/null
+++ b/Documentation/admin-guide/media/cx88.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The cx88 driver
+===============
+
+Author:  Gerd Hoffmann
+
+This is a v4l2 device driver for the cx2388x chip.
+
+
+Current status
+--------------
+
+video
+	- Works.
+	- Overlay isn't supported.
+
+audio
+	- Works. The TV standard detection is made by the driver, as the
+	  hardware has bugs to auto-detect.
+	- audio data dma (i.e. recording without loopback cable to the
+	  sound card) is supported via cx88-alsa.
+
+vbi
+	- Works.
+
+
+How to add support for new cards
+--------------------------------
+
+The driver needs some config info for the TV cards.  This stuff is in
+cx88-cards.c.  If the driver doesn't work well you likely need a new
+entry for your card in that file.  Check the kernel log (using dmesg)
+to see whenever the driver knows your card or not.  There is a line
+like this one:
+
+.. code-block:: none
+
+	cx8800[0]: subsystem: 0070:3400, board: Hauppauge WinTV \
+		34xxx models [card=1,autodetected]
+
+If your card is listed as "board: UNKNOWN/GENERIC" it is unknown to
+the driver.  What to do then?
+
+1) Try upgrading to the latest snapshot, maybe it has been added
+   meanwhile.
+2) You can try to create a new entry yourself, have a look at
+   cx88-cards.c.  If that worked, mail me your changes as unified
+   diff ("diff -u").
+3) Or you can mail me the config information.  We need at least the
+   following information to add the card:
+
+     - the PCI Subsystem ID ("0070:3400" from the line above,
+       "lspci -v" output is fine too).
+     - the tuner type used by the card.  You can try to find one by
+       trial-and-error using the tuner=<n> insmod option.  If you
+       know which one the card has you can also have a look at the
+       list in CARDLIST.tuner
diff --git a/Documentation/admin-guide/media/dvb-drivers.rst b/Documentation/admin-guide/media/dvb-drivers.rst
new file mode 100644
index 000000000..66fa4edd0
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-drivers.rst
@@ -0,0 +1,15 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================================
+Digital TV driver-specific documentation
+========================================
+
+.. toctree::
+	:maxdepth: 2
+
+	avermedia
+	bt8xx
+	lmedm04
+	opera-firmware
+	technisat
+	ttusb-dec
diff --git a/Documentation/admin-guide/media/dvb-usb-a800-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-a800-cardlist.rst
new file mode 100644
index 000000000..2ec8bb823
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-a800-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-a800 cards list
+=======================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia AverTV DVB-T USB 2.0 (A800)
+     - 07ca:a800, 07ca:a801
diff --git a/Documentation/admin-guide/media/dvb-usb-af9005-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-af9005-cardlist.rst
new file mode 100644
index 000000000..285160ee8
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-af9005-cardlist.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-af9005 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Afatech DVB-T USB1.1 stick
+     - 15a4:9020
+   * - Ansonic DVB-T USB1.1 stick
+     - 10b9:6000
+   * - TerraTec Cinergy T USB XE
+     - 0ccd:0055
diff --git a/Documentation/admin-guide/media/dvb-usb-af9015-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-af9015-cardlist.rst
new file mode 100644
index 000000000..c557994f7
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-af9015-cardlist.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-af9015 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia A309
+     - 07ca:a309
+   * - AVerMedia AVerTV DVB-T Volar X
+     - 07ca:a815
+   * - Afatech AF9015 reference design
+     - 15a4:9015, 15a4:9016
+   * - AverMedia AVerTV Red HD+ (A850T)
+     - 07ca:850b
+   * - AverMedia AVerTV Volar Black HD (A850)
+     - 07ca:850a
+   * - AverMedia AVerTV Volar GPS 805 (A805)
+     - 07ca:a805
+   * - AverMedia AVerTV Volar M (A815Mac)
+     - 07ca:815a
+   * - Conceptronic USB2.0 DVB-T CTVDIGRCU V3.0
+     - 1b80:e397
+   * - DigitalNow TinyTwin
+     - 13d3:3226
+   * - DigitalNow TinyTwin v2
+     - 1b80:e402
+   * - DigitalNow TinyTwin v3
+     - 1f4d:9016
+   * - Fujitsu-Siemens Slim Mobile USB DVB-T
+     - 07ca:8150
+   * - Genius TVGo DVB-T03
+     - 0458:4012
+   * - KWorld Digital MC-810
+     - 1b80:c810
+   * - KWorld PlusTV DVB-T PCI Pro Card (DVB-T PC160-T)
+     - 1b80:c161
+   * - KWorld PlusTV Dual DVB-T PCI (DVB-T PC160-2T)
+     - 1b80:c160
+   * - KWorld PlusTV Dual DVB-T Stick (DVB-T 399U)
+     - 1b80:e399, 1b80:e400
+   * - KWorld USB DVB-T Stick Mobile (UB383-T)
+     - 1b80:e383
+   * - KWorld USB DVB-T TV Stick II (VS-DVB-T 395U)
+     - 1b80:e396, 1b80:e39b, 1b80:e395, 1b80:e39a
+   * - Leadtek WinFast DTV Dongle Gold
+     - 0413:6029
+   * - Leadtek WinFast DTV2000DS
+     - 0413:6a04
+   * - MSI DIGIVOX Duo
+     - 1462:8801
+   * - MSI Digi VOX mini III
+     - 1462:8807
+   * - Pinnacle PCTV 71e
+     - 2304:022b
+   * - Sveon STV20 Tuner USB DVB-T HDTV
+     - 1b80:e39d
+   * - Sveon STV22 Dual USB DVB-T Tuner HDTV
+     - 1b80:e401
+   * - Telestar Starstick 2
+     - 10b9:8000
+   * - TerraTec Cinergy T Stick Dual RC
+     - 0ccd:0099
+   * - TerraTec Cinergy T Stick RC
+     - 0ccd:0097
+   * - TerraTec Cinergy T USB XE
+     - 0ccd:0069
+   * - TrekStor DVB-T USB Stick
+     - 15a4:901b
+   * - TwinHan AzureWave AD-TU700(704J)
+     - 13d3:3237
+   * - Xtensions XD-380
+     - 1ae7:0381
diff --git a/Documentation/admin-guide/media/dvb-usb-af9035-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-af9035-cardlist.rst
new file mode 100644
index 000000000..63e417077
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-af9035-cardlist.rst
@@ -0,0 +1,74 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-af9035 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia AVerTV Volar HD/PRO (A835)
+     - 07ca:a835, 07ca:b835
+   * - AVerMedia HD Volar (A867)
+     - 07ca:1867, 07ca:a867, 07ca:0337
+   * - AVerMedia TD310 DVB-T2
+     - 07ca:1871
+   * - AVerMedia Twinstar (A825)
+     - 07ca:0825
+   * - Afatech AF9035 reference design
+     - 15a4:9035, 15a4:1000, 15a4:1001, 15a4:1002, 15a4:1003
+   * - Asus U3100Mini Plus
+     - 0b05:1779
+   * - Avermedia A835B(1835)
+     - 07ca:1835
+   * - Avermedia A835B(2835)
+     - 07ca:2835
+   * - Avermedia A835B(3835)
+     - 07ca:3835
+   * - Avermedia A835B(4835)
+     - 07ca:4835
+   * - Avermedia AverTV Volar HD 2 (TD110)
+     - 07ca:a110
+   * - Avermedia H335
+     - 07ca:0335
+   * - Digital Dual TV Receiver CTVDIGDUAL_V2
+     - 1b80:e410
+   * - EVOLVEO XtraTV stick
+     - 1f4d:a115
+   * - Hauppauge WinTV-MiniStick 2
+     - 2040:f900
+   * - ITE 9135 Generic
+     - 048d:9135
+   * - ITE 9135(9005) Generic
+     - 048d:9005
+   * - ITE 9135(9006) Generic
+     - 048d:9006
+   * - ITE 9303 Generic
+     - 048d:9306
+   * - Kworld UB499-2T T09
+     - 1b80:e409
+   * - Leadtek WinFast DTV Dongle Dual
+     - 0413:6a05
+   * - Logilink VG0022A
+     - 1d19:0100
+   * - PCTV AndroiDTV (78e)
+     - 2013:025a
+   * - PCTV microStick (79e)
+     - 2013:0262
+   * - Sveon STV22 Dual DVB-T HDTV
+     - 1b80:e411
+   * - TerraTec Cinergy T Stick
+     - 0ccd:0093
+   * - TerraTec Cinergy T Stick (rev. 2)
+     - 0ccd:00aa
+   * - TerraTec Cinergy T Stick Dual RC (rev. 2)
+     - 0ccd:0099
+   * - TerraTec Cinergy TC2 Stick
+     - 0ccd:10b2
+   * - TerraTec T1
+     - 0ccd:10ae
diff --git a/Documentation/admin-guide/media/dvb-usb-anysee-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-anysee-cardlist.rst
new file mode 100644
index 000000000..1fb5d22a0
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-anysee-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-anysee cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Anysee
+     - 04b4:861f, 1c73:861f
diff --git a/Documentation/admin-guide/media/dvb-usb-au6610-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-au6610-cardlist.rst
new file mode 100644
index 000000000..02b2b7427
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-au6610-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-au6610 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Sigmatek DVB-110
+     - 058f:6610
diff --git a/Documentation/admin-guide/media/dvb-usb-az6007-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-az6007-cardlist.rst
new file mode 100644
index 000000000..db27eb47c
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-az6007-cardlist.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-az6007 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Azurewave 6007
+     - 13d3:0ccd
+   * - Technisat CableStar Combo HD CI
+     - 14f7:0003
+   * - Terratec H7
+     - 0ccd:10b4, 0ccd:10a3
diff --git a/Documentation/admin-guide/media/dvb-usb-az6027-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-az6027-cardlist.rst
new file mode 100644
index 000000000..6d8575e9d
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-az6027-cardlist.rst
@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-az6027 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AZUREWAVE DVB-S/S2 USB2.0 (AZ6027)
+     - 13d3:3275
+   * - Elgato EyeTV Sat
+     - 0fd9:002a, 0fd9:0025, 0fd9:0036
+   * - TERRATEC S7
+     - 0ccd:10a4
+   * - TERRATEC S7 MKII
+     - 0ccd:10ac
+   * - Technisat SkyStar USB 2 HD CI
+     - 14f7:0001, 14f7:0002
diff --git a/Documentation/admin-guide/media/dvb-usb-ce6230-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-ce6230-cardlist.rst
new file mode 100644
index 000000000..09750e8ac
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-ce6230-cardlist.rst
@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-ce6230 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia A310 USB 2.0 DVB-T tuner
+     - 07ca:a310
+   * - Intel CE9500 reference design
+     - 8086:9500
diff --git a/Documentation/admin-guide/media/dvb-usb-cinergyT2-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-cinergyT2-cardlist.rst
new file mode 100644
index 000000000..0ee753929
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-cinergyT2-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-cinergyT2 cards list
+============================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - TerraTec/qanu USB2.0 Highspeed DVB-T Receiver
+     - 0ccd:0x0038
diff --git a/Documentation/admin-guide/media/dvb-usb-cxusb-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-cxusb-cardlist.rst
new file mode 100644
index 000000000..a73f15d1a
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-cxusb-cardlist.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-cxusb cards list
+========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia AVerTVHD Volar (A868R)
+     -
+   * - Conexant DMB-TH Stick
+     -
+   * - DViCO FusionHDTV DVB-T Dual Digital 2
+     -
+   * - DViCO FusionHDTV DVB-T Dual Digital 4
+     -
+   * - DViCO FusionHDTV DVB-T Dual Digital 4 (rev 2)
+     -
+   * - DViCO FusionHDTV DVB-T Dual USB
+     -
+   * - DViCO FusionHDTV DVB-T NANO2
+     -
+   * - DViCO FusionHDTV DVB-T USB (LGZ201)
+     -
+   * - DViCO FusionHDTV DVB-T USB (TH7579)
+     -
+   * - DViCO FusionHDTV5 USB Gold
+     -
+   * - DigitalNow DVB-T Dual USB
+     -
+   * - Medion MD95700 (MDUSBTV-HYBRID)
+     -
+   * - Mygica D689 DMB-TH
+     -
diff --git a/Documentation/admin-guide/media/dvb-usb-dib0700-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dib0700-cardlist.rst
new file mode 100644
index 000000000..4b76b6f10
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dib0700-cardlist.rst
@@ -0,0 +1,162 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dib0700 cards list
+==========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - ASUS My Cinema U3000 Mini DVBT Tuner
+     - 0b05:171f
+   * - ASUS My Cinema U3100 Mini DVBT Tuner
+     - 0b05:173f
+   * - AVerMedia AVerTV DVB-T Express
+     - 07ca:b568
+   * - AVerMedia AVerTV DVB-T Volar
+     - 07ca:a807, 07ca:b808
+   * - Artec T14BR DVB-T
+     - 05d8:810f
+   * - Asus My Cinema-U3000Hybrid
+     - 0b05:1736
+   * - Compro Videomate U500
+     - 185b:1e78, 185b:1e80
+   * - DiBcom NIM7090 reference design
+     - 10b8:1bb2
+   * - DiBcom NIM8096MD reference design
+     - 10b8:1fa8
+   * - DiBcom NIM9090MD reference design
+     - 10b8:2384
+   * - DiBcom STK7070P reference design
+     - 10b8:1ebc
+   * - DiBcom STK7070PD reference design
+     - 10b8:1ebe
+   * - DiBcom STK7700D reference design
+     - 10b8:1ef0
+   * - DiBcom STK7700P reference design
+     - 10b8:1e14, 10b8:1e78
+   * - DiBcom STK7770P reference design
+     - 10b8:1e80
+   * - DiBcom STK807xP reference design
+     - 10b8:1f90
+   * - DiBcom STK807xPVR reference design
+     - 10b8:1f98
+   * - DiBcom STK8096-PVR reference design
+     - 2013:1faa, 10b8:1faa
+   * - DiBcom STK8096GP reference design
+     - 10b8:1fa0
+   * - DiBcom STK9090M reference design
+     - 10b8:2383
+   * - DiBcom TFE7090PVR reference design
+     - 10b8:1bb4
+   * - DiBcom TFE7790P reference design
+     - 10b8:1e6e
+   * - DiBcom TFE8096P reference design
+     - 10b8:1f9C
+   * - Elgato EyeTV DTT
+     - 0fd9:0021
+   * - Elgato EyeTV DTT rev. 2
+     - 0fd9:003f
+   * - Elgato EyeTV Diversity
+     - 0fd9:0011
+   * - Elgato EyeTV Dtt Dlx PD378S
+     - 0fd9:0020
+   * - EvolutePC TVWay+
+     - 1e59:0002
+   * - Gigabyte U7000
+     - 1044:7001
+   * - Gigabyte U8000-RH
+     - 1044:7002
+   * - Hama DVB=T Hybrid USB Stick
+     - 147f:2758
+   * - Hauppauge ATSC MiniCard (B200)
+     - 2040:b200
+   * - Hauppauge ATSC MiniCard (B210)
+     - 2040:b210
+   * - Hauppauge Nova-T 500 Dual DVB-T
+     - 2040:9941, 2040:9950
+   * - Hauppauge Nova-T MyTV.t
+     - 2040:7080
+   * - Hauppauge Nova-T Stick
+     - 2040:7050, 2040:7060, 2040:7070
+   * - Hauppauge Nova-TD Stick (52009)
+     - 2040:5200
+   * - Hauppauge Nova-TD Stick/Elgato Eye-TV Diversity
+     - 2040:9580
+   * - Hauppauge Nova-TD-500 (84xxx)
+     - 2040:8400
+   * - Leadtek WinFast DTV Dongle H
+     - 0413:60f6
+   * - Leadtek Winfast DTV Dongle (STK7700P based)
+     - 0413:6f00, 0413:6f01
+   * - Medion CTX1921 DVB-T USB
+     - 1660:1921
+   * - Microsoft Xbox One Digital TV Tuner
+     - 045e:02d5
+   * - PCTV 2002e
+     - 2013:025c
+   * - PCTV 2002e SE
+     - 2013:025d
+   * - Pinnacle Expresscard 320cx
+     - 2304:022e
+   * - Pinnacle PCTV 2000e
+     - 2304:022c
+   * - Pinnacle PCTV 282e
+     - 2013:0248, 2304:0248
+   * - Pinnacle PCTV 340e HD Pro USB Stick
+     - 2304:023d
+   * - Pinnacle PCTV 72e
+     - 2304:0236
+   * - Pinnacle PCTV 73A
+     - 2304:0243
+   * - Pinnacle PCTV 73e
+     - 2304:0237
+   * - Pinnacle PCTV 73e SE
+     - 2013:0245, 2304:0245
+   * - Pinnacle PCTV DVB-T Flash Stick
+     - 2304:0228
+   * - Pinnacle PCTV Dual DVB-T Diversity Stick
+     - 2304:0229
+   * - Pinnacle PCTV HD Pro USB Stick
+     - 2304:023a
+   * - Pinnacle PCTV HD USB Stick
+     - 2304:023b
+   * - Pinnacle PCTV Hybrid Stick Solo
+     - 2304:023e
+   * - Prolink Pixelview SBTVD
+     - 1554:5010
+   * - Sony PlayTV
+     - 1415:0003
+   * - TechniSat AirStar TeleStick 2
+     - 14f7:0004
+   * - Terratec Cinergy DT USB XS Diversity/ T5
+     - 0ccd:0081, 0ccd:10a1
+   * - Terratec Cinergy DT XS Diversity
+     - 0ccd:005a
+   * - Terratec Cinergy HT Express
+     - 0ccd:0060
+   * - Terratec Cinergy HT USB XE
+     - 0ccd:0058
+   * - Terratec Cinergy T Express
+     - 0ccd:0062
+   * - Terratec Cinergy T USB XXS (HD)/ T3
+     - 0ccd:0078, 0ccd:10a0, 0ccd:00ab
+   * - Uniwill STK7700P based (Hama and others)
+     - 1584:6003
+   * - YUAN High-Tech DiBcom STK7700D
+     - 1164:1e8c
+   * - YUAN High-Tech MC770
+     - 1164:0871
+   * - YUAN High-Tech STK7700D
+     - 1164:1efc
+   * - YUAN High-Tech STK7700PH
+     - 1164:1f08
+   * - Yuan EC372S
+     - 1164:1edc
+   * - Yuan PD378S
+     - 1164:2edc
diff --git a/Documentation/admin-guide/media/dvb-usb-dibusb-mb-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dibusb-mb-cardlist.rst
new file mode 100644
index 000000000..f25a54721
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dibusb-mb-cardlist.rst
@@ -0,0 +1,42 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dibusb-mb cards list
+============================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AVerMedia AverTV DVBT USB1.1
+     - 14aa:0001, 14aa:0002
+   * - Artec T1 USB1.1 TVBOX with AN2135
+     - 05d8:8105, 05d8:8106
+   * - Artec T1 USB1.1 TVBOX with AN2235
+     - 05d8:8107, 05d8:8108
+   * - Artec T1 USB1.1 TVBOX with AN2235 (faulty USB IDs)
+     - 0547:2235
+   * - Artec T1 USB2.0
+     - 05d8:8109, 05d8:810a
+   * - Compro Videomate DVB-U2000 - DVB-T USB1.1 (please confirm to linux-dvb)
+     - 185b:d000, 145f:010c, 185b:d001
+   * - DiBcom USB1.1 DVB-T reference design (MOD3000)
+     - 10b8:0bb8, 10b8:0bb9
+   * - Grandtec USB1.1 DVB-T
+     - 5032:0fa0, 5032:0bb8, 5032:0fa1, 5032:0bb9
+   * - KWorld V-Stream XPERT DTV - DVB-T USB1.1
+     - eb1a:17de, eb1a:17df
+   * - KWorld Xpert DVB-T USB2.0
+     - eb2a:17de
+   * - KWorld/ADSTech Instant DVB-T USB2.0
+     - 06e1:a333, 06e1:a334
+   * - TwinhanDTV USB-Ter USB1.1 / Magic Box I / HAMA USB1.1 DVB-T device
+     - 13d3:3201, 1822:3201, 13d3:3202, 1822:3202
+   * - Unknown USB1.1 DVB-T device ???? please report the name to the author
+     - 1025:005e, 1025:005f
+   * - VideoWalker DVB-T USB
+     - 0458:701e, 0458:701f
diff --git a/Documentation/admin-guide/media/dvb-usb-dibusb-mc-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dibusb-mc-cardlist.rst
new file mode 100644
index 000000000..8d03bae0e
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dibusb-mc-cardlist.rst
@@ -0,0 +1,30 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dibusb-mc cards list
+============================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Artec T1 USB2.0 TVBOX (please check the warm ID)
+     - 05d8:8109, 05d8:810a
+   * - Artec T14 - USB2.0 DVB-T
+     - 05d8:810b, 05d8:810c
+   * - DiBcom USB2.0 DVB-T reference design (MOD3000P)
+     - 10b8:0bc6, 10b8:0bc7
+   * - GRAND - USB2.0 DVB-T adapter
+     - 5032:0bc6, 5032:0bc7
+   * - Humax/Coex DVB-T USB Stick 2.0 High Speed
+     - 10b9:5000, 10b9:5001
+   * - LITE-ON USB2.0 DVB-T Tuner
+     - 04ca:f000, 04ca:f001
+   * - Leadtek - USB2.0 Winfast DTV dongle
+     - 0413:6025, 0413:6026
+   * - MSI Digivox Mini SL
+     - eb1a:e360, eb1a:e361
diff --git a/Documentation/admin-guide/media/dvb-usb-digitv-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-digitv-cardlist.rst
new file mode 100644
index 000000000..2b4d8325e
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-digitv-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-digitv cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Nebula Electronics uDigiTV DVB-T USB2.0)
+     - 0547:0201
diff --git a/Documentation/admin-guide/media/dvb-usb-dtt200u-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dtt200u-cardlist.rst
new file mode 100644
index 000000000..b4150a7bf
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dtt200u-cardlist.rst
@@ -0,0 +1,22 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dtt200u cards list
+==========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - WideView WT-220U PenType Receiver (Miglia)
+     - 18f3:0220
+   * - WideView WT-220U PenType Receiver (Typhoon/Freecom)
+     - 14aa:0222, 14aa:0220, 14aa:0221, 14aa:0225, 14aa:0226
+   * - WideView WT-220U PenType Receiver (based on ZL353)
+     - 14aa:022a, 14aa:022b
+   * - WideView/Yuan/Yakumo/Hama/Typhoon DVB-T USB2.0 (WT-200U)
+     - 14aa:0201, 14aa:0301
diff --git a/Documentation/admin-guide/media/dvb-usb-dtv5100-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dtv5100-cardlist.rst
new file mode 100644
index 000000000..91d6e35e6
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dtv5100-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dtv5100 cards list
+==========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - AME DTV-5100 USB2.0 DVB-T
+     - 0x06be:0xa232
diff --git a/Documentation/admin-guide/media/dvb-usb-dvbsky-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dvbsky-cardlist.rst
new file mode 100644
index 000000000..9f7b619f3
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dvbsky-cardlist.rst
@@ -0,0 +1,42 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dvbsky cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - DVBSky S960/S860
+     - 0572:6831
+   * - DVBSky S960CI
+     - 0572:960c
+   * - DVBSky T330
+     - 0572:0320
+   * - DVBSky T680CI
+     - 0572:680c
+   * - MyGica Mini DVB-(T/T2/C) USB Stick T230
+     - 0572:c688
+   * - MyGica Mini DVB-(T/T2/C) USB Stick T230C
+     - 0572:c689
+   * - MyGica Mini DVB-(T/T2/C) USB Stick T230C Lite
+     - 0572:c699
+   * - MyGica Mini DVB-(T/T2/C) USB Stick T230C v2
+     - 0572:c68a
+   * - TechnoTrend TT-connect CT2-4650 CI
+     - 0b48:3012
+   * - TechnoTrend TT-connect CT2-4650 CI v1.1
+     - 0b48:3015
+   * - TechnoTrend TT-connect S2-4650 CI
+     - 0b48:3017
+   * - TechnoTrend TVStick CT2-4400
+     - 0b48:3014
+   * - Terratec Cinergy S2 Rev.4
+     - 0ccd:0105
+   * - Terratec H7 Rev.4
+     - 0ccd:10a5
diff --git a/Documentation/admin-guide/media/dvb-usb-dw2102-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-dw2102-cardlist.rst
new file mode 100644
index 000000000..e39bc8e4b
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-dw2102-cardlist.rst
@@ -0,0 +1,56 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-dw2102 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - DVBWorld DVB-C 3101 USB2.0
+     - 04b4:3101
+   * - DVBWorld DVB-S 2101 USB2.0
+     - 04b4:0x2101
+   * - DVBWorld DVB-S 2102 USB2.0
+     - 04b4:2102
+   * - DVBWorld DW2104 USB2.0
+     - 04b4:2104
+   * - GOTVIEW Satellite HD
+     - 0x1FE1:5456
+   * - Geniatech T220 DVB-T/T2 USB2.0
+     - 0x1f4d:0xD220
+   * - SU3000HD DVB-S USB2.0
+     - 0x1f4d:0x3000
+   * - TeVii S482 (tuner 1)
+     - 0x9022:0xd483
+   * - TeVii S482 (tuner 2)
+     - 0x9022:0xd484
+   * - TeVii S630 USB
+     - 0x9022:d630
+   * - TeVii S650 USB2.0
+     - 0x9022:d650
+   * - TeVii S662
+     - 0x9022:d662
+   * - TechnoTrend TT-connect S2-4600
+     - 0b48:3011
+   * - TerraTec Cinergy S USB
+     - 0ccd:0064
+   * - Terratec Cinergy S2 PCIe Dual Port 1
+     - 153b:1181
+   * - Terratec Cinergy S2 PCIe Dual Port 2
+     - 153b:1182
+   * - Terratec Cinergy S2 USB BOX
+     - 0ccd:0x0105
+   * - Terratec Cinergy S2 USB HD
+     - 0ccd:00a8
+   * - Terratec Cinergy S2 USB HD Rev.2
+     - 0ccd:00b0
+   * - Terratec Cinergy S2 USB HD Rev.3
+     - 0ccd:0102
+   * - X3M TV SPC1400HD PCI
+     - 0x1f4d:0x3100
diff --git a/Documentation/admin-guide/media/dvb-usb-ec168-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-ec168-cardlist.rst
new file mode 100644
index 000000000..a3660dfa5
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-ec168-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-ec168 cards list
+========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - E3C EC168 reference design
+     - 18b4:1689, 18b4:fffa, 18b4:fffb, 18b4:1001, 18b4:1002
diff --git a/Documentation/admin-guide/media/dvb-usb-gl861-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-gl861-cardlist.rst
new file mode 100644
index 000000000..5ec62fe03
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-gl861-cardlist.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-gl861 cards list
+========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - 774 Friio White ISDB-T USB2.0
+     - 7a69:0001
+   * - A-LINK DTU DVB-T USB2.0
+     - 05e3:f170
+   * - MSI Mega Sky 55801 DVB-T USB2.0
+     - 0db0:5581
diff --git a/Documentation/admin-guide/media/dvb-usb-gp8psk-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-gp8psk-cardlist.rst
new file mode 100644
index 000000000..150fa9f78
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-gp8psk-cardlist.rst
@@ -0,0 +1,22 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-gp8psk cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Genpix 8PSK-to-USB2 Rev.1 DVB-S receiver
+     - 09c0:0200, 09c0:0201
+   * - Genpix 8PSK-to-USB2 Rev.2 DVB-S receiver
+     - 09c0:0202
+   * - Genpix SkyWalker-1 DVB-S receiver
+     - 09c0:0203
+   * - Genpix SkyWalker-2 DVB-S receiver
+     - 09c0:0206
diff --git a/Documentation/admin-guide/media/dvb-usb-lmedm04-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-lmedm04-cardlist.rst
new file mode 100644
index 000000000..2050fbf03
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-lmedm04-cardlist.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-lmedm04 cards list
+==========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - DM04_LME2510C_DVB-S
+     - 3344:1120
+   * - DM04_LME2510C_DVB-S RS2000
+     - 3344:22f0
+   * - DM04_LME2510_DVB-S
+     - 3344:1122
diff --git a/Documentation/admin-guide/media/dvb-usb-m920x-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-m920x-cardlist.rst
new file mode 100644
index 000000000..73145940b
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-m920x-cardlist.rst
@@ -0,0 +1,26 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-m920x cards list
+========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - DTV-DVB UDTT7049
+     - 13d3:3219
+   * - Dposh DVB-T USB2.0
+     - 1498:9206, 1498:a090
+   * - LifeView TV Walker Twin DVB-T USB2.0
+     - 10fd:0514, 10fd:0513
+   * - MSI DIGI VOX mini II DVB-T USB2.0
+     - 10fd:1513
+   * - MSI Mega Sky 580 DVB-T USB2.0
+     - 0db0:5580
+   * - Pinnacle PCTV 310e
+     - 13d3:3211
diff --git a/Documentation/admin-guide/media/dvb-usb-mxl111sf-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-mxl111sf-cardlist.rst
new file mode 100644
index 000000000..6974801c4
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-mxl111sf-cardlist.rst
@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-mxl111sf cards list
+===========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - HCW 117xxx
+     - 2040:b702
+   * - HCW 126xxx
+     - 2040:c602, 2040:c60a
+   * - Hauppauge 117xxx ATSC+
+     - 2040:b700, 2040:b703, 2040:b753, 2040:b763, 2040:b757, 2040:b767
+   * - Hauppauge 117xxx DVBT
+     - 2040:b704, 2040:b764
+   * - Hauppauge 126xxx
+     - 2040:c612, 2040:c61a
+   * - Hauppauge 126xxx ATSC
+     - 2040:c601, 2040:c609, 2040:b701
+   * - Hauppauge 126xxx ATSC+
+     - 2040:c600, 2040:c603, 2040:c60b, 2040:c653, 2040:c65b
+   * - Hauppauge 126xxx DVBT
+     - 2040:c604, 2040:c60c
+   * - Hauppauge 138xxx DVBT
+     - 2040:d854, 2040:d864, 2040:d8d4, 2040:d8e4
+   * - Hauppauge Mercury
+     - 2040:d853, 2040:d863, 2040:d8d3, 2040:d8e3, 2040:d8ff
+   * - Hauppauge WinTV-Aero-M
+     - 2040:c613, 2040:c61b
diff --git a/Documentation/admin-guide/media/dvb-usb-nova-t-usb2-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-nova-t-usb2-cardlist.rst
new file mode 100644
index 000000000..e295f912a
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-nova-t-usb2-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-nova-t-usb2 cards list
+==============================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Hauppauge WinTV-NOVA-T usb2
+     - 2040:9300, 2040:9301
diff --git a/Documentation/admin-guide/media/dvb-usb-opera1-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-opera1-cardlist.rst
new file mode 100644
index 000000000..362245f5a
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-opera1-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-opera1 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Opera1 DVB-S USB2.0
+     - 04b4:2830, 695c:3829
diff --git a/Documentation/admin-guide/media/dvb-usb-pctv452e-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-pctv452e-cardlist.rst
new file mode 100644
index 000000000..886d8cc18
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-pctv452e-cardlist.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-pctv452e cards list
+===========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - PCTV HDTV USB
+     - 2304:021f
+   * - Technotrend TT Connect S2-3600
+     - 0b48:3007
+   * - Technotrend TT Connect S2-3650-CI
+     - 0b48:300a
diff --git a/Documentation/admin-guide/media/dvb-usb-rtl28xxu-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-rtl28xxu-cardlist.rst
new file mode 100644
index 000000000..9f4295331
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-rtl28xxu-cardlist.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-rtl28xxu cards list
+===========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - ASUS My Cinema-U3100Mini Plus V2
+     - 1b80:d3a8
+   * - Astrometa DVB-T2
+     - 15f4:0131
+   * - Compro VideoMate U620F
+     - 185b:0620
+   * - Compro VideoMate U650F
+     - 185b:0650
+   * - Crypto ReDi PC 50 A
+     - 1f4d:a803
+   * - Dexatek DK DVB-T Dongle
+     - 1d19:1101
+   * - Dexatek DK mini DVB-T Dongle
+     - 1d19:1102
+   * - DigitalNow Quad DVB-T Receiver
+     - 0413:6680
+   * - Freecom USB2.0 DVB-T
+     - 14aa:0160, 14aa:0161
+   * - G-Tek Electronics Group Lifeview LV5TDLX DVB-T
+     - 1f4d:b803
+   * - GIGABYTE U7300
+     - 1b80:d393
+   * - Genius TVGo DVB-T03
+     - 0458:707f
+   * - GoTView MasterHD 3
+     - 5654:ca42
+   * - Leadtek WinFast DTV Dongle mini
+     - 0413:6a03
+   * - Leadtek WinFast DTV2000DS Plus
+     - 0413:6f12
+   * - Leadtek Winfast DTV Dongle Mini D
+     - 0413:6f0f
+   * - MSI DIGIVOX Micro HD
+     - 1d19:1104
+   * - MaxMedia HU394-T
+     - 1b80:d394
+   * - PROlectrix DV107669
+     - 1f4d:d803
+   * - Peak DVB-T USB
+     - 1b80:d395
+   * - Realtek RTL2831U reference design
+     - 0bda:2831
+   * - Realtek RTL2832U reference design
+     - 0bda:2832, 0bda:2838
+   * - Sveon STV20
+     - 1b80:d39d
+   * - Sveon STV21
+     - 1b80:d3b0
+   * - Sveon STV27
+     - 1b80:d3af
+   * - TURBO-X Pure TV Tuner DTT-2000
+     - 1b80:d3a4
+   * - TerraTec Cinergy T Stick Black
+     - 0ccd:00a9
+   * - TerraTec Cinergy T Stick RC (Rev. 3)
+     - 0ccd:00d3
+   * - TerraTec Cinergy T Stick+
+     - 0ccd:00d7
+   * - TerraTec NOXON DAB Stick
+     - 0ccd:00b3
+   * - TerraTec NOXON DAB Stick (rev 2)
+     - 0ccd:00e0
+   * - TerraTec NOXON DAB Stick (rev 3)
+     - 0ccd:00b4
+   * - Trekstor DVB-T Stick Terres 2.0
+     - 1f4d:C803
diff --git a/Documentation/admin-guide/media/dvb-usb-technisat-usb2-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-technisat-usb2-cardlist.rst
new file mode 100644
index 000000000..30ee92ada
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-technisat-usb2-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-technisat-usb2 cards list
+=================================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Technisat SkyStar USB HD (DVB-S/S2)
+     - 14f7:0500
diff --git a/Documentation/admin-guide/media/dvb-usb-ttusb2-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-ttusb2-cardlist.rst
new file mode 100644
index 000000000..faa78e5f3
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-ttusb2-cardlist.rst
@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-ttusb2 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Pinnacle 400e DVB-S USB2.0
+     - 2304:020f
+   * - Pinnacle 450e DVB-S USB2.0
+     - 2304:0222
+   * - Technotrend TT-connect CT-3650
+     - 0b48:300d
+   * - Technotrend TT-connect S-2400
+     - 0b48:3006
+   * - Technotrend TT-connect S-2400 (8kB EEPROM)
+     - 0b48:3009
diff --git a/Documentation/admin-guide/media/dvb-usb-umt-010-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-umt-010-cardlist.rst
new file mode 100644
index 000000000..ce7ce901b
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-umt-010-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-umt-010 cards list
+==========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Hanftek UMT-010 DVB-T USB2.0
+     - 15f4:0001, 15f4:0015
diff --git a/Documentation/admin-guide/media/dvb-usb-vp702x-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-vp702x-cardlist.rst
new file mode 100644
index 000000000..101442434
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-vp702x-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-vp702x cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - TwinhanDTV StarBox DVB-S USB2.0 (VP7021)
+     - 13d3:3207
diff --git a/Documentation/admin-guide/media/dvb-usb-vp7045-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-vp7045-cardlist.rst
new file mode 100644
index 000000000..2fc8fc4ec
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-vp7045-cardlist.rst
@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-vp7045 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - DigitalNow TinyUSB 2 DVB-t Receiver
+     - 13d3:3223, 13d3:3224
+   * - Twinhan USB2.0 DVB-T receiver (TwinhanDTV Alpha/MagicBox II)
+     - 13d3:3205, 13d3:3206
diff --git a/Documentation/admin-guide/media/dvb-usb-zd1301-cardlist.rst b/Documentation/admin-guide/media/dvb-usb-zd1301-cardlist.rst
new file mode 100644
index 000000000..9ca446184
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb-usb-zd1301-cardlist.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+dvb-usb-zd1301 cards list
+=========================
+
+.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 7 13
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - ZyDAS ZD1301 reference design
+     - 0ace:13a1
diff --git a/Documentation/admin-guide/media/dvb.rst b/Documentation/admin-guide/media/dvb.rst
new file mode 100644
index 000000000..e5258bfa5
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb.rst
@@ -0,0 +1,12 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+Digital TV
+==========
+
+.. toctree::
+
+	dvb_intro
+	ci
+	faq
+	dvb_references
diff --git a/Documentation/admin-guide/media/dvb_intro.rst b/Documentation/admin-guide/media/dvb_intro.rst
new file mode 100644
index 000000000..44eac9b3b
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb_intro.rst
@@ -0,0 +1,616 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================
+Using the Digital TV Framework
+==============================
+
+Introduction
+~~~~~~~~~~~~
+
+One significant difference between Digital TV and Analogue TV that the
+unwary (like myself) should consider is that, although the component
+structure of DVB-T cards are substantially similar to Analogue TV cards,
+they function in substantially different ways.
+
+The purpose of an Analogue TV is to receive and display an Analogue
+Television signal. An Analogue TV signal (otherwise known as composite
+video) is an analogue encoding of a sequence of image frames (25 frames
+per second in Europe) rasterised using an interlacing technique.
+Interlacing takes two fields to represent one frame. Therefore, an
+Analogue TV card for a PC has the following purpose:
+
+* Tune the receiver to receive a broadcast signal
+* demodulate the broadcast signal
+* demultiplex the analogue video signal and analogue audio
+  signal.
+
+  .. note::
+
+     some countries employ a digital audio signal
+     embedded within the modulated composite analogue signal -
+     using NICAM signaling.)
+
+* digitize the analogue video signal and make the resulting datastream
+  available to the data bus.
+
+The digital datastream from an Analogue TV card is generated by
+circuitry on the card and is often presented uncompressed. For a PAL TV
+signal encoded at a resolution of 768x576 24-bit color pixels over 25
+frames per second - a fair amount of data is generated and must be
+processed by the PC before it can be displayed on the video monitor
+screen. Some Analogue TV cards for PCs have onboard MPEG2 encoders which
+permit the raw digital data stream to be presented to the PC in an
+encoded and compressed form - similar to the form that is used in
+Digital TV.
+
+The purpose of a simple budget digital TV card (DVB-T,C or S) is to
+simply:
+
+* Tune the received to receive a broadcast signal. * Extract the encoded
+  digital datastream from the broadcast signal.
+* Make the encoded digital datastream (MPEG2) available to the data bus.
+
+The significant difference between the two is that the tuner on the
+analogue TV card spits out an Analogue signal, whereas the tuner on the
+digital TV card spits out a compressed encoded digital datastream. As
+the signal is already digitised, it is trivial to pass this datastream
+to the PC databus with minimal additional processing and then extract
+the digital video and audio datastreams passing them to the appropriate
+software or hardware for decoding and viewing.
+
+Getting the card going
+~~~~~~~~~~~~~~~~~~~~~~
+
+The Device Driver API for DVB under Linux will the following
+device nodes via the devfs filesystem:
+
+* /dev/dvb/adapter0/demux0
+* /dev/dvb/adapter0/dvr0
+* /dev/dvb/adapter0/frontend0
+
+The ``/dev/dvb/adapter0/dvr0`` device node is used to read the MPEG2
+Data Stream and the ``/dev/dvb/adapter0/frontend0`` device node is used
+to tune the frontend tuner module. The ``/dev/dvb/adapter0/demux0`` is
+used to control what programs will be received.
+
+Depending on the card's feature set, the Device Driver API could also
+expose other device nodes:
+
+* /dev/dvb/adapter0/ca0
+* /dev/dvb/adapter0/audio0
+* /dev/dvb/adapter0/net0
+* /dev/dvb/adapter0/osd0
+* /dev/dvb/adapter0/video0
+
+The ``/dev/dvb/adapter0/ca0`` is used to decode encrypted channels. The
+other device nodes are found only on devices that use the av7110
+driver, with is now obsoleted, together with the extra API whose such
+devices use.
+
+Receiving a digital TV channel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section attempts to explain how it works and how this affects the
+configuration of a Digital TV card.
+
+On this example, we're considering tuning into DVB-T channels in
+Australia, at the Melbourne region.
+
+The frequencies broadcast by Mount Dandenong transmitters are,
+currently:
+
+Table 1. Transponder Frequencies Mount Dandenong, Vic, Aus.
+
+===========	===========
+Broadcaster	Frequency
+===========	===========
+Seven		177.500 Mhz
+SBS		184.500 Mhz
+Nine		191.625 Mhz
+Ten		219.500 Mhz
+ABC		226.500 Mhz
+Channel 31	557.625 Mhz
+===========	===========
+
+The digital TV Scan utilities (like dvbv5-scan) have use a set of
+compiled-in defaults for various countries and regions. Those are
+currently provided as a separate package, called dtv-scan-tables. It's
+git tree is located at LinuxTV.org:
+
+    https://git.linuxtv.org/dtv-scan-tables.git/
+
+If none of the tables there suit, you can specify a data file on the
+command line which contains the transponder frequencies. Here is a
+sample file for the above channel transponders, in the old "channel"
+format::
+
+	# Data file for DVB scan program
+	#
+	# C Frequency SymbolRate FEC QAM
+	# S Frequency Polarisation SymbolRate FEC
+	# T Frequency Bandwidth FEC FEC2 QAM Mode Guard Hier
+
+	T 177500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE
+	T 184500000 7MHz AUTO AUTO QAM64 8k 1/8 NONE
+	T 191625000 7MHz AUTO AUTO QAM64 8k 1/16 NONE
+	T 219500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE
+	T 226500000 7MHz AUTO AUTO QAM64 8k 1/16 NONE
+	T 557625000 7MHz AUTO AUTO QPSK 8k 1/16 NONE
+
+Nowadays, we prefer to use a newer format, with is more verbose and easier
+to understand. With the new format, the "Seven" channel transponder's
+data is represented by::
+
+	[Seven]
+		DELIVERY_SYSTEM = DVBT
+		FREQUENCY = 177500000
+		BANDWIDTH_HZ = 7000000
+		CODE_RATE_HP = AUTO
+		CODE_RATE_LP = AUTO
+		MODULATION = QAM/64
+		TRANSMISSION_MODE = 8K
+		GUARD_INTERVAL = 1/16
+		HIERARCHY = NONE
+		INVERSION = AUTO
+
+For an updated version of the complete table, please see:
+
+    https://git.linuxtv.org/dtv-scan-tables.git/tree/dvb-t/au-Melbourne
+
+When the Digital TV scanning utility runs, it will output a file
+containing the information for all the audio and video programs that
+exists into each channel's transponders which the card's frontend can
+lock onto. (i.e. any whose signal is strong enough at your antenna).
+
+Here's the output of the dvbv5 tools from a channel scan took from
+Melburne::
+
+    [ABC HDTV]
+	    SERVICE_ID = 560
+	    VIDEO_PID = 2307
+	    AUDIO_PID = 0
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [ABC TV Melbourne]
+	    SERVICE_ID = 561
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [ABC TV 2]
+	    SERVICE_ID = 562
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [ABC TV 3]
+	    SERVICE_ID = 563
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [ABC TV 4]
+	    SERVICE_ID = 564
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [ABC DiG Radio]
+	    SERVICE_ID = 566
+	    VIDEO_PID = 0
+	    AUDIO_PID = 2311
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 226500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 3/4
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital]
+	    SERVICE_ID = 1585
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital 1]
+	    SERVICE_ID = 1586
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital 2]
+	    SERVICE_ID = 1587
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital 3]
+	    SERVICE_ID = 1588
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital]
+	    SERVICE_ID = 1589
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital 4]
+	    SERVICE_ID = 1590
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital]
+	    SERVICE_ID = 1591
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN HD]
+	    SERVICE_ID = 1592
+	    VIDEO_PID = 514
+	    AUDIO_PID = 0
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [TEN Digital]
+	    SERVICE_ID = 1593
+	    VIDEO_PID = 512
+	    AUDIO_PID = 650
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 219500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [Nine Digital]
+	    SERVICE_ID = 1072
+	    VIDEO_PID = 513
+	    AUDIO_PID = 660
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 191625000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [Nine Digital HD]
+	    SERVICE_ID = 1073
+	    VIDEO_PID = 512
+	    AUDIO_PID = 0
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 191625000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [Nine Guide]
+	    SERVICE_ID = 1074
+	    VIDEO_PID = 514
+	    AUDIO_PID = 670
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 191625000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 3/4
+	    CODE_RATE_LP = 1/2
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/16
+	    HIERARCHY = NONE
+
+    [7 Digital]
+	    SERVICE_ID = 1328
+	    VIDEO_PID = 769
+	    AUDIO_PID = 770
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [7 Digital 1]
+	    SERVICE_ID = 1329
+	    VIDEO_PID = 769
+	    AUDIO_PID = 770
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [7 Digital 2]
+	    SERVICE_ID = 1330
+	    VIDEO_PID = 769
+	    AUDIO_PID = 770
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [7 Digital 3]
+	    SERVICE_ID = 1331
+	    VIDEO_PID = 769
+	    AUDIO_PID = 770
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [7 HD Digital]
+	    SERVICE_ID = 1332
+	    VIDEO_PID = 833
+	    AUDIO_PID = 834
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [7 Program Guide]
+	    SERVICE_ID = 1334
+	    VIDEO_PID = 865
+	    AUDIO_PID = 866
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 177500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS HD]
+	    SERVICE_ID = 784
+	    VIDEO_PID = 102
+	    AUDIO_PID = 103
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS DIGITAL 1]
+	    SERVICE_ID = 785
+	    VIDEO_PID = 161
+	    AUDIO_PID = 81
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS DIGITAL 2]
+	    SERVICE_ID = 786
+	    VIDEO_PID = 162
+	    AUDIO_PID = 83
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS EPG]
+	    SERVICE_ID = 787
+	    VIDEO_PID = 163
+	    AUDIO_PID = 85
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS RADIO 1]
+	    SERVICE_ID = 798
+	    VIDEO_PID = 0
+	    AUDIO_PID = 201
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
+
+    [SBS RADIO 2]
+	    SERVICE_ID = 799
+	    VIDEO_PID = 0
+	    AUDIO_PID = 202
+	    DELIVERY_SYSTEM = DVBT
+	    FREQUENCY = 536500000
+	    INVERSION = OFF
+	    BANDWIDTH_HZ = 7000000
+	    CODE_RATE_HP = 2/3
+	    CODE_RATE_LP = 2/3
+	    MODULATION = QAM/64
+	    TRANSMISSION_MODE = 8K
+	    GUARD_INTERVAL = 1/8
+	    HIERARCHY = NONE
diff --git a/Documentation/admin-guide/media/dvb_references.rst b/Documentation/admin-guide/media/dvb_references.rst
new file mode 100644
index 000000000..4f0fd4259
--- /dev/null
+++ b/Documentation/admin-guide/media/dvb_references.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+References
+==========
+
+The main development site and GIT repository for Digital TV
+drivers is https://linuxtv.org.
+
+The DVB mailing list linux-dvb is hosted at vger. Please see
+http://vger.kernel.org/vger-lists.html#linux-media for details.
+
+There are also some other old lists hosted at:
+https://linuxtv.org/lists.php. If you're interested on that for historic
+reasons, please check the archive at https://linuxtv.org/pipermail/linux-dvb/.
+
+The media subsystem Wiki is hosted at https://linuxtv.org/wiki/.
+There, you'll find lots of information, from both development and usage
+of media boards. Please check it before asking newbie questions on the
+mailing list or IRC channels.
+
+The API documentation is documented at the Kernel tree. You can find it
+in both html and pdf formats, together with other useful documentation at:
+
+  - https://linuxtv.org/docs.php.
+
+You may also find useful material at https://linuxtv.org/downloads/.
+
+In order to get the needed firmware for some drivers to work, there's
+a script at the kernel tree, at scripts/get_dvb_firmware.
diff --git a/Documentation/admin-guide/media/em28xx-cardlist.rst b/Documentation/admin-guide/media/em28xx-cardlist.rst
new file mode 100644
index 000000000..741aa7f7c
--- /dev/null
+++ b/Documentation/admin-guide/media/em28xx-cardlist.rst
@@ -0,0 +1,452 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+EM28xx cards list
+=================
+
+.. tabularcolumns:: |p{1.4cm}|p{10.0cm}|p{1.9cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 12 3 16
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - Empia Chip
+     - USB IDs
+   * - 0
+     - Unknown EM2800 video grabber
+     - em2800
+     - eb1a:2800
+   * - 1
+     - Unknown EM2750/28xx video grabber
+     - em2820 or em2840
+     - eb1a:2710, eb1a:2820, eb1a:2821, eb1a:2860, eb1a:2861, eb1a:2862, eb1a:2863, eb1a:2870, eb1a:2881, eb1a:2883, eb1a:2868, eb1a:2875
+   * - 2
+     - Terratec Cinergy 250 USB
+     - em2820 or em2840
+     - 0ccd:0036
+   * - 3
+     - Pinnacle PCTV USB 2
+     - em2820 or em2840
+     - 2304:0208
+   * - 4
+     - Hauppauge WinTV USB 2
+     - em2820 or em2840
+     - 2040:4200, 2040:4201
+   * - 5
+     - MSI VOX USB 2.0
+     - em2820 or em2840
+     -
+   * - 6
+     - Terratec Cinergy 200 USB
+     - em2800
+     -
+   * - 7
+     - Leadtek Winfast USB II
+     - em2800
+     - 0413:6023
+   * - 8
+     - Kworld USB2800
+     - em2800
+     -
+   * - 9
+     - Pinnacle Dazzle DVC 90/100/101/107 / Kaiser Baas Video to DVD maker / Kworld DVD Maker 2 / Plextor ConvertX PX-AV100U
+     - em2820 or em2840
+     - 1b80:e302, 1b80:e304, 2304:0207, 2304:021a, 093b:a003
+   * - 10
+     - Hauppauge WinTV HVR 900
+     - em2880
+     - 2040:6500
+   * - 11
+     - Terratec Hybrid XS
+     - em2880
+     -
+   * - 12
+     - Kworld PVR TV 2800 RF
+     - em2820 or em2840
+     -
+   * - 13
+     - Terratec Prodigy XS
+     - em2880
+     -
+   * - 14
+     - SIIG AVTuner-PVR / Pixelview Prolink PlayTV USB 2.0
+     - em2820 or em2840
+     -
+   * - 15
+     - V-Gear PocketTV
+     - em2800
+     -
+   * - 16
+     - Hauppauge WinTV HVR 950
+     - em2883
+     - 2040:6513, 2040:6517, 2040:651b
+   * - 17
+     - Pinnacle PCTV HD Pro Stick
+     - em2880
+     - 2304:0227
+   * - 18
+     - Hauppauge WinTV HVR 900 (R2)
+     - em2880
+     - 2040:6502
+   * - 19
+     - EM2860/SAA711X Reference Design
+     - em2860
+     -
+   * - 20
+     - AMD ATI TV Wonder HD 600
+     - em2880
+     - 0438:b002
+   * - 21
+     - eMPIA Technology, Inc. GrabBeeX+ Video Encoder
+     - em2800
+     - eb1a:2801
+   * - 22
+     - EM2710/EM2750/EM2751 webcam grabber
+     - em2750
+     - eb1a:2750, eb1a:2751
+   * - 23
+     - Huaqi DLCW-130
+     - em2750
+     -
+   * - 24
+     - D-Link DUB-T210 TV Tuner
+     - em2820 or em2840
+     - 2001:f112
+   * - 25
+     - Gadmei UTV310
+     - em2820 or em2840
+     -
+   * - 26
+     - Hercules Smart TV USB 2.0
+     - em2820 or em2840
+     -
+   * - 27
+     - Pinnacle PCTV USB 2 (Philips FM1216ME)
+     - em2820 or em2840
+     -
+   * - 28
+     - Leadtek Winfast USB II Deluxe
+     - em2820 or em2840
+     -
+   * - 29
+     - EM2860/TVP5150 Reference Design
+     - em2860
+     - eb1a:5051
+   * - 30
+     - Videology 20K14XUSB USB2.0
+     - em2820 or em2840
+     -
+   * - 31
+     - Usbgear VD204v9
+     - em2821
+     -
+   * - 32
+     - Supercomp USB 2.0 TV
+     - em2821
+     -
+   * - 33
+     - Elgato Video Capture
+     - em2860
+     - 0fd9:0033
+   * - 34
+     - Terratec Cinergy A Hybrid XS
+     - em2860
+     - 0ccd:004f
+   * - 35
+     - Typhoon DVD Maker
+     - em2860
+     -
+   * - 36
+     - NetGMBH Cam
+     - em2860
+     -
+   * - 37
+     - Gadmei UTV330
+     - em2860
+     - eb1a:50a6
+   * - 38
+     - Yakumo MovieMixer
+     - em2861
+     -
+   * - 39
+     - KWorld PVRTV 300U
+     - em2861
+     - eb1a:e300
+   * - 40
+     - Plextor ConvertX PX-TV100U
+     - em2861
+     - 093b:a005
+   * - 41
+     - Kworld 350 U DVB-T
+     - em2870
+     - eb1a:e350
+   * - 42
+     - Kworld 355 U DVB-T
+     - em2870
+     - eb1a:e355, eb1a:e357, eb1a:e359
+   * - 43
+     - Terratec Cinergy T XS
+     - em2870
+     -
+   * - 44
+     - Terratec Cinergy T XS (MT2060)
+     - em2870
+     - 0ccd:0043
+   * - 45
+     - Pinnacle PCTV DVB-T
+     - em2870
+     -
+   * - 46
+     - Compro, VideoMate U3
+     - em2870
+     - 185b:2870
+   * - 47
+     - KWorld DVB-T 305U
+     - em2880
+     - eb1a:e305
+   * - 48
+     - KWorld DVB-T 310U
+     - em2880
+     -
+   * - 49
+     - MSI DigiVox A/D
+     - em2880
+     - eb1a:e310
+   * - 50
+     - MSI DigiVox A/D II
+     - em2880
+     - eb1a:e320
+   * - 51
+     - Terratec Hybrid XS Secam
+     - em2880
+     - 0ccd:004c
+   * - 52
+     - DNT DA2 Hybrid
+     - em2881
+     -
+   * - 53
+     - Pinnacle Hybrid Pro
+     - em2881
+     -
+   * - 54
+     - Kworld VS-DVB-T 323UR
+     - em2882
+     - eb1a:e323
+   * - 55
+     - Terratec Cinergy Hybrid T USB XS (em2882)
+     - em2882
+     - 0ccd:005e, 0ccd:0042
+   * - 56
+     - Pinnacle Hybrid Pro (330e)
+     - em2882
+     - 2304:0226
+   * - 57
+     - Kworld PlusTV HD Hybrid 330
+     - em2883
+     - eb1a:a316
+   * - 58
+     - Compro VideoMate ForYou/Stereo
+     - em2820 or em2840
+     - 185b:2041
+   * - 59
+     - Pinnacle PCTV HD Mini
+     - em2874
+     - 2304:023f
+   * - 60
+     - Hauppauge WinTV HVR 850
+     - em2883
+     - 2040:651f
+   * - 61
+     - Pixelview PlayTV Box 4 USB 2.0
+     - em2820 or em2840
+     -
+   * - 62
+     - Gadmei TVR200
+     - em2820 or em2840
+     -
+   * - 63
+     - Kaiomy TVnPC U2
+     - em2860
+     - eb1a:e303
+   * - 64
+     - Easy Cap Capture DC-60
+     - em2860
+     - 1b80:e309
+   * - 65
+     - IO-DATA GV-MVP/SZ
+     - em2820 or em2840
+     - 04bb:0515
+   * - 66
+     - Empire dual TV
+     - em2880
+     -
+   * - 67
+     - Terratec Grabby
+     - em2860
+     - 0ccd:0096, 0ccd:10AF
+   * - 68
+     - Terratec AV350
+     - em2860
+     - 0ccd:0084
+   * - 69
+     - KWorld ATSC 315U HDTV TV Box
+     - em2882
+     - eb1a:a313
+   * - 70
+     - Evga inDtube
+     - em2882
+     -
+   * - 71
+     - Silvercrest Webcam 1.3mpix
+     - em2820 or em2840
+     -
+   * - 72
+     - Gadmei UTV330+
+     - em2861
+     -
+   * - 73
+     - Reddo DVB-C USB TV Box
+     - em2870
+     -
+   * - 74
+     - Actionmaster/LinXcel/Digitus VC211A
+     - em2800
+     -
+   * - 75
+     - Dikom DK300
+     - em2882
+     -
+   * - 76
+     - KWorld PlusTV 340U or UB435-Q (ATSC)
+     - em2870
+     - 1b80:a340
+   * - 77
+     - EM2874 Leadership ISDBT
+     - em2874
+     -
+   * - 78
+     - PCTV nanoStick T2 290e
+     - em28174
+     - 2013:024f
+   * - 79
+     - Terratec Cinergy H5
+     - em2884
+     - eb1a:2885, 0ccd:10a2, 0ccd:10ad, 0ccd:10b6
+   * - 80
+     - PCTV DVB-S2 Stick (460e)
+     - em28174
+     - 2013:024c
+   * - 81
+     - Hauppauge WinTV HVR 930C
+     - em2884
+     - 2040:1605
+   * - 82
+     - Terratec Cinergy HTC Stick
+     - em2884
+     - 0ccd:00b2
+   * - 83
+     - Honestech Vidbox NW03
+     - em2860
+     - eb1a:5006
+   * - 84
+     - MaxMedia UB425-TC
+     - em2874
+     - 1b80:e425
+   * - 85
+     - PCTV QuatroStick (510e)
+     - em2884
+     - 2304:0242
+   * - 86
+     - PCTV QuatroStick nano (520e)
+     - em2884
+     - 2013:0251
+   * - 87
+     - Terratec Cinergy HTC USB XS
+     - em2884
+     - 0ccd:008e, 0ccd:00ac
+   * - 88
+     - C3 Tech Digital Duo HDTV/SDTV USB
+     - em2884
+     - 1b80:e755
+   * - 89
+     - Delock 61959
+     - em2874
+     - 1b80:e1cc
+   * - 90
+     - KWorld USB ATSC TV Stick UB435-Q V2
+     - em2874
+     - 1b80:e346
+   * - 91
+     - SpeedLink Vicious And Devine Laplace webcam
+     - em2765
+     - 1ae7:9003, 1ae7:9004
+   * - 92
+     - PCTV DVB-S2 Stick (461e)
+     - em28178
+     - 2013:0258
+   * - 93
+     - KWorld USB ATSC TV Stick UB435-Q V3
+     - em2874
+     - 1b80:e34c
+   * - 94
+     - PCTV tripleStick (292e)
+     - em28178
+     - 2013:025f, 2013:0264, 2040:0264, 2040:8264, 2040:8268
+   * - 95
+     - Leadtek VC100
+     - em2861
+     - 0413:6f07
+   * - 96
+     - Terratec Cinergy T2 Stick HD
+     - em28178
+     - eb1a:8179
+   * - 97
+     - Elgato EyeTV Hybrid 2008 INT
+     - em2884
+     - 0fd9:0018
+   * - 98
+     - PLEX PX-BCUD
+     - em28178
+     - 3275:0085
+   * - 99
+     - Hauppauge WinTV-dualHD DVB
+     - em28174
+     - 2040:0265, 2040:8265
+   * - 100
+     - Hauppauge WinTV-dualHD 01595 ATSC/QAM
+     - em28174
+     - 2040:026d, 2040:826d
+   * - 101
+     - Terratec Cinergy H6 rev. 2
+     - em2884
+     - 0ccd:10b2
+   * - 102
+     - :ZOLID HYBRID TV STICK
+     - em2882
+     -
+   * - 103
+     - Magix USB Videowandler-2
+     - em2861
+     - 1b80:e349
+   * - 104
+     - PCTV DVB-S2 Stick (461e v2)
+     - em28178
+     - 2013:0461, 2013:0259
+   * - 105
+     - MyGica iGrabber
+     - em2860
+     - 1f4d:1abe
+   * - 106
+     - Hauppauge USB QuadHD ATSC
+     - em28274
+     - 2040:846d
+   * - 107
+     - MyGica UTV3 Analog USB2.0 TV Box
+     - em2860
+     - eb1a:2860
+   * - 113
+     - StarTech SVID2USB232
+     - em28281
+     - eb1a:8286
diff --git a/Documentation/admin-guide/media/faq.rst b/Documentation/admin-guide/media/faq.rst
new file mode 100644
index 000000000..b63548b6f
--- /dev/null
+++ b/Documentation/admin-guide/media/faq.rst
@@ -0,0 +1,216 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+FAQ
+===
+
+.. note::
+
+     1. With Digital TV, a single physical channel may have different
+	contents inside it. The specs call each one as a *service*.
+	This is what a TV user would call "channel". So, in order to
+	avoid confusion, we're calling *transponders* as the physical
+	channel on this FAQ, and *services* for the logical channel.
+     2. The LinuxTV community maintains some Wiki pages with contain
+        a lot of information related to the media subsystem. If you
+        don't find an answer for your needs here, it is likely that
+        you'll be able to get something useful there. It is hosted
+	at:
+
+	https://www.linuxtv.org/wiki/
+
+Some very frequently asked questions about Linux Digital TV support
+
+1. The signal seems to die a few seconds after tuning.
+
+	It's not a bug, it's a feature. Because the frontends have
+	significant power requirements (and hence get very hot), they
+	are powered down if they are unused (i.e. if the frontend device
+	is closed). The ``dvb-core`` module parameter ``dvb_shutdown_timeout``
+	allow you to change the timeout (default 5 seconds). Setting the
+	timeout to 0 disables the timeout feature.
+
+2. How can I watch TV?
+
+	Together with the Linux Kernel, the Digital TV developers support
+	some simple utilities which are mainly intended for testing
+	and to demonstrate how the DVB API works. This is called DVB v5
+	tools and are grouped together with the ``v4l-utils`` git repository:
+
+	    https://git.linuxtv.org/v4l-utils.git/
+
+	You can find more information at the LinuxTV wiki:
+
+	    https://www.linuxtv.org/wiki/index.php/DVBv5_Tools
+
+	The first step is to get a list of services that are transmitted.
+
+	This is done by using several existing tools. You can use
+	for example the ``dvbv5-scan`` tool. You can find more information
+	about it at:
+
+	    https://www.linuxtv.org/wiki/index.php/Dvbv5-scan
+
+	There are some other applications like ``w_scan`` [#]_ that do a
+	blind scan, trying hard to find all possible channels, but
+	those consumes a large amount of time to run.
+
+	.. [#] https://www.linuxtv.org/wiki/index.php/W_scan
+
+	Also, some applications like ``kaffeine`` have their own code
+	to scan for services. So, you don't need to use an external
+	application to obtain such list.
+
+	Most of such tools need a file containing a list of channel
+	transponders available on your area. So, LinuxTV developers
+	maintain tables of Digital TV channel transponders, receiving
+	patches from the community to keep them updated.
+
+	This list is hosted at:
+
+	    https://git.linuxtv.org/dtv-scan-tables.git
+
+	And packaged on several distributions.
+
+	Kaffeine has some blind scan support for some terrestrial standards.
+	It also relies on DTV scan tables, although it contains a copy
+	of it internally (and, if requested by the user, it will download
+	newer versions of it).
+
+	If you are lucky you can just use one of the supplied channel
+	transponders. If not, you may need to seek for such info at
+	the Internet and create a new file. There are several sites with
+	contains physical channel lists. For cable and satellite, usually
+	knowing how to tune into a single channel is enough for the
+	scanning tool to identify the other channels. On some places,
+	this could also work for terrestrial transmissions.
+
+	Once you have a transponders list, you need to generate a services
+	list with a tool like ``dvbv5-scan``.
+
+	Almost all modern Digital TV cards don't have built-in hardware
+	MPEG-decoders. So, it is up to the application to get a MPEG-TS
+	stream provided by the board, split it into audio, video and other
+	data and decode.
+
+3. Which Digital TV applications exist?
+
+	Several media player applications are capable of tuning into
+	digital TV channels, including Kaffeine, Vlc, mplayer and MythTV.
+
+	Kaffeine aims to be very user-friendly, and it is maintained
+	by one of the Kernel driver developers.
+
+	A comprehensive list of those and other apps can be found at:
+
+	    https://www.linuxtv.org/wiki/index.php/TV_Related_Software
+
+	Some of the most popular ones are linked below:
+
+	https://kde.org/applications/multimedia/org.kde.kaffeine
+		KDE media player, focused on Digital TV support
+
+	https://www.linuxtv.org/vdrwiki/index.php/Main_Page
+		Klaus Schmidinger's Video Disk Recorder
+
+	https://linuxtv.org/downloads and https://git.linuxtv.org/
+		Digital TV and other media-related applications and
+		Kernel drivers. The ``v4l-utils`` package there contains
+		several swiss knife tools for using with Digital TV.
+
+	http://sourceforge.net/projects/dvbtools/
+		Dave Chapman's dvbtools package, including
+		dvbstream and dvbtune
+
+	http://www.dbox2.info/
+		LinuxDVB on the dBox2
+
+	http://www.tuxbox.org/
+		the TuxBox CVS many interesting DVB applications and the dBox2
+		DVB source
+
+	http://www.nenie.org/misc/mpsys/
+		MPSYS: a MPEG2 system library and tools
+
+	https://www.videolan.org/vlc/index.pt.html
+		Vlc
+
+	http://mplayerhq.hu/
+		MPlayer
+
+	http://xine.sourceforge.net/ and http://xinehq.de/
+		Xine
+
+	http://www.mythtv.org/
+		MythTV - analog TV and digital TV PVR
+
+	http://dvbsnoop.sourceforge.net/
+		DVB sniffer program to monitor, analyze, debug, dump
+		or view dvb/mpeg/dsm-cc/mhp stream information (TS,
+		PES, SECTION)
+
+4. Can't get a signal tuned correctly
+
+	That could be due to a lot of problems. On my personal experience,
+	usually TV cards need stronger signals than TV sets, and are more
+	sensitive to noise. So, perhaps you just need a better antenna or
+	cabling. Yet, it could also be some hardware or driver issue.
+
+	For example, if you are using a Technotrend/Hauppauge DVB-C card
+	*without* analog module, you might have to use module parameter
+	adac=-1 (dvb-ttpci.o).
+
+	Please see the FAQ page at linuxtv.org, as it could contain some
+	valuable information:
+
+	    https://www.linuxtv.org/wiki/index.php/FAQ_%26_Troubleshooting
+
+	If that doesn't work, check at the linux-media ML archives, to
+	see if someone else had a similar problem with your hardware
+	and/or digital TV service provider:
+
+	    https://lore.kernel.org/linux-media/
+
+	If none of this works, you can try sending an e-mail to the
+	linux-media ML and see if someone else could shed some light.
+	The e-mail is linux-media AT vger.kernel.org.
+
+5. The dvb_net device doesn't give me any packets at all
+
+	Run ``tcpdump`` on the ``dvb0_0`` interface. This sets the interface
+	into promiscuous mode so it accepts any packets from the PID
+	you have configured with the ``dvbnet`` utility. Check if there
+	are any packets with the IP addr and MAC addr you have
+	configured with ``ifconfig`` or with ``ip addr``.
+
+	If ``tcpdump`` doesn't give you any output, check the statistics
+	which ``ifconfig`` or ``netstat -ni`` outputs. (Note: If the MAC
+	address is wrong, ``dvb_net`` won't get any input; thus you have to
+	run ``tcpdump`` before checking the statistics.) If there are no
+	packets at all then maybe the PID is wrong. If there are error packets,
+	then either the PID is wrong or the stream does not conform to
+	the MPE standard (EN 301 192, http://www.etsi.org/). You can
+	use e.g. ``dvbsnoop`` for debugging.
+
+6. The ``dvb_net`` device doesn't give me any multicast packets
+
+	Check your routes if they include the multicast address range.
+	Additionally make sure that "source validation by reversed path
+	lookup" is disabled::
+
+	  $ "echo 0 > /proc/sys/net/ipv4/conf/dvb0/rp_filter"
+
+7. What are all those modules that need to be loaded?
+
+	In order to make it more flexible and support different hardware
+	combinations, the media subsystem is written on a modular way.
+
+	So, besides the Digital TV hardware module for the main chipset,
+	it also needs to load a frontend driver, plus the Digital TV
+	core. If the board also has remote controller, it will also
+	need the remote controller core and the remote controller tables.
+	The same happens if the board has support for analog TV: the
+	core support for video4linux need to be loaded.
+
+	The actual module names are Linux-kernel version specific, as,
+	from time to time, things change, in order to make the media
+	support more flexible.
diff --git a/Documentation/admin-guide/media/fimc.rst b/Documentation/admin-guide/media/fimc.rst
new file mode 100644
index 000000000..267ef52fe
--- /dev/null
+++ b/Documentation/admin-guide/media/fimc.rst
@@ -0,0 +1,153 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+The Samsung S5P/Exynos4 FIMC driver
+===================================
+
+Copyright |copy| 2012 - 2013 Samsung Electronics Co., Ltd.
+
+The FIMC (Fully Interactive Mobile Camera) device available in Samsung
+SoC Application Processors is an integrated camera host interface, color
+space converter, image resizer and rotator.  It's also capable of capturing
+data from LCD controller (FIMD) through the SoC internal writeback data
+path.  There are multiple FIMC instances in the SoCs (up to 4), having
+slightly different capabilities, like pixel alignment constraints, rotator
+availability, LCD writeback support, etc. The driver is located at
+drivers/media/platform/samsung/exynos4-is directory.
+
+Supported SoCs
+--------------
+
+S5PC100 (mem-to-mem only), S5PV210, Exynos4210
+
+Supported features
+------------------
+
+- camera parallel interface capture (ITU-R.BT601/565);
+- camera serial interface capture (MIPI-CSI2);
+- memory-to-memory processing (color space conversion, scaling, mirror
+  and rotation);
+- dynamic pipeline re-configuration at runtime (re-attachment of any FIMC
+  instance to any parallel video input or any MIPI-CSI front-end);
+- runtime PM and system wide suspend/resume
+
+Not currently supported
+-----------------------
+
+- LCD writeback input
+- per frame clock gating (mem-to-mem)
+
+User space interfaces
+---------------------
+
+Media device interface
+~~~~~~~~~~~~~~~~~~~~~~
+
+The driver supports Media Controller API as defined at :ref:`media_controller`.
+The media device driver name is "Samsung S5P FIMC".
+
+The purpose of this interface is to allow changing assignment of FIMC instances
+to the SoC peripheral camera input at runtime and optionally to control internal
+connections of the MIPI-CSIS device(s) to the FIMC entities.
+
+The media device interface allows to configure the SoC for capturing image
+data from the sensor through more than one FIMC instance (e.g. for simultaneous
+viewfinder and still capture setup).
+
+Reconfiguration is done by enabling/disabling media links created by the driver
+during initialization. The internal device topology can be easily discovered
+through media entity and links enumeration.
+
+Memory-to-memory video node
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+V4L2 memory-to-memory interface at /dev/video? device node.  This is standalone
+video device, it has no media pads. However please note the mem-to-mem and
+capture video node operation on same FIMC instance is not allowed.  The driver
+detects such cases but the applications should prevent them to avoid an
+undefined behaviour.
+
+Capture video node
+~~~~~~~~~~~~~~~~~~
+
+The driver supports V4L2 Video Capture Interface as defined at
+:ref:`devices`.
+
+At the capture and mem-to-mem video nodes only the multi-planar API is
+supported. For more details see: :ref:`planar-apis`.
+
+Camera capture subdevs
+~~~~~~~~~~~~~~~~~~~~~~
+
+Each FIMC instance exports a sub-device node (/dev/v4l-subdev?), a sub-device
+node is also created per each available and enabled at the platform level
+MIPI-CSI receiver device (currently up to two).
+
+sysfs
+~~~~~
+
+In order to enable more precise camera pipeline control through the sub-device
+API the driver creates a sysfs entry associated with "s5p-fimc-md" platform
+device. The entry path is: /sys/platform/devices/s5p-fimc-md/subdev_conf_mode.
+
+In typical use case there could be a following capture pipeline configuration:
+sensor subdev -> mipi-csi subdev -> fimc subdev -> video node
+
+When we configure these devices through sub-device API at user space, the
+configuration flow must be from left to right, and the video node is
+configured as last one.
+
+When we don't use sub-device user space API the whole configuration of all
+devices belonging to the pipeline is done at the video node driver.
+The sysfs entry allows to instruct the capture node driver not to configure
+the sub-devices (format, crop), to avoid resetting the subdevs' configuration
+when the last configuration steps at the video node is performed.
+
+For full sub-device control support (subdevs configured at user space before
+starting streaming):
+
+.. code-block:: none
+
+	# echo "sub-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode
+
+For V4L2 video node control only (subdevs configured internally by the host
+driver):
+
+.. code-block:: none
+
+	# echo "vid-dev" > /sys/platform/devices/s5p-fimc-md/subdev_conf_mode
+
+This is a default option.
+
+5. Device mapping to video and subdev device nodes
+--------------------------------------------------
+
+There are associated two video device nodes with each device instance in
+hardware - video capture and mem-to-mem and additionally a subdev node for
+more precise FIMC capture subsystem control. In addition a separate v4l2
+sub-device node is created per each MIPI-CSIS device.
+
+How to find out which /dev/video? or /dev/v4l-subdev? is assigned to which
+device?
+
+You can either grep through the kernel log to find relevant information, i.e.
+
+.. code-block:: none
+
+	# dmesg | grep -i fimc
+
+(note that udev, if present, might still have rearranged the video nodes),
+
+or retrieve the information from /dev/media? with help of the media-ctl tool:
+
+.. code-block:: none
+
+	# media-ctl -p
+
+7. Build
+--------
+
+If the driver is built as a loadable kernel module (CONFIG_VIDEO_SAMSUNG_S5P_FIMC=m)
+two modules are created (in addition to the core v4l2 modules): s5p-fimc.ko and
+optional s5p-csis.ko (MIPI-CSI receiver subdev).
diff --git a/Documentation/admin-guide/media/frontend-cardlist.rst b/Documentation/admin-guide/media/frontend-cardlist.rst
new file mode 100644
index 000000000..ba5b7c69a
--- /dev/null
+++ b/Documentation/admin-guide/media/frontend-cardlist.rst
@@ -0,0 +1,226 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+Frontend drivers
+================
+
+.. note::
+
+  #) There is no guarantee that every frontend driver works
+     out of the box with every card, because of different wiring.
+
+  #) The demodulator chips can be used with a variety of
+     tuner/PLL chips, and not all combinations are supported. Often
+     the demodulator and tuner/PLL chip are inside a metal box for
+     shielding, and the whole metal box has its own part number.
+
+
+Common Interface (EN50221) controller drivers
+=============================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+cxd2099         Sony CXD2099AR Common Interface driver
+sp2             CIMaX SP2
+==============  =========================================================
+
+ATSC (North American/Korean Terrestrial/Cable DTV) frontends
+============================================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+au8522_dig      Auvitek AU8522 based DTV demod
+au8522_decoder  Auvitek AU8522 based ATV demod
+bcm3510         Broadcom BCM3510
+lg2160          LG Electronics LG216x based
+lgdt3305        LG Electronics LGDT3304 and LGDT3305 based
+lgdt3306a       LG Electronics LGDT3306A based
+lgdt330x        LG Electronics LGDT3302/LGDT3303 based
+nxt200x         NxtWave Communications NXT2002/NXT2004 based
+or51132         Oren OR51132 based
+or51211         Oren OR51211 based
+s5h1409         Samsung S5H1409 based
+s5h1411         Samsung S5H1411 based
+==============  =========================================================
+
+DVB-C (cable) frontends
+=======================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+stv0297         ST STV0297 based
+tda10021        Philips TDA10021 based
+tda10023        Philips TDA10023 based
+ves1820         VLSI VES1820 based
+==============  =========================================================
+
+DVB-S (satellite) frontends
+===========================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+cx24110         Conexant CX24110 based
+cx24116         Conexant CX24116 based
+cx24117         Conexant CX24117 based
+cx24120         Conexant CX24120 based
+cx24123         Conexant CX24123 based
+ds3000          Montage Technology DS3000 based
+mb86a16         Fujitsu MB86A16 based
+mt312           Zarlink VP310/MT312/ZL10313 based
+s5h1420         Samsung S5H1420 based
+si21xx          Silicon Labs SI21XX based
+stb6000         ST STB6000 silicon tuner
+stv0288         ST STV0288 based
+stv0299         ST STV0299 based
+stv0900         ST STV0900 based
+stv6110         ST STV6110 silicon tuner
+tda10071        NXP TDA10071
+tda10086        Philips TDA10086 based
+tda8083         Philips TDA8083 based
+tda8261         Philips TDA8261 based
+tda826x         Philips TDA826X silicon tuner
+ts2020          Montage Technology TS2020 based tuners
+tua6100         Infineon TUA6100 PLL
+cx24113         Conexant CX24113/CX24128 tuner for DVB-S/DSS
+itd1000         Integrant ITD1000 Zero IF tuner for DVB-S/DSS
+ves1x93         VLSI VES1893 or VES1993 based
+zl10036         Zarlink ZL10036 silicon tuner
+zl10039         Zarlink ZL10039 silicon tuner
+==============  =========================================================
+
+DVB-T (terrestrial) frontends
+=============================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+af9013          Afatech AF9013 demodulator
+cx22700         Conexant CX22700 based
+cx22702         Conexant cx22702 demodulator (OFDM)
+cxd2820r        Sony CXD2820R
+cxd2841er       Sony CXD2841ER
+cxd2880         Sony CXD2880 DVB-T2/T tuner + demodulator
+dib3000mb       DiBcom 3000M-B
+dib3000mc       DiBcom 3000P/M-C
+dib7000m        DiBcom 7000MA/MB/PA/PB/MC
+dib7000p        DiBcom 7000PC
+dib9000         DiBcom 9000
+drxd            Micronas DRXD driver
+ec100           E3C EC100
+l64781          LSI L64781
+mt352           Zarlink MT352 based
+nxt6000         NxtWave Communications NXT6000 based
+rtl2830         Realtek RTL2830 DVB-T
+rtl2832         Realtek RTL2832 DVB-T
+rtl2832_sdr     Realtek RTL2832 SDR
+s5h1432         Samsung s5h1432 demodulator (OFDM)
+si2168          Silicon Labs Si2168
+sp8870          Spase sp8870 based
+sp887x          Spase sp887x based
+stv0367         ST STV0367 based
+tda10048        Philips TDA10048HN based
+tda1004x        Philips TDA10045H/TDA10046H based
+zd1301_demod    ZyDAS ZD1301
+zl10353         Zarlink ZL10353 based
+==============  =========================================================
+
+Digital terrestrial only tuners/PLL
+===================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+dvb-pll         Generic I2C PLL based tuners
+dib0070         DiBcom DiB0070 silicon base-band tuner
+dib0090         DiBcom DiB0090 silicon base-band tuner
+==============  =========================================================
+
+ISDB-S (satellite) & ISDB-T (terrestrial) frontends
+===================================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+mn88443x        Socionext MN88443x
+tc90522         Toshiba TC90522
+==============  =========================================================
+
+ISDB-T (terrestrial) frontends
+==============================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+dib8000         DiBcom 8000MB/MC
+mb86a20s        Fujitsu mb86a20s
+s921            Sharp S921 frontend
+==============  =========================================================
+
+Multistandard (cable + terrestrial) frontends
+=============================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+drxk            Micronas DRXK based
+mn88472         Panasonic MN88472
+mn88473         Panasonic MN88473
+si2165          Silicon Labs si2165 based
+tda18271c2dd    NXP TDA18271C2 silicon tuner
+==============  =========================================================
+
+Multistandard (satellite) frontends
+===================================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+m88ds3103       Montage Technology M88DS3103
+mxl5xx          MaxLinear MxL5xx based tuner-demodulators
+stb0899         STB0899 based
+stb6100         STB6100 based tuners
+stv090x         STV0900/STV0903(A/B) based
+stv0910         STV0910 based
+stv6110x        STV6110/(A) based tuners
+stv6111         STV6111 based tuners
+==============  =========================================================
+
+SEC control devices for DVB-S
+=============================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+a8293           Allegro A8293
+af9033          Afatech AF9033 DVB-T demodulator
+ascot2e         Sony Ascot2E tuner
+atbm8830        AltoBeam ATBM8830/8831 DMB-TH demodulator
+drx39xyj        Micronas DRX-J demodulator
+helene          Sony HELENE Sat/Ter tuner (CXD2858ER)
+horus3a         Sony Horus3A tuner
+isl6405         ISL6405 SEC controller
+isl6421         ISL6421 SEC controller
+isl6423         ISL6423 SEC controller
+ix2505v         Sharp IX2505V silicon tuner
+lgs8gl5         Silicon Legend LGS-8GL5 demodulator (OFDM)
+lgs8gxx         Legend Silicon LGS8913/LGS8GL5/LGS8GXX DMB-TH demodulator
+lnbh25          LNBH25 SEC controller
+lnbh29          LNBH29 SEC controller
+lnbp21          LNBP21/LNBH24 SEC controllers
+lnbp22          LNBP22 SEC controllers
+m88rs2000       M88RS2000 DVB-S demodulator and tuner
+tda665x         TDA665x tuner
+==============  =========================================================
+
+Tools to develop new frontends
+==============================
+
+==============  =========================================================
+Driver          Name
+==============  =========================================================
+dvb_dummy_fe    Dummy frontend driver
+==============  =========================================================
diff --git a/Documentation/admin-guide/media/gspca-cardlist.rst b/Documentation/admin-guide/media/gspca-cardlist.rst
new file mode 100644
index 000000000..e3404d158
--- /dev/null
+++ b/Documentation/admin-guide/media/gspca-cardlist.rst
@@ -0,0 +1,451 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The gspca cards list
+====================
+
+The modules for the gspca webcam drivers are:
+
+- gspca_main: main driver
+- gspca\_\ *driver*: subdriver module with *driver* as follows
+
+=========	=========	===================================================================
+*driver*	vend:prod	Device
+=========	=========	===================================================================
+spca501         0000:0000	MystFromOri Unknown Camera
+spca508         0130:0130	Clone Digital Webcam 11043
+se401           03e8:0004	Endpoints/AoxSE401
+zc3xx           03f0:1b07	HP Premium Starter Cam
+m5602           0402:5602	ALi Video Camera Controller
+spca501         040a:0002	Kodak DVC-325
+spca500         040a:0300	Kodak EZ200
+zc3xx           041e:041e	Creative WebCam Live!
+ov519           041e:4003	Video Blaster WebCam Go Plus
+stv0680         041e:4007	Go Mini
+spca500         041e:400a	Creative PC-CAM 300
+sunplus         041e:400b	Creative PC-CAM 600
+sunplus         041e:4012	PC-Cam350
+sunplus         041e:4013	Creative Pccam750
+zc3xx           041e:4017	Creative Webcam Mobile PD1090
+spca508         041e:4018	Creative Webcam Vista (PD1100)
+spca561         041e:401a	Creative Webcam Vista (PD1100)
+zc3xx           041e:401c	Creative NX
+spca505         041e:401d	Creative Webcam NX ULTRA
+zc3xx           041e:401e	Creative Nx Pro
+zc3xx           041e:401f	Creative Webcam Notebook PD1171
+zc3xx           041e:4022	Webcam NX Pro
+pac207          041e:4028	Creative Webcam Vista Plus
+zc3xx           041e:4029	Creative WebCam Vista Pro
+zc3xx           041e:4034	Creative Instant P0620
+zc3xx           041e:4035	Creative Instant P0620D
+zc3xx           041e:4036	Creative Live !
+sq930x          041e:4038	Creative Joy-IT
+zc3xx           041e:403a	Creative Nx Pro 2
+spca561         041e:403b	Creative Webcam Vista (VF0010)
+sq930x          041e:403c	Creative Live! Ultra
+sq930x          041e:403d	Creative Live! Ultra for Notebooks
+sq930x          041e:4041	Creative Live! Motion
+zc3xx           041e:4051	Creative Live!Cam Notebook Pro (VF0250)
+ov519           041e:4052	Creative Live! VISTA IM
+zc3xx           041e:4053	Creative Live!Cam Video IM
+vc032x          041e:405b	Creative Live! Cam Notebook Ultra (VC0130)
+ov519           041e:405f	Creative Live! VISTA VF0330
+ov519           041e:4060	Creative Live! VISTA VF0350
+ov519           041e:4061	Creative Live! VISTA VF0400
+ov519           041e:4064	Creative Live! VISTA VF0420
+ov519           041e:4067	Creative Live! Cam Video IM (VF0350)
+ov519           041e:4068	Creative Live! VISTA VF0470
+sn9c2028        0458:7003	GeniusVideocam Live v2
+spca561         0458:7004	Genius VideoCAM Express V2
+sn9c2028        0458:7005	Genius Smart 300, version 2
+sunplus         0458:7006	Genius Dsc 1.3 Smart
+zc3xx           0458:7007	Genius VideoCam V2
+zc3xx           0458:700c	Genius VideoCam V3
+zc3xx           0458:700f	Genius VideoCam Web V2
+sonixj          0458:7025	Genius Eye 311Q
+sn9c20x         0458:7029	Genius Look 320s
+sonixj          0458:702e	Genius Slim 310 NB
+sn9c20x         0458:7045	Genius Look 1320 V2
+sn9c20x         0458:704a	Genius Slim 1320
+sn9c20x         0458:704c	Genius i-Look 1321
+sn9c20x         045e:00f4	LifeCam VX-6000 (SN9C20x + OV9650)
+sonixj          045e:00f5	MicroSoft VX3000
+sonixj          045e:00f7	MicroSoft VX1000
+ov519           045e:028c	Micro$oft xbox cam
+kinect          045e:02ae	Xbox NUI Camera
+kinect          045e:02bf	Kinect for Windows NUI Camera
+spca561         0461:0815	Micro Innovations IC200 Webcam
+sunplus         0461:0821	Fujifilm MV-1
+zc3xx           0461:0a00	MicroInnovation WebCam320
+stv06xx         046D:08F0	QuickCamMessenger
+stv06xx         046D:08F5	QuickCamCommunicate
+stv06xx         046D:08F6	QuickCamMessenger (new)
+stv06xx         046d:0840	QuickCamExpress
+stv06xx         046d:0850	LEGOcam / QuickCam Web
+stv06xx         046d:0870	DexxaWebCam USB
+spca500         046d:0890	Logitech QuickCam traveler
+vc032x          046d:0892	Logitech Orbicam
+vc032x          046d:0896	Logitech Orbicam
+vc032x          046d:0897	Logitech QuickCam for Dell notebooks
+zc3xx           046d:089d	Logitech QuickCam E2500
+zc3xx           046d:08a0	Logitech QC IM
+zc3xx           046d:08a1	Logitech QC IM 0x08A1 +sound
+zc3xx           046d:08a2	Labtec Webcam Pro
+zc3xx           046d:08a3	Logitech QC Chat
+zc3xx           046d:08a6	Logitech QCim
+zc3xx           046d:08a7	Logitech QuickCam Image
+zc3xx           046d:08a9	Logitech Notebook Deluxe
+zc3xx           046d:08aa	Labtec Webcam Notebook
+zc3xx           046d:08ac	Logitech QuickCam Cool
+zc3xx           046d:08ad	Logitech QCCommunicate STX
+zc3xx           046d:08ae	Logitech QuickCam for Notebooks
+zc3xx           046d:08af	Logitech QuickCam Cool
+zc3xx           046d:08b9	Logitech QuickCam Express
+zc3xx           046d:08d7	Logitech QCam STX
+zc3xx           046d:08d8	Logitech Notebook Deluxe
+zc3xx           046d:08d9	Logitech QuickCam IM/Connect
+zc3xx           046d:08da	Logitech QuickCam Messenger
+zc3xx           046d:08dd	Logitech QuickCam for Notebooks
+spca500         046d:0900	Logitech Inc. ClickSmart 310
+spca500         046d:0901	Logitech Inc. ClickSmart 510
+sunplus         046d:0905	Logitech ClickSmart 820
+tv8532          046d:0920	Logitech QuickCam Express
+tv8532          046d:0921	Labtec Webcam
+spca561         046d:0928	Logitech QC Express Etch2
+spca561         046d:0929	Labtec Webcam Elch2
+spca561         046d:092a	Logitech QC for Notebook
+spca561         046d:092b	Labtec Webcam Plus
+spca561         046d:092c	Logitech QC chat Elch2
+spca561         046d:092d	Logitech QC Elch2
+spca561         046d:092e	Logitech QC Elch2
+spca561         046d:092f	Logitech QuickCam Express Plus
+sunplus         046d:0960	Logitech ClickSmart 420
+nw80x           046d:d001	Logitech QuickCam Pro (dark focus ring)
+se401           0471:030b	PhilipsPCVC665K
+sunplus         0471:0322	Philips DMVC1300K
+zc3xx           0471:0325	Philips SPC 200 NC
+zc3xx           0471:0326	Philips SPC 300 NC
+sonixj          0471:0327	Philips SPC 600 NC
+sonixj          0471:0328	Philips SPC 700 NC
+zc3xx           0471:032d	Philips SPC 210 NC
+zc3xx           0471:032e	Philips SPC 315 NC
+sonixj          0471:0330	Philips SPC 710 NC
+se401           047d:5001	Kensington67014
+se401           047d:5002	Kensington6701(5/7)
+se401           047d:5003	Kensington67016
+spca501         0497:c001	Smile International
+sunplus         04a5:3003	Benq DC 1300
+sunplus         04a5:3008	Benq DC 1500
+sunplus         04a5:300a	Benq DC 3410
+spca500         04a5:300c	Benq DC 1016
+benq            04a5:3035	Benq DC E300
+vicam           04c1:009d	HomeConnect Webcam [vicam]
+konica          04c8:0720	IntelYC 76
+finepix         04cb:0104	Fujifilm FinePix 4800
+finepix         04cb:0109	Fujifilm FinePix A202
+finepix         04cb:010b	Fujifilm FinePix A203
+finepix         04cb:010f	Fujifilm FinePix A204
+finepix         04cb:0111	Fujifilm FinePix A205
+finepix         04cb:0113	Fujifilm FinePix A210
+finepix         04cb:0115	Fujifilm FinePix A303
+finepix         04cb:0117	Fujifilm FinePix A310
+finepix         04cb:0119	Fujifilm FinePix F401
+finepix         04cb:011b	Fujifilm FinePix F402
+finepix         04cb:011d	Fujifilm FinePix F410
+finepix         04cb:0121	Fujifilm FinePix F601
+finepix         04cb:0123	Fujifilm FinePix F700
+finepix         04cb:0125	Fujifilm FinePix M603
+finepix         04cb:0127	Fujifilm FinePix S300
+finepix         04cb:0129	Fujifilm FinePix S304
+finepix         04cb:012b	Fujifilm FinePix S500
+finepix         04cb:012d	Fujifilm FinePix S602
+finepix         04cb:012f	Fujifilm FinePix S700
+finepix         04cb:0131	Fujifilm FinePix unknown model
+finepix         04cb:013b	Fujifilm FinePix unknown model
+finepix         04cb:013d	Fujifilm FinePix unknown model
+finepix         04cb:013f	Fujifilm FinePix F420
+sunplus         04f1:1001	JVC GC A50
+spca561         04fc:0561	Flexcam 100
+spca1528        04fc:1528	Sunplus MD80 clone
+sunplus         04fc:500c	Sunplus CA500C
+sunplus         04fc:504a	Aiptek Mini PenCam 1.3
+sunplus         04fc:504b	Maxell MaxPocket LE 1.3
+sunplus         04fc:5330	Digitrex 2110
+sunplus         04fc:5360	Sunplus Generic
+spca500         04fc:7333	PalmPixDC85
+sunplus         04fc:ffff	Pure DigitalDakota
+nw80x           0502:d001	DVC V6
+spca501         0506:00df	3Com HomeConnect Lite
+sunplus         052b:1507	Megapixel 5 Pretec DC-1007
+sunplus         052b:1513	Megapix V4
+sunplus         052b:1803	MegaImage VI
+nw80x           052b:d001	EZCam Pro p35u
+tv8532          0545:808b	Veo Stingray
+tv8532          0545:8333	Veo Stingray
+sunplus         0546:3155	Polaroid PDC3070
+sunplus         0546:3191	Polaroid Ion 80
+sunplus         0546:3273	Polaroid PDC2030
+touptek         0547:6801	TTUCMOS08000KPB, AS MU800
+dtcs033         0547:7303	Anchor Chips, Inc
+ov519           054c:0154	Sonny toy4
+ov519           054c:0155	Sonny toy5
+cpia1           0553:0002	CPIA CPiA (version1) based cameras
+stv0680         0553:0202	STV0680 Camera
+zc3xx           055f:c005	Mustek Wcam300A
+spca500         055f:c200	Mustek Gsmart 300
+sunplus         055f:c211	Kowa Bs888e Microcamera
+spca500         055f:c220	Gsmart Mini
+sunplus         055f:c230	Mustek Digicam 330K
+sunplus         055f:c232	Mustek MDC3500
+sunplus         055f:c360	Mustek DV4000 Mpeg4
+sunplus         055f:c420	Mustek gSmart Mini 2
+sunplus         055f:c430	Mustek Gsmart LCD 2
+sunplus         055f:c440	Mustek DV 3000
+sunplus         055f:c520	Mustek gSmart Mini 3
+sunplus         055f:c530	Mustek Gsmart LCD 3
+sunplus         055f:c540	Gsmart D30
+sunplus         055f:c630	Mustek MDC4000
+sunplus         055f:c650	Mustek MDC5500Z
+nw80x           055f:d001	Mustek Wcam 300 mini
+zc3xx           055f:d003	Mustek WCam300A
+zc3xx           055f:d004	Mustek WCam300 AN
+conex           0572:0041	Creative Notebook cx11646
+ov519           05a9:0511	Video Blaster WebCam 3/WebCam Plus, D-Link USB Digital Video Camera
+ov519           05a9:0518	Creative WebCam
+ov519           05a9:0519	OV519 Microphone
+ov519           05a9:0530	OmniVision
+ov534_9         05a9:1550	OmniVision VEHO Filmscanner
+ov519           05a9:2800	OmniVision SuperCAM
+ov519           05a9:4519	Webcam Classic
+ov534_9         05a9:8065	OmniVision test kit ov538+ov9712
+ov519           05a9:8519	OmniVision
+ov519           05a9:a511	D-Link USB Digital Video Camera
+ov519           05a9:a518	D-Link DSB-C310 Webcam
+sunplus         05da:1018	Digital Dream Enigma 1.3
+stk014          05e1:0893	Syntek DV4000
+gl860           05e3:0503	Genesys Logic PC Camera
+gl860           05e3:f191	Genesys Logic PC Camera
+vicam           0602:1001	ViCam Webcam
+spca561         060b:a001	Maxell Compact Pc PM3
+zc3xx           0698:2003	CTX M730V built in
+topro           06a2:0003	TP6800 PC Camera, CmoX CX0342 webcam
+topro           06a2:6810	Creative Qmax
+nw80x           06a5:0000	Typhoon Webcam 100 USB
+nw80x           06a5:d001	Divio based webcams
+nw80x           06a5:d800	Divio Chicony TwinkleCam, Trust SpaceCam
+spca500         06bd:0404	Agfa CL20
+spca500         06be:0800	Optimedia
+nw80x           06be:d001	EZCam Pro p35u
+sunplus         06d6:0031	Trust 610 LCD PowerC@m Zoom
+sunplus         06d6:0041	Aashima Technology B.V.
+spca506         06e1:a190	ADS Instant VCD
+ov534           06f8:3002	Hercules Blog Webcam
+ov534_9         06f8:3003	Hercules Dualpix HD Weblog
+sonixj          06f8:3004	Hercules Classic Silver
+sonixj          06f8:3008	Hercules Deluxe Optical Glass
+pac7302         06f8:3009	Hercules Classic Link
+pac7302         06f8:301b	Hercules Link
+nw80x           0728:d001	AVerMedia Camguard
+spca508         0733:0110	ViewQuest VQ110
+spca501         0733:0401	Intel Create and Share
+spca501         0733:0402	ViewQuest M318B
+spca505         0733:0430	Intel PC Camera Pro
+sunplus         0733:1311	Digital Dream Epsilon 1.3
+sunplus         0733:1314	Mercury 2.1MEG Deluxe Classic Cam
+sunplus         0733:2211	Jenoptik jdc 21 LCD
+sunplus         0733:2221	Mercury Digital Pro 3.1p
+sunplus         0733:3261	Concord 3045 spca536a
+sunplus         0733:3281	Cyberpix S550V
+spca506         0734:043b	3DeMon USB Capture aka
+cpia1           0813:0001	QX3 camera
+ov519           0813:0002	Dual Mode USB Camera Plus
+spca500         084d:0003	D-Link DSC-350
+spca500         08ca:0103	Aiptek PocketDV
+sunplus         08ca:0104	Aiptek PocketDVII 1.3
+sunplus         08ca:0106	Aiptek Pocket DV3100+
+mr97310a        08ca:0110	Trust Spyc@m 100
+mr97310a        08ca:0111	Aiptek PenCam VGA+
+sunplus         08ca:2008	Aiptek Mini PenCam 2 M
+sunplus         08ca:2010	Aiptek PocketCam 3M
+sunplus         08ca:2016	Aiptek PocketCam 2 Mega
+sunplus         08ca:2018	Aiptek Pencam SD 2M
+sunplus         08ca:2020	Aiptek Slim 3000F
+sunplus         08ca:2022	Aiptek Slim 3200
+sunplus         08ca:2024	Aiptek DV3500 Mpeg4
+sunplus         08ca:2028	Aiptek PocketCam4M
+sunplus         08ca:2040	Aiptek PocketDV4100M
+sunplus         08ca:2042	Aiptek PocketDV5100
+sunplus         08ca:2050	Medion MD 41437
+sunplus         08ca:2060	Aiptek PocketDV5300
+tv8532          0923:010f	ICM532 cams
+mr97310a        093a:010e	All known CIF cams with this ID
+mr97310a        093a:010f	All known VGA cams with this ID
+mars            093a:050f	Mars-Semi Pc-Camera
+pac207          093a:2460	Qtec Webcam 100
+pac207          093a:2461	HP Webcam
+pac207          093a:2463	Philips SPC 220 NC
+pac207          093a:2464	Labtec Webcam 1200
+pac207          093a:2468	Webcam WB-1400T
+pac207          093a:2470	Genius GF112
+pac207          093a:2471	Genius VideoCam ge111
+pac207          093a:2472	Genius VideoCam ge110
+pac207          093a:2474	Genius iLook 111
+pac207          093a:2476	Genius e-Messenger 112
+pac7311         093a:2600	PAC7311 Typhoon
+pac7311         093a:2601	Philips SPC 610 NC
+pac7311         093a:2603	Philips SPC 500 NC
+pac7311         093a:2608	Trust WB-3300p
+pac7311         093a:260e	Gigaware VGA PC Camera, Trust WB-3350p, SIGMA cam 2350
+pac7311         093a:260f	SnakeCam
+pac7302         093a:2620	Apollo AC-905
+pac7302         093a:2621	PAC731x
+pac7302         093a:2622	Genius Eye 312
+pac7302         093a:2623	Pixart Imaging, Inc.
+pac7302         093a:2624	PAC7302
+pac7302         093a:2625	Genius iSlim 310
+pac7302         093a:2626	Labtec 2200
+pac7302         093a:2627	Genius FaceCam 300
+pac7302         093a:2628	Genius iLook 300
+pac7302         093a:2629	Genius iSlim 300
+pac7302         093a:262a	Webcam 300k
+pac7302         093a:262c	Philips SPC 230 NC
+jl2005bcd       0979:0227	Various brands, 19 known cameras supported
+jeilinj         0979:0270	Sakar 57379
+jeilinj         0979:0280	Sportscam DV15, Sakar 57379
+zc3xx           0ac8:0301	Web Camera
+zc3xx           0ac8:0302	Z-star Vimicro zc0302
+vc032x          0ac8:0321	Vimicro generic vc0321
+vc032x          0ac8:0323	Vimicro Vc0323
+vc032x          0ac8:0328	A4Tech PK-130MG
+zc3xx           0ac8:301b	Z-Star zc301b
+zc3xx           0ac8:303b	Vimicro 0x303b
+zc3xx           0ac8:305b	Z-star Vimicro zc0305b
+zc3xx           0ac8:307b	PC Camera (ZS0211)
+vc032x          0ac8:c001	Sony embedded vimicro
+vc032x          0ac8:c002	Sony embedded vimicro
+vc032x          0ac8:c301	Samsung Q1 Ultra Premium
+spca508         0af9:0010	Hama USB Sightcam 100
+spca508         0af9:0011	Hama USB Sightcam 100
+ov519           0b62:0059	iBOT2 Webcam
+sonixb          0c45:6001	Genius VideoCAM NB
+sonixb          0c45:6005	Microdia Sweex Mini Webcam
+sonixb          0c45:6007	Sonix sn9c101 + Tas5110D
+sonixb          0c45:6009	spcaCam@120
+sonixb          0c45:600d	spcaCam@120
+sonixb          0c45:6011	Microdia PC Camera (SN9C102)
+sonixb          0c45:6019	Generic Sonix OV7630
+sonixb          0c45:6024	Generic Sonix Tas5130c
+sonixb          0c45:6025	Xcam Shanga
+sonixb          0c45:6027	GeniusEye 310
+sonixb          0c45:6028	Sonix Btc Pc380
+sonixb          0c45:6029	spcaCam@150
+sonixb          0c45:602a	Meade ETX-105EC Camera
+sonixb          0c45:602c	Generic Sonix OV7630
+sonixb          0c45:602d	LIC-200 LG
+sonixb          0c45:602e	Genius VideoCam Messenger
+sonixj          0c45:6040	Speed NVC 350K
+sonixj          0c45:607c	Sonix sn9c102p Hv7131R
+sonixb          0c45:6083	VideoCAM Look
+sonixb          0c45:608c	VideoCAM Look
+sonixb          0c45:608f	PC Camera (SN9C103 + OV7630)
+sonixb          0c45:60a8	VideoCAM Look
+sonixb          0c45:60aa	VideoCAM Look
+sonixb          0c45:60af	VideoCAM Look
+sonixb          0c45:60b0	Genius VideoCam Look
+sonixj          0c45:60c0	Sangha Sn535
+sonixj          0c45:60ce	USB-PC-Camera-168 (TALK-5067)
+sonixj          0c45:60ec	SN9C105+MO4000
+sonixj          0c45:60fb	Surfer NoName
+sonixj          0c45:60fc	LG-LIC300
+sonixj          0c45:60fe	Microdia Audio
+sonixj          0c45:6100	PC Camera (SN9C128)
+sonixj          0c45:6102	PC Camera (SN9C128)
+sonixj          0c45:610a	PC Camera (SN9C128)
+sonixj          0c45:610b	PC Camera (SN9C128)
+sonixj          0c45:610c	PC Camera (SN9C128)
+sonixj          0c45:610e	PC Camera (SN9C128)
+sonixj          0c45:6128	Microdia/Sonix SNP325
+sonixj          0c45:612a	Avant Camera
+sonixj          0c45:612b	Speed-Link REFLECT2
+sonixj          0c45:612c	Typhoon Rasy Cam 1.3MPix
+sonixj          0c45:612e	PC Camera (SN9C110)
+sonixj          0c45:6130	Sonix Pccam
+sonixj          0c45:6138	Sn9c120 Mo4000
+sonixj          0c45:613a	Microdia Sonix PC Camera
+sonixj          0c45:613b	Surfer SN-206
+sonixj          0c45:613c	Sonix Pccam168
+sonixj          0c45:613e	PC Camera (SN9C120)
+sonixj          0c45:6142	Hama PC-Webcam AC-150
+sonixj          0c45:6143	Sonix Pccam168
+sonixj          0c45:6148	Digitus DA-70811/ZSMC USB PC Camera ZS211/Microdia
+sonixj          0c45:614a	Frontech E-Ccam (JIL-2225)
+sn9c20x         0c45:6240	PC Camera (SN9C201 + MT9M001)
+sn9c20x         0c45:6242	PC Camera (SN9C201 + MT9M111)
+sn9c20x         0c45:6248	PC Camera (SN9C201 + OV9655)
+sn9c20x         0c45:624c	PC Camera (SN9C201 + MT9M112)
+sn9c20x         0c45:624e	PC Camera (SN9C201 + SOI968)
+sn9c20x         0c45:624f	PC Camera (SN9C201 + OV9650)
+sn9c20x         0c45:6251	PC Camera (SN9C201 + OV9650)
+sn9c20x         0c45:6253	PC Camera (SN9C201 + OV9650)
+sn9c20x         0c45:6260	PC Camera (SN9C201 + OV7670)
+sn9c20x         0c45:6270	PC Camera (SN9C201 + MT9V011/MT9V111/MT9V112)
+sn9c20x         0c45:627b	PC Camera (SN9C201 + OV7660)
+sn9c20x         0c45:627c	PC Camera (SN9C201 + HV7131R)
+sn9c20x         0c45:627f	PC Camera (SN9C201 + OV9650)
+sn9c20x         0c45:6280	PC Camera (SN9C202 + MT9M001)
+sn9c20x         0c45:6282	PC Camera (SN9C202 + MT9M111)
+sn9c20x         0c45:6288	PC Camera (SN9C202 + OV9655)
+sn9c20x         0c45:628c	PC Camera (SN9C201 + MT9M112)
+sn9c20x         0c45:628e	PC Camera (SN9C202 + SOI968)
+sn9c20x         0c45:628f	PC Camera (SN9C202 + OV9650)
+sn9c20x         0c45:62a0	PC Camera (SN9C202 + OV7670)
+sn9c20x         0c45:62b0	PC Camera (SN9C202 + MT9V011/MT9V111/MT9V112)
+sn9c20x         0c45:62b3	PC Camera (SN9C202 + OV9655)
+sn9c20x         0c45:62bb	PC Camera (SN9C202 + OV7660)
+sn9c20x         0c45:62bc	PC Camera (SN9C202 + HV7131R)
+sn9c2028        0c45:8001	Wild Planet Digital Spy Camera
+sn9c2028        0c45:8003	Sakar #11199, #6637x, #67480 keychain cams
+sn9c2028        0c45:8008	Mini-Shotz ms-350
+sn9c2028        0c45:800a	Vivitar Vivicam 3350B
+sunplus         0d64:0303	Sunplus FashionCam DXG
+ov519           0e96:c001	TRUST 380 USB2 SPACEC@M
+etoms           102c:6151	Qcam Sangha CIF
+etoms           102c:6251	Qcam xxxxxx VGA
+ov519           1046:9967	W9967CF/W9968CF WebCam IC, Video Blaster WebCam Go
+zc3xx           10fd:0128	Typhoon Webshot II USB 300k 0x0128
+spca561         10fd:7e50	FlyCam Usb 100
+zc3xx           10fd:804d	Typhoon Webshot II Webcam [zc0301]
+zc3xx           10fd:8050	Typhoon Webshot II USB 300k
+ov534           1415:2000	Sony HD Eye for PS3 (SLEH 00201)
+pac207          145f:013a	Trust WB-1300N
+pac7302         145f:013c	Trust
+sn9c20x         145f:013d	Trust WB-3600R
+vc032x          15b8:6001	HP 2.0 Megapixel
+vc032x          15b8:6002	HP 2.0 Megapixel rz406aa
+stk1135         174f:6a31	ASUSlaptop, MT9M112 sensor
+spca501         1776:501c	Arowana 300K CMOS Camera
+t613            17a1:0128	TASCORP JPEG Webcam, NGS Cyclops
+vc032x          17ef:4802	Lenovo Vc0323+MI1310_SOC
+pac7302         1ae7:2001	SpeedLinkSnappy Mic SL-6825-SBK
+pac207          2001:f115	D-Link DSB-C120
+sq905c          2770:9050	Disney pix micro (CIF)
+sq905c          2770:9051	Lego Bionicle
+sq905c          2770:9052	Disney pix micro 2 (VGA)
+sq905c          2770:905c	All 11 known cameras with this ID
+sq905           2770:9120	All 24 known cameras with this ID
+sq905c          2770:913d	All 4 known cameras with this ID
+sq930x          2770:930b	Sweex Motion Tracking / I-Tec iCam Tracer
+sq930x          2770:930c	Trust WB-3500T / NSG Robbie 2.0
+spca500         2899:012c	Toptro Industrial
+ov519           8020:ef04	ov519
+spca508         8086:0110	Intel Easy PC Camera
+spca500         8086:0630	Intel Pocket PC Camera
+spca506         99fa:8988	Grandtec V.cap
+sn9c20x         a168:0610	Dino-Lite Digital Microscope (SN9C201 + HV7131R)
+sn9c20x         a168:0611	Dino-Lite Digital Microscope (SN9C201 + HV7131R)
+sn9c20x         a168:0613	Dino-Lite Digital Microscope (SN9C201 + HV7131R)
+sn9c20x         a168:0614	Dino-Lite Digital Microscope (SN9C201 + MT9M111)
+sn9c20x         a168:0615	Dino-Lite Digital Microscope (SN9C201 + MT9M111)
+sn9c20x         a168:0617	Dino-Lite Digital Microscope (SN9C201 + MT9M111)
+sn9c20x         a168:0618	Dino-Lite Digital Microscope (SN9C201 + HV7131R)
+spca561         abcd:cdee	Petcam
+=========	=========	===================================================================
diff --git a/Documentation/admin-guide/media/i2c-cardlist.rst b/Documentation/admin-guide/media/i2c-cardlist.rst
new file mode 100644
index 000000000..fff962558
--- /dev/null
+++ b/Documentation/admin-guide/media/i2c-cardlist.rst
@@ -0,0 +1,287 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+I²C drivers
+===========
+
+The I²C (Inter-Integrated Circuit) bus is a three-wires bus used internally
+at the media cards for communication between different chips. While the bus
+is not visible to the Linux Kernel, drivers need to send and receive
+commands via the bus. The Linux Kernel driver abstraction has support to
+implement different drivers for each component inside an I²C bus, as if
+the bus were visible to the main system board.
+
+One of the problems with I²C devices is that sometimes the same device may
+work with different I²C hardware. This is common, for example, on devices
+that comes with a tuner for North America market, and another one for
+Europe. Some drivers have a ``tuner=`` modprobe parameter to allow using a
+different tuner number in order to address such issue.
+
+The current supported of I²C drivers (not including staging drivers) are
+listed below.
+
+Audio decoders, processors and mixers
+-------------------------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+cs3308        Cirrus Logic CS3308 audio ADC
+cs5345        Cirrus Logic CS5345 audio ADC
+cs53l32a      Cirrus Logic CS53L32A audio ADC
+msp3400       Micronas MSP34xx audio decoders
+sony-btf-mpx  Sony BTF's internal MPX
+tda1997x      NXP TDA1997x HDMI receiver
+tda7432       Philips TDA7432 audio processor
+tda9840       Philips TDA9840 audio processor
+tea6415c      Philips TEA6415C audio processor
+tea6420       Philips TEA6420 audio processor
+tlv320aic23b  Texas Instruments TLV320AIC23B audio codec
+tvaudio       Simple audio decoder chips
+uda1342       Philips UDA1342 audio codec
+vp27smpx      Panasonic VP27's internal MPX
+wm8739        Wolfson Microelectronics WM8739 stereo audio ADC
+wm8775        Wolfson Microelectronics WM8775 audio ADC with input mixer
+============  ==========================================================
+
+Audio/Video compression chips
+-----------------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+saa6752hs     Philips SAA6752HS MPEG-2 Audio/Video Encoder
+============  ==========================================================
+
+Camera sensor devices
+---------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+ccs           MIPI CCS compliant camera sensors (also SMIA++ and SMIA)
+et8ek8        ET8EK8 camera sensor
+hi556         Hynix Hi-556 sensor
+hi846         Hynix Hi-846 sensor
+imx208        Sony IMX208 sensor
+imx214        Sony IMX214 sensor
+imx219        Sony IMX219 sensor
+imx258        Sony IMX258 sensor
+imx274        Sony IMX274 sensor
+imx290        Sony IMX290 sensor
+imx319        Sony IMX319 sensor
+imx334        Sony IMX334 sensor
+imx355        Sony IMX355 sensor
+imx412        Sony IMX412 sensor
+mt9m001       mt9m001
+mt9m111       mt9m111, mt9m112 and mt9m131
+mt9p031       Aptina MT9P031
+mt9t112       Aptina MT9T111/MT9T112
+mt9v011       Micron mt9v011 sensor
+mt9v032       Micron MT9V032 sensor
+mt9v111       Aptina MT9V111 sensor
+ov13858       OmniVision OV13858 sensor
+ov13b10       OmniVision OV13B10 sensor
+ov2640        OmniVision OV2640 sensor
+ov2659        OmniVision OV2659 sensor
+ov2680        OmniVision OV2680 sensor
+ov2685        OmniVision OV2685 sensor
+ov5640        OmniVision OV5640 sensor
+ov5645        OmniVision OV5645 sensor
+ov5647        OmniVision OV5647 sensor
+ov5670        OmniVision OV5670 sensor
+ov5675        OmniVision OV5675 sensor
+ov5695        OmniVision OV5695 sensor
+ov7251        OmniVision OV7251 sensor
+ov7640        OmniVision OV7640 sensor
+ov7670        OmniVision OV7670 sensor
+ov772x        OmniVision OV772x sensor
+ov7740        OmniVision OV7740 sensor
+ov8856        OmniVision OV8856 sensor
+ov9640        OmniVision OV9640 sensor
+ov9650        OmniVision OV9650/OV9652 sensor
+rj54n1cb0c    Sharp RJ54N1CB0C sensor
+s5c73m3       Samsung S5C73M3 sensor
+s5k4ecgx      Samsung S5K4ECGX sensor
+s5k5baf       Samsung S5K5BAF sensor
+s5k6a3        Samsung S5K6A3 sensor
+============  ==========================================================
+
+Flash devices
+-------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+adp1653       ADP1653 flash
+lm3560        LM3560 dual flash driver
+lm3646        LM3646 dual flash driver
+============  ==========================================================
+
+IR I2C driver
+-------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+ir-kbd-i2c    I2C module for IR
+============  ==========================================================
+
+Lens drivers
+------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+ad5820        AD5820 lens voice coil
+ak7375        AK7375 lens voice coil
+dw9714        DW9714 lens voice coil
+dw9768        DW9768 lens voice coil
+dw9807-vcm    DW9807 lens voice coil
+============  ==========================================================
+
+Miscellaneous helper chips
+--------------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+video-i2c     I2C transport video
+m52790        Mitsubishi M52790 A/V switch
+st-mipid02    STMicroelectronics MIPID02 CSI-2 to PARALLEL bridge
+ths7303       THS7303/53 Video Amplifier
+============  ==========================================================
+
+RDS decoders
+------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+saa6588       SAA6588 Radio Chip RDS decoder
+============  ==========================================================
+
+SDR tuner chips
+---------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+max2175       Maxim 2175 RF to Bits tuner
+============  ==========================================================
+
+Video and audio decoders
+------------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+cx25840       Conexant CX2584x audio/video decoders
+saa717x       Philips SAA7171/3/4 audio/video decoders
+============  ==========================================================
+
+Video decoders
+--------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+adv7180       Analog Devices ADV7180 decoder
+adv7183       Analog Devices ADV7183 decoder
+adv748x       Analog Devices ADV748x decoder
+adv7604       Analog Devices ADV7604 decoder
+adv7842       Analog Devices ADV7842 decoder
+bt819         BT819A VideoStream decoder
+bt856         BT856 VideoStream decoder
+bt866         BT866 VideoStream decoder
+ks0127        KS0127 video decoder
+ml86v7667     OKI ML86V7667 video decoder
+saa7110       Philips SAA7110 video decoder
+saa7115       Philips SAA7111/3/4/5 video decoders
+tc358743      Toshiba TC358743 decoder
+tvp514x       Texas Instruments TVP514x video decoder
+tvp5150       Texas Instruments TVP5150 video decoder
+tvp7002       Texas Instruments TVP7002 video decoder
+tw2804        Techwell TW2804 multiple video decoder
+tw9903        Techwell TW9903 video decoder
+tw9906        Techwell TW9906 video decoder
+tw9910        Techwell TW9910 video decoder
+vpx3220       vpx3220a, vpx3216b & vpx3214c video decoders
+============  ==========================================================
+
+Video encoders
+--------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+adv7170       Analog Devices ADV7170 video encoder
+adv7175       Analog Devices ADV7175 video encoder
+adv7343       ADV7343 video encoder
+adv7393       ADV7393 video encoder
+adv7511-v4l2  Analog Devices ADV7511 encoder
+ak881x        AK8813/AK8814 video encoders
+saa7127       Philips SAA7127/9 digital video encoders
+saa7185       Philips SAA7185 video encoder
+ths8200       Texas Instruments THS8200 video encoder
+============  ==========================================================
+
+Video improvement chips
+-----------------------
+
+============  ==========================================================
+Driver        Name
+============  ==========================================================
+upd64031a     NEC Electronics uPD64031A Ghost Reduction
+upd64083      NEC Electronics uPD64083 3-Dimensional Y/C separation
+============  ==========================================================
+
+Tuner drivers
+-------------
+
+============  ==================================================
+Driver        Name
+============  ==================================================
+e4000         Elonics E4000 silicon tuner
+fc0011        Fitipower FC0011 silicon tuner
+fc0012        Fitipower FC0012 silicon tuner
+fc0013        Fitipower FC0013 silicon tuner
+fc2580        FCI FC2580 silicon tuner
+it913x        ITE Tech IT913x silicon tuner
+m88rs6000t    Montage M88RS6000 internal tuner
+max2165       Maxim MAX2165 silicon tuner
+mc44s803      Freescale MC44S803 Low Power CMOS Broadband tuners
+msi001        Mirics MSi001
+mt2060        Microtune MT2060 silicon IF tuner
+mt2063        Microtune MT2063 silicon IF tuner
+mt20xx        Microtune 2032 / 2050 tuners
+mt2131        Microtune MT2131 silicon tuner
+mt2266        Microtune MT2266 silicon tuner
+mxl301rf      MaxLinear MxL301RF tuner
+mxl5005s      MaxLinear MSL5005S silicon tuner
+mxl5007t      MaxLinear MxL5007T silicon tuner
+qm1d1b0004    Sharp QM1D1B0004 tuner
+qm1d1c0042    Sharp QM1D1C0042 tuner
+qt1010        Quantek QT1010 silicon tuner
+r820t         Rafael Micro R820T silicon tuner
+si2157        Silicon Labs Si2157 silicon tuner
+tuner-types   Simple tuner support
+tda18212      NXP TDA18212 silicon tuner
+tda18218      NXP TDA18218 silicon tuner
+tda18250      NXP TDA18250 silicon tuner
+tda18271      NXP TDA18271 silicon tuner
+tda827x       Philips TDA827X silicon tuner
+tda8290       TDA 8290/8295 + 8275(a)/18271 tuner combo
+tda9887       TDA 9885/6/7 analog IF demodulator
+tea5761       TEA 5761 radio tuner
+tea5767       TEA 5767 radio tuner
+tua9001       Infineon TUA9001 silicon tuner
+xc2028        XCeive xc2028/xc3028 tuners
+xc4000        Xceive XC4000 silicon tuner
+xc5000        Xceive XC5000 silicon tuner
+============  ==================================================
+
+.. toctree::
+	:maxdepth: 1
+
+	tuner-cardlist
+	frontend-cardlist
diff --git a/Documentation/admin-guide/media/imx.rst b/Documentation/admin-guide/media/imx.rst
new file mode 100644
index 000000000..bb68100d8
--- /dev/null
+++ b/Documentation/admin-guide/media/imx.rst
@@ -0,0 +1,714 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+i.MX Video Capture Driver
+=========================
+
+Introduction
+------------
+
+The Freescale i.MX5/6 contains an Image Processing Unit (IPU), which
+handles the flow of image frames to and from capture devices and
+display devices.
+
+For image capture, the IPU contains the following internal subunits:
+
+- Image DMA Controller (IDMAC)
+- Camera Serial Interface (CSI)
+- Image Converter (IC)
+- Sensor Multi-FIFO Controller (SMFC)
+- Image Rotator (IRT)
+- Video De-Interlacing or Combining Block (VDIC)
+
+The IDMAC is the DMA controller for transfer of image frames to and from
+memory. Various dedicated DMA channels exist for both video capture and
+display paths. During transfer, the IDMAC is also capable of vertical
+image flip, 8x8 block transfer (see IRT description), pixel component
+re-ordering (for example UYVY to YUYV) within the same colorspace, and
+packed <--> planar conversion. The IDMAC can also perform a simple
+de-interlacing by interweaving even and odd lines during transfer
+(without motion compensation which requires the VDIC).
+
+The CSI is the backend capture unit that interfaces directly with
+camera sensors over Parallel, BT.656/1120, and MIPI CSI-2 buses.
+
+The IC handles color-space conversion, resizing (downscaling and
+upscaling), horizontal flip, and 90/270 degree rotation operations.
+
+There are three independent "tasks" within the IC that can carry out
+conversions concurrently: pre-process encoding, pre-process viewfinder,
+and post-processing. Within each task, conversions are split into three
+sections: downsizing section, main section (upsizing, flip, colorspace
+conversion, and graphics plane combining), and rotation section.
+
+The IPU time-shares the IC task operations. The time-slice granularity
+is one burst of eight pixels in the downsizing section, one image line
+in the main processing section, one image frame in the rotation section.
+
+The SMFC is composed of four independent FIFOs that each can transfer
+captured frames from sensors directly to memory concurrently via four
+IDMAC channels.
+
+The IRT carries out 90 and 270 degree image rotation operations. The
+rotation operation is carried out on 8x8 pixel blocks at a time. This
+operation is supported by the IDMAC which handles the 8x8 block transfer
+along with block reordering, in coordination with vertical flip.
+
+The VDIC handles the conversion of interlaced video to progressive, with
+support for different motion compensation modes (low, medium, and high
+motion). The deinterlaced output frames from the VDIC can be sent to the
+IC pre-process viewfinder task for further conversions. The VDIC also
+contains a Combiner that combines two image planes, with alpha blending
+and color keying.
+
+In addition to the IPU internal subunits, there are also two units
+outside the IPU that are also involved in video capture on i.MX:
+
+- MIPI CSI-2 Receiver for camera sensors with the MIPI CSI-2 bus
+  interface. This is a Synopsys DesignWare core.
+- Two video multiplexers for selecting among multiple sensor inputs
+  to send to a CSI.
+
+For more info, refer to the latest versions of the i.MX5/6 reference
+manuals [#f1]_ and [#f2]_.
+
+
+Features
+--------
+
+Some of the features of this driver include:
+
+- Many different pipelines can be configured via media controller API,
+  that correspond to the hardware video capture pipelines supported in
+  the i.MX.
+
+- Supports parallel, BT.565, and MIPI CSI-2 interfaces.
+
+- Concurrent independent streams, by configuring pipelines to multiple
+  video capture interfaces using independent entities.
+
+- Scaling, color-space conversion, horizontal and vertical flip, and
+  image rotation via IC task subdevs.
+
+- Many pixel formats supported (RGB, packed and planar YUV, partial
+  planar YUV).
+
+- The VDIC subdev supports motion compensated de-interlacing, with three
+  motion compensation modes: low, medium, and high motion. Pipelines are
+  defined that allow sending frames to the VDIC subdev directly from the
+  CSI. There is also support in the future for sending frames to the
+  VDIC from memory buffers via output/mem2mem devices.
+
+- Includes a Frame Interval Monitor (FIM) that can correct vertical sync
+  problems with the ADV718x video decoders.
+
+
+Topology
+--------
+
+The following shows the media topologies for the i.MX6Q SabreSD and
+i.MX6Q SabreAuto. Refer to these diagrams in the entity descriptions
+in the next section.
+
+The i.MX5/6 topologies can differ upstream from the IPUv3 CSI video
+multiplexers, but the internal IPUv3 topology downstream from there
+is common to all i.MX5/6 platforms. For example, the SabreSD, with the
+MIPI CSI-2 OV5640 sensor, requires the i.MX6 MIPI CSI-2 receiver. But
+the SabreAuto has only the ADV7180 decoder on a parallel bt.656 bus, and
+therefore does not require the MIPI CSI-2 receiver, so it is missing in
+its graph.
+
+.. _imx6q_topology_graph:
+
+.. kernel-figure:: imx6q-sabresd.dot
+    :alt:   Diagram of the i.MX6Q SabreSD media pipeline topology
+    :align: center
+
+    Media pipeline graph on i.MX6Q SabreSD
+
+.. kernel-figure:: imx6q-sabreauto.dot
+    :alt:   Diagram of the i.MX6Q SabreAuto media pipeline topology
+    :align: center
+
+    Media pipeline graph on i.MX6Q SabreAuto
+
+Entities
+--------
+
+imx6-mipi-csi2
+--------------
+
+This is the MIPI CSI-2 receiver entity. It has one sink pad to receive
+the MIPI CSI-2 stream (usually from a MIPI CSI-2 camera sensor). It has
+four source pads, corresponding to the four MIPI CSI-2 demuxed virtual
+channel outputs. Multiple source pads can be enabled to independently
+stream from multiple virtual channels.
+
+This entity actually consists of two sub-blocks. One is the MIPI CSI-2
+core. This is a Synopsys Designware MIPI CSI-2 core. The other sub-block
+is a "CSI-2 to IPU gasket". The gasket acts as a demultiplexer of the
+four virtual channels streams, providing four separate parallel buses
+containing each virtual channel that are routed to CSIs or video
+multiplexers as described below.
+
+On i.MX6 solo/dual-lite, all four virtual channel buses are routed to
+two video multiplexers. Both CSI0 and CSI1 can receive any virtual
+channel, as selected by the video multiplexers.
+
+On i.MX6 Quad, virtual channel 0 is routed to IPU1-CSI0 (after selected
+by a video mux), virtual channels 1 and 2 are hard-wired to IPU1-CSI1
+and IPU2-CSI0, respectively, and virtual channel 3 is routed to
+IPU2-CSI1 (again selected by a video mux).
+
+ipuX_csiY_mux
+-------------
+
+These are the video multiplexers. They have two or more sink pads to
+select from either camera sensors with a parallel interface, or from
+MIPI CSI-2 virtual channels from imx6-mipi-csi2 entity. They have a
+single source pad that routes to a CSI (ipuX_csiY entities).
+
+On i.MX6 solo/dual-lite, there are two video mux entities. One sits
+in front of IPU1-CSI0 to select between a parallel sensor and any of
+the four MIPI CSI-2 virtual channels (a total of five sink pads). The
+other mux sits in front of IPU1-CSI1, and again has five sink pads to
+select between a parallel sensor and any of the four MIPI CSI-2 virtual
+channels.
+
+On i.MX6 Quad, there are two video mux entities. One sits in front of
+IPU1-CSI0 to select between a parallel sensor and MIPI CSI-2 virtual
+channel 0 (two sink pads). The other mux sits in front of IPU2-CSI1 to
+select between a parallel sensor and MIPI CSI-2 virtual channel 3 (two
+sink pads).
+
+ipuX_csiY
+---------
+
+These are the CSI entities. They have a single sink pad receiving from
+either a video mux or from a MIPI CSI-2 virtual channel as described
+above.
+
+This entity has two source pads. The first source pad can link directly
+to the ipuX_vdic entity or the ipuX_ic_prp entity, using hardware links
+that require no IDMAC memory buffer transfer.
+
+When the direct source pad is routed to the ipuX_ic_prp entity, frames
+from the CSI can be processed by one or both of the IC pre-processing
+tasks.
+
+When the direct source pad is routed to the ipuX_vdic entity, the VDIC
+will carry out motion-compensated de-interlace using "high motion" mode
+(see description of ipuX_vdic entity).
+
+The second source pad sends video frames directly to memory buffers
+via the SMFC and an IDMAC channel, bypassing IC pre-processing. This
+source pad is routed to a capture device node, with a node name of the
+format "ipuX_csiY capture".
+
+Note that since the IDMAC source pad makes use of an IDMAC channel,
+pixel reordering within the same colorspace can be carried out by the
+IDMAC channel. For example, if the CSI sink pad is receiving in UYVY
+order, the capture device linked to the IDMAC source pad can capture
+in YUYV order. Also, if the CSI sink pad is receiving a packed YUV
+format, the capture device can capture a planar YUV format such as
+YUV420.
+
+The IDMAC channel at the IDMAC source pad also supports simple
+interweave without motion compensation, which is activated if the source
+pad's field type is sequential top-bottom or bottom-top, and the
+requested capture interface field type is set to interlaced (t-b, b-t,
+or unqualified interlaced). The capture interface will enforce the same
+field order as the source pad field order (interlaced-bt if source pad
+is seq-bt, interlaced-tb if source pad is seq-tb).
+
+For events produced by ipuX_csiY, see ref:`imx_api_ipuX_csiY`.
+
+Cropping in ipuX_csiY
+---------------------
+
+The CSI supports cropping the incoming raw sensor frames. This is
+implemented in the ipuX_csiY entities at the sink pad, using the
+crop selection subdev API.
+
+The CSI also supports fixed divide-by-two downscaling independently in
+width and height. This is implemented in the ipuX_csiY entities at
+the sink pad, using the compose selection subdev API.
+
+The output rectangle at the ipuX_csiY source pad is the same as
+the compose rectangle at the sink pad. So the source pad rectangle
+cannot be negotiated, it must be set using the compose selection
+API at sink pad (if /2 downscale is desired, otherwise source pad
+rectangle is equal to incoming rectangle).
+
+To give an example of crop and /2 downscale, this will crop a
+1280x960 input frame to 640x480, and then /2 downscale in both
+dimensions to 320x240 (assumes ipu1_csi0 is linked to ipu1_csi0_mux):
+
+.. code-block:: none
+
+   media-ctl -V "'ipu1_csi0_mux':2[fmt:UYVY2X8/1280x960]"
+   media-ctl -V "'ipu1_csi0':0[crop:(0,0)/640x480]"
+   media-ctl -V "'ipu1_csi0':0[compose:(0,0)/320x240]"
+
+Frame Skipping in ipuX_csiY
+---------------------------
+
+The CSI supports frame rate decimation, via frame skipping. Frame
+rate decimation is specified by setting the frame intervals at
+sink and source pads. The ipuX_csiY entity then applies the best
+frame skip setting to the CSI to achieve the desired frame rate
+at the source pad.
+
+The following example reduces an assumed incoming 60 Hz frame
+rate by half at the IDMAC output source pad:
+
+.. code-block:: none
+
+   media-ctl -V "'ipu1_csi0':0[fmt:UYVY2X8/640x480@1/60]"
+   media-ctl -V "'ipu1_csi0':2[fmt:UYVY2X8/640x480@1/30]"
+
+Frame Interval Monitor in ipuX_csiY
+-----------------------------------
+
+See ref:`imx_api_FIM`.
+
+ipuX_vdic
+---------
+
+The VDIC carries out motion compensated de-interlacing, with three
+motion compensation modes: low, medium, and high motion. The mode is
+specified with the menu control V4L2_CID_DEINTERLACING_MODE. The VDIC
+has two sink pads and a single source pad.
+
+The direct sink pad receives from an ipuX_csiY direct pad. With this
+link the VDIC can only operate in high motion mode.
+
+When the IDMAC sink pad is activated, it receives from an output
+or mem2mem device node. With this pipeline, the VDIC can also operate
+in low and medium modes, because these modes require receiving
+frames from memory buffers. Note that an output or mem2mem device
+is not implemented yet, so this sink pad currently has no links.
+
+The source pad routes to the IC pre-processing entity ipuX_ic_prp.
+
+ipuX_ic_prp
+-----------
+
+This is the IC pre-processing entity. It acts as a router, routing
+data from its sink pad to one or both of its source pads.
+
+This entity has a single sink pad. The sink pad can receive from the
+ipuX_csiY direct pad, or from ipuX_vdic.
+
+This entity has two source pads. One source pad routes to the
+pre-process encode task entity (ipuX_ic_prpenc), the other to the
+pre-process viewfinder task entity (ipuX_ic_prpvf). Both source pads
+can be activated at the same time if the sink pad is receiving from
+ipuX_csiY. Only the source pad to the pre-process viewfinder task entity
+can be activated if the sink pad is receiving from ipuX_vdic (frames
+from the VDIC can only be processed by the pre-process viewfinder task).
+
+ipuX_ic_prpenc
+--------------
+
+This is the IC pre-processing encode entity. It has a single sink
+pad from ipuX_ic_prp, and a single source pad. The source pad is
+routed to a capture device node, with a node name of the format
+"ipuX_ic_prpenc capture".
+
+This entity performs the IC pre-process encode task operations:
+color-space conversion, resizing (downscaling and upscaling),
+horizontal and vertical flip, and 90/270 degree rotation. Flip
+and rotation are provided via standard V4L2 controls.
+
+Like the ipuX_csiY IDMAC source, this entity also supports simple
+de-interlace without motion compensation, and pixel reordering.
+
+ipuX_ic_prpvf
+-------------
+
+This is the IC pre-processing viewfinder entity. It has a single sink
+pad from ipuX_ic_prp, and a single source pad. The source pad is routed
+to a capture device node, with a node name of the format
+"ipuX_ic_prpvf capture".
+
+This entity is identical in operation to ipuX_ic_prpenc, with the same
+resizing and CSC operations and flip/rotation controls. It will receive
+and process de-interlaced frames from the ipuX_vdic if ipuX_ic_prp is
+receiving from ipuX_vdic.
+
+Like the ipuX_csiY IDMAC source, this entity supports simple
+interweaving without motion compensation. However, note that if the
+ipuX_vdic is included in the pipeline (ipuX_ic_prp is receiving from
+ipuX_vdic), it's not possible to use interweave in ipuX_ic_prpvf,
+since the ipuX_vdic has already carried out de-interlacing (with
+motion compensation) and therefore the field type output from
+ipuX_vdic can only be none (progressive).
+
+Capture Pipelines
+-----------------
+
+The following describe the various use-cases supported by the pipelines.
+
+The links shown do not include the backend sensor, video mux, or mipi
+csi-2 receiver links. This depends on the type of sensor interface
+(parallel or mipi csi-2). So these pipelines begin with:
+
+sensor -> ipuX_csiY_mux -> ...
+
+for parallel sensors, or:
+
+sensor -> imx6-mipi-csi2 -> (ipuX_csiY_mux) -> ...
+
+for mipi csi-2 sensors. The imx6-mipi-csi2 receiver may need to route
+to the video mux (ipuX_csiY_mux) before sending to the CSI, depending
+on the mipi csi-2 virtual channel, hence ipuX_csiY_mux is shown in
+parenthesis.
+
+Unprocessed Video Capture:
+--------------------------
+
+Send frames directly from sensor to camera device interface node, with
+no conversions, via ipuX_csiY IDMAC source pad:
+
+-> ipuX_csiY:2 -> ipuX_csiY capture
+
+IC Direct Conversions:
+----------------------
+
+This pipeline uses the preprocess encode entity to route frames directly
+from the CSI to the IC, to carry out scaling up to 1024x1024 resolution,
+CSC, flipping, and image rotation:
+
+-> ipuX_csiY:1 -> 0:ipuX_ic_prp:1 -> 0:ipuX_ic_prpenc:1 -> ipuX_ic_prpenc capture
+
+Motion Compensated De-interlace:
+--------------------------------
+
+This pipeline routes frames from the CSI direct pad to the VDIC entity to
+support motion-compensated de-interlacing (high motion mode only),
+scaling up to 1024x1024, CSC, flip, and rotation:
+
+-> ipuX_csiY:1 -> 0:ipuX_vdic:2 -> 0:ipuX_ic_prp:2 -> 0:ipuX_ic_prpvf:1 -> ipuX_ic_prpvf capture
+
+
+Usage Notes
+-----------
+
+To aid in configuration and for backward compatibility with V4L2
+applications that access controls only from video device nodes, the
+capture device interfaces inherit controls from the active entities
+in the current pipeline, so controls can be accessed either directly
+from the subdev or from the active capture device interface. For
+example, the FIM controls are available either from the ipuX_csiY
+subdevs or from the active capture device.
+
+The following are specific usage notes for the Sabre* reference
+boards:
+
+
+i.MX6Q SabreLite with OV5642 and OV5640
+---------------------------------------
+
+This platform requires the OmniVision OV5642 module with a parallel
+camera interface, and the OV5640 module with a MIPI CSI-2
+interface. Both modules are available from Boundary Devices:
+
+- https://boundarydevices.com/product/nit6x_5mp
+- https://boundarydevices.com/product/nit6x_5mp_mipi
+
+Note that if only one camera module is available, the other sensor
+node can be disabled in the device tree.
+
+The OV5642 module is connected to the parallel bus input on the i.MX
+internal video mux to IPU1 CSI0. It's i2c bus connects to i2c bus 2.
+
+The MIPI CSI-2 OV5640 module is connected to the i.MX internal MIPI CSI-2
+receiver, and the four virtual channel outputs from the receiver are
+routed as follows: vc0 to the IPU1 CSI0 mux, vc1 directly to IPU1 CSI1,
+vc2 directly to IPU2 CSI0, and vc3 to the IPU2 CSI1 mux. The OV5640 is
+also connected to i2c bus 2 on the SabreLite, therefore the OV5642 and
+OV5640 must not share the same i2c slave address.
+
+The following basic example configures unprocessed video capture
+pipelines for both sensors. The OV5642 is routed to ipu1_csi0, and
+the OV5640, transmitting on MIPI CSI-2 virtual channel 1 (which is
+imx6-mipi-csi2 pad 2), is routed to ipu1_csi1. Both sensors are
+configured to output 640x480, and the OV5642 outputs YUYV2X8, the
+OV5640 UYVY2X8:
+
+.. code-block:: none
+
+   # Setup links for OV5642
+   media-ctl -l "'ov5642 1-0042':0 -> 'ipu1_csi0_mux':1[1]"
+   media-ctl -l "'ipu1_csi0_mux':2 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':2 -> 'ipu1_csi0 capture':0[1]"
+   # Setup links for OV5640
+   media-ctl -l "'ov5640 1-0040':0 -> 'imx6-mipi-csi2':0[1]"
+   media-ctl -l "'imx6-mipi-csi2':2 -> 'ipu1_csi1':0[1]"
+   media-ctl -l "'ipu1_csi1':2 -> 'ipu1_csi1 capture':0[1]"
+   # Configure pads for OV5642 pipeline
+   media-ctl -V "'ov5642 1-0042':0 [fmt:YUYV2X8/640x480 field:none]"
+   media-ctl -V "'ipu1_csi0_mux':2 [fmt:YUYV2X8/640x480 field:none]"
+   media-ctl -V "'ipu1_csi0':2 [fmt:AYUV32/640x480 field:none]"
+   # Configure pads for OV5640 pipeline
+   media-ctl -V "'ov5640 1-0040':0 [fmt:UYVY2X8/640x480 field:none]"
+   media-ctl -V "'imx6-mipi-csi2':2 [fmt:UYVY2X8/640x480 field:none]"
+   media-ctl -V "'ipu1_csi1':2 [fmt:AYUV32/640x480 field:none]"
+
+Streaming can then begin independently on the capture device nodes
+"ipu1_csi0 capture" and "ipu1_csi1 capture". The v4l2-ctl tool can
+be used to select any supported YUV pixelformat on the capture device
+nodes, including planar.
+
+i.MX6Q SabreAuto with ADV7180 decoder
+-------------------------------------
+
+On the i.MX6Q SabreAuto, an on-board ADV7180 SD decoder is connected to the
+parallel bus input on the internal video mux to IPU1 CSI0.
+
+The following example configures a pipeline to capture from the ADV7180
+video decoder, assuming NTSC 720x480 input signals, using simple
+interweave (unconverted and without motion compensation). The adv7180
+must output sequential or alternating fields (field type 'seq-bt' for
+NTSC, or 'alternate'):
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'adv7180 3-0021':0 -> 'ipu1_csi0_mux':1[1]"
+   media-ctl -l "'ipu1_csi0_mux':2 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':2 -> 'ipu1_csi0 capture':0[1]"
+   # Configure pads
+   media-ctl -V "'adv7180 3-0021':0 [fmt:UYVY2X8/720x480 field:seq-bt]"
+   media-ctl -V "'ipu1_csi0_mux':2 [fmt:UYVY2X8/720x480]"
+   media-ctl -V "'ipu1_csi0':2 [fmt:AYUV32/720x480]"
+   # Configure "ipu1_csi0 capture" interface (assumed at /dev/video4)
+   v4l2-ctl -d4 --set-fmt-video=field=interlaced_bt
+
+Streaming can then begin on /dev/video4. The v4l2-ctl tool can also be
+used to select any supported YUV pixelformat on /dev/video4.
+
+This example configures a pipeline to capture from the ADV7180
+video decoder, assuming PAL 720x576 input signals, with Motion
+Compensated de-interlacing. The adv7180 must output sequential or
+alternating fields (field type 'seq-tb' for PAL, or 'alternate').
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'adv7180 3-0021':0 -> 'ipu1_csi0_mux':1[1]"
+   media-ctl -l "'ipu1_csi0_mux':2 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':1 -> 'ipu1_vdic':0[1]"
+   media-ctl -l "'ipu1_vdic':2 -> 'ipu1_ic_prp':0[1]"
+   media-ctl -l "'ipu1_ic_prp':2 -> 'ipu1_ic_prpvf':0[1]"
+   media-ctl -l "'ipu1_ic_prpvf':1 -> 'ipu1_ic_prpvf capture':0[1]"
+   # Configure pads
+   media-ctl -V "'adv7180 3-0021':0 [fmt:UYVY2X8/720x576 field:seq-tb]"
+   media-ctl -V "'ipu1_csi0_mux':2 [fmt:UYVY2X8/720x576]"
+   media-ctl -V "'ipu1_csi0':1 [fmt:AYUV32/720x576]"
+   media-ctl -V "'ipu1_vdic':2 [fmt:AYUV32/720x576 field:none]"
+   media-ctl -V "'ipu1_ic_prp':2 [fmt:AYUV32/720x576 field:none]"
+   media-ctl -V "'ipu1_ic_prpvf':1 [fmt:AYUV32/720x576 field:none]"
+   # Configure "ipu1_ic_prpvf capture" interface (assumed at /dev/video2)
+   v4l2-ctl -d2 --set-fmt-video=field=none
+
+Streaming can then begin on /dev/video2. The v4l2-ctl tool can also be
+used to select any supported YUV pixelformat on /dev/video2.
+
+This platform accepts Composite Video analog inputs to the ADV7180 on
+Ain1 (connector J42).
+
+i.MX6DL SabreAuto with ADV7180 decoder
+--------------------------------------
+
+On the i.MX6DL SabreAuto, an on-board ADV7180 SD decoder is connected to the
+parallel bus input on the internal video mux to IPU1 CSI0.
+
+The following example configures a pipeline to capture from the ADV7180
+video decoder, assuming NTSC 720x480 input signals, using simple
+interweave (unconverted and without motion compensation). The adv7180
+must output sequential or alternating fields (field type 'seq-bt' for
+NTSC, or 'alternate'):
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'adv7180 4-0021':0 -> 'ipu1_csi0_mux':4[1]"
+   media-ctl -l "'ipu1_csi0_mux':5 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':2 -> 'ipu1_csi0 capture':0[1]"
+   # Configure pads
+   media-ctl -V "'adv7180 4-0021':0 [fmt:UYVY2X8/720x480 field:seq-bt]"
+   media-ctl -V "'ipu1_csi0_mux':5 [fmt:UYVY2X8/720x480]"
+   media-ctl -V "'ipu1_csi0':2 [fmt:AYUV32/720x480]"
+   # Configure "ipu1_csi0 capture" interface (assumed at /dev/video0)
+   v4l2-ctl -d0 --set-fmt-video=field=interlaced_bt
+
+Streaming can then begin on /dev/video0. The v4l2-ctl tool can also be
+used to select any supported YUV pixelformat on /dev/video0.
+
+This example configures a pipeline to capture from the ADV7180
+video decoder, assuming PAL 720x576 input signals, with Motion
+Compensated de-interlacing. The adv7180 must output sequential or
+alternating fields (field type 'seq-tb' for PAL, or 'alternate').
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'adv7180 4-0021':0 -> 'ipu1_csi0_mux':4[1]"
+   media-ctl -l "'ipu1_csi0_mux':5 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':1 -> 'ipu1_vdic':0[1]"
+   media-ctl -l "'ipu1_vdic':2 -> 'ipu1_ic_prp':0[1]"
+   media-ctl -l "'ipu1_ic_prp':2 -> 'ipu1_ic_prpvf':0[1]"
+   media-ctl -l "'ipu1_ic_prpvf':1 -> 'ipu1_ic_prpvf capture':0[1]"
+   # Configure pads
+   media-ctl -V "'adv7180 4-0021':0 [fmt:UYVY2X8/720x576 field:seq-tb]"
+   media-ctl -V "'ipu1_csi0_mux':5 [fmt:UYVY2X8/720x576]"
+   media-ctl -V "'ipu1_csi0':1 [fmt:AYUV32/720x576]"
+   media-ctl -V "'ipu1_vdic':2 [fmt:AYUV32/720x576 field:none]"
+   media-ctl -V "'ipu1_ic_prp':2 [fmt:AYUV32/720x576 field:none]"
+   media-ctl -V "'ipu1_ic_prpvf':1 [fmt:AYUV32/720x576 field:none]"
+   # Configure "ipu1_ic_prpvf capture" interface (assumed at /dev/video2)
+   v4l2-ctl -d2 --set-fmt-video=field=none
+
+Streaming can then begin on /dev/video2. The v4l2-ctl tool can also be
+used to select any supported YUV pixelformat on /dev/video2.
+
+This platform accepts Composite Video analog inputs to the ADV7180 on
+Ain1 (connector J42).
+
+i.MX6Q SabreSD with MIPI CSI-2 OV5640
+-------------------------------------
+
+Similarly to i.MX6Q SabreLite, the i.MX6Q SabreSD supports a parallel
+interface OV5642 module on IPU1 CSI0, and a MIPI CSI-2 OV5640
+module. The OV5642 connects to i2c bus 1 and the OV5640 to i2c bus 2.
+
+The device tree for SabreSD includes OF graphs for both the parallel
+OV5642 and the MIPI CSI-2 OV5640, but as of this writing only the MIPI
+CSI-2 OV5640 has been tested, so the OV5642 node is currently disabled.
+The OV5640 module connects to MIPI connector J5. The NXP part number
+for the OV5640 module that connects to the SabreSD board is H120729.
+
+The following example configures unprocessed video capture pipeline to
+capture from the OV5640, transmitting on MIPI CSI-2 virtual channel 0:
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'ov5640 1-003c':0 -> 'imx6-mipi-csi2':0[1]"
+   media-ctl -l "'imx6-mipi-csi2':1 -> 'ipu1_csi0_mux':0[1]"
+   media-ctl -l "'ipu1_csi0_mux':2 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':2 -> 'ipu1_csi0 capture':0[1]"
+   # Configure pads
+   media-ctl -V "'ov5640 1-003c':0 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'imx6-mipi-csi2':1 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'ipu1_csi0_mux':0 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'ipu1_csi0':0 [fmt:AYUV32/640x480]"
+
+Streaming can then begin on "ipu1_csi0 capture" node. The v4l2-ctl
+tool can be used to select any supported pixelformat on the capture
+device node.
+
+To determine what is the /dev/video node correspondent to
+"ipu1_csi0 capture":
+
+.. code-block:: none
+
+   media-ctl -e "ipu1_csi0 capture"
+   /dev/video0
+
+/dev/video0 is the streaming element in this case.
+
+Starting the streaming via v4l2-ctl:
+
+.. code-block:: none
+
+   v4l2-ctl --stream-mmap -d /dev/video0
+
+Starting the streaming via Gstreamer and sending the content to the display:
+
+.. code-block:: none
+
+   gst-launch-1.0 v4l2src device=/dev/video0 ! kmssink
+
+The following example configures a direct conversion pipeline to capture
+from the OV5640, transmitting on MIPI CSI-2 virtual channel 0. It also
+shows colorspace conversion and scaling at IC output.
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'ov5640 1-003c':0 -> 'imx6-mipi-csi2':0[1]"
+   media-ctl -l "'imx6-mipi-csi2':1 -> 'ipu1_csi0_mux':0[1]"
+   media-ctl -l "'ipu1_csi0_mux':2 -> 'ipu1_csi0':0[1]"
+   media-ctl -l "'ipu1_csi0':1 -> 'ipu1_ic_prp':0[1]"
+   media-ctl -l "'ipu1_ic_prp':1 -> 'ipu1_ic_prpenc':0[1]"
+   media-ctl -l "'ipu1_ic_prpenc':1 -> 'ipu1_ic_prpenc capture':0[1]"
+   # Configure pads
+   media-ctl -V "'ov5640 1-003c':0 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'imx6-mipi-csi2':1 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'ipu1_csi0_mux':2 [fmt:UYVY2X8/640x480]"
+   media-ctl -V "'ipu1_csi0':1 [fmt:AYUV32/640x480]"
+   media-ctl -V "'ipu1_ic_prp':1 [fmt:AYUV32/640x480]"
+   media-ctl -V "'ipu1_ic_prpenc':1 [fmt:ARGB8888_1X32/800x600]"
+   # Set a format at the capture interface
+   v4l2-ctl -d /dev/video1 --set-fmt-video=pixelformat=RGB3
+
+Streaming can then begin on "ipu1_ic_prpenc capture" node.
+
+To determine what is the /dev/video node correspondent to
+"ipu1_ic_prpenc capture":
+
+.. code-block:: none
+
+   media-ctl -e "ipu1_ic_prpenc capture"
+   /dev/video1
+
+
+/dev/video1 is the streaming element in this case.
+
+Starting the streaming via v4l2-ctl:
+
+.. code-block:: none
+
+   v4l2-ctl --stream-mmap -d /dev/video1
+
+Starting the streaming via Gstreamer and sending the content to the display:
+
+.. code-block:: none
+
+   gst-launch-1.0 v4l2src device=/dev/video1 ! kmssink
+
+Known Issues
+------------
+
+1. When using 90 or 270 degree rotation control at capture resolutions
+   near the IC resizer limit of 1024x1024, and combined with planar
+   pixel formats (YUV420, YUV422p), frame capture will often fail with
+   no end-of-frame interrupts from the IDMAC channel. To work around
+   this, use lower resolution and/or packed formats (YUYV, RGB3, etc.)
+   when 90 or 270 rotations are needed.
+
+
+File list
+---------
+
+drivers/staging/media/imx/
+include/media/imx.h
+include/linux/imx-media.h
+
+References
+----------
+
+.. [#f1] http://www.nxp.com/assets/documents/data/en/reference-manuals/IMX6DQRM.pdf
+.. [#f2] http://www.nxp.com/assets/documents/data/en/reference-manuals/IMX6SDLRM.pdf
+
+
+Authors
+-------
+
+- Steve Longerbeam <steve_longerbeam@mentor.com>
+- Philipp Zabel <kernel@pengutronix.de>
+- Russell King <linux@armlinux.org.uk>
+
+Copyright (C) 2012-2017 Mentor Graphics Inc.
diff --git a/Documentation/admin-guide/media/imx6q-sabreauto.dot b/Documentation/admin-guide/media/imx6q-sabreauto.dot
new file mode 100644
index 000000000..bd6cf0b35
--- /dev/null
+++ b/Documentation/admin-guide/media/imx6q-sabreauto.dot
@@ -0,0 +1,51 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | ipu1_csi0\n/dev/v4l-subdev0 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port2 -> n00000005 [style=dashed]
+	n00000001:port1 -> n0000000f:port0 [style=dashed]
+	n00000001:port1 -> n0000000b:port0 [style=dashed]
+	n00000005 [label="ipu1_csi0 capture\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000000b [label="{{<port0> 0 | <port1> 1} | ipu1_vdic\n/dev/v4l-subdev1 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000b:port2 -> n0000000f:port0 [style=dashed]
+	n0000000f [label="{{<port0> 0} | ipu1_ic_prp\n/dev/v4l-subdev2 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000f:port1 -> n00000013:port0 [style=dashed]
+	n0000000f:port2 -> n0000001c:port0 [style=dashed]
+	n00000013 [label="{{<port0> 0} | ipu1_ic_prpenc\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000013:port1 -> n00000016 [style=dashed]
+	n00000016 [label="ipu1_ic_prpenc capture\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n0000001c [label="{{<port0> 0} | ipu1_ic_prpvf\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001c:port1 -> n0000001f [style=dashed]
+	n0000001f [label="ipu1_ic_prpvf capture\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n0000002f [label="{{<port0> 0} | ipu1_csi1\n/dev/v4l-subdev5 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000002f:port2 -> n00000033 [style=dashed]
+	n0000002f:port1 -> n0000000f:port0 [style=dashed]
+	n0000002f:port1 -> n0000000b:port0 [style=dashed]
+	n00000033 [label="ipu1_csi1 capture\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n0000003d [label="{{<port0> 0} | ipu2_csi0\n/dev/v4l-subdev6 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003d:port2 -> n00000041 [style=dashed]
+	n0000003d:port1 -> n0000004b:port0 [style=dashed]
+	n0000003d:port1 -> n00000047:port0 [style=dashed]
+	n00000041 [label="ipu2_csi0 capture\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n00000047 [label="{{<port0> 0 | <port1> 1} | ipu2_vdic\n/dev/v4l-subdev7 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000047:port2 -> n0000004b:port0 [style=dashed]
+	n0000004b [label="{{<port0> 0} | ipu2_ic_prp\n/dev/v4l-subdev8 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000004b:port1 -> n0000004f:port0 [style=dashed]
+	n0000004b:port2 -> n00000058:port0 [style=dashed]
+	n0000004f [label="{{<port0> 0} | ipu2_ic_prpenc\n/dev/v4l-subdev9 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000004f:port1 -> n00000052 [style=dashed]
+	n00000052 [label="ipu2_ic_prpenc capture\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+	n00000058 [label="{{<port0> 0} | ipu2_ic_prpvf\n/dev/v4l-subdev10 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000058:port1 -> n0000005b [style=dashed]
+	n0000005b [label="ipu2_ic_prpvf capture\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+	n0000006b [label="{{<port0> 0} | ipu2_csi1\n/dev/v4l-subdev11 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000006b:port2 -> n0000006f [style=dashed]
+	n0000006b:port1 -> n0000004b:port0 [style=dashed]
+	n0000006b:port1 -> n00000047:port0 [style=dashed]
+	n0000006f [label="ipu2_csi1 capture\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+	n00000079 [label="{{<port0> 0 | <port1> 1} | ipu1_csi0_mux\n/dev/v4l-subdev12 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000079:port2 -> n00000001:port0 [style=dashed]
+	n0000007d [label="{{<port0> 0 | <port1> 1} | ipu2_csi1_mux\n/dev/v4l-subdev13 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000007d:port2 -> n0000006b:port0 [style=dashed]
+	n00000081 [label="{{} | adv7180 3-0021\n/dev/v4l-subdev14 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000081:port0 -> n00000079:port1 [style=dashed]
+}
diff --git a/Documentation/admin-guide/media/imx6q-sabresd.dot b/Documentation/admin-guide/media/imx6q-sabresd.dot
new file mode 100644
index 000000000..7d56cafa1
--- /dev/null
+++ b/Documentation/admin-guide/media/imx6q-sabresd.dot
@@ -0,0 +1,56 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | ipu1_csi0\n/dev/v4l-subdev0 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port2 -> n00000005 [style=dashed]
+	n00000001:port1 -> n0000000f:port0 [style=dashed]
+	n00000001:port1 -> n0000000b:port0 [style=dashed]
+	n00000005 [label="ipu1_csi0 capture\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000000b [label="{{<port0> 0 | <port1> 1} | ipu1_vdic\n/dev/v4l-subdev1 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000b:port2 -> n0000000f:port0 [style=dashed]
+	n0000000f [label="{{<port0> 0} | ipu1_ic_prp\n/dev/v4l-subdev2 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000f:port1 -> n00000013:port0 [style=dashed]
+	n0000000f:port2 -> n0000001c:port0 [style=dashed]
+	n00000013 [label="{{<port0> 0} | ipu1_ic_prpenc\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000013:port1 -> n00000016 [style=dashed]
+	n00000016 [label="ipu1_ic_prpenc capture\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n0000001c [label="{{<port0> 0} | ipu1_ic_prpvf\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001c:port1 -> n0000001f [style=dashed]
+	n0000001f [label="ipu1_ic_prpvf capture\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n0000002f [label="{{<port0> 0} | ipu1_csi1\n/dev/v4l-subdev5 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000002f:port2 -> n00000033 [style=dashed]
+	n0000002f:port1 -> n0000000f:port0 [style=dashed]
+	n0000002f:port1 -> n0000000b:port0 [style=dashed]
+	n00000033 [label="ipu1_csi1 capture\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n0000003d [label="{{<port0> 0} | ipu2_csi0\n/dev/v4l-subdev6 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003d:port2 -> n00000041 [style=dashed]
+	n0000003d:port1 -> n0000004b:port0 [style=dashed]
+	n0000003d:port1 -> n00000047:port0 [style=dashed]
+	n00000041 [label="ipu2_csi0 capture\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n00000047 [label="{{<port0> 0 | <port1> 1} | ipu2_vdic\n/dev/v4l-subdev7 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000047:port2 -> n0000004b:port0 [style=dashed]
+	n0000004b [label="{{<port0> 0} | ipu2_ic_prp\n/dev/v4l-subdev8 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000004b:port1 -> n0000004f:port0 [style=dashed]
+	n0000004b:port2 -> n00000058:port0 [style=dashed]
+	n0000004f [label="{{<port0> 0} | ipu2_ic_prpenc\n/dev/v4l-subdev9 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000004f:port1 -> n00000052 [style=dashed]
+	n00000052 [label="ipu2_ic_prpenc capture\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+	n00000058 [label="{{<port0> 0} | ipu2_ic_prpvf\n/dev/v4l-subdev10 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000058:port1 -> n0000005b [style=dashed]
+	n0000005b [label="ipu2_ic_prpvf capture\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+	n0000006b [label="{{<port0> 0} | ipu2_csi1\n/dev/v4l-subdev11 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000006b:port2 -> n0000006f [style=dashed]
+	n0000006b:port1 -> n0000004b:port0 [style=dashed]
+	n0000006b:port1 -> n00000047:port0 [style=dashed]
+	n0000006f [label="ipu2_csi1 capture\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+	n00000079 [label="{{<port0> 0} | imx6-mipi-csi2\n/dev/v4l-subdev12 | {<port1> 1 | <port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000079:port2 -> n0000002f:port0 [style=dashed]
+	n00000079:port3 -> n0000003d:port0 [style=dashed]
+	n00000079:port1 -> n0000007f:port0 [style=dashed]
+	n00000079:port4 -> n00000083:port0 [style=dashed]
+	n0000007f [label="{{<port0> 0 | <port1> 1} | ipu1_csi0_mux\n/dev/v4l-subdev13 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000007f:port2 -> n00000001:port0 [style=dashed]
+	n00000083 [label="{{<port0> 0 | <port1> 1} | ipu2_csi1_mux\n/dev/v4l-subdev14 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000083:port2 -> n0000006b:port0 [style=dashed]
+	n00000087 [label="{{} | ov5640 1-003c\n/dev/v4l-subdev15 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000087:port0 -> n00000079:port0 [style=dashed]
+}
diff --git a/Documentation/admin-guide/media/imx7.rst b/Documentation/admin-guide/media/imx7.rst
new file mode 100644
index 000000000..2fa27718f
--- /dev/null
+++ b/Documentation/admin-guide/media/imx7.rst
@@ -0,0 +1,221 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+i.MX7 Video Capture Driver
+==========================
+
+Introduction
+------------
+
+The i.MX7 contrary to the i.MX5/6 family does not contain an Image Processing
+Unit (IPU); because of that the capabilities to perform operations or
+manipulation of the capture frames are less feature rich.
+
+For image capture the i.MX7 has three units:
+- CMOS Sensor Interface (CSI)
+- Video Multiplexer
+- MIPI CSI-2 Receiver
+
+.. code-block:: none
+
+   MIPI Camera Input ---> MIPI CSI-2 --- > |\
+                                           | \
+                                           |  \
+                                           | M |
+                                           | U | ------>  CSI ---> Capture
+                                           | X |
+                                           |  /
+   Parallel Camera Input ----------------> | /
+                                           |/
+
+For additional information, please refer to the latest versions of the i.MX7
+reference manual [#f1]_.
+
+Entities
+--------
+
+imx-mipi-csi2
+--------------
+
+This is the MIPI CSI-2 receiver entity. It has one sink pad to receive the pixel
+data from MIPI CSI-2 camera sensor. It has one source pad, corresponding to the
+virtual channel 0. This module is compliant to previous version of Samsung
+D-phy, and supports two D-PHY Rx Data lanes.
+
+csi-mux
+-------
+
+This is the video multiplexer. It has two sink pads to select from either camera
+sensor with a parallel interface or from MIPI CSI-2 virtual channel 0.  It has
+a single source pad that routes to the CSI.
+
+csi
+---
+
+The CSI enables the chip to connect directly to external CMOS image sensor. CSI
+can interface directly with Parallel and MIPI CSI-2 buses. It has 256 x 64 FIFO
+to store received image pixel data and embedded DMA controllers to transfer data
+from the FIFO through AHB bus.
+
+This entity has one sink pad that receives from the csi-mux entity and a single
+source pad that routes video frames directly to memory buffers. This pad is
+routed to a capture device node.
+
+Usage Notes
+-----------
+
+To aid in configuration and for backward compatibility with V4L2 applications
+that access controls only from video device nodes, the capture device interfaces
+inherit controls from the active entities in the current pipeline, so controls
+can be accessed either directly from the subdev or from the active capture
+device interface. For example, the sensor controls are available either from the
+sensor subdevs or from the active capture device.
+
+Warp7 with OV2680
+-----------------
+
+On this platform an OV2680 MIPI CSI-2 module is connected to the internal MIPI
+CSI-2 receiver. The following example configures a video capture pipeline with
+an output of 800x600, and BGGR 10 bit bayer format:
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'ov2680 1-0036':0 -> 'imx7-mipi-csis.0':0[1]"
+   media-ctl -l "'imx7-mipi-csis.0':1 -> 'csi-mux':1[1]"
+   media-ctl -l "'csi-mux':2 -> 'csi':0[1]"
+   media-ctl -l "'csi':1 -> 'csi capture':0[1]"
+
+   # Configure pads for pipeline
+   media-ctl -V "'ov2680 1-0036':0 [fmt:SBGGR10_1X10/800x600 field:none]"
+   media-ctl -V "'csi-mux':1 [fmt:SBGGR10_1X10/800x600 field:none]"
+   media-ctl -V "'csi-mux':2 [fmt:SBGGR10_1X10/800x600 field:none]"
+   media-ctl -V "'imx7-mipi-csis.0':0 [fmt:SBGGR10_1X10/800x600 field:none]"
+   media-ctl -V "'csi':0 [fmt:SBGGR10_1X10/800x600 field:none]"
+
+After this streaming can start. The v4l2-ctl tool can be used to select any of
+the resolutions supported by the sensor.
+
+.. code-block:: none
+
+	# media-ctl -p
+	Media controller API version 5.2.0
+
+	Media device information
+	------------------------
+	driver          imx7-csi
+	model           imx-media
+	serial
+	bus info
+	hw revision     0x0
+	driver version  5.2.0
+
+	Device topology
+	- entity 1: csi (2 pads, 2 links)
+	            type V4L2 subdev subtype Unknown flags 0
+	            device node name /dev/v4l-subdev0
+	        pad0: Sink
+	                [fmt:SBGGR10_1X10/800x600 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
+	                <- "csi-mux":2 [ENABLED]
+	        pad1: Source
+	                [fmt:SBGGR10_1X10/800x600 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
+	                -> "csi capture":0 [ENABLED]
+
+	- entity 4: csi capture (1 pad, 1 link)
+	            type Node subtype V4L flags 0
+	            device node name /dev/video0
+	        pad0: Sink
+	                <- "csi":1 [ENABLED]
+
+	- entity 10: csi-mux (3 pads, 2 links)
+	             type V4L2 subdev subtype Unknown flags 0
+	             device node name /dev/v4l-subdev1
+	        pad0: Sink
+	                [fmt:Y8_1X8/1x1 field:none]
+	        pad1: Sink
+	               [fmt:SBGGR10_1X10/800x600 field:none]
+	                <- "imx7-mipi-csis.0":1 [ENABLED]
+	        pad2: Source
+	                [fmt:SBGGR10_1X10/800x600 field:none]
+	                -> "csi":0 [ENABLED]
+
+	- entity 14: imx7-mipi-csis.0 (2 pads, 2 links)
+	             type V4L2 subdev subtype Unknown flags 0
+	             device node name /dev/v4l-subdev2
+	        pad0: Sink
+	                [fmt:SBGGR10_1X10/800x600 field:none]
+	                <- "ov2680 1-0036":0 [ENABLED]
+	        pad1: Source
+	                [fmt:SBGGR10_1X10/800x600 field:none]
+	                -> "csi-mux":1 [ENABLED]
+
+	- entity 17: ov2680 1-0036 (1 pad, 1 link)
+	             type V4L2 subdev subtype Sensor flags 0
+	             device node name /dev/v4l-subdev3
+	        pad0: Source
+	                [fmt:SBGGR10_1X10/800x600@1/30 field:none colorspace:srgb]
+	                -> "imx7-mipi-csis.0":0 [ENABLED]
+
+i.MX6ULL-EVK with OV5640
+------------------------
+
+On this platform a parallel OV5640 sensor is connected to the CSI port.
+The following example configures a video capture pipeline with an output
+of 640x480 and UYVY8_2X8 format:
+
+.. code-block:: none
+
+   # Setup links
+   media-ctl -l "'ov5640 1-003c':0 -> 'csi':0[1]"
+   media-ctl -l "'csi':1 -> 'csi capture':0[1]"
+
+   # Configure pads for pipeline
+   media-ctl -v -V "'ov5640 1-003c':0 [fmt:UYVY8_2X8/640x480 field:none]"
+
+After this streaming can start:
+
+.. code-block:: none
+
+   gst-launch-1.0 -v v4l2src device=/dev/video1 ! video/x-raw,format=UYVY,width=640,height=480 ! v4l2convert ! fbdevsink
+
+.. code-block:: none
+
+	# media-ctl -p
+	Media controller API version 5.14.0
+
+	Media device information
+	------------------------
+	driver          imx7-csi
+	model           imx-media
+	serial
+	bus info
+	hw revision     0x0
+	driver version  5.14.0
+
+	Device topology
+	- entity 1: csi (2 pads, 2 links)
+	            type V4L2 subdev subtype Unknown flags 0
+	            device node name /dev/v4l-subdev0
+	        pad0: Sink
+	                [fmt:UYVY8_2X8/640x480 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
+	                <- "ov5640 1-003c":0 [ENABLED,IMMUTABLE]
+	        pad1: Source
+	                [fmt:UYVY8_2X8/640x480 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
+	                -> "csi capture":0 [ENABLED,IMMUTABLE]
+
+	- entity 4: csi capture (1 pad, 1 link)
+	            type Node subtype V4L flags 0
+	            device node name /dev/video1
+	        pad0: Sink
+	                <- "csi":1 [ENABLED,IMMUTABLE]
+
+	- entity 10: ov5640 1-003c (1 pad, 1 link)
+	             type V4L2 subdev subtype Sensor flags 0
+	             device node name /dev/v4l-subdev1
+	        pad0: Source
+	                [fmt:UYVY8_2X8/640x480@1/30 field:none colorspace:srgb xfer:srgb ycbcr:601 quantization:full-range]
+	                -> "csi":0 [ENABLED,IMMUTABLE]
+
+References
+----------
+
+.. [#f1] https://www.nxp.com/docs/en/reference-manual/IMX7SRM.pdf
diff --git a/Documentation/admin-guide/media/index.rst b/Documentation/admin-guide/media/index.rst
new file mode 100644
index 000000000..b11737ae6
--- /dev/null
+++ b/Documentation/admin-guide/media/index.rst
@@ -0,0 +1,61 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+====================================
+Media subsystem admin and user guide
+====================================
+
+This section contains usage information about media subsystem and
+its supported drivers.
+
+Please see:
+
+Documentation/userspace-api/media/index.rst
+
+  - for the userspace APIs used on media devices.
+
+Documentation/driver-api/media/index.rst
+
+  - for driver development information and Kernel APIs used by
+    media devices;
+
+Documentation/process/debugging/media_specific_debugging_guide.rst
+
+  - for advice about essential tools and techniques to debug drivers on this
+    subsystem
+
+.. toctree::
+	:caption: Table of Contents
+	:maxdepth: 2
+	:numbered:
+
+	intro
+	building
+
+	remote-controller
+
+	cec
+
+	dvb
+
+	cardlist
+
+	v4l-drivers
+	dvb-drivers
+
+**Copyright** |copy| 1999-2020 : LinuxTV Developers
+
+::
+
+  This documentation is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by the Free
+  Software Foundation; either version 2 of the License, or (at your option) any
+  later version.
+
+  This program is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+  more details.
+
+  For more details see the file COPYING in the source distribution of Linux.
diff --git a/Documentation/admin-guide/media/intro.rst b/Documentation/admin-guide/media/intro.rst
new file mode 100644
index 000000000..fec8122f2
--- /dev/null
+++ b/Documentation/admin-guide/media/intro.rst
@@ -0,0 +1,27 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Introduction
+============
+
+The media subsystem consists on Linux support for several different types
+of devices:
+
+- Audio and video grabbers;
+- PC and Laptop Cameras;
+- Complex cameras found on Embedded hardware;
+- Analog and digital TV;
+- HDMI Customer Electronics Control (CEC);
+- Multi-touch input devices;
+- Remote Controllers;
+- Media encoders and decoders.
+
+Due to the diversity of devices, the subsystem provides several different
+APIs:
+
+- Remote Controller API;
+- HDMI CEC API;
+- Video4Linux API;
+- Media controller API;
+- Video4Linux Request API (experimental);
+- Digital TV API (also known as DVB API).
diff --git a/Documentation/admin-guide/media/ipu3.rst b/Documentation/admin-guide/media/ipu3.rst
new file mode 100644
index 000000000..9c1909429
--- /dev/null
+++ b/Documentation/admin-guide/media/ipu3.rst
@@ -0,0 +1,596 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+===============================================================
+Intel Image Processing Unit 3 (IPU3) Imaging Unit (ImgU) driver
+===============================================================
+
+Copyright |copy| 2018 Intel Corporation
+
+Introduction
+============
+
+This file documents the Intel IPU3 (3rd generation Image Processing Unit)
+Imaging Unit drivers located under drivers/media/pci/intel/ipu3 (CIO2) as well
+as under drivers/staging/media/ipu3 (ImgU).
+
+The Intel IPU3 found in certain Kaby Lake (as well as certain Sky Lake)
+platforms (U/Y processor lines) is made up of two parts namely the Imaging Unit
+(ImgU) and the CIO2 device (MIPI CSI2 receiver).
+
+The CIO2 device receives the raw Bayer data from the sensors and outputs the
+frames in a format that is specific to the IPU3 (for consumption by the IPU3
+ImgU). The CIO2 driver is available as drivers/media/pci/intel/ipu3/ipu3-cio2*
+and is enabled through the CONFIG_VIDEO_IPU3_CIO2 config option.
+
+The Imaging Unit (ImgU) is responsible for processing images captured
+by the IPU3 CIO2 device. The ImgU driver sources can be found under
+drivers/staging/media/ipu3 directory. The driver is enabled through the
+CONFIG_VIDEO_IPU3_IMGU config option.
+
+The two driver modules are named ipu3_csi2 and ipu3_imgu, respectively.
+
+The drivers has been tested on Kaby Lake platforms (U/Y processor lines).
+
+Both of the drivers implement V4L2, Media Controller and V4L2 sub-device
+interfaces. The IPU3 CIO2 driver supports camera sensors connected to the CIO2
+MIPI CSI-2 interfaces through V4L2 sub-device sensor drivers.
+
+CIO2
+====
+
+The CIO2 is represented as a single V4L2 subdev, which provides a V4L2 subdev
+interface to the user space. There is a video node for each CSI-2 receiver,
+with a single media controller interface for the entire device.
+
+The CIO2 contains four independent capture channel, each with its own MIPI CSI-2
+receiver and DMA engine. Each channel is modelled as a V4L2 sub-device exposed
+to userspace as a V4L2 sub-device node and has two pads:
+
+.. tabularcolumns:: |p{0.8cm}|p{4.0cm}|p{4.0cm}|
+
+.. flat-table::
+    :header-rows: 1
+
+    * - Pad
+      - Direction
+      - Purpose
+
+    * - 0
+      - sink
+      - MIPI CSI-2 input, connected to the sensor subdev
+
+    * - 1
+      - source
+      - Raw video capture, connected to the V4L2 video interface
+
+The V4L2 video interfaces model the DMA engines. They are exposed to userspace
+as V4L2 video device nodes.
+
+Capturing frames in raw Bayer format
+------------------------------------
+
+CIO2 MIPI CSI2 receiver is used to capture frames (in packed raw Bayer format)
+from the raw sensors connected to the CSI2 ports. The captured frames are used
+as input to the ImgU driver.
+
+Image processing using IPU3 ImgU requires tools such as raw2pnm [#f1]_, and
+yavta [#f2]_ due to the following unique requirements and / or features specific
+to IPU3.
+
+-- The IPU3 CSI2 receiver outputs the captured frames from the sensor in packed
+raw Bayer format that is specific to IPU3.
+
+-- Multiple video nodes have to be operated simultaneously.
+
+Let us take the example of ov5670 sensor connected to CSI2 port 0, for a
+2592x1944 image capture.
+
+Using the media controller APIs, the ov5670 sensor is configured to send
+frames in packed raw Bayer format to IPU3 CSI2 receiver.
+
+.. code-block:: none
+
+    # This example assumes /dev/media0 as the CIO2 media device
+    export MDEV=/dev/media0
+
+    # and that ov5670 sensor is connected to i2c bus 10 with address 0x36
+    export SDEV=$(media-ctl -d $MDEV -e "ov5670 10-0036")
+
+    # Establish the link for the media devices using media-ctl
+    media-ctl -d $MDEV -l "ov5670:0 -> ipu3-csi2 0:0[1]"
+
+    # Set the format for the media devices
+    media-ctl -d $MDEV -V "ov5670:0 [fmt:SGRBG10/2592x1944]"
+    media-ctl -d $MDEV -V "ipu3-csi2 0:0 [fmt:SGRBG10/2592x1944]"
+    media-ctl -d $MDEV -V "ipu3-csi2 0:1 [fmt:SGRBG10/2592x1944]"
+
+Once the media pipeline is configured, desired sensor specific settings
+(such as exposure and gain settings) can be set, using the yavta tool.
+
+e.g
+
+.. code-block:: none
+
+    yavta -w 0x009e0903 444 $SDEV
+    yavta -w 0x009e0913 1024 $SDEV
+    yavta -w 0x009e0911 2046 $SDEV
+
+Once the desired sensor settings are set, frame captures can be done as below.
+
+e.g
+
+.. code-block:: none
+
+    yavta --data-prefix -u -c10 -n5 -I -s2592x1944 --file=/tmp/frame-#.bin \
+          -f IPU3_SGRBG10 $(media-ctl -d $MDEV -e "ipu3-cio2 0")
+
+With the above command, 10 frames are captured at 2592x1944 resolution, with
+sGRBG10 format and output as IPU3_SGRBG10 format.
+
+The captured frames are available as /tmp/frame-#.bin files.
+
+ImgU
+====
+
+The ImgU is represented as two V4L2 subdevs, each of which provides a V4L2
+subdev interface to the user space.
+
+Each V4L2 subdev represents a pipe, which can support a maximum of 2 streams.
+This helps to support advanced camera features like Continuous View Finder (CVF)
+and Snapshot During Video(SDV).
+
+The ImgU contains two independent pipes, each modelled as a V4L2 sub-device
+exposed to userspace as a V4L2 sub-device node.
+
+Each pipe has two sink pads and three source pads for the following purpose:
+
+.. tabularcolumns:: |p{0.8cm}|p{4.0cm}|p{4.0cm}|
+
+.. flat-table::
+    :header-rows: 1
+
+    * - Pad
+      - Direction
+      - Purpose
+
+    * - 0
+      - sink
+      - Input raw video stream
+
+    * - 1
+      - sink
+      - Processing parameters
+
+    * - 2
+      - source
+      - Output processed video stream
+
+    * - 3
+      - source
+      - Output viewfinder video stream
+
+    * - 4
+      - source
+      - 3A statistics
+
+Each pad is connected to a corresponding V4L2 video interface, exposed to 
+userspace as a V4L2 video device node.
+
+Device operation
+----------------
+
+With ImgU, once the input video node ("ipu3-imgu 0/1":0, in
+<entity>:<pad-number> format) is queued with buffer (in packed raw Bayer
+format), ImgU starts processing the buffer and produces the video output in YUV
+format and statistics output on respective output nodes. The driver is expected
+to have buffers ready for all of parameter, output and statistics nodes, when
+input video node is queued with buffer.
+
+At a minimum, all of input, main output, 3A statistics and viewfinder
+video nodes should be enabled for IPU3 to start image processing.
+
+Each ImgU V4L2 subdev has the following set of video nodes.
+
+input, output and viewfinder video nodes
+----------------------------------------
+
+The frames (in packed raw Bayer format specific to the IPU3) received by the
+input video node is processed by the IPU3 Imaging Unit and are output to 2 video
+nodes, with each targeting a different purpose (main output and viewfinder
+output).
+
+Details onand the Bayer format specific to the IPU3 can be found in
+:ref:`v4l2-pix-fmt-ipu3-sbggr10`.
+
+The driver supports V4L2 Video Capture Interface as defined at :ref:`devices`.
+
+Only the multi-planar API is supported. More details can be found at
+:ref:`planar-apis`.
+
+Parameters video node
+---------------------
+
+The parameters video node receives the ImgU algorithm parameters that are used
+to configure how the ImgU algorithms process the image.
+
+Details on processing parameters specific to the IPU3 can be found in
+:ref:`v4l2-meta-fmt-params`.
+
+3A statistics video node
+------------------------
+
+3A statistics video node is used by the ImgU driver to output the 3A (auto
+focus, auto exposure and auto white balance) statistics for the frames that are
+being processed by the ImgU to user space applications. User space applications
+can use this statistics data to compute the desired algorithm parameters for
+the ImgU.
+
+Configuring the Intel IPU3
+==========================
+
+The IPU3 ImgU pipelines can be configured using the Media Controller, defined at
+:ref:`media_controller`.
+
+Running mode and firmware binary selection
+------------------------------------------
+
+ImgU works based on firmware, currently the ImgU firmware support run 2 pipes
+in time-sharing with single input frame data. Each pipe can run at certain mode
+- "VIDEO" or "STILL", "VIDEO" mode is commonly used for video frames capture,
+and "STILL" is used for still frame capture. However, you can also select
+"VIDEO" to capture still frames if you want to capture images with less system
+load and power. For "STILL" mode, ImgU will try to use smaller BDS factor and
+output larger bayer frame for further YUV processing than "VIDEO" mode to get
+high quality images. Besides, "STILL" mode need XNR3 to do noise reduction,
+hence "STILL" mode will need more power and memory bandwidth than "VIDEO" mode.
+TNR will be enabled in "VIDEO" mode and bypassed by "STILL" mode. ImgU is
+running at "VIDEO" mode by default, the user can use v4l2 control
+V4L2_CID_INTEL_IPU3_MODE (currently defined in
+drivers/staging/media/ipu3/include/uapi/intel-ipu3.h) to query and set the
+running mode. For user, there is no difference for buffer queueing between the
+"VIDEO" and "STILL" mode, mandatory input and main output node should be
+enabled and buffers need be queued, the statistics and the view-finder queues
+are optional.
+
+The firmware binary will be selected according to current running mode, such log
+"using binary if_to_osys_striped " or "using binary if_to_osys_primary_striped"
+could be observed if you enable the ImgU dynamic debug, the binary
+if_to_osys_striped is selected for "VIDEO" and the binary
+"if_to_osys_primary_striped" is selected for "STILL".
+
+
+Processing the image in raw Bayer format
+----------------------------------------
+
+Configuring ImgU V4L2 subdev for image processing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ImgU V4L2 subdevs have to be configured with media controller APIs to have
+all the video nodes setup correctly.
+
+Let us take "ipu3-imgu 0" subdev as an example.
+
+.. code-block:: none
+
+    media-ctl -d $MDEV -r
+    media-ctl -d $MDEV -l "ipu3-imgu 0 input":0 -> "ipu3-imgu 0":0[1]
+    media-ctl -d $MDEV -l "ipu3-imgu 0":2 -> "ipu3-imgu 0 output":0[1]
+    media-ctl -d $MDEV -l "ipu3-imgu 0":3 -> "ipu3-imgu 0 viewfinder":0[1]
+    media-ctl -d $MDEV -l "ipu3-imgu 0":4 -> "ipu3-imgu 0 3a stat":0[1]
+
+Also the pipe mode of the corresponding V4L2 subdev should be set as desired
+(e.g 0 for video mode or 1 for still mode) through the control id 0x009819a1 as
+below.
+
+.. code-block:: none
+
+    yavta -w "0x009819A1 1" /dev/v4l-subdev7
+
+Certain hardware blocks in ImgU pipeline can change the frame resolution by
+cropping or scaling, these hardware blocks include Input Feeder(IF), Bayer Down
+Scaler (BDS) and Geometric Distortion Correction (GDC).
+There is also a block which can change the frame resolution - YUV Scaler, it is
+only applicable to the secondary output.
+
+RAW Bayer frames go through these ImgU pipeline hardware blocks and the final
+processed image output to the DDR memory.
+
+.. kernel-figure::  ipu3_rcb.svg
+   :alt: ipu3 resolution blocks image
+
+   IPU3 resolution change hardware blocks
+
+**Input Feeder**
+
+Input Feeder gets the Bayer frame data from the sensor, it can enable cropping
+of lines and columns from the frame and then store pixels into device's internal
+pixel buffer which are ready to readout by following blocks.
+
+**Bayer Down Scaler**
+
+Bayer Down Scaler is capable of performing image scaling in Bayer domain, the
+downscale factor can be configured from 1X to 1/4X in each axis with
+configuration steps of 0.03125 (1/32).
+
+**Geometric Distortion Correction**
+
+Geometric Distortion Correction is used to perform correction of distortions
+and image filtering. It needs some extra filter and envelope padding pixels to
+work, so the input resolution of GDC should be larger than the output
+resolution.
+
+**YUV Scaler**
+
+YUV Scaler which similar with BDS, but it is mainly do image down scaling in
+YUV domain, it can support up to 1/12X down scaling, but it can not be applied
+to the main output.
+
+The ImgU V4L2 subdev has to be configured with the supported resolutions in all
+the above hardware blocks, for a given input resolution.
+For a given supported resolution for an input frame, the Input Feeder, Bayer
+Down Scaler and GDC blocks should be configured with the supported resolutions
+as each hardware block has its own alignment requirement.
+
+You must configure the output resolution of the hardware blocks smartly to meet
+the hardware requirement along with keeping the maximum field of view. The
+intermediate resolutions can be generated by specific tool -
+
+https://github.com/intel/intel-ipu3-pipecfg
+
+This tool can be used to generate intermediate resolutions. More information can
+be obtained by looking at the following IPU3 ImgU configuration table.
+
+https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master
+
+Under baseboard-poppy/media-libs/cros-camera-hal-configs-poppy/files/gcss
+directory, graph_settings_ov5670.xml can be used as an example.
+
+The following steps prepare the ImgU pipeline for the image processing.
+
+1. The ImgU V4L2 subdev data format should be set by using the
+VIDIOC_SUBDEV_S_FMT on pad 0, using the GDC width and height obtained above.
+
+2. The ImgU V4L2 subdev cropping should be set by using the
+VIDIOC_SUBDEV_S_SELECTION on pad 0, with V4L2_SEL_TGT_CROP as the target,
+using the input feeder height and width.
+
+3. The ImgU V4L2 subdev composing should be set by using the
+VIDIOC_SUBDEV_S_SELECTION on pad 0, with V4L2_SEL_TGT_COMPOSE as the target,
+using the BDS height and width.
+
+For the ov5670 example, for an input frame with a resolution of 2592x1944
+(which is input to the ImgU subdev pad 0), the corresponding resolutions
+for input feeder, BDS and GDC are 2592x1944, 2592x1944 and 2560x1920
+respectively.
+
+Once this is done, the received raw Bayer frames can be input to the ImgU
+V4L2 subdev as below, using the open source application v4l2n [#f1]_.
+
+For an image captured with 2592x1944 [#f4]_ resolution, with desired output
+resolution as 2560x1920 and viewfinder resolution as 2560x1920, the following
+v4l2n command can be used. This helps process the raw Bayer frames and produces
+the desired results for the main output image and the viewfinder output, in NV12
+format.
+
+.. code-block:: none
+
+    v4l2n --pipe=4 --load=/tmp/frame-#.bin --open=/dev/video4
+          --fmt=type:VIDEO_OUTPUT_MPLANE,width=2592,height=1944,pixelformat=0X47337069 \
+          --reqbufs=type:VIDEO_OUTPUT_MPLANE,count:1 --pipe=1 \
+          --output=/tmp/frames.out --open=/dev/video5 \
+          --fmt=type:VIDEO_CAPTURE_MPLANE,width=2560,height=1920,pixelformat=NV12 \
+          --reqbufs=type:VIDEO_CAPTURE_MPLANE,count:1 --pipe=2 \
+          --output=/tmp/frames.vf --open=/dev/video6 \
+          --fmt=type:VIDEO_CAPTURE_MPLANE,width=2560,height=1920,pixelformat=NV12 \
+          --reqbufs=type:VIDEO_CAPTURE_MPLANE,count:1 --pipe=3 --open=/dev/video7 \
+          --output=/tmp/frames.3A --fmt=type:META_CAPTURE,? \
+          --reqbufs=count:1,type:META_CAPTURE --pipe=1,2,3,4 --stream=5
+
+You can also use yavta [#f2]_ command to do same thing as above:
+
+.. code-block:: none
+
+    yavta --data-prefix -Bcapture-mplane -c10 -n5 -I -s2592x1944 \
+          --file=frame-#.out-f NV12 /dev/video5 & \
+    yavta --data-prefix -Bcapture-mplane -c10 -n5 -I -s2592x1944 \
+          --file=frame-#.vf -f NV12 /dev/video6 & \
+    yavta --data-prefix -Bmeta-capture -c10 -n5 -I \
+          --file=frame-#.3a /dev/video7 & \
+    yavta --data-prefix -Boutput-mplane -c10 -n5 -I -s2592x1944 \
+          --file=/tmp/frame-in.cio2 -f IPU3_SGRBG10 /dev/video4
+
+where /dev/video4, /dev/video5, /dev/video6 and /dev/video7 devices point to
+input, output, viewfinder and 3A statistics video nodes respectively.
+
+Converting the raw Bayer image into YUV domain
+----------------------------------------------
+
+The processed images after the above step, can be converted to YUV domain
+as below.
+
+Main output frames
+~~~~~~~~~~~~~~~~~~
+
+.. code-block:: none
+
+    raw2pnm -x2560 -y1920 -fNV12 /tmp/frames.out /tmp/frames.out.ppm
+
+where 2560x1920 is output resolution, NV12 is the video format, followed
+by input frame and output PNM file.
+
+Viewfinder output frames
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: none
+
+    raw2pnm -x2560 -y1920 -fNV12 /tmp/frames.vf /tmp/frames.vf.ppm
+
+where 2560x1920 is output resolution, NV12 is the video format, followed
+by input frame and output PNM file.
+
+Example user space code for IPU3
+================================
+
+User space code that configures and uses IPU3 is available here.
+
+https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/master/
+
+The source can be located under hal/intel directory.
+
+Overview of IPU3 pipeline
+=========================
+
+IPU3 pipeline has a number of image processing stages, each of which takes a
+set of parameters as input. The major stages of pipelines are shown here:
+
+.. kernel-render:: DOT
+   :alt: IPU3 ImgU Pipeline
+   :caption: IPU3 ImgU Pipeline Diagram
+
+   digraph "IPU3 ImgU" {
+       node [shape=box]
+       splines="ortho"
+       rankdir="LR"
+
+       a [label="Raw pixels"]
+       b [label="Bayer Downscaling"]
+       c [label="Optical Black Correction"]
+       d [label="Linearization"]
+       e [label="Lens Shading Correction"]
+       f [label="White Balance / Exposure / Focus Apply"]
+       g [label="Bayer Noise Reduction"]
+       h [label="ANR"]
+       i [label="Demosaicing"]
+       j [label="Color Correction Matrix"]
+       k [label="Gamma correction"]
+       l [label="Color Space Conversion"]
+       m [label="Chroma Down Scaling"]
+       n [label="Chromatic Noise Reduction"]
+       o [label="Total Color Correction"]
+       p [label="XNR3"]
+       q [label="TNR"]
+       r [label="DDR", style=filled, fillcolor=yellow, shape=cylinder]
+       s [label="YUV Downscaling"]
+       t [label="DDR", style=filled, fillcolor=yellow, shape=cylinder]
+
+       { rank=same; a -> b -> c -> d -> e -> f -> g -> h -> i }
+       { rank=same; j -> k -> l -> m -> n -> o -> p -> q -> s -> t}
+
+       a -> j [style=invis, weight=10]
+       i -> j
+       q -> r
+   }
+
+The table below presents a description of the above algorithms.
+
+======================== =======================================================
+Name			 Description
+======================== =======================================================
+Optical Black Correction Optical Black Correction block subtracts a pre-defined
+			 value from the respective pixel values to obtain better
+			 image quality.
+			 Defined in struct ipu3_uapi_obgrid_param.
+Linearization		 This algo block uses linearization parameters to
+			 address non-linearity sensor effects. The Lookup table
+			 table is defined in
+			 struct ipu3_uapi_isp_lin_vmem_params.
+SHD			 Lens shading correction is used to correct spatial
+			 non-uniformity of the pixel response due to optical
+			 lens shading. This is done by applying a different gain
+			 for each pixel. The gain, black level etc are
+			 configured in struct ipu3_uapi_shd_config_static.
+BNR			 Bayer noise reduction block removes image noise by
+			 applying a bilateral filter.
+			 See struct ipu3_uapi_bnr_static_config for details.
+ANR			 Advanced Noise Reduction is a block based algorithm
+			 that performs noise reduction in the Bayer domain. The
+			 convolution matrix etc can be found in
+			 struct ipu3_uapi_anr_config.
+DM			 Demosaicing converts raw sensor data in Bayer format
+			 into RGB (Red, Green, Blue) presentation. Then add
+			 outputs of estimation of Y channel for following stream
+			 processing by Firmware. The struct is defined as
+			 struct ipu3_uapi_dm_config.
+Color Correction	 Color Correction algo transforms sensor specific color
+			 space to the standard "sRGB" color space. This is done
+			 by applying 3x3 matrix defined in
+			 struct ipu3_uapi_ccm_mat_config.
+Gamma correction	 Gamma correction struct ipu3_uapi_gamma_config is a
+			 basic non-linear tone mapping correction that is
+			 applied per pixel for each pixel component.
+CSC			 Color space conversion transforms each pixel from the
+			 RGB primary presentation to YUV (Y: brightness,
+			 UV: Luminance) presentation. This is done by applying
+			 a 3x3 matrix defined in
+			 struct ipu3_uapi_csc_mat_config
+CDS			 Chroma down sampling
+			 After the CSC is performed, the Chroma Down Sampling
+			 is applied for a UV plane down sampling by a factor
+			 of 2 in each direction for YUV 4:2:0 using a 4x2
+			 configurable filter struct ipu3_uapi_cds_params.
+CHNR			 Chroma noise reduction
+			 This block processes only the chrominance pixels and
+			 performs noise reduction by cleaning the high
+			 frequency noise.
+			 See struct struct ipu3_uapi_yuvp1_chnr_config.
+TCC			 Total color correction as defined in struct
+			 struct ipu3_uapi_yuvp2_tcc_static_config.
+XNR3			 eXtreme Noise Reduction V3 is the third revision of
+			 noise reduction algorithm used to improve image
+			 quality. This removes the low frequency noise in the
+			 captured image. Two related structs are  being defined,
+			 struct ipu3_uapi_isp_xnr3_params for ISP data memory
+			 and struct ipu3_uapi_isp_xnr3_vmem_params for vector
+			 memory.
+TNR			 Temporal Noise Reduction block compares successive
+			 frames in time to remove anomalies / noise in pixel
+			 values. struct ipu3_uapi_isp_tnr3_vmem_params and
+			 struct ipu3_uapi_isp_tnr3_params are defined for ISP
+			 vector and data memory respectively.
+======================== =======================================================
+
+Other often encountered acronyms not listed in above table:
+
+	ACC
+		Accelerator cluster
+	AWB_FR
+		Auto white balance filter response statistics
+	BDS
+		Bayer downscaler parameters
+	CCM
+		Color correction matrix coefficients
+	IEFd
+		Image enhancement filter directed
+	Obgrid
+		Optical black level compensation
+	OSYS
+		Output system configuration
+	ROI
+		Region of interest
+	YDS
+		Y down sampling
+	YTM
+		Y-tone mapping
+
+A few stages of the pipeline will be executed by firmware running on the ISP
+processor, while many others will use a set of fixed hardware blocks also
+called accelerator cluster (ACC) to crunch pixel data and produce statistics.
+
+ACC parameters of individual algorithms, as defined by
+struct ipu3_uapi_acc_param, can be chosen to be applied by the user
+space through struct struct ipu3_uapi_flags embedded in
+struct ipu3_uapi_params structure. For parameters that are configured as
+not enabled by the user space, the corresponding structs are ignored by the
+driver, in which case the existing configuration of the algorithm will be
+preserved.
+
+References
+==========
+
+.. [#f1] https://github.com/intel/nvt
+
+.. [#f2] http://git.ideasonboard.org/yavta.git
+
+.. [#f4] ImgU limitation requires an additional 16x16 for all input resolutions
diff --git a/Documentation/admin-guide/media/ipu3_rcb.svg b/Documentation/admin-guide/media/ipu3_rcb.svg
new file mode 100644
index 000000000..d878421b4
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diff --git a/Documentation/admin-guide/media/ipu6-isys.rst b/Documentation/admin-guide/media/ipu6-isys.rst
new file mode 100644
index 000000000..d05086824
--- /dev/null
+++ b/Documentation/admin-guide/media/ipu6-isys.rst
@@ -0,0 +1,161 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+========================================================
+Intel Image Processing Unit 6 (IPU6) Input System driver
+========================================================
+
+Copyright |copy| 2023--2024 Intel Corporation
+
+Introduction
+============
+
+This file documents the Intel IPU6 (6th generation Image Processing Unit)
+Input System (MIPI CSI2 receiver) drivers located under
+drivers/media/pci/intel/ipu6.
+
+The Intel IPU6 can be found in certain Intel SoCs but not in all SKUs:
+
+* Tiger Lake
+* Jasper Lake
+* Alder Lake
+* Raptor Lake
+* Meteor Lake
+
+Intel IPU6 is made up of two components - Input System (ISYS) and Processing
+System (PSYS).
+
+The Input System mainly works as MIPI CSI-2 receiver which receives and
+processes the image data from the sensors and outputs the frames to memory.
+
+There are 2 driver modules - intel-ipu6 and intel-ipu6-isys. intel-ipu6 is an
+IPU6 common driver which does PCI configuration, firmware loading and parsing,
+firmware authentication, DMA mapping and IPU-MMU (internal Memory mapping Unit)
+configuration. intel_ipu6_isys implements V4L2, Media Controller and V4L2
+sub-device interfaces. The IPU6 ISYS driver supports camera sensors connected
+to the IPU6 ISYS through V4L2 sub-device sensor drivers.
+
+.. Note:: See Documentation/driver-api/media/drivers/ipu6.rst for more
+	  information about the IPU6 hardware.
+
+Input system driver
+===================
+
+The Input System driver mainly configures CSI-2 D-PHY, constructs the firmware
+stream configuration, sends commands to firmware, gets response from hardware
+and firmware and then returns buffers to user.  The ISYS is represented as
+several V4L2 sub-devices as well as video nodes.
+
+.. kernel-figure::  ipu6_isys_graph.svg
+   :alt: ipu6 isys media graph with multiple streams support
+
+   IPU6 ISYS media graph with multiple streams support
+
+The graph has been produced using the following command:
+
+.. code-block:: none
+
+   fdp -Gsplines=true -Tsvg < dot > dot.svg
+
+Capturing frames with IPU6 ISYS
+-------------------------------
+
+IPU6 ISYS is used to capture frames from the camera sensors connected to the
+CSI2 ports. The supported input formats of ISYS are listed in table below:
+
+.. tabularcolumns:: |p{0.8cm}|p{4.0cm}|p{4.0cm}|
+
+.. flat-table::
+    :header-rows: 1
+
+    * - IPU6 ISYS supported input formats
+
+    * - RGB565, RGB888
+
+    * - UYVY8, YUYV8
+
+    * - RAW8, RAW10, RAW12
+
+.. _ipu6_isys_capture_examples:
+
+Examples
+~~~~~~~~
+
+Here is an example of IPU6 ISYS raw capture on Dell XPS 9315 laptop. On this
+machine, ov01a10 sensor is connected to IPU ISYS CSI-2 port 2, which can
+generate images at sBGGR10 with resolution 1280x800.
+
+Using the media controller APIs, we can configure ov01a10 sensor by
+media-ctl [#f1]_ and yavta [#f2]_ to transmit frames to IPU6 ISYS.
+
+.. code-block:: none
+
+    # Example 1 capture frame from ov01a10 camera sensor
+    # This example assumes /dev/media0 as the IPU ISYS media device
+    export MDEV=/dev/media0
+
+    # Establish the link for the media devices using media-ctl
+    media-ctl -d $MDEV -l "\"ov01a10 3-0036\":0 -> \"Intel IPU6 CSI2 2\":0[1]"
+
+    # Set the format for the media devices
+    media-ctl -d $MDEV -V "ov01a10:0 [fmt:SBGGR10/1280x800]"
+    media-ctl -d $MDEV -V "Intel IPU6 CSI2 2:0 [fmt:SBGGR10/1280x800]"
+    media-ctl -d $MDEV -V "Intel IPU6 CSI2 2:1 [fmt:SBGGR10/1280x800]"
+
+Once the media pipeline is configured, desired sensor specific settings
+(such as exposure and gain settings) can be set, using the yavta tool.
+
+e.g
+
+.. code-block:: none
+
+    # and that ov01a10 sensor is connected to i2c bus 3 with address 0x36
+    export SDEV=$(media-ctl -d $MDEV -e "ov01a10 3-0036")
+
+    yavta -w 0x009e0903 400 $SDEV
+    yavta -w 0x009e0913 1000 $SDEV
+    yavta -w 0x009e0911 2000 $SDEV
+
+Once the desired sensor settings are set, frame captures can be done as below.
+
+e.g
+
+.. code-block:: none
+
+    yavta --data-prefix -u -c10 -n5 -I -s 1280x800 --file=/tmp/frame-#.bin \
+            -f SBGGR10 $(media-ctl -d $MDEV -e "Intel IPU6 ISYS Capture 0")
+
+With the above command, 10 frames are captured at 1280x800 resolution with
+sBGGR10 format. The captured frames are available as /tmp/frame-#.bin files.
+
+Here is another example of IPU6 ISYS RAW and metadata capture from camera
+sensor ov2740 on Lenovo X1 Yoga laptop.
+
+.. code-block:: none
+
+    media-ctl -l "\"ov2740 14-0036\":0 -> \"Intel IPU6 CSI2 1\":0[1]"
+    media-ctl -l "\"Intel IPU6 CSI2 1\":1 -> \"Intel IPU6 ISYS Capture 0\":0[1]"
+    media-ctl -l "\"Intel IPU6 CSI2 1\":2 -> \"Intel IPU6 ISYS Capture 1\":0[1]"
+
+    # set routing
+    media-ctl -R "\"Intel IPU6 CSI2 1\" [0/0->1/0[1],0/1->2/1[1]]"
+
+    media-ctl -V "\"Intel IPU6 CSI2 1\":0/0 [fmt:SGRBG10/1932x1092]"
+    media-ctl -V "\"Intel IPU6 CSI2 1\":0/1 [fmt:GENERIC_8/97x1]"
+    media-ctl -V "\"Intel IPU6 CSI2 1\":1/0 [fmt:SGRBG10/1932x1092]"
+    media-ctl -V "\"Intel IPU6 CSI2 1\":2/1 [fmt:GENERIC_8/97x1]"
+
+    CAPTURE_DEV=$(media-ctl -e "Intel IPU6 ISYS Capture 0")
+    ./yavta --data-prefix -c100 -n5 -I -s1932x1092 --file=/tmp/frame-#.bin \
+        -f SGRBG10 ${CAPTURE_DEV}
+
+    CAPTURE_META=$(media-ctl -e "Intel IPU6 ISYS Capture 1")
+    ./yavta --data-prefix -c100 -n5 -I -s97x1 -B meta-capture \
+        --file=/tmp/meta-#.bin -f GENERIC_8 ${CAPTURE_META}
+
+References
+==========
+
+.. [#f1] https://git.ideasonboard.org/media-ctl.git
+.. [#f2] https://git.ideasonboard.org/yavta.git
diff --git a/Documentation/admin-guide/media/ipu6_isys_graph.svg b/Documentation/admin-guide/media/ipu6_isys_graph.svg
new file mode 100644
index 000000000..c8539ef32
--- /dev/null
+++ b/Documentation/admin-guide/media/ipu6_isys_graph.svg
@@ -0,0 +1,548 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
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+<text text-anchor="middle" x="1017.02" y="-660.27" font-family="Times,serif" font-size="14.00">/dev/video2</text>
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diff --git a/Documentation/admin-guide/media/ivtv-cardlist.rst b/Documentation/admin-guide/media/ivtv-cardlist.rst
new file mode 100644
index 000000000..0ffc3b71a
--- /dev/null
+++ b/Documentation/admin-guide/media/ivtv-cardlist.rst
@@ -0,0 +1,139 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+IVTV cards list
+===============
+
+.. tabularcolumns:: |p{1.4cm}|p{12.7cm}|p{3.4cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - Hauppauge WinTV PVR-250
+     - IVTV16 104d:813d
+
+   * - 1
+     - Hauppauge WinTV PVR-350
+     - IVTV16 104d:813d
+
+   * - 2
+     - Hauppauge WinTV PVR-150
+     - IVTV16 104d:813d
+
+   * - 3
+     - AVerMedia M179
+     - IVTV15 1461:a3cf, IVTV15 1461:a3ce
+
+   * - 4
+     - Yuan MPG600, Kuroutoshikou ITVC16-STVLP
+     - IVTV16 12ab:fff3, IVTV16 12ab:ffff
+
+   * - 5
+     - YUAN MPG160, Kuroutoshikou ITVC15-STVLP, I/O Data GV-M2TV/PCI
+     - IVTV15 10fc:40a0
+
+   * - 6
+     - Yuan PG600, Diamond PVR-550
+     - IVTV16 ff92:0070, IVTV16 ffab:0600
+
+   * - 7
+     - Adaptec VideOh! AVC-2410
+     - IVTV16 9005:0093
+
+   * - 8
+     - Adaptec VideOh! AVC-2010
+     - IVTV16 9005:0092
+
+   * - 9
+     - Nagase Transgear 5000TV
+     - IVTV16 1461:bfff
+
+   * - 10
+     - AOpen VA2000MAX-SNT6
+     - IVTV16 0000:ff5f
+
+   * - 11
+     - Yuan MPG600GR, Kuroutoshikou CX23416GYC-STVLP
+     - IVTV16 12ab:0600, IVTV16 fbab:0600, IVTV16 1154:0523
+
+   * - 12
+     - I/O Data GV-MVP/RX, GV-MVP/RX2W (dual tuner)
+     - IVTV16 10fc:d01e, IVTV16 10fc:d038, IVTV16 10fc:d039
+
+   * - 13
+     - I/O Data GV-MVP/RX2E
+     - IVTV16 10fc:d025
+
+   * - 14
+     - GotView PCI DVD
+     - IVTV16 12ab:0600
+
+   * - 15
+     - GotView PCI DVD2 Deluxe
+     - IVTV16 ffac:0600
+
+   * - 16
+     - Yuan MPC622
+     - IVTV16 ff01:d998
+
+   * - 17
+     - Digital Cowboy DCT-MTVP1
+     - IVTV16 1461:bfff
+
+   * - 18
+     - Yuan PG600-2, GotView PCI DVD Lite
+     - IVTV16 ffab:0600, IVTV16 ffad:0600
+
+   * - 19
+     - Club3D ZAP-TV1x01
+     - IVTV16 ffab:0600
+
+   * - 20
+     - AVerTV MCE 116 Plus
+     - IVTV16 1461:c439
+
+   * - 21
+     - ASUS Falcon2
+     - IVTV16 1043:4b66, IVTV16 1043:462e, IVTV16 1043:4b2e
+
+   * - 22
+     - AVerMedia PVR-150 Plus / AVerTV M113 Partsnic (Daewoo) Tuner
+     - IVTV16 1461:c034, IVTV16 1461:c035
+
+   * - 23
+     - AVerMedia EZMaker PCI Deluxe
+     - IVTV16 1461:c03f
+
+   * - 24
+     - AVerMedia M104
+     - IVTV16 1461:c136
+
+   * - 25
+     - Buffalo PC-MV5L/PCI
+     - IVTV16 1154:052b
+
+   * - 26
+     - AVerMedia UltraTV 1500 MCE / AVerTV M113 Philips Tuner
+     - IVTV16 1461:c019, IVTV16 1461:c01b
+
+   * - 27
+     - Sony VAIO Giga Pocket (ENX Kikyou)
+     - IVTV16 104d:813d
+
+   * - 28
+     - Hauppauge WinTV PVR-350 (V1)
+     - IVTV16 104d:813d
+
+   * - 29
+     - Yuan MPG600GR, Kuroutoshikou CX23416GYC-STVLP (no GR)
+     - IVTV16 104d:813d
+
+   * - 30
+     - Yuan MPG600GR, Kuroutoshikou CX23416GYC-STVLP (no GR/YCS)
+     - IVTV16 104d:813d
diff --git a/Documentation/admin-guide/media/ivtv.rst b/Documentation/admin-guide/media/ivtv.rst
new file mode 100644
index 000000000..8b65ac3f5
--- /dev/null
+++ b/Documentation/admin-guide/media/ivtv.rst
@@ -0,0 +1,218 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The ivtv driver
+===============
+
+Author: Hans Verkuil <hverkuil@kernel.org>
+
+This is a v4l2 device driver for the Conexant cx23415/6 MPEG encoder/decoder.
+The cx23415 can do both encoding and decoding, the cx23416 can only do MPEG
+encoding. Currently the only card featuring full decoding support is the
+Hauppauge PVR-350.
+
+.. note::
+
+   #) This driver requires the latest encoder firmware (version 2.06.039, size
+      376836 bytes). Get the firmware from here:
+
+      https://linuxtv.org/downloads/firmware/#conexant
+
+   #) 'normal' TV applications do not work with this driver, you need
+      an application that can handle MPEG input such as mplayer, xine, MythTV,
+      etc.
+
+The primary goal of the IVTV project is to provide a "clean room" Linux
+Open Source driver implementation for video capture cards based on the
+iCompression iTVC15 or Conexant CX23415/CX23416 MPEG Codec.
+
+Features
+--------
+
+ * Hardware mpeg2 capture of broadcast video (and sound) via the tuner or
+   S-Video/Composite and audio line-in.
+ * Hardware mpeg2 capture of FM radio where hardware support exists
+ * Supports NTSC, PAL, SECAM with stereo sound
+ * Supports SAP and bilingual transmissions.
+ * Supports raw VBI (closed captions and teletext).
+ * Supports sliced VBI (closed captions and teletext) and is able to insert
+   this into the captured MPEG stream.
+ * Supports raw YUV and PCM input.
+
+Additional features for the PVR-350 (CX23415 based)
+---------------------------------------------------
+
+ * Provides hardware mpeg2 playback
+ * Provides comprehensive OSD (On Screen Display: ie. graphics overlaying the
+   video signal)
+ * Provides a framebuffer (allowing X applications to appear on the video
+   device)
+ * Supports raw YUV output.
+
+IMPORTANT: In case of problems first read this page:
+	https://help.ubuntu.com/community/Install_IVTV_Troubleshooting
+
+See also
+--------
+
+https://linuxtv.org
+
+IRC
+---
+
+irc://irc.freenode.net/#v4l
+
+----------------------------------------------------------
+
+Devices
+-------
+
+A maximum of 12 ivtv boards are allowed at the moment.
+
+Cards that don't have a video output capability (i.e. non PVR350 cards)
+lack the vbi8, vbi16, video16 and video48 devices. They also do not
+support the framebuffer device /dev/fbx for OSD.
+
+The radio0 device may or may not be present, depending on whether the
+card has a radio tuner or not.
+
+Here is a list of the base v4l devices:
+
+.. code-block:: none
+
+	crw-rw----    1 root     video     81,   0 Jun 19 22:22 /dev/video0
+	crw-rw----    1 root     video     81,  16 Jun 19 22:22 /dev/video16
+	crw-rw----    1 root     video     81,  24 Jun 19 22:22 /dev/video24
+	crw-rw----    1 root     video     81,  32 Jun 19 22:22 /dev/video32
+	crw-rw----    1 root     video     81,  48 Jun 19 22:22 /dev/video48
+	crw-rw----    1 root     video     81,  64 Jun 19 22:22 /dev/radio0
+	crw-rw----    1 root     video     81, 224 Jun 19 22:22 /dev/vbi0
+	crw-rw----    1 root     video     81, 228 Jun 19 22:22 /dev/vbi8
+	crw-rw----    1 root     video     81, 232 Jun 19 22:22 /dev/vbi16
+
+Base devices
+------------
+
+For every extra card you have the numbers increased by one. For example,
+/dev/video0 is listed as the 'base' encoding capture device so we have:
+
+- /dev/video0  is the encoding capture device for the first card (card 0)
+- /dev/video1  is the encoding capture device for the second card (card 1)
+- /dev/video2  is the encoding capture device for the third card (card 2)
+
+Note that if the first card doesn't have a feature (eg no decoder, so no
+video16, the second card will still use video17. The simple rule is 'add
+the card number to the base device number'. If you have other capture
+cards (e.g. WinTV PCI) that are detected first, then you have to tell
+the ivtv module about it so that it will start counting at 1 (or 2, or
+whatever). Otherwise the device numbers can get confusing. The ivtv
+'ivtv_first_minor' module option can be used for that.
+
+
+- /dev/video0
+
+  The encoding capture device(s).
+
+  Read-only.
+
+  Reading from this device gets you the MPEG1/2 program stream.
+  Example:
+
+  .. code-block:: none
+
+	cat /dev/video0 > my.mpg (you need to hit ctrl-c to exit)
+
+
+- /dev/video16
+
+  The decoder output device(s)
+
+  Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
+
+  An mpeg2 stream sent to this device will appear on the selected video
+  display, audio will appear on the line-out/audio out.  It is only
+  available for cards that support video out. Example:
+
+  .. code-block:: none
+
+	cat my.mpg >/dev/video16
+
+
+- /dev/video24
+
+  The raw audio capture device(s).
+
+  Read-only
+
+  The raw audio PCM stereo stream from the currently selected
+  tuner or audio line-in.  Reading from this device results in a raw
+  (signed 16 bit Little Endian, 48000 Hz, stereo pcm) capture.
+  This device only captures audio. This should be replaced by an ALSA
+  device in the future.
+  Note that there is no corresponding raw audio output device, this is
+  not supported in the decoder firmware.
+
+
+- /dev/video32
+
+  The raw video capture device(s)
+
+  Read-only
+
+  The raw YUV video output from the current video input. The YUV format
+  is a 16x16 linear tiled NV12 format (V4L2_PIX_FMT_NV12_16L16)
+
+  Note that the YUV and PCM streams are not synchronized, so they are of
+  limited use.
+
+
+- /dev/video48
+
+  The raw video display device(s)
+
+  Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
+
+  Writes a YUV stream to the decoder of the card.
+
+
+- /dev/radio0
+
+  The radio tuner device(s)
+
+  Cannot be read or written.
+
+  Used to enable the radio tuner and tune to a frequency. You cannot
+  read or write audio streams with this device.  Once you use this
+  device to tune the radio, use /dev/video24 to read the raw pcm stream
+  or /dev/video0 to get an mpeg2 stream with black video.
+
+
+- /dev/vbi0
+
+  The 'vertical blank interval' (Teletext, CC, WSS etc) capture device(s)
+
+  Read-only
+
+  Captures the raw (or sliced) video data sent during the Vertical Blank
+  Interval. This data is used to encode teletext, closed captions, VPS,
+  widescreen signalling, electronic program guide information, and other
+  services.
+
+
+- /dev/vbi8
+
+  Processed vbi feedback device(s)
+
+  Read-only. Only present if the MPEG decoder (i.e. CX23415) exists.
+
+  The sliced VBI data embedded in an MPEG stream is reproduced on this
+  device. So while playing back a recording on /dev/video16, you can
+  read the embedded VBI data from /dev/vbi8.
+
+
+- /dev/vbi16
+
+  The vbi 'display' device(s)
+
+  Write-only. Only present if the MPEG decoder (i.e. CX23415) exists.
+
+  Can be used to send sliced VBI data to the video-out connector.
diff --git a/Documentation/admin-guide/media/lmedm04.rst b/Documentation/admin-guide/media/lmedm04.rst
new file mode 100644
index 000000000..a6ee33413
--- /dev/null
+++ b/Documentation/admin-guide/media/lmedm04.rst
@@ -0,0 +1,107 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Firmware files for lmedm04 cards
+================================
+
+To extract firmware for the DM04/QQBOX you need to copy the
+following file(s) to this directory.
+
+For DM04+/QQBOX LME2510C (Sharp 7395 Tuner)
+-------------------------------------------
+
+The Sharp 7395 driver can be found in windows/system32/drivers
+
+US2A0D.sys (dated 17 Mar 2009)
+
+
+and run:
+
+.. code-block:: none
+
+	scripts/get_dvb_firmware lme2510c_s7395
+
+will produce dvb-usb-lme2510c-s7395.fw
+
+An alternative but older firmware can be found on the driver
+disk DVB-S_EN_3.5A in BDADriver/driver
+
+LMEBDA_DVBS7395C.sys (dated 18 Jan 2008)
+
+and run:
+
+.. code-block:: none
+
+	./get_dvb_firmware lme2510c_s7395_old
+
+will produce dvb-usb-lme2510c-s7395.fw
+
+The LG firmware can be found on the driver
+disk DM04+_5.1A[LG] in BDADriver/driver
+
+For DM04 LME2510 (LG Tuner)
+---------------------------
+
+LMEBDA_DVBS.sys (dated 13 Nov 2007)
+
+and run:
+
+
+.. code-block:: none
+
+	./get_dvb_firmware lme2510_lg
+
+will produce dvb-usb-lme2510-lg.fw
+
+
+Other LG firmware can be extracted manually from US280D.sys
+only found in windows/system32/drivers
+
+dd if=US280D.sys ibs=1 skip=42360 count=3924 of=dvb-usb-lme2510-lg.fw
+
+For DM04 LME2510C (LG Tuner)
+----------------------------
+
+.. code-block:: none
+
+	dd if=US280D.sys ibs=1 skip=35200 count=3850 of=dvb-usb-lme2510c-lg.fw
+
+
+The Sharp 0194 tuner driver can be found in windows/system32/drivers
+
+US290D.sys (dated 09 Apr 2009)
+
+For LME2510
+-----------
+
+.. code-block:: none
+
+	dd if=US290D.sys ibs=1 skip=36856 count=3976 of=dvb-usb-lme2510-s0194.fw
+
+
+For LME2510C
+------------
+
+
+.. code-block:: none
+
+	dd if=US290D.sys ibs=1 skip=33152 count=3697 of=dvb-usb-lme2510c-s0194.fw
+
+
+The m88rs2000 tuner driver can be found in windows/system32/drivers
+
+US2B0D.sys (dated 29 Jun 2010)
+
+
+.. code-block:: none
+
+	dd if=US2B0D.sys ibs=1 skip=34432 count=3871 of=dvb-usb-lme2510c-rs2000.fw
+
+We need to modify id of rs2000 firmware or it will warm boot id 3344:1120.
+
+
+.. code-block:: none
+
+
+	echo -ne \\xF0\\x22 | dd conv=notrunc bs=1 count=2 seek=266 of=dvb-usb-lme2510c-rs2000.fw
+
+Copy the firmware file(s) to /lib/firmware
diff --git a/Documentation/admin-guide/media/mali-c55-graph.dot b/Documentation/admin-guide/media/mali-c55-graph.dot
new file mode 100644
index 000000000..0775ba42b
--- /dev/null
+++ b/Documentation/admin-guide/media/mali-c55-graph.dot
@@ -0,0 +1,19 @@
+digraph board {
+        rankdir=TB
+        n00000001 [label="{{} | mali-c55 tpg\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000001:port0 -> n00000003:port0 [style=dashed]
+        n00000003 [label="{{<port0> 0} | mali-c55 isp\n/dev/v4l-subdev1 | {<port1> 1 | <port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000003:port1 -> n00000007:port0 [style=bold]
+        n00000003:port2 -> n00000007:port2 [style=bold]
+        n00000003:port1 -> n0000000b:port0 [style=bold]
+        n00000007 [label="{{<port0> 0 | <port2> 2} | mali-c55 resizer fr\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000007:port1 -> n0000000e [style=bold]
+        n0000000b [label="{{<port0> 0} | mali-c55 resizer ds\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n0000000b:port1 -> n00000012 [style=bold]
+        n0000000e [label="mali-c55 fr\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+        n00000012 [label="mali-c55 ds\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+        n00000022 [label="{{<port0> 0} | csi2-rx\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000022:port1 -> n00000003:port0
+        n00000027 [label="{{} | imx415 1-001a\n/dev/v4l-subdev5 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000027:port0 -> n00000022:port0 [style=bold]
+}
\ No newline at end of file
diff --git a/Documentation/admin-guide/media/mali-c55.rst b/Documentation/admin-guide/media/mali-c55.rst
new file mode 100644
index 000000000..315f98200
--- /dev/null
+++ b/Documentation/admin-guide/media/mali-c55.rst
@@ -0,0 +1,413 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================================
+ARM Mali-C55 Image Signal Processor driver
+==========================================
+
+Introduction
+============
+
+This file documents the driver for ARM's Mali-C55 Image Signal Processor. The
+driver is located under drivers/media/platform/arm/mali-c55.
+
+The Mali-C55 ISP receives data in either raw Bayer format or RGB/YUV format from
+sensors through either a parallel interface or a memory bus before processing it
+and outputting it through an internal DMA engine. Two output pipelines are
+possible (though one may not be fitted, depending on the implementation). These
+are referred to as "Full resolution" and "Downscale", but the naming is historic
+and both pipes are capable of cropping/scaling operations. The full resolution
+pipe is also capable of outputting RAW data, bypassing much of the ISP's
+processing. The downscale pipe cannot output RAW data. An integrated test
+pattern generator can be used to drive the ISP and produce image data in the
+absence of a connected camera sensor. The driver module is named mali_c55, and
+is enabled through the CONFIG_VIDEO_MALI_C55 config option.
+
+The driver implements V4L2, Media Controller and V4L2 Subdevice interfaces and
+expects camera sensors connected to the ISP to have V4L2 subdevice interfaces.
+
+Mali-C55 ISP hardware
+=====================
+
+A high level functional view of the Mali-C55 ISP is presented below. The ISP
+takes input from either a live source or through a DMA engine for memory input,
+depending on the SoC integration.::
+
+  +---------+    +----------+                                     +--------+
+  | Sensor  |--->| CSI-2 Rx |                "Full Resolution"    |  DMA   |
+  +---------+    +----------+   |\                 Output    +--->| Writer |
+                       |        | \                          |    +--------+
+                       |        |  \    +----------+  +------+---> Streaming I/O
+  +------------+       +------->|   |   |          |  |
+  |            |                |   |-->| Mali-C55 |--+
+  | DMA Reader |--------------->|   |   |    ISP   |  |
+  |            |                |  /    |          |  |      +---> Streaming I/O
+  +------------+                | /     +----------+  |      |
+                                |/                    +------+
+                                                             |    +--------+
+                                                             +--->|  DMA   |
+                                               "Downscaled"       | Writer |
+                                                  Output          +--------+
+
+Media Controller Topology
+=========================
+
+An example of the ISP's topology (as implemented in a system with an IMX415
+camera sensor and generic CSI-2 receiver) is below:
+
+
+.. kernel-figure:: mali-c55-graph.dot
+    :alt:   mali-c55-graph.dot
+    :align: center
+
+The driver has 4 V4L2 subdevices:
+
+- `mali_c55 isp`: Responsible for configuring input crop and color space
+                  conversion
+- `mali_c55 tpg`: The test pattern generator, emulating a camera sensor.
+- `mali_c55 resizer fr`: The Full-Resolution pipe resizer
+- `mali_c55 resizer ds`: The Downscale pipe resizer
+
+The driver has 3 V4L2 video devices:
+
+- `mali-c55 fr`: The full-resolution pipe's capture device
+- `mali-c55 ds`: The downscale pipe's capture device
+- `mali-c55 3a stats`: The 3A statistics capture device
+
+Frame sequences are synchronised across to two capture devices, meaning if one
+pipe is started later than the other the sequence numbers returned in its
+buffers will match those of the other pipe rather than starting from zero.
+
+Idiosyncrasies
+--------------
+
+**mali-c55 isp**
+The `mali-c55 isp` subdevice has a single sink pad to which all sources of data
+should be connected. The active source is selected by enabling the appropriate
+media link and disabling all others. The ISP has two source pads, reflecting the
+different paths through which it can internally route data. Tap points within
+the ISP allow users to divert data to avoid processing by some or all of the
+hardware's processing steps. The diagram below is intended only to highlight how
+the bypassing works and is not a true reflection of those processing steps; for
+a high-level functional block diagram see ARM's developer page for the
+ISP [3]_::
+
+  +--------------------------------------------------------------+
+  |                Possible Internal ISP Data Routes             |
+  |          +------------+  +----------+  +------------+        |
+  +---+      |            |  |          |  |  Colour    |    +---+
+  | 0 |--+-->| Processing |->| Demosaic |->|   Space    |--->| 1 |
+  +---+  |   |            |  |          |  | Conversion |    +---+
+  |      |   +------------+  +----------+  +------------+        |
+  |      |                                                   +---+
+  |      +---------------------------------------------------| 2 |
+  |                                                          +---+
+  |                                                              |
+  +--------------------------------------------------------------+
+
+
+.. flat-table::
+    :header-rows: 1
+
+    * - Pad
+      - Direction
+      - Purpose
+
+    * - 0
+      - sink
+      - Data input, connected to the TPG and camera sensors
+
+    * - 1
+      - source
+      - RGB/YUV data, connected to the FR and DS V4L2 subdevices
+
+    * - 2
+      - source
+      - RAW bayer data, connected to the FR V4L2 subdevices
+
+The ISP is limited to both input and output resolutions between 640x480 and
+8192x8192, and this is reflected in the ISP and resizer subdevice's .set_fmt()
+operations.
+
+**mali-c55 resizer fr**
+The `mali-c55 resizer fr` subdevice has two _sink_ pads to reflect the different
+insertion points in the hardware (either RAW or demosaiced data):
+
+.. flat-table::
+    :header-rows: 1
+
+    * - Pad
+      - Direction
+      - Purpose
+
+    * - 0
+      - sink
+      - Data input connected to the ISP's demosaiced stream.
+
+    * - 1
+      - source
+      - Data output connected to the capture video device
+
+    * - 2
+      - sink
+      - Data input connected to the ISP's raw data stream
+
+The data source in use is selected through the routing API; two routes each of a
+single stream are available:
+
+.. flat-table::
+    :header-rows: 1
+
+    * - Sink Pad
+      - Source Pad
+      - Purpose
+
+    * - 0
+      - 1
+      - Demosaiced data route
+
+    * - 2
+      - 1
+      - Raw data route
+
+
+If the demosaiced route is active then the FR pipe is only capable of output
+in RGB/YUV formats. If the raw route is active then the output reflects the
+input (which may be either Bayer or RGB/YUV data).
+
+Using the driver to capture video
+=================================
+
+Using the media controller APIs we can configure the input source and ISP to
+capture images in a variety of formats. In the examples below, configuring the
+media graph is done with the v4l-utils [1]_ package's media-ctl utility.
+Capturing the images is done with yavta [2]_.
+
+Configuring the input source
+----------------------------
+
+The first step is to set the input source that we wish by enabling the correct
+media link. Using the example topology above, we can select the TPG as follows:
+
+.. code-block:: none
+
+    media-ctl -l "'lte-csi2-rx':1->'mali-c55 isp':0[0]"
+    media-ctl -l "'mali-c55 tpg':0->'mali-c55 isp':0[1]"
+
+Configuring which video devices will stream data
+------------------------------------------------
+
+The driver will wait for all video devices to have their VIDIOC_STREAMON ioctl
+called before it tells the sensor to start streaming. To facilitate this we need
+to enable links to the video devices that we want to use. In the example below
+we enable the links to both of the image capture video devices
+
+.. code-block:: none
+
+    media-ctl -l "'mali-c55 resizer fr':1->'mali-c55 fr':0[1]"
+    media-ctl -l "'mali-c55 resizer ds':1->'mali-c55 ds':0[1]"
+
+Capturing bayer data from the source and processing to RGB/YUV
+--------------------------------------------------------------
+
+To capture 1920x1080 bayer data from the source and push it through the ISP's
+full processing pipeline, we configure the data formats appropriately on the
+source, ISP and resizer subdevices and set the FR resizer's routing to select
+processed data. The media bus format on the resizer's source pad will be either
+RGB121212_1X36 or YUV10_1X30, depending on whether you want to capture RGB or
+YUV. The ISP's debayering block outputs RGB data natively, setting the source
+pad format to YUV10_1X30 enables the colour space conversion block.
+
+In this example we target RGB565 output, so select RGB121212_1X36 as the resizer
+source pad's format:
+
+.. code-block:: none
+
+    # Set formats on the TPG and ISP
+    media-ctl -V "'mali-c55 tpg':0[fmt:SRGGB20_1X20/1920x1080]"
+    media-ctl -V "'mali-c55 isp':0[fmt:SRGGB20_1X20/1920x1080]"
+    media-ctl -V "'mali-c55 isp':1[fmt:SRGGB20_1X20/1920x1080]"
+
+    # Set routing on the FR resizer
+    media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[1],2/0->1/0[0]]"
+
+    # Set format on the resizer, must be done AFTER the routing.
+    media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/1920x1080]"
+
+The downscale output can also be used to stream data at the same time. In this
+case since only processed data can be captured through the downscale output no
+routing need be set:
+
+.. code-block:: none
+
+    # Set format on the resizer
+    media-ctl -V "'mali-c55 resizer ds':1[fmt:RGB121212_1X36/1920x1080]"
+
+Following which images can be captured from both the FR and DS output's video
+devices (simultaneously, if desired):
+
+.. code-block:: none
+
+    yavta -f RGB565 -s 1920x1080 -c10 /dev/video0
+    yavta -f RGB565 -s 1920x1080 -c10 /dev/video1
+
+Cropping the image
+~~~~~~~~~~~~~~~~~~
+
+Both the full resolution and downscale pipes can crop to a minimum resolution of
+640x480. To crop the image simply configure the resizer's sink pad's crop and
+compose rectangles and set the format on the video device:
+
+.. code-block:: none
+
+    media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(480,270)/640x480 compose:(0,0)/640x480]"
+    media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]"
+    yavta -f RGB565 -s 640x480 -c10 /dev/video0
+
+Downscaling the image
+~~~~~~~~~~~~~~~~~~~~~
+
+Both the full resolution and downscale pipes can downscale the image by up to 8x
+provided the minimum 640x480 output resolution is adhered to. For the best image
+result the scaling ratio for each direction should be the same. To configure
+scaling we use the compose rectangle on the resizer's sink pad:
+
+.. code-block:: none
+
+    media-ctl -V "'mali-c55 resizer fr':0[fmt:RGB121212_1X36/1920x1080 crop:(0,0)/1920x1080 compose:(0,0)/640x480]"
+    media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB121212_1X36/640x480]"
+    yavta -f RGB565 -s 640x480 -c10 /dev/video0
+
+Capturing images in YUV formats
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If we need to output YUV data rather than RGB the color space conversion block
+needs to be active, which is achieved by setting MEDIA_BUS_FMT_YUV10_1X30 on the
+resizer's source pad. We can then configure a capture format like NV12 (here in
+its multi-planar variant)
+
+.. code-block:: none
+
+    media-ctl -V "'mali-c55 resizer fr':1[fmt:YUV10_1X30/1920x1080]"
+    yavta -f NV12M -s 1920x1080 -c10 /dev/video0
+
+Capturing RGB data from the source and processing it with the resizers
+----------------------------------------------------------------------
+
+The Mali-C55 ISP can work with sensors capable of outputting RGB data. In this
+case although none of the image quality blocks would be used it can still
+crop/scale the data in the usual way. For this reason RGB data input to the ISP
+still goes through the ISP subdevice's pad 1 to the resizer.
+
+To achieve this, the ISP's sink pad's format is set to
+MEDIA_BUS_FMT_RGB202020_1X60 - this reflects the format that data must be in to
+work with the ISP. Converting the camera sensor's output to that format is the
+responsibility of external hardware.
+
+In this example we ask the test pattern generator to give us RGB data instead of
+bayer.
+
+.. code-block:: none
+
+    media-ctl -V "'mali-c55 tpg':0[fmt:RGB202020_1X60/1920x1080]"
+    media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]"
+
+Cropping or scaling the data can be done in exactly the same way as outlined
+earlier.
+
+Capturing raw data from the source and outputting it unmodified
+-----------------------------------------------------------------
+
+The ISP can additionally capture raw data from the source and output it on the
+full resolution pipe only, completely unmodified. In this case the downscale
+pipe can still process the data normally and be used at the same time.
+
+To configure raw bypass the FR resizer's subdevice's routing table needs to be
+configured, followed by formats in the appropriate places:
+
+.. code-block:: none
+
+    media-ctl -R "'mali-c55 resizer fr'[0/0->1/0[0],2/0->1/0[1]]"
+    media-ctl -V "'mali-c55 isp':0[fmt:RGB202020_1X60/1920x1080]"
+    media-ctl -V "'mali-c55 resizer fr':2[fmt:RGB202020_1X60/1920x1080]"
+    media-ctl -V "'mali-c55 resizer fr':1[fmt:RGB202020_1X60/1920x1080]"
+
+    # Set format on the video device and stream
+    yavta -f RGB565 -s 1920x1080 -c10 /dev/video0
+
+.. _mali-c55-3a-stats:
+
+Capturing ISP Statistics
+========================
+
+The ISP is capable of producing statistics for consumption by image processing
+algorithms running in userspace. These statistics can be captured by queueing
+buffers to the `mali-c55 3a stats` V4L2 Device whilst the ISP is streaming. Only
+the :ref:`V4L2_META_FMT_MALI_C55_STATS <v4l2-meta-fmt-mali-c55-stats>`
+format is supported, so no format-setting need be done:
+
+.. code-block:: none
+
+    # We assume the media graph has been configured to support RGB565 capture
+    # from the mali-c55 fr V4L2 Device, which is at /dev/video0. The statistics
+    # V4L2 device is at /dev/video3
+
+    yavta -f RGB565 -s 1920x1080 -c32 /dev/video0 && \
+    yavta -c10 -F /dev/video3
+
+The layout of the buffer is described by :c:type:`mali_c55_stats_buffer`,
+but broadly statistics are generated to support three image processing
+algorithms; AEXP (Auto-Exposure), AWB (Auto-White Balance) and AF (Auto-Focus).
+These stats can be drawn from various places in the Mali C55 ISP pipeline, known
+as "tap points". This high-level block diagram is intended to explain where in
+the processing flow the statistics can be drawn from::
+
+                  +--> AEXP-2            +----> AEXP-1          +--> AF-0
+                  |                      +----> AF-1            |
+                  |                      |                      |
+      +---------+ |   +--------------+   |   +--------------+   |
+      |  Input  +-+-->+ Digital Gain +---+-->+ Black Level  +---+---+
+      +---------+     +--------------+       +--------------+       |
+  +-----------------------------------------------------------------+
+  |
+  |   +--------------+ +---------+       +----------------+
+  +-->| Sinter Noise +-+  White  +--+--->|  Lens Shading  +--+---------------+
+      |   Reduction  | | Balance |  |    |                |  |               |
+      +--------------+ +---------+  |    +----------------+  |               |
+                                    +---> AEXP-0 (A)         +--> AEXP-0 (B) |
+  +--------------------------------------------------------------------------+
+  |
+  |   +----------------+      +--------------+  +----------------+
+  +-->|  Tone mapping  +-+--->| Demosaicing  +->+ Purple Fringe  +-+-----------+
+      |                | |    +--------------+  |   Correction   | |           |
+      +----------------+ +-> AEXP-IRIDIX        +----------------+ +---> AWB-0 |
+  +----------------------------------------------------------------------------+
+  |                    +-------------+        +-------------+
+  +------------------->|   Colour    +---+--->|    Output   |
+                       | Correction  |   |    |  Pipelines  |
+                       +-------------+   |    +-------------+
+                                         +-->  AWB-1
+
+By default all statistics are drawn from the 0th tap point for each algorithm;
+I.E. AEXP statistics from AEXP-0 (A), AWB statistics from AWB-0 and AF
+statistics from AF-0. This is configurable for AEXP and AWB statsistics through
+programming the ISP's parameters.
+
+.. _mali-c55-3a-params:
+
+Programming ISP Parameters
+==========================
+
+The ISP can be programmed with various parameters from userspace to apply to the
+hardware before and during video stream. This allows userspace to dynamically
+change values such as black level, white balance and lens shading gains and so
+on.
+
+The buffer format and how to populate it are described by the
+:ref:`V4L2_META_FMT_MALI_C55_PARAMS <v4l2-meta-fmt-mali-c55-params>` format,
+which should be set as the data format for the `mali-c55 3a params` video node.
+
+References
+==========
+.. [1] https://git.linuxtv.org/v4l-utils.git/
+.. [2] https://git.ideasonboard.org/yavta.git
+.. [3] https://developer.arm.com/Processors/Mali-C55
diff --git a/Documentation/admin-guide/media/mgb4.rst b/Documentation/admin-guide/media/mgb4.rst
new file mode 100644
index 000000000..8e429fd77
--- /dev/null
+++ b/Documentation/admin-guide/media/mgb4.rst
@@ -0,0 +1,396 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+The mgb4 driver
+===============
+
+Copyright |copy| 2023 - 2025 Digiteq Automotive
+    author: Martin Tůma <martin.tuma@digiteqautomotive.com>
+
+This is a v4l2 device driver for the Digiteq Automotive FrameGrabber 4, a PCIe
+card capable of capturing and generating FPD-Link III and GMSL2/3 video streams
+as used in the automotive industry.
+
+sysfs interface
+---------------
+
+The mgb4 driver provides a sysfs interface, that is used to configure video
+stream related parameters (some of them must be set properly before the v4l2
+device can be opened) and obtain the video device/stream status.
+
+There are two types of parameters - global / PCI card related, found under
+``/sys/class/video4linux/videoX/device`` and module specific found under
+``/sys/class/video4linux/videoX``.
+
+Global (PCI card) parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**module_type** (R):
+    Module type.
+
+    | 0 - No module present
+    | 1 - FPDL3
+    | 2 - GMSL3 (one serializer, two daisy chained deserializers)
+    | 3 - GMSL3 (one serializer, two deserializers)
+    | 4 - GMSL3 (two deserializers with two daisy chain outputs)
+    | 6 - GMSL1
+    | 8 - GMSL3 coax
+
+**module_version** (R):
+    Module version number. Zero in case of a missing module.
+
+**fw_type** (R):
+    Firmware type.
+
+    | 1 - FPDL3
+    | 2 - GMSL3
+    | 3 - GMSL1
+
+**fw_version** (R):
+    Firmware version number.
+
+**serial_number** (R):
+    Card serial number. The format is::
+
+        PRODUCT-REVISION-SERIES-SERIAL
+
+    where each component is a 8b number.
+
+Common FPDL3/GMSL input parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**input_id** (R):
+    Input number ID, zero based.
+
+**oldi_lane_width** (RW):
+    Number of deserializer output lanes.
+
+    | 0 - single
+    | 1 - dual (default)
+
+**color_mapping** (RW):
+    Mapping of the incoming bits in the signal to the colour bits of the pixels.
+
+    | 0 - OLDI/JEIDA
+    | 1 - SPWG/VESA (default)
+    | 2 - ZDML
+
+**link_status** (R):
+    Video link status. If the link is locked, chips are properly connected and
+    communicating at the same speed and protocol. The link can be locked without
+    an active video stream.
+
+    A value of 0 is equivalent to the V4L2_IN_ST_NO_SYNC flag of the V4L2
+    VIDIOC_ENUMINPUT status bits.
+
+    | 0 - unlocked
+    | 1 - locked
+
+**stream_status** (R):
+    Video stream status. A stream is detected if the link is locked, the input
+    pixel clock is running and the DE signal is moving.
+
+    A value of 0 is equivalent to the V4L2_IN_ST_NO_SIGNAL flag of the V4L2
+    VIDIOC_ENUMINPUT status bits.
+
+    | 0 - not detected
+    | 1 - detected
+
+**video_width** (R):
+    Video stream width. This is the actual width as detected by the HW.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in the width
+    field of the v4l2_bt_timings struct.
+
+**video_height** (R):
+    Video stream height. This is the actual height as detected by the HW.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in the height
+    field of the v4l2_bt_timings struct.
+
+**vsync_status** (R):
+    The type of VSYNC pulses as detected by the video format detector.
+
+    The value is equivalent to the flags returned by VIDIOC_QUERY_DV_TIMINGS in
+    the polarities field of the v4l2_bt_timings struct.
+
+    | 0 - active low
+    | 1 - active high
+    | 2 - not available
+
+**hsync_status** (R):
+    The type of HSYNC pulses as detected by the video format detector.
+
+    The value is equivalent to the flags returned by VIDIOC_QUERY_DV_TIMINGS in
+    the polarities field of the v4l2_bt_timings struct.
+
+    | 0 - active low
+    | 1 - active high
+    | 2 - not available
+
+**vsync_gap_length** (RW):
+    If the incoming video signal does not contain synchronization VSYNC and
+    HSYNC pulses, these must be generated internally in the FPGA to achieve
+    the correct frame ordering. This value indicates, how many "empty" pixels
+    (pixels with deasserted Data Enable signal) are necessary to generate the
+    internal VSYNC pulse.
+
+**hsync_gap_length** (RW):
+    If the incoming video signal does not contain synchronization VSYNC and
+    HSYNC pulses, these must be generated internally in the FPGA to achieve
+    the correct frame ordering. This value indicates, how many "empty" pixels
+    (pixels with deasserted Data Enable signal) are necessary to generate the
+    internal HSYNC pulse. The value must be greater than 1 and smaller than
+    vsync_gap_length.
+
+**pclk_frequency** (R):
+    Input pixel clock frequency in kHz.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the pixelclock field of the v4l2_bt_timings struct.
+
+    *Note: The frequency_range parameter must be set properly first to get
+    a valid frequency here.*
+
+**hsync_width** (R):
+    Width of the HSYNC signal in PCLK clock ticks.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the hsync field of the v4l2_bt_timings struct.
+
+**vsync_width** (R):
+    Width of the VSYNC signal in PCLK clock ticks.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the vsync field of the v4l2_bt_timings struct.
+
+**hback_porch** (R):
+    Number of PCLK pulses between deassertion of the HSYNC signal and the first
+    valid pixel in the video line (marked by DE=1).
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the hbackporch field of the v4l2_bt_timings struct.
+
+**hfront_porch** (R):
+    Number of PCLK pulses between the end of the last valid pixel in the video
+    line (marked by DE=1) and assertion of the HSYNC signal.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the hfrontporch field of the v4l2_bt_timings struct.
+
+**vback_porch** (R):
+    Number of video lines between deassertion of the VSYNC signal and the video
+    line with the first valid pixel (marked by DE=1).
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the vbackporch field of the v4l2_bt_timings struct.
+
+**vfront_porch** (R):
+    Number of video lines between the end of the last valid pixel line (marked
+    by DE=1) and assertion of the VSYNC signal.
+
+    The value is identical to what VIDIOC_QUERY_DV_TIMINGS returns in
+    the vfrontporch field of the v4l2_bt_timings struct.
+
+**frequency_range** (RW)
+    PLL frequency range of the OLDI input clock generator. The PLL frequency is
+    derived from the Pixel Clock Frequency (PCLK) and is equal to PCLK if
+    oldi_lane_width is set to "single" and PCLK/2 if oldi_lane_width is set to
+    "dual".
+
+    | 0 - PLL < 50MHz (default)
+    | 1 - PLL >= 50MHz
+
+    *Note: This parameter can not be changed while the input v4l2 device is
+    open.*
+
+Common FPDL3/GMSL output parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**output_id** (R):
+    Output number ID, zero based.
+
+**video_source** (RW):
+    Output video source. If set to 0 or 1, the source is the corresponding card
+    input and the v4l2 output devices are disabled. If set to 2 or 3, the source
+    is the corresponding v4l2 video output device. The default is
+    the corresponding v4l2 output, i.e. 2 for OUT1 and 3 for OUT2.
+
+    | 0 - input 0
+    | 1 - input 1
+    | 2 - v4l2 output 0
+    | 3 - v4l2 output 1
+
+    *Note: This parameter can not be changed while ANY of the input/output v4l2
+    devices is open.*
+
+**display_width** (RW):
+    Display width. There is no autodetection of the connected display, so the
+    proper value must be set before the start of streaming. The default width
+    is 1280.
+
+    *Note: This parameter can not be changed while the output v4l2 device is
+    open.*
+
+**display_height** (RW):
+    Display height. There is no autodetection of the connected display, so the
+    proper value must be set before the start of streaming. The default height
+    is 640.
+
+    *Note: This parameter can not be changed while the output v4l2 device is
+    open.*
+
+**color_mapping** (RW):
+    Mapping of the outgoing bits in the signal to the colour bits of the pixels.
+
+    | 0 - OLDI/JEIDA
+    | 1 - SPWG/VESA (default)
+    | 2 - ZDML
+
+**frame_rate** (RW):
+    Output video signal frame rate limit in frames per second. Due to
+    the limited output pixel clock steps, the card can not always generate
+    a frame rate perfectly matching the value required by the connected display.
+    Using this parameter one can limit the frame rate by "crippling" the signal
+    so that the lines are not equal (the porches of the last line differ) but
+    the signal appears like having the exact frame rate to the connected display.
+    The default frame rate limit is 60Hz.
+
+**hsync_polarity** (RW):
+    HSYNC signal polarity.
+
+    | 0 - active low (default)
+    | 1 - active high
+
+**vsync_polarity** (RW):
+    VSYNC signal polarity.
+
+    | 0 - active low (default)
+    | 1 - active high
+
+**de_polarity** (RW):
+    DE signal polarity.
+
+    | 0 - active low
+    | 1 - active high (default)
+
+**pclk_frequency** (RW):
+    Output pixel clock frequency. Allowed values are between 25000-190000(kHz)
+    and there is a non-linear stepping between two consecutive allowed
+    frequencies. The driver finds the nearest allowed frequency to the given
+    value and sets it. When reading this property, you get the exact
+    frequency set by the driver. The default frequency is 61150kHz.
+
+    *Note: This parameter can not be changed while the output v4l2 device is
+    open.*
+
+**hsync_width** (RW):
+    Width of the HSYNC signal in pixels. The default value is 40.
+
+**vsync_width** (RW):
+    Width of the VSYNC signal in video lines. The default value is 20.
+
+**hback_porch** (RW):
+    Number of PCLK pulses between deassertion of the HSYNC signal and the first
+    valid pixel in the video line (marked by DE=1). The default value is 50.
+
+**hfront_porch** (RW):
+    Number of PCLK pulses between the end of the last valid pixel in the video
+    line (marked by DE=1) and assertion of the HSYNC signal. The default value
+    is 50.
+
+**vback_porch** (RW):
+    Number of video lines between deassertion of the VSYNC signal and the video
+    line with the first valid pixel (marked by DE=1). The default value is 31.
+
+**vfront_porch** (RW):
+    Number of video lines between the end of the last valid pixel line (marked
+    by DE=1) and assertion of the VSYNC signal. The default value is 30.
+
+FPDL3 specific input parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**fpdl3_input_width** (RW):
+    Number of deserializer input lines.
+
+    | 0 - auto (default)
+    | 1 - single
+    | 2 - dual
+
+FPDL3 specific output parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**fpdl3_output_width** (RW):
+    Number of serializer output lines.
+
+    | 0 - auto (default)
+    | 1 - single
+    | 2 - dual
+
+GMSL specific input parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**gmsl_mode** (RW):
+    GMSL speed mode.
+
+    | 0 - 12Gb/s (default)
+    | 1 - 6Gb/s
+    | 2 - 3Gb/s
+    | 3 - 1.5Gb/s
+
+**gmsl_stream_id** (RW):
+    The GMSL multi-stream contains up to four video streams. This parameter
+    selects which stream is captured by the video input. The value is the
+    zero-based index of the stream. The default stream id is 0.
+
+    *Note: This parameter can not be changed while the input v4l2 device is
+    open.*
+
+**gmsl_fec** (RW):
+    GMSL Forward Error Correction (FEC).
+
+    | 0 - disabled
+    | 1 - enabled (default)
+
+MTD partitions
+--------------
+
+The mgb4 driver creates a MTD device with two partitions:
+ - mgb4-fw.X - FPGA firmware.
+ - mgb4-data.X - Factory settings, e.g. card serial number.
+
+The *mgb4-fw* partition is writable and is used for FW updates, *mgb4-data* is
+read-only. The *X* attached to the partition name represents the card number.
+Depending on the CONFIG_MTD_PARTITIONED_MASTER kernel configuration, you may
+also have a third partition named *mgb4-flash* available in the system. This
+partition represents the whole, unpartitioned, card's FLASH memory and one should
+not fiddle with it...
+
+IIO (triggers)
+--------------
+
+The mgb4 driver creates an Industrial I/O (IIO) device that provides trigger and
+signal level status capability. The following scan elements are available:
+
+**activity**:
+	The trigger levels and pending status.
+
+	| bit 1 - trigger 1 pending
+	| bit 2 - trigger 2 pending
+	| bit 5 - trigger 1 level
+	| bit 6 - trigger 2 level
+
+**timestamp**:
+	The trigger event timestamp.
+
+The iio device can operate either in "raw" mode where you can fetch the signal
+levels (activity bits 5 and 6) using sysfs access or in triggered buffer mode.
+In the triggered buffer mode you can follow the signal level changes (activity
+bits 1 and 2) using the iio device in /dev. If you enable the timestamps, you
+will also get the exact trigger event time that can be matched to a video frame
+(every mgb4 video frame has a timestamp with the same clock source).
+
+*Note: although the activity sample always contains all the status bits, it makes
+no sense to get the pending bits in raw mode or the level bits in the triggered
+buffer mode - the values do not represent valid data in such case.*
diff --git a/Documentation/admin-guide/media/misc-cardlist.rst b/Documentation/admin-guide/media/misc-cardlist.rst
new file mode 100644
index 000000000..4c26bcfcc
--- /dev/null
+++ b/Documentation/admin-guide/media/misc-cardlist.rst
@@ -0,0 +1,28 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Firewire driver
+===============
+
+The media subsystem also provides a firewire driver for digital TV:
+
+=======  =====================
+Driver   Name
+=======  =====================
+firedtv  FireDTV and FloppyDTV
+=======  =====================
+
+Test drivers
+============
+
+In order to test userspace applications, there's a number of virtual
+drivers, with provide test functionality, simulating real hardware
+devices:
+
+=======  ======================================
+Driver   Name
+=======  ======================================
+vicodec  Virtual Codec Driver
+vim2m    Virtual Memory-to-Memory Driver
+vimc     Virtual Media Controller Driver (VIMC)
+vivid    Virtual Video Test Driver
+=======  ======================================
diff --git a/Documentation/admin-guide/media/omap3isp.rst b/Documentation/admin-guide/media/omap3isp.rst
new file mode 100644
index 000000000..f32e7375a
--- /dev/null
+++ b/Documentation/admin-guide/media/omap3isp.rst
@@ -0,0 +1,92 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+OMAP 3 Image Signal Processor (ISP) driver
+==========================================
+
+Copyright |copy| 2010 Nokia Corporation
+
+Copyright |copy| 2009 Texas Instruments, Inc.
+
+Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
+Sakari Ailus <sakari.ailus@iki.fi>, David Cohen <dacohen@gmail.com>
+
+
+Introduction
+------------
+
+This file documents the Texas Instruments OMAP 3 Image Signal Processor (ISP)
+driver located under drivers/media/platform/ti/omap3isp. The original driver was
+written by Texas Instruments but since that it has been rewritten (twice) at
+Nokia.
+
+The driver has been successfully used on the following versions of OMAP 3:
+
+- 3430
+- 3530
+- 3630
+
+The driver implements V4L2, Media controller and v4l2_subdev interfaces.
+Sensor, lens and flash drivers using the v4l2_subdev interface in the kernel
+are supported.
+
+
+Split to subdevs
+----------------
+
+The OMAP 3 ISP is split into V4L2 subdevs, each of the blocks inside the ISP
+having one subdev to represent it. Each of the subdevs provide a V4L2 subdev
+interface to userspace.
+
+- OMAP3 ISP CCP2
+- OMAP3 ISP CSI2a
+- OMAP3 ISP CCDC
+- OMAP3 ISP preview
+- OMAP3 ISP resizer
+- OMAP3 ISP AEWB
+- OMAP3 ISP AF
+- OMAP3 ISP histogram
+
+Each possible link in the ISP is modelled by a link in the Media controller
+interface. For an example program see [#]_.
+
+
+Controlling the OMAP 3 ISP
+--------------------------
+
+In general, the settings given to the OMAP 3 ISP take effect at the beginning
+of the following frame. This is done when the module becomes idle during the
+vertical blanking period on the sensor. In memory-to-memory operation the pipe
+is run one frame at a time. Applying the settings is done between the frames.
+
+All the blocks in the ISP, excluding the CSI-2 and possibly the CCP2 receiver,
+insist on receiving complete frames. Sensors must thus never send the ISP
+partial frames.
+
+Autoidle does have issues with some ISP blocks on the 3430, at least.
+Autoidle is only enabled on 3630 when the omap3isp module parameter autoidle
+is non-zero.
+
+Technical reference manuals (TRMs) and other documentation
+----------------------------------------------------------
+
+OMAP 3430 TRM:
+<URL:http://focus.ti.com/pdfs/wtbu/OMAP34xx_ES3.1.x_PUBLIC_TRM_vZM.zip>
+Referenced 2011-03-05.
+
+OMAP 35xx TRM:
+<URL:http://www.ti.com/litv/pdf/spruf98o> Referenced 2011-03-05.
+
+OMAP 3630 TRM:
+<URL:http://focus.ti.com/pdfs/wtbu/OMAP36xx_ES1.x_PUBLIC_TRM_vQ.zip>
+Referenced 2011-03-05.
+
+DM 3730 TRM:
+<URL:http://www.ti.com/litv/pdf/sprugn4h> Referenced 2011-03-06.
+
+
+References
+----------
+
+.. [#] http://git.ideasonboard.org/?p=media-ctl.git;a=summary
diff --git a/Documentation/admin-guide/media/opera-firmware.rst b/Documentation/admin-guide/media/opera-firmware.rst
new file mode 100644
index 000000000..fab358155
--- /dev/null
+++ b/Documentation/admin-guide/media/opera-firmware.rst
@@ -0,0 +1,33 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Opera firmware
+==============
+
+Author: Marco Gittler <g.marco@freenet.de>
+
+To extract the firmware for the Opera DVB-S1 USB-Box
+you need to copy the files:
+
+2830SCap2.sys
+2830SLoad2.sys
+
+from the windriver disk into this directory.
+
+Then run:
+
+.. code-block:: none
+
+	scripts/get_dvb_firmware opera1
+
+and after that you have 2 files:
+
+dvb-usb-opera-01.fw
+dvb-usb-opera1-fpga-01.fw
+
+in here.
+
+Copy them into /lib/firmware/ .
+
+After that the driver can load the firmware
+(if you have enabled firmware loading
+in kernel config and have hotplug running).
diff --git a/Documentation/admin-guide/media/other-usb-cardlist.rst b/Documentation/admin-guide/media/other-usb-cardlist.rst
new file mode 100644
index 000000000..fb88db50e
--- /dev/null
+++ b/Documentation/admin-guide/media/other-usb-cardlist.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Other USB cards list
+====================
+
+================  ======================================  =====================
+Driver            Card name                               USB IDs
+================  ======================================  =====================
+airspy		  Airspy				  1d50:60a1
+dvb-as102	  Abilis Systems DVB-Titan		  1BA6:0001
+dvb-as102	  PCTV Systems picoStick (74e)		  2013:0246
+dvb-as102	  Elgato EyeTV DTT Deluxe		  0fd9:002c
+dvb-as102	  nBox DVB-T Dongle			  0b89:0007
+dvb-as102	  Sky IT Digital Key (green led)	  2137:0001
+b2c2-flexcop-usb  Technisat/B2C2 FlexCop II/IIb/III	  0af7:0101
+		  Digital TV
+go7007		  WIS GO7007 MPEG encoder		  1943:a250, 093b:a002,
+							  093b:a004, 0eb1:6666,
+							  0eb1:6668
+hackrf		  HackRF Software Decoder Radio		  1d50:6089
+hdpvr		  Hauppauge HD PVR			  2040:4900, 2040:4901,
+							  2040:4902, 2040:4982,
+							  2040:4903
+msi2500		  Mirics MSi3101 SDR Dongle		  1df7:2500, 2040:d300
+pvrusb2		  Hauppauge WinTV-PVR USB2		  2040:2900, 2040:2950,
+							  2040:2400, 1164:0622,
+							  1164:0602, 11ba:1003,
+							  11ba:1001, 2040:7300,
+							  2040:7500, 2040:7501,
+							  0ccd:0039, 2040:7502,
+							  2040:7510
+pwc		  Creative Webcam 5			  041E:400C
+pwc		  Creative Webcam Pro Ex		  041E:4011
+pwc		  Logitech QuickCam 3000 Pro		  046D:08B0
+pwc		  Logitech QuickCam Notebook Pro	  046D:08B1
+pwc		  Logitech QuickCam 4000 Pro		  046D:08B2
+pwc		  Logitech QuickCam Zoom (old model)	  046D:08B3
+pwc		  Logitech QuickCam Zoom (new model)	  046D:08B4
+pwc		  Logitech QuickCam Orbit/Sphere	  046D:08B5
+pwc		  Logitech/Cisco VT Camera		  046D:08B6
+pwc		  Logitech ViewPort AV 100		  046D:08B7
+pwc		  Logitech QuickCam			  046D:08B8
+pwc		  Philips PCA645VC			  0471:0302
+pwc		  Philips PCA646VC			  0471:0303
+pwc		  Askey VC010 type 2			  0471:0304
+pwc		  Philips PCVC675K (Vesta)		  0471:0307
+pwc		  Philips PCVC680K (Vesta Pro)		  0471:0308
+pwc		  Philips PCVC690K (Vesta Pro Scan)	  0471:030C
+pwc		  Philips PCVC730K (ToUCam Fun),	  0471:0310
+		  PCVC830 (ToUCam II)
+pwc		  Philips PCVC740K (ToUCam Pro),	  0471:0311
+		  PCVC840 (ToUCam II)
+pwc		  Philips PCVC750K (ToUCam Pro Scan)	  0471:0312
+pwc		  Philips PCVC720K/40 (ToUCam XS)	  0471:0313
+pwc		  Philips SPC 900NC			  0471:0329
+pwc		  Philips SPC 880NC			  0471:032C
+pwc		  Sotec Afina Eye			  04CC:8116
+pwc		  Samsung MPC-C10			  055D:9000
+pwc		  Samsung MPC-C30			  055D:9001
+pwc		  Samsung SNC-35E (Ver3.0)		  055D:9002
+pwc		  Askey VC010 type 1			  069A:0001
+pwc		  AME Co. Afina Eye			  06BE:8116
+pwc		  Visionite VCS-UC300			  0d81:1900
+pwc		  Visionite VCS-UM100			  0d81:1910
+s2255drv	  Sensoray 2255				  1943:2255, 1943:2257
+stk1160		  STK1160 USB video capture dongle	  05e1:0408
+dvb-ttusb-budget  Technotrend/Hauppauge Nova-USB devices  0b48:1003, 0b48:1004,
+							  0b48:1005
+dvb-ttusb_dec	  Technotrend/Hauppauge MPEG decoder	  0b48:1006
+		  DEC3000-s
+dvb-ttusb_dec	  Technotrend/Hauppauge MPEG decoder	  0b48:1007
+dvb-ttusb_dec	  Technotrend/Hauppauge MPEG decoder	  0b48:1008
+		  DEC2000-t
+dvb-ttusb_dec	  Technotrend/Hauppauge MPEG decoder
+		  DEC2540-t				  0b48:1009
+usbtv		  Fushicai USBTV007 Audio-Video Grabber	  1b71:3002, 1f71:3301,
+							  1f71:3306
+================  ======================================  =====================
diff --git a/Documentation/admin-guide/media/pci-cardlist.rst b/Documentation/admin-guide/media/pci-cardlist.rst
new file mode 100644
index 000000000..239879634
--- /dev/null
+++ b/Documentation/admin-guide/media/pci-cardlist.rst
@@ -0,0 +1,108 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+PCI drivers
+===========
+
+The PCI boards are identified by an identification called PCI ID. The PCI ID
+is actually composed by two parts:
+
+	- Vendor ID and device ID;
+	- Subsystem ID and Subsystem device ID;
+
+The ``lspci -nn`` command allows identifying the vendor/device PCI IDs:
+
+.. code-block:: none
+   :emphasize-lines: 3
+
+    $ lspci -nn
+    ...
+    00:0a.0 Multimedia controller [0480]: Philips Semiconductors SAA7131/SAA7133/SAA7135 Video Broadcast Decoder [1131:7133] (rev d1)
+    00:0b.0 Multimedia controller [0480]: Brooktree Corporation Bt878 Audio Capture [109e:0878] (rev 11)
+    01:00.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23887/8 PCIe Broadcast Audio and Video Decoder with 3D Comb [14f1:8880] (rev 0f)
+    02:01.0 Multimedia video controller [0400]: Internext Compression Inc iTVC15 (CX23415) Video Decoder [4444:0803] (rev 01)
+    02:02.0 Multimedia video controller [0400]: Conexant Systems, Inc. CX23418 Single-Chip MPEG-2 Encoder with Integrated Analog Video/Broadcast Audio Decoder [14f1:5b7a]
+    02:03.0 Multimedia video controller [0400]: Brooktree Corporation Bt878 Video Capture [109e:036e] (rev 11)
+    ...
+
+The subsystem IDs can be obtained using ``lspci -vn``
+
+.. code-block:: none
+   :emphasize-lines: 4
+
+    $ lspci -vn
+    ...
+	00:0a.0 0480: 1131:7133 (rev d1)
+		Subsystem: 1461:f01d
+		Flags: bus master, medium devsel, latency 32, IRQ 209
+		Memory at e2002000 (32-bit, non-prefetchable) [size=2K]
+		Capabilities: [40] Power Management version 2
+    ...
+
+At the above example, the first card uses the ``saa7134`` driver, and
+has a vendor/device PCI ID equal to ``1131:7133`` and a PCI subsystem
+ID equal to ``1461:f01d`` (see :doc:`Saa7134 card list<saa7134-cardlist>`).
+
+Unfortunately, sometimes the same PCI subsystem ID is used by different
+products. So, several media drivers allow passing a ``card=`` parameter,
+in order to setup a card number that would match the correct settings for
+an specific board.
+
+The current supported PCI/PCIe cards (not including staging drivers) are
+listed below\ [#]_.
+
+.. [#] some of the drivers have sub-drivers, not shown at this table
+
+================  ========================================================
+Driver            Name
+================  ========================================================
+altera-ci         Altera FPGA based CI module
+b2c2-flexcop-pci  Technisat/B2C2 Air/Sky/Cable2PC PCI
+bt878             DVB/ATSC Support for bt878 based TV cards
+bttv              BT8x8 Video For Linux
+cobalt            Cisco Cobalt
+cx18              Conexant cx23418 MPEG encoder
+cx23885           Conexant cx23885 (2388x successor)
+cx25821           Conexant cx25821
+cx88xx            Conexant 2388x (bt878 successor)
+ddbridge          Digital Devices bridge
+dm1105            SDMC DM1105 based PCI cards
+dt3155            DT3155 frame grabber
+dvb-ttpci         AV7110 cards
+earth-pt1         PT1 cards
+earth-pt3         Earthsoft PT3 cards
+hexium_gemini     Hexium Gemini frame grabber
+hexium_orion      Hexium HV-PCI6 and Orion frame grabber
+hopper            HOPPER based cards
+ipu3-cio2         Intel ipu3-cio2 driver
+ivtv              Conexant cx23416/cx23415 MPEG encoder/decoder
+ivtvfb            Conexant cx23415 framebuffer
+mantis            MANTIS based cards
+mgb4              Digiteq Automotive MGB4 frame grabber
+mxb               Siemens-Nixdorf 'Multimedia eXtension Board'
+netup-unidvb      NetUP Universal DVB card
+ngene             Micronas nGene
+pluto2            Pluto2 cards
+saa7134           Philips SAA7134
+saa7164           NXP SAA7164
+smipcie           SMI PCIe DVBSky cards
+solo6x10          Bluecherry / Softlogic 6x10 capture cards (MPEG-4/H.264)
+tw5864            Techwell TW5864 video/audio grabber and encoder
+tw686x            Intersil/Techwell TW686x
+tw68              Techwell tw68x Video For Linux
+zoran             Zoran-36057/36067 JPEG codec
+================  ========================================================
+
+Some of those drivers support multiple devices, as shown at the card
+lists below:
+
+.. toctree::
+	:maxdepth: 1
+
+	bttv-cardlist
+	cx18-cardlist
+	cx23885-cardlist
+	cx88-cardlist
+	ivtv-cardlist
+	saa7134-cardlist
+	saa7164-cardlist
+	zoran-cardlist
diff --git a/Documentation/admin-guide/media/philips.rst b/Documentation/admin-guide/media/philips.rst
new file mode 100644
index 000000000..e2840be10
--- /dev/null
+++ b/Documentation/admin-guide/media/philips.rst
@@ -0,0 +1,247 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Philips webcams (pwc driver)
+============================
+
+This file contains some additional information for the Philips and OEM webcams.
+E-mail: webcam@smcc.demon.nl                        Last updated: 2004-01-19
+Site: http://www.smcc.demon.nl/webcam/
+
+As of this moment, the following cameras are supported:
+
+ * Philips PCA645
+ * Philips PCA646
+ * Philips PCVC675
+ * Philips PCVC680
+ * Philips PCVC690
+ * Philips PCVC720/40
+ * Philips PCVC730
+ * Philips PCVC740
+ * Philips PCVC750
+ * Askey VC010
+ * Creative Labs Webcam 5
+ * Creative Labs Webcam Pro Ex
+ * Logitech QuickCam 3000 Pro
+ * Logitech QuickCam 4000 Pro
+ * Logitech QuickCam Notebook Pro
+ * Logitech QuickCam Zoom
+ * Logitech QuickCam Orbit
+ * Logitech QuickCam Sphere
+ * Samsung MPC-C10
+ * Samsung MPC-C30
+ * Sotec Afina Eye
+ * AME CU-001
+ * Visionite VCS-UM100
+ * Visionite VCS-UC300
+
+The main webpage for the Philips driver is at the address above. It contains
+a lot of extra information, a FAQ, and the binary plugin 'PWCX'. This plugin
+contains decompression routines that allow you to use higher image sizes and
+framerates; in addition the webcam uses less bandwidth on the USB bus (handy
+if you want to run more than 1 camera simultaneously). These routines fall
+under a NDA, and may therefore not be distributed as source; however, its use
+is completely optional.
+
+You can build this code either into your kernel, or as a module. I recommend
+the latter, since it makes troubleshooting a lot easier. The built-in
+microphone is supported through the USB Audio class.
+
+When you load the module you can set some default settings for the
+camera; some programs depend on a particular image-size or -format and
+don't know how to set it properly in the driver. The options are:
+
+size
+   Can be one of 'sqcif', 'qsif', 'qcif', 'sif', 'cif' or
+   'vga', for an image size of resp. 128x96, 160x120, 176x144,
+   320x240, 352x288 and 640x480 (of course, only for those cameras that
+   support these resolutions).
+
+fps
+   Specifies the desired framerate. Is an integer in the range of 4-30.
+
+fbufs
+   This parameter specifies the number of internal buffers to use for storing
+   frames from the cam. This will help if the process that reads images from
+   the cam is a bit slow or momentarily busy. However, on slow machines it
+   only introduces lag, so choose carefully. The default is 3, which is
+   reasonable. You can set it between 2 and 5.
+
+mbufs
+   This is an integer between 1 and 10. It will tell the module the number of
+   buffers to reserve for mmap(), VIDIOCCGMBUF, VIDIOCMCAPTURE and friends.
+   The default is 2, which is adequate for most applications (double
+   buffering).
+
+   Should you experience a lot of 'Dumping frame...' messages during
+   grabbing with a tool that uses mmap(), you might want to increase if.
+   However, it doesn't really buffer images, it just gives you a bit more
+   slack when your program is behind. But you need a multi-threaded or
+   forked program to really take advantage of these buffers.
+
+   The absolute maximum is 10, but don't set it too high!  Every buffer takes
+   up 460 KB of RAM, so unless you have a lot of memory setting this to
+   something more than 4 is an absolute waste.  This memory is only
+   allocated during open(), so nothing is wasted when the camera is not in
+   use.
+
+power_save
+   When power_save is enabled (set to 1), the module will try to shut down
+   the cam on close() and re-activate on open(). This will save power and
+   turn off the LED. Not all cameras support this though (the 645 and 646
+   don't have power saving at all), and some models don't work either (they
+   will shut down, but never wake up). Consider this experimental. By
+   default this option is disabled.
+
+compression (only useful with the plugin)
+   With this option you can control the compression factor that the camera
+   uses to squeeze the image through the USB bus. You can set the
+   parameter between 0 and 3::
+
+     0 = prefer uncompressed images; if the requested mode is not available
+	 in an uncompressed format, the driver will silently switch to low
+	 compression.
+     1 = low compression.
+     2 = medium compression.
+     3 = high compression.
+
+   High compression takes less bandwidth of course, but it could also
+   introduce some unwanted artefacts. The default is 2, medium compression.
+   See the FAQ on the website for an overview of which modes require
+   compression.
+
+   The compression parameter does not apply to the 645 and 646 cameras
+   and OEM models derived from those (only a few). Most cams honour this
+   parameter.
+
+leds
+   This settings takes 2 integers, that define the on/off time for the LED
+   (in milliseconds). One of the interesting things that you can do with
+   this is let the LED blink while the camera is in use. This::
+
+     leds=500,500
+
+   will blink the LED once every second. But with::
+
+     leds=0,0
+
+   the LED never goes on, making it suitable for silent surveillance.
+
+   By default the camera's LED is on solid while in use, and turned off
+   when the camera is not used anymore.
+
+   This parameter works only with the ToUCam range of cameras (720, 730, 740,
+   750) and OEMs. For other cameras this command is silently ignored, and
+   the LED cannot be controlled.
+
+   Finally: this parameters does not take effect UNTIL the first time you
+   open the camera device. Until then, the LED remains on.
+
+dev_hint
+   A long standing problem with USB devices is their dynamic nature: you
+   never know what device a camera gets assigned; it depends on module load
+   order, the hub configuration, the order in which devices are plugged in,
+   and the phase of the moon (i.e. it can be random). With this option you
+   can give the driver a hint as to what video device node (/dev/videoX) it
+   should use with a specific camera. This is also handy if you have two
+   cameras of the same model.
+
+   A camera is specified by its type (the number from the camera model,
+   like PCA645, PCVC750VC, etc) and optionally the serial number (visible
+   in /sys/kernel/debug/usb/devices). A hint consists of a string with the
+   following format::
+
+      [type[.serialnumber]:]node
+
+   The square brackets mean that both the type and the serialnumber are
+   optional, but a serialnumber cannot be specified without a type (which
+   would be rather pointless). The serialnumber is separated from the type
+   by a '.'; the node number by a ':'.
+
+   This somewhat cryptic syntax is best explained by a few examples::
+
+     dev_hint=3,5              The first detected cam gets assigned
+			       /dev/video3, the second /dev/video5. Any
+			       other cameras will get the first free
+			       available slot (see below).
+
+     dev_hint=645:1,680:2      The PCA645 camera will get /dev/video1,
+			       and a PCVC680 /dev/video2.
+
+     dev_hint=645.0123:3,645.4567:0	The PCA645 camera with serialnumber
+					0123 goes to /dev/video3, the same
+					camera model with the 4567 serial
+					gets /dev/video0.
+
+     dev_hint=750:1,4,5,6       The PCVC750 camera will get /dev/video1, the
+				next 3 Philips cams will use /dev/video4
+				through /dev/video6.
+
+   Some points worth knowing:
+
+   - Serialnumbers are case sensitive and must be written full, including
+     leading zeroes (it's treated as a string).
+   - If a device node is already occupied, registration will fail and
+     the webcam is not available.
+   - You can have up to 64 video devices; be sure to make enough device
+     nodes in /dev if you want to spread the numbers.
+     After /dev/video9 comes /dev/video10 (not /dev/videoA).
+   - If a camera does not match any dev_hint, it will simply get assigned
+     the first available device node, just as it used to be.
+
+trace
+   In order to better detect problems, it is now possible to turn on a
+   'trace' of some of the calls the module makes; it logs all items in your
+   kernel log at debug level.
+
+   The trace variable is a bitmask; each bit represents a certain feature.
+   If you want to trace something, look up the bit value(s) in the table
+   below, add the values together and supply that to the trace variable.
+
+   ====== ======= ================================================ =======
+   Value  Value   Description					   Default
+   (dec)  (hex)
+   ====== ======= ================================================ =======
+       1    0x1   Module initialization; this will log messages       On
+		  while loading and unloading the module
+
+       2    0x2   probe() and disconnect() traces                     On
+
+       4    0x4   Trace open() and close() calls                      Off
+
+       8    0x8   read(), mmap() and associated ioctl() calls         Off
+
+      16   0x10   Memory allocation of buffers, etc.                  Off
+
+      32   0x20   Showing underflow, overflow and Dumping frame       On
+		  messages
+
+      64   0x40   Show viewport and image sizes                       Off
+
+     128   0x80   PWCX debugging                                      Off
+   ====== ======= ================================================ =======
+
+   For example, to trace the open() & read() functions, sum 8 + 4 = 12,
+   so you would supply trace=12 during insmod or modprobe. If
+   you want to turn the initialization and probing tracing off, set trace=0.
+   The default value for trace is 35 (0x23).
+
+
+
+Example::
+
+     # modprobe pwc size=cif fps=15 power_save=1
+
+The fbufs, mbufs and trace parameters are global and apply to all connected
+cameras. Each camera has its own set of buffers.
+
+size and fps only specify defaults when you open() the device; this is to
+accommodate some tools that don't set the size. You can change these
+settings after open() with the Video4Linux ioctl() calls. The default of
+defaults is QCIF size at 10 fps.
+
+The compression parameter is semiglobal; it sets the initial compression
+preference for all camera's, but this parameter can be set per camera with
+the VIDIOCPWCSCQUAL ioctl() call.
+
+All parameters are optional.
+
diff --git a/Documentation/admin-guide/media/platform-cardlist.rst b/Documentation/admin-guide/media/platform-cardlist.rst
new file mode 100644
index 000000000..63f4b19c3
--- /dev/null
+++ b/Documentation/admin-guide/media/platform-cardlist.rst
@@ -0,0 +1,87 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Platform drivers
+================
+
+There are several drivers that are focused on providing support for
+functionality that are already included at the main board, and don't
+use neither USB nor PCI bus. Those drivers are called platform
+drivers, and are very popular on embedded devices.
+
+The current supported of platform drivers (not including staging drivers) are
+listed below
+
+=================  ============================================================
+Driver             Name
+=================  ============================================================
+am437x-vpfe        TI AM437x VPFE
+aspeed-video       Aspeed AST2400 and AST2500
+atmel-isc          ATMEL Image Sensor Controller (ISC)
+atmel-isi          ATMEL Image Sensor Interface (ISI)
+cafe_ccic          Marvell 88ALP01 (Cafe) CMOS Camera Controller
+cdns-csi2rx        Cadence MIPI-CSI2 RX Controller
+cdns-csi2tx        Cadence MIPI-CSI2 TX Controller
+coda-vpu           Chips&Media Coda multi-standard codec IP
+dm355_ccdc         TI DM355 CCDC video capture
+dm644x_ccdc        TI DM6446 CCDC video capture
+exynos-fimc-is     EXYNOS4x12 FIMC-IS (Imaging Subsystem)
+exynos-fimc-lite   EXYNOS FIMC-LITE camera interface
+exynos-gsc         Samsung Exynos G-Scaler
+exy                Samsung S5P/EXYNOS4 SoC series Camera Subsystem
+imx-pxp            i.MX Pixel Pipeline (PXP)
+isdf               TI DM365 ISIF video capture
+mmp_camera         Marvell Armada 610 integrated camera controller
+mtk_jpeg           Mediatek JPEG Codec
+mtk-mdp            Mediatek MDP
+mtk-vcodec-dec     Mediatek Video Codec
+mtk-vpu            Mediatek Video Processor Unit
+mx2_emmaprp        MX2 eMMa-PrP
+omap3-isp          OMAP 3 Camera
+omap-vout          OMAP2/OMAP3 V4L2-Display
+pxa_camera         PXA27x Quick Capture Interface
+qcom-camss         Qualcomm V4L2 Camera Subsystem
+rcar-csi2          R-Car MIPI CSI-2 Receiver
+rcar_drif          Renesas Digital Radio Interface (DRIF)
+rcar-fcp           Renesas Frame Compression Processor
+rcar_fdp1          Renesas Fine Display Processor
+rcar_jpu           Renesas JPEG Processing Unit
+rcar-vin           R-Car Video Input (VIN)
+renesas-ceu        Renesas Capture Engine Unit (CEU)
+rockchip-rga       Rockchip Raster 2d Graphic Acceleration Unit
+s3c-camif          Samsung S3C24XX/S3C64XX SoC Camera Interface
+s5p-csis           S5P/EXYNOS MIPI-CSI2 receiver (MIPI-CSIS)
+s5p-fimc           S5P/EXYNOS4 FIMC/CAMIF camera interface
+s5p-g2d            Samsung S5P and EXYNOS4 G2D 2d graphics accelerator
+s5p-jpeg           Samsung S5P/Exynos3250/Exynos4 JPEG codec
+s5p-mfc            Samsung S5P MFC Video Codec
+sh_veu             SuperH VEU mem2mem video processing
+sh_vou             SuperH VOU video output
+stm32-dcmi         STM32 Digital Camera Memory Interface (DCMI)
+stm32-dma2d        STM32 Chrom-Art Accelerator Unit
+sun4i-csi          Allwinner A10 CMOS Sensor Interface Support
+sun6i-csi          Allwinner V3s Camera Sensor Interface
+sun8i-di           Allwinner Deinterlace
+sun8i-rotate       Allwinner DE2 rotation
+ti-cal             TI Memory-to-memory multimedia devices
+ti-csc             TI DVB platform devices
+ti-vpe             TI VPE (Video Processing Engine)
+venus-enc          Qualcomm Venus V4L2 encoder/decoder
+via-camera         VIAFB camera controller
+video-mux          Video Multiplexer
+vpif_display       TI DaVinci VPIF V4L2-Display
+vpif_capture       TI DaVinci VPIF video capture
+vsp1               Renesas VSP1 Video Processing Engine
+xilinx-tpg         Xilinx Video Test Pattern Generator
+xilinx-video       Xilinx Video IP (EXPERIMENTAL)
+xilinx-vtc         Xilinx Video Timing Controller
+=================  ============================================================
+
+MMC/SDIO DVB adapters
+---------------------
+
+=======  ===========================================
+Driver   Name
+=======  ===========================================
+smssdio  Siano SMS1xxx based MDTV via SDIO interface
+=======  ===========================================
+
diff --git a/Documentation/admin-guide/media/qcom_camss.rst b/Documentation/admin-guide/media/qcom_camss.rst
new file mode 100644
index 000000000..8a8f3ff40
--- /dev/null
+++ b/Documentation/admin-guide/media/qcom_camss.rst
@@ -0,0 +1,185 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+Qualcomm Camera Subsystem driver
+================================
+
+Introduction
+------------
+
+This file documents the Qualcomm Camera Subsystem driver located under
+drivers/media/platform/qcom/camss.
+
+The current version of the driver supports the Camera Subsystem found on
+Qualcomm MSM8916/APQ8016 and MSM8996/APQ8096 processors.
+
+The driver implements V4L2, Media controller and V4L2 subdev interfaces.
+Camera sensor using V4L2 subdev interface in the kernel is supported.
+
+The driver is implemented using as a reference the Qualcomm Camera Subsystem
+driver for Android as found in Code Linaro [#f1]_ [#f2]_.
+
+
+Qualcomm Camera Subsystem hardware
+----------------------------------
+
+The Camera Subsystem hardware found on 8x16 / 8x96 processors and supported by
+the driver consists of:
+
+- 2 / 3 CSIPHY modules. They handle the Physical layer of the CSI2 receivers.
+  A separate camera sensor can be connected to each of the CSIPHY module;
+- 2 / 4 CSID (CSI Decoder) modules. They handle the Protocol and Application
+  layer of the CSI2 receivers. A CSID can decode data stream from any of the
+  CSIPHY. Each CSID also contains a TG (Test Generator) block which can generate
+  artificial input data for test purposes;
+- ISPIF (ISP Interface) module. Handles the routing of the data streams from
+  the CSIDs to the inputs of the VFE;
+- 1 / 2 VFE (Video Front End) module(s). Contain a pipeline of image processing
+  hardware blocks. The VFE has different input interfaces. The PIX (Pixel) input
+  interface feeds the input data to the image processing pipeline. The image
+  processing pipeline contains also a scale and crop module at the end. Three
+  RDI (Raw Dump Interface) input interfaces bypass the image processing
+  pipeline. The VFE also contains the AXI bus interface which writes the output
+  data to memory.
+
+
+Supported functionality
+-----------------------
+
+The current version of the driver supports:
+
+- Input from camera sensor via CSIPHY;
+- Generation of test input data by the TG in CSID;
+- RDI interface of VFE
+
+  - Raw dump of the input data to memory.
+
+    Supported formats:
+
+    - YUYV/UYVY/YVYU/VYUY (packed YUV 4:2:2 - V4L2_PIX_FMT_YUYV /
+      V4L2_PIX_FMT_UYVY / V4L2_PIX_FMT_YVYU / V4L2_PIX_FMT_VYUY);
+    - MIPI RAW8 (8bit Bayer RAW - V4L2_PIX_FMT_SRGGB8 /
+      V4L2_PIX_FMT_SGRBG8 / V4L2_PIX_FMT_SGBRG8 / V4L2_PIX_FMT_SBGGR8);
+    - MIPI RAW10 (10bit packed Bayer RAW - V4L2_PIX_FMT_SBGGR10P /
+      V4L2_PIX_FMT_SGBRG10P / V4L2_PIX_FMT_SGRBG10P / V4L2_PIX_FMT_SRGGB10P /
+      V4L2_PIX_FMT_Y10P);
+    - MIPI RAW12 (12bit packed Bayer RAW - V4L2_PIX_FMT_SRGGB12P /
+      V4L2_PIX_FMT_SGBRG12P / V4L2_PIX_FMT_SGRBG12P / V4L2_PIX_FMT_SRGGB12P).
+    - (8x96 only) MIPI RAW14 (14bit packed Bayer RAW - V4L2_PIX_FMT_SRGGB14P /
+      V4L2_PIX_FMT_SGBRG14P / V4L2_PIX_FMT_SGRBG14P / V4L2_PIX_FMT_SRGGB14P).
+
+  - (8x96 only) Format conversion of the input data.
+
+    Supported input formats:
+
+    - MIPI RAW10 (10bit packed Bayer RAW - V4L2_PIX_FMT_SBGGR10P / V4L2_PIX_FMT_Y10P).
+
+    Supported output formats:
+
+    - Plain16 RAW10 (10bit unpacked Bayer RAW - V4L2_PIX_FMT_SBGGR10 / V4L2_PIX_FMT_Y10).
+
+- PIX interface of VFE
+
+  - Format conversion of the input data.
+
+    Supported input formats:
+
+    - YUYV/UYVY/YVYU/VYUY (packed YUV 4:2:2 - V4L2_PIX_FMT_YUYV /
+      V4L2_PIX_FMT_UYVY / V4L2_PIX_FMT_YVYU / V4L2_PIX_FMT_VYUY).
+
+    Supported output formats:
+
+    - NV12/NV21 (two plane YUV 4:2:0 - V4L2_PIX_FMT_NV12 / V4L2_PIX_FMT_NV21);
+    - NV16/NV61 (two plane YUV 4:2:2 - V4L2_PIX_FMT_NV16 / V4L2_PIX_FMT_NV61).
+    - (8x96 only) YUYV/UYVY/YVYU/VYUY (packed YUV 4:2:2 - V4L2_PIX_FMT_YUYV /
+      V4L2_PIX_FMT_UYVY / V4L2_PIX_FMT_YVYU / V4L2_PIX_FMT_VYUY).
+
+  - Scaling support. Configuration of the VFE Encoder Scale module
+    for downscalling with ratio up to 16x.
+
+  - Cropping support. Configuration of the VFE Encoder Crop module.
+
+- Concurrent and independent usage of two (8x96: three) data inputs -
+  could be camera sensors and/or TG.
+
+
+Driver Architecture and Design
+------------------------------
+
+The driver implements the V4L2 subdev interface. With the goal to model the
+hardware links between the modules and to expose a clean, logical and usable
+interface, the driver is split into V4L2 sub-devices as follows (8x16 / 8x96):
+
+- 2 / 3 CSIPHY sub-devices - each CSIPHY is represented by a single sub-device;
+- 2 / 4 CSID sub-devices - each CSID is represented by a single sub-device;
+- 2 / 4 ISPIF sub-devices - ISPIF is represented by a number of sub-devices
+  equal to the number of CSID sub-devices;
+- 4 / 8 VFE sub-devices - VFE is represented by a number of sub-devices equal to
+  the number of the input interfaces (3 RDI and 1 PIX for each VFE).
+
+The considerations to split the driver in this particular way are as follows:
+
+- representing CSIPHY and CSID modules by a separate sub-device for each module
+  allows to model the hardware links between these modules;
+- representing VFE by a separate sub-devices for each input interface allows
+  to use the input interfaces concurrently and independently as this is
+  supported by the hardware;
+- representing ISPIF by a number of sub-devices equal to the number of CSID
+  sub-devices allows to create linear media controller pipelines when using two
+  cameras simultaneously. This avoids branches in the pipelines which otherwise
+  will require a) userspace and b) media framework (e.g. power on/off
+  operations) to  make assumptions about the data flow from a sink pad to a
+  source pad on a single media entity.
+
+Each VFE sub-device is linked to a separate video device node.
+
+The media controller pipeline graph is as follows (with connected two / three
+OV5645 camera sensors):
+
+.. _qcom_camss_graph:
+
+.. kernel-figure:: qcom_camss_graph.dot
+    :alt:   qcom_camss_graph.dot
+    :align: center
+
+    Media pipeline graph 8x16
+
+.. kernel-figure:: qcom_camss_8x96_graph.dot
+    :alt:   qcom_camss_8x96_graph.dot
+    :align: center
+
+    Media pipeline graph 8x96
+
+
+Implementation
+--------------
+
+Runtime configuration of the hardware (updating settings while streaming) is
+not required to implement the currently supported functionality. The complete
+configuration on each hardware module is applied on STREAMON ioctl based on
+the current active media links, formats and controls set.
+
+The output size of the scaler module in the VFE is configured with the actual
+compose selection rectangle on the sink pad of the 'msm_vfe0_pix' entity.
+
+The crop output area of the crop module in the VFE is configured with the actual
+crop selection rectangle on the source pad of the 'msm_vfe0_pix' entity.
+
+
+Documentation
+-------------
+
+APQ8016 Specification:
+https://developer.qualcomm.com/download/sd410/snapdragon-410-processor-device-specification.pdf
+Referenced 2016-11-24.
+
+APQ8096 Specification:
+https://developer.qualcomm.com/download/sd820e/qualcomm-snapdragon-820e-processor-apq8096sge-device-specification.pdf
+Referenced 2018-06-22.
+
+References
+----------
+
+.. [#f1] https://git.codelinaro.org/clo/la/kernel/msm-3.10/
+.. [#f2] https://git.codelinaro.org/clo/la/kernel/msm-3.18/
diff --git a/Documentation/admin-guide/media/qcom_camss_8x96_graph.dot b/Documentation/admin-guide/media/qcom_camss_8x96_graph.dot
new file mode 100644
index 000000000..7ed243b41
--- /dev/null
+++ b/Documentation/admin-guide/media/qcom_camss_8x96_graph.dot
@@ -0,0 +1,106 @@
+# SPDX-License-Identifier: GPL-2.0
+
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | msm_csiphy0\n/dev/v4l-subdev0 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port1 -> n0000000a:port0 [style=dashed]
+	n00000001:port1 -> n0000000d:port0 [style=dashed]
+	n00000001:port1 -> n00000010:port0 [style=dashed]
+	n00000001:port1 -> n00000013:port0 [style=dashed]
+	n00000004 [label="{{<port0> 0} | msm_csiphy1\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000004:port1 -> n0000000a:port0 [style=dashed]
+	n00000004:port1 -> n0000000d:port0 [style=dashed]
+	n00000004:port1 -> n00000010:port0 [style=dashed]
+	n00000004:port1 -> n00000013:port0 [style=dashed]
+	n00000007 [label="{{<port0> 0} | msm_csiphy2\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000007:port1 -> n0000000a:port0 [style=dashed]
+	n00000007:port1 -> n0000000d:port0 [style=dashed]
+	n00000007:port1 -> n00000010:port0 [style=dashed]
+	n00000007:port1 -> n00000013:port0 [style=dashed]
+	n0000000a [label="{{<port0> 0} | msm_csid0\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000a:port1 -> n00000016:port0 [style=dashed]
+	n0000000a:port1 -> n00000019:port0 [style=dashed]
+	n0000000a:port1 -> n0000001c:port0 [style=dashed]
+	n0000000a:port1 -> n0000001f:port0 [style=dashed]
+	n0000000d [label="{{<port0> 0} | msm_csid1\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000d:port1 -> n00000016:port0 [style=dashed]
+	n0000000d:port1 -> n00000019:port0 [style=dashed]
+	n0000000d:port1 -> n0000001c:port0 [style=dashed]
+	n0000000d:port1 -> n0000001f:port0 [style=dashed]
+	n00000010 [label="{{<port0> 0} | msm_csid2\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000010:port1 -> n00000016:port0 [style=dashed]
+	n00000010:port1 -> n00000019:port0 [style=dashed]
+	n00000010:port1 -> n0000001c:port0 [style=dashed]
+	n00000010:port1 -> n0000001f:port0 [style=dashed]
+	n00000013 [label="{{<port0> 0} | msm_csid3\n/dev/v4l-subdev6 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000013:port1 -> n00000016:port0 [style=dashed]
+	n00000013:port1 -> n00000019:port0 [style=dashed]
+	n00000013:port1 -> n0000001c:port0 [style=dashed]
+	n00000013:port1 -> n0000001f:port0 [style=dashed]
+	n00000016 [label="{{<port0> 0} | msm_ispif0\n/dev/v4l-subdev7 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000016:port1 -> n00000022:port0 [style=dashed]
+	n00000016:port1 -> n0000002b:port0 [style=dashed]
+	n00000016:port1 -> n00000034:port0 [style=dashed]
+	n00000016:port1 -> n0000003d:port0 [style=dashed]
+	n00000016:port1 -> n00000046:port0 [style=dashed]
+	n00000016:port1 -> n0000004f:port0 [style=dashed]
+	n00000016:port1 -> n00000058:port0 [style=dashed]
+	n00000016:port1 -> n00000061:port0 [style=dashed]
+	n00000019 [label="{{<port0> 0} | msm_ispif1\n/dev/v4l-subdev8 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000019:port1 -> n00000022:port0 [style=dashed]
+	n00000019:port1 -> n0000002b:port0 [style=dashed]
+	n00000019:port1 -> n00000034:port0 [style=dashed]
+	n00000019:port1 -> n0000003d:port0 [style=dashed]
+	n00000019:port1 -> n00000046:port0 [style=dashed]
+	n00000019:port1 -> n0000004f:port0 [style=dashed]
+	n00000019:port1 -> n00000058:port0 [style=dashed]
+	n00000019:port1 -> n00000061:port0 [style=dashed]
+	n0000001c [label="{{<port0> 0} | msm_ispif2\n/dev/v4l-subdev9 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001c:port1 -> n00000022:port0 [style=dashed]
+	n0000001c:port1 -> n0000002b:port0 [style=dashed]
+	n0000001c:port1 -> n00000034:port0 [style=dashed]
+	n0000001c:port1 -> n0000003d:port0 [style=dashed]
+	n0000001c:port1 -> n00000046:port0 [style=dashed]
+	n0000001c:port1 -> n0000004f:port0 [style=dashed]
+	n0000001c:port1 -> n00000058:port0 [style=dashed]
+	n0000001c:port1 -> n00000061:port0 [style=dashed]
+	n0000001f [label="{{<port0> 0} | msm_ispif3\n/dev/v4l-subdev10 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001f:port1 -> n00000022:port0 [style=dashed]
+	n0000001f:port1 -> n0000002b:port0 [style=dashed]
+	n0000001f:port1 -> n00000034:port0 [style=dashed]
+	n0000001f:port1 -> n0000003d:port0 [style=dashed]
+	n0000001f:port1 -> n00000046:port0 [style=dashed]
+	n0000001f:port1 -> n0000004f:port0 [style=dashed]
+	n0000001f:port1 -> n00000058:port0 [style=dashed]
+	n0000001f:port1 -> n00000061:port0 [style=dashed]
+	n00000022 [label="{{<port0> 0} | msm_vfe0_rdi0\n/dev/v4l-subdev11 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000022:port1 -> n00000025 [style=bold]
+	n00000025 [label="msm_vfe0_video0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000002b [label="{{<port0> 0} | msm_vfe0_rdi1\n/dev/v4l-subdev12 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000002b:port1 -> n0000002e [style=bold]
+	n0000002e [label="msm_vfe0_video1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000034 [label="{{<port0> 0} | msm_vfe0_rdi2\n/dev/v4l-subdev13 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000034:port1 -> n00000037 [style=bold]
+	n00000037 [label="msm_vfe0_video2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n0000003d [label="{{<port0> 0} | msm_vfe0_pix\n/dev/v4l-subdev14 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003d:port1 -> n00000040 [style=bold]
+	n00000040 [label="msm_vfe0_video3\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n00000046 [label="{{<port0> 0} | msm_vfe1_rdi0\n/dev/v4l-subdev15 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000046:port1 -> n00000049 [style=bold]
+	n00000049 [label="msm_vfe1_video0\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n0000004f [label="{{<port0> 0} | msm_vfe1_rdi1\n/dev/v4l-subdev16 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000004f:port1 -> n00000052 [style=bold]
+	n00000052 [label="msm_vfe1_video1\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+	n00000058 [label="{{<port0> 0} | msm_vfe1_rdi2\n/dev/v4l-subdev17 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000058:port1 -> n0000005b [style=bold]
+	n0000005b [label="msm_vfe1_video2\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+	n00000061 [label="{{<port0> 0} | msm_vfe1_pix\n/dev/v4l-subdev18 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000061:port1 -> n00000064 [style=bold]
+	n00000064 [label="msm_vfe1_video3\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+	n000000e2 [label="{{} | ov5645 3-0039\n/dev/v4l-subdev19 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n000000e2:port0 -> n00000004:port0 [style=bold]
+	n000000e4 [label="{{} | ov5645 3-003a\n/dev/v4l-subdev20 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n000000e4:port0 -> n00000007:port0 [style=bold]
+	n000000e6 [label="{{} | ov5645 3-003b\n/dev/v4l-subdev21 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n000000e6:port0 -> n00000001:port0 [style=bold]
+}
diff --git a/Documentation/admin-guide/media/qcom_camss_graph.dot b/Documentation/admin-guide/media/qcom_camss_graph.dot
new file mode 100644
index 000000000..ef7dca92f
--- /dev/null
+++ b/Documentation/admin-guide/media/qcom_camss_graph.dot
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | msm_csiphy0\n/dev/v4l-subdev0 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port1 -> n00000007:port0 [style=dashed]
+	n00000001:port1 -> n0000000a:port0 [style=dashed]
+	n00000004 [label="{{<port0> 0} | msm_csiphy1\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000004:port1 -> n00000007:port0 [style=dashed]
+	n00000004:port1 -> n0000000a:port0 [style=dashed]
+	n00000007 [label="{{<port0> 0} | msm_csid0\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000007:port1 -> n0000000d:port0 [style=dashed]
+	n00000007:port1 -> n00000010:port0 [style=dashed]
+	n0000000a [label="{{<port0> 0} | msm_csid1\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000a:port1 -> n0000000d:port0 [style=dashed]
+	n0000000a:port1 -> n00000010:port0 [style=dashed]
+	n0000000d [label="{{<port0> 0} | msm_ispif0\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000d:port1 -> n00000013:port0 [style=dashed]
+	n0000000d:port1 -> n0000001c:port0 [style=dashed]
+	n0000000d:port1 -> n00000025:port0 [style=dashed]
+	n0000000d:port1 -> n0000002e:port0 [style=dashed]
+	n00000010 [label="{{<port0> 0} | msm_ispif1\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000010:port1 -> n00000013:port0 [style=dashed]
+	n00000010:port1 -> n0000001c:port0 [style=dashed]
+	n00000010:port1 -> n00000025:port0 [style=dashed]
+	n00000010:port1 -> n0000002e:port0 [style=dashed]
+	n00000013 [label="{{<port0> 0} | msm_vfe0_rdi0\n/dev/v4l-subdev6 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000013:port1 -> n00000016 [style=bold]
+	n00000016 [label="msm_vfe0_video0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000001c [label="{{<port0> 0} | msm_vfe0_rdi1\n/dev/v4l-subdev7 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001c:port1 -> n0000001f [style=bold]
+	n0000001f [label="msm_vfe0_video1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000025 [label="{{<port0> 0} | msm_vfe0_rdi2\n/dev/v4l-subdev8 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000025:port1 -> n00000028 [style=bold]
+	n00000028 [label="msm_vfe0_video2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n0000002e [label="{{<port0> 0} | msm_vfe0_pix\n/dev/v4l-subdev9 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000002e:port1 -> n00000031 [style=bold]
+	n00000031 [label="msm_vfe0_video3\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n00000057 [label="{{} | ov5645 1-0076\n/dev/v4l-subdev10 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000057:port0 -> n00000001:port0 [style=bold]
+	n00000059 [label="{{} | ov5645 1-0074\n/dev/v4l-subdev11 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000059:port0 -> n00000004:port0 [style=bold]
+}
diff --git a/Documentation/admin-guide/media/radio-cardlist.rst b/Documentation/admin-guide/media/radio-cardlist.rst
new file mode 100644
index 000000000..cec724256
--- /dev/null
+++ b/Documentation/admin-guide/media/radio-cardlist.rst
@@ -0,0 +1,43 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Radio drivers
+=============
+
+There is also support for pure AM/FM radio, and even for some FM radio
+transmitters:
+
+=====================  =========================================================
+Driver                 Name
+=====================  =========================================================
+si4713                 Silicon Labs Si4713 FM Radio Transmitter
+radio-aztech           Aztech/Packard Bell Radio
+radio-cadet            ADS Cadet AM/FM Tuner
+radio-gemtek           GemTek Radio card (or compatible)
+radio-maxiradio        Guillemot MAXI Radio FM 2000 radio
+radio-miropcm20        miroSOUND PCM20 radio
+radio-aimslab          AIMSlab RadioTrack (aka RadioReveal)
+radio-rtrack2          AIMSlab RadioTrack II
+saa7706h               SAA7706H Car Radio DSP
+radio-sf16fmi          SF16-FMI/SF16-FMP/SF16-FMD Radio
+radio-sf16fmr2         SF16-FMR2/SF16-FMD2 Radio
+radio-shark            Griffin radioSHARK USB radio receiver
+shark2                 Griffin radioSHARK2 USB radio receiver
+radio-si470x-common    Silicon Labs Si470x FM Radio Receiver
+radio-si476x           Silicon Laboratories Si476x I2C FM Radio
+radio-tea5764          TEA5764 I2C FM radio
+tef6862                TEF6862 Car Radio Enhanced Selectivity Tuner
+radio-terratec         TerraTec ActiveRadio ISA Standalone
+radio-timb             Enable the Timberdale radio driver
+radio-trust            Trust FM radio card
+radio-typhoon          Typhoon Radio (a.k.a. EcoRadio)
+fm_drv                 ISA radio devices
+fm_drv                 ISA radio devices
+radio-zoltrix          Zoltrix Radio
+dsbr100                D-Link/GemTek USB FM radio
+radio-keene            Keene FM Transmitter USB
+radio-ma901            Masterkit MA901 USB FM radio
+radio-mr800            AverMedia MR 800 USB FM radio
+radio-raremono         Thanko's Raremono AM/FM/SW radio
+radio-si470x-usb       Silicon Labs Si470x FM Radio Receiver support with USB
+radio-usb-si4713       Silicon Labs Si4713 FM Radio Transmitter support with USB
+=====================  =========================================================
diff --git a/Documentation/admin-guide/media/raspberrypi-pisp-be.dot b/Documentation/admin-guide/media/raspberrypi-pisp-be.dot
new file mode 100644
index 000000000..55671dc1d
--- /dev/null
+++ b/Documentation/admin-guide/media/raspberrypi-pisp-be.dot
@@ -0,0 +1,20 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0 | <port1> 1 | <port2> 2 | <port7> 7} | pispbe\n | {<port3> 3 | <port4> 4 | <port5> 5 | <port6> 6}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port3 -> n0000001c [style=bold]
+	n00000001:port4 -> n00000022 [style=bold]
+	n00000001:port5 -> n00000028 [style=bold]
+	n00000001:port6 -> n0000002e [style=bold]
+	n0000000a [label="pispbe-input\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000000a -> n00000001:port0 [style=bold]
+	n00000010 [label="pispbe-tdn_input\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000010 -> n00000001:port1 [style=bold]
+	n00000016 [label="pispbe-stitch_input\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n00000016 -> n00000001:port2 [style=bold]
+	n0000001c [label="pispbe-output0\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n00000022 [label="pispbe-output1\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n00000028 [label="pispbe-tdn_output\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+	n0000002e [label="pispbe-stitch_output\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+	n00000034 [label="pispbe-config\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+	n00000034 -> n00000001:port7 [style=bold]
+}
diff --git a/Documentation/admin-guide/media/raspberrypi-pisp-be.rst b/Documentation/admin-guide/media/raspberrypi-pisp-be.rst
new file mode 100644
index 000000000..0fcf46f26
--- /dev/null
+++ b/Documentation/admin-guide/media/raspberrypi-pisp-be.rst
@@ -0,0 +1,109 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========================================================
+Raspberry Pi PiSP Back End Memory-to-Memory ISP (pisp-be)
+=========================================================
+
+The PiSP Back End
+=================
+
+The PiSP Back End is a memory-to-memory Image Signal Processor (ISP) which reads
+image data from DRAM memory and performs image processing as specified by the
+application through the parameters in a configuration buffer, before writing
+pixel data back to memory through two distinct output channels.
+
+The ISP registers and programming model are documented in the `Raspberry Pi
+Image Signal Processor (PiSP) Specification document`_
+
+The PiSP Back End ISP processes images in tiles. The handling of image
+tessellation and the computation of low-level configuration parameters is
+realized by a free software library called `libpisp
+<https://github.com/raspberrypi/libpisp>`_.
+
+The full image processing pipeline, which involves capturing RAW Bayer data from
+an image sensor through a MIPI CSI-2 compatible capture interface, storing them
+in DRAM memory and processing them in the PiSP Back End to obtain images usable
+by an application is implemented in `libcamera <https://libcamera.org>`_ as
+part of the Raspberry Pi platform support.
+
+The pisp-be driver
+==================
+
+The Raspberry Pi PiSP Back End (pisp-be) driver is located under
+drivers/media/platform/raspberrypi/pisp-be. It uses the `V4L2 API` to register
+a number of video capture and output devices, the `V4L2 subdev API` to register
+a subdevice for the ISP that connects the video devices in a single media graph
+realized using the `Media Controller (MC) API`.
+
+The media topology registered by the `pisp-be` driver is represented below:
+
+.. _pips-be-topology:
+
+.. kernel-figure:: raspberrypi-pisp-be.dot
+    :alt:   Diagram of the default media pipeline topology
+    :align: center
+
+
+The media graph registers the following video device nodes:
+
+- pispbe-input: output device for images to be submitted to the ISP for
+  processing.
+- pispbe-tdn_input: output device for temporal denoise.
+- pispbe-stitch_input: output device for image stitching (HDR).
+- pispbe-output0: first capture device for processed images.
+- pispbe-output1: second capture device for processed images.
+- pispbe-tdn_output: capture device for temporal denoise.
+- pispbe-stitch_output: capture device for image stitching (HDR).
+- pispbe-config: output device for ISP configuration parameters.
+
+pispbe-input
+------------
+
+Images to be processed by the ISP are queued to the `pispbe-input` output device
+node. For a list of image formats supported as input to the ISP refer to the
+`Raspberry Pi Image Signal Processor (PiSP) Specification document`_.
+
+pispbe-tdn_input, pispbe-tdn_output
+-----------------------------------
+
+The `pispbe-tdn_input` output video device receives images to be processed by
+the temporal denoise block which are captured from the `pispbe-tdn_output`
+capture video device. Userspace is responsible for maintaining queues on both
+devices, and ensuring that buffers completed on the output are queued to the
+input.
+
+pispbe-stitch_input, pispbe-stitch_output
+-----------------------------------------
+
+To realize HDR (high dynamic range) image processing the image stitching and
+tonemapping blocks are used. The `pispbe-stitch_output` writes images to memory
+and the `pispbe-stitch_input` receives the previously written frame to process
+it along with the current input image. Userspace is responsible for maintaining
+queues on both devices, and ensuring that buffers completed on the output are
+queued to the input.
+
+pispbe-output0, pispbe-output1
+------------------------------
+
+The two capture devices write to memory the pixel data as processed by the ISP.
+
+pispbe-config
+-------------
+
+The `pispbe-config` output video devices receives a buffer of configuration
+parameters that define the desired image processing to be performed by the ISP.
+
+The format of the ISP configuration parameter is defined by
+:c:type:`pisp_be_tiles_config` C structure and the meaning of each parameter is
+described in the `Raspberry Pi Image Signal Processor (PiSP) Specification
+document`_.
+
+ISP configuration
+=================
+
+The ISP configuration is described solely by the content of the parameters
+buffer. The only parameter that userspace needs to configure using the V4L2 API
+is the image format on the output and capture video devices for validation of
+the content of the parameters buffer.
+
+.. _Raspberry Pi Image Signal Processor (PiSP) Specification document: https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf
diff --git a/Documentation/admin-guide/media/raspberrypi-rp1-cfe.dot b/Documentation/admin-guide/media/raspberrypi-rp1-cfe.dot
new file mode 100644
index 000000000..7717f2291
--- /dev/null
+++ b/Documentation/admin-guide/media/raspberrypi-rp1-cfe.dot
@@ -0,0 +1,27 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | csi2\n/dev/v4l-subdev0 | {<port1> 1 | <port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port1 -> n00000011 [style=dashed]
+	n00000001:port1 -> n00000007:port0
+	n00000001:port2 -> n00000015
+	n00000001:port2 -> n00000007:port0 [style=dashed]
+	n00000001:port3 -> n00000019 [style=dashed]
+	n00000001:port3 -> n00000007:port0 [style=dashed]
+	n00000001:port4 -> n0000001d [style=dashed]
+	n00000001:port4 -> n00000007:port0 [style=dashed]
+	n00000007 [label="{{<port0> 0 | <port1> 1} | pisp-fe\n/dev/v4l-subdev1 | {<port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000007:port2 -> n00000021
+	n00000007:port3 -> n00000025 [style=dashed]
+	n00000007:port4 -> n00000029
+	n0000000d [label="{imx219 6-0010\n/dev/v4l-subdev2 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000000d:port0 -> n00000001:port0 [style=bold]
+	n00000011 [label="rp1-cfe-csi2-ch0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n00000015 [label="rp1-cfe-csi2-ch1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000019 [label="rp1-cfe-csi2-ch2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n0000001d [label="rp1-cfe-csi2-ch3\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n00000021 [label="rp1-cfe-fe-image0\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n00000025 [label="rp1-cfe-fe-image1\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+	n00000029 [label="rp1-cfe-fe-stats\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+	n0000002d [label="rp1-cfe-fe-config\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+	n0000002d -> n00000007:port1
+}
diff --git a/Documentation/admin-guide/media/raspberrypi-rp1-cfe.rst b/Documentation/admin-guide/media/raspberrypi-rp1-cfe.rst
new file mode 100644
index 000000000..668d978a9
--- /dev/null
+++ b/Documentation/admin-guide/media/raspberrypi-rp1-cfe.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================================
+Raspberry Pi PiSP Camera Front End (rp1-cfe)
+============================================
+
+The PiSP Camera Front End
+=========================
+
+The PiSP Camera Front End (CFE) is a module which combines a CSI-2 receiver with
+a simple ISP, called the Front End (FE).
+
+The CFE has four DMA engines and can write frames from four separate streams
+received from the CSI-2 to the memory. One of those streams can also be routed
+directly to the FE, which can do minimal image processing, write two versions
+(e.g. non-scaled and downscaled versions) of the received frames to memory and
+provide statistics of the received frames.
+
+The FE registers are documented in the `Raspberry Pi Image Signal Processor
+(ISP) Specification document
+<https://datasheets.raspberrypi.com/camera/raspberry-pi-image-signal-processor-specification.pdf>`_,
+and example code for FE can be found in `libpisp
+<https://github.com/raspberrypi/libpisp>`_.
+
+The rp1-cfe driver
+==================
+
+The Raspberry Pi PiSP Camera Front End (rp1-cfe) driver is located under
+drivers/media/platform/raspberrypi/rp1-cfe. It uses the `V4L2 API` to register
+a number of video capture and output devices, the `V4L2 subdev API` to register
+subdevices for the CSI-2 received and the FE that connects the video devices in
+a single media graph realized using the `Media Controller (MC) API`.
+
+The media topology registered by the `rp1-cfe` driver, in this particular
+example connected to an imx219 sensor, is the following one:
+
+.. _rp1-cfe-topology:
+
+.. kernel-figure:: raspberrypi-rp1-cfe.dot
+    :alt:   Diagram of an example media pipeline topology
+    :align: center
+
+The media graph contains the following video device nodes:
+
+- rp1-cfe-csi2-ch0: capture device for the first CSI-2 stream
+- rp1-cfe-csi2-ch1: capture device for the second CSI-2 stream
+- rp1-cfe-csi2-ch2: capture device for the third CSI-2 stream
+- rp1-cfe-csi2-ch3: capture device for the fourth CSI-2 stream
+- rp1-cfe-fe-image0: capture device for the first FE output
+- rp1-cfe-fe-image1: capture device for the second FE output
+- rp1-cfe-fe-stats: capture device for the FE statistics
+- rp1-cfe-fe-config: output device for FE configuration
+
+rp1-cfe-csi2-chX
+----------------
+
+The rp1-cfe-csi2-chX capture devices are normal V4L2 capture devices which
+can be used to capture video frames or metadata received from the CSI-2.
+
+rp1-cfe-fe-image0, rp1-cfe-fe-image1
+------------------------------------
+
+The rp1-cfe-fe-image0 and rp1-cfe-fe-image1 capture devices are used to write
+the processed frames to memory.
+
+rp1-cfe-fe-stats
+----------------
+
+The format of the FE statistics buffer is defined by
+:c:type:`pisp_statistics` C structure and the meaning of each parameter is
+described in the `PiSP specification` document.
+
+rp1-cfe-fe-config
+-----------------
+
+The format of the FE configuration buffer is defined by
+:c:type:`pisp_fe_config` C structure and the meaning of each parameter is
+described in the `PiSP specification` document.
diff --git a/Documentation/admin-guide/media/rcar-fdp1.rst b/Documentation/admin-guide/media/rcar-fdp1.rst
new file mode 100644
index 000000000..88b0edcf9
--- /dev/null
+++ b/Documentation/admin-guide/media/rcar-fdp1.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Renesas R-Car Fine Display Processor (FDP1) Driver
+==================================================
+
+The R-Car FDP1 driver implements driver-specific controls as follows.
+
+``V4L2_CID_DEINTERLACING_MODE (menu)``
+    The video deinterlacing mode (such as Bob, Weave, ...). The R-Car FDP1
+    driver implements the following modes.
+
+.. flat-table::
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 4
+
+    * - ``"Progressive" (0)``
+      - The input image video stream is progressive (not interlaced). No
+        deinterlacing is performed. Apart from (optional) format and encoding
+        conversion output frames are identical to the input frames.
+    * - ``"Adaptive 2D/3D" (1)``
+      - Motion adaptive version of 2D and 3D deinterlacing. Use 3D deinterlacing
+        in the presence of fast motion and 2D deinterlacing with diagonal
+        interpolation otherwise.
+    * - ``"Fixed 2D" (2)``
+      - The current field is scaled vertically by averaging adjacent lines to
+        recover missing lines. This method is also known as blending or Line
+        Averaging (LAV).
+    * - ``"Fixed 3D" (3)``
+      - The previous and next fields are averaged to recover lines missing from
+        the current field. This method is also known as Field Averaging (FAV).
+    * - ``"Previous field" (4)``
+      - The current field is weaved with the previous field, i.e. the previous
+        field is used to fill missing lines from the current field. This method
+        is also known as weave deinterlacing.
+    * - ``"Next field" (5)``
+      - The current field is weaved with the next field, i.e. the next field is
+        used to fill missing lines from the current field. This method is also
+        known as weave deinterlacing.
diff --git a/Documentation/admin-guide/media/remote-controller.rst b/Documentation/admin-guide/media/remote-controller.rst
new file mode 100644
index 000000000..188944b00
--- /dev/null
+++ b/Documentation/admin-guide/media/remote-controller.rst
@@ -0,0 +1,76 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================================================
+Infrared remote control support in video4linux drivers
+======================================================
+
+Authors: Gerd Hoffmann, Mauro Carvalho Chehab
+
+Basics
+======
+
+Most analog and digital TV boards support remote controllers. Several of
+them have a microprocessor that receives the IR carriers, convert into
+pulse/space sequences and then to scan codes, returning such codes to
+userspace ("scancode mode"). Other boards return just the pulse/space
+sequences ("raw mode").
+
+The support for remote controller in scancode mode is provided by the
+standard Linux input layer. The support for raw mode is provided via LIRC.
+
+In order to check the support and test it, it is suggested to download
+the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_. It provides
+two tools to handle remote controllers:
+
+- ir-keytable: provides a way to query the remote controller, list the
+  protocols it supports, enable in-kernel support for IR decoder or
+  switch the protocol and to test the reception of scan codes;
+
+- ir-ctl: provide tools to handle remote controllers that support raw mode
+  via LIRC interface.
+
+Usually, the remote controller module is auto-loaded when the TV card is
+detected. However, for a few devices, you need to manually load the
+ir-kbd-i2c module.
+
+How it works
+============
+
+The modules register the remote as keyboard within the linux input
+layer, i.e. you'll see the keys of the remote as normal key strokes
+(if CONFIG_INPUT_KEYBOARD is enabled).
+
+Using the event devices (CONFIG_INPUT_EVDEV) it is possible for
+applications to access the remote via /dev/input/event<n> devices.
+The udev/systemd will automatically create the devices. If you install
+the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_, it may also
+automatically load a different keytable than the default one. Please see
+`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ ir-keytable.1
+man page for details.
+
+The ir-keytable tool is nice for trouble shooting, i.e. to check
+whenever the input device is really present, which of the devices it
+is, check whenever pressing keys on the remote actually generates
+events and the like.  You can also use any other input utility that changes
+the keymaps, like the input kbd utility.
+
+
+Using with lircd
+----------------
+
+The latest versions of the lircd daemon supports reading events from the
+linux input layer (via event device). It also supports receiving IR codes
+in lirc mode.
+
+
+Using without lircd
+-------------------
+
+Xorg recognizes several IR keycodes that have its numerical value lower
+than 247. With the advent of Wayland, the input driver got updated too,
+and should now accept all keycodes. Yet, you may want to just reassign
+the keycodes to something that your favorite media application likes.
+
+This can be done by setting
+`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ to load your own
+keytable in runtime. Please read  ir-keytable.1 man page for details.
diff --git a/Documentation/admin-guide/media/rkcif-rk3568-vicap.dot b/Documentation/admin-guide/media/rkcif-rk3568-vicap.dot
new file mode 100644
index 000000000..3fac59335
--- /dev/null
+++ b/Documentation/admin-guide/media/rkcif-rk3568-vicap.dot
@@ -0,0 +1,8 @@
+digraph board {
+        rankdir=TB
+        n00000001 [label="{{<port0> 0} | rkcif-dvp0\n/dev/v4l-subdev0 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000001:port1 -> n00000004
+        n00000004 [label="rkcif-dvp0-id0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+        n00000025 [label="{{} | it6801 2-0048\n/dev/v4l-subdev1 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000025:port0 -> n00000001:port0
+}
diff --git a/Documentation/admin-guide/media/rkcif-rk3588-vicap.dot b/Documentation/admin-guide/media/rkcif-rk3588-vicap.dot
new file mode 100644
index 000000000..f6d340492
--- /dev/null
+++ b/Documentation/admin-guide/media/rkcif-rk3588-vicap.dot
@@ -0,0 +1,29 @@
+digraph board {
+        rankdir=TB
+        n00000007 [label="{{<port0> 0} | rkcif-mipi2\n/dev/v4l-subdev0 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000007:port1 -> n0000000a
+        n00000007:port1 -> n00000010 [style=dashed]
+        n00000007:port1 -> n00000016 [style=dashed]
+        n00000007:port1 -> n0000001c [style=dashed]
+        n0000000a [label="rkcif-mipi2-id0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+        n00000010 [label="rkcif-mipi2-id1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+        n00000016 [label="rkcif-mipi2-id2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+        n0000001c [label="rkcif-mipi2-id3\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+        n00000025 [label="{{<port0> 0} | rkcif-mipi4\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000025:port1 -> n00000028
+        n00000025:port1 -> n0000002e [style=dashed]
+        n00000025:port1 -> n00000034 [style=dashed]
+        n00000025:port1 -> n0000003a [style=dashed]
+        n00000028 [label="rkcif-mipi4-id0\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+        n0000002e [label="rkcif-mipi4-id1\n/dev/video5", shape=box, style=filled, fillcolor=yellow]
+        n00000034 [label="rkcif-mipi4-id2\n/dev/video6", shape=box, style=filled, fillcolor=yellow]
+        n0000003a [label="rkcif-mipi4-id3\n/dev/video7", shape=box, style=filled, fillcolor=yellow]
+        n00000043 [label="{{<port0> 0} | dw-mipi-csi2rx fdd30000.csi\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000043:port1 -> n00000007:port0
+        n00000048 [label="{{<port0> 0} | dw-mipi-csi2rx fdd50000.csi\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000048:port1 -> n00000025:port0
+        n0000004d [label="{{} | imx415 3-001a\n/dev/v4l-subdev4 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+        n0000004d:port0 -> n00000043:port0
+        n00000051 [label="{{} | imx415 4-001a\n/dev/v4l-subdev5 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+        n00000051:port0 -> n00000048:port0
+}
diff --git a/Documentation/admin-guide/media/rkcif.rst b/Documentation/admin-guide/media/rkcif.rst
new file mode 100644
index 000000000..313a0ea45
--- /dev/null
+++ b/Documentation/admin-guide/media/rkcif.rst
@@ -0,0 +1,111 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========================================
+Rockchip Camera Interface (CIF)
+=========================================
+
+Introduction
+============
+
+The Rockchip Camera Interface (CIF) is featured in many Rockchip SoCs in
+different variants.
+The different variants are combinations of common building blocks, such as
+
+* INTERFACE blocks of different types, namely
+
+  * the Digital Video Port (DVP, a parallel data interface)
+  * the interface block for the MIPI CSI-2 receiver
+
+* CROP units
+
+* MIPI CSI-2 receiver (not available on all variants): This unit is referred
+  to as MIPI CSI HOST in the Rockchip documentation.
+  Technically, it is a separate hardware block, but it is strongly coupled to
+  the CIF and therefore included here.
+
+* MUX units (not available on all variants) that pass the video data to an
+  image signal processor (ISP)
+
+* SCALE units (not available on all variants)
+
+* DMA engines that transfer video data into system memory using a
+  double-buffering mechanism called ping-pong mode
+
+* Support for four streams per INTERFACE block (not available on all
+  variants), e.g., for MIPI CSI-2 Virtual Channels (VCs)
+
+This document describes the different variants of the CIF, their hardware
+layout, as well as their representation in the media controller centric rkcif
+device driver, which is located under drivers/media/platform/rockchip/rkcif.
+
+Variants
+========
+
+Rockchip PX30 Video Input Processor (VIP)
+-----------------------------------------
+
+The PX30 Video Input Processor (VIP) features a digital video port that accepts
+parallel video data or BT.656.
+Since these protocols do not feature multiple streams, the VIP has one DMA
+engine that transfers the input video data into system memory.
+
+The rkcif driver represents this hardware variant by exposing one V4L2 subdevice
+(the DVP INTERFACE/CROP block) and one V4L2 device (the DVP DMA engine).
+
+Rockchip RK3568 Video Capture (VICAP)
+-------------------------------------
+
+The RK3568 Video Capture (VICAP) unit features a digital video port and a MIPI
+CSI-2 receiver that can receive video data independently.
+The DVP accepts parallel video data, BT.656 and BT.1120.
+Since the BT.1120 protocol may feature more than one stream, the RK3568 VICAP
+DVP features four DMA engines that can capture different streams.
+Similarly, the RK3568 VICAP MIPI CSI-2 receiver features four DMA engines to
+handle different Virtual Channels (VCs).
+
+The rkcif driver represents this hardware variant by exposing up the following
+V4L2 subdevices:
+
+* rkcif-dvp0: INTERFACE/CROP block for the DVP
+
+and the following video devices:
+
+* rkcif-dvp0-id0: The support for multiple streams on the DVP is not yet
+  implemented, as it is hard to find test hardware. Thus, this video device
+  represents the first DMA engine of the RK3568 DVP.
+
+.. kernel-figure:: rkcif-rk3568-vicap.dot
+    :alt:   Topology of the RK3568 Video Capture (VICAP) unit
+    :align: center
+
+Rockchip RK3588 Video Capture (VICAP)
+-------------------------------------
+
+The RK3588 Video Capture (VICAP) unit features a digital video port and six
+MIPI CSI-2 capture interfaces that can receive video data independently.
+The DVP accepts parallel video data, BT.656 and BT.1120.
+Since the BT.1120 protocol may feature more than one stream, the RK3588 VICAP
+DVP features four DMA engines that can capture different streams.
+Similarly, the RK3588 VICAP MIPI CSI-2 receivers feature four DMA engines each
+to handle different Virtual Channels (VCs).
+
+The rkcif driver represents this hardware variant by exposing the following
+V4L2 subdevices:
+
+* dw-mipi-csi2rx fdd30000.csi: MIPI CSI-2 receiver connected to MIPI DPHY0
+* dw-mipi-csi2rx fdd50000.csi: MIPI CSI-2 receiver connected to MIPI DPHY1
+* rkcif-mipi2: INTERFACE/CROP block for the MIPI CSI-2 receiver connected to
+  MIPI DPHY0
+* rkcif-mipi4: INTERFACE/CROP block for the MIPI CSI-2 receiver connected to
+  MIPI DPHY1
+
+and the following video devices:
+
+* rkcif-mipi2-id{0,1,2,3}: The DMA engines connected to the rkcif-mipi2
+  INTERFACE/CROP block.
+* rkcif-mipi4-id{0,1,2,3}: The DMA engines connected to the rkcif-mipi4
+  INTERFACE/CROP block.
+
+.. kernel-figure:: rkcif-rk3588-vicap.dot
+    :alt:   Topology of the RK3588 Video Capture (VICAP) unit
+    :align: center
diff --git a/Documentation/admin-guide/media/rkisp1.dot b/Documentation/admin-guide/media/rkisp1.dot
new file mode 100644
index 000000000..54c1953a6
--- /dev/null
+++ b/Documentation/admin-guide/media/rkisp1.dot
@@ -0,0 +1,18 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0 | <port1> 1} | rkisp1_isp\n/dev/v4l-subdev0 | {<port2> 2 | <port3> 3}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port2 -> n00000006:port0
+	n00000001:port2 -> n00000009:port0
+	n00000001:port3 -> n00000014 [style=bold]
+	n00000006 [label="{{<port0> 0} | rkisp1_resizer_mainpath\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000006:port1 -> n0000000c [style=bold]
+	n00000009 [label="{{<port0> 0} | rkisp1_resizer_selfpath\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000009:port1 -> n00000010 [style=bold]
+	n0000000c [label="rkisp1_mainpath\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n00000010 [label="rkisp1_selfpath\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000014 [label="rkisp1_stats\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n00000018 [label="rkisp1_params\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n00000018 -> n00000001:port1 [style=bold]
+	n0000001c [label="{{} | imx219 4-0010\n/dev/v4l-subdev3 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000001c:port0 -> n00000001:port0
+}
diff --git a/Documentation/admin-guide/media/rkisp1.rst b/Documentation/admin-guide/media/rkisp1.rst
new file mode 100644
index 000000000..6c878c714
--- /dev/null
+++ b/Documentation/admin-guide/media/rkisp1.rst
@@ -0,0 +1,204 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+=========================================
+Rockchip Image Signal Processor (rkisp1)
+=========================================
+
+Introduction
+============
+
+This file documents the driver for the Rockchip ISP1 that is part of RK3288
+and RK3399 SoCs. The driver is located under drivers/media/platform/rockchip/
+rkisp1 and uses the Media-Controller API.
+
+Revisions
+=========
+
+There exist multiple smaller revisions to this ISP that got introduced in
+later SoCs. Revisions can be found in the enum :c:type:`rkisp1_cif_isp_version`
+in the UAPI and the revision of the ISP inside the running SoC can be read
+in the field hw_revision of struct media_device_info as returned by
+ioctl MEDIA_IOC_DEVICE_INFO.
+
+Versions in use are:
+
+- RKISP1_V10: used at least in rk3288 and rk3399
+- RKISP1_V11: declared in the original vendor code, but not used
+- RKISP1_V12: used at least in rk3326 and px30
+- RKISP1_V13: used at least in rk1808
+
+Topology
+========
+.. _rkisp1_topology_graph:
+
+.. kernel-figure:: rkisp1.dot
+    :alt:   Diagram of the default media pipeline topology
+    :align: center
+
+
+The driver has 4 video devices:
+
+- rkisp1_mainpath: capture device for retrieving images, usually in higher
+  resolution.
+- rkisp1_selfpath: capture device for retrieving images.
+- rkisp1_stats: a metadata capture device that sends statistics.
+- rkisp1_params: a metadata output device that receives parameters
+  configurations from userspace.
+
+The driver has 3 subdevices:
+
+- rkisp1_resizer_mainpath: used to resize and downsample frames for the
+  mainpath capture device.
+- rkisp1_resizer_selfpath: used to resize and downsample frames for the
+  selfpath capture device.
+- rkisp1_isp: is connected to the sensor and is responsible for all the isp
+  operations.
+
+
+rkisp1_mainpath, rkisp1_selfpath - Frames Capture Video Nodes
+-------------------------------------------------------------
+Those are the `mainpath` and `selfpath` capture devices to capture frames.
+Those entities are the DMA engines that write the frames to memory.
+The selfpath video device can capture YUV/RGB formats. Its input is YUV encoded
+stream and it is able to convert it to RGB. The selfpath is not able to
+capture bayer formats.
+The mainpath can capture both bayer and YUV formats but it is not able to
+capture RGB formats.
+Both capture videos support
+the ``V4L2_CAP_IO_MC`` :ref:`capability <device-capabilities>`.
+
+
+rkisp1_resizer_mainpath, rkisp1_resizer_selfpath - Resizers Subdevices Nodes
+----------------------------------------------------------------------------
+Those are resizer entities for the mainpath and the selfpath. Those entities
+can scale the frames up and down and also change the YUV sampling (for example
+YUV4:2:2 -> YUV4:2:0). They also have cropping capability on the sink pad.
+The resizers entities can only operate on YUV:4:2:2 format
+(MEDIA_BUS_FMT_YUYV8_2X8).
+The mainpath capture device supports capturing video in bayer formats. In that
+case the resizer of the mainpath is set to 'bypass' mode - it just forward the
+frame without operating on it.
+
+rkisp1_isp - Image Signal Processing Subdevice Node
+---------------------------------------------------
+This is the isp entity. It is connected to the sensor on sink pad 0 and
+receives the frames using the CSI-2 protocol. It is responsible of configuring
+the CSI-2 protocol. It has a cropping capability on sink pad 0 that is
+connected to the sensor and on source pad 2 connected to the resizer entities.
+Cropping on sink pad 0 defines the image region from the sensor.
+Cropping on source pad 2 defines the region for the Image Stabilizer (IS).
+
+.. _rkisp1_stats:
+
+rkisp1_stats - Statistics Video Node
+------------------------------------
+The statistics video node outputs the 3A (auto focus, auto exposure and auto
+white balance) statistics, and also histogram statistics for the frames that
+are being processed by the rkisp1 to userspace applications.
+Using these data, applications can implement algorithms and re-parameterize
+the driver through the rkisp_params node to improve image quality during a
+video stream.
+The buffer format is defined by struct :c:type:`rkisp1_stat_buffer`, and
+userspace should set
+:ref:`V4L2_META_FMT_RK_ISP1_STAT_3A <v4l2-meta-fmt-rk-isp1-stat-3a>` as the
+dataformat.
+
+.. _rkisp1_params:
+
+rkisp1_params - Parameters Video Node
+-------------------------------------
+The rkisp1_params video node receives a set of parameters from userspace
+to be applied to the hardware during a video stream, allowing userspace
+to dynamically modify values such as black level, cross talk corrections
+and others.
+
+The ISP driver supports two different parameters configuration methods, the
+`fixed parameters format` or the `extensible parameters format`.
+
+When using the `fixed parameters` method the buffer format is defined by struct
+:c:type:`rkisp1_params_cfg`, and userspace should set
+:ref:`V4L2_META_FMT_RK_ISP1_PARAMS <v4l2-meta-fmt-rk-isp1-params>` as the
+dataformat.
+
+When using the `extensible parameters` method the buffer format is defined by
+struct :c:type:`rkisp1_ext_params_cfg`, and userspace should set
+:ref:`V4L2_META_FMT_RK_ISP1_EXT_PARAMS <v4l2-meta-fmt-rk-isp1-ext-params>` as
+the dataformat.
+
+Capturing Video Frames Example
+==============================
+
+In the following example, the sensor connected to pad 0 of 'rkisp1_isp' is
+imx219.
+
+The following commands can be used to capture video from the selfpath video
+node with dimension 900x800 planar format YUV 4:2:2. It uses all cropping
+capabilities possible, (see explanation right below)
+
+.. code-block:: bash
+
+	# set the links
+	"media-ctl" "-d" "platform:rkisp1" "-r"
+	"media-ctl" "-d" "platform:rkisp1" "-l" "'imx219 4-0010':0 -> 'rkisp1_isp':0 [1]"
+	"media-ctl" "-d" "platform:rkisp1" "-l" "'rkisp1_isp':2 -> 'rkisp1_resizer_selfpath':0 [1]"
+	"media-ctl" "-d" "platform:rkisp1" "-l" "'rkisp1_isp':2 -> 'rkisp1_resizer_mainpath':0 [0]"
+
+	# set format for imx219 4-0010:0
+	"media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"imx219 4-0010":0 [fmt:SRGGB10_1X10/1640x1232]'
+
+	# set format for rkisp1_isp pads:
+	"media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_isp":0 [fmt:SRGGB10_1X10/1640x1232 crop: (0,0)/1600x1200]'
+	"media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_isp":2 [fmt:YUYV8_2X8/1600x1200 crop: (0,0)/1500x1100]'
+
+	# set format for rkisp1_resizer_selfpath pads:
+	"media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_selfpath":0 [fmt:YUYV8_2X8/1500x1100 crop: (300,400)/1400x1000]'
+	"media-ctl" "-d" "platform:rkisp1" "--set-v4l2" '"rkisp1_resizer_selfpath":1 [fmt:YUYV8_2X8/900x800]'
+
+	# set format for rkisp1_selfpath:
+	"v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "-v" "width=900,height=800,"
+	"v4l2-ctl" "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "-v" "pixelformat=422P"
+
+	# start streaming:
+	v4l2-ctl "-z" "platform:rkisp1" "-d" "rkisp1_selfpath" "--stream-mmap" "--stream-count" "10"
+
+
+In the above example the sensor is configured to bayer format:
+`SRGGB10_1X10/1640x1232`. The rkisp1_isp:0 pad should be configured to the
+same mbus format and dimensions as the sensor, otherwise streaming will fail
+with 'EPIPE' error. So it is also configured to `SRGGB10_1X10/1640x1232`.
+In addition, the rkisp1_isp:0 pad is configured to cropping `(0,0)/1600x1200`.
+
+The cropping dimensions are automatically propagated to be the format of the
+isp source pad `rkisp1_isp:2`. Another cropping operation is configured on
+the isp source pad: `(0,0)/1500x1100`.
+
+The resizer's sink pad `rkisp1_resizer_selfpath` should be configured to format
+`YUYV8_2X8/1500x1100` in order to match the format on the other side of the
+link. In addition a cropping `(300,400)/1400x1000` is configured on it.
+
+The source pad of the resizer, `rkisp1_resizer_selfpath:1` is configured to
+format `YUYV8_2X8/900x800`. That means that the resizer first crop a window
+of `(300,400)/1400x100` from the received frame and then scales this window
+to dimension `900x800`.
+
+Note that the above example does not uses the stats-params control loop.
+Therefore the capture frames will not go through the 3A algorithms and
+probably won't have a good quality, and can even look dark and greenish.
+
+Configuring Quantization
+========================
+
+The driver supports limited and full range quantization on YUV formats,
+where limited is the default.
+To switch between one or the other, userspace should use the Colorspace
+Conversion API (CSC) for subdevices on source pad 2 of the
+isp (`rkisp1_isp:2`). The quantization configured on this pad is the
+quantization of the captured video frames on the mainpath and selfpath
+video nodes.
+Note that the resizer and capture entities will always report
+``V4L2_QUANTIZATION_DEFAULT`` even if the quantization is configured to full
+range on `rkisp1_isp:2`. So in order to get the configured quantization,
+application should get it from pad `rkisp1_isp:2`.
+
diff --git a/Documentation/admin-guide/media/saa7134-cardlist.rst b/Documentation/admin-guide/media/saa7134-cardlist.rst
new file mode 100644
index 000000000..3ef8fab6b
--- /dev/null
+++ b/Documentation/admin-guide/media/saa7134-cardlist.rst
@@ -0,0 +1,803 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+SAA7134 cards list
+==================
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - UNKNOWN/GENERIC
+     -
+
+   * - 1
+     - Proteus Pro [philips reference design]
+     - 1131:2001, 1131:2001
+
+   * - 2
+     - LifeView FlyVIDEO3000
+     - 5168:0138, 4e42:0138
+
+   * - 3
+     - LifeView/Typhoon FlyVIDEO2000
+     - 5168:0138, 4e42:0138
+
+   * - 4
+     - EMPRESS
+     - 1131:6752
+
+   * - 5
+     - SKNet Monster TV
+     - 1131:4e85
+
+   * - 6
+     - Tevion MD 9717
+     -
+
+   * - 7
+     - KNC One TV-Station RDS / Typhoon TV Tuner RDS
+     - 1131:fe01, 1894:fe01
+
+   * - 8
+     - Terratec Cinergy 400 TV
+     - 153b:1142
+
+   * - 9
+     - Medion 5044
+     -
+
+   * - 10
+     - Kworld/KuroutoShikou SAA7130-TVPCI
+     -
+
+   * - 11
+     - Terratec Cinergy 600 TV
+     - 153b:1143
+
+   * - 12
+     - Medion 7134
+     - 16be:0003, 16be:5000
+
+   * - 13
+     - Typhoon TV+Radio 90031
+     -
+
+   * - 14
+     - ELSA EX-VISION 300TV
+     - 1048:226b
+
+   * - 15
+     - ELSA EX-VISION 500TV
+     - 1048:226a
+
+   * - 16
+     - ASUS TV-FM 7134
+     - 1043:4842, 1043:4830, 1043:4840
+
+   * - 17
+     - AOPEN VA1000 POWER
+     - 1131:7133
+
+   * - 18
+     - BMK MPEX No Tuner
+     -
+
+   * - 19
+     - Compro VideoMate TV
+     - 185b:c100
+
+   * - 20
+     - Matrox CronosPlus
+     - 102B:48d0
+
+   * - 21
+     - 10MOONS PCI TV CAPTURE CARD
+     - 1131:2001
+
+   * - 22
+     - AverMedia M156 / Medion 2819
+     - 1461:a70b
+
+   * - 23
+     - BMK MPEX Tuner
+     -
+
+   * - 24
+     - KNC One TV-Station DVR
+     - 1894:a006
+
+   * - 25
+     - ASUS TV-FM 7133
+     - 1043:4843
+
+   * - 26
+     - Pinnacle PCTV Stereo (saa7134)
+     - 11bd:002b
+
+   * - 27
+     - Manli MuchTV M-TV002
+     -
+
+   * - 28
+     - Manli MuchTV M-TV001
+     -
+
+   * - 29
+     - Nagase Sangyo TransGear 3000TV
+     - 1461:050c
+
+   * - 30
+     - Elitegroup ECS TVP3XP FM1216 Tuner Card(PAL-BG,FM)
+     - 1019:4cb4
+
+   * - 31
+     - Elitegroup ECS TVP3XP FM1236 Tuner Card (NTSC,FM)
+     - 1019:4cb5
+
+   * - 32
+     - AVACS SmartTV
+     -
+
+   * - 33
+     - AVerMedia DVD EZMaker
+     - 1461:10ff
+
+   * - 34
+     - Noval Prime TV 7133
+     -
+
+   * - 35
+     - AverMedia AverTV Studio 305
+     - 1461:2115
+
+   * - 36
+     - UPMOST PURPLE TV
+     - 12ab:0800
+
+   * - 37
+     - Items MuchTV Plus / IT-005
+     -
+
+   * - 38
+     - Terratec Cinergy 200 TV
+     - 153b:1152
+
+   * - 39
+     - LifeView FlyTV Platinum Mini
+     - 5168:0212, 4e42:0212, 5169:1502
+
+   * - 40
+     - Compro VideoMate TV PVR/FM
+     - 185b:c100
+
+   * - 41
+     - Compro VideoMate TV Gold+
+     - 185b:c100
+
+   * - 42
+     - Sabrent SBT-TVFM (saa7130)
+     -
+
+   * - 43
+     - :Zolid Xpert TV7134
+     -
+
+   * - 44
+     - Empire PCI TV-Radio LE
+     -
+
+   * - 45
+     - Avermedia AVerTV Studio 307
+     - 1461:9715
+
+   * - 46
+     - AVerMedia Cardbus TV/Radio (E500)
+     - 1461:d6ee
+
+   * - 47
+     - Terratec Cinergy 400 mobile
+     - 153b:1162
+
+   * - 48
+     - Terratec Cinergy 600 TV MK3
+     - 153b:1158
+
+   * - 49
+     - Compro VideoMate Gold+ Pal
+     - 185b:c200
+
+   * - 50
+     - Pinnacle PCTV 300i DVB-T + PAL
+     - 11bd:002d
+
+   * - 51
+     - ProVideo PV952
+     - 1540:9524
+
+   * - 52
+     - AverMedia AverTV/305
+     - 1461:2108
+
+   * - 53
+     - ASUS TV-FM 7135
+     - 1043:4845
+
+   * - 54
+     - LifeView FlyTV Platinum FM / Gold
+     - 5168:0214, 5168:5214, 1489:0214, 5168:0304
+
+   * - 55
+     - LifeView FlyDVB-T DUO / MSI TV@nywhere Duo
+     - 5168:0306, 4E42:0306
+
+   * - 56
+     - Avermedia AVerTV 307
+     - 1461:a70a
+
+   * - 57
+     - Avermedia AVerTV GO 007 FM
+     - 1461:f31f
+
+   * - 58
+     - ADS Tech Instant TV (saa7135)
+     - 1421:0350, 1421:0351, 1421:0370, 1421:1370
+
+   * - 59
+     - Kworld/Tevion V-Stream Xpert TV PVR7134
+     -
+
+   * - 60
+     - LifeView/Typhoon/Genius FlyDVB-T Duo Cardbus
+     - 5168:0502, 4e42:0502, 1489:0502
+
+   * - 61
+     - Philips TOUGH DVB-T reference design
+     - 1131:2004
+
+   * - 62
+     - Compro VideoMate TV Gold+II
+     -
+
+   * - 63
+     - Kworld Xpert TV PVR7134
+     -
+
+   * - 64
+     - FlyTV mini Asus Digimatrix
+     - 1043:0210
+
+   * - 65
+     - V-Stream Studio TV Terminator
+     -
+
+   * - 66
+     - Yuan TUN-900 (saa7135)
+     -
+
+   * - 67
+     - Beholder BeholdTV 409 FM
+     - 0000:4091
+
+   * - 68
+     - GoTView 7135 PCI
+     - 5456:7135
+
+   * - 69
+     - Philips EUROPA V3 reference design
+     - 1131:2004
+
+   * - 70
+     - Compro Videomate DVB-T300
+     - 185b:c900
+
+   * - 71
+     - Compro Videomate DVB-T200
+     - 185b:c901
+
+   * - 72
+     - RTD Embedded Technologies VFG7350
+     - 1435:7350
+
+   * - 73
+     - RTD Embedded Technologies VFG7330
+     - 1435:7330
+
+   * - 74
+     - LifeView FlyTV Platinum Mini2
+     - 14c0:1212
+
+   * - 75
+     - AVerMedia AVerTVHD MCE A180
+     - 1461:1044
+
+   * - 76
+     - SKNet MonsterTV Mobile
+     - 1131:4ee9
+
+   * - 77
+     - Pinnacle PCTV 40i/50i/110i (saa7133)
+     - 11bd:002e
+
+   * - 78
+     - ASUSTeK P7131 Dual
+     - 1043:4862
+
+   * - 79
+     - Sedna/MuchTV PC TV Cardbus TV/Radio (ITO25 Rev:2B)
+     -
+
+   * - 80
+     - ASUS Digimatrix TV
+     - 1043:0210
+
+   * - 81
+     - Philips Tiger reference design
+     - 1131:2018
+
+   * - 82
+     - MSI TV@Anywhere plus
+     - 1462:6231, 1462:8624
+
+   * - 83
+     - Terratec Cinergy 250 PCI TV
+     - 153b:1160
+
+   * - 84
+     - LifeView FlyDVB Trio
+     - 5168:0319
+
+   * - 85
+     - AverTV DVB-T 777
+     - 1461:2c05, 1461:2c05
+
+   * - 86
+     - LifeView FlyDVB-T / Genius VideoWonder DVB-T
+     - 5168:0301, 1489:0301
+
+   * - 87
+     - ADS Instant TV Duo Cardbus PTV331
+     - 0331:1421
+
+   * - 88
+     - Tevion/KWorld DVB-T 220RF
+     - 17de:7201
+
+   * - 89
+     - ELSA EX-VISION 700TV
+     - 1048:226c
+
+   * - 90
+     - Kworld ATSC110/115
+     - 17de:7350, 17de:7352
+
+   * - 91
+     - AVerMedia A169 B
+     - 1461:7360
+
+   * - 92
+     - AVerMedia A169 B1
+     - 1461:6360
+
+   * - 93
+     - Medion 7134 Bridge #2
+     - 16be:0005
+
+   * - 94
+     - LifeView FlyDVB-T Hybrid Cardbus/MSI TV @nywhere A/D NB
+     - 5168:3306, 5168:3502, 5168:3307, 4e42:3502
+
+   * - 95
+     - LifeView FlyVIDEO3000 (NTSC)
+     - 5169:0138
+
+   * - 96
+     - Medion Md8800 Quadro
+     - 16be:0007, 16be:0008, 16be:000d
+
+   * - 97
+     - LifeView FlyDVB-S /Acorp TV134DS
+     - 5168:0300, 4e42:0300
+
+   * - 98
+     - Proteus Pro 2309
+     - 0919:2003
+
+   * - 99
+     - AVerMedia TV Hybrid A16AR
+     - 1461:2c00
+
+   * - 100
+     - Asus Europa2 OEM
+     - 1043:4860
+
+   * - 101
+     - Pinnacle PCTV 310i
+     - 11bd:002f
+
+   * - 102
+     - Avermedia AVerTV Studio 507
+     - 1461:9715
+
+   * - 103
+     - Compro Videomate DVB-T200A
+     -
+
+   * - 104
+     - Hauppauge WinTV-HVR1110 DVB-T/Hybrid
+     - 0070:6700, 0070:6701, 0070:6702, 0070:6703, 0070:6704, 0070:6705
+
+   * - 105
+     - Terratec Cinergy HT PCMCIA
+     - 153b:1172
+
+   * - 106
+     - Encore ENLTV
+     - 1131:2342, 1131:2341, 3016:2344
+
+   * - 107
+     - Encore ENLTV-FM
+     - 1131:230f
+
+   * - 108
+     - Terratec Cinergy HT PCI
+     - 153b:1175
+
+   * - 109
+     - Philips Tiger - S Reference design
+     -
+
+   * - 110
+     - Avermedia M102
+     - 1461:f31e
+
+   * - 111
+     - ASUS P7131 4871
+     - 1043:4871
+
+   * - 112
+     - ASUSTeK P7131 Hybrid
+     - 1043:4876
+
+   * - 113
+     - Elitegroup ECS TVP3XP FM1246 Tuner Card (PAL,FM)
+     - 1019:4cb6
+
+   * - 114
+     - KWorld DVB-T 210
+     - 17de:7250
+
+   * - 115
+     - Sabrent PCMCIA TV-PCB05
+     - 0919:2003
+
+   * - 116
+     - 10MOONS TM300 TV Card
+     - 1131:2304
+
+   * - 117
+     - Avermedia Super 007
+     - 1461:f01d
+
+   * - 118
+     - Beholder BeholdTV 401
+     - 0000:4016
+
+   * - 119
+     - Beholder BeholdTV 403
+     - 0000:4036
+
+   * - 120
+     - Beholder BeholdTV 403 FM
+     - 0000:4037
+
+   * - 121
+     - Beholder BeholdTV 405
+     - 0000:4050
+
+   * - 122
+     - Beholder BeholdTV 405 FM
+     - 0000:4051
+
+   * - 123
+     - Beholder BeholdTV 407
+     - 0000:4070
+
+   * - 124
+     - Beholder BeholdTV 407 FM
+     - 0000:4071
+
+   * - 125
+     - Beholder BeholdTV 409
+     - 0000:4090
+
+   * - 126
+     - Beholder BeholdTV 505 FM
+     - 5ace:5050
+
+   * - 127
+     - Beholder BeholdTV 507 FM / BeholdTV 509 FM
+     - 5ace:5070, 5ace:5090
+
+   * - 128
+     - Beholder BeholdTV Columbus TV/FM
+     - 0000:5201
+
+   * - 129
+     - Beholder BeholdTV 607 FM
+     - 5ace:6070
+
+   * - 130
+     - Beholder BeholdTV M6
+     - 5ace:6190
+
+   * - 131
+     - Twinhan Hybrid DTV-DVB 3056 PCI
+     - 1822:0022
+
+   * - 132
+     - Genius TVGO AM11MCE
+     -
+
+   * - 133
+     - NXP Snake DVB-S reference design
+     -
+
+   * - 134
+     - Medion/Creatix CTX953 Hybrid
+     - 16be:0010
+
+   * - 135
+     - MSI TV@nywhere A/D v1.1
+     - 1462:8625
+
+   * - 136
+     - AVerMedia Cardbus TV/Radio (E506R)
+     - 1461:f436
+
+   * - 137
+     - AVerMedia Hybrid TV/Radio (A16D)
+     - 1461:f936
+
+   * - 138
+     - Avermedia M115
+     - 1461:a836
+
+   * - 139
+     - Compro VideoMate T750
+     - 185b:c900
+
+   * - 140
+     - Avermedia DVB-S Pro A700
+     - 1461:a7a1
+
+   * - 141
+     - Avermedia DVB-S Hybrid+FM A700
+     - 1461:a7a2
+
+   * - 142
+     - Beholder BeholdTV H6
+     - 5ace:6290
+
+   * - 143
+     - Beholder BeholdTV M63
+     - 5ace:6191
+
+   * - 144
+     - Beholder BeholdTV M6 Extra
+     - 5ace:6193
+
+   * - 145
+     - AVerMedia MiniPCI DVB-T Hybrid M103
+     - 1461:f636, 1461:f736
+
+   * - 146
+     - ASUSTeK P7131 Analog
+     -
+
+   * - 147
+     - Asus Tiger 3in1
+     - 1043:4878
+
+   * - 148
+     - Encore ENLTV-FM v5.3
+     - 1a7f:2008
+
+   * - 149
+     - Avermedia PCI pure analog (M135A)
+     - 1461:f11d
+
+   * - 150
+     - Zogis Real Angel 220
+     -
+
+   * - 151
+     - ADS Tech Instant HDTV
+     - 1421:0380
+
+   * - 152
+     - Asus Tiger Rev:1.00
+     - 1043:4857
+
+   * - 153
+     - Kworld Plus TV Analog Lite PCI
+     - 17de:7128
+
+   * - 154
+     - Avermedia AVerTV GO 007 FM Plus
+     - 1461:f31d
+
+   * - 155
+     - Hauppauge WinTV-HVR1150 ATSC/QAM-Hybrid
+     - 0070:6706, 0070:6708
+
+   * - 156
+     - Hauppauge WinTV-HVR1120 DVB-T/Hybrid
+     - 0070:6707, 0070:6709, 0070:670a
+
+   * - 157
+     - Avermedia AVerTV Studio 507UA
+     - 1461:a11b
+
+   * - 158
+     - AVerMedia Cardbus TV/Radio (E501R)
+     - 1461:b7e9
+
+   * - 159
+     - Beholder BeholdTV 505 RDS
+     - 0000:505B
+
+   * - 160
+     - Beholder BeholdTV 507 RDS
+     - 0000:5071
+
+   * - 161
+     - Beholder BeholdTV 507 RDS
+     - 0000:507B
+
+   * - 162
+     - Beholder BeholdTV 607 FM
+     - 5ace:6071
+
+   * - 163
+     - Beholder BeholdTV 609 FM
+     - 5ace:6090
+
+   * - 164
+     - Beholder BeholdTV 609 FM
+     - 5ace:6091
+
+   * - 165
+     - Beholder BeholdTV 607 RDS
+     - 5ace:6072
+
+   * - 166
+     - Beholder BeholdTV 607 RDS
+     - 5ace:6073
+
+   * - 167
+     - Beholder BeholdTV 609 RDS
+     - 5ace:6092
+
+   * - 168
+     - Beholder BeholdTV 609 RDS
+     - 5ace:6093
+
+   * - 169
+     - Compro VideoMate S350/S300
+     - 185b:c900
+
+   * - 170
+     - AverMedia AverTV Studio 505
+     - 1461:a115
+
+   * - 171
+     - Beholder BeholdTV X7
+     - 5ace:7595
+
+   * - 172
+     - RoverMedia TV Link Pro FM
+     - 19d1:0138
+
+   * - 173
+     - Zolid Hybrid TV Tuner PCI
+     - 1131:2004
+
+   * - 174
+     - Asus Europa Hybrid OEM
+     - 1043:4847
+
+   * - 175
+     - Leadtek Winfast DTV1000S
+     - 107d:6655
+
+   * - 176
+     - Beholder BeholdTV 505 RDS
+     - 0000:5051
+
+   * - 177
+     - Hawell HW-404M7
+     -
+
+   * - 178
+     - Beholder BeholdTV H7
+     - 5ace:7190
+
+   * - 179
+     - Beholder BeholdTV A7
+     - 5ace:7090
+
+   * - 180
+     - Avermedia PCI M733A
+     - 1461:4155, 1461:4255
+
+   * - 181
+     - TechoTrend TT-budget T-3000
+     - 13c2:2804
+
+   * - 182
+     - Kworld PCI SBTVD/ISDB-T Full-Seg Hybrid
+     - 17de:b136
+
+   * - 183
+     - Compro VideoMate Vista M1F
+     - 185b:c900
+
+   * - 184
+     - Encore ENLTV-FM 3
+     - 1a7f:2108
+
+   * - 185
+     - MagicPro ProHDTV Pro2 DMB-TH/Hybrid
+     - 17de:d136
+
+   * - 186
+     - Beholder BeholdTV 501
+     - 5ace:5010
+
+   * - 187
+     - Beholder BeholdTV 503 FM
+     - 5ace:5030
+
+   * - 188
+     - Sensoray 811/911
+     - 6000:0811, 6000:0911
+
+   * - 189
+     - Kworld PC150-U
+     - 17de:a134
+
+   * - 190
+     - Asus My Cinema PS3-100
+     - 1043:48cd
+
+   * - 191
+     - Hawell HW-9004V1
+     -
+
+   * - 192
+     - AverMedia AverTV Satellite Hybrid+FM A706
+     - 1461:2055
+
+   * - 193
+     - WIS Voyager or compatible
+     - 1905:7007
+
+   * - 194
+     - AverMedia AverTV/505
+     - 1461:a10a
+
+   * - 195
+     - Leadtek Winfast TV2100 FM
+     - 107d:6f3a
+
+   * - 196
+     - SnaZio* TVPVR PRO
+     - 1779:13cf
diff --git a/Documentation/admin-guide/media/saa7134.rst b/Documentation/admin-guide/media/saa7134.rst
new file mode 100644
index 000000000..18d7cbc89
--- /dev/null
+++ b/Documentation/admin-guide/media/saa7134.rst
@@ -0,0 +1,89 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The saa7134 driver
+==================
+
+Author Gerd Hoffmann
+
+
+This is a v4l2/oss device driver for saa7130/33/34/35 based capture / TV
+boards.
+
+
+Status
+------
+
+Almost everything is working.  video, sound, tuner, radio, mpeg ts, ...
+
+As with bttv, card-specific tweaks are needed.  Check CARDLIST for a
+list of known TV cards and saa7134-cards.c for the drivers card
+configuration info.
+
+
+Build
+-----
+
+Once you pick up a Kernel source, you should configure, build,
+install and boot the new kernel.  You'll need at least
+these config options::
+
+    ./scripts/config -e PCI
+    ./scripts/config -e INPUT
+    ./scripts/config -m I2C
+    ./scripts/config -m MEDIA_SUPPORT
+    ./scripts/config -e MEDIA_PCI_SUPPORT
+    ./scripts/config -e MEDIA_ANALOG_TV_SUPPORT
+    ./scripts/config -e MEDIA_DIGITAL_TV_SUPPORT
+    ./scripts/config -e MEDIA_RADIO_SUPPORT
+    ./scripts/config -e RC_CORE
+    ./scripts/config -e MEDIA_SUBDRV_AUTOSELECT
+    ./scripts/config -m VIDEO_SAA7134
+    ./scripts/config -e SAA7134_ALSA
+    ./scripts/config -e VIDEO_SAA7134_RC
+    ./scripts/config -e VIDEO_SAA7134_DVB
+    ./scripts/config -e VIDEO_SAA7134_GO7007
+
+To build and install, you should run::
+
+    make && make modules_install && make install
+
+Once the new Kernel is booted, saa7134 driver should be loaded automatically.
+
+Depending on the card you might have to pass ``card=<nr>`` as insmod option.
+If so, please check Documentation/admin-guide/media/saa7134-cardlist.rst
+for valid choices.
+
+Once you have your card type number, you can pass a modules configuration
+via a file (usually, it is either ``/etc/modules.conf`` or some file at
+``/etc/modules-load.d/``, but the actual place depends on your
+distribution), with this content::
+
+    options saa7134 card=13 # Assuming that your card type is #13
+
+
+Changes / Fixes
+---------------
+
+Please mail to linux-media AT vger.kernel.org unified diffs against
+the linux media git tree:
+
+    https://git.linuxtv.org/media.git/
+
+This is done by committing a patch at a clone of the git tree and
+submitting the patch using ``git send-email``. Don't forget to
+describe at the lots  what it changes / which problem it fixes / whatever
+it is good for ...
+
+
+Known Problems
+--------------
+
+* The tuner for the flyvideos isn't detected automatically and the
+  default might not work for you depending on which version you have.
+  There is a ``tuner=`` insmod option to override the driver's default.
+
+Credits
+-------
+
+andrew.stevens@philips.com + werner.leeb@philips.com for providing
+saa7134 hardware specs and sample board.
diff --git a/Documentation/admin-guide/media/saa7164-cardlist.rst b/Documentation/admin-guide/media/saa7164-cardlist.rst
new file mode 100644
index 000000000..7949c09aa
--- /dev/null
+++ b/Documentation/admin-guide/media/saa7164-cardlist.rst
@@ -0,0 +1,71 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+SAA7164 cards list
+==================
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - Unknown
+     -
+
+   * - 1
+     - Generic Rev2
+     -
+
+   * - 2
+     - Generic Rev3
+     -
+
+   * - 3
+     - Hauppauge WinTV-HVR2250
+     - 0070:8880, 0070:8810
+
+   * - 4
+     - Hauppauge WinTV-HVR2200
+     - 0070:8980
+
+   * - 5
+     - Hauppauge WinTV-HVR2200
+     - 0070:8900
+
+   * - 6
+     - Hauppauge WinTV-HVR2200
+     - 0070:8901
+
+   * - 7
+     - Hauppauge WinTV-HVR2250
+     - 0070:8891, 0070:8851
+
+   * - 8
+     - Hauppauge WinTV-HVR2250
+     - 0070:88A1
+
+   * - 9
+     - Hauppauge WinTV-HVR2200
+     - 0070:8940
+
+   * - 10
+     - Hauppauge WinTV-HVR2200
+     - 0070:8953
+
+   * - 11
+     - Hauppauge WinTV-HVR2255(proto)
+     - 0070:f111
+
+   * - 12
+     - Hauppauge WinTV-HVR2255
+     - 0070:f111
+
+   * - 13
+     - Hauppauge WinTV-HVR2205
+     - 0070:f123, 0070:f120
diff --git a/Documentation/admin-guide/media/si470x.rst b/Documentation/admin-guide/media/si470x.rst
new file mode 100644
index 000000000..d53bf5f95
--- /dev/null
+++ b/Documentation/admin-guide/media/si470x.rst
@@ -0,0 +1,167 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+The Silicon Labs Si470x FM Radio Receivers driver
+=================================================
+
+Copyright |copy| 2009 Tobias Lorenz <tobias.lorenz@gmx.net>
+
+
+Information from Silicon Labs
+-----------------------------
+
+Silicon Laboratories is the manufacturer of the radio ICs, that nowadays are the
+most often used radio receivers in cell phones. Usually they are connected with
+I2C. But SiLabs also provides a reference design, which integrates this IC,
+together with a small microcontroller C8051F321, to form a USB radio.
+Part of this reference design is also a radio application in binary and source
+code. The software also contains an automatic firmware upgrade to the most
+current version. Information on these can be downloaded here:
+http://www.silabs.com/usbradio
+
+
+Supported ICs
+-------------
+
+The following ICs have a very similar register set, so that they are or will be
+supported somewhen by the driver:
+
+- Si4700: FM radio receiver
+- Si4701: FM radio receiver, RDS Support
+- Si4702: FM radio receiver
+- Si4703: FM radio receiver, RDS Support
+- Si4704: FM radio receiver, no external antenna required
+- Si4705: FM radio receiver, no external antenna required, RDS support, Dig I/O
+- Si4706: Enhanced FM RDS/TMC radio receiver, no external antenna required, RDS
+	  Support
+- Si4707: Dedicated weather band radio receiver with SAME decoder, RDS Support
+- Si4708: Smallest FM receivers
+- Si4709: Smallest FM receivers, RDS Support
+
+More information on these can be downloaded here:
+http://www.silabs.com/products/mcu/Pages/USBFMRadioRD.aspx
+
+
+Supported USB devices
+---------------------
+
+Currently the following USB radios (vendor:product) with the Silicon Labs si470x
+chips are known to work:
+
+- 10c4:818a: Silicon Labs USB FM Radio Reference Design
+- 06e1:a155: ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF)
+- 1b80:d700: KWorld USB FM Radio SnapMusic Mobile 700 (FM700)
+- 10c5:819a: Sanei Electric, Inc. FM USB Radio (sold as DealExtreme.com PCear)
+
+
+Software
+--------
+
+Testing is usually done with most application under Debian/testing:
+
+- fmtools - Utility for managing FM tuner cards
+- gnomeradio - FM-radio tuner for the GNOME desktop
+- gradio - GTK FM radio tuner
+- kradio - Comfortable Radio Application for KDE
+- radio - ncurses-based radio application
+- mplayer - The Ultimate Movie Player For Linux
+- v4l2-ctl - Collection of command line video4linux utilities
+
+For example, you can use:
+
+.. code-block:: none
+
+	v4l2-ctl -d /dev/radio0 --set-ctrl=volume=10,mute=0 --set-freq=95.21 --all
+
+There is also a library libv4l, which can be used. It's going to have a function
+for frequency seeking, either by using hardware functionality as in radio-si470x
+or by implementing a function as we currently have in every of the mentioned
+programs. Somewhen the radio programs should make use of libv4l.
+
+For processing RDS information, there is a project ongoing at:
+http://rdsd.berlios.de/
+
+There is currently no project for making TMC sentences human readable.
+
+
+Audio Listing
+-------------
+
+USB Audio is provided by the ALSA snd_usb_audio module. It is recommended to
+also select SND_USB_AUDIO, as this is required to get sound from the radio. For
+listing you have to redirect the sound, for example using one of the following
+commands. Please adjust the audio devices to your needs (/dev/dsp* and hw:x,x).
+
+If you just want to test audio (very poor quality):
+
+.. code-block:: none
+
+	cat /dev/dsp1 > /dev/dsp
+
+If you use sox + OSS try:
+
+.. code-block:: none
+
+	sox -2 --endian little -r 96000 -t oss /dev/dsp1 -t oss /dev/dsp
+
+or using sox + alsa:
+
+.. code-block:: none
+
+	sox --endian little -c 2 -S -r 96000 -t alsa hw:1 -t alsa -r 96000 hw:0
+
+If you use arts try:
+
+.. code-block:: none
+
+	arecord -D hw:1,0 -r96000 -c2 -f S16_LE | artsdsp aplay -B -
+
+If you use mplayer try:
+
+.. code-block:: none
+
+	mplayer -radio adevice=hw=1.0:arate=96000 \
+		-rawaudio rate=96000 \
+		radio://<frequency>/capture
+
+Module Parameters
+-----------------
+
+After loading the module, you still have access to some of them in the sysfs
+mount under /sys/module/radio_si470x/parameters. The contents of read-only files
+(0444) are not updated, even if space, band and de are changed using private
+video controls. The others are runtime changeable.
+
+
+Errors
+------
+
+Increase tune_timeout, if you often get -EIO errors.
+
+When timed out or band limit is reached, hw_freq_seek returns -EAGAIN.
+
+If you get any errors from snd_usb_audio, please report them to the ALSA people.
+
+
+Open Issues
+-----------
+
+V4L minor device allocation and parameter setting is not perfect. A solution is
+currently under discussion.
+
+There is an USB interface for downloading/uploading new firmware images. Support
+for it can be implemented using the request_firmware interface.
+
+There is a RDS interrupt mode. The driver is already using the same interface
+for polling RDS information, but is currently not using the interrupt mode.
+
+There is a LED interface, which can be used to override the LED control
+programmed in the firmware. This can be made available using the LED support
+functions in the kernel.
+
+
+Other useful information and links
+----------------------------------
+
+http://www.silabs.com/usbradio
diff --git a/Documentation/admin-guide/media/si4713.rst b/Documentation/admin-guide/media/si4713.rst
new file mode 100644
index 000000000..85dcf1cd2
--- /dev/null
+++ b/Documentation/admin-guide/media/si4713.rst
@@ -0,0 +1,192 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+The Silicon Labs Si4713 FM Radio Transmitter Driver
+===================================================
+
+Copyright |copy| 2009 Nokia Corporation
+
+Contact: Eduardo Valentin <eduardo.valentin@nokia.com>
+
+
+Information about the Device
+----------------------------
+
+This chip is a Silicon Labs product. It is an I2C device, currently on 0x63 address.
+Basically, it has transmission and signal noise level measurement features.
+
+The Si4713 integrates transmit functions for FM broadcast stereo transmission.
+The chip also allows integrated receive power scanning to identify low signal
+power FM channels.
+
+The chip is programmed using commands and responses. There are also several
+properties which can change the behavior of this chip.
+
+Users must comply with local regulations on radio frequency (RF) transmission.
+
+Device driver description
+-------------------------
+
+There are two modules to handle this device. One is an I2C device driver
+and the other is a platform driver.
+
+The I2C device driver exports a v4l2-subdev interface to the kernel.
+All properties can also be accessed by v4l2 extended controls interface, by
+using the v4l2-subdev calls (g_ext_ctrls, s_ext_ctrls).
+
+The platform device driver exports a v4l2 radio device interface to user land.
+So, it uses the I2C device driver as a sub device in order to send the user
+commands to the actual device. Basically it is a wrapper to the I2C device driver.
+
+Applications can use v4l2 radio API to specify frequency of operation, mute state,
+etc. But mostly of its properties will be present in the extended controls.
+
+When the v4l2 mute property is set to 1 (true), the driver will turn the chip off.
+
+Properties description
+----------------------
+
+The properties can be accessed using v4l2 extended controls.
+Here is an output from v4l2-ctl util:
+
+.. code-block:: none
+
+	/ # v4l2-ctl -d /dev/radio0 --all -L
+	Driver Info:
+		Driver name   : radio-si4713
+		Card type     : Silicon Labs Si4713 Modulator
+		Bus info      :
+		Driver version: 0
+		Capabilities  : 0x00080800
+			RDS Output
+			Modulator
+	Audio output: 0 (FM Modulator Audio Out)
+	Frequency: 1408000 (88.000000 MHz)
+	Video Standard = 0x00000000
+	Modulator:
+		Name                 : FM Modulator
+		Capabilities         : 62.5 Hz stereo rds
+		Frequency range      : 76.0 MHz - 108.0 MHz
+		Subchannel modulation: stereo+rds
+
+	User Controls
+
+				mute (bool) : default=1 value=0
+
+	FM Radio Modulator Controls
+
+		rds_signal_deviation (int)  : min=0 max=90000 step=10 default=200 value=200 flags=slider
+			rds_program_id (int)  : min=0 max=65535 step=1 default=0 value=0
+		rds_program_type (int)  : min=0 max=31 step=1 default=0 value=0
+			rds_ps_name (str)  : min=0 max=96 step=8 value='si4713  '
+			rds_radio_text (str)  : min=0 max=384 step=32 value=''
+	audio_limiter_feature_enabled (bool) : default=1 value=1
+	audio_limiter_release_time (int)  : min=250 max=102390 step=50 default=5010 value=5010 flags=slider
+		audio_limiter_deviation (int)  : min=0 max=90000 step=10 default=66250 value=66250 flags=slider
+	audio_compression_feature_enabl (bool) : default=1 value=1
+		audio_compression_gain (int)  : min=0 max=20 step=1 default=15 value=15 flags=slider
+	audio_compression_threshold (int)  : min=-40 max=0 step=1 default=-40 value=-40 flags=slider
+	audio_compression_attack_time (int)  : min=0 max=5000 step=500 default=0 value=0 flags=slider
+	audio_compression_release_time (int)  : min=100000 max=1000000 step=100000 default=1000000 value=1000000 flags=slider
+	pilot_tone_feature_enabled (bool) : default=1 value=1
+		pilot_tone_deviation (int)  : min=0 max=90000 step=10 default=6750 value=6750 flags=slider
+		pilot_tone_frequency (int)  : min=0 max=19000 step=1 default=19000 value=19000 flags=slider
+		pre_emphasis_settings (menu) : min=0 max=2 default=1 value=1
+		tune_power_level (int)  : min=0 max=120 step=1 default=88 value=88 flags=slider
+		tune_antenna_capacitor (int)  : min=0 max=191 step=1 default=0 value=110 flags=slider
+
+Here is a summary of them:
+
+* Pilot is an audible tone sent by the device.
+
+- pilot_frequency - Configures the frequency of the stereo pilot tone.
+- pilot_deviation - Configures pilot tone frequency deviation level.
+- pilot_enabled - Enables or disables the pilot tone feature.
+
+* The si4713 device is capable of applying audio compression to the
+  transmitted signal.
+
+- acomp_enabled - Enables or disables the audio dynamic range control feature.
+- acomp_gain - Sets the gain for audio dynamic range control.
+- acomp_threshold - Sets the threshold level for audio dynamic range control.
+- acomp_attack_time - Sets the attack time for audio dynamic range control.
+- acomp_release_time - Sets the release time for audio dynamic range control.
+
+* Limiter sets up the audio deviation limiter feature. Once an over deviation occurs,
+  it is possible to adjust the front-end gain of the audio input and always
+  prevent over deviation.
+
+- limiter_enabled - Enables or disables the limiter feature.
+- limiter_deviation - Configures audio frequency deviation level.
+- limiter_release_time - Sets the limiter release time.
+
+* Tuning power
+
+- power_level - Sets the output power level for signal transmission.
+  antenna_capacitor - This selects the value of antenna tuning capacitor
+  manually or automatically if set to zero.
+
+* RDS related
+
+- rds_ps_name - Sets the RDS ps name field for transmission.
+- rds_radio_text - Sets the RDS radio text for transmission.
+- rds_pi - Sets the RDS PI field for transmission.
+- rds_pty - Sets the RDS PTY field for transmission.
+
+* Region related
+
+- preemphasis - sets the preemphasis to be applied for transmission.
+
+RNL
+---
+
+This device also has an interface to measure received noise level. To do that, you should
+ioctl the device node. Here is an code of example:
+
+.. code-block:: none
+
+	int main (int argc, char *argv[])
+	{
+		struct si4713_rnl rnl;
+		int fd = open("/dev/radio0", O_RDWR);
+		int rval;
+
+		if (argc < 2)
+			return -EINVAL;
+
+		if (fd < 0)
+			return fd;
+
+		sscanf(argv[1], "%d", &rnl.frequency);
+
+		rval = ioctl(fd, SI4713_IOC_MEASURE_RNL, &rnl);
+		if (rval < 0)
+			return rval;
+
+		printf("received noise level: %d\n", rnl.rnl);
+
+		close(fd);
+	}
+
+The struct si4713_rnl and SI4713_IOC_MEASURE_RNL are defined under
+include/linux/platform_data/media/si4713.h.
+
+Stereo/Mono and RDS subchannels
+-------------------------------
+
+The device can also be configured using the available sub channels for
+transmission. To do that use S/G_MODULATOR ioctl and configure txsubchans properly.
+Refer to the V4L2 API specification for proper use of this ioctl.
+
+Testing
+-------
+Testing is usually done with v4l2-ctl utility for managing FM tuner cards.
+The tool can be found in v4l-dvb repository under v4l2-apps/util directory.
+
+Example for setting rds ps name:
+
+.. code-block:: none
+
+	# v4l2-ctl -d /dev/radio0 --set-ctrl=rds_ps_name="Dummy"
+
diff --git a/Documentation/admin-guide/media/si476x.rst b/Documentation/admin-guide/media/si476x.rst
new file mode 100644
index 000000000..c8882ee9f
--- /dev/null
+++ b/Documentation/admin-guide/media/si476x.rst
@@ -0,0 +1,160 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+
+The SI476x Driver
+=================
+
+Copyright |copy| 2013 Andrey Smirnov <andrew.smirnov@gmail.com>
+
+TODO for the driver
+-------------------
+
+- According to the SiLabs' datasheet it is possible to update the
+  firmware of the radio chip in the run-time, thus bringing it to the
+  most recent version. Unfortunately I couldn't find any mentioning of
+  the said firmware update for the old chips that I tested the driver
+  against, so for chips like that the driver only exposes the old
+  functionality.
+
+
+Parameters exposed over debugfs
+-------------------------------
+SI476x allow user to get multiple characteristics that can be very
+useful for EoL testing/RF performance estimation, parameters that have
+very little to do with V4L2 subsystem. Such parameters are exposed via
+debugfs and can be accessed via regular file I/O operations.
+
+The drivers exposes following files:
+
+* /sys/kernel/debug/<device-name>/acf
+  This file contains ACF(Automatically Controlled Features) status
+  information. The contents of the file is binary data of the
+  following layout:
+
+  .. tabularcolumns:: |p{7ex}|p{12ex}|L|
+
+  =============  ==============   ====================================
+  Offset	 Name		  Description
+  =============  ==============   ====================================
+  0x00		 blend_int	  Flag, set when stereo separation has
+				  crossed below the blend threshold
+  0x01		 hblend_int	  Flag, set when HiBlend cutoff
+				  frequency is lower than threshold
+  0x02		 hicut_int	  Flag, set when HiCut cutoff
+				  frequency is lower than threshold
+  0x03		 chbw_int	  Flag, set when channel filter
+				  bandwidth is less than threshold
+  0x04		 softmute_int	  Flag indicating that softmute
+				  attenuation has increased above
+				  softmute threshold
+  0x05		 smute		  0 - Audio is not soft muted
+				  1 - Audio is soft muted
+  0x06		 smattn		  Soft mute attenuation level in dB
+  0x07		 chbw		  Channel filter bandwidth in kHz
+  0x08		 hicut		  HiCut cutoff frequency in units of
+				  100Hz
+  0x09		 hiblend	  HiBlend cutoff frequency in units
+				  of 100 Hz
+  0x10		 pilot		  0 - Stereo pilot is not present
+				  1 - Stereo pilot is present
+  0x11		 stblend	  Stereo blend in %
+  =============  ==============   ====================================
+
+
+* /sys/kernel/debug/<device-name>/rds_blckcnt
+  This file contains statistics about RDS receptions. It's binary data
+  has the following layout:
+
+  .. tabularcolumns:: |p{7ex}|p{12ex}|L|
+
+  =============  ==============   ====================================
+  Offset	 Name		  Description
+  =============  ==============   ====================================
+  0x00		 expected	  Number of expected RDS blocks
+  0x02		 received	  Number of received RDS blocks
+  0x04		 uncorrectable	  Number of uncorrectable RDS blocks
+  =============  ==============   ====================================
+
+* /sys/kernel/debug/<device-name>/agc
+  This file contains information about parameters pertaining to
+  AGC(Automatic Gain Control)
+
+  The layout is:
+
+  .. tabularcolumns:: |p{7ex}|p{12ex}|L|
+
+  =============  ==============   ====================================
+  Offset	 Name		  Description
+  =============  ==============   ====================================
+  0x00		 mxhi		  0 - FM Mixer PD high threshold is
+				  not tripped
+				  1 - FM Mixer PD high threshold is
+				  tripped
+  0x01		 mxlo		  ditto for FM Mixer PD low
+  0x02		 lnahi		  ditto for FM LNA PD high
+  0x03		 lnalo		  ditto for FM LNA PD low
+  0x04		 fmagc1		  FMAGC1 attenuator resistance
+				  (see datasheet for more detail)
+  0x05		 fmagc2		  ditto for FMAGC2
+  0x06		 pgagain	  PGA gain in dB
+  0x07		 fmwblang	  FM/WB LNA Gain in dB
+  =============  ==============   ====================================
+
+* /sys/kernel/debug/<device-name>/rsq
+  This file contains information about parameters pertaining to
+  RSQ(Received Signal Quality)
+
+  The layout is:
+
+  .. tabularcolumns:: |p{7ex}|p{12ex}|p{60ex}|
+
+  =============  ==============   ====================================
+  Offset	 Name		  Description
+  =============  ==============   ====================================
+  0x00		 multhint	  0 - multipath value has not crossed
+				  the Multipath high threshold
+				  1 - multipath value has crossed
+				  the Multipath high threshold
+  0x01		 multlint	  ditto for Multipath low threshold
+  0x02		 snrhint	  0 - received signal's SNR has not
+				  crossed high threshold
+				  1 - received signal's SNR has
+				  crossed high threshold
+  0x03		 snrlint	  ditto for low threshold
+  0x04		 rssihint	  ditto for RSSI high threshold
+  0x05		 rssilint	  ditto for RSSI low threshold
+  0x06		 bltf		  Flag indicating if seek command
+				  reached/wrapped seek band limit
+  0x07		 snr_ready	  Indicates that SNR metrics is ready
+  0x08		 rssiready	  ditto for RSSI metrics
+  0x09		 injside	  0 - Low-side injection is being used
+				  1 - High-side injection is used
+  0x10		 afcrl		  Flag indicating if AFC rails
+  0x11		 valid		  Flag indicating if channel is valid
+  0x12		 readfreq	  Current tuned frequency
+  0x14		 freqoff	  Signed frequency offset in units of
+				  2ppm
+  0x15		 rssi		  Signed value of RSSI in dBuV
+  0x16		 snr		  Signed RF SNR in dB
+  0x17		 issi		  Signed Image Strength Signal
+				  indicator
+  0x18		 lassi		  Signed Low side adjacent Channel
+				  Strength indicator
+  0x19		 hassi		  ditto for High side
+  0x20		 mult		  Multipath indicator
+  0x21		 dev		  Frequency deviation
+  0x24		 assi		  Adjacent channel SSI
+  0x25		 usn		  Ultrasonic noise indicator
+  0x26		 pilotdev	  Pilot deviation in units of 100 Hz
+  0x27		 rdsdev		  ditto for RDS
+  0x28		 assidev	  ditto for ASSI
+  0x29		 strongdev	  Frequency deviation
+  0x30		 rdspi		  RDS PI code
+  =============  ==============   ====================================
+
+* /sys/kernel/debug/<device-name>/rsq_primary
+  This file contains information about parameters pertaining to
+  RSQ(Received Signal Quality) for primary tuner only. Layout is as
+  the one above.
diff --git a/Documentation/admin-guide/media/siano-cardlist.rst b/Documentation/admin-guide/media/siano-cardlist.rst
new file mode 100644
index 000000000..bb731a953
--- /dev/null
+++ b/Documentation/admin-guide/media/siano-cardlist.rst
@@ -0,0 +1,56 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Siano cards list
+================
+
+.. tabularcolumns:: p{13.3cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 17 16
+   :stub-columns: 0
+
+   * - Card name
+     - USB IDs
+   * - Hauppauge Catamount
+     - 2040:1700
+   * - Hauppauge Okemo-A
+     - 2040:1800
+   * - Hauppauge Okemo-B
+     - 2040:1801
+   * - Hauppauge WinTV MiniCard
+     - 2040:2000, 2040:200a, 2040:2010, 2040:2011, 2040:2019
+   * - Hauppauge WinTV MiniCard Rev 2
+     - 2040:2009
+   * - Hauppauge WinTV MiniStick
+     - 2040:5500, 2040:5510, 2040:5520, 2040:5530, 2040:5580, 2040:5590, 2040:b900, 2040:b910, 2040:b980, 2040:b990, 2040:c000, 2040:c010, 2040:c080, 2040:c090, 2040:c0a0, 2040:f5a0
+   * - Hauppauge microStick 77e
+     - 2013:0257
+   * - ONDA Data Card Digital Receiver
+     - 19D2:0078
+   * - Siano Denver (ATSC-M/H) Digital Receiver
+     - 187f:0800
+   * - Siano Denver (TDMB) Digital Receiver
+     - 187f:0700
+   * - Siano Ming Digital Receiver
+     - 187f:0310
+   * - Siano Nice Digital Receiver
+     - 187f:0202, 187f:0202
+   * - Siano Nova A Digital Receiver
+     - 187f:0200
+   * - Siano Nova B Digital Receiver
+     - 187f:0201
+   * - Siano Pele Digital Receiver
+     - 187f:0500
+   * - Siano Rio Digital Receiver
+     - 187f:0600, 3275:0080
+   * - Siano Stellar Digital Receiver
+     - 187f:0100
+   * - Siano Stellar Digital Receiver ROM
+     - 187f:0010
+   * - Siano Vega Digital Receiver
+     - 187f:0300
+   * - Siano Venice Digital Receiver
+     - 187f:0301, 187f:0301, 187f:0302
+   * - ZTE Data Card Digital Receiver
+     - 19D2:0086
diff --git a/Documentation/admin-guide/media/technisat.rst b/Documentation/admin-guide/media/technisat.rst
new file mode 100644
index 000000000..9eaa12366
--- /dev/null
+++ b/Documentation/admin-guide/media/technisat.rst
@@ -0,0 +1,100 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+How to set up the Technisat/B2C2 Flexcop devices
+================================================
+
+.. note::
+
+   This documentation is outdated.
+
+Author: Uwe Bugla <uwe.bugla@gmx.de> August 2009
+
+Find out what device you have
+-----------------------------
+
+Important Notice: The driver does NOT support Technisat USB 2 devices!
+
+First start your linux box with a shipped kernel:
+
+.. code-block:: none
+
+	lspci -vvv for a PCI device (lsusb -vvv for an USB device) will show you for example:
+	02:0b.0 Network controller: Techsan Electronics Co Ltd B2C2 FlexCopII DVB chip /
+	Technisat SkyStar2 DVB card (rev 02)
+
+	dmesg | grep frontend may show you for example:
+	DVB: registering frontend 0 (Conexant CX24123/CX24109)...
+
+Kernel compilation:
+-------------------
+
+If the Flexcop / Technisat is the only DVB / TV / Radio device in your box
+get rid of unnecessary modules and check this one:
+
+``Multimedia support`` => ``Customise analog and hybrid tuner modules to build``
+
+In this directory uncheck every driver which is activated there
+(except ``Simple tuner support`` for ATSC 3rd generation only -> see case 9 please).
+
+Then please activate:
+
+- Main module part:
+
+  ``Multimedia support`` => ``DVB/ATSC adapters`` => ``Technisat/B2C2 FlexcopII(b) and FlexCopIII adapters``
+
+  #) => ``Technisat/B2C2 Air/Sky/Cable2PC PCI`` (PCI card) or
+  #) => ``Technisat/B2C2 Air/Sky/Cable2PC USB`` (USB 1.1 adapter)
+     and for troubleshooting purposes:
+  #) => ``Enable debug for the B2C2 FlexCop drivers``
+
+- Frontend / Tuner / Demodulator module part:
+
+  ``Multimedia support`` => ``DVB/ATSC adapters``
+   => ``Customise the frontend modules to build`` ``Customise DVB frontends`` =>
+
+  - SkyStar DVB-S Revision 2.3:
+
+    #) => ``Zarlink VP310/MT312/ZL10313 based``
+    #) => ``Generic I2C PLL based tuners``
+
+  - SkyStar DVB-S Revision 2.6:
+
+    #) => ``ST STV0299 based``
+    #) => ``Generic I2C PLL based tuners``
+
+  - SkyStar DVB-S Revision 2.7:
+
+    #) => ``Samsung S5H1420 based``
+    #) => ``Integrant ITD1000 Zero IF tuner for DVB-S/DSS``
+    #) => ``ISL6421 SEC controller``
+
+  - SkyStar DVB-S Revision 2.8:
+
+    #) => ``Conexant CX24123 based``
+    #) => ``Conexant CX24113/CX24128 tuner for DVB-S/DSS``
+    #) => ``ISL6421 SEC controller``
+
+  - AirStar DVB-T card:
+
+    #) => ``Zarlink MT352 based``
+    #) => ``Generic I2C PLL based tuners``
+
+  - CableStar DVB-C card:
+
+    #) => ``ST STV0297 based``
+    #) => ``Generic I2C PLL based tuners``
+
+  - AirStar ATSC card 1st generation:
+
+    #) => ``Broadcom BCM3510``
+
+  - AirStar ATSC card 2nd generation:
+
+    #) => ``NxtWave Communications NXT2002/NXT2004 based``
+    #) => ``Generic I2C PLL based tuners``
+
+  - AirStar ATSC card 3rd generation:
+
+    #) => ``LG Electronics LGDT3302/LGDT3303 based``
+    #) ``Multimedia support`` => ``Customise analog and hybrid tuner modules to build`` => ``Simple tuner support``
+
diff --git a/Documentation/admin-guide/media/ttusb-dec.rst b/Documentation/admin-guide/media/ttusb-dec.rst
new file mode 100644
index 000000000..516bbab8a
--- /dev/null
+++ b/Documentation/admin-guide/media/ttusb-dec.rst
@@ -0,0 +1,45 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+TechnoTrend/Hauppauge DEC USB Driver
+====================================
+
+Driver Status
+-------------
+
+Supported:
+
+	- DEC2000-t
+	- DEC2450-t
+	- DEC3000-s
+	- Video Streaming
+	- Audio Streaming
+	- Section Filters
+	- Channel Zapping
+	- Hotplug firmware loader
+
+To Do:
+
+	- Tuner status information
+	- DVB network interface
+	- Streaming video PC->DEC
+	- Conax support for 2450-t
+
+Getting the Firmware
+--------------------
+To download the firmware, use the following commands:
+
+.. code-block:: none
+
+	scripts/get_dvb_firmware dec2000t
+	scripts/get_dvb_firmware dec2540t
+	scripts/get_dvb_firmware dec3000s
+
+
+Hotplug Firmware Loading
+------------------------
+
+Since 2.6 kernels, the firmware is loaded at the point that the driver module
+is loaded.
+
+Copy the three files downloaded above into the /usr/lib/hotplug/firmware or
+/lib/firmware directory (depending on configuration of firmware hotplug).
diff --git a/Documentation/admin-guide/media/tuner-cardlist.rst b/Documentation/admin-guide/media/tuner-cardlist.rst
new file mode 100644
index 000000000..65ecf48dd
--- /dev/null
+++ b/Documentation/admin-guide/media/tuner-cardlist.rst
@@ -0,0 +1,102 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Tuner cards list
+================
+
+============ =====================================================
+Tuner number Card name
+============ =====================================================
+0            Temic PAL (4002 FH5)
+1            Philips PAL_I (FI1246 and compatibles)
+2            Philips NTSC (FI1236,FM1236 and compatibles)
+3            Philips (SECAM+PAL_BG) (FI1216MF, FM1216MF, FR1216MF)
+4            NoTuner
+5            Philips PAL_BG (FI1216 and compatibles)
+6            Temic NTSC (4032 FY5)
+7            Temic PAL_I (4062 FY5)
+8            Temic NTSC (4036 FY5)
+9            Alps HSBH1
+10           Alps TSBE1
+11           Alps TSBB5
+12           Alps TSBE5
+13           Alps TSBC5
+14           Temic PAL_BG (4006FH5)
+15           Alps TSCH6
+16           Temic PAL_DK (4016 FY5)
+17           Philips NTSC_M (MK2)
+18           Temic PAL_I (4066 FY5)
+19           Temic PAL* auto (4006 FN5)
+20           Temic PAL_BG (4009 FR5) or PAL_I (4069 FR5)
+21           Temic NTSC (4039 FR5)
+22           Temic PAL/SECAM multi (4046 FM5)
+23           Philips PAL_DK (FI1256 and compatibles)
+24           Philips PAL/SECAM multi (FQ1216ME)
+25           LG PAL_I+FM (TAPC-I001D)
+26           LG PAL_I (TAPC-I701D)
+27           LG NTSC+FM (TPI8NSR01F)
+28           LG PAL_BG+FM (TPI8PSB01D)
+29           LG PAL_BG (TPI8PSB11D)
+30           Temic PAL* auto + FM (4009 FN5)
+31           SHARP NTSC_JP (2U5JF5540)
+32           Samsung PAL TCPM9091PD27
+33           MT20xx universal
+34           Temic PAL_BG (4106 FH5)
+35           Temic PAL_DK/SECAM_L (4012 FY5)
+36           Temic NTSC (4136 FY5)
+37           LG PAL (newer TAPC series)
+38           Philips PAL/SECAM multi (FM1216ME MK3)
+39           LG NTSC (newer TAPC series)
+40           HITACHI V7-J180AT
+41           Philips PAL_MK (FI1216 MK)
+42           Philips FCV1236D ATSC/NTSC dual in
+43           Philips NTSC MK3 (FM1236MK3 or FM1236/F)
+44           Philips 4 in 1 (ATI TV Wonder Pro/Conexant)
+45           Microtune 4049 FM5
+46           Panasonic VP27s/ENGE4324D
+47           LG NTSC (TAPE series)
+48           Tenna TNF 8831 BGFF)
+49           Microtune 4042 FI5 ATSC/NTSC dual in
+50           TCL 2002N
+51           Philips PAL/SECAM_D (FM 1256 I-H3)
+52           Thomson DTT 7610 (ATSC/NTSC)
+53           Philips FQ1286
+54           Philips/NXP TDA 8290/8295 + 8275/8275A/18271
+55           TCL 2002MB
+56           Philips PAL/SECAM multi (FQ1216AME MK4)
+57           Philips FQ1236A MK4
+58           Ymec TVision TVF-8531MF/8831MF/8731MF
+59           Ymec TVision TVF-5533MF
+60           Thomson DTT 761X (ATSC/NTSC)
+61           Tena TNF9533-D/IF/TNF9533-B/DF
+62           Philips TEA5767HN FM Radio
+63           Philips FMD1216ME MK3 Hybrid Tuner
+64           LG TDVS-H06xF
+65           Ymec TVF66T5-B/DFF
+66           LG TALN series
+67           Philips TD1316 Hybrid Tuner
+68           Philips TUV1236D ATSC/NTSC dual in
+69           Tena TNF 5335 and similar models
+70           Samsung TCPN 2121P30A
+71           Xceive xc2028/xc3028 tuner
+72           Thomson FE6600
+73           Samsung TCPG 6121P30A
+75           Philips TEA5761 FM Radio
+76           Xceive 5000 tuner
+77           TCL tuner MF02GIP-5N-E
+78           Philips FMD1216MEX MK3 Hybrid Tuner
+79           Philips PAL/SECAM multi (FM1216 MK5)
+80           Philips FQ1216LME MK3 PAL/SECAM w/active loopthrough
+81           Partsnic (Daewoo) PTI-5NF05
+82           Philips CU1216L
+83           NXP TDA18271
+84           Sony BTF-Pxn01Z
+85           Philips FQ1236 MK5
+86           Tena TNF5337 MFD
+87           Xceive 4000 tuner
+88           Xceive 5000C tuner
+89           Sony BTF-PG472Z PAL/SECAM
+90           Sony BTF-PK467Z NTSC-M-JP
+91           Sony BTF-PB463Z NTSC-M
+92           Silicon Labs Si2157 tuner
+93           Tena TNF931D-DFDR1
+============ =====================================================
diff --git a/Documentation/admin-guide/media/usb-cardlist.rst b/Documentation/admin-guide/media/usb-cardlist.rst
new file mode 100644
index 000000000..5f5ab0723
--- /dev/null
+++ b/Documentation/admin-guide/media/usb-cardlist.rst
@@ -0,0 +1,149 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+USB drivers
+===========
+
+The USB boards are identified by an identification called USB ID.
+
+The ``lsusb`` command allows identifying the USB IDs::
+
+    $ lsusb
+    ...
+    Bus 001 Device 015: ID 046d:082d Logitech, Inc. HD Pro Webcam C920
+    Bus 001 Device 074: ID 2040:b131 Hauppauge
+    Bus 001 Device 075: ID 2013:024f PCTV Systems nanoStick T2 290e
+    ...
+
+Newer camera devices use a standard way to expose themselves as such,
+via USB Video Class. Those cameras are automatically supported by the
+``uvc-driver``.
+
+Older cameras and TV USB devices uses USB Vendor Classes: each vendor
+defines its own way to access the device. This section contains
+card lists for such vendor-class devices.
+
+While this is not as common as on PCI, sometimes the same USB ID is used
+by different products. So, several media drivers allow passing a ``card=``
+parameter, in order to setup a card number that would match the correct
+settings for an specific product type.
+
+The current supported USB cards (not including staging drivers) are
+listed below\ [#]_.
+
+.. [#]
+
+   some of the drivers have sub-drivers, not shown at this table.
+   In particular, gspca driver has lots of sub-drivers,
+   for cameras not supported by the USB Video Class (UVC) driver,
+   as shown at :doc:`gspca card list <gspca-cardlist>`.
+
+======================  =========================================================
+Driver                  Name
+======================  =========================================================
+airspy                  AirSpy
+au0828                  Auvitek AU0828
+b2c2-flexcop-usb        Technisat/B2C2 Air/Sky/Cable2PC USB
+cx231xx                 Conexant cx231xx USB video capture
+dvb-as102               Abilis AS102 DVB receiver
+dvb-ttusb-budget        Technotrend/Hauppauge Nova - USB devices
+dvb-usb-a800            AVerMedia AverTV DVB-T USB 2.0 (A800)
+dvb-usb-af9005          Afatech AF9005 DVB-T USB1.1
+dvb-usb-af9015          Afatech AF9015 DVB-T USB2.0
+dvb-usb-af9035          Afatech AF9035 DVB-T USB2.0
+dvb-usb-anysee          Anysee DVB-T/C USB2.0
+dvb-usb-au6610          Alcor Micro AU6610 USB2.0
+dvb-usb-az6007          AzureWave 6007 and clones DVB-T/C USB2.0
+dvb-usb-az6027          Azurewave DVB-S/S2 USB2.0 AZ6027
+dvb-usb-ce6230          Intel CE6230 DVB-T USB2.0
+dvb-usb-cinergyT2       Terratec CinergyT2/qanu USB 2.0 DVB-T
+dvb-usb-cxusb           Conexant USB2.0 hybrid
+dvb-usb-dib0700         DiBcom DiB0700
+dvb-usb-dibusb-common   DiBcom DiB3000M-B
+dvb-usb-dibusb-mc       DiBcom DiB3000M-C/P
+dvb-usb-digitv          Nebula Electronics uDigiTV DVB-T USB2.0
+dvb-usb-dtt200u         WideView WT-200U and WT-220U (pen) DVB-T
+dvb-usb-dtv5100         AME DTV-5100 USB2.0 DVB-T
+dvb-usb-dvbsky          DVBSky USB
+dvb-usb-dw2102          DvbWorld & TeVii DVB-S/S2 USB2.0
+dvb-usb-ec168           E3C EC168 DVB-T USB2.0
+dvb-usb-gl861           Genesys Logic GL861 USB2.0
+dvb-usb-gp8psk          GENPIX 8PSK->USB module
+dvb-usb-lmedm04         LME DM04/QQBOX DVB-S USB2.0
+dvb-usb-m920x           Uli m920x DVB-T USB2.0
+dvb-usb-nova-t-usb2     Hauppauge WinTV-NOVA-T usb2 DVB-T USB2.0
+dvb-usb-opera           Opera1 DVB-S USB2.0 receiver
+dvb-usb-pctv452e        Pinnacle PCTV HDTV Pro USB device/TT Connect S2-3600
+dvb-usb-rtl28xxu        Realtek RTL28xxU DVB USB
+dvb-usb-technisat-usb2  Technisat DVB-S/S2 USB2.0
+dvb-usb-ttusb2          Pinnacle 400e DVB-S USB2.0
+dvb-usb-umt-010         HanfTek UMT-010 DVB-T USB2.0
+dvb_usb_v2              Support for various USB DVB devices v2
+dvb-usb-vp702x          TwinhanDTV StarBox and clones DVB-S USB2.0
+dvb-usb-vp7045          TwinhanDTV Alpha/MagicBoxII, DNTV tinyUSB2, Beetle USB2.0
+em28xx                  Empia EM28xx USB devices
+go7007                  WIS GO7007 MPEG encoder
+gspca                   Drivers for several USB Cameras
+hackrf                  HackRF
+hdpvr                   Hauppauge HD PVR
+msi2500                 Mirics MSi2500
+mxl111sf-tuner          MxL111SF DTV USB2.0
+pvrusb2                 Hauppauge WinTV-PVR USB2
+pwc                     USB Philips Cameras
+s2250                   Sensoray 2250/2251
+s2255drv                USB Sensoray 2255 video capture device
+smsusb                  Siano SMS1xxx based MDTV receiver
+ttusb_dec               Technotrend/Hauppauge USB DEC devices
+usbtv                   USBTV007 video capture
+uvcvideo                USB Video Class (UVC)
+zd1301                  ZyDAS ZD1301
+======================  =========================================================
+
+.. toctree::
+	:maxdepth: 1
+
+	au0828-cardlist
+	cx231xx-cardlist
+	em28xx-cardlist
+	siano-cardlist
+
+	gspca-cardlist
+
+	dvb-usb-dib0700-cardlist
+	dvb-usb-dibusb-mb-cardlist
+	dvb-usb-dibusb-mc-cardlist
+
+	dvb-usb-a800-cardlist
+	dvb-usb-af9005-cardlist
+	dvb-usb-az6027-cardlist
+	dvb-usb-cinergyT2-cardlist
+	dvb-usb-cxusb-cardlist
+	dvb-usb-digitv-cardlist
+	dvb-usb-dtt200u-cardlist
+	dvb-usb-dtv5100-cardlist
+	dvb-usb-dw2102-cardlist
+	dvb-usb-gp8psk-cardlist
+	dvb-usb-m920x-cardlist
+	dvb-usb-nova-t-usb2-cardlist
+	dvb-usb-opera1-cardlist
+	dvb-usb-pctv452e-cardlist
+	dvb-usb-technisat-usb2-cardlist
+	dvb-usb-ttusb2-cardlist
+	dvb-usb-umt-010-cardlist
+	dvb-usb-vp702x-cardlist
+	dvb-usb-vp7045-cardlist
+
+	dvb-usb-af9015-cardlist
+	dvb-usb-af9035-cardlist
+	dvb-usb-anysee-cardlist
+	dvb-usb-au6610-cardlist
+	dvb-usb-az6007-cardlist
+	dvb-usb-ce6230-cardlist
+	dvb-usb-dvbsky-cardlist
+	dvb-usb-ec168-cardlist
+	dvb-usb-gl861-cardlist
+	dvb-usb-lmedm04-cardlist
+	dvb-usb-mxl111sf-cardlist
+	dvb-usb-rtl28xxu-cardlist
+	dvb-usb-zd1301-cardlist
+
+	other-usb-cardlist
diff --git a/Documentation/admin-guide/media/v4l-drivers.rst b/Documentation/admin-guide/media/v4l-drivers.rst
new file mode 100644
index 000000000..4621eae9f
--- /dev/null
+++ b/Documentation/admin-guide/media/v4l-drivers.rst
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _uapi-v4l-drivers:
+
+===============================================
+Video4Linux (V4L) driver-specific documentation
+===============================================
+
+.. toctree::
+	:maxdepth: 2
+
+	amdisp4-1
+	bttv
+	c3-isp
+	cafe_ccic
+	cx88
+	fimc
+	imx
+	imx7
+	ipu3
+	ipu6-isys
+	ivtv
+	mali-c55
+	mgb4
+	omap3isp
+	philips
+	qcom_camss
+	raspberrypi-pisp-be
+	rcar-fdp1
+	rkcif
+	rkisp1
+	raspberrypi-rp1-cfe
+	saa7134
+	si470x
+	si4713
+	si476x
+	vimc
+	visl
+	vivid
diff --git a/Documentation/admin-guide/media/vimc.dot b/Documentation/admin-guide/media/vimc.dot
new file mode 100644
index 000000000..92a5bb631
--- /dev/null
+++ b/Documentation/admin-guide/media/vimc.dot
@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0
+
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{} | Sensor A\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port0 -> n00000005:port0 [style=bold]
+	n00000001:port0 -> n0000000b [style=bold]
+	n00000001 -> n00000002
+	n00000002 [label="{{} | Lens A\n/dev/v4l-subdev5 | {<port0>}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000003 [label="{{} | Sensor B\n/dev/v4l-subdev1 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000003:port0 -> n00000008:port0 [style=bold]
+	n00000003:port0 -> n0000000f [style=bold]
+	n00000003 -> n00000004
+	n00000004 [label="{{} | Lens B\n/dev/v4l-subdev6 | {<port0>}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000005 [label="{{<port0> 0} | Debayer A\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000005:port1 -> n00000015:port0
+	n00000008 [label="{{<port0> 0} | Debayer B\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000008:port1 -> n00000015:port0 [style=dashed]
+	n0000000b [label="Raw Capture 0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n0000000f [label="Raw Capture 1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000013 [label="{{} | RGB/YUV Input\n/dev/v4l-subdev4 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000013:port0 -> n00000015:port0 [style=dashed]
+	n00000015 [label="{{<port0> 0} | Scaler\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000015:port1 -> n00000018 [style=bold]
+	n00000018 [label="RGB/YUV Capture\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+}
diff --git a/Documentation/admin-guide/media/vimc.rst b/Documentation/admin-guide/media/vimc.rst
new file mode 100644
index 000000000..29d843a8d
--- /dev/null
+++ b/Documentation/admin-guide/media/vimc.rst
@@ -0,0 +1,110 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The Virtual Media Controller Driver (vimc)
+==========================================
+
+The vimc driver emulates complex video hardware using the V4L2 API and the Media
+API. It has a capture device and three subdevices: sensor, debayer and scaler.
+
+Topology
+--------
+
+The topology is hardcoded, although you could modify it in vimc-core and
+recompile the driver to achieve your own topology. This is the default topology:
+
+.. _vimc_topology_graph:
+
+.. kernel-figure:: vimc.dot
+    :alt:   Diagram of the default media pipeline topology
+    :align: center
+
+    Media pipeline graph on vimc
+
+Configuring the topology
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Each subdevice will come with its default configuration (pixelformat, height,
+width, ...). One needs to configure the topology in order to match the
+configuration on each linked subdevice to stream frames through the pipeline.
+If the configuration doesn't match, the stream will fail. The ``v4l-utils``
+package is a bundle of user-space applications, that comes with ``media-ctl`` and
+``v4l2-ctl`` that can be used to configure the vimc configuration. This sequence
+of commands fits for the default topology:
+
+.. code-block:: bash
+
+        media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
+        media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
+        media-ctl -d platform:vimc -V '"Scaler":0[fmt:RGB888_1X24/640x480]'
+        media-ctl -d platform:vimc -V '"Scaler":0[crop:(100,50)/400x150]'
+        media-ctl -d platform:vimc -V '"Scaler":1[fmt:RGB888_1X24/300x700]'
+        v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=300,height=700
+        v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
+
+Subdevices
+----------
+
+Subdevices define the behavior of an entity in the topology. Depending on the
+subdevice, the entity can have multiple pads of type source or sink.
+
+vimc-sensor:
+	Generates images in several formats using video test pattern generator.
+	Exposes:
+
+	* 1 Pad source
+
+vimc-lens:
+	Ancillary lens for a sensor. Supports auto focus control. Linked to
+	a vimc-sensor using an ancillary link. The lens supports FOCUS_ABSOLUTE
+	control.
+
+.. code-block:: bash
+
+	media-ctl -p
+	...
+	- entity 28: Lens A (0 pad, 0 link)
+			type V4L2 subdev subtype Lens flags 0
+			device node name /dev/v4l-subdev6
+	- entity 29: Lens B (0 pad, 0 link)
+			type V4L2 subdev subtype Lens flags 0
+			device node name /dev/v4l-subdev7
+	v4l2-ctl -d /dev/v4l-subdev7 -C focus_absolute
+	focus_absolute: 0
+
+
+vimc-debayer:
+	Transforms images in bayer format into a non-bayer format.
+	Exposes:
+
+	* 1 Pad sink
+	* 1 Pad source
+
+vimc-scaler:
+	Re-size the image to meet the source pad resolution. E.g.: if the sync
+	pad is configured to 360x480 and the source to 1280x720, the image will
+	be stretched to fit the source resolution. Works for any resolution
+	within the vimc limitations (even shrinking the image if necessary).
+	Exposes:
+
+	* 1 Pad sink
+	* 1 Pad source
+
+vimc-capture:
+	Exposes node /dev/videoX to allow userspace to capture the stream.
+	Exposes:
+
+	* 1 Pad sink
+	* 1 Pad source
+
+Module options
+--------------
+
+Vimc has a module parameter to configure the driver.
+
+* ``allocator=<unsigned int>``
+
+	memory allocator selection, default is 0. It specifies the way buffers
+	will be allocated.
+
+		- 0: vmalloc
+		- 1: dma-contig
diff --git a/Documentation/admin-guide/media/visl.rst b/Documentation/admin-guide/media/visl.rst
new file mode 100644
index 000000000..cd45145cd
--- /dev/null
+++ b/Documentation/admin-guide/media/visl.rst
@@ -0,0 +1,185 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The Virtual Stateless Decoder Driver (visl)
+===========================================
+
+A virtual stateless decoder device for stateless uAPI development
+purposes.
+
+This tool's objective is to help the development and testing of
+userspace applications that use the V4L2 stateless API to decode media.
+
+A userspace implementation can use visl to run a decoding loop even when
+no hardware is available or when the kernel uAPI for the codec has not
+been upstreamed yet. This can reveal bugs at an early stage.
+
+This driver can also trace the contents of the V4L2 controls submitted
+to it.  It can also dump the contents of the vb2 buffers through a
+debugfs interface. This is in many ways similar to the tracing
+infrastructure available for other popular encode/decode APIs out there
+and can help develop a userspace application by using another (working)
+one as a reference.
+
+.. note::
+
+        No actual decoding of video frames is performed by visl. The
+        V4L2 test pattern generator is used to write various debug information
+        to the capture buffers instead.
+
+Module parameters
+-----------------
+
+- visl_debug: Activates debug info, printing various debug messages through
+  dprintk. Also controls whether per-frame debug info is shown. Defaults to off.
+  Note that enabling this feature can result in slow performance through serial.
+
+- visl_transtime_ms: Simulated process time in milliseconds. Slowing down the
+  decoding speed can be useful for debugging.
+
+- visl_dprintk_frame_start, visl_dprintk_frame_nframes: Dictates a range of
+  frames where dprintk is activated. This only controls the dprintk tracing on a
+  per-frame basis. Note that printing a lot of data can be slow through serial.
+
+- keep_bitstream_buffers: Controls whether bitstream (i.e. OUTPUT) buffers are
+  kept after a decoding session. Defaults to false so as to reduce the amount of
+  clutter. keep_bitstream_buffers == false works well when live debugging the
+  client program with GDB.
+
+- bitstream_trace_frame_start, bitstream_trace_nframes: Similar to
+  visl_dprintk_frame_start, visl_dprintk_nframes, but controls the dumping of
+  buffer data through debugfs instead.
+
+- tpg_verbose: Write extra information on each output frame to ease debugging
+  the API. When set to true, the output frames are not stable for a given input
+  as some information like pointers or queue status will be added to them.
+
+What is the default use case for this driver?
+---------------------------------------------
+
+This driver can be used as a way to compare different userspace implementations.
+This assumes that a working client is run against visl and that the ftrace and
+OUTPUT buffer data is subsequently used to debug a work-in-progress
+implementation.
+
+Even though no video decoding is actually done, the output frames can be used
+against a reference for a given input, except if tpg_verbose is set to true.
+
+Depending on the tpg_verbose parameter value, information on reference frames,
+their timestamps, the status of the OUTPUT and CAPTURE queues and more can be
+read directly from the CAPTURE buffers.
+
+Supported codecs
+----------------
+
+The following codecs are supported:
+
+- FWHT
+- MPEG2
+- VP8
+- VP9
+- H.264
+- HEVC
+- AV1
+
+visl trace events
+-----------------
+The trace events are defined on a per-codec basis, e.g.:
+
+.. code-block:: bash
+
+        $ ls /sys/kernel/tracing/events/ | grep visl
+        visl_av1_controls
+        visl_fwht_controls
+        visl_h264_controls
+        visl_hevc_controls
+        visl_mpeg2_controls
+        visl_vp8_controls
+        visl_vp9_controls
+
+For example, in order to dump HEVC SPS data:
+
+.. code-block:: bash
+
+        $ echo 1 >  /sys/kernel/tracing/events/visl_hevc_controls/v4l2_ctrl_hevc_sps/enable
+
+The SPS data will be dumped to the trace buffer, i.e.:
+
+.. code-block:: bash
+
+        $ cat /sys/kernel/tracing/trace
+        video_parameter_set_id 0
+        seq_parameter_set_id 0
+        pic_width_in_luma_samples 1920
+        pic_height_in_luma_samples 1080
+        bit_depth_luma_minus8 0
+        bit_depth_chroma_minus8 0
+        log2_max_pic_order_cnt_lsb_minus4 4
+        sps_max_dec_pic_buffering_minus1 6
+        sps_max_num_reorder_pics 2
+        sps_max_latency_increase_plus1 0
+        log2_min_luma_coding_block_size_minus3 0
+        log2_diff_max_min_luma_coding_block_size 3
+        log2_min_luma_transform_block_size_minus2 0
+        log2_diff_max_min_luma_transform_block_size 3
+        max_transform_hierarchy_depth_inter 2
+        max_transform_hierarchy_depth_intra 2
+        pcm_sample_bit_depth_luma_minus1 0
+        pcm_sample_bit_depth_chroma_minus1 0
+        log2_min_pcm_luma_coding_block_size_minus3 0
+        log2_diff_max_min_pcm_luma_coding_block_size 0
+        num_short_term_ref_pic_sets 0
+        num_long_term_ref_pics_sps 0
+        chroma_format_idc 1
+        sps_max_sub_layers_minus1 0
+        flags AMP_ENABLED|SAMPLE_ADAPTIVE_OFFSET|TEMPORAL_MVP_ENABLED|STRONG_INTRA_SMOOTHING_ENABLED
+
+
+Dumping OUTPUT buffer data through debugfs
+------------------------------------------
+
+If the **VISL_DEBUGFS** Kconfig is enabled, visl will populate
+**/sys/kernel/debug/visl/bitstream** with OUTPUT buffer data according to the
+values of bitstream_trace_frame_start and bitstream_trace_nframes. This can
+highlight errors as broken clients may fail to fill the buffers properly.
+
+A single file is created for each processed OUTPUT buffer. Its name contains an
+integer that denotes the buffer sequence, i.e.:
+
+.. code-block:: c
+
+	snprintf(name, 32, "bitstream%d", run->src->sequence);
+
+Dumping the values is simply a matter of reading from the file, i.e.:
+
+For the buffer with sequence == 0:
+
+.. code-block:: bash
+
+        $ xxd /sys/kernel/debug/visl/bitstream/bitstream0
+        00000000: 2601 af04 d088 bc25 a173 0e41 a4f2 3274  &......%.s.A..2t
+        00000010: c668 cb28 e775 b4ac f53a ba60 f8fd 3aa1  .h.(.u...:.`..:.
+        00000020: 46b4 bcfc 506c e227 2372 e5f5 d7ea 579f  F...Pl.'#r....W.
+        00000030: 6371 5eb5 0eb8 23b5 ca6a 5de5 983a 19e4  cq^...#..j]..:..
+        00000040: e8c3 4320 b4ba a226 cbc1 4138 3a12 32d6  ..C ...&..A8:.2.
+        00000050: fef3 247b 3523 4e90 9682 ac8e eb0c a389  ..${5#N.........
+        00000060: ddd0 6cfc 0187 0e20 7aae b15b 1812 3d33  ..l.... z..[..=3
+        00000070: e1c5 f425 a83a 00b7 4f18 8127 3c4c aefb  ...%.:..O..'<L..
+
+For the buffer with sequence == 1:
+
+.. code-block:: bash
+
+        $ xxd /sys/kernel/debug/visl/bitstream/bitstream1
+        00000000: 0201 d021 49e1 0c40 aa11 1449 14a6 01dc  ...!I..@...I....
+        00000010: 7023 889a c8cd 2cd0 13b4 dab0 e8ca 21fe  p#....,.......!.
+        00000020: c4c8 ab4c 486e 4e2f b0df 96cc c74e 8dde  ...LHnN/.....N..
+        00000030: 8ce7 ee36 d880 4095 4d64 30a0 ff4f 0c5e  ...6..@.Md0..O.^
+        00000040: f16b a6a1 d806 ca2a 0ece a673 7bea 1f37  .k.....*...s{..7
+        00000050: 370f 5bb9 1dc4 ba21 6434 bc53 0173 cba0  7.[....!d4.S.s..
+        00000060: dfe6 bc99 01ea b6e0 346b 92b5 c8de 9f5d  ........4k.....]
+        00000070: e7cc 3484 1769 fef2 a693 a945 2c8b 31da  ..4..i.....E,.1.
+
+And so on.
+
+By default, the files are removed during STREAMOFF. This is to reduce the amount
+of clutter.
diff --git a/Documentation/admin-guide/media/vivid.rst b/Documentation/admin-guide/media/vivid.rst
new file mode 100644
index 000000000..034ca7c77
--- /dev/null
+++ b/Documentation/admin-guide/media/vivid.rst
@@ -0,0 +1,1361 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The Virtual Video Test Driver (vivid)
+=====================================
+
+This driver emulates video4linux hardware of various types: video capture, video
+output, vbi capture and output, metadata capture and output, radio receivers and
+transmitters, touch capture and a software defined radio receiver. In addition a
+simple framebuffer device is available for testing capture and output overlays.
+
+Up to 64 vivid instances can be created, each with up to 16 inputs and 16 outputs.
+
+Each input can be a webcam, TV capture device, S-Video capture device or an HDMI
+capture device. Each output can be an S-Video output device or an HDMI output
+device.
+
+These inputs and outputs act exactly as a real hardware device would behave. This
+allows you to use this driver as a test input for application development, since
+you can test the various features without requiring special hardware.
+
+This document describes the features implemented by this driver:
+
+- Support for read()/write(), MMAP, USERPTR and DMABUF streaming I/O.
+- A large list of test patterns and variations thereof
+- Working brightness, contrast, saturation and hue controls
+- Support for the alpha color component
+- Full colorspace support, including limited/full RGB range
+- All possible control types are present
+- Support for various pixel aspect ratios and video aspect ratios
+- Error injection to test what happens if errors occur
+- Supports crop/compose/scale in any combination for both input and output
+- Can emulate up to 4K resolutions
+- All Field settings are supported for testing interlaced capturing
+- Supports all standard YUV and RGB formats, including two multiplanar YUV formats
+- Raw and Sliced VBI capture and output support
+- Radio receiver and transmitter support, including RDS support
+- Software defined radio (SDR) support
+- Capture and output overlay support
+- Metadata capture and output support
+- Touch capture support
+
+These features will be described in more detail below.
+
+Configuring the driver
+----------------------
+
+By default the driver will create a single instance that has a video capture
+device with webcam, TV, S-Video and HDMI inputs, a video output device with
+S-Video and HDMI outputs, one vbi capture device, one vbi output device, one
+radio receiver device, one radio transmitter device and one SDR device.
+
+The number of instances, devices, video inputs and outputs and their types are
+all configurable using the following module options:
+
+- n_devs:
+
+	number of driver instances to create. By default set to 1. Up to 64
+	instances can be created.
+
+- node_types:
+
+	which devices should each driver instance create. An array of
+	hexadecimal values, one for each instance. The default is 0xe1d3d.
+	Each value is a bitmask with the following meaning:
+
+		- bit 0: Video Capture node
+		- bit 2-3: VBI Capture node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both
+		- bit 4: Radio Receiver node
+		- bit 5: Software Defined Radio Receiver node
+		- bit 8: Video Output node
+		- bit 10-11: VBI Output node: 0 = none, 1 = raw vbi, 2 = sliced vbi, 3 = both
+		- bit 12: Radio Transmitter node
+		- bit 16: Framebuffer for testing overlays
+		- bit 17: Metadata Capture node
+		- bit 18: Metadata Output node
+		- bit 19: Touch Capture node
+
+	So to create four instances, the first two with just one video capture
+	device, the second two with just one video output device you would pass
+	these module options to vivid:
+
+	.. code-block:: none
+
+		n_devs=4 node_types=0x1,0x1,0x100,0x100
+
+- num_inputs:
+
+	the number of inputs, one for each instance. By default 4 inputs
+	are created for each video capture device. At most 16 inputs can be created,
+	and there must be at least one.
+
+- input_types:
+
+	the input types for each instance, the default is 0xe4. This defines
+	what the type of each input is when the inputs are created for each driver
+	instance. This is a hexadecimal value with up to 16 pairs of bits, each
+	pair gives the type and bits 0-1 map to input 0, bits 2-3 map to input 1,
+	30-31 map to input 15. Each pair of bits has the following meaning:
+
+		- 00: this is a webcam input
+		- 01: this is a TV tuner input
+		- 10: this is an S-Video input
+		- 11: this is an HDMI input
+
+	So to create a video capture device with 8 inputs where input 0 is a TV
+	tuner, inputs 1-3 are S-Video inputs and inputs 4-7 are HDMI inputs you
+	would use the following module options:
+
+	.. code-block:: none
+
+		num_inputs=8 input_types=0xffa9
+
+- num_outputs:
+
+	the number of outputs, one for each instance. By default 2 outputs
+	are created for each video output device. At most 16 outputs can be
+	created, and there must be at least one.
+
+- output_types:
+
+	the output types for each instance, the default is 0x02. This defines
+	what the type of each output is when the outputs are created for each
+	driver instance. This is a hexadecimal value with up to 16 bits, each bit
+	gives the type and bit 0 maps to output 0, bit 1 maps to output 1, bit
+	15 maps to output 15. The meaning of each bit is as follows:
+
+		- 0: this is an S-Video output
+		- 1: this is an HDMI output
+
+	So to create a video output device with 8 outputs where outputs 0-3 are
+	S-Video outputs and outputs 4-7 are HDMI outputs you would use the
+	following module options:
+
+	.. code-block:: none
+
+		num_outputs=8 output_types=0xf0
+
+- vid_cap_nr:
+
+	give the desired videoX start number for each video capture device.
+	The default is -1 which will just take the first free number. This allows
+	you to map capture video nodes to specific videoX device nodes. Example:
+
+	.. code-block:: none
+
+		n_devs=4 vid_cap_nr=2,4,6,8
+
+	This will attempt to assign /dev/video2 for the video capture device of
+	the first vivid instance, video4 for the next up to video8 for the last
+	instance. If it can't succeed, then it will just take the next free
+	number.
+
+- vid_out_nr:
+
+	give the desired videoX start number for each video output device.
+	The default is -1 which will just take the first free number.
+
+- vbi_cap_nr:
+
+	give the desired vbiX start number for each vbi capture device.
+	The default is -1 which will just take the first free number.
+
+- vbi_out_nr:
+
+	give the desired vbiX start number for each vbi output device.
+	The default is -1 which will just take the first free number.
+
+- radio_rx_nr:
+
+	give the desired radioX start number for each radio receiver device.
+	The default is -1 which will just take the first free number.
+
+- radio_tx_nr:
+
+	give the desired radioX start number for each radio transmitter
+	device. The default is -1 which will just take the first free number.
+
+- sdr_cap_nr:
+
+	give the desired swradioX start number for each SDR capture device.
+	The default is -1 which will just take the first free number.
+
+- meta_cap_nr:
+
+        give the desired videoX start number for each metadata capture device.
+        The default is -1 which will just take the first free number.
+
+- meta_out_nr:
+
+        give the desired videoX start number for each metadata output device.
+        The default is -1 which will just take the first free number.
+
+- touch_cap_nr:
+
+        give the desired v4l-touchX start number for each touch capture device.
+        The default is -1 which will just take the first free number.
+
+- ccs_cap_mode:
+
+	specify the allowed video capture crop/compose/scaling combination
+	for each driver instance. Video capture devices can have any combination
+	of cropping, composing and scaling capabilities and this will tell the
+	vivid driver which of those is should emulate. By default the user can
+	select this through controls.
+
+	The value is either -1 (controlled by the user) or a set of three bits,
+	each enabling (1) or disabling (0) one of the features:
+
+	- bit 0:
+
+		Enable crop support. Cropping will take only part of the
+		incoming picture.
+	- bit 1:
+
+		Enable compose support. Composing will copy the incoming
+		picture into a larger buffer.
+
+	- bit 2:
+
+		Enable scaling support. Scaling can scale the incoming
+		picture. The scaler of the vivid driver can enlarge up
+		or down to four times the original size. The scaler is
+		very simple and low-quality. Simplicity and speed were
+		key, not quality.
+
+	Note that this value is ignored by webcam inputs: those enumerate
+	discrete framesizes and that is incompatible with cropping, composing
+	or scaling.
+
+- ccs_out_mode:
+
+	specify the allowed video output crop/compose/scaling combination
+	for each driver instance. Video output devices can have any combination
+	of cropping, composing and scaling capabilities and this will tell the
+	vivid driver which of those is should emulate. By default the user can
+	select this through controls.
+
+	The value is either -1 (controlled by the user) or a set of three bits,
+	each enabling (1) or disabling (0) one of the features:
+
+	- bit 0:
+
+		Enable crop support. Cropping will take only part of the
+		outgoing buffer.
+
+	- bit 1:
+
+		Enable compose support. Composing will copy the incoming
+		buffer into a larger picture frame.
+
+	- bit 2:
+
+		Enable scaling support. Scaling can scale the incoming
+		buffer. The scaler of the vivid driver can enlarge up
+		or down to four times the original size. The scaler is
+		very simple and low-quality. Simplicity and speed were
+		key, not quality.
+
+- multiplanar:
+
+	select whether each device instance supports multi-planar formats,
+	and thus the V4L2 multi-planar API. By default device instances are
+	single-planar.
+
+	This module option can override that for each instance. Values are:
+
+		- 1: this is a single-planar instance.
+		- 2: this is a multi-planar instance.
+
+- vivid_debug:
+
+	enable driver debugging info
+
+- no_error_inj:
+
+	if set disable the error injecting controls. This option is
+	needed in order to run a tool like v4l2-compliance. Tools like that
+	exercise all controls including a control like 'Disconnect' which
+	emulates a USB disconnect, making the device inaccessible and so
+	all tests that v4l2-compliance is doing will fail afterwards.
+
+	There may be other situations as well where you want to disable the
+	error injection support of vivid. When this option is set, then the
+	controls that select crop, compose and scale behavior are also
+	removed. Unless overridden by ccs_cap_mode and/or ccs_out_mode the
+	will default to enabling crop, compose and scaling.
+
+- allocators:
+
+	memory allocator selection, default is 0. It specifies the way buffers
+	will be allocated.
+
+		- 0: vmalloc
+		- 1: dma-contig
+
+- cache_hints:
+
+	specifies if the device should set queues' user-space cache and memory
+	consistency hint capability (V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS).
+	The hints are valid only when using MMAP streaming I/O. Default is 0.
+
+		- 0: forbid hints
+		- 1: allow hints
+
+- supports_requests:
+
+	specifies if the device should support the Request API. There are
+	three possible values, default is 1:
+
+		- 0: no request
+		- 1: supports requests
+		- 2: requires requests
+
+Taken together, all these module options allow you to precisely customize
+the driver behavior and test your application with all sorts of permutations.
+It is also very suitable to emulate hardware that is not yet available, e.g.
+when developing software for a new upcoming device.
+
+
+Video Capture
+-------------
+
+This is probably the most frequently used feature. The video capture device
+can be configured by using the module options num_inputs, input_types and
+ccs_cap_mode (see "Configuring the driver" for more detailed information),
+but by default four inputs are configured: a webcam, a TV tuner, an S-Video
+and an HDMI input, one input for each input type. Those are described in more
+detail below.
+
+Special attention has been given to the rate at which new frames become
+available. The jitter will be around 1 jiffy (that depends on the HZ
+configuration of your kernel, so usually 1/100, 1/250 or 1/1000 of a second),
+but the long-term behavior is exactly following the framerate. So a
+framerate of 59.94 Hz is really different from 60 Hz. If the framerate
+exceeds your kernel's HZ value, then you will get dropped frames, but the
+frame/field sequence counting will keep track of that so the sequence
+count will skip whenever frames are dropped.
+
+
+Webcam Input
+~~~~~~~~~~~~
+
+The webcam input supports three framesizes: 320x180, 640x360 and 1280x720. It
+supports frames per second settings of 10, 15, 25, 30, 50 and 60 fps. Which ones
+are available depends on the chosen framesize: the larger the framesize, the
+lower the maximum frames per second.
+
+The initially selected colorspace when you switch to the webcam input will be
+sRGB.
+
+
+TV and S-Video Inputs
+~~~~~~~~~~~~~~~~~~~~~
+
+The only difference between the TV and S-Video input is that the TV has a
+tuner. Otherwise they behave identically.
+
+These inputs support audio inputs as well: one TV and one Line-In. They
+both support all TV standards. If the standard is queried, then the Vivid
+controls 'Standard Signal Mode' and 'Standard' determine what
+the result will be.
+
+These inputs support all combinations of the field setting. Special care has
+been taken to faithfully reproduce how fields are handled for the different
+TV standards. This is particularly noticeable when generating a horizontally
+moving image so the temporal effect of using interlaced formats becomes clearly
+visible. For 50 Hz standards the top field is the oldest and the bottom field
+is the newest in time. For 60 Hz standards that is reversed: the bottom field
+is the oldest and the top field is the newest in time.
+
+When you start capturing in V4L2_FIELD_ALTERNATE mode the first buffer will
+contain the top field for 50 Hz standards and the bottom field for 60 Hz
+standards. This is what capture hardware does as well.
+
+Finally, for PAL/SECAM standards the first half of the top line contains noise.
+This simulates the Wide Screen Signal that is commonly placed there.
+
+The initially selected colorspace when you switch to the TV or S-Video input
+will be SMPTE-170M.
+
+The pixel aspect ratio will depend on the TV standard. The video aspect ratio
+can be selected through the 'Standard Aspect Ratio' Vivid control.
+Choices are '4x3', '16x9' which will give letterboxed widescreen video and
+'16x9 Anamorphic' which will give full screen squashed anamorphic widescreen
+video that will need to be scaled accordingly.
+
+The TV 'tuner' supports a frequency range of 44-958 MHz. Channels are available
+every 6 MHz, starting from 49.25 MHz. For each channel the generated image
+will be in color for the +/- 0.25 MHz around it, and in grayscale for
++/- 1 MHz around the channel. Beyond that it is just noise. The VIDIOC_G_TUNER
+ioctl will return 100% signal strength for +/- 0.25 MHz and 50% for +/- 1 MHz.
+It will also return correct afc values to show whether the frequency is too
+low or too high.
+
+The audio subchannels that are returned are MONO for the +/- 1 MHz range around
+a valid channel frequency. When the frequency is within +/- 0.25 MHz of the
+channel it will return either MONO, STEREO, either MONO | SAP (for NTSC) or
+LANG1 | LANG2 (for others), or STEREO | SAP.
+
+Which one is returned depends on the chosen channel, each next valid channel
+will cycle through the possible audio subchannel combinations. This allows
+you to test the various combinations by just switching channels..
+
+Finally, for these inputs the v4l2_timecode struct is filled in the
+dequeued v4l2_buffer struct.
+
+
+HDMI Input
+~~~~~~~~~~
+
+The HDMI inputs supports all CEA-861 and DMT timings, both progressive and
+interlaced, for pixelclock frequencies between 25 and 600 MHz. The field
+mode for interlaced formats is always V4L2_FIELD_ALTERNATE. For HDMI the
+field order is always top field first, and when you start capturing an
+interlaced format you will receive the top field first.
+
+The initially selected colorspace when you switch to the HDMI input or
+select an HDMI timing is based on the format resolution: for resolutions
+less than or equal to 720x576 the colorspace is set to SMPTE-170M, for
+others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings).
+
+The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it
+set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV
+standard, and for all others a 1:1 pixel aspect ratio is returned.
+
+The video aspect ratio can be selected through the 'DV Timings Aspect Ratio'
+Vivid control. Choices are 'Source Width x Height' (just use the
+same ratio as the chosen format), '4x3' or '16x9', either of which can
+result in pillarboxed or letterboxed video.
+
+For HDMI inputs it is possible to set the EDID. By default a simple EDID
+is provided. You can only set the EDID for HDMI inputs. Internally, however,
+the EDID is shared between all HDMI inputs.
+
+No interpretation is done of the EDID data with the exception of the
+physical address. See the CEC section for more details.
+
+There is a maximum of 15 HDMI inputs (if there are more, then they will be
+reduced to 15) since that's the limitation of the EDID physical address.
+
+
+Video Output
+------------
+
+The video output device can be configured by using the module options
+num_outputs, output_types and ccs_out_mode (see "Configuring the driver"
+for more detailed information), but by default two outputs are configured:
+an S-Video and an HDMI input, one output for each output type. Those are
+described in more detail below.
+
+Like with video capture the framerate is also exact in the long term.
+
+
+S-Video Output
+~~~~~~~~~~~~~~
+
+This output supports audio outputs as well: "Line-Out 1" and "Line-Out 2".
+The S-Video output supports all TV standards.
+
+This output supports all combinations of the field setting.
+
+The initially selected colorspace when you switch to the TV or S-Video input
+will be SMPTE-170M.
+
+
+HDMI Output
+~~~~~~~~~~~
+
+The HDMI output supports all CEA-861 and DMT timings, both progressive and
+interlaced, for pixelclock frequencies between 25 and 600 MHz. The field
+mode for interlaced formats is always V4L2_FIELD_ALTERNATE.
+
+The initially selected colorspace when you switch to the HDMI output or
+select an HDMI timing is based on the format resolution: for resolutions
+less than or equal to 720x576 the colorspace is set to SMPTE-170M, for
+others it is set to REC-709 (CEA-861 timings) or sRGB (VESA DMT timings).
+
+The pixel aspect ratio will depend on the HDMI timing: for 720x480 is it
+set as for the NTSC TV standard, for 720x576 it is set as for the PAL TV
+standard, and for all others a 1:1 pixel aspect ratio is returned.
+
+An HDMI output has a valid EDID which can be obtained through VIDIOC_G_EDID.
+
+There is a maximum of 15 HDMI outputs (if there are more, then they will be
+reduced to 15) since that's the limitation of the EDID physical address. See
+also the CEC section for more details.
+
+VBI Capture
+-----------
+
+There are three types of VBI capture devices: those that only support raw
+(undecoded) VBI, those that only support sliced (decoded) VBI and those that
+support both. This is determined by the node_types module option. In all
+cases the driver will generate valid VBI data: for 60 Hz standards it will
+generate Closed Caption and XDS data. The closed caption stream will
+alternate between "Hello world!" and "Closed captions test" every second.
+The XDS stream will give the current time once a minute. For 50 Hz standards
+it will generate the Wide Screen Signal which is based on the actual Video
+Aspect Ratio control setting and teletext pages 100-159, one page per frame.
+
+The VBI device will only work for the S-Video and TV inputs, it will give
+back an error if the current input is a webcam or HDMI.
+
+
+VBI Output
+----------
+
+There are three types of VBI output devices: those that only support raw
+(undecoded) VBI, those that only support sliced (decoded) VBI and those that
+support both. This is determined by the node_types module option.
+
+The sliced VBI output supports the Wide Screen Signal and the teletext signal
+for 50 Hz standards and Closed Captioning + XDS for 60 Hz standards.
+
+The VBI device will only work for the S-Video output, it will give
+back an error if the current output is HDMI.
+
+
+Radio Receiver
+--------------
+
+The radio receiver emulates an FM/AM/SW receiver. The FM band also supports RDS.
+The frequency ranges are:
+
+	- FM: 64 MHz - 108 MHz
+	- AM: 520 kHz - 1710 kHz
+	- SW: 2300 kHz - 26.1 MHz
+
+Valid channels are emulated every 1 MHz for FM and every 100 kHz for AM and SW.
+The signal strength decreases the further the frequency is from the valid
+frequency until it becomes 0% at +/- 50 kHz (FM) or 5 kHz (AM/SW) from the
+ideal frequency. The initial frequency when the driver is loaded is set to
+95 MHz.
+
+The FM receiver supports RDS as well, both using 'Block I/O' and 'Controls'
+modes. In the 'Controls' mode the RDS information is stored in read-only
+controls. These controls are updated every time the frequency is changed,
+or when the tuner status is requested. The Block I/O method uses the read()
+interface to pass the RDS blocks on to the application for decoding.
+
+The RDS signal is 'detected' for +/- 12.5 kHz around the channel frequency,
+and the further the frequency is away from the valid frequency the more RDS
+errors are randomly introduced into the block I/O stream, up to 50% of all
+blocks if you are +/- 12.5 kHz from the channel frequency. All four errors
+can occur in equal proportions: blocks marked 'CORRECTED', blocks marked
+'ERROR', blocks marked 'INVALID' and dropped blocks.
+
+The generated RDS stream contains all the standard fields contained in a
+0B group, and also radio text and the current time.
+
+The receiver supports HW frequency seek, either in Bounded mode, Wrap Around
+mode or both, which is configurable with the "Radio HW Seek Mode" control.
+
+
+Radio Transmitter
+-----------------
+
+The radio transmitter emulates an FM/AM/SW transmitter. The FM band also supports RDS.
+The frequency ranges are:
+
+	- FM: 64 MHz - 108 MHz
+	- AM: 520 kHz - 1710 kHz
+	- SW: 2300 kHz - 26.1 MHz
+
+The initial frequency when the driver is loaded is 95.5 MHz.
+
+The FM transmitter supports RDS as well, both using 'Block I/O' and 'Controls'
+modes. In the 'Controls' mode the transmitted RDS information is configured
+using controls, and in 'Block I/O' mode the blocks are passed to the driver
+using write().
+
+
+Software Defined Radio Receiver
+-------------------------------
+
+The SDR receiver has three frequency bands for the ADC tuner:
+
+	- 300 kHz
+	- 900 kHz - 2800 kHz
+	- 3200 kHz
+
+The RF tuner supports 50 MHz - 2000 MHz.
+
+The generated data contains the In-phase and Quadrature components of a
+1 kHz tone that has an amplitude of sqrt(2).
+
+
+Metadata Capture
+----------------
+
+The Metadata capture generates UVC format metadata. The PTS and SCR are
+transmitted based on the values set in vivid controls.
+
+The Metadata device will only work for the Webcam input, it will give
+back an error for all other inputs.
+
+
+Metadata Output
+---------------
+
+The Metadata output can be used to set brightness, contrast, saturation and hue.
+
+The Metadata device will only work for the Webcam output, it will give
+back an error for all other outputs.
+
+
+Touch Capture
+-------------
+
+The Touch capture generates touch patterns simulating single tap, double tap,
+triple tap, move from left to right, zoom in, zoom out, palm press (simulating
+a large area being pressed on a touchpad), and simulating 16 simultaneous
+touch points.
+
+Controls
+--------
+
+Different devices support different controls. The sections below will describe
+each control and which devices support them.
+
+
+User Controls - Test Controls
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Button, Boolean, Integer 32 Bits, Integer 64 Bits, Menu, String, Bitmask and
+Integer Menu are controls that represent all possible control types. The Menu
+control and the Integer Menu control both have 'holes' in their menu list,
+meaning that one or more menu items return EINVAL when VIDIOC_QUERYMENU is called.
+Both menu controls also have a non-zero minimum control value.  These features
+allow you to check if your application can handle such things correctly.
+These controls are supported for every device type.
+
+
+User Controls - Video Capture
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following controls are specific to video capture.
+
+The Brightness, Contrast, Saturation and Hue controls actually work and are
+standard. There is one special feature with the Brightness control: each
+video input has its own brightness value, so changing input will restore
+the brightness for that input. In addition, each video input uses a different
+brightness range (minimum and maximum control values). Switching inputs will
+cause a control event to be sent with the V4L2_EVENT_CTRL_CH_RANGE flag set.
+This allows you to test controls that can change their range.
+
+The 'Gain, Automatic' and Gain controls can be used to test volatile controls:
+if 'Gain, Automatic' is set, then the Gain control is volatile and changes
+constantly. If 'Gain, Automatic' is cleared, then the Gain control is a normal
+control.
+
+The 'Horizontal Flip' and 'Vertical Flip' controls can be used to flip the
+image. These combine with the 'Sensor Flipped Horizontally/Vertically' Vivid
+controls.
+
+The 'Alpha Component' control can be used to set the alpha component for
+formats containing an alpha channel.
+
+
+User Controls - Audio
+~~~~~~~~~~~~~~~~~~~~~
+
+The following controls are specific to video capture and output and radio
+receivers and transmitters.
+
+The 'Volume' and 'Mute' audio controls are typical for such devices to
+control the volume and mute the audio. They don't actually do anything in
+the vivid driver.
+
+
+Vivid Controls
+~~~~~~~~~~~~~~
+
+These vivid custom controls control the image generation, error injection, etc.
+
+
+Test Pattern Controls
+^^^^^^^^^^^^^^^^^^^^^
+
+The Test Pattern Controls are all specific to video capture.
+
+- Test Pattern:
+
+	selects which test pattern to use. Use the CSC Colorbar for
+	testing colorspace conversions: the colors used in that test pattern
+	map to valid colors in all colorspaces. The colorspace conversion
+	is disabled for the other test patterns.
+
+- OSD Text Mode:
+
+	selects whether the text superimposed on the
+	test pattern should be shown, and if so, whether only counters should
+	be displayed or the full text.
+
+- Horizontal Movement:
+
+	selects whether the test pattern should
+	move to the left or right and at what speed.
+
+- Vertical Movement:
+
+	does the same for the vertical direction.
+
+- Show Border:
+
+	show a two-pixel wide border at the edge of the actual image,
+	excluding letter or pillarboxing.
+
+- Show Square:
+
+	show a square in the middle of the image. If the image is
+	displayed with the correct pixel and image aspect ratio corrections,
+	then the width and height of the square on the monitor should be
+	the same.
+
+- Insert SAV Code in Image:
+
+	adds a SAV (Start of Active Video) code to the image.
+	This can be used to check if such codes in the image are inadvertently
+	interpreted instead of being ignored.
+
+- Insert EAV Code in Image:
+
+	does the same for the EAV (End of Active Video) code.
+
+- Insert Video Guard Band
+
+	adds 4 columns of pixels with the HDMI Video Guard Band code at the
+	left hand side of the image. This only works with 3 or 4 byte RGB pixel
+	formats. The RGB pixel value 0xab/0x55/0xab turns out to be equivalent
+	to the HDMI Video Guard Band code that precedes each active video line
+	(see section 5.2.2.1 in the HDMI 1.3 Specification). To test if a video
+	receiver has correct HDMI Video Guard Band processing, enable this
+	control and then move the image to the left hand side of the screen.
+	That will result in video lines that start with multiple pixels that
+	have the same value as the Video Guard Band that precedes them.
+	Receivers that will just keep skipping Video Guard Band values will
+	now fail and either loose sync or these video lines will shift.
+
+
+Capture Feature Selection Controls
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These controls are all specific to video capture.
+
+- Sensor Flipped Horizontally:
+
+	the image is flipped horizontally and the
+	V4L2_IN_ST_HFLIP input status flag is set. This emulates the case where
+	a sensor is for example mounted upside down.
+
+- Sensor Flipped Vertically:
+
+	the image is flipped vertically and the
+	V4L2_IN_ST_VFLIP input status flag is set. This emulates the case where
+	a sensor is for example mounted upside down.
+
+- Standard Aspect Ratio:
+
+	selects if the image aspect ratio as used for the TV or
+	S-Video input should be 4x3, 16x9 or anamorphic widescreen. This may
+	introduce letterboxing.
+
+- DV Timings Aspect Ratio:
+
+	selects if the image aspect ratio as used for the HDMI
+	input should be the same as the source width and height ratio, or if
+	it should be 4x3 or 16x9. This may introduce letter or pillarboxing.
+
+- Timestamp Source:
+
+	selects when the timestamp for each buffer is taken.
+
+- Colorspace:
+
+	selects which colorspace should be used when generating the image.
+	This only applies if the CSC Colorbar test pattern is selected,
+	otherwise the test pattern will go through unconverted.
+	This behavior is also what you want, since a 75% Colorbar
+	should really have 75% signal intensity and should not be affected
+	by colorspace conversions.
+
+	Changing the colorspace will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a detected colorspace change.
+
+- Transfer Function:
+
+	selects which colorspace transfer function should be used when
+	generating an image. This only applies if the CSC Colorbar test pattern is
+	selected, otherwise the test pattern will go through unconverted.
+	This behavior is also what you want, since a 75% Colorbar
+	should really have 75% signal intensity and should not be affected
+	by colorspace conversions.
+
+	Changing the transfer function will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a detected colorspace change.
+
+- Y'CbCr Encoding:
+
+	selects which Y'CbCr encoding should be used when generating
+	a Y'CbCr image.	This only applies if the format is set to a Y'CbCr format
+	as opposed to an RGB format.
+
+	Changing the Y'CbCr encoding will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a detected colorspace change.
+
+- Quantization:
+
+	selects which quantization should be used for the RGB or Y'CbCr
+	encoding when generating the test pattern.
+
+	Changing the quantization will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a detected colorspace change.
+
+- Limited RGB Range (16-235):
+
+	selects if the RGB range of the HDMI source should
+	be limited or full range. This combines with the Digital Video 'Rx RGB
+	Quantization Range' control and can be used to test what happens if
+	a source provides you with the wrong quantization range information.
+	See the description of that control for more details.
+
+- Apply Alpha To Red Only:
+
+	apply the alpha channel as set by the 'Alpha Component'
+	user control to the red color of the test pattern only.
+
+- Enable Capture Cropping:
+
+	enables crop support. This control is only present if
+	the ccs_cap_mode module option is set to the default value of -1 and if
+	the no_error_inj module option is set to 0 (the default).
+
+- Enable Capture Composing:
+
+	enables composing support. This control is only
+	present if the ccs_cap_mode module option is set to the default value of
+	-1 and if the no_error_inj module option is set to 0 (the default).
+
+- Enable Capture Scaler:
+
+	enables support for a scaler (maximum 4 times upscaling
+	and downscaling). This control is only present if the ccs_cap_mode
+	module option is set to the default value of -1 and if the no_error_inj
+	module option is set to 0 (the default).
+
+- Maximum EDID Blocks:
+
+	determines how many EDID blocks the driver supports.
+	Note that the vivid driver does not actually interpret new EDID
+	data, it just stores it. It allows for up to 256 EDID blocks
+	which is the maximum supported by the standard.
+
+- Fill Percentage of Frame:
+
+	can be used to draw only the top X percent
+	of the image. Since each frame has to be drawn by the driver, this
+	demands a lot of the CPU. For large resolutions this becomes
+	problematic. By drawing only part of the image this CPU load can
+	be reduced.
+
+
+Output Feature Selection Controls
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These controls are all specific to video output.
+
+- Enable Output Cropping:
+
+	enables crop support. This control is only present if
+	the ccs_out_mode module option is set to the default value of -1 and if
+	the no_error_inj module option is set to 0 (the default).
+
+- Enable Output Composing:
+
+	enables composing support. This control is only
+	present if the ccs_out_mode module option is set to the default value of
+	-1 and if the no_error_inj module option is set to 0 (the default).
+
+- Enable Output Scaler:
+
+	enables support for a scaler (maximum 4 times upscaling
+	and downscaling). This control is only present if the ccs_out_mode
+	module option is set to the default value of -1 and if the no_error_inj
+	module option is set to 0 (the default).
+
+
+Error Injection Controls
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The following two controls are only valid for video and vbi capture.
+
+- Standard Signal Mode:
+
+	selects the behavior of VIDIOC_QUERYSTD: what should it return?
+
+	Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a changed input condition (e.g. a cable
+	was plugged in or out).
+
+- Standard:
+
+	selects the standard that VIDIOC_QUERYSTD should return if the
+	previous control is set to "Selected Standard".
+
+	Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a changed input standard.
+
+
+The following two controls are only valid for video capture.
+
+- DV Timings Signal Mode:
+
+	selects the behavior of VIDIOC_QUERY_DV_TIMINGS: what
+	should it return?
+
+	Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates a changed input condition (e.g. a cable
+	was plugged in or out).
+
+- DV Timings:
+
+	selects the timings the VIDIOC_QUERY_DV_TIMINGS should return
+	if the previous control is set to "Selected DV Timings".
+
+	Changing this control will result in the V4L2_EVENT_SOURCE_CHANGE
+	to be sent since it emulates changed input timings.
+
+
+The following controls are only present if the no_error_inj module option
+is set to 0 (the default). These controls are valid for video and vbi
+capture and output streams and for the SDR capture device except for the
+Disconnect control which is valid for all devices.
+
+- Wrap Sequence Number:
+
+	test what happens when you wrap the sequence number in
+	struct v4l2_buffer around.
+
+- Wrap Timestamp:
+
+	test what happens when you wrap the timestamp in struct
+	v4l2_buffer around.
+
+- Percentage of Dropped Buffers:
+
+	sets the percentage of buffers that
+	are never returned by the driver (i.e., they are dropped).
+
+- Disconnect:
+
+	emulates a USB disconnect. The device will act as if it has
+	been disconnected. Only after all open filehandles to the device
+	node have been closed will the device become 'connected' again.
+
+- Inject V4L2_BUF_FLAG_ERROR:
+
+	when pressed, the next frame returned by
+	the driver will have the error flag set (i.e. the frame is marked
+	corrupt).
+
+- Inject VIDIOC_REQBUFS Error:
+
+	when pressed, the next REQBUFS or CREATE_BUFS
+	ioctl call will fail with an error. To be precise: the videobuf2
+	queue_setup() op will return -EINVAL.
+
+- Inject VIDIOC_QBUF Error:
+
+	when pressed, the next VIDIOC_QBUF or
+	VIDIOC_PREPARE_BUFFER ioctl call will fail with an error. To be
+	precise: the videobuf2 buf_prepare() op will return -EINVAL.
+
+- Inject VIDIOC_STREAMON Error:
+
+	when pressed, the next VIDIOC_STREAMON ioctl
+	call will fail with an error. To be precise: the videobuf2
+	start_streaming() op will return -EINVAL.
+
+- Inject Fatal Streaming Error:
+
+	when pressed, the streaming core will be
+	marked as having suffered a fatal error, the only way to recover
+	from that is to stop streaming. To be precise: the videobuf2
+	vb2_queue_error() function is called.
+
+
+VBI Raw Capture Controls
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+- Interlaced VBI Format:
+
+	if set, then the raw VBI data will be interlaced instead
+	of providing it grouped by field.
+
+
+Digital Video Controls
+~~~~~~~~~~~~~~~~~~~~~~
+
+- Rx RGB Quantization Range:
+
+	sets the RGB quantization detection of the HDMI
+	input. This combines with the Vivid 'Limited RGB Range (16-235)'
+	control and can be used to test what happens if a source provides
+	you with the wrong quantization range information. This can be tested
+	by selecting an HDMI input, setting this control to Full or Limited
+	range and selecting the opposite in the 'Limited RGB Range (16-235)'
+	control. The effect is easy to see if the 'Gray Ramp' test pattern
+	is selected.
+
+- Tx RGB Quantization Range:
+
+	sets the RGB quantization detection of the HDMI
+	output. It is currently not used for anything in vivid, but most HDMI
+	transmitters would typically have this control.
+
+- Transmit Mode:
+
+	sets the transmit mode of the HDMI output to HDMI or DVI-D. This
+	affects the reported colorspace since DVI_D outputs will always use
+	sRGB.
+
+
+FM Radio Receiver Controls
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- RDS Reception:
+
+	set if the RDS receiver should be enabled.
+
+- RDS Program Type:
+
+
+- RDS PS Name:
+
+
+- RDS Radio Text:
+
+
+- RDS Traffic Announcement:
+
+
+- RDS Traffic Program:
+
+
+- RDS Music:
+
+	these are all read-only controls. If RDS Rx I/O Mode is set to
+	"Block I/O", then they are inactive as well. If RDS Rx I/O Mode is set
+	to "Controls", then these controls report the received RDS data.
+
+.. note::
+	The vivid implementation of this is pretty basic: they are only
+	updated when you set a new frequency or when you get the tuner status
+	(VIDIOC_G_TUNER).
+
+- Radio HW Seek Mode:
+
+	can be one of "Bounded", "Wrap Around" or "Both". This
+	determines if VIDIOC_S_HW_FREQ_SEEK will be bounded by the frequency
+	range or wrap-around or if it is selectable by the user.
+
+- Radio Programmable HW Seek:
+
+	if set, then the user can provide the lower and
+	upper bound of the HW Seek. Otherwise the frequency range boundaries
+	will be used.
+
+- Generate RBDS Instead of RDS:
+
+	if set, then generate RBDS (the US variant of
+	RDS) data instead of RDS (European-style RDS). This affects only the
+	PICODE and PTY codes.
+
+- RDS Rx I/O Mode:
+
+	this can be "Block I/O" where the RDS blocks have to be read()
+	by the application, or "Controls" where the RDS data is provided by
+	the RDS controls mentioned above.
+
+
+FM Radio Modulator Controls
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- RDS Program ID:
+
+
+- RDS Program Type:
+
+
+- RDS PS Name:
+
+
+- RDS Radio Text:
+
+
+- RDS Stereo:
+
+
+- RDS Artificial Head:
+
+
+- RDS Compressed:
+
+
+- RDS Dynamic PTY:
+
+
+- RDS Traffic Announcement:
+
+
+- RDS Traffic Program:
+
+
+- RDS Music:
+
+	these are all controls that set the RDS data that is transmitted by
+	the FM modulator.
+
+- RDS Tx I/O Mode:
+
+	this can be "Block I/O" where the application has to use write()
+	to pass the RDS blocks to the driver, or "Controls" where the RDS data
+	is Provided by the RDS controls mentioned above.
+
+Metadata Capture Controls
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Generate PTS
+
+        if set, then the generated metadata stream contains Presentation timestamp.
+
+- Generate SCR
+
+        if set, then the generated metadata stream contains Source Clock information.
+
+
+Video, Sliced VBI and HDMI CEC Looping
+--------------------------------------
+
+Video Looping functionality is supported for devices created by the same
+vivid driver instance, as well as across multiple instances of the vivid driver.
+The vivid driver supports looping of video and Sliced VBI data between an S-Video output
+and an S-Video input. It also supports looping of video and HDMI CEC data between an
+HDMI output and an HDMI input.
+
+To enable looping, set the 'HDMI/S-Video XXX-N Is Connected To' control(s) to select
+whether an input uses the Test Pattern Generator, or is disconnected, or is connected
+to an output. An input can be connected to an output from any vivid instance.
+The inputs and outputs are numbered XXX-N where XXX is the vivid instance number
+(see module option n_devs). If there is only one vivid instance (the default), then
+XXX will be 000. And N is the Nth S-Video/HDMI input or output of that instance.
+If vivid is loaded without module options, then you can connect the S-Video 000-0 input
+to the S-Video 000-0 output, or the HDMI 000-0 input to the HDMI 000-0 output.
+This is the equivalent of connecting or disconnecting a cable between an input and an
+output in a physical device.
+
+If an 'HDMI/S-Video XXX-N Is Connected To' control selected an output, then the video
+output will be looped to the video input provided that:
+
+- the currently selected input matches the input indicated by the control name.
+
+- in the vivid instance of the output connector, the currently selected output matches
+  the output indicated by the control's value.
+
+- the video resolution of the video input must match that of the video output.
+  So it is not possible to loop a 50 Hz (720x576) S-Video output to a 60 Hz
+  (720x480) S-Video input, or a 720p60 HDMI output to a 1080p30 input.
+
+- the pixel formats must be identical on both sides. Otherwise the driver would
+  have to do pixel format conversion as well, and that's taking things too far.
+
+- the field settings must be identical on both sides. Same reason as above:
+  requiring the driver to convert from one field format to another complicated
+  matters too much. This also prohibits capturing with 'Field Top' or 'Field
+  Bottom' when the output video is set to 'Field Alternate'. This combination,
+  while legal, became too complicated to support. Both sides have to be 'Field
+  Alternate' for this to work. Also note that for this specific case the
+  sequence and field counting in struct v4l2_buffer on the capture side may not
+  be 100% accurate.
+
+- field settings V4L2_FIELD_SEQ_TB/BT are not supported. While it is possible to
+  implement this, it would mean a lot of work to get this right. Since these
+  field values are rarely used the decision was made not to implement this for
+  now.
+
+- on the input side the "Standard Signal Mode" for the S-Video input or the
+  "DV Timings Signal Mode" for the HDMI input should be configured so that a
+  valid signal is passed to the video input.
+
+If any condition is not valid, then the 'Noise' test pattern is shown.
+
+The framerates do not have to match, although this might change in the future.
+
+By default you will see the OSD text superimposed on top of the looped video.
+This can be turned off by changing the "OSD Text Mode" control of the video
+capture device.
+
+For VBI looping to work all of the above must be valid and in addition the vbi
+output must be configured for sliced VBI. The VBI capture side can be configured
+for either raw or sliced VBI. Note that at the moment only CC/XDS (60 Hz formats)
+and WSS (50 Hz formats) VBI data is looped. Teletext VBI data is not looped.
+
+
+Radio & RDS Looping
+-------------------
+
+The vivid driver supports looping of RDS output to RDS input.
+
+Since radio is wireless this looping always happens if the radio receiver
+frequency is close to the radio transmitter frequency. In that case the radio
+transmitter will 'override' the emulated radio stations.
+
+RDS looping is currently supported only between devices created by the same
+vivid driver instance.
+
+As mentioned in the "Radio Receiver" section, the radio receiver emulates
+stations at regular frequency intervals. Depending on the frequency of the
+radio receiver a signal strength value is calculated (this is returned by
+VIDIOC_G_TUNER). However, it will also look at the frequency set by the radio
+transmitter and if that results in a higher signal strength than the settings
+of the radio transmitter will be used as if it was a valid station. This also
+includes the RDS data (if any) that the transmitter 'transmits'. This is
+received faithfully on the receiver side. Note that when the driver is loaded
+the frequencies of the radio receiver and transmitter are not identical, so
+initially no looping takes place.
+
+
+Cropping, Composing, Scaling
+----------------------------
+
+This driver supports cropping, composing and scaling in any combination. Normally
+which features are supported can be selected through the Vivid controls,
+but it is also possible to hardcode it when the module is loaded through the
+ccs_cap_mode and ccs_out_mode module options. See "Configuring the driver" on
+the details of these module options.
+
+This allows you to test your application for all these variations.
+
+Note that the webcam input never supports cropping, composing or scaling. That
+only applies to the TV/S-Video/HDMI inputs and outputs. The reason is that
+webcams, including this virtual implementation, normally use
+VIDIOC_ENUM_FRAMESIZES to list a set of discrete framesizes that it supports.
+And that does not combine with cropping, composing or scaling. This is
+primarily a limitation of the V4L2 API which is carefully reproduced here.
+
+The minimum and maximum resolutions that the scaler can achieve are 16x16 and
+(4096 * 4) x (2160 x 4), but it can only scale up or down by a factor of 4 or
+less. So for a source resolution of 1280x720 the minimum the scaler can do is
+320x180 and the maximum is 5120x2880. You can play around with this using the
+qv4l2 test tool and you will see these dependencies.
+
+This driver also supports larger 'bytesperline' settings, something that
+VIDIOC_S_FMT allows but that few drivers implement.
+
+The scaler is a simple scaler that uses the Coarse Bresenham algorithm. It's
+designed for speed and simplicity, not quality.
+
+If the combination of crop, compose and scaling allows it, then it is possible
+to change crop and compose rectangles on the fly.
+
+
+Formats
+-------
+
+The driver supports all the regular packed and planar 4:4:4, 4:2:2 and 4:2:0
+YUYV formats, 8, 16, 24 and 32 RGB packed formats and various multiplanar
+formats.
+
+The alpha component can be set through the 'Alpha Component' User control
+for those formats that support it. If the 'Apply Alpha To Red Only' control
+is set, then the alpha component is only used for the color red and set to
+0 otherwise.
+
+The driver has to be configured to support the multiplanar formats. By default
+the driver instances are single-planar. This can be changed by setting the
+multiplanar module option, see "Configuring the driver" for more details on that
+option.
+
+If the driver instance is using the multiplanar formats/API, then the first
+single planar format (YUYV) and the multiplanar NV16M and NV61M formats the
+will have a plane that has a non-zero data_offset of 128 bytes. It is rare for
+data_offset to be non-zero, so this is a useful feature for testing applications.
+
+Video output will also honor any data_offset that the application set.
+
+
+Output Overlay
+--------------
+
+Note: output overlays are primarily implemented in order to test the existing
+V4L2 output overlay API. Whether this API should be used for new drivers is
+questionable.
+
+This driver has support for an output overlay and is capable of:
+
+	- bitmap clipping,
+	- list clipping (up to 16 rectangles)
+	- chromakey
+	- source chromakey
+	- global alpha
+	- local alpha
+	- local inverse alpha
+
+Output overlays are not supported for multiplanar formats. In addition, the
+pixelformat of the capture format and that of the framebuffer must be the
+same for the overlay to work. Otherwise VIDIOC_OVERLAY will return an error.
+
+Output overlays only work if the driver has been configured to create a
+framebuffer by setting flag 0x10000 in the node_types module option. The
+created framebuffer has a size of 720x576 and supports ARGB 1:5:5:5 and
+RGB 5:6:5.
+
+In order to see the effects of the various clipping, chromakeying or alpha
+processing capabilities you need to turn on video looping and see the results
+on the capture side. The use of the clipping, chromakeying or alpha processing
+capabilities will slow down the video loop considerably as a lot of checks have
+to be done per pixel.
+
+
+CEC (Consumer Electronics Control)
+----------------------------------
+
+If there are HDMI inputs then a CEC adapter will be created that has
+the same number of input ports. This is the equivalent of e.g. a TV that
+has that number of inputs. Each HDMI output will also create a
+CEC adapter that is hooked up to the corresponding input port, or (if there
+are more outputs than inputs) is not hooked up at all. In other words,
+this is the equivalent of hooking up each output device to an input port of
+the TV. Any remaining output devices remain unconnected.
+
+The EDID that each output reads reports a unique CEC physical address that is
+based on the physical address of the EDID of the input. So if the EDID of the
+receiver has physical address A.B.0.0, then each output will see an EDID
+containing physical address A.B.C.0 where C is 1 to the number of inputs. If
+there are more outputs than inputs then the remaining outputs have a CEC adapter
+that is disabled and reports an invalid physical address.
+
+
+Some Future Improvements
+------------------------
+
+Just as a reminder and in no particular order:
+
+- Add a virtual alsa driver to test audio
+- Add virtual sub-devices
+- Some support for testing compressed video
+- Add support to loop raw VBI output to raw VBI input
+- Add support to loop teletext sliced VBI output to VBI input
+- Fix sequence/field numbering when looping of video with alternate fields
+- Add support for V4L2_CID_BG_COLOR for video outputs
+- Add ARGB888 overlay support: better testing of the alpha channel
+- Improve pixel aspect support in the tpg code by passing a real v4l2_fract
+- Use per-queue locks and/or per-device locks to improve throughput
+- The SDR radio should use the same 'frequencies' for stations as the normal
+  radio receiver, and give back noise if the frequency doesn't match up with
+  a station frequency
+- Make a thread for the RDS generation, that would help in particular for the
+  "Controls" RDS Rx I/O Mode as the read-only RDS controls could be updated
+  in real-time.
+- Changing the EDID doesn't wait 100 ms before setting the HPD signal.
diff --git a/Documentation/admin-guide/media/zoran-cardlist.rst b/Documentation/admin-guide/media/zoran-cardlist.rst
new file mode 100644
index 000000000..d7fc8bed6
--- /dev/null
+++ b/Documentation/admin-guide/media/zoran-cardlist.rst
@@ -0,0 +1,51 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Zoran cards list
+================
+
+.. tabularcolumns:: |p{1.4cm}|p{11.1cm}|p{4.2cm}|
+
+.. flat-table::
+   :header-rows: 1
+   :widths: 2 19 18
+   :stub-columns: 0
+
+   * - Card number
+     - Card name
+     - PCI subsystem IDs
+
+   * - 0
+     - DC10(old)
+     - <any>
+
+   * - 1
+     - DC10(new)
+     - <any>
+
+   * - 2
+     - DC10_PLUS
+     - 1031:7efe
+
+   * - 3
+     - DC30
+     - <any>
+
+   * - 4
+     - DC30_PLUS
+     - 1031:d801
+
+   * - 5
+     - LML33
+     - <any>
+
+   * - 6
+     - LML33R10
+     - 12f8:8a02
+
+   * - 7
+     - Buz
+     - 13ca:4231
+
+   * - 8
+     - 6-Eyes
+     - <any>
diff --git a/Documentation/admin-guide/mm/cma_debugfs.rst b/Documentation/admin-guide/mm/cma_debugfs.rst
new file mode 100644
index 000000000..4120e9cb0
--- /dev/null
+++ b/Documentation/admin-guide/mm/cma_debugfs.rst
@@ -0,0 +1,31 @@
+=====================
+CMA Debugfs Interface
+=====================
+
+The CMA debugfs interface is useful to retrieve basic information out of the
+different CMA areas and to test allocation/release in each of the areas.
+
+Each CMA area represents a directory under <debugfs>/cma/, represented by
+its CMA name like below:
+
+	<debugfs>/cma/<cma_name>
+
+The structure of the files created under that directory is as follows:
+
+ - [RO] base_pfn: The base PFN (Page Frame Number) of the CMA area.
+        This is the same as ranges/0/base_pfn.
+ - [RO] count: Amount of memory in the CMA area.
+ - [RO] order_per_bit: Order of pages represented by one bit.
+ - [RO] bitmap: The bitmap of allocated pages in the area.
+        This is the same as ranges/0/base_pfn.
+ - [RO] ranges/N/base_pfn: The base PFN of contiguous range N
+        in the CMA area.
+ - [RO] ranges/N/bitmap: The bit map of allocated pages in
+        range N in the CMA area.
+ - [WO] alloc: Allocate N pages from that CMA area. For example::
+
+	echo 5 > <debugfs>/cma/<cma_name>/alloc
+
+would try to allocate 5 pages from the 'cma_name' area.
+
+ - [WO] free: Free N pages from that CMA area, similar to the above.
diff --git a/Documentation/admin-guide/mm/concepts.rst b/Documentation/admin-guide/mm/concepts.rst
new file mode 100644
index 000000000..e796b0a7e
--- /dev/null
+++ b/Documentation/admin-guide/mm/concepts.rst
@@ -0,0 +1,220 @@
+=================
+Concepts overview
+=================
+
+The memory management in Linux is a complex system that evolved over the
+years and included more and more functionality to support a variety of
+systems from MMU-less microcontrollers to supercomputers. The memory
+management for systems without an MMU is called ``nommu`` and it
+definitely deserves a dedicated document, which hopefully will be
+eventually written. Yet, although some of the concepts are the same,
+here we assume that an MMU is available and a CPU can translate a virtual
+address to a physical address.
+
+.. contents:: :local:
+
+Virtual Memory Primer
+=====================
+
+The physical memory in a computer system is a limited resource and
+even for systems that support memory hotplug there is a hard limit on
+the amount of memory that can be installed. The physical memory is not
+necessarily contiguous; it might be accessible as a set of distinct
+address ranges. Besides, different CPU architectures, and even
+different implementations of the same architecture have different views
+of how these address ranges are defined.
+
+All this makes dealing directly with physical memory quite complex and
+to avoid this complexity a concept of virtual memory was developed.
+
+The virtual memory abstracts the details of physical memory from the
+application software, allows to keep only needed information in the
+physical memory (demand paging) and provides a mechanism for the
+protection and controlled sharing of data between processes.
+
+With virtual memory, each and every memory access uses a virtual
+address. When the CPU decodes an instruction that reads (or
+writes) from (or to) the system memory, it translates the `virtual`
+address encoded in that instruction to a `physical` address that the
+memory controller can understand.
+
+The physical system memory is divided into page frames, or pages. The
+size of each page is architecture specific. Some architectures allow
+selection of the page size from several supported values; this
+selection is performed at the kernel build time by setting an
+appropriate kernel configuration option.
+
+Each physical memory page can be mapped as one or more virtual
+pages. These mappings are described by page tables that allow
+translation from a virtual address used by programs to the physical
+memory address. The page tables are organized hierarchically.
+
+The tables at the lowest level of the hierarchy contain physical
+addresses of actual pages used by the software. The tables at higher
+levels contain physical addresses of the pages belonging to the lower
+levels. The pointer to the top level page table resides in a
+register. When the CPU performs the address translation, it uses this
+register to access the top level page table. The high bits of the
+virtual address are used to index an entry in the top level page
+table. That entry is then used to access the next level in the
+hierarchy with the next bits of the virtual address as the index to
+that level page table. The lowest bits in the virtual address define
+the offset inside the actual page.
+
+Huge Pages
+==========
+
+The address translation requires several memory accesses and memory
+accesses are slow relatively to CPU speed. To avoid spending precious
+processor cycles on the address translation, CPUs maintain a cache of
+such translations called Translation Lookaside Buffer (or
+TLB). Usually TLB is pretty scarce resource and applications with
+large memory working set will experience performance hit because of
+TLB misses.
+
+Many modern CPU architectures allow mapping of the memory pages
+directly by the higher levels in the page table. For instance, on x86,
+it is possible to map 2M and even 1G pages using entries in the second
+and the third level page tables. In Linux such pages are called
+`huge`. Usage of huge pages significantly reduces pressure on TLB,
+improves TLB hit-rate and thus improves overall system performance.
+
+There are two mechanisms in Linux that enable mapping of the physical
+memory with the huge pages. The first one is `HugeTLB filesystem`, or
+hugetlbfs. It is a pseudo filesystem that uses RAM as its backing
+store. For the files created in this filesystem the data resides in
+the memory and mapped using huge pages. The hugetlbfs is described at
+Documentation/admin-guide/mm/hugetlbpage.rst.
+
+Another, more recent, mechanism that enables use of the huge pages is
+called `Transparent HugePages`, or THP. Unlike the hugetlbfs that
+requires users and/or system administrators to configure what parts of
+the system memory should and can be mapped by the huge pages, THP
+manages such mappings transparently to the user and hence the
+name. See Documentation/admin-guide/mm/transhuge.rst for more details
+about THP.
+
+Zones
+=====
+
+Often hardware poses restrictions on how different physical memory
+ranges can be accessed. In some cases, devices cannot perform DMA to
+all the addressable memory. In other cases, the size of the physical
+memory exceeds the maximal addressable size of virtual memory and
+special actions are required to access portions of the memory. Linux
+groups memory pages into `zones` according to their possible
+usage. For example, ZONE_DMA will contain memory that can be used by
+devices for DMA, ZONE_HIGHMEM will contain memory that is not
+permanently mapped into kernel's address space and ZONE_NORMAL will
+contain normally addressed pages.
+
+The actual layout of the memory zones is hardware dependent as not all
+architectures define all zones, and requirements for DMA are different
+for different platforms.
+
+Nodes
+=====
+
+Many multi-processor machines are NUMA - Non-Uniform Memory Access -
+systems. In such systems the memory is arranged into banks that have
+different access latency depending on the "distance" from the
+processor. Each bank is referred to as a `node` and for each node Linux
+constructs an independent memory management subsystem. A node has its
+own set of zones, lists of free and used pages and various statistics
+counters. You can find more details about NUMA in
+Documentation/mm/numa.rst` and in
+Documentation/admin-guide/mm/numa_memory_policy.rst.
+
+Page cache
+==========
+
+The physical memory is volatile and the common case for getting data
+into the memory is to read it from files. Whenever a file is read, the
+data is put into the `page cache` to avoid expensive disk access on
+the subsequent reads. Similarly, when one writes to a file, the data
+is placed in the page cache and eventually gets into the backing
+storage device. The written pages are marked as `dirty` and when Linux
+decides to reuse them for other purposes, it makes sure to synchronize
+the file contents on the device with the updated data.
+
+Anonymous Memory
+================
+
+The `anonymous memory` or `anonymous mappings` represent memory that
+is not backed by a filesystem. Such mappings are implicitly created
+for program's stack and heap or by explicit calls to mmap(2) system
+call. Usually, the anonymous mappings only define virtual memory areas
+that the program is allowed to access. The read accesses will result
+in creation of a page table entry that references a special physical
+page filled with zeroes. When the program performs a write, a regular
+physical page will be allocated to hold the written data. The page
+will be marked dirty and if the kernel decides to repurpose it,
+the dirty page will be swapped out.
+
+Reclaim
+=======
+
+Throughout the system lifetime, a physical page can be used for storing
+different types of data. It can be kernel internal data structures,
+DMA'able buffers for device drivers use, data read from a filesystem,
+memory allocated by user space processes etc.
+
+Depending on the page usage it is treated differently by the Linux
+memory management. The pages that can be freed at any time, either
+because they cache the data available elsewhere, for instance, on a
+hard disk, or because they can be swapped out, again, to the hard
+disk, are called `reclaimable`. The most notable categories of the
+reclaimable pages are page cache and anonymous memory.
+
+In most cases, the pages holding internal kernel data and used as DMA
+buffers cannot be repurposed, and they remain pinned until freed by
+their user. Such pages are called `unreclaimable`. However, in certain
+circumstances, even pages occupied with kernel data structures can be
+reclaimed. For instance, in-memory caches of filesystem metadata can
+be re-read from the storage device and therefore it is possible to
+discard them from the main memory when system is under memory
+pressure.
+
+The process of freeing the reclaimable physical memory pages and
+repurposing them is called (surprise!) `reclaim`. Linux can reclaim
+pages either asynchronously or synchronously, depending on the state
+of the system. When the system is not loaded, most of the memory is free
+and allocation requests will be satisfied immediately from the free
+pages supply. As the load increases, the amount of the free pages goes
+down and when it reaches a certain threshold (low watermark), an
+allocation request will awaken the ``kswapd`` daemon. It will
+asynchronously scan memory pages and either just free them if the data
+they contain is available elsewhere, or evict to the backing storage
+device (remember those dirty pages?). As memory usage increases even
+more and reaches another threshold - min watermark - an allocation
+will trigger `direct reclaim`. In this case allocation is stalled
+until enough memory pages are reclaimed to satisfy the request.
+
+Compaction
+==========
+
+As the system runs, tasks allocate and free the memory and it becomes
+fragmented. Although with virtual memory it is possible to present
+scattered physical pages as virtually contiguous range, sometimes it is
+necessary to allocate large physically contiguous memory areas. Such
+need may arise, for instance, when a device driver requires a large
+buffer for DMA, or when THP allocates a huge page. Memory `compaction`
+addresses the fragmentation issue. This mechanism moves occupied pages
+from the lower part of a memory zone to free pages in the upper part
+of the zone. When a compaction scan is finished free pages are grouped
+together at the beginning of the zone and allocations of large
+physically contiguous areas become possible.
+
+Like reclaim, the compaction may happen asynchronously in the ``kcompactd``
+daemon or synchronously as a result of a memory allocation request.
+
+OOM killer
+==========
+
+It is possible that on a loaded machine memory will be exhausted and the
+kernel will be unable to reclaim enough memory to continue to operate. In
+order to save the rest of the system, it invokes the `OOM killer`.
+
+The `OOM killer` selects a task to sacrifice for the sake of the overall
+system health. The selected task is killed in a hope that after it exits
+enough memory will be freed to continue normal operation.
diff --git a/Documentation/admin-guide/mm/damon/index.rst b/Documentation/admin-guide/mm/damon/index.rst
new file mode 100644
index 000000000..3ce316448
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/index.rst
@@ -0,0 +1,17 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================================================================
+DAMON: Data Access MONitoring and Access-aware System Operations
+================================================================
+
+:doc:`DAMON </mm/damon/index>` is a Linux kernel subsystem for efficient data
+access monitoring and access-aware system operations.
+
+.. toctree::
+   :maxdepth: 2
+
+   start
+   usage
+   reclaim
+   lru_sort
+   stat
diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
new file mode 100644
index 000000000..b93ca9b08
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
@@ -0,0 +1,368 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+DAMON-based LRU-lists Sorting
+=============================
+
+DAMON-based LRU-lists Sorting (DAMON_LRU_SORT) is a static kernel module that
+aimed to be used for proactive and lightweight data access pattern based
+(de)prioritization of pages on their LRU-lists for making LRU-lists a more
+trusworthy data access pattern source.
+
+Where Proactive LRU-lists Sorting is Required?
+==============================================
+
+As page-granularity access checking overhead could be significant on huge
+systems, LRU lists are normally not proactively sorted but partially and
+reactively sorted for special events including specific user requests, system
+calls and memory pressure.  As a result, LRU lists are sometimes not so
+perfectly prepared to be used as a trustworthy access pattern source for some
+situations including reclamation target pages selection under sudden memory
+pressure.
+
+Because DAMON can identify access patterns of best-effort accuracy while
+inducing only user-specified range of overhead, proactively running
+DAMON_LRU_SORT could be helpful for making LRU lists more trustworthy access
+pattern source with low and controlled overhead.
+
+How It Works?
+=============
+
+DAMON_LRU_SORT finds hot pages (pages of memory regions that showing access
+rates that higher than a user-specified threshold) and cold pages (pages of
+memory regions that showing no access for a time that longer than a
+user-specified threshold) using DAMON, and prioritizes hot pages while
+deprioritizing cold pages on their LRU-lists.  To avoid it consuming too much
+CPU for the prioritizations, a CPU time usage limit can be configured.  Under
+the limit, it prioritizes and deprioritizes more hot and cold pages first,
+respectively.  System administrators can also configure under what situation
+this scheme should automatically activated and deactivated with three memory
+pressure watermarks.
+
+Its default parameters for hotness/coldness thresholds and CPU quota limit are
+conservatively chosen.  That is, the module under its default parameters could
+be widely used without harm for common situations while providing a level of
+benefits for systems having clear hot/cold access patterns under memory
+pressure while consuming only a limited small portion of CPU time.
+
+Interface: Module Parameters
+============================
+
+To use this feature, you should first ensure your system is running on a kernel
+that is built with ``CONFIG_DAMON_LRU_SORT=y``.
+
+To let sysadmins enable or disable it and tune for the given system,
+DAMON_LRU_SORT utilizes module parameters.  That is, you can put
+``damon_lru_sort.<parameter>=<value>`` on the kernel boot command line or write
+proper values to ``/sys/module/damon_lru_sort/parameters/<parameter>`` files.
+
+Below are the description of each parameter.
+
+enabled
+-------
+
+Enable or disable DAMON_LRU_SORT.
+
+You can enable DAMON_LRU_SORT by setting the value of this parameter as ``Y``.
+Setting it as ``N`` disables DAMON_LRU_SORT.  Note that DAMON_LRU_SORT could do
+no real monitoring and LRU-lists sorting due to the watermarks-based activation
+condition.  Refer to below descriptions for the watermarks parameter for this.
+
+commit_inputs
+-------------
+
+Make DAMON_LRU_SORT reads the input parameters again, except ``enabled``.
+
+Input parameters that updated while DAMON_LRU_SORT is running are not applied
+by default.  Once this parameter is set as ``Y``, DAMON_LRU_SORT reads values
+of parameters except ``enabled`` again.  Once the re-reading is done, this
+parameter is set as ``N``.  If invalid parameters are found while the
+re-reading, DAMON_LRU_SORT will be disabled.
+
+Once ``Y`` is written to this parameter, the user must not write to any
+parameters until reading ``commit_inputs`` again returns ``N``.  If users
+violate this rule, the kernel may exhibit undefined behavior.
+
+active_mem_bp
+-------------
+
+Desired active to [in]active memory ratio in bp (1/10,000).
+
+While keeping the caps that set by other quotas, DAMON_LRU_SORT automatically
+increases and decreases the effective level of the quota aiming the LRU
+[de]prioritizations of the hot and cold memory resulting in this active to
+[in]active memory ratio.  Value zero means disabling this auto-tuning feature.
+
+Disabled by default.
+
+autotune_monitoring_intervals
+-----------------------------
+
+If this parameter is set as ``Y``, DAMON_LRU_SORT automatically tunes DAMON's
+sampling and aggregation intervals.  The auto-tuning aims to capture meaningful
+amount of access events in each DAMON-snapshot, while keeping the sampling
+interval 5 milliseconds in minimum, and 10 seconds in maximum.  Setting this as
+``N`` disables the auto-tuning.
+
+Disabled by default.
+
+filter_young_pages
+------------------
+
+Filter [non-]young pages accordingly for LRU [de]prioritizations.
+
+If this is set, check page level access (youngness) once again before each
+LRU [de]prioritization operation.  LRU prioritization operation is skipped
+if the page has not accessed since the last check (not young).  LRU
+deprioritization operation is skipped if the page has accessed since the
+last check (young).  The feature is enabled or disabled if this parameter is
+set as ``Y`` or ``N``, respectively.
+
+Disabled by default.
+
+hot_thres_access_freq
+---------------------
+
+Access frequency threshold for hot memory regions identification in permil.
+
+If a memory region is accessed in frequency of this or higher, DAMON_LRU_SORT
+identifies the region as hot, and mark it as accessed on the LRU list, so that
+it could not be reclaimed under memory pressure.  50% by default.
+
+cold_min_age
+------------
+
+Time threshold for cold memory regions identification in microseconds.
+
+If a memory region is not accessed for this or longer time, DAMON_LRU_SORT
+identifies the region as cold, and mark it as unaccessed on the LRU list, so
+that it could be reclaimed first under memory pressure.  120 seconds by
+default.
+
+quota_ms
+--------
+
+Limit of time for trying the LRU lists sorting in milliseconds.
+
+DAMON_LRU_SORT tries to use only up to this time within a time window
+(quota_reset_interval_ms) for trying LRU lists sorting.  This can be used
+for limiting CPU consumption of DAMON_LRU_SORT.  If the value is zero, the
+limit is disabled.
+
+10 ms by default.
+
+quota_reset_interval_ms
+-----------------------
+
+The time quota charge reset interval in milliseconds.
+
+The charge reset interval for the quota of time (quota_ms).  That is,
+DAMON_LRU_SORT does not try LRU-lists sorting for more than quota_ms
+milliseconds or quota_sz bytes within quota_reset_interval_ms milliseconds.
+
+1 second by default.
+
+wmarks_interval
+---------------
+
+The watermarks check time interval in microseconds.
+
+Minimal time to wait before checking the watermarks, when DAMON_LRU_SORT is
+enabled but inactive due to its watermarks rule.  5 seconds by default.
+
+wmarks_high
+-----------
+
+Free memory rate (per thousand) for the high watermark.
+
+If free memory of the system in bytes per thousand bytes is higher than this,
+DAMON_LRU_SORT becomes inactive, so it does nothing but periodically checks the
+watermarks.  200 (20%) by default.
+
+wmarks_mid
+----------
+
+Free memory rate (per thousand) for the middle watermark.
+
+If free memory of the system in bytes per thousand bytes is between this and
+the low watermark, DAMON_LRU_SORT becomes active, so starts the monitoring and
+the LRU-lists sorting.  150 (15%) by default.
+
+wmarks_low
+----------
+
+Free memory rate (per thousand) for the low watermark.
+
+If free memory of the system in bytes per thousand bytes is lower than this,
+DAMON_LRU_SORT becomes inactive, so it does nothing but periodically checks the
+watermarks.  50 (5%) by default.
+
+sample_interval
+---------------
+
+Sampling interval for the monitoring in microseconds.
+
+The sampling interval of DAMON for the cold memory monitoring.  Please refer to
+the DAMON documentation (:doc:`usage`) for more detail.  5ms by default.
+
+aggr_interval
+-------------
+
+Aggregation interval for the monitoring in microseconds.
+
+The aggregation interval of DAMON for the cold memory monitoring.  Please
+refer to the DAMON documentation (:doc:`usage`) for more detail.  100ms by
+default.
+
+min_nr_regions
+--------------
+
+Minimum number of monitoring regions.
+
+The minimal number of monitoring regions of DAMON for the cold memory
+monitoring.  This can be used to set lower-bound of the monitoring quality.
+But, setting this too high could result in increased monitoring overhead.
+Please refer to the DAMON documentation (:doc:`usage`) for more detail.  10 by
+default.
+
+Note that this must be 3 or higher. Please refer to the :ref:`Monitoring
+<damon_design_monitoring>` section of the design document for the rationale
+behind this lower bound.
+
+max_nr_regions
+--------------
+
+Maximum number of monitoring regions.
+
+The maximum number of monitoring regions of DAMON for the cold memory
+monitoring.  This can be used to set upper-bound of the monitoring overhead.
+However, setting this too low could result in bad monitoring quality.  Please
+refer to the DAMON documentation (:doc:`usage`) for more detail.  1000 by
+defaults.
+
+monitor_region_start
+--------------------
+
+Start of target memory region in physical address.
+
+The start physical address of memory region that DAMON_LRU_SORT will do work
+against.  By default, the system's entire physical memory is used as the
+region.
+
+monitor_region_end
+------------------
+
+End of target memory region in physical address.
+
+The end physical address of memory region that DAMON_LRU_SORT will do work
+against.  By default, the system's entire physical memory is used as the
+region.
+
+addr_unit
+---------
+
+A scale factor for memory addresses and bytes.
+
+This parameter is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM.
+
+``monitor_region_start`` and ``monitor_region_end`` should be provided in this
+unit.  For example, let's suppose ``addr_unit``, ``monitor_region_start`` and
+``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively.
+Then DAMON_LRU_SORT will work for 10 KiB length of physical address range that
+starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes).
+
+Stat parameters having ``bytes_`` prefix are also in this unit.  For example,
+let's suppose values of ``addr_unit``, ``bytes_lru_sort_tried_hot_regions`` and
+``bytes_lru_sorted_hot_regions`` are ``1024``, ``42``, and ``32``,
+respectively.  Then it means DAMON_LRU_SORT tried to LRU-sort 42 KiB of hot
+memory and successfully LRU-sorted 32 KiB of the memory in total.
+
+If unsure, use only the default value (``1``) and forget about this.
+
+kdamond_pid
+-----------
+
+PID of the DAMON thread.
+
+If DAMON_LRU_SORT is enabled, this becomes the PID of the worker thread.  Else,
+-1.
+
+nr_lru_sort_tried_hot_regions
+-----------------------------
+
+Number of hot memory regions that tried to be LRU-sorted.
+
+bytes_lru_sort_tried_hot_regions
+--------------------------------
+
+Total bytes of hot memory regions that tried to be LRU-sorted.
+
+nr_lru_sorted_hot_regions
+-------------------------
+
+Number of hot memory regions that successfully be LRU-sorted.
+
+bytes_lru_sorted_hot_regions
+----------------------------
+
+Total bytes of hot memory regions that successfully be LRU-sorted.
+
+nr_hot_quota_exceeds
+--------------------
+
+Number of times that the time quota limit for hot regions have exceeded.
+
+nr_lru_sort_tried_cold_regions
+------------------------------
+
+Number of cold memory regions that tried to be LRU-sorted.
+
+bytes_lru_sort_tried_cold_regions
+---------------------------------
+
+Total bytes of cold memory regions that tried to be LRU-sorted.
+
+nr_lru_sorted_cold_regions
+--------------------------
+
+Number of cold memory regions that successfully be LRU-sorted.
+
+bytes_lru_sorted_cold_regions
+-----------------------------
+
+Total bytes of cold memory regions that successfully be LRU-sorted.
+
+nr_cold_quota_exceeds
+---------------------
+
+Number of times that the time quota limit for cold regions have exceeded.
+
+Example
+=======
+
+Below runtime example commands make DAMON_LRU_SORT to find memory regions
+having >=50% access frequency and LRU-prioritize while LRU-deprioritizing
+memory regions that not accessed for 120 seconds.  The prioritization and
+deprioritization is limited to be done using only up to 1% CPU time to avoid
+DAMON_LRU_SORT consuming too much CPU time for the (de)prioritization.  It also
+asks DAMON_LRU_SORT to do nothing if the system's free memory rate is more than
+50%, but start the real works if it becomes lower than 40%.  If DAMON_RECLAIM
+doesn't make progress and therefore the free memory rate becomes lower than
+20%, it asks DAMON_LRU_SORT to do nothing again, so that we can fall back to
+the LRU-list based page granularity reclamation. ::
+
+    # cd /sys/module/damon_lru_sort/parameters
+    # echo 500 > hot_thres_access_freq
+    # echo 120000000 > cold_min_age
+    # echo 10 > quota_ms
+    # echo 1000 > quota_reset_interval_ms
+    # echo 500 > wmarks_high
+    # echo 400 > wmarks_mid
+    # echo 200 > wmarks_low
+    # echo Y > enabled
+
+Note that this module (damon_lru_sort) cannot run simultaneously with other
+DAMON-based special-purpose modules.  Refer to :ref:`DAMON design special
+purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>`
+for more details.
diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
new file mode 100644
index 000000000..ec7e3e32b
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -0,0 +1,349 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================
+DAMON-based Reclamation
+=======================
+
+DAMON-based Reclamation (DAMON_RECLAIM) is a static kernel module that aimed to
+be used for proactive and lightweight reclamation under light memory pressure.
+It doesn't aim to replace the LRU-list based page_granularity reclamation, but
+to be selectively used for different level of memory pressure and requirements.
+
+Where Proactive Reclamation is Required?
+========================================
+
+On general memory over-committed systems, proactively reclaiming cold pages
+helps saving memory and reducing latency spikes that incurred by the direct
+reclaim of the process or CPU consumption of kswapd, while incurring only
+minimal performance degradation [1]_ [2]_ .
+
+Free Pages Reporting [3]_ based memory over-commit virtualization systems are
+good example of the cases.  In such systems, the guest VMs reports their free
+memory to host, and the host reallocates the reported memory to other guests.
+As a result, the memory of the systems are fully utilized.  However, the
+guests could be not so memory-frugal, mainly because some kernel subsystems and
+user-space applications are designed to use as much memory as available.  Then,
+guests could report only small amount of memory as free to host, results in
+memory utilization drop of the systems.  Running the proactive reclamation in
+guests could mitigate this problem.
+
+How It Works?
+=============
+
+DAMON_RECLAIM finds memory regions that didn't accessed for specific time
+duration and page out.  To avoid it consuming too much CPU for the paging out
+operation, a speed limit can be configured.  Under the speed limit, it pages
+out memory regions that didn't accessed longer time first.  System
+administrators can also configure under what situation this scheme should
+automatically activated and deactivated with three memory pressure watermarks.
+
+Interface: Module Parameters
+============================
+
+To use this feature, you should first ensure your system is running on a kernel
+that is built with ``CONFIG_DAMON_RECLAIM=y``.
+
+To let sysadmins enable or disable it and tune for the given system,
+DAMON_RECLAIM utilizes module parameters.  That is, you can put
+``damon_reclaim.<parameter>=<value>`` on the kernel boot command line or write
+proper values to ``/sys/module/damon_reclaim/parameters/<parameter>`` files.
+
+Below are the description of each parameter.
+
+enabled
+-------
+
+Enable or disable DAMON_RECLAIM.
+
+You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``.
+Setting it as ``N`` disables DAMON_RECLAIM.  Note that DAMON_RECLAIM could do
+no real monitoring and reclamation due to the watermarks-based activation
+condition.  Refer to below descriptions for the watermarks parameter for this.
+
+commit_inputs
+-------------
+
+Make DAMON_RECLAIM reads the input parameters again, except ``enabled``.
+
+Input parameters that updated while DAMON_RECLAIM is running are not applied
+by default.  Once this parameter is set as ``Y``, DAMON_RECLAIM reads values
+of parameters except ``enabled`` again.  Once the re-reading is done, this
+parameter is set as ``N``.  If invalid parameters are found while the
+re-reading, DAMON_RECLAIM will be disabled.
+
+Once ``Y`` is written to this parameter, the user must not write to any
+parameters until reading ``commit_inputs`` again returns ``N``.  If users
+violate this rule, the kernel may exhibit undefined behavior.
+
+min_age
+-------
+
+Time threshold for cold memory regions identification in microseconds.
+
+If a memory region is not accessed for this or longer time, DAMON_RECLAIM
+identifies the region as cold, and reclaims it.
+
+120 seconds by default.
+
+autotune_monitoring_intervals
+-----------------------------
+
+If this parameter is set as ``Y``, DAMON_RECLAIM automatically tunes DAMON's
+sampling and aggregation intervals.  The auto-tuning aims to capture meaningful
+amount of access events in each DAMON-snapshot, while keeping the sampling
+interval 5 milliseconds in minimum, and 10 seconds in maximum.  Setting this as
+``N`` disables the auto-tuning.
+
+Disabled by default.
+
+quota_ms
+--------
+
+Limit of time for the reclamation in milliseconds.
+
+DAMON_RECLAIM tries to use only up to this time within a time window
+(quota_reset_interval_ms) for trying reclamation of cold pages.  This can be
+used for limiting CPU consumption of DAMON_RECLAIM.  If the value is zero, the
+limit is disabled.
+
+10 ms by default.
+
+quota_sz
+--------
+
+Limit of size of memory for the reclamation in bytes.
+
+DAMON_RECLAIM charges amount of memory which it tried to reclaim within a time
+window (quota_reset_interval_ms) and makes no more than this limit is tried.
+This can be used for limiting consumption of CPU and IO.  If this value is
+zero, the limit is disabled.
+
+128 MiB by default.
+
+quota_reset_interval_ms
+-----------------------
+
+The time/size quota charge reset interval in milliseconds.
+
+The charget reset interval for the quota of time (quota_ms) and size
+(quota_sz).  That is, DAMON_RECLAIM does not try reclamation for more than
+quota_ms milliseconds or quota_sz bytes within quota_reset_interval_ms
+milliseconds.
+
+1 second by default.
+
+quota_mem_pressure_us
+---------------------
+
+Desired level of memory pressure-stall time in microseconds.
+
+While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
+increases and decreases the effective level of the quota aiming this level of
+memory pressure is incurred.  System-wide ``some`` memory PSI in microseconds
+per quota reset interval (``quota_reset_interval_ms``) is collected and
+compared to this value to see if the aim is satisfied.  Value zero means
+disabling this auto-tuning feature.
+
+Disabled by default.
+
+quota_autotune_feedback
+-----------------------
+
+User-specifiable feedback for auto-tuning of the effective quota.
+
+While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
+increases and decreases the effective level of the quota aiming receiving this
+feedback of value ``10,000`` from the user.  DAMON_RECLAIM assumes the feedback
+value and the quota are positively proportional.  Value zero means disabling
+this auto-tuning feature.
+
+Disabled by default.
+
+wmarks_interval
+---------------
+
+Minimal time to wait before checking the watermarks, when DAMON_RECLAIM is
+enabled but inactive due to its watermarks rule.
+
+wmarks_high
+-----------
+
+Free memory rate (per thousand) for the high watermark.
+
+If free memory of the system in bytes per thousand bytes is higher than this,
+DAMON_RECLAIM becomes inactive, so it does nothing but only periodically checks
+the watermarks.
+
+wmarks_mid
+----------
+
+Free memory rate (per thousand) for the middle watermark.
+
+If free memory of the system in bytes per thousand bytes is between this and
+the low watermark, DAMON_RECLAIM becomes active, so starts the monitoring and
+the reclaiming.
+
+wmarks_low
+----------
+
+Free memory rate (per thousand) for the low watermark.
+
+If free memory of the system in bytes per thousand bytes is lower than this,
+DAMON_RECLAIM becomes inactive, so it does nothing but periodically checks the
+watermarks.  In the case, the system falls back to the LRU-list based page
+granularity reclamation logic.
+
+sample_interval
+---------------
+
+Sampling interval for the monitoring in microseconds.
+
+The sampling interval of DAMON for the cold memory monitoring.  Please refer to
+the DAMON documentation (:doc:`usage`) for more detail.
+
+aggr_interval
+-------------
+
+Aggregation interval for the monitoring in microseconds.
+
+The aggregation interval of DAMON for the cold memory monitoring.  Please
+refer to the DAMON documentation (:doc:`usage`) for more detail.
+
+min_nr_regions
+--------------
+
+Minimum number of monitoring regions.
+
+The minimal number of monitoring regions of DAMON for the cold memory
+monitoring.  This can be used to set lower-bound of the monitoring quality.
+But, setting this too high could result in increased monitoring overhead.
+Please refer to the DAMON documentation (:doc:`usage`) for more detail.
+
+Note that this must be 3 or higher. Please refer to the :ref:`Monitoring
+<damon_design_monitoring>` section of the design document for the rationale
+behind this lower bound.
+
+max_nr_regions
+--------------
+
+Maximum number of monitoring regions.
+
+The maximum number of monitoring regions of DAMON for the cold memory
+monitoring.  This can be used to set upper-bound of the monitoring overhead.
+However, setting this too low could result in bad monitoring quality.  Please
+refer to the DAMON documentation (:doc:`usage`) for more detail.
+
+monitor_region_start
+--------------------
+
+Start of target memory region in physical address.
+
+The start physical address of memory region that DAMON_RECLAIM will do work
+against.  That is, DAMON_RECLAIM will find cold memory regions in this region
+and reclaims.  By default, the system's entire physical memory is used as the
+region.
+
+monitor_region_end
+------------------
+
+End of target memory region in physical address.
+
+The end physical address of memory region that DAMON_RECLAIM will do work
+against.  That is, DAMON_RECLAIM will find cold memory regions in this region
+and reclaims.  By default, the system's entire physical memory is used as the
+region.
+
+addr_unit
+---------
+
+A scale factor for memory addresses and bytes.
+
+This parameter is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM.
+
+``monitor_region_start`` and ``monitor_region_end`` should be provided in this
+unit.  For example, let's suppose ``addr_unit``, ``monitor_region_start`` and
+``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively.
+Then DAMON_RECLAIM will work for 10 KiB length of physical address range that
+starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes).
+
+``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are also in
+this unit.  For example, let's suppose values of ``addr_unit``,
+``bytes_reclaim_tried_regions`` and ``bytes_reclaimed_regions`` are ``1024``,
+``42``, and ``32``, respectively.  Then it means DAMON_RECLAIM tried to reclaim
+42 KiB memory and successfully reclaimed 32 KiB memory in total.
+
+If unsure, use only the default value (``1``) and forget about this.
+
+skip_anon
+---------
+
+Skip anonymous pages reclamation.
+
+If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
+pages.  By default, ``N``.
+
+
+kdamond_pid
+-----------
+
+PID of the DAMON thread.
+
+If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread.  Else,
+-1.
+
+nr_reclaim_tried_regions
+------------------------
+
+Number of memory regions that tried to be reclaimed by DAMON_RECLAIM.
+
+bytes_reclaim_tried_regions
+---------------------------
+
+Total bytes of memory regions that tried to be reclaimed by DAMON_RECLAIM.
+
+nr_reclaimed_regions
+--------------------
+
+Number of memory regions that successfully be reclaimed by DAMON_RECLAIM.
+
+bytes_reclaimed_regions
+-----------------------
+
+Total bytes of memory regions that successfully be reclaimed by DAMON_RECLAIM.
+
+nr_quota_exceeds
+----------------
+
+Number of times that the time/space quota limits have exceeded.
+
+Example
+=======
+
+Below runtime example commands make DAMON_RECLAIM to find memory regions that
+not accessed for 30 seconds or more and pages out.  The reclamation is limited
+to be done only up to 1 GiB per second to avoid DAMON_RECLAIM consuming too
+much CPU time for the paging out operation.  It also asks DAMON_RECLAIM to do
+nothing if the system's free memory rate is more than 50%, but start the real
+works if it becomes lower than 40%.  If DAMON_RECLAIM doesn't make progress and
+therefore the free memory rate becomes lower than 20%, it asks DAMON_RECLAIM to
+do nothing again, so that we can fall back to the LRU-list based page
+granularity reclamation. ::
+
+    # cd /sys/module/damon_reclaim/parameters
+    # echo 30000000 > min_age
+    # echo $((1 * 1024 * 1024 * 1024)) > quota_sz
+    # echo 1000 > quota_reset_interval_ms
+    # echo 500 > wmarks_high
+    # echo 400 > wmarks_mid
+    # echo 200 > wmarks_low
+    # echo Y > enabled
+
+Note that this module (damon_reclaim) cannot run simultaneously with other
+DAMON-based special-purpose modules.  Refer to :ref:`DAMON design special
+purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>`
+for more details.
+
+.. [1] https://research.google/pubs/pub48551/
+.. [2] https://lwn.net/Articles/787611/
+.. [3] https://www.kernel.org/doc/html/latest/mm/free_page_reporting.html
diff --git a/Documentation/admin-guide/mm/damon/start.rst b/Documentation/admin-guide/mm/damon/start.rst
new file mode 100644
index 000000000..ec8c34b2d
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/start.rst
@@ -0,0 +1,178 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Getting Started
+===============
+
+This document briefly describes how you can use DAMON by demonstrating its
+default user space tool.  Please note that this document describes only a part
+of its features for brevity.  Please refer to the usage `doc
+<https://github.com/damonitor/damo/blob/next/USAGE.md>`_ of the tool for more
+details.
+
+
+Prerequisites
+=============
+
+Kernel
+------
+
+You should first ensure your system is running on a kernel built with
+``CONFIG_DAMON_*=y``.
+
+
+User Space Tool
+---------------
+
+For the demonstration, we will use the default user space tool for DAMON,
+called DAMON Operator (DAMO).  It is available at
+https://github.com/damonitor/damo.  The examples below assume that ``damo`` is on
+your ``$PATH``.  It's not mandatory, though.
+
+Because DAMO is using the sysfs interface (refer to :doc:`usage` for the
+detail) of DAMON, you should ensure :doc:`sysfs </filesystems/sysfs>` is
+mounted.
+
+
+Snapshot Data Access Patterns
+=============================
+
+The commands below show the memory access pattern of a program at the moment of
+the execution. ::
+
+    $ git clone https://github.com/sjp38/masim; cd masim; make
+    $ sudo damo start "./masim ./configs/stairs.cfg --quiet"
+    $ sudo damo report access
+    heatmap: 641111111000000000000000000000000000000000000000000000[...]33333333333333335557984444[...]7
+    # min/max temperatures: -1,840,000,000, 370,010,000, column size: 3.925 MiB
+    0   addr 86.182 TiB   size 8.000 KiB   access 0 %   age 14.900 s
+    1   addr 86.182 TiB   size 8.000 KiB   access 60 %  age 0 ns
+    2   addr 86.182 TiB   size 3.422 MiB   access 0 %   age 4.100 s
+    3   addr 86.182 TiB   size 2.004 MiB   access 95 %  age 2.200 s
+    4   addr 86.182 TiB   size 29.688 MiB  access 0 %   age 14.100 s
+    5   addr 86.182 TiB   size 29.516 MiB  access 0 %   age 16.700 s
+    6   addr 86.182 TiB   size 29.633 MiB  access 0 %   age 17.900 s
+    7   addr 86.182 TiB   size 117.652 MiB access 0 %   age 18.400 s
+    8   addr 126.990 TiB  size 62.332 MiB  access 0 %   age 9.500 s
+    9   addr 126.990 TiB  size 13.980 MiB  access 0 %   age 5.200 s
+    10  addr 126.990 TiB  size 9.539 MiB   access 100 % age 3.700 s
+    11  addr 126.990 TiB  size 16.098 MiB  access 0 %   age 6.400 s
+    12  addr 127.987 TiB  size 132.000 KiB access 0 %   age 2.900 s
+    total size: 314.008 MiB
+    $ sudo damo stop
+
+The first command of the above example downloads and builds an artificial
+memory access generator program called ``masim``.  The second command asks DAMO
+to start the program via the given command and make DAMON monitors the newly
+started process.  The third command retrieves the current snapshot of the
+monitored access pattern of the process from DAMON and shows the pattern in a
+human readable format.
+
+The first line of the output shows the relative access temperature (hotness) of
+the regions in a single row hetmap format.  Each column on the heatmap
+represents regions of same size on the monitored virtual address space.  The
+position of the colun on the row and the number on the column represents the
+relative location and access temperature of the region.  ``[...]`` means
+unmapped huge regions on the virtual address spaces.  The second line shows
+additional information for better understanding the heatmap.
+
+Each line of the output from the third line shows which virtual address range
+(``addr XX size XX``) of the process is how frequently (``access XX %``)
+accessed for how long time (``age XX``).  For example, the evelenth region of
+~9.5 MiB size is being most frequently accessed for last 3.7 seconds.  Finally,
+the fourth command stops DAMON.
+
+Note that DAMON can monitor not only virtual address spaces but multiple types
+of address spaces including the physical address space.
+
+
+Recording Data Access Patterns
+==============================
+
+The commands below record the memory access patterns of a program and save the
+monitoring results to a file. ::
+
+    $ ./masim ./configs/zigzag.cfg &
+    $ sudo damo record -o damon.data $(pidof masim)
+
+The line of the commands run the artificial memory access
+generator program again.  The generator will repeatedly
+access two 100 MiB sized memory regions one by one.  You can substitute this
+with your real workload.  The last line asks ``damo`` to record the access
+pattern in the ``damon.data`` file.
+
+
+Visualizing Recorded Patterns
+=============================
+
+You can visualize the pattern in a heatmap, showing which memory region
+(x-axis) got accessed when (y-axis) and how frequently (number).::
+
+    $ sudo damo report heatmap
+    22222222222222222222222222222222222222211111111111111111111111111111111111111100
+    44444444444444444444444444444444444444434444444444444444444444444444444444443200
+    44444444444444444444444444444444444444433444444444444444444444444444444444444200
+    33333333333333333333333333333333333333344555555555555555555555555555555555555200
+    33333333333333333333333333333333333344444444444444444444444444444444444444444200
+    22222222222222222222222222222222222223355555555555555555555555555555555555555200
+    00000000000000000000000000000000000000288888888888888888888888888888888888888400
+    00000000000000000000000000000000000000288888888888888888888888888888888888888400
+    33333333333333333333333333333333333333355555555555555555555555555555555555555200
+    88888888888888888888888888888888888888600000000000000000000000000000000000000000
+    88888888888888888888888888888888888888600000000000000000000000000000000000000000
+    33333333333333333333333333333333333333444444444444444444444444444444444444443200
+    00000000000000000000000000000000000000288888888888888888888888888888888888888400
+    [...]
+    # access_frequency:  0  1  2  3  4  5  6  7  8  9
+    # x-axis: space (139728247021568-139728453431248: 196.848 MiB)
+    # y-axis: time (15256597248362-15326899978162: 1 m 10.303 s)
+    # resolution: 80x40 (2.461 MiB and 1.758 s for each character)
+
+You can also visualize the distribution of the working set size, sorted by the
+size.::
+
+    $ sudo damo report wss --range 0 101 10
+    # <percentile> <wss>
+    # target_id     18446632103789443072
+    # avr:  107.708 MiB
+      0             0 B |                                                           |
+     10      95.328 MiB |****************************                               |
+     20      95.332 MiB |****************************                               |
+     30      95.340 MiB |****************************                               |
+     40      95.387 MiB |****************************                               |
+     50      95.387 MiB |****************************                               |
+     60      95.398 MiB |****************************                               |
+     70      95.398 MiB |****************************                               |
+     80      95.504 MiB |****************************                               |
+     90     190.703 MiB |*********************************************************  |
+    100     196.875 MiB |***********************************************************|
+
+Using ``--sortby`` option with the above command, you can show how the working
+set size has chronologically changed.::
+
+    $ sudo damo report wss --range 0 101 10 --sortby time
+    # <percentile> <wss>
+    # target_id     18446632103789443072
+    # avr:  107.708 MiB
+      0       3.051 MiB |                                                           |
+     10     190.703 MiB |***********************************************************|
+     20      95.336 MiB |*****************************                              |
+     30      95.328 MiB |*****************************                              |
+     40      95.387 MiB |*****************************                              |
+     50      95.332 MiB |*****************************                              |
+     60      95.320 MiB |*****************************                              |
+     70      95.398 MiB |*****************************                              |
+     80      95.398 MiB |*****************************                              |
+     90      95.340 MiB |*****************************                              |
+    100      95.398 MiB |*****************************                              |
+
+
+Data Access Pattern Aware Memory Management
+===========================================
+
+Below command makes every memory region of size >=4K that has not accessed for
+>=60 seconds in your workload to be swapped out. ::
+
+    $ sudo damo start --damos_access_rate 0 0 --damos_sz_region 4K max \
+                      --damos_age 60s max --damos_action pageout \
+                      --target_pid <pid of your workload>
diff --git a/Documentation/admin-guide/mm/damon/stat.rst b/Documentation/admin-guide/mm/damon/stat.rst
new file mode 100644
index 000000000..46c5dd96a
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/stat.rst
@@ -0,0 +1,98 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================================
+Data Access Monitoring Results Stat
+===================================
+
+Data Access Monitoring Results Stat (DAMON_STAT) is a static kernel module that
+is aimed to be used for simple access pattern monitoring.  It monitors accesses
+on the system's entire physical memory using DAMON, and provides simplified
+access monitoring results statistics, namely idle time percentiles and
+estimated memory bandwidth.
+
+.. _damon_stat_monitoring_accuracy_overhead:
+
+Monitoring Accuracy and Overhead
+================================
+
+DAMON_STAT uses monitoring intervals :ref:`auto-tuning
+<damon_design_monitoring_intervals_autotuning>` to make its accuracy high and
+overhead minimum.  It auto-tunes the intervals aiming 4 % of observable access
+events to be captured in each snapshot, while limiting the resulting sampling
+interval to be 5 milliseconds in minimum and 10 seconds in maximum.  On a few
+production server systems, it resulted in consuming only 0.x % single CPU time,
+while capturing reasonable quality of access patterns.  The tuning-resulting
+intervals can be retrieved via ``aggr_interval_us`` :ref:`parameter
+<damon_stat_aggr_interval_us>`.
+
+Interface: Module Parameters
+============================
+
+To use this feature, you should first ensure your system is running on a kernel
+that is built with ``CONFIG_DAMON_STAT=y``.  The feature can be enabled by
+default at build time, by setting ``CONFIG_DAMON_STAT_ENABLED_DEFAULT`` true.
+
+To let sysadmins enable or disable it at boot and/or runtime, and read the
+monitoring results, DAMON_STAT provides module parameters.  Following
+sections are descriptions of the parameters.
+
+enabled
+-------
+
+Enable or disable DAMON_STAT.
+
+You can enable DAMON_STAT by setting the value of this parameter as ``Y``.
+Setting it as ``N`` disables DAMON_STAT.  The default value is set by
+``CONFIG_DAMON_STAT_ENABLED_DEFAULT`` build config option.
+
+Note that this module (damon_stat) cannot run simultaneously with other
+DAMON-based special-purpose modules.  Refer to :ref:`DAMON design special
+purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>`
+for more details.
+
+.. _damon_stat_aggr_interval_us:
+
+aggr_interval_us
+----------------
+
+Auto-tuned aggregation time interval in microseconds.
+
+Users can read the aggregation interval of DAMON that is being used by the
+DAMON instance for DAMON_STAT.  It is :ref:`auto-tuned
+<damon_stat_monitoring_accuracy_overhead>` and therefore the value is
+dynamically changed.
+
+estimated_memory_bandwidth
+--------------------------
+
+Estimated memory bandwidth consumption (bytes per second) of the system.
+
+DAMON_STAT reads observed access events on the current DAMON results snapshot
+and converts it to memory bandwidth consumption estimation in bytes per second.
+The resulting metric is exposed to user via this read-only parameter.  Because
+DAMON uses sampling, this is only an estimation of the access intensity rather
+than accurate memory bandwidth.
+
+memory_idle_ms_percentiles
+--------------------------
+
+Per-byte idle time (milliseconds) percentiles of the system.
+
+DAMON_STAT calculates how long each byte of the memory was not accessed until
+now (idle time), based on the current DAMON results snapshot.  For regions
+having access frequency (nr_accesses) larger than zero, how long the current
+access frequency level was kept multiplied by ``-1`` becomes the idlee time of
+every byte of the region.  If a region has zero access frequency (nr_accesses),
+how long the region was keeping the zero access frequency (age) becomes the
+idle time of every byte of the region.  Then, DAMON_STAT exposes the
+percentiles of the idle time values via this read-only parameter.  Reading the
+parameter returns 101 idle time values in milliseconds, separated by comma.
+Each value represents 0-th, 1st, 2nd, 3rd, ..., 99th and 100th percentile idle
+times.
+
+kdamond_pid
+-----------
+
+PID of the DAMON thread.
+
+If DAMON_STAT is enabled, this becomes the PID of the worker thread.  Else, -1.
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
new file mode 100644
index 000000000..da5f9afd0
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -0,0 +1,762 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Detailed Usages
+===============
+
+DAMON provides below interfaces for different users.
+
+- *Special-purpose DAMON modules.*
+  :ref:`This <damon_modules_special_purpose>` is for people who are building,
+  distributing, and/or administrating the kernel with special-purpose DAMON
+  usages.  Using this, users can use DAMON's major features for the given
+  purposes in build, boot, or runtime in simple ways.
+- *DAMON user space tool.*
+  `This <https://github.com/damonitor/damo>`_ is for privileged people such as
+  system administrators who want a just-working human-friendly interface.
+  Using this, users can use the DAMON’s major features in a human-friendly way.
+  It may not be highly tuned for special cases, though.  For more detail,
+  please refer to its `usage document
+  <https://github.com/damonitor/damo/blob/next/USAGE.md>`_.
+- *sysfs interface.*
+  :ref:`This <sysfs_interface>` is for privileged user space programmers who
+  want more optimized use of DAMON.  Using this, users can use DAMON’s major
+  features by reading from and writing to special sysfs files.  Therefore,
+  you can write and use your personalized DAMON sysfs wrapper programs that
+  reads/writes the sysfs files instead of you.  The `DAMON user space tool
+  <https://github.com/damonitor/damo>`_ is one example of such programs.
+- *Kernel Space Programming Interface.*
+  :doc:`This </mm/damon/api>` is for kernel space programmers.  Using this,
+  users can utilize every feature of DAMON most flexibly and efficiently by
+  writing kernel space DAMON application programs for you.  You can even extend
+  DAMON for various address spaces.  For detail, please refer to the interface
+  :doc:`document </mm/damon/api>`.
+
+.. _sysfs_interface:
+
+sysfs Interface
+===============
+
+DAMON sysfs interface is built when ``CONFIG_DAMON_SYSFS`` is defined.  It
+creates multiple directories and files under its sysfs directory,
+``<sysfs>/kernel/mm/damon/``.  You can control DAMON by writing to and reading
+from the files under the directory.
+
+For a short example, users can monitor the virtual address space of a given
+workload as below. ::
+
+    # cd /sys/kernel/mm/damon/admin/
+    # echo 1 > kdamonds/nr_kdamonds && echo 1 > kdamonds/0/contexts/nr_contexts
+    # echo vaddr > kdamonds/0/contexts/0/operations
+    # echo 1 > kdamonds/0/contexts/0/targets/nr_targets
+    # echo $(pidof <workload>) > kdamonds/0/contexts/0/targets/0/pid_target
+    # echo on > kdamonds/0/state
+
+Files Hierarchy
+---------------
+
+The files hierarchy of DAMON sysfs interface is shown below.  In the below
+figure, parents-children relations are represented with indentations, each
+directory is having ``/`` suffix, and files in each directory are separated by
+comma (",").
+
+.. parsed-literal::
+
+    :ref:`/sys/kernel/mm/damon <sysfs_root>`/admin
+    │ :ref:`kdamonds <sysfs_kdamonds>`/nr_kdamonds
+    │ │ :ref:`0 <sysfs_kdamond>`/state,pid,refresh_ms
+    │ │ │ :ref:`contexts <sysfs_contexts>`/nr_contexts
+    │ │ │ │ :ref:`0 <sysfs_context>`/avail_operations,operations,addr_unit,
+    │ │ │ │   pause
+    │ │ │ │ │ :ref:`monitoring_attrs <sysfs_monitoring_attrs>`/
+    │ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
+    │ │ │ │ │ │ │ intervals_goal/access_bp,aggrs,min_sample_us,max_sample_us
+    │ │ │ │ │ │ nr_regions/min,max
+    │ │ │ │ │ │ :ref:`probes <damon_usage_sysfs_probes>`/nr_probes
+    │ │ │ │ │ │ │ 0/weight
+    │ │ │ │ │ │ │ │ filters/nr_filters
+    │ │ │ │ │ │ │ │ │ 0/type,matching,allow,path
+    │ │ │ │ │ │ │ │ │ ...
+    │ │ │ │ │ │ │ ...
+    │ │ │ │ │ :ref:`targets <sysfs_targets>`/nr_targets
+    │ │ │ │ │ │ :ref:`0 <sysfs_target>`/pid_target,obsolete_target
+    │ │ │ │ │ │ │ :ref:`regions <sysfs_regions>`/nr_regions
+    │ │ │ │ │ │ │ │ :ref:`0 <sysfs_region>`/start,end
+    │ │ │ │ │ │ │ │ ...
+    │ │ │ │ │ │ ...
+    │ │ │ │ │ :ref:`schemes <sysfs_schemes>`/nr_schemes
+    │ │ │ │ │ │ :ref:`0 <sysfs_scheme>`/action,target_nid,apply_interval_us
+    │ │ │ │ │ │ │ :ref:`access_pattern <sysfs_access_pattern>`/
+    │ │ │ │ │ │ │ │ sz/min,max
+    │ │ │ │ │ │ │ │ nr_accesses/min,max
+    │ │ │ │ │ │ │ │ age/min,max
+    │ │ │ │ │ │ │ :ref:`quotas <sysfs_quotas>`/ms,bytes,reset_interval_ms,
+    │ │ │ │ │ │ │     effective_bytes,goal_tuner,
+    │ │ │ │ │ │ │     fail_charge_num,fail_charge_denom
+    │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
+    │ │ │ │ │ │ │ │ :ref:`goals <sysfs_schemes_quota_goals>`/nr_goals
+    │ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value,nid,path
+    │ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
+    │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters
+    │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,damon_target_idx,min,max
+    │ │ │ │ │ │ │ :ref:`dests <damon_sysfs_dests>`/nr_dests
+    │ │ │ │ │ │ │ │ 0/id,weight
+    │ │ │ │ │ │ │ :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds,nr_snapshots,max_nr_snapshots
+    │ │ │ │ │ │ │ :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes
+    │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age,sz_filter_passed
+    │ │ │ │ │ │ │ │ │ probes
+    │ │ │ │ │ │ │ │ │ │ 0/hits
+    │ │ │ │ │ │ │ │ │ │ ...
+    │ │ │ │ │ │ │ │ ...
+    │ │ │ │ │ │ ...
+    │ │ │ │ ...
+    │ │ ...
+
+.. _sysfs_root:
+
+Root
+----
+
+The root of the DAMON sysfs interface is ``<sysfs>/kernel/mm/damon/``, and it
+has one directory named ``admin``.  The directory contains the files for
+privileged user space programs' control of DAMON.  User space tools or daemons
+having the root permission could use this directory.
+
+.. _sysfs_kdamonds:
+
+kdamonds/
+---------
+
+Under the ``admin`` directory, one directory, ``kdamonds``, which has files for
+controlling the kdamonds (refer to
+:ref:`design <damon_design_execution_model_and_data_structures>` for more
+details) exists.  In the beginning, this directory has only one file,
+``nr_kdamonds``.  Writing a number (``N``) to the file creates the number of
+child directories named ``0`` to ``N-1``.  Each directory represents each
+kdamond.
+
+.. _sysfs_kdamond:
+
+kdamonds/<N>/
+-------------
+
+In each kdamond directory, three files (``state``, ``pid`` and ``refresh_ms``)
+and one directory (``contexts``) exist.
+
+Reading ``state`` returns ``on`` if the kdamond is currently running, or
+``off`` if it is not running.
+
+Users can write below commands for the kdamond to the ``state`` file.
+
+- ``on``: Start running.
+- ``off``: Stop running.
+- ``commit``: Read the user inputs in the sysfs files except ``state`` file
+  again.  Monitoring :ref:`target region <sysfs_regions>` inputs are also be
+  ignored if no target region is specified.
+- ``update_tuned_intervals``: Update the contents of ``sample_us`` and
+  ``aggr_us`` files of the kdamond with the auto-tuning applied ``sampling
+  interval`` and ``aggregation interval`` for the files.  Please refer to
+  :ref:`intervals_goal section <damon_usage_sysfs_monitoring_intervals_goal>`
+  for more details.
+- ``commit_schemes_quota_goals``: Read the DAMON-based operation schemes'
+  :ref:`quota goals <sysfs_schemes_quota_goals>`.
+- ``update_schemes_stats``: Update the contents of stats files for each
+  DAMON-based operation scheme of the kdamond.  For details of the stats,
+  please refer to :ref:`stats section <sysfs_schemes_stats>`.
+- ``update_schemes_tried_regions``: Update the DAMON-based operation scheme
+  action tried regions directory for each DAMON-based operation scheme of the
+  kdamond.  For details of the DAMON-based operation scheme action tried
+  regions directory, please refer to
+  :ref:`tried_regions section <sysfs_schemes_tried_regions>`.
+- ``update_schemes_tried_bytes``: Update only ``.../tried_regions/total_bytes``
+  files.
+- ``clear_schemes_tried_regions``: Clear the DAMON-based operating scheme
+  action tried regions directory for each DAMON-based operation scheme of the
+  kdamond.
+- ``update_schemes_effective_quotas``: Update the contents of
+  ``effective_bytes`` files for each DAMON-based operation scheme of the
+  kdamond.  For more details, refer to :ref:`quotas directory <sysfs_quotas>`.
+
+If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread.
+
+Users can ask the kernel to periodically update files showing auto-tuned
+parameters and DAMOS stats instead of manually writing
+``update_tuned_intervals`` like keywords to ``state`` file.  For this, users
+should write the desired update time interval in milliseconds to ``refresh_ms``
+file.  If the interval is zero, the periodic update is disabled.  Reading the
+file shows currently set time interval.
+
+``contexts`` directory contains files for controlling the monitoring contexts
+that this kdamond will execute.
+
+.. _sysfs_contexts:
+
+kdamonds/<N>/contexts/
+----------------------
+
+In the beginning, this directory has only one file, ``nr_contexts``.  Writing a
+number (``N``) to the file creates the number of child directories named as
+``0`` to ``N-1``.  Each directory represents each monitoring context (refer to
+:ref:`design <damon_design_execution_model_and_data_structures>` for more
+details).  At the moment, only one context per kdamond is supported, so only
+``0`` or ``1`` can be written to the file.
+
+.. _sysfs_context:
+
+contexts/<N>/
+-------------
+
+In each context directory, four files (``avail_operations``, ``operations``,
+``addr_unit`` and ``pause``) and three directories (``monitoring_attrs``,
+``targets``, and ``schemes``) exist.
+
+DAMON supports multiple types of :ref:`monitoring operations
+<damon_design_configurable_operations_set>`, including those for virtual address
+space and the physical address space.  You can get the list of available
+monitoring operations set on the currently running kernel by reading
+``avail_operations`` file.  Based on the kernel configuration, the file will
+list different available operation sets.  Please refer to the :ref:`design
+<damon_operations_set>` for the list of all available operation sets and their
+brief explanations.
+
+You can set and get what type of monitoring operations DAMON will use for the
+context by writing one of the keywords listed in ``avail_operations`` file and
+reading from the ``operations`` file.
+
+``addr_unit`` file is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the operations set.
+
+``pause`` file is for setting and getting the :ref:`pause request
+<damon_design_execution_model_and_data_structures>` parameter of the context.
+
+.. _sysfs_monitoring_attrs:
+
+contexts/<N>/monitoring_attrs/
+------------------------------
+
+Files for specifying attributes of the monitoring including required quality
+and efficiency of the monitoring are in ``monitoring_attrs`` directory.
+Specifically, three directories, ``intervals``, ``nr_regions`` and ``probes``
+exist in this directory.
+
+Under ``intervals`` directory, three files for DAMON's sampling interval
+(``sample_us``), aggregation interval (``aggr_us``), and update interval
+(``update_us``) exist.  You can set and get the values in micro-seconds by
+writing to and reading from the files.
+
+Under ``nr_regions`` directory, two files for the lower-bound and upper-bound
+of DAMON's monitoring regions (``min`` and ``max``, respectively), which
+controls the monitoring overhead, exist.  You can set and get the values by
+writing to and reading from the files.
+
+For more details about the intervals and monitoring regions range, please refer
+to the Design document (:doc:`/mm/damon/design`).
+
+.. _damon_usage_sysfs_monitoring_intervals_goal:
+
+contexts/<N>/monitoring_attrs/intervals/intervals_goal/
+-------------------------------------------------------
+
+Under the ``intervals`` directory, one directory for automated tuning of
+``sample_us`` and ``aggr_us``, namely ``intervals_goal`` directory also exists.
+Under the directory, four files for the auto-tuning control, namely
+``access_bp``, ``aggrs``, ``min_sample_us`` and ``max_sample_us`` exist.
+Please refer to  the :ref:`design document of the feature
+<damon_design_monitoring_intervals_autotuning>` for the internal of the tuning
+mechanism.  Reading and writing the four files under ``intervals_goal``
+directory shows and updates the tuning parameters that described in the
+:ref:`design doc <damon_design_monitoring_intervals_autotuning>` with the same
+names.  The tuning starts with the user-set ``sample_us`` and ``aggr_us``.  The
+tuning-applied current values of the two intervals can be read from the
+``sample_us`` and ``aggr_us`` files after writing ``update_tuned_intervals`` to
+the ``state`` file.
+
+.. _damon_usage_sysfs_probes:
+
+contexts/<N>/monitoring_attrs/probes/
+-------------------------------------
+
+A directory for registering :ref:`data attributes monitoring
+<damon_design_data_attrs_monitoring>` probes.
+
+In the beginning, this directory has only one file, ``nr_probes``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each monitoring probe.
+
+In each probe directory, one directory, ``filters`` exists.  The directory
+contains files for installing filters for the probe, that is used to determine
+the data attribute for the probe.
+
+Each probe directory also contains ``weight`` file.  Reading from and writing
+to the file gets and sets the :ref:`attributes-only monitoring
+<damon_design_attrs_only_monitoring>` weight for the attribute of the probe.
+
+In the beginning, ``filters`` directory has only one file, ``nr_filters``.
+Writing a number (``N``) to the file creates the number of child directories
+named ``0`` to ``N-1``.  Each directory represents each filter and works in a
+way similar to that for :ref:`DAMOS filter <sysfs_filters>`.  When the filter
+``type`` is ``memcg``, ``path`` file acts as ``memcg_path`` for :ref:`DAMOS
+filter <sysfs_filters>`.
+
+.. _sysfs_targets:
+
+contexts/<N>/targets/
+---------------------
+
+In the beginning, this directory has only one file, ``nr_targets``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each monitoring target.
+
+.. _sysfs_target:
+
+targets/<N>/
+------------
+
+In each target directory, two files (``pid_target`` and ``obsolete_target``)
+and one directory (``regions``) exist.
+
+If you wrote ``vaddr`` to the ``contexts/<N>/operations``, each target should
+be a process.  You can specify the process to DAMON by writing the pid of the
+process to the ``pid_target`` file.
+
+Users can selectively remove targets in the middle of the targets array by
+writing non-zero value to ``obsolete_target`` file and committing it (writing
+``commit`` to ``state`` file).  DAMON will remove the matching targets from its
+internal targets array.  Users are responsible to construct target directories
+again, so that those correctly represent the changed internal targets array.
+
+
+.. _sysfs_regions:
+
+targets/<N>/regions
+-------------------
+
+In case of ``fvaddr`` or ``paddr`` monitoring operations sets, users are
+required to set the monitoring target address ranges.  In case of ``vaddr``
+operations set, it is not mandatory, but users can optionally set the initial
+monitoring region to specific address ranges.  Please refer to the :ref:`design
+<damon_design_vaddr_target_regions_construction>` for more details.
+
+For such cases, users can explicitly set the initial monitoring target regions
+as they want, by writing proper values to the files under this directory.
+
+In the beginning, this directory has only one file, ``nr_regions``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each initial monitoring target region.
+
+If ``nr_regions`` is zero when committing new DAMON parameters online (writing
+``commit`` to ``state`` file of :ref:`kdamond <sysfs_kdamond>`), the commit
+logic ignores the target regions.  In other words, the current monitoring
+results for the target are preserved.
+
+.. _sysfs_region:
+
+regions/<N>/
+------------
+
+In each region directory, you will find two files (``start`` and ``end``).  You
+can set and get the start and end addresses of the initial monitoring target
+region by writing to and reading from the files, respectively.
+
+Each region should not overlap with others.  ``end`` of directory ``N`` should
+be equal or smaller than ``start`` of directory ``N+1``.
+
+.. _sysfs_schemes:
+
+contexts/<N>/schemes/
+---------------------
+
+The directory for DAMON-based Operation Schemes (:ref:`DAMOS
+<damon_design_damos>`).  Users can get and set the schemes by reading from and
+writing to files under this directory.
+
+In the beginning, this directory has only one file, ``nr_schemes``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each DAMON-based operation scheme.
+
+.. _sysfs_scheme:
+
+schemes/<N>/
+------------
+
+In each scheme directory, nine directories (``access_pattern``, ``quotas``,
+``watermarks``, ``core_filters``, ``ops_filters``, ``filters``, ``dests``,
+``stats``, and ``tried_regions``) and three files (``action``, ``target_nid``
+and ``apply_interval_us``) exist.
+
+The ``action`` file is for setting and getting the scheme's :ref:`action
+<damon_design_damos_action>`.  The keywords that can be written to and read
+from the file and their meaning are same to those of the list on
+:ref:`design doc <damon_design_damos_action>`.
+
+The ``target_nid`` file is for setting the migration target node, which is
+only meaningful when the ``action`` is either ``migrate_hot`` or
+``migrate_cold``.
+
+The ``apply_interval_us`` file is for setting and getting the scheme's
+:ref:`apply_interval <damon_design_damos>` in microseconds.
+
+.. _sysfs_access_pattern:
+
+schemes/<N>/access_pattern/
+---------------------------
+
+The directory for the target access :ref:`pattern
+<damon_design_damos_access_pattern>` of the given DAMON-based operation scheme.
+
+Under the ``access_pattern`` directory, three directories (``sz``,
+``nr_accesses``, and ``age``) each having two files (``min`` and ``max``)
+exist.  You can set and get the access pattern for the given scheme by writing
+to and reading from the ``min`` and ``max`` files under ``sz``,
+``nr_accesses``, and ``age`` directories, respectively.  Note that the ``min``
+and the ``max`` form a closed interval.
+
+.. _sysfs_quotas:
+
+schemes/<N>/quotas/
+-------------------
+
+The directory for the :ref:`quotas <damon_design_damos_quotas>` of the given
+DAMON-based operation scheme.
+
+Under ``quotas`` directory, seven files (``ms``, ``bytes``,
+``reset_interval_ms``, ``effective_bytes``, ``goal_tuner``, ``fail_charge_num``
+and ``fail_charge_denom``) and two directories (``weights`` and ``goals``)
+exist.
+
+You can set the ``time quota`` in milliseconds, ``size quota`` in bytes, and
+``reset interval`` in milliseconds by writing the values to the three files,
+respectively.  Then, DAMON tries to use only up to ``time quota`` milliseconds
+for applying the ``action`` to memory regions of the ``access_pattern``, and to
+apply the action to only up to ``bytes`` bytes of memory regions within the
+``reset_interval_ms``.  Setting both ``ms`` and ``bytes`` zero disables the
+quota limits unless at least one :ref:`goal <sysfs_schemes_quota_goals>` is
+set.
+
+You can set the goal-based effective quota auto-tuning algorithm to use, by
+writing the algorithm name to ``goal_tuner`` file.  Reading the file returns
+the currently selected tuner algorithm.  Refer to the design documentation of
+:ref:`automatic quota tuning goals <damon_design_damos_quotas_auto_tuning>` for
+the background design of the feature and the name of the selectable algorithms.
+Refer to :ref:`goals directory <sysfs_schemes_quota_goals>` for the goals
+setup.
+
+You can set the action-failed memory quota charging ratio by writing the
+numerator and the denominator for the ratio to ``fail_charge_num`` and
+``fail_charge_denom`` files, respectively.  Reading those files will return the
+current set values.  Refer to :ref:`design
+<damon_design_damos_quotas_failed_memory_charging_ratio>` for more details of
+the ratio feature.
+
+The time quota is internally transformed to a size quota.  Between the
+transformed size quota and user-specified size quota, smaller one is applied.
+Based on the user-specified :ref:`goal <sysfs_schemes_quota_goals>`, the
+effective size quota is further adjusted.  Reading ``effective_bytes`` returns
+the current effective size quota.  The file is not updated in real time, so
+users should ask DAMON sysfs interface to update the content of the file for
+the stats by writing a special keyword, ``update_schemes_effective_quotas`` to
+the relevant ``kdamonds/<N>/state`` file.
+
+Under ``weights`` directory, three files (``sz_permil``,
+``nr_accesses_permil``, and ``age_permil``) exist.
+You can set the :ref:`prioritization weights
+<damon_design_damos_quotas_prioritization>` for size, access frequency, and age
+in per-thousand unit by writing the values to the three files under the
+``weights`` directory.
+
+.. _sysfs_schemes_quota_goals:
+
+schemes/<N>/quotas/goals/
+-------------------------
+
+The directory for the :ref:`automatic quota tuning goals
+<damon_design_damos_quotas_auto_tuning>` of the given DAMON-based operation
+scheme.
+
+In the beginning, this directory has only one file, ``nr_goals``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each goal and current achievement.
+Among the multiple feedback, the best one is used.
+
+Each goal directory contains five files, namely ``target_metric``,
+``target_value``, ``current_value``, ``nid``, and ``path``.  Users can set and
+get the five parameters for the quota auto-tuning goals that specified on the
+:ref:`design doc <damon_design_damos_quotas_auto_tuning>` by writing to and
+reading from each of the files.  Because the kernel does not update
+``current_value``, reading it only makes sense when ``target_metric`` is
+``user_input``.  Note that users should further write
+``commit_schemes_quota_goals`` to the ``state`` file of the :ref:`kdamond
+directory <sysfs_kdamond>` to pass the feedback to DAMON.
+
+.. _sysfs_watermarks:
+
+schemes/<N>/watermarks/
+-----------------------
+
+The directory for the :ref:`watermarks <damon_design_damos_watermarks>` of the
+given DAMON-based operation scheme.
+
+Under the watermarks directory, five files (``metric``, ``interval_us``,
+``high``, ``mid``, and ``low``) for setting the metric, the time interval
+between check of the metric, and the three watermarks exist.  You can set and
+get the five values by writing to and reading from the files, respectively.
+
+Keywords and meanings of those that can be written to the ``metric`` file are
+as below.
+
+ - none: Ignore the watermarks
+ - free_mem_rate: System's free memory rate (per thousand)
+
+The ``interval_us`` should be written in microseconds unit.
+
+.. _sysfs_filters:
+
+schemes/<N>/{core\_,ops\_,}filters/
+-----------------------------------
+
+Directories for :ref:`filters <damon_design_damos_filters>` of the given
+DAMON-based operation scheme.
+
+``core_filters`` and ``ops_filters`` directories are for the filters handled by
+the DAMON core layer and operations set layer, respectively.  ``filters``
+directory can be used for installing filters regardless of their handled
+layers.  Filters that requested by ``core_filters`` and ``ops_filters`` will be
+installed before those of ``filters``.  All three directories have same files.
+
+Use of ``filters`` directory can make filters evaluation orders confusing to
+expect.  For this reason, ``filters`` directory is deprecated.  It is still
+functioning, but is scheduled for removal in the near future.  Users should use
+``core_filters`` and ``ops_filters`` directories instead.
+
+In the beginning, the directory has only one file, ``nr_filters``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each filter.  The filters are evaluated
+in the numeric order.
+
+Each filter directory contains nine files, namely ``type``, ``matching``,
+``allow``, ``memcg_path``, ``addr_start``, ``addr_end``, ``min``, ``max``
+and ``damon_target_idx``.  To ``type`` file, you can write the type of the
+filter.  Refer to :ref:`the design doc <damon_design_damos_filters>` for
+available type names, their meaning and on what layer those are handled.
+
+For ``memcg`` type, you can specify the memory cgroup of the interest by
+writing the path of the memory cgroup from the cgroups mount point to
+``memcg_path`` file.  For ``addr`` type, you can specify the start and end
+address of the range (open-ended interval) to ``addr_start`` and ``addr_end``
+files, respectively.  For ``hugepage_size`` type, you can specify the minimum
+and maximum size of the range (closed interval) to ``min`` and ``max`` files,
+respectively.  For ``target`` type, you can specify the index of the target
+between the list of the DAMON context's monitoring targets list to
+``damon_target_idx`` file.
+
+You can write ``Y`` or ``N`` to ``matching`` file to specify whether the filter
+is for memory that matches the ``type``.  You can write ``Y`` or ``N`` to
+``allow`` file to specify if applying the action to the memory that satisfies
+the ``type`` and ``matching`` should be allowed or not.
+
+For example, below restricts a DAMOS action to be applied to only non-anonymous
+pages of all memory cgroups except ``/having_care_already``.::
+
+    # cd ops_filters/0/
+    # echo 2 > nr_filters
+    # # disallow anonymous pages
+    echo anon > 0/type
+    echo Y > 0/matching
+    echo N > 0/allow
+    # # further filter out all cgroups except one at '/having_care_already'
+    echo memcg > 1/type
+    echo /having_care_already > 1/memcg_path
+    echo Y > 1/matching
+    echo N > 1/allow
+
+Refer to the :ref:`DAMOS filters design documentation
+<damon_design_damos_filters>` for more details including how multiple filters
+of different ``allow`` works, when each of the filters are supported, and
+differences on stats.
+
+.. _damon_sysfs_dests:
+
+schemes/<N>/dests/
+------------------
+
+Directory for specifying the destinations of given DAMON-based operation
+scheme's action.  This directory is ignored if the action of the given scheme
+is not supporting multiple destinations.  Only ``DAMOS_MIGRATE_{HOT,COLD}``
+actions are supporting multiple destinations.
+
+In the beginning, the directory has only one file, ``nr_dests``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each action destination.
+
+Each destination directory contains two files, namely ``id`` and ``weight``.
+Users can write and read the identifier of the destination to ``id`` file.
+For ``DAMOS_MIGRATE_{HOT,COLD}`` actions, the migrate destination node's node
+id should be written to ``id`` file.  Users can write and read the weight of
+the destination among the given destinations to the ``weight`` file.  The
+weight can be an arbitrary integer.  When DAMOS apply the action to each entity
+of the memory region, it will select the destination of the action based on the
+relative weights of the destinations.
+
+.. _sysfs_schemes_stats:
+
+schemes/<N>/stats/
+------------------
+
+DAMON counts statistics for each scheme.  This statistics can be used for
+online analysis or tuning of the schemes.  Refer to :ref:`design doc
+<damon_design_damos_stat>` for more details about the stats.
+
+The statistics can be retrieved by reading the files under ``stats`` directory
+(``nr_tried``, ``sz_tried``, ``nr_applied``, ``sz_applied``,
+``sz_ops_filter_passed``, ``qt_exceeds``, ``nr_snapshots`` and
+``max_nr_snapshots``), respectively.
+
+The files are not updated in real time by default.  Users should ask DAMON
+sysfs interface to periodically update those using ``refresh_ms``, or do a one
+time update by writing a special keyword, ``update_schemes_stats`` to the
+relevant ``kdamonds/<N>/state`` file.  Refer to :ref:`kdamond directory
+<sysfs_kdamond>` for more details.
+
+.. _sysfs_schemes_tried_regions:
+
+schemes/<N>/tried_regions/
+--------------------------
+
+This directory initially has one file, ``total_bytes``.
+
+When a special keyword, ``update_schemes_tried_regions``, is written to the
+relevant ``kdamonds/<N>/state`` file, DAMON updates the ``total_bytes`` file so
+that reading it returns the total size of the scheme tried regions, and creates
+directories named integer starting from ``0`` under this directory.  Each
+directory contains files exposing detailed information about each of the memory
+region that the corresponding scheme's ``action`` has tried to be applied under
+this directory, during next :ref:`apply interval <damon_design_damos>` of the
+corresponding scheme.  The information includes address range, ``nr_accesses``,
+and ``age`` of the region.
+
+Writing ``update_schemes_tried_bytes`` to the relevant ``kdamonds/<N>/state``
+file will only update the ``total_bytes`` file, and will not create the
+subdirectories.
+
+The directories will be removed when another special keyword,
+``clear_schemes_tried_regions``, is written to the relevant
+``kdamonds/<N>/state`` file.
+
+The expected usage of this directory is investigations of schemes' behaviors,
+and query-like efficient data access monitoring results retrievals.  For the
+latter use case, in particular, users can set the ``action`` as ``stat`` and
+set the ``access pattern`` as their interested pattern that they want to query.
+
+.. _sysfs_schemes_tried_region:
+
+tried_regions/<N>/
+------------------
+
+In each region directory, you will find five files (``start``, ``end``,
+``nr_accesses``, ``age`` and ``sz_filter_passed``).  Reading the files will
+show the properties of the region that corresponding DAMON-based operation
+scheme ``action`` has tried to be applied.
+
+tried_regions/<N>/probes/
+-------------------------
+
+In each region directory, one directory (``probes``) also exists.  In the
+directory, subdirectories named ``0`` to ``N-1`` exists.  ``N`` is the number
+of installed probes.  In each number-named directory, a file (``hits``) exist.
+Reading the file shows the number of data attributes monitoring probe-hit
+positive samples of the region.
+
+Example
+~~~~~~~
+
+Below commands applies a scheme saying "If a memory region of size in [4KiB,
+8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate
+interval in [10, 20], page out the region.  For the paging out, use only up to
+10ms per second, and also don't page out more than 1GiB per second.  Under the
+limitation, page out memory regions having longer age first.  Also, check the
+free memory rate of the system every 5 seconds, start the monitoring and paging
+out when the free memory rate becomes lower than 50%, but stop it if the free
+memory rate becomes larger than 60%, or lower than 30%". ::
+
+    # cd <sysfs>/kernel/mm/damon/admin
+    # # populate directories
+    # echo 1 > kdamonds/nr_kdamonds; echo 1 > kdamonds/0/contexts/nr_contexts;
+    # echo 1 > kdamonds/0/contexts/0/schemes/nr_schemes
+    # cd kdamonds/0/contexts/0/schemes/0
+    # # set the basic access pattern and the action
+    # echo 4096 > access_pattern/sz/min
+    # echo 8192 > access_pattern/sz/max
+    # echo 0 > access_pattern/nr_accesses/min
+    # echo 5 > access_pattern/nr_accesses/max
+    # echo 10 > access_pattern/age/min
+    # echo 20 > access_pattern/age/max
+    # echo pageout > action
+    # # set quotas
+    # echo 10 > quotas/ms
+    # echo $((1024*1024*1024)) > quotas/bytes
+    # echo 1000 > quotas/reset_interval_ms
+    # # set watermark
+    # echo free_mem_rate > watermarks/metric
+    # echo 5000000 > watermarks/interval_us
+    # echo 600 > watermarks/high
+    # echo 500 > watermarks/mid
+    # echo 300 > watermarks/low
+
+Please note that it's highly recommended to use user space tools like `damo
+<https://github.com/damonitor/damo>`_ rather than manually reading and writing
+the files as above.  Above is only for an example.
+
+.. _tracepoint:
+
+Tracepoints for Monitoring Results
+==================================
+
+Users can get the monitoring results via the :ref:`tried_regions
+<sysfs_schemes_tried_regions>`.  The interface is useful for getting a
+snapshot, but it could be inefficient for fully recording all the monitoring
+results.  For the purpose, two trace points, namely ``damon:damon_aggregated``
+and ``damon:damos_before_apply``, are provided.  ``damon:damon_aggregated``
+provides the whole monitoring results, while ``damon:damos_before_apply``
+provides the monitoring results for regions that each DAMON-based Operation
+Scheme (:ref:`DAMOS <damon_design_damos>`) is gonna be applied.  Hence,
+``damon:damos_before_apply`` is more useful for recording internal behavior of
+DAMOS, or DAMOS target access
+:ref:`pattern <damon_design_damos_access_pattern>` based query-like efficient
+monitoring results recording.
+
+While the monitoring is turned on, you could record the tracepoint events and
+show results using tracepoint supporting tools like ``perf``.  For example::
+
+    # echo on > kdamonds/0/state
+    # perf record -e damon:damon_aggregated &
+    # sleep 5
+    # kill 9 $(pidof perf)
+    # echo off > kdamonds/0/state
+    # perf script
+    kdamond.0 46568 [027] 79357.842179: damon:damon_aggregated: target_id=0 nr_regions=11 122509119488-135708762112: 0 864
+    [...]
+
+Each line of the perf script output represents each monitoring region.  The
+first five fields are as usual other tracepoint outputs.  The sixth field
+(``target_id=X``) shows the id of the monitoring target of the region.  The
+seventh field (``nr_regions=X``) shows the total number of monitoring regions
+for the target.  The eighth field (``X-Y:``) shows the start (``X``) and end
+(``Y``) addresses of the region in bytes.  The ninth field (``X``) shows the
+``nr_accesses`` of the region (refer to
+:ref:`design <damon_design_region_based_sampling>` for more details of the
+counter).  Finally the tenth field (``X``) shows the ``age`` of the region
+(refer to :ref:`design <damon_design_age_tracking>` for more details of the
+counter).
+
+If the event was ``damon:damos_before_apply``, the ``perf script`` output would
+be somewhat like below::
+
+    kdamond.0 47293 [000] 80801.060214: damon:damos_before_apply: ctx_idx=0 scheme_idx=0 target_idx=0 nr_regions=11 121932607488-135128711168: 0 136
+    [...]
+
+Each line of the output represents each monitoring region that each DAMON-based
+Operation Scheme was about to be applied at the traced time.  The first five
+fields are as usual.  It shows the index of the DAMON context (``ctx_idx=X``)
+of the scheme in the list of the contexts of the context's kdamond, the index
+of the scheme (``scheme_idx=X``) in the list of the schemes of the context, in
+addition to the output of ``damon_aggregated`` tracepoint.
diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
new file mode 100644
index 000000000..3cc15d800
--- /dev/null
+++ b/Documentation/admin-guide/mm/hugetlbpage.rst
@@ -0,0 +1,487 @@
+=============
+HugeTLB Pages
+=============
+
+Overview
+========
+
+The intent of this file is to give a brief summary of hugetlbpage support in
+the Linux kernel.  This support is built on top of multiple page size support
+that is provided by most modern architectures.  For example, x86 CPUs normally
+support 4K and 2M (1G if architecturally supported) page sizes, ia64
+architecture supports multiple page sizes 4K, 8K, 64K, 256K, 1M, 4M, 16M,
+256M and ppc64 supports 4K and 16M.  A TLB is a cache of virtual-to-physical
+translations.  Typically this is a very scarce resource on processor.
+Operating systems try to make best use of limited number of TLB resources.
+This optimization is more critical now as bigger and bigger physical memories
+(several GBs) are more readily available.
+
+Users can use the huge page support in Linux kernel by either using the mmap
+system call or standard SYSV shared memory system calls (shmget, shmat).
+
+First the Linux kernel needs to be built with the CONFIG_HUGETLBFS
+(present under "File systems") and CONFIG_HUGETLB_PAGE (selected
+automatically when CONFIG_HUGETLBFS is selected) configuration
+options.
+
+The ``/proc/meminfo`` file provides information about the total number of
+persistent hugetlb pages in the kernel's huge page pool.  It also displays
+default huge page size and information about the number of free, reserved
+and surplus huge pages in the pool of huge pages of default size.
+The huge page size is needed for generating the proper alignment and
+size of the arguments to system calls that map huge page regions.
+
+The output of ``cat /proc/meminfo`` will include lines like::
+
+	HugePages_Total: uuu
+	HugePages_Free:  vvv
+	HugePages_Rsvd:  www
+	HugePages_Surp:  xxx
+	Hugepagesize:    yyy kB
+	Hugetlb:         zzz kB
+
+where:
+
+HugePages_Total
+	is the size of the pool of huge pages.
+HugePages_Free
+	is the number of huge pages in the pool that are not yet
+        allocated.
+HugePages_Rsvd
+	is short for "reserved," and is the number of huge pages for
+        which a commitment to allocate from the pool has been made,
+        but no allocation has yet been made.  Reserved huge pages
+        guarantee that an application will be able to allocate a
+        huge page from the pool of huge pages at fault time.
+HugePages_Surp
+	is short for "surplus," and is the number of huge pages in
+        the pool above the value in ``/proc/sys/vm/nr_hugepages``. The
+        maximum number of surplus huge pages is controlled by
+        ``/proc/sys/vm/nr_overcommit_hugepages``.
+	Note: When the feature of freeing unused vmemmap pages associated
+	with each hugetlb page is enabled, the number of surplus huge pages
+	may be temporarily larger than the maximum number of surplus huge
+	pages when the system is under memory pressure.
+Hugepagesize
+	is the default hugepage size (in kB).
+Hugetlb
+        is the total amount of memory (in kB), consumed by huge
+        pages of all sizes.
+        If huge pages of different sizes are in use, this number
+        will exceed HugePages_Total \* Hugepagesize. To get more
+        detailed information, please, refer to
+        ``/sys/kernel/mm/hugepages`` (described below).
+
+
+``/proc/filesystems`` should also show a filesystem of type "hugetlbfs"
+configured in the kernel.
+
+``/proc/sys/vm/nr_hugepages`` indicates the current number of "persistent" huge
+pages in the kernel's huge page pool.  "Persistent" huge pages will be
+returned to the huge page pool when freed by a task.  A user with root
+privileges can dynamically allocate more or free some persistent huge pages
+by increasing or decreasing the value of ``nr_hugepages``.
+
+Note: When the feature of freeing unused vmemmap pages associated with each
+hugetlb page is enabled, we can fail to free the huge pages triggered by
+the user when the system is under memory pressure.  Please try again later.
+
+Pages that are used as huge pages are reserved inside the kernel and cannot
+be used for other purposes.  Huge pages cannot be swapped out under
+memory pressure.
+
+Once a number of huge pages have been pre-allocated to the kernel huge page
+pool, a user with appropriate privilege can use either the mmap system call
+or shared memory system calls to use the huge pages.  See the discussion of
+:ref:`Using Huge Pages <using_huge_pages>`, below.
+
+The administrator can allocate persistent huge pages on the kernel boot
+command line by specifying the "hugepages=N" parameter, where 'N' = the
+number of huge pages requested.  This is the most reliable method of
+allocating huge pages as memory has not yet become fragmented.
+
+Some platforms support multiple huge page sizes.  To allocate huge pages
+of a specific size, one must precede the huge pages boot command parameters
+with a huge page size selection parameter "hugepagesz=<size>".  <size> must
+be specified in bytes with optional scale suffix [kKmMgG].  The default huge
+page size may be selected with the "default_hugepagesz=<size>" boot parameter.
+
+Hugetlb boot command line parameter semantics
+
+hugepagesz
+	Specify a huge page size.  Used in conjunction with hugepages
+	parameter to preallocate a number of huge pages of the specified
+	size.  Hence, hugepagesz and hugepages are typically specified in
+	pairs such as::
+
+		hugepagesz=2M hugepages=512
+
+	hugepagesz can only be specified once on the command line for a
+	specific huge page size.  Valid huge page sizes are architecture
+	dependent.
+hugepages
+	Specify the number of huge pages to preallocate.  This typically
+	follows a valid hugepagesz or default_hugepagesz parameter.  However,
+	if hugepages is the first or only hugetlb command line parameter it
+	implicitly specifies the number of huge pages of default size to
+	allocate.  If the number of huge pages of default size is implicitly
+	specified, it can not be overwritten by a hugepagesz,hugepages
+	parameter pair for the default size.  This parameter also has a
+	node format.  The node format specifies the number of huge pages
+	to allocate on specific nodes.
+
+	For example, on an architecture with 2M default huge page size::
+
+		hugepages=256 hugepagesz=2M hugepages=512
+
+	will result in 256 2M huge pages being allocated and a warning message
+	indicating that the hugepages=512 parameter is ignored.  If a hugepages
+	parameter is preceded by an invalid hugepagesz parameter, it will
+	be ignored.
+
+	Node format example::
+
+		hugepagesz=2M hugepages=0:1,1:2
+
+	It will allocate 1 2M hugepage on node0 and 2 2M hugepages on node1.
+	If the node number is invalid,  the parameter will be ignored.
+hugepage_alloc_threads
+	Specify the number of threads that should be used to allocate hugepages
+	during boot. This parameter can be used to improve system bootup time
+	when allocating a large amount of huge pages.
+
+	The default value is 25% of the available hardware threads.
+	Example to use 8 allocation threads::
+
+		hugepage_alloc_threads=8
+
+	Note that this parameter only applies to non-gigantic huge pages.
+default_hugepagesz
+	Specify the default huge page size.  This parameter can
+	only be specified once on the command line.  default_hugepagesz can
+	optionally be followed by the hugepages parameter to preallocate a
+	specific number of huge pages of default size.  The number of default
+	sized huge pages to preallocate can also be implicitly specified as
+	mentioned in the hugepages section above.  Therefore, on an
+	architecture with 2M default huge page size::
+
+		hugepages=256
+		default_hugepagesz=2M hugepages=256
+		hugepages=256 default_hugepagesz=2M
+
+	will all result in 256 2M huge pages being allocated.  Valid default
+	huge page size is architecture dependent.
+hugetlb_free_vmemmap
+	When CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is set, this enables HugeTLB
+	Vmemmap Optimization (HVO).
+
+When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
+indicates the current number of pre-allocated huge pages of the default size.
+Thus, one can use the following command to dynamically allocate/deallocate
+default sized persistent huge pages::
+
+	echo 20 > /proc/sys/vm/nr_hugepages
+
+This command will try to adjust the number of default sized huge pages in the
+huge page pool to 20, allocating or freeing huge pages, as required.
+
+On a NUMA platform, the kernel will attempt to distribute the huge page pool
+over all the set of allowed nodes specified by the NUMA memory policy of the
+task that modifies ``nr_hugepages``. The default for the allowed nodes--when the
+task has default memory policy--is all on-line nodes with memory.  Allowed
+nodes with insufficient available, contiguous memory for a huge page will be
+silently skipped when allocating persistent huge pages.  See the
+:ref:`discussion below <mem_policy_and_hp_alloc>`
+of the interaction of task memory policy, cpusets and per node attributes
+with the allocation and freeing of persistent huge pages.
+
+The success or failure of huge page allocation depends on the amount of
+physically contiguous memory that is present in system at the time of the
+allocation attempt.  If the kernel is unable to allocate huge pages from
+some nodes in a NUMA system, it will attempt to make up the difference by
+allocating extra pages on other nodes with sufficient available contiguous
+memory, if any.
+
+System administrators may want to put this command in one of the local rc
+init files.  This will enable the kernel to allocate huge pages early in
+the boot process when the possibility of getting physical contiguous pages
+is still very high.  Administrators can verify the number of huge pages
+actually allocated by checking the sysctl or meminfo.  To check the per node
+distribution of huge pages in a NUMA system, use::
+
+	cat /sys/devices/system/node/node*/meminfo | fgrep Huge
+
+``/proc/sys/vm/nr_overcommit_hugepages`` specifies how large the pool of
+huge pages can grow, if more huge pages than ``/proc/sys/vm/nr_hugepages`` are
+requested by applications.  Writing any non-zero value into this file
+indicates that the hugetlb subsystem is allowed to try to obtain that
+number of "surplus" huge pages from the kernel's normal page pool, when the
+persistent huge page pool is exhausted. As these surplus huge pages become
+unused, they are freed back to the kernel's normal page pool.
+
+When increasing the huge page pool size via ``nr_hugepages``, any existing
+surplus pages will first be promoted to persistent huge pages.  Then, additional
+huge pages will be allocated, if necessary and if possible, to fulfill
+the new persistent huge page pool size.
+
+The administrator may shrink the pool of persistent huge pages for
+the default huge page size by setting the ``nr_hugepages`` sysctl to a
+smaller value.  The kernel will attempt to balance the freeing of huge pages
+across all nodes in the memory policy of the task modifying ``nr_hugepages``.
+Any free huge pages on the selected nodes will be freed back to the kernel's
+normal page pool.
+
+Caveat: Shrinking the persistent huge page pool via ``nr_hugepages`` such that
+it becomes less than the number of huge pages in use will convert the balance
+of the in-use huge pages to surplus huge pages.  This will occur even if
+the number of surplus pages would exceed the overcommit value.  As long as
+this condition holds--that is, until ``nr_hugepages+nr_overcommit_hugepages`` is
+increased sufficiently, or the surplus huge pages go out of use and are freed--
+no more surplus huge pages will be allowed to be allocated.
+
+With support for multiple huge page pools at run-time available, much of
+the huge page userspace interface in ``/proc/sys/vm`` has been duplicated in
+sysfs.
+The ``/proc`` interfaces discussed above have been retained for backwards
+compatibility. The root huge page control directory in sysfs is::
+
+	/sys/kernel/mm/hugepages
+
+For each huge page size supported by the running kernel, a subdirectory
+will exist, of the form::
+
+	hugepages-${size}kB
+
+Inside each of these directories, the set of files contained in ``/proc``
+will exist.  In addition, two additional interfaces for demoting huge
+pages may exist::
+
+        demote
+        demote_size
+	nr_hugepages
+	nr_hugepages_mempolicy
+	nr_overcommit_hugepages
+	free_hugepages
+	resv_hugepages
+	surplus_hugepages
+
+The demote interfaces provide the ability to split a huge page into
+smaller huge pages.  For example, the x86 architecture supports both
+1GB and 2MB huge pages sizes.  A 1GB huge page can be split into 512
+2MB huge pages.  Demote interfaces are not available for the smallest
+huge page size.  The demote interfaces are:
+
+demote_size
+        is the size of demoted pages.  When a page is demoted a corresponding
+        number of huge pages of demote_size will be created.  By default,
+        demote_size is set to the next smaller huge page size.  If there are
+        multiple smaller huge page sizes, demote_size can be set to any of
+        these smaller sizes.  Only huge page sizes less than the current huge
+        pages size are allowed.
+
+demote
+        is used to demote a number of huge pages.  A user with root privileges
+        can write to this file.  It may not be possible to demote the
+        requested number of huge pages.  To determine how many pages were
+        actually demoted, compare the value of nr_hugepages before and after
+        writing to the demote interface.  demote is a write only interface.
+
+The interfaces which are the same as in ``/proc`` (all except demote and
+demote_size) function as described above for the default huge page-sized case.
+
+.. _mem_policy_and_hp_alloc:
+
+Interaction of Task Memory Policy with Huge Page Allocation/Freeing
+===================================================================
+
+Whether huge pages are allocated and freed via the ``/proc`` interface or
+the ``/sysfs`` interface using the ``nr_hugepages_mempolicy`` attribute, the
+NUMA nodes from which huge pages are allocated or freed are controlled by the
+NUMA memory policy of the task that modifies the ``nr_hugepages_mempolicy``
+sysctl or attribute.  When the ``nr_hugepages`` attribute is used, mempolicy
+is ignored.
+
+The recommended method to allocate or free huge pages to/from the kernel
+huge page pool, using the ``nr_hugepages`` example above, is::
+
+    numactl --interleave <node-list> echo 20 \
+				>/proc/sys/vm/nr_hugepages_mempolicy
+
+or, more succinctly::
+
+    numactl -m <node-list> echo 20 >/proc/sys/vm/nr_hugepages_mempolicy
+
+This will allocate or free ``abs(20 - nr_hugepages)`` to or from the nodes
+specified in <node-list>, depending on whether number of persistent huge pages
+is initially less than or greater than 20, respectively.  No huge pages will be
+allocated nor freed on any node not included in the specified <node-list>.
+
+When adjusting the persistent hugepage count via ``nr_hugepages_mempolicy``, any
+memory policy mode--bind, preferred, local or interleave--may be used.  The
+resulting effect on persistent huge page allocation is as follows:
+
+#. Regardless of mempolicy mode [see
+   Documentation/admin-guide/mm/numa_memory_policy.rst],
+   persistent huge pages will be distributed across the node or nodes
+   specified in the mempolicy as if "interleave" had been specified.
+   However, if a node in the policy does not contain sufficient contiguous
+   memory for a huge page, the allocation will not "fallback" to the nearest
+   neighbor node with sufficient contiguous memory.  To do this would cause
+   undesirable imbalance in the distribution of the huge page pool, or
+   possibly, allocation of persistent huge pages on nodes not allowed by
+   the task's memory policy.
+
+#. One or more nodes may be specified with the bind or interleave policy.
+   If more than one node is specified with the preferred policy, only the
+   lowest numeric id will be used.  Local policy will select the node where
+   the task is running at the time the nodes_allowed mask is constructed.
+   For local policy to be deterministic, the task must be bound to a cpu or
+   cpus in a single node.  Otherwise, the task could be migrated to some
+   other node at any time after launch and the resulting node will be
+   indeterminate.  Thus, local policy is not very useful for this purpose.
+   Any of the other mempolicy modes may be used to specify a single node.
+
+#. The nodes allowed mask will be derived from any non-default task mempolicy,
+   whether this policy was set explicitly by the task itself or one of its
+   ancestors, such as numactl.  This means that if the task is invoked from a
+   shell with non-default policy, that policy will be used.  One can specify a
+   node list of "all" with numactl --interleave or --membind [-m] to achieve
+   interleaving over all nodes in the system or cpuset.
+
+#. Any task mempolicy specified--e.g., using numactl--will be constrained by
+   the resource limits of any cpuset in which the task runs.  Thus, there will
+   be no way for a task with non-default policy running in a cpuset with a
+   subset of the system nodes to allocate huge pages outside the cpuset
+   without first moving to a cpuset that contains all of the desired nodes.
+
+#. Boot-time huge page allocation attempts to distribute the requested number
+   of huge pages over all on-lines nodes with memory.
+
+Per Node Hugepages Attributes
+=============================
+
+A subset of the contents of the root huge page control directory in sysfs,
+described above, will be replicated under each the system device of each
+NUMA node with memory in::
+
+	/sys/devices/system/node/node[0-9]*/hugepages/
+
+Under this directory, the subdirectory for each supported huge page size
+contains the following attribute files::
+
+	nr_hugepages
+	free_hugepages
+	surplus_hugepages
+
+The free\_' and surplus\_' attribute files are read-only.  They return the number
+of free and surplus [overcommitted] huge pages, respectively, on the parent
+node.
+
+The ``nr_hugepages`` attribute returns the total number of huge pages on the
+specified node.  When this attribute is written, the number of persistent huge
+pages on the parent node will be adjusted to the specified value, if sufficient
+resources exist, regardless of the task's mempolicy or cpuset constraints.
+
+Note that the number of overcommit and reserve pages remain global quantities,
+as we don't know until fault time, when the faulting task's mempolicy is
+applied, from which node the huge page allocation will be attempted.
+
+The hugetlb may be migrated between the per-node hugepages pool in the following
+scenarios: memory offline, memory failure, longterm pinning, syscalls(mbind,
+migrate_pages and move_pages), alloc_contig_range() and alloc_contig_pages().
+Now only memory offline, memory failure and syscalls allow fallbacking to allocate
+a new hugetlb on a different node if the current node is unable to allocate during
+hugetlb migration, that means these 3 cases can break the per-node hugepages pool.
+
+.. _using_huge_pages:
+
+Using Huge Pages
+================
+
+If the user applications are going to request huge pages using mmap system
+call, then it is required that system administrator mount a file system of
+type hugetlbfs::
+
+  mount -t hugetlbfs \
+	-o uid=<value>,gid=<value>,mode=<value>,pagesize=<value>,size=<value>,\
+	min_size=<value>,nr_inodes=<value> none /mnt/huge
+
+This command mounts a (pseudo) filesystem of type hugetlbfs on the directory
+``/mnt/huge``.  Any file created on ``/mnt/huge`` uses huge pages.
+
+The ``uid`` and ``gid`` options sets the owner and group of the root of the
+file system.  By default the ``uid`` and ``gid`` of the current process
+are taken.
+
+The ``mode`` option sets the mode of root of file system to value & 01777.
+This value is given in octal. By default the value 0755 is picked.
+
+If the platform supports multiple huge page sizes, the ``pagesize`` option can
+be used to specify the huge page size and associated pool. ``pagesize``
+is specified in bytes. If ``pagesize`` is not specified the platform's
+default huge page size and associated pool will be used.
+
+The ``size`` option sets the maximum value of memory (huge pages) allowed
+for that filesystem (``/mnt/huge``). The ``size`` option can be specified
+in bytes, or as a percentage of the specified huge page pool (``nr_hugepages``).
+The size is rounded down to HPAGE_SIZE boundary.
+
+The ``min_size`` option sets the minimum value of memory (huge pages) allowed
+for the filesystem. ``min_size`` can be specified in the same way as ``size``,
+either bytes or a percentage of the huge page pool.
+At mount time, the number of huge pages specified by ``min_size`` are reserved
+for use by the filesystem.
+If there are not enough free huge pages available, the mount will fail.
+As huge pages are allocated to the filesystem and freed, the reserve count
+is adjusted so that the sum of allocated and reserved huge pages is always
+at least ``min_size``.
+
+The option ``nr_inodes`` sets the maximum number of inodes that ``/mnt/huge``
+can use.
+
+If the ``size``, ``min_size`` or ``nr_inodes`` option is not provided on
+command line then no limits are set.
+
+For ``pagesize``, ``size``, ``min_size`` and ``nr_inodes`` options, you can
+use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo.
+For example, size=2K has the same meaning as size=2048.
+
+While read system calls are supported on files that reside on hugetlb
+file systems, write system calls are not.
+
+Regular chown, chgrp, and chmod commands (with right permissions) could be
+used to change the file attributes on hugetlbfs.
+
+Also, it is important to note that no such mount command is required if
+applications are going to use only shmat/shmget system calls or mmap with
+MAP_HUGETLB.  For an example of how to use mmap with MAP_HUGETLB see
+:ref:`examples <examples>` below.
+
+Users who wish to use hugetlb memory via shared memory segment should be
+members of a supplementary group and system admin needs to configure that gid
+into ``/proc/sys/vm/hugetlb_shm_group``.  It is possible for same or different
+applications to use any combination of mmaps and shm* calls, though the mount of
+filesystem will be required for using mmap calls without MAP_HUGETLB.
+
+Syscalls that operate on memory backed by hugetlb pages only have their lengths
+aligned to the native page size of the processor; they will normally fail with
+errno set to EINVAL or exclude hugetlb pages that extend beyond the length if
+not hugepage aligned.  For example, munmap(2) will fail if memory is backed by
+a hugetlb page and the length is smaller than the hugepage size.
+
+
+Examples
+========
+
+.. _examples:
+
+``hugetlb-shm``
+	see tools/testing/selftests/mm/hugetlb-shm.c
+
+``hugetlb-mmap``
+	see tools/testing/selftests/mm/hugetlb-mmap.c
+
+The `libhugetlbfs`_  library provides a wide range of userspace tools
+to help with huge page usability, environment setup, and control.
+
+.. _libhugetlbfs: https://github.com/libhugetlbfs/libhugetlbfs
diff --git a/Documentation/admin-guide/mm/idle_page_tracking.rst b/Documentation/admin-guide/mm/idle_page_tracking.rst
new file mode 100644
index 000000000..16fcf38da
--- /dev/null
+++ b/Documentation/admin-guide/mm/idle_page_tracking.rst
@@ -0,0 +1,118 @@
+==================
+Idle Page Tracking
+==================
+
+Motivation
+==========
+
+The idle page tracking feature allows to track which memory pages are being
+accessed by a workload and which are idle. This information can be useful for
+estimating the workload's working set size, which, in turn, can be taken into
+account when configuring the workload parameters, setting memory cgroup limits,
+or deciding where to place the workload within a compute cluster.
+
+It is enabled by CONFIG_IDLE_PAGE_TRACKING=y.
+
+.. _user_api:
+
+User API
+========
+
+The idle page tracking API is located at ``/sys/kernel/mm/page_idle``.
+Currently, it consists of the only read-write file,
+``/sys/kernel/mm/page_idle/bitmap``.
+
+The file implements a bitmap where each bit corresponds to a memory page. The
+bitmap is represented by an array of 8-byte integers, and the page at PFN #i is
+mapped to bit #i%64 of array element #i/64, byte order is native. When a bit is
+set, the corresponding page is idle.
+
+A page is considered idle if it has not been accessed since it was marked idle
+(for more details on what "accessed" actually means see the :ref:`Implementation
+Details <impl_details>` section).
+To mark a page idle one has to set the bit corresponding to
+the page by writing to the file. A value written to the file is OR-ed with the
+current bitmap value.
+
+Only accesses to user memory pages are tracked. These are pages mapped to a
+process address space, page cache and buffer pages, swap cache pages. For other
+page types (e.g. SLAB pages) an attempt to mark a page idle is silently ignored,
+and hence such pages are never reported idle.
+
+For huge pages the idle flag is set only on the head page, so one has to read
+``/proc/kpageflags`` in order to correctly count idle huge pages.
+
+Reading from or writing to ``/sys/kernel/mm/page_idle/bitmap`` will return
+-EINVAL if you are not starting the read/write on an 8-byte boundary, or
+if the size of the read/write is not a multiple of 8 bytes. Writing to
+this file beyond max PFN will return -ENXIO.
+
+That said, in order to estimate the amount of pages that are not used by a
+workload one should:
+
+ 1. Mark all the workload's pages as idle by setting corresponding bits in
+    ``/sys/kernel/mm/page_idle/bitmap``. The pages can be found by reading
+    ``/proc/pid/pagemap`` if the workload is represented by a process, or by
+    filtering out alien pages using ``/proc/kpagecgroup`` in case the workload
+    is placed in a memory cgroup.
+
+ 2. Wait until the workload accesses its working set.
+
+ 3. Read ``/sys/kernel/mm/page_idle/bitmap`` and count the number of bits set.
+    If one wants to ignore certain types of pages, e.g. mlocked pages since they
+    are not reclaimable, he or she can filter them out using
+    ``/proc/kpageflags``.
+
+The page-types tool in the tools/mm directory can be used to assist in this.
+If the tool is run initially with the appropriate option, it will mark all the
+queried pages as idle.  Subsequent runs of the tool can then show which pages have
+their idle flag cleared in the interim.
+
+See Documentation/admin-guide/mm/pagemap.rst for more information about
+``/proc/pid/pagemap``, ``/proc/kpageflags``, and ``/proc/kpagecgroup``.
+
+.. _impl_details:
+
+Implementation Details
+======================
+
+The kernel internally keeps track of accesses to user memory pages in order to
+reclaim unreferenced pages first on memory shortage conditions. A page is
+considered referenced if it has been recently accessed via a process address
+space, in which case one or more PTEs it is mapped to will have the Accessed bit
+set, or marked accessed explicitly by the kernel (see mark_page_accessed()). The
+latter happens when:
+
+ - a userspace process reads or writes a page using a system call (e.g. read(2)
+   or write(2))
+
+ - a page that is used for storing filesystem buffers is read or written,
+   because a process needs filesystem metadata stored in it (e.g. lists a
+   directory tree)
+
+ - a page is accessed by a device driver using get_user_pages()
+
+When a dirty page is written to swap or disk as a result of memory reclaim or
+exceeding the dirty memory limit, it is not marked referenced.
+
+The idle memory tracking feature adds a new page flag, the Idle flag. This flag
+is set manually, by writing to ``/sys/kernel/mm/page_idle/bitmap`` (see the
+:ref:`User API <user_api>`
+section), and cleared automatically whenever a page is referenced as defined
+above.
+
+When a page is marked idle, the Accessed bit must be cleared in all PTEs it is
+mapped to, otherwise we will not be able to detect accesses to the page coming
+from a process address space. To avoid interference with the reclaimer, which,
+as noted above, uses the Accessed bit to promote actively referenced pages, one
+more page flag is introduced, the Young flag. When the PTE Accessed bit is
+cleared as a result of setting or updating a page's Idle flag, the Young flag
+is set on the page. The reclaimer treats the Young flag as an extra PTE
+Accessed bit and therefore will consider such a page as referenced.
+
+Since the idle memory tracking feature is based on the memory reclaimer logic,
+it only works with pages that are on an LRU list, other pages are silently
+ignored. That means it will ignore a user memory page if it is isolated, but
+since there are usually not many of them, it should not affect the overall
+result noticeably. In order not to stall scanning of the idle page bitmap,
+locked pages may be skipped too.
diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst
new file mode 100644
index 000000000..bbb563cba
--- /dev/null
+++ b/Documentation/admin-guide/mm/index.rst
@@ -0,0 +1,45 @@
+=================
+Memory Management
+=================
+
+Linux memory management subsystem is responsible, as the name implies,
+for managing the memory in the system. This includes implementation of
+virtual memory and demand paging, memory allocation both for kernel
+internal structures and user space programs, mapping of files into
+processes address space and many other cool things.
+
+Linux memory management is a complex system with many configurable
+settings. Most of these settings are available via ``/proc``
+filesystem and can be queried and adjusted using ``sysctl``. These APIs
+are described in Documentation/admin-guide/sysctl/vm.rst and in `man 5 proc`_.
+
+.. _man 5 proc: http://man7.org/linux/man-pages/man5/proc.5.html
+
+Linux memory management has its own jargon and if you are not yet
+familiar with it, consider reading Documentation/admin-guide/mm/concepts.rst.
+
+Here we document in detail how to interact with various mechanisms in
+the Linux memory management.
+
+.. toctree::
+   :maxdepth: 1
+
+   concepts
+   cma_debugfs
+   damon/index
+   hugetlbpage
+   idle_page_tracking
+   ksm
+   memory-hotplug
+   multigen_lru
+   nommu-mmap
+   numa_memory_policy
+   numaperf
+   pagemap
+   shrinker_debugfs
+   slab
+   soft-dirty
+   transhuge
+   userfaultfd
+   zswap
+   kho
diff --git a/Documentation/admin-guide/mm/kho.rst b/Documentation/admin-guide/mm/kho.rst
new file mode 100644
index 000000000..2c26e560b
--- /dev/null
+++ b/Documentation/admin-guide/mm/kho.rst
@@ -0,0 +1,123 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+====================
+Kexec Handover Usage
+====================
+
+Kexec HandOver (KHO) is a mechanism that allows Linux to preserve memory
+regions, which could contain serialized system states, across kexec.
+
+This document expects that you are familiar with the base KHO
+:ref:`concepts <kho-concepts>`. If you have not read
+them yet, please do so now.
+
+Prerequisites
+=============
+
+KHO is available when the kernel is compiled with ``CONFIG_KEXEC_HANDOVER``
+set to y. Every KHO producer may have its own config option that you
+need to enable if you would like to preserve their respective state across
+kexec.
+
+To use KHO, please boot the kernel with the ``kho=on`` command line
+parameter. You may use ``kho_scratch`` parameter to define size of the
+scratch regions. For example ``kho_scratch=16M,512M,256M`` will reserve a
+16 MiB low memory scratch area, a 512 MiB global scratch region, and 256 MiB
+per NUMA node scratch regions on boot.
+
+Perform a KHO kexec
+===================
+
+To perform a KHO kexec, load the target payload and kexec into it. It
+is important that you use the ``-s`` parameter to use the in-kernel
+kexec file loader, as user space kexec tooling currently has no
+support for KHO with the user space based file loader ::
+
+  # kexec -l /path/to/bzImage --initrd /path/to/initrd -s
+  # kexec -e
+
+The new kernel will boot up and contain some of the previous kernel's state.
+
+For example, if you used ``reserve_mem`` command line parameter to create
+an early memory reservation, the new kernel will have that memory at the
+same physical address as the old kernel.
+
+Kexec Metadata
+==============
+
+KHO automatically tracks metadata about the kexec chain, passing information
+about the previous kernel to the next kernel. This feature helps diagnose
+bugs that only reproduce when kexecing from specific kernel versions.
+
+On each KHO kexec, the kernel logs the previous kernel's version and the
+number of kexec reboots since the last cold boot::
+
+    [    0.000000] KHO: exec from: 6.19.0-rc4-next-20260107 (count 1)
+
+The metadata includes:
+
+``previous_release``
+    The kernel version string (from ``uname -r``) of the kernel that
+    initiated the kexec.
+
+``kexec_count``
+    The number of kexec boots since the last cold boot. On cold boot,
+    this counter starts at 0 and increments with each kexec. This helps
+    identify issues that only manifest after multiple consecutive kexec
+    reboots.
+
+Use Cases
+---------
+
+This metadata is particularly useful for debugging kexec transition bugs,
+where a buggy kernel kexecs into a new kernel and the bug manifests only
+in the second kernel. Examples of such bugs include:
+
+- Memory corruption from the previous kernel affecting the new kernel
+- Incorrect hardware state left by the previous kernel
+- Firmware/ACPI state issues that only appear in kexec scenarios
+
+At scale, correlating crashes to the previous kernel version enables
+faster root cause analysis when issues only occur in specific kernel
+transition scenarios.
+
+debugfs Interfaces
+==================
+
+These debugfs interfaces are available when the kernel is compiled with
+``CONFIG_KEXEC_HANDOVER_DEBUGFS`` enabled.
+
+Currently KHO creates the following debugfs interfaces. Notice that these
+interfaces may change in the future. They will be moved to sysfs once KHO is
+stabilized.
+
+``/sys/kernel/debug/kho/out/fdt``
+    The kernel exposes the flattened device tree blob that carries its
+    current KHO state in this file. Kexec user space tooling can use this
+    as input file for the KHO payload image.
+
+``/sys/kernel/debug/kho/out/scratch_len``
+    Lengths of KHO scratch regions, which are physically contiguous
+    memory regions that will always stay available for future kexec
+    allocations. Kexec user space tools can use this file to determine
+    where it should place its payload images.
+
+``/sys/kernel/debug/kho/out/scratch_phys``
+    Physical locations of KHO scratch regions. Kexec user space tools
+    can use this file in conjunction to scratch_phys to determine where
+    it should place its payload images.
+
+``/sys/kernel/debug/kho/out/sub_fdts/``
+    KHO producers can register their own FDT or another binary blob under
+    this directory.
+
+``/sys/kernel/debug/kho/in/fdt``
+    When the kernel was booted with Kexec HandOver (KHO),
+    the state tree that carries metadata about the previous
+    kernel's state is in this file in the format of flattened
+    device tree. This file may disappear when all consumers of
+    it finished to interpret their metadata.
+
+``/sys/kernel/debug/kho/in/sub_fdts/``
+    Similar to ``kho/out/sub_fdts/``, but contains sub blobs
+    of KHO producers passed from the old kernel.
diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-guide/mm/ksm.rst
new file mode 100644
index 000000000..ad8e7a41f
--- /dev/null
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -0,0 +1,323 @@
+=======================
+Kernel Samepage Merging
+=======================
+
+Overview
+========
+
+KSM is a memory-saving de-duplication feature, enabled by CONFIG_KSM=y,
+added to the Linux kernel in 2.6.32.  See ``mm/ksm.c`` for its implementation,
+and http://lwn.net/Articles/306704/ and https://lwn.net/Articles/330589/
+
+KSM was originally developed for use with KVM (where it was known as
+Kernel Shared Memory), to fit more virtual machines into physical memory,
+by sharing the data common between them.  But it can be useful to any
+application which generates many instances of the same data.
+
+The KSM daemon ksmd periodically scans those areas of user memory
+which have been registered with it, looking for pages of identical
+content which can be replaced by a single write-protected page (which
+is automatically copied if a process later wants to update its
+content). The amount of pages that KSM daemon scans in a single pass
+and the time between the passes are configured using :ref:`sysfs
+interface <ksm_sysfs>`
+
+KSM only merges anonymous (private) pages, never pagecache (file) pages.
+KSM's merged pages were originally locked into kernel memory, but can now
+be swapped out just like other user pages (but sharing is broken when they
+are swapped back in: ksmd must rediscover their identity and merge again).
+
+Controlling KSM with madvise
+============================
+
+KSM only operates on those areas of address space which an application
+has advised to be likely candidates for merging, by using the madvise(2)
+system call::
+
+	int madvise(addr, length, MADV_MERGEABLE)
+
+The app may call
+
+::
+
+	int madvise(addr, length, MADV_UNMERGEABLE)
+
+to cancel that advice and restore unshared pages: whereupon KSM
+unmerges whatever it merged in that range.  Note: this unmerging call
+may suddenly require more memory than is available - possibly failing
+with EAGAIN, but more probably arousing the Out-Of-Memory killer.
+
+If KSM is not configured into the running kernel, madvise MADV_MERGEABLE
+and MADV_UNMERGEABLE simply fail with EINVAL.  If the running kernel was
+built with CONFIG_KSM=y, those calls will normally succeed: even if the
+KSM daemon is not currently running, MADV_MERGEABLE still registers
+the range for whenever the KSM daemon is started; even if the range
+cannot contain any pages which KSM could actually merge; even if
+MADV_UNMERGEABLE is applied to a range which was never MADV_MERGEABLE.
+
+If a region of memory must be split into at least one new MADV_MERGEABLE
+or MADV_UNMERGEABLE region, the madvise may return ENOMEM if the process
+will exceed ``vm.max_map_count`` (see Documentation/admin-guide/sysctl/vm.rst).
+
+Like other madvise calls, they are intended for use on mapped areas of
+the user address space: they will report ENOMEM if the specified range
+includes unmapped gaps (though working on the intervening mapped areas),
+and might fail with EAGAIN if not enough memory for internal structures.
+
+Applications should be considerate in their use of MADV_MERGEABLE,
+restricting its use to areas likely to benefit.  KSM's scans may use a lot
+of processing power: some installations will disable KSM for that reason.
+
+.. _ksm_sysfs:
+
+KSM daemon sysfs interface
+==========================
+
+The KSM daemon is controlled by sysfs files in ``/sys/kernel/mm/ksm/``,
+readable by all but writable only by root:
+
+pages_to_scan
+        how many pages to scan before ksmd goes to sleep
+        e.g. ``echo 100 > /sys/kernel/mm/ksm/pages_to_scan``.
+
+        The pages_to_scan value cannot be changed if ``advisor_mode`` has
+        been set to scan-time.
+
+        Default: 100 (chosen for demonstration purposes)
+
+sleep_millisecs
+        how many milliseconds ksmd should sleep before next scan
+        e.g. ``echo 20 > /sys/kernel/mm/ksm/sleep_millisecs``
+
+        Default: 20 (chosen for demonstration purposes)
+
+merge_across_nodes
+        specifies if pages from different NUMA nodes can be merged.
+        When set to 0, ksm merges only pages which physically reside
+        in the memory area of same NUMA node. That brings lower
+        latency to access of shared pages. Systems with more nodes, at
+        significant NUMA distances, are likely to benefit from the
+        lower latency of setting 0. Smaller systems, which need to
+        minimize memory usage, are likely to benefit from the greater
+        sharing of setting 1 (default). You may wish to compare how
+        your system performs under each setting, before deciding on
+        which to use. ``merge_across_nodes`` setting can be changed only
+        when there are no ksm shared pages in the system: set run 2 to
+        unmerge pages first, then to 1 after changing
+        ``merge_across_nodes``, to remerge according to the new setting.
+
+        Default: 1 (merging across nodes as in earlier releases)
+
+run
+        * set to 0 to stop ksmd from running but keep merged pages,
+        * set to 1 to run ksmd e.g. ``echo 1 > /sys/kernel/mm/ksm/run``,
+        * set to 2 to stop ksmd and unmerge all pages currently merged, but
+	  leave mergeable areas registered for next run.
+
+        Default: 0 (must be changed to 1 to activate KSM, except if
+        CONFIG_SYSFS is disabled)
+
+use_zero_pages
+        specifies whether empty pages (i.e. allocated pages that only
+        contain zeroes) should be treated specially.  When set to 1,
+        empty pages are merged with the kernel zero page(s) instead of
+        with each other as it would happen normally. This can improve
+        the performance on architectures with coloured zero pages,
+        depending on the workload. Care should be taken when enabling
+        this setting, as it can potentially degrade the performance of
+        KSM for some workloads, for example if the checksums of pages
+        candidate for merging match the checksum of an empty
+        page. This setting can be changed at any time, it is only
+        effective for pages merged after the change.
+
+        Default: 0 (normal KSM behaviour as in earlier releases)
+
+max_page_sharing
+        Maximum sharing allowed for each KSM page. This enforces a
+        deduplication limit to avoid high latency for virtual memory
+        operations that involve traversal of the virtual mappings that
+        share the KSM page. The minimum value is 2 as a newly created
+        KSM page will have at least two sharers. The higher this value
+        the faster KSM will merge the memory and the higher the
+        deduplication factor will be, but the slower the worst case
+        virtual mappings traversal could be for any given KSM
+        page. Slowing down this traversal means there will be higher
+        latency for certain virtual memory operations happening during
+        swapping, compaction, NUMA balancing and page migration, in
+        turn decreasing responsiveness for the caller of those virtual
+        memory operations. The scheduler latency of other tasks not
+        involved with the VM operations doing the virtual mappings
+        traversal is not affected by this parameter as these
+        traversals are always schedule friendly themselves.
+
+stable_node_chains_prune_millisecs
+        specifies how frequently KSM checks the metadata of the pages
+        that hit the deduplication limit for stale information.
+        Smaller milllisecs values will free up the KSM metadata with
+        lower latency, but they will make ksmd use more CPU during the
+        scan. It's a noop if not a single KSM page hit the
+        ``max_page_sharing`` yet.
+
+smart_scan
+        Historically KSM checked every candidate page for each scan. It did
+        not take into account historic information.  When smart scan is
+        enabled, pages that have previously not been de-duplicated get
+        skipped. How often these pages are skipped depends on how often
+        de-duplication has already been tried and failed. By default this
+        optimization is enabled.  The ``pages_skipped`` metric shows how
+        effective the setting is.
+
+advisor_mode
+        The ``advisor_mode`` selects the current advisor. Two modes are
+        supported: none and scan-time. The default is none. By setting
+        ``advisor_mode`` to scan-time, the scan time advisor is enabled.
+        The section about ``advisor`` explains in detail how the scan time
+        advisor works.
+
+adivsor_max_cpu
+        specifies the upper limit of the cpu percent usage of the ksmd
+        background thread. The default is 70.
+
+advisor_target_scan_time
+        specifies the target scan time in seconds to scan all the candidate
+        pages. The default value is 200 seconds.
+
+advisor_min_pages_to_scan
+        specifies the lower limit of the ``pages_to_scan`` parameter of the
+        scan time advisor. The default is 500.
+
+adivsor_max_pages_to_scan
+        specifies the upper limit of the ``pages_to_scan`` parameter of the
+        scan time advisor. The default is 30000.
+
+The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``:
+
+general_profit
+        how effective is KSM. The calculation is explained below.
+pages_scanned
+        how many pages are being scanned for ksm
+pages_shared
+        how many shared pages are being used
+pages_sharing
+        how many more sites are sharing them i.e. how much saved
+pages_unshared
+        how many pages unique but repeatedly checked for merging
+pages_volatile
+        how many pages changing too fast to be placed in a tree
+pages_skipped
+        how many pages did the "smart" page scanning algorithm skip
+full_scans
+        how many times all mergeable areas have been scanned
+stable_node_chains
+        the number of KSM pages that hit the ``max_page_sharing`` limit
+stable_node_dups
+        number of duplicated KSM pages
+ksm_zero_pages
+        how many zero pages that are still mapped into processes were mapped by
+        KSM when deduplicating.
+
+When ``use_zero_pages`` is/was enabled, the sum of ``pages_sharing`` +
+``ksm_zero_pages`` represents the actual number of pages saved by KSM.
+if ``use_zero_pages`` has never been enabled, ``ksm_zero_pages`` is 0.
+
+A high ratio of ``pages_sharing`` to ``pages_shared`` indicates good
+sharing, but a high ratio of ``pages_unshared`` to ``pages_sharing``
+indicates wasted effort.  ``pages_volatile`` embraces several
+different kinds of activity, but a high proportion there would also
+indicate poor use of madvise MADV_MERGEABLE.
+
+The maximum possible ``pages_sharing/pages_shared`` ratio is limited by the
+``max_page_sharing`` tunable. To increase the ratio ``max_page_sharing`` must
+be increased accordingly.
+
+Monitoring KSM profit
+=====================
+
+KSM can save memory by merging identical pages, but also can consume
+additional memory, because it needs to generate a number of rmap_items to
+save each scanned page's brief rmap information. Some of these pages may
+be merged, but some may not be abled to be merged after being checked
+several times, which are unprofitable memory consumed.
+
+1) How to determine whether KSM save memory or consume memory in system-wide
+   range? Here is a simple approximate calculation for reference::
+
+	general_profit =~ ksm_saved_pages * sizeof(page) - (all_rmap_items) *
+			  sizeof(rmap_item);
+
+   where ksm_saved_pages equals to the sum of ``pages_sharing`` +
+   ``ksm_zero_pages`` of the system, and all_rmap_items can be easily
+   obtained by summing ``pages_sharing``, ``pages_shared``, ``pages_unshared``
+   and ``pages_volatile``.
+
+2) The KSM profit inner a single process can be similarly obtained by the
+   following approximate calculation::
+
+	process_profit =~ ksm_saved_pages * sizeof(page) -
+			  ksm_rmap_items * sizeof(rmap_item).
+
+   where ksm_saved_pages equals to the sum of ``ksm_merging_pages`` and
+   ``ksm_zero_pages``, both of which are shown under the directory
+   ``/proc/<pid>/ksm_stat``, and ksm_rmap_items is also shown in
+   ``/proc/<pid>/ksm_stat``. The process profit is also shown in
+   ``/proc/<pid>/ksm_stat`` as ksm_process_profit.
+
+From the perspective of application, a high ratio of ``ksm_rmap_items`` to
+``ksm_merging_pages`` means a bad madvise-applied policy, so developers or
+administrators have to rethink how to change madvise policy. Giving an example
+for reference, a page's size is usually 4K, and the rmap_item's size is
+separately 32B on 32-bit CPU architecture and 64B on 64-bit CPU architecture.
+so if the ``ksm_rmap_items/ksm_merging_pages`` ratio exceeds 64 on 64-bit CPU
+or exceeds 128 on 32-bit CPU, then the app's madvise policy should be dropped,
+because the ksm profit is approximately zero or negative.
+
+Monitoring KSM events
+=====================
+
+There are some counters in /proc/vmstat that may be used to monitor KSM events.
+KSM might help save memory, it's a tradeoff by may suffering delay on KSM COW
+or on swapping in copy. Those events could help users evaluate whether or how
+to use KSM. For example, if cow_ksm increases too fast, user may decrease the
+range of madvise(, , MADV_MERGEABLE).
+
+cow_ksm
+	is incremented every time a KSM page triggers copy on write (COW)
+	when users try to write to a KSM page, we have to make a copy.
+
+ksm_swpin_copy
+	is incremented every time a KSM page is copied when swapping in
+	note that KSM page might be copied when swapping in because do_swap_page()
+	cannot do all the locking needed to reconstitute a cross-anon_vma KSM page.
+
+Advisor
+=======
+
+The number of candidate pages for KSM is dynamic. It can be often observed
+that during the startup of an application more candidate pages need to be
+processed. Without an advisor the ``pages_to_scan`` parameter needs to be
+sized for the maximum number of candidate pages. The scan time advisor can
+changes the ``pages_to_scan`` parameter based on demand.
+
+The advisor can be enabled, so KSM can automatically adapt to changes in the
+number of candidate pages to scan. Two advisors are implemented: none and
+scan-time. With none, no advisor is enabled. The default is none.
+
+The scan time advisor changes the ``pages_to_scan`` parameter based on the
+observed scan times. The possible values for the ``pages_to_scan`` parameter is
+limited by the ``advisor_max_cpu`` parameter. In addition there is also the
+``advisor_target_scan_time`` parameter. This parameter sets the target time to
+scan all the KSM candidate pages. The parameter ``advisor_target_scan_time``
+decides how aggressive the scan time advisor scans candidate pages. Lower
+values make the scan time advisor to scan more aggressively. This is the most
+important parameter for the configuration of the scan time advisor.
+
+The initial value and the maximum value can be changed with
+``advisor_min_pages_to_scan`` and ``advisor_max_pages_to_scan``. The default
+values are sufficient for most workloads and use cases.
+
+The ``pages_to_scan`` parameter is re-calculated after a scan has been completed.
+
+
+--
+Izik Eidus,
+Hugh Dickins, 17 Nov 2009
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
new file mode 100644
index 000000000..0207f8725
--- /dev/null
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -0,0 +1,706 @@
+==================
+Memory Hot(Un)Plug
+==================
+
+This document describes generic Linux support for memory hot(un)plug with
+a focus on System RAM, including ZONE_MOVABLE support.
+
+.. contents:: :local:
+
+Introduction
+============
+
+Memory hot(un)plug allows for increasing and decreasing the size of physical
+memory available to a machine at runtime. In the simplest case, it consists of
+physically plugging or unplugging a DIMM at runtime, coordinated with the
+operating system.
+
+Memory hot(un)plug is used for various purposes:
+
+- The physical memory available to a machine can be adjusted at runtime, up- or
+  downgrading the memory capacity. This dynamic memory resizing, sometimes
+  referred to as "capacity on demand", is frequently used with virtual machines
+  and logical partitions.
+
+- Replacing hardware, such as DIMMs or whole NUMA nodes, without downtime. One
+  example is replacing failing memory modules.
+
+- Reducing energy consumption either by physically unplugging memory modules or
+  by logically unplugging (parts of) memory modules from Linux.
+
+Further, the basic memory hot(un)plug infrastructure in Linux is nowadays also
+used to expose persistent memory, other performance-differentiated memory and
+reserved memory regions as ordinary system RAM to Linux.
+
+Linux only supports memory hot(un)plug on selected 64 bit architectures, such as
+x86_64, arm64, ppc64 and s390x.
+
+Memory Hot(Un)Plug Granularity
+------------------------------
+
+Memory hot(un)plug in Linux uses the SPARSEMEM memory model, which divides the
+physical memory address space into chunks of the same size: memory sections. The
+size of a memory section is architecture dependent. For example, x86_64 uses
+128 MiB and ppc64 uses 16 MiB.
+
+Memory sections are combined into chunks referred to as "memory blocks". The
+size of a memory block is architecture dependent and corresponds to the smallest
+granularity that can be hot(un)plugged. The default size of a memory block is
+the same as memory section size, unless an architecture specifies otherwise.
+
+All memory blocks have the same size.
+
+Phases of Memory Hotplug
+------------------------
+
+Memory hotplug consists of two phases:
+
+(1) Adding the memory to Linux
+(2) Onlining memory blocks
+
+In the first phase, metadata, such as the memory map ("memmap") and page tables
+for the direct mapping, is allocated and initialized, and memory blocks are
+created; the latter also creates sysfs files for managing newly created memory
+blocks.
+
+In the second phase, added memory is exposed to the page allocator. After this
+phase, the memory is visible in memory statistics, such as free and total
+memory, of the system.
+
+Phases of Memory Hotunplug
+--------------------------
+
+Memory hotunplug consists of two phases:
+
+(1) Offlining memory blocks
+(2) Removing the memory from Linux
+
+In the first phase, memory is "hidden" from the page allocator again, for
+example, by migrating busy memory to other memory locations and removing all
+relevant free pages from the page allocator After this phase, the memory is no
+longer visible in memory statistics of the system.
+
+In the second phase, the memory blocks are removed and metadata is freed.
+
+Memory Hotplug Notifications
+============================
+
+There are various ways how Linux is notified about memory hotplug events such
+that it can start adding hotplugged memory. This description is limited to
+systems that support ACPI; mechanisms specific to other firmware interfaces or
+virtual machines are not described.
+
+ACPI Notifications
+------------------
+
+Platforms that support ACPI, such as x86_64, can support memory hotplug
+notifications via ACPI.
+
+In general, a firmware supporting memory hotplug defines a memory class object
+HID "PNP0C80". When notified about hotplug of a new memory device, the ACPI
+driver will hotplug the memory to Linux.
+
+If the firmware supports hotplug of NUMA nodes, it defines an object _HID
+"ACPI0004", "PNP0A05", or "PNP0A06". When notified about an hotplug event, all
+assigned memory devices are added to Linux by the ACPI driver.
+
+Similarly, Linux can be notified about requests to hotunplug a memory device or
+a NUMA node via ACPI. The ACPI driver will try offlining all relevant memory
+blocks, and, if successful, hotunplug the memory from Linux.
+
+Manual Probing
+--------------
+
+On some architectures, the firmware may not be able to notify the operating
+system about a memory hotplug event. Instead, the memory has to be manually
+probed from user space.
+
+The probe interface is located at::
+
+	/sys/devices/system/memory/probe
+
+Only complete memory blocks can be probed. Individual memory blocks are probed
+by providing the physical start address of the memory block::
+
+	% echo addr > /sys/devices/system/memory/probe
+
+Which results in a memory block for the range [addr, addr + memory_block_size)
+being created.
+
+.. note::
+
+  Using the probe interface is discouraged as it is easy to crash the kernel,
+  because Linux cannot validate user input; this interface might be removed in
+  the future.
+
+Onlining and Offlining Memory Blocks
+====================================
+
+After a memory block has been created, Linux has to be instructed to actually
+make use of that memory: the memory block has to be "online".
+
+Before a memory block can be removed, Linux has to stop using any memory part of
+the memory block: the memory block has to be "offlined".
+
+The Linux kernel can be configured to automatically online added memory blocks
+and drivers automatically trigger offlining of memory blocks when trying
+hotunplug of memory. Memory blocks can only be removed once offlining succeeded
+and drivers may trigger offlining of memory blocks when attempting hotunplug of
+memory.
+
+Onlining Memory Blocks Manually
+-------------------------------
+
+If auto-onlining of memory blocks isn't enabled, user-space has to manually
+trigger onlining of memory blocks. Often, udev rules are used to automate this
+task in user space.
+
+Onlining of a memory block can be triggered via::
+
+	% echo online > /sys/devices/system/memory/memoryXXX/state
+
+Or alternatively::
+
+	% echo 1 > /sys/devices/system/memory/memoryXXX/online
+
+The kernel will select the target zone automatically, depending on the
+configured ``online_policy``.
+
+One can explicitly request to associate an offline memory block with
+ZONE_MOVABLE by::
+
+	% echo online_movable > /sys/devices/system/memory/memoryXXX/state
+
+Or one can explicitly request a kernel zone (usually ZONE_NORMAL) by::
+
+	% echo online_kernel > /sys/devices/system/memory/memoryXXX/state
+
+In any case, if onlining succeeds, the state of the memory block is changed to
+be "online". If it fails, the state of the memory block will remain unchanged
+and the above commands will fail.
+
+Onlining Memory Blocks Automatically
+------------------------------------
+
+The kernel can be configured to try auto-onlining of newly added memory blocks.
+If this feature is disabled, the memory blocks will stay offline until
+explicitly onlined from user space.
+
+The configured auto-online behavior can be observed via::
+
+	% cat /sys/devices/system/memory/auto_online_blocks
+
+Auto-onlining can be enabled by writing ``online``, ``online_kernel`` or
+``online_movable`` to that file, like::
+
+	% echo online > /sys/devices/system/memory/auto_online_blocks
+
+Similarly to manual onlining, with ``online`` the kernel will select the
+target zone automatically, depending on the configured ``online_policy``.
+
+Modifying the auto-online behavior will only affect all subsequently added
+memory blocks only.
+
+.. note::
+
+  In corner cases, auto-onlining can fail. The kernel won't retry. Note that
+  auto-onlining is not expected to fail in default configurations.
+
+.. note::
+
+  DLPAR on ppc64 ignores the ``offline`` setting and will still online added
+  memory blocks; if onlining fails, memory blocks are removed again.
+
+Offlining Memory Blocks
+-----------------------
+
+In the current implementation, Linux's memory offlining will try migrating all
+movable pages off the affected memory block. As most kernel allocations, such as
+page tables, are unmovable, page migration can fail and, therefore, inhibit
+memory offlining from succeeding.
+
+Having the memory provided by memory block managed by ZONE_MOVABLE significantly
+increases memory offlining reliability; still, memory offlining can fail in
+some corner cases.
+
+Further, memory offlining might retry for a long time (or even forever), until
+aborted by the user.
+
+Offlining of a memory block can be triggered via::
+
+	% echo offline > /sys/devices/system/memory/memoryXXX/state
+
+Or alternatively::
+
+	% echo 0 > /sys/devices/system/memory/memoryXXX/online
+
+If offlining succeeds, the state of the memory block is changed to be "offline".
+If it fails, the state of the memory block will remain unchanged and the above
+commands will fail, for example, via::
+
+	bash: echo: write error: Device or resource busy
+
+or via::
+
+	bash: echo: write error: Invalid argument
+
+Observing the State of Memory Blocks
+------------------------------------
+
+The state (online/offline/going-offline) of a memory block can be observed
+either via::
+
+	% cat /sys/devices/system/memory/memoryXXX/state
+
+Or alternatively (1/0) via::
+
+	% cat /sys/devices/system/memory/memoryXXX/online
+
+For an online memory block, the managing zone can be observed via::
+
+	% cat /sys/devices/system/memory/memoryXXX/valid_zones
+
+Configuring Memory Hot(Un)Plug
+==============================
+
+There are various ways how system administrators can configure memory
+hot(un)plug and interact with memory blocks, especially, to online them.
+
+Memory Hot(Un)Plug Configuration via Sysfs
+------------------------------------------
+
+Some memory hot(un)plug properties can be configured or inspected via sysfs in::
+
+	/sys/devices/system/memory/
+
+The following files are currently defined:
+
+====================== =========================================================
+``auto_online_blocks`` read-write: set or get the default state of new memory
+		       blocks; configure auto-onlining.
+
+		       The default value depends on the
+		       CONFIG_MHP_DEFAULT_ONLINE_TYPE kernel configuration
+		       options.
+
+		       See the ``state`` property of memory blocks for details.
+``block_size_bytes``   read-only: the size in bytes of a memory block.
+``probe``	       write-only: add (probe) selected memory blocks manually
+		       from user space by supplying the physical start address.
+
+		       Availability depends on the CONFIG_ARCH_MEMORY_PROBE
+		       kernel configuration option.
+``uevent``	       read-write: generic udev file for device subsystems.
+``crash_hotplug``      read-only: when changes to the system memory map
+		       occur due to hot un/plug of memory, this file contains
+		       '1' if the kernel updates the kdump capture kernel memory
+		       map itself (via elfcorehdr and other relevant kexec
+		       segments), or '0' if userspace must update the kdump
+		       capture kernel memory map.
+
+		       Availability depends on the CONFIG_MEMORY_HOTPLUG kernel
+		       configuration option.
+====================== =========================================================
+
+.. note::
+
+  When the CONFIG_MEMORY_FAILURE kernel configuration option is enabled, two
+  additional files ``hard_offline_page`` and ``soft_offline_page`` are available
+  to trigger hwpoisoning of pages, for example, for testing purposes. Note that
+  this functionality is not really related to memory hot(un)plug or actual
+  offlining of memory blocks.
+
+Memory Block Configuration via Sysfs
+------------------------------------
+
+Each memory block is represented as a memory block device that can be
+onlined or offlined. All memory blocks have their device information located in
+sysfs. Each present memory block is listed under
+``/sys/devices/system/memory`` as::
+
+	/sys/devices/system/memory/memoryXXX
+
+where XXX is the memory block id; the number of digits is variable.
+
+A present memory block indicates that some memory in the range is present;
+however, a memory block might span memory holes. A memory block spanning memory
+holes cannot be offlined.
+
+For example, assume 1 GiB memory block size. A device for a memory starting at
+0x100000000 is ``/sys/devices/system/memory/memory4``::
+
+	(0x100000000 / 1Gib = 4)
+
+This device covers address range [0x100000000 ... 0x140000000)
+
+The following files are currently defined:
+
+=================== ============================================================
+``online``	    read-write: simplified interface to trigger onlining /
+		    offlining and to observe the state of a memory block.
+		    When onlining, the zone is selected automatically.
+``phys_device``	    read-only: legacy interface only ever used on s390x to
+		    expose the covered storage increment.
+``phys_index``	    read-only: the memory block id (XXX).
+``removable``	    read-only: legacy interface that indicated whether a memory
+		    block was likely to be offlineable or not. Nowadays, the
+		    kernel return ``1`` if and only if it supports memory
+		    offlining.
+``state``	    read-write: advanced interface to trigger onlining /
+		    offlining and to observe the state of a memory block.
+
+		    When writing, ``online``, ``offline``, ``online_kernel`` and
+		    ``online_movable`` are supported.
+
+		    ``online_movable`` specifies onlining to ZONE_MOVABLE.
+		    ``online_kernel`` specifies onlining to the default kernel
+		    zone for the memory block, such as ZONE_NORMAL.
+                    ``online`` let's the kernel select the zone automatically.
+
+		    When reading, ``online``, ``offline`` and ``going-offline``
+		    may be returned.
+``uevent``	    read-write: generic uevent file for devices.
+``valid_zones``     read-only: when a block is online, shows the zone it
+		    belongs to; when a block is offline, shows what zone will
+		    manage it when the block will be onlined.
+
+		    For online memory blocks, ``DMA``, ``DMA32``, ``Normal``,
+		    ``Movable`` and ``none`` may be returned. ``none`` indicates
+		    that memory provided by a memory block is managed by
+		    multiple zones or spans multiple nodes; such memory blocks
+		    cannot be offlined. ``Movable`` indicates ZONE_MOVABLE.
+		    Other values indicate a kernel zone.
+
+		    For offline memory blocks, the first column shows the
+		    zone the kernel would select when onlining the memory block
+		    right now without further specifying a zone.
+
+		    Availability depends on the CONFIG_MEMORY_HOTREMOVE
+		    kernel configuration option.
+=================== ============================================================
+
+.. note::
+
+  If the CONFIG_NUMA kernel configuration option is enabled, the memoryXXX/
+  directories can also be accessed via symbolic links located in the
+  ``/sys/devices/system/node/node*`` directories.
+
+  For example::
+
+	/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
+
+  A backlink will also be created::
+
+	/sys/devices/system/memory/memory9/node0 -> ../../node/node0
+
+Command Line Parameters
+-----------------------
+
+Some command line parameters affect memory hot(un)plug handling. The following
+command line parameters are relevant:
+
+======================== =======================================================
+``memhp_default_state``	 configure auto-onlining by essentially setting
+                         ``/sys/devices/system/memory/auto_online_blocks``.
+``movable_node``	 configure automatic zone selection in the kernel when
+			 using the ``contig-zones`` online policy. When
+			 set, the kernel will default to ZONE_MOVABLE when
+			 onlining a memory block, unless other zones can be kept
+			 contiguous.
+======================== =======================================================
+
+See Documentation/admin-guide/kernel-parameters.txt for a more generic
+description of these command line parameters.
+
+Module Parameters
+------------------
+
+Instead of additional command line parameters or sysfs files, the
+``memory_hotplug`` subsystem now provides a dedicated namespace for module
+parameters. Module parameters can be set via the command line by predicating
+them with ``memory_hotplug.`` such as::
+
+	memory_hotplug.memmap_on_memory=1
+
+and they can be observed (and some even modified at runtime) via::
+
+	/sys/module/memory_hotplug/parameters/
+
+The following module parameters are currently defined:
+
+================================ ===============================================
+``memmap_on_memory``		 read-write: Allocate memory for the memmap from
+				 the added memory block itself. Even if enabled,
+				 actual support depends on various other system
+				 properties and should only be regarded as a
+				 hint whether the behavior would be desired.
+
+				 While allocating the memmap from the memory
+				 block itself makes memory hotplug less likely
+				 to fail and keeps the memmap on the same NUMA
+				 node in any case, it can fragment physical
+				 memory in a way that huge pages in bigger
+				 granularity cannot be formed on hotplugged
+				 memory.
+
+				 With value "force" it could result in memory
+				 wastage due to memmap size limitations. For
+				 example, if the memmap for a memory block
+				 requires 1 MiB, but the pageblock size is 2
+				 MiB, 1 MiB of hotplugged memory will be wasted.
+				 Note that there are still cases where the
+				 feature cannot be enforced: for example, if the
+				 memmap is smaller than a single page, or if the
+				 architecture does not support the forced mode
+				 in all configurations.
+
+``online_policy``		 read-write: Set the basic policy used for
+				 automatic zone selection when onlining memory
+				 blocks without specifying a target zone.
+				 ``contig-zones`` has been the kernel default
+				 before this parameter was added. After an
+				 online policy was configured and memory was
+				 online, the policy should not be changed
+				 anymore.
+
+				 When set to ``contig-zones``, the kernel will
+				 try keeping zones contiguous. If a memory block
+				 intersects multiple zones or no zone, the
+				 behavior depends on the ``movable_node`` kernel
+				 command line parameter: default to ZONE_MOVABLE
+				 if set, default to the applicable kernel zone
+				 (usually ZONE_NORMAL) if not set.
+
+				 When set to ``auto-movable``, the kernel will
+				 try onlining memory blocks to ZONE_MOVABLE if
+				 possible according to the configuration and
+				 memory device details. With this policy, one
+				 can avoid zone imbalances when eventually
+				 hotplugging a lot of memory later and still
+				 wanting to be able to hotunplug as much as
+				 possible reliably, very desirable in
+				 virtualized environments. This policy ignores
+				 the ``movable_node`` kernel command line
+				 parameter and isn't really applicable in
+				 environments that require it (e.g., bare metal
+				 with hotunpluggable nodes) where hotplugged
+				 memory might be exposed via the
+				 firmware-provided memory map early during boot
+				 to the system instead of getting detected,
+				 added and onlined  later during boot (such as
+				 done by virtio-mem or by some hypervisors
+				 implementing emulated DIMMs). As one example, a
+				 hotplugged DIMM will be onlined either
+				 completely to ZONE_MOVABLE or completely to
+				 ZONE_NORMAL, not a mixture.
+				 As another example, as many memory blocks
+				 belonging to a virtio-mem device will be
+				 onlined to ZONE_MOVABLE as possible,
+				 special-casing units of memory blocks that can
+				 only get hotunplugged together. *This policy
+				 does not protect from setups that are
+				 problematic with ZONE_MOVABLE and does not
+				 change the zone of memory blocks dynamically
+				 after they were onlined.*
+``auto_movable_ratio``		 read-write: Set the maximum MOVABLE:KERNEL
+				 memory ratio in % for the ``auto-movable``
+				 online policy. Whether the ratio applies only
+				 for the system across all NUMA nodes or also
+				 per NUMA nodes depends on the
+				 ``auto_movable_numa_aware`` configuration.
+
+				 All accounting is based on present memory pages
+				 in the zones combined with accounting per
+				 memory device. Memory dedicated to the CMA
+				 allocator is accounted as MOVABLE, although
+				 residing on one of the kernel zones. The
+				 possible ratio depends on the actual workload.
+				 The kernel default is "301" %, for example,
+				 allowing for hotplugging 24 GiB to a 8 GiB VM
+				 and automatically onlining all hotplugged
+				 memory to ZONE_MOVABLE in many setups. The
+				 additional 1% deals with some pages being not
+				 present, for example, because of some firmware
+				 allocations.
+
+				 Note that ZONE_NORMAL memory provided by one
+				 memory device does not allow for more
+				 ZONE_MOVABLE memory for a different memory
+				 device. As one example, onlining memory of a
+				 hotplugged DIMM to ZONE_NORMAL will not allow
+				 for another hotplugged DIMM to get onlined to
+				 ZONE_MOVABLE automatically. In contrast, memory
+				 hotplugged by a virtio-mem device that got
+				 onlined to ZONE_NORMAL will allow for more
+				 ZONE_MOVABLE memory within *the same*
+				 virtio-mem device.
+``auto_movable_numa_aware``	 read-write: Configure whether the
+				 ``auto_movable_ratio`` in the ``auto-movable``
+				 online policy also applies per NUMA
+				 node in addition to the whole system across all
+				 NUMA nodes. The kernel default is "Y".
+
+				 Disabling NUMA awareness can be helpful when
+				 dealing with NUMA nodes that should be
+				 completely hotunpluggable, onlining the memory
+				 completely to ZONE_MOVABLE automatically if
+				 possible.
+
+				 Parameter availability depends on CONFIG_NUMA.
+================================ ===============================================
+
+ZONE_MOVABLE
+============
+
+ZONE_MOVABLE is an important mechanism for more reliable memory offlining.
+Further, having system RAM managed by ZONE_MOVABLE instead of one of the
+kernel zones can increase the number of possible transparent huge pages and
+dynamically allocated huge pages.
+
+Most kernel allocations are unmovable. Important examples include the memory
+map (usually 1/64ths of memory), page tables, and kmalloc(). Such allocations
+can only be served from the kernel zones.
+
+Most user space pages, such as anonymous memory, and page cache pages are
+movable. Such allocations can be served from ZONE_MOVABLE and the kernel zones.
+
+Only movable allocations are served from ZONE_MOVABLE, resulting in unmovable
+allocations being limited to the kernel zones. Without ZONE_MOVABLE, there is
+absolutely no guarantee whether a memory block can be offlined successfully.
+
+Zone Imbalances
+---------------
+
+Having too much system RAM managed by ZONE_MOVABLE is called a zone imbalance,
+which can harm the system or degrade performance. As one example, the kernel
+might crash because it runs out of free memory for unmovable allocations,
+although there is still plenty of free memory left in ZONE_MOVABLE.
+
+Usually, MOVABLE:KERNEL ratios of up to 3:1 or even 4:1 are fine. Ratios of 63:1
+are definitely impossible due to the overhead for the memory map.
+
+Actual safe zone ratios depend on the workload. Extreme cases, like excessive
+long-term pinning of pages, might not be able to deal with ZONE_MOVABLE at all.
+
+.. note::
+
+  CMA memory part of a kernel zone essentially behaves like memory in
+  ZONE_MOVABLE and similar considerations apply, especially when combining
+  CMA with ZONE_MOVABLE.
+
+ZONE_MOVABLE Sizing Considerations
+----------------------------------
+
+We usually expect that a large portion of available system RAM will actually
+be consumed by user space, either directly or indirectly via the page cache. In
+the normal case, ZONE_MOVABLE can be used when allocating such pages just fine.
+
+With that in mind, it makes sense that we can have a big portion of system RAM
+managed by ZONE_MOVABLE. However, there are some things to consider when using
+ZONE_MOVABLE, especially when fine-tuning zone ratios:
+
+- Having a lot of offline memory blocks. Even offline memory blocks consume
+  memory for metadata and page tables in the direct map; having a lot of offline
+  memory blocks is not a typical case, though.
+
+- Memory ballooning without support for balloon memory migration is incompatible
+  with ZONE_MOVABLE. Only some implementations, such as virtio-balloon and
+  pseries CMM, fully support balloon memory migration.
+
+  Further, the CONFIG_BALLOON_MIGRATION kernel configuration option might be
+  disabled. In that case, balloon inflation will only perform unmovable
+  allocations and silently create a zone imbalance, usually triggered by
+  inflation requests from the hypervisor.
+
+- Gigantic pages are unmovable when an architecture does not support
+  huge page migration and/or the ``movable_gigantic_pages`` sysctl is false.
+  See Documentation/admin-guide/sysctl/vm.rst for more info on this sysctl.
+
+- Huge pages are unmovable when an architectures does not support huge
+  page migration, resulting in a similar issue as with gigantic pages.
+
+- Page tables are unmovable. Excessive swapping, mapping extremely large
+  files or ZONE_DEVICE memory can be problematic, although only really relevant
+  in corner cases. When we manage a lot of user space memory that has been
+  swapped out or is served from a file/persistent memory/... we still need a lot
+  of page tables to manage that memory once user space accessed that memory.
+
+- In certain DAX configurations the memory map for the device memory will be
+  allocated from the kernel zones.
+
+- KASAN can have a significant memory overhead, for example, consuming 1/8th of
+  the total system memory size as (unmovable) tracking metadata.
+
+- Long-term pinning of pages. Techniques that rely on long-term pinnings
+  (especially, RDMA and vfio/mdev) are fundamentally problematic with
+  ZONE_MOVABLE, and therefore, memory offlining. Pinned pages cannot reside
+  on ZONE_MOVABLE as that would turn these pages unmovable. Therefore, they
+  have to be migrated off that zone while pinning. Pinning a page can fail
+  even if there is plenty of free memory in ZONE_MOVABLE.
+
+  In addition, using ZONE_MOVABLE might make page pinning more expensive,
+  because of the page migration overhead.
+
+By default, all the memory configured at boot time is managed by the kernel
+zones and ZONE_MOVABLE is not used.
+
+To enable ZONE_MOVABLE to include the memory present at boot and to control the
+ratio between movable and kernel zones there are two command line options:
+``kernelcore=`` and ``movablecore=``. See
+Documentation/admin-guide/kernel-parameters.rst for their description.
+
+Memory Offlining and ZONE_MOVABLE
+---------------------------------
+
+Even with ZONE_MOVABLE, there are some corner cases where offlining a memory
+block might fail:
+
+- Memory blocks with memory holes; this applies to memory blocks present during
+  boot and can apply to memory blocks hotplugged via the XEN balloon and the
+  Hyper-V balloon.
+
+- Mixed NUMA nodes and mixed zones within a single memory block prevent memory
+  offlining; this applies to memory blocks present during boot only.
+
+- Special memory blocks prevented by the system from getting offlined. Examples
+  include any memory available during boot on arm64 or memory blocks spanning
+  the crashkernel area on s390x; this usually applies to memory blocks present
+  during boot only.
+
+- Memory blocks overlapping with CMA areas cannot be offlined, this applies to
+  memory blocks present during boot only.
+
+- Concurrent activity that operates on the same physical memory area, such as
+  allocating gigantic pages, can result in temporary offlining failures.
+
+- When an admin sets the ``movable_gigantic_pages`` sysctl to true, gigantic
+  pages are allowed in ZONE_MOVABLE.  This only allows migratable gigantic
+  pages to be allocated; however, if there are no eligible destination gigantic
+  pages at offline, the offlining operation will fail.
+
+  Users leveraging ``movable_gigantic_pages`` should weigh the value of
+  ZONE_MOVABLE for increasing the reliability of gigantic page allocation
+  against the potential loss of hot-unplug reliability.
+
+- Out of memory when dissolving huge pages, especially when HugeTLB Vmemmap
+  Optimization (HVO) is enabled.
+
+  Offlining code may be able to migrate huge page contents, but may not be able
+  to dissolve the source huge page because it fails allocating (unmovable) pages
+  for the vmemmap, because the system might not have free memory in the kernel
+  zones left.
+
+  Users that depend on memory offlining to succeed for movable zones should
+  carefully consider whether the memory savings gained from this feature are
+  worth the risk of possibly not being able to offline memory in certain
+  situations.
+
+Further, when running into out of memory situations while migrating pages, or
+when still encountering permanently unmovable pages within ZONE_MOVABLE
+(-> BUG), memory offlining will keep retrying until it eventually succeeds.
+
+When offlining is triggered from user space, the offlining context can be
+terminated by sending a signal. A timeout based offlining can easily be
+implemented via::
+
+	% timeout $TIMEOUT offline_block | failure_handling
diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst
new file mode 100644
index 000000000..9cb54b4ff
--- /dev/null
+++ b/Documentation/admin-guide/mm/multigen_lru.rst
@@ -0,0 +1,163 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+Multi-Gen LRU
+=============
+The multi-gen LRU is an alternative LRU implementation that optimizes
+page reclaim and improves performance under memory pressure. Page
+reclaim decides the kernel's caching policy and ability to overcommit
+memory. It directly impacts the kswapd CPU usage and RAM efficiency.
+
+Quick start
+===========
+Build the kernel with the following configurations.
+
+* ``CONFIG_LRU_GEN=y``
+* ``CONFIG_LRU_GEN_ENABLED=y``
+
+All set!
+
+Runtime options
+===============
+``/sys/kernel/mm/lru_gen/`` contains stable ABIs described in the
+following subsections.
+
+Kill switch
+-----------
+``enabled`` accepts different values to enable or disable the
+following components. Its default value depends on
+``CONFIG_LRU_GEN_ENABLED``. All the components should be enabled
+unless some of them have unforeseen side effects. Writing to
+``enabled`` has no effect when a component is not supported by the
+hardware, and valid values will be accepted even when the main switch
+is off.
+
+====== ===============================================================
+Values Components
+====== ===============================================================
+0x0001 The main switch for the multi-gen LRU.
+0x0002 Clearing the accessed bit in leaf page table entries in large
+       batches, when MMU sets it (e.g., on x86). This behavior can
+       theoretically worsen lock contention (mmap_lock). If it is
+       disabled, the multi-gen LRU will suffer a minor performance
+       degradation for workloads that contiguously map hot pages,
+       whose accessed bits can be otherwise cleared by fewer larger
+       batches.
+0x0004 Clearing the accessed bit in non-leaf page table entries as
+       well, when MMU sets it (e.g., on x86). This behavior was not
+       verified on x86 varieties other than Intel and AMD. If it is
+       disabled, the multi-gen LRU will suffer a negligible
+       performance degradation.
+[yYnN] Apply to all the components above.
+====== ===============================================================
+
+E.g.,
+::
+
+    echo y >/sys/kernel/mm/lru_gen/enabled
+    cat /sys/kernel/mm/lru_gen/enabled
+    0x0007
+    echo 5 >/sys/kernel/mm/lru_gen/enabled
+    cat /sys/kernel/mm/lru_gen/enabled
+    0x0005
+
+Thrashing prevention
+--------------------
+Personal computers are more sensitive to thrashing because it can
+cause janks (lags when rendering UI) and negatively impact user
+experience. The multi-gen LRU offers thrashing prevention to the
+majority of laptop and desktop users who do not have ``oomd``.
+
+Users can write ``N`` to ``min_ttl_ms`` to prevent the working set of
+``N`` milliseconds from getting evicted. The OOM killer is triggered
+if this working set cannot be kept in memory. In other words, this
+option works as an adjustable pressure relief valve, and when open, it
+terminates applications that are hopefully not being used.
+
+Based on the average human detectable lag (~100ms), ``N=1000`` usually
+eliminates intolerable janks due to thrashing. Larger values like
+``N=3000`` make janks less noticeable at the risk of premature OOM
+kills.
+
+The default value ``0`` means disabled.
+
+Experimental features
+=====================
+``/sys/kernel/debug/lru_gen`` accepts commands described in the
+following subsections. Multiple command lines are supported, so does
+concatenation with delimiters ``,`` and ``;``.
+
+``/sys/kernel/debug/lru_gen_full`` provides additional stats for
+debugging. ``CONFIG_LRU_GEN_STATS=y`` keeps historical stats from
+evicted generations in this file.
+
+Working set estimation
+----------------------
+Working set estimation measures how much memory an application needs
+in a given time interval, and it is usually done with little impact on
+the performance of the application. E.g., data centers want to
+optimize job scheduling (bin packing) to improve memory utilizations.
+When a new job comes in, the job scheduler needs to find out whether
+each server it manages can allocate a certain amount of memory for
+this new job before it can pick a candidate. To do so, the job
+scheduler needs to estimate the working sets of the existing jobs.
+
+When it is read, ``lru_gen`` returns a histogram of numbers of pages
+accessed over different time intervals for each memcg and node.
+``MAX_NR_GENS`` decides the number of bins for each histogram. The
+histograms are noncumulative.
+::
+
+    memcg  memcg_id  memcg_path
+       node  node_id
+           min_gen_nr  age_in_ms  nr_anon_pages  nr_file_pages
+           ...
+           max_gen_nr  age_in_ms  nr_anon_pages  nr_file_pages
+
+Each bin contains an estimated number of pages that have been accessed
+within ``age_in_ms``. E.g., ``min_gen_nr`` contains the coldest pages
+and ``max_gen_nr`` contains the hottest pages, since ``age_in_ms`` of
+the former is the largest and that of the latter is the smallest.
+
+Users can write the following command to ``lru_gen`` to create a new
+generation ``max_gen_nr+1``:
+
+    ``+ memcg_id node_id max_gen_nr [can_swap [force_scan]]``
+
+``can_swap`` defaults to the swap setting and, if it is set to ``1``,
+it forces the scan of anon pages when swap is off, and vice versa.
+``force_scan`` defaults to ``1`` and, if it is set to ``0``, it
+employs heuristics to reduce the overhead, which is likely to reduce
+the coverage as well.
+
+A typical use case is that a job scheduler runs this command at a
+certain time interval to create new generations, and it ranks the
+servers it manages based on the sizes of their cold pages defined by
+this time interval.
+
+Proactive reclaim
+-----------------
+Proactive reclaim induces page reclaim when there is no memory
+pressure. It usually targets cold pages only. E.g., when a new job
+comes in, the job scheduler wants to proactively reclaim cold pages on
+the server it selected, to improve the chance of successfully landing
+this new job.
+
+Users can write the following command to ``lru_gen`` to evict
+generations less than or equal to ``min_gen_nr``.
+
+    ``- memcg_id node_id min_gen_nr [swappiness [nr_to_reclaim]]``
+
+``min_gen_nr`` should be less than ``max_gen_nr-1``, since
+``max_gen_nr`` and ``max_gen_nr-1`` are not fully aged (equivalent to
+the active list) and therefore cannot be evicted. ``swappiness``
+overrides the default value in ``/proc/sys/vm/swappiness`` and the valid
+range is [0-200, max], with max being exclusively used for the reclamation
+of anonymous memory. ``nr_to_reclaim`` limits the number of pages to evict.
+
+A typical use case is that a job scheduler runs this command before it
+tries to land a new job on a server. If it fails to materialize enough
+cold pages because of the overestimation, it retries on the next
+server according to the ranking result obtained from the working set
+estimation step. This less forceful approach limits the impacts on the
+existing jobs.
diff --git a/Documentation/admin-guide/mm/nommu-mmap.rst b/Documentation/admin-guide/mm/nommu-mmap.rst
new file mode 100644
index 000000000..8a1949b36
--- /dev/null
+++ b/Documentation/admin-guide/mm/nommu-mmap.rst
@@ -0,0 +1,283 @@
+=============================
+No-MMU memory mapping support
+=============================
+
+The kernel has limited support for memory mapping under no-MMU conditions, such
+as are used in uClinux environments. From the userspace point of view, memory
+mapping is made use of in conjunction with the mmap() system call, the shmat()
+call and the execve() system call. From the kernel's point of view, execve()
+mapping is actually performed by the binfmt drivers, which call back into the
+mmap() routines to do the actual work.
+
+Memory mapping behaviour also involves the way fork(), vfork(), clone() and
+ptrace() work. Under uClinux there is no fork(), and clone() must be supplied
+the CLONE_VM flag.
+
+The behaviour is similar between the MMU and no-MMU cases, but not identical;
+and it's also much more restricted in the latter case:
+
+ (#) Anonymous mapping, MAP_PRIVATE
+
+	In the MMU case: VM regions backed by arbitrary pages; copy-on-write
+	across fork.
+
+	In the no-MMU case: VM regions backed by arbitrary contiguous runs of
+	pages.
+
+ (#) Anonymous mapping, MAP_SHARED
+
+	These behave very much like private mappings, except that they're
+	shared across fork() or clone() without CLONE_VM in the MMU case. Since
+	the no-MMU case doesn't support these, behaviour is identical to
+	MAP_PRIVATE there.
+
+ (#) File, MAP_PRIVATE, PROT_READ / PROT_EXEC, !PROT_WRITE
+
+	In the MMU case: VM regions backed by pages read from file; changes to
+	the underlying file are reflected in the mapping; copied across fork.
+
+	In the no-MMU case:
+
+         - If one exists, the kernel will reuse an existing mapping to the
+           same segment of the same file if that has compatible permissions,
+           even if this was created by another process.
+
+         - If possible, the file mapping will be directly on the backing device
+           if the backing device has the NOMMU_MAP_DIRECT capability and
+           appropriate mapping protection capabilities. Ramfs, romfs, cramfs
+           and mtd might all permit this.
+
+	 - If the backing device can't or won't permit direct sharing,
+           but does have the NOMMU_MAP_COPY capability, then a copy of the
+           appropriate bit of the file will be read into a contiguous bit of
+           memory and any extraneous space beyond the EOF will be cleared
+
+	 - Writes to the file do not affect the mapping; writes to the mapping
+	   are visible in other processes (no MMU protection), but should not
+	   happen.
+
+ (#) File, MAP_PRIVATE, PROT_READ / PROT_EXEC, PROT_WRITE
+
+	In the MMU case: like the non-PROT_WRITE case, except that the pages in
+	question get copied before the write actually happens. From that point
+	on writes to the file underneath that page no longer get reflected into
+	the mapping's backing pages. The page is then backed by swap instead.
+
+	In the no-MMU case: works much like the non-PROT_WRITE case, except
+	that a copy is always taken and never shared.
+
+ (#) Regular file / blockdev, MAP_SHARED, PROT_READ / PROT_EXEC / PROT_WRITE
+
+	In the MMU case: VM regions backed by pages read from file; changes to
+	pages written back to file; writes to file reflected into pages backing
+	mapping; shared across fork.
+
+	In the no-MMU case: not supported.
+
+ (#) Memory backed regular file, MAP_SHARED, PROT_READ / PROT_EXEC / PROT_WRITE
+
+	In the MMU case: As for ordinary regular files.
+
+	In the no-MMU case: The filesystem providing the memory-backed file
+	(such as ramfs or tmpfs) may choose to honour an open, truncate, mmap
+	sequence by providing a contiguous sequence of pages to map. In that
+	case, a shared-writable memory mapping will be possible. It will work
+	as for the MMU case. If the filesystem does not provide any such
+	support, then the mapping request will be denied.
+
+ (#) Memory backed blockdev, MAP_SHARED, PROT_READ / PROT_EXEC / PROT_WRITE
+
+	In the MMU case: As for ordinary regular files.
+
+	In the no-MMU case: As for memory backed regular files, but the
+	blockdev must be able to provide a contiguous run of pages without
+	truncate being called. The ramdisk driver could do this if it allocated
+	all its memory as a contiguous array upfront.
+
+ (#) Memory backed chardev, MAP_SHARED, PROT_READ / PROT_EXEC / PROT_WRITE
+
+	In the MMU case: As for ordinary regular files.
+
+	In the no-MMU case: The character device driver may choose to honour
+	the mmap() by providing direct access to the underlying device if it
+	provides memory or quasi-memory that can be accessed directly. Examples
+	of such are frame buffers and flash devices. If the driver does not
+	provide any such support, then the mapping request will be denied.
+
+
+Further notes on no-MMU MMAP
+============================
+
+ (#) A request for a private mapping of a file may return a buffer that is not
+     page-aligned.  This is because XIP may take place, and the data may not be
+     paged aligned in the backing store.
+
+ (#) A request for an anonymous mapping will always be page aligned.  If
+     possible the size of the request should be a power of two otherwise some
+     of the space may be wasted as the kernel must allocate a power-of-2
+     granule but will only discard the excess if appropriately configured as
+     this has an effect on fragmentation.
+
+ (#) The memory allocated by a request for an anonymous mapping will normally
+     be cleared by the kernel before being returned in accordance with the
+     Linux man pages (ver 2.22 or later).
+
+     In the MMU case this can be achieved with reasonable performance as
+     regions are backed by virtual pages, with the contents only being mapped
+     to cleared physical pages when a write happens on that specific page
+     (prior to which, the pages are effectively mapped to the global zero page
+     from which reads can take place).  This spreads out the time it takes to
+     initialize the contents of a page - depending on the write-usage of the
+     mapping.
+
+     In the no-MMU case, however, anonymous mappings are backed by physical
+     pages, and the entire map is cleared at allocation time.  This can cause
+     significant delays during a userspace malloc() as the C library does an
+     anonymous mapping and the kernel then does a memset for the entire map.
+
+     However, for memory that isn't required to be precleared - such as that
+     returned by malloc() - mmap() can take a MAP_UNINITIALIZED flag to
+     indicate to the kernel that it shouldn't bother clearing the memory before
+     returning it.  Note that CONFIG_MMAP_ALLOW_UNINITIALIZED must be enabled
+     to permit this, otherwise the flag will be ignored.
+
+     uClibc uses this to speed up malloc(), and the ELF-FDPIC binfmt uses this
+     to allocate the brk and stack region.
+
+ (#) A list of all the private copy and anonymous mappings on the system is
+     visible through /proc/maps in no-MMU mode.
+
+ (#) A list of all the mappings in use by a process is visible through
+     /proc/<pid>/maps in no-MMU mode.
+
+ (#) Supplying MAP_FIXED or a requesting a particular mapping address will
+     result in an error.
+
+ (#) Files mapped privately usually have to have a read method provided by the
+     driver or filesystem so that the contents can be read into the memory
+     allocated if mmap() chooses not to map the backing device directly. An
+     error will result if they don't. This is most likely to be encountered
+     with character device files, pipes, fifos and sockets.
+
+
+Interprocess shared memory
+==========================
+
+Both SYSV IPC SHM shared memory and POSIX shared memory is supported in NOMMU
+mode.  The former through the usual mechanism, the latter through files created
+on ramfs or tmpfs mounts.
+
+
+Futexes
+=======
+
+Futexes are supported in NOMMU mode if the arch supports them.  An error will
+be given if an address passed to the futex system call lies outside the
+mappings made by a process or if the mapping in which the address lies does not
+support futexes (such as an I/O chardev mapping).
+
+
+No-MMU mremap
+=============
+
+The mremap() function is partially supported.  It may change the size of a
+mapping, and may move it [#]_ if MREMAP_MAYMOVE is specified and if the new size
+of the mapping exceeds the size of the slab object currently occupied by the
+memory to which the mapping refers, or if a smaller slab object could be used.
+
+MREMAP_FIXED is not supported, though it is ignored if there's no change of
+address and the object does not need to be moved.
+
+Shared mappings may not be moved.  Shareable mappings may not be moved either,
+even if they are not currently shared.
+
+The mremap() function must be given an exact match for base address and size of
+a previously mapped object.  It may not be used to create holes in existing
+mappings, move parts of existing mappings or resize parts of mappings.  It must
+act on a complete mapping.
+
+.. [#] Not currently supported.
+
+
+Providing shareable character device support
+============================================
+
+To provide shareable character device support, a driver must provide a
+file->f_op->get_unmapped_area() operation. The mmap() routines will call this
+to get a proposed address for the mapping. This may return an error if it
+doesn't wish to honour the mapping because it's too long, at a weird offset,
+under some unsupported combination of flags or whatever.
+
+The driver should also provide backing device information with capabilities set
+to indicate the permitted types of mapping on such devices. The default is
+assumed to be readable and writable, not executable, and only shareable
+directly (can't be copied).
+
+The file->f_op->mmap() operation will be called to actually inaugurate the
+mapping. It can be rejected at that point. Returning the ENOSYS error will
+cause the mapping to be copied instead if NOMMU_MAP_COPY is specified.
+
+The vm_ops->close() routine will be invoked when the last mapping on a chardev
+is removed. An existing mapping will be shared, partially or not, if possible
+without notifying the driver.
+
+It is permitted also for the file->f_op->get_unmapped_area() operation to
+return -ENOSYS. This will be taken to mean that this operation just doesn't
+want to handle it, despite the fact it's got an operation. For instance, it
+might try directing the call to a secondary driver which turns out not to
+implement it. Such is the case for the framebuffer driver which attempts to
+direct the call to the device-specific driver. Under such circumstances, the
+mapping request will be rejected if NOMMU_MAP_COPY is not specified, and a
+copy mapped otherwise.
+
+.. important::
+
+	Some types of device may present a different appearance to anyone
+	looking at them in certain modes. Flash chips can be like this; for
+	instance if they're in programming or erase mode, you might see the
+	status reflected in the mapping, instead of the data.
+
+	In such a case, care must be taken lest userspace see a shared or a
+	private mapping showing such information when the driver is busy
+	controlling the device. Remember especially: private executable
+	mappings may still be mapped directly off the device under some
+	circumstances!
+
+
+Providing shareable memory-backed file support
+==============================================
+
+Provision of shared mappings on memory backed files is similar to the provision
+of support for shared mapped character devices. The main difference is that the
+filesystem providing the service will probably allocate a contiguous collection
+of pages and permit mappings to be made on that.
+
+It is recommended that a truncate operation applied to such a file that
+increases the file size, if that file is empty, be taken as a request to gather
+enough pages to honour a mapping. This is required to support POSIX shared
+memory.
+
+Memory backed devices are indicated by the mapping's backing device info having
+the memory_backed flag set.
+
+
+Providing shareable block device support
+========================================
+
+Provision of shared mappings on block device files is exactly the same as for
+character devices. If there isn't a real device underneath, then the driver
+should allocate sufficient contiguous memory to honour any supported mapping.
+
+
+Adjusting page trimming behaviour
+=================================
+
+NOMMU mmap automatically rounds up to the nearest power-of-2 number of pages
+when performing an allocation.  This can have adverse effects on memory
+fragmentation, and as such, is left configurable.  The default behaviour is to
+aggressively trim allocations and discard any excess pages back in to the page
+allocator.  In order to retain finer-grained control over fragmentation, this
+behaviour can either be disabled completely, or bumped up to a higher page
+watermark where trimming begins.
+
+Page trimming behaviour is configurable via the sysctl ``vm.nr_trim_pages``.
diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst
new file mode 100644
index 000000000..90ab26e80
--- /dev/null
+++ b/Documentation/admin-guide/mm/numa_memory_policy.rst
@@ -0,0 +1,523 @@
+==================
+NUMA Memory Policy
+==================
+
+What is NUMA Memory Policy?
+============================
+
+In the Linux kernel, "memory policy" determines from which node the kernel will
+allocate memory in a NUMA system or in an emulated NUMA system.  Linux has
+supported platforms with Non-Uniform Memory Access architectures since 2.4.?.
+The current memory policy support was added to Linux 2.6 around May 2004.  This
+document attempts to describe the concepts and APIs of the 2.6 memory policy
+support.
+
+Memory policies should not be confused with cpusets
+(``Documentation/admin-guide/cgroup-v1/cpusets.rst``)
+which is an administrative mechanism for restricting the nodes from which
+memory may be allocated by a set of processes. Memory policies are a
+programming interface that a NUMA-aware application can take advantage of.  When
+both cpusets and policies are applied to a task, the restrictions of the cpuset
+takes priority.  See :ref:`Memory Policies and cpusets <mem_pol_and_cpusets>`
+below for more details.
+
+Memory Policy Concepts
+======================
+
+Scope of Memory Policies
+------------------------
+
+The Linux kernel supports _scopes_ of memory policy, described here from
+most general to most specific:
+
+System Default Policy
+	this policy is "hard coded" into the kernel.  It is the policy
+	that governs all page allocations that aren't controlled by
+	one of the more specific policy scopes discussed below.  When
+	the system is "up and running", the system default policy will
+	use "local allocation" described below.  However, during boot
+	up, the system default policy will be set to interleave
+	allocations across all nodes with "sufficient" memory, so as
+	not to overload the initial boot node with boot-time
+	allocations.
+
+Task/Process Policy
+	this is an optional, per-task policy.  When defined for a
+	specific task, this policy controls all page allocations made
+	by or on behalf of the task that aren't controlled by a more
+	specific scope. If a task does not define a task policy, then
+	all page allocations that would have been controlled by the
+	task policy "fall back" to the System Default Policy.
+
+	The task policy applies to the entire address space of a task. Thus,
+	it is inheritable, and indeed is inherited, across both fork()
+	[clone() w/o the CLONE_VM flag] and exec*().  This allows a parent task
+	to establish the task policy for a child task exec()'d from an
+	executable image that has no awareness of memory policy.  See the
+	:ref:`Memory Policy APIs <memory_policy_apis>` section,
+	below, for an overview of the system call
+	that a task may use to set/change its task/process policy.
+
+	In a multi-threaded task, task policies apply only to the thread
+	[Linux kernel task] that installs the policy and any threads
+	subsequently created by that thread.  Any sibling threads existing
+	at the time a new task policy is installed retain their current
+	policy.
+
+	A task policy applies only to pages allocated after the policy is
+	installed.  Any pages already faulted in by the task when the task
+	changes its task policy remain where they were allocated based on
+	the policy at the time they were allocated.
+
+.. _vma_policy:
+
+VMA Policy
+	A "VMA" or "Virtual Memory Area" refers to a range of a task's
+	virtual address space.  A task may define a specific policy for a range
+	of its virtual address space.   See the
+	:ref:`Memory Policy APIs <memory_policy_apis>` section,
+	below, for an overview of the mbind() system call used to set a VMA
+	policy.
+
+	A VMA policy will govern the allocation of pages that back
+	this region of the address space.  Any regions of the task's
+	address space that don't have an explicit VMA policy will fall
+	back to the task policy, which may itself fall back to the
+	System Default Policy.
+
+	VMA policies have a few complicating details:
+
+	* VMA policy applies ONLY to anonymous pages.  These include
+	  pages allocated for anonymous segments, such as the task
+	  stack and heap, and any regions of the address space
+	  mmap()ed with the MAP_ANONYMOUS flag.  If a VMA policy is
+	  applied to a file mapping, it will be ignored if the mapping
+	  used the MAP_SHARED flag.  If the file mapping used the
+	  MAP_PRIVATE flag, the VMA policy will only be applied when
+	  an anonymous page is allocated on an attempt to write to the
+	  mapping-- i.e., at Copy-On-Write.
+
+	* VMA policies are shared between all tasks that share a
+	  virtual address space--a.k.a. threads--independent of when
+	  the policy is installed; and they are inherited across
+	  fork().  However, because VMA policies refer to a specific
+	  region of a task's address space, and because the address
+	  space is discarded and recreated on exec*(), VMA policies
+	  are NOT inheritable across exec().  Thus, only NUMA-aware
+	  applications may use VMA policies.
+
+	* A task may install a new VMA policy on a sub-range of a
+	  previously mmap()ed region.  When this happens, Linux splits
+	  the existing virtual memory area into 2 or 3 VMAs, each with
+	  its own policy.
+
+	* By default, VMA policy applies only to pages allocated after
+	  the policy is installed.  Any pages already faulted into the
+	  VMA range remain where they were allocated based on the
+	  policy at the time they were allocated.  However, since
+	  2.6.16, Linux supports page migration via the mbind() system
+	  call, so that page contents can be moved to match a newly
+	  installed policy.
+
+Shared Policy
+	Conceptually, shared policies apply to "memory objects" mapped
+	shared into one or more tasks' distinct address spaces.  An
+	application installs shared policies the same way as VMA
+	policies--using the mbind() system call specifying a range of
+	virtual addresses that map the shared object.  However, unlike
+	VMA policies, which can be considered to be an attribute of a
+	range of a task's address space, shared policies apply
+	directly to the shared object.  Thus, all tasks that attach to
+	the object share the policy, and all pages allocated for the
+	shared object, by any task, will obey the shared policy.
+
+	As of 2.6.22, only shared memory segments, created by shmget() or
+	mmap(MAP_ANONYMOUS|MAP_SHARED), support shared policy.  When shared
+	policy support was added to Linux, the associated data structures were
+	added to hugetlbfs shmem segments.  At the time, hugetlbfs did not
+	support allocation at fault time--a.k.a lazy allocation--so hugetlbfs
+	shmem segments were never "hooked up" to the shared policy support.
+	Although hugetlbfs segments now support lazy allocation, their support
+	for shared policy has not been completed.
+
+	As mentioned above in :ref:`VMA policies <vma_policy>` section,
+	allocations of page cache pages for regular files mmap()ed
+	with MAP_SHARED ignore any VMA policy installed on the virtual
+	address range backed by the shared file mapping.  Rather,
+	shared page cache pages, including pages backing private
+	mappings that have not yet been written by the task, follow
+	task policy, if any, else System Default Policy.
+
+	The shared policy infrastructure supports different policies on subset
+	ranges of the shared object.  However, Linux still splits the VMA of
+	the task that installs the policy for each range of distinct policy.
+	Thus, different tasks that attach to a shared memory segment can have
+	different VMA configurations mapping that one shared object.  This
+	can be seen by examining the /proc/<pid>/numa_maps of tasks sharing
+	a shared memory region, when one task has installed shared policy on
+	one or more ranges of the region.
+
+Components of Memory Policies
+-----------------------------
+
+A NUMA memory policy consists of a "mode", optional mode flags, and
+an optional set of nodes.  The mode determines the behavior of the
+policy, the optional mode flags determine the behavior of the mode,
+and the optional set of nodes can be viewed as the arguments to the
+policy behavior.
+
+Internally, memory policies are implemented by a reference counted
+structure, struct mempolicy.  Details of this structure will be
+discussed in context, below, as required to explain the behavior.
+
+NUMA memory policy supports the following 4 behavioral modes:
+
+Default Mode--MPOL_DEFAULT
+	This mode is only used in the memory policy APIs.  Internally,
+	MPOL_DEFAULT is converted to the NULL memory policy in all
+	policy scopes.  Any existing non-default policy will simply be
+	removed when MPOL_DEFAULT is specified.  As a result,
+	MPOL_DEFAULT means "fall back to the next most specific policy
+	scope."
+
+	For example, a NULL or default task policy will fall back to the
+	system default policy.  A NULL or default vma policy will fall
+	back to the task policy.
+
+	When specified in one of the memory policy APIs, the Default mode
+	does not use the optional set of nodes.
+
+	It is an error for the set of nodes specified for this policy to
+	be non-empty.
+
+MPOL_BIND
+	This mode specifies that memory must come from the set of
+	nodes specified by the policy.  Memory will be allocated from
+	the node in the set with sufficient free memory that is
+	closest to the node where the allocation takes place.
+
+MPOL_PREFERRED
+	This mode specifies that the allocation should be attempted
+	from the single node specified in the policy.  If that
+	allocation fails, the kernel will search other nodes, in order
+	of increasing distance from the preferred node based on
+	information provided by the platform firmware.
+
+	Internally, the Preferred policy uses a single node--the
+	preferred_node member of struct mempolicy.  When the internal
+	mode flag MPOL_F_LOCAL is set, the preferred_node is ignored
+	and the policy is interpreted as local allocation.  "Local"
+	allocation policy can be viewed as a Preferred policy that
+	starts at the node containing the cpu where the allocation
+	takes place.
+
+	It is possible for the user to specify that local allocation
+	is always preferred by passing an empty nodemask with this
+	mode.  If an empty nodemask is passed, the policy cannot use
+	the MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES flags
+	described below.
+
+MPOL_INTERLEAVE
+	This mode specifies that page allocations be interleaved, on a
+	page granularity, across the nodes specified in the policy.
+	This mode also behaves slightly differently, based on the
+	context where it is used:
+
+	For allocation of anonymous pages and shared memory pages,
+	Interleave mode indexes the set of nodes specified by the
+	policy using the page offset of the faulting address into the
+	segment [VMA] containing the address modulo the number of
+	nodes specified by the policy.  It then attempts to allocate a
+	page, starting at the selected node, as if the node had been
+	specified by a Preferred policy or had been selected by a
+	local allocation.  That is, allocation will follow the per
+	node zonelist.
+
+	For allocation of page cache pages, Interleave mode indexes
+	the set of nodes specified by the policy using a node counter
+	maintained per task.  This counter wraps around to the lowest
+	specified node after it reaches the highest specified node.
+	This will tend to spread the pages out over the nodes
+	specified by the policy based on the order in which they are
+	allocated, rather than based on any page offset into an
+	address range or file.  During system boot up, the temporary
+	interleaved system default policy works in this mode.
+
+MPOL_PREFERRED_MANY
+	This mode specifies that the allocation should be preferably
+	satisfied from the nodemask specified in the policy. If there is
+	a memory pressure on all nodes in the nodemask, the allocation
+	can fall back to all existing numa nodes. This is effectively
+	MPOL_PREFERRED allowed for a mask rather than a single node.
+
+MPOL_WEIGHTED_INTERLEAVE
+	This mode operates the same as MPOL_INTERLEAVE, except that
+	interleaving behavior is executed based on weights set in
+	/sys/kernel/mm/mempolicy/weighted_interleave/
+
+	Weighted interleave allocates pages on nodes according to a
+	weight.  For example if nodes [0,1] are weighted [5,2], 5 pages
+	will be allocated on node0 for every 2 pages allocated on node1.
+
+NUMA memory policy supports the following optional mode flags:
+
+MPOL_F_STATIC_NODES
+	This flag specifies that the nodemask passed by
+	the user should not be remapped if the task or VMA's set of allowed
+	nodes changes after the memory policy has been defined.
+
+	Without this flag, any time a mempolicy is rebound because of a
+        change in the set of allowed nodes, the preferred nodemask (Preferred
+        Many), preferred node (Preferred) or nodemask (Bind, Interleave) is
+        remapped to the new set of allowed nodes.  This may result in nodes
+        being used that were previously undesired.
+
+	With this flag, if the user-specified nodes overlap with the
+	nodes allowed by the task's cpuset, then the memory policy is
+	applied to their intersection.  If the two sets of nodes do not
+	overlap, the Default policy is used.
+
+	For example, consider a task that is attached to a cpuset with
+	mems 1-3 that sets an Interleave policy over the same set.  If
+	the cpuset's mems change to 3-5, the Interleave will now occur
+	over nodes 3, 4, and 5.  With this flag, however, since only node
+	3 is allowed from the user's nodemask, the "interleave" only
+	occurs over that node.  If no nodes from the user's nodemask are
+	now allowed, the Default behavior is used.
+
+	MPOL_F_STATIC_NODES cannot be combined with the
+	MPOL_F_RELATIVE_NODES flag.  It also cannot be used for
+	MPOL_PREFERRED policies that were created with an empty nodemask
+	(local allocation).
+
+MPOL_F_RELATIVE_NODES
+	This flag specifies that the nodemask passed
+	by the user will be mapped relative to the set of the task or VMA's
+	set of allowed nodes.  The kernel stores the user-passed nodemask,
+	and if the allowed nodes changes, then that original nodemask will
+	be remapped relative to the new set of allowed nodes.
+
+	Without this flag (and without MPOL_F_STATIC_NODES), anytime a
+	mempolicy is rebound because of a change in the set of allowed
+	nodes, the node (Preferred) or nodemask (Bind, Interleave) is
+	remapped to the new set of allowed nodes.  That remap may not
+	preserve the relative nature of the user's passed nodemask to its
+	set of allowed nodes upon successive rebinds: a nodemask of
+	1,3,5 may be remapped to 7-9 and then to 1-3 if the set of
+	allowed nodes is restored to its original state.
+
+	With this flag, the remap is done so that the node numbers from
+	the user's passed nodemask are relative to the set of allowed
+	nodes.  In other words, if nodes 0, 2, and 4 are set in the user's
+	nodemask, the policy will be effected over the first (and in the
+	Bind or Interleave case, the third and fifth) nodes in the set of
+	allowed nodes.  The nodemask passed by the user represents nodes
+	relative to task or VMA's set of allowed nodes.
+
+	If the user's nodemask includes nodes that are outside the range
+	of the new set of allowed nodes (for example, node 5 is set in
+	the user's nodemask when the set of allowed nodes is only 0-3),
+	then the remap wraps around to the beginning of the nodemask and,
+	if not already set, sets the node in the mempolicy nodemask.
+
+	For example, consider a task that is attached to a cpuset with
+	mems 2-5 that sets an Interleave policy over the same set with
+	MPOL_F_RELATIVE_NODES.  If the cpuset's mems change to 3-7, the
+	interleave now occurs over nodes 3,5-7.  If the cpuset's mems
+	then change to 0,2-3,5, then the interleave occurs over nodes
+	0,2-3,5.
+
+	Thanks to the consistent remapping, applications preparing
+	nodemasks to specify memory policies using this flag should
+	disregard their current, actual cpuset imposed memory placement
+	and prepare the nodemask as if they were always located on
+	memory nodes 0 to N-1, where N is the number of memory nodes the
+	policy is intended to manage.  Let the kernel then remap to the
+	set of memory nodes allowed by the task's cpuset, as that may
+	change over time.
+
+	MPOL_F_RELATIVE_NODES cannot be combined with the
+	MPOL_F_STATIC_NODES flag.  It also cannot be used for
+	MPOL_PREFERRED policies that were created with an empty nodemask
+	(local allocation).
+
+Memory Policy Reference Counting
+================================
+
+To resolve use/free races, struct mempolicy contains an atomic reference
+count field.  Internal interfaces, mpol_get()/mpol_put() increment and
+decrement this reference count, respectively.  mpol_put() will only free
+the structure back to the mempolicy kmem cache when the reference count
+goes to zero.
+
+When a new memory policy is allocated, its reference count is initialized
+to '1', representing the reference held by the task that is installing the
+new policy.  When a pointer to a memory policy structure is stored in another
+structure, another reference is added, as the task's reference will be dropped
+on completion of the policy installation.
+
+During run-time "usage" of the policy, we attempt to minimize atomic operations
+on the reference count, as this can lead to cache lines bouncing between cpus
+and NUMA nodes.  "Usage" here means one of the following:
+
+1) querying of the policy, either by the task itself [using the get_mempolicy()
+   API discussed below] or by another task using the /proc/<pid>/numa_maps
+   interface.
+
+2) examination of the policy to determine the policy mode and associated node
+   or node lists, if any, for page allocation.  This is considered a "hot
+   path".  Note that for MPOL_BIND, the "usage" extends across the entire
+   allocation process, which may sleep during page reclamation, because the
+   BIND policy nodemask is used, by reference, to filter ineligible nodes.
+
+We can avoid taking an extra reference during the usages listed above as
+follows:
+
+1) we never need to get/free the system default policy as this is never
+   changed nor freed, once the system is up and running.
+
+2) for querying the policy, we do not need to take an extra reference on the
+   target task's task policy nor vma policies because we always acquire the
+   task's mm's mmap_lock for read during the query.  The set_mempolicy() and
+   mbind() APIs [see below] always acquire the mmap_lock for write when
+   installing or replacing task or vma policies.  Thus, there is no possibility
+   of a task or thread freeing a policy while another task or thread is
+   querying it.
+
+3) Page allocation usage of task or vma policy occurs in the fault path where
+   we hold them mmap_lock for read.  Again, because replacing the task or vma
+   policy requires that the mmap_lock be held for write, the policy can't be
+   freed out from under us while we're using it for page allocation.
+
+4) Shared policies require special consideration.  One task can replace a
+   shared memory policy while another task, with a distinct mmap_lock, is
+   querying or allocating a page based on the policy.  To resolve this
+   potential race, the shared policy infrastructure adds an extra reference
+   to the shared policy during lookup while holding a spin lock on the shared
+   policy management structure.  This requires that we drop this extra
+   reference when we're finished "using" the policy.  We must drop the
+   extra reference on shared policies in the same query/allocation paths
+   used for non-shared policies.  For this reason, shared policies are marked
+   as such, and the extra reference is dropped "conditionally"--i.e., only
+   for shared policies.
+
+   Because of this extra reference counting, and because we must lookup
+   shared policies in a tree structure under spinlock, shared policies are
+   more expensive to use in the page allocation path.  This is especially
+   true for shared policies on shared memory regions shared by tasks running
+   on different NUMA nodes.  This extra overhead can be avoided by always
+   falling back to task or system default policy for shared memory regions,
+   or by prefaulting the entire shared memory region into memory and locking
+   it down.  However, this might not be appropriate for all applications.
+
+.. _memory_policy_apis:
+
+Memory Policy APIs
+==================
+
+Linux supports 4 system calls for controlling memory policy.  These APIS
+always affect only the calling task, the calling task's address space, or
+some shared object mapped into the calling task's address space.
+
+.. note::
+   the headers that define these APIs and the parameter data types for
+   user space applications reside in a package that is not part of the
+   Linux kernel.  The kernel system call interfaces, with the 'sys\_'
+   prefix, are defined in <linux/syscalls.h>; the mode and flag
+   definitions are defined in <linux/mempolicy.h>.
+
+Set [Task] Memory Policy::
+
+	long set_mempolicy(int mode, const unsigned long *nmask,
+					unsigned long maxnode);
+
+Set's the calling task's "task/process memory policy" to mode
+specified by the 'mode' argument and the set of nodes defined by
+'nmask'.  'nmask' points to a bit mask of node ids containing at least
+'maxnode' ids.  Optional mode flags may be passed by combining the
+'mode' argument with the flag (for example: MPOL_INTERLEAVE |
+MPOL_F_STATIC_NODES).
+
+See the set_mempolicy(2) man page for more details
+
+
+Get [Task] Memory Policy or Related Information::
+
+	long get_mempolicy(int *mode,
+			   const unsigned long *nmask, unsigned long maxnode,
+			   void *addr, int flags);
+
+Queries the "task/process memory policy" of the calling task, or the
+policy or location of a specified virtual address, depending on the
+'flags' argument.
+
+See the get_mempolicy(2) man page for more details
+
+
+Install VMA/Shared Policy for a Range of Task's Address Space::
+
+	long mbind(void *start, unsigned long len, int mode,
+		   const unsigned long *nmask, unsigned long maxnode,
+		   unsigned flags);
+
+mbind() installs the policy specified by (mode, nmask, maxnodes) as a
+VMA policy for the range of the calling task's address space specified
+by the 'start' and 'len' arguments.  Additional actions may be
+requested via the 'flags' argument.
+
+See the mbind(2) man page for more details.
+
+Set home node for a Range of Task's Address Spacec::
+
+	long sys_set_mempolicy_home_node(unsigned long start, unsigned long len,
+					 unsigned long home_node,
+					 unsigned long flags);
+
+sys_set_mempolicy_home_node set the home node for a VMA policy present in the
+task's address range. The system call updates the home node only for the existing
+mempolicy range. Other address ranges are ignored. A home node is the NUMA node
+closest to which page allocation will come from. Specifying the home node override
+the default allocation policy to allocate memory close to the local node for an
+executing CPU.
+
+
+Memory Policy Command Line Interface
+====================================
+
+Although not strictly part of the Linux implementation of memory policy,
+a command line tool, numactl(8), exists that allows one to:
+
++ set the task policy for a specified program via set_mempolicy(2), fork(2) and
+  exec(2)
+
++ set the shared policy for a shared memory segment via mbind(2)
+
+The numactl(8) tool is packaged with the run-time version of the library
+containing the memory policy system call wrappers.  Some distributions
+package the headers and compile-time libraries in a separate development
+package.
+
+.. _mem_pol_and_cpusets:
+
+Memory Policies and cpusets
+===========================
+
+Memory policies work within cpusets as described above.  For memory policies
+that require a node or set of nodes, the nodes are restricted to the set of
+nodes whose memories are allowed by the cpuset constraints.  If the nodemask
+specified for the policy contains nodes that are not allowed by the cpuset and
+MPOL_F_RELATIVE_NODES is not used, the intersection of the set of nodes
+specified for the policy and the set of nodes with memory is used.  If the
+result is the empty set, the policy is considered invalid and cannot be
+installed.  If MPOL_F_RELATIVE_NODES is used, the policy's nodes are mapped
+onto and folded into the task's set of allowed nodes as previously described.
+
+The interaction of memory policies and cpusets can be problematic when tasks
+in two cpusets share access to a memory region, such as shared memory segments
+created by shmget() of mmap() with the MAP_ANONYMOUS and MAP_SHARED flags, and
+any of the tasks install shared policy on the region, only nodes whose
+memories are allowed in both cpusets may be used in the policies.  Obtaining
+this information requires "stepping outside" the memory policy APIs to use the
+cpuset information and requires that one know in what cpusets other task might
+be attaching to the shared region.  Furthermore, if the cpusets' allowed
+memory sets are disjoint, "local" allocation is the only valid policy.
diff --git a/Documentation/admin-guide/mm/numaperf.rst b/Documentation/admin-guide/mm/numaperf.rst
new file mode 100644
index 000000000..90a12b6a8
--- /dev/null
+++ b/Documentation/admin-guide/mm/numaperf.rst
@@ -0,0 +1,176 @@
+=======================
+NUMA Memory Performance
+=======================
+
+NUMA Locality
+=============
+
+Some platforms may have multiple types of memory attached to a compute
+node. These disparate memory ranges may share some characteristics, such
+as CPU cache coherence, but may have different performance. For example,
+different media types and buses affect bandwidth and latency.
+
+A system supports such heterogeneous memory by grouping each memory type
+under different domains, or "nodes", based on locality and performance
+characteristics.  Some memory may share the same node as a CPU, and others
+are provided as memory only nodes. While memory only nodes do not provide
+CPUs, they may still be local to one or more compute nodes relative to
+other nodes. The following diagram shows one such example of two compute
+nodes with local memory and a memory only node for each of compute node::
+
+ +------------------+     +------------------+
+ | Compute Node 0   +-----+ Compute Node 1   |
+ | Local Node0 Mem  |     | Local Node1 Mem  |
+ +--------+---------+     +--------+---------+
+          |                        |
+ +--------+---------+     +--------+---------+
+ | Slower Node2 Mem |     | Slower Node3 Mem |
+ +------------------+     +--------+---------+
+
+A "memory initiator" is a node containing one or more devices such as
+CPUs or separate memory I/O devices that can initiate memory requests.
+A "memory target" is a node containing one or more physical address
+ranges accessible from one or more memory initiators.
+
+When multiple memory initiators exist, they may not all have the same
+performance when accessing a given memory target. Each initiator-target
+pair may be organized into different ranked access classes to represent
+this relationship. The highest performing initiator to a given target
+is considered to be one of that target's local initiators, and given
+the highest access class, 0. Any given target may have one or more
+local initiators, and any given initiator may have multiple local
+memory targets.
+
+To aid applications matching memory targets with their initiators, the
+kernel provides symlinks to each other. The following example lists the
+relationship for the access class "0" memory initiators and targets::
+
+	# symlinks -v /sys/devices/system/node/nodeX/access0/targets/
+	relative: /sys/devices/system/node/nodeX/access0/targets/nodeY -> ../../nodeY
+
+	# symlinks -v /sys/devices/system/node/nodeY/access0/initiators/
+	relative: /sys/devices/system/node/nodeY/access0/initiators/nodeX -> ../../nodeX
+
+A memory initiator may have multiple memory targets in the same access
+class. The target memory's initiators in a given class indicate the
+nodes' access characteristics share the same performance relative to other
+linked initiator nodes. Each target within an initiator's access class,
+though, do not necessarily perform the same as each other.
+
+The access class "1" is used to allow differentiation between initiators
+that are CPUs and hence suitable for generic task scheduling, and
+IO initiators such as GPUs and NICs.  Unlike access class 0, only
+nodes containing CPUs are considered.
+
+NUMA Performance
+================
+
+Applications may wish to consider which node they want their memory to
+be allocated from based on the node's performance characteristics. If
+the system provides these attributes, the kernel exports them under the
+node sysfs hierarchy by appending the attributes directory under the
+memory node's access class 0 initiators as follows::
+
+	/sys/devices/system/node/nodeY/access0/initiators/
+
+These attributes apply only when accessed from nodes that have the
+are linked under the this access's initiators.
+
+The performance characteristics the kernel provides for the local initiators
+are exported are as follows::
+
+	# tree -P "read*|write*" /sys/devices/system/node/nodeY/access0/initiators/
+	/sys/devices/system/node/nodeY/access0/initiators/
+	|-- read_bandwidth
+	|-- read_latency
+	|-- write_bandwidth
+	`-- write_latency
+
+The bandwidth attributes are provided in MiB/second.
+
+The latency attributes are provided in nanoseconds.
+
+The values reported here correspond to the rated latency and bandwidth
+for the platform.
+
+Access class 1 takes the same form but only includes values for CPU to
+memory activity.
+
+NUMA Cache
+==========
+
+System memory may be constructed in a hierarchy of elements with various
+performance characteristics in order to provide large address space of
+slower performing memory cached by a smaller higher performing memory. The
+system physical addresses memory  initiators are aware of are provided
+by the last memory level in the hierarchy. The system meanwhile uses
+higher performing memory to transparently cache access to progressively
+slower levels.
+
+The term "far memory" is used to denote the last level memory in the
+hierarchy. Each increasing cache level provides higher performing
+initiator access, and the term "near memory" represents the fastest
+cache provided by the system.
+
+This numbering is different than CPU caches where the cache level (ex:
+L1, L2, L3) uses the CPU-side view where each increased level is lower
+performing. In contrast, the memory cache level is centric to the last
+level memory, so the higher numbered cache level corresponds to  memory
+nearer to the CPU, and further from far memory.
+
+The memory-side caches are not directly addressable by software. When
+software accesses a system address, the system will return it from the
+near memory cache if it is present. If it is not present, the system
+accesses the next level of memory until there is either a hit in that
+cache level, or it reaches far memory.
+
+An application does not need to know about caching attributes in order
+to use the system. Software may optionally query the memory cache
+attributes in order to maximize the performance out of such a setup.
+If the system provides a way for the kernel to discover this information,
+for example with ACPI HMAT (Heterogeneous Memory Attribute Table),
+the kernel will append these attributes to the NUMA node memory target.
+
+When the kernel first registers a memory cache with a node, the kernel
+will create the following directory::
+
+	/sys/devices/system/node/nodeX/memory_side_cache/
+
+If that directory is not present, the system either does not provide
+a memory-side cache, or that information is not accessible to the kernel.
+
+The attributes for each level of cache is provided under its cache
+level index::
+
+	/sys/devices/system/node/nodeX/memory_side_cache/indexA/
+	/sys/devices/system/node/nodeX/memory_side_cache/indexB/
+	/sys/devices/system/node/nodeX/memory_side_cache/indexC/
+
+Each cache level's directory provides its attributes. For example, the
+following shows a single cache level and the attributes available for
+software to query::
+
+	# tree /sys/devices/system/node/node0/memory_side_cache/
+	/sys/devices/system/node/node0/memory_side_cache/
+	|-- index1
+	|   |-- indexing
+	|   |-- line_size
+	|   |-- size
+	|   `-- write_policy
+
+The "indexing" will be 0 if it is a direct-mapped cache, and non-zero
+for any other indexed based, multi-way associativity.
+
+The "line_size" is the number of bytes accessed from the next cache
+level on a miss.
+
+The "size" is the number of bytes provided by this cache level.
+
+The "write_policy" will be 0 for write-back, and non-zero for
+write-through caching.
+
+See Also
+========
+
+[1] https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf
+- Section 5.2.27
diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
new file mode 100644
index 000000000..77447c454
--- /dev/null
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -0,0 +1,324 @@
+=============================
+Examining Process Page Tables
+=============================
+
+pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow
+userspace programs to examine the page tables and related information by
+reading files in ``/proc``.
+
+There are four components to pagemap:
+
+ * ``/proc/pid/pagemap``.  This file lets a userspace process find out which
+   physical frame each virtual page is mapped to.  It contains one 64-bit
+   value for each virtual page, containing the following data (from
+   ``fs/proc/task_mmu.c``, above pagemap_read):
+
+    * Bits 0-54  page frame number (PFN) if present
+    * Bits 0-4   swap type if swapped
+    * Bits 5-54  swap offset if swapped
+    * Bit  55    pte is soft-dirty (see
+      Documentation/admin-guide/mm/soft-dirty.rst)
+    * Bit  56    page exclusively mapped (since 4.2)
+    * Bit  57    pte is tracked by userfaultfd (since 5.13) — in a
+      ``VM_UFFD_WP`` VMA this indicates a write-protected PTE; in a
+      ``VM_UFFD_RWP`` VMA it indicates an RWP-protected PTE. WP and
+      RWP are mutually exclusive per VMA, so the meaning is
+      unambiguous. See Documentation/admin-guide/mm/userfaultfd.rst.
+    * Bit  58    pte is a guard region (since 6.15) (see madvise (2) man page)
+    * Bits 59-60 zero
+    * Bit  61    page is file-page or shared-anon (since 3.5)
+    * Bit  62    page swapped
+    * Bit  63    page present
+
+   Since Linux 4.0 only users with the CAP_SYS_ADMIN capability can get PFNs.
+   In 4.0 and 4.1 opens by unprivileged fail with -EPERM.  Starting from
+   4.2 the PFN field is zeroed if the user does not have CAP_SYS_ADMIN.
+   Reason: information about PFNs helps in exploiting Rowhammer vulnerability.
+
+   If the page is not present but in swap, then the PFN contains an
+   encoding of the swap file number and the page's offset into the
+   swap. Unmapped pages return a null PFN. This allows determining
+   precisely which pages are mapped (or in swap) and comparing mapped
+   pages between processes.
+
+   Traditionally, bit 56 indicates that a page is mapped exactly once and bit
+   56 is clear when a page is mapped multiple times, even when mapped in the
+   same process multiple times. In some kernel configurations, the semantics
+   for pages part of a larger allocation (e.g., THP) can differ: bit 56 is set
+   if all pages part of the corresponding large allocation are *certainly*
+   mapped in the same process, even if the page is mapped multiple times in that
+   process. Bit 56 is clear when any page page of the larger allocation
+   is *maybe* mapped in a different process. In some cases, a large allocation
+   might be treated as "maybe mapped by multiple processes" even though this
+   is no longer the case.
+
+   Efficient users of this interface will use ``/proc/pid/maps`` to
+   determine which areas of memory are actually mapped and llseek to
+   skip over unmapped regions.
+
+ * ``/proc/kpagecount``.  This file contains a 64-bit count of the number of
+   times each page is mapped, indexed by PFN. Some kernel configurations do
+   not track the precise number of times a page part of a larger allocation
+   (e.g., THP) is mapped. In these configurations, the average number of
+   mappings per page in this larger allocation is returned instead. However,
+   if any page of the large allocation is mapped, the returned value will
+   be at least 1.
+
+The page-types tool in the tools/mm directory can be used to query the
+number of times a page is mapped.
+
+ * ``/proc/kpageflags``.  This file contains a 64-bit set of flags for each
+   page, indexed by PFN.
+
+   The flags are (from ``include/uapi/linux/kernel-page-flags.h``):
+
+    0. LOCKED
+    1. ERROR
+    2. REFERENCED
+    3. UPTODATE
+    4. DIRTY
+    5. LRU
+    6. ACTIVE
+    7. SLAB
+    8. WRITEBACK
+    9. RECLAIM
+    10. BUDDY
+    11. MMAP
+    12. ANON
+    13. SWAPCACHE
+    14. SWAPBACKED
+    15. COMPOUND_HEAD
+    16. COMPOUND_TAIL
+    17. HUGE
+    18. UNEVICTABLE
+    19. HWPOISON
+    20. NOPAGE
+    21. KSM
+    22. THP
+    23. OFFLINE
+    24. ZERO_PAGE
+    25. IDLE
+    26. PGTABLE
+
+ * ``/proc/kpagecgroup``.  This file contains a 64-bit inode number of the
+   memory cgroup each page is charged to, indexed by PFN. Only available when
+   CONFIG_MEMCG is set.
+
+Short descriptions to the page flags
+====================================
+
+0 - LOCKED
+   The page is being locked for exclusive access, e.g. by undergoing read/write
+   IO.
+7 - SLAB
+   The page is managed by the SLAB/SLUB kernel memory allocator.
+   When compound page is used, either will only set this flag on the head
+   page.
+10 - BUDDY
+    A free memory block managed by the buddy system allocator.
+    The buddy system organizes free memory in blocks of various orders.
+    An order N block has 2^N physically contiguous pages, with the BUDDY flag
+    set for all pages.
+    Before 4.6 only the first page of the block had the flag set.
+15 - COMPOUND_HEAD
+    A compound page with order N consists of 2^N physically contiguous pages.
+    A compound page with order 2 takes the form of "HTTT", where H donates its
+    head page and T donates its tail page(s).  The major consumers of compound
+    pages are hugeTLB pages (Documentation/admin-guide/mm/hugetlbpage.rst),
+    the SLUB etc.  memory allocators and various device drivers.
+    However in this interface, only huge/giga pages are made visible
+    to end users.
+16 - COMPOUND_TAIL
+    A compound page tail (see description above).
+17 - HUGE
+    This is an integral part of a HugeTLB page.
+19 - HWPOISON
+    Hardware detected memory corruption on this page: don't touch the data!
+20 - NOPAGE
+    No page frame exists at the requested address.
+21 - KSM
+    Identical memory pages dynamically shared between one or more processes.
+22 - THP
+    Contiguous pages which construct THP of any size and mapped by any granularity.
+23 - OFFLINE
+    The page is logically offline.
+24 - ZERO_PAGE
+    Zero page for pfn_zero or huge_zero page.
+25 - IDLE
+    The page has not been accessed since it was marked idle (see
+    Documentation/admin-guide/mm/idle_page_tracking.rst).
+    Note that this flag may be stale in case the page was accessed via
+    a PTE. To make sure the flag is up-to-date one has to read
+    ``/sys/kernel/mm/page_idle/bitmap`` first.
+26 - PGTABLE
+    The page is in use as a page table.
+
+IO related page flags
+---------------------
+
+1 - ERROR
+   IO error occurred.
+3 - UPTODATE
+   The page has up-to-date data.
+   ie. for file backed page: (in-memory data revision >= on-disk one)
+4 - DIRTY
+   The page has been written to, hence contains new data.
+   i.e. for file backed page: (in-memory data revision >  on-disk one)
+8 - WRITEBACK
+   The page is being synced to disk.
+
+LRU related page flags
+----------------------
+
+5 - LRU
+   The page is in one of the LRU lists.
+6 - ACTIVE
+   The page is in the active LRU list.
+18 - UNEVICTABLE
+   The page is in the unevictable (non-)LRU list It is somehow pinned and
+   not a candidate for LRU page reclaims, e.g. ramfs pages,
+   shmctl(SHM_LOCK) and mlock() memory segments.
+2 - REFERENCED
+   The page has been referenced since last LRU list enqueue/requeue.
+9 - RECLAIM
+   The page will be reclaimed soon after its pageout IO completed.
+11 - MMAP
+   A memory mapped page.
+12 - ANON
+   A memory mapped page that is not part of a file.
+13 - SWAPCACHE
+   The page is mapped to swap space, i.e. has an associated swap entry.
+14 - SWAPBACKED
+   The page is backed by swap/RAM.
+
+The page-types tool in the tools/mm directory can be used to query the
+above flags.
+
+Exceptions for Shared Memory
+============================
+
+Page table entries for shared pages are cleared when the pages are zapped or
+swapped out. This makes swapped out pages indistinguishable from never-allocated
+ones.
+
+In kernel space, the swap location can still be retrieved from the page cache.
+However, values stored only on the normal PTE get lost irretrievably when the
+page is swapped out (i.e. SOFT_DIRTY).
+
+In user space, whether the page is present, swapped or none can be deduced with
+the help of lseek and/or mincore system calls.
+
+lseek() can differentiate between accessed pages (present or swapped out) and
+holes (none/non-allocated) by specifying the SEEK_DATA flag on the file where
+the pages are backed. For anonymous shared pages, the file can be found in
+``/proc/pid/map_files/``.
+
+mincore() can differentiate between pages in memory (present, including swap
+cache) and out of memory (swapped out or none/non-allocated).
+
+Other notes
+===========
+
+Reading from any of the files will return -EINVAL if you are not starting
+the read on an 8-byte boundary (e.g., if you sought an odd number of bytes
+into the file), or if the size of the read is not a multiple of 8 bytes.
+
+Before Linux 3.11 pagemap bits 55-60 were used for "page-shift" (which is
+always 12 at most architectures). Since Linux 3.11 their meaning changes
+after first clear of soft-dirty bits. Since Linux 4.2 they are used for
+flags unconditionally.
+
+Pagemap Scan IOCTL
+==================
+
+The ``PAGEMAP_SCAN`` IOCTL on the pagemap file can be used to get or optionally
+clear the info about page table entries. The following operations are supported
+in this IOCTL:
+
+- Scan the address range and get the memory ranges matching the provided criteria.
+  This is performed when the output buffer is specified.
+- Write-protect the pages. The ``PM_SCAN_WP_MATCHING`` is used to write-protect
+  the pages of interest. The ``PM_SCAN_CHECK_WPASYNC`` aborts the operation if
+  non-Async Write Protected pages are found. The ``PM_SCAN_WP_MATCHING`` can be
+  used with or without ``PM_SCAN_CHECK_WPASYNC``.
+- Both of those operations can be combined into one atomic operation where we can
+  get and write protect the pages as well.
+
+Following flags about pages are currently supported:
+
+- ``PAGE_IS_WPALLOWED`` - Page has async-write-protection enabled
+- ``PAGE_IS_WRITTEN`` - Page in a ``UFFDIO_REGISTER_MODE_WP`` VMA has been
+  written to since it was write-protected. Only reported inside such VMAs.
+- ``PAGE_IS_FILE`` - Page is file backed
+- ``PAGE_IS_PRESENT`` - Page is present in the memory
+- ``PAGE_IS_SWAPPED`` - Page is in swapped
+- ``PAGE_IS_PFNZERO`` - Page has zero PFN
+- ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed
+- ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty
+- ``PAGE_IS_GUARD`` - Page is a part of a guard region
+- ``PAGE_IS_ACCESSED`` - Page in a ``UFFDIO_REGISTER_MODE_RWP`` VMA has been
+  accessed since RWP was applied. Only reported inside such VMAs. See
+  Documentation/admin-guide/mm/userfaultfd.rst for the RWP workflow.
+
+The ``struct pm_scan_arg`` is used as the argument of the IOCTL.
+
+ 1. The size of the ``struct pm_scan_arg`` must be specified in the ``size``
+    field. This field will be helpful in recognizing the structure if extensions
+    are done later.
+ 2. The flags can be specified in the ``flags`` field. The ``PM_SCAN_WP_MATCHING``
+    and ``PM_SCAN_CHECK_WPASYNC`` are the only added flags at this time. The get
+    operation is optionally performed depending upon if the output buffer is
+    provided or not.
+ 3. The range is specified through ``start`` and ``end``.
+ 4. The walk can abort before visiting the complete range such as the user buffer
+    can get full etc. The walk ending address is specified in ``walk_end``.
+ 5. The output buffer of ``struct page_region`` array and size is specified in
+    ``vec`` and ``vec_len``.
+ 6. The optional maximum requested pages are specified in the ``max_pages``.
+ 7. The masks are specified in ``category_mask``, ``category_anyof_mask``,
+    ``category_inverted`` and ``return_mask``.
+
+Find pages which have been written and WP them as well::
+
+   struct pm_scan_arg arg = {
+   .size = sizeof(arg),
+   .flags = PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC,
+   ..
+   .category_mask = PAGE_IS_WRITTEN,
+   .return_mask = PAGE_IS_WRITTEN,
+   };
+
+Find pages which have been written, are file backed, not swapped and either
+present or huge::
+
+   struct pm_scan_arg arg = {
+   .size = sizeof(arg),
+   .flags = 0,
+   ..
+   .category_mask = PAGE_IS_WRITTEN | PAGE_IS_FILE,
+   .category_inverted = PAGE_IS_SWAPPED,
+   .category_anyof_mask = PAGE_IS_PRESENT | PAGE_IS_HUGE,
+   .return_mask = PAGE_IS_WRITTEN | PAGE_IS_SWAPPED |
+                  PAGE_IS_PRESENT | PAGE_IS_HUGE,
+   };
+
+The ``PAGE_IS_WRITTEN`` flag can be considered as a better-performing alternative
+of soft-dirty flag. It doesn't get affected by VMA merging of the kernel and hence
+the user can find the true soft-dirty pages in case of normal pages. (There may
+still be extra dirty pages reported for THP or Hugetlb pages.)
+
+"PAGE_IS_WRITTEN" category is used with uffd write protect-enabled ranges to
+implement memory dirty tracking in userspace:
+
+ 1. The userfaultfd file descriptor is created with ``userfaultfd`` syscall.
+ 2. The ``UFFD_FEATURE_WP_UNPOPULATED`` and ``UFFD_FEATURE_WP_ASYNC`` features
+    are set by ``UFFDIO_API`` IOCTL.
+ 3. The memory range is registered with ``UFFDIO_REGISTER_MODE_WP`` mode
+    through ``UFFDIO_REGISTER`` IOCTL.
+ 4. Then any part of the registered memory or the whole memory region must
+    be write protected using ``PAGEMAP_SCAN`` IOCTL with flag ``PM_SCAN_WP_MATCHING``
+    or the ``UFFDIO_WRITEPROTECT`` IOCTL can be used. Both of these perform the
+    same operation. The former is better in terms of performance.
+ 5. Now the ``PAGEMAP_SCAN`` IOCTL can be used to either just find pages which
+    have been written to since they were last marked and/or optionally write protect
+    the pages as well.
diff --git a/Documentation/admin-guide/mm/shrinker_debugfs.rst b/Documentation/admin-guide/mm/shrinker_debugfs.rst
new file mode 100644
index 000000000..c582033bd
--- /dev/null
+++ b/Documentation/admin-guide/mm/shrinker_debugfs.rst
@@ -0,0 +1,133 @@
+==========================
+Shrinker Debugfs Interface
+==========================
+
+Shrinker debugfs interface provides a visibility into the kernel memory
+shrinkers subsystem and allows to get information about individual shrinkers
+and interact with them.
+
+For each shrinker registered in the system a directory in **<debugfs>/shrinker/**
+is created. The directory's name is composed from the shrinker's name and an
+unique id: e.g. *kfree_rcu-0* or *sb-xfs:vda1-36*.
+
+Each shrinker directory contains **count** and **scan** files, which allow to
+trigger *count_objects()* and *scan_objects()* callbacks for each memcg and
+numa node (if applicable).
+
+Usage:
+------
+
+1. *List registered shrinkers*
+
+  ::
+
+    $ cd /sys/kernel/debug/shrinker/
+    $ ls
+    dquota-cache-16     sb-devpts-28     sb-proc-47       sb-tmpfs-42
+    mm-shadow-18        sb-devtmpfs-5    sb-proc-48       sb-tmpfs-43
+    mm-zspool:zram0-34  sb-hugetlbfs-17  sb-pstore-31     sb-tmpfs-44
+    rcu-kfree-0         sb-hugetlbfs-33  sb-rootfs-2      sb-tmpfs-49
+    sb-aio-20           sb-iomem-12      sb-securityfs-6  sb-tracefs-13
+    sb-anon_inodefs-15  sb-mqueue-21     sb-selinuxfs-22  sb-xfs:vda1-36
+    sb-bdev-3           sb-nsfs-4        sb-sockfs-8      sb-zsmalloc-19
+    sb-bpf-32           sb-pipefs-14     sb-sysfs-26      thp-deferred_split-10
+    sb-btrfs:vda2-24    sb-proc-25       sb-tmpfs-1       thp-zero-9
+    sb-cgroup2-30       sb-proc-39       sb-tmpfs-27      xfs-buf:vda1-37
+    sb-configfs-23      sb-proc-41       sb-tmpfs-29      xfs-inodegc:vda1-38
+    sb-dax-11           sb-proc-45       sb-tmpfs-35
+    sb-debugfs-7        sb-proc-46       sb-tmpfs-40
+
+2. *Get information about a specific shrinker*
+
+  ::
+
+    $ cd sb-btrfs\:vda2-24/
+    $ ls
+    count            scan
+
+3. *Count objects*
+
+  Each line in the output has the following format::
+
+    <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1> ...
+    <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1> ...
+    ...
+
+  If there are no objects on all numa nodes, a line is omitted. If there
+  are no objects at all, the output might be empty.
+
+  If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed
+  as cgroup inode id. If the shrinker is not numa-aware, 0's are printed
+  for all nodes except the first one.
+  ::
+
+    $ cat count
+    1 224 2
+    21 98 0
+    55 818 10
+    2367 2 0
+    2401 30 0
+    225 13 0
+    599 35 0
+    939 124 0
+    1041 3 0
+    1075 1 0
+    1109 1 0
+    1279 60 0
+    1313 7 0
+    1347 39 0
+    1381 3 0
+    1449 14 0
+    1483 63 0
+    1517 53 0
+    1551 6 0
+    1585 1 0
+    1619 6 0
+    1653 40 0
+    1687 11 0
+    1721 8 0
+    1755 4 0
+    1789 52 0
+    1823 888 0
+    1857 1 0
+    1925 2 0
+    1959 32 0
+    2027 22 0
+    2061 9 0
+    2469 799 0
+    2537 861 0
+    2639 1 0
+    2707 70 0
+    2775 4 0
+    2877 84 0
+    293 1 0
+    735 8 0
+
+4. *Scan objects*
+
+  The expected input format::
+
+    <cgroup inode id> <numa id> <number of objects to scan>
+
+  For a non-memcg-aware shrinker or on a system with no memory
+  cgrups **0** should be passed as cgroup id.
+  ::
+
+    $ cd /sys/kernel/debug/shrinker/
+    $ cd sb-btrfs\:vda2-24/
+
+    $ cat count | head -n 5
+    1 212 0
+    21 97 0
+    55 802 5
+    2367 2 0
+    225 13 0
+
+    $ echo "55 0 200" > scan
+
+    $ cat count | head -n 5
+    1 212 0
+    21 96 0
+    55 752 5
+    2367 2 0
+    225 13 0
diff --git a/Documentation/admin-guide/mm/slab.rst b/Documentation/admin-guide/mm/slab.rst
new file mode 100644
index 000000000..14429ab90
--- /dev/null
+++ b/Documentation/admin-guide/mm/slab.rst
@@ -0,0 +1,469 @@
+========================================
+Short users guide for the slab allocator
+========================================
+
+The slab allocator includes full debugging support (when built with
+CONFIG_SLUB_DEBUG=y) but it is off by default (unless built with
+CONFIG_SLUB_DEBUG_ON=y).  You can enable debugging only for selected
+slabs in order to avoid an impact on overall system performance which
+may make a bug more difficult to find.
+
+In order to switch debugging on one can add an option ``slab_debug``
+to the kernel command line. That will enable full debugging for
+all slabs.
+
+Typically one would then use the ``slabinfo`` command to get statistical
+data and perform operation on the slabs. By default ``slabinfo`` only lists
+slabs that have data in them. See "slabinfo -h" for more options when
+running the command. ``slabinfo`` can be compiled with
+::
+
+	gcc -o slabinfo tools/mm/slabinfo.c
+
+Some of the modes of operation of ``slabinfo`` require that slub debugging
+be enabled on the command line. F.e. no tracking information will be
+available without debugging on and validation can only partially
+be performed if debugging was not switched on.
+
+Some more sophisticated uses of slab_debug:
+-------------------------------------------
+
+Parameters may be given to ``slab_debug``. If none is specified then full
+debugging is enabled. Format:
+
+slab_debug=<Debug-Options>
+	Enable options for all slabs
+
+slab_debug=<Debug-Options>,<slab name1>,<slab name2>,...
+	Enable options only for select slabs (no spaces
+	after a comma)
+
+Multiple blocks of options for all slabs or selected slabs can be given, with
+blocks of options delimited by ';'. The last of "all slabs" blocks is applied
+to all slabs except those that match one of the "select slabs" block. Options
+of the first "select slabs" blocks that matches the slab's name are applied.
+
+Possible debug options are::
+
+	F		Sanity checks on (enables SLAB_DEBUG_CONSISTENCY_CHECKS
+			Sorry SLAB legacy issues)
+	Z		Red zoning
+	P		Poisoning (object and padding)
+	U		User tracking (free and alloc)
+	T		Trace (please only use on single slabs)
+	A		Enable failslab filter mark for the cache
+	O		Switch debugging off for caches that would have
+			caused higher minimum slab orders
+	-		Switch all debugging off (useful if the kernel is
+			configured with CONFIG_SLUB_DEBUG_ON)
+
+F.e. in order to boot just with sanity checks and red zoning one would specify::
+
+	slab_debug=FZ
+
+Trying to find an issue in the dentry cache? Try::
+
+	slab_debug=,dentry
+
+to only enable debugging on the dentry cache.  You may use an asterisk at the
+end of the slab name, in order to cover all slabs with the same prefix.  For
+example, here's how you can poison the dentry cache as well as all kmalloc
+slabs::
+
+	slab_debug=P,kmalloc-*,dentry
+
+Red zoning and tracking may realign the slab.  We can just apply sanity checks
+to the dentry cache with::
+
+	slab_debug=F,dentry
+
+Debugging options may require the minimum possible slab order to increase as
+a result of storing the metadata (for example, caches with PAGE_SIZE object
+sizes).  This has a higher likelihood of resulting in slab allocation errors
+in low memory situations or if there's high fragmentation of memory.  To
+switch off debugging for such caches by default, use::
+
+	slab_debug=O
+
+You can apply different options to different list of slab names, using blocks
+of options. This will enable red zoning for dentry and user tracking for
+kmalloc. All other slabs will not get any debugging enabled::
+
+	slab_debug=Z,dentry;U,kmalloc-*
+
+You can also enable options (e.g. sanity checks and poisoning) for all caches
+except some that are deemed too performance critical and don't need to be
+debugged by specifying global debug options followed by a list of slab names
+with "-" as options::
+
+	slab_debug=FZ;-,zs_handle,zspage
+
+The state of each debug option for a slab can be found in the respective files
+under::
+
+	/sys/kernel/slab/<slab name>/
+
+If the file contains 1, the option is enabled, 0 means disabled. The debug
+options from the ``slab_debug`` parameter translate to the following files::
+
+	F	sanity_checks
+	Z	red_zone
+	P	poison
+	U	store_user
+	T	trace
+	A	failslab
+
+failslab file is writable, so writing 1 or 0 will enable or disable
+the option at runtime. Write returns -EINVAL if cache is an alias.
+Careful with tracing: It may spew out lots of information and never stop if
+used on the wrong slab.
+
+Slab merging
+============
+
+If no debug options are specified then SLUB may merge similar slabs together
+in order to reduce overhead and increase cache hotness of objects.
+``slabinfo -a`` displays which slabs were merged together.
+
+Slab validation
+===============
+
+SLUB can validate all object if the kernel was booted with slab_debug. In
+order to do so you must have the ``slabinfo`` tool. Then you can do
+::
+
+	slabinfo -v
+
+which will test all objects. Output will be generated to the syslog.
+
+This also works in a more limited way if boot was without slab debug.
+In that case ``slabinfo -v`` simply tests all reachable objects. Usually
+these are in the cpu slabs and the partial slabs. Full slabs are not
+tracked by SLUB in a non debug situation.
+
+Getting more performance
+========================
+
+To some degree SLUB's performance is limited by the need to take the
+list_lock once in a while to deal with partial slabs. That overhead is
+governed by the order of the allocation for each slab. The allocations
+can be influenced by kernel parameters:
+
+.. slab_min_objects=x		(default: automatically scaled by number of cpus)
+.. slab_min_order=x		(default 0)
+.. slab_max_order=x		(default 3 (PAGE_ALLOC_COSTLY_ORDER))
+
+``slab_min_objects``
+	allows to specify how many objects must at least fit into one
+	slab in order for the allocation order to be acceptable.  In
+	general slub will be able to perform this number of
+	allocations on a slab without consulting centralized resources
+	(list_lock) where contention may occur.
+
+``slab_min_order``
+	specifies a minimum order of slabs. A similar effect like
+	``slab_min_objects``.
+
+``slab_max_order``
+	specified the order at which ``slab_min_objects`` should no
+	longer be checked. This is useful to avoid SLUB trying to
+	generate super large order pages to fit ``slab_min_objects``
+	of a slab cache with large object sizes into one high order
+	page. Setting command line parameter
+	``debug_guardpage_minorder=N`` (N > 0), forces setting
+	``slab_max_order`` to 0, what cause minimum possible order of
+	slabs allocation.
+
+``slab_strict_numa``
+        Enables the application of memory policies on each
+        allocation. This results in more accurate placement of
+        objects which may result in the reduction of accesses
+        to remote nodes. The default is to only apply memory
+        policies at the folio level when a new folio is acquired
+        or a folio is retrieved from the lists. Enabling this
+        option reduces the fastpath performance of the slab allocator.
+
+SLUB Debug output
+=================
+
+Here is a sample of slub debug output::
+
+ ====================================================================
+ BUG kmalloc-8: Right Redzone overwritten
+ --------------------------------------------------------------------
+
+ INFO: 0xc90f6d28-0xc90f6d2b. First byte 0x00 instead of 0xcc
+ INFO: Slab 0xc528c530 flags=0x400000c3 inuse=61 fp=0xc90f6d58
+ INFO: Object 0xc90f6d20 @offset=3360 fp=0xc90f6d58
+ INFO: Allocated in get_modalias+0x61/0xf5 age=53 cpu=1 pid=554
+
+ Bytes b4 (0xc90f6d10): 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
+ Object   (0xc90f6d20): 31 30 31 39 2e 30 30 35                         1019.005
+ Redzone  (0xc90f6d28): 00 cc cc cc                                     .
+ Padding  (0xc90f6d50): 5a 5a 5a 5a 5a 5a 5a 5a                         ZZZZZZZZ
+
+   [<c010523d>] dump_trace+0x63/0x1eb
+   [<c01053df>] show_trace_log_lvl+0x1a/0x2f
+   [<c010601d>] show_trace+0x12/0x14
+   [<c0106035>] dump_stack+0x16/0x18
+   [<c017e0fa>] object_err+0x143/0x14b
+   [<c017e2cc>] check_object+0x66/0x234
+   [<c017eb43>] __slab_free+0x239/0x384
+   [<c017f446>] kfree+0xa6/0xc6
+   [<c02e2335>] get_modalias+0xb9/0xf5
+   [<c02e23b7>] dmi_dev_uevent+0x27/0x3c
+   [<c027866a>] dev_uevent+0x1ad/0x1da
+   [<c0205024>] kobject_uevent_env+0x20a/0x45b
+   [<c020527f>] kobject_uevent+0xa/0xf
+   [<c02779f1>] store_uevent+0x4f/0x58
+   [<c027758e>] dev_attr_store+0x29/0x2f
+   [<c01bec4f>] sysfs_write_file+0x16e/0x19c
+   [<c0183ba7>] vfs_write+0xd1/0x15a
+   [<c01841d7>] sys_write+0x3d/0x72
+   [<c0104112>] sysenter_past_esp+0x5f/0x99
+   [<b7f7b410>] 0xb7f7b410
+   =======================
+
+ FIX kmalloc-8: Restoring Redzone 0xc90f6d28-0xc90f6d2b=0xcc
+
+If SLUB encounters a corrupted object (full detection requires the kernel
+to be booted with slab_debug) then the following output will be dumped
+into the syslog:
+
+1. Description of the problem encountered
+
+   This will be a message in the system log starting with::
+
+     ===============================================
+     BUG <slab cache affected>: <What went wrong>
+     -----------------------------------------------
+
+     INFO: <corruption start>-<corruption_end> <more info>
+     INFO: Slab <address> <slab information>
+     INFO: Object <address> <object information>
+     INFO: Allocated in <kernel function> age=<jiffies since alloc> cpu=<allocated by
+	cpu> pid=<pid of the process>
+     INFO: Freed in <kernel function> age=<jiffies since free> cpu=<freed by cpu>
+	pid=<pid of the process>
+
+   (Object allocation / free information is only available if SLAB_STORE_USER is
+   set for the slab. slab_debug sets that option)
+
+2. The object contents if an object was involved.
+
+   Various types of lines can follow the BUG SLUB line:
+
+   Bytes b4 <address> : <bytes>
+	Shows a few bytes before the object where the problem was detected.
+	Can be useful if the corruption does not stop with the start of the
+	object.
+
+   Object <address> : <bytes>
+	The bytes of the object. If the object is inactive then the bytes
+	typically contain poison values. Any non-poison value shows a
+	corruption by a write after free.
+
+   Redzone <address> : <bytes>
+	The Redzone following the object. The Redzone is used to detect
+	writes after the object. All bytes should always have the same
+	value. If there is any deviation then it is due to a write after
+	the object boundary.
+
+	(Redzone information is only available if SLAB_RED_ZONE is set.
+	slab_debug sets that option)
+
+   Padding <address> : <bytes>
+	Unused data to fill up the space in order to get the next object
+	properly aligned. In the debug case we make sure that there are
+	at least 4 bytes of padding. This allows the detection of writes
+	before the object.
+
+3. A stackdump
+
+   The stackdump describes the location where the error was detected. The cause
+   of the corruption is may be more likely found by looking at the function that
+   allocated or freed the object.
+
+4. Report on how the problem was dealt with in order to ensure the continued
+   operation of the system.
+
+   These are messages in the system log beginning with::
+
+	FIX <slab cache affected>: <corrective action taken>
+
+   In the above sample SLUB found that the Redzone of an active object has
+   been overwritten. Here a string of 8 characters was written into a slab that
+   has the length of 8 characters. However, a 8 character string needs a
+   terminating 0. That zero has overwritten the first byte of the Redzone field.
+   After reporting the details of the issue encountered the FIX SLUB message
+   tells us that SLUB has restored the Redzone to its proper value and then
+   system operations continue.
+
+Emergency operations
+====================
+
+Minimal debugging (sanity checks alone) can be enabled by booting with::
+
+	slab_debug=F
+
+This will be generally be enough to enable the resiliency features of slub
+which will keep the system running even if a bad kernel component will
+keep corrupting objects. This may be important for production systems.
+Performance will be impacted by the sanity checks and there will be a
+continual stream of error messages to the syslog but no additional memory
+will be used (unlike full debugging).
+
+No guarantees. The kernel component still needs to be fixed. Performance
+may be optimized further by locating the slab that experiences corruption
+and enabling debugging only for that cache
+
+I.e.::
+
+	slab_debug=F,dentry
+
+If the corruption occurs by writing after the end of the object then it
+may be advisable to enable a Redzone to avoid corrupting the beginning
+of other objects::
+
+	slab_debug=FZ,dentry
+
+Extended slabinfo mode and plotting
+===================================
+
+The ``slabinfo`` tool has a special 'extended' ('-X') mode that includes:
+ - Slabcache Totals
+ - Slabs sorted by size (up to -N <num> slabs, default 1)
+ - Slabs sorted by loss (up to -N <num> slabs, default 1)
+
+Additionally, in this mode ``slabinfo`` does not dynamically scale
+sizes (G/M/K) and reports everything in bytes (this functionality is
+also available to other slabinfo modes via '-B' option) which makes
+reporting more precise and accurate. Moreover, in some sense the `-X'
+mode also simplifies the analysis of slabs' behaviour, because its
+output can be plotted using the ``slabinfo-gnuplot.sh`` script. So it
+pushes the analysis from looking through the numbers (tons of numbers)
+to something easier -- visual analysis.
+
+To generate plots:
+
+a) collect slabinfo extended records, for example::
+
+	while [ 1 ]; do slabinfo -X >> FOO_STATS; sleep 1; done
+
+b) pass stats file(-s) to ``slabinfo-gnuplot.sh`` script::
+
+	slabinfo-gnuplot.sh FOO_STATS [FOO_STATS2 .. FOO_STATSN]
+
+   The ``slabinfo-gnuplot.sh`` script will pre-processes the collected records
+   and generates 3 png files (and 3 pre-processing cache files) per STATS
+   file:
+   - Slabcache Totals: FOO_STATS-totals.png
+   - Slabs sorted by size: FOO_STATS-slabs-by-size.png
+   - Slabs sorted by loss: FOO_STATS-slabs-by-loss.png
+
+Another use case, when ``slabinfo-gnuplot.sh`` can be useful, is when you
+need to compare slabs' behaviour "prior to" and "after" some code
+modification.  To help you out there, ``slabinfo-gnuplot.sh`` script
+can 'merge' the `Slabcache Totals` sections from different
+measurements. To visually compare N plots:
+
+a) Collect as many STATS1, STATS2, .. STATSN files as you need::
+
+	while [ 1 ]; do slabinfo -X >> STATS<X>; sleep 1; done
+
+b) Pre-process those STATS files::
+
+	slabinfo-gnuplot.sh STATS1 STATS2 .. STATSN
+
+c) Execute ``slabinfo-gnuplot.sh`` in '-t' mode, passing all of the
+   generated pre-processed \*-totals::
+
+	slabinfo-gnuplot.sh -t STATS1-totals STATS2-totals .. STATSN-totals
+
+   This will produce a single plot (png file).
+
+   Plots, expectedly, can be large so some fluctuations or small spikes
+   can go unnoticed. To deal with that, ``slabinfo-gnuplot.sh`` has two
+   options to 'zoom-in'/'zoom-out':
+
+   a) ``-s %d,%d`` -- overwrites the default image width and height
+   b) ``-r %d,%d`` -- specifies a range of samples to use (for example,
+      in ``slabinfo -X >> FOO_STATS; sleep 1;`` case, using a ``-r
+      40,60`` range will plot only samples collected between 40th and
+      60th seconds).
+
+
+DebugFS files for SLUB
+======================
+
+For more information about current state of SLUB caches with the user tracking
+debug option enabled, debugfs files are available, typically under
+/sys/kernel/debug/slab/<cache>/ (created only for caches with enabled user
+tracking). There are 2 types of these files with the following debug
+information:
+
+1. alloc_traces::
+
+    Prints information about unique allocation traces of the currently
+    allocated objects. The output is sorted by frequency of each trace.
+
+    Information in the output:
+    Number of objects, allocating function, possible memory wastage of
+    kmalloc objects(total/per-object), minimal/average/maximal jiffies
+    since alloc, pid range of the allocating processes, cpu mask of
+    allocating cpus, numa node mask of origins of memory, and stack trace.
+
+    Example:::
+
+    338 pci_alloc_dev+0x2c/0xa0 waste=521872/1544 age=290837/291891/293509 pid=1 cpus=106 nodes=0-1
+        __kmem_cache_alloc_node+0x11f/0x4e0
+        kmalloc_trace+0x26/0xa0
+        pci_alloc_dev+0x2c/0xa0
+        pci_scan_single_device+0xd2/0x150
+        pci_scan_slot+0xf7/0x2d0
+        pci_scan_child_bus_extend+0x4e/0x360
+        acpi_pci_root_create+0x32e/0x3b0
+        pci_acpi_scan_root+0x2b9/0x2d0
+        acpi_pci_root_add.cold.11+0x110/0xb0a
+        acpi_bus_attach+0x262/0x3f0
+        device_for_each_child+0xb7/0x110
+        acpi_dev_for_each_child+0x77/0xa0
+        acpi_bus_attach+0x108/0x3f0
+        device_for_each_child+0xb7/0x110
+        acpi_dev_for_each_child+0x77/0xa0
+        acpi_bus_attach+0x108/0x3f0
+
+2. free_traces::
+
+    Prints information about unique freeing traces of the currently allocated
+    objects. The freeing traces thus come from the previous life-cycle of the
+    objects and are reported as not available for objects allocated for the first
+    time. The output is sorted by frequency of each trace.
+
+    Information in the output:
+    Number of objects, freeing function, minimal/average/maximal jiffies since free,
+    pid range of the freeing processes, cpu mask of freeing cpus, and stack trace.
+
+    Example:::
+
+    1980 <not-available> age=4294912290 pid=0 cpus=0
+    51 acpi_ut_update_ref_count+0x6a6/0x782 age=236886/237027/237772 pid=1 cpus=1
+	kfree+0x2db/0x420
+	acpi_ut_update_ref_count+0x6a6/0x782
+	acpi_ut_update_object_reference+0x1ad/0x234
+	acpi_ut_remove_reference+0x7d/0x84
+	acpi_rs_get_prt_method_data+0x97/0xd6
+	acpi_get_irq_routing_table+0x82/0xc4
+	acpi_pci_irq_find_prt_entry+0x8e/0x2e0
+	acpi_pci_irq_lookup+0x3a/0x1e0
+	acpi_pci_irq_enable+0x77/0x240
+	pcibios_enable_device+0x39/0x40
+	do_pci_enable_device.part.0+0x5d/0xe0
+	pci_enable_device_flags+0xfc/0x120
+	pci_enable_device+0x13/0x20
+	virtio_pci_probe+0x9e/0x170
+	local_pci_probe+0x48/0x80
+	pci_device_probe+0x105/0x1c0
+
+Christoph Lameter, May 30, 2007
+Sergey Senozhatsky, October 23, 2015
diff --git a/Documentation/admin-guide/mm/soft-dirty.rst b/Documentation/admin-guide/mm/soft-dirty.rst
new file mode 100644
index 000000000..aeea936ca
--- /dev/null
+++ b/Documentation/admin-guide/mm/soft-dirty.rst
@@ -0,0 +1,45 @@
+===============
+Soft-Dirty PTEs
+===============
+
+The soft-dirty is a bit on a PTE which helps to track which pages a task
+writes to. In order to do this tracking one should
+
+  1. Clear soft-dirty bits from the task's PTEs.
+
+     This is done by writing "4" into the ``/proc/PID/clear_refs`` file of the
+     task in question.
+
+  2. Wait some time.
+
+  3. Read soft-dirty bits from the PTEs.
+
+     This is done by reading from the ``/proc/PID/pagemap``. The bit 55 of the
+     64-bit qword is the soft-dirty one. If set, the respective PTE was
+     written to since step 1.
+
+
+Internally, to do this tracking, the writable bit is cleared from PTEs
+when the soft-dirty bit is cleared. So, after this, when the task tries to
+modify a page at some virtual address the #PF occurs and the kernel sets
+the soft-dirty bit on the respective PTE.
+
+Note, that although all the task's address space is marked as r/o after the
+soft-dirty bits clear, the #PF-s that occur after that are processed fast.
+This is so, since the pages are still mapped to physical memory, and thus all
+the kernel does is finds this fact out and puts both writable and soft-dirty
+bits on the PTE.
+
+While in most cases tracking memory changes by #PF-s is more than enough
+there is still a scenario when we can lose soft dirty bits -- a task
+unmaps a previously mapped memory region and then maps a new one at exactly
+the same place. When unmap is called, the kernel internally clears PTE values
+including soft dirty bits. To notify user space application about such
+memory region renewal the kernel always marks new memory regions (and
+expanded regions) as soft dirty.
+
+This feature is actively used by the checkpoint-restore project. You
+can find more details about it on http://criu.org
+
+
+-- Pavel Emelyanov, Apr 9, 2013
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
new file mode 100644
index 000000000..b187d6184
--- /dev/null
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -0,0 +1,784 @@
+============================
+Transparent Hugepage Support
+============================
+
+Objective
+=========
+
+Performance critical computing applications dealing with large memory
+working sets are already running on top of libhugetlbfs and in turn
+hugetlbfs. Transparent HugePage Support (THP) is an alternative mean of
+using huge pages for the backing of virtual memory with huge pages
+that supports the automatic promotion and demotion of page sizes and
+without the shortcomings of hugetlbfs.
+
+Currently THP only works for anonymous memory mappings and tmpfs/shmem.
+But in the future it can expand to other filesystems.
+
+.. note::
+   in the examples below we presume that the basic page size is 4K and
+   the huge page size is 2M, although the actual numbers may vary
+   depending on the CPU architecture.
+
+The reason applications are running faster is because of two
+factors. The first factor is almost completely irrelevant and it's not
+of significant interest because it'll also have the downside of
+requiring larger clear-page copy-page in page faults which is a
+potentially negative effect. The first factor consists in taking a
+single page fault for each 2M virtual region touched by userland (so
+reducing the enter/exit kernel frequency by a 512 times factor). This
+only matters the first time the memory is accessed for the lifetime of
+a memory mapping. The second long lasting and much more important
+factor will affect all subsequent accesses to the memory for the whole
+runtime of the application. The second factor consist of two
+components:
+
+1) the TLB miss will run faster (especially with virtualization using
+   nested pagetables but almost always also on bare metal without
+   virtualization)
+
+2) a single TLB entry will be mapping a much larger amount of virtual
+   memory in turn reducing the number of TLB misses. With
+   virtualization and nested pagetables the TLB can be mapped of
+   larger size only if both KVM and the Linux guest are using
+   hugepages but a significant speedup already happens if only one of
+   the two is using hugepages just because of the fact the TLB miss is
+   going to run faster.
+
+Modern kernels support "multi-size THP" (mTHP), which introduces the
+ability to allocate memory in blocks that are bigger than a base page
+but smaller than traditional PMD-size (as described above), in
+increments of a power-of-2 number of pages. mTHP can back anonymous
+memory (for example 16K, 32K, 64K, etc). These THPs continue to be
+PTE-mapped, but in many cases can still provide similar benefits to
+those outlined above: Page faults are significantly reduced (by a
+factor of e.g. 4, 8, 16, etc), but latency spikes are much less
+prominent because the size of each page isn't as huge as the PMD-sized
+variant and there is less memory to clear in each page fault. Some
+architectures also employ TLB compression mechanisms to squeeze more
+entries in when a set of PTEs are virtually and physically contiguous
+and appropriately aligned. In this case, TLB misses will occur less
+often.
+
+THP can be enabled system wide or restricted to certain tasks or even
+memory ranges inside task's address space. Unless THP is completely
+disabled, there is ``khugepaged`` daemon that scans memory and
+collapses sequences of basic pages into huge pages of either PMD size
+or mTHP sizes, if the system is configured to do so.
+
+The THP behaviour is controlled via :ref:`sysfs <thp_sysfs>`
+interface and using madvise(2) and prctl(2) system calls.
+
+Transparent Hugepage Support maximizes the usefulness of free memory
+if compared to the reservation approach of hugetlbfs by allowing all
+unused memory to be used as cache or other movable (or even unmovable
+entities). It doesn't require reservation to prevent hugepage
+allocation failures to be noticeable from userland. It allows paging
+and all other advanced VM features to be available on the
+hugepages. It requires no modifications for applications to take
+advantage of it.
+
+Applications however can be further optimized to take advantage of
+this feature, like for example they've been optimized before to avoid
+a flood of mmap system calls for every malloc(4k). Optimizing userland
+is by far not mandatory and khugepaged already can take care of long
+lived page allocations even for hugepage unaware applications that
+deals with large amounts of memory.
+
+In certain cases when hugepages are enabled system wide, application
+may end up allocating more memory resources. An application may mmap a
+large region but only touch 1 byte of it, in that case a 2M page might
+be allocated instead of a 4k page for no good. This is why it's
+possible to disable hugepages system-wide and to only have them inside
+MADV_HUGEPAGE madvise regions.
+
+Embedded systems should enable hugepages only inside madvise regions
+to eliminate any risk of wasting any precious byte of memory and to
+only run faster.
+
+Applications that gets a lot of benefit from hugepages and that don't
+risk to lose memory by using hugepages, should use
+madvise(MADV_HUGEPAGE) on their critical mmapped regions.
+
+.. _thp_sysfs:
+
+sysfs
+=====
+
+Global THP controls
+-------------------
+
+Transparent Hugepage Support for anonymous memory can be disabled
+(mostly for debugging purposes) or only enabled inside MADV_HUGEPAGE
+regions (to avoid the risk of consuming more memory resources) or enabled
+system wide. This can be achieved per-supported-THP-size with one of::
+
+	echo always >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+	echo madvise >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+	echo never >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+
+where <size> is the hugepage size being addressed, the available sizes
+for which vary by system.
+
+.. note:: Setting "never" in all sysfs THP controls does **not** disable
+          Transparent Huge Pages globally. This is because ``madvise(...,
+          MADV_COLLAPSE)`` ignores these settings and collapses ranges to
+          PMD-sized huge pages unconditionally.
+
+For example::
+
+	echo always >/sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled
+
+Alternatively it is possible to specify that a given hugepage size
+will inherit the top-level "enabled" value::
+
+	echo inherit >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+
+For example::
+
+	echo inherit >/sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled
+
+The top-level setting (for use with "inherit") can be set by issuing
+one of the following commands::
+
+	echo always >/sys/kernel/mm/transparent_hugepage/enabled
+	echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
+	echo never >/sys/kernel/mm/transparent_hugepage/enabled
+
+By default, PMD-sized hugepages have enabled="inherit" and all other
+hugepage sizes have enabled="never". If enabling multiple hugepage
+sizes, the kernel will select the most appropriate enabled size for a
+given allocation.
+
+It's also possible to limit defrag efforts in the VM to generate
+anonymous hugepages in case they're not immediately free to madvise
+regions or to never try to defrag memory and simply fallback to regular
+pages unless hugepages are immediately available. Clearly if we spend CPU
+time to defrag memory, we would expect to gain even more by the fact we
+use hugepages later instead of regular pages. This isn't always
+guaranteed, but it may be more likely in case the allocation is for a
+MADV_HUGEPAGE region.
+
+::
+
+	echo always >/sys/kernel/mm/transparent_hugepage/defrag
+	echo defer >/sys/kernel/mm/transparent_hugepage/defrag
+	echo defer+madvise >/sys/kernel/mm/transparent_hugepage/defrag
+	echo madvise >/sys/kernel/mm/transparent_hugepage/defrag
+	echo never >/sys/kernel/mm/transparent_hugepage/defrag
+
+always
+	means that an application requesting THP will stall on
+	allocation failure and directly reclaim pages and compact
+	memory in an effort to allocate a THP immediately. This may be
+	desirable for virtual machines that benefit heavily from THP
+	use and are willing to delay the VM start to utilise them.
+
+defer
+	means that an application will wake kswapd in the background
+	to reclaim pages and wake kcompactd to compact memory so that
+	THP is available in the near future. It's the responsibility
+	of khugepaged to then install the THP pages later.
+
+defer+madvise
+	will enter direct reclaim and compaction like ``always``, but
+	only for regions that have used madvise(MADV_HUGEPAGE); all
+	other regions will wake kswapd in the background to reclaim
+	pages and wake kcompactd to compact memory so that THP is
+	available in the near future.
+
+madvise
+	will enter direct reclaim like ``always`` but only for regions
+	that are have used madvise(MADV_HUGEPAGE). This is the default
+	behaviour.
+
+never
+	should be self-explanatory. Note that ``madvise(...,
+	MADV_COLLAPSE)`` can still cause transparent huge pages to be
+	obtained even if this mode is specified everywhere.
+
+By default kernel tries to use huge, PMD-mappable zero page on read
+page fault to anonymous mapping. It's possible to disable huge zero
+page by writing 0 or enable it back by writing 1::
+
+	echo 0 >/sys/kernel/mm/transparent_hugepage/use_zero_page
+	echo 1 >/sys/kernel/mm/transparent_hugepage/use_zero_page
+
+Some userspace (such as a test program, or an optimized memory
+allocation library) may want to know the size (in bytes) of a
+PMD-mappable transparent hugepage::
+
+	cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
+
+All THPs at fault and collapse time will be added to _deferred_list,
+and will therefore be split under memory pressure if they are considered
+"underused". A THP is underused if the number of zero-filled pages in
+the THP is above max_ptes_none (see below). It is possible to disable
+this behaviour by writing 0 to shrink_underused, and enable it by writing
+1 to it::
+
+	echo 0 > /sys/kernel/mm/transparent_hugepage/shrink_underused
+	echo 1 > /sys/kernel/mm/transparent_hugepage/shrink_underused
+
+khugepaged will be automatically started when any THP size is enabled
+(either of the per-size anon control or the top-level control are set
+to "always" or "madvise"), and it'll be automatically shutdown when
+all THP sizes are disabled (when both the per-size anon control and the
+top-level control are "never").
+
+process THP controls
+--------------------
+
+A process can control its own THP behaviour using the ``PR_SET_THP_DISABLE``
+and ``PR_GET_THP_DISABLE`` pair of prctl(2) calls. The THP behaviour set using
+``PR_SET_THP_DISABLE`` is inherited across fork(2) and execve(2). These calls
+support the following arguments::
+
+	prctl(PR_SET_THP_DISABLE, 1, 0, 0, 0):
+		This will disable THPs completely for the process, irrespective
+		of global THP controls or madvise(..., MADV_COLLAPSE) being used.
+
+	prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, 0, 0):
+		This will disable THPs for the process except when the usage of THPs is
+		advised. Consequently, THPs will only be used when:
+		- Global THP controls are set to "always" or "madvise" and
+		  madvise(..., MADV_HUGEPAGE) or madvise(..., MADV_COLLAPSE) is used.
+		- Global THP controls are set to "never" and madvise(..., MADV_COLLAPSE)
+		  is used. This is the same behavior as if THPs would not be disabled on
+		  a process level.
+		Note that MADV_COLLAPSE is currently always rejected if
+		madvise(..., MADV_NOHUGEPAGE) is set on an area.
+
+	prctl(PR_SET_THP_DISABLE, 0, 0, 0, 0):
+		This will re-enable THPs for the process, as if they were never disabled.
+		Whether THPs will actually be used depends on global THP controls and
+		madvise() calls.
+
+	prctl(PR_GET_THP_DISABLE, 0, 0, 0, 0):
+		This returns a value whose bits indicate how THP-disable is configured:
+		Bits
+		 1 0  Value  Description
+		|0|0|   0    No THP-disable behaviour specified.
+		|0|1|   1    THP is entirely disabled for this process.
+		|1|1|   3    THP-except-advised mode is set for this process.
+
+Khugepaged controls
+-------------------
+
+.. note::
+   khugepaged currently only searches for opportunities to collapse file/shmem
+   to PMD-sized THP. Only anonymous memory will attempt to collapse to other THP
+   sizes.
+
+khugepaged runs usually at low frequency so while one may not want to
+invoke defrag algorithms synchronously during the page faults, it
+should be worth invoking defrag at least in khugepaged. However it's
+also possible to disable defrag in khugepaged by writing 0 or enable
+defrag in khugepaged by writing 1::
+
+	echo 0 >/sys/kernel/mm/transparent_hugepage/khugepaged/defrag
+	echo 1 >/sys/kernel/mm/transparent_hugepage/khugepaged/defrag
+
+You can also control how many pages khugepaged should scan at each
+pass::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/pages_to_scan
+
+and how many milliseconds to wait in khugepaged between each pass (you
+can set this to 0 to run khugepaged at 100% utilization of one core)::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/scan_sleep_millisecs
+
+and how many milliseconds to wait in khugepaged if there's an hugepage
+allocation failure to throttle the next allocation attempt::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/alloc_sleep_millisecs
+
+The khugepaged progress can be seen in the number of pages collapsed (note
+that this counter may not be an exact count of the number of pages
+collapsed, since "collapsed" could mean multiple things: (1) A PTE mapping
+being replaced by a PMD mapping, or (2) physical pages replaced by one
+hugepage of various sizes (PMD-sized or mTHP). Each may happen independently,
+or together, depending on the type of memory and the failures that occur.
+As such, this value should be interpreted roughly as a sign of progress,
+and counters in /proc/vmstat consulted for more accurate accounting.
+Per-order mTHP collapse statistics are also available under
+/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/stats/)::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/pages_collapsed
+
+for each pass::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/full_scans
+
+``max_ptes_none`` specifies how many empty (none/zero) pages are allowed
+when collapsing a group of small pages into one large page::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none
+
+For PMD-sized THP collapse, this directly limits the number of empty pages
+allowed in the 2MB region.
+
+For mTHP collapse, only 0 or (HPAGE_PMD_NR - 1) are supported. At
+HPAGE_PMD_NR - 1, we collapse to the highest possible order. Any intermediate
+value will emit a warning and mTHP collapse will default to max_ptes_none=0.
+
+A higher value allows more empty pages, potentially leading to more memory
+usage but better THP performance. A lower value is more conservative and
+may result in fewer THP collapses.
+
+``max_ptes_swap`` specifies how many pages can be brought in from
+swap when collapsing a group of pages into a transparent huge page::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap
+
+A higher value can cause excessive swap IO and waste
+memory. A lower value can prevent THPs from being
+collapsed, resulting fewer pages being collapsed into
+THPs, and lower memory access performance.
+
+``max_ptes_shared`` specifies how many pages can be shared across multiple
+processes. khugepaged might treat pages of THPs as shared if any page of
+that THP is shared. Exceeding the number would block the collapse::
+
+	/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_shared
+
+A higher value may increase memory footprint for some workloads.
+
+.. note::
+   For mTHP collapse, khugepaged does not support collapsing regions that
+   contain shared or swapped out pages, as this could lead to continuous
+   promotion to higher orders. The collapse will fail if any shared or
+   swapped PTEs are encountered during the scan.
+
+   Currently, madvise_collapse only supports collapsing to PMD-sized THPs
+   and does not attempt mTHP collapses.
+
+Boot parameters
+===============
+
+You can change the sysfs boot time default for the top-level "enabled"
+control by passing the parameter ``transparent_hugepage=always`` or
+``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` to the
+kernel command line.
+
+Alternatively, each supported anonymous THP size can be controlled by
+passing ``thp_anon=<size>[KMG],<size>[KMG]:<state>;<size>[KMG]-<size>[KMG]:<state>``,
+where ``<size>`` is the THP size (must be a power of 2 of PAGE_SIZE and
+supported anonymous THP)  and ``<state>`` is one of ``always``, ``madvise``,
+``never`` or ``inherit``.
+
+For example, the following will set 16K, 32K, 64K THP to ``always``,
+set 128K, 512K to ``inherit``, set 256K to ``madvise`` and 1M, 2M
+to ``never``::
+
+	thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
+
+``thp_anon=`` may be specified multiple times to configure all THP sizes as
+required. If ``thp_anon=`` is specified at least once, any anon THP sizes
+not explicitly configured on the command line are implicitly set to
+``never``.
+
+``transparent_hugepage`` setting only affects the global toggle. If
+``thp_anon`` is not specified, PMD_ORDER THP will default to ``inherit``.
+However, if a valid ``thp_anon`` setting is provided by the user, the
+PMD_ORDER THP policy will be overridden. If the policy for PMD_ORDER
+is not defined within a valid ``thp_anon``, its policy will default to
+``never``.
+
+Similarly to ``transparent_hugepage``, you can control the hugepage
+allocation policy for the internal shmem mount by using the kernel parameter
+``transparent_hugepage_shmem=<policy>``, where ``<policy>`` is one of the
+seven valid policies for shmem (``always``, ``within_size``, ``advise``,
+``never``, ``deny``, and ``force``).
+
+Similarly to ``transparent_hugepage_shmem``, you can control the default
+hugepage allocation policy for the tmpfs mount by using the kernel parameter
+``transparent_hugepage_tmpfs=<policy>``, where ``<policy>`` is one of the
+four valid policies for tmpfs (``always``, ``within_size``, ``advise``,
+``never``). The tmpfs mount default policy is ``never``.
+
+Additionally, Kconfig options are available to set the default hugepage
+policies for shmem (``CONFIG_TRANSPARENT_HUGEPAGE_SHMEM_HUGE_*``) and tmpfs
+(``CONFIG_TRANSPARENT_HUGEPAGE_TMPFS_HUGE_*``) at build time. Refer to the
+Kconfig help for more details.
+
+In the same manner as ``thp_anon`` controls each supported anonymous THP
+size, ``thp_shmem`` controls each supported shmem THP size. ``thp_shmem``
+has the same format as ``thp_anon``, but also supports the policy
+``within_size``.
+
+``thp_shmem=`` may be specified multiple times to configure all THP sizes
+as required. If ``thp_shmem=`` is specified at least once, any shmem THP
+sizes not explicitly configured on the command line are implicitly set to
+``never``.
+
+``transparent_hugepage_shmem`` setting only affects the global toggle. If
+``thp_shmem`` is not specified, PMD_ORDER hugepage will default to
+``inherit``. However, if a valid ``thp_shmem`` setting is provided by the
+user, the PMD_ORDER hugepage policy will be overridden. If the policy for
+PMD_ORDER is not defined within a valid ``thp_shmem``, its policy will
+default to ``never``.
+
+Hugepages in tmpfs/shmem
+========================
+
+Traditionally, tmpfs only supported a single huge page size ("PMD"). Today,
+it also supports smaller sizes just like anonymous memory, often referred
+to as "multi-size THP" (mTHP). Huge pages of any size are commonly
+represented in the kernel as "large folios".
+
+While there is fine control over the huge page sizes to use for the internal
+shmem mount (see below), ordinary tmpfs mounts will make use of all available
+huge page sizes without any control over the exact sizes, behaving more like
+other file systems.
+
+tmpfs mounts
+------------
+
+The THP allocation policy for tmpfs mounts can be adjusted using the mount
+option: ``huge=``. It can have following values:
+
+always
+    Attempt to allocate huge pages every time we need a new page;
+    Always try PMD-sized huge pages first, and fall back to smaller-sized
+    huge pages if the PMD-sized huge page allocation fails;
+
+never
+    Do not allocate huge pages. Note that ``madvise(..., MADV_COLLAPSE)``
+    can still cause transparent huge pages to be obtained even if this mode
+    is specified everywhere;
+
+within_size
+    Only allocate huge page if it will be fully within i_size;
+    Always try PMD-sized huge pages first, and fall back to smaller-sized
+    huge pages if the PMD-sized huge page allocation fails;
+    Also respect madvise() hints;
+
+advise
+    Only allocate huge pages if requested with madvise();
+
+Remember, that the kernel may use huge pages of all available sizes, and
+that no fine control as for the internal tmpfs mount is available.
+
+The default policy in the past was ``never``, but it can now be adjusted
+using the kernel parameter ``transparent_hugepage_tmpfs=<policy>``.
+
+``mount -o remount,huge= /mountpoint`` works fine after mount: remounting
+``huge=never`` will not attempt to break up huge pages at all, just stop more
+from being allocated.
+
+In addition to policies listed above, the sysfs knob
+/sys/kernel/mm/transparent_hugepage/shmem_enabled will affect the
+allocation policy of tmpfs mounts, when set to the following values:
+
+deny
+    For use in emergencies, to force the huge option off from
+    all mounts;
+force
+    Force the huge option on for all - very useful for testing;
+
+shmem / internal tmpfs
+----------------------
+The mount internal tmpfs mount is used for SysV SHM, memfds, shared anonymous
+mmaps (of /dev/zero or MAP_ANONYMOUS), GPU drivers' DRM  objects, Ashmem.
+
+To control the THP allocation policy for this internal tmpfs mount, the
+sysfs knob /sys/kernel/mm/transparent_hugepage/shmem_enabled and the knobs
+per THP size in
+'/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/shmem_enabled'
+can be used.
+
+The global knob has the same semantics as the ``huge=`` mount options
+for tmpfs mounts, except that the different huge page sizes can be controlled
+individually, and will only use the setting of the global knob when the
+per-size knob is set to 'inherit'.
+
+The options 'force' and 'deny' are dropped for the individual sizes, which
+are rather testing artifacts from the old ages.
+
+always
+    Attempt to allocate <size> huge pages every time we need a new page;
+
+inherit
+    Inherit the top-level "shmem_enabled" value. By default, PMD-sized hugepages
+    have enabled="inherit" and all other hugepage sizes have enabled="never";
+
+never
+    Do not allocate <size> huge pages. Note that ``madvise(...,
+    MADV_COLLAPSE)`` can still cause transparent huge pages to be obtained
+    even if this mode is specified everywhere;
+
+within_size
+    Only allocate <size> huge page if it will be fully within i_size.
+    Also respect madvise() hints;
+
+advise
+    Only allocate <size> huge pages if requested with madvise();
+
+Need of application restart
+===========================
+
+The transparent_hugepage/enabled and
+transparent_hugepage/hugepages-<size>kB/enabled values and tmpfs mount
+option only affect future behavior. So to make them effective you need
+to restart any application that could have been using hugepages. This
+also applies to the regions registered in khugepaged.
+
+Monitoring usage
+================
+
+The number of PMD-sized anonymous transparent huge pages currently used by the
+system is available by reading the AnonHugePages field in ``/proc/meminfo``.
+To identify what applications are using PMD-sized anonymous transparent huge
+pages, it is necessary to read ``/proc/PID/smaps`` and count the AnonHugePages
+fields for each mapping. (Note that AnonHugePages only applies to traditional
+PMD-sized THP for historical reasons and should have been called
+AnonHugePmdMapped).
+
+The number of file transparent huge pages mapped to userspace is available
+by reading ShmemPmdMapped and ShmemHugePages fields in ``/proc/meminfo``.
+To identify what applications are mapping file transparent huge pages, it
+is necessary to read ``/proc/PID/smaps`` and count the FilePmdMapped fields
+for each mapping.
+
+Note that reading the smaps file is expensive and reading it
+frequently will incur overhead.
+
+There are a number of counters in ``/proc/vmstat`` that may be used to
+monitor how successfully the system is providing huge pages for use.
+
+thp_fault_alloc
+	is incremented every time a huge page is successfully
+	allocated and charged to handle a page fault.
+
+thp_collapse_alloc
+	is incremented by khugepaged when it has found
+	a range of pages to collapse into one huge page and has
+	successfully allocated a new huge page to store the data.
+
+thp_fault_fallback
+	is incremented if a page fault fails to allocate or charge
+	a huge page and instead falls back to using small pages.
+
+thp_fault_fallback_charge
+	is incremented if a page fault fails to charge a huge page and
+	instead falls back to using small pages even though the
+	allocation was successful.
+
+thp_collapse_alloc_failed
+	is incremented if khugepaged found a range
+	of pages that should be collapsed into one huge page but failed
+	the allocation.
+
+thp_file_alloc
+	is incremented every time a shmem huge page is successfully
+	allocated (Note that despite being named after "file", the counter
+	measures only shmem).
+
+thp_file_fallback
+	is incremented if a shmem huge page is attempted to be allocated
+	but fails and instead falls back to using small pages. (Note that
+	despite being named after "file", the counter measures only shmem).
+
+thp_file_fallback_charge
+	is incremented if a shmem huge page cannot be charged and instead
+	falls back to using small pages even though the allocation was
+	successful. (Note that despite being named after "file", the
+	counter measures only shmem).
+
+thp_file_mapped
+	is incremented every time a file or shmem huge page is mapped into
+	user address space.
+
+thp_split_page
+	is incremented every time a huge page is split into base
+	pages. This can happen for a variety of reasons but a common
+	reason is that a huge page is old and is being reclaimed.
+	This action implies splitting all PMD the page mapped with.
+
+thp_split_page_failed
+	is incremented if kernel fails to split huge
+	page. This can happen if the page was pinned by somebody.
+
+thp_deferred_split_page
+	is incremented when a huge page is put onto split
+	queue. This happens when a huge page is partially unmapped and
+	splitting it would free up some memory. Pages on split queue are
+	going to be split under memory pressure.
+
+thp_underused_split_page
+	is incremented when a huge page on the split queue was split
+	because it was underused. A THP is underused if the number of
+	zero pages in the THP is above a certain threshold
+	(/sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none).
+
+thp_split_pmd
+	is incremented every time a PMD split into table of PTEs.
+	This can happen, for instance, when application calls mprotect() or
+	munmap() on part of huge page. It doesn't split huge page, only
+	page table entry.
+
+thp_zero_page_alloc
+	is incremented every time a huge zero page used for thp is
+	successfully allocated. Note, it doesn't count every map of
+	the huge zero page, only its allocation.
+
+thp_zero_page_alloc_failed
+	is incremented if kernel fails to allocate
+	huge zero page and falls back to using small pages.
+
+thp_swpout
+	is incremented every time a huge page is swapout in one
+	piece without splitting.
+
+thp_swpout_fallback
+	is incremented if a huge page has to be split before swapout.
+	Usually because failed to allocate some continuous swap space
+	for the huge page.
+
+In /sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/stats, There are
+also individual counters for each huge page size, which can be utilized to
+monitor the system's effectiveness in providing huge pages for usage. Each
+counter has its own corresponding file.
+
+anon_fault_alloc
+	is incremented every time a huge page is successfully
+	allocated and charged to handle a page fault.
+
+anon_fault_fallback
+	is incremented if a page fault fails to allocate or charge
+	a huge page and instead falls back to using huge pages with
+	lower orders or small pages.
+
+anon_fault_fallback_charge
+	is incremented if a page fault fails to charge a huge page and
+	instead falls back to using huge pages with lower orders or
+	small pages even though the allocation was successful.
+
+collapse_alloc
+	is incremented every time a huge page is successfully allocated for a
+	khugepaged collapse.
+
+collapse_alloc_failed
+	is incremented every time a huge page allocation fails during a
+	khugepaged collapse.
+
+zswpout
+	is incremented every time a huge page is swapped out to zswap in one
+	piece without splitting.
+
+swpin
+	is incremented every time a huge page is swapped in from a non-zswap
+	swap device in one piece.
+
+swpin_fallback
+	is incremented if swapin fails to allocate or charge a huge page
+	and instead falls back to using huge pages with lower orders or
+	small pages.
+
+swpin_fallback_charge
+	is incremented if swapin fails to charge a huge page and instead
+	falls back to using  huge pages with lower orders or small pages
+	even though the allocation was successful.
+
+swpout
+	is incremented every time a huge page is swapped out to a non-zswap
+	swap device in one piece without splitting.
+
+swpout_fallback
+	is incremented if a huge page has to be split before swapout.
+	Usually because failed to allocate some continuous swap space
+	for the huge page.
+
+shmem_alloc
+	is incremented every time a shmem huge page is successfully
+	allocated.
+
+shmem_fallback
+	is incremented if a shmem huge page is attempted to be allocated
+	but fails and instead falls back to using small pages.
+
+shmem_fallback_charge
+	is incremented if a shmem huge page cannot be charged and instead
+	falls back to using small pages even though the allocation was
+	successful.
+
+split
+	is incremented every time a huge page is successfully split into
+	smaller orders. This can happen for a variety of reasons but a
+	common reason is that a huge page is old and is being reclaimed.
+
+split_failed
+	is incremented if kernel fails to split huge
+	page. This can happen if the page was pinned by somebody.
+
+split_deferred
+        is incremented when a huge page is put onto split queue.
+        This happens when a huge page is partially unmapped and splitting
+        it would free up some memory. Pages on split queue are going to
+        be split under memory pressure, if splitting is possible.
+
+nr_anon
+       the number of anonymous THP we have in the whole system. These THPs
+       might be currently entirely mapped or have partially unmapped/unused
+       subpages.
+
+nr_anon_partially_mapped
+       the number of anonymous THP which are likely partially mapped, possibly
+       wasting memory, and have been queued for deferred memory reclamation.
+       Note that in corner some cases (e.g., failed migration), we might detect
+       an anonymous THP as "partially mapped" and count it here, even though it
+       is not actually partially mapped anymore.
+
+collapse_exceed_none_pte
+       The number of collapse attempts that failed due to exceeding the
+       max_ptes_none threshold.
+
+collapse_exceed_swap_pte
+       The number of collapse attempts that failed due to exceeding the
+       max_ptes_swap threshold. For non-PMD orders this occurs if a mTHP range
+       contains at least one swap PTE.
+
+collapse_exceed_shared_pte
+       The number of collapse attempts that failed due to exceeding the
+       max_ptes_shared threshold. For non-PMD orders this occurs if a mTHP range
+       contains at least one shared PTE.
+
+As the system ages, allocating huge pages may be expensive as the
+system uses memory compaction to copy data around memory to free a
+huge page for use. There are some counters in ``/proc/vmstat`` to help
+monitor this overhead.
+
+compact_stall
+	is incremented every time a process stalls to run
+	memory compaction so that a huge page is free for use.
+
+compact_success
+	is incremented if the system compacted memory and
+	freed a huge page for use.
+
+compact_fail
+	is incremented if the system tries to compact memory
+	but failed.
+
+It is possible to establish how long the stalls were using the function
+tracer to record how long was spent in the page allocator and
+using the mm_page_alloc tracepoint to identify which allocations were
+for huge pages.
+
+Optimizing the applications
+===========================
+
+To be guaranteed that the kernel will map a THP immediately in any
+memory region, the mmap region has to be hugepage naturally
+aligned. posix_memalign() can provide that guarantee.
+
+Hugetlbfs
+=========
+
+You can use hugetlbfs on a kernel that has transparent hugepage
+support enabled just fine as always. No difference can be noted in
+hugetlbfs other than there will be less overall fragmentation. All
+usual features belonging to hugetlbfs are preserved and
+unaffected. libhugetlbfs will also work fine as usual.
diff --git a/Documentation/admin-guide/mm/userfaultfd.rst b/Documentation/admin-guide/mm/userfaultfd.rst
new file mode 100644
index 000000000..783d969f0
--- /dev/null
+++ b/Documentation/admin-guide/mm/userfaultfd.rst
@@ -0,0 +1,687 @@
+===========
+Userfaultfd
+===========
+
+Objective
+=========
+
+Userfaults allow the implementation of on-demand paging from userland
+and more generally they allow userland to take control of various
+memory page faults, something otherwise only the kernel code could do.
+
+For example userfaults allows a proper and more optimal implementation
+of the ``PROT_NONE+SIGSEGV`` trick.
+
+Design
+======
+
+Userspace creates a new userfaultfd, initializes it, and registers one or more
+regions of virtual memory with it. Then, any page faults which occur within the
+region(s) result in a message being delivered to the userfaultfd, notifying
+userspace of the fault.
+
+The ``userfaultfd`` (aside from registering and unregistering virtual
+memory ranges) provides two primary functionalities:
+
+1) ``read/POLLIN`` protocol to notify a userland thread of the faults
+   happening
+
+2) various ``UFFDIO_*`` ioctls that can manage the virtual memory regions
+   registered in the ``userfaultfd`` that allows userland to efficiently
+   resolve the userfaults it receives via 1) or to manage the virtual
+   memory in the background
+
+The real advantage of userfaults if compared to regular virtual memory
+management of mremap/mprotect is that the userfaults in all their
+operations never involve heavyweight structures like vmas (in fact the
+``userfaultfd`` runtime load never takes the mmap_lock for writing).
+Vmas are not suitable for page- (or hugepage) granular fault tracking
+when dealing with virtual address spaces that could span
+Terabytes. Too many vmas would be needed for that.
+
+The ``userfaultfd``, once created, can also be
+passed using unix domain sockets to a manager process, so the same
+manager process could handle the userfaults of a multitude of
+different processes without them being aware about what is going on
+(well of course unless they later try to use the ``userfaultfd``
+themselves on the same region the manager is already tracking, which
+is a corner case that would currently return ``-EBUSY``).
+
+API
+===
+
+Creating a userfaultfd
+----------------------
+
+There are two ways to create a new userfaultfd, each of which provide ways to
+restrict access to this functionality (since historically userfaultfds which
+handle kernel page faults have been a useful tool for exploiting the kernel).
+
+The first way, supported since userfaultfd was introduced, is the
+userfaultfd(2) syscall. Access to this is controlled in several ways:
+
+- Any user can always create a userfaultfd which traps userspace page faults
+  only. Such a userfaultfd can be created using the userfaultfd(2) syscall
+  with the flag UFFD_USER_MODE_ONLY.
+
+- In order to also trap kernel page faults for the address space, either the
+  process needs the CAP_SYS_PTRACE capability, or the system must have
+  vm.unprivileged_userfaultfd set to 1. By default, vm.unprivileged_userfaultfd
+  is set to 0.
+
+The second way, added to the kernel more recently, is by opening
+/dev/userfaultfd and issuing a USERFAULTFD_IOC_NEW ioctl to it. This method
+yields equivalent userfaultfds to the userfaultfd(2) syscall.
+
+Unlike userfaultfd(2), access to /dev/userfaultfd is controlled via normal
+filesystem permissions (user/group/mode), which gives fine grained access to
+userfaultfd specifically, without also granting other unrelated privileges at
+the same time (as e.g. granting CAP_SYS_PTRACE would do). Users who have access
+to /dev/userfaultfd can always create userfaultfds that trap kernel page faults;
+vm.unprivileged_userfaultfd is not considered.
+
+Initializing a userfaultfd
+--------------------------
+
+When first opened the ``userfaultfd`` must be enabled invoking the
+``UFFDIO_API`` ioctl specifying a ``uffdio_api.api`` value set to ``UFFD_API`` (or
+a later API version) which will specify the ``read/POLLIN`` protocol
+userland intends to speak on the ``UFFD`` and the ``uffdio_api.features``
+userland requires. The ``UFFDIO_API`` ioctl if successful (i.e. if the
+requested ``uffdio_api.api`` is spoken also by the running kernel and the
+requested features are going to be enabled) will return into
+``uffdio_api.features`` and ``uffdio_api.ioctls`` two 64bit bitmasks of
+respectively all the available features of the read(2) protocol and
+the generic ioctl available.
+
+The ``uffdio_api.features`` bitmask returned by the ``UFFDIO_API`` ioctl
+defines what memory types are supported by the ``userfaultfd`` and what
+events, except page fault notifications, may be generated:
+
+- The ``UFFD_FEATURE_EVENT_*`` flags indicate that various other events
+  other than page faults are supported. These events are described in more
+  detail below in the `Non-cooperative userfaultfd`_ section.
+
+- ``UFFD_FEATURE_MISSING_HUGETLBFS`` and ``UFFD_FEATURE_MISSING_SHMEM``
+  indicate that the kernel supports ``UFFDIO_REGISTER_MODE_MISSING``
+  registrations for hugetlbfs and shared memory (covering all shmem APIs,
+  i.e. tmpfs, ``IPCSHM``, ``/dev/zero``, ``MAP_SHARED``, ``memfd_create``,
+  etc) virtual memory areas, respectively.
+
+- ``UFFD_FEATURE_MINOR_HUGETLBFS`` indicates that the kernel supports
+  ``UFFDIO_REGISTER_MODE_MINOR`` registration for hugetlbfs virtual memory
+  areas. ``UFFD_FEATURE_MINOR_SHMEM`` is the analogous feature indicating
+  support for shmem virtual memory areas.
+
+- ``UFFD_FEATURE_MOVE`` indicates that the kernel supports moving an
+  existing page contents from userspace.
+
+The userland application should set the feature flags it intends to use
+when invoking the ``UFFDIO_API`` ioctl, to request that those features be
+enabled if supported.
+
+Once the ``userfaultfd`` API has been enabled the ``UFFDIO_REGISTER``
+ioctl should be invoked (if present in the returned ``uffdio_api.ioctls``
+bitmask) to register a memory range in the ``userfaultfd`` by setting the
+uffdio_register structure accordingly. The ``uffdio_register.mode``
+bitmask will specify to the kernel which kind of faults to track for
+the range. The ``UFFDIO_REGISTER`` ioctl will return the
+``uffdio_register.ioctls`` bitmask of ioctls that are suitable to resolve
+userfaults on the range registered. Not all ioctls will necessarily be
+supported for all memory types (e.g. anonymous memory vs. shmem vs.
+hugetlbfs), or all types of intercepted faults.
+
+.. note::
+
+   Re-registering an already-registered range must not drop any of the
+   modes that install per-PTE markers — currently
+   ``UFFDIO_REGISTER_MODE_WP`` and ``UFFDIO_REGISTER_MODE_RWP``. Doing
+   so would strand markers with no flag to describe them, so the call
+   is rejected with ``-EBUSY``; userspace must issue
+   ``UFFDIO_UNREGISTER`` first. This differs from older kernels, which
+   silently replaced the mode bits on re-registration.
+
+Userland can use the ``uffdio_register.ioctls`` to manage the virtual
+address space in the background (to add or potentially also remove
+memory from the ``userfaultfd`` registered range). This means a userfault
+could be triggering just before userland maps in the background the
+user-faulted page.
+
+Resolving Userfaults
+--------------------
+
+There are three basic ways to resolve userfaults:
+
+- ``UFFDIO_COPY`` atomically copies some existing page contents from
+  userspace.
+
+- ``UFFDIO_ZEROPAGE`` atomically zeros the new page.
+
+- ``UFFDIO_CONTINUE`` maps an existing, previously-populated page.
+
+These operations are atomic in the sense that they guarantee nothing can
+see a half-populated page, since readers will keep userfaulting until the
+operation has finished.
+
+By default, these wake up userfaults blocked on the range in question.
+They support a ``UFFDIO_*_MODE_DONTWAKE`` ``mode`` flag, which indicates
+that waking will be done separately at some later time.
+
+Which ioctl to choose depends on the kind of page fault, and what we'd
+like to do to resolve it:
+
+- For ``UFFDIO_REGISTER_MODE_MISSING`` faults, the fault needs to be
+  resolved by either providing a new page (``UFFDIO_COPY``), or mapping
+  the zero page (``UFFDIO_ZEROPAGE``). By default, the kernel would map
+  the zero page for a missing fault. With userfaultfd, userspace can
+  decide what content to provide before the faulting thread continues.
+
+- For ``UFFDIO_REGISTER_MODE_MINOR`` faults, there is an existing page (in
+  the page cache). Userspace has the option of modifying the page's
+  contents before resolving the fault. Once the contents are correct
+  (modified or not), userspace asks the kernel to map the page and let the
+  faulting thread continue with ``UFFDIO_CONTINUE``.
+
+Notes:
+
+- You can tell which kind of fault occurred by examining
+  ``pagefault.flags`` within the ``uffd_msg``, checking for the
+  ``UFFD_PAGEFAULT_FLAG_*`` flags.
+
+- None of the page-delivering ioctls default to the range that you
+  registered with.  You must fill in all fields for the appropriate
+  ioctl struct including the range.
+
+- You get the address of the access that triggered the missing page
+  event out of a struct uffd_msg that you read in the thread from the
+  uffd.  You can supply as many pages as you want with these IOCTLs.
+  Keep in mind that unless you used DONTWAKE then the first of any of
+  those IOCTLs wakes up the faulting thread.
+
+- Be sure to test for all errors including
+  (``pollfd[0].revents & POLLERR``).  This can happen, e.g. when ranges
+  supplied were incorrect.
+
+Write Protect Notifications
+---------------------------
+
+This is equivalent to (but faster than) using mprotect and a SIGSEGV
+signal handler.
+
+Firstly you need to register a range with ``UFFDIO_REGISTER_MODE_WP``.
+Instead of using mprotect(2) you use
+``ioctl(uffd, UFFDIO_WRITEPROTECT, struct *uffdio_writeprotect)``
+while ``mode = UFFDIO_WRITEPROTECT_MODE_WP``
+in the struct passed in.  The range does not default to and does not
+have to be identical to the range you registered with.  You can write
+protect as many ranges as you like (inside the registered range).
+Then, in the thread reading from uffd the struct will have
+``msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP`` set. Now you send
+``ioctl(uffd, UFFDIO_WRITEPROTECT, struct *uffdio_writeprotect)``
+again while ``pagefault.mode`` does not have ``UFFDIO_WRITEPROTECT_MODE_WP``
+set. This wakes up the thread which will continue to run with writes. This
+allows you to do the bookkeeping about the write in the uffd reading
+thread before the ioctl.
+
+If you registered with both ``UFFDIO_REGISTER_MODE_MISSING`` and
+``UFFDIO_REGISTER_MODE_WP`` then you need to think about the sequence in
+which you supply a page and undo write protect.  Note that there is a
+difference between writes into a WP area and into a !WP area.  The
+former will have ``UFFD_PAGEFAULT_FLAG_WP`` set, the latter
+``UFFD_PAGEFAULT_FLAG_WRITE``.  The latter did not fail on protection but
+you still need to supply a page when ``UFFDIO_REGISTER_MODE_MISSING`` was
+used.
+
+Userfaultfd write-protect mode currently behave differently on none ptes
+(when e.g. page is missing) over different types of memories.
+
+For anonymous memory, ``ioctl(UFFDIO_WRITEPROTECT)`` will ignore none ptes
+(e.g. when pages are missing and not populated).  For file-backed memories
+like shmem and hugetlbfs, none ptes will be write protected just like a
+present pte.  In other words, there will be a userfaultfd write fault
+message generated when writing to a missing page on file typed memories,
+as long as the page range was write-protected before.  Such a message will
+not be generated on anonymous memories by default.
+
+If the application wants to be able to write protect none ptes on anonymous
+memory, one can pre-populate the memory with e.g. MADV_POPULATE_READ.  On
+newer kernels, one can also detect the feature UFFD_FEATURE_WP_UNPOPULATED
+and set the feature bit in advance to make sure none ptes will also be
+write protected even upon anonymous memory.
+
+When using ``UFFDIO_REGISTER_MODE_WP`` in combination with either
+``UFFDIO_REGISTER_MODE_MISSING`` or ``UFFDIO_REGISTER_MODE_MINOR``, when
+resolving missing / minor faults with ``UFFDIO_COPY`` or ``UFFDIO_CONTINUE``
+respectively, it may be desirable for the new page / mapping to be
+write-protected (so future writes will also result in a WP fault). These ioctls
+support a mode flag (``UFFDIO_COPY_MODE_WP`` or ``UFFDIO_CONTINUE_MODE_WP``
+respectively) to configure the mapping this way.
+
+If the userfaultfd context has ``UFFD_FEATURE_WP_ASYNC`` feature bit set,
+any vma registered with write-protection will work in async mode rather
+than the default sync mode.
+
+In async mode, there will be no message generated when a write operation
+happens, meanwhile the write-protection will be resolved automatically by
+the kernel.  It can be seen as a more accurate version of soft-dirty
+tracking and it can be different in a few ways:
+
+  - The dirty result will not be affected by vma changes (e.g. vma
+    merging) because the dirty is only tracked by the pte.
+
+  - It supports range operations by default, so one can enable tracking on
+    any range of memory as long as page aligned.
+
+  - Dirty information will not get lost if the pte was zapped due to
+    various reasons (e.g. during split of a shmem transparent huge page).
+
+  - Due to a reverted meaning of soft-dirty (page clean when the uffd bit
+    is set; dirty when the uffd bit is cleared), it has different semantics
+    on some of the memory operations.  For example: ``MADV_DONTNEED`` on
+    anonymous (or ``MADV_REMOVE`` on a file mapping) will be treated as
+    dirtying of memory by dropping the uffd bit during the procedure.
+
+The user app can collect the "written/dirty" status by looking up the
+uffd bit for the pages being interested in /proc/pagemap.
+
+The page will not be under track of userfaultfd-wp async mode until the page is
+explicitly write-protected by ``ioctl(UFFDIO_WRITEPROTECT)`` with the mode
+flag ``UFFDIO_WRITEPROTECT_MODE_WP`` set.  Trying to resolve a page fault
+that was tracked by async mode userfaultfd-wp is invalid.
+
+When userfaultfd-wp async mode is used alone, it can be applied to all
+kinds of memory.
+
+Memory Poisioning Emulation
+---------------------------
+
+In response to a fault (either missing or minor), an action userspace can
+take to "resolve" it is to issue a ``UFFDIO_POISON``. This will cause any
+future faulters to either get a SIGBUS, or in KVM's case the guest will
+receive an MCE as if there were hardware memory poisoning.
+
+This is used to emulate hardware memory poisoning. Imagine a VM running on a
+machine which experiences a real hardware memory error. Later, we live migrate
+the VM to another physical machine. Since we want the migration to be
+transparent to the guest, we want that same address range to act as if it was
+still poisoned, even though it's on a new physical host which ostensibly
+doesn't have a memory error in the exact same spot.
+
+Read-Write Protection
+---------------------
+
+``UFFDIO_REGISTER_MODE_RWP`` enables read-write protection tracking on a
+memory range. It is similar to (but faster than) ``mprotect(PROT_NONE)``
+combined with a signal handler; unlike ``mprotect(PROT_NONE)``, RWP only
+traps accesses to *present* PTEs, so accesses to unpopulated addresses in a
+protected range fall through to the normal missing-page path. It uses the
+PROT_NONE hinting mechanism (same as NUMA balancing) to make pages
+inaccessible while keeping them resident in memory. Works on anonymous,
+shmem, and hugetlbfs memory.
+
+RWP is designed for VM memory managers that need to track the working set
+of guest memory for cold page eviction to tiered or remote storage.
+
+**Setup:**
+
+1. Open a userfaultfd and enable ``UFFD_FEATURE_RWP`` via ``UFFDIO_API``.
+   Optionally request ``UFFD_FEATURE_RWP_ASYNC`` as well — it requires
+   ``UFFD_FEATURE_RWP`` to be set in the same ``UFFDIO_API`` call.
+
+2. Register the guest memory range with ``UFFDIO_REGISTER_MODE_RWP``
+   (and ``UFFDIO_REGISTER_MODE_MISSING`` if evicted pages will need to be
+   fetched back from storage).
+
+**Feature availability:**
+
+RWP is built on top of two kernel primitives: a spare PTE bit owned by
+userfaultfd (``CONFIG_HAVE_ARCH_USERFAULTFD_WP``) and architecture support
+for present-but-inaccessible PTEs (``CONFIG_ARCH_HAS_PTE_PROTNONE``). When both
+are available on a 64-bit kernel, the build selects
+``CONFIG_USERFAULTFD_RWP=y`` and the ``VM_UFFD_RWP`` VMA flag becomes
+available.
+
+``UFFD_FEATURE_RWP`` and ``UFFD_FEATURE_RWP_ASYNC`` are unavailable when
+the running kernel or architecture does not support them — for example
+32-bit kernels (where ``VM_UFFD_RWP`` is unavailable), kernels built
+without ``CONFIG_USERFAULTFD_RWP``, and architectures whose ptes cannot
+carry the uffd bit at runtime (e.g. riscv without the ``SVRSW60T59B``
+extension). Requesting an unsupported feature in
+``uffdio_api.features`` makes ``UFFDIO_API`` fail with ``EINVAL`` and
+leaves the userfaultfd context uninitialized; the structure is returned
+zeroed, so the error path cannot be used to discover what the kernel
+supports. The recommended probe sequence is therefore to open a
+throwaway userfaultfd, call ``UFFDIO_API`` once with ``features = 0``,
+inspect the returned bitmask, close that fd, then open the real one
+and call ``UFFDIO_API`` again with only the supported features set.
+
+**Protecting and Unprotecting:**
+
+Use ``UFFDIO_RWPROTECT`` to protect or unprotect a range, mirroring the
+``UFFDIO_WRITEPROTECT`` interface::
+
+    struct uffdio_rwprotect rwp = {
+        .range = { .start = addr, .len = len },
+        .mode = UFFDIO_RWPROTECT_MODE_RWP,  /* protect */
+    };
+    ioctl(uffd, UFFDIO_RWPROTECT, &rwp);
+
+Setting ``UFFDIO_RWPROTECT_MODE_RWP`` sets PROT_NONE on present PTEs in the
+range. Pages stay resident and their physical frames are preserved — only
+access permissions are removed.
+
+Clearing ``UFFDIO_RWPROTECT_MODE_RWP`` restores normal VMA permissions and
+wakes any faulting threads (unless ``UFFDIO_RWPROTECT_MODE_DONTWAKE`` is set).
+
+**Scope of protection:**
+
+RWP protection is a property of *present* PTEs. ``UFFDIO_RWPROTECT`` only
+affects entries that are already populated. Unpopulated addresses within
+the range remain unpopulated; when first accessed they fault through the
+normal missing path (``do_anonymous_page()``, ``do_swap_page()``,
+``finish_fault()``) and the resulting PTE is not RWP-protected. To observe
+the population itself, co-register the range with
+``UFFDIO_REGISTER_MODE_MISSING``.
+
+Protection is preserved across page reclaim: a page swapped out while
+RWP-protected carries the marker on its swap entry, and swap-in restores
+the PROT_NONE state so the first access after swap-in still faults. The
+same applies to pages temporarily replaced by migration entries.
+
+Operations that drop the PTE entirely — ``MADV_DONTNEED`` on anonymous
+memory, hole-punch on shmem, truncation of a file mapping — also drop the
+RWP marker: the next access re-populates the range without protection.
+Unlike WP (which persists via ``PTE_MARKER_UFFD_WP``), there is no
+persistent RWP marker today. The user needs to re-arm the range with
+``UFFDIO_RWPROTECT`` after any operation that explicitly frees PTEs.
+
+**Fault Handling:**
+
+When a protected page is accessed:
+
+- **Sync mode** (default): The faulting thread blocks and a
+  ``UFFD_PAGEFAULT_FLAG_RWP`` message is delivered to the userfaultfd
+  handler. The handler resolves the fault with ``UFFDIO_RWPROTECT``
+  (clearing ``MODE_RWP``), which restores the PTE permissions and wakes
+  the faulting thread.
+
+- **Async mode** (``UFFD_FEATURE_RWP_ASYNC``): The kernel automatically
+  restores PTE permissions and the thread continues without blocking. No
+  message is delivered to the handler.
+
+**Runtime Mode Switching:**
+
+``UFFDIO_SET_MODE`` toggles ``UFFD_FEATURE_RWP_ASYNC`` at runtime, allowing
+the VMM to switch between lightweight async detection and safe sync
+eviction without re-registering. The toggle takes ``mmap_write_lock()``
+and calls ``vma_start_write()`` on each UFFD-armed VMA, draining
+in-flight per-VMA-locked faults before the new mode takes effect.
+
+**Working-set detection with PAGEMAP_SCAN:**
+
+RWP-protected PTEs carry the uffd PTE bit; an access (and, in async mode, its
+auto-resolution) clears it. ``PAGEMAP_SCAN`` reports ``PAGE_IS_ACCESSED`` once
+the bit is clear on a ``VM_UFFD_RWP`` VMA, so a *non-inverted* scan reports the
+pages that were touched during the interval -- the hot set::
+
+    struct pm_scan_arg arg = {
+        .size = sizeof(arg),
+        .start = guest_mem_start,
+        .end = guest_mem_end,
+        .vec = (uint64_t)regions,
+        .vec_len = regions_len,
+        .category_mask = PAGE_IS_ACCESSED,
+        .return_mask = PAGE_IS_ACCESSED,
+    };
+    long n = ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);
+
+The returned ``page_region`` array lists the hot ranges. ``PAGE_IS_ACCESSED``
+is set on an accessed page whether it is still present or has since been
+swapped out, so the hot scan needs no ``PAGE_IS_PRESENT`` filter -- unpopulated
+holes carry neither bit and are excluded on their own.
+
+Track the hot set and reclaim everything else from the backing file (see the
+workflow below). Do **not** invert the scan to enumerate "cold" pages
+directly: an inverted scan reports only the ``VM_UFFD_RWP`` PTEs that are still
+protected, i.e. the resident portion of *this* VMA. For a file mapping the
+working set spans the whole file -- pages that live in the page cache but are
+not mapped into this VMA (a pre-populated tmpfs file, or memory populated
+through another mapping) are ``pte_none`` here, never appear in the scan, and
+would never be considered for eviction even though they occupy memory. Driving
+eviction from "file offsets minus the hot set" avoids that blind spot; a cold
+PTE scan cannot. To additionally record the *first* access to a cached but
+unmapped page (e.g. pre-populated content) as hot, co-register the range with
+``UFFDIO_REGISTER_MODE_MINOR``: such accesses then fault as minor faults
+instead of mapping the page silently.
+
+**Cleanup:**
+
+When the userfaultfd is closed or the range is unregistered, all PROT_NONE
+PTEs are automatically restored to their normal VMA permissions. This
+prevents pages from becoming permanently inaccessible.
+
+**VMM Working Set Tracking Workflow:**
+
+A typical VMM lifecycle for cold page eviction to tiered storage. Two
+mappings of the same shmem (or hugetlbfs) file are used: ``guest_mem`` is
+the RWP-registered mapping that vCPUs access through, and ``io_mem`` is a
+private mapping for VMM-side I/O. Reading ``io_mem`` does not go through
+the RWP-protected PTEs of ``guest_mem``, so the VMM's own ``pwrite()``
+never traps on its own ::
+
+    /* One-time setup */
+    fd = memfd_create("guest", MFD_CLOEXEC);
+    ftruncate(fd, guest_size);
+    guest_mem = mmap(NULL, guest_size, PROT_READ | PROT_WRITE,
+                     MAP_SHARED, fd, 0);  /* vCPU view, RWP-registered */
+    io_mem    = mmap(NULL, guest_size, PROT_READ | PROT_WRITE,
+                     MAP_SHARED, fd, 0);  /* VMM I/O view, unprotected */
+
+    uffd = userfaultfd(O_CLOEXEC | O_NONBLOCK);
+    struct uffdio_api api = {
+        .api = UFFD_API,
+        .features = UFFD_FEATURE_RWP | UFFD_FEATURE_RWP_ASYNC,
+    };
+    ioctl(uffd, UFFDIO_API, &api);
+    if (!(api.features & UFFD_FEATURE_RWP))
+        /* RWP unavailable on this kernel/arch -- fall back. */
+    ioctl(uffd, UFFDIO_REGISTER, &(struct uffdio_register){
+        .range = { guest_mem, guest_size },
+        .mode = UFFDIO_REGISTER_MODE_RWP |
+                UFFDIO_REGISTER_MODE_MISSING,
+    });
+
+    /* Tracking loop */
+    while (vm_running) {
+        /* 1. Detection phase (async -- no vCPU stalls) */
+        ioctl(uffd, UFFDIO_RWPROTECT, &(struct uffdio_rwprotect){
+            .range = full_range,
+            .mode = UFFDIO_RWPROTECT_MODE_RWP });
+        sleep(tracking_interval);
+
+        /*
+         * 2. Switch to sync BEFORE scanning. In async mode a vCPU
+         * access races eviction: it would auto-resolve and mark the
+         * page hot just as the VMM writes it out and punches it,
+         * losing the update. Sync mode makes such accesses block and
+         * be delivered, freezing the hot snapshot for the rest of the
+         * iteration.
+         */
+        ioctl(uffd, UFFDIO_SET_MODE,
+              &(struct uffdio_set_mode){
+                  .disable = UFFD_FEATURE_RWP_ASYNC });
+
+        /* 3. Read the hot set: pages touched this interval. */
+        ioctl(pagemap_fd, PAGEMAP_SCAN, &(struct pm_scan_arg){
+            .category_mask = PAGE_IS_ACCESSED,
+            .return_mask = PAGE_IS_ACCESSED,
+            ...
+        });
+
+        /*
+         * 4. Reclaim the file offsets that are NOT in the hot set.
+         * Driving this from the file's offset space (rather than from a
+         * cold PTE scan) also reclaims pages that are cached but not
+         * mapped into guest_mem, e.g. pre-populated content.
+         */
+        for each non-hot offset range:
+            /* Read from io_mem -- bypasses RWP, no fault. */
+            pwrite(storage_fd, (char *)io_mem + off, len, off);
+            /* Drop the page from the shared file. */
+            fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+                      off, len);
+            /*
+             * Wake any vCPU blocked on the RWP fault for this range:
+             * fallocate() does not iterate ctx->fault_pending_wqh.
+             */
+            ioctl(uffd, UFFDIO_WAKE, &(struct uffdio_range){
+                .start = (uintptr_t)guest_mem + off, .len = len });
+
+        /* 5. Resume async tracking */
+        ioctl(uffd, UFFDIO_SET_MODE,
+              &(struct uffdio_set_mode){
+                  .enable = UFFD_FEATURE_RWP_ASYNC });
+    }
+
+During step 4, a vCPU that accesses a ``guest_mem`` offset being evicted
+blocks with a ``UFFD_PAGEFAULT_FLAG_RWP`` fault while the eviction is in
+progress. After ``fallocate()`` punches the page out and ``UFFDIO_WAKE``
+fires, the vCPU retries the access, faults as ``MISSING``, and the
+handler resolves it with ``UFFDIO_COPY`` from storage.
+
+This workflow targets shmem and hugetlbfs (both support a private
+``io_mem`` mapping over the same fd). Anonymous-memory backings need a
+different inner-loop strategy because the VMM has no way to read the
+page without going through the RWP-protected mapping.
+
+QEMU/KVM
+========
+
+QEMU/KVM is using the ``userfaultfd`` syscall to implement postcopy live
+migration. Postcopy live migration is one form of memory
+externalization consisting of a virtual machine running with part or
+all of its memory residing on a different node in the cloud. The
+``userfaultfd`` abstraction is generic enough that not a single line of
+KVM kernel code had to be modified in order to add postcopy live
+migration to QEMU.
+
+Guest async page faults, ``FOLL_NOWAIT`` and all other ``GUP*`` features work
+just fine in combination with userfaults. Userfaults trigger async
+page faults in the guest scheduler so those guest processes that
+aren't waiting for userfaults (i.e. network bound) can keep running in
+the guest vcpus.
+
+It is generally beneficial to run one pass of precopy live migration
+just before starting postcopy live migration, in order to avoid
+generating userfaults for readonly guest regions.
+
+The implementation of postcopy live migration currently uses one
+single bidirectional socket but in the future two different sockets
+will be used (to reduce the latency of the userfaults to the minimum
+possible without having to decrease ``/proc/sys/net/ipv4/tcp_wmem``).
+
+The QEMU in the source node writes all pages that it knows are missing
+in the destination node, into the socket, and the migration thread of
+the QEMU running in the destination node runs ``UFFDIO_COPY|ZEROPAGE``
+ioctls on the ``userfaultfd`` in order to map the received pages into the
+guest (``UFFDIO_ZEROCOPY`` is used if the source page was a zero page).
+
+A different postcopy thread in the destination node listens with
+poll() to the ``userfaultfd`` in parallel. When a ``POLLIN`` event is
+generated after a userfault triggers, the postcopy thread read() from
+the ``userfaultfd`` and receives the fault address (or ``-EAGAIN`` in case the
+userfault was already resolved and waken by a ``UFFDIO_COPY|ZEROPAGE`` run
+by the parallel QEMU migration thread).
+
+After the QEMU postcopy thread (running in the destination node) gets
+the userfault address it writes the information about the missing page
+into the socket. The QEMU source node receives the information and
+roughly "seeks" to that page address and continues sending all
+remaining missing pages from that new page offset. Soon after that
+(just the time to flush the tcp_wmem queue through the network) the
+migration thread in the QEMU running in the destination node will
+receive the page that triggered the userfault and it'll map it as
+usual with the ``UFFDIO_COPY|ZEROPAGE`` (without actually knowing if it
+was spontaneously sent by the source or if it was an urgent page
+requested through a userfault).
+
+By the time the userfaults start, the QEMU in the destination node
+doesn't need to keep any per-page state bitmap relative to the live
+migration around and a single per-page bitmap has to be maintained in
+the QEMU running in the source node to know which pages are still
+missing in the destination node. The bitmap in the source node is
+checked to find which missing pages to send in round robin and we seek
+over it when receiving incoming userfaults. After sending each page of
+course the bitmap is updated accordingly. It's also useful to avoid
+sending the same page twice (in case the userfault is read by the
+postcopy thread just before ``UFFDIO_COPY|ZEROPAGE`` runs in the migration
+thread).
+
+Non-cooperative userfaultfd
+===========================
+
+When the ``userfaultfd`` is monitored by an external manager, the manager
+must be able to track changes in the process virtual memory
+layout. Userfaultfd can notify the manager about such changes using
+the same read(2) protocol as for the page fault notifications. The
+manager has to explicitly enable these events by setting appropriate
+bits in ``uffdio_api.features`` passed to ``UFFDIO_API`` ioctl:
+
+``UFFD_FEATURE_EVENT_FORK``
+	enable ``userfaultfd`` hooks for fork(). When this feature is
+	enabled, the ``userfaultfd`` context of the parent process is
+	duplicated into the newly created process. The manager
+	receives ``UFFD_EVENT_FORK`` with file descriptor of the new
+	``userfaultfd`` context in the ``uffd_msg.fork``.
+
+``UFFD_FEATURE_EVENT_REMAP``
+	enable notifications about mremap() calls. When the
+	non-cooperative process moves a virtual memory area to a
+	different location, the manager will receive
+	``UFFD_EVENT_REMAP``. The ``uffd_msg.remap`` will contain the old and
+	new addresses of the area and its original length.
+
+``UFFD_FEATURE_EVENT_REMOVE``
+	enable notifications about madvise(MADV_REMOVE) and
+	madvise(MADV_DONTNEED) calls. The event ``UFFD_EVENT_REMOVE`` will
+	be generated upon these calls to madvise(). The ``uffd_msg.remove``
+	will contain start and end addresses of the removed area.
+
+``UFFD_FEATURE_EVENT_UNMAP``
+	enable notifications about memory unmapping. The manager will
+	get ``UFFD_EVENT_UNMAP`` with ``uffd_msg.remove`` containing start and
+	end addresses of the unmapped area.
+
+Although the ``UFFD_FEATURE_EVENT_REMOVE`` and ``UFFD_FEATURE_EVENT_UNMAP``
+are pretty similar, they quite differ in the action expected from the
+``userfaultfd`` manager. In the former case, the virtual memory is
+removed, but the area is not, the area remains monitored by the
+``userfaultfd``, and if a page fault occurs in that area it will be
+delivered to the manager. The proper resolution for such page fault is
+to zeromap the faulting address. However, in the latter case, when an
+area is unmapped, either explicitly (with munmap() system call), or
+implicitly (e.g. during mremap()), the area is removed and in turn the
+``userfaultfd`` context for such area disappears too and the manager will
+not get further userland page faults from the removed area. Still, the
+notification is required in order to prevent manager from using
+``UFFDIO_COPY`` on the unmapped area.
+
+Unlike userland page faults which have to be synchronous and require
+explicit or implicit wakeup, all the events are delivered
+asynchronously and the non-cooperative process resumes execution as
+soon as manager executes read(). The ``userfaultfd`` manager should
+carefully synchronize calls to ``UFFDIO_COPY`` with the events
+processing. To aid the synchronization, the ``UFFDIO_COPY`` ioctl will
+return ``-ENOSPC`` when the monitored process exits at the time of
+``UFFDIO_COPY``, and ``-ENOENT``, when the non-cooperative process has changed
+its virtual memory layout simultaneously with outstanding ``UFFDIO_COPY``
+operation.
+
+The current asynchronous model of the event delivery is optimal for
+single threaded non-cooperative ``userfaultfd`` manager implementations. A
+synchronous event delivery model can be added later as a new
+``userfaultfd`` feature to facilitate multithreading enhancements of the
+non cooperative manager, for example to allow ``UFFDIO_COPY`` ioctls to
+run in parallel to the event reception. Single threaded
+implementations should continue to use the current async event
+delivery model instead.
diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
new file mode 100644
index 000000000..2464425c7
--- /dev/null
+++ b/Documentation/admin-guide/mm/zswap.rst
@@ -0,0 +1,138 @@
+=====
+zswap
+=====
+
+Overview
+========
+
+Zswap is a lightweight compressed cache for swap pages. It takes pages that are
+in the process of being swapped out and attempts to compress them into a
+dynamically allocated RAM-based memory pool.  zswap basically trades CPU cycles
+for potentially reduced swap I/O.  This trade-off can also result in a
+significant performance improvement if reads from the compressed cache are
+faster than reads from a swap device.
+
+Some potential benefits:
+
+* Desktop/laptop users with limited RAM capacities can mitigate the
+  performance impact of swapping.
+* Overcommitted guests that share a common I/O resource can
+  dramatically reduce their swap I/O pressure, avoiding heavy handed I/O
+  throttling by the hypervisor. This allows more work to get done with less
+  impact to the guest workload and guests sharing the I/O subsystem
+* Users with SSDs as swap devices can extend the life of the device by
+  drastically reducing life-shortening writes.
+
+Zswap evicts pages from compressed cache on an LRU basis to the backing swap
+device when the compressed pool reaches its size limit.  This requirement had
+been identified in prior community discussions.
+
+Whether Zswap is enabled at the boot time depends on whether
+the ``CONFIG_ZSWAP_DEFAULT_ON`` Kconfig option is enabled or not.
+This setting can then be overridden by providing the kernel command line
+``zswap.enabled=`` option, for example ``zswap.enabled=0``.
+Zswap can also be enabled and disabled at runtime using the sysfs interface.
+An example command to enable zswap at runtime, assuming sysfs is mounted
+at ``/sys``, is::
+
+	echo 1 > /sys/module/zswap/parameters/enabled
+
+When zswap is disabled at runtime it will stop storing pages that are
+being swapped out.  However, it will _not_ immediately write out or fault
+back into memory all of the pages stored in the compressed pool.  The
+pages stored in zswap will remain in the compressed pool until they are
+either invalidated or faulted back into memory.  In order to force all
+pages out of the compressed pool, a swapoff on the swap device(s) will
+fault back into memory all swapped out pages, including those in the
+compressed pool.
+
+Design
+======
+
+Zswap receives pages for compression from the swap subsystem and is able to
+evict pages from its own compressed pool on an LRU basis and write them back to
+the backing swap device in the case that the compressed pool is full.
+
+Zswap makes use of zsmalloc for the managing the compressed memory pool.  Each
+allocation in zsmalloc is not directly accessible by address.  Rather, a handle is
+returned by the allocation routine and that handle must be mapped before being
+accessed.  The compressed memory pool grows on demand and shrinks as compressed
+pages are freed.  The pool is not preallocated.
+
+When a swap page is passed from swapout to zswap, zswap maintains a mapping of
+the swap entry, a combination of the swap type and swap offset, to the zsmalloc
+handle that references that compressed swap page.  This mapping is achieved
+with an xarray per swap type.  The swap offset is the search key for the xarray
+nodes.
+
+During a page fault on a PTE that is a swap entry, the swapin code calls the
+zswap load function to decompress the page into the page allocated by the page
+fault handler.
+
+Once there are no PTEs referencing a swap page stored in zswap (i.e. the count
+in the swap_map goes to 0) the swap code calls the zswap invalidate function
+to free the compressed entry.
+
+Zswap seeks to be simple in its policies.  Sysfs attributes allow for one user
+controlled policy:
+
+* max_pool_percent - The maximum percentage of memory that the compressed
+  pool can occupy.
+
+The default compressor is selected in ``CONFIG_ZSWAP_COMPRESSOR_DEFAULT``
+Kconfig option, but it can be overridden at boot time by setting the
+``compressor`` attribute, e.g. ``zswap.compressor=lzo``.
+It can also be changed at runtime using the sysfs "compressor"
+attribute, e.g.::
+
+	echo lzo > /sys/module/zswap/parameters/compressor
+
+When the compressor parameter is changed at runtime, any existing compressed
+pages are not modified; they are left in their own pool.  When a request is
+made for a page in an old pool, it is uncompressed using its original
+compressor.  Once all pages are removed from an old pool, the pool and its
+compressor are freed.
+
+Some of the pages in zswap are same-value filled pages (i.e. contents of the
+page have same value or repetitive pattern). These pages include zero-filled
+pages and they are handled differently. During store operation, a page is
+checked if it is a same-value filled page before compressing it. If true, the
+compressed length of the page is set to zero and the pattern or same-filled
+value is stored.
+
+To prevent zswap from shrinking pool when zswap is full and there's a high
+pressure on swap (this will result in flipping pages in and out zswap pool
+without any real benefit but with a performance drop for the system), a
+special parameter has been introduced to implement a sort of hysteresis to
+refuse taking pages into zswap pool until it has sufficient space if the limit
+has been hit. To set the threshold at which zswap would start accepting pages
+again after it became full, use the sysfs ``accept_threshold_percent``
+attribute, e. g.::
+
+	echo 80 > /sys/module/zswap/parameters/accept_threshold_percent
+
+Setting this parameter to 100 will disable the hysteresis.
+
+Some users cannot tolerate the swapping that comes with zswap store failures
+and zswap writebacks. Swapping can be disabled entirely (without disabling
+zswap itself) on a cgroup-basis as follows::
+
+	echo 0 > /sys/fs/cgroup/<cgroup-name>/memory.zswap.writeback
+
+Note that if the store failures are recurring (for e.g if the pages are
+incompressible), users can observe reclaim inefficiency after disabling
+writeback (because the same pages might be rejected again and again).
+
+When there is a sizable amount of cold memory residing in the zswap pool, it
+can be advantageous to proactively write these cold pages to swap and reclaim
+the memory for other use cases. By default, the zswap shrinker is disabled.
+User can enable it as follows::
+
+  echo Y > /sys/module/zswap/parameters/shrinker_enabled
+
+This can be enabled at the boot time if ``CONFIG_ZSWAP_SHRINKER_DEFAULT_ON`` is
+selected.
+
+A debugfs interface is provided for various statistic about pool size, number
+of pages stored, same-value filled pages and various counters for the reasons
+pages are rejected.
diff --git a/Documentation/admin-guide/module-signing.rst b/Documentation/admin-guide/module-signing.rst
new file mode 100644
index 000000000..7f2f127dc
--- /dev/null
+++ b/Documentation/admin-guide/module-signing.rst
@@ -0,0 +1,292 @@
+Kernel module signing facility
+------------------------------
+
+.. CONTENTS
+..
+.. - Overview.
+.. - Configuring module signing.
+.. - Generating signing keys.
+.. - Public keys in the kernel.
+.. - Manually signing modules.
+.. - Signed modules and stripping.
+.. - Loading signed modules.
+.. - Non-valid signatures and unsigned modules.
+.. - Administering/protecting the private key.
+
+
+========
+Overview
+========
+
+The kernel module signing facility cryptographically signs modules during
+installation and then checks the signature upon loading the module.  This
+allows increased kernel security by disallowing the loading of unsigned modules
+or modules signed with an invalid key.  Module signing increases security by
+making it harder to load a malicious module into the kernel.  The module
+signature checking is done by the kernel so that it is not necessary to have
+trusted userspace bits.
+
+This facility uses X.509 ITU-T standard certificates to encode the public keys
+involved.  The signatures are not themselves encoded in any industrial standard
+type.  The built-in facility currently only supports the RSA, NIST P-384 ECDSA
+and NIST FIPS-204 ML-DSA public key signing standards (though it is pluggable
+and permits others to be used).  For RSA and ECDSA, the possible hash
+algorithms that can be used are SHA-2 and SHA-3 of sizes 256, 384, and 512 (the
+algorithm is selected by data in the signature); ML-DSA does its own hashing,
+but is allowed to be used with a SHA512 hash for signed attributes.
+
+
+==========================
+Configuring module signing
+==========================
+
+The module signing facility is enabled by going to the
+:menuselection:`Enable Loadable Module Support` section of
+the kernel configuration and turning on::
+
+	CONFIG_MODULE_SIG	"Module signature verification"
+
+This has a number of options available:
+
+ (1) :menuselection:`Require modules to be validly signed`
+     (``CONFIG_MODULE_SIG_FORCE``)
+
+     This specifies how the kernel should deal with a module that has a
+     signature for which the key is not known or a module that is unsigned.
+
+     If this is off (ie. "permissive"), then modules for which the key is not
+     available and modules that are unsigned are permitted, but the kernel will
+     be marked as being tainted, and the concerned modules will be marked as
+     tainted, shown with the character 'E'.
+
+     If this is on (ie. "restrictive"), only modules that have a valid
+     signature that can be verified by a public key in the kernel's possession
+     will be loaded.  All other modules will generate an error.
+
+     Irrespective of the setting here, if the module has a signature block that
+     cannot be parsed, it will be rejected out of hand.
+
+
+ (2) :menuselection:`Automatically sign all modules`
+     (``CONFIG_MODULE_SIG_ALL``)
+
+     If this is on then modules will be automatically signed during the
+     modules_install phase of a build.  If this is off, then the modules must
+     be signed manually using::
+
+	scripts/sign-file
+
+
+ (3) :menuselection:`Which hash algorithm should modules be signed with?`
+
+     This presents a choice of which hash algorithm the installation phase will
+     sign the modules with:
+
+        =============================== ==========================================
+	``CONFIG_MODULE_SIG_SHA256``	:menuselection:`Sign modules with SHA-256`
+	``CONFIG_MODULE_SIG_SHA384``	:menuselection:`Sign modules with SHA-384`
+	``CONFIG_MODULE_SIG_SHA512``	:menuselection:`Sign modules with SHA-512`
+	``CONFIG_MODULE_SIG_SHA3_256``	:menuselection:`Sign modules with SHA3-256`
+	``CONFIG_MODULE_SIG_SHA3_384``	:menuselection:`Sign modules with SHA3-384`
+	``CONFIG_MODULE_SIG_SHA3_512``	:menuselection:`Sign modules with SHA3-512`
+        =============================== ==========================================
+
+     The algorithm selected here will also be built into the kernel (rather
+     than being a module) so that modules signed with that algorithm can have
+     their signatures checked without causing a dependency loop.
+
+
+ (4) :menuselection:`File name or PKCS#11 URI of module signing key`
+     (``CONFIG_MODULE_SIG_KEY``)
+
+     Setting this option to something other than its default of
+     ``certs/signing_key.pem`` will disable the autogeneration of signing keys
+     and allow the kernel modules to be signed with a key of your choosing.
+     The string provided should identify a file containing both a private key
+     and its corresponding X.509 certificate in PEM form, or — on systems where
+     the OpenSSL ENGINE_pkcs11 is functional — a PKCS#11 URI as defined by
+     RFC7512. In the latter case, the PKCS#11 URI should reference both a
+     certificate and a private key.
+
+     If the PEM file containing the private key is encrypted, or if the
+     PKCS#11 token requires a PIN, this can be provided at build time by
+     means of the ``KBUILD_SIGN_PIN`` variable.
+
+
+ (5) :menuselection:`Additional X.509 keys for default system keyring`
+     (``CONFIG_SYSTEM_TRUSTED_KEYS``)
+
+     This option can be set to the filename of a PEM-encoded file containing
+     additional certificates which will be included in the system keyring by
+     default.
+
+Note that enabling module signing adds a dependency on the OpenSSL devel
+packages to the kernel build processes for the tool that does the signing.
+
+
+=======================
+Generating signing keys
+=======================
+
+Cryptographic keypairs are required to generate and check signatures.  A
+private key is used to generate a signature and the corresponding public key is
+used to check it.  The private key is only needed during the build, after which
+it can be deleted or stored securely.  The public key gets built into the
+kernel so that it can be used to check the signatures as the modules are
+loaded.
+
+Under normal conditions, when ``CONFIG_MODULE_SIG_KEY`` is unchanged from its
+default, the kernel build will automatically generate a new keypair using
+openssl if one does not exist in the file::
+
+	certs/signing_key.pem
+
+during the building of vmlinux (the public part of the key needs to be built
+into vmlinux) using parameters in the::
+
+	certs/x509.genkey
+
+file (which is also generated if it does not already exist).
+
+One can select between RSA (``MODULE_SIG_KEY_TYPE_RSA``), ECDSA
+(``MODULE_SIG_KEY_TYPE_ECDSA``) and ML-DSA (``MODULE_SIG_KEY_TYPE_MLDSA_*``) to
+generate an RSA 4k, a NIST P-384 keypair or an ML-DSA 44, 65 or 87 keypair.
+
+It is strongly recommended that you provide your own x509.genkey file.
+
+Most notably, in the x509.genkey file, the req_distinguished_name section
+should be altered from the default::
+
+	[ req_distinguished_name ]
+	#O = Unspecified company
+	CN = Build time autogenerated kernel key
+	#emailAddress = unspecified.user@unspecified.company
+
+The generated RSA key size can also be set with::
+
+	[ req ]
+	default_bits = 4096
+
+
+It is also possible to manually generate the key private/public files using the
+x509.genkey key generation configuration file in the root node of the Linux
+kernel sources tree and the openssl command.  The following is an example to
+generate the public/private key files::
+
+	openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \
+	   -config x509.genkey -outform PEM -out kernel_key.pem \
+	   -keyout kernel_key.pem
+
+The full pathname for the resulting kernel_key.pem file can then be specified
+in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key therein will
+be used instead of an autogenerated keypair.
+
+
+=========================
+Public keys in the kernel
+=========================
+
+The kernel contains a ring of public keys that can be viewed by root.  They're
+in a keyring called ".builtin_trusted_keys" that can be seen by::
+
+	[root@deneb ~]# cat /proc/keys
+	...
+	223c7853 I------     1 perm 1f030000     0     0 keyring   .builtin_trusted_keys: 1
+	302d2d52 I------     1 perm 1f010000     0     0 asymmetri Fedora kernel signing key: d69a84e6bce3d216b979e9505b3e3ef9a7118079: X509.RSA a7118079 []
+	...
+
+Beyond the public key generated specifically for module signing, additional
+trusted certificates can be provided in a PEM-encoded file referenced by the
+``CONFIG_SYSTEM_TRUSTED_KEYS`` configuration option.
+
+Further, the architecture code may take public keys from a hardware store and
+add those in also (e.g. from the UEFI key database).
+
+Finally, it is possible to add additional public keys by doing::
+
+	keyctl padd asymmetric "" [.builtin_trusted_keys-ID] <[key-file]
+
+e.g.::
+
+	keyctl padd asymmetric "" 0x223c7853 <my_public_key.x509
+
+Note, however, that the kernel will only permit keys to be added to
+``.builtin_trusted_keys`` **if** the new key's X.509 wrapper is validly signed by a key
+that is already resident in the ``.builtin_trusted_keys`` at the time the key was added.
+
+
+========================
+Manually signing modules
+========================
+
+To manually sign a module, use the scripts/sign-file tool available in
+the Linux kernel source tree.  The script requires 4 arguments:
+
+	1.  The hash algorithm (e.g., sha256)
+	2.  The private key filename or PKCS#11 URI
+	3.  The public key filename
+	4.  The kernel module to be signed
+
+The following is an example to sign a kernel module::
+
+	scripts/sign-file sha512 kernel-signkey.priv \
+		kernel-signkey.x509 module.ko
+
+The hash algorithm used does not have to match the one configured, but if it
+doesn't, you should make sure that hash algorithm is either built into the
+kernel or can be loaded without requiring itself.
+
+If the private key requires a passphrase or PIN, it can be provided in the
+$KBUILD_SIGN_PIN environment variable.
+
+
+============================
+Signed modules and stripping
+============================
+
+A signed module has a digital signature simply appended at the end.  The string
+``~Module signature appended~.`` at the end of the module's file confirms that a
+signature is present but it does not confirm that the signature is valid!
+
+Signed modules are BRITTLE as the signature is outside of the defined ELF
+container.  Thus they MAY NOT be stripped once the signature is computed and
+attached.  Note the entire module is the signed payload, including any and all
+debug information present at the time of signing.
+
+
+======================
+Loading signed modules
+======================
+
+Modules are loaded with insmod, modprobe, ``init_module()`` or
+``finit_module()``, exactly as for unsigned modules as no processing is
+done in userspace.  The signature checking is all done within the kernel.
+
+
+=========================================
+Non-valid signatures and unsigned modules
+=========================================
+
+If ``CONFIG_MODULE_SIG_FORCE`` is enabled or module.sig_enforce=1 is supplied on
+the kernel command line, the kernel will only load validly signed modules
+for which it has a public key.   Otherwise, it will also load modules that are
+unsigned.   Any module for which the kernel has a key, but which proves to have
+a signature mismatch will not be permitted to load.
+
+Any module that has an unparsable signature will be rejected.
+
+
+=========================================
+Administering/protecting the private key
+=========================================
+
+Since the private key is used to sign modules, viruses and malware could use
+the private key to sign modules and compromise the operating system.  The
+private key must be either destroyed or moved to a secure location and not kept
+in the root node of the kernel source tree.
+
+If you use the same private key to sign modules for multiple kernel
+configurations, you must ensure that the module version information is
+sufficient to prevent loading a module into a different kernel.  Either
+set ``CONFIG_MODVERSIONS=y`` or ensure that each configuration has a different
+kernel release string by changing ``EXTRAVERSION`` or ``CONFIG_LOCALVERSION``.
diff --git a/Documentation/admin-guide/mono.rst b/Documentation/admin-guide/mono.rst
new file mode 100644
index 000000000..c6dab5680
--- /dev/null
+++ b/Documentation/admin-guide/mono.rst
@@ -0,0 +1,70 @@
+Mono(tm) Binary Kernel Support for Linux
+-----------------------------------------
+
+To configure Linux to automatically execute Mono-based .NET binaries
+(in the form of .exe files) without the need to use the mono CLR
+wrapper, you can use the BINFMT_MISC kernel support.
+
+This will allow you to execute Mono-based .NET binaries just like any
+other program after you have done the following:
+
+1) You MUST FIRST install the Mono CLR support, either by downloading
+   a binary package, a source tarball or by installing from Git. Binary
+   packages for several distributions can be found at:
+
+	https://www.mono-project.com/download/
+
+   Instructions for compiling Mono can be found at:
+
+	https://www.mono-project.com/docs/compiling-mono/linux/
+
+   Once the Mono CLR support has been installed, just check that
+   ``/usr/bin/mono`` (which could be located elsewhere, for example
+   ``/usr/local/bin/mono``) is working.
+
+2) You have to compile BINFMT_MISC either as a module or into
+   the kernel (``CONFIG_BINFMT_MISC``) and set it up properly.
+   If you choose to compile it as a module, you will have
+   to insert it manually with modprobe/insmod, as kmod
+   cannot be easily supported with binfmt_misc.
+   Read the file ``binfmt_misc.txt`` in this directory to know
+   more about the configuration process.
+
+3) Add the following entries to ``/etc/rc.local`` or similar script
+   to be run at system startup:
+
+   .. code-block:: sh
+
+    # Insert BINFMT_MISC module into the kernel
+    if [ ! -e /proc/sys/fs/binfmt_misc/register ]; then
+        /sbin/modprobe binfmt_misc
+	# Some distributions, like Fedora Core, perform
+	# the following command automatically when the
+	# binfmt_misc module is loaded into the kernel
+	# or during normal boot up (systemd-based systems).
+	# Thus, it is possible that the following line
+	# is not needed at all.
+	mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
+    fi
+
+    # Register support for .NET CLR binaries
+    if [ -e /proc/sys/fs/binfmt_misc/register ]; then
+	# Replace /usr/bin/mono with the correct pathname to
+	# the Mono CLR runtime (usually /usr/local/bin/mono
+	# when compiling from sources or CVS).
+        echo ':CLR:M::MZ::/usr/bin/mono:' > /proc/sys/fs/binfmt_misc/register
+    else
+        echo "No binfmt_misc support"
+        exit 1
+    fi
+
+4) Check that ``.exe`` binaries can be ran without the need of a
+   wrapper script, simply by launching the ``.exe`` file directly
+   from a command prompt, for example::
+
+	/usr/bin/xsd.exe
+
+   .. note::
+
+      If this fails with a permission denied error, check
+      that the ``.exe`` file has execute permissions.
diff --git a/Documentation/admin-guide/namespaces/compatibility-list.rst b/Documentation/admin-guide/namespaces/compatibility-list.rst
new file mode 100644
index 000000000..318800b2a
--- /dev/null
+++ b/Documentation/admin-guide/namespaces/compatibility-list.rst
@@ -0,0 +1,43 @@
+=============================
+Namespaces compatibility list
+=============================
+
+This document contains the information about the problems user
+may have when creating tasks living in different namespaces.
+
+Here's the summary. This matrix shows the known problems, that
+occur when tasks share some namespace (the columns) while living
+in different other namespaces (the rows):
+
+====	===	===	===	===	====	===
+-	UTS	IPC	VFS	PID	User	Net
+====	===	===	===	===	====	===
+UTS	 X
+IPC		 X	 1
+VFS			 X
+PID		 1	 1	 X
+User		 2	 2		 X
+Net						 X
+====	===	===	===	===	====	===
+
+1. Both the IPC and the PID namespaces provide IDs to address
+   object inside the kernel. E.g. semaphore with IPCID or
+   process group with pid.
+
+   In both cases, tasks shouldn't try exposing this ID to some
+   other task living in a different namespace via a shared filesystem
+   or IPC shmem/message. The fact is that this ID is only valid
+   within the namespace it was obtained in and may refer to some
+   other object in another namespace.
+
+2. Intentionally, two equal user IDs in different user namespaces
+   should not be equal from the VFS point of view. In other
+   words, user 10 in one user namespace shouldn't have the same
+   access permissions to files, belonging to user 10 in another
+   namespace.
+
+   The same is true for the IPC namespaces being shared - two users
+   from different user namespaces should not access the same IPC objects
+   even having equal UIDs.
+
+   But currently this is not so.
diff --git a/Documentation/admin-guide/namespaces/index.rst b/Documentation/admin-guide/namespaces/index.rst
new file mode 100644
index 000000000..384f2e0f3
--- /dev/null
+++ b/Documentation/admin-guide/namespaces/index.rst
@@ -0,0 +1,11 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+Namespaces
+==========
+
+.. toctree::
+   :maxdepth: 1
+
+   compatibility-list
+   resource-control
diff --git a/Documentation/admin-guide/namespaces/resource-control.rst b/Documentation/admin-guide/namespaces/resource-control.rst
new file mode 100644
index 000000000..553a44803
--- /dev/null
+++ b/Documentation/admin-guide/namespaces/resource-control.rst
@@ -0,0 +1,18 @@
+====================================
+User namespaces and resource control
+====================================
+
+The kernel contains many kinds of objects that either don't have
+individual limits or that have limits which are ineffective when
+a set of processes is allowed to switch their UID. On a system
+where the admins don't trust their users or their users' programs,
+user namespaces expose the system to potential misuse of resources.
+
+In order to mitigate this, we recommend that admins enable memory
+control groups on any system that enables user namespaces.
+Furthermore, we recommend that admins configure the memory control
+groups to limit the maximum memory usable by any untrusted user.
+
+Memory control groups can be configured by installing the libcgroup
+package present on most distros editing /etc/cgrules.conf,
+/etc/cgconfig.conf and setting up libpam-cgroup.
diff --git a/Documentation/admin-guide/nfs/index.rst b/Documentation/admin-guide/nfs/index.rst
new file mode 100644
index 000000000..3601a708f
--- /dev/null
+++ b/Documentation/admin-guide/nfs/index.rst
@@ -0,0 +1,14 @@
+=============
+NFS
+=============
+
+.. toctree::
+    :maxdepth: 1
+
+    nfs-client
+    nfsroot
+    nfs-rdma
+    nfsd-admin-interfaces
+    nfs-idmapper
+    pnfs-block-server
+    pnfs-scsi-server
diff --git a/Documentation/admin-guide/nfs/nfs-client.rst b/Documentation/admin-guide/nfs/nfs-client.rst
new file mode 100644
index 000000000..36760685d
--- /dev/null
+++ b/Documentation/admin-guide/nfs/nfs-client.rst
@@ -0,0 +1,144 @@
+==========
+NFS Client
+==========
+
+The NFS client
+==============
+
+The NFS version 2 protocol was first documented in RFC1094 (March 1989).
+Since then two more major releases of NFS have been published, with NFSv3
+being documented in RFC1813 (June 1995), and NFSv4 in RFC3530 (April
+2003).
+
+The Linux NFS client currently supports all the above published versions,
+and work is in progress on adding support for minor version 1 of the NFSv4
+protocol.
+
+The purpose of this document is to provide information on some of the
+special features of the NFS client that can be configured by system
+administrators.
+
+
+The nfs4_unique_id parameter
+============================
+
+NFSv4 requires clients to identify themselves to servers with a unique
+string.  File open and lock state shared between one client and one server
+is associated with this identity.  To support robust NFSv4 state recovery
+and transparent state migration, this identity string must not change
+across client reboots.
+
+Without any other intervention, the Linux client uses a string that contains
+the local system's node name.  System administrators, however, often do not
+take care to ensure that node names are fully qualified and do not change
+over the lifetime of a client system.  Node names can have other
+administrative requirements that require particular behavior that does not
+work well as part of an nfs_client_id4 string.
+
+The nfs.nfs4_unique_id boot parameter specifies a unique string that can be
+used together with  a system's node name when an NFS client identifies itself to
+a server.  Thus, if the system's node name is not unique, its
+nfs.nfs4_unique_id can help prevent collisions with other clients.
+
+The nfs.nfs4_unique_id string is typically a UUID, though it can contain
+anything that is believed to be unique across all NFS clients.  An
+nfs4_unique_id string should be chosen when a client system is installed,
+just as a system's root file system gets a fresh UUID in its label at
+install time.
+
+The string should remain fixed for the lifetime of the client.  It can be
+changed safely if care is taken that the client shuts down cleanly and all
+outstanding NFSv4 state has expired, to prevent loss of NFSv4 state.
+
+This string can be stored in an NFS client's grub.conf, or it can be provided
+via a net boot facility such as PXE.  It may also be specified as an nfs.ko
+module parameter.
+
+This uniquifier string will be the same for all NFS clients running in
+containers unless it is overridden by a value written to
+/sys/fs/nfs/net/nfs_client/identifier which will be local to the network
+namespace of the process which writes.
+
+
+The DNS resolver
+================
+
+NFSv4 allows for one server to refer the NFS client to data that has been
+migrated onto another server by means of the special "fs_locations"
+attribute. See `RFC3530 Section 6: Filesystem Migration and Replication`_ and
+`Implementation Guide for Referrals in NFSv4`_.
+
+.. _RFC3530 Section 6\: Filesystem Migration and Replication: https://tools.ietf.org/html/rfc3530#section-6
+.. _Implementation Guide for Referrals in NFSv4: https://tools.ietf.org/html/draft-ietf-nfsv4-referrals-00
+
+The fs_locations information can take the form of either an ip address and
+a path, or a DNS hostname and a path. The latter requires the NFS client to
+do a DNS lookup in order to mount the new volume, and hence the need for an
+upcall to allow userland to provide this service.
+
+Assuming that the user has the 'rpc_pipefs' filesystem mounted in the usual
+/var/lib/nfs/rpc_pipefs, the upcall consists of the following steps:
+
+   (1) The process checks the dns_resolve cache to see if it contains a
+       valid entry. If so, it returns that entry and exits.
+
+   (2) If no valid entry exists, the helper script '/sbin/nfs_cache_getent'
+       (may be changed using the 'nfs.cache_getent' kernel boot parameter)
+       is run, with two arguments:
+       - the cache name, "dns_resolve"
+       - the hostname to resolve
+
+   (3) After looking up the corresponding ip address, the helper script
+       writes the result into the rpc_pipefs pseudo-file
+       '/var/lib/nfs/rpc_pipefs/cache/dns_resolve/channel'
+       in the following (text) format:
+
+		"<ip address> <hostname> <ttl>\n"
+
+       Where <ip address> is in the usual IPv4 (123.456.78.90) or IPv6
+       (ffee:ddcc:bbaa:9988:7766:5544:3322:1100, ffee::1100, ...) format.
+       <hostname> is identical to the second argument of the helper
+       script, and <ttl> is the 'time to live' of this cache entry (in
+       units of seconds).
+
+       .. note::
+            If <ip address> is invalid, say the string "0", then a negative
+            entry is created, which will cause the kernel to treat the hostname
+            as having no valid DNS translation.
+
+
+
+
+A basic sample /sbin/nfs_cache_getent
+=====================================
+.. code-block:: sh
+
+    #!/bin/bash
+    #
+    ttl=600
+    #
+    cut=/usr/bin/cut
+    getent=/usr/bin/getent
+    rpc_pipefs=/var/lib/nfs/rpc_pipefs
+    #
+    die()
+    {
+        echo "Usage: $0 cache_name entry_name"
+        exit 1
+    }
+
+    [ $# -lt 2 ] && die
+    cachename="$1"
+    cache_path=${rpc_pipefs}/cache/${cachename}/channel
+
+    case "${cachename}" in
+        dns_resolve)
+            name="$2"
+            result="$(${getent} hosts ${name} | ${cut} -f1 -d\ )"
+            [ -z "${result}" ] && result="0"
+            ;;
+        *)
+            die
+            ;;
+    esac
+    echo "${result} ${name} ${ttl}" >${cache_path}
diff --git a/Documentation/admin-guide/nfs/nfs-idmapper.rst b/Documentation/admin-guide/nfs/nfs-idmapper.rst
new file mode 100644
index 000000000..58b8e6341
--- /dev/null
+++ b/Documentation/admin-guide/nfs/nfs-idmapper.rst
@@ -0,0 +1,78 @@
+=============
+NFS ID Mapper
+=============
+
+Id mapper is used by NFS to translate user and group ids into names, and to
+translate user and group names into ids.  Part of this translation involves
+performing an upcall to userspace to request the information.  There are two
+ways NFS could obtain this information: placing a call to /sbin/request-key
+or by placing a call to the rpc.idmap daemon.
+
+NFS will attempt to call /sbin/request-key first.  If this succeeds, the
+result will be cached using the generic request-key cache.  This call should
+only fail if /etc/request-key.conf is not configured for the id_resolver key
+type, see the "Configuring" section below if you wish to use the request-key
+method.
+
+If the call to /sbin/request-key fails (if /etc/request-key.conf is not
+configured with the id_resolver key type), then the idmapper will ask the
+legacy rpc.idmap daemon for the id mapping.  This result will be stored
+in a custom NFS idmap cache.
+
+
+Configuring
+===========
+
+The file /etc/request-key.conf will need to be modified so /sbin/request-key can
+direct the upcall.  The following line should be added:
+
+``#OP	TYPE	DESCRIPTION	CALLOUT INFO	PROGRAM ARG1 ARG2 ARG3 ...``
+``#======	=======	===============	===============	===============================``
+``create	id_resolver	*	*		/usr/sbin/nfs.idmap %k %d 600``
+
+
+This will direct all id_resolver requests to the program /usr/sbin/nfs.idmap.
+The last parameter, 600, defines how many seconds into the future the key will
+expire.  This parameter is optional for /usr/sbin/nfs.idmap.  When the timeout
+is not specified, nfs.idmap will default to 600 seconds.
+
+id mapper uses for key descriptions::
+
+	  uid:  Find the UID for the given user
+	  gid:  Find the GID for the given group
+	 user:  Find the user  name for the given UID
+	group:  Find the group name for the given GID
+
+You can handle any of these individually, rather than using the generic upcall
+program.  If you would like to use your own program for a uid lookup then you
+would edit your request-key.conf so it look similar to this:
+
+``#OP	TYPE	DESCRIPTION	CALLOUT INFO	PROGRAM ARG1 ARG2 ARG3 ...``
+``#======	=======	===============	===============	===============================``
+``create	id_resolver	uid:*	*		/some/other/program %k %d 600``
+``create	id_resolver	*	*		/usr/sbin/nfs.idmap %k %d 600``
+
+
+Notice that the new line was added above the line for the generic program.
+request-key will find the first matching line and corresponding program.  In
+this case, /some/other/program will handle all uid lookups and
+/usr/sbin/nfs.idmap will handle gid, user, and group lookups.
+
+See Documentation/security/keys/request-key.rst for more information
+about the request-key function.
+
+
+nfs.idmap
+=========
+
+nfs.idmap is designed to be called by request-key, and should not be run "by
+hand".  This program takes two arguments, a serialized key and a key
+description.  The serialized key is first converted into a key_serial_t, and
+then passed as an argument to keyctl_instantiate (both are part of keyutils.h).
+
+The actual lookups are performed by functions found in nfsidmap.h.  nfs.idmap
+determines the correct function to call by looking at the first part of the
+description string.  For example, a uid lookup description will appear as
+"uid:user@domain".
+
+nfs.idmap will return 0 if the key was instantiated, and non-zero otherwise.
diff --git a/Documentation/admin-guide/nfs/nfs-rdma.rst b/Documentation/admin-guide/nfs/nfs-rdma.rst
new file mode 100644
index 000000000..f137485f8
--- /dev/null
+++ b/Documentation/admin-guide/nfs/nfs-rdma.rst
@@ -0,0 +1,292 @@
+===================
+Setting up NFS/RDMA
+===================
+
+:Author:
+  NetApp and Open Grid Computing (May 29, 2008)
+
+.. warning::
+  This document is probably obsolete.
+
+Overview
+========
+
+This document describes how to install and setup the Linux NFS/RDMA client
+and server software.
+
+The NFS/RDMA client was first included in Linux 2.6.24. The NFS/RDMA server
+was first included in the following release, Linux 2.6.25.
+
+In our testing, we have obtained excellent performance results (full 10Gbit
+wire bandwidth at minimal client CPU) under many workloads. The code passes
+the full Connectathon test suite and operates over both Infiniband and iWARP
+RDMA adapters.
+
+Getting Help
+============
+
+If you get stuck, you can ask questions on the
+nfs-rdma-devel@lists.sourceforge.net mailing list.
+
+Installation
+============
+
+These instructions are a step by step guide to building a machine for
+use with NFS/RDMA.
+
+- Install an RDMA device
+
+  Any device supported by the drivers in drivers/infiniband/hw is acceptable.
+
+  Testing has been performed using several Mellanox-based IB cards, the
+  Ammasso AMS1100 iWARP adapter, and the Chelsio cxgb3 iWARP adapter.
+
+- Install a Linux distribution and tools
+
+  The first kernel release to contain both the NFS/RDMA client and server was
+  Linux 2.6.25  Therefore, a distribution compatible with this and subsequent
+  Linux kernel release should be installed.
+
+  The procedures described in this document have been tested with
+  distributions from Red Hat's Fedora Project (http://fedora.redhat.com/).
+
+- Install nfs-utils-1.1.2 or greater on the client
+
+  An NFS/RDMA mount point can be obtained by using the mount.nfs command in
+  nfs-utils-1.1.2 or greater (nfs-utils-1.1.1 was the first nfs-utils
+  version with support for NFS/RDMA mounts, but for various reasons we
+  recommend using nfs-utils-1.1.2 or greater). To see which version of
+  mount.nfs you are using, type:
+
+  .. code-block:: sh
+
+    $ /sbin/mount.nfs -V
+
+  If the version is less than 1.1.2 or the command does not exist,
+  you should install the latest version of nfs-utils.
+
+  Download the latest package from: https://www.kernel.org/pub/linux/utils/nfs
+
+  Uncompress the package and follow the installation instructions.
+
+  If you will not need the idmapper and gssd executables (you do not need
+  these to create an NFS/RDMA enabled mount command), the installation
+  process can be simplified by disabling these features when running
+  configure:
+
+  .. code-block:: sh
+
+    $ ./configure --disable-gss --disable-nfsv4
+
+  To build nfs-utils you will need the tcp_wrappers package installed. For
+  more information on this see the package's README and INSTALL files.
+
+  After building the nfs-utils package, there will be a mount.nfs binary in
+  the utils/mount directory. This binary can be used to initiate NFS v2, v3,
+  or v4 mounts. To initiate a v4 mount, the binary must be called
+  mount.nfs4.  The standard technique is to create a symlink called
+  mount.nfs4 to mount.nfs.
+
+  This mount.nfs binary should be installed at /sbin/mount.nfs as follows:
+
+  .. code-block:: sh
+
+    $ sudo cp utils/mount/mount.nfs /sbin/mount.nfs
+
+  In this location, mount.nfs will be invoked automatically for NFS mounts
+  by the system mount command.
+
+    .. note::
+      mount.nfs and therefore nfs-utils-1.1.2 or greater is only needed
+      on the NFS client machine. You do not need this specific version of
+      nfs-utils on the server. Furthermore, only the mount.nfs command from
+      nfs-utils-1.1.2 is needed on the client.
+
+- Install a Linux kernel with NFS/RDMA
+
+  The NFS/RDMA client and server are both included in the mainline Linux
+  kernel version 2.6.25 and later. This and other versions of the Linux
+  kernel can be found at: https://www.kernel.org/pub/linux/kernel/
+
+  Download the sources and place them in an appropriate location.
+
+- Configure the RDMA stack
+
+  Make sure your kernel configuration has RDMA support enabled. Under
+  Device Drivers -> InfiniBand support, update the kernel configuration
+  to enable InfiniBand support [NOTE: the option name is misleading. Enabling
+  InfiniBand support is required for all RDMA devices (IB, iWARP, etc.)].
+
+  Enable the appropriate IB HCA support (mlx4, mthca, ehca, ipath, etc.) or
+  iWARP adapter support (amso, cxgb3, etc.).
+
+  If you are using InfiniBand, be sure to enable IP-over-InfiniBand support.
+
+- Configure the NFS client and server
+
+  Your kernel configuration must also have NFS file system support and/or
+  NFS server support enabled. These and other NFS related configuration
+  options can be found under File Systems -> Network File Systems.
+
+- Build, install, reboot
+
+  The NFS/RDMA code will be enabled automatically if NFS and RDMA
+  are turned on. The NFS/RDMA client and server are configured via the hidden
+  SUNRPC_XPRT_RDMA config option that depends on SUNRPC and INFINIBAND. The
+  value of SUNRPC_XPRT_RDMA will be:
+
+    #. N if either SUNRPC or INFINIBAND are N, in this case the NFS/RDMA client
+       and server will not be built
+
+    #. M if both SUNRPC and INFINIBAND are on (M or Y) and at least one is M,
+       in this case the NFS/RDMA client and server will be built as modules
+
+    #. Y if both SUNRPC and INFINIBAND are Y, in this case the NFS/RDMA client
+       and server will be built into the kernel
+
+  Therefore, if you have followed the steps above and turned no NFS and RDMA,
+  the NFS/RDMA client and server will be built.
+
+  Build a new kernel, install it, boot it.
+
+Check RDMA and NFS Setup
+========================
+
+Before configuring the NFS/RDMA software, it is a good idea to test
+your new kernel to ensure that the kernel is working correctly.
+In particular, it is a good idea to verify that the RDMA stack
+is functioning as expected and standard NFS over TCP/IP and/or UDP/IP
+is working properly.
+
+- Check RDMA Setup
+
+  If you built the RDMA components as modules, load them at
+  this time. For example, if you are using a Mellanox Tavor/Sinai/Arbel
+  card:
+
+  .. code-block:: sh
+
+    $ modprobe ib_mthca
+    $ modprobe ib_ipoib
+
+  If you are using InfiniBand, make sure there is a Subnet Manager (SM)
+  running on the network. If your IB switch has an embedded SM, you can
+  use it. Otherwise, you will need to run an SM, such as OpenSM, on one
+  of your end nodes.
+
+  If an SM is running on your network, you should see the following:
+
+  .. code-block:: sh
+
+    $ cat /sys/class/infiniband/driverX/ports/1/state
+    4: ACTIVE
+
+  where driverX is mthca0, ipath5, ehca3, etc.
+
+  To further test the InfiniBand software stack, use IPoIB (this
+  assumes you have two IB hosts named host1 and host2):
+
+  .. code-block:: sh
+
+    host1$ ip link set dev ib0 up
+    host1$ ip address add dev ib0 a.b.c.x
+    host2$ ip link set dev ib0 up
+    host2$ ip address add dev ib0 a.b.c.y
+    host1$ ping a.b.c.y
+    host2$ ping a.b.c.x
+
+  For other device types, follow the appropriate procedures.
+
+- Check NFS Setup
+
+  For the NFS components enabled above (client and/or server),
+  test their functionality over standard Ethernet using TCP/IP or UDP/IP.
+
+NFS/RDMA Setup
+==============
+
+We recommend that you use two machines, one to act as the client and
+one to act as the server.
+
+One time configuration:
+-----------------------
+
+- On the server system, configure the /etc/exports file and start the NFS/RDMA server.
+
+  Exports entries with the following formats have been tested::
+
+  /vol0   192.168.0.47(fsid=0,rw,async,insecure,no_root_squash)
+  /vol0   192.168.0.0/255.255.255.0(fsid=0,rw,async,insecure,no_root_squash)
+
+  The IP address(es) is(are) the client's IPoIB address for an InfiniBand
+  HCA or the client's iWARP address(es) for an RNIC.
+
+  .. note::
+    The "insecure" option must be used because the NFS/RDMA client does
+    not use a reserved port.
+
+Each time a machine boots:
+--------------------------
+
+- Load and configure the RDMA drivers
+
+  For InfiniBand using a Mellanox adapter:
+
+  .. code-block:: sh
+
+    $ modprobe ib_mthca
+    $ modprobe ib_ipoib
+    $ ip li set dev ib0 up
+    $ ip addr add dev ib0 a.b.c.d
+
+  .. note::
+    Please use unique addresses for the client and server!
+
+- Start the NFS server
+
+  If the NFS/RDMA server was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
+  kernel config), load the RDMA transport module:
+
+  .. code-block:: sh
+
+    $ modprobe svcrdma
+
+  Regardless of how the server was built (module or built-in), start the
+  server:
+
+  .. code-block:: sh
+
+    $ /etc/init.d/nfs start
+
+  or
+
+  .. code-block:: sh
+
+    $ service nfs start
+
+  Instruct the server to listen on the RDMA transport:
+
+  .. code-block:: sh
+
+    $ echo rdma 20049 > /proc/fs/nfsd/portlist
+
+- On the client system
+
+  If the NFS/RDMA client was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
+  kernel config), load the RDMA client module:
+
+  .. code-block:: sh
+
+    $ modprobe xprtrdma.ko
+
+  Regardless of how the client was built (module or built-in), use this
+  command to mount the NFS/RDMA server:
+
+  .. code-block:: sh
+
+    $ mount -o rdma,port=20049 <IPoIB-server-name-or-address>:/<export> /mnt
+
+  To verify that the mount is using RDMA, run "cat /proc/mounts" and check
+  the "proto" field for the given mount.
+
+  Congratulations! You're using NFS/RDMA!
diff --git a/Documentation/admin-guide/nfs/nfsd-admin-interfaces.rst b/Documentation/admin-guide/nfs/nfsd-admin-interfaces.rst
new file mode 100644
index 000000000..c05926f79
--- /dev/null
+++ b/Documentation/admin-guide/nfs/nfsd-admin-interfaces.rst
@@ -0,0 +1,40 @@
+==================================
+Administrative interfaces for nfsd
+==================================
+
+Note that normally these interfaces are used only by the utilities in
+nfs-utils.
+
+nfsd is controlled mainly by pseudofiles under the "nfsd" filesystem,
+which is normally mounted at /proc/fs/nfsd/.
+
+The server is always started by the first write of a nonzero value to
+nfsd/threads.
+
+Before doing that, NFSD can be told which sockets to listen on by
+writing to nfsd/portlist; that write may be:
+
+	-  an ascii-encoded file descriptor, which should refer to a
+	   bound (and listening, for tcp) socket, or
+	-  "transportname port", where transportname is currently either
+	   "udp", "tcp", or "rdma".
+
+If nfsd is started without doing any of these, then it will create one
+udp and one tcp listener at port 2049 (see nfsd_init_socks).
+
+On startup, nfsd and lockd grace periods start. nfsd is shut down by a write of
+0 to nfsd/threads.  All locks and state are thrown away at that point.
+
+Between startup and shutdown, the number of threads may be adjusted up
+or down by additional writes to nfsd/threads or by writes to
+nfsd/pool_threads.
+
+For more detail about files under nfsd/ and what they control, see
+fs/nfsd/nfsctl.c; most of them have detailed comments.
+
+Implementation notes
+====================
+
+Note that the rpc server requires the caller to serialize addition and
+removal of listening sockets, and startup and shutdown of the server.
+For nfsd this is done using nfsd_mutex.
diff --git a/Documentation/admin-guide/nfs/nfsroot.rst b/Documentation/admin-guide/nfs/nfsroot.rst
new file mode 100644
index 000000000..06990309c
--- /dev/null
+++ b/Documentation/admin-guide/nfs/nfsroot.rst
@@ -0,0 +1,364 @@
+===============================================
+Mounting the root filesystem via NFS (nfsroot)
+===============================================
+
+:Authors:
+	Written 1996 by Gero Kuhlmann <gero@gkminix.han.de>
+
+	Updated 1997 by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
+
+	Updated 2006 by Nico Schottelius <nico-kernel-nfsroot@schottelius.org>
+
+	Updated 2006 by Horms <horms@verge.net.au>
+
+	Updated 2018 by Chris Novakovic <chris@chrisn.me.uk>
+
+
+
+In order to use a diskless system, such as an X-terminal or printer server for
+example, it is necessary for the root filesystem to be present on a non-disk
+device. This may be an initramfs (see
+Documentation/filesystems/ramfs-rootfs-initramfs.rst), a ramdisk (see
+Documentation/admin-guide/initrd.rst) or a filesystem mounted via NFS. The
+following text describes on how to use NFS for the root filesystem. For the rest
+of this text 'client' means the diskless system, and 'server' means the NFS
+server.
+
+
+
+
+Enabling nfsroot capabilities
+=============================
+
+In order to use nfsroot, NFS client support needs to be selected as
+built-in during configuration. Once this has been selected, the nfsroot
+option will become available, which should also be selected.
+
+In the networking options, kernel level autoconfiguration can be selected,
+along with the types of autoconfiguration to support. Selecting all of
+DHCP, BOOTP and RARP is safe.
+
+
+
+
+Kernel command line
+===================
+
+When the kernel has been loaded by a boot loader (see below) it needs to be
+told what root fs device to use. And in the case of nfsroot, where to find
+both the server and the name of the directory on the server to mount as root.
+This can be established using the following kernel command line parameters:
+
+
+root=/dev/nfs
+  This is necessary to enable the pseudo-NFS-device. Note that it's not a
+  real device but just a synonym to tell the kernel to use NFS instead of
+  a real device.
+
+
+nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
+  If the `nfsroot' parameter is NOT given on the command line,
+  the default ``"/tftpboot/%s"`` will be used.
+
+  <server-ip>	Specifies the IP address of the NFS server.
+		The default address is determined by the ip parameter
+		(see below). This parameter allows the use of different
+		servers for IP autoconfiguration and NFS.
+
+  <root-dir>	Name of the directory on the server to mount as root.
+		If there is a "%s" token in the string, it will be
+		replaced by the ASCII-representation of the client's
+		IP address.
+
+  <nfs-options>	Standard NFS options. All options are separated by commas.
+		The following defaults are used::
+
+			port		= as given by server portmap daemon
+			rsize		= 4096
+			wsize		= 4096
+			timeo		= 7
+			retrans		= 3
+			acregmin	= 3
+			acregmax	= 60
+			acdirmin	= 30
+			acdirmax	= 60
+			flags		= hard, nointr, noposix, cto, ac
+
+
+ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>:<dns0-ip>:<dns1-ip>:<ntp0-ip>
+  This parameter tells the kernel how to configure IP addresses of devices
+  and also how to set up the IP routing table. It was originally called
+  nfsaddrs, but now the boot-time IP configuration works independently of
+  NFS, so it was renamed to ip and the old name remained as an alias for
+  compatibility reasons.
+
+  If this parameter is missing from the kernel command line, all fields are
+  assumed to be empty, and the defaults mentioned below apply. In general
+  this means that the kernel tries to configure everything using
+  autoconfiguration.
+
+  The <autoconf> parameter can appear alone as the value to the ip
+  parameter (without all the ':' characters before).  If the value is
+  "ip=off" or "ip=none", no autoconfiguration will take place, otherwise
+  autoconfiguration will take place.  The most common way to use this
+  is "ip=dhcp".
+
+  <client-ip>	IP address of the client.
+  		Default:  Determined using autoconfiguration.
+
+  <server-ip>	IP address of the NFS server.
+		If RARP is used to determine
+		the client address and this parameter is NOT empty only
+		replies from the specified server are accepted.
+
+		Only required for NFS root. That is autoconfiguration
+		will not be triggered if it is missing and NFS root is not
+		in operation.
+
+		Value is exported to /proc/net/pnp with the prefix "bootserver "
+		(see below).
+
+		Default: Determined using autoconfiguration.
+		The address of the autoconfiguration server is used.
+
+  <gw-ip>	IP address of a gateway if the server is on a different subnet.
+		Default: Determined using autoconfiguration.
+
+  <netmask>	Netmask for local network interface.
+		If unspecified the netmask is derived from the client IP address
+		assuming classful addressing.
+
+		Default:  Determined using autoconfiguration.
+
+  <hostname>	Name of the client.
+		If a '.' character is present, anything
+		before the first '.' is used as the client's hostname, and anything
+		after it is used as its NIS domain name. May be supplied by
+		autoconfiguration, but its absence will not trigger autoconfiguration.
+		If specified and DHCP is used, the user-provided hostname (and NIS
+		domain name, if present) will be carried in the DHCP request; this
+		may cause a DNS record to be created or updated for the client.
+
+  		Default: Client IP address is used in ASCII notation.
+
+  <device>	Name of network device to use.
+		Default: If the host only has one device, it is used.
+		Otherwise the device is determined using
+		autoconfiguration. This is done by sending
+		autoconfiguration requests out of all devices,
+		and using the device that received the first reply.
+
+  <autoconf>	Method to use for autoconfiguration.
+		In the case of options
+		which specify multiple autoconfiguration protocols,
+		requests are sent using all protocols, and the first one
+		to reply is used.
+
+		Only autoconfiguration protocols that have been compiled
+		into the kernel will be used, regardless of the value of
+		this option::
+
+                  off or none: don't use autoconfiguration
+				(do static IP assignment instead)
+		  on or any:   use any protocol available in the kernel
+			       (default)
+		  dhcp:        use DHCP
+		  bootp:       use BOOTP
+		  rarp:        use RARP
+		  both:        use both BOOTP and RARP but not DHCP
+		               (old option kept for backwards compatibility)
+
+		if dhcp is used, the client identifier can be used by following
+		format "ip=dhcp,client-id-type,client-id-value"
+
+                Default: any
+
+  <dns0-ip>	IP address of primary nameserver.
+		Value is exported to /proc/net/pnp with the prefix "nameserver "
+		(see below).
+
+		Default: None if not using autoconfiguration; determined
+		automatically if using autoconfiguration.
+
+  <dns1-ip>	IP address of secondary nameserver.
+		See <dns0-ip>.
+
+  <ntp0-ip>	IP address of a Network Time Protocol (NTP) server.
+		Value is exported to /proc/net/ipconfig/ntp_servers, but is
+		otherwise unused (see below).
+
+		Default: None if not using autoconfiguration; determined
+		automatically if using autoconfiguration.
+
+  After configuration (whether manual or automatic) is complete, two files
+  are created in the following format; lines are omitted if their respective
+  value is empty following configuration:
+
+  - /proc/net/pnp:
+
+	#PROTO: <DHCP|BOOTP|RARP|MANUAL>	(depending on configuration method)
+	domain <dns-domain>			(if autoconfigured, the DNS domain)
+	nameserver <dns0-ip>			(primary name server IP)
+	nameserver <dns1-ip>			(secondary name server IP)
+	nameserver <dns2-ip>			(tertiary name server IP)
+	bootserver <server-ip>			(NFS server IP)
+
+  - /proc/net/ipconfig/ntp_servers:
+
+	<ntp0-ip>				(NTP server IP)
+	<ntp1-ip>				(NTP server IP)
+	<ntp2-ip>				(NTP server IP)
+
+  <dns-domain> and <dns2-ip> (in /proc/net/pnp) and <ntp1-ip> and <ntp2-ip>
+  (in /proc/net/ipconfig/ntp_servers) are requested during autoconfiguration;
+  they cannot be specified as part of the "ip=" kernel command line parameter.
+
+  Because the "domain" and "nameserver" options are recognised by DNS
+  resolvers, /etc/resolv.conf is often linked to /proc/net/pnp on systems
+  that use an NFS root filesystem.
+
+  Note that the kernel will not synchronise the system time with any NTP
+  servers it discovers; this is the responsibility of a user space process
+  (e.g. an initrd/initramfs script that passes the IP addresses listed in
+  /proc/net/ipconfig/ntp_servers to an NTP client before mounting the real
+  root filesystem if it is on NFS).
+
+
+nfsrootdebug
+  This parameter enables debugging messages to appear in the kernel
+  log at boot time so that administrators can verify that the correct
+  NFS mount options, server address, and root path are passed to the
+  NFS client.
+
+
+rdinit=<executable file>
+  To specify which file contains the program that starts system
+  initialization, administrators can use this command line parameter.
+  The default value of this parameter is "/init".  If the specified
+  file exists and the kernel can execute it, root filesystem related
+  kernel command line parameters, including 'nfsroot=', are ignored.
+
+  A description of the process of mounting the root file system can be
+  found in Documentation/driver-api/early-userspace/early_userspace_support.rst
+
+
+Boot Loader
+===========
+
+To get the kernel into memory different approaches can be used.
+They depend on various facilities being available:
+
+
+- Booting from a floppy using syslinux
+
+	When building kernels, an easy way to create a boot floppy that uses
+	syslinux is to use the zdisk or bzdisk make targets which use zimage
+      	and bzimage images respectively. Both targets accept the
+     	FDARGS parameter which can be used to set the kernel command line.
+
+	e.g::
+
+	   make bzdisk FDARGS="root=/dev/nfs"
+
+   	Note that the user running this command will need to have
+     	access to the floppy drive device, /dev/fd0
+
+     	For more information on syslinux, including how to create bootdisks
+     	for prebuilt kernels, see https://syslinux.zytor.com/
+
+	.. note::
+		Previously it was possible to write a kernel directly to
+		a floppy using dd, configure the boot device using rdev, and
+		boot using the resulting floppy. Linux no longer supports this
+		method of booting.
+
+- Booting from a cdrom using isolinux
+
+     	When building kernels, an easy way to create a bootable cdrom that
+     	uses isolinux is to use the isoimage target which uses a bzimage
+     	image. Like zdisk and bzdisk, this target accepts the FDARGS
+     	parameter which can be used to set the kernel command line.
+
+	e.g::
+
+	  make isoimage FDARGS="root=/dev/nfs"
+
+     	The resulting iso image will be arch/<ARCH>/boot/image.iso
+     	This can be written to a cdrom using a variety of tools including
+     	cdrecord.
+
+	e.g::
+
+	  cdrecord dev=ATAPI:1,0,0 arch/x86/boot/image.iso
+
+     	For more information on isolinux, including how to create bootdisks
+     	for prebuilt kernels, see https://syslinux.zytor.com/
+
+- Using LILO
+
+	When using LILO all the necessary command line parameters may be
+	specified using the 'append=' directive in the LILO configuration
+	file.
+
+	However, to use the 'root=' directive you also need to create
+	a dummy root device, which may be removed after LILO is run.
+
+	e.g::
+
+	  mknod /dev/boot255 c 0 255
+
+	For information on configuring LILO, please refer to its documentation.
+
+- Using GRUB
+
+	When using GRUB, kernel parameter are simply appended after the kernel
+	specification: kernel <kernel> <parameters>
+
+- Using loadlin
+
+	loadlin may be used to boot Linux from a DOS command prompt without
+	requiring a local hard disk to mount as root. This has not been
+	thoroughly tested by the authors of this document, but in general
+	it should be possible configure the kernel command line similarly
+	to the configuration of LILO.
+
+	Please refer to the loadlin documentation for further information.
+
+- Using a boot ROM
+
+	This is probably the most elegant way of booting a diskless client.
+	With a boot ROM the kernel is loaded using the TFTP protocol. The
+	authors of this document are not aware of any no commercial boot
+	ROMs that support booting Linux over the network. However, there
+	are two free implementations of a boot ROM, netboot-nfs and
+	etherboot, both of which are available on sunsite.unc.edu, and both
+	of which contain everything you need to boot a diskless Linux client.
+
+- Using pxelinux
+
+	Pxelinux may be used to boot linux using the PXE boot loader
+	which is present on many modern network cards.
+
+	When using pxelinux, the kernel image is specified using
+	"kernel <relative-path-below /tftpboot>". The nfsroot parameters
+	are passed to the kernel by adding them to the "append" line.
+	It is common to use serial console in conjunction with pxelinux,
+	see Documentation/admin-guide/serial-console.rst for more information.
+
+	For more information on isolinux, including how to create bootdisks
+	for prebuilt kernels, see https://syslinux.zytor.com/
+
+
+
+
+Credits
+=======
+
+  The nfsroot code in the kernel and the RARP support have been written
+  by Gero Kuhlmann <gero@gkminix.han.de>.
+
+  The rest of the IP layer autoconfiguration code has been written
+  by Martin Mares <mj@atrey.karlin.mff.cuni.cz>.
+
+  In order to write the initial version of nfsroot I would like to thank
+  Jens-Uwe Mager <jum@anubis.han.de> for his help.
diff --git a/Documentation/admin-guide/nfs/pnfs-block-server.rst b/Documentation/admin-guide/nfs/pnfs-block-server.rst
new file mode 100644
index 000000000..7667dd2e1
--- /dev/null
+++ b/Documentation/admin-guide/nfs/pnfs-block-server.rst
@@ -0,0 +1,72 @@
+===================================
+pNFS block layout server user guide
+===================================
+
+The Linux NFS server now supports the pNFS block layout extension.  In this
+case the NFS server acts as Metadata Server (MDS) for pNFS, which in addition
+to handling all the metadata access to the NFS export also hands out layouts
+to the clients to directly access the underlying block devices that are
+shared with the client.
+
+To use pNFS block layouts with the Linux NFS server the exported file
+system needs to support the pNFS block layouts (currently just XFS), and the
+file system must sit on shared storage (typically iSCSI) that is accessible
+to the clients in addition to the MDS.  As of now the file system needs to
+sit directly on the exported volume, striping or concatenation of
+volumes on the MDS and clients is not supported yet.
+
+On the server, pNFS block volume support is automatically if the file system
+support it.  On the client make sure the kernel has the CONFIG_PNFS_BLOCK
+option enabled, the blkmapd daemon from nfs-utils is running, and the
+file system is mounted using the NFSv4.1 protocol version (mount -o vers=4.1).
+
+If the nfsd server needs to fence a non-responding client it calls
+/sbin/nfsd-recall-failed with the first argument set to the IP address of
+the client, and the second argument set to the device node without the /dev
+prefix for the file system to be fenced. Below is an example file that shows
+how to translate the device into a serial number from SCSI EVPD 0x80::
+
+	cat > /sbin/nfsd-recall-failed << EOF
+
+.. code-block:: sh
+
+	#!/bin/sh
+
+	CLIENT="$1"
+	DEV="/dev/$2"
+	EVPD=`sg_inq --page=0x80 ${DEV} | \
+		grep "Unit serial number:" | \
+		awk -F ': ' '{print $2}'`
+
+	echo "fencing client ${CLIENT} serial ${EVPD}" >> /var/log/pnfsd-fence.log
+	EOF
+
+If the nfsd server needs to fence a non-responding client and the
+fencing operation fails, the server logs a warning message in the
+system log with the following format:
+
+    FENCE failed client[IP_address] clid[#n] device[dev_name]
+
+    where:
+
+    - IP_address: refers to the IP address of the affected client.
+    - #n: indicates the unique client identifier.
+    - dev_name: specifies the name of the block device related
+      to the fencing attempt.
+
+The server will repeatedly retry the operation indefinitely. During
+this time, access to the affected file is restricted for all other
+clients. This is to prevent potential data corruption if multiple
+clients access the same file simultaneously.
+
+To restore access to the affected file for other clients, the admin
+needs to take the following actions:
+
+    - shutdown or power off the client being fenced.
+    - manually expire the client to release all its state on the server::
+
+        echo 'expire' > /proc/fs/nfsd/clients/clid/ctl
+
+    where:
+
+      - clid: is the unique client identifier displayed in the system log.
diff --git a/Documentation/admin-guide/nfs/pnfs-scsi-server.rst b/Documentation/admin-guide/nfs/pnfs-scsi-server.rst
new file mode 100644
index 000000000..b202508d2
--- /dev/null
+++ b/Documentation/admin-guide/nfs/pnfs-scsi-server.rst
@@ -0,0 +1,55 @@
+
+==================================
+pNFS SCSI layout server user guide
+==================================
+
+This document describes support for pNFS SCSI layouts in the Linux NFS server.
+With pNFS SCSI layouts, the NFS server acts as Metadata Server (MDS) for pNFS,
+which in addition to handling all the metadata access to the NFS export,
+also hands out layouts to the clients so that they can directly access the
+underlying SCSI LUNs that are shared with the client.
+
+To use pNFS SCSI layouts with the Linux NFS server, the exported file
+system needs to support the pNFS SCSI layouts (currently just XFS), and the
+file system must sit on a SCSI LUN that is accessible to the clients in
+addition to the MDS.  As of now the file system needs to sit directly on the
+exported LUN, striping or concatenation of LUNs on the MDS and clients
+is not supported yet.
+
+On a server built with CONFIG_NFSD_SCSI, the pNFS SCSI volume support is
+automatically enabled if the file system is exported using the "pnfs"
+option and the underlying SCSI device support persistent reservations.
+On the client make sure the kernel has the CONFIG_PNFS_BLOCK option
+enabled, and the file system is mounted using the NFSv4.1 protocol
+version (mount -o vers=4.1).
+
+If the nfsd server needs to fence a non-responding client and the
+fencing operation fails, the server logs a warning message in the
+system log with the following format:
+
+    FENCE failed client[IP_address] clid[#n] device[dev_name]
+
+    where:
+
+    - IP_address: refers to the IP address of the affected client.
+    - #n: indicates the unique client identifier.
+    - dev_name: specifies the name of the block device related
+      to the fencing attempt.
+
+The server will repeatedly retry the operation indefinitely. During
+this time, access to the affected file is restricted for all other
+clients. This is to prevent potential data corruption if multiple
+clients access the same file simultaneously.
+
+To restore access to the affected file for other clients, the admin
+needs to take the following actions:
+
+    - shutdown or power off the client being fenced.
+    - manually expire the client to release all its state on the server::
+
+        echo 'expire' > /proc/fs/nfsd/clients/clid/ctl
+
+    where:
+
+      - clid: is the unique client identifier displayed in the system log.
+
diff --git a/Documentation/admin-guide/numastat.rst b/Documentation/admin-guide/numastat.rst
new file mode 100644
index 000000000..08ec2c2bd
--- /dev/null
+++ b/Documentation/admin-guide/numastat.rst
@@ -0,0 +1,55 @@
+===============================
+Numa policy hit/miss statistics
+===============================
+
+/sys/devices/system/node/node*/numastat
+
+All units are pages. Hugepages have separate counters.
+
+The numa_hit, numa_miss and numa_foreign counters reflect how well processes
+are able to allocate memory from nodes they prefer. If they succeed, numa_hit
+is incremented on the preferred node, otherwise numa_foreign is incremented on
+the preferred node and numa_miss on the node where allocation succeeded.
+
+Usually preferred node is the one local to the CPU where the process executes,
+but restrictions such as mempolicies can change that, so there are also two
+counters based on CPU local node. local_node is similar to numa_hit and is
+incremented on allocation from a node by CPU on the same node. other_node is
+similar to numa_miss and is incremented on the node where allocation succeeds
+from a CPU from a different node. Note there is no counter analogical to
+numa_foreign.
+
+In more detail:
+
+=============== ============================================================
+numa_hit	A process wanted to allocate memory from this node,
+		and succeeded.
+
+numa_miss	A process wanted to allocate memory from another node,
+		but ended up with memory from this node.
+
+numa_foreign	A process wanted to allocate on this node,
+		but ended up with memory from another node.
+
+local_node	A process ran on this node's CPU,
+		and got memory from this node.
+
+other_node	A process ran on a different node's CPU
+		and got memory from this node.
+
+interleave_hit 	Interleaving wanted to allocate from this node
+		and succeeded.
+=============== ============================================================
+
+For easier reading you can use the numastat utility from the numactl package
+(http://oss.sgi.com/projects/libnuma/). Note that it only works
+well right now on machines with a small number of CPUs.
+
+Note that on systems with memoryless nodes (where a node has CPUs but no
+memory) the numa_hit, numa_miss and numa_foreign statistics can be skewed
+heavily. In the current kernel implementation, if a process prefers a
+memoryless node (i.e.  because it is running on one of its local CPU), the
+implementation actually treats one of the nearest nodes with memory as the
+preferred node. As a result, such allocation will not increase the numa_foreign
+counter on the memoryless node, and will skew the numa_hit, numa_miss and
+numa_foreign statistics of the nearest node.
diff --git a/Documentation/admin-guide/nvme-multipath.rst b/Documentation/admin-guide/nvme-multipath.rst
new file mode 100644
index 000000000..97ca1ccef
--- /dev/null
+++ b/Documentation/admin-guide/nvme-multipath.rst
@@ -0,0 +1,72 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+Linux NVMe multipath
+====================
+
+This document describes NVMe multipath and its path selection policies supported
+by the Linux NVMe host driver.
+
+
+Introduction
+============
+
+The NVMe multipath feature in Linux integrates namespaces with the same
+identifier into a single block device. Using multipath enhances the reliability
+and stability of I/O access while improving bandwidth performance. When a user
+sends I/O to this merged block device, the multipath mechanism selects one of
+the underlying block devices (paths) according to the configured policy.
+Different policies result in different path selections.
+
+
+Policies
+========
+
+All policies follow the ANA (Asymmetric Namespace Access) mechanism, meaning
+that when an optimized path is available, it will be chosen over a non-optimized
+one. Current the NVMe multipath policies include numa(default), round-robin and
+queue-depth.
+
+To set the desired policy (e.g., round-robin), use one of the following methods:
+   1. echo -n "round-robin" > /sys/module/nvme_core/parameters/iopolicy
+   2. or add the "nvme_core.iopolicy=round-robin" to cmdline.
+
+
+NUMA
+----
+
+The NUMA policy selects the path closest to the NUMA node of the current CPU for
+I/O distribution. This policy maintains the nearest paths to each NUMA node
+based on network interface connections.
+
+When to use the NUMA policy:
+  1. Multi-core Systems: Optimizes memory access in multi-core and
+     multi-processor systems, especially under NUMA architecture.
+  2. High Affinity Workloads: Binds I/O processing to the CPU to reduce
+     communication and data transfer delays across nodes.
+
+
+Round-Robin
+-----------
+
+The round-robin policy distributes I/O requests evenly across all paths to
+enhance throughput and resource utilization. Each I/O operation is sent to the
+next path in sequence.
+
+When to use the round-robin policy:
+  1. Balanced Workloads: Effective for balanced and predictable workloads with
+     similar I/O size and type.
+  2. Homogeneous Path Performance: Utilizes all paths efficiently when
+     performance characteristics (e.g., latency, bandwidth) are similar.
+
+
+Queue-Depth
+-----------
+
+The queue-depth policy manages I/O requests based on the current queue depth
+of each path, selecting the path with the least number of in-flight I/Os.
+
+When to use the queue-depth policy:
+  1. High load with small I/Os: Effectively balances load across paths when
+     the load is high, and I/O operations consist of small, relatively
+     fixed-sized requests.
diff --git a/Documentation/admin-guide/parport.rst b/Documentation/admin-guide/parport.rst
new file mode 100644
index 000000000..ad3f9b8a1
--- /dev/null
+++ b/Documentation/admin-guide/parport.rst
@@ -0,0 +1,286 @@
+Parport
++++++++
+
+The ``parport`` code provides parallel-port support under Linux.  This
+includes the ability to share one port between multiple device
+drivers.
+
+You can pass parameters to the ``parport`` code to override its automatic
+detection of your hardware.  This is particularly useful if you want
+to use IRQs, since in general these can't be autoprobed successfully.
+By default IRQs are not used even if they **can** be probed.  This is
+because there are a lot of people using the same IRQ for their
+parallel port and a sound card or network card.
+
+The ``parport`` code is split into two parts: generic (which deals with
+port-sharing) and architecture-dependent (which deals with actually
+using the port).
+
+
+Parport as modules
+==================
+
+If you load the `parport`` code as a module, say::
+
+	# insmod parport
+
+to load the generic ``parport`` code.  You then must load the
+architecture-dependent code with (for example)::
+
+	# insmod parport_pc io=0x3bc,0x378,0x278 irq=none,7,auto
+
+to tell the ``parport`` code that you want three PC-style ports, one at
+0x3bc with no IRQ, one at 0x378 using IRQ 7, and one at 0x278 with an
+auto-detected IRQ.  Currently, PC-style (``parport_pc``), Sun ``bpp``,
+Amiga, Atari, and MFC3 hardware is supported.
+
+PCI parallel I/O card support comes from ``parport_pc``.  Base I/O
+addresses should not be specified for supported PCI cards since they
+are automatically detected.
+
+
+modprobe
+--------
+
+If you use modprobe , you will find it useful to add lines as below to a
+configuration file in /etc/modprobe.d/ directory::
+
+	alias parport_lowlevel parport_pc
+	options parport_pc io=0x378,0x278 irq=7,auto
+
+modprobe will load ``parport_pc`` (with the options ``io=0x378,0x278 irq=7,auto``)
+whenever a parallel port device driver (such as ``lp``) is loaded.
+
+Note that these are example lines only!  You shouldn't in general need
+to specify any options to ``parport_pc`` in order to be able to use a
+parallel port.
+
+
+Parport probe [optional]
+------------------------
+
+In 2.2 kernels there was a module called ``parport_probe``, which was used
+for collecting IEEE 1284 device ID information.  This has now been
+enhanced and now lives with the IEEE 1284 support.  When a parallel
+port is detected, the devices that are connected to it are analysed,
+and information is logged like this::
+
+	parport0: Printer, BJC-210 (Canon)
+
+The probe information is available from files in ``/proc/sys/dev/parport/``.
+
+
+Parport linked into the kernel statically
+=========================================
+
+If you compile the ``parport`` code into the kernel, then you can use
+kernel boot parameters to get the same effect.  Add something like the
+following to your LILO command line::
+
+	parport=0x3bc parport=0x378,7 parport=0x278,auto,nofifo
+
+You can have many ``parport=...`` statements, one for each port you want
+to add.  Adding ``parport=0`` to the kernel command-line will disable
+parport support entirely.  Adding ``parport=auto`` to the kernel
+command-line will make ``parport`` use any IRQ lines or DMA channels that
+it auto-detects.
+
+
+Files in /proc
+==============
+
+If you have configured the ``/proc`` filesystem into your kernel, you will
+see a new directory entry: ``/proc/sys/dev/parport``.  In there will be a
+directory entry for each parallel port for which parport is
+configured.  In each of those directories are a collection of files
+describing that parallel port.
+
+The ``/proc/sys/dev/parport`` directory tree looks like::
+
+	parport
+	|-- default
+	|   |-- spintime
+	|   `-- timeslice
+	|-- parport0
+	|   |-- autoprobe
+	|   |-- autoprobe0
+	|   |-- autoprobe1
+	|   |-- autoprobe2
+	|   |-- autoprobe3
+	|   |-- devices
+	|   |   |-- active
+	|   |   `-- lp
+	|   |       `-- timeslice
+	|   |-- base-addr
+	|   |-- irq
+	|   |-- dma
+	|   |-- modes
+	|   `-- spintime
+	`-- parport1
+	|-- autoprobe
+	|-- autoprobe0
+	|-- autoprobe1
+	|-- autoprobe2
+	|-- autoprobe3
+	|-- devices
+	|   |-- active
+	|   `-- ppa
+	|       `-- timeslice
+	|-- base-addr
+	|-- irq
+	|-- dma
+	|-- modes
+	`-- spintime
+
+.. tabularcolumns:: |p{4.0cm}|p{13.5cm}|
+
+=======================	=======================================================
+File			Contents
+=======================	=======================================================
+``devices/active``	A list of the device drivers using that port.  A "+"
+			will appear by the name of the device currently using
+			the port (it might not appear against any).  The
+			string "none" means that there are no device drivers
+			using that port.
+
+``base-addr``		Parallel port's base address, or addresses if the port
+			has more than one in which case they are separated
+			with tabs.  These values might not have any sensible
+			meaning for some ports.
+
+``irq``			Parallel port's IRQ, or -1 if none is being used.
+
+``dma``			Parallel port's DMA channel, or -1 if none is being
+			used.
+
+``modes``		Parallel port's hardware modes, comma-separated,
+			meaning:
+
+			- PCSPP
+				PC-style SPP registers are available.
+
+			- TRISTATE
+				Port is bidirectional.
+
+			- COMPAT
+				Hardware acceleration for printers is
+				available and will be used.
+
+			- EPP
+				Hardware acceleration for EPP protocol
+				is available and will be used.
+
+			- ECP
+				Hardware acceleration for ECP protocol
+				is available and will be used.
+
+			- DMA
+				DMA is available and will be used.
+
+			Note that the current implementation will only take
+			advantage of COMPAT and ECP modes if it has an IRQ
+			line to use.
+
+``autoprobe``		Any IEEE-1284 device ID information that has been
+			acquired from the (non-IEEE 1284.3) device.
+
+``autoprobe[0-3]``	IEEE 1284 device ID information retrieved from
+			daisy-chain devices that conform to IEEE 1284.3.
+
+``spintime``		The number of microseconds to busy-loop while waiting
+			for the peripheral to respond.  You might find that
+			adjusting this improves performance, depending on your
+			peripherals.  This is a port-wide setting, i.e. it
+			applies to all devices on a particular port.
+
+``timeslice``		The number of milliseconds that a device driver is
+			allowed to keep a port claimed for.  This is advisory,
+			and driver can ignore it if it must.
+
+``default/*``		The defaults for spintime and timeslice. When a new
+			port is	registered, it picks up the default spintime.
+			When a new device is registered, it picks up the
+			default timeslice.
+=======================	=======================================================
+
+Device drivers
+==============
+
+Once the parport code is initialised, you can attach device drivers to
+specific ports.  Normally this happens automatically; if the lp driver
+is loaded it will create one lp device for each port found.  You can
+override this, though, by using parameters either when you load the lp
+driver::
+
+	# insmod lp parport=0,2
+
+or on the LILO command line::
+
+	lp=parport0 lp=parport2
+
+Both the above examples would inform lp that you want ``/dev/lp0`` to be
+the first parallel port, and /dev/lp1 to be the **third** parallel port,
+with no lp device associated with the second port (parport1).  Note
+that this is different to the way older kernels worked; there used to
+be a static association between the I/O port address and the device
+name, so ``/dev/lp0`` was always the port at 0x3bc.  This is no longer the
+case - if you only have one port, it will default to being ``/dev/lp0``,
+regardless of base address.
+
+Also:
+
+ * If you selected the IEEE 1284 support at compile time, you can say
+   ``lp=auto`` on the kernel command line, and lp will create devices
+   only for those ports that seem to have printers attached.
+
+ * If you give PLIP the ``timid`` parameter, either with ``plip=timid`` on
+   the command line, or with ``insmod plip timid=1`` when using modules,
+   it will avoid any ports that seem to be in use by other devices.
+
+ * IRQ autoprobing works only for a few port types at the moment.
+
+Reporting printer problems with parport
+=======================================
+
+If you are having problems printing, please go through these steps to
+try to narrow down where the problem area is.
+
+When reporting problems with parport, really you need to give all of
+the messages that ``parport_pc`` spits out when it initialises.  There are
+several code paths:
+
+- polling
+- interrupt-driven, protocol in software
+- interrupt-driven, protocol in hardware using PIO
+- interrupt-driven, protocol in hardware using DMA
+
+The kernel messages that ``parport_pc`` logs give an indication of which
+code path is being used. (They could be a lot better actually..)
+
+For normal printer protocol, having IEEE 1284 modes enabled or not
+should not make a difference.
+
+To turn off the 'protocol in hardware' code paths, disable
+``CONFIG_PARPORT_PC_FIFO``.  Note that when they are enabled they are not
+necessarily **used**; it depends on whether the hardware is available,
+enabled by the BIOS, and detected by the driver.
+
+So, to start with, disable ``CONFIG_PARPORT_PC_FIFO``, and load ``parport_pc``
+with ``irq=none``. See if printing works then.  It really should,
+because this is the simplest code path.
+
+If that works fine, try with ``io=0x378 irq=7`` (adjust for your
+hardware), to make it use interrupt-driven in-software protocol.
+
+If **that** works fine, then one of the hardware modes isn't working
+right.  Enable ``CONFIG_FIFO`` (no, it isn't a module option,
+and yes, it should be), set the port to ECP mode in the BIOS and note
+the DMA channel, and try with::
+
+    io=0x378 irq=7 dma=none (for PIO)
+    io=0x378 irq=7 dma=3 (for DMA)
+
+----------
+
+philb@gnu.org
+tim@cyberelk.net
diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
new file mode 100644
index 000000000..34aa33432
--- /dev/null
+++ b/Documentation/admin-guide/perf-security.rst
@@ -0,0 +1,325 @@
+.. _perf_security:
+
+Perf events and tool security
+=============================
+
+Overview
+--------
+
+Usage of Performance Counters for Linux (perf_events) [1]_ , [2]_ , [3]_
+can impose a considerable risk of leaking sensitive data accessed by
+monitored processes. The data leakage is possible both in scenarios of
+direct usage of perf_events system call API [2]_ and over data files
+generated by Perf tool user mode utility (Perf) [3]_ , [4]_ . The risk
+depends on the nature of data that perf_events performance monitoring
+units (PMU) [2]_ and Perf collect and expose for performance analysis.
+Collected system and performance data may be split into several
+categories:
+
+1. System hardware and software configuration data, for example: a CPU
+   model and its cache configuration, an amount of available memory and
+   its topology, used kernel and Perf versions, performance monitoring
+   setup including experiment time, events configuration, Perf command
+   line parameters, etc.
+
+2. User and kernel module paths and their load addresses with sizes,
+   process and thread names with their PIDs and TIDs, timestamps for
+   captured hardware and software events.
+
+3. Content of kernel software counters (e.g., for context switches, page
+   faults, CPU migrations), architectural hardware performance counters
+   (PMC) [8]_ and machine specific registers (MSR) [9]_ that provide
+   execution metrics for various monitored parts of the system (e.g.,
+   memory controller (IMC), interconnect (QPI/UPI) or peripheral (PCIe)
+   uncore counters) without direct attribution to any execution context
+   state.
+
+4. Content of architectural execution context registers (e.g., RIP, RSP,
+   RBP on x86_64), process user and kernel space memory addresses and
+   data, content of various architectural MSRs that capture data from
+   this category.
+
+Data that belong to the fourth category can potentially contain
+sensitive process data. If PMUs in some monitoring modes capture values
+of execution context registers or data from process memory then access
+to such monitoring modes requires to be ordered and secured properly.
+So, perf_events performance monitoring and observability operations are
+the subject for security access control management [5]_ .
+
+perf_events access control
+-------------------------------
+
+To perform security checks, the Linux implementation splits processes
+into two categories [6]_ : a) privileged processes (whose effective user
+ID is 0, referred to as superuser or root), and b) unprivileged
+processes (whose effective UID is nonzero). Privileged processes bypass
+all kernel security permission checks so perf_events performance
+monitoring is fully available to privileged processes without access,
+scope and resource restrictions.
+
+Unprivileged processes are subject to a full security permission check
+based on the process's credentials [5]_ (usually: effective UID,
+effective GID, and supplementary group list).
+
+Linux divides the privileges traditionally associated with superuser
+into distinct units, known as capabilities [6]_ , which can be
+independently enabled and disabled on per-thread basis for processes and
+files of unprivileged users.
+
+Unprivileged processes with enabled CAP_PERFMON capability are treated
+as privileged processes with respect to perf_events performance
+monitoring and observability operations, thus, bypass *scope* permissions
+checks in the kernel. CAP_PERFMON implements the principle of least
+privilege [13]_ (POSIX 1003.1e: 2.2.2.39) for performance monitoring and
+observability operations in the kernel and provides a secure approach to
+performance monitoring and observability in the system.
+
+For backward compatibility reasons the access to perf_events monitoring and
+observability operations is also open for CAP_SYS_ADMIN privileged
+processes but CAP_SYS_ADMIN usage for secure monitoring and observability
+use cases is discouraged with respect to the CAP_PERFMON capability.
+If system audit records [14]_ for a process using perf_events system call
+API contain denial records of acquiring both CAP_PERFMON and CAP_SYS_ADMIN
+capabilities then providing the process with CAP_PERFMON capability singly
+is recommended as the preferred secure approach to resolve double access
+denial logging related to usage of performance monitoring and observability.
+
+Prior Linux v5.9 unprivileged processes using perf_events system call
+are also subject for PTRACE_MODE_READ_REALCREDS ptrace access mode check
+[7]_ , whose outcome determines whether monitoring is permitted.
+So unprivileged processes provided with CAP_SYS_PTRACE capability are
+effectively permitted to pass the check. Starting from Linux v5.9
+CAP_SYS_PTRACE capability is not required and CAP_PERFMON is enough to
+be provided for processes to make performance monitoring and observability
+operations.
+
+Other capabilities being granted to unprivileged processes can
+effectively enable capturing of additional data required for later
+performance analysis of monitored processes or a system. For example,
+CAP_SYSLOG capability permits reading kernel space memory addresses from
+/proc/kallsyms file.
+
+Privileged Perf users groups
+---------------------------------
+
+Mechanisms of capabilities, privileged capability-dumb files [6]_,
+file system ACLs [10]_ and sudo [15]_ utility can be used to create
+dedicated groups of privileged Perf users who are permitted to execute
+performance monitoring and observability without limits. The following
+steps can be taken to create such groups of privileged Perf users.
+
+1. Create perf_users group of privileged Perf users, assign perf_users
+   group to Perf tool executable and limit access to the executable for
+   other users in the system who are not in the perf_users group:
+
+::
+
+   # groupadd perf_users
+   # ls -alhF
+   -rwxr-xr-x  2 root root  11M Oct 19 15:12 perf
+   # chgrp perf_users perf
+   # ls -alhF
+   -rwxr-xr-x  2 root perf_users  11M Oct 19 15:12 perf
+   # chmod o-rwx perf
+   # ls -alhF
+   -rwxr-x---  2 root perf_users  11M Oct 19 15:12 perf
+
+2. Assign the required capabilities to the Perf tool executable file and
+   enable members of perf_users group with monitoring and observability
+   privileges [6]_ :
+
+::
+
+   # setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
+   # setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
+   perf: OK
+   # getcap perf
+   perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep
+
+If the libcap [16]_ installed doesn't yet support "cap_perfmon", use "38" instead,
+i.e.:
+
+::
+
+   # setcap "38,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf
+
+Note that you may need to have 'cap_ipc_lock' in the mix for tools such as
+'perf top', alternatively use 'perf top -m N', to reduce the memory that
+it uses for the perf ring buffer, see the memory allocation section below.
+
+Using a libcap without support for CAP_PERFMON will make cap_get_flag(caps, 38,
+CAP_EFFECTIVE, &val) fail, which will lead the default event to be 'cycles:u',
+so as a workaround explicitly ask for the 'cycles' event, i.e.:
+
+::
+
+  # perf top -e cycles
+
+To get kernel and user samples with a perf binary with just CAP_PERFMON.
+
+As a result, members of perf_users group are capable of conducting
+performance monitoring and observability by using functionality of the
+configured Perf tool executable that, when executes, passes perf_events
+subsystem scope checks.
+
+In case Perf tool executable can't be assigned required capabilities (e.g.
+file system is mounted with nosuid option or extended attributes are
+not supported by the file system) then creation of the capabilities
+privileged environment, naturally shell, is possible. The shell provides
+inherent processes with CAP_PERFMON and other required capabilities so that
+performance monitoring and observability operations are available in the
+environment without limits. Access to the environment can be open via sudo
+utility for members of perf_users group only. In order to create such
+environment:
+
+1. Create shell script that uses capsh utility [16]_ to assign CAP_PERFMON
+   and other required capabilities into ambient capability set of the shell
+   process, lock the process security bits after enabling SECBIT_NO_SETUID_FIXUP,
+   SECBIT_NOROOT and SECBIT_NO_CAP_AMBIENT_RAISE bits and then change
+   the process identity to sudo caller of the script who should essentially
+   be a member of perf_users group:
+
+::
+
+   # ls -alh /usr/local/bin/perf.shell
+   -rwxr-xr-x. 1 root root 83 Oct 13 23:57 /usr/local/bin/perf.shell
+   # cat /usr/local/bin/perf.shell
+   exec /usr/sbin/capsh --iab=^cap_perfmon --secbits=239 --user=$SUDO_USER -- -l
+
+2. Extend sudo policy at /etc/sudoers file with a rule for perf_users group:
+
+::
+
+   # grep perf_users /etc/sudoers
+   %perf_users    ALL=/usr/local/bin/perf.shell
+
+3. Check that members of perf_users group have access to the privileged
+   shell and have CAP_PERFMON and other required capabilities enabled
+   in permitted, effective and ambient capability sets of an inherent process:
+
+::
+
+  $ id
+  uid=1003(capsh_test) gid=1004(capsh_test) groups=1004(capsh_test),1000(perf_users) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
+  $ sudo perf.shell
+  [sudo] password for capsh_test:
+  $ grep Cap /proc/self/status
+  CapInh:        0000004000000000
+  CapPrm:        0000004000000000
+  CapEff:        0000004000000000
+  CapBnd:        000000ffffffffff
+  CapAmb:        0000004000000000
+  $ capsh --decode=0000004000000000
+  0x0000004000000000=cap_perfmon
+
+As a result, members of perf_users group have access to the privileged
+environment where they can use tools employing performance monitoring APIs
+governed by CAP_PERFMON Linux capability.
+
+This specific access control management is only available to superuser
+or root running processes with CAP_SETPCAP, CAP_SETFCAP [6]_
+capabilities.
+
+Unprivileged users
+-----------------------------------
+
+perf_events *scope* and *access* control for unprivileged processes
+is governed by perf_event_paranoid [2]_ setting:
+
+-1:
+     Impose no *scope* and *access* restrictions on using perf_events
+     performance monitoring. Per-user per-cpu perf_event_mlock_kb [2]_
+     locking limit is ignored when allocating memory buffers for storing
+     performance data. This is the least secure mode since allowed
+     monitored *scope* is maximized and no perf_events specific limits
+     are imposed on *resources* allocated for performance monitoring.
+
+>=0:
+     *scope* includes per-process and system wide performance monitoring
+     but excludes raw tracepoints and ftrace function tracepoints
+     monitoring. CPU and system events happened when executing either in
+     user or in kernel space can be monitored and captured for later
+     analysis. Per-user per-cpu perf_event_mlock_kb locking limit is
+     imposed but ignored for unprivileged processes with CAP_IPC_LOCK
+     [6]_ capability.
+
+>=1:
+     *scope* includes per-process performance monitoring only and
+     excludes system wide performance monitoring. CPU and system events
+     happened when executing either in user or in kernel space can be
+     monitored and captured for later analysis. Per-user per-cpu
+     perf_event_mlock_kb locking limit is imposed but ignored for
+     unprivileged processes with CAP_IPC_LOCK capability.
+
+>=2:
+     *scope* includes per-process performance monitoring only. CPU and
+     system events happened when executing in user space only can be
+     monitored and captured for later analysis. Per-user per-cpu
+     perf_event_mlock_kb locking limit is imposed but ignored for
+     unprivileged processes with CAP_IPC_LOCK capability.
+
+Resource control
+---------------------------------
+
+Open file descriptors
++++++++++++++++++++++
+
+The perf_events system call API [2]_ allocates file descriptors for
+every configured PMU event. Open file descriptors are a per-process
+accountable resource governed by the RLIMIT_NOFILE [11]_ limit
+(ulimit -n), which is usually derived from the login shell process. When
+configuring Perf collection for a long list of events on a large server
+system, this limit can be easily hit preventing required monitoring
+configuration. RLIMIT_NOFILE limit can be increased on per-user basis
+modifying content of the limits.conf file [12]_ . Ordinarily, a Perf
+sampling session (perf record) requires an amount of open perf_event
+file descriptors that is not less than the number of monitored events
+multiplied by the number of monitored CPUs.
+
+Memory allocation
++++++++++++++++++
+
+The amount of memory available to user processes for capturing
+performance monitoring data is governed by the perf_event_mlock_kb [2]_
+setting. This perf_event specific resource setting defines overall
+per-cpu limits of memory allowed for mapping by the user processes to
+execute performance monitoring. The setting essentially extends the
+RLIMIT_MEMLOCK [11]_ limit, but only for memory regions mapped
+specifically for capturing monitored performance events and related data.
+
+For example, if a machine has eight cores and perf_event_mlock_kb limit
+is set to 516 KiB, then a user process is provided with 516 KiB * 8 =
+4128 KiB of memory above the RLIMIT_MEMLOCK limit (ulimit -l) for
+perf_event mmap buffers. In particular, this means that, if the user
+wants to start two or more performance monitoring processes, the user is
+required to manually distribute the available 4128 KiB between the
+monitoring processes, for example, using the --mmap-pages Perf record
+mode option. Otherwise, the first started performance monitoring process
+allocates all available 4128 KiB and the other processes will fail to
+proceed due to the lack of memory.
+
+RLIMIT_MEMLOCK and perf_event_mlock_kb resource constraints are ignored
+for processes with the CAP_IPC_LOCK capability. Thus, perf_events/Perf
+privileged users can be provided with memory above the constraints for
+perf_events/Perf performance monitoring purpose by providing the Perf
+executable with CAP_IPC_LOCK capability.
+
+Bibliography
+------------
+
+.. [1] `<https://lwn.net/Articles/337493/>`_
+.. [2] `<http://man7.org/linux/man-pages/man2/perf_event_open.2.html>`_
+.. [3] `<http://web.eece.maine.edu/~vweaver/projects/perf_events/>`_
+.. [4] `<https://perf.wiki.kernel.org/index.php/Main_Page>`_
+.. [5] `<https://www.kernel.org/doc/html/latest/security/credentials.html>`_
+.. [6] `<http://man7.org/linux/man-pages/man7/capabilities.7.html>`_
+.. [7] `<http://man7.org/linux/man-pages/man2/ptrace.2.html>`_
+.. [8] `<https://en.wikipedia.org/wiki/Hardware_performance_counter>`_
+.. [9] `<https://en.wikipedia.org/wiki/Model-specific_register>`_
+.. [10] `<http://man7.org/linux/man-pages/man5/acl.5.html>`_
+.. [11] `<http://man7.org/linux/man-pages/man2/getrlimit.2.html>`_
+.. [12] `<http://man7.org/linux/man-pages/man5/limits.conf.5.html>`_
+.. [13] `<https://sites.google.com/site/fullycapable>`_
+.. [14] `<http://man7.org/linux/man-pages/man8/auditd.8.html>`_
+.. [15] `<https://man7.org/linux/man-pages/man8/sudo.8.html>`_
+.. [16] `<https://git.kernel.org/pub/scm/libs/libcap/libcap.git/>`_
diff --git a/Documentation/admin-guide/perf/alibaba_pmu.rst b/Documentation/admin-guide/perf/alibaba_pmu.rst
new file mode 100644
index 000000000..7d8400239
--- /dev/null
+++ b/Documentation/admin-guide/perf/alibaba_pmu.rst
@@ -0,0 +1,105 @@
+=============================================================
+Alibaba's T-Head SoC Uncore Performance Monitoring Unit (PMU)
+=============================================================
+
+The Yitian 710, custom-built by Alibaba Group's chip development business,
+T-Head, implements uncore PMU for performance and functional debugging to
+facilitate system maintenance.
+
+DDR Sub-System Driveway (DRW) PMU Driver
+=========================================
+
+Yitian 710 employs eight DDR5/4 channels, four on each die. Each DDR5 channel
+is independent of others to service system memory requests. And one DDR5
+channel is split into two independent sub-channels. The DDR Sub-System Driveway
+implements separate PMUs for each sub-channel to monitor various performance
+metrics.
+
+The Driveway PMU devices are named as ali_drw_<sys_base_addr> with perf.
+For example, ali_drw_21000 and ali_drw_21080 are two PMU devices for two
+sub-channels of the same channel in die 0. And the PMU device of die 1 is
+prefixed with ali_drw_400XXXXX, e.g. ali_drw_40021000.
+
+Each sub-channel has 36 PMU counters in total, which is classified into
+four groups:
+
+- Group 0: PMU Cycle Counter. This group has one pair of counters
+  pmu_cycle_cnt_low and pmu_cycle_cnt_high, that is used as the cycle count
+  based on DDRC core clock.
+
+- Group 1: PMU Bandwidth Counters. This group has 8 counters that are used
+  to count the total access number of either the eight bank groups in a
+  selected rank, or four ranks separately in the first 4 counters. The base
+  transfer unit is 64B.
+
+- Group 2: PMU Retry Counters. This group has 10 counters, that intend to
+  count the total retry number of each type of uncorrectable error.
+
+- Group 3: PMU Common Counters. This group has 16 counters, that are used
+  to count the common events.
+
+For now, the Driveway PMU driver only uses counters in group 0 and group 3.
+
+The DDR Controller (DDRCTL) and DDR PHY combine to create a complete solution
+for connecting an SoC application bus to DDR memory devices. The DDRCTL
+receives transactions Host Interface (HIF) which is custom-defined by Synopsys.
+These transactions are queued internally and scheduled for access while
+satisfying the SDRAM protocol timing requirements, transaction priorities, and
+dependencies between the transactions. The DDRCTL in turn issues commands on
+the DDR PHY Interface (DFI) to the PHY module, which launches and captures data
+to and from the SDRAM. The driveway PMUs have hardware logic to gather
+statistics and performance logging signals on HIF, DFI, etc.
+
+By counting the READ, WRITE and RMW commands sent to the DDRC through the HIF
+interface, we could calculate the bandwidth. Example usage of counting memory
+data bandwidth::
+
+  perf stat \
+    -e ali_drw_21000/hif_wr/ \
+    -e ali_drw_21000/hif_rd/ \
+    -e ali_drw_21000/hif_rmw/ \
+    -e ali_drw_21000/cycle/ \
+    -e ali_drw_21080/hif_wr/ \
+    -e ali_drw_21080/hif_rd/ \
+    -e ali_drw_21080/hif_rmw/ \
+    -e ali_drw_21080/cycle/ \
+    -e ali_drw_23000/hif_wr/ \
+    -e ali_drw_23000/hif_rd/ \
+    -e ali_drw_23000/hif_rmw/ \
+    -e ali_drw_23000/cycle/ \
+    -e ali_drw_23080/hif_wr/ \
+    -e ali_drw_23080/hif_rd/ \
+    -e ali_drw_23080/hif_rmw/ \
+    -e ali_drw_23080/cycle/ \
+    -e ali_drw_25000/hif_wr/ \
+    -e ali_drw_25000/hif_rd/ \
+    -e ali_drw_25000/hif_rmw/ \
+    -e ali_drw_25000/cycle/ \
+    -e ali_drw_25080/hif_wr/ \
+    -e ali_drw_25080/hif_rd/ \
+    -e ali_drw_25080/hif_rmw/ \
+    -e ali_drw_25080/cycle/ \
+    -e ali_drw_27000/hif_wr/ \
+    -e ali_drw_27000/hif_rd/ \
+    -e ali_drw_27000/hif_rmw/ \
+    -e ali_drw_27000/cycle/ \
+    -e ali_drw_27080/hif_wr/ \
+    -e ali_drw_27080/hif_rd/ \
+    -e ali_drw_27080/hif_rmw/ \
+    -e ali_drw_27080/cycle/ -- sleep 10
+
+Example usage of counting all memory read/write bandwidth by metric::
+
+  perf stat -M ddr_read_bandwidth.all -- sleep 10
+  perf stat -M ddr_write_bandwidth.all -- sleep 10
+
+The average DRAM bandwidth can be calculated as follows:
+
+- Read Bandwidth =  perf_hif_rd * DDRC_WIDTH * DDRC_Freq / DDRC_Cycle
+- Write Bandwidth = (perf_hif_wr + perf_hif_rmw) * DDRC_WIDTH * DDRC_Freq / DDRC_Cycle
+
+Here, DDRC_WIDTH = 64 bytes.
+
+The current driver does not support sampling. So "perf record" is
+unsupported.  Also attach to a task is unsupported as the events are all
+uncore.
diff --git a/Documentation/admin-guide/perf/ampere_cspmu.rst b/Documentation/admin-guide/perf/ampere_cspmu.rst
new file mode 100644
index 000000000..94f93f5ae
--- /dev/null
+++ b/Documentation/admin-guide/perf/ampere_cspmu.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================================
+Ampere SoC Performance Monitoring Unit (PMU)
+============================================
+
+Ampere SoC PMU is a generic PMU IP that follows Arm CoreSight PMU architecture.
+Therefore, the driver is implemented as a submodule of arm_cspmu driver. At the
+first phase it's used for counting MCU events on AmpereOne.
+
+
+MCU PMU events
+--------------
+
+The PMU driver supports setting filters for "rank", "bank", and "threshold".
+Note, that the filters are per PMU instance rather than per event.
+
+
+Example for perf tool use::
+
+  / # perf list ampere
+
+    ampere_mcu_pmu_0/act_sent/                         [Kernel PMU event]
+    <...>
+    ampere_mcu_pmu_1/rd_sent/                          [Kernel PMU event]
+    <...>
+
+  / # perf stat -a -e ampere_mcu_pmu_0/act_sent,bank=5,rank=3,threshold=2/,ampere_mcu_pmu_1/rd_sent/ \
+        sleep 1
diff --git a/Documentation/admin-guide/perf/arm-ccn.rst b/Documentation/admin-guide/perf/arm-ccn.rst
new file mode 100644
index 000000000..f62f7fe50
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm-ccn.rst
@@ -0,0 +1,61 @@
+==========================
+ARM Cache Coherent Network
+==========================
+
+CCN-504 is a ring-bus interconnect consisting of 11 crosspoints
+(XPs), with each crosspoint supporting up to two device ports,
+so nodes (devices) 0 and 1 are connected to crosspoint 0,
+nodes 2 and 3 to crosspoint 1 etc.
+
+PMU (perf) driver
+-----------------
+
+The CCN driver registers a perf PMU driver, which provides
+description of available events and configuration options
+in sysfs, see /sys/bus/event_source/devices/ccn*.
+
+The "format" directory describes format of the config, config1
+and config2 fields of the perf_event_attr structure. The "events"
+directory provides configuration templates for all documented
+events, that can be used with perf tool. For example "xp_valid_flit"
+is an equivalent of "type=0x8,event=0x4". Other parameters must be
+explicitly specified.
+
+For events originating from device, "node" defines its index.
+
+Crosspoint PMU events require "xp" (index), "bus" (bus number)
+and "vc" (virtual channel ID).
+
+Crosspoint watchpoint-based events (special "event" value 0xfe)
+require "xp" and "vc" as above plus "port" (device port index),
+"dir" (transmit/receive direction), comparator values ("cmp_l"
+and "cmp_h") and "mask", being index of the comparator mask.
+
+Masks are defined separately from the event description
+(due to limited number of the config values) in the "cmp_mask"
+directory, with first 8 configurable by user and additional
+4 hardcoded for the most frequent use cases.
+
+Cycle counter is described by a "type" value 0xff and does
+not require any other settings.
+
+The driver also provides a "cpumask" sysfs attribute, which contains
+a single CPU ID, of the processor which will be used to handle all
+the CCN PMU events. It is recommended that the user space tools
+request the events on this processor (if not, the perf_event->cpu value
+will be overwritten anyway). In case of this processor being offlined,
+the events are migrated to another one and the attribute is updated.
+
+Example of perf tool use::
+
+  / # perf list | grep ccn
+    ccn/cycles/                                        [Kernel PMU event]
+  <...>
+    ccn/xp_valid_flit,xp=?,port=?,vc=?,dir=?/          [Kernel PMU event]
+  <...>
+
+  / # perf stat -a -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \
+                                                                         sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task (without "-a") perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/arm-cmn.rst b/Documentation/admin-guide/perf/arm-cmn.rst
new file mode 100644
index 000000000..796e25b70
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm-cmn.rst
@@ -0,0 +1,65 @@
+=============================
+Arm Coherent Mesh Network PMU
+=============================
+
+CMN-600 is a configurable mesh interconnect consisting of a rectangular
+grid of crosspoints (XPs), with each crosspoint supporting up to two
+device ports to which various AMBA CHI agents are attached.
+
+CMN implements a distributed PMU design as part of its debug and trace
+functionality. This consists of a local monitor (DTM) at every XP, which
+counts up to 4 event signals from the connected device nodes and/or the
+XP itself. Overflow from these local counters is accumulated in up to 8
+global counters implemented by the main controller (DTC), which provides
+overall PMU control and interrupts for global counter overflow.
+
+PMU events
+----------
+
+The PMU driver registers a single PMU device for the whole interconnect,
+see /sys/bus/event_source/devices/arm_cmn_0. Multi-chip systems may link
+more than one CMN together via external CCIX links - in this situation,
+each mesh counts its own events entirely independently, and additional
+PMU devices will be named arm_cmn_{1..n}.
+
+Most events are specified in a format based directly on the TRM
+definitions - "type" selects the respective node type, and "eventid" the
+event number. Some events require an additional occupancy ID, which is
+specified by "occupid".
+
+* Since RN-D nodes do not have any distinct events from RN-I nodes, they
+  are treated as the same type (0xa), and the common event templates are
+  named "rnid_*".
+
+* The cycle counter is treated as a synthetic event belonging to the DTC
+  node ("type" == 0x3, "eventid" is ignored).
+
+* XP events also encode the port and channel in the "eventid" field, to
+  match the underlying pmu_event0_id encoding for the pmu_event_sel
+  register. The event templates are named with prefixes to cover all
+  permutations.
+
+By default each event provides an aggregate count over all nodes of the
+given type. To target a specific node, "bynodeid" must be set to 1 and
+"nodeid" to the appropriate value derived from the CMN configuration
+(as defined in the "Node ID Mapping" section of the TRM).
+
+Watchpoints
+-----------
+
+The PMU can also count watchpoint events to monitor specific flit
+traffic. Watchpoints are treated as a synthetic event type, and like PMU
+events can be global or targeted with a particular XP's "nodeid" value.
+Since the watchpoint direction is otherwise implicit in the underlying
+register selection, separate events are provided for flit uploads and
+downloads.
+
+The flit match value and mask are passed in config1 and config2 ("val"
+and "mask" respectively). "wp_dev_sel", "wp_chn_sel", "wp_grp" and
+"wp_exclusive" are specified per the TRM definitions for dtm_wp_config0.
+Where a watchpoint needs to match fields from both match groups on the
+REQ or SNP channel, it can be specified as two events - one for each
+group - with the same nonzero "combine" value. The count for such a
+pair of combined events will be attributed to the primary match.
+Watchpoint events with a "combine" value of 0 are considered independent
+and will count individually.
diff --git a/Documentation/admin-guide/perf/arm-ni.rst b/Documentation/admin-guide/perf/arm-ni.rst
new file mode 100644
index 000000000..d26a8f697
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm-ni.rst
@@ -0,0 +1,17 @@
+====================================
+Arm Network-on Chip Interconnect PMU
+====================================
+
+NI-700 and friends implement a distinct PMU for each clock domain within the
+interconnect. Correspondingly, the driver exposes multiple PMU devices named
+arm_ni_<x>_cd_<y>, where <x> is an (arbitrary) instance identifier and <y> is
+the clock domain ID within that particular instance. If multiple NI instances
+exist within a system, the PMU devices can be correlated with the underlying
+hardware instance via sysfs parentage.
+
+Each PMU exposes base event aliases for the interface types present in its clock
+domain. These require qualifying with the "eventid" and "nodeid" parameters
+to specify the event code to count and the interface at which to count it
+(per the configured hardware ID as reflected in the xxNI_NODE_INFO register).
+The exception is the "cycles" alias for the PMU cycle counter, which is encoded
+with the PMU node type and needs no further qualification.
diff --git a/Documentation/admin-guide/perf/arm_dsu_pmu.rst b/Documentation/admin-guide/perf/arm_dsu_pmu.rst
new file mode 100644
index 000000000..7fd34db75
--- /dev/null
+++ b/Documentation/admin-guide/perf/arm_dsu_pmu.rst
@@ -0,0 +1,29 @@
+==================================
+ARM DynamIQ Shared Unit (DSU) PMU
+==================================
+
+ARM DynamIQ Shared Unit integrates one or more cores with an L3 memory system,
+control logic and external interfaces to form a multicore cluster. The PMU
+allows counting the various events related to the L3 cache, Snoop Control Unit
+etc, using 32bit independent counters. It also provides a 64bit cycle counter.
+
+The PMU can only be accessed via CPU system registers and are common to the
+cores connected to the same DSU. Like most of the other uncore PMUs, DSU
+PMU doesn't support process specific events and cannot be used in sampling mode.
+
+The DSU provides a bitmap for a subset of implemented events via hardware
+registers. There is no way for the driver to determine if the other events
+are available or not. Hence the driver exposes only those events advertised
+by the DSU, in "events" directory under::
+
+  /sys/bus/event_sources/devices/arm_dsu_<N>/
+
+The user should refer to the TRM of the product to figure out the supported events
+and use the raw event code for the unlisted events.
+
+The driver also exposes the CPUs connected to the DSU instance in "associated_cpus".
+
+
+e.g usage::
+
+	perf stat -a -e arm_dsu_0/cycles/
diff --git a/Documentation/admin-guide/perf/cxl.rst b/Documentation/admin-guide/perf/cxl.rst
new file mode 100644
index 000000000..9233ea0d0
--- /dev/null
+++ b/Documentation/admin-guide/perf/cxl.rst
@@ -0,0 +1,68 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+CXL Performance Monitoring Unit (CPMU)
+======================================
+
+The CXL rev 3.0 specification provides a definition of CXL Performance
+Monitoring Unit in section 13.2: Performance Monitoring.
+
+CXL components (e.g. Root Port, Switch Upstream Port, End Point) may have
+any number of CPMU instances. CPMU capabilities are fully discoverable from
+the devices. The specification provides event definitions for all CXL protocol
+message types and a set of additional events for things commonly counted on
+CXL devices (e.g. DRAM events).
+
+CPMU driver
+===========
+
+The CPMU driver registers a perf PMU with the name pmu_mem<X>.<Y> on the CXL bus
+representing the Yth CPMU for memX.
+
+    /sys/bus/cxl/device/pmu_mem<X>.<Y>
+
+The associated PMU is registered as
+
+   /sys/bus/event_sources/devices/cxl_pmu_mem<X>.<Y>
+
+In common with other CXL bus devices, the id has no specific meaning and the
+relationship to specific CXL device should be established via the device parent
+of the device on the CXL bus.
+
+PMU driver provides description of available events and filter options in sysfs.
+
+The "format" directory describes all formats of the config (event vendor id,
+group id and mask) config1 (threshold, filter enables) and config2 (filter
+parameters) fields of the perf_event_attr structure.  The "events" directory
+describes all documented events show in perf list.
+
+The events shown in perf list are the most fine grained events with a single
+bit of the event mask set. More general events may be enable by setting
+multiple mask bits in config. For example, all Device to Host Read Requests
+may be captured on a single counter by setting the bits for all of
+
+* d2h_req_rdcurr
+* d2h_req_rdown
+* d2h_req_rdshared
+* d2h_req_rdany
+* d2h_req_rdownnodata
+
+Example of usage::
+
+  $#perf list
+  cxl_pmu_mem0.0/clock_ticks/                        [Kernel PMU event]
+  cxl_pmu_mem0.0/d2h_req_rdshared/                   [Kernel PMU event]
+  cxl_pmu_mem0.0/h2d_req_snpcur/                     [Kernel PMU event]
+  cxl_pmu_mem0.0/h2d_req_snpdata/                    [Kernel PMU event]
+  cxl_pmu_mem0.0/h2d_req_snpinv/                     [Kernel PMU event]
+  -----------------------------------------------------------
+
+  $# perf stat -a -e cxl_pmu_mem0.0/clock_ticks/ -e cxl_pmu_mem0.0/d2h_req_rdshared/
+
+Vendor specific events may also be available and if so can be used via
+
+  $# perf stat -a -e cxl_pmu_mem0.0/vid=VID,gid=GID,mask=MASK/
+
+The driver does not support sampling so "perf record" is unsupported.
+It only supports system-wide counting so attaching to a task is
+unsupported.
diff --git a/Documentation/admin-guide/perf/dwc_pcie_pmu.rst b/Documentation/admin-guide/perf/dwc_pcie_pmu.rst
new file mode 100644
index 000000000..167f9281f
--- /dev/null
+++ b/Documentation/admin-guide/perf/dwc_pcie_pmu.rst
@@ -0,0 +1,94 @@
+======================================================================
+Synopsys DesignWare Cores (DWC) PCIe Performance Monitoring Unit (PMU)
+======================================================================
+
+DesignWare Cores (DWC) PCIe PMU
+===============================
+
+The PMU is a PCIe configuration space register block provided by each PCIe Root
+Port in a Vendor-Specific Extended Capability named RAS D.E.S (Debug, Error
+injection, and Statistics).
+
+As the name indicates, the RAS DES capability supports system level
+debugging, AER error injection, and collection of statistics. To facilitate
+collection of statistics, Synopsys DesignWare Cores PCIe controller
+provides the following two features:
+
+- one 64-bit counter for Time Based Analysis (RX/TX data throughput and
+  time spent in each low-power LTSSM state) and
+- one 32-bit counter per event for Event Counting (error and non-error
+  events for a specified lane)
+
+Note: There is no interrupt for counter overflow.
+
+Time Based Analysis
+-------------------
+
+Using this feature you can obtain information regarding RX/TX data
+throughput and time spent in each low-power LTSSM state by the controller.
+The PMU measures data in two categories:
+
+- Group#0: Percentage of time the controller stays in LTSSM states.
+- Group#1: Amount of data processed (Units of 16 bytes).
+
+Lane Event counters
+-------------------
+
+Using this feature you can obtain Error and Non-Error information in
+specific lane by the controller. The PMU event is selected by all of:
+
+- Group i
+- Event j within the Group i
+- Lane k
+
+Some of the events only exist for specific configurations.
+
+DesignWare Cores (DWC) PCIe PMU Driver
+=======================================
+
+This driver adds PMU devices for each PCIe Root Port named based on the SBDF of
+the Root Port. For example,
+
+    0001:30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
+
+the PMU device name for this Root Port is dwc_rootport_13018.
+
+The DWC PCIe PMU driver registers a perf PMU driver, which provides
+description of available events and configuration options in sysfs, see
+/sys/bus/event_source/devices/dwc_rootport_{sbdf}.
+
+The "format" directory describes format of the config fields of the
+perf_event_attr structure. The "events" directory provides configuration
+templates for all documented events.  For example,
+"rx_pcie_tlp_data_payload" is an equivalent of "eventid=0x21,type=0x0".
+
+The "perf list" command shall list the available events from sysfs, e.g.::
+
+    $# perf list | grep dwc_rootport
+    <...>
+    dwc_rootport_13018/Rx_PCIe_TLP_Data_Payload/        [Kernel PMU event]
+    <...>
+    dwc_rootport_13018/rx_memory_read,lane=?/               [Kernel PMU event]
+
+Time Based Analysis Event Usage
+-------------------------------
+
+Example usage of counting PCIe RX TLP data payload (Units of bytes)::
+
+    $# perf stat -a -e dwc_rootport_13018/Rx_PCIe_TLP_Data_Payload/
+
+The average RX/TX bandwidth can be calculated using the following formula:
+
+    PCIe RX Bandwidth = rx_pcie_tlp_data_payload / Measure_Time_Window
+    PCIe TX Bandwidth = tx_pcie_tlp_data_payload / Measure_Time_Window
+
+Lane Event Usage
+-------------------------------
+
+Each lane has the same event set and to avoid generating a list of hundreds
+of events, the user need to specify the lane ID explicitly, e.g.::
+
+    $# perf stat -a -e dwc_rootport_13018/rx_memory_read,lane=4/
+
+The driver does not support sampling, therefore "perf record" will not
+work. Per-task (without "-a") perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst b/Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst
new file mode 100644
index 000000000..2ec0249e3
--- /dev/null
+++ b/Documentation/admin-guide/perf/fujitsu_uncore_pmu.rst
@@ -0,0 +1,115 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+================================================
+Fujitsu Uncore Performance Monitoring Unit (PMU)
+================================================
+
+This driver supports the Uncore MAC PMUs and the Uncore PCI PMUs found
+in Fujitsu chips.
+Each MAC PMU on these chips is exposed as a uncore perf PMU with device name
+mac_iod<iod>_mac<mac>_ch<ch>.
+And each PCI PMU on these chips is exposed as a uncore perf PMU with device name
+pci_iod<iod>_pci<pci>.
+
+The driver provides a description of its available events and configuration
+options in sysfs, see /sys/bus/event_sources/devices/mac_iod<iod>_mac<mac>_ch<ch>/
+and /sys/bus/event_sources/devices/pci_iod<iod>_pci<pci>/.
+This driver exports:
+
+- formats, used by perf user space and other tools to configure events
+- events, used by perf user space and other tools to create events
+  symbolically, e.g.::
+
+    perf stat -a -e mac_iod0_mac0_ch0/event=0x21/ ls
+    perf stat -a -e pci_iod0_pci0/event=0x24/ ls
+
+- cpumask, used by perf user space and other tools to know on which CPUs
+  to open the events
+
+This driver supports the following events for MAC:
+
+- cycles
+  This event counts MAC cycles at MAC frequency.
+- read-count
+  This event counts the number of read requests to MAC.
+- read-count-request
+  This event counts the number of read requests including retry to MAC.
+- read-count-return
+  This event counts the number of responses to read requests to MAC.
+- read-count-request-pftgt
+  This event counts the number of read requests including retry with PFTGT
+  flag.
+- read-count-request-normal
+  This event counts the number of read requests including retry without PFTGT
+  flag.
+- read-count-return-pftgt-hit
+  This event counts the number of responses to read requests which hit the
+  PFTGT buffer.
+- read-count-return-pftgt-miss
+  This event counts the number of responses to read requests which miss the
+  PFTGT buffer.
+- read-wait
+  This event counts outstanding read requests issued by DDR memory controller
+  per cycle.
+- write-count
+  This event counts the number of write requests to MAC (including zero write,
+  full write, partial write, write cancel).
+- write-count-write
+  This event counts the number of full write requests to MAC (not including
+  zero write).
+- write-count-pwrite
+  This event counts the number of partial write requests to MAC.
+- memory-read-count
+  This event counts the number of read requests from MAC to memory.
+- memory-write-count
+  This event counts the number of full write requests from MAC to memory.
+- memory-pwrite-count
+  This event counts the number of partial write requests from MAC to memory.
+- ea-mac
+  This event counts energy consumption of MAC.
+- ea-memory
+  This event counts energy consumption of memory.
+- ea-memory-mac-write
+  This event counts the number of write requests from MAC to memory.
+- ea-ha
+  This event counts energy consumption of HA.
+
+  'ea' is the abbreviation for 'Energy Analyzer'.
+
+Examples for use with perf::
+
+  perf stat -e mac_iod0_mac0_ch0/ea-mac/ ls
+
+And, this driver supports the following events for PCI:
+
+- pci-port0-cycles
+  This event counts PCI cycles at PCI frequency in port0.
+- pci-port0-read-count
+  This event counts read transactions for data transfer in port0.
+- pci-port0-read-count-bus
+  This event counts read transactions for bus usage in port0.
+- pci-port0-write-count
+  This event counts write transactions for data transfer in port0.
+- pci-port0-write-count-bus
+  This event counts write transactions for bus usage in port0.
+- pci-port1-cycles
+  This event counts PCI cycles at PCI frequency in port1.
+- pci-port1-read-count
+  This event counts read transactions for data transfer in port1.
+- pci-port1-read-count-bus
+  This event counts read transactions for bus usage in port1.
+- pci-port1-write-count
+  This event counts write transactions for data transfer in port1.
+- pci-port1-write-count-bus
+  This event counts write transactions for bus usage in port1.
+- ea-pci
+  This event counts energy consumption of PCI.
+
+  'ea' is the abbreviation for 'Energy Analyzer'.
+
+Examples for use with perf::
+
+  perf stat -e pci_iod0_pci0/ea-pci/ ls
+
+Given that these are uncore PMUs the driver does not support sampling, therefore
+"perf record" will not work. Per-task perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/hisi-pcie-pmu.rst b/Documentation/admin-guide/perf/hisi-pcie-pmu.rst
new file mode 100644
index 000000000..083ca50de
--- /dev/null
+++ b/Documentation/admin-guide/perf/hisi-pcie-pmu.rst
@@ -0,0 +1,148 @@
+================================================
+HiSilicon PCIe Performance Monitoring Unit (PMU)
+================================================
+
+On Hip09, HiSilicon PCIe Performance Monitoring Unit (PMU) could monitor
+bandwidth, latency, bus utilization and buffer occupancy data of PCIe.
+
+Each PCIe Core has a PMU to monitor multi Root Ports of this PCIe Core and
+all Endpoints downstream these Root Ports.
+
+
+HiSilicon PCIe PMU driver
+=========================
+
+The PCIe PMU driver registers a perf PMU with the name of its sicl-id and PCIe
+Core id.::
+
+  /sys/bus/event_source/hisi_pcie<sicl>_core<core>
+
+PMU driver provides description of available events and filter options in sysfs,
+see /sys/bus/event_source/devices/hisi_pcie<sicl>_core<core>.
+
+The "format" directory describes all formats of the config (events) and config1
+(filter options) fields of the perf_event_attr structure. The "events" directory
+describes all documented events shown in perf list.
+
+The "identifier" sysfs file allows users to identify the version of the
+PMU hardware device.
+
+The "bus" sysfs file allows users to get the bus number of Root Ports
+monitored by PMU. Furthermore users can get the Root Ports range in
+[bdf_min, bdf_max] from "bdf_min" and "bdf_max" sysfs attributes
+respectively.
+
+Example usage of perf::
+
+  $# perf list
+  hisi_pcie0_core0/rx_mwr_latency/ [kernel PMU event]
+  hisi_pcie0_core0/rx_mwr_cnt/ [kernel PMU event]
+  ------------------------------------------
+
+  $# perf stat -e hisi_pcie0_core0/rx_mwr_latency,port=0xffff/
+  $# perf stat -e hisi_pcie0_core0/rx_mwr_cnt,port=0xffff/
+
+The related events usually used to calculate the bandwidth, latency or others.
+They need to start and end counting at the same time, therefore related events
+are best used in the same event group to get the expected value. There are two
+ways to know if they are related events:
+
+a) By event name, such as the latency events "xxx_latency, xxx_cnt" or
+   bandwidth events "xxx_flux, xxx_time".
+b) By event type, such as "event=0xXXXX, event=0x1XXXX".
+
+Example usage of perf group::
+
+  $# perf stat -e "{hisi_pcie0_core0/rx_mwr_latency,port=0xffff/,hisi_pcie0_core0/rx_mwr_cnt,port=0xffff/}"
+
+The current driver does not support sampling. So "perf record" is unsupported.
+Also attach to a task is unsupported for PCIe PMU.
+
+Filter options
+--------------
+
+1. Target filter
+
+   PMU could only monitor the performance of traffic downstream target Root
+   Ports or downstream target Endpoint. PCIe PMU driver support "port" and
+   "bdf" interfaces for users.
+   Please notice that, one of these two interfaces must be set, and these two
+   interfaces aren't supported at the same time. If they are both set, only
+   "port" filter is valid.
+   If "port" filter not being set or is set explicitly to zero (default), the
+   "bdf" filter will be in effect, because "bdf=0" meaning 0000:000:00.0.
+
+   - port
+
+     "port" filter can be used in all PCIe PMU events, target Root Port can be
+     selected by configuring the 16-bits-bitmap "port". Multi ports can be
+     selected for AP-layer-events, and only one port can be selected for
+     TL/DL-layer-events.
+
+     For example, if target Root Port is 0000:00:00.0 (x8 lanes), bit0 of
+     bitmap should be set, port=0x1; if target Root Port is 0000:00:04.0 (x4
+     lanes), bit8 is set, port=0x100; if these two Root Ports are both
+     monitored, port=0x101.
+
+     Example usage of perf::
+
+       $# perf stat -e hisi_pcie0_core0/rx_mwr_latency,port=0x1/ sleep 5
+
+   - bdf
+
+     "bdf" filter can only be used in bandwidth events, target Endpoint is
+     selected by configuring BDF to "bdf". Counter only counts the bandwidth of
+     message requested by target Endpoint.
+
+     For example, "bdf=0x3900" means BDF of target Endpoint is 0000:39:00.0.
+
+     Example usage of perf::
+
+       $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,bdf=0x3900/ sleep 5
+
+2. Trigger filter
+
+   Event statistics start when the first time TLP length is greater/smaller
+   than trigger condition. You can set the trigger condition by writing
+   "trig_len", and set the trigger mode by writing "trig_mode". This filter can
+   only be used in bandwidth events.
+
+   For example, "trig_len=4" means trigger condition is 2^4 DW, "trig_mode=0"
+   means statistics start when TLP length > trigger condition, "trig_mode=1"
+   means start when TLP length < condition.
+
+   Example usage of perf::
+
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,port=0xffff,trig_len=0x4,trig_mode=1/ sleep 5
+
+3. Threshold filter
+
+   Counter counts when TLP length within the specified range. You can set the
+   threshold by writing "thr_len", and set the threshold mode by writing
+   "thr_mode". This filter can only be used in bandwidth events.
+
+   For example, "thr_len=4" means threshold is 2^4 DW, "thr_mode=0" means
+   counter counts when TLP length >= threshold, and "thr_mode=1" means counts
+   when TLP length < threshold.
+
+   Example usage of perf::
+
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,port=0xffff,thr_len=0x4,thr_mode=1/ sleep 5
+
+4. TLP Length filter
+
+   When counting bandwidth, the data can be composed of certain parts of TLP
+   packets. You can specify it through "len_mode":
+
+   - 2'b00: Reserved (Do not use this since the behaviour is undefined)
+   - 2'b01: Bandwidth of TLP payloads
+   - 2'b10: Bandwidth of TLP headers
+   - 2'b11: Bandwidth of both TLP payloads and headers
+
+   For example, "len_mode=2" means only counting the bandwidth of TLP headers
+   and "len_mode=3" means the final bandwidth data is composed of both TLP
+   headers and payloads. Default value if not specified is 2'b11.
+
+   Example usage of perf::
+
+     $# perf stat -e hisi_pcie0_core0/rx_mrd_flux,port=0xffff,len_mode=0x1/ sleep 5
diff --git a/Documentation/admin-guide/perf/hisi-pmu.rst b/Documentation/admin-guide/perf/hisi-pmu.rst
new file mode 100644
index 000000000..d56b2d690
--- /dev/null
+++ b/Documentation/admin-guide/perf/hisi-pmu.rst
@@ -0,0 +1,177 @@
+======================================================
+HiSilicon SoC uncore Performance Monitoring Unit (PMU)
+======================================================
+
+The HiSilicon SoC chip includes various independent system device PMUs
+such as L3 cache (L3C), Hydra Home Agent (HHA) and DDRC. These PMUs are
+independent and have hardware logic to gather statistics and performance
+information.
+
+The HiSilicon SoC encapsulates multiple CPU and IO dies. Each CPU cluster
+(CCL) is made up of 4 cpu cores sharing one L3 cache; each CPU die is
+called Super CPU cluster (SCCL) and is made up of 6 CCLs. Each SCCL has
+two HHAs (0 - 1) and four DDRCs (0 - 3), respectively.
+
+HiSilicon SoC uncore PMU driver
+-------------------------------
+
+Each device PMU has separate registers for event counting, control and
+interrupt, and the PMU driver shall register perf PMU drivers like L3C,
+HHA and DDRC etc. The available events and configuration options shall
+be described in the sysfs, see::
+
+/sys/bus/event_source/devices/hisi_sccl{X}_<l3c{Y}/hha{Y}/ddrc{Y}>
+
+The "perf list" command shall list the available events from sysfs.
+
+Each L3C, HHA and DDRC is registered as a separate PMU with perf. The PMU
+name will appear in event listing as hisi_sccl<sccl-id>_module<index-id>.
+where "sccl-id" is the identifier of the SCCL and "index-id" is the index of
+module.
+
+e.g. hisi_sccl3_l3c0/rd_hit_cpipe is READ_HIT_CPIPE event of L3C index #0 in
+SCCL ID #3.
+
+e.g. hisi_sccl1_hha0/rx_operations is RX_OPERATIONS event of HHA index #0 in
+SCCL ID #1.
+
+The driver also provides a "cpumask" sysfs attribute, which shows the CPU core
+ID used to count the uncore PMU event. An "associated_cpus" sysfs attribute is
+also provided to show the CPUs associated with this PMU. The "cpumask" indicates
+the CPUs to open the events, usually as a hint for userspaces tools like perf.
+It only contains one associated CPU from the "associated_cpus".
+
+Example usage of perf::
+
+  $# perf list
+  hisi_sccl3_l3c0/rd_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl3_l3c0/wr_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl1_l3c0/rd_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+  hisi_sccl1_l3c0/wr_hit_cpipe/ [kernel PMU event]
+  ------------------------------------------
+
+  $# perf stat -a -e hisi_sccl3_l3c0/rd_hit_cpipe/ sleep 5
+  $# perf stat -a -e hisi_sccl3_l3c0/config=0x02/ sleep 5
+
+For HiSilicon uncore PMU v2 whose identifier is 0x30, the topology is the same
+as PMU v1, but some new functions are added to the hardware.
+
+1. L3C PMU supports filtering by core/thread within the cluster which can be
+specified as a bitmap::
+
+  $# perf stat -a -e hisi_sccl3_l3c0/config=0x02,tt_core=0x3/ sleep 5
+
+This will only count the operations from core/thread 0 and 1 in this cluster.
+
+User should not use tt_core_deprecated to specify the core/thread filtering.
+This option is provided for backward compatiblility and only support 8bit
+which may not cover all the core/thread sharing L3C.
+
+2. Tracetag allow the user to chose to count only read, write or atomic
+operations via the tt_req parameeter in perf. The default value counts all
+operations. tt_req is 3bits, 3'b100 represents read operations, 3'b101
+represents write operations, 3'b110 represents atomic store operations and
+3'b111 represents atomic non-store operations, other values are reserved::
+
+  $# perf stat -a -e hisi_sccl3_l3c0/config=0x02,tt_req=0x4/ sleep 5
+
+This will only count the read operations in this cluster.
+
+3. Datasrc allows the user to check where the data comes from. It is 5 bits.
+Some important codes are as follows:
+
+- 5'b00001: comes from L3C in this die;
+- 5'b01000: comes from L3C in the cross-die;
+- 5'b01001: comes from L3C which is in another socket;
+- 5'b01110: comes from the local DDR;
+- 5'b01111: comes from the cross-die DDR;
+- 5'b10000: comes from cross-socket DDR;
+
+etc, it is mainly helpful to find that the data source is nearest from the CPU
+cores. If datasrc_cfg is used in the multi-chips, the datasrc_skt shall be
+configured in perf command::
+
+  $# perf stat -a -e hisi_sccl3_l3c0/config=0xb9,datasrc_cfg=0xE/,
+  hisi_sccl3_l3c0/config=0xb9,datasrc_cfg=0xF/ sleep 5
+
+4. Some HiSilicon SoCs encapsulate multiple CPU and IO dies. Each CPU die
+contains several Compute Clusters (CCLs). The I/O dies are called Super I/O
+clusters (SICL) containing multiple I/O clusters (ICLs). Each CCL/ICL in the
+SoC has a unique ID. Each ID is 11bits, include a 6-bit SCCL-ID and 5-bit
+CCL/ICL-ID. For I/O die, the ICL-ID is followed by:
+
+- 5'b00000: I/O_MGMT_ICL;
+- 5'b00001: Network_ICL;
+- 5'b00011: HAC_ICL;
+- 5'b10000: PCIe_ICL;
+
+5. uring_channel: UC PMU events 0x47~0x59 supports filtering by tx request
+uring channel. It is 2 bits. Some important codes are as follows:
+
+- 2'b11: count the events which sent to the uring_ext (MATA) channel;
+- 2'b01: is the same as 2'b11;
+- 2'b10: count the events which sent to the uring (non-MATA) channel;
+- 2'b00: default value, count the events which sent to both uring and
+  uring_ext channels;
+
+6. ch: NoC PMU supports filtering the event counts of certain transaction
+channel with this option. The current supported channels are as follows:
+
+- 3'b010: Request channel
+- 3'b100: Snoop channel
+- 3'b110: Response channel
+- 3'b111: Data channel
+
+7. tt_en: NoC PMU supports counting only transactions that have tracetag set
+if this option is set. See the 2nd list for more information about tracetag.
+
+For HiSilicon uncore PMU v3 whose identifier is 0x40, some uncore PMUs are
+further divided into parts for finer granularity of tracing, each part has its
+own dedicated PMU, and all such PMUs together cover the monitoring job of events
+on particular uncore device. Such PMUs are described in sysfs with name format
+slightly changed::
+
+/sys/bus/event_source/devices/hisi_sccl{X}_<l3c{Y}_{Z}/ddrc{Y}_{Z}/noc{Y}_{Z}>
+
+Z is the sub-id, indicating different PMUs for part of hardware device.
+
+Usage of most PMUs with different sub-ids are identical. Specially, L3C PMU
+provides ``ext`` option to allow exploration of even finer granual statistics
+of L3C PMU.  L3C PMU driver uses that as hint of termination when delivering
+perf command to hardware:
+
+- ext=0: Default, could be used with event names.
+- ext=1 and ext=2: Must be used with event codes, event names are not supported.
+
+An example of perf command could be::
+
+  $# perf stat -a -e hisi_sccl0_l3c1_0/rd_spipe/ sleep 5
+
+or::
+
+  $# perf stat -a -e hisi_sccl0_l3c1_0/event=0x1,ext=1/ sleep 5
+
+As above, ``hisi_sccl0_l3c1_0`` locates PMU of Super CPU CLuster 0, L3 cache 1
+pipe0.
+
+First command locates the first part of L3C since ``ext=0`` is implied by
+default. Second command issues the counting on another part of L3C with the
+event ``0x1``.
+
+Users could configure IDs to count data come from specific CCL/ICL, by setting
+srcid_cmd & srcid_msk, and data desitined for specific CCL/ICL by setting
+tgtid_cmd & tgtid_msk. A set bit in srcid_msk/tgtid_msk means the PMU will not
+check the bit when matching against the srcid_cmd/tgtid_cmd.
+
+If all of these options are disabled, it can works by the default value that
+doesn't distinguish the filter condition and ID information and will return
+the total counter values in the PMU counters.
+
+The current driver does not support sampling. So "perf record" is unsupported.
+Also attach to a task is unsupported as the events are all uncore.
+
+Note: Please contact the maintainer for a complete list of events supported for
+the PMU devices in the SoC and its information if needed.
diff --git a/Documentation/admin-guide/perf/hns3-pmu.rst b/Documentation/admin-guide/perf/hns3-pmu.rst
new file mode 100644
index 000000000..1195e570f
--- /dev/null
+++ b/Documentation/admin-guide/perf/hns3-pmu.rst
@@ -0,0 +1,136 @@
+======================================
+HNS3 Performance Monitoring Unit (PMU)
+======================================
+
+HNS3(HiSilicon network system 3) Performance Monitoring Unit (PMU) is an
+End Point device to collect performance statistics of HiSilicon SoC NIC.
+On Hip09, each SICL(Super I/O cluster) has one PMU device.
+
+HNS3 PMU supports collection of performance statistics such as bandwidth,
+latency, packet rate and interrupt rate.
+
+Each HNS3 PMU supports 8 hardware events.
+
+HNS3 PMU driver
+===============
+
+The HNS3 PMU driver registers a perf PMU with the name of its sicl id.::
+
+  /sys/bus/event_source/devices/hns3_pmu_sicl_<sicl_id>
+
+PMU driver provides description of available events, filter modes, format,
+identifier and cpumask in sysfs.
+
+The "events" directory describes the event code of all supported events
+shown in perf list.
+
+The "filtermode" directory describes the supported filter modes of each
+event.
+
+The "format" directory describes all formats of the config (events) and
+config1 (filter options) fields of the perf_event_attr structure.
+
+The "identifier" file shows version of PMU hardware device.
+
+The "bdf_min" and "bdf_max" files show the supported bdf range of each
+pmu device.
+
+The "hw_clk_freq" file shows the hardware clock frequency of each pmu
+device.
+
+Example usage of checking event code and subevent code::
+
+  $# cat /sys/bus/event_source/devices/hns3_pmu_sicl_0/events/dly_tx_normal_to_mac_time
+  config=0x00204
+  $# cat /sys/bus/event_source/devices/hns3_pmu_sicl_0/events/dly_tx_normal_to_mac_packet_num
+  config=0x10204
+
+Each performance statistic has a pair of events to get two values to
+calculate real performance data in userspace.
+
+The bits 0~15 of config (here 0x0204) are the true hardware event code. If
+two events have same value of bits 0~15 of config, that means they are
+event pair. And the bit 16 of config indicates getting counter 0 or
+counter 1 of hardware event.
+
+After getting two values of event pair in userspace, the formula of
+computation to calculate real performance data is:::
+
+  counter 0 / counter 1
+
+Example usage of checking supported filter mode::
+
+  $# cat /sys/bus/event_source/devices/hns3_pmu_sicl_0/filtermode/bw_ssu_rpu_byte_num
+  filter mode supported: global/port/port-tc/func/func-queue/
+
+Example usage of perf::
+
+  $# perf list
+  hns3_pmu_sicl_0/bw_ssu_rpu_byte_num/ [kernel PMU event]
+  hns3_pmu_sicl_0/bw_ssu_rpu_time/     [kernel PMU event]
+  ------------------------------------------
+
+  $# perf stat -g -e hns3_pmu_sicl_0/bw_ssu_rpu_byte_num,global=1/ -e hns3_pmu_sicl_0/bw_ssu_rpu_time,global=1/ -I 1000
+  or
+  $# perf stat -g -e hns3_pmu_sicl_0/config=0x00002,global=1/ -e hns3_pmu_sicl_0/config=0x10002,global=1/ -I 1000
+
+
+Filter modes
+--------------
+
+1. global mode
+PMU collect performance statistics for all HNS3 PCIe functions of IO DIE.
+Set the "global" filter option to 1 will enable this mode.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,global=1/ -I 1000
+
+2. port mode
+PMU collect performance statistic of one whole physical port. The port id
+is same as mac id. The "tc" filter option must be set to 0xF in this mode,
+here tc stands for traffic class.
+
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,port=0,tc=0xF/ -I 1000
+
+3. port-tc mode
+PMU collect performance statistic of one tc of physical port. The port id
+is same as mac id. The "tc" filter option must be set to 0 ~ 7 in this
+mode.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,port=0,tc=0/ -I 1000
+
+4. func mode
+PMU collect performance statistic of one PF/VF. The function id is BDF of
+PF/VF, its conversion formula::
+
+  func = (bus << 8) + (device << 3) + (function)
+
+for example:
+  BDF         func
+  35:00.0    0x3500
+  35:00.1    0x3501
+  35:01.0    0x3508
+
+In this mode, the "queue" filter option must be set to 0xFFFF.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,bdf=0x3500,queue=0xFFFF/ -I 1000
+
+5. func-queue mode
+PMU collect performance statistic of one queue of PF/VF. The function id
+is BDF of PF/VF, the "queue" filter option must be set to the exact queue
+id of function.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,bdf=0x3500,queue=0/ -I 1000
+
+6. func-intr mode
+PMU collect performance statistic of one interrupt of PF/VF. The function
+id is BDF of PF/VF, the "intr" filter option must be set to the exact
+interrupt id of function.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x00301,bdf=0x3500,intr=0/ -I 1000
diff --git a/Documentation/admin-guide/perf/imx-ddr.rst b/Documentation/admin-guide/perf/imx-ddr.rst
new file mode 100644
index 000000000..77418ae5a
--- /dev/null
+++ b/Documentation/admin-guide/perf/imx-ddr.rst
@@ -0,0 +1,100 @@
+=====================================================
+Freescale i.MX8 DDR Performance Monitoring Unit (PMU)
+=====================================================
+
+There are no performance counters inside the DRAM controller, so performance
+signals are brought out to the edge of the controller where a set of 4 x 32 bit
+counters is implemented. This is controlled by the CSV modes programmed in counter
+control register which causes a large number of PERF signals to be generated.
+
+Selection of the value for each counter is done via the config registers. There
+is one register for each counter. Counter 0 is special in that it always counts
+“time” and when expired causes a lock on itself and the other counters and an
+interrupt is raised. If any other counter overflows, it continues counting, and
+no interrupt is raised.
+
+The "format" directory describes format of the config (event ID) and config1/2
+(AXI filter setting) fields of the perf_event_attr structure, see /sys/bus/event_source/
+devices/imx8_ddr0/format/. The "events" directory describes the events types
+hardware supported that can be used with perf tool, see /sys/bus/event_source/
+devices/imx8_ddr0/events/. The "caps" directory describes filter features implemented
+in DDR PMU, see /sys/bus/events_source/devices/imx8_ddr0/caps/.
+
+    .. code-block:: bash
+
+        perf stat -a -e imx8_ddr0/cycles/ cmd
+        perf stat -a -e imx8_ddr0/read/,imx8_ddr0/write/ cmd
+
+AXI filtering is only used by CSV modes 0x41 (axid-read) and 0x42 (axid-write)
+to count reading or writing matches filter setting. Filter setting is various
+from different DRAM controller implementations, which is distinguished by quirks
+in the driver. You also can dump info from userspace, "caps" directory show the
+type of AXI filter (filter, enhanced_filter and super_filter). Value 0 for
+un-supported, and value 1 for supported.
+
+* With DDR_CAP_AXI_ID_FILTER quirk(filter: 1, enhanced_filter: 0, super_filter: 0).
+  Filter is defined with two configuration parts:
+  --AXI_ID defines AxID matching value.
+  --AXI_MASKING defines which bits of AxID are meaningful for the matching.
+
+      - 0: corresponding bit is masked.
+      - 1: corresponding bit is not masked, i.e. used to do the matching.
+
+  AXI_ID and AXI_MASKING are mapped on DPCR1 register in performance counter.
+  When non-masked bits are matching corresponding AXI_ID bits then counter is
+  incremented. Perf counter is incremented if::
+
+        AxID && AXI_MASKING == AXI_ID && AXI_MASKING
+
+  This filter doesn't support filter different AXI ID for axid-read and axid-write
+  event at the same time as this filter is shared between counters.
+
+  .. code-block:: bash
+
+      perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+      perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD/ cmd
+
+  .. note::
+
+      axi_mask is inverted in userspace(i.e. set bits are bits to mask), and
+      it will be reverted in driver automatically. so that the user can just specify
+      axi_id to monitor a specific id, rather than having to specify axi_mask.
+
+  .. code-block:: bash
+
+        perf stat -a -e imx8_ddr0/axid-read,axi_id=0x12/ cmd, which will monitor ARID=0x12
+
+* With DDR_CAP_AXI_ID_FILTER_ENHANCED quirk(filter: 1, enhanced_filter: 1, super_filter: 0).
+  This is an extension to the DDR_CAP_AXI_ID_FILTER quirk which permits
+  counting the number of bytes (as opposed to the number of bursts) from DDR
+  read and write transactions concurrently with another set of data counters.
+
+* With DDR_CAP_AXI_ID_PORT_CHANNEL_FILTER quirk(filter: 0, enhanced_filter: 0, super_filter: 1).
+  There is a limitation in previous AXI filter, it cannot filter different IDs
+  at the same time as the filter is shared between counters. This quirk is the
+  extension of AXI ID filter. One improvement is that counter 1-3 has their own
+  filter, means that it supports concurrently filter various IDs. Another
+  improvement is that counter 1-3 supports AXI PORT and CHANNEL selection. Support
+  selecting address channel or data channel.
+
+  Filter is defined with 2 configuration registers per counter 1-3.
+  --Counter N MASK COMP register - including AXI_ID and AXI_MASKING.
+  --Counter N MUX CNTL register - including AXI CHANNEL and AXI PORT.
+
+      - 0: address channel
+      - 1: data channel
+
+  PMU in DDR subsystem, only one single port0 exists, so axi_port is reserved
+  which should be 0.
+
+  .. code-block:: bash
+
+      perf stat -a -e imx8_ddr0/axid-read,axi_mask=0xMMMM,axi_id=0xDDDD,axi_channel=0xH/ cmd
+      perf stat -a -e imx8_ddr0/axid-write,axi_mask=0xMMMM,axi_id=0xDDDD,axi_channel=0xH/ cmd
+
+  .. note::
+
+      axi_channel is inverted in userspace, and it will be reverted in driver
+      automatically. So that users do not need specify axi_channel if want to
+      monitor data channel from DDR transactions, since data channel is more
+      meaningful.
diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst
new file mode 100644
index 000000000..aa12708dd
--- /dev/null
+++ b/Documentation/admin-guide/perf/index.rst
@@ -0,0 +1,33 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+Performance monitor support
+===========================
+
+.. toctree::
+   :maxdepth: 1
+
+   hisi-pmu
+   hisi-pcie-pmu
+   hns3-pmu
+   imx-ddr
+   qcom_l2_pmu
+   qcom_l3_pmu
+   starfive_starlink_pmu
+   mrvl-odyssey-ddr-pmu
+   mrvl-odyssey-tad-pmu
+   arm-ccn
+   arm-cmn
+   arm-ni
+   xgene-pmu
+   arm_dsu_pmu
+   thunderx2-pmu
+   alibaba_pmu
+   dwc_pcie_pmu
+   nvidia-tegra241-pmu
+   nvidia-tegra410-pmu
+   meson-ddr-pmu
+   cxl
+   ampere_cspmu
+   mrvl-pem-pmu
+   fujitsu_uncore_pmu
diff --git a/Documentation/admin-guide/perf/meson-ddr-pmu.rst b/Documentation/admin-guide/perf/meson-ddr-pmu.rst
new file mode 100644
index 000000000..8e71be1d6
--- /dev/null
+++ b/Documentation/admin-guide/perf/meson-ddr-pmu.rst
@@ -0,0 +1,70 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================================================
+Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
+===========================================================
+
+The Amlogic Meson G12 SoC contains a bandwidth monitor inside DRAM controller.
+The monitor includes 4 channels. Each channel can count the request accessing
+DRAM. The channel can count up to 3 AXI port simultaneously. It can be helpful
+to show if the performance bottleneck is on DDR bandwidth.
+
+Currently, this driver supports the following 5 perf events:
+
++ meson_ddr_bw/total_rw_bytes/
++ meson_ddr_bw/chan_1_rw_bytes/
++ meson_ddr_bw/chan_2_rw_bytes/
++ meson_ddr_bw/chan_3_rw_bytes/
++ meson_ddr_bw/chan_4_rw_bytes/
+
+meson_ddr_bw/chan_{1,2,3,4}_rw_bytes/ events are channel-specific events.
+Each channel support filtering, which can let the channel to monitor
+individual IP module in SoC.
+
+Below are DDR access request event filter keywords:
+
++ arm             - from CPU
++ vpu_read1       - from OSD + VPP read
++ gpu             - from 3D GPU
++ pcie            - from PCIe controller
++ hdcp            - from HDCP controller
++ hevc_front      - from HEVC codec front end
++ usb3_0          - from USB3.0 controller
++ hevc_back       - from HEVC codec back end
++ h265enc         - from HEVC encoder
++ vpu_read2       - from DI read
++ vpu_write1      - from VDIN write
++ vpu_write2      - from di write
++ vdec            - from legacy codec video decoder
++ hcodec          - from H264 encoder
++ ge2d            - from ge2d
++ spicc1          - from SPI controller 1
++ usb0            - from USB2.0 controller 0
++ dma             - from system DMA controller 1
++ arb0            - from arb0
++ sd_emmc_b       - from SD eMMC b controller
++ usb1            - from USB2.0 controller 1
++ audio           - from Audio module
++ sd_emmc_c       - from SD eMMC c controller
++ spicc2          - from SPI controller 2
++ ethernet        - from Ethernet controller
+
+
+Examples:
+
+  + Show the total DDR bandwidth per seconds:
+
+    .. code-block:: bash
+
+       perf stat -a -e meson_ddr_bw/total_rw_bytes/ -I 1000 sleep 10
+
+
+  + Show individual DDR bandwidth from CPU and GPU respectively, as well as
+    sum of them:
+
+    .. code-block:: bash
+
+       perf stat -a -e meson_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
+       perf stat -a -e meson_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
+       perf stat -a -e meson_ddr_bw/chan_3_rw_bytes,arm=1,gpu=1/ -I 1000 sleep 10
+
diff --git a/Documentation/admin-guide/perf/mrvl-odyssey-ddr-pmu.rst b/Documentation/admin-guide/perf/mrvl-odyssey-ddr-pmu.rst
new file mode 100644
index 000000000..2e817593a
--- /dev/null
+++ b/Documentation/admin-guide/perf/mrvl-odyssey-ddr-pmu.rst
@@ -0,0 +1,80 @@
+===================================================================
+Marvell Odyssey DDR PMU Performance Monitoring Unit (PMU UNCORE)
+===================================================================
+
+Odyssey DRAM Subsystem supports eight counters for monitoring performance
+and software can program those counters to monitor any of the defined
+performance events. Supported performance events include those counted
+at the interface between the DDR controller and the PHY, interface between
+the DDR Controller and the CHI interconnect, or within the DDR Controller.
+
+Additionally DSS also supports two fixed performance event counters, one
+for ddr reads and the other for ddr writes.
+
+The counter will be operating in either manual or auto mode.
+
+The PMU driver exposes the available events and format options under sysfs::
+
+        /sys/bus/event_source/devices/mrvl_ddr_pmu_<>/events/
+        /sys/bus/event_source/devices/mrvl_ddr_pmu_<>/format/
+
+Examples::
+
+        $ perf list | grep ddr
+        mrvl_ddr_pmu_<>/ddr_act_bypass_access/   [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_bsm_alloc/           [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_bsm_starvation/      [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_active_access/   [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_mwr/             [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_rd_active_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_rd_or_wr_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_read/            [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_wr_access/       [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_cam_write/           [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_capar_error/         [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_crit_ref/            [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_ddr_reads/           [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_ddr_writes/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dfi_cmd_is_retry/    [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dfi_cycles/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dfi_parity_poison/   [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dfi_rd_data_access/  [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dfi_wr_data_access/  [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dqsosc_mpc/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_dqsosc_mrr/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_enter_mpsm/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_enter_powerdown/     [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_enter_selfref/       [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hif_pri_rdaccess/    [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hif_rd_access/       [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hif_rd_or_wr_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hif_rmw_access/      [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hif_wr_access/       [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_hpri_sched_rd_crit_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_load_mode/           [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_lpri_sched_rd_crit_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_precharge/           [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_precharge_for_other/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_precharge_for_rdwr/  [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_raw_hazard/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_rd_bypass_access/    [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_rd_crc_error/        [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_rd_uc_ecc_error/     [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_rdwr_transitions/    [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_refresh/             [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_retry_fifo_full/     [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_spec_ref/            [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_tcr_mrr/             [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_war_hazard/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_waw_hazard/          [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_win_limit_reached_rd/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_win_limit_reached_wr/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_wr_crc_error/        [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_wr_trxn_crit_access/ [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_write_combine/       [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_zqcl/                [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_zqlatch/             [Kernel PMU event]
+        mrvl_ddr_pmu_<>/ddr_zqstart/             [Kernel PMU event]
+
+        $ perf stat -e ddr_cam_read,ddr_cam_write,ddr_cam_active_access,ddr_cam
+          rd_or_wr_access,ddr_cam_rd_active_access,ddr_cam_mwr <workload>
diff --git a/Documentation/admin-guide/perf/mrvl-odyssey-tad-pmu.rst b/Documentation/admin-guide/perf/mrvl-odyssey-tad-pmu.rst
new file mode 100644
index 000000000..ad1975b14
--- /dev/null
+++ b/Documentation/admin-guide/perf/mrvl-odyssey-tad-pmu.rst
@@ -0,0 +1,37 @@
+====================================================================
+Marvell Odyssey LLC-TAD Performance Monitoring Unit (PMU UNCORE)
+====================================================================
+
+Each TAD provides eight 64-bit counters for monitoring
+cache behavior.The driver always configures the same counter for
+all the TADs. The user would end up effectively reserving one of
+eight counters in every TAD to look across all TADs.
+The occurrences of events are aggregated and presented to the user
+at the end of running the workload. The driver does not provide a
+way for the user to partition TADs so that different TADs are used for
+different applications.
+
+The performance events reflect various internal or interface activities.
+By combining the values from multiple performance counters, cache
+performance can be measured in terms such as: cache miss rate, cache
+allocations, interface retry rate, internal resource occupancy, etc.
+
+The PMU driver exposes the available events and format options under sysfs::
+
+        /sys/bus/event_source/devices/tad/events/
+        /sys/bus/event_source/devices/tad/format/
+
+Examples::
+
+   $ perf list | grep tad
+        tad/tad_alloc_any/                                 [Kernel PMU event]
+        tad/tad_alloc_dtg/                                 [Kernel PMU event]
+        tad/tad_alloc_ltg/                                 [Kernel PMU event]
+        tad/tad_hit_any/                                   [Kernel PMU event]
+        tad/tad_hit_dtg/                                   [Kernel PMU event]
+        tad/tad_hit_ltg/                                   [Kernel PMU event]
+        tad/tad_req_msh_in_exlmn/                          [Kernel PMU event]
+        tad/tad_tag_rd/                                    [Kernel PMU event]
+        tad/tad_tot_cycle/                                 [Kernel PMU event]
+
+   $ perf stat -e tad_alloc_dtg,tad_alloc_ltg,tad_alloc_any,tad_hit_dtg,tad_hit_ltg,tad_hit_any,tad_tag_rd <workload>
diff --git a/Documentation/admin-guide/perf/mrvl-pem-pmu.rst b/Documentation/admin-guide/perf/mrvl-pem-pmu.rst
new file mode 100644
index 000000000..c39007149
--- /dev/null
+++ b/Documentation/admin-guide/perf/mrvl-pem-pmu.rst
@@ -0,0 +1,56 @@
+=================================================================
+Marvell Odyssey PEM Performance Monitoring Unit (PMU UNCORE)
+=================================================================
+
+The PCI Express Interface Units(PEM) are associated with a corresponding
+monitoring unit. This includes performance counters to track various
+characteristics of the data that is transmitted over the PCIe link.
+
+The counters track inbound and outbound transactions which
+includes separate counters for posted/non-posted/completion TLPs.
+Also, inbound and outbound memory read requests along with their
+latencies can also be monitored. Address Translation Services(ATS)events
+such as ATS Translation, ATS Page Request, ATS Invalidation along with
+their corresponding latencies are also tracked.
+
+There are separate 64 bit counters to measure posted/non-posted/completion
+tlps in inbound and outbound transactions. ATS events are measured by
+different counters.
+
+The PMU driver exposes the available events and format options under sysfs,
+/sys/bus/event_source/devices/mrvl_pcie_rc_pmu_<>/events/
+/sys/bus/event_source/devices/mrvl_pcie_rc_pmu_<>/format/
+
+Examples::
+
+  # perf list | grep mrvl_pcie_rc_pmu
+  mrvl_pcie_rc_pmu_<>/ats_inv/             [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ats_inv_latency/     [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ats_pri/             [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ats_pri_latency/     [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ats_trans/           [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ats_trans_latency/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_inflight/         [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_reads/            [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_req_no_ro_ebus/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_req_no_ro_ncb/    [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_cpl_partid/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_dwords_cpl_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_dwords_npr/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_dwords_pr/    [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_npr/          [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ib_tlp_pr/           [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_inflight_partid/  [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_merges_cpl_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_merges_npr_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_merges_pr_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_reads_partid/     [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_cpl_partid/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_dwords_cpl_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_dwords_npr_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_dwords_pr_partid/ [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_npr_partid/   [Kernel PMU event]
+  mrvl_pcie_rc_pmu_<>/ob_tlp_pr_partid/    [Kernel PMU event]
+
+
+  # perf stat -e ib_inflight,ib_reads,ib_req_no_ro_ebus,ib_req_no_ro_ncb <workload>
diff --git a/Documentation/admin-guide/perf/nvidia-tegra241-pmu.rst b/Documentation/admin-guide/perf/nvidia-tegra241-pmu.rst
new file mode 100644
index 000000000..fad5bc4ce
--- /dev/null
+++ b/Documentation/admin-guide/perf/nvidia-tegra241-pmu.rst
@@ -0,0 +1,333 @@
+============================================================
+NVIDIA Tegra241 SoC Uncore Performance Monitoring Unit (PMU)
+============================================================
+
+The NVIDIA Tegra241 SoC includes various system PMUs to measure key performance
+metrics like memory bandwidth, latency, and utilization:
+
+* Scalable Coherency Fabric (SCF)
+* NVLink-C2C0
+* NVLink-C2C1
+* CNVLink
+* PCIE
+
+PMU Driver
+----------
+
+The PMUs in this document are based on ARM CoreSight PMU Architecture as
+described in document: ARM IHI 0091. Since this is a standard architecture, the
+PMUs are managed by a common driver "arm-cs-arch-pmu". This driver describes
+the available events and configuration of each PMU in sysfs. Please see the
+sections below to get the sysfs path of each PMU. Like other uncore PMU drivers,
+the driver provides "cpumask" sysfs attribute to show the CPU id used to handle
+the PMU event. There is also "associated_cpus" sysfs attribute, which contains a
+list of CPUs associated with the PMU instance.
+
+.. _SCF_PMU_Section:
+
+SCF PMU
+-------
+
+The SCF PMU monitors system level cache events, CPU traffic, and
+strongly-ordered (SO) PCIE write traffic to local/remote memory. Please see
+:ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about the PMU
+traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_scf_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 in socket 0::
+
+   perf stat -a -e nvidia_scf_pmu_0/event=0x0/
+
+* Count event id 0x0 in socket 1::
+
+   perf stat -a -e nvidia_scf_pmu_1/event=0x0/
+
+NVLink-C2C0 PMU
+--------------------
+
+The NVLink-C2C0 PMU monitors incoming traffic from a GPU/CPU connected with
+NVLink-C2C (Chip-2-Chip) interconnect. The type of traffic captured by this PMU
+varies dependent on the chip configuration:
+
+* NVIDIA Grace Hopper Superchip: Hopper GPU is connected with Grace SoC.
+
+  In this config, the PMU captures GPU ATS translated or EGM traffic from the GPU.
+
+* NVIDIA Grace CPU Superchip: two Grace CPU SoCs are connected.
+
+  In this config, the PMU captures read and relaxed ordered (RO) writes from
+  PCIE device of the remote SoC.
+
+Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about
+the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_nvlink_c2c0_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 from the GPU/CPU connected with socket 0::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_0/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 1::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_1/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 2::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_2/event=0x0/
+
+* Count event id 0x0 from the GPU/CPU connected with socket 3::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_3/event=0x0/
+
+The NVLink-C2C has two ports that can be connected to one GPU (occupying both
+ports) or to two GPUs (one GPU per port). The user can use "port" bitmap
+parameter to select the port(s) to monitor. Each bit represents the port number,
+e.g. "port=0x1" corresponds to port 0 and "port=0x3" is for port 0 and 1. The
+PMU will monitor both ports by default if not specified.
+
+Example for port filtering:
+
+* Count event id 0x0 from the GPU connected with socket 0 on port 0::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_0/event=0x0,port=0x1/
+
+* Count event id 0x0 from the GPUs connected with socket 0 on port 0 and port 1::
+
+   perf stat -a -e nvidia_nvlink_c2c0_pmu_0/event=0x0,port=0x3/
+
+NVLink-C2C1 PMU
+-------------------
+
+The NVLink-C2C1 PMU monitors incoming traffic from a GPU connected with
+NVLink-C2C (Chip-2-Chip) interconnect. This PMU captures untranslated GPU
+traffic, in contrast with NvLink-C2C0 PMU that captures ATS translated traffic.
+Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section` for more info about
+the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_nvlink_c2c1_pmu_<socket-id>.
+
+Example usage:
+
+* Count event id 0x0 from the GPU connected with socket 0::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_0/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 1::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_1/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 2::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_2/event=0x0/
+
+* Count event id 0x0 from the GPU connected with socket 3::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_3/event=0x0/
+
+The NVLink-C2C has two ports that can be connected to one GPU (occupying both
+ports) or to two GPUs (one GPU per port). The user can use "port" bitmap
+parameter to select the port(s) to monitor. Each bit represents the port number,
+e.g. "port=0x1" corresponds to port 0 and "port=0x3" is for port 0 and 1. The
+PMU will monitor both ports by default if not specified.
+
+Example for port filtering:
+
+* Count event id 0x0 from the GPU connected with socket 0 on port 0::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_0/event=0x0,port=0x1/
+
+* Count event id 0x0 from the GPUs connected with socket 0 on port 0 and port 1::
+
+   perf stat -a -e nvidia_nvlink_c2c1_pmu_0/event=0x0,port=0x3/
+
+CNVLink PMU
+---------------
+
+The CNVLink PMU monitors traffic from GPU and PCIE device on remote sockets
+to local memory. For PCIE traffic, this PMU captures read and relaxed ordered
+(RO) write traffic. Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section`
+for more info about the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_cnvlink_pmu_<socket-id>.
+
+Each SoC socket can be connected to one or more sockets via CNVLink. The user can
+use "rem_socket" bitmap parameter to select the remote socket(s) to monitor.
+Each bit represents the socket number, e.g. "rem_socket=0xE" corresponds to
+socket 1 to 3. The PMU will monitor all remote sockets by default if not
+specified.
+/sys/bus/event_source/devices/nvidia_cnvlink_pmu_<socket-id>/format/rem_socket
+shows the valid bits that can be set in the "rem_socket" parameter.
+
+The PMU can not distinguish the remote traffic initiator, therefore it does not
+provide filter to select the traffic source to monitor. It reports combined
+traffic from remote GPU and PCIE devices.
+
+Example usage:
+
+* Count event id 0x0 for the traffic from remote socket 1, 2, and 3 to socket 0::
+
+   perf stat -a -e nvidia_cnvlink_pmu_0/event=0x0,rem_socket=0xE/
+
+* Count event id 0x0 for the traffic from remote socket 0, 2, and 3 to socket 1::
+
+   perf stat -a -e nvidia_cnvlink_pmu_1/event=0x0,rem_socket=0xD/
+
+* Count event id 0x0 for the traffic from remote socket 0, 1, and 3 to socket 2::
+
+   perf stat -a -e nvidia_cnvlink_pmu_2/event=0x0,rem_socket=0xB/
+
+* Count event id 0x0 for the traffic from remote socket 0, 1, and 2 to socket 3::
+
+   perf stat -a -e nvidia_cnvlink_pmu_3/event=0x0,rem_socket=0x7/
+
+
+PCIE PMU
+------------
+
+The PCIE PMU monitors all read/write traffic from PCIE root ports to
+local/remote memory. Please see :ref:`NVIDIA_Uncore_PMU_Traffic_Coverage_Section`
+for more info about the PMU traffic coverage.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_pcie_pmu_<socket-id>.
+
+Each SoC socket can support multiple root ports. The user can use
+"root_port" bitmap parameter to select the port(s) to monitor, i.e.
+"root_port=0xF" corresponds to root port 0 to 3. The PMU will monitor all root
+ports by default if not specified.
+/sys/bus/event_source/devices/nvidia_pcie_pmu_<socket-id>/format/root_port
+shows the valid bits that can be set in the "root_port" parameter.
+
+Example usage:
+
+* Count event id 0x0 from root port 0 and 1 of socket 0::
+
+   perf stat -a -e nvidia_pcie_pmu_0/event=0x0,root_port=0x3/
+
+* Count event id 0x0 from root port 0 and 1 of socket 1::
+
+   perf stat -a -e nvidia_pcie_pmu_1/event=0x0,root_port=0x3/
+
+.. _NVIDIA_Uncore_PMU_Traffic_Coverage_Section:
+
+Traffic Coverage
+----------------
+
+The PMU traffic coverage may vary dependent on the chip configuration:
+
+* **NVIDIA Grace Hopper Superchip**: Hopper GPU is connected with Grace SoC.
+
+  Example configuration with two Grace SoCs::
+
+   *********************************          *********************************
+   * SOCKET-A                      *          * SOCKET-B                      *
+   *                               *          *                               *
+   *                     ::::::::  *          *  ::::::::                     *
+   *                     : PCIE :  *          *  : PCIE :                     *
+   *                     ::::::::  *          *  ::::::::                     *
+   *                         |     *          *      |                        *
+   *                         |     *          *      |                        *
+   *  :::::::            ::::::::: *          *  :::::::::            ::::::: *
+   *  :     :            :       : *          *  :       :            :     : *
+   *  : GPU :<--NVLink-->: Grace :<---CNVLink--->: Grace :<--NVLink-->: GPU : *
+   *  :     :    C2C     :  SoC  : *          *  :  SoC  :    C2C     :     : *
+   *  :::::::            ::::::::: *          *  :::::::::            ::::::: *
+   *     |                   |     *          *      |                   |    *
+   *     |                   |     *          *      |                   |    *
+   *  &&&&&&&&           &&&&&&&&  *          *   &&&&&&&&           &&&&&&&& *
+   *  & GMEM &           & CMEM &  *          *   & CMEM &           & GMEM & *
+   *  &&&&&&&&           &&&&&&&&  *          *   &&&&&&&&           &&&&&&&& *
+   *                               *          *                               *
+   *********************************          *********************************
+
+   GMEM = GPU Memory (e.g. HBM)
+   CMEM = CPU Memory (e.g. LPDDR5X)
+
+  |
+  | Following table contains traffic coverage of Grace SoC PMU in socket-A:
+
+  ::
+
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   |              |                        Source                             |
+   +              +-------+-----------+-----------+-----+----------+----------+
+   | Destination  |       |GPU ATS    |GPU Not-ATS|     | Socket-B | Socket-B |
+   |              |PCI R/W|Translated,|Translated | CPU | CPU/PCIE1| GPU/PCIE2|
+   |              |       |EGM        |           |     |          |          |
+   +==============+=======+===========+===========+=====+==========+==========+
+   | Local        | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF | SCF PMU  | CNVLink  |
+   | SYSRAM/CMEM  | PMU   |PMU        |PMU        | PMU |          | PMU      |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Local GMEM   | PCIE  |    N/A    |NVLink-C2C1| SCF | SCF PMU  | CNVLink  |
+   |              | PMU   |           |PMU        | PMU |          | PMU      |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Remote       | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF |          |          |
+   | SYSRAM/CMEM  | PMU   |PMU        |PMU        | PMU |   N/A    |   N/A    |
+   | over CNVLink |       |           |           |     |          |          |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+   | Remote GMEM  | PCIE  |NVLink-C2C0|NVLink-C2C1| SCF |          |          |
+   | over CNVLink | PMU   |PMU        |PMU        | PMU |   N/A    |   N/A    |
+   +--------------+-------+-----------+-----------+-----+----------+----------+
+
+   PCIE1 traffic represents strongly ordered (SO) writes.
+   PCIE2 traffic represents reads and relaxed ordered (RO) writes.
+
+* **NVIDIA Grace CPU Superchip**: two Grace CPU SoCs are connected.
+
+  Example configuration with two Grace SoCs::
+
+   *******************             *******************
+   * SOCKET-A        *             * SOCKET-B        *
+   *                 *             *                 *
+   *    ::::::::     *             *    ::::::::     *
+   *    : PCIE :     *             *    : PCIE :     *
+   *    ::::::::     *             *    ::::::::     *
+   *        |        *             *        |        *
+   *        |        *             *        |        *
+   *    :::::::::    *             *    :::::::::    *
+   *    :       :    *             *    :       :    *
+   *    : Grace :<--------NVLink------->: Grace :    *
+   *    :  SoC  :    *     C2C     *    :  SoC  :    *
+   *    :::::::::    *             *    :::::::::    *
+   *        |        *             *        |        *
+   *        |        *             *        |        *
+   *     &&&&&&&&    *             *     &&&&&&&&    *
+   *     & CMEM &    *             *     & CMEM &    *
+   *     &&&&&&&&    *             *     &&&&&&&&    *
+   *                 *             *                 *
+   *******************             *******************
+
+   GMEM = GPU Memory (e.g. HBM)
+   CMEM = CPU Memory (e.g. LPDDR5X)
+
+  |
+  | Following table contains traffic coverage of Grace SoC PMU in socket-A:
+
+  ::
+
+   +-----------------+-----------+---------+----------+-------------+
+   |                 |                      Source                  |
+   +                 +-----------+---------+----------+-------------+
+   | Destination     |           |         | Socket-B | Socket-B    |
+   |                 |  PCI R/W  |   CPU   | CPU/PCIE1| PCIE2       |
+   |                 |           |         |          |             |
+   +=================+===========+=========+==========+=============+
+   | Local           |  PCIE PMU | SCF PMU | SCF PMU  | NVLink-C2C0 |
+   | SYSRAM/CMEM     |           |         |          | PMU         |
+   +-----------------+-----------+---------+----------+-------------+
+   | Remote          |           |         |          |             |
+   | SYSRAM/CMEM     |  PCIE PMU | SCF PMU |   N/A    |     N/A     |
+   | over NVLink-C2C |           |         |          |             |
+   +-----------------+-----------+---------+----------+-------------+
+
+   PCIE1 traffic represents strongly ordered (SO) writes.
+   PCIE2 traffic represents reads and relaxed ordered (RO) writes.
diff --git a/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst b/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst
new file mode 100644
index 000000000..0656223b6
--- /dev/null
+++ b/Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst
@@ -0,0 +1,522 @@
+=====================================================================
+NVIDIA Tegra410 SoC Uncore Performance Monitoring Unit (PMU)
+=====================================================================
+
+The NVIDIA Tegra410 SoC includes various system PMUs to measure key performance
+metrics like memory bandwidth, latency, and utilization:
+
+* Unified Coherence Fabric (UCF)
+* PCIE
+* PCIE-TGT
+* CPU Memory (CMEM) Latency
+* NVLink-C2C
+* NV-CLink
+* NV-DLink
+
+PMU Driver
+----------
+
+The PMU driver describes the available events and configuration of each PMU in
+sysfs. Please see the sections below to get the sysfs path of each PMU. Like
+other uncore PMU drivers, the driver provides "cpumask" sysfs attribute to show
+the CPU id used to handle the PMU event. There is also "associated_cpus"
+sysfs attribute, which contains a list of CPUs associated with the PMU instance.
+
+UCF PMU
+-------
+
+The Unified Coherence Fabric (UCF) in the NVIDIA Tegra410 SoC serves as a
+distributed cache, last level for CPU Memory and CXL Memory, and cache coherent
+interconnect that supports hardware coherence across multiple coherently caching
+agents, including:
+
+  * CPU clusters
+  * GPU
+  * PCIe Ordering Controller Unit (OCU)
+  * Other IO-coherent requesters
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_ucf_pmu_<socket-id>.
+
+Some of the events available in this PMU can be used to measure bandwidth and
+utilization:
+
+  * slc_access_rd: count the number of read requests to SLC.
+  * slc_access_wr: count the number of write requests to SLC.
+  * slc_bytes_rd: count the number of bytes transferred by slc_access_rd.
+  * slc_bytes_wr: count the number of bytes transferred by slc_access_wr.
+  * mem_access_rd: count the number of read requests to local or remote memory.
+  * mem_access_wr: count the number of write requests to local or remote memory.
+  * mem_bytes_rd: count the number of bytes transferred by mem_access_rd.
+  * mem_bytes_wr: count the number of bytes transferred by mem_access_wr.
+  * cycles: counts the UCF cycles.
+
+The average bandwidth is calculated as::
+
+   AVG_SLC_READ_BANDWIDTH_IN_GBPS = SLC_BYTES_RD / ELAPSED_TIME_IN_NS
+   AVG_SLC_WRITE_BANDWIDTH_IN_GBPS = SLC_BYTES_WR / ELAPSED_TIME_IN_NS
+   AVG_MEM_READ_BANDWIDTH_IN_GBPS = MEM_BYTES_RD / ELAPSED_TIME_IN_NS
+   AVG_MEM_WRITE_BANDWIDTH_IN_GBPS = MEM_BYTES_WR / ELAPSED_TIME_IN_NS
+
+The average request rate is calculated as::
+
+   AVG_SLC_READ_REQUEST_RATE = SLC_ACCESS_RD / CYCLES
+   AVG_SLC_WRITE_REQUEST_RATE = SLC_ACCESS_WR / CYCLES
+   AVG_MEM_READ_REQUEST_RATE = MEM_ACCESS_RD / CYCLES
+   AVG_MEM_WRITE_REQUEST_RATE = MEM_ACCESS_WR / CYCLES
+
+More details about what other events are available can be found in Tegra410 SoC
+technical reference manual.
+
+The events can be filtered based on source or destination. The source filter
+indicates the traffic initiator to the SLC, e.g local CPU, non-CPU device, or
+remote socket. The destination filter specifies the destination memory type,
+e.g. local system memory (CMEM), local GPU memory (GMEM), or remote memory. The
+local/remote classification of the destination filter is based on the home
+socket of the address, not where the data actually resides. The available
+filters are described in
+/sys/bus/event_source/devices/nvidia_ucf_pmu_<socket-id>/format/.
+
+The list of UCF PMU event filters:
+
+* Source filter:
+
+  * src_loc_cpu: if set, count events from local CPU
+  * src_loc_noncpu: if set, count events from local non-CPU device
+  * src_rem: if set, count events from CPU, GPU, PCIE devices of remote socket
+
+* Destination filter:
+
+  * dst_loc_cmem: if set, count events to local system memory (CMEM) address
+  * dst_loc_gmem: if set, count events to local GPU memory (GMEM) address
+  * dst_loc_other: if set, count events to local CXL memory address
+  * dst_rem: if set, count events to CPU, GPU, and CXL memory address of remote socket
+
+If the source is not specified, the PMU will count events from all sources. If
+the destination is not specified, the PMU will count events to all destinations.
+
+Example usage:
+
+* Count event id 0x0 in socket 0 from all sources and to all destinations::
+
+    perf stat -a -e nvidia_ucf_pmu_0/event=0x0/
+
+* Count event id 0x0 in socket 0 with source filter = local CPU and destination
+  filter = local system memory (CMEM)::
+
+    perf stat -a -e nvidia_ucf_pmu_0/event=0x0,src_loc_cpu=0x1,dst_loc_cmem=0x1/
+
+* Count event id 0x0 in socket 1 with source filter = local non-CPU device and
+  destination filter = remote memory::
+
+    perf stat -a -e nvidia_ucf_pmu_1/event=0x0,src_loc_noncpu=0x1,dst_rem=0x1/
+
+PCIE PMU
+--------
+
+This PMU is located in the SOC fabric connecting the PCIE root complex (RC) and
+the memory subsystem. It monitors all read/write traffic from the root port(s)
+or a particular BDF in a PCIE RC to local or remote memory. There is one PMU per
+PCIE RC in the SoC. Each RC can have up to 16 lanes that can be bifurcated into
+up to 8 root ports. The traffic from each root port can be filtered using RP or
+BDF filter. For example, specifying "src_rp_mask=0xFF" means the PMU counter will
+capture traffic from all RPs. Please see below for more details.
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_pcie_pmu_<socket-id>_rc_<pcie-rc-id>.
+
+The events in this PMU can be used to measure bandwidth, utilization, and
+latency:
+
+  * rd_req: count the number of read requests by PCIE device.
+  * wr_req: count the number of write requests by PCIE device.
+  * rd_bytes: count the number of bytes transferred by rd_req.
+  * wr_bytes: count the number of bytes transferred by wr_req.
+  * rd_cum_outs: count outstanding rd_req each cycle.
+  * cycles: count the clock cycles of SOC fabric connected to the PCIE interface.
+
+The average bandwidth is calculated as::
+
+   AVG_RD_BANDWIDTH_IN_GBPS = RD_BYTES / ELAPSED_TIME_IN_NS
+   AVG_WR_BANDWIDTH_IN_GBPS = WR_BYTES / ELAPSED_TIME_IN_NS
+
+The average request rate is calculated as::
+
+   AVG_RD_REQUEST_RATE = RD_REQ / CYCLES
+   AVG_WR_REQUEST_RATE = WR_REQ / CYCLES
+
+
+The average latency is calculated as::
+
+   FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS
+   AVG_LATENCY_IN_CYCLES = RD_CUM_OUTS / RD_REQ
+   AVERAGE_LATENCY_IN_NS = AVG_LATENCY_IN_CYCLES / FREQ_IN_GHZ
+
+The PMU events can be filtered based on the traffic source and destination.
+The source filter indicates the PCIE devices that will be monitored. The
+destination filter specifies the destination memory type, e.g. local system
+memory (CMEM), local GPU memory (GMEM), or remote memory. The local/remote
+classification of the destination filter is based on the home socket of the
+address, not where the data actually resides. These filters can be found in
+/sys/bus/event_source/devices/nvidia_pcie_pmu_<socket-id>_rc_<pcie-rc-id>/format/.
+
+The list of event filters:
+
+* Source filter:
+
+  * src_rp_mask: bitmask of root ports that will be monitored. Each bit in this
+    bitmask represents the RP index in the RC. If the bit is set, all devices under
+    the associated RP will be monitored. E.g "src_rp_mask=0xF" will monitor
+    devices in root port 0 to 3.
+  * src_bdf: the BDF that will be monitored. This is a 16-bit value that
+    follows formula: (bus << 8) + (device << 3) + (function). For example, the
+    value of BDF 27:01.1 is 0x2781.
+  * src_bdf_en: enable the BDF filter. If this is set, the BDF filter value in
+    "src_bdf" is used to filter the traffic.
+
+  Note that Root-Port and BDF filters are mutually exclusive and the PMU in
+  each RC can only have one BDF filter for the whole counters. If BDF filter
+  is enabled, the BDF filter value will be applied to all events.
+
+* Destination filter:
+
+  * dst_loc_cmem: if set, count events to local system memory (CMEM) address
+  * dst_loc_gmem: if set, count events to local GPU memory (GMEM) address
+  * dst_loc_pcie_p2p: if set, count events to local PCIE peer address
+  * dst_loc_pcie_cxl: if set, count events to local CXL memory address
+  * dst_rem: if set, count events to remote memory address
+
+If the source filter is not specified, the PMU will count events from all root
+ports. If the destination filter is not specified, the PMU will count events
+to all destinations.
+
+Example usage:
+
+* Count event id 0x0 from root port 0 of PCIE RC-0 on socket 0 targeting all
+  destinations::
+
+    perf stat -a -e nvidia_pcie_pmu_0_rc_0/event=0x0,src_rp_mask=0x1/
+
+* Count event id 0x1 from root port 0 and 1 of PCIE RC-1 on socket 0 and
+  targeting just local CMEM of socket 0::
+
+    perf stat -a -e nvidia_pcie_pmu_0_rc_1/event=0x1,src_rp_mask=0x3,dst_loc_cmem=0x1/
+
+* Count event id 0x2 from root port 0 of PCIE RC-2 on socket 1 targeting all
+  destinations::
+
+    perf stat -a -e nvidia_pcie_pmu_1_rc_2/event=0x2,src_rp_mask=0x1/
+
+* Count event id 0x3 from root port 0 and 1 of PCIE RC-3 on socket 1 and
+  targeting just local CMEM of socket 1::
+
+    perf stat -a -e nvidia_pcie_pmu_1_rc_3/event=0x3,src_rp_mask=0x3,dst_loc_cmem=0x1/
+
+* Count event id 0x4 from BDF 01:01.0 of PCIE RC-4 on socket 0 targeting all
+  destinations::
+
+    perf stat -a -e nvidia_pcie_pmu_0_rc_4/event=0x4,src_bdf=0x0180,src_bdf_en=0x1/
+
+.. _NVIDIA_T410_PCIE_PMU_RC_Mapping_Section:
+
+Mapping the RC# to lspci segment number
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Mapping the RC# to lspci segment number can be non-trivial; hence a new NVIDIA
+Designated Vendor Specific Capability (DVSEC) register is added into the PCIE config space
+for each RP. This DVSEC has vendor id "10de" and DVSEC id of "0x4". The DVSEC register
+contains the following information to map PCIE devices under the RP back to its RC# :
+
+  - Bus# (byte 0xc) : bus number as reported by the lspci output
+  - Segment# (byte 0xd) : segment number as reported by the lspci output
+  - RP# (byte 0xe) : port number as reported by LnkCap attribute from lspci for a device with Root Port capability
+  - RC# (byte 0xf): root complex number associated with the RP
+  - Socket# (byte 0x10): socket number associated with the RP
+
+Example script for mapping lspci BDF to RC# and socket#::
+
+  #!/bin/bash
+  while read bdf rest; do
+    dvsec4_reg=$(lspci -vv -s $bdf | awk '
+      /Designated Vendor-Specific: Vendor=10de ID=0004/ {
+        match($0, /\[([0-9a-fA-F]+)/, arr);
+        print "0x" arr[1];
+        exit
+      }
+    ')
+    if [ -n "$dvsec4_reg" ]; then
+      bus=$(setpci -s $bdf $(printf '0x%x' $((${dvsec4_reg} + 0xc))).b)
+      segment=$(setpci -s $bdf $(printf '0x%x' $((${dvsec4_reg} + 0xd))).b)
+      rp=$(setpci -s $bdf $(printf '0x%x' $((${dvsec4_reg} + 0xe))).b)
+      rc=$(setpci -s $bdf $(printf '0x%x' $((${dvsec4_reg} + 0xf))).b)
+      socket=$(setpci -s $bdf $(printf '0x%x' $((${dvsec4_reg} + 0x10))).b)
+      echo "$bdf: Bus=$bus, Segment=$segment, RP=$rp, RC=$rc, Socket=$socket"
+    fi
+  done < <(lspci -d 10de:)
+
+Example output::
+
+  0001:00:00.0: Bus=00, Segment=01, RP=00, RC=00, Socket=00
+  0002:80:00.0: Bus=80, Segment=02, RP=01, RC=01, Socket=00
+  0002:a0:00.0: Bus=a0, Segment=02, RP=02, RC=01, Socket=00
+  0002:c0:00.0: Bus=c0, Segment=02, RP=03, RC=01, Socket=00
+  0002:e0:00.0: Bus=e0, Segment=02, RP=04, RC=01, Socket=00
+  0003:00:00.0: Bus=00, Segment=03, RP=00, RC=02, Socket=00
+  0004:00:00.0: Bus=00, Segment=04, RP=00, RC=03, Socket=00
+  0005:00:00.0: Bus=00, Segment=05, RP=00, RC=04, Socket=00
+  0005:40:00.0: Bus=40, Segment=05, RP=01, RC=04, Socket=00
+  0005:c0:00.0: Bus=c0, Segment=05, RP=02, RC=04, Socket=00
+  0006:00:00.0: Bus=00, Segment=06, RP=00, RC=05, Socket=00
+  0009:00:00.0: Bus=00, Segment=09, RP=00, RC=00, Socket=01
+  000a:80:00.0: Bus=80, Segment=0a, RP=01, RC=01, Socket=01
+  000a:a0:00.0: Bus=a0, Segment=0a, RP=02, RC=01, Socket=01
+  000a:e0:00.0: Bus=e0, Segment=0a, RP=03, RC=01, Socket=01
+  000b:00:00.0: Bus=00, Segment=0b, RP=00, RC=02, Socket=01
+  000c:00:00.0: Bus=00, Segment=0c, RP=00, RC=03, Socket=01
+  000d:00:00.0: Bus=00, Segment=0d, RP=00, RC=04, Socket=01
+  000d:40:00.0: Bus=40, Segment=0d, RP=01, RC=04, Socket=01
+  000d:c0:00.0: Bus=c0, Segment=0d, RP=02, RC=04, Socket=01
+  000e:00:00.0: Bus=00, Segment=0e, RP=00, RC=05, Socket=01
+
+PCIE-TGT PMU
+------------
+
+This PMU is located in the SOC fabric connecting the PCIE root complex (RC) and
+the memory subsystem. It monitors traffic targeting PCIE BAR and CXL HDM ranges.
+There is one PCIE-TGT PMU per PCIE RC in the SoC. Each RC in Tegra410 SoC can
+have up to 16 lanes that can be bifurcated into up to 8 root ports (RP). The PMU
+provides RP filter to count PCIE BAR traffic to each RP and address filter to
+count access to PCIE BAR or CXL HDM ranges. The details of the filters are
+described in the following sections.
+
+Mapping the RC# to lspci segment number is similar to the PCIE PMU. Please see
+:ref:`NVIDIA_T410_PCIE_PMU_RC_Mapping_Section` for more info.
+
+The events and configuration options of this PMU device are available in sysfs,
+see /sys/bus/event_source/devices/nvidia_pcie_tgt_pmu_<socket-id>_rc_<pcie-rc-id>.
+
+The events in this PMU can be used to measure bandwidth and utilization:
+
+  * rd_req: count the number of read requests to PCIE.
+  * wr_req: count the number of write requests to PCIE.
+  * rd_bytes: count the number of bytes transferred by rd_req.
+  * wr_bytes: count the number of bytes transferred by wr_req.
+  * cycles: count the clock cycles of SOC fabric connected to the PCIE interface.
+
+The average bandwidth is calculated as::
+
+   AVG_RD_BANDWIDTH_IN_GBPS = RD_BYTES / ELAPSED_TIME_IN_NS
+   AVG_WR_BANDWIDTH_IN_GBPS = WR_BYTES / ELAPSED_TIME_IN_NS
+
+The average request rate is calculated as::
+
+   AVG_RD_REQUEST_RATE = RD_REQ / CYCLES
+   AVG_WR_REQUEST_RATE = WR_REQ / CYCLES
+
+The PMU events can be filtered based on the destination root port or target
+address range. Filtering based on RP is only available for PCIE BAR traffic.
+Address filter works for both PCIE BAR and CXL HDM ranges. These filters can be
+found in sysfs, see
+/sys/bus/event_source/devices/nvidia_pcie_tgt_pmu_<socket-id>_rc_<pcie-rc-id>/format/.
+
+Destination filter settings:
+
+* dst_rp_mask: bitmask to select the root port(s) to monitor. E.g. "dst_rp_mask=0xFF"
+  corresponds to all root ports (from 0 to 7) in the PCIE RC. Note that this filter is
+  only available for PCIE BAR traffic.
+* dst_addr_base: BAR or CXL HDM filter base address.
+* dst_addr_mask: BAR or CXL HDM filter address mask.
+* dst_addr_en: enable BAR or CXL HDM address range filter. If this is set, the
+  address range specified by "dst_addr_base" and "dst_addr_mask" will be used to filter
+  the PCIE BAR and CXL HDM traffic address. The PMU uses the following comparison
+  to determine if the traffic destination address falls within the filter range::
+
+    (txn's addr & dst_addr_mask) == (dst_addr_base & dst_addr_mask)
+
+  If the comparison succeeds, then the event will be counted.
+
+If the destination filter is not specified, the RP filter will be configured by default
+to count PCIE BAR traffic to all root ports.
+
+Example usage:
+
+* Count event id 0x0 to root port 0 and 1 of PCIE RC-0 on socket 0::
+
+    perf stat -a -e nvidia_pcie_tgt_pmu_0_rc_0/event=0x0,dst_rp_mask=0x3/
+
+* Count event id 0x1 for accesses to PCIE BAR or CXL HDM address range
+  0x10000 to 0x100FF on socket 0's PCIE RC-1::
+
+    perf stat -a -e nvidia_pcie_tgt_pmu_0_rc_1/event=0x1,dst_addr_base=0x10000,dst_addr_mask=0xFFF00,dst_addr_en=0x1/
+
+CPU Memory (CMEM) Latency PMU
+-----------------------------
+
+This PMU monitors latency events of memory read requests from the edge of the
+Unified Coherence Fabric (UCF) to local CPU DRAM:
+
+  * RD_REQ counters: count read requests (32B per request).
+  * RD_CUM_OUTS counters: accumulated outstanding request counter, which track
+    how many cycles the read requests are in flight.
+  * CYCLES counter: counts the number of elapsed cycles.
+
+The average latency is calculated as::
+
+   FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS
+   AVG_LATENCY_IN_CYCLES = RD_CUM_OUTS / RD_REQ
+   AVERAGE_LATENCY_IN_NS = AVG_LATENCY_IN_CYCLES / FREQ_IN_GHZ
+
+The events and configuration options of this PMU device are described in sysfs,
+see /sys/bus/event_source/devices/nvidia_cmem_latency_pmu_<socket-id>.
+
+Example usage::
+
+  perf stat -a -e '{nvidia_cmem_latency_pmu_0/rd_req/,nvidia_cmem_latency_pmu_0/rd_cum_outs/,nvidia_cmem_latency_pmu_0/cycles/}'
+
+NVLink-C2C PMU
+--------------
+
+This PMU monitors latency events of memory read/write requests that pass through
+the NVIDIA Chip-to-Chip (C2C) interface. Bandwidth events are not available
+in this PMU, unlike the C2C PMU in Grace (Tegra241 SoC).
+
+The events and configuration options of this PMU device are available in sysfs,
+see /sys/bus/event_source/devices/nvidia_nvlink_c2c_pmu_<socket-id>.
+
+The list of events:
+
+  * IN_RD_CUM_OUTS: accumulated outstanding request (in cycles) of incoming read requests.
+  * IN_RD_REQ: the number of incoming read requests.
+  * IN_WR_CUM_OUTS: accumulated outstanding request (in cycles) of incoming write requests.
+  * IN_WR_REQ: the number of incoming write requests.
+  * OUT_RD_CUM_OUTS: accumulated outstanding request (in cycles) of outgoing read requests.
+  * OUT_RD_REQ: the number of outgoing read requests.
+  * OUT_WR_CUM_OUTS: accumulated outstanding request (in cycles) of outgoing write requests.
+  * OUT_WR_REQ: the number of outgoing write requests.
+  * CYCLES: NVLink-C2C interface cycle counts.
+
+The incoming events count the reads/writes from remote device to the SoC.
+The outgoing events count the reads/writes from the SoC to remote device.
+
+The sysfs /sys/bus/event_source/devices/nvidia_nvlink_c2c_pmu_<socket-id>/peer
+contains the information about the connected device.
+
+When the C2C interface is connected to GPU(s), the user can use the
+"gpu_mask" parameter to filter traffic to/from specific GPU(s). Each bit represents the GPU
+index, e.g. "gpu_mask=0x1" corresponds to GPU 0 and "gpu_mask=0x3" is for GPU 0 and 1.
+The PMU will monitor all GPUs by default if not specified.
+
+When connected to another SoC, only the read events are available.
+
+The events can be used to calculate the average latency of the read/write requests::
+
+   C2C_FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS
+
+   IN_RD_AVG_LATENCY_IN_CYCLES = IN_RD_CUM_OUTS / IN_RD_REQ
+   IN_RD_AVG_LATENCY_IN_NS = IN_RD_AVG_LATENCY_IN_CYCLES / C2C_FREQ_IN_GHZ
+
+   IN_WR_AVG_LATENCY_IN_CYCLES = IN_WR_CUM_OUTS / IN_WR_REQ
+   IN_WR_AVG_LATENCY_IN_NS = IN_WR_AVG_LATENCY_IN_CYCLES / C2C_FREQ_IN_GHZ
+
+   OUT_RD_AVG_LATENCY_IN_CYCLES = OUT_RD_CUM_OUTS / OUT_RD_REQ
+   OUT_RD_AVG_LATENCY_IN_NS = OUT_RD_AVG_LATENCY_IN_CYCLES / C2C_FREQ_IN_GHZ
+
+   OUT_WR_AVG_LATENCY_IN_CYCLES = OUT_WR_CUM_OUTS / OUT_WR_REQ
+   OUT_WR_AVG_LATENCY_IN_NS = OUT_WR_AVG_LATENCY_IN_CYCLES / C2C_FREQ_IN_GHZ
+
+Example usage:
+
+  * Count incoming traffic from all GPUs connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/in_rd_req/
+
+  * Count incoming traffic from GPU 0 connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/in_rd_cum_outs,gpu_mask=0x1/
+
+  * Count incoming traffic from GPU 1 connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/in_rd_cum_outs,gpu_mask=0x2/
+
+  * Count outgoing traffic to all GPUs connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/out_rd_req/
+
+  * Count outgoing traffic to GPU 0 connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/out_rd_cum_outs,gpu_mask=0x1/
+
+  * Count outgoing traffic to GPU 1 connected via NVLink-C2C::
+
+      perf stat -a -e nvidia_nvlink_c2c_pmu_0/out_rd_cum_outs,gpu_mask=0x2/
+
+NV-CLink PMU
+------------
+
+This PMU monitors latency events of memory read requests that pass through
+the NV-CLINK interface. Bandwidth events are not available in this PMU.
+In Tegra410 SoC, the NV-CLink interface is used to connect to another Tegra410
+SoC and this PMU only counts read traffic.
+
+The events and configuration options of this PMU device are available in sysfs,
+see /sys/bus/event_source/devices/nvidia_nvclink_pmu_<socket-id>.
+
+The list of events:
+
+  * IN_RD_CUM_OUTS: accumulated outstanding request (in cycles) of incoming read requests.
+  * IN_RD_REQ: the number of incoming read requests.
+  * OUT_RD_CUM_OUTS: accumulated outstanding request (in cycles) of outgoing read requests.
+  * OUT_RD_REQ: the number of outgoing read requests.
+  * CYCLES: NV-CLINK interface cycle counts.
+
+The incoming events count the reads from remote device to the SoC.
+The outgoing events count the reads from the SoC to remote device.
+
+The events can be used to calculate the average latency of the read requests::
+
+   CLINK_FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS
+
+   IN_RD_AVG_LATENCY_IN_CYCLES = IN_RD_CUM_OUTS / IN_RD_REQ
+   IN_RD_AVG_LATENCY_IN_NS = IN_RD_AVG_LATENCY_IN_CYCLES / CLINK_FREQ_IN_GHZ
+
+   OUT_RD_AVG_LATENCY_IN_CYCLES = OUT_RD_CUM_OUTS / OUT_RD_REQ
+   OUT_RD_AVG_LATENCY_IN_NS = OUT_RD_AVG_LATENCY_IN_CYCLES / CLINK_FREQ_IN_GHZ
+
+Example usage:
+
+  * Count incoming read traffic from remote SoC connected via NV-CLINK::
+
+      perf stat -a -e nvidia_nvclink_pmu_0/in_rd_req/
+
+  * Count outgoing read traffic to remote SoC connected via NV-CLINK::
+
+      perf stat -a -e nvidia_nvclink_pmu_0/out_rd_req/
+
+NV-DLink PMU
+------------
+
+This PMU monitors latency events of memory read requests that pass through
+the NV-DLINK interface.  Bandwidth events are not available in this PMU.
+In Tegra410 SoC, this PMU only counts CXL memory read traffic.
+
+The events and configuration options of this PMU device are available in sysfs,
+see /sys/bus/event_source/devices/nvidia_nvdlink_pmu_<socket-id>.
+
+The list of events:
+
+  * IN_RD_CUM_OUTS: accumulated outstanding read requests (in cycles) to CXL memory.
+  * IN_RD_REQ: the number of read requests to CXL memory.
+  * CYCLES: NV-DLINK interface cycle counts.
+
+The events can be used to calculate the average latency of the read requests::
+
+   DLINK_FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS
+
+   IN_RD_AVG_LATENCY_IN_CYCLES = IN_RD_CUM_OUTS / IN_RD_REQ
+   IN_RD_AVG_LATENCY_IN_NS = IN_RD_AVG_LATENCY_IN_CYCLES / DLINK_FREQ_IN_GHZ
+
+Example usage:
+
+  * Count read events to CXL memory::
+
+      perf stat -a -e '{nvidia_nvdlink_pmu_0/in_rd_req/,nvidia_nvdlink_pmu_0/in_rd_cum_outs/}'
diff --git a/Documentation/admin-guide/perf/qcom_l2_pmu.rst b/Documentation/admin-guide/perf/qcom_l2_pmu.rst
new file mode 100644
index 000000000..c37c6be9b
--- /dev/null
+++ b/Documentation/admin-guide/perf/qcom_l2_pmu.rst
@@ -0,0 +1,39 @@
+=====================================================================
+Qualcomm Technologies Level-2 Cache Performance Monitoring Unit (PMU)
+=====================================================================
+
+This driver supports the L2 cache clusters found in Qualcomm Technologies
+Centriq SoCs. There are multiple physical L2 cache clusters, each with their
+own PMU. Each cluster has one or more CPUs associated with it.
+
+There is one logical L2 PMU exposed, which aggregates the results from
+the physical PMUs.
+
+The driver provides a description of its available events and configuration
+options in sysfs, see /sys/bus/event_source/devices/l2cache_0.
+
+The "format" directory describes the format of the events.
+
+Events can be envisioned as a 2-dimensional array. Each column represents
+a group of events. There are 8 groups. Only one entry from each
+group can be in use at a time. If multiple events from the same group
+are specified, the conflicting events cannot be counted at the same time.
+
+Events are specified as 0xCCG, where CC is 2 hex digits specifying
+the code (array row) and G specifies the group (column) 0-7.
+
+In addition there is a cycle counter event specified by the value 0xFE
+which is outside the above scheme.
+
+The driver provides a "cpumask" sysfs attribute which contains a mask
+consisting of one CPU per cluster which will be used to handle all the PMU
+events on that cluster.
+
+Examples for use with perf::
+
+  perf stat -e l2cache_0/config=0x001/,l2cache_0/config=0x042/ -a sleep 1
+
+  perf stat -e l2cache_0/config=0xfe/ -C 2 sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/qcom_l3_pmu.rst b/Documentation/admin-guide/perf/qcom_l3_pmu.rst
new file mode 100644
index 000000000..a66556b7e
--- /dev/null
+++ b/Documentation/admin-guide/perf/qcom_l3_pmu.rst
@@ -0,0 +1,26 @@
+===========================================================================
+Qualcomm Datacenter Technologies L3 Cache Performance Monitoring Unit (PMU)
+===========================================================================
+
+This driver supports the L3 cache PMUs found in Qualcomm Datacenter Technologies
+Centriq SoCs. The L3 cache on these SOCs is composed of multiple slices, shared
+by all cores within a socket. Each slice is exposed as a separate uncore perf
+PMU with device name l3cache_<socket>_<instance>. User space is responsible
+for aggregating across slices.
+
+The driver provides a description of its available events and configuration
+options in sysfs, see /sys/bus/event_source/devices/l3cache*. Given that these are uncore PMUs
+the driver also exposes a "cpumask" sysfs attribute which contains a mask
+consisting of one CPU per socket which will be used to handle all the PMU
+events on that socket.
+
+The hardware implements 32bit event counters and has a flat 8bit event space
+exposed via the "event" format attribute. In addition to the 32bit physical
+counters the driver supports virtual 64bit hardware counters by using hardware
+counter chaining. This feature is exposed via the "lc" (long counter) format
+flag. E.g.::
+
+  perf stat -e l3cache_0_0/read-miss,lc/
+
+Given that these are uncore PMUs the driver does not support sampling, therefore
+"perf record" will not work. Per-task perf sessions are not supported.
diff --git a/Documentation/admin-guide/perf/starfive_starlink_pmu.rst b/Documentation/admin-guide/perf/starfive_starlink_pmu.rst
new file mode 100644
index 000000000..2932ddb4e
--- /dev/null
+++ b/Documentation/admin-guide/perf/starfive_starlink_pmu.rst
@@ -0,0 +1,46 @@
+================================================
+StarFive StarLink Performance Monitor Unit (PMU)
+================================================
+
+StarFive StarLink Performance Monitor Unit (PMU) exists within the
+StarLink Coherent Network on Chip (CNoC) that connects multiple CPU
+clusters with an L3 memory system.
+
+The uncore PMU supports overflow interrupt, up to 16 programmable 64bit
+event counters, and an independent 64bit cycle counter.
+The PMU can only be accessed via Memory Mapped I/O and are common to the
+cores connected to the same PMU.
+
+Driver exposes supported PMU events in sysfs "events" directory under::
+
+  /sys/bus/event_source/devices/starfive_starlink_pmu/events/
+
+Driver exposes cpu used to handle PMU events in sysfs "cpumask" directory
+under::
+
+  /sys/bus/event_source/devices/starfive_starlink_pmu/cpumask/
+
+Driver describes the format of config (event ID) in sysfs "format" directory
+under::
+
+  /sys/bus/event_source/devices/starfive_starlink_pmu/format/
+
+Example of perf usage::
+
+	$ perf list
+
+	starfive_starlink_pmu/cycles/                      [Kernel PMU event]
+	starfive_starlink_pmu/read_hit/                    [Kernel PMU event]
+	starfive_starlink_pmu/read_miss/                   [Kernel PMU event]
+	starfive_starlink_pmu/read_request/                [Kernel PMU event]
+	starfive_starlink_pmu/release_request/             [Kernel PMU event]
+	starfive_starlink_pmu/write_hit/                   [Kernel PMU event]
+	starfive_starlink_pmu/write_miss/                  [Kernel PMU event]
+	starfive_starlink_pmu/write_request/               [Kernel PMU event]
+	starfive_starlink_pmu/writeback/                   [Kernel PMU event]
+
+
+	$ perf stat -a -e /starfive_starlink_pmu/cycles/ sleep 1
+
+Sampling is not supported. As a result, "perf record" is not supported.
+Attaching to a task is not supported, only system-wide counting is supported.
diff --git a/Documentation/admin-guide/perf/thunderx2-pmu.rst b/Documentation/admin-guide/perf/thunderx2-pmu.rst
new file mode 100644
index 000000000..9255f7bf9
--- /dev/null
+++ b/Documentation/admin-guide/perf/thunderx2-pmu.rst
@@ -0,0 +1,44 @@
+=============================================================
+Cavium ThunderX2 SoC Performance Monitoring Unit (PMU UNCORE)
+=============================================================
+
+The ThunderX2 SoC PMU consists of independent, system-wide, per-socket
+PMUs such as the Level 3 Cache (L3C), DDR4 Memory Controller (DMC) and
+Cavium Coherent Processor Interconnect (CCPI2).
+
+The DMC has 8 interleaved channels and the L3C has 16 interleaved tiles.
+Events are counted for the default channel (i.e. channel 0) and prorated
+to the total number of channels/tiles.
+
+The DMC and L3C support up to 4 counters, while the CCPI2 supports up to 8
+counters. Counters are independently programmable to different events and
+can be started and stopped individually. None of the counters support an
+overflow interrupt. DMC and L3C counters are 32-bit and read every 2 seconds.
+The CCPI2 counters are 64-bit and assumed not to overflow in normal operation.
+
+PMU UNCORE (perf) driver:
+
+The thunderx2_pmu driver registers per-socket perf PMUs for the DMC and
+L3C devices.  Each PMU can be used to count up to 4 (DMC/L3C) or up to 8
+(CCPI2) events simultaneously. The PMUs provide a description of their
+available events and configuration options under sysfs, see
+/sys/bus/event_source/devices/uncore_<l3c_S/dmc_S/ccpi2_S/>; S is the socket id.
+
+The driver does not support sampling, therefore "perf record" will not
+work. Per-task perf sessions are also not supported.
+
+Examples::
+
+  # perf stat -a -e uncore_dmc_0/cnt_cycles/ sleep 1
+
+  # perf stat -a -e \
+  uncore_dmc_0/cnt_cycles/,\
+  uncore_dmc_0/data_transfers/,\
+  uncore_dmc_0/read_txns/,\
+  uncore_dmc_0/write_txns/ sleep 1
+
+  # perf stat -a -e \
+  uncore_l3c_0/read_request/,\
+  uncore_l3c_0/read_hit/,\
+  uncore_l3c_0/inv_request/,\
+  uncore_l3c_0/inv_hit/ sleep 1
diff --git a/Documentation/admin-guide/perf/xgene-pmu.rst b/Documentation/admin-guide/perf/xgene-pmu.rst
new file mode 100644
index 000000000..98ccb8e77
--- /dev/null
+++ b/Documentation/admin-guide/perf/xgene-pmu.rst
@@ -0,0 +1,49 @@
+================================================
+APM X-Gene SoC Performance Monitoring Unit (PMU)
+================================================
+
+X-Gene SoC PMU consists of various independent system device PMUs such as
+L3 cache(s), I/O bridge(s), memory controller bridge(s) and memory
+controller(s). These PMU devices are loosely architected to follow the
+same model as the PMU for ARM cores. The PMUs share the same top level
+interrupt and status CSR region.
+
+PMU (perf) driver
+-----------------
+
+The xgene-pmu driver registers several perf PMU drivers. Each of the perf
+driver provides description of its available events and configuration options
+in sysfs, see /sys/bus/event_source/devices/<l3cX/iobX/mcbX/mcX>/.
+
+The "format" directory describes format of the config (event ID),
+config1 (agent ID) fields of the perf_event_attr structure. The "events"
+directory provides configuration templates for all supported event types that
+can be used with perf tool. For example, "l3c0/bank-fifo-full/" is an
+equivalent of "l3c0/config=0x0b/".
+
+Most of the SoC PMU has a specific list of agent ID used for monitoring
+performance of a specific datapath. For example, agents of a L3 cache can be
+a specific CPU or an I/O bridge. Each PMU has a set of 2 registers capable of
+masking the agents from which the request come from. If the bit with
+the bit number corresponding to the agent is set, the event is counted only if
+it is caused by a request from that agent. Each agent ID bit is inversely mapped
+to a corresponding bit in "config1" field. By default, the event will be
+counted for all agent requests (config1 = 0x0). For all the supported agents of
+each PMU, please refer to APM X-Gene User Manual.
+
+Each perf driver also provides a "cpumask" sysfs attribute, which contains a
+single CPU ID of the processor which will be used to handle all the PMU events.
+
+Example for perf tool use::
+
+ / # perf list | grep -e l3c -e iob -e mcb -e mc
+   l3c0/ackq-full/                                    [Kernel PMU event]
+ <...>
+   mcb1/mcb-csw-stall/                                [Kernel PMU event]
+
+ / # perf stat -a -e l3c0/read-miss/,mcb1/csw-write-request/ sleep 1
+
+ / # perf stat -a -e l3c0/read-miss,config1=0xfffffffffffffffe/ sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Per-task (without "-a") perf sessions are not supported.
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
new file mode 100644
index 000000000..6fd72ba52
--- /dev/null
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -0,0 +1,867 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===============================================
+``amd-pstate`` CPU Performance Scaling Driver
+===============================================
+
+:Copyright: |copy| 2021 Advanced Micro Devices, Inc.
+
+:Author: Huang Rui <ray.huang@amd.com>
+
+
+Introduction
+===================
+
+``amd-pstate`` is the AMD CPU performance scaling driver that introduces a
+new CPU frequency control mechanism on modern AMD APU and CPU series in
+Linux kernel. The new mechanism is based on Collaborative Processor
+Performance Control (CPPC) which provides finer grain frequency management
+than legacy ACPI hardware P-States. Current AMD CPU/APU platforms are using
+the ACPI P-states driver to manage CPU frequency and clocks with switching
+only in 3 P-states. CPPC replaces the ACPI P-states controls and allows a
+flexible, low-latency interface for the Linux kernel to directly
+communicate the performance hints to hardware.
+
+``amd-pstate`` leverages the Linux kernel governors such as ``schedutil``,
+``ondemand``, etc. to manage the performance hints which are provided by
+CPPC hardware functionality that internally follows the hardware
+specification (for details refer to AMD64 Architecture Programmer's Manual
+Volume 2: System Programming [1]_). Currently, ``amd-pstate`` supports basic
+frequency control function according to kernel governors on some of the
+Zen2 and Zen3 processors, and we will implement more AMD specific functions
+in future after we verify them on the hardware and SBIOS.
+
+
+AMD CPPC Overview
+=======================
+
+Collaborative Processor Performance Control (CPPC) interface enumerates a
+continuous, abstract, and unit-less performance value in a scale that is
+not tied to a specific performance state / frequency. This is an ACPI
+standard [2]_ which software can specify application performance goals and
+hints as a relative target to the infrastructure limits. AMD processors
+provide the low latency register model (MSR) instead of an AML code
+interpreter for performance adjustments. ``amd-pstate`` will initialize a
+``struct cpufreq_driver`` instance, ``amd_pstate_driver``, with the callbacks
+to manage each performance update behavior. ::
+
+ Highest Perf ------>+-----------------------+                         +-----------------------+
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |          Max Perf  ---->|                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+ Nominal Perf ------>+-----------------------+                         +-----------------------+
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |      Desired Perf  ---->|                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+  Lowest non-        |                       |                         |                       |
+  linear perf ------>+-----------------------+                         +-----------------------+
+                     |                       |                         |                       |
+                     |                       |          Min perf  ---->|                       |
+                     |                       |                         |                       |
+  Lowest perf ------>+-----------------------+                         +-----------------------+
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+                     |                       |                         |                       |
+          0   ------>+-----------------------+                         +-----------------------+
+
+                                     AMD P-States Performance Scale
+
+
+.. _perf_cap:
+
+AMD CPPC Performance Capability
+--------------------------------
+
+Highest Performance (RO)
+.........................
+
+This is the absolute maximum performance an individual processor may reach,
+assuming ideal conditions. This performance level may not be sustainable
+for long durations and may only be achievable if other platform components
+are in a specific state; for example, it may require other processors to be in
+an idle state. This would be equivalent to the highest frequencies
+supported by the processor.
+
+Nominal (Guaranteed) Performance (RO)
+......................................
+
+This is the maximum sustained performance level of the processor, assuming
+ideal operating conditions. In the absence of an external constraint (power,
+thermal, etc.), this is the performance level the processor is expected to
+be able to maintain continuously. All cores/processors are expected to be
+able to sustain their nominal performance state simultaneously.
+
+Lowest non-linear Performance (RO)
+...................................
+
+This is the lowest performance level at which nonlinear power savings are
+achieved, for example, due to the combined effects of voltage and frequency
+scaling. Above this threshold, lower performance levels should be generally
+more energy efficient than higher performance levels. This register
+effectively conveys the most efficient performance level to ``amd-pstate``.
+
+Lowest Performance (RO)
+........................
+
+This is the absolute lowest performance level of the processor. Selecting a
+performance level lower than the lowest nonlinear performance level may
+cause an efficiency penalty but should reduce the instantaneous power
+consumption of the processor.
+
+AMD CPPC Performance Control
+------------------------------
+
+``amd-pstate`` passes performance goals through these registers. The
+register drives the behavior of the desired performance target.
+
+Minimum requested performance (RW)
+...................................
+
+``amd-pstate`` specifies the minimum allowed performance level.
+
+Maximum requested performance (RW)
+...................................
+
+``amd-pstate`` specifies a limit the maximum performance that is expected
+to be supplied by the hardware.
+
+Desired performance target (RW)
+...................................
+
+``amd-pstate`` specifies a desired target in the CPPC performance scale as
+a relative number. This can be expressed as percentage of nominal
+performance (infrastructure max). Below the nominal sustained performance
+level, desired performance expresses the average performance level of the
+processor subject to hardware. Above the nominal performance level,
+the processor must provide at least nominal performance requested and go higher
+if current operating conditions allow.
+
+Energy Performance Preference (EPP) (RW)
+.........................................
+
+This attribute provides a hint to the hardware if software wants to bias
+toward performance (0x0) or energy efficiency (0xff).
+
+
+Key Governors Support
+=======================
+
+``amd-pstate`` can be used with all the (generic) scaling governors listed
+by the ``scaling_available_governors`` policy attribute in ``sysfs``. Then,
+it is responsible for the configuration of policy objects corresponding to
+CPUs and provides the ``CPUFreq`` core (and the scaling governors attached
+to the policy objects) with accurate information on the maximum and minimum
+operating frequencies supported by the hardware. Users can check the
+``scaling_cur_freq`` information comes from the ``CPUFreq`` core.
+
+``amd-pstate`` mainly supports ``schedutil`` and ``ondemand`` for dynamic
+frequency control. It is to fine tune the processor configuration on
+``amd-pstate`` to the ``schedutil`` with CPU CFS scheduler. ``amd-pstate``
+registers the adjust_perf callback to implement performance update behavior
+similar to CPPC. It is initialized by ``sugov_start`` and then populates the
+CPU's update_util_data pointer to assign ``sugov_update_single_perf`` as the
+utilization update callback function in the CPU scheduler. The CPU scheduler
+will call ``cpufreq_update_util`` and assigns the target performance according
+to the ``struct sugov_cpu`` that the utilization update belongs to.
+Then, ``amd-pstate`` updates the desired performance according to the CPU
+scheduler assigned.
+
+.. _processor_support:
+
+Processor Support
+=======================
+
+The ``amd-pstate`` initialization will fail if the ``_CPC`` entry in the ACPI
+SBIOS does not exist in the detected processor. It uses ``acpi_cpc_valid``
+to check the existence of ``_CPC``. All Zen based processors support the legacy
+ACPI hardware P-States function, so when ``amd-pstate`` fails initialization,
+the kernel will fall back to initialize the ``acpi-cpufreq`` driver.
+
+There are two types of hardware implementations for ``amd-pstate``: one is
+`Full MSR Support <perf_cap_>`_ and another is `Shared Memory Support
+<perf_cap_>`_. It can use the :c:macro:`X86_FEATURE_CPPC` feature flag to
+indicate the different types. (For details, refer to the Processor Programming
+Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors [3]_.)
+``amd-pstate`` is to register different ``static_call`` instances for different
+hardware implementations.
+
+Currently, some of the Zen2 and Zen3 processors support ``amd-pstate``. In the
+future, it will be supported on more and more AMD processors.
+
+Full MSR Support
+-----------------
+
+Some new Zen3 processors such as Cezanne provide the MSR registers directly
+while the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is set.
+``amd-pstate`` can handle the MSR register to implement the fast switch
+function in ``CPUFreq`` that can reduce the latency of frequency control in
+interrupt context. The functions with a ``pstate_xxx`` prefix represent the
+operations on MSR registers.
+
+Shared Memory Support
+----------------------
+
+If the :c:macro:`X86_FEATURE_CPPC` CPU feature flag is not set, the
+processor supports the shared memory solution. In this case, ``amd-pstate``
+uses the ``cppc_acpi`` helper methods to implement the callback functions
+that are defined on ``static_call``. The functions with the ``cppc_xxx`` prefix
+represent the operations of ACPI CPPC helpers for the shared memory solution.
+
+
+AMD P-States and ACPI hardware P-States always can be supported in one
+processor. But AMD P-States has the higher priority and if it is enabled
+with :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond
+to the request from AMD P-States.
+
+
+User Space Interface in ``sysfs`` - Per-policy control
+======================================================
+
+``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to
+control its functionality at the system level. They are located in the
+``/sys/devices/system/cpu/cpufreq/policyX/`` directory and affect all CPUs. ::
+
+ root@hr-test1:/home/ray# ls /sys/devices/system/cpu/cpufreq/policy0/*amd*
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_highest_perf
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_hw_prefcore
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_freq
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_count
+ /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_prefcore_ranking
+
+
+``amd_pstate_highest_perf / amd_pstate_max_freq``
+
+Maximum CPPC performance and CPU frequency that the driver is allowed to
+set, in percent of the maximum supported CPPC performance level (the highest
+performance supported in `AMD CPPC Performance Capability <perf_cap_>`_).
+In some ASICs, the highest CPPC performance is not the one in the ``_CPC``
+table, so we need to expose it to sysfs. If boost is not active, but
+still supported, this maximum frequency will be larger than the one in
+``cpuinfo``.
+This attribute is read-only.
+
+``amd_pstate_lowest_nonlinear_freq``
+
+The lowest non-linear CPPC CPU frequency that the driver is allowed to set,
+in percent of the maximum supported CPPC performance level. (Please see the
+lowest non-linear performance in `AMD CPPC Performance Capability
+<perf_cap_>`_.)
+This attribute is read-only.
+
+``amd_pstate_hw_prefcore``
+
+Whether the platform supports the preferred core feature and it has
+been enabled. This attribute is read-only. This file is only visible
+on platforms which support the preferred core feature.
+
+``amd_pstate_prefcore_ranking``
+
+The performance ranking of the core. This number doesn't have any unit, but
+larger numbers are preferred at the time of reading. This can change at
+runtime based on platform conditions. This attribute is read-only. This file
+is only visible on platforms which support the preferred core feature.
+
+``amd_pstate_floor_freq``
+
+The floor frequency associated with each CPU. Userspace can write any
+value between ``cpuinfo_min_freq`` and ``scaling_max_freq`` into this
+file. When the system is under power or thermal constraints, the
+platform firmware will attempt to throttle the CPU frequency to the
+value specified in ``amd_pstate_floor_freq`` before throttling it
+further. This allows userspace to specify different floor frequencies
+to different CPUs. For optimal results, threads of the same core
+should have the same floor frequency value. This file is only visible
+on platforms that support the CPPC Performance Priority feature.
+
+
+``amd_pstate_floor_count``
+
+The number of distinct Floor Performance levels supported by the
+platform. For example, if this value is 2, then the number of unique
+values obtained from the command ``cat
+/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq |
+sort -n | uniq`` should be at most this number for the behavior
+described in ``amd_pstate_floor_freq`` to take effect. A zero value
+implies that the platform supports unlimited floor performance levels.
+This file is only visible on platforms that support the CPPC
+Performance Priority feature.
+
+**Note**: When ``amd_pstate_floor_count`` is non-zero, the frequency to
+which the CPU is throttled under power or thermal constraints is
+undefined when the number of unique values of ``amd_pstate_floor_freq``
+across all CPUs in the system exceeds ``amd_pstate_floor_count``.
+
+``energy_performance_available_preferences``
+
+A list of all the supported EPP preferences that could be used for
+``energy_performance_preference`` on this system.
+These profiles represent different hints that are provided
+to the low-level firmware about the user's desired energy vs efficiency
+tradeoff.  ``default`` represents the epp value is set by platform
+firmware. ``custom`` designates that integer values 0-255 may be written
+as well. ``dynamic`` designates that the EPP is modified dynamically
+on kernel events. See ``Dynamic energy performance profile`` section below to
+know more about the ``dynamic`` mode. This attribute is read-only.
+
+``energy_performance_preference``
+
+The current energy performance preference can be read from this attribute.
+and user can change current preference according to energy or performance needs
+Coarse named profiles are available in the attribute
+``energy_performance_available_preferences``.
+Users can also write individual integer values between 0 to 255.
+Lower epp values shift the bias towards improved performance while a higher epp
+value shifts the bias towards power-savings. The exact impact can change from
+one platform to the other. If a valid integer was last written, then a number
+will be returned on future reads. If a valid string was last written then a
+string will be returned on future reads. This attribute is read-write.
+
+``boost``
+The `boost` sysfs attribute provides control over the CPU core
+performance boost, allowing users to manage the maximum frequency limitation
+of the CPU. This attribute can be used to enable or disable the boost feature
+on individual CPUs.
+
+When the boost feature is enabled, the CPU can dynamically increase its frequency
+beyond the base frequency, providing enhanced performance for demanding workloads.
+On the other hand, disabling the boost feature restricts the CPU to operate at the
+base frequency, which may be desirable in certain scenarios to prioritize power
+efficiency or manage temperature.
+
+To manipulate the `boost` attribute, users can write a value of `0` to disable the
+boost or `1` to enable it, for the respective CPU using the sysfs path
+`/sys/devices/system/cpu/cpuX/cpufreq/boost`, where `X` represents the CPU number.
+
+Other performance and frequency values can be read back from
+``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
+
+Dynamic energy performance profile
+==================================
+The amd-pstate driver supports dynamically selecting the energy performance
+profile based on the system profile and the current power source in active mode.
+
+The ``dynamic`` mode is listed in
+``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_available_preferences``
+when available while running under the ``powersave`` governor. The ``dynamic``
+mode can be toggled on by writing the same to the sysfs file
+``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_preference`` when
+available.
+
+When ``energy_performance_preference`` is set to ``dynamic``, the driver will
+select a different energy performance profile when the machine is running on
+battery or AC power. The driver will also register with the platform profile
+handler to receive notifications of user desired power state and react to
+those.
+
+``amd-pstate`` vs ``acpi-cpufreq``
+======================================
+
+On the majority of AMD platforms supported by ``acpi-cpufreq``, the ACPI tables
+provided by the platform firmware are used for CPU performance scaling, but
+only provide 3 P-states on AMD processors.
+However, on modern AMD APU and CPU series, hardware provides the Collaborative
+Processor Performance Control according to the ACPI protocol and customizes this
+for AMD platforms. That is, fine-grained and continuous frequency ranges
+instead of the legacy hardware P-states. ``amd-pstate`` is the kernel
+module which supports the new AMD P-States mechanism on most of the future AMD
+platforms. The AMD P-States mechanism is the more performance and energy
+efficiency frequency management method on AMD processors.
+
+
+``amd-pstate`` Driver Operation Modes
+======================================
+
+``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode,
+non-autonomous (passive) mode and guided autonomous (guided) mode.
+Active/passive/guided mode can be chosen by different kernel parameters.
+
+- In autonomous mode, platform ignores the desired performance level request
+  and takes into account only the values set to the minimum, maximum and energy
+  performance preference registers.
+- In non-autonomous mode, platform gets desired performance level
+  from OS directly through Desired Performance Register.
+- In guided-autonomous mode, platform sets operating performance level
+  autonomously according to the current workload and within the limits set by
+  OS through min and max performance registers.
+
+Active Mode
+------------
+
+``amd_pstate=active``
+
+This is the low-level firmware control mode which is implemented by ``amd_pstate_epp``
+driver with ``amd_pstate=active`` passed to the kernel in the command line.
+In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software
+wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware.
+then CPPC power algorithm will calculate the runtime workload and adjust the realtime
+cores frequency according to the power supply and thermal, core voltage and some other
+hardware conditions.
+
+Passive Mode
+------------
+
+``amd_pstate=passive``
+
+It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line.
+In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC
+performance scale as a relative number. This can be expressed as percentage of nominal
+performance (infrastructure max). Below the nominal sustained performance level,
+desired performance expresses the average performance level of the processor subject
+to the Performance Reduction Tolerance register. Above the nominal performance level,
+processor must provide at least nominal performance requested and go higher if current
+operating conditions allow.
+
+Guided Mode
+-----------
+
+``amd_pstate=guided``
+
+If ``amd_pstate=guided`` is passed to kernel command line option then this mode
+is activated.  In this mode, driver requests minimum and maximum performance
+level and the platform autonomously selects a performance level in this range
+and appropriate to the current workload.
+
+``amd-pstate`` Preferred Core
+=================================
+
+The core frequency is subjected to the process variation in semiconductors.
+Not all cores are able to reach the maximum frequency respecting the
+infrastructure limits. Consequently, AMD has redefined the concept of
+maximum frequency of a part. This means that a fraction of cores can reach
+maximum frequency. To find the best process scheduling policy for a given
+scenario, OS needs to know the core ordering informed by the platform through
+highest performance capability register of the CPPC interface.
+
+``amd-pstate`` preferred core enables the scheduler to prefer scheduling on
+cores that can achieve a higher frequency with lower voltage. The preferred
+core rankings can dynamically change based on the workload, platform conditions,
+thermals and ageing.
+
+The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate``
+driver will also determine whether or not ``amd-pstate`` preferred core is
+supported by the platform.
+
+``amd-pstate`` driver will provide an initial core ordering when the system boots.
+The platform uses the CPPC interfaces to communicate the core ranking to the
+operating system and scheduler to make sure that OS is choosing the cores
+with highest performance firstly for scheduling the process. When ``amd-pstate``
+driver receives a message with the highest performance change, it will
+update the core ranking and set the cpu's priority.
+
+``amd-pstate`` Preferred Core Switch
+=====================================
+Kernel Parameters
+-----------------
+
+``amd-pstate`` preferred core has two states: enable and disable.
+Enable/disable states can be chosen by different kernel parameters.
+Default enable ``amd-pstate`` preferred core.
+
+``amd_prefcore=disable``
+
+For systems that support ``amd-pstate`` preferred core, the core rankings will
+always be advertised by the platform. But OS can choose to ignore that via the
+kernel parameter ``amd_prefcore=disable``.
+
+``amd_dynamic_epp``
+
+When AMD pstate is in auto mode, dynamic EPP will control whether the kernel
+autonomously changes the EPP mode. The default is disabled. It can be enabled
+with the kernel parameter ``amd_dynamic_epp=enable``.
+
+User Space Interface in ``sysfs`` - General
+===========================================
+
+Global Attributes
+-----------------
+
+``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to
+control its functionality at the system level.  They are located in the
+``/sys/devices/system/cpu/amd_pstate/`` directory and affect all CPUs.
+
+``status``
+	Operation mode of the driver: "active", "passive", "guided" or "disable".
+
+	"active"
+		The driver is functional and in the ``active mode``
+
+	"passive"
+		The driver is functional and in the ``passive mode``
+
+	"guided"
+		The driver is functional and in the ``guided mode``
+
+	"disable"
+		The driver is unregistered and not functional now.
+
+        This attribute can be written to in order to change the driver's
+        operation mode or to unregister it.  The string written to it must be
+        one of the possible values of it and, if successful, writing one of
+        these values to the sysfs file will cause the driver to switch over
+        to the operation mode represented by that string - or to be
+        unregistered in the "disable" case.
+
+``prefcore``
+	Preferred core state of the driver: "enabled" or "disabled".
+
+	"enabled"
+		Enable the ``amd-pstate`` preferred core.
+
+	"disabled"
+		Disable the ``amd-pstate`` preferred core
+
+
+        This attribute is read-only to check the state of preferred core set
+        by the kernel parameter.
+
+``cpupower`` tool support for ``amd-pstate``
+===============================================
+
+``amd-pstate`` is supported by the ``cpupower`` tool, which can be used to dump
+frequency information. Development is in progress to support more and more
+operations for the new ``amd-pstate`` module with this tool. ::
+
+ root@hr-test1:/home/ray# cpupower frequency-info
+ analyzing CPU 0:
+   driver: amd-pstate
+   CPUs which run at the same hardware frequency: 0
+   CPUs which need to have their frequency coordinated by software: 0
+   maximum transition latency: 131 us
+   hardware limits: 400 MHz - 4.68 GHz
+   available cpufreq governors: ondemand conservative powersave userspace performance schedutil
+   current policy: frequency should be within 400 MHz and 4.68 GHz.
+                   The governor "schedutil" may decide which speed to use
+                   within this range.
+   current CPU frequency: Unable to call hardware
+   current CPU frequency: 4.02 GHz (asserted by call to kernel)
+   boost state support:
+     Supported: yes
+     Active: yes
+     AMD PSTATE Highest Performance: 166. Maximum Frequency: 4.68 GHz.
+     AMD PSTATE Nominal Performance: 117. Nominal Frequency: 3.30 GHz.
+     AMD PSTATE Lowest Non-linear Performance: 39. Lowest Non-linear Frequency: 1.10 GHz.
+     AMD PSTATE Lowest Performance: 15. Lowest Frequency: 400 MHz.
+
+
+Diagnostics and Tuning
+=======================
+
+Trace Events
+--------------
+
+There are two static trace events that can be used for ``amd-pstate``
+diagnostics. One of them is the ``cpu_frequency`` trace event generally used
+by ``CPUFreq``, and the other one is the ``amd_pstate_perf`` trace event
+specific to ``amd-pstate``.  The following sequence of shell commands can
+be used to enable them and see their output (if the kernel is
+configured to support event tracing). ::
+
+ root@hr-test1:/home/ray# cd /sys/kernel/tracing/
+ root@hr-test1:/sys/kernel/tracing# echo 1 > events/amd_cpu/enable
+ root@hr-test1:/sys/kernel/tracing# cat trace
+ # tracer: nop
+ #
+ # entries-in-buffer/entries-written: 47827/42233061   #P:2
+ #
+ #                                _-----=> irqs-off
+ #                               / _----=> need-resched
+ #                              | / _---=> hardirq/softirq
+ #                              || / _--=> preempt-depth
+ #                              ||| /     delay
+ #           TASK-PID     CPU#  ||||   TIMESTAMP  FUNCTION
+ #              | |         |   ||||      |         |
+          <idle>-0       [015] dN...  4995.979886: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=15 changed=false fast_switch=true
+          <idle>-0       [007] d.h..  4995.979893: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=7 changed=false fast_switch=true
+             cat-2161    [000] d....  4995.980841: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=0 changed=false fast_switch=true
+            sshd-2125    [004] d.s..  4995.980968: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=4 changed=false fast_switch=true
+          <idle>-0       [007] d.s..  4995.980968: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=7 changed=false fast_switch=true
+          <idle>-0       [003] d.s..  4995.980971: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=3 changed=false fast_switch=true
+          <idle>-0       [011] d.s..  4995.980996: amd_pstate_perf: amd_min_perf=85 amd_des_perf=85 amd_max_perf=166 cpu_id=11 changed=false fast_switch=true
+
+The ``cpu_frequency`` trace event will be triggered either by the ``schedutil`` scaling
+governor (for the policies it is attached to), or by the ``CPUFreq`` core (for the
+policies with other scaling governors).
+
+
+Tracer Tool
+-------------
+
+``amd_pstate_tracer.py`` can record and parse ``amd-pstate`` trace log, then
+generate performance plots. This utility can be used to debug and tune the
+performance of ``amd-pstate`` driver. The tracer tool needs to import intel
+pstate tracer.
+
+Tracer tool located in ``linux/tools/power/x86/amd_pstate_tracer``. It can be
+used in two ways. If trace file is available, then directly parse the file
+with command ::
+
+ ./amd_pstate_trace.py [-c cpus] -t <trace_file> -n <test_name>
+
+Or generate trace file with root privilege, then parse and plot with command ::
+
+ sudo ./amd_pstate_trace.py [-c cpus] -n <test_name> -i <interval> [-m kbytes]
+
+The test result can be found in ``results/test_name``. Following is the example
+about part of the output. ::
+
+ common_cpu  common_secs  common_usecs  min_perf  des_perf  max_perf  freq    mperf   apef    tsc       load   duration_ms  sample_num  elapsed_time  common_comm
+ CPU_005     712          116384        39        49        166       0.7565  9645075 2214891 38431470  25.1   11.646       469         2.496         kworker/5:0-40
+ CPU_006     712          116408        39        49        166       0.6769  8950227 1839034 37192089  24.06  11.272       470         2.496         kworker/6:0-1264
+
+Unit Tests for amd-pstate
+-------------------------
+
+``amd-pstate-ut`` is a test module for testing the ``amd-pstate`` driver.
+
+ * It can help all users to verify their processor support (SBIOS/Firmware or Hardware).
+
+ * Kernel can have a basic function test to avoid the kernel regression during the update.
+
+ * We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization.
+
+1. Test case descriptions
+
+    1). Basic tests
+
+        Test prerequisite and basic functions for the ``amd-pstate`` driver.
+
+        +---------+--------------------------------+------------------------------------------------------------------------------------+
+        | Index   | Functions                      | Description                                                                        |
+        +=========+================================+====================================================================================+
+        | 1       | amd_pstate_ut_acpi_cpc_valid   || Check whether the _CPC object is present in SBIOS.                                |
+        |         |                                ||                                                                                   |
+        |         |                                || The detail refer to `Processor Support <processor_support_>`_.                    |
+        +---------+--------------------------------+------------------------------------------------------------------------------------+
+        | 2       | amd_pstate_ut_check_enabled    || Check whether AMD P-State is enabled.                                             |
+        |         |                                ||                                                                                   |
+        |         |                                || AMD P-States and ACPI hardware P-States always can be supported in one processor. |
+        |         |                                | But AMD P-States has the higher priority and if it is enabled with                 |
+        |         |                                | :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the      |
+        |         |                                | request from AMD P-States.                                                         |
+        +---------+--------------------------------+------------------------------------------------------------------------------------+
+        | 3       | amd_pstate_ut_check_perf       || Check if the each performance values are reasonable.                              |
+        |         |                                || highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0.           |
+        +---------+--------------------------------+------------------------------------------------------------------------------------+
+        | 4       | amd_pstate_ut_check_freq       || Check if the each frequency values and max freq when set support boost mode       |
+        |         |                                | are reasonable.                                                                    |
+        |         |                                || max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0                   |
+        |         |                                || If boost is not active but supported, this maximum frequency will be larger than  |
+        |         |                                | the one in ``cpuinfo``.                                                            |
+        +---------+--------------------------------+------------------------------------------------------------------------------------+
+
+    2). Tbench test
+
+        Test and monitor the cpu changes when running tbench benchmark under the specified governor.
+        These changes include desire performance, frequency, load, performance, energy etc.
+        The specified governor is ondemand or schedutil.
+        Tbench can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.
+
+    3). Gitsource test
+
+        Test and monitor the cpu changes when running gitsource benchmark under the specified governor.
+        These changes include desire performance, frequency, load, time, energy etc.
+        The specified governor is ondemand or schedutil.
+        Gitsource can also be tested on the ``acpi-cpufreq`` kernel driver for comparison.
+
+#. How to execute the tests
+
+   We use test module in the kselftest frameworks to implement it.
+   We create ``amd-pstate-ut`` module and tie it into kselftest.(for
+   details refer to Linux Kernel Selftests [4]_).
+
+    1). Build
+
+        + open the :c:macro:`CONFIG_X86_AMD_PSTATE` configuration option.
+        + set the :c:macro:`CONFIG_X86_AMD_PSTATE_UT` configuration option to M.
+        + make project
+        + make selftest ::
+
+            $ cd linux
+            $ make -C tools/testing/selftests
+
+        + make perf ::
+
+            $ cd tools/perf/
+            $ make
+
+
+    2). Installation & Steps ::
+
+        $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest
+        $ cp tools/perf/perf /usr/bin/perf
+        $ sudo ./kselftest/run_kselftest.sh -c amd-pstate
+
+    3). Specified test case ::
+
+        $ cd ~/kselftest/amd-pstate
+        $ sudo ./run.sh -t basic
+        $ sudo ./run.sh -t tbench
+        $ sudo ./run.sh -t tbench -m acpi-cpufreq
+        $ sudo ./run.sh -t gitsource
+        $ sudo ./run.sh -t gitsource -m acpi-cpufreq
+        $ ./run.sh --help
+        ./run.sh: illegal option -- -
+        Usage: ./run.sh [OPTION...]
+                [-h <help>]
+                [-o <output-file-for-dump>]
+                [-c <all: All testing,
+                     basic: Basic testing,
+                     tbench: Tbench testing,
+                     gitsource: Gitsource testing.>]
+                [-t <tbench time limit>]
+                [-p <tbench process number>]
+                [-l <loop times for tbench>]
+                [-i <amd tracer interval>]
+                [-m <comparative test: acpi-cpufreq>]
+
+
+    4). Results
+
+        + basic
+
+         When you finish test, you will get the following log info ::
+
+          $ dmesg | grep "amd_pstate_ut" | tee log.txt
+          [12977.570663] amd_pstate_ut: 1    amd_pstate_ut_acpi_cpc_valid  success!
+          [12977.570673] amd_pstate_ut: 2    amd_pstate_ut_check_enabled   success!
+          [12977.571207] amd_pstate_ut: 3    amd_pstate_ut_check_perf      success!
+          [12977.571212] amd_pstate_ut: 4    amd_pstate_ut_check_freq      success!
+
+        + tbench
+
+         When you finish test, you will get selftest.tbench.csv and png images.
+         The selftest.tbench.csv file contains the raw data and the drop of the comparative test.
+         The png images shows the performance, energy and performan per watt of each test.
+         Open selftest.tbench.csv :
+
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + Governor                                        | Round        | Des-perf | Freq    | Load     | Performance | Energy  | Performance Per Watt |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + Unit                                            |              |          | GHz     |          | MB/s        | J       | MB/J                 |
+         +=================================================+==============+==========+=========+==========+=============+=========+======================+
+         + amd-pstate-ondemand                             | 1            |          |         |          | 2504.05     | 1563.67 | 158.5378             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | 2            |          |         |          | 2243.64     | 1430.32 | 155.2941             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | 3            |          |         |          | 2183.88     | 1401.32 | 154.2860             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | Average      |          |         |          | 2310.52     | 1465.1  | 156.1268             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 1            | 165.329  | 1.62257 | 99.798   | 2136.54     | 1395.26 | 151.5971             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 2            | 166      | 1.49761 | 99.9993  | 2100.56     | 1380.5  | 150.6377             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 3            | 166      | 1.47806 | 99.9993  | 2084.12     | 1375.76 | 149.9737             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | Average      | 165.776  | 1.53275 | 99.9322  | 2107.07     | 1383.84 | 150.7399             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 1            |          |         |          | 2529.9      | 1564.4  | 160.0997             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 2            |          |         |          | 2249.76     | 1432.97 | 155.4297             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 3            |          |         |          | 2181.46     | 1406.88 | 153.5060             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | Average      |          |         |          | 2320.37     | 1468.08 | 156.4741             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 1            |          |         |          | 2137.64     | 1385.24 | 152.7723             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 2            |          |         |          | 2107.05     | 1372.23 | 152.0138             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 3            |          |         |          | 2085.86     | 1365.35 | 151.2433             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | Average      |          |         |          | 2110.18     | 1374.27 | 152.0136             |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) |          |         |          | -9.0584     | -6.3899 | -2.8506              |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand VS amd-pstate-schedutil     | Comprison(%) |          |         |          | 8.8053      | -5.5463 | -3.4503              |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand VS amd-pstate-ondemand    | Comprison(%) |          |         |          | -0.4245     | -0.2029 | -0.2219              |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil VS amd-pstate-schedutil  | Comprison(%) |          |         |          | -0.1473     | 0.6963  | -0.8378              |
+         +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+
+
+        + gitsource
+
+         When you finish test, you will get selftest.gitsource.csv and png images.
+         The selftest.gitsource.csv file contains the raw data and the drop of the comparative test.
+         The png images shows the performance, energy and performan per watt of each test.
+         Open selftest.gitsource.csv :
+
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + Governor                                        | Round        | Des-perf | Freq     | Load     | Time        | Energy  | Performance Per Watt |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + Unit                                            |              |          | GHz      |          | s           | J       | 1/J                  |
+         +=================================================+==============+==========+==========+==========+=============+=========+======================+
+         + amd-pstate-ondemand                             | 1            | 50.119   | 2.10509  | 23.3076  | 475.69      | 865.78  | 0.001155027          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | 2            | 94.8006  | 1.98771  | 56.6533  | 467.1       | 839.67  | 0.001190944          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | 3            | 76.6091  | 2.53251  | 43.7791  | 467.69      | 855.85  | 0.001168429          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand                             | Average      | 73.8429  | 2.20844  | 41.2467  | 470.16      | 853.767 | 0.001171279          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 1            | 165.919  | 1.62319  | 98.3868  | 464.17      | 866.8   | 0.001153668          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 2            | 165.97   | 1.31309  | 99.5712  | 480.15      | 880.4   | 0.001135847          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | 3            | 165.973  | 1.28448  | 99.9252  | 481.79      | 867.02  | 0.001153375          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-schedutil                            | Average      | 165.954  | 1.40692  | 99.2944  | 475.37      | 871.407 | 0.001147569          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 1            |          |          |          | 2379.62     | 742.96  | 0.001345967          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 2            |          |          |          | 441.74      | 817.49  | 0.001223256          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | 3            |          |          |          | 455.48      | 820.01  | 0.001219497          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand                           | Average      |          |          |          | 425.613     | 793.487 | 0.001260260          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 1            |          |          |          | 459.69      | 838.54  | 0.001192548          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 2            |          |          |          | 466.55      | 830.89  | 0.001203528          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | 3            |          |          |          | 470.38      | 837.32  | 0.001194286          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil                          | Average      |          |          |          | 465.54      | 835.583 | 0.001196769          |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) |          |          |          | 9.3810      | 5.3051  | -5.0379              |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + amd-pstate-ondemand VS amd-pstate-schedutil     | Comprison(%) | 124.7392 | -36.2934 | 140.7329 | 1.1081      | 2.0661  | -2.0242              |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-ondemand VS amd-pstate-ondemand    | Comprison(%) |          |          |          | 10.4665     | 7.5968  | -7.0605              |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+         + acpi-cpufreq-schedutil VS amd-pstate-schedutil  | Comprison(%) |          |          |          | 2.1115      | 4.2873  | -4.1110              |
+         +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+
+
+Reference
+===========
+
+.. [1] AMD64 Architecture Programmer's Manual Volume 2: System Programming,
+       https://docs.amd.com/v/u/en-US/24593_3.44_APM_Vol2
+
+.. [2] Advanced Configuration and Power Interface Specification,
+       https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf
+
+.. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors
+       https://docs.amd.com/v/u/en-US/56569-A1-PUB_3.03
+
+.. [4] Linux Kernel Selftests,
+       https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html
diff --git a/Documentation/admin-guide/pm/cpufreq.rst b/Documentation/admin-guide/pm/cpufreq.rst
new file mode 100644
index 000000000..34baf20cc
--- /dev/null
+++ b/Documentation/admin-guide/pm/cpufreq.rst
@@ -0,0 +1,725 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+.. |intel_pstate| replace:: :doc:`intel_pstate <intel_pstate>`
+
+=======================
+CPU Performance Scaling
+=======================
+
+:Copyright: |copy| 2017 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+The Concept of CPU Performance Scaling
+======================================
+
+The majority of modern processors are capable of operating in a number of
+different clock frequency and voltage configurations, often referred to as
+Operating Performance Points or P-states (in ACPI terminology).  As a rule,
+the higher the clock frequency and the higher the voltage, the more instructions
+can be retired by the CPU over a unit of time, but also the higher the clock
+frequency and the higher the voltage, the more energy is consumed over a unit of
+time (or the more power is drawn) by the CPU in the given P-state.  Therefore
+there is a natural tradeoff between the CPU capacity (the number of instructions
+that can be executed over a unit of time) and the power drawn by the CPU.
+
+In some situations it is desirable or even necessary to run the program as fast
+as possible and then there is no reason to use any P-states different from the
+highest one (i.e. the highest-performance frequency/voltage configuration
+available).  In some other cases, however, it may not be necessary to execute
+instructions so quickly and maintaining the highest available CPU capacity for a
+relatively long time without utilizing it entirely may be regarded as wasteful.
+It also may not be physically possible to maintain maximum CPU capacity for too
+long for thermal or power supply capacity reasons or similar.  To cover those
+cases, there are hardware interfaces allowing CPUs to be switched between
+different frequency/voltage configurations or (in the ACPI terminology) to be
+put into different P-states.
+
+Typically, they are used along with algorithms to estimate the required CPU
+capacity, so as to decide which P-states to put the CPUs into.  Of course, since
+the utilization of the system generally changes over time, that has to be done
+repeatedly on a regular basis.  The activity by which this happens is referred
+to as CPU performance scaling or CPU frequency scaling (because it involves
+adjusting the CPU clock frequency).
+
+
+CPU Performance Scaling in Linux
+================================
+
+The Linux kernel supports CPU performance scaling by means of the ``CPUFreq``
+(CPU Frequency scaling) subsystem that consists of three layers of code: the
+core, scaling governors and scaling drivers.
+
+The ``CPUFreq`` core provides the common code infrastructure and user space
+interfaces for all platforms that support CPU performance scaling.  It defines
+the basic framework in which the other components operate.
+
+Scaling governors implement algorithms to estimate the required CPU capacity.
+As a rule, each governor implements one, possibly parametrized, scaling
+algorithm.
+
+Scaling drivers talk to the hardware.  They provide scaling governors with
+information on the available P-states (or P-state ranges in some cases) and
+access platform-specific hardware interfaces to change CPU P-states as requested
+by scaling governors.
+
+In principle, all available scaling governors can be used with every scaling
+driver.  That design is based on the observation that the information used by
+performance scaling algorithms for P-state selection can be represented in a
+platform-independent form in the majority of cases, so it should be possible
+to use the same performance scaling algorithm implemented in exactly the same
+way regardless of which scaling driver is used.  Consequently, the same set of
+scaling governors should be suitable for every supported platform.
+
+However, that observation may not hold for performance scaling algorithms
+based on information provided by the hardware itself, for example through
+feedback registers, as that information is typically specific to the hardware
+interface it comes from and may not be easily represented in an abstract,
+platform-independent way.  For this reason, ``CPUFreq`` allows scaling drivers
+to bypass the governor layer and implement their own performance scaling
+algorithms.  That is done by the |intel_pstate| scaling driver.
+
+
+``CPUFreq`` Policy Objects
+==========================
+
+In some cases the hardware interface for P-state control is shared by multiple
+CPUs.  That is, for example, the same register (or set of registers) is used to
+control the P-state of multiple CPUs at the same time and writing to it affects
+all of those CPUs simultaneously.
+
+Sets of CPUs sharing hardware P-state control interfaces are represented by
+``CPUFreq`` as struct cpufreq_policy objects.  For consistency,
+struct cpufreq_policy is also used when there is only one CPU in the given
+set.
+
+The ``CPUFreq`` core maintains a pointer to a struct cpufreq_policy object for
+every CPU in the system, including CPUs that are currently offline.  If multiple
+CPUs share the same hardware P-state control interface, all of the pointers
+corresponding to them point to the same struct cpufreq_policy object.
+
+``CPUFreq`` uses struct cpufreq_policy as its basic data type and the design
+of its user space interface is based on the policy concept.
+
+
+CPU Initialization
+==================
+
+First of all, a scaling driver has to be registered for ``CPUFreq`` to work.
+It is only possible to register one scaling driver at a time, so the scaling
+driver is expected to be able to handle all CPUs in the system.
+
+The scaling driver may be registered before or after CPU registration.  If
+CPUs are registered earlier, the driver core invokes the ``CPUFreq`` core to
+take a note of all of the already registered CPUs during the registration of the
+scaling driver.  In turn, if any CPUs are registered after the registration of
+the scaling driver, the ``CPUFreq`` core will be invoked to take note of them
+at their registration time.
+
+In any case, the ``CPUFreq`` core is invoked to take note of any logical CPU it
+has not seen so far as soon as it is ready to handle that CPU.  [Note that the
+logical CPU may be a physical single-core processor, or a single core in a
+multicore processor, or a hardware thread in a physical processor or processor
+core.  In what follows "CPU" always means "logical CPU" unless explicitly stated
+otherwise and the word "processor" is used to refer to the physical part
+possibly including multiple logical CPUs.]
+
+Once invoked, the ``CPUFreq`` core checks if the policy pointer is already set
+for the given CPU and if so, it skips the policy object creation.  Otherwise,
+a new policy object is created and initialized, which involves the creation of
+a new policy directory in ``sysfs``, and the policy pointer corresponding to
+the given CPU is set to the new policy object's address in memory.
+
+Next, the scaling driver's ``->init()`` callback is invoked with the policy
+pointer of the new CPU passed to it as the argument.  That callback is expected
+to initialize the performance scaling hardware interface for the given CPU (or,
+more precisely, for the set of CPUs sharing the hardware interface it belongs
+to, represented by its policy object) and, if the policy object it has been
+called for is new, to set parameters of the policy, like the minimum and maximum
+frequencies supported by the hardware, the table of available frequencies (if
+the set of supported P-states is not a continuous range), and the mask of CPUs
+that belong to the same policy (including both online and offline CPUs).  That
+mask is then used by the core to populate the policy pointers for all of the
+CPUs in it.
+
+The next major initialization step for a new policy object is to attach a
+scaling governor to it (to begin with, that is the default scaling governor
+determined by the kernel command line or configuration, but it may be changed
+later via ``sysfs``).  First, a pointer to the new policy object is passed to
+the governor's ``->init()`` callback which is expected to initialize all of the
+data structures necessary to handle the given policy and, possibly, to add
+a governor ``sysfs`` interface to it.  Next, the governor is started by
+invoking its ``->start()`` callback.
+
+That callback is expected to register per-CPU utilization update callbacks for
+all of the online CPUs belonging to the given policy with the CPU scheduler.
+The utilization update callbacks will be invoked by the CPU scheduler on
+important events, like task enqueue and dequeue, on every iteration of the
+scheduler tick or generally whenever the CPU utilization may change (from the
+scheduler's perspective).  They are expected to carry out computations needed
+to determine the P-state to use for the given policy going forward and to
+invoke the scaling driver to make changes to the hardware in accordance with
+the P-state selection.  The scaling driver may be invoked directly from
+scheduler context or asynchronously, via a kernel thread or workqueue, depending
+on the configuration and capabilities of the scaling driver and the governor.
+
+Similar steps are taken for policy objects that are not new, but were "inactive"
+previously, meaning that all of the CPUs belonging to them were offline.  The
+only practical difference in that case is that the ``CPUFreq`` core will attempt
+to use the scaling governor previously used with the policy that became
+"inactive" (and is re-initialized now) instead of the default governor.
+
+In turn, if a previously offline CPU is being brought back online, but some
+other CPUs sharing the policy object with it are online already, there is no
+need to re-initialize the policy object at all.  In that case, it only is
+necessary to restart the scaling governor so that it can take the new online CPU
+into account.  That is achieved by invoking the governor's ``->stop`` and
+``->start()`` callbacks, in this order, for the entire policy.
+
+As mentioned before, the |intel_pstate| scaling driver bypasses the scaling
+governor layer of ``CPUFreq`` and provides its own P-state selection algorithms.
+Consequently, if |intel_pstate| is used, scaling governors are not attached to
+new policy objects.  Instead, the driver's ``->setpolicy()`` callback is invoked
+to register per-CPU utilization update callbacks for each policy.  These
+callbacks are invoked by the CPU scheduler in the same way as for scaling
+governors, but in the |intel_pstate| case they both determine the P-state to
+use and change the hardware configuration accordingly in one go from scheduler
+context.
+
+The policy objects created during CPU initialization and other data structures
+associated with them are torn down when the scaling driver is unregistered
+(which happens when the kernel module containing it is unloaded, for example) or
+when the last CPU belonging to the given policy in unregistered.
+
+
+Policy Interface in ``sysfs``
+=============================
+
+During the initialization of the kernel, the ``CPUFreq`` core creates a
+``sysfs`` directory (kobject) called ``cpufreq`` under
+:file:`/sys/devices/system/cpu/`.
+
+That directory contains a ``policyX`` subdirectory (where ``X`` represents an
+integer number) for every policy object maintained by the ``CPUFreq`` core.
+Each ``policyX`` directory is pointed to by ``cpufreq`` symbolic links
+under :file:`/sys/devices/system/cpu/cpuY/` (where ``Y`` represents an integer
+that may be different from the one represented by ``X``) for all of the CPUs
+associated with (or belonging to) the given policy.  The ``policyX`` directories
+in :file:`/sys/devices/system/cpu/cpufreq` each contain policy-specific
+attributes (files) to control ``CPUFreq`` behavior for the corresponding policy
+objects (that is, for all of the CPUs associated with them).
+
+Some of those attributes are generic.  They are created by the ``CPUFreq`` core
+and their behavior generally does not depend on what scaling driver is in use
+and what scaling governor is attached to the given policy.  Some scaling drivers
+also add driver-specific attributes to the policy directories in ``sysfs`` to
+control policy-specific aspects of driver behavior.
+
+The generic attributes under :file:`/sys/devices/system/cpu/cpufreq/policyX/`
+are the following:
+
+``affected_cpus``
+	List of online CPUs belonging to this policy (i.e. sharing the hardware
+	performance scaling interface represented by the ``policyX`` policy
+	object).
+
+``bios_limit``
+	If the platform firmware (BIOS) tells the OS to apply an upper limit to
+	CPU frequencies, that limit will be reported through this attribute (if
+	present).
+
+	The existence of the limit may be a result of some (often unintentional)
+	BIOS settings, restrictions coming from a service processor or other
+	BIOS/HW-based mechanisms.
+
+	This does not cover ACPI thermal limitations which can be discovered
+	through a generic thermal driver.
+
+	This attribute is not present if the scaling driver in use does not
+	support it.
+
+``cpuinfo_cur_freq``
+	Current frequency of the CPUs belonging to this policy as obtained from
+	the hardware (in KHz).
+
+	This is expected to be the frequency the hardware actually runs at.
+	If that frequency cannot be determined, this attribute should not
+	be present.
+
+``cpuinfo_avg_freq``
+        An average frequency (in KHz) of all CPUs belonging to a given policy,
+        derived from a hardware provided feedback and reported on a time frame
+        spanning at most few milliseconds.
+
+        This is expected to be based on the frequency the hardware actually runs
+        at and, as such, might require specialised hardware support (such as AMU
+        extension on ARM). If one cannot be determined, this attribute should
+        not be present.
+
+        Note that failed attempt to retrieve current frequency for a given
+        CPU(s) will result in an appropriate error, i.e.: EAGAIN for CPU that
+        remains idle (raised on ARM).
+
+``cpuinfo_max_freq``
+	Maximum possible operating frequency the CPUs belonging to this policy
+	can run at (in kHz).
+
+``cpuinfo_min_freq``
+	Minimum possible operating frequency the CPUs belonging to this policy
+	can run at (in kHz).
+
+``cpuinfo_transition_latency``
+	The time it takes to switch the CPUs belonging to this policy from one
+	P-state to another, in nanoseconds.
+
+``related_cpus``
+	List of all (online and offline) CPUs belonging to this policy.
+
+``scaling_available_frequencies``
+	List of available frequencies of the CPUs belonging to this policy
+	(in kHz).
+
+``scaling_available_governors``
+	List of ``CPUFreq`` scaling governors present in the kernel that can
+	be attached to this policy or (if the |intel_pstate| scaling driver is
+	in use) list of scaling algorithms provided by the driver that can be
+	applied to this policy.
+
+	[Note that some governors are modular and it may be necessary to load a
+	kernel module for the governor held by it to become available and be
+	listed by this attribute.]
+
+``scaling_cur_freq``
+	Current frequency of all of the CPUs belonging to this policy (in kHz).
+
+	In the majority of cases, this is the frequency of the last P-state
+	requested by the scaling driver from the hardware using the scaling
+	interface provided by it, which may or may not reflect the frequency
+	the CPU is actually running at (due to hardware design and other
+	limitations).
+
+	Some architectures (e.g. ``x86``) may attempt to provide information
+	more precisely reflecting the current CPU frequency through this
+	attribute, but that still may not be the exact current CPU frequency as
+	seen by the hardware at the moment. This behavior though, is only
+	available via c:macro:``CPUFREQ_ARCH_CUR_FREQ`` option.
+
+``scaling_driver``
+	The scaling driver currently in use.
+
+``scaling_governor``
+	The scaling governor currently attached to this policy or (if the
+	|intel_pstate| scaling driver is in use) the scaling algorithm
+	provided by the driver that is currently applied to this policy.
+
+	This attribute is read-write and writing to it will cause a new scaling
+	governor to be attached to this policy or a new scaling algorithm
+	provided by the scaling driver to be applied to it (in the
+	|intel_pstate| case), as indicated by the string written to this
+	attribute (which must be one of the names listed by the
+	``scaling_available_governors`` attribute described above).
+
+``scaling_max_freq``
+	Maximum frequency the CPUs belonging to this policy are allowed to be
+	running at (in kHz).
+
+	This attribute is read-write and writing a string representing an
+	integer to it will cause a new limit to be set (it must not be lower
+	than the value of the ``scaling_min_freq`` attribute).
+
+``scaling_min_freq``
+	Minimum frequency the CPUs belonging to this policy are allowed to be
+	running at (in kHz).
+
+	This attribute is read-write and writing a string representing a
+	non-negative integer to it will cause a new limit to be set (it must not
+	be higher than the value of the ``scaling_max_freq`` attribute).
+
+``scaling_setspeed``
+	This attribute is functional only if the `userspace`_ scaling governor
+	is attached to the given policy.
+
+	It returns the last frequency requested by the governor (in kHz) or can
+	be written to in order to set a new frequency for the policy.
+
+
+Generic Scaling Governors
+=========================
+
+``CPUFreq`` provides generic scaling governors that can be used with all
+scaling drivers.  As stated before, each of them implements a single, possibly
+parametrized, performance scaling algorithm.
+
+Scaling governors are attached to policy objects and different policy objects
+can be handled by different scaling governors at the same time (although that
+may lead to suboptimal results in some cases).
+
+The scaling governor for a given policy object can be changed at any time with
+the help of the ``scaling_governor`` policy attribute in ``sysfs``.
+
+Some governors expose ``sysfs`` attributes to control or fine-tune the scaling
+algorithms implemented by them.  Those attributes, referred to as governor
+tunables, can be either global (system-wide) or per-policy, depending on the
+scaling driver in use.  If the driver requires governor tunables to be
+per-policy, they are located in a subdirectory of each policy directory.
+Otherwise, they are located in a subdirectory under
+:file:`/sys/devices/system/cpu/cpufreq/`.  In either case the name of the
+subdirectory containing the governor tunables is the name of the governor
+providing them.
+
+``performance``
+---------------
+
+When attached to a policy object, this governor causes the highest frequency,
+within the ``scaling_max_freq`` policy limit, to be requested for that policy.
+
+The request is made once at that time the governor for the policy is set to
+``performance`` and whenever the ``scaling_max_freq`` or ``scaling_min_freq``
+policy limits change after that.
+
+``powersave``
+-------------
+
+When attached to a policy object, this governor causes the lowest frequency,
+within the ``scaling_min_freq`` policy limit, to be requested for that policy.
+
+The request is made once at that time the governor for the policy is set to
+``powersave`` and whenever the ``scaling_max_freq`` or ``scaling_min_freq``
+policy limits change after that.
+
+``userspace``
+-------------
+
+This governor does not do anything by itself.  Instead, it allows user space
+to set the CPU frequency for the policy it is attached to by writing to the
+``scaling_setspeed`` attribute of that policy. Though the intention may be to
+set an exact frequency for the policy, the actual frequency may vary depending
+on hardware coordination, thermal and power limits, and other factors.
+
+``schedutil``
+-------------
+
+This governor uses CPU utilization data available from the CPU scheduler.  It
+generally is regarded as a part of the CPU scheduler, so it can access the
+scheduler's internal data structures directly.
+
+It runs entirely in scheduler context, although in some cases it may need to
+invoke the scaling driver asynchronously when it decides that the CPU frequency
+should be changed for a given policy (that depends on whether or not the driver
+is capable of changing the CPU frequency from scheduler context).
+
+The actions of this governor for a particular CPU depend on the scheduling class
+invoking its utilization update callback for that CPU.  If it is invoked by the
+RT or deadline scheduling classes, the governor will increase the frequency to
+the allowed maximum (that is, the ``scaling_max_freq`` policy limit).  In turn,
+if it is invoked by the CFS scheduling class, the governor will use the
+Per-Entity Load Tracking (PELT) metric for the root control group of the
+given CPU as the CPU utilization estimate (see the *Per-entity load tracking*
+LWN.net article [1]_ for a description of the PELT mechanism).  Then, the new
+CPU frequency to apply is computed in accordance with the formula
+
+	f = 1.25 * ``f_0`` * ``util`` / ``max``
+
+where ``util`` is the PELT number, ``max`` is the theoretical maximum of
+``util``, and ``f_0`` is either the maximum possible CPU frequency for the given
+policy (if the PELT number is frequency-invariant), or the current CPU frequency
+(otherwise).
+
+This governor also employs a mechanism allowing it to temporarily bump up the
+CPU frequency for tasks that have been waiting on I/O most recently, called
+"IO-wait boosting".  That happens when the :c:macro:`SCHED_CPUFREQ_IOWAIT` flag
+is passed by the scheduler to the governor callback which causes the frequency
+to go up to the allowed maximum immediately and then draw back to the value
+returned by the above formula over time.
+
+This governor exposes only one tunable:
+
+``rate_limit_us``
+	Minimum time (in microseconds) that has to pass between two consecutive
+	runs of governor computations (default: 1.5 times the scaling driver's
+	transition latency or 1ms if the driver does not provide a latency value).
+
+	The purpose of this tunable is to reduce the scheduler context overhead
+	of the governor which might be excessive without it.
+
+This governor generally is regarded as a replacement for the older `ondemand`_
+and `conservative`_ governors (described below), as it is simpler and more
+tightly integrated with the CPU scheduler, its overhead in terms of CPU context
+switches and similar is less significant, and it uses the scheduler's own CPU
+utilization metric, so in principle its decisions should not contradict the
+decisions made by the other parts of the scheduler.
+
+``ondemand``
+------------
+
+This governor uses CPU load as a CPU frequency selection metric.
+
+In order to estimate the current CPU load, it measures the time elapsed between
+consecutive invocations of its worker routine and computes the fraction of that
+time in which the given CPU was not idle.  The ratio of the non-idle (active)
+time to the total CPU time is taken as an estimate of the load.
+
+If this governor is attached to a policy shared by multiple CPUs, the load is
+estimated for all of them and the greatest result is taken as the load estimate
+for the entire policy.
+
+The worker routine of this governor has to run in process context, so it is
+invoked asynchronously (via a workqueue) and CPU P-states are updated from
+there if necessary.  As a result, the scheduler context overhead from this
+governor is minimum, but it causes additional CPU context switches to happen
+relatively often and the CPU P-state updates triggered by it can be relatively
+irregular.  Also, it affects its own CPU load metric by running code that
+reduces the CPU idle time (even though the CPU idle time is only reduced very
+slightly by it).
+
+It generally selects CPU frequencies proportional to the estimated load, so that
+the value of the ``cpuinfo_max_freq`` policy attribute corresponds to the load of
+1 (or 100%), and the value of the ``cpuinfo_min_freq`` policy attribute
+corresponds to the load of 0, unless when the load exceeds a (configurable)
+speedup threshold, in which case it will go straight for the highest frequency
+it is allowed to use (the ``scaling_max_freq`` policy limit).
+
+This governor exposes the following tunables:
+
+``sampling_rate``
+	This is how often the governor's worker routine should run, in
+	microseconds.
+
+	Typically, it is set to values of the order of 2000 (2 ms).  Its
+	default value is to add a 50% breathing room
+	to ``cpuinfo_transition_latency`` on each policy this governor is
+	attached to. The minimum is typically the length of two scheduler
+	ticks.
+
+	If this tunable is per-policy, the following shell command sets the time
+	represented by it to be 1.5 times as high as the transition latency
+	(the default)::
+
+	# echo $(($(cat cpuinfo_transition_latency) * 3 / 2)) > ondemand/sampling_rate
+
+``up_threshold``
+	If the estimated CPU load is above this value (in percent), the governor
+	will set the frequency to the maximum value allowed for the policy.
+	Otherwise, the selected frequency will be proportional to the estimated
+	CPU load.
+
+``ignore_nice_load``
+	If set to 1 (default 0), it will cause the CPU load estimation code to
+	treat the CPU time spent on executing tasks with "nice" levels greater
+	than 0 as CPU idle time.
+
+	This may be useful if there are tasks in the system that should not be
+	taken into account when deciding what frequency to run the CPUs at.
+	Then, to make that happen it is sufficient to increase the "nice" level
+	of those tasks above 0 and set this attribute to 1.
+
+``sampling_down_factor``
+	Temporary multiplier, between 1 (default) and 100000 inclusive, to apply to
+	the ``sampling_rate`` value if the CPU load goes above ``up_threshold``.
+
+	This causes the next execution of the governor's worker routine (after
+	setting the frequency to the allowed maximum) to be delayed, so the
+	frequency stays at the maximum level for a longer time.
+
+	Frequency fluctuations in some bursty workloads may be avoided this way
+	at the cost of additional energy spent on maintaining the maximum CPU
+	capacity.
+
+``powersave_bias``
+	Reduction factor to apply to the original frequency target of the
+	governor (including the maximum value used when the ``up_threshold``
+	value is exceeded by the estimated CPU load) or sensitivity threshold
+	for the AMD frequency sensitivity powersave bias driver
+	(:file:`drivers/cpufreq/amd_freq_sensitivity.c`), between 0 and 1000
+	inclusive.
+
+	If the AMD frequency sensitivity powersave bias driver is not loaded,
+	the effective frequency to apply is given by
+
+		f * (1 - ``powersave_bias`` / 1000)
+
+	where f is the governor's original frequency target.  The default value
+	of this attribute is 0 in that case.
+
+	If the AMD frequency sensitivity powersave bias driver is loaded, the
+	value of this attribute is 400 by default and it is used in a different
+	way.
+
+	On Family 16h (and later) AMD processors there is a mechanism to get a
+	measured workload sensitivity, between 0 and 100% inclusive, from the
+	hardware.  That value can be used to estimate how the performance of the
+	workload running on a CPU will change in response to frequency changes.
+
+	The performance of a workload with the sensitivity of 0 (memory-bound or
+	IO-bound) is not expected to increase at all as a result of increasing
+	the CPU frequency, whereas workloads with the sensitivity of 100%
+	(CPU-bound) are expected to perform much better if the CPU frequency is
+	increased.
+
+	If the workload sensitivity is less than the threshold represented by
+	the ``powersave_bias`` value, the sensitivity powersave bias driver
+	will cause the governor to select a frequency lower than its original
+	target, so as to avoid over-provisioning workloads that will not benefit
+	from running at higher CPU frequencies.
+
+``conservative``
+----------------
+
+This governor uses CPU load as a CPU frequency selection metric.
+
+It estimates the CPU load in the same way as the `ondemand`_ governor described
+above, but the CPU frequency selection algorithm implemented by it is different.
+
+Namely, it avoids changing the frequency significantly over short time intervals
+which may not be suitable for systems with limited power supply capacity (e.g.
+battery-powered).  To achieve that, it changes the frequency in relatively
+small steps, one step at a time, up or down - depending on whether or not a
+(configurable) threshold has been exceeded by the estimated CPU load.
+
+This governor exposes the following tunables:
+
+``freq_step``
+	Frequency step in percent of the maximum frequency the governor is
+	allowed to set (the ``scaling_max_freq`` policy limit), between 0 and
+	100 (5 by default).
+
+	This is how much the frequency is allowed to change in one go.  Setting
+	it to 0 disables frequency changes by the governor entirely and setting
+	it to 100 effectively causes the governor to periodically
+	switch the frequency between the ``scaling_min_freq`` and
+	``scaling_max_freq`` policy limits.
+
+``down_threshold``
+	Threshold value (in percent, 20 by default) used to determine the
+	frequency change direction.
+
+	If the estimated CPU load is greater than this value, the frequency will
+	go up (by ``freq_step``).  If the load is less than this value (and the
+	``sampling_down_factor`` mechanism is not in effect), the frequency will
+	go down.  Otherwise, the frequency will not be changed.
+
+``sampling_down_factor``
+	Frequency decrease deferral factor, between 1 (default) and 10
+	inclusive.
+
+	It effectively causes the frequency to go down ``sampling_down_factor``
+	times slower than it ramps up.
+
+
+Frequency Boost Support
+=======================
+
+Background
+----------
+
+Some processors support a mechanism to raise the operating frequency of some
+cores in a multicore package temporarily (and above the sustainable frequency
+threshold for the whole package) under certain conditions, for example if the
+whole chip is not fully utilized and below its intended thermal or power budget.
+
+Different names are used by different vendors to refer to this functionality.
+For Intel processors it is referred to as "Turbo Boost", AMD calls it
+"Turbo-Core" or (in technical documentation) "Core Performance Boost" and so on.
+As a rule, it also is implemented differently by different vendors.  The simple
+term "frequency boost" is used here for brevity to refer to all of those
+implementations.
+
+The frequency boost mechanism may be either hardware-based or software-based.
+If it is hardware-based (e.g. on x86), the decision to trigger the boosting is
+made by the hardware (although in general it requires the hardware to be put
+into a special state in which it can control the CPU frequency within certain
+limits).  If it is software-based (e.g. on ARM), the scaling driver decides
+whether or not to trigger boosting and when to do that.
+
+The ``boost`` File in ``sysfs``
+-------------------------------
+
+This file is located under :file:`/sys/devices/system/cpu/cpufreq/` and controls
+the "boost" setting for the whole system.  It is not present if the underlying
+scaling driver does not support the frequency boost mechanism (or supports it,
+but provides a driver-specific interface for controlling it, like
+|intel_pstate|).
+
+If the value in this file is 1, the frequency boost mechanism is enabled.  This
+means that either the hardware can be put into states in which it is able to
+trigger boosting (in the hardware-based case), or the software is allowed to
+trigger boosting (in the software-based case).  It does not mean that boosting
+is actually in use at the moment on any CPUs in the system.  It only means a
+permission to use the frequency boost mechanism (which still may never be used
+for other reasons).
+
+If the value in this file is 0, the frequency boost mechanism is disabled and
+cannot be used at all.
+
+The only values that can be written to this file are 0 and 1.
+
+Rationale for Boost Control Knob
+--------------------------------
+
+The frequency boost mechanism is generally intended to help to achieve optimum
+CPU performance on time scales below software resolution (e.g. below the
+scheduler tick interval) and it is demonstrably suitable for many workloads, but
+it may lead to problems in certain situations.
+
+For this reason, many systems make it possible to disable the frequency boost
+mechanism in the platform firmware (BIOS) setup, but that requires the system to
+be restarted for the setting to be adjusted as desired, which may not be
+practical at least in some cases.  For example:
+
+  1. Boosting means overclocking the processor, although under controlled
+     conditions.  Generally, the processor's energy consumption increases
+     as a result of increasing its frequency and voltage, even temporarily.
+     That may not be desirable on systems that switch to power sources of
+     limited capacity, such as batteries, so the ability to disable the boost
+     mechanism while the system is running may help there (but that depends on
+     the workload too).
+
+  2. In some situations deterministic behavior is more important than
+     performance or energy consumption (or both) and the ability to disable
+     boosting while the system is running may be useful then.
+
+  3. To examine the impact of the frequency boost mechanism itself, it is useful
+     to be able to run tests with and without boosting, preferably without
+     restarting the system in the meantime.
+
+  4. Reproducible results are important when running benchmarks.  Since
+     the boosting functionality depends on the load of the whole package,
+     single-thread performance may vary because of it which may lead to
+     unreproducible results sometimes.  That can be avoided by disabling the
+     frequency boost mechanism before running benchmarks sensitive to that
+     issue.
+
+Legacy AMD ``cpb`` Knob
+-----------------------
+
+The AMD powernow-k8 scaling driver supports a ``sysfs`` knob very similar to
+the global ``boost`` one.  It is used for disabling/enabling the "Core
+Performance Boost" feature of some AMD processors.
+
+If present, that knob is located in every ``CPUFreq`` policy directory in
+``sysfs`` (:file:`/sys/devices/system/cpu/cpufreq/policyX/`) and is called
+``cpb``, which indicates a more fine grained control interface.  The actual
+implementation, however, works on the system-wide basis and setting that knob
+for one policy causes the same value of it to be set for all of the other
+policies at the same time.
+
+That knob is still supported on AMD processors that support its underlying
+hardware feature, but it may be configured out of the kernel (via the
+:c:macro:`CONFIG_X86_ACPI_CPUFREQ_CPB` configuration option) and the global
+``boost`` knob is present regardless.  Thus it is always possible use the
+``boost`` knob instead of the ``cpb`` one which is highly recommended, as that
+is more consistent with what all of the other systems do (and the ``cpb`` knob
+may not be supported any more in the future).
+
+The ``cpb`` knob is never present for any processors without the underlying
+hardware feature (e.g. all Intel ones), even if the
+:c:macro:`CONFIG_X86_ACPI_CPUFREQ_CPB` configuration option is set.
+
+
+References
+==========
+
+.. [1] Jonathan Corbet, *Per-entity load tracking*,
+       https://lwn.net/Articles/531853/
diff --git a/Documentation/admin-guide/pm/cpufreq_drivers.rst b/Documentation/admin-guide/pm/cpufreq_drivers.rst
new file mode 100644
index 000000000..9a134ae65
--- /dev/null
+++ b/Documentation/admin-guide/pm/cpufreq_drivers.rst
@@ -0,0 +1,274 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================================
+Legacy Documentation of CPU Performance Scaling Drivers
+=======================================================
+
+Included below are historic documents describing assorted
+:doc:`CPU performance scaling <cpufreq>` drivers.  They are reproduced verbatim,
+with the original white space formatting and indentation preserved, except for
+the added leading space character in every line of text.
+
+
+AMD PowerNow! Drivers
+=====================
+
+::
+
+ PowerNow! and Cool'n'Quiet are AMD names for frequency
+ management capabilities in AMD processors. As the hardware
+ implementation changes in new generations of the processors,
+ there is a different cpu-freq driver for each generation.
+
+ Note that the driver's will not load on the "wrong" hardware,
+ so it is safe to try each driver in turn when in doubt as to
+ which is the correct driver.
+
+ Note that the functionality to change frequency (and voltage)
+ is not available in all processors. The drivers will refuse
+ to load on processors without this capability. The capability
+ is detected with the cpuid instruction.
+
+ The drivers use BIOS supplied tables to obtain frequency and
+ voltage information appropriate for a particular platform.
+ Frequency transitions will be unavailable if the BIOS does
+ not supply these tables.
+
+ 6th Generation: powernow-k6
+
+ 7th Generation: powernow-k7: Athlon, Duron, Geode.
+
+ 8th Generation: powernow-k8: Athlon, Athlon 64, Opteron, Sempron.
+ Documentation on this functionality in 8th generation processors
+ is available in the "BIOS and Kernel Developer's Guide", publication
+ 26094, in chapter 9, available for download from www.amd.com.
+
+ BIOS supplied data, for powernow-k7 and for powernow-k8, may be
+ from either the PSB table or from ACPI objects. The ACPI support
+ is only available if the kernel config sets CONFIG_ACPI_PROCESSOR.
+ The powernow-k8 driver will attempt to use ACPI if so configured,
+ and fall back to PST if that fails.
+ The powernow-k7 driver will try to use the PSB support first, and
+ fall back to ACPI if the PSB support fails. A module parameter,
+ acpi_force, is provided to force ACPI support to be used instead
+ of PSB support.
+
+
+``cpufreq-nforce2``
+===================
+
+::
+
+ The cpufreq-nforce2 driver changes the FSB on nVidia nForce2 platforms.
+
+ This works better than on other platforms, because the FSB of the CPU
+ can be controlled independently from the PCI/AGP clock.
+
+ The module has two options:
+
+ 	fid: 	 multiplier * 10 (for example 8.5 = 85)
+ 	min_fsb: minimum FSB
+
+ If not set, fid is calculated from the current CPU speed and the FSB.
+ min_fsb defaults to FSB at boot time - 50 MHz.
+
+ IMPORTANT: The available range is limited downwards!
+            Also the minimum available FSB can differ, for systems
+            booting with 200 MHz, 150 should always work.
+
+
+``pcc-cpufreq``
+===============
+
+::
+
+ /*
+  *  pcc-cpufreq.txt - PCC interface documentation
+  *
+  *  Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
+  *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
+  *      Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
+  */
+
+
+ 			Processor Clocking Control Driver
+ 			---------------------------------
+
+ Contents:
+ ---------
+ 1.	Introduction
+ 1.1	PCC interface
+ 1.1.1	Get Average Frequency
+ 1.1.2	Set Desired Frequency
+ 1.2	Platforms affected
+ 2.	Driver and /sys details
+ 2.1	scaling_available_frequencies
+ 2.2	cpuinfo_transition_latency
+ 2.3	cpuinfo_cur_freq
+ 2.4	related_cpus
+ 3.	Caveats
+
+ 1. Introduction:
+ ----------------
+ Processor Clocking Control (PCC) is an interface between the platform
+ firmware and OSPM. It is a mechanism for coordinating processor
+ performance (ie: frequency) between the platform firmware and the OS.
+
+ The PCC driver (pcc-cpufreq) allows OSPM to take advantage of the PCC
+ interface.
+
+ OS utilizes the PCC interface to inform platform firmware what frequency the
+ OS wants for a logical processor. The platform firmware attempts to achieve
+ the requested frequency. If the request for the target frequency could not be
+ satisfied by platform firmware, then it usually means that power budget
+ conditions are in place, and "power capping" is taking place.
+
+ 1.1 PCC interface:
+ ------------------
+ The complete PCC specification is available here:
+ https://acpica.org/sites/acpica/files/Processor-Clocking-Control-v1p0.pdf
+
+ PCC relies on a shared memory region that provides a channel for communication
+ between the OS and platform firmware. PCC also implements a "doorbell" that
+ is used by the OS to inform the platform firmware that a command has been
+ sent.
+
+ The ACPI PCCH() method is used to discover the location of the PCC shared
+ memory region. The shared memory region header contains the "command" and
+ "status" interface. PCCH() also contains details on how to access the platform
+ doorbell.
+
+ The following commands are supported by the PCC interface:
+ * Get Average Frequency
+ * Set Desired Frequency
+
+ The ACPI PCCP() method is implemented for each logical processor and is
+ used to discover the offsets for the input and output buffers in the shared
+ memory region.
+
+ When PCC mode is enabled, the platform will not expose processor performance
+ or throttle states (_PSS, _TSS and related ACPI objects) to OSPM. Therefore,
+ the native P-state driver (such as acpi-cpufreq for Intel, powernow-k8 for
+ AMD) will not load.
+
+ However, OSPM remains in control of policy. The governor (eg: "ondemand")
+ computes the required performance for each processor based on server workload.
+ The PCC driver fills in the command interface, and the input buffer and
+ communicates the request to the platform firmware. The platform firmware is
+ responsible for delivering the requested performance.
+
+ Each PCC command is "global" in scope and can affect all the logical CPUs in
+ the system. Therefore, PCC is capable of performing "group" updates. With PCC
+ the OS is capable of getting/setting the frequency of all the logical CPUs in
+ the system with a single call to the BIOS.
+
+ 1.1.1 Get Average Frequency:
+ ----------------------------
+ This command is used by the OSPM to query the running frequency of the
+ processor since the last time this command was completed. The output buffer
+ indicates the average unhalted frequency of the logical processor expressed as
+ a percentage of the nominal (ie: maximum) CPU frequency. The output buffer
+ also signifies if the CPU frequency is limited by a power budget condition.
+
+ 1.1.2 Set Desired Frequency:
+ ----------------------------
+ This command is used by the OSPM to communicate to the platform firmware the
+ desired frequency for a logical processor. The output buffer is currently
+ ignored by OSPM. The next invocation of "Get Average Frequency" will inform
+ OSPM if the desired frequency was achieved or not.
+
+ 1.2 Platforms affected:
+ -----------------------
+ The PCC driver will load on any system where the platform firmware:
+ * supports the PCC interface, and the associated PCCH() and PCCP() methods
+ * assumes responsibility for managing the hardware clocking controls in order
+ to deliver the requested processor performance
+
+ Currently, certain HP ProLiant platforms implement the PCC interface. On those
+ platforms PCC is the "default" choice.
+
+ However, it is possible to disable this interface via a BIOS setting. In
+ such an instance, as is also the case on platforms where the PCC interface
+ is not implemented, the PCC driver will fail to load silently.
+
+ 2. Driver and /sys details:
+ ---------------------------
+ When the driver loads, it merely prints the lowest and the highest CPU
+ frequencies supported by the platform firmware.
+
+ The PCC driver loads with a message such as:
+ pcc-cpufreq: (v1.00.00) driver loaded with frequency limits: 1600 MHz, 2933
+ MHz
+
+ This means that the OPSM can request the CPU to run at any frequency in
+ between the limits (1600 MHz, and 2933 MHz) specified in the message.
+
+ Internally, there is no need for the driver to convert the "target" frequency
+ to a corresponding P-state.
+
+ The VERSION number for the driver will be of the format v.xy.ab.
+ eg: 1.00.02
+    ----- --
+     |    |
+     |    -- this will increase with bug fixes/enhancements to the driver
+     |-- this is the version of the PCC specification the driver adheres to
+
+
+ The following is a brief discussion on some of the fields exported via the
+ /sys filesystem and how their values are affected by the PCC driver:
+
+ 2.1 scaling_available_frequencies:
+ ----------------------------------
+ scaling_available_frequencies is not created in /sys. No intermediate
+ frequencies need to be listed because the BIOS will try to achieve any
+ frequency, within limits, requested by the governor. A frequency does not have
+ to be strictly associated with a P-state.
+
+ 2.2 cpuinfo_transition_latency:
+ -------------------------------
+ The cpuinfo_transition_latency field is 0. The PCC specification does
+ not include a field to expose this value currently.
+
+ 2.3 cpuinfo_cur_freq:
+ ---------------------
+ A) Often cpuinfo_cur_freq will show a value different than what is declared
+ in the scaling_available_frequencies or scaling_cur_freq, or scaling_max_freq.
+ This is due to "turbo boost" available on recent Intel processors. If certain
+ conditions are met the BIOS can achieve a slightly higher speed than requested
+ by OSPM. An example:
+
+ scaling_cur_freq	: 2933000
+ cpuinfo_cur_freq	: 3196000
+
+ B) There is a round-off error associated with the cpuinfo_cur_freq value.
+ Since the driver obtains the current frequency as a "percentage" (%) of the
+ nominal frequency from the BIOS, sometimes, the values displayed by
+ scaling_cur_freq and cpuinfo_cur_freq may not match. An example:
+
+ scaling_cur_freq	: 1600000
+ cpuinfo_cur_freq	: 1583000
+
+ In this example, the nominal frequency is 2933 MHz. The driver obtains the
+ current frequency, cpuinfo_cur_freq, as 54% of the nominal frequency:
+
+ 	54% of 2933 MHz = 1583 MHz
+
+ Nominal frequency is the maximum frequency of the processor, and it usually
+ corresponds to the frequency of the P0 P-state.
+
+ 2.4 related_cpus:
+ -----------------
+ The related_cpus field is identical to affected_cpus.
+
+ affected_cpus	: 4
+ related_cpus	: 4
+
+ Currently, the PCC driver does not evaluate _PSD. The platforms that support
+ PCC do not implement SW_ALL. So OSPM doesn't need to perform any coordination
+ to ensure that the same frequency is requested of all dependent CPUs.
+
+ 3. Caveats:
+ -----------
+ The "cpufreq_stats" module in its present form cannot be loaded and
+ expected to work with the PCC driver. Since the "cpufreq_stats" module
+ provides information wrt each P-state, it is not applicable to the PCC driver.
diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst
new file mode 100644
index 000000000..be4c1120e
--- /dev/null
+++ b/Documentation/admin-guide/pm/cpuidle.rst
@@ -0,0 +1,666 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+.. |struct cpuidle_state| replace:: :c:type:`struct cpuidle_state <cpuidle_state>`
+.. |cpufreq| replace:: :doc:`CPU Performance Scaling <cpufreq>`
+
+========================
+CPU Idle Time Management
+========================
+
+:Copyright: |copy| 2018 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+Concepts
+========
+
+Modern processors are generally able to enter states in which the execution of
+a program is suspended and instructions belonging to it are not fetched from
+memory or executed.  Those states are the *idle* states of the processor.
+
+Since part of the processor hardware is not used in idle states, entering them
+generally allows power drawn by the processor to be reduced and, in consequence,
+it is an opportunity to save energy.
+
+CPU idle time management is an energy-efficiency feature concerned about using
+the idle states of processors for this purpose.
+
+Logical CPUs
+------------
+
+CPU idle time management operates on CPUs as seen by the *CPU scheduler* (that
+is the part of the kernel responsible for the distribution of computational
+work in the system).  In its view, CPUs are *logical* units.  That is, they need
+not be separate physical entities and may just be interfaces appearing to
+software as individual single-core processors.  In other words, a CPU is an
+entity which appears to be fetching instructions that belong to one sequence
+(program) from memory and executing them, but it need not work this way
+physically.  Generally, three different cases can be consider here.
+
+First, if the whole processor can only follow one sequence of instructions (one
+program) at a time, it is a CPU.  In that case, if the hardware is asked to
+enter an idle state, that applies to the processor as a whole.
+
+Second, if the processor is multi-core, each core in it is able to follow at
+least one program at a time.  The cores need not be entirely independent of each
+other (for example, they may share caches), but still most of the time they
+work physically in parallel with each other, so if each of them executes only
+one program, those programs run mostly independently of each other at the same
+time.  The entire cores are CPUs in that case and if the hardware is asked to
+enter an idle state, that applies to the core that asked for it in the first
+place, but it also may apply to a larger unit (say a "package" or a "cluster")
+that the core belongs to (in fact, it may apply to an entire hierarchy of larger
+units containing the core).  Namely, if all of the cores in the larger unit
+except for one have been put into idle states at the "core level" and the
+remaining core asks the processor to enter an idle state, that may trigger it
+to put the whole larger unit into an idle state which also will affect the
+other cores in that unit.
+
+Finally, each core in a multi-core processor may be able to follow more than one
+program in the same time frame (that is, each core may be able to fetch
+instructions from multiple locations in memory and execute them in the same time
+frame, but not necessarily entirely in parallel with each other).  In that case
+the cores present themselves to software as "bundles" each consisting of
+multiple individual single-core "processors", referred to as *hardware threads*
+(or hyper-threads specifically on Intel hardware), that each can follow one
+sequence of instructions.  Then, the hardware threads are CPUs from the CPU idle
+time management perspective and if the processor is asked to enter an idle state
+by one of them, the hardware thread (or CPU) that asked for it is stopped, but
+nothing more happens, unless all of the other hardware threads within the same
+core also have asked the processor to enter an idle state.  In that situation,
+the core may be put into an idle state individually or a larger unit containing
+it may be put into an idle state as a whole (if the other cores within the
+larger unit are in idle states already).
+
+Idle CPUs
+---------
+
+Logical CPUs, simply referred to as "CPUs" in what follows, are regarded as
+*idle* by the Linux kernel when there are no tasks to run on them except for the
+special "idle" task.
+
+Tasks are the CPU scheduler's representation of work.  Each task consists of a
+sequence of instructions to execute, or code, data to be manipulated while
+running that code, and some context information that needs to be loaded into the
+processor every time the task's code is run by a CPU.  The CPU scheduler
+distributes work by assigning tasks to run to the CPUs present in the system.
+
+Tasks can be in various states.  In particular, they are *runnable* if there are
+no specific conditions preventing their code from being run by a CPU as long as
+there is a CPU available for that (for example, they are not waiting for any
+events to occur or similar).  When a task becomes runnable, the CPU scheduler
+assigns it to one of the available CPUs to run and if there are no more runnable
+tasks assigned to it, the CPU will load the given task's context and run its
+code (from the instruction following the last one executed so far, possibly by
+another CPU).  [If there are multiple runnable tasks assigned to one CPU
+simultaneously, they will be subject to prioritization and time sharing in order
+to allow them to make some progress over time.]
+
+The special "idle" task becomes runnable if there are no other runnable tasks
+assigned to the given CPU and the CPU is then regarded as idle.  In other words,
+in Linux idle CPUs run the code of the "idle" task called *the idle loop*.  That
+code may cause the processor to be put into one of its idle states, if they are
+supported, in order to save energy, but if the processor does not support any
+idle states, or there is not enough time to spend in an idle state before the
+next wakeup event, or there are strict latency constraints preventing any of the
+available idle states from being used, the CPU will simply execute more or less
+useless instructions in a loop until it is assigned a new task to run.
+
+
+.. _idle-loop:
+
+The Idle Loop
+=============
+
+The idle loop code takes two major steps in every iteration of it.  First, it
+calls into a code module referred to as the *governor* that belongs to the CPU
+idle time management subsystem called ``CPUIdle`` to select an idle state for
+the CPU to ask the hardware to enter.  Second, it invokes another code module
+from the ``CPUIdle`` subsystem, called the *driver*, to actually ask the
+processor hardware to enter the idle state selected by the governor.
+
+The role of the governor is to find an idle state most suitable for the
+conditions at hand.  For this purpose, idle states that the hardware can be
+asked to enter by logical CPUs are represented in an abstract way independent of
+the platform or the processor architecture and organized in a one-dimensional
+(linear) array.  That array has to be prepared and supplied by the ``CPUIdle``
+driver matching the platform the kernel is running on at the initialization
+time.  This allows ``CPUIdle`` governors to be independent of the underlying
+hardware and to work with any platforms that the Linux kernel can run on.
+
+Each idle state present in that array is characterized by two parameters to be
+taken into account by the governor, the *target residency* and the (worst-case)
+*exit latency*.  The target residency is the minimum time the hardware must
+spend in the given state, including the time needed to enter it (which may be
+substantial), in order to save more energy than it would save by entering one of
+the shallower idle states instead.  [The "depth" of an idle state roughly
+corresponds to the power drawn by the processor in that state.]  The exit
+latency, in turn, is the maximum time it will take a CPU asking the processor
+hardware to enter an idle state to start executing the first instruction after a
+wakeup from that state.  Note that in general the exit latency also must cover
+the time needed to enter the given state in case the wakeup occurs when the
+hardware is entering it and it must be entered completely to be exited in an
+ordered manner.
+
+There are two types of information that can influence the governor's decisions.
+First of all, the governor knows the time until the closest timer event.  That
+time is known exactly, because the kernel programs timers and it knows exactly
+when they will trigger, and it is the maximum time the hardware that the given
+CPU depends on can spend in an idle state, including the time necessary to enter
+and exit it.  However, the CPU may be woken up by a non-timer event at any time
+(in particular, before the closest timer triggers) and it generally is not known
+when that may happen.  The governor can only see how much time the CPU actually
+was idle after it has been woken up (that time will be referred to as the *idle
+duration* from now on) and it can use that information somehow along with the
+time until the closest timer to estimate the idle duration in future.  How the
+governor uses that information depends on what algorithm is implemented by it
+and that is the primary reason for having more than one governor in the
+``CPUIdle`` subsystem.
+
+There are four ``CPUIdle`` governors available, ``menu``, `TEO <teo-gov_>`_,
+``ladder`` and ``haltpoll``.  Which of them is used by default depends on the
+configuration of the kernel and in particular on whether or not the scheduler
+tick can be `stopped by the idle loop <idle-cpus-and-tick_>`_.  Available
+governors can be read from the :file:`available_governors`, and the governor
+can be changed at runtime.  The name of the ``CPUIdle`` governor currently
+used by the kernel can be read from the :file:`current_governor_ro` or
+:file:`current_governor` file under :file:`/sys/devices/system/cpu/cpuidle/`
+in ``sysfs``.
+
+Which ``CPUIdle`` driver is used, on the other hand, usually depends on the
+platform the kernel is running on, but there are platforms with more than one
+matching driver.  For example, there are two drivers that can work with the
+majority of Intel platforms, ``intel_idle`` and ``acpi_idle``, one with
+hardcoded idle states information and the other able to read that information
+from the system's ACPI tables, respectively.  Still, even in those cases, the
+driver chosen at the system initialization time cannot be replaced later, so the
+decision on which one of them to use has to be made early (on Intel platforms
+the ``acpi_idle`` driver will be used if ``intel_idle`` is disabled for some
+reason or if it does not recognize the processor).  The name of the ``CPUIdle``
+driver currently used by the kernel can be read from the :file:`current_driver`
+file under :file:`/sys/devices/system/cpu/cpuidle/` in ``sysfs``.
+
+
+.. _idle-cpus-and-tick:
+
+Idle CPUs and The Scheduler Tick
+================================
+
+The scheduler tick is a timer that triggers periodically in order to implement
+the time sharing strategy of the CPU scheduler.  Of course, if there are
+multiple runnable tasks assigned to one CPU at the same time, the only way to
+allow them to make reasonable progress in a given time frame is to make them
+share the available CPU time.  Namely, in rough approximation, each task is
+given a slice of the CPU time to run its code, subject to the scheduling class,
+prioritization and so on and when that time slice is used up, the CPU should be
+switched over to running (the code of) another task.  The currently running task
+may not want to give the CPU away voluntarily, however, and the scheduler tick
+is there to make the switch happen regardless.  That is not the only role of the
+tick, but it is the primary reason for using it.
+
+The scheduler tick is problematic from the CPU idle time management perspective,
+because it triggers periodically and relatively often (depending on the kernel
+configuration, the length of the tick period is between 1 ms and 10 ms).
+Thus, if the tick is allowed to trigger on idle CPUs, it will not make sense
+for them to ask the hardware to enter idle states with target residencies above
+the tick period length.  Moreover, in that case the idle duration of any CPU
+will never exceed the tick period length and the energy used for entering and
+exiting idle states due to the tick wakeups on idle CPUs will be wasted.
+
+Fortunately, it is not really necessary to allow the tick to trigger on idle
+CPUs, because (by definition) they have no tasks to run except for the special
+"idle" one.  In other words, from the CPU scheduler perspective, the only user
+of the CPU time on them is the idle loop.  Since the time of an idle CPU need
+not be shared between multiple runnable tasks, the primary reason for using the
+tick goes away if the given CPU is idle.  Consequently, it is possible to stop
+the scheduler tick entirely on idle CPUs in principle, even though that may not
+always be worth the effort.
+
+Whether or not it makes sense to stop the scheduler tick in the idle loop
+depends on what is expected by the governor.  First, if there is another
+(non-tick) timer due to trigger within the tick range, stopping the tick clearly
+would be a waste of time, even though the timer hardware may not need to be
+reprogrammed in that case.  Second, if the governor is expecting a non-timer
+wakeup within the tick range, stopping the tick is not necessary and it may even
+be harmful.  Namely, in that case the governor will select an idle state with
+the target residency within the time until the expected wakeup, so that state is
+going to be relatively shallow.  The governor really cannot select a deep idle
+state then, as that would contradict its own expectation of a wakeup in short
+order.  Now, if the wakeup really occurs shortly, stopping the tick would be a
+waste of time and in this case the timer hardware would need to be reprogrammed,
+which is expensive.  On the other hand, if the tick is stopped and the wakeup
+does not occur any time soon, the hardware may spend indefinite amount of time
+in the shallow idle state selected by the governor, which will be a waste of
+energy.  Hence, if the governor is expecting a wakeup of any kind within the
+tick range, it is better to allow the tick trigger.  Otherwise, however, the
+governor will select a relatively deep idle state, so the tick should be stopped
+so that it does not wake up the CPU too early.
+
+In any case, the governor knows what it is expecting and the decision on whether
+or not to stop the scheduler tick belongs to it.  Still, if the tick has been
+stopped already (in one of the previous iterations of the loop), it is better
+to leave it as is and the governor needs to take that into account.
+
+The kernel can be configured to disable stopping the scheduler tick in the idle
+loop altogether.  That can be done through the build-time configuration of it
+(by unsetting the ``CONFIG_NO_HZ_IDLE`` configuration option) or by passing
+``nohz=off`` to it in the command line.  In both cases, as the stopping of the
+scheduler tick is disabled, the governor's decisions regarding it are simply
+ignored by the idle loop code and the tick is never stopped.
+
+The systems that run kernels configured to allow the scheduler tick to be
+stopped on idle CPUs are referred to as *tickless* systems and they are
+generally regarded as more energy-efficient than the systems running kernels in
+which the tick cannot be stopped.  If the given system is tickless, it will use
+the ``menu`` governor by default and if it is not tickless, the default
+``CPUIdle`` governor on it will be ``ladder``.
+
+
+.. _menu-gov:
+
+The ``menu`` Governor
+=====================
+
+The ``menu`` governor is the default ``CPUIdle`` governor for tickless systems.
+It is quite complex, but the basic principle of its design is straightforward.
+Namely, when invoked to select an idle state for a CPU (i.e. an idle state that
+the CPU will ask the processor hardware to enter), it attempts to predict the
+idle duration and uses the predicted value for idle state selection.
+
+It first uses a simple pattern recognition algorithm to obtain a preliminary
+idle duration prediction.  Namely, it saves the last 8 observed idle duration
+values and, when predicting the idle duration next time, it computes the average
+and variance of them.  If the variance is small (smaller than 400 square
+milliseconds) or it is small relative to the average (the average is greater
+that 6 times the standard deviation), the average is regarded as the "typical
+interval" value.  Otherwise, either the longest or the shortest (depending on
+which one is farther from the average) of the saved observed idle duration
+values is discarded and the computation is repeated for the remaining ones.
+
+Again, if the variance of them is small (in the above sense), the average is
+taken as the "typical interval" value and so on, until either the "typical
+interval" is determined or too many data points are disregarded.  In the latter
+case, if the size of the set of data points still under consideration is
+sufficiently large, the next idle duration is not likely to be above the largest
+idle duration value still in that set, so that value is taken as the predicted
+next idle duration.  Finally, if the set of data points still under
+consideration is too small, no prediction is made.
+
+If the preliminary prediction of the next idle duration computed this way is
+long enough, the governor obtains the time until the closest timer event with
+the assumption that the scheduler tick will be stopped.  That time, referred to
+as the *sleep length* in what follows, is the upper bound on the time before the
+next CPU wakeup.  It is used to determine the sleep length range, which in turn
+is needed to get the sleep length correction factor.
+
+The ``menu`` governor maintains an array containing several correction factor
+values that correspond to different sleep length ranges organized so that each
+range represented in the array is approximately 10 times wider than the previous
+one.
+
+The correction factor for the given sleep length range (determined before
+selecting the idle state for the CPU) is updated after the CPU has been woken
+up and the closer the sleep length is to the observed idle duration, the closer
+to 1 the correction factor becomes (it must fall between 0 and 1 inclusive).
+The sleep length is multiplied by the correction factor for the range that it
+falls into to obtain an approximation of the predicted idle duration that is
+compared to the "typical interval" determined previously and the minimum of
+the two is taken as the final idle duration prediction.
+
+If the "typical interval" value is small, which means that the CPU is likely
+to be woken up soon enough, the sleep length computation is skipped as it may
+be costly and the idle duration is simply predicted to equal the "typical
+interval" value.
+
+Now, the governor is ready to walk the list of idle states and choose one of
+them.  For this purpose, it compares the target residency of each state with
+the predicted idle duration and the exit latency of it with the with the latency
+limit coming from the power management quality of service, or `PM QoS <cpu-pm-qos_>`_,
+framework.  It selects the state with the target residency closest to the predicted
+idle duration, but still below it, and exit latency that does not exceed the
+limit.
+
+In the final step the governor may still need to refine the idle state selection
+if it has not decided to `stop the scheduler tick <idle-cpus-and-tick_>`_.  That
+happens if the idle duration predicted by it is less than the tick period and
+the tick has not been stopped already (in a previous iteration of the idle
+loop).  Then, the sleep length used in the previous computations may not reflect
+the real time until the closest timer event and if it really is greater than
+that time, the governor may need to select a shallower state with a suitable
+target residency.
+
+
+.. _teo-gov:
+
+The Timer Events Oriented (TEO) Governor
+========================================
+
+The timer events oriented (TEO) governor is an alternative ``CPUIdle`` governor
+for tickless systems.  It follows the same basic strategy as the ``menu`` `one
+<menu-gov_>`_: it always tries to find the deepest idle state suitable for the
+given conditions.  However, it applies a different approach to that problem.
+
+.. kernel-doc:: drivers/cpuidle/governors/teo.c
+   :doc: teo-description
+
+.. _idle-states-representation:
+
+Representation of Idle States
+=============================
+
+For the CPU idle time management purposes all of the physical idle states
+supported by the processor have to be represented as a one-dimensional array of
+|struct cpuidle_state| objects each allowing an individual (logical) CPU to ask
+the processor hardware to enter an idle state of certain properties.  If there
+is a hierarchy of units in the processor, one |struct cpuidle_state| object can
+cover a combination of idle states supported by the units at different levels of
+the hierarchy.  In that case, the `target residency and exit latency parameters
+of it <idle-loop_>`_, must reflect the properties of the idle state at the
+deepest level (i.e. the idle state of the unit containing all of the other
+units).
+
+For example, take a processor with two cores in a larger unit referred to as
+a "module" and suppose that asking the hardware to enter a specific idle state
+(say "X") at the "core" level by one core will trigger the module to try to
+enter a specific idle state of its own (say "MX") if the other core is in idle
+state "X" already.  In other words, asking for idle state "X" at the "core"
+level gives the hardware a license to go as deep as to idle state "MX" at the
+"module" level, but there is no guarantee that this is going to happen (the core
+asking for idle state "X" may just end up in that state by itself instead).
+Then, the target residency of the |struct cpuidle_state| object representing
+idle state "X" must reflect the minimum time to spend in idle state "MX" of
+the module (including the time needed to enter it), because that is the minimum
+time the CPU needs to be idle to save any energy in case the hardware enters
+that state.  Analogously, the exit latency parameter of that object must cover
+the exit time of idle state "MX" of the module (and usually its entry time too),
+because that is the maximum delay between a wakeup signal and the time the CPU
+will start to execute the first new instruction (assuming that both cores in the
+module will always be ready to execute instructions as soon as the module
+becomes operational as a whole).
+
+There are processors without direct coordination between different levels of the
+hierarchy of units inside them, however.  In those cases asking for an idle
+state at the "core" level does not automatically affect the "module" level, for
+example, in any way and the ``CPUIdle`` driver is responsible for the entire
+handling of the hierarchy.  Then, the definition of the idle state objects is
+entirely up to the driver, but still the physical properties of the idle state
+that the processor hardware finally goes into must always follow the parameters
+used by the governor for idle state selection (for instance, the actual exit
+latency of that idle state must not exceed the exit latency parameter of the
+idle state object selected by the governor).
+
+In addition to the target residency and exit latency idle state parameters
+discussed above, the objects representing idle states each contain a few other
+parameters describing the idle state and a pointer to the function to run in
+order to ask the hardware to enter that state.  Also, for each
+|struct cpuidle_state| object, there is a corresponding
+:c:type:`struct cpuidle_state_usage <cpuidle_state_usage>` one containing usage
+statistics of the given idle state.  That information is exposed by the kernel
+via ``sysfs``.
+
+For each CPU in the system, there is a :file:`/sys/devices/system/cpu/cpu<N>/cpuidle/`
+directory in ``sysfs``, where the number ``<N>`` is assigned to the given
+CPU at the initialization time.  That directory contains a set of subdirectories
+called :file:`state0`, :file:`state1` and so on, up to the number of idle state
+objects defined for the given CPU minus one.  Each of these directories
+corresponds to one idle state object and the larger the number in its name, the
+deeper the (effective) idle state represented by it.  Each of them contains
+a number of files (attributes) representing the properties of the idle state
+object corresponding to it, as follows:
+
+``above``
+	Total number of times this idle state had been asked for, but the
+	observed idle duration was certainly too short to match its target
+	residency.
+
+``below``
+	Total number of times this idle state had been asked for, but certainly
+	a deeper idle state would have been a better match for the observed idle
+	duration.
+
+``desc``
+	Description of the idle state.
+
+``disable``
+	Whether or not this idle state is disabled.
+
+``default_status``
+	The default status of this state, "enabled" or "disabled".
+
+``latency``
+	Exit latency of the idle state in microseconds.
+
+``name``
+	Name of the idle state.
+
+``power``
+	Power drawn by hardware in this idle state in milliwatts (if specified,
+	0 otherwise).
+
+``residency``
+	Target residency of the idle state in microseconds.
+
+``time``
+	Total time spent in this idle state by the given CPU (as measured by the
+	kernel) in microseconds.
+
+``usage``
+	Total number of times the hardware has been asked by the given CPU to
+	enter this idle state.
+
+``rejected``
+	Total number of times a request to enter this idle state on the given
+	CPU was rejected.
+
+The :file:`desc` and :file:`name` files both contain strings.  The difference
+between them is that the name is expected to be more concise, while the
+description may be longer and it may contain white space or special characters.
+The other files listed above contain integer numbers.
+
+The :file:`disable` attribute is the only writeable one.  If it contains 1, the
+given idle state is disabled for this particular CPU, which means that the
+governor will never select it for this particular CPU and the ``CPUIdle``
+driver will never ask the hardware to enter it for that CPU as a result.
+However, disabling an idle state for one CPU does not prevent it from being
+asked for by the other CPUs, so it must be disabled for all of them in order to
+never be asked for by any of them.  [Note that, due to the way the ``ladder``
+governor is implemented, disabling an idle state prevents that governor from
+selecting any idle states deeper than the disabled one too.]
+
+If the :file:`disable` attribute contains 0, the given idle state is enabled for
+this particular CPU, but it still may be disabled for some or all of the other
+CPUs in the system at the same time.  Writing 1 to it causes the idle state to
+be disabled for this particular CPU and writing 0 to it allows the governor to
+take it into consideration for the given CPU and the driver to ask for it,
+unless that state was disabled globally in the driver (in which case it cannot
+be used at all).
+
+The :file:`power` attribute is not defined very well, especially for idle state
+objects representing combinations of idle states at different levels of the
+hierarchy of units in the processor, and it generally is hard to obtain idle
+state power numbers for complex hardware, so :file:`power` often contains 0 (not
+available) and if it contains a nonzero number, that number may not be very
+accurate and it should not be relied on for anything meaningful.
+
+The number in the :file:`time` file generally may be greater than the total time
+really spent by the given CPU in the given idle state, because it is measured by
+the kernel and it may not cover the cases in which the hardware refused to enter
+this idle state and entered a shallower one instead of it (or even it did not
+enter any idle state at all).  The kernel can only measure the time span between
+asking the hardware to enter an idle state and the subsequent wakeup of the CPU
+and it cannot say what really happened in the meantime at the hardware level.
+Moreover, if the idle state object in question represents a combination of idle
+states at different levels of the hierarchy of units in the processor,
+the kernel can never say how deep the hardware went down the hierarchy in any
+particular case.  For these reasons, the only reliable way to find out how
+much time has been spent by the hardware in different idle states supported by
+it is to use idle state residency counters in the hardware, if available.
+
+Generally, an interrupt received when trying to enter an idle state causes the
+idle state entry request to be rejected, in which case the ``CPUIdle`` driver
+may return an error code to indicate that this was the case. The :file:`usage`
+and :file:`rejected` files report the number of times the given idle state
+was entered successfully or rejected, respectively.
+
+.. _cpu-pm-qos:
+
+Power Management Quality of Service for CPUs
+============================================
+
+The power management quality of service (PM QoS) framework in the Linux kernel
+allows kernel code and user space processes to set constraints on various
+energy-efficiency features of the kernel to prevent performance from dropping
+below a required level.
+
+CPU idle time management can be affected by PM QoS in two ways, through the
+global CPU latency limit and through the resume latency constraints for
+individual CPUs.  Kernel code (e.g. device drivers) can set both of them with
+the help of special internal interfaces provided by the PM QoS framework.  User
+space can modify the former by opening the :file:`cpu_dma_latency` special
+device file under :file:`/dev/` and writing a binary value (interpreted as a
+signed 32-bit integer) to it.  In turn, the resume latency constraint for a CPU
+can be modified from user space by writing a string (representing a signed
+32-bit integer) to the :file:`power/pm_qos_resume_latency_us` file under
+:file:`/sys/devices/system/cpu/cpu<N>/` in ``sysfs``, where the CPU number
+``<N>`` is allocated at the system initialization time.  Negative values
+will be rejected in both cases and, also in both cases, the written integer
+number will be interpreted as a requested PM QoS constraint in microseconds.
+
+The requested value is not automatically applied as a new constraint, however,
+as it may be less restrictive (greater in this particular case) than another
+constraint previously requested by someone else.  For this reason, the PM QoS
+framework maintains a list of requests that have been made so far for the
+global CPU latency limit and for each individual CPU, aggregates them and
+applies the effective (minimum in this particular case) value as the new
+constraint.
+
+In fact, opening the :file:`cpu_dma_latency` special device file causes a new
+PM QoS request to be created and added to a global priority list of CPU latency
+limit requests and the file descriptor coming from the "open" operation
+represents that request.  If that file descriptor is then used for writing, the
+number written to it will be associated with the PM QoS request represented by
+it as a new requested limit value.  Next, the priority list mechanism will be
+used to determine the new effective value of the entire list of requests and
+that effective value will be set as a new CPU latency limit.  Thus requesting a
+new limit value will only change the real limit if the effective "list" value is
+affected by it, which is the case if it is the minimum of the requested values
+in the list.
+
+The process holding a file descriptor obtained by opening the
+:file:`cpu_dma_latency` special device file controls the PM QoS request
+associated with that file descriptor, but it controls this particular PM QoS
+request only.
+
+Closing the :file:`cpu_dma_latency` special device file or, more precisely, the
+file descriptor obtained while opening it, causes the PM QoS request associated
+with that file descriptor to be removed from the global priority list of CPU
+latency limit requests and destroyed.  If that happens, the priority list
+mechanism will be used again, to determine the new effective value for the whole
+list and that value will become the new limit.
+
+In turn, for each CPU there is one resume latency PM QoS request associated with
+the :file:`power/pm_qos_resume_latency_us` file under
+:file:`/sys/devices/system/cpu/cpu<N>/` in ``sysfs`` and writing to it causes
+this single PM QoS request to be updated regardless of which user space
+process does that.  In other words, this PM QoS request is shared by the entire
+user space, so access to the file associated with it needs to be arbitrated
+to avoid confusion.  [Arguably, the only legitimate use of this mechanism in
+practice is to pin a process to the CPU in question and let it use the
+``sysfs`` interface to control the resume latency constraint for it.]  It is
+still only a request, however.  It is an entry in a priority list used to
+determine the effective value to be set as the resume latency constraint for the
+CPU in question every time the list of requests is updated this way or another
+(there may be other requests coming from kernel code in that list).
+
+CPU idle time governors are expected to regard the minimum of the global
+(effective) CPU latency limit and the effective resume latency constraint for
+the given CPU as the upper limit for the exit latency of the idle states that
+they are allowed to select for that CPU.  They should never select any idle
+states with exit latency beyond that limit.
+
+While the above CPU QoS constraints apply to CPU idle time management, user
+space may also request a CPU system wakeup latency QoS limit, via the
+`cpu_wakeup_latency` file.  This QoS constraint is respected when selecting a
+suitable idle state for the CPUs, while entering the system-wide suspend-to-idle
+sleep state, but also to the regular CPU idle time management.
+
+Note that, the management of the `cpu_wakeup_latency` file works according to
+the 'cpu_dma_latency' file from user space point of view.  Moreover, the unit
+is also microseconds.
+
+Idle States Control Via Kernel Command Line
+===========================================
+
+In addition to the ``sysfs`` interface allowing individual idle states to be
+`disabled for individual CPUs <idle-states-representation_>`_, there are kernel
+command line parameters affecting CPU idle time management.
+
+The ``cpuidle.off=1`` kernel command line option can be used to disable the
+CPU idle time management entirely.  It does not prevent the idle loop from
+running on idle CPUs, but it prevents the CPU idle time governors and drivers
+from being invoked.  If it is added to the kernel command line, the idle loop
+will ask the hardware to enter idle states on idle CPUs via the CPU architecture
+support code that is expected to provide a default mechanism for this purpose.
+That default mechanism usually is the least common denominator for all of the
+processors implementing the architecture (i.e. CPU instruction set) in question,
+however, so it is rather crude and not very energy-efficient.  For this reason,
+it is not recommended for production use.
+
+The ``cpuidle.governor=`` kernel command line switch allows the ``CPUIdle``
+governor to use to be specified.  It has to be appended with a string matching
+the name of an available governor (e.g. ``cpuidle.governor=menu``) and that
+governor will be used instead of the default one.  It is possible to force
+the ``menu`` governor to be used on the systems that use the ``ladder`` governor
+by default this way, for example.
+
+The other kernel command line parameters controlling CPU idle time management
+described below are only relevant for the *x86* architecture and references
+to ``intel_idle`` affect Intel processors only.
+
+The *x86* architecture support code recognizes three kernel command line
+options related to CPU idle time management: ``idle=poll``, ``idle=halt``,
+and ``idle=nomwait``.  The first two of them disable the ``acpi_idle`` and
+``intel_idle`` drivers altogether, which effectively causes the entire
+``CPUIdle`` subsystem to be disabled and makes the idle loop invoke the
+architecture support code to deal with idle CPUs.  How it does that depends on
+which of the two parameters is added to the kernel command line.  In the
+``idle=halt`` case, the architecture support code will use the ``HLT``
+instruction of the CPUs (which, as a rule, suspends the execution of the program
+and causes the hardware to attempt to enter the shallowest available idle state)
+for this purpose, and if ``idle=poll`` is used, idle CPUs will execute a
+more or less "lightweight" sequence of instructions in a tight loop.  [Note
+that using ``idle=poll`` is somewhat drastic in many cases, as preventing idle
+CPUs from saving almost any energy at all may not be the only effect of it.
+For example, on Intel hardware it effectively prevents CPUs from using
+P-states (see |cpufreq|) that require any number of CPUs in a package to be
+idle, so it very well may hurt single-thread computations performance as well as
+energy-efficiency.  Thus using it for performance reasons may not be a good idea
+at all.]
+
+The ``idle=nomwait`` option prevents the use of ``MWAIT`` instruction of
+the CPU to enter idle states. When this option is used, the ``acpi_idle``
+driver will use the ``HLT`` instruction instead of ``MWAIT``. On systems
+running Intel processors, this option disables the ``intel_idle`` driver
+and forces the use of the ``acpi_idle`` driver instead. Note that in either
+case, ``acpi_idle`` driver will function only if all the information needed
+by it is in the system's ACPI tables.
+
+In addition to the architecture-level kernel command line options affecting CPU
+idle time management, there are parameters affecting individual ``CPUIdle``
+drivers that can be passed to them via the kernel command line.  Specifically,
+the ``intel_idle.max_cstate=<n>`` and ``processor.max_cstate=<n>`` parameters,
+where ``<n>`` is an idle state index also used in the name of the given
+state's directory in ``sysfs`` (see
+`Representation of Idle States <idle-states-representation_>`_), causes the
+``intel_idle`` and ``acpi_idle`` drivers, respectively, to discard all of the
+idle states deeper than idle state ``<n>``.  In that case, they will never ask
+for any of those idle states or expose them to the governor.  [The behavior of
+the two drivers is different for ``<n>`` equal to ``0``.  Adding
+``intel_idle.max_cstate=0`` to the kernel command line disables the
+``intel_idle`` driver and allows ``acpi_idle`` to be used, whereas
+``processor.max_cstate=0`` is equivalent to ``processor.max_cstate=1``.
+Also, the ``acpi_idle`` driver is part of the ``processor`` kernel module that
+can be loaded separately and ``max_cstate=<n>`` can be passed to it as a module
+parameter when it is loaded.]
diff --git a/Documentation/admin-guide/pm/index.rst b/Documentation/admin-guide/pm/index.rst
new file mode 100644
index 000000000..39f8f9f81
--- /dev/null
+++ b/Documentation/admin-guide/pm/index.rst
@@ -0,0 +1,12 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+Power Management
+================
+
+.. toctree::
+   :maxdepth: 2
+
+   strategies
+   system-wide
+   working-state
diff --git a/Documentation/admin-guide/pm/intel-speed-select.rst b/Documentation/admin-guide/pm/intel-speed-select.rst
new file mode 100644
index 000000000..dec2a25f1
--- /dev/null
+++ b/Documentation/admin-guide/pm/intel-speed-select.rst
@@ -0,0 +1,939 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================================================
+Intel(R) Speed Select Technology User Guide
+============================================================
+
+The Intel(R) Speed Select Technology (Intel(R) SST) provides a powerful new
+collection of features that give more granular control over CPU performance.
+With Intel(R) SST, one server can be configured for power and performance for a
+variety of diverse workload requirements.
+
+Refer to the links below for an overview of the technology:
+
+- https://www.intel.com/content/www/us/en/architecture-and-technology/speed-select-technology-article.html
+- https://builders.intel.com/docs/networkbuilders/intel-speed-select-technology-base-frequency-enhancing-performance.pdf
+
+These capabilities are further enhanced in some of the newer generations of
+server platforms where these features can be enumerated and controlled
+dynamically without pre-configuring via BIOS setup options. This dynamic
+configuration is done via mailbox commands to the hardware. One way to enumerate
+and configure these features is by using the Intel Speed Select utility.
+
+This document explains how to use the Intel Speed Select tool to enumerate and
+control Intel(R) SST features. This document gives example commands and explains
+how these commands change the power and performance profile of the system under
+test. Using this tool as an example, customers can replicate the messaging
+implemented in the tool in their production software.
+
+intel-speed-select configuration tool
+======================================
+
+Most Linux distribution packages may include the "intel-speed-select" tool. If not,
+it can be built by downloading the Linux kernel tree from kernel.org. Once
+downloaded, the tool can be built without building the full kernel.
+
+From the kernel tree, run the following commands::
+
+# cd tools/power/x86/intel-speed-select/
+# make
+# make install
+
+Getting Help
+------------
+
+To get help with the tool, execute the command below::
+
+# intel-speed-select --help
+
+The top-level help describes arguments and features. Notice that there is a
+multi-level help structure in the tool. For example, to get help for the feature "perf-profile"::
+
+# intel-speed-select perf-profile --help
+
+To get help on a command, another level of help is provided. For example for the command info "info"::
+
+# intel-speed-select perf-profile info --help
+
+Summary of platform capability
+------------------------------
+To check the current platform and driver capabilities, execute::
+
+#intel-speed-select --info
+
+For example on a test system::
+
+ # intel-speed-select --info
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ Platform: API version : 1
+ Platform: Driver version : 1
+ Platform: mbox supported : 1
+ Platform: mmio supported : 1
+ Intel(R) SST-PP (feature perf-profile) is supported
+ TDP level change control is unlocked, max level: 4
+ Intel(R) SST-TF (feature turbo-freq) is supported
+ Intel(R) SST-BF (feature base-freq) is not supported
+ Intel(R) SST-CP (feature core-power) is supported
+
+Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP)
+------------------------------------------------------------------------
+
+This feature allows configuration of a server dynamically based on workload
+performance requirements. This helps users during deployment as they do not have
+to choose a specific server configuration statically.  This Intel(R) Speed Select
+Technology - Performance Profile (Intel(R) SST-PP) feature introduces a mechanism
+that allows multiple optimized performance profiles per system. Each profile
+defines a set of CPUs that need to be online and rest offline to sustain a
+guaranteed base frequency. Once the user issues a command to use a specific
+performance profile and meet CPU online/offline requirement, the user can expect
+a change in the base frequency dynamically. This feature is called
+"perf-profile" when using the Intel Speed Select tool.
+
+Number or performance levels
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There can be multiple performance profiles on a system. To get the number of
+profiles, execute the command below::
+
+ # intel-speed-select perf-profile get-config-levels
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+        get-config-levels:4
+ package-1
+  die-0
+    cpu-14
+        get-config-levels:4
+
+On this system under test, there are 4 performance profiles in addition to the
+base performance profile (which is performance level 0).
+
+Lock/Unlock status
+~~~~~~~~~~~~~~~~~~
+
+Even if there are multiple performance profiles, it is possible that they
+are locked. If they are locked, users cannot issue a command to change the
+performance state. It is possible that there is a BIOS setup to unlock or check
+with your system vendor.
+
+To check if the system is locked, execute the following command::
+
+ # intel-speed-select perf-profile get-lock-status
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+        get-lock-status:0
+ package-1
+  die-0
+    cpu-14
+        get-lock-status:0
+
+In this case, lock status is 0, which means that the system is unlocked.
+
+Properties of a performance level
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To get properties of a specific performance level (For example for the level 0, below), execute the command below::
+
+ # intel-speed-select perf-profile info -l 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      perf-profile-level-0
+        cpu-count:28
+        enable-cpu-mask:000003ff,f0003fff
+        enable-cpu-list:0,1,2,3,4,5,6,7,8,9,10,11,12,13,28,29,30,31,32,33,34,35,36,37,38,39,40,41
+        thermal-design-power-ratio:26
+        base-frequency(MHz):2600
+        speed-select-turbo-freq:disabled
+        speed-select-base-freq:disabled
+	...
+	...
+
+Here -l option is used to specify a performance level.
+
+If the option -l is omitted, then this command will print information about all
+the performance levels. The above command is printing properties of the
+performance level 0.
+
+For this performance profile, the list of CPUs displayed by the
+"enable-cpu-mask/enable-cpu-list" at the max can be "online." When that
+condition is met, then base frequency of 2600 MHz can be maintained. To
+understand more, execute "intel-speed-select perf-profile info" for performance
+level 4::
+
+ # intel-speed-select perf-profile info -l 4
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      perf-profile-level-4
+        cpu-count:28
+        enable-cpu-mask:000000fa,f0000faf
+        enable-cpu-list:0,1,2,3,5,7,8,9,10,11,28,29,30,31,33,35,36,37,38,39
+        thermal-design-power-ratio:28
+        base-frequency(MHz):2800
+        speed-select-turbo-freq:disabled
+        speed-select-base-freq:unsupported
+	...
+	...
+
+There are fewer CPUs in the "enable-cpu-mask/enable-cpu-list". Consequently, if
+the user only keeps these CPUs online and the rest "offline," then the base
+frequency is increased to 2.8 GHz compared to 2.6 GHz at performance level 0.
+
+Get current performance level
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To get the current performance level, execute::
+
+ # intel-speed-select perf-profile get-config-current-level
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+        get-config-current_level:0
+
+First verify that the base_frequency displayed by the cpufreq sysfs is correct::
+
+ # cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency
+ 2600000
+
+This matches the base-frequency (MHz) field value displayed from the
+"perf-profile info" command for performance level 0(cpufreq frequency is in
+KHz).
+
+To check if the average frequency is equal to the base frequency for a 100% busy
+workload, disable turbo::
+
+# echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
+
+Then runs a busy workload on all CPUs, for example::
+
+#stress -c 64
+
+To verify the base frequency, run turbostat::
+
+ #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
+
+  Package	Core	CPU	Bzy_MHz
+		-	-	2600
+  0		0	0	2600
+  0		1	1	2600
+  0		2	2	2600
+  0		3	3	2600
+  0		4	4	2600
+  .		.	.	.
+
+
+Changing performance level
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To the change the performance level to 4, execute::
+
+ # intel-speed-select -d perf-profile set-config-level -l 4 -o
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      perf-profile
+        set_tdp_level:success
+
+In the command above, "-o" is optional. If it is specified, then it will also
+offline CPUs which are not present in the enable_cpu_mask for this performance
+level.
+
+Now if the base_frequency is checked::
+
+ #cat /sys/devices/system/cpu/cpu0/cpufreq/base_frequency
+ 2800000
+
+Which shows that the base frequency now increased from 2600 MHz at performance
+level 0 to 2800 MHz at performance level 4. As a result, any workload, which can
+use fewer CPUs, can see a boost of 200 MHz compared to performance level 0.
+
+Changing performance level via BMC Interface
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It is possible to change SST-PP level using out of band (OOB) agent (Via some
+remote management console, through BMC "Baseboard Management Controller"
+interface). This mode is supported from the Sapphire Rapids processor
+generation. The kernel and tool change to support this mode is added to Linux
+kernel version 5.18. To enable this feature, kernel config
+"CONFIG_INTEL_HFI_THERMAL" is required. The minimum version of the tool
+is "v1.12" to support this feature, which is part of Linux kernel version 5.18.
+
+To support such configuration, this tool can be used as a daemon. Add
+a command line option --oob::
+
+ # intel-speed-select --oob
+ Intel(R) Speed Select Technology
+ Executing on CPU model:143[0x8f]
+ OOB mode is enabled and will run as daemon
+
+In this mode the tool will online/offline CPUs based on the new performance
+level.
+
+Check presence of other Intel(R) SST features
+---------------------------------------------
+
+Each of the performance profiles also specifies whether there is support of
+other two Intel(R) SST features (Intel(R) Speed Select Technology - Base Frequency
+(Intel(R) SST-BF) and Intel(R) Speed Select Technology - Turbo Frequency (Intel
+SST-TF)).
+
+For example, from the output of "perf-profile info" above, for level 0 and level
+4:
+
+For level 0::
+       speed-select-turbo-freq:disabled
+       speed-select-base-freq:disabled
+
+For level 4::
+       speed-select-turbo-freq:disabled
+       speed-select-base-freq:unsupported
+
+Given these results, the "speed-select-base-freq" (Intel(R) SST-BF) in level 4
+changed from "disabled" to "unsupported" compared to performance level 0.
+
+This means that at performance level 4, the "speed-select-base-freq" feature is
+not supported. However, at performance level 0, this feature is "supported", but
+currently "disabled", meaning the user has not activated this feature. Whereas
+"speed-select-turbo-freq" (Intel(R) SST-TF) is supported at both performance
+levels, but currently not activated by the user.
+
+The Intel(R) SST-BF and the Intel(R) SST-TF features are built on a foundation
+technology called Intel(R) Speed Select Technology - Core Power (Intel(R) SST-CP).
+The platform firmware enables this feature when Intel(R) SST-BF or Intel(R) SST-TF
+is supported on a platform.
+
+Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP)
+---------------------------------------------------------------
+
+Intel(R) Speed Select Technology Core Power (Intel(R) SST-CP) is an interface that
+allows users to define per core priority. This defines a mechanism to distribute
+power among cores when there is a power constrained scenario. This defines a
+class of service (CLOS) configuration.
+
+The user can configure up to 4 class of service configurations. Each CLOS group
+configuration allows definitions of parameters, which affects how the frequency
+can be limited and power is distributed. Each CPU core can be tied to a class of
+service and hence an associated priority. The granularity is at core level not
+at per CPU level.
+
+Enable CLOS based prioritization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To use CLOS based prioritization feature, firmware must be informed to enable
+and use a priority type. There is a default per platform priority type, which
+can be changed with optional command line parameter.
+
+To enable and check the options, execute::
+
+ # intel-speed-select core-power enable --help
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ Enable core-power for a package/die
+	Clos Enable: Specify priority type with [--priority|-p]
+		 0: Proportional, 1: Ordered
+
+There are two types of priority types:
+
+- Ordered
+
+Priority for ordered throttling is defined based on the index of the assigned
+CLOS group. Where CLOS0 gets highest priority (throttled last).
+
+Priority order is:
+CLOS0 > CLOS1 > CLOS2 > CLOS3.
+
+- Proportional
+
+When proportional priority is used, there is an additional parameter called
+frequency_weight, which can be specified per CLOS group. The goal of
+proportional priority is to provide each core with the requested min., then
+distribute all remaining (excess/deficit) budgets in proportion to a defined
+weight. This proportional priority can be configured using "core-power config"
+command.
+
+To enable with the platform default priority type, execute::
+
+ # intel-speed-select core-power enable
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      core-power
+        enable:success
+ package-1
+  die-0
+    cpu-6
+      core-power
+        enable:success
+
+The scope of this enable is per package or die scoped when a package contains
+multiple dies. To check if CLOS is enabled and get priority type, "core-power
+info" command can be used. For example to check the status of core-power feature
+on CPU 0, execute::
+
+ # intel-speed-select -c 0 core-power info
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      core-power
+        support-status:supported
+        enable-status:enabled
+        clos-enable-status:enabled
+        priority-type:proportional
+ package-1
+  die-0
+    cpu-24
+      core-power
+        support-status:supported
+        enable-status:enabled
+        clos-enable-status:enabled
+        priority-type:proportional
+
+Configuring CLOS groups
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Each CLOS group has its own attributes including min, max, freq_weight and
+desired. These parameters can be configured with "core-power config" command.
+Defaults will be used if user skips setting a parameter except clos id, which is
+mandatory. To check core-power config options, execute::
+
+ # intel-speed-select core-power config --help
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ Set core-power configuration for one of the four clos ids
+	Specify targeted clos id with [--clos|-c]
+	Specify clos Proportional Priority [--weight|-w]
+	Specify clos min in MHz with [--min|-n]
+	Specify clos max in MHz with [--max|-m]
+
+For example::
+
+ # intel-speed-select core-power config -c 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ clos epp is not specified, default: 0
+ clos frequency weight is not specified, default: 0
+ clos min is not specified, default: 0 MHz
+ clos max is not specified, default: 25500 MHz
+ clos desired is not specified, default: 0
+ package-0
+  die-0
+    cpu-0
+      core-power
+        config:success
+ package-1
+  die-0
+    cpu-6
+      core-power
+        config:success
+
+The user has the option to change defaults. For example, the user can change the
+"min" and set the base frequency to always get guaranteed base frequency.
+
+Get the current CLOS configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To check the current configuration, "core-power get-config" can be used. For
+example, to get the configuration of CLOS 0::
+
+ # intel-speed-select core-power get-config -c 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      core-power
+        clos:0
+        epp:0
+        clos-proportional-priority:0
+        clos-min:0 MHz
+        clos-max:Max Turbo frequency
+        clos-desired:0 MHz
+ package-1
+  die-0
+    cpu-24
+      core-power
+        clos:0
+        epp:0
+        clos-proportional-priority:0
+        clos-min:0 MHz
+        clos-max:Max Turbo frequency
+        clos-desired:0 MHz
+
+Associating a CPU with a CLOS group
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To associate a CPU to a CLOS group "core-power assoc" command can be used::
+
+ # intel-speed-select core-power assoc --help
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ Associate a clos id to a CPU
+	Specify targeted clos id with [--clos|-c]
+
+
+For example to associate CPU 10 to CLOS group 3, execute::
+
+ # intel-speed-select -c 10 core-power assoc -c 3
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-10
+      core-power
+        assoc:success
+
+Once a CPU is associated, its sibling CPUs are also associated to a CLOS group.
+Once associated, avoid changing Linux "cpufreq" subsystem scaling frequency
+limits.
+
+To check the existing association for a CPU, "core-power get-assoc" command can
+be used. For example, to get association of CPU 10, execute::
+
+ # intel-speed-select -c 10 core-power get-assoc
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-1
+  die-0
+    cpu-10
+      get-assoc
+        clos:3
+
+This shows that CPU 10 is part of a CLOS group 3.
+
+
+Disable CLOS based prioritization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To disable, execute::
+
+# intel-speed-select core-power disable
+
+Some features like Intel(R) SST-TF can only be enabled when CLOS based prioritization
+is enabled. For this reason, disabling while Intel(R) SST-TF is enabled can cause
+Intel(R) SST-TF to fail. This will cause the "disable" command to display an error
+if Intel(R) SST-TF is already enabled. In turn, to disable, the Intel(R) SST-TF
+feature must be disabled first.
+
+Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF)
+-------------------------------------------------------------------
+
+The Intel(R) Speed Select Technology - Base Frequency (Intel(R) SST-BF) feature lets
+the user control base frequency. If some critical workload threads demand
+constant high guaranteed performance, then this feature can be used to execute
+the thread at higher base frequency on specific sets of CPUs (high priority
+CPUs) at the cost of lower base frequency (low priority CPUs) on other CPUs.
+This feature does not require offline of the low priority CPUs.
+
+The support of Intel(R) SST-BF depends on the Intel(R) Speed Select Technology -
+Performance Profile (Intel(R) SST-PP) performance level configuration. It is
+possible that only certain performance levels support Intel(R) SST-BF. It is also
+possible that only base performance level (level = 0) has support of Intel
+SST-BF. Consequently, first select the desired performance level to enable this
+feature.
+
+In the system under test here, Intel(R) SST-BF is supported at the base
+performance level 0, but currently disabled. For example for the level 0::
+
+ # intel-speed-select -c 0 perf-profile info -l 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      perf-profile-level-0
+        ...
+
+        speed-select-base-freq:disabled
+	...
+
+Before enabling Intel(R) SST-BF and measuring its impact on a workload
+performance, execute some workload and measure performance and get a baseline
+performance to compare against.
+
+Here the user wants more guaranteed performance. For this reason, it is likely
+that turbo is disabled. To disable turbo, execute::
+
+#echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
+
+Based on the output of the "intel-speed-select perf-profile info -l 0" base
+frequency of guaranteed frequency 2600 MHz.
+
+
+Measure baseline performance for comparison
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To compare, pick a multi-threaded workload where each thread can be scheduled on
+separate CPUs. "Hackbench pipe" test is a good example on how to improve
+performance using Intel(R) SST-BF.
+
+Below, the workload is measuring average scheduler wakeup latency, so a lower
+number means better performance::
+
+ # taskset -c 3,4 perf bench -r 100 sched pipe
+ # Running 'sched/pipe' benchmark:
+ # Executed 1000000 pipe operations between two processes
+     Total time: 6.102 [sec]
+       6.102445 usecs/op
+         163868 ops/sec
+
+While running the above test, if we take turbostat output, it will show us that
+2 of the CPUs are busy and reaching max. frequency (which would be the base
+frequency as the turbo is disabled). The turbostat output::
+
+ #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
+ Package	Core	CPU	Bzy_MHz
+ 0		0	0	1000
+ 0		1	1	1005
+ 0		2	2	1000
+ 0		3	3	2600
+ 0		4	4	2600
+ 0		5	5	1000
+ 0		6	6	1000
+ 0		7	7	1005
+ 0		8	8	1005
+ 0		9	9	1000
+ 0		10	10	1000
+ 0		11	11	995
+ 0		12	12	1000
+ 0		13	13	1000
+
+From the above turbostat output, both CPU 3 and 4 are very busy and reaching
+full guaranteed frequency of 2600 MHz.
+
+Intel(R) SST-BF Capabilities
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To get capabilities of Intel(R) SST-BF for the current performance level 0,
+execute::
+
+ # intel-speed-select base-freq info -l 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      speed-select-base-freq
+        high-priority-base-frequency(MHz):3000
+        high-priority-cpu-mask:00000216,00002160
+        high-priority-cpu-list:5,6,8,13,33,34,36,41
+        low-priority-base-frequency(MHz):2400
+        tjunction-temperature(C):125
+        thermal-design-power(W):205
+
+The above capabilities show that there are some CPUs on this system that can
+offer base frequency of 3000 MHz compared to the standard base frequency at this
+performance levels. Nevertheless, these CPUs are fixed, and they are presented
+via high-priority-cpu-list/high-priority-cpu-mask. But if this Intel(R) SST-BF
+feature is selected, the low priorities CPUs (which are not in
+high-priority-cpu-list) can only offer up to 2400 MHz. As a result, if this
+clipping of low priority CPUs is acceptable, then the user can enable Intel
+SST-BF feature particularly for the above "sched pipe" workload since only two
+CPUs are used, they can be scheduled on high priority CPUs and can get boost of
+400 MHz.
+
+Enable Intel(R) SST-BF
+~~~~~~~~~~~~~~~~~~~~~~
+
+To enable Intel(R) SST-BF feature, execute::
+
+ # intel-speed-select base-freq enable -a
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      base-freq
+        enable:success
+ package-1
+  die-0
+    cpu-14
+      base-freq
+        enable:success
+
+In this case, -a option is optional. This not only enables Intel(R) SST-BF, but it
+also adjusts the priority of cores using Intel(R) Speed Select Technology Core
+Power (Intel(R) SST-CP) features. This option sets the minimum performance of each
+Intel(R) Speed Select Technology - Performance Profile (Intel(R) SST-PP) class to
+maximum performance so that the hardware will give maximum performance possible
+for each CPU.
+
+If -a option is not used, then the following steps are required before enabling
+Intel(R) SST-BF:
+
+- Discover Intel(R) SST-BF and note low and high priority base frequency
+- Note the high priority CPU list
+- Enable CLOS using core-power feature set
+- Configure CLOS parameters. Use CLOS.min to set to minimum performance
+- Subscribe desired CPUs to CLOS groups
+
+With this configuration, if the same workload is executed by pinning the
+workload to high priority CPUs (CPU 5 and 6 in this case)::
+
+ #taskset -c 5,6 perf bench -r 100 sched pipe
+ # Running 'sched/pipe' benchmark:
+ # Executed 1000000 pipe operations between two processes
+     Total time: 5.627 [sec]
+       5.627922 usecs/op
+         177685 ops/sec
+
+This way, by enabling Intel(R) SST-BF, the performance of this benchmark is
+improved (latency reduced) by 7.79%. From the turbostat output, it can be
+observed that the high priority CPUs reached 3000 MHz compared to 2600 MHz.
+The turbostat output::
+
+ #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
+ Package	Core	CPU	Bzy_MHz
+ 0		0	0	2151
+ 0		1	1	2166
+ 0		2	2	2175
+ 0		3	3	2175
+ 0		4	4	2175
+ 0		5	5	3000
+ 0		6	6	3000
+ 0		7	7	2180
+ 0		8	8	2662
+ 0		9	9	2176
+ 0		10	10	2175
+ 0		11	11	2176
+ 0		12	12	2176
+ 0		13	13	2661
+
+Disable Intel(R) SST-BF
+~~~~~~~~~~~~~~~~~~~~~~~
+
+To disable the Intel(R) SST-BF feature, execute::
+
+# intel-speed-select base-freq disable -a
+
+
+Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF)
+--------------------------------------------------------------------
+
+This feature enables the ability to set different "All core turbo ratio limits"
+to cores based on the priority. By using this feature, some cores can be
+configured to get higher turbo frequency by designating them as high priority at
+the cost of lower or no turbo frequency on the low priority cores.
+
+For this reason, this feature is only useful when system is busy utilizing all
+CPUs, but the user wants some configurable option to get high performance on
+some CPUs.
+
+The support of Intel(R) Speed Select Technology - Turbo Frequency (Intel(R) SST-TF)
+depends on the Intel(R) Speed Select Technology - Performance Profile (Intel
+SST-PP) performance level configuration. It is possible that only a certain
+performance level supports Intel(R) SST-TF. It is also possible that only the base
+performance level (level = 0) has the support of Intel(R) SST-TF. Hence, first
+select the desired performance level to enable this feature.
+
+In the system under test here, Intel(R) SST-TF is supported at the base
+performance level 0, but currently disabled::
+
+ # intel-speed-select -c 0 perf-profile info -l 0
+ Intel(R) Speed Select Technology
+ package-0
+  die-0
+    cpu-0
+      perf-profile-level-0
+        ...
+        ...
+        speed-select-turbo-freq:disabled
+        ...
+        ...
+
+
+To check if performance can be improved using Intel(R) SST-TF feature, get the turbo
+frequency properties with Intel(R) SST-TF enabled and compare to the base turbo
+capability of this system.
+
+Get Base turbo capability
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To get the base turbo capability of performance level 0, execute::
+
+ # intel-speed-select perf-profile info -l 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      perf-profile-level-0
+        ...
+        ...
+        turbo-ratio-limits-sse
+          bucket-0
+            core-count:2
+            max-turbo-frequency(MHz):3200
+          bucket-1
+            core-count:4
+            max-turbo-frequency(MHz):3100
+          bucket-2
+            core-count:6
+            max-turbo-frequency(MHz):3100
+          bucket-3
+            core-count:8
+            max-turbo-frequency(MHz):3100
+          bucket-4
+            core-count:10
+            max-turbo-frequency(MHz):3100
+          bucket-5
+            core-count:12
+            max-turbo-frequency(MHz):3100
+          bucket-6
+            core-count:14
+            max-turbo-frequency(MHz):3100
+          bucket-7
+            core-count:16
+            max-turbo-frequency(MHz):3100
+
+Based on the data above, when all the CPUS are busy, the max. frequency of 3100
+MHz can be achieved. If there is some busy workload on cpu 0 - 11 (e.g. stress)
+and on CPU 12 and 13, execute "hackbench pipe" workload::
+
+ # taskset -c 12,13 perf bench -r 100 sched pipe
+ # Running 'sched/pipe' benchmark:
+ # Executed 1000000 pipe operations between two processes
+     Total time: 5.705 [sec]
+       5.705488 usecs/op
+         175269 ops/sec
+
+The turbostat output::
+
+ #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
+ Package	Core	CPU	Bzy_MHz
+ 0		0	0	3000
+ 0		1	1	3000
+ 0		2	2	3000
+ 0		3	3	3000
+ 0		4	4	3000
+ 0		5	5	3100
+ 0		6	6	3100
+ 0		7	7	3000
+ 0		8	8	3100
+ 0		9	9	3000
+ 0		10	10	3000
+ 0		11	11	3000
+ 0		12	12	3100
+ 0		13	13	3100
+
+Based on turbostat output, the performance is limited by frequency cap of 3100
+MHz. To check if the hackbench performance can be improved for CPU 12 and CPU
+13, first check the capability of the Intel(R) SST-TF feature for this performance
+level.
+
+Get Intel(R) SST-TF Capability
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To get the capability, the "turbo-freq info" command can be used::
+
+ # intel-speed-select turbo-freq info -l 0
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-0
+      speed-select-turbo-freq
+          bucket-0
+            high-priority-cores-count:2
+            high-priority-max-frequency(MHz):3200
+            high-priority-max-avx2-frequency(MHz):3200
+            high-priority-max-avx512-frequency(MHz):3100
+          bucket-1
+            high-priority-cores-count:4
+            high-priority-max-frequency(MHz):3100
+            high-priority-max-avx2-frequency(MHz):3000
+            high-priority-max-avx512-frequency(MHz):2900
+          bucket-2
+            high-priority-cores-count:6
+            high-priority-max-frequency(MHz):3100
+            high-priority-max-avx2-frequency(MHz):3000
+            high-priority-max-avx512-frequency(MHz):2900
+          speed-select-turbo-freq-clip-frequencies
+            low-priority-max-frequency(MHz):2600
+            low-priority-max-avx2-frequency(MHz):2400
+            low-priority-max-avx512-frequency(MHz):2100
+
+Based on the output above, there is an Intel(R) SST-TF bucket for which there are
+two high priority cores. If only two high priority cores are set, then max.
+turbo frequency on those cores can be increased to 3200 MHz. This is 100 MHz
+more than the base turbo capability for all cores.
+
+In turn, for the hackbench workload, two CPUs can be set as high priority and
+rest as low priority. One side effect is that once enabled, the low priority
+cores will be clipped to a lower frequency of 2600 MHz.
+
+Enable Intel(R) SST-TF
+~~~~~~~~~~~~~~~~~~~~~~
+
+To enable Intel(R) SST-TF, execute::
+
+ # intel-speed-select -c 12,13 turbo-freq enable -a
+ Intel(R) Speed Select Technology
+ Executing on CPU model: X
+ package-0
+  die-0
+    cpu-12
+      turbo-freq
+        enable:success
+ package-0
+  die-0
+    cpu-13
+      turbo-freq
+        enable:success
+ package--1
+  die-0
+    cpu-63
+      turbo-freq --auto
+        enable:success
+
+In this case, the option "-a" is optional. If set, it enables Intel(R) SST-TF
+feature and also sets the CPUs to high and low priority using Intel Speed
+Select Technology Core Power (Intel(R) SST-CP) features. The CPU numbers passed
+with "-c" arguments are marked as high priority, including its siblings.
+
+If -a option is not used, then the following steps are required before enabling
+Intel(R) SST-TF:
+
+- Discover Intel(R) SST-TF and note buckets of high priority cores and maximum frequency
+
+- Enable CLOS using core-power feature set - Configure CLOS parameters
+
+- Subscribe desired CPUs to CLOS groups making sure that high priority cores are set to the maximum frequency
+
+If the same hackbench workload is executed, schedule hackbench threads on high
+priority CPUs::
+
+ #taskset -c 12,13 perf bench -r 100 sched pipe
+ # Running 'sched/pipe' benchmark:
+ # Executed 1000000 pipe operations between two processes
+     Total time: 5.510 [sec]
+       5.510165 usecs/op
+         180826 ops/sec
+
+This improved performance by around 3.3% improvement on a busy system. Here the
+turbostat output will show that the CPU 12 and CPU 13 are getting 100 MHz boost.
+The turbostat output::
+
+ #turbostat -c 0-13 --show Package,Core,CPU,Bzy_MHz -i 1
+ Package	Core	CPU	Bzy_MHz
+ ...
+ 0		12	12	3200
+ 0		13	13	3200
diff --git a/Documentation/admin-guide/pm/intel_epb.rst b/Documentation/admin-guide/pm/intel_epb.rst
new file mode 100644
index 000000000..005121167
--- /dev/null
+++ b/Documentation/admin-guide/pm/intel_epb.rst
@@ -0,0 +1,41 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+======================================
+Intel Performance and Energy Bias Hint
+======================================
+
+:Copyright: |copy| 2019 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+.. kernel-doc:: arch/x86/kernel/cpu/intel_epb.c
+   :doc: overview
+
+Intel Performance and Energy Bias Attribute in ``sysfs``
+========================================================
+
+The Intel Performance and Energy Bias Hint (EPB) value for a given (logical) CPU
+can be checked or updated through a ``sysfs`` attribute (file) under
+:file:`/sys/devices/system/cpu/cpu<N>/power/`, where the CPU number ``<N>``
+is allocated at the system initialization time:
+
+``energy_perf_bias``
+	Shows the current EPB value for the CPU in a sliding scale 0 - 15, where
+	a value of 0 corresponds to a hint preference for highest performance
+	and a value of 15 corresponds to the maximum energy savings.
+
+	In order to update the EPB value for the CPU, this attribute can be
+	written to, either with a number in the 0 - 15 sliding scale above, or
+	with one of the strings: "performance", "balance-performance", "normal",
+	"balance-power", "power" that represent values reflected by their
+	meaning.
+
+	This attribute is present for all online CPUs supporting the EPB
+	feature.
+
+Note that while the EPB interface to the processor is defined at the logical CPU
+level, the physical register backing it may be shared by multiple CPUs (for
+example, SMT siblings or cores in one package).  For this reason, updating the
+EPB value for one CPU may cause the EPB values for other CPUs to change.
diff --git a/Documentation/admin-guide/pm/intel_idle.rst b/Documentation/admin-guide/pm/intel_idle.rst
new file mode 100644
index 000000000..996e5bd83
--- /dev/null
+++ b/Documentation/admin-guide/pm/intel_idle.rst
@@ -0,0 +1,335 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+==============================================
+``intel_idle`` CPU Idle Time Management Driver
+==============================================
+
+:Copyright: |copy| 2020 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+General Information
+===================
+
+``intel_idle`` is a part of the
+:doc:`CPU idle time management subsystem <cpuidle>` in the Linux kernel
+(``CPUIdle``).  It is the default CPU idle time management driver for the
+Nehalem and later generations of Intel processors, but the level of support for
+a particular processor model in it depends on whether or not it recognizes that
+processor model and may also depend on information coming from the platform
+firmware.  [To understand ``intel_idle`` it is necessary to know how ``CPUIdle``
+works in general, so this is the time to get familiar with
+Documentation/admin-guide/pm/cpuidle.rst if you have not done that yet.]
+
+``intel_idle`` uses the ``MWAIT`` instruction to inform the processor that the
+logical CPU executing it is idle and so it may be possible to put some of the
+processor's functional blocks into low-power states.  That instruction takes two
+arguments (passed in the ``EAX`` and ``ECX`` registers of the target CPU), the
+first of which, referred to as a *hint*, can be used by the processor to
+determine what can be done (for details refer to Intel Software Developer’s
+Manual [1]_).  Accordingly, ``intel_idle`` refuses to work with processors in
+which the support for the ``MWAIT`` instruction has been disabled (for example,
+via the platform firmware configuration menu) or which do not support that
+instruction at all.
+
+``intel_idle`` is not modular, so it cannot be unloaded, which means that the
+only way to pass early-configuration-time parameters to it is via the kernel
+command line.
+
+Sysfs Interface
+===============
+
+The ``intel_idle`` driver exposes the following ``sysfs`` attributes in
+``/sys/devices/system/cpu/cpuidle/``:
+
+``intel_c1_demotion``
+	Enable or disable C1 demotion for all CPUs in the system. This file is
+	only exposed on platforms that support the C1 demotion feature and where
+	it was tested. Value 0 means that C1 demotion is disabled, value 1 means
+	that it is enabled. Write 0 or 1 to disable or enable C1 demotion for
+	all CPUs.
+
+	The C1 demotion feature involves the platform firmware demoting deep
+	C-state requests from the OS (e.g., C6 requests) to C1. The idea is that
+	firmware monitors CPU wake-up rate, and if it is higher than a
+	platform-specific threshold, the firmware demotes deep C-state requests
+	to C1. For example, Linux requests C6, but firmware noticed too many
+	wake-ups per second, and it keeps the CPU in C1. When the CPU stays in
+	C1 long enough, the platform promotes it back to C6. This may improve
+	some workloads' performance, but it may also increase power consumption.
+
+.. _intel-idle-enumeration-of-states:
+
+Enumeration of Idle States
+==========================
+
+Each ``MWAIT`` hint value is interpreted by the processor as a license to
+reconfigure itself in a certain way in order to save energy.  The processor
+configurations (with reduced power draw) resulting from that are referred to
+as C-states (in the ACPI terminology) or idle states.  The list of meaningful
+``MWAIT`` hint values and idle states (i.e. low-power configurations of the
+processor) corresponding to them depends on the processor model and it may also
+depend on the configuration of the platform.
+
+In order to create a list of available idle states required by the ``CPUIdle``
+subsystem (see :ref:`idle-states-representation` in
+Documentation/admin-guide/pm/cpuidle.rst),
+``intel_idle`` can use two sources of information: static tables of idle states
+for different processor models included in the driver itself and the ACPI tables
+of the system.  The former are always used if the processor model at hand is
+recognized by ``intel_idle`` and the latter are used if that is required for
+the given processor model (which is the case for all server processor models
+recognized by ``intel_idle``) or if the processor model is not recognized.
+[There is a module parameter that can be used to make the driver use the ACPI
+tables with any processor model recognized by it; see
+`below <intel-idle-parameters_>`_.]
+
+If the ACPI tables are going to be used for building the list of available idle
+states, ``intel_idle`` will be looking for ``_LPI`` or ``_CST`` objects in them
+(refer to the ACPI specification [2]_ for the definitions of the ``_LPI`` and
+``_CST`` objects).  If ``_LPI`` is present under at least one of the ACPI
+objects representing the CPUs in the system and ``_LPI`` processing produces a
+non-empty list of valid idle states, it will be used.  Otherwise, ``_CST`` will
+be used so long as it is present under at least one of the ACPI objects
+representing the CPUs in the system and it returns a non-empty list of valid
+idle states.  In either case, since the ``CPUIdle`` subsystem expects that the
+list of idle states supplied by the driver will be suitable for all of the CPUs
+handled by it and ``intel_idle`` is registered as the ``CPUIdle`` driver for all
+of the CPUs in the system, ``intel_idle`` looks for the first CPU where the
+ACPI-supplied list of idle states (coming from either ``_LPI`` or ``_CST``)
+is not empty.  Moreover, all of the states in that list need to be of the FFH
+(Functional Fixed Hardware) type, which means that the ``MWAIT`` instruction is
+expected to be used to tell the processor that the given idle state may be
+entered.  If that expectation is met, the list of idle states is assumed to be
+applicable to all of the other CPUs in the system and the idle state
+descriptions extracted from it are stored in a preliminary list of idle states
+coming from the ACPI tables.  [This step is skipped if ``intel_idle`` is
+configured to ignore the ACPI tables; see `below <intel-idle-parameters_>`_.]
+
+Next, the first (index 0) entry in the list of available idle states is
+initialized to represent a "polling idle state" (a pseudo-idle state in which
+the target CPU continuously fetches and executes instructions), and the
+subsequent (real) idle state entries are populated as follows.
+
+If the processor model at hand is recognized by ``intel_idle``, there is a
+(static) table of idle state descriptions for it in the driver.  In that case,
+the "internal" table is the primary source of information on idle states and the
+information from it is copied to the final list of available idle states.  If
+using the ACPI tables for the enumeration of idle states is not required
+(depending on the processor model), all of the listed idle state are enabled by
+default (so all of them will be taken into consideration by ``CPUIdle``
+governors during CPU idle state selection).  Otherwise, some of the listed idle
+states may not be enabled by default if there are no matching entries in the
+preliminary list of idle states coming from the ACPI tables.  In that case user
+space still can enable them later (on a per-CPU basis) with the help of
+the ``disable`` idle state attribute in ``sysfs`` (see
+:ref:`idle-states-representation` in
+Documentation/admin-guide/pm/cpuidle.rst).  This basically means that
+the idle states "known" to the driver may not be enabled by default if they have
+not been exposed by the platform firmware (through the ACPI tables).
+
+If the given processor model is not recognized by ``intel_idle``, but it
+supports ``MWAIT``, the preliminary list of idle states coming from the ACPI
+tables is used for building the final list that will be supplied to the
+``CPUIdle`` core during driver registration.  For each idle state in that list,
+the description, ``MWAIT`` hint and exit (wake) latency are copied to the
+corresponding entry in the final list of idle states.  If the preliminary list
+of idle states has been obtained through ``_LPI`` processing, the minimum
+residency parameter of the given idle state is taken as its target residency.
+Otherwise, for C1-type idle states, the exit latency value is also used as the
+target residency (for compatibility with the majority of the "internal" tables
+of idle states for various processor models recognized by ``intel_idle``), and
+for the other idle state types (C2 and C3) the target residency value is 3 times
+the exit latency (again, that is because it reflects the target residency to
+exit latency ratio in the majority of cases for the processor models recognized
+by ``intel_idle``).  The name of the idle state (to be returned by the ``name``
+idle state attribute in ``sysfs``) is either "Cx_LPI" (if it comes from ``_LPI``
+processing) or "Cx_ACPI", where x is the index of that idle state in the final
+list (note that the minimum value of x is 1, because 0 is reserved for the
+"polling" state), and its target residency is based on the exit latency value.
+All of the idle states in the final list are enabled by default in this case.
+
+
+.. _intel-idle-initialization:
+
+Initialization
+==============
+
+The initialization of ``intel_idle`` starts with checking if the kernel command
+line options forbid the use of the ``MWAIT`` instruction.  If that is the case,
+an error code is returned right away.
+
+The next step is to check whether or not the processor model is known to the
+driver, which determines the idle states enumeration method (see
+`above <intel-idle-enumeration-of-states_>`_), and whether or not the processor
+supports ``MWAIT`` (the initialization fails if that is not the case).  Then,
+the ``MWAIT`` support in the processor is enumerated through ``CPUID`` and the
+driver initialization fails if the level of support is not as expected (for
+example, if the total number of ``MWAIT`` substates returned is 0).
+
+Next, if the driver is not configured to ignore the ACPI tables (see
+`below <intel-idle-parameters_>`_), the idle states information provided by the
+platform firmware is extracted from them.
+
+Then, ``CPUIdle`` device objects are allocated for all CPUs and the list of
+available idle states is created as explained
+`above <intel-idle-enumeration-of-states_>`_.
+
+Finally, ``intel_idle`` is registered with the help of cpuidle_register_driver()
+as the ``CPUIdle`` driver for all CPUs in the system and a CPU online callback
+for configuring individual CPUs is registered via cpuhp_setup_state(), which
+(among other things) causes the callback routine to be invoked for all of the
+CPUs present in the system at that time (each CPU executes its own instance of
+the callback routine).  That routine registers a ``CPUIdle`` device for the CPU
+running it (which enables the ``CPUIdle`` subsystem to operate that CPU) and
+optionally performs some CPU-specific initialization actions that may be
+required for the given processor model.
+
+
+.. _intel-idle-parameters:
+
+Kernel Command Line Options and Module Parameters
+=================================================
+
+The *x86* architecture support code recognizes three kernel command line
+options related to CPU idle time management: ``idle=poll``, ``idle=halt``,
+and ``idle=nomwait``.  If any of them is present in the kernel command line, the
+``MWAIT`` instruction is not allowed to be used, so the initialization of
+``intel_idle`` will fail.
+
+Apart from that there are five module parameters recognized by ``intel_idle``
+itself that can be set via the kernel command line (they cannot be updated via
+sysfs, so that is the only way to change their values).
+
+The ``max_cstate`` parameter value is the maximum idle state index in the list
+of idle states supplied to the ``CPUIdle`` core during the registration of the
+driver.  It is also the maximum number of regular (non-polling) idle states that
+can be used by ``intel_idle``, so the enumeration of idle states is terminated
+after finding that number of usable idle states (the other idle states that
+potentially might have been used if ``max_cstate`` had been greater are not
+taken into consideration at all).  Setting ``max_cstate`` can prevent
+``intel_idle`` from exposing idle states that are regarded as "too deep" for
+some reason to the ``CPUIdle`` core, but it does so by making them effectively
+invisible until the system is shut down and started again which may not always
+be desirable.  In practice, it is only really necessary to do that if the idle
+states in question cannot be enabled during system startup, because in the
+working state of the system the CPU power management quality of service (PM
+QoS) feature can be used to prevent ``CPUIdle`` from touching those idle states
+even if they have been enumerated (see :ref:`cpu-pm-qos` in
+Documentation/admin-guide/pm/cpuidle.rst).
+Setting ``max_cstate`` to 0 causes the ``intel_idle`` initialization to fail.
+
+The ``no_acpi``, ``use_acpi`` and ``no_native`` module parameters are
+recognized by ``intel_idle`` if the kernel has been configured with ACPI
+support.  In the case that ACPI is not configured these flags have no impact
+on functionality.
+
+``no_acpi`` - Do not use ACPI at all.  Only native mode is available, no
+ACPI mode.
+
+``use_acpi`` - No-op in ACPI mode, the driver will consult ACPI tables for
+C-states on/off status in native mode.
+
+``no_native`` - Work only in ACPI mode, no native mode available (ignore
+all custom tables).
+
+The value of the ``states_off`` module parameter (0 by default) represents a
+list of idle states to be disabled by default in the form of a bitmask.
+
+Namely, the positions of the bits that are set in the ``states_off`` value are
+the indices of idle states to be disabled by default (as reflected by the names
+of the corresponding idle state directories in ``sysfs``, :file:`state0`,
+:file:`state1` ... :file:`state<i>` ..., where ``<i>`` is the index of the given
+idle state; see :ref:`idle-states-representation` in
+Documentation/admin-guide/pm/cpuidle.rst).
+
+For example, if ``states_off`` is equal to 3, the driver will disable idle
+states 0 and 1 by default, and if it is equal to 8, idle state 3 will be
+disabled by default and so on (bit positions beyond the maximum idle state index
+are ignored).
+
+The idle states disabled this way can be enabled (on a per-CPU basis) from user
+space via ``sysfs``.
+
+The ``ibrs_off`` module parameter is a boolean flag (defaults to
+false). If set, it is used to control if IBRS (Indirect Branch Restricted
+Speculation) should be turned off when the CPU enters an idle state.
+This flag does not affect CPUs that use Enhanced IBRS which can remain
+on with little performance impact.
+
+For some CPUs, IBRS will be selected as mitigation for Spectre v2 and Retbleed
+security vulnerabilities by default.  Leaving the IBRS mode on while idling may
+have a performance impact on its sibling CPU.  The IBRS mode will be turned off
+by default when the CPU enters into a deep idle state, but not in some
+shallower ones.  Setting the ``ibrs_off`` module parameter will force the IBRS
+mode to off when the CPU is in any one of the available idle states.  This may
+help performance of a sibling CPU at the expense of a slightly higher wakeup
+latency for the idle CPU.
+
+The ``table`` argument allows customization of idle state latency and target
+residency. The syntax is a comma-separated list of ``name:latency:residency``
+entries, where ``name`` is the idle state name, ``latency`` is the exit latency
+in microseconds, and ``residency`` is the target residency in microseconds. It
+is not necessary to specify all idle states; only those to be customized. For
+example, ``C1:1:3,C6:50:100`` sets the exit latency and target residency for
+C1 and C6 to 1/3 and 50/100 microseconds, respectively. Remaining idle states
+keep their default values. The driver verifies that deeper idle states have
+higher latency and target residency than shallower ones. Also, target
+residency cannot be smaller than exit latency. If any of these conditions is
+not met, the driver ignores the entire ``table`` parameter.
+
+.. _intel-idle-core-and-package-idle-states:
+
+Core and Package Levels of Idle States
+======================================
+
+Typically, in a processor supporting the ``MWAIT`` instruction there are (at
+least) two levels of idle states (or C-states).  One level, referred to as
+"core C-states", covers individual cores in the processor, whereas the other
+level, referred to as "package C-states", covers the entire processor package
+and it may also involve other components of the system (GPUs, memory
+controllers, I/O hubs etc.).
+
+Some of the ``MWAIT`` hint values allow the processor to use core C-states only
+(most importantly, that is the case for the ``MWAIT`` hint value corresponding
+to the ``C1`` idle state), but the majority of them give it a license to put
+the target core (i.e. the core containing the logical CPU executing ``MWAIT``
+with the given hint value) into a specific core C-state and then (if possible)
+to enter a specific package C-state at the deeper level.  For example, the
+``MWAIT`` hint value representing the ``C3`` idle state allows the processor to
+put the target core into the low-power state referred to as "core ``C3``" (or
+``CC3``), which happens if all of the logical CPUs (SMT siblings) in that core
+have executed ``MWAIT`` with the ``C3`` hint value (or with a hint value
+representing a deeper idle state), and in addition to that (in the majority of
+cases) it gives the processor a license to put the entire package (possibly
+including some non-CPU components such as a GPU or a memory controller) into the
+low-power state referred to as "package ``C3``" (or ``PC3``), which happens if
+all of the cores have gone into the ``CC3`` state and (possibly) some additional
+conditions are satisfied (for instance, if the GPU is covered by ``PC3``, it may
+be required to be in a certain GPU-specific low-power state for ``PC3`` to be
+reachable).
+
+As a rule, there is no simple way to make the processor use core C-states only
+if the conditions for entering the corresponding package C-states are met, so
+the logical CPU executing ``MWAIT`` with a hint value that is not core-level
+only (like for ``C1``) must always assume that this may cause the processor to
+enter a package C-state.  [That is why the exit latency and target residency
+values corresponding to the majority of ``MWAIT`` hint values in the "internal"
+tables of idle states in ``intel_idle`` reflect the properties of package
+C-states.]  If using package C-states is not desirable at all, either
+:ref:`PM QoS <cpu-pm-qos>` or the ``max_cstate`` module parameter of
+``intel_idle`` described `above <intel-idle-parameters_>`_ must be used to
+restrict the range of permissible idle states to the ones with core-level only
+``MWAIT`` hint values (like ``C1``).
+
+
+References
+==========
+
+.. [1] *Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 2B*,
+       https://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2b-manual.html
+
+.. [2] *Advanced Configuration and Power Interface (ACPI) Specification*,
+       https://uefi.org/specifications
diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst
new file mode 100644
index 000000000..25fe5d88f
--- /dev/null
+++ b/Documentation/admin-guide/pm/intel_pstate.rst
@@ -0,0 +1,889 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===============================================
+``intel_pstate`` CPU Performance Scaling Driver
+===============================================
+
+:Copyright: |copy| 2017 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+General Information
+===================
+
+``intel_pstate`` is a part of the
+:doc:`CPU performance scaling subsystem <cpufreq>` in the Linux kernel
+(``CPUFreq``).  It is a scaling driver for the Sandy Bridge and later
+generations of Intel processors.  Note, however, that some of those processors
+may not be supported.  [To understand ``intel_pstate`` it is necessary to know
+how ``CPUFreq`` works in general, so this is the time to read
+Documentation/admin-guide/pm/cpufreq.rst if you have not done that yet.]
+
+For the processors supported by ``intel_pstate``, the P-state concept is broader
+than just an operating frequency or an operating performance point (see the
+LinuxCon Europe 2015 presentation by Kristen Accardi [1]_ for more
+information about that).  For this reason, the representation of P-states used
+by ``intel_pstate`` internally follows the hardware specification (for details
+refer to Intel Software Developer’s Manual [2]_).  However, the ``CPUFreq`` core
+uses frequencies for identifying operating performance points of CPUs and
+frequencies are involved in the user space interface exposed by it, so
+``intel_pstate`` maps its internal representation of P-states to frequencies too
+(fortunately, that mapping is unambiguous).  At the same time, it would not be
+practical for ``intel_pstate`` to supply the ``CPUFreq`` core with a table of
+available frequencies due to the possible size of it, so the driver does not do
+that.  Some functionality of the core is limited by that.
+
+Since the hardware P-state selection interface used by ``intel_pstate`` is
+available at the logical CPU level, the driver always works with individual
+CPUs.  Consequently, if ``intel_pstate`` is in use, every ``CPUFreq`` policy
+object corresponds to one logical CPU and ``CPUFreq`` policies are effectively
+equivalent to CPUs.  In particular, this means that they become "inactive" every
+time the corresponding CPU is taken offline and need to be re-initialized when
+it goes back online.
+
+``intel_pstate`` is not modular, so it cannot be unloaded, which means that the
+only way to pass early-configuration-time parameters to it is via the kernel
+command line.  However, its configuration can be adjusted via ``sysfs`` to a
+great extent.  In some configurations it even is possible to unregister it via
+``sysfs`` which allows another ``CPUFreq`` scaling driver to be loaded and
+registered (see :ref:`below <status_attr>`).
+
+.. _operation_modes:
+
+Operation Modes
+===============
+
+``intel_pstate`` can operate in two different modes, active or passive.  In the
+active mode, it uses its own internal performance scaling governor algorithm or
+allows the hardware to do performance scaling by itself, while in the passive
+mode it responds to requests made by a generic ``CPUFreq`` governor implementing
+a certain performance scaling algorithm.  Which of them will be in effect
+depends on what kernel command line options are used and on the capabilities of
+the processor.
+
+.. _active_mode:
+
+Active Mode
+-----------
+
+This is the default operation mode of ``intel_pstate`` for processors with
+hardware-managed P-states (HWP) support.  If it works in this mode, the
+``scaling_driver`` policy attribute in ``sysfs`` for all ``CPUFreq`` policies
+contains the string "intel_pstate".
+
+In this mode the driver bypasses the scaling governors layer of ``CPUFreq`` and
+provides its own scaling algorithms for P-state selection.  Those algorithms
+can be applied to ``CPUFreq`` policies in the same way as generic scaling
+governors (that is, through the ``scaling_governor`` policy attribute in
+``sysfs``).  [Note that different P-state selection algorithms may be chosen for
+different policies, but that is not recommended.]
+
+They are not generic scaling governors, but their names are the same as the
+names of some of those governors.  Moreover, confusingly enough, they generally
+do not work in the same way as the generic governors they share the names with.
+For example, the ``powersave`` P-state selection algorithm provided by
+``intel_pstate`` is not a counterpart of the generic ``powersave`` governor
+(roughly, it corresponds to the ``schedutil`` and ``ondemand`` governors).
+
+There are two P-state selection algorithms provided by ``intel_pstate`` in the
+active mode: ``powersave`` and ``performance``.  The way they both operate
+depends on whether or not the hardware-managed P-states (HWP) feature has been
+enabled in the processor and possibly on the processor model.
+
+Which of the P-state selection algorithms is used by default depends on the
+:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option.
+Namely, if that option is set, the ``performance`` algorithm will be used by
+default, and the other one will be used by default if it is not set.
+
+.. _active_mode_hwp:
+
+Active Mode With HWP
+~~~~~~~~~~~~~~~~~~~~
+
+If the processor supports the HWP feature, it will be enabled during the
+processor initialization and cannot be disabled after that.  It is possible
+to avoid enabling it by passing the ``intel_pstate=no_hwp`` argument to the
+kernel in the command line.
+
+If the HWP feature has been enabled, ``intel_pstate`` relies on the processor to
+select P-states by itself, but still it can give hints to the processor's
+internal P-state selection logic.  What those hints are depends on which P-state
+selection algorithm has been applied to the given policy (or to the CPU it
+corresponds to).
+
+Even though the P-state selection is carried out by the processor automatically,
+``intel_pstate`` registers utilization update callbacks with the CPU scheduler
+in this mode.  However, they are not used for running a P-state selection
+algorithm, but for periodic updates of the current CPU frequency information to
+be made available from the ``scaling_cur_freq`` policy attribute in ``sysfs``.
+
+HWP + ``performance``
+.....................
+
+In this configuration ``intel_pstate`` will write 0 to the processor's
+Energy-Performance Preference (EPP) knob (if supported) or its
+Energy-Performance Bias (EPB) knob (otherwise), which means that the processor's
+internal P-state selection logic is expected to focus entirely on performance.
+
+This will override the EPP/EPB setting coming from the ``sysfs`` interface
+(see :ref:`energy_performance_hints` below).  Moreover, any attempts to change
+the EPP/EPB to a value different from 0 ("performance") via ``sysfs`` in this
+configuration will be rejected.
+
+Also, in this configuration the range of P-states available to the processor's
+internal P-state selection logic is always restricted to the upper boundary
+(that is, the maximum P-state that the driver is allowed to use).
+
+HWP + ``powersave``
+...................
+
+In this configuration ``intel_pstate`` will set the processor's
+Energy-Performance Preference (EPP) knob (if supported) or its
+Energy-Performance Bias (EPB) knob (otherwise) to whatever value it was
+previously set to via ``sysfs`` (or whatever default value it was
+set to by the platform firmware).  This usually causes the processor's
+internal P-state selection logic to be less performance-focused.
+
+Active Mode Without HWP
+~~~~~~~~~~~~~~~~~~~~~~~
+
+This operation mode is optional for processors that do not support the HWP
+feature or when the ``intel_pstate=no_hwp`` argument is passed to the kernel in
+the command line.  The active mode is used in those cases if the
+``intel_pstate=active`` argument is passed to the kernel in the command line.
+In this mode ``intel_pstate`` may refuse to work with processors that are not
+recognized by it.  [Note that ``intel_pstate`` will never refuse to work with
+any processor with the HWP feature enabled.]
+
+In this mode ``intel_pstate`` registers utilization update callbacks with the
+CPU scheduler in order to run a P-state selection algorithm, either
+``powersave`` or ``performance``, depending on the ``scaling_governor`` policy
+setting in ``sysfs``.  The current CPU frequency information to be made
+available from the ``scaling_cur_freq`` policy attribute in ``sysfs`` is
+periodically updated by those utilization update callbacks too.
+
+``performance``
+...............
+
+Without HWP, this P-state selection algorithm is always the same regardless of
+the processor model and platform configuration.
+
+It selects the maximum P-state it is allowed to use, subject to limits set via
+``sysfs``, every time the driver configuration for the given CPU is updated
+(e.g. via ``sysfs``).
+
+This is the default P-state selection algorithm if the
+:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option
+is set.
+
+``powersave``
+.............
+
+Without HWP, this P-state selection algorithm is similar to the algorithm
+implemented by the generic ``schedutil`` scaling governor except that the
+utilization metric used by it is based on numbers coming from feedback
+registers of the CPU.  It generally selects P-states proportional to the
+current CPU utilization.
+
+This algorithm is run by the driver's utilization update callback for the
+given CPU when it is invoked by the CPU scheduler, but not more often than
+every 10 ms.  Like in the ``performance`` case, the hardware configuration
+is not touched if the new P-state turns out to be the same as the current
+one.
+
+This is the default P-state selection algorithm if the
+:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option
+is not set.
+
+.. _passive_mode:
+
+Passive Mode
+------------
+
+This is the default operation mode of ``intel_pstate`` for processors without
+hardware-managed P-states (HWP) support.  It is always used if the
+``intel_pstate=passive`` argument is passed to the kernel in the command line
+regardless of whether or not the given processor supports HWP.  [Note that the
+``intel_pstate=no_hwp`` setting causes the driver to start in the passive mode
+if it is not combined with ``intel_pstate=active``.]  Like in the active mode
+without HWP support, in this mode ``intel_pstate`` may refuse to work with
+processors that are not recognized by it if HWP is prevented from being enabled
+through the kernel command line.
+
+If the driver works in this mode, the ``scaling_driver`` policy attribute in
+``sysfs`` for all ``CPUFreq`` policies contains the string "intel_cpufreq".
+Then, the driver behaves like a regular ``CPUFreq`` scaling driver.  That is,
+it is invoked by generic scaling governors when necessary to talk to the
+hardware in order to change the P-state of a CPU (in particular, the
+``schedutil`` governor can invoke it directly from scheduler context).
+
+While in this mode, ``intel_pstate`` can be used with all of the (generic)
+scaling governors listed by the ``scaling_available_governors`` policy attribute
+in ``sysfs`` (and the P-state selection algorithms described above are not
+used).  Then, it is responsible for the configuration of policy objects
+corresponding to CPUs and provides the ``CPUFreq`` core (and the scaling
+governors attached to the policy objects) with accurate information on the
+maximum and minimum operating frequencies supported by the hardware (including
+the so-called "turbo" frequency ranges).  In other words, in the passive mode
+the entire range of available P-states is exposed by ``intel_pstate`` to the
+``CPUFreq`` core.  However, in this mode the driver does not register
+utilization update callbacks with the CPU scheduler and the ``scaling_cur_freq``
+information comes from the ``CPUFreq`` core (and is the last frequency selected
+by the current scaling governor for the given policy).
+
+
+.. _turbo:
+
+Turbo P-states Support
+======================
+
+In the majority of cases, the entire range of P-states available to
+``intel_pstate`` can be divided into two sub-ranges that correspond to
+different types of processor behavior, above and below a boundary that
+will be referred to as the "turbo threshold" in what follows.
+
+The P-states above the turbo threshold are referred to as "turbo P-states" and
+the whole sub-range of P-states they belong to is referred to as the "turbo
+range".  These names are related to the Turbo Boost technology allowing a
+multicore processor to opportunistically increase the P-state of one or more
+cores if there is enough power to do that and if that is not going to cause the
+thermal envelope of the processor package to be exceeded.
+
+Specifically, if software sets the P-state of a CPU core within the turbo range
+(that is, above the turbo threshold), the processor is permitted to take over
+performance scaling control for that core and put it into turbo P-states of its
+choice going forward.  However, that permission is interpreted differently by
+different processor generations.  Namely, the Sandy Bridge generation of
+processors will never use any P-states above the last one set by software for
+the given core, even if it is within the turbo range, whereas all of the later
+processor generations will take it as a license to use any P-states from the
+turbo range, even above the one set by software.  In other words, on those
+processors setting any P-state from the turbo range will enable the processor
+to put the given core into all turbo P-states up to and including the maximum
+supported one as it sees fit.
+
+One important property of turbo P-states is that they are not sustainable.  More
+precisely, there is no guarantee that any CPUs will be able to stay in any of
+those states indefinitely, because the power distribution within the processor
+package may change over time  or the thermal envelope it was designed for might
+be exceeded if a turbo P-state was used for too long.
+
+In turn, the P-states below the turbo threshold generally are sustainable.  In
+fact, if one of them is set by software, the processor is not expected to change
+it to a lower one unless in a thermal stress or a power limit violation
+situation (a higher P-state may still be used if it is set for another CPU in
+the same package at the same time, for example).
+
+Some processors allow multiple cores to be in turbo P-states at the same time,
+but the maximum P-state that can be set for them generally depends on the number
+of cores running concurrently.  The maximum turbo P-state that can be set for 3
+cores at the same time usually is lower than the analogous maximum P-state for
+2 cores, which in turn usually is lower than the maximum turbo P-state that can
+be set for 1 core.  The one-core maximum turbo P-state is thus the maximum
+supported one overall.
+
+The maximum supported turbo P-state, the turbo threshold (the maximum supported
+non-turbo P-state) and the minimum supported P-state are specific to the
+processor model and can be determined by reading the processor's model-specific
+registers (MSRs).  Moreover, some processors support the Configurable TDP
+(Thermal Design Power) feature and, when that feature is enabled, the turbo
+threshold effectively becomes a configurable value that can be set by the
+platform firmware.
+
+Unlike ``_PSS`` objects in the ACPI tables, ``intel_pstate`` always exposes
+the entire range of available P-states, including the whole turbo range, to the
+``CPUFreq`` core and (in the passive mode) to generic scaling governors.  This
+generally causes turbo P-states to be set more often when ``intel_pstate`` is
+used relative to ACPI-based CPU performance scaling (see
+:ref:`below <acpi-cpufreq>` for more information).
+
+Moreover, since ``intel_pstate`` always knows what the real turbo threshold is
+(even if the Configurable TDP feature is enabled in the processor), its
+``no_turbo`` attribute in ``sysfs`` (described :ref:`below <no_turbo_attr>`) should
+work as expected in all cases (that is, if set to disable turbo P-states, it
+always should prevent ``intel_pstate`` from using them).
+
+
+Processor Support
+=================
+
+To handle a given processor ``intel_pstate`` requires a number of different
+pieces of information on it to be known, including:
+
+ * The minimum supported P-state.
+
+ * The maximum supported :ref:`non-turbo P-state <turbo>`.
+
+ * Whether or not turbo P-states are supported at all.
+
+ * The maximum supported :ref:`one-core turbo P-state <turbo>` (if turbo
+   P-states are supported).
+
+ * The scaling formula to translate the driver's internal representation
+   of P-states into frequencies and the other way around.
+
+Generally, ways to obtain that information are specific to the processor model
+or family.  Although it often is possible to obtain all of it from the processor
+itself (using model-specific registers), there are cases in which hardware
+manuals need to be consulted to get to it too.
+
+For this reason, there is a list of supported processors in ``intel_pstate`` and
+the driver initialization will fail if the detected processor is not in that
+list, unless it supports the HWP feature.  [The interface to obtain all of the
+information listed above is the same for all of the processors supporting the
+HWP feature, which is why ``intel_pstate`` works with all of them.]
+
+
+Support for Hybrid Processors
+=============================
+
+Some processors supported by ``intel_pstate`` contain two or more types of CPU
+cores differing by the maximum turbo P-state, performance vs power characteristics,
+cache sizes, and possibly other properties.  They are commonly referred to as
+hybrid processors.  To support them, ``intel_pstate`` requires HWP to be enabled
+and it assumes the HWP performance units to be the same for all CPUs in the
+system, so a given HWP performance level always represents approximately the
+same physical performance regardless of the core (CPU) type.
+
+Hybrid Processors with SMT
+--------------------------
+
+On systems where SMT (Simultaneous Multithreading), also referred to as
+HyperThreading (HT) in the context of Intel processors, is enabled on at least
+one core, ``intel_pstate`` assigns performance-based priorities to CPUs.  Namely,
+the priority of a given CPU reflects its highest HWP performance level which
+causes the CPU scheduler to generally prefer more performant CPUs, so the less
+performant CPUs are used when the other ones are fully loaded.  SMT siblings
+(that is, logical CPUs sharing one physical core) are given the same priority.
+The scheduler can pull tasks from lower-priority cores and place them on any
+sibling.  Since the scheduler spreads tasks among physical cores, tasks will be
+placed on the SMT siblings of physical cores only after all physical cores are
+busy.
+
+This approach maximizes performance in the majority of cases, but unfortunately
+it also leads to excessive energy usage in some important scenarios, like video
+playback, which is not generally desirable.  While there is no other viable
+choice with SMT enabled because the effective capacity and utilization of SMT
+siblings are hard to determine, hybrid processors without SMT can be handled in
+more energy-efficient ways.
+
+.. _CAS:
+
+Capacity-Aware Scheduling Support
+---------------------------------
+
+The capacity-aware scheduling (CAS) support in the CPU scheduler is enabled by
+``intel_pstate`` by default on hybrid processors without SMT.  CAS generally
+causes the scheduler to put tasks on a CPU so long as there is a sufficient
+amount of spare capacity on it, and if the utilization of a given task is too
+high for it, the task will need to go somewhere else.
+
+Since CAS takes CPU capacities into account, it does not require CPU
+prioritization and it allows tasks to be distributed more symmetrically among
+the more performant and less performant CPUs.  Once placed on a CPU with enough
+capacity to accommodate it, a task may just continue to run there regardless of
+whether or not the other CPUs are fully loaded, so on average CAS reduces the
+utilization of the more performant CPUs which causes the energy usage to be more
+balanced because the more performant CPUs are generally less energy-efficient
+than the less performant ones.
+
+In order to use CAS, the scheduler needs to know the capacity of each CPU in
+the system and it needs to be able to compute scale-invariant utilization of
+CPUs, so ``intel_pstate`` provides it with the requisite information.
+
+First of all, the capacity of each CPU is represented by the ratio of its highest
+HWP performance level, multiplied by 1024, to the highest HWP performance level
+of the most performant CPU in the system, which works because the HWP performance
+units are the same for all CPUs.  Second, the frequency-invariance computations,
+carried out by the scheduler to always express CPU utilization in the same units
+regardless of the frequency it is currently running at, are adjusted to take the
+CPU capacity into account.  All of this happens when ``intel_pstate`` has
+registered itself with the ``CPUFreq`` core and it has figured out that it is
+running on a hybrid processor without SMT.
+
+Energy-Aware Scheduling Support
+-------------------------------
+
+If ``CONFIG_ENERGY_MODEL`` has been set during kernel configuration and
+``intel_pstate`` runs on a hybrid processor without SMT, in addition to enabling
+:ref:`CAS` it registers an Energy Model for the processor.  This allows the
+Energy-Aware Scheduling (EAS) support to be enabled in the CPU scheduler if
+``schedutil`` is used as the  ``CPUFreq`` governor which requires ``intel_pstate``
+to operate in the :ref:`passive mode <passive_mode>`.
+
+The Energy Model registered by ``intel_pstate`` is artificial (that is, it is
+based on abstract cost values and it does not include any real power numbers)
+and it is relatively simple to avoid unnecessary computations in the scheduler.
+There is a performance domain in it for every CPU in the system and the cost
+values for these performance domains have been chosen so that running a task on
+a less performant (small) CPU appears to be always cheaper than running that
+task on a more performant (big) CPU.  However, for two CPUs of the same type,
+the cost difference depends on their current utilization, and the CPU whose
+current utilization is higher generally appears to be a more expensive
+destination for a given task.  This helps to balance the load among CPUs of the
+same type.
+
+Since EAS works on top of CAS, high-utilization tasks are always migrated to
+CPUs with enough capacity to accommodate them, but thanks to EAS, low-utilization
+tasks tend to be placed on the CPUs that look less expensive to the scheduler.
+Effectively, this causes the less performant and less loaded CPUs to be
+preferred as long as they have enough spare capacity to run the given task
+which generally leads to reduced energy usage.
+
+The Energy Model created by ``intel_pstate`` can be inspected by looking at
+the ``energy_model`` directory in ``debugfs`` (typlically mounted on
+``/sys/kernel/debug/``).
+
+
+User Space Interface in ``sysfs``
+=================================
+
+.. _global_attributes:
+
+Global Attributes
+-----------------
+
+``intel_pstate`` exposes several global attributes (files) in ``sysfs`` to
+control its functionality at the system level.  They are located in the
+``/sys/devices/system/cpu/intel_pstate/`` directory and affect all CPUs.
+
+Some of them are not present if the ``intel_pstate=per_cpu_perf_limits``
+argument is passed to the kernel in the command line.
+
+``max_perf_pct``
+	Maximum P-state the driver is allowed to set in percent of the
+	maximum supported performance level (the highest supported :ref:`turbo
+	P-state <turbo>`).
+
+	This attribute will not be exposed if the
+	``intel_pstate=per_cpu_perf_limits`` argument is present in the kernel
+	command line.
+
+``min_perf_pct``
+	Minimum P-state the driver is allowed to set in percent of the
+	maximum supported performance level (the highest supported :ref:`turbo
+	P-state <turbo>`).
+
+	This attribute will not be exposed if the
+	``intel_pstate=per_cpu_perf_limits`` argument is present in the kernel
+	command line.
+
+``num_pstates``
+	Number of P-states supported by the processor (between 0 and 255
+	inclusive) including both turbo and non-turbo P-states (see
+	:ref:`turbo`).
+
+	This attribute is present only if the value exposed by it is the same
+	for all of the CPUs in the system.
+
+	The value of this attribute is not affected by the ``no_turbo``
+	setting described :ref:`below <no_turbo_attr>`.
+
+	This attribute is read-only.
+
+``turbo_pct``
+	Ratio of the :ref:`turbo range <turbo>` size to the size of the entire
+	range of supported P-states, in percent.
+
+	This attribute is present only if the value exposed by it is the same
+	for all of the CPUs in the system.
+
+	This attribute is read-only.
+
+.. _no_turbo_attr:
+
+``no_turbo``
+	If set (equal to 1), the driver is not allowed to set any turbo P-states
+	(see :ref:`turbo`).  If unset (equal to 0, which is the
+	default), turbo P-states can be set by the driver.
+	[Note that ``intel_pstate`` does not support the general ``boost``
+	attribute (supported by some other scaling drivers) which is replaced
+	by this one.]
+
+	This attribute does not affect the maximum supported frequency value
+	supplied to the ``CPUFreq`` core and exposed via the policy interface,
+	but it affects the maximum possible value of per-policy P-state	limits
+	(see :ref:`policy_attributes_interpretation` below for details).
+
+``hwp_dynamic_boost``
+	This attribute is only present if ``intel_pstate`` works in the
+	:ref:`active mode with the HWP feature enabled <active_mode_hwp>` in
+	the processor.  If set (equal to 1), it causes the minimum P-state limit
+	to be increased dynamically for a short time whenever a task previously
+	waiting on I/O is selected to run on a given logical CPU (the purpose
+	of this mechanism is to improve performance).
+
+	This setting has no effect on logical CPUs whose minimum P-state limit
+	is directly set to the highest non-turbo P-state or above it.
+
+.. _status_attr:
+
+``status``
+	Operation mode of the driver: "active", "passive" or "off".
+
+	"active"
+		The driver is functional and in the :ref:`active mode
+		<active_mode>`.
+
+	"passive"
+		The driver is functional and in the :ref:`passive mode
+		<passive_mode>`.
+
+	"off"
+		The driver is not functional (it is not registered as a scaling
+		driver with the ``CPUFreq`` core).
+
+	This attribute can be written to in order to change the driver's
+	operation mode or to unregister it.  The string written to it must be
+	one of the possible values of it and, if successful, the write will
+	cause the driver to switch over to the operation mode represented by
+	that string - or to be unregistered in the "off" case.  [Actually,
+	switching over from the active mode to the passive mode or the other
+	way around causes the driver to be unregistered and registered again
+	with a different set of callbacks, so all of its settings (the global
+	as well as the per-policy ones) are then reset to their default
+	values, possibly depending on the target operation mode.]
+
+``energy_efficiency``
+	This attribute is only present on platforms with CPUs matching the Kaby
+	Lake or Coffee Lake desktop CPU model. By default, energy-efficiency
+	optimizations are disabled on these CPU models if HWP is enabled.
+	Enabling energy-efficiency optimizations may limit maximum operating
+	frequency with or without the HWP feature.  With HWP enabled, the
+	optimizations are done only in the turbo frequency range.  Without it,
+	they are done in the entire available frequency range.  Setting this
+	attribute to "1" enables the energy-efficiency optimizations and setting
+	to "0" disables them.
+
+.. _policy_attributes_interpretation:
+
+Interpretation of Policy Attributes
+-----------------------------------
+
+The interpretation of some ``CPUFreq`` policy attributes described in
+Documentation/admin-guide/pm/cpufreq.rst is special with ``intel_pstate``
+as the current scaling driver and it generally depends on the driver's
+:ref:`operation mode <operation_modes>`.
+
+First of all, the values of the ``cpuinfo_max_freq``, ``cpuinfo_min_freq`` and
+``scaling_cur_freq`` attributes are produced by applying a processor-specific
+multiplier to the internal P-state representation used by ``intel_pstate``.
+Also, the values of the ``scaling_max_freq`` and ``scaling_min_freq``
+attributes are capped by the frequency corresponding to the maximum P-state that
+the driver is allowed to set.
+
+If the ``no_turbo`` :ref:`global attribute <no_turbo_attr>` is set, the driver
+is not allowed to use turbo P-states, so the maximum value of
+``scaling_max_freq`` and ``scaling_min_freq`` is limited to the maximum
+non-turbo P-state frequency.
+Accordingly, setting ``no_turbo`` causes ``scaling_max_freq`` and
+``scaling_min_freq`` to go down to that value if they were above it before.
+However, the old values of ``scaling_max_freq`` and ``scaling_min_freq`` will be
+restored after unsetting ``no_turbo``, unless these attributes have been written
+to after ``no_turbo`` was set.
+
+If ``no_turbo`` is not set, the maximum possible value of ``scaling_max_freq``
+and ``scaling_min_freq`` corresponds to the maximum supported turbo P-state,
+which also is the value of ``cpuinfo_max_freq`` in either case.
+
+Next, the following policy attributes have special meaning if
+``intel_pstate`` works in the :ref:`active mode <active_mode>`:
+
+``scaling_available_governors``
+	List of P-state selection algorithms provided by ``intel_pstate``.
+
+``scaling_governor``
+	P-state selection algorithm provided by ``intel_pstate`` currently in
+	use with the given policy.
+
+``scaling_cur_freq``
+	Frequency of the average P-state of the CPU represented by the given
+	policy for the time interval between the last two invocations of the
+	driver's utilization update callback by the CPU scheduler for that CPU.
+
+One more policy attribute is present if the HWP feature is enabled in the
+processor:
+
+``base_frequency``
+	Shows the base frequency of the CPU. Any frequency above this will be
+	in the turbo frequency range.
+
+The meaning of these attributes in the :ref:`passive mode <passive_mode>` is the
+same as for other scaling drivers.
+
+Additionally, the value of the ``scaling_driver`` attribute for ``intel_pstate``
+depends on the operation mode of the driver.  Namely, it is either
+"intel_pstate" (in the :ref:`active mode <active_mode>`) or "intel_cpufreq"
+(in the :ref:`passive mode <passive_mode>`).
+
+.. _pstate_limits_coordination:
+
+Coordination of P-State Limits
+------------------------------
+
+``intel_pstate`` allows P-state limits to be set in two ways: with the help of
+the ``max_perf_pct`` and ``min_perf_pct`` :ref:`global attributes
+<global_attributes>` or via the ``scaling_max_freq`` and ``scaling_min_freq``
+``CPUFreq`` policy attributes.  The coordination between those limits is based
+on the following rules, regardless of the current operation mode of the driver:
+
+ 1. All CPUs are affected by the global limits (that is, none of them can be
+    requested to run faster than the global maximum and none of them can be
+    requested to run slower than the global minimum).
+
+ 2. Each individual CPU is affected by its own per-policy limits (that is, it
+    cannot be requested to run faster than its own per-policy maximum and it
+    cannot be requested to run slower than its own per-policy minimum). The
+    effective performance depends on whether the platform supports per core
+    P-states, hyper-threading is enabled and on current performance requests
+    from other CPUs. When platform doesn't support per core P-states, the
+    effective performance can be more than the policy limits set on a CPU, if
+    other CPUs are requesting higher performance at that moment. Even with per
+    core P-states support, when hyper-threading is enabled, if the sibling CPU
+    is requesting higher performance, the other siblings will get higher
+    performance than their policy limits.
+
+ 3. The global and per-policy limits can be set independently.
+
+In the :ref:`active mode with the HWP feature enabled <active_mode_hwp>`, the
+resulting effective values are written into hardware registers whenever the
+limits change in order to request its internal P-state selection logic to always
+set P-states within these limits.  Otherwise, the limits are taken into account
+by scaling governors (in the :ref:`passive mode <passive_mode>`) and by the
+driver every time before setting a new P-state for a CPU.
+
+Additionally, if the ``intel_pstate=per_cpu_perf_limits`` command line argument
+is passed to the kernel, ``max_perf_pct`` and ``min_perf_pct`` are not exposed
+at all and the only way to set the limits is by using the policy attributes.
+
+.. _energy_performance_hints:
+
+Energy vs Performance Hints
+---------------------------
+
+If the hardware-managed P-states (HWP) is enabled in the processor, additional
+attributes, intended to allow user space to help ``intel_pstate`` to adjust the
+processor's internal P-state selection logic by focusing it on performance or on
+energy-efficiency, or somewhere between the two extremes, are present in every
+``CPUFreq`` policy directory in ``sysfs``.  They are :
+
+``energy_performance_preference``
+	Current value of the energy vs performance hint for the given policy
+	(or the CPU represented by it).
+
+	The hint can be changed by writing to this attribute.
+
+``energy_performance_available_preferences``
+	List of strings that can be written to the
+	``energy_performance_preference`` attribute.
+
+	They represent different energy vs performance hints and should be
+	self-explanatory, except that ``default`` represents whatever hint
+	value was set by the platform firmware.
+
+Strings written to the ``energy_performance_preference`` attribute are
+internally translated to integer values written to the processor's
+Energy-Performance Preference (EPP) knob (if supported) or its
+Energy-Performance Bias (EPB) knob. It is also possible to write a positive
+integer value between 0 to 255, if the EPP feature is present. If the EPP
+feature is not present, writing integer value to this attribute is not
+supported. In this case, user can use the
+"/sys/devices/system/cpu/cpu*/power/energy_perf_bias" interface.
+
+[Note that tasks may by migrated from one CPU to another by the scheduler's
+load-balancing algorithm and if different energy vs performance hints are
+set for those CPUs, that may lead to undesirable outcomes.  To avoid such
+issues it is better to set the same energy vs performance hint for all CPUs
+or to pin every task potentially sensitive to them to a specific CPU.]
+
+.. _acpi-cpufreq:
+
+``intel_pstate`` vs ``acpi-cpufreq``
+====================================
+
+On the majority of systems supported by ``intel_pstate``, the ACPI tables
+provided by the platform firmware contain ``_PSS`` objects returning information
+that can be used for CPU performance scaling (refer to the ACPI specification
+[3]_ for details on the ``_PSS`` objects and the format of the information
+returned by them).
+
+The information returned by the ACPI ``_PSS`` objects is used by the
+``acpi-cpufreq`` scaling driver.  On systems supported by ``intel_pstate``
+the ``acpi-cpufreq`` driver uses the same hardware CPU performance scaling
+interface, but the set of P-states it can use is limited by the ``_PSS``
+output.
+
+On those systems each ``_PSS`` object returns a list of P-states supported by
+the corresponding CPU which basically is a subset of the P-states range that can
+be used by ``intel_pstate`` on the same system, with one exception: the whole
+:ref:`turbo range <turbo>` is represented by one item in it (the topmost one).
+By convention, the frequency returned by ``_PSS`` for that item is greater by
+1 MHz than the frequency of the highest non-turbo P-state listed by it, but the
+corresponding P-state representation (following the hardware specification)
+returned for it matches the maximum supported turbo P-state (or is the
+special value 255 meaning essentially "go as high as you can get").
+
+The list of P-states returned by ``_PSS`` is reflected by the table of
+available frequencies supplied by ``acpi-cpufreq`` to the ``CPUFreq`` core and
+scaling governors and the minimum and maximum supported frequencies reported by
+it come from that list as well.  In particular, given the special representation
+of the turbo range described above, this means that the maximum supported
+frequency reported by ``acpi-cpufreq`` is higher by 1 MHz than the frequency
+of the highest supported non-turbo P-state listed by ``_PSS`` which, of course,
+affects decisions made by the scaling governors, except for ``powersave`` and
+``performance``.
+
+For example, if a given governor attempts to select a frequency proportional to
+estimated CPU load and maps the load of 100% to the maximum supported frequency
+(possibly multiplied by a constant), then it will tend to choose P-states below
+the turbo threshold if ``acpi-cpufreq`` is used as the scaling driver, because
+in that case the turbo range corresponds to a small fraction of the frequency
+band it can use (1 MHz vs 1 GHz or more).  In consequence, it will only go to
+the turbo range for the highest loads and the other loads above 50% that might
+benefit from running at turbo frequencies will be given non-turbo P-states
+instead.
+
+One more issue related to that may appear on systems supporting the
+:ref:`Configurable TDP feature <turbo>` allowing the platform firmware to set
+the turbo threshold.  Namely, if that is not coordinated with the lists of
+P-states returned by ``_PSS`` properly, there may be more than one item
+corresponding to a turbo P-state in those lists and there may be a problem with
+avoiding the turbo range (if desirable or necessary).  Usually, to avoid using
+turbo P-states overall, ``acpi-cpufreq`` simply avoids using the topmost state
+listed by ``_PSS``, but that is not sufficient when there are other turbo
+P-states in the list returned by it.
+
+Apart from the above, ``acpi-cpufreq`` works like ``intel_pstate`` in the
+:ref:`passive mode <passive_mode>`, except that the number of P-states it can
+set is limited to the ones listed by the ACPI ``_PSS`` objects.
+
+
+Kernel Command Line Options for ``intel_pstate``
+================================================
+
+Several kernel command line options can be used to pass early-configuration-time
+parameters to ``intel_pstate`` in order to enforce specific behavior of it.  All
+of them have to be prepended with the ``intel_pstate=`` prefix.
+
+``disable``
+	Do not register ``intel_pstate`` as the scaling driver even if the
+	processor is supported by it.
+
+``active``
+	Register ``intel_pstate`` in the :ref:`active mode <active_mode>` to
+        start with.
+
+``passive``
+	Register ``intel_pstate`` in the :ref:`passive mode <passive_mode>` to
+	start with.
+
+``force``
+	Register ``intel_pstate`` as the scaling driver instead of
+	``acpi-cpufreq`` even if the latter is preferred on the given system.
+
+	This may prevent some platform features (such as thermal controls and
+	power capping) that rely on the availability of ACPI P-states
+	information from functioning as expected, so it should be used with
+	caution.
+
+	This option does not work with processors that are not supported by
+	``intel_pstate`` and on platforms where the ``pcc-cpufreq`` scaling
+	driver is used instead of ``acpi-cpufreq``.
+
+``no_hwp``
+	Do not enable the hardware-managed P-states (HWP) feature even if it is
+	supported by the processor.
+
+``hwp_only``
+	Register ``intel_pstate`` as the scaling driver only if the
+	hardware-managed P-states (HWP) feature is supported by the processor.
+
+``support_acpi_ppc``
+	Take ACPI ``_PPC`` performance limits into account.
+
+	If the preferred power management profile in the FADT (Fixed ACPI
+	Description Table) is set to "Enterprise Server" or "Performance
+	Server", the ACPI ``_PPC`` limits are taken into account by default
+	and this option has no effect.
+
+``per_cpu_perf_limits``
+	Use per-logical-CPU P-State limits (see
+        :ref:`pstate_limits_coordination` for details).
+
+``no_cas``
+	Do not enable :ref:`capacity-aware scheduling <CAS>` which is enabled
+        by default on hybrid systems without SMT.
+
+Diagnostics and Tuning
+======================
+
+Trace Events
+------------
+
+There are two static trace events that can be used for ``intel_pstate``
+diagnostics.  One of them is the ``cpu_frequency`` trace event generally used
+by ``CPUFreq``, and the other one is the ``pstate_sample`` trace event specific
+to ``intel_pstate``.  Both of them are triggered by ``intel_pstate`` only if
+it works in the :ref:`active mode <active_mode>`.
+
+The following sequence of shell commands can be used to enable them and see
+their output (if the kernel is generally configured to support event tracing)::
+
+ # cd /sys/kernel/tracing/
+ # echo 1 > events/power/pstate_sample/enable
+ # echo 1 > events/power/cpu_frequency/enable
+ # cat trace
+ gnome-terminal--4510  [001] ..s.  1177.680733: pstate_sample: core_busy=107 scaled=94 from=26 to=26 mperf=1143818 aperf=1230607 tsc=29838618 freq=2474476
+ cat-5235  [002] ..s.  1177.681723: cpu_frequency: state=2900000 cpu_id=2
+
+If ``intel_pstate`` works in the :ref:`passive mode <passive_mode>`, the
+``cpu_frequency`` trace event will be triggered either by the ``schedutil``
+scaling governor (for the policies it is attached to), or by the ``CPUFreq``
+core (for the policies with other scaling governors).
+
+``ftrace``
+----------
+
+The ``ftrace`` interface can be used for low-level diagnostics of
+``intel_pstate``.  For example, to check how often the function to set a
+P-state is called, the ``ftrace`` filter can be set to
+:c:func:`intel_pstate_set_pstate`::
+
+ # cd /sys/kernel/tracing/
+ # cat available_filter_functions | grep -i pstate
+ intel_pstate_set_pstate
+ intel_pstate_cpu_init
+ ...
+ # echo intel_pstate_set_pstate > set_ftrace_filter
+ # echo function > current_tracer
+ # cat trace | head -15
+ # tracer: function
+ #
+ # entries-in-buffer/entries-written: 80/80   #P:4
+ #
+ #                              _-----=> irqs-off
+ #                             / _----=> need-resched
+ #                            | / _---=> hardirq/softirq
+ #                            || / _--=> preempt-depth
+ #                            ||| /     delay
+ #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
+ #              | |       |   ||||       |         |
+             Xorg-3129  [000] ..s.  2537.644844: intel_pstate_set_pstate <-intel_pstate_timer_func
+  gnome-terminal--4510  [002] ..s.  2537.649844: intel_pstate_set_pstate <-intel_pstate_timer_func
+      gnome-shell-3409  [001] ..s.  2537.650850: intel_pstate_set_pstate <-intel_pstate_timer_func
+           <idle>-0     [000] ..s.  2537.654843: intel_pstate_set_pstate <-intel_pstate_timer_func
+
+
+References
+==========
+
+.. [1] Kristen Accardi, *Balancing Power and Performance in the Linux Kernel*,
+       https://events.static.linuxfound.org/sites/events/files/slides/LinuxConEurope_2015.pdf
+
+.. [2] *Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 3: System Programming Guide*,
+       https://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-system-programming-manual-325384.html
+
+.. [3] *Advanced Configuration and Power Interface Specification*,
+       https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf
diff --git a/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst
new file mode 100644
index 000000000..b43ad4d5e
--- /dev/null
+++ b/Documentation/admin-guide/pm/intel_uncore_frequency_scaling.rst
@@ -0,0 +1,191 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+==============================
+Intel Uncore Frequency Scaling
+==============================
+
+:Copyright: |copy| 2022-2023 Intel Corporation
+
+:Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+
+Introduction
+------------
+
+The uncore can consume significant amount of power in Intel's Xeon servers based
+on the workload characteristics. To optimize the total power and improve overall
+performance, SoCs have internal algorithms for scaling uncore frequency. These
+algorithms monitor workload usage of uncore and set a desirable frequency.
+
+It is possible that users have different expectations of uncore performance and
+want to have control over it. The objective is similar to allowing users to set
+the scaling min/max frequencies via cpufreq sysfs to improve CPU performance.
+Users may have some latency sensitive workloads where they do not want any
+change to uncore frequency. Also, users may have workloads which require
+different core and uncore performance at distinct phases and they may want to
+use both cpufreq and the uncore scaling interface to distribute power and
+improve overall performance.
+
+Sysfs Interface
+---------------
+
+To control uncore frequency, a sysfs interface is provided in the directory:
+`/sys/devices/system/cpu/intel_uncore_frequency/`.
+
+There is one directory for each package and die combination as the scope of
+uncore scaling control is per die in multiple die/package SoCs or per
+package for single die per package SoCs. The name represents the
+scope of control. For example: 'package_00_die_00' is for package id 0 and
+die 0.
+
+Each package_*_die_* contains the following attributes:
+
+``initial_max_freq_khz``
+	Out of reset, this attribute represent the maximum possible frequency.
+	This is a read-only attribute. If users adjust max_freq_khz,
+	they can always go back to maximum using the value from this attribute.
+
+``initial_min_freq_khz``
+	Out of reset, this attribute represent the minimum possible frequency.
+	This is a read-only attribute. If users adjust min_freq_khz,
+	they can always go back to minimum using the value from this attribute.
+
+``max_freq_khz``
+	This attribute is used to set the maximum uncore frequency.
+
+``min_freq_khz``
+	This attribute is used to set the minimum uncore frequency.
+
+``current_freq_khz``
+	This attribute is used to get the current uncore frequency.
+
+SoCs with TPMI (Topology Aware Register and PM Capsule Interface)
+-----------------------------------------------------------------
+
+An SoC can contain multiple power domains with individual or collection
+of mesh partitions. This partition is called fabric cluster.
+
+Certain type of meshes will need to run at the same frequency, they will
+be placed in the same fabric cluster. Benefit of fabric cluster is that it
+offers a scalable mechanism to deal with partitioned fabrics in a SoC.
+
+The current sysfs interface supports controls at package and die level.
+This interface is not enough to support more granular control at
+fabric cluster level.
+
+SoCs with the support of TPMI (Topology Aware Register and PM Capsule
+Interface), can have multiple power domains. Each power domain can
+contain one or more fabric clusters.
+
+To represent controls at fabric cluster level in addition to the
+controls at package and die level (like systems without TPMI
+support), sysfs is enhanced. This granular interface is presented in the
+sysfs with directories names prefixed with "uncore". For example:
+uncore00, uncore01 etc.
+
+The scope of control is specified by attributes "package_id", "domain_id"
+and "fabric_cluster_id" in the directory.
+
+Attributes in each directory:
+
+``instance_id``
+	This attribute is used to get die indices in userspace mapped MMIO
+	blocks. Indices are local to a single TPMI partition. Needed for direct
+	TPMI register access.
+
+``domain_id``
+	This attribute is used to get the power domain id of this instance.
+	Indices are unique in all TPMI partitions on a given CPU package. Can be
+	used to map compute dies to corresponding CPUs.
+
+``die_id``
+	This attribute is used to get the Linux die id of this instance.
+	This attribute is only present for domains with core agents and
+	when the CPUID leaf 0x1f presents die ID.
+
+``fabric_cluster_id``
+	This attribute is used to get the fabric cluster id of this instance.
+
+``package_id``
+	This attribute is used to get the package id of this instance.
+
+``agent_types``
+	This attribute displays all the hardware agents present within the
+	domain. Each agent has the capability to control one or more hardware
+	subsystems, which include: core, cache, memory, and I/O.
+
+The other attributes are same as presented at package_*_die_* level.
+
+In most of current use cases, the "max_freq_khz" and "min_freq_khz"
+is updated at "package_*_die_*" level. This model will be still supported
+with the following approach:
+
+When user uses controls at "package_*_die_*" level, then every fabric
+cluster is affected in that package and die. For example: user changes
+"max_freq_khz" in the package_00_die_00, then "max_freq_khz" for uncore*
+directory with the same package id will be updated. In this case user can
+still update "max_freq_khz" at each uncore* level, which is more restrictive.
+Similarly, user can update "min_freq_khz" at "package_*_die_*" level
+to apply at each uncore* level.
+
+Support for "current_freq_khz" is available only at each fabric cluster
+level (i.e., in uncore* directory).
+
+Efficiency vs. Latency Tradeoff
+-------------------------------
+
+The Efficiency Latency Control (ELC) feature improves performance
+per watt. With this feature hardware power management algorithms
+optimize trade-off between latency and power consumption. For some
+latency sensitive workloads further tuning can be done by SW to
+get desired performance.
+
+The hardware monitors the average CPU utilization across all cores
+in a power domain at regular intervals and decides an uncore frequency.
+While this may result in the best performance per watt, workload may be
+expecting higher performance at the expense of power. Consider an
+application that intermittently wakes up to perform memory reads on an
+otherwise idle system. In such cases, if hardware lowers uncore
+frequency, then there may be delay in ramp up of frequency to meet
+target performance.
+
+The ELC control defines some parameters which can be changed from SW.
+If the average CPU utilization is below a user-defined threshold
+(elc_low_threshold_percent attribute below), the user-defined uncore
+floor frequency will be used (elc_floor_freq_khz attribute below)
+instead of hardware calculated minimum.
+
+Similarly in high load scenario where the CPU utilization goes above
+the high threshold value (elc_high_threshold_percent attribute below)
+instead of jumping to maximum uncore frequency, frequency is increased
+in 100MHz steps. This avoids consuming unnecessarily high power
+immediately with CPU utilization spikes.
+
+Attributes for efficiency latency control:
+
+``elc_floor_freq_khz``
+	This attribute is used to get/set the efficiency latency floor frequency.
+	If this variable is lower than the 'min_freq_khz', it is ignored by
+	the firmware.
+
+``elc_low_threshold_percent``
+	This attribute is used to get/set the efficiency latency control low
+	threshold. This attribute is in percentages of CPU utilization.
+
+``elc_high_threshold_percent``
+	This attribute is used to get/set the efficiency latency control high
+	threshold. This attribute is in percentages of CPU utilization.
+
+``elc_high_threshold_enable``
+	This attribute is used to enable/disable the efficiency latency control
+	high threshold. Write '1' to enable, '0' to disable.
+
+Example system configuration below, which does following:
+  * when CPU utilization is less than 10%: sets uncore frequency to 800MHz
+  * when CPU utilization is higher than 95%: increases uncore frequency in
+    100MHz steps, until power limit is reached
+
+  elc_floor_freq_khz:800000
+  elc_high_threshold_percent:95
+  elc_high_threshold_enable:1
+  elc_low_threshold_percent:10
diff --git a/Documentation/admin-guide/pm/sleep-states.rst b/Documentation/admin-guide/pm/sleep-states.rst
new file mode 100644
index 000000000..ee55a460c
--- /dev/null
+++ b/Documentation/admin-guide/pm/sleep-states.rst
@@ -0,0 +1,291 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===================
+System Sleep States
+===================
+
+:Copyright: |copy| 2017 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+Sleep states are global low-power states of the entire system in which user
+space code cannot be executed and the overall system activity is significantly
+reduced.
+
+
+Sleep States That Can Be Supported
+==================================
+
+Depending on its configuration and the capabilities of the platform it runs on,
+the Linux kernel can support up to four system sleep states, including
+hibernation and up to three variants of system suspend.  The sleep states that
+can be supported by the kernel are listed below.
+
+.. _s2idle:
+
+Suspend-to-Idle
+---------------
+
+This is a generic, pure software, light-weight variant of system suspend (also
+referred to as S2I or S2Idle).  It allows more energy to be saved relative to
+runtime idle by freezing user space, suspending the timekeeping and putting all
+I/O devices into low-power states (possibly lower-power than available in the
+working state), such that the processors can spend time in their deepest idle
+states while the system is suspended.
+
+The system is woken up from this state by in-band interrupts, so theoretically
+any devices that can cause interrupts to be generated in the working state can
+also be set up as wakeup devices for S2Idle.
+
+This state can be used on platforms without support for :ref:`standby <standby>`
+or :ref:`suspend-to-RAM <s2ram>`, or it can be used in addition to any of the
+deeper system suspend variants to provide reduced resume latency.  It is always
+supported if the :c:macro:`CONFIG_SUSPEND` kernel configuration option is set.
+
+.. _standby:
+
+Standby
+-------
+
+This state, if supported, offers moderate, but real, energy savings, while
+providing a relatively straightforward transition back to the working state.  No
+operating state is lost (the system core logic retains power), so the system can
+go back to where it left off easily enough.
+
+In addition to freezing user space, suspending the timekeeping and putting all
+I/O devices into low-power states, which is done for :ref:`suspend-to-idle
+<s2idle>` too, nonboot CPUs are taken offline and all low-level system functions
+are suspended during transitions into this state.  For this reason, it should
+allow more energy to be saved relative to :ref:`suspend-to-idle <s2idle>`, but
+the resume latency will generally be greater than for that state.
+
+The set of devices that can wake up the system from this state usually is
+reduced relative to :ref:`suspend-to-idle <s2idle>` and it may be necessary to
+rely on the platform for setting up the wakeup functionality as appropriate.
+
+This state is supported if the :c:macro:`CONFIG_SUSPEND` kernel configuration
+option is set and the support for it is registered by the platform with the
+core system suspend subsystem.  On ACPI-based systems this state is mapped to
+the S1 system state defined by ACPI.
+
+.. _s2ram:
+
+Suspend-to-RAM
+--------------
+
+This state (also referred to as STR or S2RAM), if supported, offers significant
+energy savings as everything in the system is put into a low-power state, except
+for memory, which should be placed into the self-refresh mode to retain its
+contents.  All of the steps carried out when entering :ref:`standby <standby>`
+are also carried out during transitions to S2RAM.  Additional operations may
+take place depending on the platform capabilities.  In particular, on ACPI-based
+systems the kernel passes control to the platform firmware (BIOS) as the last
+step during S2RAM transitions and that usually results in powering down some
+more low-level components that are not directly controlled by the kernel.
+
+The state of devices and CPUs is saved and held in memory.  All devices are
+suspended and put into low-power states.  In many cases, all peripheral buses
+lose power when entering S2RAM, so devices must be able to handle the transition
+back to the "on" state.
+
+On ACPI-based systems S2RAM requires some minimal boot-strapping code in the
+platform firmware to resume the system from it.  This may be the case on other
+platforms too.
+
+The set of devices that can wake up the system from S2RAM usually is reduced
+relative to :ref:`suspend-to-idle <s2idle>` and :ref:`standby <standby>` and it
+may be necessary to rely on the platform for setting up the wakeup functionality
+as appropriate.
+
+S2RAM is supported if the :c:macro:`CONFIG_SUSPEND` kernel configuration option
+is set and the support for it is registered by the platform with the core system
+suspend subsystem.  On ACPI-based systems it is mapped to the S3 system state
+defined by ACPI.
+
+.. _hibernation:
+
+Hibernation
+-----------
+
+This state (also referred to as Suspend-to-Disk or STD) offers the greatest
+energy savings and can be used even in the absence of low-level platform support
+for system suspend.  However, it requires some low-level code for resuming the
+system to be present for the underlying CPU architecture.
+
+Hibernation is significantly different from any of the system suspend variants.
+It takes three system state changes to put it into hibernation and two system
+state changes to resume it.
+
+First, when hibernation is triggered, the kernel stops all system activity and
+creates a snapshot image of memory to be written into persistent storage.  Next,
+the system goes into a state in which the snapshot image can be saved, the image
+is written out and finally the system goes into the target low-power state in
+which power is cut from almost all of its hardware components, including memory,
+except for a limited set of wakeup devices.
+
+Once the snapshot image has been written out, the system may either enter a
+special low-power state (like ACPI S4), or it may simply power down itself.
+Powering down means minimum power draw and it allows this mechanism to work on
+any system.  However, entering a special low-power state may allow additional
+means of system wakeup to be used  (e.g. pressing a key on the keyboard or
+opening a laptop lid).
+
+After wakeup, control goes to the platform firmware that runs a boot loader
+which boots a fresh instance of the kernel (control may also go directly to
+the boot loader, depending on the system configuration, but anyway it causes
+a fresh instance of the kernel to be booted).  That new instance of the kernel
+(referred to as the ``restore kernel``) looks for a hibernation image in
+persistent storage and if one is found, it is loaded into memory.  Next, all
+activity in the system is stopped and the restore kernel overwrites itself with
+the image contents and jumps into a special trampoline area in the original
+kernel stored in the image (referred to as the ``image kernel``), which is where
+the special architecture-specific low-level code is needed.  Finally, the
+image kernel restores the system to the pre-hibernation state and allows user
+space to run again.
+
+Hibernation is supported if the :c:macro:`CONFIG_HIBERNATION` kernel
+configuration option is set.  However, this option can only be set if support
+for the given CPU architecture includes the low-level code for system resume.
+
+
+Basic ``sysfs`` Interfaces for System Suspend and Hibernation
+=============================================================
+
+The power management subsystem provides userspace with a unified ``sysfs``
+interface for system sleep regardless of the underlying system architecture or
+platform.  That interface is located in the :file:`/sys/power/` directory
+(assuming that ``sysfs`` is mounted at :file:`/sys`) and it consists of the
+following attributes (files):
+
+``state``
+	This file contains a list of strings representing sleep states supported
+	by the kernel.  Writing one of these strings into it causes the kernel
+	to start a transition of the system into the sleep state represented by
+	that string.
+
+	In particular, the "disk", "freeze" and "standby" strings represent the
+	:ref:`hibernation <hibernation>`, :ref:`suspend-to-idle <s2idle>` and
+	:ref:`standby <standby>` sleep states, respectively.  The "mem" string
+	is interpreted in accordance with the contents of the ``mem_sleep`` file
+	described below.
+
+	If the kernel does not support any system sleep states, this file is
+	not present.
+
+``mem_sleep``
+	This file contains a list of strings representing supported system
+	suspend	variants and allows user space to select the variant to be
+	associated with the "mem" string in the ``state`` file described above.
+
+	The strings that may be present in this file are "s2idle", "shallow"
+	and "deep".  The "s2idle" string always represents :ref:`suspend-to-idle
+	<s2idle>` and, by convention, "shallow" and "deep" represent
+	:ref:`standby <standby>` and :ref:`suspend-to-RAM <s2ram>`,
+	respectively.
+
+	Writing one of the listed strings into this file causes the system
+	suspend variant represented by it to be associated with the "mem" string
+	in the ``state`` file.  The string representing the suspend variant
+	currently associated with the "mem" string in the ``state`` file is
+	shown in square brackets.
+
+	If the kernel does not support system suspend, this file is not present.
+
+``disk``
+	This file controls the operating mode of hibernation (Suspend-to-Disk).
+	Specifically, it tells the kernel what to do after creating a
+	hibernation image.
+
+	Reading from it returns a list of supported options encoded as:
+
+	``platform``
+		Put the system into a special low-power state (e.g. ACPI S4) to
+		make additional wakeup options available and possibly allow the
+		platform firmware to take a simplified initialization path after
+		wakeup.
+
+		It is only available if the platform provides a special
+		mechanism to put the system to sleep after creating a
+		hibernation image (platforms with ACPI do that as a rule, for
+		example).
+
+	``shutdown``
+		Power off the system.
+
+	``reboot``
+		Reboot the system (useful for diagnostics mostly).
+
+	``suspend``
+		Hybrid system suspend.  Put the system into the suspend sleep
+		state selected through the ``mem_sleep`` file described above.
+		If the system is successfully woken up from that state, discard
+		the hibernation image and continue.  Otherwise, use the image
+		to restore the previous state of the system.
+
+		It is available if system suspend is supported.
+
+	``test_resume``
+		Diagnostic operation.  Load the image as though the system had
+		just woken up from hibernation and the currently running kernel
+		instance was a restore kernel and follow up with full system
+		resume.
+
+	Writing one of the strings listed above into this file causes the option
+	represented by it to be selected.
+
+	The currently selected option is shown in square brackets, which means
+	that the operation represented by it will be carried out after creating
+	and saving the image when hibernation is triggered by writing ``disk``
+	to :file:`/sys/power/state`.
+
+	If the kernel does not support hibernation, this file is not present.
+
+``image_size``
+	This file controls the size of hibernation images.
+
+	It can be written a string representing a non-negative integer that will
+	be used as a best-effort upper limit of the image size, in bytes.  The
+	hibernation core will do its best to ensure that the image size will not
+	exceed that number, but if that turns out to be impossible to achieve, a
+	hibernation image will still be created and its size will be as small as
+	possible.  In particular, writing '0' to this file causes the size of
+	hibernation images to be minimum.
+
+	Reading from it returns the current image size limit, which is set to
+	around 2/5 of the available RAM size by default.
+
+``pm_trace``
+	This file controls the "PM trace" mechanism saving the last suspend
+	or resume event point in the RTC memory across reboots.  It helps to
+	debug hard lockups or reboots due to device driver failures that occur
+	during system suspend or resume (which is more common) more effectively.
+
+	If it contains "1", the fingerprint of each suspend/resume event point
+	in turn will be stored in the RTC memory (overwriting the actual RTC
+	information), so it will survive a system crash if one occurs right
+	after storing it and it can be used later to identify the driver that
+	caused the crash to happen.
+
+	It contains "0" by default, which may be changed to "1" by writing a
+	string representing a nonzero integer into it.
+
+According to the above, there are two ways to make the system go into the
+:ref:`suspend-to-idle <s2idle>` state.  The first one is to write "freeze"
+directly to :file:`/sys/power/state`.  The second one is to write "s2idle" to
+:file:`/sys/power/mem_sleep` and then to write "mem" to
+:file:`/sys/power/state`.  Likewise, there are two ways to make the system go
+into the :ref:`standby <standby>` state (the strings to write to the control
+files in that case are "standby" or "shallow" and "mem", respectively) if that
+state is supported by the platform.  However, there is only one way to make the
+system go into the :ref:`suspend-to-RAM <s2ram>` state (write "deep" into
+:file:`/sys/power/mem_sleep` and "mem" into :file:`/sys/power/state`).
+
+The default suspend variant (ie. the one to be used without writing anything
+into :file:`/sys/power/mem_sleep`) is either "deep" (on the majority of systems
+supporting :ref:`suspend-to-RAM <s2ram>`) or "s2idle", but it can be overridden
+by the value of the ``mem_sleep_default`` parameter in the kernel command line.
+On some systems with ACPI, depending on the information in the ACPI tables, the
+default may be "s2idle" even if :ref:`suspend-to-RAM <s2ram>` is supported in
+principle.
diff --git a/Documentation/admin-guide/pm/strategies.rst b/Documentation/admin-guide/pm/strategies.rst
new file mode 100644
index 000000000..dd0362e32
--- /dev/null
+++ b/Documentation/admin-guide/pm/strategies.rst
@@ -0,0 +1,56 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===========================
+Power Management Strategies
+===========================
+
+:Copyright: |copy| 2017 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+The Linux kernel supports two major high-level power management strategies.
+
+One of them is based on using global low-power states of the whole system in
+which user space code cannot be executed and the overall system activity is
+significantly reduced, referred to as :doc:`sleep states <sleep-states>`.  The
+kernel puts the system into one of these states when requested by user space
+and the system stays in it until a special signal is received from one of
+designated devices, triggering a transition to the ``working state`` in which
+user space code can run.  Because sleep states are global and the whole system
+is affected by the state changes, this strategy is referred to as the
+:doc:`system-wide power management <system-wide>`.
+
+The other strategy, referred to as the :doc:`working-state power management
+<working-state>`, is based on adjusting the power states of individual hardware
+components of the system, as needed, in the working state.  In consequence, if
+this strategy is in use, the working state of the system usually does not
+correspond to any particular physical configuration of it, but can be treated as
+a metastate covering a range of different power states of the system in which
+the individual components of it can be either ``active`` (in use) or
+``inactive`` (idle).  If they are active, they have to be in power states
+allowing them to process data and to be accessed by software.  In turn, if they
+are inactive, ideally, they should be in low-power states in which they may not
+be accessible.
+
+If all of the system components are active, the system as a whole is regarded as
+"runtime active" and that situation typically corresponds to the maximum power
+draw (or maximum energy usage) of it.  If all of them are inactive, the system
+as a whole is regarded as "runtime idle" which may be very close to a sleep
+state from the physical system configuration and power draw perspective, but
+then it takes much less time and effort to start executing user space code than
+for the same system in a sleep state.  However, transitions from sleep states
+back to the working state can only be started by a limited set of devices, so
+typically the system can spend much more time in a sleep state than it can be
+runtime idle in one go.  For this reason, systems usually use less energy in
+sleep states than when they are runtime idle most of the time.
+
+Moreover, the two power management strategies address different usage scenarios.
+Namely, if the user indicates that the system will not be in use going forward,
+for example by closing its lid (if the system is a laptop), it probably should
+go into a sleep state at that point.  On the other hand, if the user simply goes
+away from the laptop keyboard, it probably should stay in the working state and
+use the working-state power management in case it becomes idle, because the user
+may come back to it at any time and then may want the system to be immediately
+accessible.
diff --git a/Documentation/admin-guide/pm/suspend-flows.rst b/Documentation/admin-guide/pm/suspend-flows.rst
new file mode 100644
index 000000000..c479d7462
--- /dev/null
+++ b/Documentation/admin-guide/pm/suspend-flows.rst
@@ -0,0 +1,270 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+=========================
+System Suspend Code Flows
+=========================
+
+:Copyright: |copy| 2020 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+At least one global system-wide transition needs to be carried out for the
+system to get from the working state into one of the supported
+:doc:`sleep states <sleep-states>`.  Hibernation requires more than one
+transition to occur for this purpose, but the other sleep states, commonly
+referred to as *system-wide suspend* (or simply *system suspend*) states, need
+only one.
+
+For those sleep states, the transition from the working state of the system into
+the target sleep state is referred to as *system suspend* too (in the majority
+of cases, whether this means a transition or a sleep state of the system should
+be clear from the context) and the transition back from the sleep state into the
+working state is referred to as *system resume*.
+
+The kernel code flows associated with the suspend and resume transitions for
+different sleep states of the system are quite similar, but there are some
+significant differences between the :ref:`suspend-to-idle <s2idle>` code flows
+and the code flows related to the :ref:`suspend-to-RAM <s2ram>` and
+:ref:`standby <standby>` sleep states.
+
+The :ref:`suspend-to-RAM <s2ram>` and :ref:`standby <standby>` sleep states
+cannot be implemented without platform support and the difference between them
+boils down to the platform-specific actions carried out by the suspend and
+resume hooks that need to be provided by the platform driver to make them
+available.  Apart from that, the suspend and resume code flows for these sleep
+states are mostly identical, so they both together will be referred to as
+*platform-dependent suspend* states in what follows.
+
+
+.. _s2idle_suspend:
+
+Suspend-to-idle Suspend Code Flow
+=================================
+
+The following steps are taken in order to transition the system from the working
+state to the :ref:`suspend-to-idle <s2idle>` sleep state:
+
+ 1. Invoking system-wide suspend notifiers.
+
+    Kernel subsystems can register callbacks to be invoked when the suspend
+    transition is about to occur and when the resume transition has finished.
+
+    That allows them to prepare for the change of the system state and to clean
+    up after getting back to the working state.
+
+ 2. Freezing tasks.
+
+    Tasks are frozen primarily in order to avoid unchecked hardware accesses
+    from user space through MMIO regions or I/O registers exposed directly to
+    it and to prevent user space from entering the kernel while the next step
+    of the transition is in progress (which might have been problematic for
+    various reasons).
+
+    All user space tasks are intercepted as though they were sent a signal and
+    put into uninterruptible sleep until the end of the subsequent system resume
+    transition.
+
+    The kernel threads that choose to be frozen during system suspend for
+    specific reasons are frozen subsequently, but they are not intercepted.
+    Instead, they are expected to periodically check whether or not they need
+    to be frozen and to put themselves into uninterruptible sleep if so.  [Note,
+    however, that kernel threads can use locking and other concurrency controls
+    available in kernel space to synchronize themselves with system suspend and
+    resume, which can be much more precise than the freezing, so the latter is
+    not a recommended option for kernel threads.]
+
+ 3. Suspending devices and reconfiguring IRQs.
+
+    Devices are suspended in four phases called *prepare*, *suspend*,
+    *late suspend* and *noirq suspend* (see :ref:`driverapi_pm_devices` for more
+    information on what exactly happens in each phase).
+
+    Every device is visited in each phase, but typically it is not physically
+    accessed in more than two of them.
+
+    The runtime PM API is disabled for every device during the *late* suspend
+    phase and high-level ("action") interrupt handlers are prevented from being
+    invoked before the *noirq* suspend phase.
+
+    Interrupts are still handled after that, but they are only acknowledged to
+    interrupt controllers without performing any device-specific actions that
+    would be triggered in the working state of the system (those actions are
+    deferred till the subsequent system resume transition as described
+    `below <s2idle_resume_>`_).
+
+    IRQs associated with system wakeup devices are "armed" so that the resume
+    transition of the system is started when one of them signals an event.
+
+ 4. Freezing the scheduler tick and suspending timekeeping.
+
+    When all devices have been suspended, CPUs enter the idle loop and are put
+    into the deepest available idle state.  While doing that, each of them
+    "freezes" its own scheduler tick so that the timer events associated with
+    the tick do not occur until the CPU is woken up by another interrupt source.
+
+    The last CPU to enter the idle state also stops the timekeeping which
+    (among other things) prevents high resolution timers from triggering going
+    forward until the first CPU that is woken up restarts the timekeeping.
+    That allows the CPUs to stay in the deep idle state relatively long in one
+    go.
+
+    From this point on, the CPUs can only be woken up by non-timer hardware
+    interrupts.  If that happens, they go back to the idle state unless the
+    interrupt that woke up one of them comes from an IRQ that has been armed for
+    system wakeup, in which case the system resume transition is started.
+
+
+.. _s2idle_resume:
+
+Suspend-to-idle Resume Code Flow
+================================
+
+The following steps are taken in order to transition the system from the
+:ref:`suspend-to-idle <s2idle>` sleep state into the working state:
+
+ 1. Resuming timekeeping and unfreezing the scheduler tick.
+
+    When one of the CPUs is woken up (by a non-timer hardware interrupt), it
+    leaves the idle state entered in the last step of the preceding suspend
+    transition, restarts the timekeeping (unless it has been restarted already
+    by another CPU that woke up earlier) and the scheduler tick on that CPU is
+    unfrozen.
+
+    If the interrupt that has woken up the CPU was armed for system wakeup,
+    the system resume transition begins.
+
+ 2. Resuming devices and restoring the working-state configuration of IRQs.
+
+    Devices are resumed in four phases called *noirq resume*, *early resume*,
+    *resume* and *complete* (see :ref:`driverapi_pm_devices` for more
+    information on what exactly happens in each phase).
+
+    Every device is visited in each phase, but typically it is not physically
+    accessed in more than two of them.
+
+    The working-state configuration of IRQs is restored after the *noirq* resume
+    phase and the runtime PM API is re-enabled for every device whose driver
+    supports it during the *early* resume phase.
+
+ 3. Thawing tasks.
+
+    Tasks frozen in step 2 of the preceding `suspend <s2idle_suspend_>`_
+    transition are "thawed", which means that they are woken up from the
+    uninterruptible sleep that they went into at that time and user space tasks
+    are allowed to exit the kernel.
+
+ 4. Invoking system-wide resume notifiers.
+
+    This is analogous to step 1 of the `suspend <s2idle_suspend_>`_ transition
+    and the same set of callbacks is invoked at this point, but a different
+    "notification type" parameter value is passed to them.
+
+
+Platform-dependent Suspend Code Flow
+====================================
+
+The following steps are taken in order to transition the system from the working
+state to platform-dependent suspend state:
+
+ 1. Invoking system-wide suspend notifiers.
+
+    This step is the same as step 1 of the suspend-to-idle suspend transition
+    described `above <s2idle_suspend_>`_.
+
+ 2. Freezing tasks.
+
+    This step is the same as step 2 of the suspend-to-idle suspend transition
+    described `above <s2idle_suspend_>`_.
+
+ 3. Suspending devices and reconfiguring IRQs.
+
+    This step is analogous to step 3 of the suspend-to-idle suspend transition
+    described `above <s2idle_suspend_>`_, but the arming of IRQs for system
+    wakeup generally does not have any effect on the platform.
+
+    There are platforms that can go into a very deep low-power state internally
+    when all CPUs in them are in sufficiently deep idle states and all I/O
+    devices have been put into low-power states.  On those platforms,
+    suspend-to-idle can reduce system power very effectively.
+
+    On the other platforms, however, low-level components (like interrupt
+    controllers) need to be turned off in a platform-specific way (implemented
+    in the hooks provided by the platform driver) to achieve comparable power
+    reduction.
+
+    That usually prevents in-band hardware interrupts from waking up the system,
+    which must be done in a special platform-dependent way.  Then, the
+    configuration of system wakeup sources usually starts when system wakeup
+    devices are suspended and is finalized by the platform suspend hooks later
+    on.
+
+ 4. Disabling non-boot CPUs.
+
+    On some platforms the suspend hooks mentioned above must run in a one-CPU
+    configuration of the system (in particular, the hardware cannot be accessed
+    by any code running in parallel with the platform suspend hooks that may,
+    and often do, trap into the platform firmware in order to finalize the
+    suspend transition).
+
+    For this reason, the CPU offline/online (CPU hotplug) framework is used
+    to take all of the CPUs in the system, except for one (the boot CPU),
+    offline (typically, the CPUs that have been taken offline go into deep idle
+    states).
+
+    This means that all tasks are migrated away from those CPUs and all IRQs are
+    rerouted to the only CPU that remains online.
+
+ 5. Suspending core system components.
+
+    This prepares the core system components for (possibly) losing power going
+    forward and suspends the timekeeping.
+
+ 6. Platform-specific power removal.
+
+    This is expected to remove power from all of the system components except
+    for the memory controller and RAM (in order to preserve the contents of the
+    latter) and some devices designated for system wakeup.
+
+    In many cases control is passed to the platform firmware which is expected
+    to finalize the suspend transition as needed.
+
+
+Platform-dependent Resume Code Flow
+===================================
+
+The following steps are taken in order to transition the system from a
+platform-dependent suspend state into the working state:
+
+ 1. Platform-specific system wakeup.
+
+    The platform is woken up by a signal from one of the designated system
+    wakeup devices (which need not be an in-band hardware interrupt)  and
+    control is passed back to the kernel (the working configuration of the
+    platform may need to be restored by the platform firmware before the
+    kernel gets control again).
+
+ 2. Resuming core system components.
+
+    The suspend-time configuration of the core system components is restored and
+    the timekeeping is resumed.
+
+ 3. Re-enabling non-boot CPUs.
+
+    The CPUs disabled in step 4 of the preceding suspend transition are taken
+    back online and their suspend-time configuration is restored.
+
+ 4. Resuming devices and restoring the working-state configuration of IRQs.
+
+    This step is the same as step 2 of the suspend-to-idle suspend transition
+    described `above <s2idle_resume_>`_.
+
+ 5. Thawing tasks.
+
+    This step is the same as step 3 of the suspend-to-idle suspend transition
+    described `above <s2idle_resume_>`_.
+
+ 6. Invoking system-wide resume notifiers.
+
+    This step is the same as step 4 of the suspend-to-idle suspend transition
+    described `above <s2idle_resume_>`_.
diff --git a/Documentation/admin-guide/pm/system-wide.rst b/Documentation/admin-guide/pm/system-wide.rst
new file mode 100644
index 000000000..1a1924d71
--- /dev/null
+++ b/Documentation/admin-guide/pm/system-wide.rst
@@ -0,0 +1,11 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============================
+System-Wide Power Management
+============================
+
+.. toctree::
+   :maxdepth: 2
+
+   sleep-states
+   suspend-flows
diff --git a/Documentation/admin-guide/pm/working-state.rst b/Documentation/admin-guide/pm/working-state.rst
new file mode 100644
index 000000000..ee4588781
--- /dev/null
+++ b/Documentation/admin-guide/pm/working-state.rst
@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================
+Working-State Power Management
+==============================
+
+.. toctree::
+   :maxdepth: 2
+
+   cpuidle
+   intel_idle
+   cpufreq
+   intel_pstate
+   amd-pstate
+   cpufreq_drivers
+   intel_epb
+   intel-speed-select
+   intel_uncore_frequency_scaling
diff --git a/Documentation/admin-guide/pnp.rst b/Documentation/admin-guide/pnp.rst
new file mode 100644
index 000000000..24d80e3eb
--- /dev/null
+++ b/Documentation/admin-guide/pnp.rst
@@ -0,0 +1,285 @@
+=================================
+Linux Plug and Play Documentation
+=================================
+
+:Author: Adam Belay <ambx1@neo.rr.com>
+:Last updated: Oct. 16, 2002
+
+
+Overview
+--------
+
+Plug and Play provides a means of detecting and setting resources for legacy or
+otherwise unconfigurable devices.  The Linux Plug and Play Layer provides these 
+services to compatible drivers.
+
+
+The User Interface
+------------------
+
+The Linux Plug and Play user interface provides a means to activate PnP devices
+for legacy and user level drivers that do not support Linux Plug and Play.  The 
+user interface is integrated into sysfs.
+
+In addition to the standard sysfs file the following are created in each
+device's directory:
+- id - displays a list of support EISA IDs
+- options - displays possible resource configurations
+- resources - displays currently allocated resources and allows resource changes
+
+activating a device
+^^^^^^^^^^^^^^^^^^^
+
+::
+
+	# echo "auto" > resources
+
+this will invoke the automatic resource config system to activate the device
+
+manually activating a device
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+	# echo "manual <depnum> <mode>" > resources
+
+	<depnum> - the configuration number
+	<mode> - static or dynamic
+		 static = for next boot
+		 dynamic = now
+
+disabling a device
+^^^^^^^^^^^^^^^^^^
+
+::
+
+	# echo "disable" > resources
+
+
+EXAMPLE:
+
+Suppose you need to activate the floppy disk controller.
+
+1. change to the proper directory, in my case it is
+   /driver/bus/pnp/devices/00:0f::
+
+	# cd /driver/bus/pnp/devices/00:0f
+	# cat name
+	PC standard floppy disk controller
+
+2. check if the device is already active::
+
+	# cat resources
+	DISABLED
+
+  - Notice the string "DISABLED".  This means the device is not active.
+
+3. check the device's possible configurations (optional)::
+
+	# cat options
+	Dependent: 01 - Priority acceptable
+	    port 0x3f0-0x3f0, align 0x7, size 0x6, 16-bit address decoding
+	    port 0x3f7-0x3f7, align 0x0, size 0x1, 16-bit address decoding
+	    irq 6
+	    dma 2 8-bit compatible
+	Dependent: 02 - Priority acceptable
+	    port 0x370-0x370, align 0x7, size 0x6, 16-bit address decoding
+	    port 0x377-0x377, align 0x0, size 0x1, 16-bit address decoding
+	    irq 6
+	    dma 2 8-bit compatible
+
+4. now activate the device::
+
+	# echo "auto" > resources
+
+5. finally check if the device is active::
+
+	# cat resources
+	io 0x3f0-0x3f5
+	io 0x3f7-0x3f7
+	irq 6
+	dma 2
+
+also there are a series of kernel parameters::
+
+	pnp_reserve_irq=irq1[,irq2] ....
+	pnp_reserve_dma=dma1[,dma2] ....
+	pnp_reserve_io=io1,size1[,io2,size2] ....
+	pnp_reserve_mem=mem1,size1[,mem2,size2] ....
+
+
+
+The Unified Plug and Play Layer
+-------------------------------
+
+All Plug and Play drivers, protocols, and services meet at a central location
+called the Plug and Play Layer.  This layer is responsible for the exchange of 
+information between PnP drivers and PnP protocols.  Thus it automatically 
+forwards commands to the proper protocol.  This makes writing PnP drivers 
+significantly easier.
+
+The following functions are available from the Plug and Play Layer:
+
+pnp_get_protocol
+  increments the number of uses by one
+
+pnp_put_protocol
+  deincrements the number of uses by one
+
+pnp_register_protocol
+  use this to register a new PnP protocol
+
+pnp_register_driver
+  adds a PnP driver to the Plug and Play Layer
+
+  this includes driver model integration
+  returns zero for success or a negative error number for failure; count
+  calls to the .add() method if you need to know how many devices bind to
+  the driver
+
+pnp_unregister_driver
+  removes a PnP driver from the Plug and Play Layer
+
+
+
+Plug and Play Protocols
+-----------------------
+
+This section contains information for PnP protocol developers.
+
+The following Protocols are currently available in the computing world:
+
+- PNPBIOS:
+    used for system devices such as serial and parallel ports.
+- ISAPNP:
+    provides PnP support for the ISA bus
+- ACPI:
+    among its many uses, ACPI provides information about system level
+    devices.
+
+It is meant to replace the PNPBIOS.  It is not currently supported by Linux
+Plug and Play but it is planned to be in the near future.
+
+
+Requirements for a Linux PnP protocol:
+1. the protocol must use EISA IDs
+2. the protocol must inform the PnP Layer of a device's current configuration
+
+- the ability to set resources is optional but preferred.
+
+The following are PnP protocol related functions:
+
+pnp_add_device
+  use this function to add a PnP device to the PnP layer
+
+  only call this function when all wanted values are set in the pnp_dev
+  structure
+
+pnp_init_device
+  call this to initialize the PnP structure
+
+pnp_remove_device
+  call this to remove a device from the Plug and Play Layer.
+  it will fail if the device is still in use.
+  automatically will free mem used by the device and related structures
+
+pnp_add_id
+  adds an EISA ID to the list of supported IDs for the specified device
+
+For more information consult the source of a protocol such as
+/drivers/pnp/pnpbios/core.c.
+
+
+
+Linux Plug and Play Drivers
+---------------------------
+
+This section contains information for Linux PnP driver developers.
+
+The New Way
+^^^^^^^^^^^
+
+1. first make a list of supported EISA IDS
+
+   ex::
+
+	static const struct pnp_id pnp_dev_table[] = {
+		/* Standard LPT Printer Port */
+		{.id = "PNP0400", .driver_data = 0},
+		/* ECP Printer Port */
+		{.id = "PNP0401", .driver_data = 0},
+		{.id = ""}
+	};
+
+   Please note that the character 'X' can be used as a wild card in the function
+   portion (last four characters).
+
+   ex::
+
+	/* Unknown PnP modems */
+	{	"PNPCXXX",		UNKNOWN_DEV	},
+
+   Supported PnP card IDs can optionally be defined.
+   ex::
+
+	static const struct pnp_id pnp_card_table[] = {
+		{	"ANYDEVS",		0	},
+		{	"",			0	}
+	};
+
+2. Optionally define probe and remove functions.  It may make sense not to
+   define these functions if the driver already has a reliable method of detecting
+   the resources, such as the parport_pc driver.
+
+   ex::
+
+	static int
+	serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const
+			struct pnp_id *dev_id)
+	{
+	. . .
+
+   ex::
+
+	static void serial_pnp_remove(struct pnp_dev * dev)
+	{
+	. . .
+
+   consult /drivers/serial/8250_pnp.c for more information.
+
+3. create a driver structure
+
+   ex::
+
+	static struct pnp_driver serial_pnp_driver = {
+		.name		= "serial",
+		.card_id_table	= pnp_card_table,
+		.id_table	= pnp_dev_table,
+		.probe		= serial_pnp_probe,
+		.remove		= serial_pnp_remove,
+	};
+
+   * name and id_table cannot be NULL.
+
+4. register the driver
+
+   ex::
+
+	static int __init serial8250_pnp_init(void)
+	{
+		return pnp_register_driver(&serial_pnp_driver);
+	}
+
+The Old Way
+^^^^^^^^^^^
+
+A series of compatibility functions have been created to make it easy to convert
+ISAPNP drivers.  They should serve as a temporary solution only.
+
+They are as follows::
+
+	struct pnp_dev *pnp_find_dev(struct pnp_card *card,
+				     unsigned short vendor,
+				     unsigned short function,
+				     struct pnp_dev *from)
+
diff --git a/Documentation/admin-guide/pstore-blk.rst b/Documentation/admin-guide/pstore-blk.rst
new file mode 100644
index 000000000..1bb2a1c29
--- /dev/null
+++ b/Documentation/admin-guide/pstore-blk.rst
@@ -0,0 +1,234 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+pstore block oops/panic logger
+==============================
+
+Introduction
+------------
+
+pstore block (pstore/blk) is an oops/panic logger that writes its logs to a
+block device and non-block device before the system crashes. You can get
+these log files by mounting pstore filesystem like::
+
+    mount -t pstore pstore /sys/fs/pstore
+
+
+pstore block concepts
+---------------------
+
+pstore/blk provides efficient configuration method for pstore/blk, which
+divides all configurations into two parts, configurations for user and
+configurations for driver.
+
+Configurations for user determine how pstore/blk works, such as pmsg_size,
+kmsg_size and so on. All of them support both Kconfig and module parameters,
+but module parameters have priority over Kconfig.
+
+Configurations for driver are all about block device and non-block device,
+such as total_size of block device and read/write operations.
+
+Configurations for user
+-----------------------
+
+All of these configurations support both Kconfig and module parameters, but
+module parameters have priority over Kconfig.
+
+Here is an example for module parameters::
+
+        pstore_blk.blkdev=/dev/mmcblk0p7 pstore_blk.kmsg_size=64 best_effort=y
+
+The detail of each configurations may be of interest to you.
+
+blkdev
+~~~~~~
+
+The block device to use. Most of the time, it is a partition of block device.
+It's required for pstore/blk. It is also used for MTD device.
+
+When pstore/blk is built as a module, "blkdev" accepts the following variants:
+
+1. /dev/<disk_name> represents the device number of disk
+#. /dev/<disk_name><decimal> represents the device number of partition - device
+   number of disk plus the partition number
+#. /dev/<disk_name>p<decimal> - same as the above; this form is used when disk
+   name of partitioned disk ends with a digit.
+
+When pstore/blk is built into the kernel, "blkdev" accepts the following variants:
+
+#. <hex_major><hex_minor> device number in hexadecimal representation,
+   with no leading 0x, for example b302.
+#. PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF represents the unique id of
+   a partition if the partition table provides it. The UUID may be either an
+   EFI/GPT UUID, or refer to an MSDOS partition using the format SSSSSSSS-PP,
+   where SSSSSSSS is a zero-filled hex representation of the 32-bit
+   "NT disk signature", and PP is a zero-filled hex representation of the
+   1-based partition number.
+#. PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to a
+   partition with a known unique id.
+#. <major>:<minor> major and minor number of the device separated by a colon.
+
+It accepts the following variants for MTD device:
+
+1. <device name> MTD device name. "pstore" is recommended.
+#. <device number> MTD device number.
+
+kmsg_size
+~~~~~~~~~
+
+The chunk size in KB for oops/panic front-end. It **MUST** be a multiple of 4.
+It's optional if you do not care about the oops/panic log.
+
+There are multiple chunks for oops/panic front-end depending on the remaining
+space except other pstore front-ends.
+
+pstore/blk will log to oops/panic chunks one by one, and always overwrite the
+oldest chunk if there is no more free chunk.
+
+pmsg_size
+~~~~~~~~~
+
+The chunk size in KB for pmsg front-end. It **MUST** be a multiple of 4.
+It's optional if you do not care about the pmsg log.
+
+Unlike oops/panic front-end, there is only one chunk for pmsg front-end.
+
+Pmsg is a user space accessible pstore object. Writes to */dev/pmsg0* are
+appended to the chunk. On reboot the contents are available in
+*/sys/fs/pstore/pmsg-pstore-blk-0*.
+
+console_size
+~~~~~~~~~~~~
+
+The chunk size in KB for console front-end.  It **MUST** be a multiple of 4.
+It's optional if you do not care about the console log.
+
+Similar to pmsg front-end, there is only one chunk for console front-end.
+
+All log of console will be appended to the chunk. On reboot the contents are
+available in */sys/fs/pstore/console-pstore-blk-0*.
+
+ftrace_size
+~~~~~~~~~~~
+
+The chunk size in KB for ftrace front-end. It **MUST** be a multiple of 4.
+It's optional if you do not care about the ftrace log.
+
+Similar to oops front-end, there are multiple chunks for ftrace front-end
+depending on the count of cpu processors. Each chunk size is equal to
+ftrace_size / processors_count.
+
+All log of ftrace will be appended to the chunk. On reboot the contents are
+combined and available in */sys/fs/pstore/ftrace-pstore-blk-0*.
+
+Persistent function tracing might be useful for debugging software or hardware
+related hangs. Here is an example of usage::
+
+ # mount -t pstore pstore /sys/fs/pstore
+ # mount -t debugfs debugfs /sys/kernel/debug/
+ # echo 1 > /sys/kernel/debug/pstore/record_ftrace
+ # reboot -f
+ [...]
+ # mount -t pstore pstore /sys/fs/pstore
+ # tail /sys/fs/pstore/ftrace-pstore-blk-0
+ CPU:0 ts:5914676 c0063828  c0063b94  call_cpuidle <- cpu_startup_entry+0x1b8/0x1e0
+ CPU:0 ts:5914678 c039ecdc  c006385c  cpuidle_enter_state <- call_cpuidle+0x44/0x48
+ CPU:0 ts:5914680 c039e9a0  c039ecf0  cpuidle_enter_freeze <- cpuidle_enter_state+0x304/0x314
+ CPU:0 ts:5914681 c0063870  c039ea30  sched_idle_set_state <- cpuidle_enter_state+0x44/0x314
+ CPU:1 ts:5916720 c0160f59  c015ee04  kernfs_unmap_bin_file <- __kernfs_remove+0x140/0x204
+ CPU:1 ts:5916721 c05ca625  c015ee0c  __mutex_lock_slowpath <- __kernfs_remove+0x148/0x204
+ CPU:1 ts:5916723 c05c813d  c05ca630  yield_to <- __mutex_lock_slowpath+0x314/0x358
+ CPU:1 ts:5916724 c05ca2d1  c05ca638  __ww_mutex_lock <- __mutex_lock_slowpath+0x31c/0x358
+
+max_reason
+~~~~~~~~~~
+
+Limiting which kinds of kmsg dumps are stored can be controlled via
+the ``max_reason`` value, as defined in include/linux/kmsg_dump.h's
+``enum kmsg_dump_reason``. For example, to store both Oopses and Panics,
+``max_reason`` should be set to 2 (KMSG_DUMP_OOPS), to store only Panics
+``max_reason`` should be set to 1 (KMSG_DUMP_PANIC). Setting this to 0
+(KMSG_DUMP_UNDEF), means the reason filtering will be controlled by the
+``printk.always_kmsg_dump`` boot param: if unset, it'll be KMSG_DUMP_OOPS,
+otherwise KMSG_DUMP_MAX.
+
+Configurations for driver
+-------------------------
+
+A device driver uses ``register_pstore_device`` with
+``struct pstore_device_info`` to register to pstore/blk.
+
+.. kernel-doc:: fs/pstore/blk.c
+   :export:
+
+Compression and header
+----------------------
+
+Block device is large enough for uncompressed oops data. Actually we do not
+recommend data compression because pstore/blk will insert some information into
+the first line of oops/panic data. For example::
+
+        Panic: Total 16 times
+
+It means that it's OOPS|Panic for the 16th time since the first booting.
+Sometimes the number of occurrences of oops|panic since the first booting is
+important to judge whether the system is stable.
+
+The following line is inserted by pstore filesystem. For example::
+
+        Oops#2 Part1
+
+It means that it's OOPS for the 2nd time on the last boot.
+
+Reading the data
+----------------
+
+The dump data can be read from the pstore filesystem. The format for these
+files is ``dmesg-pstore-blk-[N]`` for oops/panic front-end,
+``pmsg-pstore-blk-0`` for pmsg front-end and so on.  The timestamp of the
+dump file records the trigger time. To delete a stored record from block
+device, simply unlink the respective pstore file.
+
+Attentions in panic read/write APIs
+-----------------------------------
+
+If on panic, the kernel is not going to run for much longer, the tasks will not
+be scheduled and most kernel resources will be out of service. It
+looks like a single-threaded program running on a single-core computer.
+
+The following points require special attention for panic read/write APIs:
+
+1. Can **NOT** allocate any memory.
+   If you need memory, just allocate while the block driver is initializing
+   rather than waiting until the panic.
+#. Must be polled, **NOT** interrupt driven.
+   No task schedule any more. The block driver should delay to ensure the write
+   succeeds, but NOT sleep.
+#. Can **NOT** take any lock.
+   There is no other task, nor any shared resource; you are safe to break all
+   locks.
+#. Just use CPU to transfer.
+   Do not use DMA to transfer unless you are sure that DMA will not keep lock.
+#. Control registers directly.
+   Please control registers directly rather than use Linux kernel resources.
+   Do I/O map while initializing rather than wait until a panic occurs.
+#. Reset your block device and controller if necessary.
+   If you are not sure of the state of your block device and controller when
+   a panic occurs, you are safe to stop and reset them.
+
+pstore/blk supports psblk_blkdev_info(), which is defined in
+*linux/pstore_blk.h*, to get information of using block device, such as the
+device number, sector count and start sector of the whole disk.
+
+pstore block internals
+----------------------
+
+For developer reference, here are all the important structures and APIs:
+
+.. kernel-doc:: fs/pstore/zone.c
+   :internal:
+
+.. kernel-doc:: include/linux/pstore_zone.h
+   :internal:
+
+.. kernel-doc:: include/linux/pstore_blk.h
+   :internal:
diff --git a/Documentation/admin-guide/quickly-build-trimmed-linux.rst b/Documentation/admin-guide/quickly-build-trimmed-linux.rst
new file mode 100644
index 000000000..3432dc8e1
--- /dev/null
+++ b/Documentation/admin-guide/quickly-build-trimmed-linux.rst
@@ -0,0 +1,1099 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+.. [see the bottom of this file for redistribution information]
+
+===========================================
+How to quickly build a trimmed Linux kernel
+===========================================
+
+This guide explains how to swiftly build Linux kernels that are ideal for
+testing purposes, but perfectly fine for day-to-day use, too.
+
+The essence of the process (aka 'TL;DR')
+========================================
+
+*[If you are new to compiling Linux, ignore this TLDR and head over to the next
+section below: it contains a step-by-step guide, which is more detailed, but
+still brief and easy to follow; that guide and its accompanying reference
+section also mention alternatives, pitfalls, and additional aspects, all of
+which might be relevant for you.]*
+
+If your system uses techniques like Secure Boot, prepare it to permit starting
+self-compiled Linux kernels; install compilers and everything else needed for
+building Linux; make sure to have 12 Gigabyte free space in your home directory.
+Now run the following commands to download fresh Linux mainline sources, which
+you then use to configure, build and install your own kernel::
+
+    git clone --depth 1 -b master \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git ~/linux/
+    cd ~/linux/
+    # Hint: if you want to apply patches, do it at this point. See below for details.
+    # Hint: it's recommended to tag your build at this point. See below for details.
+    yes "" | make localmodconfig
+    # Hint: at this point you might want to adjust the build configuration; you'll
+    #   have to, if you are running Debian. See below for details.
+    make -j $(nproc --all)
+    # Note: on many commodity distributions the next command suffices, but on Arch
+    #   Linux, its derivatives, and some others it does not. See below for details.
+    command -v installkernel && sudo make modules_install install
+    reboot
+
+If you later want to build a newer mainline snapshot, use these commands::
+
+    cd ~/linux/
+    git fetch --depth 1 origin
+    # Note: the next command will discard any changes you did to the code:
+    git checkout --force --detach origin/master
+    # Reminder: if you want to (re)apply patches, do it at this point.
+    # Reminder: you might want to add or modify a build tag at this point.
+    make olddefconfig
+    make -j $(nproc --all)
+    # Reminder: the next command on some distributions does not suffice.
+    command -v installkernel && sudo make modules_install install
+    reboot
+
+Step-by-step guide
+==================
+
+Compiling your own Linux kernel is easy in principle. There are various ways to
+do it. Which of them actually work and is the best depends on the circumstances.
+
+This guide describes a way perfectly suited for those who want to quickly
+install Linux from sources without being bothered by complicated details; the
+goal is to cover everything typically needed on mainstream Linux distributions
+running on commodity PC or server hardware.
+
+The described approach is great for testing purposes, for example to try a
+proposed fix or to check if a problem was already fixed in the latest codebase.
+Nonetheless, kernels built this way are also totally fine for day-to-day use
+while at the same time being easy to keep up to date.
+
+The following steps describe the important aspects of the process; a
+comprehensive reference section later explains each of them in more detail. It
+sometimes also describes alternative approaches, pitfalls, as well as errors
+that might occur at a particular point -- and how to then get things rolling
+again.
+
+..
+   Note: if you see this note, you are reading the text's source file. You
+   might want to switch to a rendered version, as it makes it a lot easier to
+   quickly look something up in the reference section and afterwards jump back
+   to where you left off. Find a the latest rendered version here:
+   https://docs.kernel.org/admin-guide/quickly-build-trimmed-linux.html
+
+.. _backup_sbs:
+
+ * Create a fresh backup and put system repair and restore tools at hand, just
+   to be prepared for the unlikely case of something going sideways.
+
+   [:ref:`details<backup>`]
+
+.. _secureboot_sbs:
+
+ * On platforms with 'Secure Boot' or similar techniques, prepare everything to
+   ensure the system will permit your self-compiled kernel to boot later. The
+   quickest and easiest way to achieve this on commodity x86 systems is to
+   disable such techniques in the BIOS setup utility; alternatively, remove
+   their restrictions through a process initiated by
+   ``mokutil --disable-validation``.
+
+   [:ref:`details<secureboot>`]
+
+.. _buildrequires_sbs:
+
+ * Install all software required to build a Linux kernel. Often you will need:
+   'bc', 'binutils' ('ld' et al.), 'bison', 'flex', 'gcc', 'git', 'openssl',
+   'pahole', 'perl', and the development headers for 'libelf' and 'openssl'. The
+   reference section shows how to quickly install those on various popular Linux
+   distributions.
+
+   [:ref:`details<buildrequires>`]
+
+.. _diskspace_sbs:
+
+ * Ensure to have enough free space for building and installing Linux. For the
+   latter 150 Megabyte in /lib/ and 100 in /boot/ are a safe bet. For storing
+   sources and build artifacts 12 Gigabyte in your home directory should
+   typically suffice. If you have less available, be sure to check the reference
+   section for the step that explains adjusting your kernels build
+   configuration: it mentions a trick that reduce the amount of required space
+   in /home/ to around 4 Gigabyte.
+
+   [:ref:`details<diskspace>`]
+
+.. _sources_sbs:
+
+ * Retrieve the sources of the Linux version you intend to build; then change
+   into the directory holding them, as all further commands in this guide are
+   meant to be executed from there.
+
+   *[Note: the following paragraphs describe how to retrieve the sources by
+   partially cloning the Linux stable git repository. This is called a shallow
+   clone. The reference section explains two alternatives:* :ref:`packaged
+   archives<sources_archive>` *and* :ref:`a full git clone<sources_full>` *;
+   prefer the latter, if downloading a lot of data does not bother you, as that
+   will avoid some* :ref:`peculiar characteristics of shallow clones the
+   reference section explains<sources_shallow>` *.]*
+
+   First, execute the following command to retrieve a fresh mainline codebase::
+
+     git clone --no-checkout --depth 1 -b master \
+       https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git ~/linux/
+     cd ~/linux/
+
+   If you want to access recent mainline releases and pre-releases, deepen you
+   clone's history to the oldest mainline version you are interested in::
+
+     git fetch --shallow-exclude=v6.0 origin
+
+   In case you want to access a stable/longterm release (say v6.1.5), simply add
+   the branch holding that series; afterwards fetch the history at least up to
+   the mainline version that started the series (v6.1)::
+
+     git remote set-branches --add origin linux-6.1.y
+     git fetch --shallow-exclude=v6.0 origin
+
+   Now checkout the code you are interested in. If you just performed the
+   initial clone, you will be able to check out a fresh mainline codebase, which
+   is ideal for checking whether developers already fixed an issue::
+
+      git checkout --detach origin/master
+
+   If you deepened your clone, you instead of ``origin/master`` can specify the
+   version you deepened to (``v6.0`` above); later releases like ``v6.1`` and
+   pre-release like ``v6.2-rc1`` will work, too. Stable or longterm versions
+   like ``v6.1.5`` work just the same, if you added the appropriate
+   stable/longterm branch as described.
+
+   [:ref:`details<sources>`]
+
+.. _patching_sbs:
+
+ * In case you want to apply a kernel patch, do so now. Often a command like
+   this will do the trick::
+
+     patch -p1 < ../proposed-fix.patch
+
+   If the ``-p1`` is actually needed, depends on how the patch was created; in
+   case it does not apply thus try without it.
+
+   If you cloned the sources with git and anything goes sideways, run ``git
+   reset --hard`` to undo any changes to the sources.
+
+   [:ref:`details<patching>`]
+
+.. _tagging_sbs:
+
+ * If you patched your kernel or have one of the same version installed already,
+   better add a unique tag to the one you are about to build::
+
+     echo "-proposed_fix" > localversion
+
+   Running ``uname -r`` under your kernel later will then print something like
+   '6.1-rc4-proposed_fix'.
+
+   [:ref:`details<tagging>`]
+
+ .. _configuration_sbs:
+
+ * Create the build configuration for your kernel based on an existing
+   configuration.
+
+   If you already prepared such a '.config' file yourself, copy it to
+   ~/linux/ and run ``make olddefconfig``.
+
+   Use the same command, if your distribution or somebody else already tailored
+   your running kernel to your or your hardware's needs: the make target
+   'olddefconfig' will then try to use that kernel's .config as base.
+
+   Using this make target is fine for everybody else, too -- but you often can
+   save a lot of time by using this command instead::
+
+     yes "" | make localmodconfig
+
+   This will try to pick your distribution's kernel as base, but then disable
+   modules for any features apparently superfluous for your setup. This will
+   reduce the compile time enormously, especially if you are running an
+   universal kernel from a commodity Linux distribution.
+
+   There is a catch: 'localmodconfig' is likely to disable kernel features you
+   did not use since you booted your Linux -- like drivers for currently
+   disconnected peripherals or virtualization software not currently in use.
+   You can reduce or nearly eliminate that risk with tricks the reference
+   section outlines; but when building a kernel just for quick testing purposes
+   it is often negligible if such features are missing. But you should keep that
+   aspect in mind when using a kernel built with this make target, as it might
+   be the reason why something you only use occasionally stopped working.
+
+   [:ref:`details<configuration>`]
+
+.. _configmods_sbs:
+
+ * Check if you might want to or have to adjust some kernel configuration
+   options:
+
+  * Evaluate how you want to handle debug symbols. Enable them, if you later
+    might need to decode a stack trace found for example in a 'panic', 'Oops',
+    'warning', or 'BUG'; on the other hand disable them, if you are short on
+    storage space or prefer a smaller kernel binary. See the reference section
+    for details on how to do either. If neither applies, it will likely be fine
+    to simply not bother with this. [:ref:`details<configmods_debugsymbols>`]
+
+  * Are you running Debian? Then to avoid known problems by performing
+    additional adjustments explained in the reference section.
+    [:ref:`details<configmods_distros>`].
+
+  * If you want to influence the other aspects of the configuration, do so now
+    by using make targets like 'menuconfig' or 'xconfig'.
+    [:ref:`details<configmods_individual>`].
+
+.. _build_sbs:
+
+ * Build the image and the modules of your kernel::
+
+     make -j $(nproc --all)
+
+   If you want your kernel packaged up as deb, rpm, or tar file, see the
+   reference section for alternatives.
+
+   [:ref:`details<build>`]
+
+.. _install_sbs:
+
+ * Now install your kernel::
+
+     command -v installkernel && sudo make modules_install install
+
+   Often all left for you to do afterwards is a ``reboot``, as many commodity
+   Linux distributions will then create an initramfs (also known as initrd) and
+   an entry for your kernel in your bootloader's configuration; but on some
+   distributions you have to take care of these two steps manually for reasons
+   the reference section explains.
+
+   On a few distributions like Arch Linux and its derivatives the above command
+   does nothing at all; in that case you have to manually install your kernel,
+   as outlined in the reference section.
+
+   If you are running an immutable Linux distribution, check its documentation
+   and the web to find out how to install your own kernel there.
+
+   [:ref:`details<install>`]
+
+.. _another_sbs:
+
+ * To later build another kernel you need similar steps, but sometimes slightly
+   different commands.
+
+   First, switch back into the sources tree::
+
+      cd ~/linux/
+
+   In case you want to build a version from a stable/longterm series you have
+   not used yet (say 6.2.y), tell git to track it::
+
+      git remote set-branches --add origin linux-6.2.y
+
+   Now fetch the latest upstream changes; you again need to specify the earliest
+   version you care about, as git otherwise might retrieve the entire commit
+   history::
+
+     git fetch --shallow-exclude=v6.0 origin
+
+   Now switch to the version you are interested in -- but be aware the command
+   used here will discard any modifications you performed, as they would
+   conflict with the sources you want to checkout::
+
+     git checkout --force --detach origin/master
+
+   At this point you might want to patch the sources again or set/modify a build
+   tag, as explained earlier. Afterwards adjust the build configuration to the
+   new codebase using olddefconfig, which will now adjust the configuration file
+   you prepared earlier using localmodconfig  (~/linux/.config) for your next
+   kernel::
+
+     # reminder: if you want to apply patches, do it at this point
+     # reminder: you might want to update your build tag at this point
+     make olddefconfig
+
+   Now build your kernel::
+
+     make -j $(nproc --all)
+
+   Afterwards install the kernel as outlined above::
+
+     command -v installkernel && sudo make modules_install install
+
+   [:ref:`details<another>`]
+
+.. _uninstall_sbs:
+
+ * Your kernel is easy to remove later, as its parts are only stored in two
+   places and clearly identifiable by the kernel's release name. Just ensure to
+   not delete the kernel you are running, as that might render your system
+   unbootable.
+
+   Start by deleting the directory holding your kernel's modules, which is named
+   after its release name -- '6.0.1-foobar' in the following example::
+
+     sudo rm -rf /lib/modules/6.0.1-foobar
+
+   Now try the following command, which on some distributions will delete all
+   other kernel files installed while also removing the kernel's entry from the
+   bootloader configuration::
+
+     command -v kernel-install && sudo kernel-install -v remove 6.0.1-foobar
+
+   If that command does not output anything or fails, see the reference section;
+   do the same if any files named '*6.0.1-foobar*' remain in /boot/.
+
+   [:ref:`details<uninstall>`]
+
+.. _submit_improvements_qbtl:
+
+Did you run into trouble following the step-by-step guide not cleared up by the
+reference section below? Did you spot errors? Or do you have ideas on how to
+improve the guide?
+
+If any of that applies, please let the developers know by sending a short note
+or a patch to Thorsten Leemhuis <linux@leemhuis.info> while ideally CCing the
+public Linux docs mailing list <linux-doc@vger.kernel.org>. Such feedback is
+vital to improve this text further, which is in everybody's interest, as it will
+enable more people to master the task described here.
+
+Reference section for the step-by-step guide
+============================================
+
+This section holds additional information for each of the steps in the above
+guide.
+
+.. _backup:
+
+Prepare for emergencies
+-----------------------
+
+   *Create a fresh backup and put system repair and restore tools at hand*
+   [:ref:`... <backup_sbs>`]
+
+Remember, you are dealing with computers, which sometimes do unexpected things
+-- especially if you fiddle with crucial parts like the kernel of an operating
+system. That's what you are about to do in this process. Hence, better prepare
+for something going sideways, even if that should not happen.
+
+[:ref:`back to step-by-step guide <backup_sbs>`]
+
+.. _secureboot:
+
+Dealing with techniques like Secure Boot
+----------------------------------------
+
+   *On platforms with 'Secure Boot' or similar techniques, prepare everything to
+   ensure the system will permit your self-compiled kernel to boot later.*
+   [:ref:`... <secureboot_sbs>`]
+
+Many modern systems allow only certain operating systems to start; they thus by
+default will reject booting self-compiled kernels.
+
+You ideally deal with this by making your platform trust your self-built kernels
+with the help of a certificate and signing. How to do that is not described
+here, as it requires various steps that would take the text too far away from
+its purpose; 'Documentation/admin-guide/module-signing.rst' and various web
+sides already explain this in more detail.
+
+Temporarily disabling solutions like Secure Boot is another way to make your own
+Linux boot. On commodity x86 systems it is possible to do this in the BIOS Setup
+utility; the steps to do so are not described here, as they greatly vary between
+machines.
+
+On mainstream x86 Linux distributions there is a third and universal option:
+disable all Secure Boot restrictions for your Linux environment. You can
+initiate this process by running ``mokutil --disable-validation``; this will
+tell you to create a one-time password, which is safe to write down. Now
+restart; right after your BIOS performed all self-tests the bootloader Shim will
+show a blue box with a message 'Press any key to perform MOK management'. Hit
+some key before the countdown exposes. This will open a menu and choose 'Change
+Secure Boot state' there. Shim's 'MokManager' will now ask you to enter three
+randomly chosen characters from the one-time password specified earlier. Once
+you provided them, confirm that you really want to disable the validation.
+Afterwards, permit MokManager to reboot the machine.
+
+[:ref:`back to step-by-step guide <secureboot_sbs>`]
+
+.. _buildrequires:
+
+Install build requirements
+--------------------------
+
+   *Install all software required to build a Linux kernel.*
+   [:ref:`...<buildrequires_sbs>`]
+
+The kernel is pretty stand-alone, but besides tools like the compiler you will
+sometimes need a few libraries to build one. How to install everything needed
+depends on your Linux distribution and the configuration of the kernel you are
+about to build.
+
+Here are a few examples what you typically need on some mainstream
+distributions:
+
+ * Debian, Ubuntu, and derivatives::
+
+     sudo apt install bc binutils bison dwarves flex gcc git make openssl \
+       pahole perl-base libssl-dev libelf-dev
+
+ * Fedora and derivatives::
+
+     sudo dnf install binutils /usr/include/{libelf.h,openssl/pkcs7.h} \
+       /usr/bin/{bc,bison,flex,gcc,git,openssl,make,perl,pahole}
+
+ * openSUSE and derivatives::
+
+     sudo zypper install bc binutils bison dwarves flex gcc git make perl-base \
+       openssl openssl-devel libelf-dev
+
+In case you wonder why these lists include openssl and its development headers:
+they are needed for the Secure Boot support, which many distributions enable in
+their kernel configuration for x86 machines.
+
+Sometimes you will need tools for compression formats like bzip2, gzip, lz4,
+lzma, lzo, xz, or zstd as well.
+
+You might need additional libraries and their development headers in case you
+perform tasks not covered in this guide. For example, zlib will be needed when
+building kernel tools from the tools/ directory; adjusting the build
+configuration with make targets like 'menuconfig' or 'xconfig' will require
+development headers for ncurses or Qt5.
+
+[:ref:`back to step-by-step guide <buildrequires_sbs>`]
+
+.. _diskspace:
+
+Space requirements
+------------------
+
+   *Ensure to have enough free space for building and installing Linux.*
+   [:ref:`... <diskspace_sbs>`]
+
+The numbers mentioned are rough estimates with a big extra charge to be on the
+safe side, so often you will need less.
+
+If you have space constraints, remember to read the reference section when you
+reach the :ref:`section about configuration adjustments' <configmods>`, as
+ensuring debug symbols are disabled will reduce the consumed disk space by quite
+a few gigabytes.
+
+[:ref:`back to step-by-step guide <diskspace_sbs>`]
+
+
+.. _sources:
+
+Download the sources
+--------------------
+
+  *Retrieve the sources of the Linux version you intend to build.*
+  [:ref:`...<sources_sbs>`]
+
+The step-by-step guide outlines how to retrieve Linux' sources using a shallow
+git clone. There is :ref:`more to tell about this method<sources_shallow>` and
+two alternate ways worth describing: :ref:`packaged archives<sources_archive>`
+and :ref:`a full git clone<sources_full>`. And the aspects ':ref:`wouldn't it
+be wiser to use a proper pre-release than the latest mainline code
+<sources_snapshot>`' and ':ref:`how to get an even fresher mainline codebase
+<sources_fresher>`' need elaboration, too.
+
+Note, to keep things simple the commands used in this guide store the build
+artifacts in the source tree. If you prefer to separate them, simply add
+something like ``O=~/linux-builddir/`` to all make calls; also adjust the path
+in all commands that add files or modify any generated (like your '.config').
+
+[:ref:`back to step-by-step guide <sources_sbs>`]
+
+.. _sources_shallow:
+
+Noteworthy characteristics of shallow clones
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The step-by-step guide uses a shallow clone, as it is the best solution for most
+of this document's target audience. There are a few aspects of this approach
+worth mentioning:
+
+ * This document in most places uses ``git fetch`` with ``--shallow-exclude=``
+   to specify the earliest version you care about (or to be precise: its git
+   tag). You alternatively can use the parameter ``--shallow-since=`` to specify
+   an absolute (say ``'2023-07-15'``) or relative (``'12 months'``) date to
+   define the depth of the history you want to download. As a second
+   alternative, you can also specify a certain depth explicitly with a parameter
+   like ``--depth=1``, unless you add branches for stable/longterm kernels.
+
+ * When running ``git fetch``, remember to always specify the oldest version,
+   the time you care about, or an explicit depth as shown in the step-by-step
+   guide. Otherwise you will risk downloading nearly the entire git history,
+   which will consume quite a bit of time and bandwidth while also stressing the
+   servers.
+
+   Note, you do not have to use the same version or date all the time. But when
+   you change it over time, git will deepen or flatten the history to the
+   specified point. That allows you to retrieve versions you initially thought
+   you did not need -- or it will discard the sources of older versions, for
+   example in case you want to free up some disk space. The latter will happen
+   automatically when using ``--shallow-since=`` or
+   ``--depth=``.
+
+ * Be warned, when deepening your clone you might encounter an error like
+   'fatal: error in object: unshallow cafecaca0c0dacafecaca0c0dacafecaca0c0da'.
+   In that case run ``git repack -d`` and try again``
+
+ * In case you want to revert changes from a certain version (say Linux 6.3) or
+   perform a bisection (v6.2..v6.3), better tell ``git fetch`` to retrieve
+   objects up to three versions earlier (e.g. 6.0): ``git describe`` will then
+   be able to describe most commits just like it would in a full git clone.
+
+[:ref:`back to step-by-step guide <sources_sbs>`] [:ref:`back to section intro <sources>`]
+
+.. _sources_archive:
+
+Downloading the sources using a packages archive
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+People new to compiling Linux often assume downloading an archive via the
+front-page of https://kernel.org is the best approach to retrieve Linux'
+sources. It actually can be, if you are certain to build just one particular
+kernel version without changing any code. Thing is: you might be sure this will
+be the case, but in practice it often will turn out to be a wrong assumption.
+
+That's because when reporting or debugging an issue developers will often ask to
+give another version a try. They also might suggest temporarily undoing a commit
+with ``git revert`` or might provide various patches to try. Sometimes reporters
+will also be asked to use ``git bisect`` to find the change causing a problem.
+These things rely on git or are a lot easier and quicker to handle with it.
+
+A shallow clone also does not add any significant overhead. For example, when
+you use ``git clone --depth=1`` to create a shallow clone of the latest mainline
+codebase git will only retrieve a little more data than downloading the latest
+mainline pre-release (aka 'rc') via the front-page of kernel.org would.
+
+A shallow clone therefore is often the better choice. If you nevertheless want
+to use a packaged source archive, download one via kernel.org; afterwards
+extract its content to some directory and change to the subdirectory created
+during extraction. The rest of the step-by-step guide will work just fine, apart
+from things that rely on git -- but this mainly concerns the section on
+successive builds of other versions.
+
+[:ref:`back to step-by-step guide <sources_sbs>`] [:ref:`back to section intro <sources>`]
+
+.. _sources_full:
+
+Downloading the sources using a full git clone
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If downloading and storing a lot of data (~4,4 Gigabyte as of early 2023) is
+nothing that bothers you, instead of a shallow clone perform a full git clone
+instead. You then will avoid the specialties mentioned above and will have all
+versions and individual commits at hand at any time::
+
+    curl -L \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/clone.bundle \
+      -o linux-stable.git.bundle
+    git clone linux-stable.git.bundle ~/linux/
+    rm linux-stable.git.bundle
+    cd ~/linux/
+    git remote set-url origin \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
+    git fetch origin
+    git checkout --detach origin/master
+
+[:ref:`back to step-by-step guide <sources_sbs>`] [:ref:`back to section intro <sources>`]
+
+.. _sources_snapshot:
+
+Proper pre-releases (RCs) vs. latest mainline
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When cloning the sources using git and checking out origin/master, you often
+will retrieve a codebase that is somewhere between the latest and the next
+release or pre-release. This almost always is the code you want when giving
+mainline a shot: pre-releases like v6.1-rc5 are in no way special, as they do
+not get any significant extra testing before being published.
+
+There is one exception: you might want to stick to the latest mainline release
+(say v6.1) before its successor's first pre-release (v6.2-rc1) is out. That is
+because compiler errors and other problems are more likely to occur during this
+time, as mainline then is in its 'merge window': a usually two week long phase,
+in which the bulk of the changes for the next release is merged.
+
+[:ref:`back to step-by-step guide <sources_sbs>`] [:ref:`back to section intro <sources>`]
+
+.. _sources_fresher:
+
+Avoiding the mainline lag
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The explanations for both the shallow clone and the full clone both retrieve the
+code from the Linux stable git repository. That makes things simpler for this
+document's audience, as it allows easy access to both mainline and
+stable/longterm releases. This approach has just one downside:
+
+Changes merged into the mainline repository are only synced to the master branch
+of the Linux stable repository  every few hours. This lag most of the time is
+not something to worry about; but in case you really need the latest code, just
+add the mainline repo as additional remote and checkout the code from there::
+
+    git remote add mainline \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+    git fetch mainline
+    git checkout --detach mainline/master
+
+When doing this with a shallow clone, remember to call ``git fetch`` with one
+of the parameters described earlier to limit the depth.
+
+[:ref:`back to step-by-step guide <sources_sbs>`] [:ref:`back to section intro <sources>`]
+
+.. _patching:
+
+Patch the sources (optional)
+----------------------------
+
+  *In case you want to apply a kernel patch, do so now.*
+  [:ref:`...<patching_sbs>`]
+
+This is the point where you might want to patch your kernel -- for example when
+a developer proposed a fix and asked you to check if it helps. The step-by-step
+guide already explains everything crucial here.
+
+[:ref:`back to step-by-step guide <patching_sbs>`]
+
+.. _tagging:
+
+Tagging this kernel build (optional, often wise)
+------------------------------------------------
+
+  *If you patched your kernel or already have that kernel version installed,
+  better tag your kernel by extending its release name:*
+  [:ref:`...<tagging_sbs>`]
+
+Tagging your kernel will help avoid confusion later, especially when you patched
+your kernel. Adding an individual tag will also ensure the kernel's image and
+its modules are installed in parallel to any existing kernels.
+
+There are various ways to add such a tag. The step-by-step guide realizes one by
+creating a 'localversion' file in your build directory from which the kernel
+build scripts will automatically pick up the tag. You can later change that file
+to use a different tag in subsequent builds or simply remove that file to dump
+the tag.
+
+[:ref:`back to step-by-step guide <tagging_sbs>`]
+
+.. _configuration:
+
+Define the build configuration for your kernel
+----------------------------------------------
+
+  *Create the build configuration for your kernel based on an existing
+  configuration.* [:ref:`... <configuration_sbs>`]
+
+There are various aspects for this steps that require a more careful
+explanation:
+
+Pitfalls when using another configuration file as base
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Make targets like localmodconfig and olddefconfig share a few common snares you
+want to be aware of:
+
+ * These targets will reuse a kernel build configuration in your build directory
+   (e.g. '~/linux/.config'), if one exists. In case you want to start from
+   scratch you thus need to delete it.
+
+ * The make targets try to find the configuration for your running kernel
+   automatically, but might choose poorly. A line like '# using defaults found
+   in /boot/config-6.0.7-250.fc36.x86_64' or 'using config:
+   '/boot/config-6.0.7-250.fc36.x86_64' tells you which file they picked. If
+   that is not the intended one, simply store it as '~/linux/.config'
+   before using these make targets.
+
+ * Unexpected things might happen if you try to use a config file prepared for
+   one kernel (say v6.0) on an older generation (say v5.15). In that case you
+   might want to use a configuration as base which your distribution utilized
+   when they used that or an slightly older kernel version.
+
+Influencing the configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The make target olddefconfig and the ``yes "" |`` used when utilizing
+localmodconfig will set any undefined build options to their default value. This
+among others will disable many kernel features that were introduced after your
+base kernel was released.
+
+If you want to set these configurations options manually, use ``oldconfig``
+instead of ``olddefconfig`` or omit the ``yes "" |`` when utilizing
+localmodconfig. Then for each undefined configuration option you will be asked
+how to proceed. In case you are unsure what to answer, simply hit 'enter' to
+apply the default value.
+
+Big pitfall when using localmodconfig
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As explained briefly in the step-by-step guide already: with localmodconfig it
+can easily happen that your self-built kernel will lack modules for tasks you
+did not perform before utilizing this make target. That's because those tasks
+require kernel modules that are normally autoloaded when you perform that task
+for the first time; if you didn't perform that task at least once before using
+localmodconfig, the latter will thus assume these modules are superfluous and
+disable them.
+
+You can try to avoid this by performing typical tasks that often will autoload
+additional kernel modules: start a VM, establish VPN connections, loop-mount a
+CD/DVD ISO, mount network shares (CIFS, NFS, ...), and connect all external
+devices (2FA keys, headsets, webcams, ...) as well as storage devices with file
+systems you otherwise do not utilize (btrfs, ext4, FAT, NTFS, XFS, ...). But it
+is hard to think of everything that might be needed -- even kernel developers
+often forget one thing or another at this point.
+
+Do not let that risk bother you, especially when compiling a kernel only for
+testing purposes: everything typically crucial will be there. And if you forget
+something important you can turn on a missing feature later and quickly run the
+commands to compile and install a better kernel.
+
+But if you plan to build and use self-built kernels regularly, you might want to
+reduce the risk by recording which modules your system loads over the course of
+a few weeks. You can automate this with `modprobed-db
+<https://github.com/graysky2/modprobed-db>`_. Afterwards use ``LSMOD=<path>`` to
+point localmodconfig to the list of modules modprobed-db noticed being used::
+
+    yes "" | make LSMOD="${HOME}"/.config/modprobed.db localmodconfig
+
+Remote building with localmodconfig
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If you want to use localmodconfig to build a kernel for another machine, run
+``lsmod > lsmod_foo-machine`` on it and transfer that file to your build host.
+Now point the build scripts to the file like this: ``yes "" | make
+LSMOD=~/lsmod_foo-machine localmodconfig``. Note, in this case
+you likely want to copy a base kernel configuration from the other machine over
+as well and place it as .config in your build directory.
+
+[:ref:`back to step-by-step guide <configuration_sbs>`]
+
+.. _configmods:
+
+Adjust build configuration
+--------------------------
+
+   *Check if you might want to or have to adjust some kernel configuration
+   options:*
+
+Depending on your needs you at this point might want or have to adjust some
+kernel configuration options.
+
+.. _configmods_debugsymbols:
+
+Debug symbols
+~~~~~~~~~~~~~
+
+   *Evaluate how you want to handle debug symbols.*
+   [:ref:`...<configmods_sbs>`]
+
+Most users do not need to care about this, it's often fine to leave everything
+as it is; but you should take a closer look at this, if you might need to decode
+a stack trace or want to reduce space consumption.
+
+Having debug symbols available can be important when your kernel throws a
+'panic', 'Oops', 'warning', or 'BUG' later when running, as then you will be
+able to find the exact place where the problem occurred in the code. But
+collecting and embedding the needed debug information takes time and consumes
+quite a bit of space: in late 2022 the build artifacts for a typical x86 kernel
+configured with localmodconfig consumed around 5 Gigabyte of space with debug
+symbols, but less than 1 when they were disabled. The resulting kernel image and
+the modules are bigger as well, which increases load times.
+
+Hence, if you want a small kernel and are unlikely to decode a stack trace
+later, you might want to disable debug symbols to avoid above downsides::
+
+    ./scripts/config --file .config -d DEBUG_INFO \
+      -d DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT -d DEBUG_INFO_DWARF4 \
+      -d DEBUG_INFO_DWARF5 -e CONFIG_DEBUG_INFO_NONE
+    make olddefconfig
+
+You on the other hand definitely want to enable them, if there is a decent
+chance that you need to decode a stack trace later (as explained by 'Decode
+failure messages' in Documentation/admin-guide/tainted-kernels.rst in more
+detail)::
+
+    ./scripts/config --file .config -d DEBUG_INFO_NONE -e DEBUG_KERNEL
+      -e DEBUG_INFO -e DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT -e KALLSYMS -e KALLSYMS_ALL
+    make olddefconfig
+
+Note, many mainstream distributions enable debug symbols in their kernel
+configurations -- make targets like localmodconfig and olddefconfig thus will
+often pick that setting up.
+
+[:ref:`back to step-by-step guide <configmods_sbs>`]
+
+.. _configmods_distros:
+
+Distro specific adjustments
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+   *Are you running* [:ref:`... <configmods_sbs>`]
+
+The following sections help you to avoid build problems that are known to occur
+when following this guide on a few commodity distributions.
+
+**Debian:**
+
+ * Remove a stale reference to a certificate file that would cause your build to
+   fail::
+
+    ./scripts/config --file .config --set-str SYSTEM_TRUSTED_KEYS ''
+
+   Alternatively, download the needed certificate and make that configuration
+   option point to it, as `the Debian handbook explains in more detail
+   <https://debian-handbook.info/browse/stable/sect.kernel-compilation.html>`_
+   -- or generate your own, as explained in
+   Documentation/admin-guide/module-signing.rst.
+
+[:ref:`back to step-by-step guide <configmods_sbs>`]
+
+.. _configmods_individual:
+
+Individual adjustments
+~~~~~~~~~~~~~~~~~~~~~~
+
+   *If you want to influence the other aspects of the configuration, do so
+   now* [:ref:`... <configmods_sbs>`]
+
+You at this point can use a command like ``make menuconfig`` to enable or
+disable certain features using a text-based user interface; to use a graphical
+configuration utilize, use the make target ``xconfig`` or ``gconfig`` instead.
+All of them require development libraries from toolkits they are based on
+(ncurses, Qt5, Gtk2); an error message will tell you if something required is
+missing.
+
+[:ref:`back to step-by-step guide <configmods_sbs>`]
+
+.. _build:
+
+Build your kernel
+-----------------
+
+  *Build the image and the modules of your kernel* [:ref:`... <build_sbs>`]
+
+A lot can go wrong at this stage, but the instructions below will help you help
+yourself. Another subsection explains how to directly package your kernel up as
+deb, rpm or tar file.
+
+Dealing with build errors
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When a build error occurs, it might be caused by some aspect of your machine's
+setup that often can be fixed quickly; other times though the problem lies in
+the code and can only be fixed by a developer. A close examination of the
+failure messages coupled with some research on the internet will often tell you
+which of the two it is. To perform such an investigation, restart the build
+process like this::
+
+    make V=1
+
+The ``V=1`` activates verbose output, which might be needed to see the actual
+error. To make it easier to spot, this command also omits the ``-j $(nproc
+--all)`` used earlier to utilize every CPU core in the system for the job -- but
+this parallelism also results in some clutter when failures occur.
+
+After a few seconds the build process should run into the error again. Now try
+to find the most crucial line describing the problem. Then search the internet
+for the most important and non-generic section of that line (say 4 to 8 words);
+avoid or remove anything that looks remotely system-specific, like your username
+or local path names like ``/home/username/linux/``. First try your regular
+internet search engine with that string, afterwards search Linux kernel mailing
+lists via `lore.kernel.org/all/ <https://lore.kernel.org/all/>`_.
+
+This most of the time will find something that will explain what is wrong; quite
+often one of the hits will provide a solution for your problem, too. If you
+do not find anything that matches your problem, try again from a different angle
+by modifying your search terms or using another line from the error messages.
+
+In the end, most trouble you are to run into has likely been encountered and
+reported by others already. That includes issues where the cause is not your
+system, but lies the code. If you run into one of those, you might thus find a
+solution (e.g. a patch) or workaround for your problem, too.
+
+Package your kernel up
+~~~~~~~~~~~~~~~~~~~~~~
+
+The step-by-step guide uses the default make targets (e.g. 'bzImage' and
+'modules' on x86) to build the image and the modules of your kernel, which later
+steps of the guide then install. You instead can also directly build everything
+and directly package it up by using one of the following targets:
+
+ * ``make -j $(nproc --all) bindeb-pkg`` to generate a deb package
+
+ * ``make -j $(nproc --all) binrpm-pkg`` to generate a rpm package
+
+ * ``make -j $(nproc --all) tarbz2-pkg`` to generate a bz2 compressed tarball
+
+This is just a selection of available make targets for this purpose, see
+``make help`` for others. You can also use these targets after running
+``make -j $(nproc --all)``, as they will pick up everything already built.
+
+If you employ the targets to generate deb or rpm packages, ignore the
+step-by-step guide's instructions on installing and removing your kernel;
+instead install and remove the packages using the package utility for the format
+(e.g. dpkg and rpm) or a package management utility build on top of them (apt,
+aptitude, dnf/yum, zypper, ...). Be aware that the packages generated using
+these two make targets are designed to work on various distributions utilizing
+those formats, they thus will sometimes behave differently than your
+distribution's kernel packages.
+
+[:ref:`back to step-by-step guide <build_sbs>`]
+
+.. _install:
+
+Install your kernel
+-------------------
+
+  *Now install your kernel* [:ref:`... <install_sbs>`]
+
+What you need to do after executing the command in the step-by-step guide
+depends on the existence and the implementation of an ``installkernel``
+executable. Many commodity Linux distributions ship such a kernel installer in
+``/sbin/`` that does everything needed, hence there is nothing left for you
+except rebooting. But some distributions contain an installkernel that does
+only part of the job -- and a few lack it completely and leave all the work to
+you.
+
+If ``installkernel`` is found, the kernel's build system will delegate the
+actual installation of your kernel's image and related files to this executable.
+On almost all Linux distributions it will store the image as '/boot/vmlinuz-
+<your kernel's release name>' and put a 'System.map-<your kernel's release
+name>' alongside it. Your kernel will thus be installed in parallel to any
+existing ones, unless you already have one with exactly the same release name.
+
+Installkernel on many distributions will afterwards generate an 'initramfs'
+(often also called 'initrd'), which commodity distributions rely on for booting;
+hence be sure to keep the order of the two make targets used in the step-by-step
+guide, as things will go sideways if you install your kernel's image before its
+modules. Often installkernel will then add your kernel to the bootloader
+configuration, too. You have to take care of one or both of these tasks
+yourself, if your distributions installkernel doesn't handle them.
+
+A few distributions like Arch Linux and its derivatives totally lack an
+installkernel executable. On those just install the modules using the kernel's
+build system and then install the image and the System.map file manually::
+
+     sudo make modules_install
+     sudo install -m 0600 $(make -s image_name) /boot/vmlinuz-$(make -s kernelrelease)
+     sudo install -m 0600 System.map /boot/System.map-$(make -s kernelrelease)
+
+If your distribution boots with the help of an initramfs, now generate one for
+your kernel using the tools your distribution provides for this process.
+Afterwards add your kernel to your bootloader configuration and reboot.
+
+[:ref:`back to step-by-step guide <install_sbs>`]
+
+.. _another:
+
+Another round later
+-------------------
+
+  *To later build another kernel you need similar, but sometimes slightly
+  different commands* [:ref:`... <another_sbs>`]
+
+The process to build later kernels is similar, but at some points slightly
+different. You for example do not want to use 'localmodconfig' for succeeding
+kernel builds, as you already created a trimmed down configuration you want to
+use from now on. Hence instead just use ``oldconfig`` or ``olddefconfig`` to
+adjust your build configurations to the needs of the kernel version you are
+about to build.
+
+If you created a shallow-clone with git, remember what the :ref:`section that
+explained the setup described in more detail <sources>`: you need to use a
+slightly different ``git fetch`` command and when switching to another series
+need to add an additional remote branch.
+
+[:ref:`back to step-by-step guide <another_sbs>`]
+
+.. _uninstall:
+
+Uninstall the kernel later
+--------------------------
+
+  *All parts of your installed kernel are identifiable by its release name and
+  thus easy to remove later.* [:ref:`... <uninstall_sbs>`]
+
+Do not worry installing your kernel manually and thus bypassing your
+distribution's packaging system will totally mess up your machine: all parts of
+your kernel are easy to remove later, as files are stored in two places only and
+normally identifiable by the kernel's release name.
+
+One of the two places is a directory in /lib/modules/, which holds the modules
+for each installed kernel. This directory is named after the kernel's release
+name; hence, to remove all modules for one of your kernels, simply remove its
+modules directory in /lib/modules/.
+
+The other place is /boot/, where typically one to five files will be placed
+during installation of a kernel. All of them usually contain the release name in
+their file name, but how many files and their name depends somewhat on your
+distribution's installkernel executable (:ref:`see above <install>`) and its
+initramfs generator. On some distributions the ``kernel-install`` command
+mentioned in the step-by-step guide will remove all of these files for you --
+and the entry for your kernel in the bootloader configuration at the same time,
+too. On others you have to take care of these steps yourself. The following
+command should interactively remove the two main files of a kernel with the
+release name '6.0.1-foobar'::
+
+    rm -i /boot/{System.map,vmlinuz}-6.0.1-foobar
+
+Now remove the belonging initramfs, which often will be called something like
+``/boot/initramfs-6.0.1-foobar.img`` or ``/boot/initrd.img-6.0.1-foobar``.
+Afterwards check for other files in /boot/ that have '6.0.1-foobar' in their
+name and delete them as well. Now remove the kernel from your bootloader's
+configuration.
+
+Note, be very careful with wildcards like '*' when deleting files or directories
+for kernels manually: you might accidentally remove files of a 6.0.11 kernel
+when all you want is to remove 6.0 or 6.0.1.
+
+[:ref:`back to step-by-step guide <uninstall_sbs>`]
+
+.. _faq:
+
+FAQ
+===
+
+Why does this 'how-to' not work on my system?
+---------------------------------------------
+
+As initially stated, this guide is 'designed to cover everything typically
+needed [to build a kernel] on mainstream Linux distributions running on
+commodity PC or server hardware'. The outlined approach despite this should work
+on many other setups as well. But trying to cover every possible use-case in one
+guide would defeat its purpose, as without such a focus you would need dozens or
+hundreds of constructs along the lines of 'in case you are having <insert
+machine or distro>, you at this point have to do <this and that>
+<instead|additionally>'. Each of which would make the text longer, more
+complicated, and harder to follow.
+
+That being said: this of course is a balancing act. Hence, if you think an
+additional use-case is worth describing, suggest it to the maintainers of this
+document, as :ref:`described above <submit_improvements_qbtl>`.
+
+
+..
+   end-of-content
+..
+   This document is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If
+   you spot a typo or small mistake, feel free to let him know directly and
+   he'll fix it. You are free to do the same in a mostly informal way if you
+   want to contribute changes to the text -- but for copyright reasons please CC
+   linux-doc@vger.kernel.org and 'sign-off' your contribution as
+   Documentation/process/submitting-patches.rst explains in the section 'Sign
+   your work - the Developer's Certificate of Origin'.
+..
+   This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top
+   of the file. If you want to distribute this text under CC-BY-4.0 only,
+   please use 'The Linux kernel development community' for author attribution
+   and link this as source:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/quickly-build-trimmed-linux.rst
+..
+   Note: Only the content of this RST file as found in the Linux kernel sources
+   is available under CC-BY-4.0, as versions of this text that were processed
+   (for example by the kernel's build system) might contain content taken from
+   files which use a more restrictive license.
+
diff --git a/Documentation/admin-guide/ramoops.rst b/Documentation/admin-guide/ramoops.rst
new file mode 100644
index 000000000..2eabef312
--- /dev/null
+++ b/Documentation/admin-guide/ramoops.rst
@@ -0,0 +1,177 @@
+Ramoops oops/panic logger
+=========================
+
+Sergiu Iordache <sergiu@chromium.org>
+
+Updated: 10 Feb 2021
+
+Introduction
+------------
+
+Ramoops is an oops/panic logger that writes its logs to RAM before the system
+crashes. It works by logging oopses and panics in a circular buffer. Ramoops
+needs a system with persistent RAM so that the content of that area can
+survive after a restart.
+
+Ramoops concepts
+----------------
+
+Ramoops uses a predefined memory area to store the dump. The start and size
+and type of the memory area are set using three variables:
+
+  * ``mem_address`` for the start
+  * ``mem_size`` for the size. The memory size will be rounded down to a
+    power of two.
+  * ``mem_type`` to specify if the memory type (default is pgprot_writecombine).
+  * ``mem_name`` to specify a memory region defined by ``reserve_mem`` command
+    line parameter.
+
+Typically the default value of ``mem_type=0`` should be used as that sets the pstore
+mapping to pgprot_writecombine. Setting ``mem_type=1`` attempts to use
+``pgprot_noncached``, which only works on some platforms. This is because pstore
+depends on atomic operations. At least on ARM, pgprot_noncached causes the
+memory to be mapped strongly ordered, and atomic operations on strongly ordered
+memory are implementation defined, and won't work on many ARMs such as omaps.
+Setting ``mem_type=2`` attempts to treat the memory region as normal memory,
+which enables full cache on it. This can improve the performance.
+
+The memory area is divided into ``record_size`` chunks (also rounded down to
+power of two) and each kmesg dump writes a ``record_size`` chunk of
+information.
+
+Limiting which kinds of kmsg dumps are stored can be controlled via
+the ``max_reason`` value, as defined in include/linux/kmsg_dump.h's
+``enum kmsg_dump_reason``. For example, to store both Oopses and Panics,
+``max_reason`` should be set to 2 (KMSG_DUMP_OOPS), to store only Panics
+``max_reason`` should be set to 1 (KMSG_DUMP_PANIC). Setting this to 0
+(KMSG_DUMP_UNDEF), means the reason filtering will be controlled by the
+``printk.always_kmsg_dump`` boot param: if unset, it'll be KMSG_DUMP_OOPS,
+otherwise KMSG_DUMP_MAX.
+
+The module uses a counter to record multiple dumps but the counter gets reset
+on restart (i.e. new dumps after the restart will overwrite old ones).
+
+Ramoops also supports software ECC protection of persistent memory regions.
+This might be useful when a hardware reset was used to bring the machine back
+to life (i.e. a watchdog triggered). In such cases, RAM may be somewhat
+corrupt, but usually it is restorable.
+
+Setting the parameters
+----------------------
+
+Setting the ramoops parameters can be done in several different manners:
+
+ A. Use the module parameters (which have the names of the variables described
+ as before). For quick debugging, you can also reserve parts of memory during
+ boot and then use the reserved memory for ramoops. For example, assuming a
+ machine with > 128 MB of memory, the following kernel command line will tell
+ the kernel to use only the first 128 MB of memory, and place ECC-protected
+ ramoops region at 128 MB boundary::
+
+	mem=128M ramoops.mem_address=0x8000000 ramoops.ecc=1
+
+ B. Use Device Tree bindings, as described in
+ ``Documentation/devicetree/bindings/reserved-memory/ramoops.yaml``.
+ For example::
+
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		ramoops@8f000000 {
+			compatible = "ramoops";
+			reg = <0 0x8f000000 0 0x100000>;
+			record-size = <0x4000>;
+			console-size = <0x4000>;
+		};
+	};
+
+ C. Use a platform device and set the platform data. The parameters can then
+ be set through that platform data. An example of doing that is:
+
+ .. code-block:: c
+
+  #include <linux/pstore_ram.h>
+  [...]
+
+  static struct ramoops_platform_data ramoops_data = {
+        .mem_size               = <...>,
+        .mem_address            = <...>,
+        .mem_type               = <...>,
+        .record_size            = <...>,
+        .max_reason             = <...>,
+        .ecc                    = <...>,
+  };
+
+  static struct platform_device ramoops_dev = {
+        .name = "ramoops",
+        .dev = {
+                .platform_data = &ramoops_data,
+        },
+  };
+
+  [... inside a function ...]
+  int ret;
+
+  ret = platform_device_register(&ramoops_dev);
+  if (ret) {
+	printk(KERN_ERR "unable to register platform device\n");
+	return ret;
+  }
+
+ D. Using a region of memory reserved via ``reserve_mem`` command line
+    parameter. The address and size will be defined by the ``reserve_mem``
+    parameter. Note, that ``reserve_mem`` may not always allocate memory
+    in the same location, and cannot be relied upon. Testing will need
+    to be done, and it may not work on every machine, nor every kernel.
+    Consider this a "best effort" approach. The ``reserve_mem`` option
+    takes a size, alignment and name as arguments. The name is used
+    to map the memory to a label that can be retrieved by ramoops.
+
+	reserve_mem=2M:4096:oops  ramoops.mem_name=oops
+
+You can specify either RAM memory or peripheral devices' memory. However, when
+specifying RAM, be sure to reserve the memory by issuing memblock_reserve()
+very early in the architecture code, e.g.::
+
+	#include <linux/memblock.h>
+
+	memblock_reserve(ramoops_data.mem_address, ramoops_data.mem_size);
+
+Dump format
+-----------
+
+The data dump begins with a header, currently defined as ``====`` followed by a
+timestamp and a new line. The dump then continues with the actual data.
+
+Reading the data
+----------------
+
+The dump data can be read from the pstore filesystem. The format for these
+files is ``dmesg-ramoops-N``, where N is the record number in memory. To delete
+a stored record from RAM, simply unlink the respective pstore file.
+
+Persistent function tracing
+---------------------------
+
+Persistent function tracing might be useful for debugging software or hardware
+related hangs. The functions call chain log is stored in a ``ftrace-ramoops``
+file. Here is an example of usage::
+
+ # mount -t debugfs debugfs /sys/kernel/debug/
+ # echo 1 > /sys/kernel/debug/pstore/record_ftrace
+ # reboot -f
+ [...]
+ # mount -t pstore pstore /mnt/
+ # tail /mnt/ftrace-ramoops
+ 0 ffffffff8101ea64  ffffffff8101bcda  native_apic_mem_read <- disconnect_bsp_APIC+0x6a/0xc0
+ 0 ffffffff8101ea44  ffffffff8101bcf6  native_apic_mem_write <- disconnect_bsp_APIC+0x86/0xc0
+ 0 ffffffff81020084  ffffffff8101a4b5  hpet_disable <- native_machine_shutdown+0x75/0x90
+ 0 ffffffff81005f94  ffffffff8101a4bb  iommu_shutdown_noop <- native_machine_shutdown+0x7b/0x90
+ 0 ffffffff8101a6a1  ffffffff8101a437  native_machine_emergency_restart <- native_machine_restart+0x37/0x40
+ 0 ffffffff811f9876  ffffffff8101a73a  acpi_reboot <- native_machine_emergency_restart+0xaa/0x1e0
+ 0 ffffffff8101a514  ffffffff8101a772  mach_reboot_fixups <- native_machine_emergency_restart+0xe2/0x1e0
+ 0 ffffffff811d9c54  ffffffff8101a7a0  __const_udelay <- native_machine_emergency_restart+0x110/0x1e0
+ 0 ffffffff811d9c34  ffffffff811d9c80  __delay <- __const_udelay+0x30/0x40
+ 0 ffffffff811d9d14  ffffffff811d9c3f  delay_tsc <- __delay+0xf/0x20
diff --git a/Documentation/admin-guide/rapidio.rst b/Documentation/admin-guide/rapidio.rst
new file mode 100644
index 000000000..71ff658ab
--- /dev/null
+++ b/Documentation/admin-guide/rapidio.rst
@@ -0,0 +1,107 @@
+=======================
+RapidIO Subsystem Guide
+=======================
+
+:Author: Matt Porter
+
+Introduction
+============
+
+RapidIO is a high speed switched fabric interconnect with features aimed
+at the embedded market. RapidIO provides support for memory-mapped I/O
+as well as message-based transactions over the switched fabric network.
+RapidIO has a standardized discovery mechanism not unlike the PCI bus
+standard that allows simple detection of devices in a network.
+
+This documentation is provided for developers intending to support
+RapidIO on new architectures, write new drivers, or to understand the
+subsystem internals.
+
+Known Bugs and Limitations
+==========================
+
+Bugs
+----
+
+None. ;)
+
+Limitations
+-----------
+
+1. Access/management of RapidIO memory regions is not supported
+
+2. Multiple host enumeration is not supported
+
+RapidIO driver interface
+========================
+
+Drivers are provided a set of calls in order to interface with the
+subsystem to gather info on devices, request/map memory region
+resources, and manage mailboxes/doorbells.
+
+Functions
+---------
+
+.. kernel-doc:: include/linux/rio_drv.h
+   :internal:
+
+.. kernel-doc:: drivers/rapidio/rio-driver.c
+   :export:
+
+.. kernel-doc:: drivers/rapidio/rio.c
+   :export:
+
+Internals
+=========
+
+This chapter contains the autogenerated documentation of the RapidIO
+subsystem.
+
+Structures
+----------
+
+.. kernel-doc:: include/linux/rio.h
+   :internal:
+
+Enumeration and Discovery
+-------------------------
+
+.. kernel-doc:: drivers/rapidio/rio-scan.c
+   :internal:
+
+Driver functionality
+--------------------
+
+.. kernel-doc:: drivers/rapidio/rio.c
+   :internal:
+
+.. kernel-doc:: drivers/rapidio/rio-access.c
+   :internal:
+
+Device model support
+--------------------
+
+.. kernel-doc:: drivers/rapidio/rio-driver.c
+   :internal:
+
+PPC32 support
+-------------
+
+.. kernel-doc:: arch/powerpc/sysdev/fsl_rio.c
+   :internal:
+
+Credits
+=======
+
+The following people have contributed to the RapidIO subsystem directly
+or indirectly:
+
+1. Matt Porter\ mporter@kernel.crashing.org
+
+2. Randy Vinson\ rvinson@mvista.com
+
+3. Dan Malek\ dan@embeddedalley.com
+
+The following people have contributed to this document:
+
+1. Matt Porter\ mporter@kernel.crashing.org
diff --git a/Documentation/admin-guide/reporting-issues.rst b/Documentation/admin-guide/reporting-issues.rst
new file mode 100644
index 000000000..87dd874ff
--- /dev/null
+++ b/Documentation/admin-guide/reporting-issues.rst
@@ -0,0 +1,1770 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+.. See the bottom of this file for additional redistribution information.
+
+Reporting issues
+++++++++++++++++
+
+
+The short guide (aka TL;DR)
+===========================
+
+Are you facing a regression with vanilla kernels from the same stable or
+longterm series? One still supported? Then search the `LKML
+<https://lore.kernel.org/lkml/>`_ and the `Linux stable mailing list
+<https://lore.kernel.org/stable/>`_ archives for matching reports to join. If
+you don't find any, install `the latest release from that series
+<https://kernel.org/>`_. If it still shows the issue, report it to the stable
+mailing list (stable@vger.kernel.org) and CC the regressions list
+(regressions@lists.linux.dev); ideally also CC the maintainer and the mailing
+list for the subsystem in question.
+
+In all other cases try your best guess which kernel part might be causing the
+issue. Check the :ref:`MAINTAINERS <maintainers>` file for how its developers
+expect to be told about problems, which most of the time will be by email with a
+mailing list in CC. Check the destination's archives for matching reports;
+search the `LKML <https://lore.kernel.org/lkml/>`_ and the web, too. If you
+don't find any to join, install `the latest mainline kernel
+<https://kernel.org/>`_. If the issue is present there, send a report.
+
+The issue was fixed there, but you would like to see it resolved in a still
+supported stable or longterm series as well? Then install its latest release.
+If it shows the problem, search for the change that fixed it in mainline and
+check if backporting is in the works or was discarded; if it's neither, ask
+those who handled the change for it.
+
+**General remarks**: When installing and testing a kernel as outlined above,
+ensure it's vanilla (IOW: not patched and not using add-on modules). Also make
+sure it's built and running in a healthy environment and not already tainted
+before the issue occurs.
+
+If you are facing multiple issues with the Linux kernel at once, report each
+separately. While writing your report, include all information relevant to the
+issue, like the kernel and the distro used. In case of a regression, CC the
+regressions mailing list (regressions@lists.linux.dev) to your report. Also try
+to pinpoint the culprit with a bisection; if you succeed, include its
+commit-id and CC everyone in the sign-off-by chain.
+
+Once the report is out, answer any questions that come up and help where you
+can. That includes keeping the ball rolling by occasionally retesting with newer
+releases and sending a status update afterwards.
+
+..
+   Note: If you see this note, you are reading the text's source file. You
+   might want to switch to a rendered version: It makes it a lot easier to
+   read and navigate this document -- especially when you want to look something
+   up in the reference section, then jump back to where you left off.
+..
+   Find the latest rendered version of this text here:
+   https://docs.kernel.org/admin-guide/reporting-issues.html
+
+
+Step-by-step guide how to report issues to the kernel maintainers
+=================================================================
+
+The above TL;DR outlines roughly how to report issues to the Linux kernel
+developers. It might be all that's needed for people already familiar with
+reporting issues to Free/Libre & Open Source Software (FLOSS) projects. For
+everyone else there is this section. It is more detailed and uses a
+step-by-step approach. It still tries to be brief for readability and leaves
+out a lot of details; those are described below the step-by-step guide in a
+reference section, which explains each of the steps in more detail.
+
+Note: this section covers a few more aspects than the TL;DR and does things in
+a slightly different order. That's in your interest, to make sure you notice
+early if an issue that looks like a Linux kernel problem is actually caused by
+something else. These steps thus help to ensure the time you invest in this
+process won't feel wasted in the end:
+
+ * Are you facing an issue with a Linux kernel a hardware or software vendor
+   provided? Then in almost all cases you are better off to stop reading this
+   document and reporting the issue to your vendor instead, unless you are
+   willing to install the latest Linux version yourself. Be aware the latter
+   will often be needed anyway to hunt down and fix issues.
+
+ * Perform a rough search for existing reports with your favorite internet
+   search engine; additionally, check the archives of the `Linux Kernel Mailing
+   List (LKML) <https://lore.kernel.org/lkml/>`_. If you find matching reports,
+   join the discussion instead of sending a new one.
+
+ * See if the issue you are dealing with qualifies as regression, security
+   issue, or a really severe problem: those are 'issues of high priority' that
+   need special handling in some steps that are about to follow.
+
+ * Make sure it's not the kernel's surroundings that are causing the issue
+   you face.
+
+ * Create a fresh backup and put system repair and restore tools at hand.
+
+ * Ensure your system does not enhance its kernels by building additional
+   kernel modules on-the-fly, which solutions like DKMS might be doing locally
+   without your knowledge.
+
+ * Check if your kernel was 'tainted' when the issue occurred, as the event
+   that made the kernel set this flag might be causing the issue you face.
+
+ * Write down coarsely how to reproduce the issue. If you deal with multiple
+   issues at once, create separate notes for each of them and make sure they
+   work independently on a freshly booted system. That's needed, as each issue
+   needs to get reported to the kernel developers separately, unless they are
+   strongly entangled.
+
+ * If you are facing a regression within a stable or longterm version line
+   (say something broke when updating from 5.10.4 to 5.10.5), scroll down to
+   'Dealing with regressions within a stable and longterm kernel line'.
+
+ * Locate the driver or kernel subsystem that seems to be causing the issue.
+   Find out how and where its developers expect reports. Note: most of the
+   time this won't be bugzilla.kernel.org, as issues typically need to be sent
+   by mail to a maintainer and a public mailing list.
+
+ * Search the archives of the bug tracker or mailing list in question
+   thoroughly for reports that might match your issue. If you find anything,
+   join the discussion instead of sending a new report.
+
+After these preparations you'll now enter the main part:
+
+ * Unless you are already running the latest 'mainline' Linux kernel, better
+   go and install it for the reporting process. Testing and reporting with
+   the latest 'stable' Linux can be an acceptable alternative in some
+   situations; during the merge window that actually might be even the best
+   approach, but in that development phase it can be an even better idea to
+   suspend your efforts for a few days anyway. Whatever version you choose,
+   ideally use a 'vanilla' build. Ignoring all of this advice will dramatically
+   increase the risk your report will be rejected or ignored.
+
+ * Ensure the kernel you just installed does not 'taint' itself when
+   running.
+
+ * Reproduce the issue with the kernel you just installed. If it doesn't show
+   up there, scroll down to the instructions for issues only happening with
+   stable and longterm kernels.
+
+ * Optimize your notes: try to find and write the most straightforward way to
+   reproduce your issue. Make sure the end result has all the important
+   details, and at the same time is easy to read and understand for others
+   that hear about it for the first time. And if you learned something in this
+   process, consider searching again for existing reports about the issue.
+
+ * If your failure involves a 'panic', 'Oops', 'warning', or 'BUG', consider
+   decoding the kernel log to find the line of code that triggered the error.
+
+ * If your problem is a regression, try to narrow down when the issue was
+   introduced as much as possible.
+
+ * Start to compile the report by writing a detailed description about the
+   issue. Always mention a few things: the latest kernel version you installed
+   for reproducing, the Linux Distribution used, and your notes on how to
+   reproduce the issue. Ideally, make the kernel's build configuration
+   (.config) and the output from ``dmesg`` available somewhere on the net and
+   link to it. Include or upload all other information that might be relevant,
+   like the output/screenshot of an Oops or the output from ``lspci``. Once
+   you wrote this main part, insert a normal length paragraph on top of it
+   outlining the issue and the impact quickly. On top of this add one sentence
+   that briefly describes the problem and gets people to read on. Now give the
+   thing a descriptive title or subject that yet again is shorter. Then you're
+   ready to send or file the report like the MAINTAINERS file told you, unless
+   you are dealing with one of those 'issues of high priority': they need
+   special care which is explained in 'Special handling for high priority
+   issues' below.
+
+ * Wait for reactions and keep the thing rolling until you can accept the
+   outcome in one way or the other. Thus react publicly and in a timely manner
+   to any inquiries. Test proposed fixes. Do proactive testing: retest with at
+   least every first release candidate (RC) of a new mainline version and
+   report your results. Send friendly reminders if things stall. And try to
+   help yourself, if you don't get any help or if it's unsatisfying.
+
+
+Reporting regressions within a stable and longterm kernel line
+--------------------------------------------------------------
+
+This subsection is for you, if you followed above process and got sent here at
+the point about regression within a stable or longterm kernel version line. You
+face one of those if something breaks when updating from 5.10.4 to 5.10.5 (a
+switch from 5.9.15 to 5.10.5 does not qualify). The developers want to fix such
+regressions as quickly as possible, hence there is a streamlined process to
+report them:
+
+ * Check if the kernel developers still maintain the Linux kernel version
+   line you care about: go to the  `front page of kernel.org
+   <https://kernel.org/>`_ and make sure it mentions
+   the latest release of the particular version line without an '[EOL]' tag.
+
+ * Check the archives of the `Linux stable mailing list
+   <https://lore.kernel.org/stable/>`_ for existing reports.
+
+ * Install the latest release from the particular version line as a vanilla
+   kernel. Ensure this kernel is not tainted and still shows the problem, as
+   the issue might have already been fixed there. If you first noticed the
+   problem with a vendor kernel, check a vanilla build of the last version
+   known to work performs fine as well.
+
+ * Send a short problem report to the Linux stable mailing list
+   (stable@vger.kernel.org) and CC the Linux regressions mailing list
+   (regressions@lists.linux.dev); if you suspect the cause in a particular
+   subsystem, CC its maintainer and its mailing list. Roughly describe the
+   issue and ideally explain how to reproduce it. Mention the first version
+   that shows the problem and the last version that's working fine. Then
+   wait for further instructions.
+
+The reference section below explains each of these steps in more detail.
+
+
+Reporting issues only occurring in older kernel version lines
+-------------------------------------------------------------
+
+This subsection is for you, if you tried the latest mainline kernel as outlined
+above, but failed to reproduce your issue there; at the same time you want to
+see the issue fixed in a still supported stable or longterm series or vendor
+kernels regularly rebased on those. If that is the case, follow these steps:
+
+ * Prepare yourself for the possibility that going through the next few steps
+   might not get the issue solved in older releases: the fix might be too big
+   or risky to get backported there.
+
+ * Perform the first three steps in the section "Dealing with regressions
+   within a stable and longterm kernel line" above.
+
+ * Search the Linux kernel version control system for the change that fixed
+   the issue in mainline, as its commit message might tell you if the fix is
+   scheduled for backporting already. If you don't find anything that way,
+   search the appropriate mailing lists for posts that discuss such an issue
+   or peer-review possible fixes; then check the discussions if the fix was
+   deemed unsuitable for backporting. If backporting was not considered at
+   all, join the newest discussion, asking if it's in the cards.
+
+ * One of the former steps should lead to a solution. If that doesn't work
+   out, ask the maintainers for the subsystem that seems to be causing the
+   issue for advice; CC the mailing list for the particular subsystem as well
+   as the stable mailing list.
+
+The reference section below explains each of these steps in more detail.
+
+
+Conclusion of the step-by-step guide
+------------------------------------
+
+Did you run into trouble following the step-by-step guide not cleared up by the
+reference section below? Did you spot errors? Or do you have ideas on how to
+improve the guide?
+
+If any of that applies, please let the developers know by sending a short note
+or a patch to Thorsten Leemhuis <linux@leemhuis.info> while ideally CCing the
+public Linux docs mailing list <linux-doc@vger.kernel.org>. Such feedback is
+vital to improve this text further, which is in everybody's interest, as it will
+enable more people to master the task described here.
+
+
+Reference section: Reporting issues to the kernel maintainers
+=============================================================
+
+The step-by-step guide above outlines all the major steps in brief fashion,
+which usually covers everything required. But even experienced users will
+sometimes wonder how to actually realize some of those steps or why they are
+needed; there are also corner cases the guide ignores for readability. That is
+what the entries in this reference section are for, which provide additional
+information for each of the steps in the guide.
+
+A few words of general advice:
+
+* The Linux developers are well aware that reporting bugs to them is more
+  complicated and demanding than in other FLOSS projects. Some of it is because
+  the kernel is different, among others due to its mail-driven development
+  process and because it consists mostly of drivers. Some of it is because
+  improving things would require work in several technical areas and people
+  triaging bugs –– and nobody has stepped up to do or fund that work.
+
+* A warranty or support contract with some vendor doesn't entitle you to
+  request fixes from the upstream Linux developers: Such contracts are
+  completely outside the scope of the upstream Linux kernel, its development
+  community, and this document -- even if those handling the issue work for the
+  vendor who issued the contract. If you want to claim your rights, use the
+  vendor's support channel.
+
+* If you never reported an issue to a FLOSS project before, consider skimming
+  guides like `How to ask good questions
+  <https://jvns.ca/blog/good-questions/>`_, `How To Ask Questions The Smart Way
+  <http://www.catb.org/esr/faqs/smart-questions.html>`_, and `How to Report
+  Bugs Effectively <https://www.chiark.greenend.org.uk/~sgtatham/bugs.html>`_,.
+
+With that off the table, find below details for the steps from the detailed
+guide on reporting issues to the Linux kernel developers.
+
+
+Make sure you're using the upstream Linux kernel
+------------------------------------------------
+
+   *Are you facing an issue with a Linux kernel a hardware or software vendor
+   provided? Then in almost all cases you are better off to stop reading this
+   document and reporting the issue to your vendor instead, unless you are
+   willing to install the latest Linux version yourself. Be aware the latter
+   will often be needed anyway to hunt down and fix issues.*
+
+Like most programmers, Linux kernel developers don't like to spend time dealing
+with reports for issues that don't even happen with their current code. It's
+just a waste everybody's time, especially yours. Unfortunately such situations
+easily happen when it comes to the kernel and often leads to frustration on both
+sides. That's because almost all Linux-based kernels pre-installed on devices
+(Computers, Laptops, Smartphones, Routers, …) and most shipped by Linux
+distributors are quite distant from the official Linux kernel as distributed by
+kernel.org: these kernels from these vendors are often ancient from the point of
+Linux development or heavily modified, often both.
+
+Most of these vendor kernels are quite unsuitable for reporting issues to the
+Linux kernel developers: an issue you face with one of them might have been
+fixed by the Linux kernel developers months or years ago already; additionally,
+the modifications and enhancements by the vendor might be causing the issue you
+face, even if they look small or totally unrelated. That's why you should report
+issues with these kernels to the vendor. Its developers should look into the
+report and, in case it turns out to be an upstream issue, fix it directly
+upstream or forward the report there. In practice that often does not work out
+or might not what you want. You thus might want to consider circumventing the
+vendor by installing the very latest Linux kernel core yourself. If that's an
+option for you move ahead in this process, as a later step in this guide will
+explain how to do that once it rules out other potential causes for your issue.
+
+Note, the previous paragraph is starting with the word 'most', as sometimes
+developers in fact are willing to handle reports about issues occurring with
+vendor kernels. If they do in the end highly depends on the developers and the
+issue in question. Your chances are quite good if the distributor applied only
+small modifications to a kernel based on a recent Linux version; that for
+example often holds true for the mainline kernels shipped by Debian GNU/Linux
+Sid or Fedora Rawhide. Some developers will also accept reports about issues
+with kernels from distributions shipping the latest stable kernel, as long as
+it's only slightly modified; that for example is often the case for Arch Linux,
+regular Fedora releases, and openSUSE Tumbleweed. But keep in mind, you better
+want to use a mainline Linux and avoid using a stable kernel for this
+process, as outlined in the section 'Install a fresh kernel for testing' in more
+detail.
+
+Obviously you are free to ignore all this advice and report problems with an old
+or heavily modified vendor kernel to the upstream Linux developers. But note,
+those often get rejected or ignored, so consider yourself warned. But it's still
+better than not reporting the issue at all: sometimes such reports directly or
+indirectly will help to get the issue fixed over time.
+
+
+Search for existing reports, first run
+--------------------------------------
+
+   *Perform a rough search for existing reports with your favorite internet
+   search engine; additionally, check the archives of the Linux Kernel Mailing
+   List (LKML). If you find matching reports, join the discussion instead of
+   sending a new one.*
+
+Reporting an issue that someone else already brought forward is often a waste of
+time for everyone involved, especially you as the reporter. So it's in your own
+interest to thoroughly check if somebody reported the issue already. At this
+step of the process it's okay to just perform a rough search: a later step will
+tell you to perform a more detailed search once you know where your issue needs
+to be reported to. Nevertheless, do not hurry with this step of the reporting
+process, it can save you time and trouble.
+
+Simply search the internet with your favorite search engine first. Afterwards,
+search the `Linux Kernel Mailing List (LKML) archives
+<https://lore.kernel.org/lkml/>`_.
+
+If you get flooded with results consider telling your search engine to limit
+search timeframe to the past month or year. And wherever you search, make sure
+to use good search terms; vary them a few times, too. While doing so try to
+look at the issue from the perspective of someone else: that will help you to
+come up with other words to use as search terms. Also make sure not to use too
+many search terms at once. Remember to search with and without information like
+the name of the kernel driver or the name of the affected hardware component.
+But its exact brand name (say 'ASUS Red Devil Radeon RX 5700 XT Gaming OC')
+often is not much helpful, as it is too specific. Instead try search terms like
+the model line (Radeon 5700 or Radeon 5000) and the code name of the main chip
+('Navi' or 'Navi10') with and without its manufacturer ('AMD').
+
+In case you find an existing report about your issue, join the discussion, as
+you might be able to provide valuable additional information. That can be
+important even when a fix is prepared or in its final stages already, as
+developers might look for people that can provide additional information or
+test a proposed fix. Jump to the section 'Duties after the report went out' for
+details on how to get properly involved.
+
+Note, searching `bugzilla.kernel.org <https://bugzilla.kernel.org/>`_ might also
+be a good idea, as that might provide valuable insights or turn up matching
+reports. If you find the latter, just keep in mind: most subsystems expect
+reports in different places, as described below in the section "Check where you
+need to report your issue". The developers that should take care of the issue
+thus might not even be aware of the bugzilla ticket. Hence, check the ticket if
+the issue already got reported as outlined in this document and if not consider
+doing so.
+
+
+Issue of high priority?
+-----------------------
+
+    *See if the issue you are dealing with qualifies as regression, security
+    issue, or a really severe problem: those are 'issues of high priority' that
+    need special handling in some steps that are about to follow.*
+
+Linus Torvalds and the leading Linux kernel developers want to see some issues
+fixed as soon as possible, hence there are 'issues of high priority' that get
+handled slightly differently in the reporting process. Three type of cases
+qualify: regressions, security issues, and really severe problems.
+
+You deal with a regression if some application or practical use case running
+fine with one Linux kernel works worse or not at all with a newer version
+compiled using a similar configuration. The document
+Documentation/admin-guide/reporting-regressions.rst explains this in more
+detail. It also provides a good deal of other information about regressions you
+might want to be aware of; it for example explains how to add your issue to the
+list of tracked regressions, to ensure it won't fall through the cracks.
+
+What qualifies as security issue is left to your judgment. Consider reading
+Documentation/process/security-bugs.rst before proceeding, as it
+provides additional details how to best handle security issues.
+
+An issue is a 'really severe problem' when something totally unacceptably bad
+happens. That's for example the case when a Linux kernel corrupts the data it's
+handling or damages hardware it's running on. You're also dealing with a severe
+issue when the kernel suddenly stops working with an error message ('kernel
+panic') or without any farewell note at all. Note: do not confuse a 'panic' (a
+fatal error where the kernel stop itself) with a 'Oops' (a recoverable error),
+as the kernel remains running after the latter.
+
+
+Ensure a healthy environment
+----------------------------
+
+    *Make sure it's not the kernel's surroundings that are causing the issue
+    you face.*
+
+Problems that look a lot like a kernel issue are sometimes caused by build or
+runtime environment. It's hard to rule out that problem completely, but you
+should minimize it:
+
+ * Use proven tools when building your kernel, as bugs in the compiler or the
+   binutils can cause the resulting kernel to misbehave.
+
+ * Ensure your computer components run within their design specifications;
+   that's especially important for the main processor, the main memory, and the
+   motherboard. Therefore, stop undervolting or overclocking when facing a
+   potential kernel issue.
+
+ * Try to make sure it's not faulty hardware that is causing your issue. Bad
+   main memory for example can result in a multitude of issues that will
+   manifest itself in problems looking like kernel issues.
+
+ * If you're dealing with a filesystem issue, you might want to check the file
+   system in question with ``fsck``, as it might be damaged in a way that leads
+   to unexpected kernel behavior.
+
+ * When dealing with a regression, make sure it's not something else that
+   changed in parallel to updating the kernel. The problem for example might be
+   caused by other software that was updated at the same time. It can also
+   happen that a hardware component coincidentally just broke when you rebooted
+   into a new kernel for the first time. Updating the systems BIOS or changing
+   something in the BIOS Setup can also lead to problems that on look a lot
+   like a kernel regression.
+
+
+Prepare for emergencies
+-----------------------
+
+    *Create a fresh backup and put system repair and restore tools at hand.*
+
+Reminder, you are dealing with computers, which sometimes do unexpected things,
+especially if you fiddle with crucial parts like the kernel of its operating
+system. That's what you are about to do in this process. Thus, make sure to
+create a fresh backup; also ensure you have all tools at hand to repair or
+reinstall the operating system as well as everything you need to restore the
+backup.
+
+
+Make sure your kernel doesn't get enhanced
+------------------------------------------
+
+    *Ensure your system does not enhance its kernels by building additional
+    kernel modules on-the-fly, which solutions like DKMS might be doing locally
+    without your knowledge.*
+
+The risk your issue report gets ignored or rejected dramatically increases if
+your kernel gets enhanced in any way. That's why you should remove or disable
+mechanisms like akmods and DKMS: those build add-on kernel modules
+automatically, for example when you install a new Linux kernel or boot it for
+the first time. Also remove any modules they might have installed. Then reboot
+before proceeding.
+
+Note, you might not be aware that your system is using one of these solutions:
+they often get set up silently when you install Nvidia's proprietary graphics
+driver, VirtualBox, or other software that requires a some support from a
+module not part of the Linux kernel. That why your might need to uninstall the
+packages with such software to get rid of any 3rd party kernel module.
+
+
+Check 'taint' flag
+------------------
+
+    *Check if your kernel was 'tainted' when the issue occurred, as the event
+    that made the kernel set this flag might be causing the issue you face.*
+
+The kernel marks itself with a 'taint' flag when something happens that might
+lead to follow-up errors that look totally unrelated. The issue you face might
+be such an error if your kernel is tainted. That's why it's in your interest to
+rule this out early before investing more time into this process. This is the
+only reason why this step is here, as this process later will tell you to
+install the latest mainline kernel; you will need to check the taint flag again
+then, as that's when it matters because it's the kernel the report will focus
+on.
+
+On a running system is easy to check if the kernel tainted itself: if ``cat
+/proc/sys/kernel/tainted`` returns '0' then the kernel is not tainted and
+everything is fine. Checking that file is impossible in some situations; that's
+why the kernel also mentions the taint status when it reports an internal
+problem (a 'kernel bug'), a recoverable error (a 'kernel Oops') or a
+non-recoverable error before halting operation (a 'kernel panic'). Look near
+the top of the error messages printed when one of these occurs and search for a
+line starting with 'CPU:'. It should end with 'Not tainted' if the kernel was
+not tainted when it noticed the problem; it was tainted if you see 'Tainted:'
+followed by a few spaces and some letters.
+
+If your kernel is tainted, study Documentation/admin-guide/tainted-kernels.rst
+to find out why. Try to eliminate the reason. Often it's caused by one these
+three things:
+
+ 1. A recoverable error (a 'kernel Oops') occurred and the kernel tainted
+    itself, as the kernel knows it might misbehave in strange ways after that
+    point. In that case check your kernel or system log and look for a section
+    that starts with this::
+
+       Oops: 0000 [#1] SMP
+
+    That's the first Oops since boot-up, as the '#1' between the brackets shows.
+    Every Oops and any other problem that happens after that point might be a
+    follow-up problem to that first Oops, even if both look totally unrelated.
+    Rule this out by getting rid of the cause for the first Oops and reproducing
+    the issue afterwards. Sometimes simply restarting will be enough, sometimes
+    a change to the configuration followed by a reboot can eliminate the Oops.
+    But don't invest too much time into this at this point of the process, as
+    the cause for the Oops might already be fixed in the newer Linux kernel
+    version you are going to install later in this process.
+
+ 2. Your system uses a software that installs its own kernel modules, for
+    example Nvidia's proprietary graphics driver or VirtualBox. The kernel
+    taints itself when it loads such module from external sources (even if
+    they are Open Source): they sometimes cause errors in unrelated kernel
+    areas and thus might be causing the issue you face. You therefore have to
+    prevent those modules from loading when you want to report an issue to the
+    Linux kernel developers. Most of the time the easiest way to do that is:
+    temporarily uninstall such software including any modules they might have
+    installed. Afterwards reboot.
+
+ 3. The kernel also taints itself when it's loading a module that resides in
+    the staging tree of the Linux kernel source. That's a special area for
+    code (mostly drivers) that does not yet fulfill the normal Linux kernel
+    quality standards. When you report an issue with such a module it's
+    obviously okay if the kernel is tainted; just make sure the module in
+    question is the only reason for the taint. If the issue happens in an
+    unrelated area reboot and temporarily block the module from being loaded
+    by specifying ``foo.blacklist=1`` as kernel parameter (replace 'foo' with
+    the name of the module in question).
+
+
+Document how to reproduce issue
+-------------------------------
+
+    *Write down coarsely how to reproduce the issue. If you deal with multiple
+    issues at once, create separate notes for each of them and make sure they
+    work independently on a freshly booted system. That's needed, as each issue
+    needs to get reported to the kernel developers separately, unless they are
+    strongly entangled.*
+
+If you deal with multiple issues at once, you'll have to report each of them
+separately, as they might be handled by different developers. Describing
+various issues in one report also makes it quite difficult for others to tear
+it apart. Hence, only combine issues in one report if they are very strongly
+entangled.
+
+Additionally, during the reporting process you will have to test if the issue
+happens with other kernel versions. Therefore, it will make your work easier if
+you know exactly how to reproduce an issue quickly on a freshly booted system.
+
+Note: it's often fruitless to report issues that only happened once, as they
+might be caused by a bit flip due to cosmic radiation. That's why you should
+try to rule that out by reproducing the issue before going further. Feel free
+to ignore this advice if you are experienced enough to tell a one-time error
+due to faulty hardware apart from a kernel issue that rarely happens and thus
+is hard to reproduce.
+
+
+Regression in stable or longterm kernel?
+----------------------------------------
+
+    *If you are facing a regression within a stable or longterm version line
+    (say something broke when updating from 5.10.4 to 5.10.5), scroll down to
+    'Dealing with regressions within a stable and longterm kernel line'.*
+
+Regression within a stable and longterm kernel version line are something the
+Linux developers want to fix badly, as such issues are even more unwanted than
+regression in the main development branch, as they can quickly affect a lot of
+people. The developers thus want to learn about such issues as quickly as
+possible, hence there is a streamlined process to report them. Note,
+regressions with newer kernel version line (say something broke when switching
+from 5.9.15 to 5.10.5) do not qualify.
+
+
+Check where you need to report your issue
+-----------------------------------------
+
+    *Locate the driver or kernel subsystem that seems to be causing the issue.
+    Find out how and where its developers expect reports. Note: most of the
+    time this won't be bugzilla.kernel.org, as issues typically need to be sent
+    by mail to a maintainer and a public mailing list.*
+
+It's crucial to send your report to the right people, as the Linux kernel is a
+big project and most of its developers are only familiar with a small subset of
+it. Quite a few programmers for example only care for just one driver, for
+example one for a WiFi chip; its developer likely will only have small or no
+knowledge about the internals of remote or unrelated "subsystems", like the TCP
+stack, the PCIe/PCI subsystem, memory management or file systems.
+
+Problem is: the Linux kernel lacks a central bug tracker where you can simply
+file your issue and make it reach the developers that need to know about it.
+That's why you have to find the right place and way to report issues yourself.
+You can do that with the help of a script (see below), but it mainly targets
+kernel developers and experts. For everybody else the MAINTAINERS file is the
+better place.
+
+How to read the MAINTAINERS file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+To illustrate how to use the :ref:`MAINTAINERS <maintainers>` file, let's assume
+the WiFi in your Laptop suddenly misbehaves after updating the kernel. In that
+case it's likely an issue in the WiFi driver. Obviously it could also be some
+code it builds upon, but unless you suspect something like that stick to the
+driver. If it's really something else, the driver's developers will get the
+right people involved.
+
+Sadly, there is no way to check which code is driving a particular hardware
+component that is both universal and easy.
+
+In case of a problem with the WiFi driver you for example might want to look at
+the output of ``lspci -k``, as it lists devices on the PCI/PCIe bus and the
+kernel module driving it::
+
+       [user@something ~]$ lspci -k
+       [...]
+       3a:00.0 Network controller: Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter (rev 32)
+         Subsystem: Bigfoot Networks, Inc. Device 1535
+         Kernel driver in use: ath10k_pci
+         Kernel modules: ath10k_pci
+       [...]
+
+But this approach won't work if your WiFi chip is connected over USB or some
+other internal bus. In those cases you might want to check your WiFi manager or
+the output of ``ip link``. Look for the name of the problematic network
+interface, which might be something like 'wlp58s0'. This name can be used like
+this to find the module driving it::
+
+       [user@something ~]$ realpath --relative-to=/sys/module/ /sys/class/net/wlp58s0/device/driver/module
+       ath10k_pci
+
+In case tricks like these don't bring you any further, try to search the
+internet on how to narrow down the driver or subsystem in question. And if you
+are unsure which it is: just try your best guess, somebody will help you if you
+guessed poorly.
+
+Once you know the driver or subsystem, you want to search for it in the
+MAINTAINERS file. In the case of 'ath10k_pci' you won't find anything, as the
+name is too specific. Sometimes you will need to search on the net for help;
+but before doing so, try a somewhat shorted or modified name when searching the
+MAINTAINERS file, as then you might find something like this::
+
+       QUALCOMM ATHEROS ATH10K WIRELESS DRIVER
+       Mail:          A. Some Human <shuman@example.com>
+       Mailing list:  ath10k@lists.infradead.org
+       Status:        Supported
+       Web-page:      https://wireless.wiki.kernel.org/en/users/Drivers/ath10k
+       SCM:           git git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git
+       Files:         drivers/net/wireless/ath/ath10k/
+
+Note: the line description will be abbreviations, if you read the plain
+MAINTAINERS file found in the root of the Linux source tree. 'Mail:' for
+example will be 'M:', 'Mailing list:' will be 'L', and 'Status:' will be 'S:'.
+A section near the top of the file explains these and other abbreviations.
+
+First look at the line 'Status'. Ideally it should be 'Supported' or
+'Maintained'. If it states 'Obsolete' then you are using some outdated approach
+that was replaced by a newer solution you need to switch to. Sometimes the code
+only has someone who provides 'Odd Fixes' when feeling motivated. And with
+'Orphan' you are totally out of luck, as nobody takes care of the code anymore.
+That only leaves these options: arrange yourself to live with the issue, fix it
+yourself, or find a programmer somewhere willing to fix it.
+
+After checking the status, look for a line starting with 'bugs:': it will tell
+you where to find a subsystem specific bug tracker to file your issue. The
+example above does not have such a line. That is the case for most sections, as
+Linux kernel development is completely driven by mail. Very few subsystems use
+a bug tracker, and only some of those rely on bugzilla.kernel.org.
+
+In this and many other cases you thus have to look for lines starting with
+'Mail:' instead. Those mention the name and the email addresses for the
+maintainers of the particular code. Also look for a line starting with 'Mailing
+list:', which tells you the public mailing list where the code is developed.
+Your report later needs to go by mail to those addresses. Additionally, for all
+issue reports sent by email, make sure to add the Linux Kernel Mailing List
+(LKML) <linux-kernel@vger.kernel.org> to CC. Don't omit either of the mailing
+lists when sending your issue report by mail later! Maintainers are busy people
+and might leave some work for other developers on the subsystem specific list;
+and LKML is important to have one place where all issue reports can be found.
+
+
+Finding the maintainers with the help of a script
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For people that have the Linux sources at hand there is a second option to find
+the proper place to report: the script 'scripts/get_maintainer.pl' which tries
+to find all people to contact. It queries the MAINTAINERS file and needs to be
+called with a path to the source code in question. For drivers compiled as
+module if often can be found with a command like this::
+
+       $ modinfo ath10k_pci | grep filename | sed 's!/lib/modules/.*/kernel/!!; s!filename:!!; s!\.ko\(\|\.xz\)!!'
+       drivers/net/wireless/ath/ath10k/ath10k_pci.ko
+
+Pass parts of this to the script::
+
+       $ ./scripts/get_maintainer.pl -f drivers/net/wireless/ath/ath10k*
+       Some Human <shuman@example.com> (supporter:QUALCOMM ATHEROS ATH10K WIRELESS DRIVER)
+       Another S. Human <asomehuman@example.com> (maintainer:NETWORKING DRIVERS)
+       ath10k@lists.infradead.org (open list:QUALCOMM ATHEROS ATH10K WIRELESS DRIVER)
+       linux-wireless@vger.kernel.org (open list:NETWORKING DRIVERS (WIRELESS))
+       netdev@vger.kernel.org (open list:NETWORKING DRIVERS)
+       linux-kernel@vger.kernel.org (open list)
+
+Don't sent your report to all of them. Send it to the maintainers, which the
+script calls "supporter:"; additionally CC the most specific mailing list for
+the code as well as the Linux Kernel Mailing List (LKML). In this case you thus
+would need to send the report to 'Some Human <shuman@example.com>' with
+'ath10k@lists.infradead.org' and 'linux-kernel@vger.kernel.org' in CC.
+
+Note: in case you cloned the Linux sources with git you might want to call
+``get_maintainer.pl`` a second time with ``--git``. The script then will look
+at the commit history to find which people recently worked on the code in
+question, as they might be able to help. But use these results with care, as it
+can easily send you in a wrong direction. That for example happens quickly in
+areas rarely changed (like old or unmaintained drivers): sometimes such code is
+modified during tree-wide cleanups by developers that do not care about the
+particular driver at all.
+
+
+Search for existing reports, second run
+---------------------------------------
+
+    *Search the archives of the bug tracker or mailing list in question
+    thoroughly for reports that might match your issue. If you find anything,
+    join the discussion instead of sending a new report.*
+
+As mentioned earlier already: reporting an issue that someone else already
+brought forward is often a waste of time for everyone involved, especially you
+as the reporter. That's why you should search for existing report again, now
+that you know where they need to be reported to. If it's mailing list, you will
+often find its archives on `lore.kernel.org <https://lore.kernel.org/>`_.
+
+But some list are hosted in different places. That for example is the case for
+the ath10k WiFi driver used as example in the previous step. But you'll often
+find the archives for these lists easily on the net. Searching for 'archive
+ath10k@lists.infradead.org' for example will lead you to the `Info page for the
+ath10k mailing list <https://lists.infradead.org/mailman/listinfo/ath10k>`_,
+which at the top links to its
+`list archives <https://lists.infradead.org/pipermail/ath10k/>`_. Sadly this and
+quite a few other lists miss a way to search the archives. In those cases use a
+regular internet search engine and add something like
+'site:lists.infradead.org/pipermail/ath10k/' to your search terms, which limits
+the results to the archives at that URL.
+
+It's also wise to check the internet, LKML and maybe bugzilla.kernel.org again
+at this point. If your report needs to be filed in a bug tracker, you may want
+to check the mailing list archives for the subsystem as well, as someone might
+have reported it only there.
+
+For details how to search and what to do if you find matching reports see
+"Search for existing reports, first run" above.
+
+Do not hurry with this step of the reporting process: spending 30 to 60 minutes
+or even more time can save you and others quite a lot of time and trouble.
+
+
+Install a fresh kernel for testing
+----------------------------------
+
+    *Unless you are already running the latest 'mainline' Linux kernel, better
+    go and install it for the reporting process. Testing and reporting with
+    the latest 'stable' Linux can be an acceptable alternative in some
+    situations; during the merge window that actually might be even the best
+    approach, but in that development phase it can be an even better idea to
+    suspend your efforts for a few days anyway. Whatever version you choose,
+    ideally use a 'vanilla' built. Ignoring all of this advice will dramatically
+    increase the risk your report will be rejected or ignored.*
+
+As mentioned in the detailed explanation for the first step already: Like most
+programmers, Linux kernel developers don't like to spend time dealing with
+reports for issues that don't even happen with the current code. It's just a
+waste everybody's time, especially yours. That's why it's in everybody's
+interest that you confirm the issue still exists with the latest upstream code
+before reporting it. You are free to ignore this advice, but as outlined
+earlier: doing so dramatically increases the risk that your issue report might
+get rejected or simply ignored.
+
+In the scope of the kernel "latest upstream" normally means:
+
+ * Install a mainline kernel; the latest stable kernel can be an option, but
+   most of the time is better avoided. Longterm kernels (sometimes called 'LTS
+   kernels') are unsuitable at this point of the process. The next subsection
+   explains all of this in more detail.
+
+ * The over next subsection describes way to obtain and install such a kernel.
+   It also outlines that using a pre-compiled kernel are fine, but better are
+   vanilla, which means: it was built using Linux sources taken straight `from
+   kernel.org <https://kernel.org/>`_ and not modified or enhanced in any way.
+
+Choosing the right version for testing
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Head over to `kernel.org <https://kernel.org/>`_ to find out which version you
+want to use for testing. Ignore the big yellow button that says 'Latest release'
+and look a little lower at the table. At its top you'll see a line starting with
+mainline, which most of the time will point to a pre-release with a version
+number like '5.8-rc2'. If that's the case, you'll want to use this mainline
+kernel for testing, as that where all fixes have to be applied first. Do not let
+that 'rc' scare you, these 'development kernels' are pretty reliable — and you
+made a backup, as you were instructed above, didn't you?
+
+In about two out of every nine to ten weeks, mainline might point you to a
+proper release with a version number like '5.7'. If that happens, consider
+suspending the reporting process until the first pre-release of the next
+version (5.8-rc1) shows up on kernel.org. That's because the Linux development
+cycle then is in its two-week long 'merge window'. The bulk of the changes and
+all intrusive ones get merged for the next release during this time. It's a bit
+more risky to use mainline during this period. Kernel developers are also often
+quite busy then and might have no spare time to deal with issue reports. It's
+also quite possible that one of the many changes applied during the merge
+window fixes the issue you face; that's why you soon would have to retest with
+a newer kernel version anyway, as outlined below in the section 'Duties after
+the report went out'.
+
+That's why it might make sense to wait till the merge window is over. But don't
+to that if you're dealing with something that shouldn't wait. In that case
+consider obtaining the latest mainline kernel via git (see below) or use the
+latest stable version offered on kernel.org. Using that is also acceptable in
+case mainline for some reason does currently not work for you. An in general:
+using it for reproducing the issue is also better than not reporting it issue
+at all.
+
+Better avoid using the latest stable kernel outside merge windows, as all fixes
+must be applied to mainline first. That's why checking the latest mainline
+kernel is so important: any issue you want to see fixed in older version lines
+needs to be fixed in mainline first before it can get backported, which can
+take a few days or weeks. Another reason: the fix you hope for might be too
+hard or risky for backporting; reporting the issue again hence is unlikely to
+change anything.
+
+These aspects are also why longterm kernels (sometimes called "LTS kernels")
+are unsuitable for this part of the reporting process: they are to distant from
+the current code. Hence go and test mainline first and follow the process
+further: if the issue doesn't occur with mainline it will guide you how to get
+it fixed in older version lines, if that's in the cards for the fix in question.
+
+How to obtain a fresh Linux kernel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Using a pre-compiled kernel**: This is often the quickest, easiest, and safest
+way for testing — especially is you are unfamiliar with the Linux kernel. The
+problem: most of those shipped by distributors or add-on repositories are build
+from modified Linux sources. They are thus not vanilla and therefore often
+unsuitable for testing and issue reporting: the changes might cause the issue
+you face or influence it somehow.
+
+But you are in luck if you are using a popular Linux distribution: for quite a
+few of them you'll find repositories on the net that contain packages with the
+latest mainline or stable Linux built as vanilla kernel. It's totally okay to
+use these, just make sure from the repository's description they are vanilla or
+at least close to it. Additionally ensure the packages contain the latest
+versions as offered on kernel.org. The packages are likely unsuitable if they
+are older than a week, as new mainline and stable kernels typically get released
+at least once a week.
+
+Please note that you might need to build your own kernel manually later: that's
+sometimes needed for debugging or testing fixes, as described later in this
+document. Also be aware that pre-compiled kernels might lack debug symbols that
+are needed to decode messages the kernel prints when a panic, Oops, warning, or
+BUG occurs; if you plan to decode those, you might be better off compiling a
+kernel yourself (see the end of this subsection and the section titled 'Decode
+failure messages' for details).
+
+**Using git**: Developers and experienced Linux users familiar with git are
+often best served by obtaining the latest Linux kernel sources straight from the
+`official development repository on kernel.org
+<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/>`_.
+Those are likely a bit ahead of the latest mainline pre-release. Don't worry
+about it: they are as reliable as a proper pre-release, unless the kernel's
+development cycle is currently in the middle of a merge window. But even then
+they are quite reliable.
+
+**Conventional**: People unfamiliar with git are often best served by
+downloading the sources as tarball from `kernel.org <https://kernel.org/>`_.
+
+How to actually build a kernel is not described here, as many websites explain
+the necessary steps already. If you are new to it, consider following one of
+those how-to's that suggest to use ``make localmodconfig``, as that tries to
+pick up the configuration of your current kernel and then tries to adjust it
+somewhat for your system. That does not make the resulting kernel any better,
+but quicker to compile.
+
+Note: If you are dealing with a panic, Oops, warning, or BUG from the kernel,
+please try to enable CONFIG_KALLSYMS when configuring your kernel.
+Additionally, enable CONFIG_DEBUG_KERNEL and CONFIG_DEBUG_INFO, too; the
+latter is the relevant one of those two, but can only be reached if you enable
+the former. Be aware CONFIG_DEBUG_INFO increases the storage space required to
+build a kernel by quite a bit. But that's worth it, as these options will allow
+you later to pinpoint the exact line of code that triggers your issue. The
+section 'Decode failure messages' below explains this in more detail.
+
+But keep in mind: Always keep a record of the issue encountered in case it is
+hard to reproduce. Sending an undecoded report is better than not reporting
+the issue at all.
+
+
+Check 'taint' flag
+------------------
+
+    *Ensure the kernel you just installed does not 'taint' itself when
+    running.*
+
+As outlined above in more detail already: the kernel sets a 'taint' flag when
+something happens that can lead to follow-up errors that look totally
+unrelated. That's why you need to check if the kernel you just installed does
+not set this flag. And if it does, you in almost all the cases needs to
+eliminate the reason for it before you reporting issues that occur with it. See
+the section above for details how to do that.
+
+
+Reproduce issue with the fresh kernel
+-------------------------------------
+
+    *Reproduce the issue with the kernel you just installed. If it doesn't show
+    up there, scroll down to the instructions for issues only happening with
+    stable and longterm kernels.*
+
+Check if the issue occurs with the fresh Linux kernel version you just
+installed. If it was fixed there already, consider sticking with this version
+line and abandoning your plan to report the issue. But keep in mind that other
+users might still be plagued by it, as long as it's not fixed in either stable
+and longterm version from kernel.org (and thus vendor kernels derived from
+those). If you prefer to use one of those or just want to help their users,
+head over to the section "Details about reporting issues only occurring in
+older kernel version lines" below.
+
+
+Optimize description to reproduce issue
+---------------------------------------
+
+    *Optimize your notes: try to find and write the most straightforward way to
+    reproduce your issue. Make sure the end result has all the important
+    details, and at the same time is easy to read and understand for others
+    that hear about it for the first time. And if you learned something in this
+    process, consider searching again for existing reports about the issue.*
+
+An unnecessarily complex report will make it hard for others to understand your
+report. Thus try to find a reproducer that's straight forward to describe and
+thus easy to understand in written form. Include all important details, but at
+the same time try to keep it as short as possible.
+
+In this in the previous steps you likely have learned a thing or two about the
+issue you face. Use this knowledge and search again for existing reports
+instead you can join.
+
+
+Decode failure messages
+-----------------------
+
+    *If your failure involves a 'panic', 'Oops', 'warning', or 'BUG', consider
+    decoding the kernel log to find the line of code that triggered the error.*
+
+When the kernel detects an internal problem, it will log some information about
+the executed code. This makes it possible to pinpoint the exact line in the
+source code that triggered the issue and shows how it was called. But that only
+works if you enabled CONFIG_DEBUG_INFO and CONFIG_KALLSYMS when configuring
+your kernel. If you did so, consider to decode the information from the
+kernel's log. That will make it a lot easier to understand what lead to the
+'panic', 'Oops', 'warning', or 'BUG', which increases the chances that someone
+can provide a fix.
+
+Decoding can be done with a script you find in the Linux source tree. If you
+are running a kernel you compiled yourself earlier, call it like this::
+
+       [user@something ~]$ sudo dmesg | ./linux-5.10.5/scripts/decode_stacktrace.sh ./linux-5.10.5/vmlinux
+
+If you are running a packaged vanilla kernel, you will likely have to install
+the corresponding packages with debug symbols. Then call the script (which you
+might need to get from the Linux sources if your distro does not package it)
+like this::
+
+       [user@something ~]$ sudo dmesg | ./linux-5.10.5/scripts/decode_stacktrace.sh \
+        /usr/lib/debug/lib/modules/5.10.10-4.1.x86_64/vmlinux /usr/src/kernels/5.10.10-4.1.x86_64/
+
+The script will work on log lines like the following, which show the address of
+the code the kernel was executing when the error occurred::
+
+       [   68.387301] RIP: 0010:test_module_init+0x5/0xffa [test_module]
+
+Once decoded, these lines will look like this::
+
+       [   68.387301] RIP: 0010:test_module_init (/home/username/linux-5.10.5/test-module/test-module.c:16) test_module
+
+In this case the executed code was built from the file
+'~/linux-5.10.5/test-module/test-module.c' and the error occurred by the
+instructions found in line '16'.
+
+The script will similarly decode the addresses mentioned in the section
+starting with 'Call trace', which show the path to the function where the
+problem occurred. Additionally, the script will show the assembler output for
+the code section the kernel was executing.
+
+Note, if you can't get this to work, simply skip this step and mention the
+reason for it in the report. If you're lucky, it might not be needed. And if it
+is, someone might help you to get things going. Also be aware this is just one
+of several ways to decode kernel stack traces. Sometimes different steps will
+be required to retrieve the relevant details. Don't worry about that, if that's
+needed in your case, developers will tell you what to do.
+
+
+Special care for regressions
+----------------------------
+
+    *If your problem is a regression, try to narrow down when the issue was
+    introduced as much as possible.*
+
+Linux lead developer Linus Torvalds insists that the Linux kernel never
+worsens, that's why he deems regressions as unacceptable and wants to see them
+fixed quickly. That's why changes that introduced a regression are often
+promptly reverted if the issue they cause can't get solved quickly any other
+way. Reporting a regression is thus a bit like playing a kind of trump card to
+get something quickly fixed. But for that to happen the change that's causing
+the regression needs to be known. Normally it's up to the reporter to track
+down the culprit, as maintainers often won't have the time or setup at hand to
+reproduce it themselves.
+
+To find the change there is a process called 'bisection' which the document
+Documentation/admin-guide/bug-bisect.rst describes in detail. That process
+will often require you to build about ten to twenty kernel images, trying to
+reproduce the issue with each of them before building the next. Yes, that takes
+some time, but don't worry, it works a lot quicker than most people assume.
+Thanks to a 'binary search' this will lead you to the one commit in the source
+code management system that's causing the regression. Once you find it, search
+the net for the subject of the change, its commit id and the shortened commit id
+(the first 12 characters of the commit id). This will lead you to existing
+reports about it, if there are any.
+
+Note, a bisection needs a bit of know-how, which not everyone has, and quite a
+bit of effort, which not everyone is willing to invest. Nevertheless, it's
+highly recommended performing a bisection yourself. If you really can't or
+don't want to go down that route at least find out which mainline kernel
+introduced the regression. If something for example breaks when switching from
+5.5.15 to 5.8.4, then try at least all the mainline releases in that area (5.6,
+5.7 and 5.8) to check when it first showed up. Unless you're trying to find a
+regression in a stable or longterm kernel, avoid testing versions which number
+has three sections (5.6.12, 5.7.8), as that makes the outcome hard to
+interpret, which might render your testing useless. Once you found the major
+version which introduced the regression, feel free to move on in the reporting
+process. But keep in mind: it depends on the issue at hand if the developers
+will be able to help without knowing the culprit. Sometimes they might
+recognize from the report want went wrong and can fix it; other times they will
+be unable to help unless you perform a bisection.
+
+When dealing with regressions make sure the issue you face is really caused by
+the kernel and not by something else, as outlined above already.
+
+In the whole process keep in mind: an issue only qualifies as regression if the
+older and the newer kernel got built with a similar configuration. This can be
+achieved by using ``make olddefconfig``, as explained in more detail by
+Documentation/admin-guide/reporting-regressions.rst; that document also
+provides a good deal of other information about regressions you might want to be
+aware of.
+
+
+Write and send the report
+-------------------------
+
+    *Start to compile the report by writing a detailed description about the
+    issue. Always mention a few things: the latest kernel version you installed
+    for reproducing, the Linux Distribution used, and your notes on how to
+    reproduce the issue. Ideally, make the kernel's build configuration
+    (.config) and the output from ``dmesg`` available somewhere on the net and
+    link to it. Include or upload all other information that might be relevant,
+    like the output/screenshot of an Oops or the output from ``lspci``. Once
+    you wrote this main part, insert a normal length paragraph on top of it
+    outlining the issue and the impact quickly. On top of this add one sentence
+    that briefly describes the problem and gets people to read on. Now give the
+    thing a descriptive title or subject that yet again is shorter. Then you're
+    ready to send or file the report like the MAINTAINERS file told you, unless
+    you are dealing with one of those 'issues of high priority': they need
+    special care which is explained in 'Special handling for high priority
+    issues' below.*
+
+Now that you have prepared everything it's time to write your report. How to do
+that is partly explained by the three documents linked to in the preface above.
+That's why this text will only mention a few of the essentials as well as
+things specific to the Linux kernel.
+
+There is one thing that fits both categories: the most crucial parts of your
+report are the title/subject, the first sentence, and the first paragraph.
+Developers often get quite a lot of mail. They thus often just take a few
+seconds to skim a mail before deciding to move on or look closer. Thus: the
+better the top section of your report, the higher are the chances that someone
+will look into it and help you. And that is why you should ignore them for now
+and write the detailed report first. ;-)
+
+Things each report should mention
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Describe in detail how your issue happens with the fresh vanilla kernel you
+installed. Try to include the step-by-step instructions you wrote and optimized
+earlier that outline how you and ideally others can reproduce the issue; in
+those rare cases where that's impossible try to describe what you did to
+trigger it.
+
+Also include all the relevant information others might need to understand the
+issue and its environment. What's actually needed depends a lot on the issue,
+but there are some things you should include always:
+
+ * the output from ``cat /proc/version``, which contains the Linux kernel
+   version number and the compiler it was built with.
+
+ * the Linux distribution the machine is running (``hostnamectl | grep
+   "Operating System"``)
+
+ * the architecture of the CPU and the operating system (``uname -mi``)
+
+ * if you are dealing with a regression and performed a bisection, mention the
+   subject and the commit-id of the change that is causing it.
+
+In a lot of cases it's also wise to make two more things available to those
+that read your report:
+
+ * the configuration used for building your Linux kernel (the '.config' file)
+
+ * the kernel's messages that you get from ``dmesg`` written to a file. Make
+   sure that it starts with a line like 'Linux version 5.8-1
+   (foobar@example.com) (gcc (GCC) 10.2.1, GNU ld version 2.34) #1 SMP Mon Aug
+   3 14:54:37 UTC 2020' If it's missing, then important messages from the first
+   boot phase already got discarded. In this case instead consider using
+   ``journalctl -b 0 -k``; alternatively you can also reboot, reproduce the
+   issue and call ``dmesg`` right afterwards.
+
+These two files are big, that's why it's a bad idea to put them directly into
+your report. If you are filing the issue in a bug tracker then attach them to
+the ticket. If you report the issue by mail do not attach them, as that makes
+the mail too large; instead do one of these things:
+
+ * Upload the files somewhere public (your website, a public file paste
+   service, a ticket created just for this purpose on `bugzilla.kernel.org
+   <https://bugzilla.kernel.org/>`_, ...) and include a link to them in your
+   report. Ideally use something where the files stay available for years, as
+   they could be useful to someone many years from now; this for example can
+   happen if five or ten years from now a developer works on some code that was
+   changed just to fix your issue.
+
+ * Put the files aside and mention you will send them later in individual
+   replies to your own mail. Just remember to actually do that once the report
+   went out. ;-)
+
+Things that might be wise to provide
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Depending on the issue you might need to add more background data. Here are a
+few suggestions what often is good to provide:
+
+ * If you are dealing with a 'warning', an 'OOPS' or a 'panic' from the kernel,
+   include it. If you can't copy'n'paste it, try to capture a netconsole trace
+   or at least take a picture of the screen.
+
+ * If the issue might be related to your computer hardware, mention what kind
+   of system you use. If you for example have problems with your graphics card,
+   mention its manufacturer, the card's model, and what chip is uses. If it's a
+   laptop mention its name, but try to make sure it's meaningful. 'Dell XPS 13'
+   for example is not, because it might be the one from 2012; that one looks
+   not that different from the one sold today, but apart from that the two have
+   nothing in common. Hence, in such cases add the exact model number, which
+   for example are '9380' or '7390' for XPS 13 models introduced during 2019.
+   Names like 'Lenovo Thinkpad T590' are also somewhat ambiguous: there are
+   variants of this laptop with and without a dedicated graphics chip, so try
+   to find the exact model name or specify the main components.
+
+ * Mention the relevant software in use. If you have problems with loading
+   modules, you want to mention the versions of kmod, systemd, and udev in use.
+   If one of the DRM drivers misbehaves, you want to state the versions of
+   libdrm and Mesa; also specify your Wayland compositor or the X-Server and
+   its driver. If you have a filesystem issue, mention the version of
+   corresponding filesystem utilities (e2fsprogs, btrfs-progs, xfsprogs, ...).
+
+ * Gather additional information from the kernel that might be of interest. The
+   output from ``lspci -nn`` will for example help others to identify what
+   hardware you use. If you have a problem with hardware you even might want to
+   make the output from ``sudo lspci -vvv`` available, as that provides
+   insights how the components were configured. For some issues it might be
+   good to include the contents of files like ``/proc/cpuinfo``,
+   ``/proc/ioports``, ``/proc/iomem``, ``/proc/modules``, or
+   ``/proc/scsi/scsi``. Some subsystem also offer tools to collect relevant
+   information. One such tool is ``alsa-info.sh`` `which the audio/sound
+   subsystem developers provide <https://www.alsa-project.org/wiki/AlsaInfo>`_.
+
+Those examples should give your some ideas of what data might be wise to
+attach, but you have to think yourself what will be helpful for others to know.
+Don't worry too much about forgetting something, as developers will ask for
+additional details they need. But making everything important available from
+the start increases the chance someone will take a closer look.
+
+
+The important part: the head of your report
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Now that you have the detailed part of the report prepared let's get to the
+most important section: the first few sentences. Thus go to the top, add
+something like 'The detailed description:' before the part you just wrote and
+insert two newlines at the top. Now write one normal length paragraph that
+describes the issue roughly. Leave out all boring details and focus on the
+crucial parts readers need to know to understand what this is all about; if you
+think this bug affects a lot of users, mention this to get people interested.
+
+Once you did that insert two more lines at the top and write a one sentence
+summary that explains quickly what the report is about. After that you have to
+get even more abstract and write an even shorter subject/title for the report.
+
+Now that you have written this part take some time to optimize it, as it is the
+most important parts of your report: a lot of people will only read this before
+they decide if reading the rest is time well spent.
+
+Now send or file the report like the :ref:`MAINTAINERS <maintainers>` file told
+you, unless it's one of those 'issues of high priority' outlined earlier: in
+that case please read the next subsection first before sending the report on
+its way.
+
+Special handling for high priority issues
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Reports for high priority issues need special handling.
+
+**Severe issues**: make sure the subject or ticket title as well as the first
+paragraph makes the severeness obvious.
+
+**Regressions**: make the report's subject start with '[REGRESSION]'.
+
+In case you performed a successful bisection, use the title of the change that
+introduced the regression as the second part of your subject. Make the report
+also mention the commit id of the culprit. In case of an unsuccessful bisection,
+make your report mention the latest tested version that's working fine (say 5.7)
+and the oldest where the issue occurs (say 5.8-rc1).
+
+When sending the report by mail, CC the Linux regressions mailing list
+(regressions@lists.linux.dev). In case the report needs to be filed to some web
+tracker, proceed to do so. Once filed, forward the report by mail to the
+regressions list; CC the maintainer and the mailing list for the subsystem in
+question. Make sure to inline the forwarded report, hence do not attach it.
+Also add a short note at the top where you mention the URL to the ticket.
+
+When mailing or forwarding the report, in case of a successful bisection add the
+author of the culprit to the recipients; also CC everyone in the signed-off-by
+chain, which you find at the end of its commit message.
+
+**Security issues**: for these issues your will have to evaluate if a
+short-term risk to other users would arise if details were publicly disclosed.
+If that's not the case simply proceed with reporting the issue as described.
+For issues that bear such a risk you will need to adjust the reporting process
+slightly:
+
+ * If the MAINTAINERS file instructed you to report the issue by mail, do not
+   CC any public mailing lists.
+
+ * If you were supposed to file the issue in a bug tracker make sure to mark
+   the ticket as 'private' or 'security issue'. If the bug tracker does not
+   offer a way to keep reports private, forget about it and send your report as
+   a private mail to the maintainers instead.
+
+In both cases make sure to also mail your report to the addresses the
+MAINTAINERS file lists in the section 'security contact'. Ideally directly CC
+them when sending the report by mail. If you filed it in a bug tracker, forward
+the report's text to these addresses; but on top of it put a small note where
+you mention that you filed it with a link to the ticket.
+
+See Documentation/process/security-bugs.rst for more information.
+
+
+Duties after the report went out
+--------------------------------
+
+    *Wait for reactions and keep the thing rolling until you can accept the
+    outcome in one way or the other. Thus react publicly and in a timely manner
+    to any inquiries. Test proposed fixes. Do proactive testing: retest with at
+    least every first release candidate (RC) of a new mainline version and
+    report your results. Send friendly reminders if things stall. And try to
+    help yourself, if you don't get any help or if it's unsatisfying.*
+
+If your report was good and you are really lucky then one of the developers
+might immediately spot what's causing the issue; they then might write a patch
+to fix it, test it, and send it straight for integration in mainline while
+tagging it for later backport to stable and longterm kernels that need it. Then
+all you need to do is reply with a 'Thank you very much' and switch to a version
+with the fix once it gets released.
+
+But this ideal scenario rarely happens. That's why the job is only starting
+once you got the report out. What you'll have to do depends on the situations,
+but often it will be the things listed below. But before digging into the
+details, here are a few important things you need to keep in mind for this part
+of the process.
+
+
+General advice for further interactions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**Always reply in public**: When you filed the issue in a bug tracker, always
+reply there and do not contact any of the developers privately about it. For
+mailed reports always use the 'Reply-all' function when replying to any mails
+you receive. That includes mails with any additional data you might want to add
+to your report: go to your mail applications 'Sent' folder and use 'reply-all'
+on your mail with the report. This approach will make sure the public mailing
+list(s) and everyone else that gets involved over time stays in the loop; it
+also keeps the mail thread intact, which among others is really important for
+mailing lists to group all related mails together.
+
+There are just two situations where a comment in a bug tracker or a 'Reply-all'
+is unsuitable:
+
+ * Someone tells you to send something privately.
+
+ * You were told to send something, but noticed it contains sensitive
+   information that needs to be kept private. In that case it's okay to send it
+   in private to the developer that asked for it. But note in the ticket or a
+   mail that you did that, so everyone else knows you honored the request.
+
+**Do research before asking for clarifications or help**: In this part of the
+process someone might tell you to do something that requires a skill you might
+not have mastered yet. For example, you might be asked to use some test tools
+you never have heard of yet; or you might be asked to apply a patch to the
+Linux kernel sources to test if it helps. In some cases it will be fine sending
+a reply asking for instructions how to do that. But before going that route try
+to find the answer own your own by searching the internet; alternatively
+consider asking in other places for advice. For example ask a friend or post
+about it to a chatroom or forum you normally hang out.
+
+**Be patient**: If you are really lucky you might get a reply to your report
+within a few hours. But most of the time it will take longer, as maintainers
+are scattered around the globe and thus might be in a different time zone – one
+where they already enjoy their night away from keyboard.
+
+In general, kernel developers will take one to five business days to respond to
+reports. Sometimes it will take longer, as they might be busy with the merge
+windows, other work, visiting developer conferences, or simply enjoying a long
+summer holiday.
+
+The 'issues of high priority' (see above for an explanation) are an exception
+here: maintainers should address them as soon as possible; that's why you
+should wait a week at maximum (or just two days if it's something urgent)
+before sending a friendly reminder.
+
+Sometimes the maintainer might not be responding in a timely manner; other
+times there might be disagreements, for example if an issue qualifies as
+regression or not. In such cases raise your concerns on the mailing list and
+ask others for public or private replies how to move on. If that fails, it
+might be appropriate to get a higher authority involved. In case of a WiFi
+driver that would be the wireless maintainers; if there are no higher level
+maintainers or all else fails, it might be one of those rare situations where
+it's okay to get Linus Torvalds involved.
+
+**Proactive testing**: Every time the first pre-release (the 'rc1') of a new
+mainline kernel version gets released, go and check if the issue is fixed there
+or if anything of importance changed. Mention the outcome in the ticket or in a
+mail you sent as reply to your report (make sure it has all those in the CC
+that up to that point participated in the discussion). This will show your
+commitment and that you are willing to help. It also tells developers if the
+issue persists and makes sure they do not forget about it. A few other
+occasional retests (for example with rc3, rc5 and the final) are also a good
+idea, but only report your results if something relevant changed or if you are
+writing something anyway.
+
+With all these general things off the table let's get into the details of how
+to help to get issues resolved once they were reported.
+
+Inquires and testing request
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Here are your duties in case you got replies to your report:
+
+**Check who you deal with**: Most of the time it will be the maintainer or a
+developer of the particular code area that will respond to your report. But as
+issues are normally reported in public it could be anyone that's replying —
+including people that want to help, but in the end might guide you totally off
+track with their questions or requests. That rarely happens, but it's one of
+many reasons why it's wise to quickly run an internet search to see who you're
+interacting with. By doing this you also get aware if your report was heard by
+the right people, as a reminder to the maintainer (see below) might be in order
+later if discussion fades out without leading to a satisfying solution for the
+issue.
+
+**Inquiries for data**: Often you will be asked to test something or provide
+additional details. Try to provide the requested information soon, as you have
+the attention of someone that might help and risk losing it the longer you
+wait; that outcome is even likely if you do not provide the information within
+a few business days.
+
+**Requests for testing**: When you are asked to test a diagnostic patch or a
+possible fix, try to test it in timely manner, too. But do it properly and make
+sure to not rush it: mixing things up can happen easily and can lead to a lot
+of confusion for everyone involved. A common mistake for example is thinking a
+proposed patch with a fix was applied, but in fact wasn't. Things like that
+happen even to experienced testers occasionally, but they most of the time will
+notice when the kernel with the fix behaves just as one without it.
+
+What to do when nothing of substance happens
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some reports will not get any reaction from the responsible Linux kernel
+developers; or a discussion around the issue evolved, but faded out with
+nothing of substance coming out of it.
+
+In these cases wait two (better: three) weeks before sending a friendly
+reminder: maybe the maintainer was just away from keyboard for a while when
+your report arrived or had something more important to take care of. When
+writing the reminder, kindly ask if anything else from your side is needed to
+get the ball running somehow. If the report got out by mail, do that in the
+first lines of a mail that is a reply to your initial mail (see above) which
+includes a full quote of the original report below: that's on of those few
+situations where such a 'TOFU' (Text Over, Fullquote Under) is the right
+approach, as then all the recipients will have the details at hand immediately
+in the proper order.
+
+After the reminder wait three more weeks for replies. If you still don't get a
+proper reaction, you first should reconsider your approach. Did you maybe try
+to reach out to the wrong people? Was the report maybe offensive or so
+confusing that people decided to completely stay away from it? The best way to
+rule out such factors: show the report to one or two people familiar with FLOSS
+issue reporting and ask for their opinion. Also ask them for their advice how
+to move forward. That might mean: prepare a better report and make those people
+review it before you send it out. Such an approach is totally fine; just
+mention that this is the second and improved report on the issue and include a
+link to the first report.
+
+If the report was proper you can send a second reminder; in it ask for advice
+why the report did not get any replies. A good moment for this second reminder
+mail is shortly after the first pre-release (the 'rc1') of a new Linux kernel
+version got published, as you should retest and provide a status update at that
+point anyway (see above).
+
+If the second reminder again results in no reaction within a week, try to
+contact a higher-level maintainer asking for advice: even busy maintainers by
+then should at least have sent some kind of acknowledgment.
+
+Remember to prepare yourself for a disappointment: maintainers ideally should
+react somehow to every issue report, but they are only obliged to fix those
+'issues of high priority' outlined earlier. So don't be too devastating if you
+get a reply along the lines of 'thanks for the report, I have more important
+issues to deal with currently and won't have time to look into this for the
+foreseeable future'.
+
+It's also possible that after some discussion in the bug tracker or on a list
+nothing happens anymore and reminders don't help to motivate anyone to work out
+a fix. Such situations can be devastating, but is within the cards when it
+comes to Linux kernel development. This and several other reasons for not
+getting help are explained in 'Why some issues won't get any reaction or remain
+unfixed after being reported' near the end of this document.
+
+Don't get devastated if you don't find any help or if the issue in the end does
+not get solved: the Linux kernel is FLOSS and thus you can still help yourself.
+You for example could try to find others that are affected and team up with
+them to get the issue resolved. Such a team could prepare a fresh report
+together that mentions how many you are and why this is something that in your
+option should get fixed. Maybe together you can also narrow down the root cause
+or the change that introduced a regression, which often makes developing a fix
+easier. And with a bit of luck there might be someone in the team that knows a
+bit about programming and might be able to write a fix.
+
+
+Reference for "Reporting regressions within a stable and longterm kernel line"
+------------------------------------------------------------------------------
+
+This subsection provides details for the steps you need to perform if you face
+a regression within a stable and longterm kernel line.
+
+Make sure the particular version line still gets support
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    *Check if the kernel developers still maintain the Linux kernel version
+    line you care about: go to the front page of kernel.org and make sure it
+    mentions the latest release of the particular version line without an
+    '[EOL]' tag.*
+
+Most kernel version lines only get supported for about three months, as
+maintaining them longer is quite a lot of work. Hence, only one per year is
+chosen and gets supported for at least two years (often six). That's why you
+need to check if the kernel developers still support the version line you care
+for.
+
+Note, if kernel.org lists two stable version lines on the front page, you
+should consider switching to the newer one and forget about the older one:
+support for it is likely to be abandoned soon. Then it will get a "end-of-life"
+(EOL) stamp. Version lines that reached that point still get mentioned on the
+kernel.org front page for a week or two, but are unsuitable for testing and
+reporting.
+
+Search stable mailing list
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    *Check the archives of the Linux stable mailing list for existing reports.*
+
+Maybe the issue you face is already known and was fixed or is about to. Hence,
+`search the archives of the Linux stable mailing list
+<https://lore.kernel.org/stable/>`_ for reports about an issue like yours. If
+you find any matches, consider joining the discussion, unless the fix is
+already finished and scheduled to get applied soon.
+
+Reproduce issue with the newest release
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    *Install the latest release from the particular version line as a vanilla
+    kernel. Ensure this kernel is not tainted and still shows the problem, as
+    the issue might have already been fixed there. If you first noticed the
+    problem with a vendor kernel, check a vanilla build of the last version
+    known to work performs fine as well.*
+
+Before investing any more time in this process you want to check if the issue
+was already fixed in the latest release of version line you're interested in.
+This kernel needs to be vanilla and shouldn't be tainted before the issue
+happens, as detailed outlined already above in the section "Install a fresh
+kernel for testing".
+
+Did you first notice the regression with a vendor kernel? Then changes the
+vendor applied might be interfering. You need to rule that out by performing
+a recheck. Say something broke when you updated from 5.10.4-vendor.42 to
+5.10.5-vendor.43. Then after testing the latest 5.10 release as outlined in
+the previous paragraph check if a vanilla build of Linux 5.10.4 works fine as
+well. If things are broken there, the issue does not qualify as upstream
+regression and you need switch back to the main step-by-step guide to report
+the issue.
+
+Report the regression
+~~~~~~~~~~~~~~~~~~~~~
+
+    *Send a short problem report to the Linux stable mailing list
+    (stable@vger.kernel.org) and CC the Linux regressions mailing list
+    (regressions@lists.linux.dev); if you suspect the cause in a particular
+    subsystem, CC its maintainer and its mailing list. Roughly describe the
+    issue and ideally explain how to reproduce it. Mention the first version
+    that shows the problem and the last version that's working fine. Then
+    wait for further instructions.*
+
+When reporting a regression that happens within a stable or longterm kernel
+line (say when updating from 5.10.4 to 5.10.5) a brief report is enough for
+the start to get the issue reported quickly. Hence a rough description to the
+stable and regressions mailing list is all it takes; but in case you suspect
+the cause in a particular subsystem, CC its maintainers and its mailing list
+as well, because that will speed things up.
+
+And note, it helps developers a great deal if you can specify the exact version
+that introduced the problem. Hence if possible within a reasonable time frame,
+try to find that version using vanilla kernels. Let's assume something broke when
+your distributor released a update from Linux kernel 5.10.5 to 5.10.8. Then as
+instructed above go and check the latest kernel from that version line, say
+5.10.9. If it shows the problem, try a vanilla 5.10.5 to ensure that no patches
+the distributor applied interfere. If the issue doesn't manifest itself there,
+try 5.10.7 and then (depending on the outcome) 5.10.8 or 5.10.6 to find the
+first version where things broke. Mention it in the report and state that 5.10.9
+is still broken.
+
+What the previous paragraph outlines is basically a rough manual 'bisection'.
+Once your report is out your might get asked to do a proper one, as it allows to
+pinpoint the exact change that causes the issue (which then can easily get
+reverted to fix the issue quickly). Hence consider to do a proper bisection
+right away if time permits. See the section 'Special care for regressions' and
+the document Documentation/admin-guide/bug-bisect.rst for details how to
+perform one. In case of a successful bisection add the author of the culprit to
+the recipients; also CC everyone in the signed-off-by chain, which you find at
+the end of its commit message.
+
+
+Reference for "Reporting issues only occurring in older kernel version lines"
+-----------------------------------------------------------------------------
+
+This section provides details for the steps you need to take if you could not
+reproduce your issue with a mainline kernel, but want to see it fixed in older
+version lines (aka stable and longterm kernels).
+
+Some fixes are too complex
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    *Prepare yourself for the possibility that going through the next few steps
+    might not get the issue solved in older releases: the fix might be too big
+    or risky to get backported there.*
+
+Even small and seemingly obvious code-changes sometimes introduce new and
+totally unexpected problems. The maintainers of the stable and longterm kernels
+are very aware of that and thus only apply changes to these kernels that are
+within rules outlined in Documentation/process/stable-kernel-rules.rst.
+
+Complex or risky changes for example do not qualify and thus only get applied
+to mainline. Other fixes are easy to get backported to the newest stable and
+longterm kernels, but too risky to integrate into older ones. So be aware the
+fix you are hoping for might be one of those that won't be backported to the
+version line your care about. In that case you'll have no other choice then to
+live with the issue or switch to a newer Linux version, unless you want to
+patch the fix into your kernels yourself.
+
+Common preparations
+~~~~~~~~~~~~~~~~~~~
+
+    *Perform the first three steps in the section "Reporting issues only
+    occurring in older kernel version lines" above.*
+
+You need to carry out a few steps already described in another section of this
+guide. Those steps will let you:
+
+ * Check if the kernel developers still maintain the Linux kernel version line
+   you care about.
+
+ * Search the Linux stable mailing list for exiting reports.
+
+ * Check with the latest release.
+
+
+Check code history and search for existing discussions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    *Search the Linux kernel version control system for the change that fixed
+    the issue in mainline, as its commit message might tell you if the fix is
+    scheduled for backporting already. If you don't find anything that way,
+    search the appropriate mailing lists for posts that discuss such an issue
+    or peer-review possible fixes; then check the discussions if the fix was
+    deemed unsuitable for backporting. If backporting was not considered at
+    all, join the newest discussion, asking if it's in the cards.*
+
+In a lot of cases the issue you deal with will have happened with mainline, but
+got fixed there. The commit that fixed it would need to get backported as well
+to get the issue solved. That's why you want to search for it or any
+discussions abound it.
+
+ * First try to find the fix in the Git repository that holds the Linux kernel
+   sources. You can do this with the web interfaces `on kernel.org
+   <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/>`_
+   or its mirror `on GitHub <https://github.com/torvalds/linux>`_; if you have
+   a local clone you alternatively can search on the command line with ``git
+   log --grep=<pattern>``.
+
+   If you find the fix, look if the commit message near the end contains a
+   'stable tag' that looks like this:
+
+          Cc: <stable@vger.kernel.org> # 5.4+
+
+   If that's case the developer marked the fix safe for backporting to version
+   line 5.4 and later. Most of the time it's getting applied there within two
+   weeks, but sometimes it takes a bit longer.
+
+ * If the commit doesn't tell you anything or if you can't find the fix, look
+   again for discussions about the issue. Search the net with your favorite
+   internet search engine as well as the archives for the `Linux kernel
+   developers mailing list <https://lore.kernel.org/lkml/>`_. Also read the
+   section `Locate kernel area that causes the issue` above and follow the
+   instructions to find the subsystem in question: its bug tracker or mailing
+   list archive might have the answer you are looking for.
+
+ * If you see a proposed fix, search for it in the version control system as
+   outlined above, as the commit might tell you if a backport can be expected.
+
+   * Check the discussions for any indicators the fix might be too risky to get
+     backported to the version line you care about. If that's the case you have
+     to live with the issue or switch to the kernel version line where the fix
+     got applied.
+
+   * If the fix doesn't contain a stable tag and backporting was not discussed,
+     join the discussion: mention the version where you face the issue and that
+     you would like to see it fixed, if suitable.
+
+
+Ask for advice
+~~~~~~~~~~~~~~
+
+    *One of the former steps should lead to a solution. If that doesn't work
+    out, ask the maintainers for the subsystem that seems to be causing the
+    issue for advice; CC the mailing list for the particular subsystem as well
+    as the stable mailing list.*
+
+If the previous three steps didn't get you closer to a solution there is only
+one option left: ask for advice. Do that in a mail you sent to the maintainers
+for the subsystem where the issue seems to have its roots; CC the mailing list
+for the subsystem as well as the stable mailing list (stable@vger.kernel.org).
+
+
+Appendix: Why it is somewhat hard to report kernel bugs
+=======================================================
+
+The Linux kernel developers are well aware that reporting bugs to them is harder
+than in other Free/Libre Open Source Projects. Many reasons for that lie in the
+nature of kernels, Linux' development model, and how the world uses the kernel:
+
+* *Most kernels of Linux distributions are totally unsuitable for reporting bugs
+  upstream.* The reference section above already explained this in detail:
+  outdated codebases as well as modifications and add-ons lead to kernel bugs
+  that were fixed upstream a long time ago or never happened there in the first
+  place. Developers of other Open Source software face these problems as well,
+  but the situation is a lot worse when it comes to the kernel, as the changes
+  and their impact are much more severe -- which is why many kernel developers
+  expect reports with kernels built from fresh and nearly unmodified sources.
+
+* *Bugs often only occur in a special environment.* That is because Linux is
+  mostly drivers and can be used in a multitude of ways. Developers often do not
+  have a matching setup at hand -- and therefore frequently must rely on bug
+  reporters for isolating a problems's cause and testing proposed fixes.
+
+* *The kernel has hundreds of maintainers, but all-rounders are very rare.* That
+  again is and effect caused by the multitude of features and drivers, due to
+  which many kernel developers know little about lower or higher layers related
+  to their code and even less about other areas.
+
+* *It is hard finding where to report issues to, among others, due to the lack
+  of a central bug tracker.* This is something even some kernel developers
+  dislike, but that's the situation everyone has to deal with currently.
+
+* *Stable and longterm kernels are primarily maintained by a dedicated 'stable
+  team', which only handles regressions introduced within stable and longterm
+  series.* When someone reports a bug, say, using Linux 6.1.2, the team will,
+  therefore, always ask if mainline is affected: if the bug already happened
+  in 6.1 or occurs with latest mainline (say, 6.2-rc3), they in everybody's
+  interest shove it to the regular developers, as those know the code best.
+
+* *Linux developers are free to focus on latest mainline.* Some, thus, react
+  coldly to reports about bugs in, say, Linux 6.0 when 6.1 is already out;
+  even the latter might not be enough once 6.2-rc1 is out. Some will also not
+  be very welcoming to reports with 6.1.5 or 6.1.6, as the problem might be a
+  series-specific regression the stable team (see above) caused and must fix.
+
+* *Sometimes there is nobody to help.* Sometimes this is due to the lack of
+  hardware documentation -- for example, when a driver was built using reverse
+  engineering or was taken over by spare-time developers when the hardware
+  manufacturer left it behind. Other times there is nobody to even report bugs
+  to: when maintainers move on without a replacement, their code often remains
+  in the kernel as long as it's useful.
+
+Some of these aspects could be improved to facilitate bug reporting -- many
+Linux kernel developers are well aware of this and would be glad if a few
+individuals or an entity would make this their mission.
+
+..
+   end-of-content
+..
+   This document is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If
+   you spot a typo or small mistake, feel free to let him know directly and
+   he'll fix it. You are free to do the same in a mostly informal way if you
+   want to contribute changes to the text, but for copyright reasons please CC
+   linux-doc@vger.kernel.org and "sign-off" your contribution as
+   Documentation/process/submitting-patches.rst outlines in the section "Sign
+   your work - the Developer's Certificate of Origin".
+..
+   This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top
+   of the file. If you want to distribute this text under CC-BY-4.0 only,
+   please use "The Linux kernel developers" for author attribution and link
+   this as source:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/reporting-issues.rst
+..
+   Note: Only the content of this RST file as found in the Linux kernel sources
+   is available under CC-BY-4.0, as versions of this text that were processed
+   (for example by the kernel's build system) might contain content taken from
+   files which use a more restrictive license.
diff --git a/Documentation/admin-guide/reporting-regressions.rst b/Documentation/admin-guide/reporting-regressions.rst
new file mode 100644
index 000000000..946518355
--- /dev/null
+++ b/Documentation/admin-guide/reporting-regressions.rst
@@ -0,0 +1,451 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+.. [see the bottom of this file for redistribution information]
+
+Reporting regressions
++++++++++++++++++++++
+
+"*We don't cause regressions*" is the first rule of Linux kernel development;
+Linux founder and lead developer Linus Torvalds established it himself and
+ensures it's obeyed.
+
+This document describes what the rule means for users and how the Linux kernel's
+development model ensures to address all reported regressions; aspects relevant
+for kernel developers are left to Documentation/process/handling-regressions.rst.
+
+
+The important bits (aka "TL;DR")
+================================
+
+#. It's a regression if something running fine with one Linux kernel works worse
+   or not at all with a newer version. Note, the newer kernel has to be compiled
+   using a similar configuration; the detailed explanations below describes this
+   and other fine print in more detail.
+
+#. Report your issue as outlined in Documentation/admin-guide/reporting-issues.rst,
+   it already covers all aspects important for regressions and repeated
+   below for convenience. Two of them are important: start your report's subject
+   with "[REGRESSION]" and CC or forward it to `the regression mailing list
+   <https://lore.kernel.org/regressions/>`_ (regressions@lists.linux.dev).
+
+#. Optional, but recommended: when sending or forwarding your report, make the
+   Linux kernel regression tracking bot "regzbot" track the issue by specifying
+   when the regression started like this::
+
+       #regzbot introduced: v5.13..v5.14-rc1
+
+
+All the details on Linux kernel regressions relevant for users
+==============================================================
+
+
+The important basics
+--------------------
+
+
+What is a "regression" and what is the "no regressions" rule?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It's a regression if some application or practical use case running fine with
+one Linux kernel works worse or not at all with a newer version compiled using a
+similar configuration. The "no regressions" rule forbids this to take place; if
+it happens by accident, developers that caused it are expected to quickly fix
+the issue.
+
+It thus is a regression when a WiFi driver from Linux 5.13 works fine, but with
+5.14 doesn't work at all, works significantly slower, or misbehaves somehow.
+It's also a regression if a perfectly working application suddenly shows erratic
+behavior with a newer kernel version; such issues can be caused by changes in
+procfs, sysfs, or one of the many other interfaces Linux provides to userland
+software. But keep in mind, as mentioned earlier: 5.14 in this example needs to
+be built from a configuration similar to the one from 5.13. This can be achieved
+using ``make olddefconfig``, as explained in more detail below.
+
+Note the "practical use case" in the first sentence of this section: developers
+despite the "no regressions" rule are free to change any aspect of the kernel
+and even APIs or ABIs to userland, as long as no existing application or use
+case breaks.
+
+Also be aware the "no regressions" rule covers only interfaces the kernel
+provides to the userland. It thus does not apply to kernel-internal interfaces
+like the module API, which some externally developed drivers use to hook into
+the kernel.
+
+How do I report a regression?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Just report the issue as outlined in
+Documentation/admin-guide/reporting-issues.rst, it already describes the
+important points. The following aspects outlined there are especially relevant
+for regressions:
+
+ * When checking for existing reports to join, also search the `archives of the
+   Linux regressions mailing list <https://lore.kernel.org/regressions/>`_ and
+   `regzbot's web-interface <https://linux-regtracking.leemhuis.info/regzbot/>`_.
+
+ * Start your report's subject with "[REGRESSION]".
+
+ * In your report, clearly mention the last kernel version that worked fine and
+   the first broken one. Ideally try to find the exact change causing the
+   regression using a bisection, as explained below in more detail.
+
+ * Remember to let the Linux regressions mailing list
+   (regressions@lists.linux.dev) know about your report:
+
+   * If you report the regression by mail, CC the regressions list.
+
+   * If you report your regression to some bug tracker, forward the submitted
+     report by mail to the regressions list while CCing the maintainer and the
+     mailing list for the subsystem in question.
+
+   If it's a regression within a stable or longterm series (e.g.
+   v5.15.3..v5.15.5), remember to CC the `Linux stable mailing list
+   <https://lore.kernel.org/stable/>`_ (stable@vger.kernel.org).
+
+  In case you performed a successful bisection, add everyone to the CC the
+  culprit's commit message mentions in lines starting with "Signed-off-by:".
+
+When CCing for forwarding your report to the list, consider directly telling the
+aforementioned Linux kernel regression tracking bot about your report. To do
+that, include a paragraph like this in your mail::
+
+       #regzbot introduced: v5.13..v5.14-rc1
+
+Regzbot will then consider your mail a report for a regression introduced in the
+specified version range. In above case Linux v5.13 still worked fine and Linux
+v5.14-rc1 was the first version where you encountered the issue. If you
+performed a bisection to find the commit that caused the regression, specify the
+culprit's commit-id instead::
+
+       #regzbot introduced: 1f2e3d4c5d
+
+Placing such a "regzbot command" is in your interest, as it will ensure the
+report won't fall through the cracks unnoticed. If you omit this, the Linux
+kernel's regressions tracker will take care of telling regzbot about your
+regression, as long as you send a copy to the regressions mailing lists. But the
+regression tracker is just one human which sometimes has to rest or occasionally
+might even enjoy some time away from computers (as crazy as that might sound).
+Relying on this person thus will result in an unnecessary delay before the
+regressions becomes mentioned `on the list of tracked and unresolved Linux
+kernel regressions <https://linux-regtracking.leemhuis.info/regzbot/>`_ and the
+weekly regression reports sent by regzbot. Such delays can result in Linus
+Torvalds being unaware of important regressions when deciding between "continue
+development or call this finished and release the final?".
+
+Are really all regressions fixed?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Nearly all of them are, as long as the change causing the regression (the
+"culprit commit") is reliably identified. Some regressions can be fixed without
+this, but often it's required.
+
+Who needs to find the root cause of a regression?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Developers of the affected code area should try to locate the culprit on their
+own. But for them that's often impossible to do with reasonable effort, as quite
+a lot of issues only occur in a particular environment outside the developer's
+reach -- for example, a specific hardware platform, firmware, Linux distro,
+system's configuration, or application. That's why in the end it's often up to
+the reporter to locate the culprit commit; sometimes users might even need to
+run additional tests afterwards to pinpoint the exact root cause. Developers
+should offer advice and reasonably help where they can, to make this process
+relatively easy and achievable for typical users.
+
+How can I find the culprit?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Perform a bisection, as roughly outlined in
+Documentation/admin-guide/reporting-issues.rst and described in more detail by
+Documentation/admin-guide/bug-bisect.rst. It might sound like a lot of work, but
+in many cases finds the culprit relatively quickly. If it's hard or
+time-consuming to reliably reproduce the issue, consider teaming up with other
+affected users to narrow down the search range together.
+
+Who can I ask for advice when it comes to regressions?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Send a mail to the regressions mailing list (regressions@lists.linux.dev) while
+CCing the Linux kernel's regression tracker (regressions@leemhuis.info); if the
+issue might better be dealt with in private, feel free to omit the list.
+
+
+Additional details about regressions
+------------------------------------
+
+
+What is the goal of the "no regressions" rule?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Users should feel safe when updating kernel versions and not have to worry
+something might break. This is in the interest of the kernel developers to make
+updating attractive: they don't want users to stay on stable or longterm Linux
+series that are either abandoned or more than one and a half years old. That's
+in everybody's interest, as `those series might have known bugs, security
+issues, or other problematic aspects already fixed in later versions
+<http://www.kroah.com/log/blog/2018/08/24/what-stable-kernel-should-i-use/>`_.
+Additionally, the kernel developers want to make it simple and appealing for
+users to test the latest pre-release or regular release. That's also in
+everybody's interest, as it's a lot easier to track down and fix problems, if
+they are reported shortly after being introduced.
+
+Is the "no regressions" rule really adhered in practice?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It's taken really seriously, as can be seen by many mailing list posts from
+Linux creator and lead developer Linus Torvalds, some of which are quoted in
+Documentation/process/handling-regressions.rst.
+
+Exceptions to this rule are extremely rare; in the past developers almost always
+turned out to be wrong when they assumed a particular situation was warranting
+an exception.
+
+Who ensures the "no regressions" rule is actually followed?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The subsystem maintainers should take care of that, which are watched and
+supported by the tree maintainers -- e.g. Linus Torvalds for mainline and
+Greg Kroah-Hartman et al. for various stable/longterm series.
+
+All of them are helped by people trying to ensure no regression report falls
+through the cracks. One of them is Thorsten Leemhuis, who's currently acting as
+the Linux kernel's "regressions tracker"; to facilitate this work he relies on
+regzbot, the Linux kernel regression tracking bot. That's why you want to bring
+your report on the radar of these people by CCing or forwarding each report to
+the regressions mailing list, ideally with a "regzbot command" in your mail to
+get it tracked immediately.
+
+How quickly are regressions normally fixed?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Developers should fix any reported regression as quickly as possible, to provide
+affected users with a solution in a timely manner and prevent more users from
+running into the issue; nevertheless developers need to take enough time and
+care to ensure regression fixes do not cause additional damage.
+
+The answer thus depends on various factors like the impact of a regression, its
+age, or the Linux series in which it occurs. In the end though, most regressions
+should be fixed within two weeks.
+
+Is it a regression, if the issue can be avoided by updating some software?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Almost always: yes. If a developer tells you otherwise, ask the regression
+tracker for advice as outlined above.
+
+Is it a regression, if a newer kernel works slower or consumes more energy?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Yes, but the difference has to be significant. A five percent slow-down in a
+micro-benchmark thus is unlikely to qualify as regression, unless it also
+influences the results of a broad benchmark by more than one percent. If in
+doubt, ask for advice.
+
+Is it a regression, if an external kernel module breaks when updating Linux?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+No, as the "no regression" rule is about interfaces and services the Linux
+kernel provides to the userland. It thus does not cover building or running
+externally developed kernel modules, as they run in kernel-space and hook into
+the kernel using internal interfaces occasionally changed.
+
+How are regressions handled that are caused by security fixes?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In extremely rare situations security issues can't be fixed without causing
+regressions; those fixes are given way, as they are the lesser evil in the end.
+Luckily this middling almost always can be avoided, as key developers for the
+affected area and often Linus Torvalds himself try very hard to fix security
+issues without causing regressions.
+
+If you nevertheless face such a case, check the mailing list archives if people
+tried their best to avoid the regression. If not, report it; if in doubt, ask
+for advice as outlined above.
+
+What happens if fixing a regression is impossible without causing another?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sadly these things happen, but luckily not very often; if they occur, expert
+developers of the affected code area should look into the issue to find a fix
+that avoids regressions or at least their impact. If you run into such a
+situation, do what was outlined already for regressions caused by security
+fixes: check earlier discussions if people already tried their best and ask for
+advice if in doubt.
+
+A quick note while at it: these situations could be avoided, if people would
+regularly give mainline pre-releases (say v5.15-rc1 or -rc3) from each
+development cycle a test run. This is best explained by imagining a change
+integrated between Linux v5.14 and v5.15-rc1 which causes a regression, but at
+the same time is a hard requirement for some other improvement applied for
+5.15-rc1. All these changes often can simply be reverted and the regression thus
+solved, if someone finds and reports it before 5.15 is released. A few days or
+weeks later this solution can become impossible, as some software might have
+started to rely on aspects introduced by one of the follow-up changes: reverting
+all changes would then cause a regression for users of said software and thus is
+out of the question.
+
+Is it a regression, if some feature I relied on was removed months ago?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It is, but often it's hard to fix such regressions due to the aspects outlined
+in the previous section. It hence needs to be dealt with on a case-by-case
+basis. This is another reason why it's in everybody's interest to regularly test
+mainline pre-releases.
+
+Does the "no regression" rule apply if I seem to be the only affected person?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It does, but only for practical usage: the Linux developers want to be free to
+remove support for hardware only to be found in attics and museums anymore.
+
+Note, sometimes regressions can't be avoided to make progress -- and the latter
+is needed to prevent Linux from stagnation. Hence, if only very few users seem
+to be affected by a regression, it for the greater good might be in their and
+everyone else's interest to lettings things pass. Especially if there is an
+easy way to circumvent the regression somehow, for example by updating some
+software or using a kernel parameter created just for this purpose.
+
+Does the regression rule apply for code in the staging tree as well?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Not according to the `help text for the configuration option covering all
+staging code <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/staging/Kconfig>`_,
+which since its early days states::
+
+       Please note that these drivers are under heavy development, may or
+       may not work, and may contain userspace interfaces that most likely
+       will be changed in the near future.
+
+The staging developers nevertheless often adhere to the "no regressions" rule,
+but sometimes bend it to make progress. That's for example why some users had to
+deal with (often negligible) regressions when a WiFi driver from the staging
+tree was replaced by a totally different one written from scratch.
+
+Why do later versions have to be "compiled with a similar configuration"?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Because the Linux kernel developers sometimes integrate changes known to cause
+regressions, but make them optional and disable them in the kernel's default
+configuration. This trick allows progress, as the "no regressions" rule
+otherwise would lead to stagnation.
+
+Consider for example a new security feature blocking access to some kernel
+interfaces often abused by malware, which at the same time are required to run a
+few rarely used applications. The outlined approach makes both camps happy:
+people using these applications can leave the new security feature off, while
+everyone else can enable it without running into trouble.
+
+How to create a configuration similar to the one of an older kernel?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Start your machine with a known-good kernel and configure the newer Linux
+version with ``make olddefconfig``. This makes the kernel's build scripts pick
+up the configuration file (the ".config" file) from the running kernel as base
+for the new one you are about to compile; afterwards they set all new
+configuration options to their default value, which should disable new features
+that might cause regressions.
+
+Can I report a regression I found with pre-compiled vanilla kernels?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You need to ensure the newer kernel was compiled with a similar configuration
+file as the older one (see above), as those that built them might have enabled
+some known-to-be incompatible feature for the newer kernel. If in doubt, report
+the matter to the kernel's provider and ask for advice.
+
+
+More about regression tracking with "regzbot"
+---------------------------------------------
+
+What is regression tracking and why should I care about it?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Rules like "no regressions" need someone to ensure they are followed, otherwise
+they are broken either accidentally or on purpose. History has shown this to be
+true for Linux kernel development as well. That's why Thorsten Leemhuis, the
+Linux Kernel's regression tracker, and some people try to ensure all regression
+are fixed by keeping an eye on them until they are resolved. Neither of them are
+paid for this, that's why the work is done on a best effort basis.
+
+Why and how are Linux kernel regressions tracked using a bot?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Tracking regressions completely manually has proven to be quite hard due to the
+distributed and loosely structured nature of Linux kernel development process.
+That's why the Linux kernel's regression tracker developed regzbot to facilitate
+the work, with the long term goal to automate regression tracking as much as
+possible for everyone involved.
+
+Regzbot works by watching for replies to reports of tracked regressions.
+Additionally, it's looking out for posted or committed patches referencing such
+reports with "Link:" tags; replies to such patch postings are tracked as well.
+Combined this data provides good insights into the current state of the fixing
+process.
+
+How to see which regressions regzbot tracks currently?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Check out `regzbot's web-interface <https://linux-regtracking.leemhuis.info/regzbot/>`_.
+
+What kind of issues are supposed to be tracked by regzbot?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The bot is meant to track regressions, hence please don't involve regzbot for
+regular issues. But it's okay for the Linux kernel's regression tracker if you
+involve regzbot to track severe issues, like reports about hangs, corrupted
+data, or internal errors (Panic, Oops, BUG(), warning, ...).
+
+How to change aspects of a tracked regression?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By using a 'regzbot command' in a direct or indirect reply to the mail with the
+report. The easiest way to do that: find the report in your "Sent" folder or the
+mailing list archive and reply to it using your mailer's "Reply-all" function.
+In that mail, use one of the following commands in a stand-alone paragraph (IOW:
+use blank lines to separate one or multiple of these commands from the rest of
+the mail's text).
+
+ * Update when the regression started to happen, for example after performing a
+   bisection::
+
+       #regzbot introduced: 1f2e3d4c5d
+
+ * Set or update the title::
+
+       #regzbot title: foo
+
+ * Monitor a discussion or bugzilla.kernel.org ticket where additions aspects of
+   the issue or a fix are discussed:::
+
+       #regzbot monitor: https://lore.kernel.org/r/30th.anniversary.repost@klaava.Helsinki.FI/
+       #regzbot monitor: https://bugzilla.kernel.org/show_bug.cgi?id=123456789
+
+ * Point to a place with further details of interest, like a mailing list post
+   or a ticket in a bug tracker that are slightly related, but about a different
+   topic::
+
+       #regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=123456789
+
+ * Mark a regression as invalid::
+
+       #regzbot invalid: wasn't a regression, problem has always existed
+
+Regzbot supports a few other commands primarily used by developers or people
+tracking regressions. They and more details about the aforementioned regzbot
+commands can be found in the `getting started guide
+<https://gitlab.com/knurd42/regzbot/-/blob/main/docs/getting_started.md>`_ and
+the `reference documentation <https://gitlab.com/knurd42/regzbot/-/blob/main/docs/reference.md>`_
+for regzbot.
+
+..
+   end-of-content
+..
+   This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top
+   of the file. If you want to distribute this text under CC-BY-4.0 only,
+   please use "The Linux kernel developers" for author attribution and link
+   this as source:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/reporting-regressions.rst
+..
+   Note: Only the content of this RST file as found in the Linux kernel sources
+   is available under CC-BY-4.0, as versions of this text that were processed
+   (for example by the kernel's build system) might contain content taken from
+   files which use a more restrictive license.
diff --git a/Documentation/admin-guide/rtc.rst b/Documentation/admin-guide/rtc.rst
new file mode 100644
index 000000000..688c95b11
--- /dev/null
+++ b/Documentation/admin-guide/rtc.rst
@@ -0,0 +1,140 @@
+=======================================
+Real Time Clock (RTC) Drivers for Linux
+=======================================
+
+When Linux developers talk about a "Real Time Clock", they usually mean
+something that tracks wall clock time and is battery backed so that it
+works even with system power off.  Such clocks will normally not track
+the local time zone or daylight savings time -- unless they dual boot
+with MS-Windows -- but will instead be set to Coordinated Universal Time
+(UTC, formerly "Greenwich Mean Time").
+
+The newest non-PC hardware tends to just count seconds, like the time(2)
+system call reports, but RTCs also very commonly represent time using
+the Gregorian calendar and 24 hour time, as reported by gmtime(3).
+
+Linux has two largely-compatible userspace RTC API families you may
+need to know about:
+
+    *	/dev/rtc ... is the RTC provided by PC compatible systems,
+	so it's not very portable to non-x86 systems.
+
+    *	/dev/rtc0, /dev/rtc1 ... are part of a framework that's
+	supported by a wide variety of RTC chips on all systems.
+
+Programmers need to understand that the PC/AT functionality is not
+always available, and some systems can do much more.  That is, the
+RTCs use the same API to make requests in both RTC frameworks (using
+different filenames of course), but the hardware may not offer the
+same functionality.  For example, not every RTC is hooked up to an
+IRQ, so they can't all issue alarms; and where standard PC RTCs can
+only issue an alarm up to 24 hours in the future, other hardware may
+be able to schedule one any time in the upcoming century.
+
+
+Old PC/AT-Compatible driver:  /dev/rtc
+--------------------------------------
+
+All PCs (even Alpha machines) have a Real Time Clock built into them.
+Usually they are built into the chipset of the computer, but some may
+actually have a Motorola MC146818 (or clone) on the board. This is the
+clock that keeps the date and time while your computer is turned off.
+
+ACPI has standardized that MC146818 functionality, and extended it in
+a few ways (enabling longer alarm periods, and wake-from-hibernate).
+That functionality is NOT exposed in the old driver.
+
+However it can also be used to generate signals from a slow 2Hz to a
+relatively fast 8192Hz, in increments of powers of two. These signals
+are reported by interrupt number 8. (Oh! So *that* is what IRQ 8 is
+for...) It can also function as a 24hr alarm, raising IRQ 8 when the
+alarm goes off. The alarm can also be programmed to only check any
+subset of the three programmable values, meaning that it could be set to
+ring on the 30th second of the 30th minute of every hour, for example.
+The clock can also be set to generate an interrupt upon every clock
+update, thus generating a 1Hz signal.
+
+The interrupts are reported via /dev/rtc (major 10, minor 135, read only
+character device) in the form of an unsigned long. The low byte contains
+the type of interrupt (update-done, alarm-rang, or periodic) that was
+raised, and the remaining bytes contain the number of interrupts since
+the last read.  Status information is reported through the pseudo-file
+/proc/driver/rtc if the /proc filesystem was enabled.  The driver has
+built in locking so that only one process is allowed to have the /dev/rtc
+interface open at a time.
+
+A user process can monitor these interrupts by doing a read(2) or a
+select(2) on /dev/rtc -- either will block/stop the user process until
+the next interrupt is received. This is useful for things like
+reasonably high frequency data acquisition where one doesn't want to
+burn up 100% CPU by polling gettimeofday etc. etc.
+
+At high frequencies, or under high loads, the user process should check
+the number of interrupts received since the last read to determine if
+there has been any interrupt "pileup" so to speak. Just for reference, a
+typical 486-33 running a tight read loop on /dev/rtc will start to suffer
+occasional interrupt pileup (i.e. > 1 IRQ event since last read) for
+frequencies above 1024Hz. So you really should check the high bytes
+of the value you read, especially at frequencies above that of the
+normal timer interrupt, which is 100Hz.
+
+Programming and/or enabling interrupt frequencies greater than 64Hz is
+only allowed by root. This is perhaps a bit conservative, but we don't want
+an evil user generating lots of IRQs on a slow 386sx-16, where it might have
+a negative impact on performance. This 64Hz limit can be changed by writing
+a different value to /proc/sys/dev/rtc/max-user-freq. Note that the
+interrupt handler is only a few lines of code to minimize any possibility
+of this effect.
+
+Also, if the kernel time is synchronized with an external source, the 
+kernel will write the time back to the CMOS clock every 11 minutes. In 
+the process of doing this, the kernel briefly turns off RTC periodic 
+interrupts, so be aware of this if you are doing serious work. If you
+don't synchronize the kernel time with an external source (via ntp or
+whatever) then the kernel will keep its hands off the RTC, allowing you
+exclusive access to the device for your applications.
+
+The alarm and/or interrupt frequency are programmed into the RTC via
+various ioctl(2) calls as listed in ./include/linux/rtc.h
+Rather than write 50 pages describing the ioctl() and so on, it is
+perhaps more useful to include a small test program that demonstrates
+how to use them, and demonstrates the features of the driver. This is
+probably a lot more useful to people interested in writing applications
+that will be using this driver.  See the code at the end of this document.
+
+(The original /dev/rtc driver was written by Paul Gortmaker.)
+
+
+New portable "RTC Class" drivers:  /dev/rtcN
+--------------------------------------------
+
+Because Linux supports many non-ACPI and non-PC platforms, some of which
+have more than one RTC style clock, it needed a more portable solution
+than expecting a single battery-backed MC146818 clone on every system.
+Accordingly, a new "RTC Class" framework has been defined.  It offers
+three different userspace interfaces:
+
+    *	/dev/rtcN ... much the same as the older /dev/rtc interface
+
+    *	/sys/class/rtc/rtcN ... sysfs attributes support readonly
+	access to some RTC attributes.
+
+    *	/proc/driver/rtc ... the system clock RTC may expose itself
+	using a procfs interface. If there is no RTC for the system clock,
+	rtc0 is used by default. More information is (currently) shown
+	here than through sysfs.
+
+The RTC Class framework supports a wide variety of RTCs, ranging from those
+integrated into embeddable system-on-chip (SOC) processors to discrete chips
+using I2C, SPI, or some other bus to communicate with the host CPU.  There's
+even support for PC-style RTCs ... including the features exposed on newer PCs
+through ACPI.
+
+The new framework also removes the "one RTC per system" restriction.  For
+example, maybe the low-power battery-backed RTC is a discrete I2C chip, but
+a high functionality RTC is integrated into the SOC.  That system might read
+the system clock from the discrete RTC, but use the integrated one for all
+other tasks, because of its greater functionality.
+
+Check out tools/testing/selftests/rtc/rtctest.c for an example usage of the
+ioctl interface.
diff --git a/Documentation/admin-guide/serial-console.rst b/Documentation/admin-guide/serial-console.rst
new file mode 100644
index 000000000..1609e7479
--- /dev/null
+++ b/Documentation/admin-guide/serial-console.rst
@@ -0,0 +1,147 @@
+.. _serial_console:
+
+Linux Serial Console
+====================
+
+To use a serial port as console you need to compile the support into your
+kernel - by default it is not compiled in. For PC style serial ports
+it's the config option next to menu option:
+
+:menuselection:`Character devices --> Serial drivers --> 8250/16550 and compatible serial support --> Console on 8250/16550 and compatible serial port`
+
+You must compile serial support into the kernel and not as a module.
+
+It is possible to specify multiple devices for console output. You can
+define a new kernel command line option to select which device(s) to
+use for console output.
+
+The format of this option is::
+
+	console=device,options
+
+	device:		tty0 for the foreground virtual console
+			ttyX for any other virtual console
+			ttySx for a serial port
+			lp0 for the first parallel port
+			ttyUSB0 for the first USB serial device
+
+	options:	depend on the driver. For the serial port this
+			defines the baudrate/parity/bits/flow control of
+			the port, in the format BBBBPNF, where BBBB is the
+			speed, P is parity (n/o/e), N is number of bits,
+			and F is flow control ('r' for RTS). Default is
+			9600n8. The maximum baudrate is 115200.
+
+You can specify multiple console= options on the kernel command line.
+
+The behavior is well defined when each device type is mentioned only once.
+In this case, the output will appear on all requested consoles. And
+the last device will be used when you open ``/dev/console``.
+So, for example::
+
+	console=ttyS1,9600 console=tty0
+
+defines that opening ``/dev/console`` will get you the current foreground
+virtual console, and kernel messages will appear on both the VGA
+console and the 2nd serial port (ttyS1 or COM2) at 9600 baud.
+
+The behavior is more complicated when the same device type is defined more
+times. In this case, there are the following two rules:
+
+1. The output will appear only on the first device of each defined type.
+
+2. ``/dev/console`` will be associated with the first registered device.
+   Where the registration order depends on how kernel initializes various
+   subsystems.
+
+   This rule is used also when the last console= parameter is not used
+   for other reasons. For example, because of a typo or because
+   the hardware is not available.
+
+The result might be surprising. For example, the following two command
+lines have the same result::
+
+	console=ttyS1,9600 console=tty0 console=tty1
+	console=tty0 console=ttyS1,9600 console=tty1
+
+The kernel messages are printed only on ``tty0`` and ``ttyS1``. And
+``/dev/console`` gets associated with ``tty0``. It is because kernel
+tries to register graphical consoles before serial ones. It does it
+because of the default behavior when no console device is specified,
+see below.
+
+Note that the last ``console=tty1`` parameter still makes a difference.
+The kernel command line is used also by systemd. It would use the last
+defined ``tty1`` as the login console.
+
+If no console device is specified, the first device found capable of
+acting as a system console will be used. At this time, the system
+first looks for a VGA card and then for a serial port. So if you don't
+have a VGA card in your system the first serial port will automatically
+become the console, unless the kernel is configured with the
+CONFIG_NULL_TTY_DEFAULT_CONSOLE option, then it will default to using the
+ttynull device.
+
+You will need to create a new device to use ``/dev/console``. The official
+``/dev/console`` is now character device 5,1.
+
+(You can also use a network device as a console.  See
+``Documentation/networking/netconsole.rst`` for information on that.)
+
+Here's an example that will use ``/dev/ttyS1`` (COM2) as the console.
+Replace the sample values as needed.
+
+1. Create ``/dev/console`` (real console) and ``/dev/tty0`` (master virtual
+   console)::
+
+     cd /dev
+     rm -f console tty0
+     mknod -m 622 console c 5 1
+     mknod -m 622 tty0 c 4 0
+
+2. LILO can also take input from a serial device. This is a very
+   useful option. To tell LILO to use the serial port:
+   In lilo.conf (global section)::
+
+     serial  = 1,9600n8 (ttyS1, 9600 bd, no parity, 8 bits)
+
+3. Adjust to kernel flags for the new kernel,
+   again in lilo.conf (kernel section)::
+
+     append = "console=ttyS1,9600"
+
+4. Make sure a getty runs on the serial port so that you can login to
+   it once the system is done booting. This is done by adding a line
+   like this to ``/etc/inittab`` (exact syntax depends on your getty)::
+
+     S1:23:respawn:/sbin/getty -L ttyS1 9600 vt100
+
+5. Init and ``/etc/ioctl.save``
+
+   Sysvinit remembers its stty settings in a file in ``/etc``, called
+   ``/etc/ioctl.save``. REMOVE THIS FILE before using the serial
+   console for the first time, because otherwise init will probably
+   set the baudrate to 38400 (baudrate of the virtual console).
+
+6. ``/dev/console`` and X
+   Programs that want to do something with the virtual console usually
+   open ``/dev/console``. If you have created the new ``/dev/console`` device,
+   and your console is NOT the virtual console some programs will fail.
+   Those are programs that want to access the VT interface, and use
+   ``/dev/console instead of /dev/tty0``. Some of those programs are::
+
+     Xfree86, svgalib, gpm, SVGATextMode
+
+   It should be fixed in modern versions of these programs though.
+
+   Note that if you boot without a ``console=`` option (or with
+   ``console=/dev/tty0``), ``/dev/console`` is the same as ``/dev/tty0``.
+   In that case everything will still work.
+
+7. Thanks
+
+   Thanks to Geert Uytterhoeven <geert@linux-m68k.org>
+   for porting the patches from 2.1.4x to 2.1.6x for taking care of
+   the integration of these patches into m68k, ppc and alpha.
+
+Miquel van Smoorenburg <miquels@cistron.nl>, 11-Jun-2000
diff --git a/Documentation/admin-guide/spkguide.txt b/Documentation/admin-guide/spkguide.txt
new file mode 100644
index 000000000..0d5965138
--- /dev/null
+++ b/Documentation/admin-guide/spkguide.txt
@@ -0,0 +1,1625 @@
+
+The Speakup User's Guide
+For Speakup 3.1.2 and Later
+By Gene Collins
+Updated by others
+Last modified on Mon Sep 27 14:26:31 2010
+Document version 1.3
+
+Copyright (c) 2005  Gene Collins
+Copyright (c) 2008, 2023  Samuel Thibault
+Copyright (c) 2009, 2010  the Speakup Team
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
+copy of the license is included in the section entitled "GNU Free
+Documentation License".
+
+Preface
+
+The purpose of this document is to familiarize users with the user
+interface to Speakup, a Linux Screen Reader.  If you need instructions
+for installing or obtaining Speakup, visit the web site at
+http://linux-speakup.org/.  Speakup is a set of patches to the standard
+Linux kernel source tree.  It can be built as a series of modules, or as
+a part of a monolithic kernel.  These details are beyond the scope of
+this manual, but the user may need to be aware of the module
+capabilities, depending on how your system administrator has installed
+Speakup.  If Speakup is built as a part of a monolithic kernel, and the
+user is using a hardware synthesizer, then Speakup will be able to
+provide speech access from the time the kernel is loaded, until the time
+the system is shutdown.  This means that if you have obtained Linux
+installation media for a distribution which includes Speakup as a part
+of its kernel, you will be able, as a blind person, to install Linux
+with speech access unaided by a sighted person.  Again, these details
+are beyond the scope of this manual, but the user should be aware of
+them.  See the web site mentioned above for further details.
+
+1.  Starting Speakup
+
+If your system administrator has installed Speakup to work with your
+specific synthesizer by default, then all you need to do to use Speakup
+is to boot your system, and Speakup should come up talking.  This
+assumes of course  that your synthesizer is a supported hardware
+synthesizer, and that it is either installed in or connected to your
+system, and is if necessary powered on.
+
+It is possible, however, that Speakup may have been compiled into the
+kernel with no default synthesizer.  It is even possible that your
+kernel has been compiled with support for some of the supported
+synthesizers and not others.  If you find that this is the case, and
+your synthesizer is supported but not available, complain to the person
+who compiled and installed your kernel.  Or better yet, go to the web
+site, and learn how to patch Speakup into your own kernel source, and
+build and install your own kernel.
+
+If your kernel has been compiled with Speakup, and has no default
+synthesizer set, or you would like to use a different synthesizer than
+the default one, then you may issue the following command at the boot
+prompt of your boot loader.
+
+linux speakup.synth=ltlk
+
+This command would tell Speakup to look for and use a LiteTalk or
+DoubleTalk LT at boot up.  You may replace the ltlk synthesizer keyword
+with the keyword for whatever synthesizer you wish to use.  The
+speakup.synth parameter will accept the following keywords, provided
+that support for the related synthesizers has been built into the
+kernel.
+
+acntsa -- Accent SA
+acntpc -- Accent PC
+apollo -- Apollo
+audptr -- Audapter
+bns -- Braille 'n Speak
+dectlk -- DecTalk Express (old and new, db9 serial only)
+decext -- DecTalk (old) External
+dtlk -- DoubleTalk PC
+keypc -- Keynote Gold PC
+ltlk -- DoubleTalk LT, LiteTalk, or external Tripletalk (db9 serial only)
+spkout -- Speak Out
+txprt -- Transport
+dummy -- Plain text terminal
+
+Note: Speakup does * NOT * support the internal Tripletalk!
+
+Speakup does support two other synthesizers, but because they work in
+conjunction with other software, they must be loaded as modules after
+their related software is loaded, and so are not available at boot up.
+These are as follows:
+
+decpc -- DecTalk PC (not available at boot up)
+soft -- One of several software synthesizers (not available at boot up)
+
+By default speakup looks for the synthesizer on the ttyS0 serial port. This can
+be changed with the device parameter of the modules, for instance for
+DoubleTalk LT:
+
+speakup_ltlk.dev=ttyUSB0
+
+See the sections on loading modules and software synthesizers later in
+this manual for further details.  It should be noted here that the
+speakup.synth boot parameter will have no effect if Speakup has been
+compiled as modules.  In order for Speakup modules to be loaded during
+the boot process, such action must be configured by your system
+administrator.  This will mean that you will hear some, but not all,  of
+the bootup messages.
+
+2.  Basic operation
+
+Once you have booted the system, and if necessary, have supplied the
+proper bootup parameter for your synthesizer, Speakup will begin
+talking as soon as the kernel is loaded.  In fact, it will talk a lot!
+It will speak all the boot up messages that the kernel prints on the
+screen during the boot process.  This is because Speakup is not a
+separate screen reader, but is actually built into the operating
+system.  Since almost all console applications must print text on the
+screen using the kernel, and must get their keyboard input through the
+kernel, they are automatically handled properly by Speakup.  There are a
+few exceptions, but we'll come to those later.
+
+Note:  In this guide I will refer to the numeric keypad as the keypad.
+This is done because the speakupmap.map file referred to later in this
+manual uses the term keypad instead of numeric keypad.  Also I'm lazy
+and would rather only type one word.  So keypad it is.  Got it?  Good.
+
+Most of the Speakup review keys are located on the keypad at the far
+right of the keyboard.  The numlock key should be off, in order for these
+to work.  If you toggle the numlock on, the keypad will produce numbers,
+which is exactly what you want for spreadsheets and such.  For the
+purposes of this guide, you should have the numlock turned off, which is
+its default state at bootup.
+
+You probably won't want to listen to all the bootup messages every time
+you start your system, though it's a good idea to listen to them at
+least once, just so you'll know what kind of information is available to
+you during the boot process.  You can always review these messages after
+bootup with the command:
+
+dmesg | more
+
+In order to speed the boot process, and to silence the speaking of the
+bootup messages, just press the keypad enter key.  This key is located
+in the bottom right corner of the keypad.  Speakup will shut up and stay
+that way, until you press another key.
+
+You can check to see if the boot process has completed by pressing the 8
+key on the keypad, which reads the current line.  This also has the
+effect of starting Speakup talking again, so you can press keypad enter
+to silence it again if the boot process has not completed.
+
+When the boot process is complete, you will arrive at a "login" prompt.
+At this point, you'll need to type in your user id and password, as
+provided by your system administrator.  You will hear Speakup speak the
+letters of your user id as you type it, but not the password.  This is
+because the password is not displayed on the screen for security
+reasons.  This has nothing to do with Speakup, it's a Linux security
+feature.
+
+Once you've logged in, you can run any Linux command or program which is
+allowed by your user id.  Normal users will not be able to run programs
+which require root privileges.
+
+When you are running a program or command, Speakup will automatically
+speak new text as it arrives on the screen.  You can at any time silence
+the speech with keypad enter, or use any of the Speakup review keys.
+
+Here are some basic Speakup review keys, and a short description of what
+they do.
+
+keypad 1 -- read previous character
+keypad 2 -- read current character (pressing keypad 2 twice rapidly will speak
+	the current character phonetically)
+keypad 3 -- read next character
+keypad 4 -- read previous word
+keypad 5 -- read current word (press twice rapidly to spell the current word)
+keypad 6 -- read next word
+keypad 7 -- read previous line
+keypad 8 -- read current line (press twice rapidly to hear how much the
+	text on the current line is indented)
+keypad 9 -- read next line
+keypad period -- speak current cursor position and announce current
+	virtual console
+
+It's also worth noting that the insert key on the keypad is mapped
+as the speakup key.  Instead of pressing and releasing this key, as you
+do under DOS or Windows, you hold it like a shift key, and press other
+keys in combination with it.  For example, repeatedly holding keypad
+insert, from now on called speakup, and keypad enter will toggle the
+speaking of new text on the screen on and off.  This is not the same as
+just pressing keypad enter by itself, which just silences the speech
+until you hit another key.  When you hit speakup plus keypad enter,
+Speakup will say, "You turned me off.", or "Hey, that's better."  When
+Speakup is turned off, no new text on the screen will be spoken.  You
+can still use the reading controls to review the screen however.
+
+3.  Using the Speakup Help System
+
+In order to enter the Speakup help system, press and hold the speakup
+key (remember that this is the keypad insert key), and press the f1 key.
+You will hear the message:
+
+"Press space to leave help, cursor up or down to scroll, or a letter to
+go to commands in list."
+
+When you press the spacebar to leave the help system, you will hear:
+
+"Leaving help."
+
+While you are in the Speakup help system, you can scroll up or down
+through the list of available commands using the cursor keys.  The list
+of commands is arranged in alphabetical order.  If you wish to jump to
+commands in a specific part of the alphabet, you may press the letter of
+the alphabet you wish to jump to.
+
+You can also just explore by typing keyboard keys.  Pressing keys will
+cause Speakup to speak the command associated with that key.  For
+example, if you press the keypad 8 key, you will hear:
+
+"Keypad 8 is line, say current."
+
+You'll notice that some commands do not have keys assigned to them.
+This is because they are very infrequently used commands, and are also
+accessible through the sys system.  We'll discuss the sys system later
+in this manual.
+
+You'll also notice that some commands have two keys assigned to them.
+This is because Speakup has a built in set of alternative key bindings
+for laptop users.  The alternate speakup key is the caps lock key.  You
+can press and hold the caps lock key, while pressing an alternate
+speakup command key to activate the command.  On most laptops, the
+numeric keypad is defined as the keys in the j k l area of the keyboard.
+
+There is usually a function key which turns this keypad function on and
+off, and some other key which controls the numlock state.  Toggling the
+keypad functionality on and off can become a royal pain.  So, Speakup
+gives you a simple way to get at an alternative set of key mappings for
+your laptop.  These are also available by default on desktop systems,
+because Speakup does not know whether it is running on a desktop or
+laptop.  So you may choose which set of Speakup keys to use.  Some
+system administrators may have chosen to compile Speakup for a desktop
+system without this set of alternate key bindings, but these details are
+beyond the scope of this manual.  To use the caps lock for its normal
+purpose, hold the shift key while toggling the caps lock on and off.  We
+should note here, that holding the caps lock key and pressing the z key
+will toggle the alternate j k l keypad on and off.
+
+4.  Keys and Their Assigned Commands
+
+In this section, we'll go through a list of all the speakup keys and
+commands.  You can also get a list of commands and assigned keys from
+the help system.
+
+The following list was taken from the speakupmap.map file.  Key
+assignments are on the left of the equal sign, and the associated
+Speakup commands are on the right.  The designation "spk" means to press
+and hold the speakup key, a.k.a. keypad insert, a.k.a. caps lock, while
+pressing the other specified key.
+
+spk key_f9 = punc_level_dec
+spk key_f10 = punc_level_inc
+spk key_f11 = reading_punc_dec
+spk key_f12 = reading_punc_inc
+spk key_1 = vol_dec
+spk key_2 =  vol_inc
+spk key_3 = pitch_dec
+spk key_4 = pitch_inc
+spk key_5 = rate_dec
+spk key_6 = rate_inc
+key_kpasterisk = toggle_cursoring
+spk key_kpasterisk = speakup_goto
+spk key_f1 = speakup_help
+spk key_f2 = set_win
+spk key_f3 = clear_win
+spk key_f4 = enable_win
+spk key_f5 = edit_some
+spk key_f6 = edit_most
+spk key_f7 = edit_delim
+spk key_f8 = edit_repeat
+shift spk key_f9 = edit_exnum
+ key_kp7 = say_prev_line
+spk key_kp7 = left_edge
+ key_kp8 = say_line
+double  key_kp8 = say_line_indent
+spk key_kp8 = say_from_top
+ key_kp9 = say_next_line
+spk  key_kp9 = top_edge
+ key_kpminus = speakup_parked
+spk key_kpminus = say_char_num
+ key_kp4 = say_prev_word
+spk key_kp4 = say_from_left
+ key_kp5 = say_word
+double key_kp5 = spell_word
+spk key_kp5 = spell_phonetic
+ key_kp6 = say_next_word
+spk key_kp6 = say_to_right
+ key_kpplus = say_screen
+spk key_kpplus = say_win
+ key_kp1 = say_prev_char
+spk key_kp1 = right_edge
+ key_kp2 = say_char
+spk key_kp2 = say_to_bottom
+double key_kp2 = say_phonetic_char
+ key_kp3 = say_next_char
+spk  key_kp3 = bottom_edge
+ key_kp0 = spk_key
+ key_kpdot = say_position
+spk key_kpdot = say_attributes
+key_kpenter = speakup_quiet
+spk key_kpenter = speakup_off
+key_sysrq = speech_kill
+ key_kpslash = speakup_cut
+spk key_kpslash = speakup_paste
+spk key_pageup = say_first_char
+spk key_pagedown = say_last_char
+key_capslock = spk_key
+ spk key_z = spk_lock
+key_leftmeta = spk_key
+ctrl spk key_0 = speakup_goto
+spk key_u = say_prev_line
+spk key_i = say_line
+double spk key_i = say_line_indent
+spk key_o = say_next_line
+spk key_minus = speakup_parked
+shift spk key_minus = say_char_num
+spk key_j = say_prev_word
+spk key_k = say_word
+double spk key_k = spell_word
+spk key_l = say_next_word
+spk key_m = say_prev_char
+spk key_comma = say_char
+double spk key_comma = say_phonetic_char
+spk key_dot = say_next_char
+spk key_n = say_position
+ ctrl spk key_m = left_edge
+ ctrl spk key_y = top_edge
+ ctrl spk key_dot = right_edge
+ctrl spk key_p = bottom_edge
+spk key_apostrophe = say_screen
+spk key_h = say_from_left
+spk key_y = say_from_top
+spk key_semicolon = say_to_right
+spk key_p = say_to_bottom
+spk key_slash = say_attributes
+ spk key_enter = speakup_quiet
+ ctrl  spk key_enter = speakup_off
+ spk key_9 = speakup_cut
+spk key_8 = speakup_paste
+shift spk key_m = say_first_char
+ ctrl spk key_semicolon = say_last_char
+spk key_r = read_all_doc
+
+5.  The Speakup Sys System
+
+The Speakup screen reader also creates a speakup subdirectory as a part
+of the sys system.
+
+As a convenience, run as root
+
+ln -s /sys/accessibility/speakup /speakup
+
+to directly access speakup parameters from /speakup.
+You can see these entries by typing the command:
+
+ls -1 /speakup/*
+
+If you issue the above ls command, you will get back something like
+this:
+
+/speakup/attrib_bleep
+/speakup/bell_pos
+/speakup/bleep_time
+/speakup/bleeps
+/speakup/cursor_time
+/speakup/delimiters
+/speakup/ex_num
+/speakup/key_echo
+/speakup/keymap
+/speakup/no_interrupt
+/speakup/punc_all
+/speakup/punc_level
+/speakup/punc_most
+/speakup/punc_some
+/speakup/reading_punc
+/speakup/repeats
+/speakup/say_control
+/speakup/say_word_ctl
+/speakup/silent
+/speakup/spell_delay
+/speakup/synth
+/speakup/synth_direct
+/speakup/version
+
+/speakup/i18n:
+announcements
+characters
+chartab
+colors
+ctl_keys
+formatted
+function_names
+key_names
+states
+
+/speakup/soft:
+caps_start
+caps_stop
+delay_time
+direct
+freq
+full_time
+jiffy_delta
+pitch
+inflection
+punct
+rate
+tone
+trigger_time
+voice
+vol
+
+Notice the two subdirectories of /speakup: /speakup/i18n and
+/speakup/soft.
+The i18n subdirectory is described in a later section.
+The files under /speakup/soft represent settings that are specific to the
+driver for the software synthesizer.  If you use the LiteTalk, your
+synthesizer-specific settings would be found in /speakup/ltlk.  In other words,
+a subdirectory named /speakup/KWD is created to hold parameters specific
+to the device whose keyword is KWD.
+These parameters include volume, rate, pitch, and others.
+
+In addition to using the Speakup hot keys to change such things as
+volume, pitch, and rate, you can also echo values to the appropriate
+entry in the /speakup directory.  This is very useful, since it
+lets you control Speakup parameters from within a script.  How you
+would write such scripts is somewhat beyond the scope of this manual,
+but I will include a couple of simple examples here to give you a
+general idea of what such scripts can do.
+
+Suppose for example, that you wanted to control both the punctuation
+level and the reading punctuation level at the same time.  For
+simplicity, we'll call them punc0, punc1, punc2, and punc3.  The scripts
+might look something like this:
+
+#!/bin/bash
+# punc0
+# set punc and reading punc levels to 0
+echo 0 >/speakup/punc_level
+echo 0 >/speakup/reading_punc
+echo Punctuation level set to 0.
+
+#!/bin/bash
+# punc1
+# set punc and reading punc levels to 1
+echo 1 >/speakup/punc_level
+echo 1 >/speakup/reading_punc
+echo Punctuation level set to 1.
+
+#!/bin/bash
+# punc2
+# set punc and reading punc levels to 2
+echo 2 >/speakup/punc_level
+echo 2 >/speakup/reading_punc
+echo Punctuation level set to 2.
+
+#!/bin/bash
+# punc3
+# set punc and reading punc levels to 3
+echo 3 >/speakup/punc_level
+echo 3 >/speakup/reading_punc
+echo Punctuation level set to 3.
+
+If you were to store these four small scripts in a directory in your
+path, perhaps /usr/local/bin, and set the permissions to 755 with the
+chmod command, then you could change the default reading punc and
+punctuation levels at the same time by issuing just one command.  For
+example, if you were to execute the punc3 command at your shell prompt,
+then the reading punc and punc level would both get set to 3.
+
+I should note that the above scripts were written to work with bash, but
+regardless of which shell you use, you should be able to do something
+similar.
+
+The Speakup sys system also has another interesting use.  You can echo
+Speakup parameters into the sys system in a script during system
+startup, and speakup will return to your preferred parameters every time
+the system is rebooted.
+
+Most of the Speakup sys parameters can be manipulated by a regular user
+on the system.  However, there are a few parameters that are dangerous
+enough that they should only be manipulated by the root user on your
+system.  There are even some parameters that are read only, and cannot
+be written to at all.  For example, the version entry in the Speakup
+sys system is read only.  This is because there is no reason for a user
+to tamper with the version number which is reported by Speakup.  Doing
+an ls -l on /speakup/version will return this:
+
+-r--r--r--    1 root     root            0 Mar 21 13:46 /speakup/version
+
+As you can see, the version entry in the Speakup sys system is read
+only, is owned by root, and belongs to the root group.  Doing a cat of
+/speakup/version will display the Speakup version number, like
+this:
+
+cat /speakup/version
+Speakup v-2.00 CVS: Thu Oct 21 10:38:21 EDT 2004
+synth dtlk version 1.1
+
+The display shows the Speakup version number, along with the version
+number of the driver for the current synthesizer.
+
+Looking at entries in the Speakup sys system can be useful in many
+ways.  For example, you might wish to know what level your volume is set
+at.  You could type:
+
+cat /speakup/KWD/vol
+# Replace KWD with the keyword for your synthesizer, E.G., ltlk for LiteTalk.
+5
+
+The number five which comes back is the level at which the synthesizer
+volume is set at.
+
+All the entries in the Speakup sys system are readable, some are
+writable by root only, and some are writable by everyone.  Unless you
+know what you are doing, you should probably leave the ones that are
+writable by root only alone.  Most of the names are self explanatory.
+Vol for controlling volume, pitch for pitch, inflection for pitch range, rate
+for controlling speaking rate, etc.  If you find one you aren't sure about, you
+can post a query on the Speakup list.
+
+6.  Changing Synthesizers
+
+It is possible to change to a different synthesizer while speakup is
+running.  In other words, it is not necessary to reboot the system
+in order to use a different synthesizer.  You can simply echo the
+synthesizer keyword to the /speakup/synth sys entry.
+Depending on your situation, you may wish to echo none to the synth
+sys entry, to disable speech while one synthesizer is disconnected and
+a second one is connected in its place.  Then echo the keyword for the
+new synthesizer into the synth sys entry in order to start speech
+with the newly connected synthesizer.  See the list of synthesizer
+keywords in section 1 to find the keyword which matches your synth.
+
+7.  Loading modules
+
+As mentioned earlier, Speakup can either be completely compiled into the
+kernel, with the exception of the help module, or it can be compiled as
+a series of modules.   When compiled as modules, Speakup will only be
+able to speak some of the bootup messages if your system administrator
+has configured the system to load the modules at boot time. The modules
+can  be loaded after the file systems have been checked and mounted, or
+from an initrd.  There is a third possibility.  Speakup can be compiled
+with some components built into the kernel, and others as modules.  As
+we'll see in the next section, this is particularly useful when you are
+working with software synthesizers.
+
+If Speakup is completely compiled as modules, then you must use the
+modprobe command to load Speakup.  You do this by loading the module for
+the synthesizer driver you wish to use.  The driver modules are all
+named speakup_<keyword>, where <keyword> is the keyword for the
+synthesizer you want.  So, in order to load the driver for the DecTalk
+Express, you would type the following command:
+
+modprobe speakup_dectlk
+
+Issuing this command would load the DecTalk Express driver and all other
+related Speakup modules necessary to get Speakup up and running.
+
+To completely unload Speakup, again presuming that it is entirely built
+as modules, you would give the command:
+
+modprobe -r speakup_dectlk
+
+The above command assumes you were running a DecTalk Express.  If you
+were using a different synth, then you would substitute its keyword in
+place of dectlk.
+
+If you have multiple drivers loaded, you need to unload all of them, in
+order to completely unload Speakup.
+For example, if you have loaded both the dectlk and ltlk drivers, use the
+command:
+modprobe -r speakup_dectlk speakup_ltlk
+
+You cannot unload the driver for software synthesizers when a user-space
+daemon is using /dev/softsynth.  First, kill the daemon.  Next, remove
+the driver with the command:
+modprobe -r speakup_soft
+
+Now, suppose we have a situation where the main Speakup component
+is built into the kernel, and some or all of the drivers are built as
+modules.  Since the main part of Speakup is compiled into the kernel, a
+partial Speakup sys system has been created which we can take advantage
+of by simply echoing the synthesizer keyword into the
+/speakup/synth sys entry.  This will cause the kernel to
+automatically load the appropriate driver module, and start Speakup
+talking.  To switch to another synth, just echo a new keyword to the
+synth sys entry.  For example, to load the DoubleTalk LT driver,
+you would type:
+
+echo ltlk >/speakup/synth
+
+You can use the modprobe -r command to unload driver modules, regardless
+of whether the main part of Speakup has been built into the kernel or
+not.
+
+8.  Using Software Synthesizers
+
+Using a software synthesizer requires that some other software be
+installed and running on your system.  For this reason, software
+synthesizers are not available for use at bootup, or during a system
+installation process.
+There are two freely-available solutions for software speech: Espeakup and
+Speech Dispatcher.
+These are described in subsections 8.1 and 8.2, respectively.
+
+During the rest of this section, we assume that speakup_soft is either
+built in to your kernel, or loaded as a module.
+
+If your system does not have udev installed , before you can use a
+software synthesizer, you must have created the /dev/softsynth device.
+If you have not already done so, issue the following commands as root:
+
+cd /dev
+mknod softsynth c 10 26
+
+While we are at it, we might just as well create the /dev/synth device,
+which can be used to let user space programs send information to your
+synthesizer.  To create /dev/synth, change to the /dev directory, and
+issue the following command as root:
+
+mknod synth c 10 25
+
+of both.
+
+8.1. Espeakup
+
+Espeakup is a connector between Speakup and the eSpeak software synthesizer.
+Espeakup may already be available as a package for your distribution
+of Linux.  If it is not packaged, you need to install it manually.
+You can find it in the contrib/ subdirectory of the Speakup sources.
+The filename is espeakup-$VERSION.tar.bz2, where $VERSION
+depends on the current release of Espeakup.  The Speakup 3.1.2 source
+ships with version 0.71 of Espeakup.
+The README file included with the Espeakup sources describes the process
+of manual installation.
+
+Assuming that Espeakup is installed, either by the user or by the distributor,
+follow these steps to use it.
+
+Tell Speakup to use the "soft driver:
+echo soft > /speakup/synth
+
+Finally, start the espeakup program.  There are two ways to do it.
+Both require root privileges.
+
+If Espeakup was installed as a package for your Linux distribution,
+you probably have a distribution-specific script that controls the operation
+of the daemon.  Look for a file named espeakup under /etc/init.d or
+/etc/rc.d.  Execute the following command with root privileges:
+/etc/init.d/espeakup start
+Replace init.d with rc.d, if your distribution uses scripts located under
+/etc/rc.d.
+Your distribution will also have a procedure for starting daemons at
+boot-time, so it is possible to have software speech as soon as user-space
+daemons are started by the bootup scripts.
+These procedures are not described in this document.
+
+If you built Espeakup manually, the "make install" step placed the binary
+under /usr/bin.
+Run the following command as root:
+/usr/bin/espeakup
+Espeakup should start speaking.
+
+8.2. Speech Dispatcher
+
+For this option, you must have a package called
+Speech Dispatcher running on your system, and it must be configured to
+work with one of its supported software synthesizers.
+
+Two open source synthesizers you might use are Flite and Festival.  You
+might also choose to purchase the Software DecTalk from Fonix Sales Inc.
+If you run a google search for Fonix, you'll find their web site.
+
+You can obtain a copy of Speech Dispatcher from free(b)soft at
+http://www.freebsoft.org/.  Follow the installation instructions that
+come with Speech Dispatcher in order to install and configure Speech
+Dispatcher.  You can check out the web site for your Linux distribution
+in order to get a copy of either Flite or Festival.  Your Linux
+distribution may also have a precompiled Speech Dispatcher package.
+
+Once you've installed, configured, and tested Speech Dispatcher with your
+chosen software synthesizer, you still need one more piece of software
+in order to make things work.  You need a package called speechd-up.
+You get it from the free(b)soft web site mentioned above.  After you've
+compiled and installed speechd-up, you are almost ready to begin using
+your software synthesizer.
+
+Now you can begin using your software synthesizer.  In order to do so,
+echo the soft keyword to the synth sys entry like this:
+
+echo soft >/speakup/synth
+
+Next run the speechd_up command like this:
+
+speechd_up &
+
+Your synth should now start talking, and you should be able to adjust
+the pitch, rate, etc.
+
+9.  Using The DecTalk PC Card
+
+The DecTalk PC card is an ISA card that is inserted into one of the ISA
+slots in your computer.  It requires that the DecTalk PC software be
+installed on your computer, and that the software be loaded onto the
+Dectalk PC card before it can be used.
+
+You can get the dec_pc.tgz file from the linux-speakup.org site.  The
+dec_pc.tgz file is in the ~ftp/pub/linux/speakup directory.
+
+After you have downloaded the dec_pc.tgz file, untar it in your home
+directory, and read the Readme file in the newly created dec_pc
+directory.
+
+The easiest way to get the software working is to copy the entire dec_pc
+directory into /user/local/lib.  To do this, su to root in your home
+directory, and issue the command:
+
+cp dec_pc /usr/local/lib
+
+You will need to copy the dtload command from the dec_pc directory to a
+directory in your path.  Either /usr/bin or /usr/local/bin is a good
+choice.
+
+You can now run the dtload command in order to load the DecTalk PC
+software onto the card.  After you have done this, echo the decpc
+keyword to the synth entry in the sys system like this:
+
+echo decpc >/speakup/synth
+
+Your DecTalk PC should start talking, and then you can adjust the pitch,
+rate, volume, voice, etc.  The voice entry in the Speakup sys system
+will accept a number from 0 through 7 for the DecTalk PC synthesizer,
+which will give you access to some of the DecTalk voices.
+
+10.  Using Cursor Tracking
+
+In Speakup version 2.0 and later, cursor tracking is turned on by
+default.  This means that when you are using an editor, Speakup will
+automatically speak characters as you move left and right with the
+cursor keys, and lines as you move up and down with the cursor keys.
+This is the traditional sort of cursor tracking.
+Recent versions of Speakup provide two additional ways to control the
+text that is spoken when the cursor is moved:
+"highlight tracking" and "read window."
+They are described later in this section.
+Sometimes, these modes get in your way, so you can disable cursor tracking
+altogether.
+
+You may select among the various forms of cursor tracking using the keypad
+asterisk key.
+Each time you press this key, a new mode is selected, and Speakup speaks
+the name of the new mode.  The names for the four possible states of cursor
+tracking are: "cursoring on", "highlight tracking", "read window",
+and "cursoring off."  The keypad asterisk key moves through the list of
+modes in a circular fashion.
+
+If highlight tracking is enabled, Speakup tracks highlighted text,
+rather than the cursor itself. When you move the cursor with the arrow keys,
+Speakup speaks the currently highlighted information.
+This is useful when moving through various menus and dialog boxes.
+If cursor tracking isn't helping you while navigating a menu,
+try highlight tracking.
+
+With the "read window" variety of cursor tracking, you can limit the text
+that Speakup speaks by specifying a window of interest on the screen.
+See section 15 for a description of the process of defining windows.
+When you move the cursor via the arrow keys, Speakup only speaks
+the contents of the window.  This is especially helpful when you are hearing
+superfluous speech.  Consider the following example.
+
+Suppose that you are at a shell prompt.  You use bash, and you want to
+explore your command history using the up and down arrow keys.  If you
+have enabled cursor tracking, you will hear two pieces of information.
+Speakup speaks both your shell prompt and the current entry from the
+command history.  You may not want to hear the prompt repeated
+each time you move, so you can silence it by specifying a window.  Find
+the last line of text on the screen.  Clear the current window by pressing
+the key combination speakup f3.  Use the review cursor to find the first
+character that follows your shell prompt.  Press speakup + f2 twice, to
+define a one-line window.  The boundaries of the window are the
+character following the shell prompt and the end of the line.  Now, cycle
+through the cursor tracking modes using keypad asterisk, until Speakup
+says "read window."  Move through your history using your arrow keys.
+You will notice that Speakup no longer speaks the redundant prompt.
+
+Some folks like to turn cursor tracking off while they are using the
+lynx web browser.  You definitely want to turn cursor tracking off when
+you are using the alsamixer application.  Otherwise, you won't be able
+to hear your mixer settings while you are using the arrow keys.
+
+11.  Cut and Paste
+
+One of Speakup's more useful features is the ability to cut and paste
+text on the screen.  This means that you can capture information from a
+program, and paste that captured text into a different place in the
+program, or into an entirely different program, which may even be
+running on a different console.
+
+For example, in this manual, we have made references to several web
+sites.  It would be nice if you could cut and paste these urls into your
+web browser.  Speakup does this quite nicely.  Suppose you wanted to
+past the following url into your browser:
+
+http://linux-speakup.org/
+
+Use the speakup review keys to position the reading cursor on the first
+character of the above url.  When the reading cursor is in position,
+press the keypad slash key once.  Speakup will say, "mark".  Next,
+position the reading cursor on the rightmost character of the above
+url. Press the keypad slash key once again to actually cut the text
+from the screen.  Speakup will say, "cut".  Although we call this
+cutting, Speakup does not actually delete the cut text from the screen.
+It makes a copy of the text in a special buffer for later pasting.
+
+Now that you have the url cut from the screen, you can paste it into
+your browser, or even paste the url on a command line as an argument to
+your browser.
+
+Suppose you want to start lynx and go to the Speakup site.
+
+You can switch to a different console with the alt left and right
+arrows, or you can switch to a specific console by typing alt and a
+function key.  These are not Speakup commands, just standard Linux
+console capabilities.
+
+Once you've changed to an appropriate console, and are at a shell prompt,
+type the word lynx, followed by a space.  Now press and hold the speakup
+key, while you type the keypad slash character.  The url will be pasted
+onto the command line, just as though you had typed it in.  Press the
+enter key to execute the command.
+
+The paste buffer will continue to hold the cut information, until a new
+mark and cut operation is carried out.  This means you can paste the cut
+information as many times as you like before doing another cut
+operation.
+
+You are not limited to cutting and pasting only one line on the screen.
+You can also cut and paste rectangular regions of the screen.  Just
+position the reading cursor at the top left corner of the text to be
+cut, mark it with the keypad slash key, then position the reading cursor
+at the bottom right corner of the region to be cut, and cut it with the
+keypad slash key.
+
+12.  Changing the Pronunciation of Characters
+
+Through the /speakup/i18n/characters sys entry, Speakup gives you the
+ability to change how Speakup pronounces a given character.  You could,
+for example, change how some punctuation characters are spoken.  You can
+even change how Speakup will pronounce certain letters.
+
+You may, for example, wish to change how Speakup pronounces the z
+character.  The author of Speakup, Kirk Reiser, is Canadian, and thus
+believes that the z should be pronounced zed.  If you are an American,
+you might wish to use the zee pronunciation instead of zed.  You can
+change the pronunciation of both the upper and lower case z with the
+following two commands:
+
+echo 90 zee >/speakup/characters
+echo 122 zee >/speakup/characters
+
+Let's examine the parts of the two previous commands.  They are issued
+at the shell prompt, and could be placed in a startup script.
+
+The word echo tells the shell that you want to have it display the
+string of characters that follow the word echo.  If you were to just
+type:
+
+echo hello.
+
+You would get the word hello printed on your screen as soon as you
+pressed the enter key.  In this case, we are echoing strings that we
+want to be redirected into the sys system.
+
+The numbers 90 and 122 in the above echo commands are the ascii numeric
+values for the upper and lower case z, the characters we wish to change.
+
+The string zee is the pronunciation that we want Speakup to use for the
+upper and lower case z.
+
+The > symbol redirects the output of the echo command to a file, just
+like in DOS, or at the Windows command prompt.
+
+And finally, /speakup/i18n/characters is the file entry in the sys system
+where we want the output to be directed.  Speakup looks at the numeric
+value of the character we want to change, and inserts the pronunciation
+string into an internal table.
+
+You can look at the whole table with the following command:
+
+cat /speakup/i18n/characters
+
+Speakup will then print out the entire character pronunciation table.  I
+won't display it here, but leave you to look at it at your convenience.
+
+13.  Mapping Keys
+
+Speakup has the capability of allowing you to assign or "map" keys to
+internal Speakup commands.  This section necessarily assumes you have a
+Linux kernel source tree installed, and that it has been patched and
+configured with Speakup.  How you do this is beyond the scope of this
+manual.  For this information, visit the Speakup web site at
+http://linux-speakup.org/.  The reason you'll need the kernel source
+tree patched with Speakup is that the genmap utility you'll need for
+processing keymaps is in the
+/usr/src/linux-<version_number>/drivers/char/speakup directory.  The
+<version_number> in the above directory path is the version number of
+the Linux source tree you are working with.
+
+So ok, you've gone off and gotten your kernel source tree, and patched
+and configured it.  Now you can start manipulating keymaps.
+
+You can either use the
+/usr/src/linux-<version_number>/drivers/char/speakup/speakupmap.map file
+included with the Speakup source, or you can cut and paste the copy in
+section 4 into a separate file.  If you use the one in the Speakup
+source tree, make sure you make a backup of it before you start making
+changes.  You have been warned!
+
+Suppose that you want to swap the key assignments for the Speakup
+say_last_char and the Speakup say_first_char commands.  The
+speakupmap.map lists the key mappings for these two commands as follows:
+
+spk key_pageup = say_first_char
+spk key_pagedown = say_last_char
+
+You can edit your copy of the speakupmap.map file and swap the command
+names on the right side of the = (equals) sign.  You did make a backup,
+right?  The new keymap lines would look like this:
+
+spk key_pageup = say_last_char
+spk key_pagedown = say_first_char
+
+After you edit your copy of the speakupmap.map file, save it under a new
+file name, perhaps newmap.map.  Then exit your editor and return to the
+shell prompt.
+
+You are now ready to load your keymap with your swapped key assignments.
+ Assuming that you saved your new keymap as the file newmap.map, you
+would load your keymap into the sys system like this:
+
+/usr/src/linux-<version_number>/drivers/char/speakup/genmap newmap.map
+>/speakup/keymap
+
+Remember to substitute your kernel version number for the
+<version_number> in the above command.  Also note that although the
+above command wrapped onto two lines in this document, you should type
+it all on one line.
+
+Your say first and say last characters should now be swapped.  Pressing
+speakup pagedown should read you the first non-whitespace character on
+the line your reading cursor is in, and pressing speakup pageup should
+read you the last character on the line your reading cursor is in.
+
+You should note that these new mappings will only stay in effect until
+you reboot, or until you load another keymap.
+
+One final warning.  If you try to load a partial map, you will quickly
+find that all the mappings you didn't include in your file got deleted
+from the working map.  Be extremely careful, and always make a backup!
+You have been warned!
+
+14.  Internationalizing Speakup
+
+Speakup indicates various conditions to the user by speaking messages.
+For instance, when you move to the left edge of the screen with the
+review keys, Speakup says, "left."
+Prior to version 3.1.0 of Speakup, all of these messages were in English,
+and they could not be changed.  If you used a non-English synthesizer,
+you still heard English messages, such as "left" and "cursoring on."
+In version 3.1.0 or higher, one may load translations for the various
+messages via the /sys filesystem.
+
+The directory /speakup/i18n contains several collections of messages.
+Each group of messages is stored in its own file.
+The following section lists all of these files, along with a brief description
+of each.
+
+14.1.  Files Under the i18n Subdirectory
+
+* announcements:
+This file contains various general announcements, most of which cannot
+be categorized.  You will find messages such as "You killed Speakup",
+"I'm alive", "leaving help", "parked", "unparked", and others.
+You will also find the names of the screen edges and cursor tracking modes
+here.
+
+* characters:
+See section 12 for a description of this file.
+
+* chartab:
+See section 12.  Unlike the rest of the files in the i18n subdirectory,
+this one does not contain messages to be spoken.
+
+* colors:
+When you use the "say attributes" function, Speakup says the name of the
+foreground and background colors.  These names come from the i18n/colors
+file.
+
+* ctl_keys:
+Here, you will find names of control keys.  These are used with Speakup's
+say_control feature.
+
+* formatted:
+This group of messages contains embedded formatting codes, to specify
+the type and width of displayed data.  If you change these, you must
+preserve all of the formatting codes, and they must appear in the order
+used by the default messages.
+
+* function_names:
+Here, you will find a list of names for Speakup functions.  These are used
+by the help system.  For example, suppose that you have activated help mode,
+and you pressed keypad 3.  Speakup says:
+"keypad 3 is character, say next."
+The message "character, say next" names a Speakup function, and it
+comes from this function_names file.
+
+* key_names:
+Again, key_names is used by Speakup's help system.  In the previous
+example, Speakup said that you pressed "keypad 3."
+This name came from the key_names file.
+
+* states:
+This file contains names for key states.
+Again, these are part of the help system.  For instance, if you had pressed
+speakup + keypad 3, you would hear:
+"speakup keypad 3 is go to bottom edge."
+The speakup key is depressed, so the name of the key state is speakup.
+This part of the message comes from the states collection.
+
+14.2.  Changing language
+
+14.2.1. Loading Your Own Messages
+
+The files under the i18n subdirectory all follow the same format.
+They consist of lines, with one message per line.
+Each message is represented by a number, followed by the text of the message.
+The number is the position of the message in the given collection.
+For example, if you view the file /speakup/i18n/colors, you will see the
+following list:
+
+0	black
+1	blue
+2	green
+3	cyan
+4	red
+5	magenta
+6	yellow
+7	white
+8	grey
+
+You can change one message, or you can change a whole group.
+To load a whole collection of messages from a new source, simply use
+the cp command:
+cp ~/my_colors /speakup/i18n/colors
+You can change an individual message with the echo command,
+as shown in the following example.
+
+The Spanish name for the color blue is azul.
+Looking at the colors file, we see that the name "blue" is at position 1
+within the colors group.  Let's change blue to azul:
+echo '1 azul' > /speakup/i18n/colors
+The next time that Speakup says message 1 from the colors group, it will
+say "azul", rather than "blue."
+
+14.2.2. Choose a language
+
+In the future, translations into various languages will be made available,
+and most users will just load the files necessary for their language. So far,
+only French language is available beyond native Canadian English language.
+
+French is only available after you are logged in.
+
+Canadian English is the default language. To toggle another language,
+download the source of Speakup and untar it in your home directory. The
+following command should let you do this:
+
+tar xvjf speakup-<version>.tar.bz2
+
+where <version> is the version number of the application.
+
+Next, change to the newly created directory, then into the tools/ directory, and
+run the script speakup_setlocale. You are asked the language that you want to
+use. Type the number associated to your language (e.g. fr for French) then press
+Enter. Needed files are copied in the i18n directory.
+
+Note: the speakupconf must be installed on your system so that settings are saved.
+Otherwise, you will have an error: your language will be loaded but you will
+have to run the script again every time Speakup restarts.
+See section 16.1. for information about speakupconf.
+
+You will have to repeat these steps for any change of locale, i.e. if you wish
+change the speakup's language or charset (iso-8859-15 ou UTF-8).
+
+If you wish store the settings, note that at your next login, you will need to
+do:
+
+speakup load
+
+Alternatively, you can add the above line to your file
+~/.bashrc or ~/.bash_profile.
+
+If your system administrator himself ran the script, all the users will be able
+to change from English to the language chosen by root and do directly
+speakupconf load (or add this to the ~/.bashrc or
+~/.bash_profile file). If there are several languages to handle, the
+administrator (or every user) will have to run the first steps until speakupconf
+save, choosing the appropriate language, in every user's home directory. Every
+user will then be able to do speakupconf load, Speakup will load his own settings.
+
+14.3.  No Support for Non-Western-European Languages
+
+As of the current release, Speakup only supports Western European languages.
+Support for the extended characters used by languages outside of the Western
+European family of languages is a work in progress.
+
+15.  Using Speakup's Windowing Capability
+
+Speakup has the capability of defining and manipulating windows on the
+screen.  Speakup uses the term "Window", to mean a user defined area of
+the screen.  The key strokes for defining and manipulating Speakup
+windows are as follows:
+
+speakup + f2 -- Set the bounds of the window.
+Speakup + f3 -- clear the current window definition.
+speakup + f4 -- Toggle window silence on and off.
+speakup + keypad plus -- Say the currently defined window.
+
+These capabilities are useful for tracking a certain part of the screen
+without rereading the whole screen, or for silencing a part of the
+screen that is constantly changing, such as a clock or status line.
+
+There is no way to save these window settings, and you can only have one
+window defined for each virtual console.  There is also no way to have
+windows automatically defined for specific applications.
+
+In order to define a window, use the review keys to move your reading
+cursor to the beginning of the area you want to define.  Then press
+speakup + f2.  Speakup will tell you that the window starts at the
+indicated row and column position.  Then move the reading cursor to the
+end of the area to be defined as a window, and press speakup + f2 again.
+ If there is more than one line in the window, Speakup will tell you
+that the window ends at the indicated row and column position.  If there
+is only one line in the window, then Speakup will tell you that the
+window is the specified line on the screen.  If you are only defining a
+one line window, you can just press speakup + f2 twice after placing the
+reading cursor on the line you want to define as a window.  It is not
+necessary to position the reading cursor at the end of the line in order
+to define the whole line as a window.
+
+16.  Tools for Controlling Speakup
+
+The speakup distribution includes extra tools (in the tools directory)
+which were written to make speakup easier to use.  This section will
+briefly describe the use of these tools.
+
+16.1.  Speakupconf
+
+speakupconf began life as a contribution from Steve Holmes, a member of
+the speakup community.  We would like to thank him for his work on the
+early versions of this project.
+
+This script may be installed as part of your linux distribution, but if
+it isn't, the recommended places to put it are /usr/local/bin or
+/usr/bin.  This script can be run by any user, so it does not require
+root privileges.
+
+Speakupconf allows you to save and load your Speakup settings.  It works
+by reading and writing the /sys files described above.
+
+The directory that speakupconf uses to store your settings depends on
+whether it is run from the root account.  If you execute speakupconf as
+root, it uses the directory /etc/speakup.  Otherwise, it uses the directory
+~/.speakup, where ~ is your home directory.
+Anyone who needs to use Speakup from your console can load his own custom
+settings with this script.
+
+speakupconf takes one required argument: load or save.
+Use the command
+speakupconf save
+to save your Speakup settings, and
+speakupconf load
+to load them into Speakup.
+A second argument may be specified to use an alternate directory to
+load or save the speakup parameters.
+
+16.2.  Talkwith
+
+Charles Hallenbeck, another member of the speakup community, wrote the
+initial versions of this script, and we would also like to thank him for
+his work on it.
+
+This script needs root privileges to run, so if it is not installed as
+part of your linux distribution, the recommended places to install it
+are /usr/local/sbin or /usr/sbin.
+
+Talkwith allows you to switch synthesizers on the fly.  It takes a synthesizer
+name as an argument.  For instance,
+talkwith dectlk
+causes Speakup to use the DecTalk Express.  If you wish to switch to a
+software synthesizer, you must also indicate which daemon you wish to
+use.  There are two possible choices:
+spd and espeakup.  spd is an abbreviation for speechd-up.
+If you wish to use espeakup for software synthesis, give the command
+talkwith soft espeakup
+To use speechd-up, type:
+talkwith soft spd
+Any arguments that follow the name of the daemon are passed to the daemon
+when it is invoked.  For instance:
+talkwith espeakup --default-voice=fr
+causes espeakup to use the French voice.
+Note that talkwith must always be executed with root privileges.
+
+Talkwith does not attempt to load your settings after the new
+synthesizer is activated.  You can use speakupconf to load your settings
+if desired.
+
+                GNU Free Documentation License
+                  Version 1.2, November 2002
+
+
+ Copyright (C) 2000,2001,2002  Free Software Foundation, Inc.
+ Everyone is permitted to copy and distribute verbatim copies
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+
+
+0. PREAMBLE
+
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+6. COLLECTIONS OF DOCUMENTS
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+The Free Software Foundation may publish new, revised versions
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diff --git a/Documentation/admin-guide/svga.rst b/Documentation/admin-guide/svga.rst
new file mode 100644
index 000000000..9eb1e0738
--- /dev/null
+++ b/Documentation/admin-guide/svga.rst
@@ -0,0 +1,250 @@
+.. include:: <isonum.txt>
+
+=================================
+Video Mode Selection Support 2.13
+=================================
+
+:Copyright: |copy| 1995--1999 Martin Mares, <mj@ucw.cz>
+
+Intro
+~~~~~
+
+This small document describes the "Video Mode Selection" feature which
+allows the use of various special video modes supported by the video BIOS. Due
+to usage of the BIOS, the selection is limited to boot time (before the
+kernel decompression starts) and works only on 80X86 machines that are
+booted through BIOS firmware (as opposed to through UEFI, kexec, etc.).
+
+.. note::
+
+   Short intro for the impatient: Just use vga=ask for the first time,
+   enter ``scan`` on the video mode prompt, pick the mode you want to use,
+   remember its mode ID (the four-digit hexadecimal number) and then
+   set the vga parameter to this number (converted to decimal first).
+
+The video mode to be used is selected by a kernel parameter which can be
+specified in the kernel Makefile (the SVGA_MODE=... line) or by the "vga=..."
+option of LILO (or some other boot loader you use) or by the "xrandr" utility
+(present in standard Linux utility packages). You can use the following values
+of this parameter::
+
+   NORMAL_VGA - Standard 80x25 mode available on all display adapters.
+
+   EXTENDED_VGA	- Standard 8-pixel font mode: 80x43 on EGA, 80x50 on VGA.
+
+   ASK_VGA - Display a video mode menu upon startup (see below).
+
+   0..35 - Menu item number (when you have used the menu to view the list of
+      modes available on your adapter, you can specify the menu item you want
+      to use). 0..9 correspond to "0".."9", 10..35 to "a".."z". Warning: the
+      mode list displayed may vary as the kernel version changes, because the
+      modes are listed in a "first detected -- first displayed" manner. It's
+      better to use absolute mode numbers instead.
+
+   0x.... - Hexadecimal video mode ID (also displayed on the menu, see below
+      for exact meaning of the ID). Warning: LILO doesn't support
+      hexadecimal numbers -- you have to convert it to decimal manually.
+
+Menu
+~~~~
+
+The ASK_VGA mode causes the kernel to offer a video mode menu upon
+bootup. It displays a "Press <RETURN> to see video modes available, <SPACE>
+to continue or wait 30 secs" message. If you press <RETURN>, you enter the
+menu, if you press <SPACE> or wait 30 seconds, the kernel will boot up in
+the standard 80x25 mode.
+
+The menu looks like::
+
+	Video adapter: <name-of-detected-video-adapter>
+	Mode:    COLSxROWS:
+	0  0F00  80x25
+	1  0F01  80x50
+	2  0F02  80x43
+	3  0F03  80x26
+	....
+	Enter mode number or ``scan``: <flashing-cursor-here>
+
+<name-of-detected-video-adapter> tells what video adapter did Linux detect
+-- it's either a generic adapter name (MDA, CGA, HGC, EGA, VGA, VESA VGA [a VGA
+with VESA-compliant BIOS]) or a chipset name (e.g., Trident). Direct detection
+of chipsets is turned off by default as it's inherently unreliable due to
+absolutely insane PC design.
+
+"0  0F00  80x25" means that the first menu item (the menu items are numbered
+from "0" to "9" and from "a" to "z") is a 80x25 mode with ID=0x0f00 (see the
+next section for a description of mode IDs).
+
+<flashing-cursor-here> encourages you to enter the item number or mode ID
+you wish to set and press <RETURN>. If the computer complains something about
+"Unknown mode ID", it is trying to tell you that it isn't possible to set such
+a mode. It's also possible to press only <RETURN> which leaves the current mode.
+
+The mode list usually contains a few basic modes and some VESA modes.  In
+case your chipset has been detected, some chipset-specific modes are shown as
+well (some of these might be missing or unusable on your machine as different
+BIOSes are often shipped with the same card and the mode numbers depend purely
+on the VGA BIOS).
+
+The modes displayed on the menu are partially sorted: The list starts with
+the standard modes (80x25 and 80x50) followed by "special" modes (80x28 and
+80x43), local modes (if the local modes feature is enabled), VESA modes and
+finally SVGA modes for the auto-detected adapter.
+
+If you are not happy with the mode list offered (e.g., if you think your card
+is able to do more), you can enter "scan" instead of item number / mode ID.  The
+program will try to ask the BIOS for all possible video mode numbers and test
+what happens then. The screen will be probably flashing wildly for some time and
+strange noises will be heard from inside the monitor and so on and then, really
+all consistent video modes supported by your BIOS will appear (plus maybe some
+``ghost modes``). If you are afraid this could damage your monitor, don't use
+this function.
+
+After scanning, the mode ordering is a bit different: the auto-detected SVGA
+modes are not listed at all and the modes revealed by ``scan`` are shown before
+all VESA modes.
+
+Mode IDs
+~~~~~~~~
+
+Because of the complexity of all the video stuff, the video mode IDs
+used here are also a bit complex. A video mode ID is a 16-bit number usually
+expressed in a hexadecimal notation (starting with "0x"). You can set a mode
+by entering its mode directly if you know it even if it isn't shown on the menu.
+
+The ID numbers can be divided to those regions::
+
+   0x0000 to 0x00ff - menu item references. 0x0000 is the first item. Don't use
+	outside the menu as this can change from boot to boot (especially if you
+	have used the ``scan`` feature).
+
+   0x0100 to 0x017f - standard BIOS modes. The ID is a BIOS video mode number
+	(as presented to INT 10, function 00) increased by 0x0100.
+
+   0x0200 to 0x08ff - VESA BIOS modes. The ID is a VESA mode ID increased by
+	0x0100. All VESA modes should be autodetected and shown on the menu.
+
+   0x0900 to 0x09ff - Video7 special modes. Set by calling INT 0x10, AX=0x6f05.
+	(Usually 940=80x43, 941=132x25, 942=132x44, 943=80x60, 944=100x60,
+	945=132x28 for the standard Video7 BIOS)
+
+   0x0f00 to 0x0fff - special modes (they are set by various tricks -- usually
+	by modifying one of the standard modes). Currently available:
+	0x0f00	standard 80x25, don't reset mode if already set (=FFFF)
+	0x0f01	standard with 8-point font: 80x43 on EGA, 80x50 on VGA
+	0x0f02	VGA 80x43 (VGA switched to 350 scanlines with a 8-point font)
+	0x0f03	VGA 80x28 (standard VGA scans, but 14-point font)
+	0x0f04	leave current video mode
+	0x0f05	VGA 80x30 (480 scans, 16-point font)
+	0x0f06	VGA 80x34 (480 scans, 14-point font)
+	0x0f07	VGA 80x60 (480 scans, 8-point font)
+	0x0f08	Graphics hack (see the VIDEO_GFX_HACK paragraph below)
+
+   0x1000 to 0x7fff - modes specified by resolution. The code has a "0xRRCC"
+	form where RR is a number of rows and CC is a number of columns.
+	E.g., 0x1950 corresponds to a 80x25 mode, 0x2b84 to 132x43 etc.
+	This is the only fully portable way to refer to a non-standard mode,
+	but it relies on the mode being found and displayed on the menu
+	(remember that mode scanning is not done automatically).
+
+   0xff00 to 0xffff - aliases for backward compatibility:
+	0xffff	equivalent to 0x0f00 (standard 80x25)
+	0xfffe	equivalent to 0x0f01 (EGA 80x43 or VGA 80x50)
+
+If you add 0x8000 to the mode ID, the program will try to recalculate
+vertical display timing according to mode parameters, which can be used to
+eliminate some annoying bugs of certain VGA BIOSes (usually those used for
+cards with S3 chipsets and old Cirrus Logic BIOSes) -- mainly extra lines at the
+end of the display.
+
+Options
+~~~~~~~
+
+Build options for arch/x86/boot/* are selected by the kernel kconfig
+utility and the kernel .config file.
+
+VIDEO_GFX_HACK - includes special hack for setting of graphics modes
+to be used later by special drivers.
+Allows to set _any_ BIOS mode including graphic ones and forcing specific
+text screen resolution instead of peeking it from BIOS variables. Don't use
+unless you think you know what you're doing. To activate this setup, use
+mode number 0x0f08 (see the Mode IDs section above).
+
+Still doesn't work?
+~~~~~~~~~~~~~~~~~~~
+
+When the mode detection doesn't work (e.g., the mode list is incorrect or
+the machine hangs instead of displaying the menu), try to switch off some of
+the configuration options listed under "Options". If it fails, you can still use
+your kernel with the video mode set directly via the kernel parameter.
+
+In either case, please send me a bug report containing what _exactly_
+happens and how do the configuration switches affect the behaviour of the bug.
+
+If you start Linux from M$-DOS, you might also use some DOS tools for
+video mode setting. In this case, you must specify the 0x0f04 mode ("leave
+current settings") to Linux, because if you don't and you use any non-standard
+mode, Linux will switch to 80x25 automatically.
+
+If you set some extended mode and there's one or more extra lines on the
+bottom of the display containing already scrolled-out text, your VGA BIOS
+contains the most common video BIOS bug called "incorrect vertical display
+end setting". Adding 0x8000 to the mode ID might fix the problem. Unfortunately,
+this must be done manually -- no autodetection mechanisms are available.
+
+History
+~~~~~~~
+
+=============== ================================================================
+1.0 (??-Nov-95)	First version supporting all adapters supported by the old
+		setup.S + Cirrus Logic 54XX. Present in some 1.3.4? kernels
+		and then removed due to instability on some machines.
+2.0 (28-Jan-96)	Rewritten from scratch. Cirrus Logic 64XX support added, almost
+		everything is configurable, the VESA support should be much more
+		stable, explicit mode numbering allowed, "scan" implemented etc.
+2.1 (30-Jan-96) VESA modes moved to 0x200-0x3ff. Mode selection by resolution
+		supported. Few bugs fixed. VESA modes are listed prior to
+		modes supplied by SVGA autodetection as they are more reliable.
+		CLGD autodetect works better. Doesn't depend on 80x25 being
+		active when started. Scanning fixed. 80x43 (any VGA) added.
+		Code cleaned up.
+2.2 (01-Feb-96)	EGA 80x43 fixed. VESA extended to 0x200-0x4ff (non-standard 02XX
+		VESA modes work now). Display end bug workaround supported.
+		Special modes renumbered to allow adding of the "recalculate"
+		flag, 0xffff and 0xfffe became aliases instead of real IDs.
+		Screen contents retained during mode changes.
+2.3 (15-Mar-96)	Changed to work with 1.3.74 kernel.
+2.4 (18-Mar-96)	Added patches by Hans Lermen fixing a memory overwrite problem
+		with some boot loaders. Memory management rewritten to reflect
+		these changes. Unfortunately, screen contents retaining works
+		only with some loaders now.
+		Added a Tseng 132x60 mode.
+2.5 (19-Mar-96)	Fixed a VESA mode scanning bug introduced in 2.4.
+2.6 (25-Mar-96)	Some VESA BIOS errors not reported -- it fixes error reports on
+		several cards with broken VESA code (e.g., ATI VGA).
+2.7 (09-Apr-96)	- Accepted all VESA modes in range 0x100 to 0x7ff, because some
+		  cards use very strange mode numbers.
+		- Added Realtek VGA modes (thanks to Gonzalo Tornaria).
+		- Hardware testing order slightly changed, tests based on ROM
+		  contents done as first.
+		- Added support for special Video7 mode switching functions
+		  (thanks to Tom Vander Aa).
+		- Added 480-scanline modes (especially useful for notebooks,
+		  original version written by hhanemaa@cs.ruu.nl, patched by
+		  Jeff Chua, rewritten by me).
+		- Screen store/restore fixed.
+2.8 (14-Apr-96) - Previous release was not compilable without CONFIG_VIDEO_SVGA.
+		- Better recognition of text modes during mode scan.
+2.9 (12-May-96)	- Ignored VESA modes 0x80 - 0xff (more VESA BIOS bugs!)
+2.10(11-Nov-96) - The whole thing made optional.
+		- Added the CONFIG_VIDEO_400_HACK switch.
+		- Added the CONFIG_VIDEO_GFX_HACK switch.
+		- Code cleanup.
+2.11(03-May-97) - Yet another cleanup, now including also the documentation.
+		- Direct testing of SVGA adapters turned off by default, ``scan``
+		  offered explicitly on the prompt line.
+		- Removed the doc section describing adding of new probing
+		  functions as I try to get rid of _all_ hardware probing here.
+2.12(25-May-98) Added support for VESA frame buffer graphics.
+2.13(14-May-99) Minor documentation fixes.
+=============== ================================================================
diff --git a/Documentation/admin-guide/syscall-user-dispatch.rst b/Documentation/admin-guide/syscall-user-dispatch.rst
new file mode 100644
index 000000000..c1768d9e8
--- /dev/null
+++ b/Documentation/admin-guide/syscall-user-dispatch.rst
@@ -0,0 +1,99 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+Syscall User Dispatch
+=====================
+
+Background
+----------
+
+Compatibility layers like Wine need a way to efficiently emulate system
+calls of only a part of their process - the part that has the
+incompatible code - while being able to execute native syscalls without
+a high performance penalty on the native part of the process.  Seccomp
+falls short on this task, since it has limited support to efficiently
+filter syscalls based on memory regions, and it doesn't support removing
+filters.  Therefore a new mechanism is necessary.
+
+Syscall User Dispatch brings the filtering of the syscall dispatcher
+address back to userspace.  The application is in control of a flip
+switch, indicating the current personality of the process.  A
+multiple-personality application can then flip the switch without
+invoking the kernel, when crossing the compatibility layer API
+boundaries, to enable/disable the syscall redirection and execute
+syscalls directly (disabled) or send them to be emulated in userspace
+through a SIGSYS.
+
+The goal of this design is to provide very quick compatibility layer
+boundary crosses, which is achieved by not executing a syscall to change
+personality every time the compatibility layer executes.  Instead, a
+userspace memory region exposed to the kernel indicates the current
+personality, and the application simply modifies that variable to
+configure the mechanism.
+
+There is a relatively high cost associated with handling signals on most
+architectures, like x86, but at least for Wine, syscalls issued by
+native Windows code are currently not known to be a performance problem,
+since they are quite rare, at least for modern gaming applications.
+
+Since this mechanism is designed to capture syscalls issued by
+non-native applications, it must function on syscalls whose invocation
+ABI is completely unexpected to Linux.  Syscall User Dispatch, therefore
+doesn't rely on any of the syscall ABI to make the filtering.  It uses
+only the syscall dispatcher address and the userspace key.
+
+As the ABI of these intercepted syscalls is unknown to Linux, these
+syscalls are not instrumentable via ptrace or the syscall tracepoints.
+
+Interface
+---------
+
+A thread can setup this mechanism on supported kernels by executing the
+following prctl:
+
+  prctl(PR_SET_SYSCALL_USER_DISPATCH, <op>, <offset>, <length>, [selector])
+
+<op> is either PR_SYS_DISPATCH_EXCLUSIVE_ON/PR_SYS_DISPATCH_INCLUSIVE_ON
+or PR_SYS_DISPATCH_OFF, to enable and disable the mechanism globally for
+that thread.  When PR_SYS_DISPATCH_OFF is used, the other fields must be zero.
+
+For PR_SYS_DISPATCH_EXCLUSIVE_ON [<offset>, <offset>+<length>) delimit
+a memory region interval from which syscalls are always executed directly,
+regardless of the userspace selector.  This provides a fast path for the
+C library, which includes the most common syscall dispatchers in the native
+code applications, and also provides a way for the signal handler to return
+without triggering a nested SIGSYS on (rt\_)sigreturn.  Users of this
+interface should make sure that at least the signal trampoline code is
+included in this region. In addition, for syscalls that implement the
+trampoline code on the vDSO, that trampoline is never intercepted.
+
+For PR_SYS_DISPATCH_INCLUSIVE_ON [<offset>, <offset>+<length>) delimit
+a memory region interval from which syscalls are dispatched based on
+the userspace selector. Syscalls from outside of the range are always
+executed directly.
+
+[selector] is a pointer to a char-sized region in the process memory
+region, that provides a quick way to enable disable syscall redirection
+thread-wide, without the need to invoke the kernel directly.  selector
+can be set to SYSCALL_DISPATCH_FILTER_ALLOW or SYSCALL_DISPATCH_FILTER_BLOCK.
+Any other value should terminate the program with a SIGSYS.
+
+Additionally, a tasks syscall user dispatch configuration can be peeked
+and poked via the PTRACE_(GET|SET)_SYSCALL_USER_DISPATCH_CONFIG ptrace
+requests. This is useful for checkpoint/restart software.
+
+Security Notes
+--------------
+
+Syscall User Dispatch provides functionality for compatibility layers to
+quickly capture system calls issued by a non-native part of the
+application, while not impacting the Linux native regions of the
+process.  It is not a mechanism for sandboxing system calls, and it
+should not be seen as a security mechanism, since it is trivial for a
+malicious application to subvert the mechanism by jumping to an allowed
+dispatcher region prior to executing the syscall, or to discover the
+address and modify the selector value.  If the use case requires any
+kind of security sandboxing, Seccomp should be used instead.
+
+Any fork or exec of the existing process resets the mechanism to
+PR_SYS_DISPATCH_OFF.
diff --git a/Documentation/admin-guide/sysctl/abi.rst b/Documentation/admin-guide/sysctl/abi.rst
new file mode 100644
index 000000000..4e6db0a2a
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/abi.rst
@@ -0,0 +1,34 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+================================
+Documentation for /proc/sys/abi/
+================================
+
+.. See scripts/check-sysctl-docs to keep this up to date:
+.. scripts/check-sysctl-docs -vtable="abi" \
+..         Documentation/admin-guide/sysctl/abi.rst \
+..         $(git grep -l register_sysctl_)
+
+Copyright (c) 2020, Stephen Kitt
+
+For general info, see Documentation/admin-guide/sysctl/index.rst.
+
+------------------------------------------------------------------------------
+
+The files in ``/proc/sys/abi`` can be used to see and modify
+ABI-related settings.
+
+Currently, these files might (depending on your configuration)
+show up in ``/proc/sys/kernel``:
+
+.. contents:: :local:
+
+vsyscall32 (x86)
+================
+
+Determines whether the kernels maps a vDSO page into 32-bit processes;
+can be set to 1 to enable, or 0 to disable. Defaults to enabled if
+``CONFIG_COMPAT_VDSO`` is set, disabled otherwise.
+
+This controls the same setting as the ``vdso32`` kernel boot
+parameter.
diff --git a/Documentation/admin-guide/sysctl/crypto.rst b/Documentation/admin-guide/sysctl/crypto.rst
new file mode 100644
index 000000000..9a1bd5328
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/crypto.rst
@@ -0,0 +1,83 @@
+=================
+/proc/sys/crypto/
+=================
+
+These files show up in ``/proc/sys/crypto/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+.. _af_alg_restrict:
+
+af_alg_restrict
+===============
+
+Controls the level of restriction of AF_ALG.
+
+AF_ALG is a deprecated and rarely-used userspace interface that is a
+frequent source of vulnerabilities. It also unnecessarily exposes a
+large number of kernel implementation details. For more information
+about AF_ALG, see :ref:`Documentation/crypto/userspace-if.rst
+<crypto_userspace_interface>`.
+
+Starting in Linux v7.3, AF_ALG supports only a limited set of
+algorithms by default. This sysctl allows the system administrator to
+remove this restriction when needed for compatibility reasons, or to
+go further and disable AF_ALG entirely. The default value is 1.
+
+===  ==================================================================
+0    AF_ALG is unrestricted.
+
+1    AF_ALG is supported with a limited list of algorithms. The list
+     is designed for compatibility with known users such as iwd and
+     bluez that haven't yet been fixed to use userspace crypto code.
+
+     Specifically, there is an allowlist for unprivileged processes
+     and a somewhat longer allowlist for processes that hold
+     CAP_SYS_ADMIN or CAP_NET_ADMIN in the initial user namespace.
+
+     Attempts to bind() an AF_ALG socket with a disallowed algorithm
+     fail with ENOENT.
+
+2    AF_ALG is completely disabled. Attempts to create an AF_ALG
+     socket fail with EAFNOSUPPORT.
+===  ==================================================================
+
+fips_enabled
+============
+
+Read-only flag that indicates whether FIPS mode is enabled.
+
+- ``0``: FIPS mode is disabled (default).
+- ``1``: FIPS mode is enabled.
+
+This value is set at boot time via the ``fips=1`` kernel command line
+parameter. When enabled, the cryptographic API will restrict the use
+of certain algorithms and perform self-tests to ensure compliance with
+FIPS (Federal Information Processing Standards) requirements, such as
+FIPS 140-2 and the newer FIPS 140-3, depending on the kernel
+configuration and the module in use.
+
+fips_name
+=========
+
+Read-only file that contains the name of the FIPS module currently in use.
+The value is typically configured via the ``CONFIG_CRYPTO_FIPS_NAME``
+kernel configuration option.
+
+fips_version
+============
+
+Read-only file that contains the version string of the FIPS module.
+If ``CONFIG_CRYPTO_FIPS_CUSTOM_VERSION`` is set, it uses the value from
+``CONFIG_CRYPTO_FIPS_VERSION``. Otherwise, it defaults to the kernel
+release version (``UTS_RELEASE``).
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+.. See scripts/check-sysctl-docs to keep this up to date:
+.. scripts/check-sysctl-docs -vtable="crypto" \
+..         $(git grep -l register_sysctl_)
diff --git a/Documentation/admin-guide/sysctl/debug.rst b/Documentation/admin-guide/sysctl/debug.rst
new file mode 100644
index 000000000..506bd5e48
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/debug.rst
@@ -0,0 +1,52 @@
+================
+/proc/sys/debug/
+================
+
+These files show up in ``/proc/sys/debug/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+exception-trace
+===============
+
+This flag controls whether the kernel prints information about unhandled
+signals (like segmentation faults) to the kernel log (``dmesg``).
+
+- ``0``: Unhandled signals are not traced.
+- ``1``: Information about unhandled signals is printed.
+
+The default value is ``1`` on most architectures (like x86, MIPS, RISC-V),
+but it is ``0`` on **arm64**.
+
+The actual information printed and the context provided varies
+significantly depending on the CPU architecture. For example:
+
+- On **x86**, it typically prints the instruction pointer (IP), error
+  code, and address that caused a page fault.
+- On **PowerPC**, it may print the next instruction pointer (NIP),
+  link register (LR), and other relevant registers.
+
+When enabled, this feature is often rate-limited to prevent the kernel
+log from being flooded during a crash loop.
+
+kprobes-optimization
+====================
+
+This flag enables or disables the optimization of Kprobes on certain
+architectures (like x86).
+
+- ``0``: Kprobes optimization is turned off.
+- ``1``: Kprobes optimization is turned on (default).
+
+For more details on Kprobes and its optimization, please refer to
+Documentation/trace/kprobes.rst.
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+.. See scripts/check-sysctl-docs to keep this up to date:
+.. scripts/check-sysctl-docs -vtable="debug" \
+..         $(git grep -l register_sysctl_)
diff --git a/Documentation/admin-guide/sysctl/fs.rst b/Documentation/admin-guide/sysctl/fs.rst
new file mode 100644
index 000000000..9b7f65c3e
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/fs.rst
@@ -0,0 +1,374 @@
+===============================
+Documentation for /proc/sys/fs/
+===============================
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+Copyright (c) 2009,        Shen Feng<shen@cn.fujitsu.com>
+
+For general info and legal blurb, please look in intro.rst.
+
+------------------------------------------------------------------------------
+
+This file contains documentation for the sysctl files and directories
+in ``/proc/sys/fs/``.
+
+The files in this directory can be used to tune and monitor
+miscellaneous and general things in the operation of the Linux
+kernel. Since some of the files *can* be used to screw up your
+system, it is advisable to read both documentation and source
+before actually making adjustments.
+
+1. /proc/sys/fs
+===============
+
+Currently, these files might (depending on your configuration)
+show up in ``/proc/sys/fs``:
+
+.. contents:: :local:
+
+
+aio-nr & aio-max-nr
+-------------------
+
+``aio-nr`` shows the current system-wide number of asynchronous io
+requests.  ``aio-max-nr`` allows you to change the maximum value
+``aio-nr`` can grow to.  If ``aio-nr`` reaches ``aio-nr-max`` then
+``io_setup`` will fail with ``EAGAIN``.  Note that raising
+``aio-max-nr`` does not result in the
+pre-allocation or re-sizing of any kernel data structures.
+
+dentry-negative
+----------------------------
+
+Policy for negative dentries. Set to 1 to always delete the dentry when a
+file is removed, and 0 to disable it. By default, this behavior is disabled.
+
+dentry-state
+------------
+
+This file shows the values in ``struct dentry_stat_t``, as defined in
+``fs/dcache.c``::
+
+  struct dentry_stat_t dentry_stat {
+        long nr_dentry;
+        long nr_unused;
+        long age_limit;         /* age in seconds */
+        long want_pages;        /* pages requested by system */
+        long nr_negative;       /* # of unused negative dentries */
+        long dummy;             /* Reserved for future use */
+  };
+
+Dentries are dynamically allocated and deallocated.
+
+``nr_dentry`` shows the total number of dentries allocated (active
++ unused). ``nr_unused shows`` the number of dentries that are not
+actively used, but are saved in the LRU list for future reuse.
+
+``age_limit`` is the age in seconds after which dcache entries
+can be reclaimed when memory is short and ``want_pages`` is
+nonzero when ``shrink_dcache_pages()`` has been called and the
+dcache isn't pruned yet.
+
+``nr_negative`` shows the number of unused dentries that are also
+negative dentries which do not map to any files. Instead,
+they help speeding up rejection of non-existing files provided
+by the users.
+
+
+file-max & file-nr
+------------------
+
+The value in ``file-max`` denotes the maximum number of file-
+handles that the Linux kernel will allocate. When you get lots
+of error messages about running out of file handles, you might
+want to increase this limit.
+
+Historically,the kernel was able to allocate file handles
+dynamically, but not to free them again. The three values in
+``file-nr`` denote the number of allocated file handles, the number
+of allocated but unused file handles, and the maximum number of
+file handles. Linux 2.6 and later always reports 0 as the number of free
+file handles -- this is not an error, it just means that the
+number of allocated file handles exactly matches the number of
+used file handles.
+
+Attempts to allocate more file descriptors than ``file-max`` are
+reported with ``printk``, look for::
+
+  VFS: file-max limit <number> reached
+
+in the kernel logs.
+
+
+inode-nr & inode-state
+----------------------
+
+As with file handles, the kernel allocates the inode structures
+dynamically, but can't free them yet.
+
+The file ``inode-nr`` contains the first two items from
+``inode-state``, so we'll skip to that file...
+
+``inode-state`` contains three actual numbers and four dummies.
+The actual numbers are, in order of appearance, ``nr_inodes``,
+``nr_free_inodes`` and ``preshrink``.
+
+``nr_inodes`` stands for the number of inodes the system has
+allocated.
+
+``nr_free_inodes`` represents the number of free inodes (?) and
+preshrink is nonzero when the
+system needs to prune the inode list instead of allocating
+more.
+
+
+mount-max
+---------
+
+This denotes the maximum number of mounts that may exist
+in a mount namespace.
+
+
+nr_open
+-------
+
+This denotes the maximum number of file-handles a process can
+allocate. Default value is 1024*1024 (1048576) which should be
+enough for most machines. Actual limit depends on ``RLIMIT_NOFILE``
+resource limit.
+
+
+overflowgid & overflowuid
+-------------------------
+
+Some filesystems only support 16-bit UIDs and GIDs, although in Linux
+UIDs and GIDs are 32 bits. When one of these filesystems is mounted
+with writes enabled, any UID or GID that would exceed 65535 is translated
+to a fixed value before being written to disk.
+
+These sysctls allow you to change the value of the fixed UID and GID.
+The default is 65534.
+
+
+pipe-user-pages-hard
+--------------------
+
+Maximum total number of pages a non-privileged user may allocate for pipes.
+Once this limit is reached, no new pipes may be allocated until usage goes
+below the limit again. When set to 0, no limit is applied, which is the default
+setting.
+
+
+pipe-user-pages-soft
+--------------------
+
+Maximum total number of pages a non-privileged user may allocate for pipes
+before the pipe size gets limited to two pages. Once this limit is reached,
+new pipes will be limited to two pages in size for this user in order to
+limit total memory usage, and trying to increase them using ``fcntl()`` will be
+denied until usage goes below the limit again. The default value allows to
+allocate up to 1024 pipes at their default size. When set to 0, no limit is
+applied.
+
+
+protected_fifos
+---------------
+
+The intent of this protection is to avoid unintentional writes to
+an attacker-controlled FIFO, where a program expected to create a regular
+file.
+
+When set to "0", writing to FIFOs is unrestricted.
+
+When set to "1" don't allow ``O_CREAT`` open on FIFOs that we don't own
+in world writable sticky directories, unless they are owned by the
+owner of the directory.
+
+When set to "2" it also applies to group writable sticky directories.
+
+This protection is based on the restrictions in Openwall.
+
+
+protected_hardlinks
+--------------------
+
+A long-standing class of security issues is the hardlink-based
+time-of-check-time-of-use race, most commonly seen in world-writable
+directories like ``/tmp``. The common method of exploitation of this flaw
+is to cross privilege boundaries when following a given hardlink (i.e. a
+root process follows a hardlink created by another user). Additionally,
+on systems without separated partitions, this stops unauthorized users
+from "pinning" vulnerable setuid/setgid files against being upgraded by
+the administrator, or linking to special files.
+
+When set to "0", hardlink creation behavior is unrestricted.
+
+When set to "1" hardlinks cannot be created by users if they do not
+already own the source file, or do not have read/write access to it.
+
+This protection is based on the restrictions in Openwall and grsecurity.
+
+
+protected_regular
+-----------------
+
+This protection is similar to `protected_fifos`_, but it
+avoids writes to an attacker-controlled regular file, where a program
+expected to create one.
+
+When set to "0", writing to regular files is unrestricted.
+
+When set to "1" don't allow ``O_CREAT`` open on regular files that we
+don't own in world writable sticky directories, unless they are
+owned by the owner of the directory.
+
+When set to "2" it also applies to group writable sticky directories.
+
+
+protected_symlinks
+------------------
+
+A long-standing class of security issues is the symlink-based
+time-of-check-time-of-use race, most commonly seen in world-writable
+directories like ``/tmp``. The common method of exploitation of this flaw
+is to cross privilege boundaries when following a given symlink (i.e. a
+root process follows a symlink belonging to another user). For a likely
+incomplete list of hundreds of examples across the years, please see:
+https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=/tmp
+
+When set to "0", symlink following behavior is unrestricted.
+
+When set to "1" symlinks are permitted to be followed only when outside
+a sticky world-writable directory, or when the uid of the symlink and
+follower match, or when the directory owner matches the symlink's owner.
+
+This protection is based on the restrictions in Openwall and grsecurity.
+
+
+suid_dumpable
+-------------
+
+This value can be used to query and set the core dump mode for setuid
+or otherwise protected/tainted binaries. The modes are
+
+=   ==========  ===============================================================
+0   (default)	Traditional behaviour. Any process which has changed
+		privilege levels or is execute only will not be dumped.
+1   (debug)	All processes dump core when possible. The core dump is
+		owned by the current user and no security is applied. This is
+		intended for system debugging situations only.
+		Ptrace is unchecked.
+		This is insecure as it allows regular users to examine the
+		memory contents of privileged processes.
+2   (suidsafe)	Any binary which normally would not be dumped is dumped
+		anyway, but only if the ``core_pattern`` kernel sysctl (see
+		:ref:`Documentation/admin-guide/sysctl/kernel.rst <core_pattern>`)
+		is set to
+		either a pipe handler or a fully qualified path. (For more
+		details on this limitation, see CVE-2006-2451.) This mode is
+		appropriate when administrators are attempting to debug
+		problems in a normal environment, and either have a core dump
+		pipe handler that knows to treat privileged core dumps with
+		care, or specific directory defined for catching core dumps.
+		If a core dump happens without a pipe handler or fully
+		qualified path, a message will be emitted to syslog warning
+		about the lack of a correct setting.
+=   ==========  ===============================================================
+
+
+
+2. /proc/sys/fs/binfmt_misc
+===========================
+
+Documentation for the files in ``/proc/sys/fs/binfmt_misc`` is
+in Documentation/admin-guide/binfmt-misc.rst.
+
+
+3. /proc/sys/fs/mqueue - POSIX message queues filesystem
+========================================================
+
+
+The "mqueue"  filesystem provides  the necessary kernel features to enable the
+creation of a  user space  library that  implements  the  POSIX message queues
+API (as noted by the  MSG tag in the  POSIX 1003.1-2001 version  of the System
+Interfaces specification.)
+
+The "mqueue" filesystem contains values for determining/setting the
+amount of resources used by the file system.
+
+``/proc/sys/fs/mqueue/queues_max`` is a read/write file for
+setting/getting the maximum number of message queues allowed on the
+system.
+
+``/proc/sys/fs/mqueue/msg_max`` is a read/write file for
+setting/getting the maximum number of messages in a queue value.  In
+fact it is the limiting value for another (user) limit which is set in
+``mq_open`` invocation.  This attribute of a queue must be less than
+or equal to ``msg_max``.
+
+``/proc/sys/fs/mqueue/msgsize_max`` is a read/write file for
+setting/getting the maximum message size value (it is an attribute of
+every message queue, set during its creation).
+
+``/proc/sys/fs/mqueue/msg_default`` is a read/write file for
+setting/getting the default number of messages in a queue value if the
+``attr`` parameter of ``mq_open(2)`` is ``NULL``. If it exceeds
+``msg_max``, the default value is initialized to ``msg_max``.
+
+``/proc/sys/fs/mqueue/msgsize_default`` is a read/write file for
+setting/getting the default message size value if the ``attr``
+parameter of ``mq_open(2)`` is ``NULL``. If it exceeds
+``msgsize_max``, the default value is initialized to ``msgsize_max``.
+
+4. /proc/sys/fs/epoll - Configuration options for the epoll interface
+=====================================================================
+
+This directory contains configuration options for the epoll(7) interface.
+
+max_user_watches
+----------------
+
+Every epoll file descriptor can store a number of files to be monitored
+for event readiness. Each one of these monitored files constitutes a "watch".
+This configuration option sets the maximum number of "watches" that are
+allowed for each user.
+Each "watch" costs roughly 90 bytes on a 32-bit kernel, and roughly 160 bytes
+on a 64-bit one.
+The current default value for ``max_user_watches`` is 4% of the
+available low memory, divided by the "watch" cost in bytes.
+
+5. /proc/sys/fs/fuse - Configuration options for FUSE filesystems
+=====================================================================
+
+This directory contains the following configuration options for FUSE
+filesystems:
+
+``/proc/sys/fs/fuse/max_pages_limit`` is a read/write file for
+setting/getting the maximum number of pages that can be used for servicing
+requests in FUSE.
+
+``/proc/sys/fs/fuse/default_request_timeout`` is a read/write file for
+setting/getting the default timeout (in seconds) for a fuse server to
+reply to a kernel-issued request in the event where the server did not
+specify a timeout at mount. If the server set a timeout,
+then default_request_timeout will be ignored.  The default
+"default_request_timeout" is set to 0. 0 indicates no default timeout.
+The maximum value that can be set is 65535.
+
+``/proc/sys/fs/fuse/max_request_timeout`` is a read/write file for
+setting/getting the maximum timeout (in seconds) for a fuse server to
+reply to a kernel-issued request. A value greater than 0 automatically opts
+the server into a timeout that will be set to at most "max_request_timeout",
+even if the server did not specify a timeout and default_request_timeout is
+set to 0. If max_request_timeout is greater than 0 and the server set a timeout
+greater than max_request_timeout or default_request_timeout is set to a value
+greater than max_request_timeout, the system will use max_request_timeout as the
+timeout. 0 indicates no max request timeout. The maximum value that can be set
+is 65535.
+
+For timeouts, if the server does not respond to the request by the time
+the set timeout elapses, then the connection to the fuse server will be aborted.
+Please note that the timeouts are not 100% precise (eg you may set 60 seconds but
+the timeout may kick in after 70 seconds). The upper margin of error for the
+timeout is roughly FUSE_TIMEOUT_TIMER_FREQ seconds.
diff --git a/Documentation/admin-guide/sysctl/index.rst b/Documentation/admin-guide/sysctl/index.rst
new file mode 100644
index 000000000..50f00514f
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/index.rst
@@ -0,0 +1,107 @@
+===========================
+Documentation for /proc/sys
+===========================
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+------------------------------------------------------------------------------
+
+'Why', I hear you ask, 'would anyone even _want_ documentation
+for them sysctl files? If anybody really needs it, it's all in
+the source...'
+
+Well, this documentation is written because some people either
+don't know they need to tweak something, or because they don't
+have the time or knowledge to read the source code.
+
+Furthermore, the programmers who built sysctl have built it to
+be actually used, not just for the fun of programming it :-)
+
+------------------------------------------------------------------------------
+
+Legal blurb:
+
+As usual, there are two main things to consider:
+
+1. you get what you pay for
+2. it's free
+
+The consequences are that I won't guarantee the correctness of
+this document, and if you come to me complaining about how you
+screwed up your system because of wrong documentation, I won't
+feel sorry for you. I might even laugh at you...
+
+But of course, if you _do_ manage to screw up your system using
+only the sysctl options used in this file, I'd like to hear of
+it. Not only to have a great laugh, but also to make sure that
+you're the last RTFMing person to screw up.
+
+In short, e-mail your suggestions, corrections and / or horror
+stories to: <riel@nl.linux.org>
+
+Rik van Riel.
+
+--------------------------------------------------------------
+
+Introduction
+============
+
+Sysctl is a means of configuring certain aspects of the kernel
+at run-time, and the /proc/sys/ directory is there so that you
+don't even need special tools to do it!
+In fact, there are only four things needed to use these config
+facilities:
+
+- a running Linux system
+- root access
+- common sense (this is especially hard to come by these days)
+- knowledge of what all those values mean
+
+As a quick 'ls /proc/sys' will show, the directory consists of
+several (arch-dependent?) subdirs. Each subdir is mainly about
+one part of the kernel, so you can do configuration on a piece
+by piece basis, or just some 'thematic frobbing'.
+
+This documentation is about:
+
+=============== ===============================================================
+abi/		execution domains & personalities
+<$ARCH>		tuning controls for various CPU architecture (e.g. csky, s390)
+crypto/		cryptographic subsystem
+debug/		debugging features
+dev/		device specific information (e.g. dev/cdrom/info)
+fs/		specific filesystems
+		filehandle, inode, dentry and quota tuning
+		binfmt_misc <Documentation/admin-guide/binfmt-misc.rst>
+kernel/		global kernel info / tuning
+		miscellaneous stuff
+		some architecture-specific controls
+		security (LSM) stuff
+net/		networking stuff, for documentation look in:
+		<Documentation/networking/>
+proc/		<empty>
+sunrpc/		SUN Remote Procedure Call (NFS)
+user/		Per user namespace limits
+vm/		memory management tuning
+		buffer and cache management
+xen/		Xen hypervisor controls
+=============== ===============================================================
+
+These are the subdirs I have on my system or have been discovered by
+searching through the source code. There might be more or other subdirs
+in another setup. If you see another dir, I'd really like to hear about
+it :-)
+
+.. toctree::
+   :maxdepth: 1
+
+   abi
+   crypto
+   debug
+   fs
+   kernel
+   net
+   sunrpc
+   user
+   vm
+   xen
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
new file mode 100644
index 000000000..b6328cd0f
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -0,0 +1,1753 @@
+===================================
+Documentation for /proc/sys/kernel/
+===================================
+
+.. See scripts/check-sysctl-docs to keep this up to date
+
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+Copyright (c) 2009,        Shen Feng<shen@cn.fujitsu.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+------------------------------------------------------------------------------
+
+This file contains documentation for the sysctl files in
+``/proc/sys/kernel/``.
+
+The files in this directory can be used to tune and monitor
+miscellaneous and general things in the operation of the Linux
+kernel. Since some of the files *can* be used to screw up your
+system, it is advisable to read both documentation and source
+before actually making adjustments.
+
+Currently, these files might (depending on your configuration)
+show up in ``/proc/sys/kernel``:
+
+.. contents:: :local:
+
+
+acct
+====
+
+::
+
+    highwater lowwater frequency
+
+If BSD-style process accounting is enabled these values control
+its behaviour. If free space on filesystem where the log lives
+goes below ``lowwater``\ % accounting suspends. If free space gets
+above ``highwater``\ % accounting resumes. ``frequency`` determines
+how often do we check the amount of free space (value is in
+seconds). Default:
+
+::
+
+    4 2 30
+
+That is, suspend accounting if free space drops below 2%; resume it
+if it increases to at least 4%; consider information about amount of
+free space valid for 30 seconds.
+
+
+acpi_video_flags
+================
+
+See Documentation/power/video.rst. This allows the video resume mode to be set,
+in a similar fashion to the ``acpi_sleep`` kernel parameter, by
+combining the following values:
+
+= =======
+1 s3_bios
+2 s3_mode
+4 s3_beep
+= =======
+
+arch
+====
+
+The machine hardware name, the same output as ``uname -m``
+(e.g. ``x86_64`` or ``aarch64``).
+
+auto_msgmni
+===========
+
+This variable has no effect and may be removed in future kernel
+releases. Reading it always returns 0.
+Up to Linux 3.17, it enabled/disabled automatic recomputing of
+`msgmni`_
+upon memory add/remove or upon IPC namespace creation/removal.
+Echoing "1" into this file enabled msgmni automatic recomputing.
+Echoing "0" turned it off. The default value was 1.
+
+
+bootloader_type (x86 only)
+==========================
+
+This gives the bootloader type number as indicated by the bootloader,
+shifted left by 4, and OR'd with the low four bits of the bootloader
+version.  The reason for this encoding is that this used to match the
+``type_of_loader`` field in the kernel header; the encoding is kept for
+backwards compatibility.  That is, if the full bootloader type number
+is 0x15 and the full version number is 0x234, this file will contain
+the value 340 = 0x154.
+
+See the ``type_of_loader`` and ``ext_loader_type`` fields in
+Documentation/arch/x86/boot.rst for additional information.
+
+
+bootloader_version (x86 only)
+=============================
+
+The complete bootloader version number.  In the example above, this
+file will contain the value 564 = 0x234.
+
+See the ``type_of_loader`` and ``ext_loader_ver`` fields in
+Documentation/arch/x86/boot.rst for additional information.
+
+
+bpf_stats_enabled
+=================
+
+Controls whether the kernel should collect statistics on BPF programs
+(total time spent running, number of times run...). Enabling
+statistics causes a slight reduction in performance on each program
+run. The statistics can be seen using ``bpftool``.
+
+= ===================================
+0 Don't collect statistics (default).
+1 Collect statistics.
+= ===================================
+
+
+cad_pid
+=======
+
+This is the pid which will be signalled on reboot (notably, by
+Ctrl-Alt-Delete). Writing a value to this file which doesn't
+correspond to a running process will result in ``-ESRCH``.
+
+See also `ctrl-alt-del`_.
+
+
+cap_last_cap
+============
+
+Highest valid capability of the running kernel.  Exports
+``CAP_LAST_CAP`` from the kernel.
+
+
+.. _core_pattern:
+
+core_pattern
+============
+
+``core_pattern`` is used to specify a core dumpfile pattern name.
+
+* max length 127 characters; default value is "core"
+* ``core_pattern`` is used as a pattern template for the output
+  filename; certain string patterns (beginning with '%') are
+  substituted with their actual values.
+* backward compatibility with ``core_uses_pid``:
+
+	If ``core_pattern`` does not include "%p" (default does not)
+	and ``core_uses_pid`` is set, then .PID will be appended to
+	the filename.
+
+* corename format specifiers
+
+	========	==========================================
+	%<NUL>		'%' is dropped
+	%%		output one '%'
+	%p		pid
+	%P		global pid (init PID namespace)
+	%i		tid
+	%I		global tid (init PID namespace)
+	%u		uid (in initial user namespace)
+	%g		gid (in initial user namespace)
+	%d		dump mode, matches ``PR_SET_DUMPABLE`` and
+			``/proc/sys/fs/suid_dumpable``
+	%s		signal number
+	%t		UNIX time of dump
+	%h		hostname
+	%e		executable filename (may be shortened, could be changed by prctl etc)
+	%f      	executable filename
+	%E		executable path
+	%c		maximum size of core file by resource limit RLIMIT_CORE
+	%C		CPU the task ran on
+	%F		pidfd number
+	%<OTHER>	both are dropped
+	========	==========================================
+
+* If the first character of the pattern is a '|', the kernel will treat
+  the rest of the pattern as a command to run.  The core dump will be
+  written to the standard input of that program instead of to a file.
+
+
+core_pipe_limit
+===============
+
+This sysctl is only applicable when `core_pattern`_ is configured to
+pipe core files to a user space helper (when the first character of
+``core_pattern`` is a '|', see above).
+When collecting cores via a pipe to an application, it is occasionally
+useful for the collecting application to gather data about the
+crashing process from its ``/proc/pid`` directory.
+In order to do this safely, the kernel must wait for the collecting
+process to exit, so as not to remove the crashing processes proc files
+prematurely.
+This in turn creates the possibility that a misbehaving userspace
+collecting process can block the reaping of a crashed process simply
+by never exiting.
+This sysctl defends against that.
+It defines how many concurrent crashing processes may be piped to user
+space applications in parallel.
+If this value is exceeded, then those crashing processes above that
+value are noted via the kernel log and their cores are skipped.
+0 is a special value, indicating that unlimited processes may be
+captured in parallel, but that no waiting will take place (i.e. the
+collecting process is not guaranteed access to ``/proc/<crashing
+pid>/``).
+This value defaults to 0.
+
+
+core_sort_vma
+=============
+
+The default coredump writes VMAs in address order. By setting
+``core_sort_vma`` to 1, VMAs will be written from smallest size
+to largest size. This is known to break at least elfutils, but
+can be handy when dealing with very large (and truncated)
+coredumps where the more useful debugging details are included
+in the smaller VMAs.
+
+
+core_uses_pid
+=============
+
+The default coredump filename is "core".  By setting
+``core_uses_pid`` to 1, the coredump filename becomes core.PID.
+If `core_pattern`_ does not include "%p" (default does not)
+and ``core_uses_pid`` is set, then .PID will be appended to
+the filename.
+
+
+ctrl-alt-del
+============
+
+When the value in this file is 0, ctrl-alt-del is trapped and
+sent to the ``init(1)`` program to handle a graceful restart.
+When, however, the value is > 0, Linux's reaction to a Vulcan
+Nerve Pinch (tm) will be an immediate reboot, without even
+syncing its dirty buffers.
+
+Note:
+  when a program (like dosemu) has the keyboard in 'raw'
+  mode, the ctrl-alt-del is intercepted by the program before it
+  ever reaches the kernel tty layer, and it's up to the program
+  to decide what to do with it.
+
+
+dmesg_restrict
+==============
+
+This toggle indicates whether unprivileged users are prevented
+from using ``dmesg(8)`` to view messages from the kernel's log
+buffer.
+When ``dmesg_restrict`` is set to 0 there are no restrictions.
+When ``dmesg_restrict`` is set to 1, users must have
+``CAP_SYSLOG`` to use ``dmesg(8)``.
+
+The kernel config option ``CONFIG_SECURITY_DMESG_RESTRICT`` sets the
+default value of ``dmesg_restrict``.
+
+
+domainname & hostname
+=====================
+
+These files can be used to set the NIS/YP domainname and the
+hostname of your box in exactly the same way as the commands
+domainname and hostname, i.e.::
+
+	# echo "darkstar" > /proc/sys/kernel/hostname
+	# echo "mydomain" > /proc/sys/kernel/domainname
+
+has the same effect as::
+
+	# hostname "darkstar"
+	# domainname "mydomain"
+
+Note, however, that the classic darkstar.frop.org has the
+hostname "darkstar" and DNS (Internet Domain Name Server)
+domainname "frop.org", not to be confused with the NIS (Network
+Information Service) or YP (Yellow Pages) domainname. These two
+domain names are in general different. For a detailed discussion
+see the ``hostname(1)`` man page.
+
+
+firmware_config
+===============
+
+See Documentation/driver-api/firmware/fallback-mechanisms.rst.
+
+The entries in this directory allow the firmware loader helper
+fallback to be controlled:
+
+* ``force_sysfs_fallback``, when set to 1, forces the use of the
+  fallback;
+* ``ignore_sysfs_fallback``, when set to 1, ignores any fallback.
+
+
+ftrace_dump_on_oops
+===================
+
+Determines whether ``ftrace_dump()`` should be called on an oops (or
+kernel panic). This will output the contents of the ftrace buffers to
+the console.  This is very useful for capturing traces that lead to
+crashes and outputting them to a serial console.
+
+======================= ===========================================
+0                       Disabled (default).
+1                       Dump buffers of all CPUs.
+2(orig_cpu)             Dump the buffer of the CPU that triggered the
+                        oops.
+<instance>              Dump the specific instance buffer on all CPUs.
+<instance>=2(orig_cpu)  Dump the specific instance buffer on the CPU
+                        that triggered the oops.
+======================= ===========================================
+
+Multiple instance dump is also supported, and instances are separated
+by commas. If global buffer also needs to be dumped, please specify
+the dump mode (1/2/orig_cpu) first for global buffer.
+
+So for example to dump "foo" and "bar" instance buffer on all CPUs,
+user can::
+
+  echo "foo,bar" > /proc/sys/kernel/ftrace_dump_on_oops
+
+To dump global buffer and "foo" instance buffer on all
+CPUs along with the "bar" instance buffer on CPU that triggered the
+oops, user can::
+
+  echo "1,foo,bar=2" > /proc/sys/kernel/ftrace_dump_on_oops
+
+ftrace_enabled, stack_tracer_enabled
+====================================
+
+See Documentation/trace/ftrace.rst.
+
+
+hardlockup_all_cpu_backtrace
+============================
+
+This value controls the hard lockup detector behavior when a hard
+lockup condition is detected as to whether or not to gather further
+debug information. If enabled, arch-specific all-CPU stack dumping
+will be initiated.
+
+= ============================================
+0 Do nothing. This is the default behavior.
+1 On detection capture more debug information.
+= ============================================
+
+
+hardlockup_panic
+================
+
+This parameter can be used to control whether the kernel panics
+when a hard lockup is detected.
+
+= ===========================
+0 Don't panic on hard lockup.
+1 Panic on hard lockup.
+= ===========================
+
+See Documentation/admin-guide/lockup-watchdogs.rst for more information.
+This can also be set using the nmi_watchdog kernel parameter.
+
+
+hotplug
+=======
+
+Path for the hotplug policy agent.
+Default value is ``CONFIG_UEVENT_HELPER_PATH``, which in turn defaults
+to the empty string.
+
+This file only exists when ``CONFIG_UEVENT_HELPER`` is enabled. Most
+modern systems rely exclusively on the netlink-based uevent source and
+don't need this.
+
+
+hung_task_all_cpu_backtrace
+===========================
+
+If this option is set, the kernel will send an NMI to all CPUs to dump
+their backtraces when a hung task is detected. This file shows up if
+CONFIG_DETECT_HUNG_TASK and CONFIG_SMP are enabled.
+
+0: Won't show all CPUs backtraces when a hung task is detected.
+This is the default behavior.
+
+1: Will non-maskably interrupt all CPUs and dump their backtraces when
+a hung task is detected.
+
+
+hung_task_panic
+===============
+
+When set to a non-zero value, a kernel panic will be triggered if the
+number of hung tasks found during a single scan reaches this value.
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+= =======================================================
+0 Continue operation. This is the default behavior.
+N Panic when N hung tasks are found during a single scan.
+= =======================================================
+
+
+hung_task_check_count
+=====================
+
+The upper bound on the number of tasks that are checked.
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+
+hung_task_detect_count
+======================
+
+Indicates the total number of tasks that have been detected as hung since
+the system boot or since the counter was reset. The counter is zeroed when
+a value of 0 is written.
+
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+hung_task_sys_info
+==================
+A comma separated list of extra system information to be dumped when
+hung task is detected, for example, "tasks,mem,timers,locks,...".
+Refer 'panic_sys_info' section below for more details.
+
+hung_task_timeout_secs
+======================
+
+When a task in D state did not get scheduled
+for more than this value report a warning.
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+0 means infinite timeout, no checking is done.
+
+Possible values to set are in range {0:``LONG_MAX``/``HZ``}.
+
+
+hung_task_check_interval_secs
+=============================
+
+Hung task check interval. If hung task checking is enabled
+(see `hung_task_timeout_secs`_), the check is done every
+``hung_task_check_interval_secs`` seconds.
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+0 (default) means use ``hung_task_timeout_secs`` as checking
+interval.
+
+Possible values to set are in range {0:``LONG_MAX``/``HZ``}.
+
+
+hung_task_warnings
+==================
+
+The maximum number of warnings to report. During a check interval
+if a hung task is detected, this value is decreased by 1.
+When this value reaches 0, no more warnings will be reported.
+This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled.
+
+-1: report an infinite number of warnings.
+
+
+hyperv_record_panic_msg
+=======================
+
+Controls whether the panic kmsg data should be reported to Hyper-V.
+
+= =========================================================
+0 Do not report panic kmsg data.
+1 Report the panic kmsg data. This is the default behavior.
+= =========================================================
+
+
+ignore-unaligned-usertrap
+=========================
+
+On architectures where unaligned accesses cause traps, and where this
+feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN``;
+currently, ``arc``, ``parisc`` and ``loongarch``), controls whether all
+unaligned traps are logged.
+
+= =============================================================
+0 Log all unaligned accesses.
+1 Only warn the first time a process traps. This is the default
+  setting.
+= =============================================================
+
+See also `unaligned-trap`_.
+
+io_uring_disabled
+=================
+
+Prevents all processes from creating new io_uring instances. Enabling this
+shrinks the kernel's attack surface.
+
+= ======================================================================
+0 All processes can create io_uring instances as normal. This is the
+  default setting.
+1 io_uring creation is disabled (io_uring_setup() will fail with
+  -EPERM) for unprivileged processes not in the io_uring_group group.
+  Existing io_uring instances can still be used.  See the
+  documentation for io_uring_group for more information.
+2 io_uring creation is disabled for all processes. io_uring_setup()
+  always fails with -EPERM. Existing io_uring instances can still be
+  used.
+= ======================================================================
+
+
+io_uring_group
+==============
+
+When io_uring_disabled is set to 1, a process must either be
+privileged (CAP_SYS_ADMIN) or be in the io_uring_group group in order
+to create an io_uring instance.  If io_uring_group is set to -1 (the
+default), only processes with the CAP_SYS_ADMIN capability may create
+io_uring instances.
+
+
+kernel_sys_info
+===============
+A comma separated list of extra system information to be dumped when
+soft/hard lockup is detected, for example, "tasks,mem,timers,locks,...".
+Refer 'panic_sys_info' section below for more details.
+
+It serves as the default kernel control knob, which will take effect
+when a kernel module calls sys_info() with parameter==0.
+
+kexec_load_disabled
+===================
+
+A toggle indicating if the syscalls ``kexec_load`` and
+``kexec_file_load`` have been disabled.
+This value defaults to 0 (false: ``kexec_*load`` enabled), but can be
+set to 1 (true: ``kexec_*load`` disabled).
+Once true, kexec can no longer be used, and the toggle cannot be set
+back to false.
+This allows a kexec image to be loaded before disabling the syscall,
+allowing a system to set up (and later use) an image without it being
+altered.
+Generally used together with the `modules_disabled`_ sysctl.
+
+kexec_load_limit_panic
+======================
+
+This parameter specifies a limit to the number of times the syscalls
+``kexec_load`` and ``kexec_file_load`` can be called with a crash
+image. It can only be set with a more restrictive value than the
+current one.
+
+== ======================================================
+-1 Unlimited calls to kexec. This is the default setting.
+N  Number of calls left.
+== ======================================================
+
+kexec_load_limit_reboot
+=======================
+
+Similar functionality as ``kexec_load_limit_panic``, but for a normal
+image.
+
+kptr_restrict
+=============
+
+This toggle indicates whether restrictions are placed on
+exposing kernel addresses via ``/proc`` and other interfaces.
+
+When ``kptr_restrict`` is set to 0 (the default) the address is hashed
+before printing.
+(This is the equivalent to %p.)
+
+When ``kptr_restrict`` is set to 1, kernel pointers printed using the
+%pK format specifier will be replaced with 0s unless the user has
+``CAP_SYSLOG`` and effective user and group ids are equal to the real
+ids.
+This is because %pK checks are done at read() time rather than open()
+time, so if permissions are elevated between the open() and the read()
+(e.g via a setuid binary) then %pK will not leak kernel pointers to
+unprivileged users.
+Note, this is a temporary solution only.
+The correct long-term solution is to do the permission checks at
+open() time.
+Consider removing world read permissions from files that use %pK, and
+using `dmesg_restrict`_ to protect against uses of %pK in ``dmesg(8)``
+if leaking kernel pointer values to unprivileged users is a concern.
+
+When ``kptr_restrict`` is set to 2, kernel pointers printed using
+%pK will be replaced with 0s regardless of privileges.
+
+For disabling these security restrictions early at boot time (and once
+for all), use the ``hash_pointers`` boot parameter instead.
+
+softlockup_sys_info & hardlockup_sys_info
+=========================================
+A comma separated list of extra system information to be dumped when
+soft/hard lockup is detected, for example, "tasks,mem,timers,locks,...".
+Refer 'panic_sys_info' section below for more details.
+
+modprobe
+========
+
+The full path to the usermode helper for autoloading kernel modules,
+by default ``CONFIG_MODPROBE_PATH``, which in turn defaults to
+"/sbin/modprobe".  This binary is executed when the kernel requests a
+module.  For example, if userspace passes an unknown filesystem type
+to mount(), then the kernel will automatically request the
+corresponding filesystem module by executing this usermode helper.
+This usermode helper should insert the needed module into the kernel.
+
+This sysctl only affects module autoloading.  It has no effect on the
+ability to explicitly insert modules.
+
+This sysctl can be used to debug module loading requests::
+
+    echo '#! /bin/sh' > /tmp/modprobe
+    echo 'echo "$@" >> /tmp/modprobe.log' >> /tmp/modprobe
+    echo 'exec /sbin/modprobe "$@"' >> /tmp/modprobe
+    chmod a+x /tmp/modprobe
+    echo /tmp/modprobe > /proc/sys/kernel/modprobe
+
+Alternatively, if this sysctl is set to the empty string, then module
+autoloading is completely disabled.  The kernel will not try to
+execute a usermode helper at all, nor will it call the
+kernel_module_request LSM hook.
+
+If CONFIG_STATIC_USERMODEHELPER=y is set in the kernel configuration,
+then the configured static usermode helper overrides this sysctl,
+except that the empty string is still accepted to completely disable
+module autoloading as described above.
+
+modules_disabled
+================
+
+A toggle value indicating if modules are allowed to be loaded
+in an otherwise modular kernel.  This toggle defaults to off
+(0), but can be set true (1).  Once true, modules can be
+neither loaded nor unloaded, and the toggle cannot be set back
+to false.  Generally used with the `kexec_load_disabled`_ toggle.
+
+
+.. _msgmni:
+
+msgmax, msgmnb, and msgmni
+==========================
+
+``msgmax`` is the maximum size of an IPC message, in bytes. 8192 by
+default (``MSGMAX``).
+
+``msgmnb`` is the maximum size of an IPC queue, in bytes. 16384 by
+default (``MSGMNB``).
+
+``msgmni`` is the maximum number of IPC queues. 32000 by default
+(``MSGMNI``).
+
+All of these parameters are set per ipc namespace. The maximum number of bytes
+in POSIX message queues is limited by ``RLIMIT_MSGQUEUE``. This limit is
+respected hierarchically in the each user namespace.
+
+msg_next_id, sem_next_id, and shm_next_id (System V IPC)
+========================================================
+
+These three toggles allows to specify desired id for next allocated IPC
+object: message, semaphore or shared memory respectively.
+
+By default they are equal to -1, which means generic allocation logic.
+Possible values to set are in range {0:``INT_MAX``}.
+
+Notes:
+  1) kernel doesn't guarantee, that new object will have desired id. So,
+     it's up to userspace, how to handle an object with "wrong" id.
+  2) Toggle with non-default value will be set back to -1 by kernel after
+     successful IPC object allocation. If an IPC object allocation syscall
+     fails, it is undefined if the value remains unmodified or is reset to -1.
+
+
+ngroups_max
+===========
+
+Maximum number of supplementary groups, _i.e._ the maximum size which
+``setgroups`` will accept. Exports ``NGROUPS_MAX`` from the kernel.
+
+
+
+nmi_watchdog
+============
+
+This parameter can be used to control the NMI watchdog
+(i.e. the hard lockup detector) on x86 systems.
+
+= =================================
+0 Disable the hard lockup detector.
+1 Enable the hard lockup detector.
+= =================================
+
+The hard lockup detector monitors each CPU for its ability to respond to
+timer interrupts. The mechanism utilizes CPU performance counter registers
+that are programmed to generate Non-Maskable Interrupts (NMIs) periodically
+while a CPU is busy. Hence, the alternative name 'NMI watchdog'.
+
+The NMI watchdog is disabled by default if the kernel is running as a guest
+in a KVM virtual machine. This default can be overridden by adding::
+
+   nmi_watchdog=1
+
+to the guest kernel command line (see
+Documentation/admin-guide/kernel-parameters.rst).
+
+
+nmi_wd_lpm_factor (PPC only)
+============================
+
+Factor to apply to the NMI watchdog timeout (only when ``nmi_watchdog`` is
+set to 1). This factor represents the percentage added to
+``watchdog_thresh`` when calculating the NMI watchdog timeout during an
+LPM. The soft lockup timeout is not impacted.
+
+A value of 0 means no change. The default value is 200 meaning the NMI
+watchdog is set to 30s (based on ``watchdog_thresh`` equal to 10).
+
+
+numa_balancing
+==============
+
+Enables/disables and configures automatic page fault based NUMA memory
+balancing.  Memory is moved automatically to nodes that access it often.
+The value to set can be the result of ORing the following:
+
+= =================================
+0 NUMA_BALANCING_DISABLED
+1 NUMA_BALANCING_NORMAL
+2 NUMA_BALANCING_MEMORY_TIERING
+= =================================
+
+Or NUMA_BALANCING_NORMAL to optimize page placement among different
+NUMA nodes to reduce remote accessing.  On NUMA machines, there is a
+performance penalty if remote memory is accessed by a CPU. When this
+feature is enabled the kernel samples what task thread is accessing
+memory by periodically unmapping pages and later trapping a page
+fault. At the time of the page fault, it is determined if the data
+being accessed should be migrated to a local memory node.
+
+The unmapping of pages and trapping faults incur additional overhead that
+ideally is offset by improved memory locality but there is no universal
+guarantee. If the target workload is already bound to NUMA nodes then this
+feature should be disabled.
+
+Or NUMA_BALANCING_MEMORY_TIERING to optimize page placement among
+different types of memory (represented as different NUMA nodes) to
+place the hot pages in the fast memory.  This is implemented based on
+unmapping and page fault too.
+
+numa_balancing_promote_rate_limit_MBps
+======================================
+
+Too high promotion/demotion throughput between different memory types
+may hurt application latency.  This can be used to rate limit the
+promotion throughput.  The per-node max promotion throughput in MB/s
+will be limited to be no more than the set value.
+
+A rule of thumb is to set this to less than 1/10 of the PMEM node
+write bandwidth.
+
+oops_all_cpu_backtrace
+======================
+
+If this option is set, the kernel will send an NMI to all CPUs to dump
+their backtraces when an oops event occurs. It should be used as a last
+resort in case a panic cannot be triggered (to protect VMs running, for
+example) or kdump can't be collected. This file shows up if CONFIG_SMP
+is enabled.
+
+0: Won't show all CPUs backtraces when an oops is detected.
+This is the default behavior.
+
+1: Will non-maskably interrupt all CPUs and dump their backtraces when
+an oops event is detected.
+
+
+oops_limit
+==========
+
+Number of kernel oopses after which the kernel should panic when
+``panic_on_oops`` is not set. Setting this to 0 disables checking
+the count. Setting this to  1 has the same effect as setting
+``panic_on_oops=1``. The default value is 10000.
+
+
+osrelease, ostype & version
+===========================
+
+::
+
+  # cat osrelease
+  2.1.88
+  # cat ostype
+  Linux
+  # cat version
+  #5 Wed Feb 25 21:49:24 MET 1998
+
+The files ``osrelease`` and ``ostype`` should be clear enough.
+``version``
+needs a little more clarification however. The '#5' means that
+this is the fifth kernel built from this source base and the
+date behind it indicates the time the kernel was built.
+The only way to tune these values is to rebuild the kernel :-)
+
+
+overflowgid & overflowuid
+=========================
+
+if your architecture did not always support 32-bit UIDs (i.e. arm,
+i386, m68k, sh, and sparc32), a fixed UID and GID will be returned to
+applications that use the old 16-bit UID/GID system calls, if the
+actual UID or GID would exceed 65535.
+
+These sysctls allow you to change the value of the fixed UID and GID.
+The default is 65534.
+
+
+panic
+=====
+
+The value in this file determines the behaviour of the kernel on a
+panic:
+
+* if zero, the kernel will loop forever;
+* if negative, the kernel will reboot immediately;
+* if positive, the kernel will reboot after the corresponding number
+  of seconds.
+
+When you use the software watchdog, the recommended setting is 60.
+
+
+panic_on_io_nmi
+===============
+
+Controls the kernel's behavior when a CPU receives an NMI caused by
+an IO error.
+
+= ==================================================================
+0 Try to continue operation (default).
+1 Panic immediately. The IO error triggered an NMI. This indicates a
+  serious system condition which could result in IO data corruption.
+  Rather than continuing, panicking might be a better choice. Some
+  servers issue this sort of NMI when the dump button is pushed,
+  and you can use this option to take a crash dump.
+= ==================================================================
+
+
+panic_on_oops
+=============
+
+Controls the kernel's behaviour when an oops or BUG is encountered.
+
+= ===================================================================
+0 Try to continue operation.
+1 Panic immediately.  If the `panic` sysctl is also non-zero then the
+  machine will be rebooted.
+= ===================================================================
+
+
+panic_on_stackoverflow
+======================
+
+Controls the kernel's behavior when detecting the overflows of
+kernel, IRQ and exception stacks except a user stack.
+This file shows up if ``CONFIG_DEBUG_STACKOVERFLOW`` is enabled.
+
+= ==========================
+0 Try to continue operation.
+1 Panic immediately.
+= ==========================
+
+
+panic_on_unrecovered_nmi
+========================
+
+The default Linux behaviour on an NMI of either memory or unknown is
+to continue operation. For many environments such as scientific
+computing it is preferable that the box is taken out and the error
+dealt with than an uncorrected parity/ECC error get propagated.
+
+A small number of systems do generate NMIs for bizarre random reasons
+such as power management so the default is off. That sysctl works like
+the existing panic controls already in that directory.
+
+
+panic_on_warn
+=============
+
+Calls panic() in the WARN() path when set to 1.  This is useful to avoid
+a kernel rebuild when attempting to kdump at the location of a WARN().
+
+= ================================================
+0 Only WARN(), default behaviour.
+1 Call panic() after printing out WARN() location.
+= ================================================
+
+
+panic_print
+===========
+
+Bitmask for printing system info when panic happens. User can chose
+combination of the following bits:
+
+=====  ============================================
+bit 0  print all tasks info
+bit 1  print system memory info
+bit 2  print timer info
+bit 3  print locks info if ``CONFIG_LOCKDEP`` is on
+bit 4  print ftrace buffer
+bit 5  replay all kernel messages on consoles at the end of panic
+bit 6  print all CPUs backtrace (if available in the arch)
+bit 7  print only tasks in uninterruptible (blocked) state
+=====  ============================================
+
+So for example to print tasks and memory info on panic, user can::
+
+  echo 3 > /proc/sys/kernel/panic_print
+
+
+panic_sys_info
+==============
+
+A comma separated list of extra information to be dumped on panic,
+for example, "tasks,mem,timers,...".  It is a human readable alternative
+to 'panic_print'. Possible values are:
+
+=============   ===================================================
+tasks           print all tasks info
+mem             print system memory info
+timers          print timers info
+locks           print locks info if CONFIG_LOCKDEP is on
+ftrace          print ftrace buffer
+all_bt          print all CPUs backtrace (if available in the arch)
+blocked_tasks   print only tasks in uninterruptible (blocked) state
+=============   ===================================================
+
+
+panic_on_rcu_stall
+==================
+
+When set to 1, calls panic() after RCU stall detection messages. This
+is useful to define the root cause of RCU stalls using a vmcore.
+
+= ============================================================
+0 Do not panic() when RCU stall takes place, default behavior.
+1 panic() after printing RCU stall messages.
+= ============================================================
+
+max_rcu_stall_to_panic
+======================
+
+When ``panic_on_rcu_stall`` is set to 1, this value determines the
+number of times that RCU can stall before panic() is called.
+
+When ``panic_on_rcu_stall`` is set to 0, this value is has no effect.
+
+perf_cpu_time_max_percent
+=========================
+
+Hints to the kernel how much CPU time it should be allowed to
+use to handle perf sampling events.  If the perf subsystem
+is informed that its samples are exceeding this limit, it
+will drop its sampling frequency to attempt to reduce its CPU
+usage.
+
+Some perf sampling happens in NMIs.  If these samples
+unexpectedly take too long to execute, the NMIs can become
+stacked up next to each other so much that nothing else is
+allowed to execute.
+
+===== ========================================================
+0     Disable the mechanism.  Do not monitor or correct perf's
+      sampling rate no matter how CPU time it takes.
+
+1-100 Attempt to throttle perf's sample rate to this
+      percentage of CPU.  Note: the kernel calculates an
+      "expected" length of each sample event.  100 here means
+      100% of that expected length.  Even if this is set to
+      100, you may still see sample throttling if this
+      length is exceeded.  Set to 0 if you truly do not care
+      how much CPU is consumed.
+===== ========================================================
+
+
+perf_event_paranoid
+===================
+
+Controls use of the performance events system by unprivileged
+users (without CAP_PERFMON).  The default value is 2.
+
+For backward compatibility reasons access to system performance
+monitoring and observability remains open for CAP_SYS_ADMIN
+privileged processes but CAP_SYS_ADMIN usage for secure system
+performance monitoring and observability operations is discouraged
+with respect to CAP_PERFMON use cases.
+
+===  ==================================================================
+ -1  Allow use of (almost) all events by all users.
+
+     Ignore mlock limit after perf_event_mlock_kb without
+     ``CAP_IPC_LOCK``.
+
+>=0  Disallow ftrace function tracepoint by users without
+     ``CAP_PERFMON``.
+
+     Disallow raw tracepoint access by users without ``CAP_PERFMON``.
+
+>=1  Disallow CPU event access by users without ``CAP_PERFMON``.
+
+>=2  Disallow kernel profiling by users without ``CAP_PERFMON``.
+===  ==================================================================
+
+
+perf_event_max_stack
+====================
+
+Controls maximum number of stack frames to copy for (``attr.sample_type &
+PERF_SAMPLE_CALLCHAIN``) configured events, for instance, when using
+'``perf record -g``' or '``perf trace --call-graph fp``'.
+
+This can only be done when no events are in use that have callchains
+enabled, otherwise writing to this file will return ``-EBUSY``.
+
+The default value is 127.
+
+
+perf_event_mlock_kb
+===================
+
+Control size of per-cpu ring buffer not counted against mlock limit.
+
+The default value is 512 + 1 page
+
+
+perf_event_max_contexts_per_stack
+=================================
+
+Controls maximum number of stack frame context entries for
+(``attr.sample_type & PERF_SAMPLE_CALLCHAIN``) configured events, for
+instance, when using '``perf record -g``' or '``perf trace --call-graph fp``'.
+
+This can only be done when no events are in use that have callchains
+enabled, otherwise writing to this file will return ``-EBUSY``.
+
+The default value is 8.
+
+
+perf_user_access (arm64 and riscv only)
+=======================================
+
+Controls user space access for reading perf event counters.
+
+* for arm64
+  The default value is 0 (access disabled).
+
+  When set to 1, user space can read performance monitor counter registers
+  directly.
+
+  See Documentation/arch/arm64/perf.rst for more information.
+
+* for riscv
+  When set to 0, user space access is disabled.
+
+  The default value is 1, user space can read performance monitor counter
+  registers through perf, any direct access without perf intervention will trigger
+  an illegal instruction.
+
+  When set to 2, which enables legacy mode (user space has direct access to cycle
+  and insret CSRs only). Note that this legacy value is deprecated and will be
+  removed once all user space applications are fixed.
+
+  Note that the time CSR is always directly accessible to all modes.
+
+pid_max
+=======
+
+PID allocation wrap value.  When the kernel's next PID value
+reaches this value, it wraps back to a minimum PID value.
+PIDs of value ``pid_max`` or larger are not allocated.
+
+
+ns_last_pid
+===========
+
+The last pid allocated in the current (the one task using this sysctl
+lives in) pid namespace. When selecting a pid for a next task on fork
+kernel tries to allocate a number starting from this one.
+
+
+powersave-nap (PPC only)
+========================
+
+If set, Linux-PPC will use the 'nap' mode of powersaving,
+otherwise the 'doze' mode will be used.
+
+
+==============================================================
+
+printk
+======
+
+The four values in printk denote: ``console_loglevel``,
+``default_message_loglevel``, ``minimum_console_loglevel`` and
+``default_console_loglevel`` respectively.
+
+These values influence printk() behavior when printing or
+logging error messages. See '``man 2 syslog``' for more info on
+the different loglevels.
+
+======================== =====================================
+console_loglevel         messages with a higher priority than
+                         this will be printed to the console
+default_message_loglevel messages without an explicit priority
+                         will be printed with this priority
+minimum_console_loglevel minimum (highest) value to which
+                         console_loglevel can be set
+default_console_loglevel default value for console_loglevel
+======================== =====================================
+
+
+printk_delay
+============
+
+Delay each printk message in ``printk_delay`` milliseconds
+
+Value from 0 - 10000 is allowed.
+
+
+printk_ratelimit
+================
+
+Some warning messages are rate limited. ``printk_ratelimit`` specifies
+the minimum length of time between these messages (in seconds).
+The default value is 5 seconds.
+
+A value of 0 will disable rate limiting.
+
+
+printk_ratelimit_burst
+======================
+
+While long term we enforce one message per `printk_ratelimit`_
+seconds, we do allow a burst of messages to pass through.
+``printk_ratelimit_burst`` specifies the number of messages we can
+send before ratelimiting kicks in.  After `printk_ratelimit`_ seconds
+have elapsed, another burst of messages may be sent.
+
+The default value is 10 messages.
+
+
+printk_devkmsg
+==============
+
+Control the logging to ``/dev/kmsg`` from userspace:
+
+========= =============================================
+ratelimit default, ratelimited
+on        unlimited logging to /dev/kmsg from userspace
+off       logging to /dev/kmsg disabled
+========= =============================================
+
+The kernel command line parameter ``printk.devkmsg=`` overrides this and is
+a one-time setting until next reboot: once set, it cannot be changed by
+this sysctl interface anymore.
+
+==============================================================
+
+
+pty
+===
+
+See Documentation/filesystems/devpts.rst.
+
+
+random
+======
+
+This is a directory, with the following entries:
+
+* ``boot_id``: a UUID generated the first time this is retrieved, and
+  unvarying after that;
+
+* ``uuid``: a UUID generated every time this is retrieved (this can
+  thus be used to generate UUIDs at will);
+
+* ``entropy_avail``: the pool's entropy count, in bits;
+
+* ``poolsize``: the entropy pool size, in bits;
+
+* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum
+  number of seconds between urandom pool reseeding). This file is
+  writable for compatibility purposes, but writing to it has no effect
+  on any RNG behavior;
+
+* ``write_wakeup_threshold``: when the entropy count drops below this
+  (as a number of bits), processes waiting to write to ``/dev/random``
+  are woken up. This file is writable for compatibility purposes, but
+  writing to it has no effect on any RNG behavior.
+
+
+randomize_va_space
+==================
+
+This option can be used to select the type of process address
+space randomization that is used in the system, for architectures
+that support this feature.
+
+==  ===========================================================================
+0   Turn the process address space randomization off.  This is the
+    default for architectures that do not support this feature anyways,
+    and kernels that are booted with the "norandmaps" parameter.
+
+1   Make the addresses of mmap base, stack and VDSO page randomized.
+    This, among other things, implies that shared libraries will be
+    loaded to random addresses.  Also for PIE-linked binaries, the
+    location of code start is randomized.  This is the default if the
+    ``CONFIG_COMPAT_BRK`` option is enabled.
+
+2   Additionally enable heap randomization.  This is the default if
+    ``CONFIG_COMPAT_BRK`` is disabled.
+
+    There are a few legacy applications out there (such as some ancient
+    versions of libc.so.5 from 1996) that assume that brk area starts
+    just after the end of the code+bss.  These applications break when
+    start of the brk area is randomized.  There are however no known
+    non-legacy applications that would be broken this way, so for most
+    systems it is safe to choose full randomization.
+
+    Systems with ancient and/or broken binaries should be configured
+    with ``CONFIG_COMPAT_BRK`` enabled, which excludes the heap from process
+    address space randomization.
+==  ===========================================================================
+
+
+reboot-cmd (SPARC only)
+=======================
+
+??? This seems to be a way to give an argument to the Sparc
+ROM/Flash boot loader. Maybe to tell it what to do after
+rebooting. ???
+
+
+sched_energy_aware
+==================
+
+Enables/disables Energy Aware Scheduling (EAS). EAS starts
+automatically on platforms where it can run (that is,
+platforms with asymmetric CPU topologies and having an Energy
+Model available). If your platform happens to meet the
+requirements for EAS but you do not want to use it, change
+this value to 0. On Non-EAS platforms, write operation fails and
+read doesn't return anything.
+
+task_delayacct
+===============
+
+Enables/disables task delay accounting (see
+Documentation/accounting/delay-accounting.rst. Enabling this feature incurs
+a small amount of overhead in the scheduler but is useful for debugging
+and performance tuning. It is required by some tools such as iotop.
+
+sched_schedstats
+================
+
+Enables/disables scheduler statistics. Enabling this feature
+incurs a small amount of overhead in the scheduler but is
+useful for debugging and performance tuning.
+
+sched_util_clamp_min
+====================
+
+Max allowed *minimum* utilization.
+
+Default value is 1024, which is the maximum possible value.
+
+It means that any requested uclamp.min value cannot be greater than
+sched_util_clamp_min, i.e., it is restricted to the range
+[0:sched_util_clamp_min].
+
+sched_util_clamp_max
+====================
+
+Max allowed *maximum* utilization.
+
+Default value is 1024, which is the maximum possible value.
+
+It means that any requested uclamp.max value cannot be greater than
+sched_util_clamp_max, i.e., it is restricted to the range
+[0:sched_util_clamp_max].
+
+sched_util_clamp_min_rt_default
+===============================
+
+By default Linux is tuned for performance. Which means that RT tasks always run
+at the highest frequency and most capable (highest capacity) CPU (in
+heterogeneous systems).
+
+Uclamp achieves this by setting the requested uclamp.min of all RT tasks to
+1024 by default, which effectively boosts the tasks to run at the highest
+frequency and biases them to run on the biggest CPU.
+
+This knob allows admins to change the default behavior when uclamp is being
+used. In battery powered devices particularly, running at the maximum
+capacity and frequency will increase energy consumption and shorten the battery
+life.
+
+This knob is only effective for RT tasks which the user hasn't modified their
+requested uclamp.min value via sched_setattr() syscall.
+
+This knob will not escape the range constraint imposed by sched_util_clamp_min
+defined above.
+
+For example if
+
+	sched_util_clamp_min_rt_default = 800
+	sched_util_clamp_min = 600
+
+Then the boost will be clamped to 600 because 800 is outside of the permissible
+range of [0:600]. This could happen for instance if a powersave mode will
+restrict all boosts temporarily by modifying sched_util_clamp_min. As soon as
+this restriction is lifted, the requested sched_util_clamp_min_rt_default
+will take effect.
+
+seccomp
+=======
+
+See Documentation/userspace-api/seccomp_filter.rst.
+
+
+sg-big-buff
+===========
+
+This file shows the size of the generic SCSI (sg) buffer.
+You can't tune it just yet, but you could change it on
+compile time by editing ``include/scsi/sg.h`` and changing
+the value of ``SG_BIG_BUFF``.
+
+There shouldn't be any reason to change this value. If
+you can come up with one, you probably know what you
+are doing anyway :)
+
+
+shmall
+======
+
+This parameter sets the total amount of shared memory pages that can be used
+inside ipc namespace. The shared memory pages counting occurs for each ipc
+namespace separately and is not inherited. Hence, ``shmall`` should always be at
+least ``ceil(shmmax/PAGE_SIZE)``.
+
+If you are not sure what the default ``PAGE_SIZE`` is on your Linux
+system, you can run the following command::
+
+	# getconf PAGE_SIZE
+
+To reduce or disable the ability to allocate shared memory, you must create a
+new ipc namespace, set this parameter to the required value and prohibit the
+creation of a new ipc namespace in the current user namespace or cgroups can
+be used.
+
+shmmax
+======
+
+This value can be used to query and set the run time limit
+on the maximum shared memory segment size that can be created.
+Shared memory segments up to 1Gb are now supported in the
+kernel.  This value defaults to ``SHMMAX``.
+
+
+shmmni
+======
+
+This value determines the maximum number of shared memory segments.
+4096 by default (``SHMMNI``).
+
+
+shm_rmid_forced
+===============
+
+Linux lets you set resource limits, including how much memory one
+process can consume, via ``setrlimit(2)``.  Unfortunately, shared memory
+segments are allowed to exist without association with any process, and
+thus might not be counted against any resource limits.  If enabled,
+shared memory segments are automatically destroyed when their attach
+count becomes zero after a detach or a process termination.  It will
+also destroy segments that were created, but never attached to, on exit
+from the process.  The only use left for ``IPC_RMID`` is to immediately
+destroy an unattached segment.  Of course, this breaks the way things are
+defined, so some applications might stop working.  Note that this
+feature will do you no good unless you also configure your resource
+limits (in particular, ``RLIMIT_AS`` and ``RLIMIT_NPROC``).  Most systems don't
+need this.
+
+Note that if you change this from 0 to 1, already created segments
+without users and with a dead originative process will be destroyed.
+
+
+syscall_user_dispatch
+=====================
+
+Controls whether userspace may arm Syscall User Dispatch via
+``prctl(PR_SET_SYSCALL_USER_DISPATCH, ...)`` or the
+``PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG`` ptrace request:
+
+  ==  ===================================================================
+  0   Arming syscall user dispatch is denied with ``-EPERM``.  Tasks that
+      already armed it keep it, and disabling it is always permitted.
+  1   (default) Arming syscall user dispatch is permitted.
+  ==  ===================================================================
+
+Only present when the kernel is built with ``CONFIG_SYSCALL_USER_DISPATCH``
+and ``CONFIG_PROC_SYSCTL``.
+
+
+sysctl_writes_strict
+====================
+
+Control how file position affects the behavior of updating sysctl values
+via the ``/proc/sys`` interface:
+
+  ==   ======================================================================
+  -1   Legacy per-write sysctl value handling, with no printk warnings.
+       Each write syscall must fully contain the sysctl value to be
+       written, and multiple writes on the same sysctl file descriptor
+       will rewrite the sysctl value, regardless of file position.
+   0   Same behavior as above, but warn about processes that perform writes
+       to a sysctl file descriptor when the file position is not 0.
+   1   (default) Respect file position when writing sysctl strings. Multiple
+       writes will append to the sysctl value buffer. Anything past the max
+       length of the sysctl value buffer will be ignored. Writes to numeric
+       sysctl entries must always be at file position 0 and the value must
+       be fully contained in the buffer sent in the write syscall.
+  ==   ======================================================================
+
+
+softlockup_all_cpu_backtrace
+============================
+
+This value controls the soft lockup detector thread's behavior
+when a soft lockup condition is detected as to whether or not
+to gather further debug information. If enabled, each cpu will
+be issued an NMI and instructed to capture stack trace.
+
+This feature is only applicable for architectures which support
+NMI.
+
+= ============================================
+0 Do nothing. This is the default behavior.
+1 On detection capture more debug information.
+= ============================================
+
+
+softlockup_panic
+=================
+
+This parameter can be used to control whether the kernel panics
+when a soft lockup is detected.
+
+= ============================================
+0 Don't panic on soft lockup.
+1 Panic on soft lockup.
+= ============================================
+
+This can also be set using the softlockup_panic kernel parameter.
+
+
+soft_watchdog
+=============
+
+This parameter can be used to control the soft lockup detector.
+
+= =================================
+0 Disable the soft lockup detector.
+1 Enable the soft lockup detector.
+= =================================
+
+The soft lockup detector monitors CPUs for threads that are hogging the CPUs
+without rescheduling voluntarily, and thus prevent the 'migration/N' threads
+from running, causing the watchdog work fail to execute. The mechanism depends
+on the CPUs ability to respond to timer interrupts which are needed for the
+watchdog work to be queued by the watchdog timer function, otherwise the NMI
+watchdog — if enabled — can detect a hard lockup condition.
+
+
+split_lock_mitigate (x86 only)
+==============================
+
+On x86, each "split lock" imposes a system-wide performance penalty. On larger
+systems, large numbers of split locks from unprivileged users can result in
+denials of service to well-behaved and potentially more important users.
+
+The kernel mitigates these bad users by detecting split locks and imposing
+penalties: forcing them to wait and only allowing one core to execute split
+locks at a time.
+
+These mitigations can make those bad applications unbearably slow. Setting
+split_lock_mitigate=0 may restore some application performance, but will also
+increase system exposure to denial of service attacks from split lock users.
+
+= ===================================================================
+0 Disable the mitigation mode - just warns the split lock on kernel log
+  and exposes the system to denials of service from the split lockers.
+1 Enable the mitigation mode (this is the default) - penalizes the split
+  lockers with intentional performance degradation.
+= ===================================================================
+
+
+stack_erasing
+=============
+
+This parameter can be used to control kernel stack erasing at the end
+of syscalls for kernels built with ``CONFIG_KSTACK_ERASE``.
+
+That erasing reduces the information which kernel stack leak bugs
+can reveal and blocks some uninitialized stack variable attacks.
+The tradeoff is the performance impact: on a single CPU system kernel
+compilation sees a 1% slowdown, other systems and workloads may vary.
+
+= ====================================================================
+0 Kernel stack erasing is disabled, KSTACK_ERASE_METRICS are not updated.
+1 Kernel stack erasing is enabled (default), it is performed before
+  returning to the userspace at the end of syscalls.
+= ====================================================================
+
+
+stop-a (SPARC only)
+===================
+
+Controls Stop-A:
+
+= ====================================
+0 Stop-A has no effect.
+1 Stop-A breaks to the PROM (default).
+= ====================================
+
+Stop-A is always enabled on a panic, so that the user can return to
+the boot PROM.
+
+
+sysrq
+=====
+
+See Documentation/admin-guide/sysrq.rst.
+
+
+tainted
+=======
+
+Non-zero if the kernel has been tainted. Numeric values, which can be
+ORed together. The letters are seen in "Tainted" line of Oops reports.
+
+======  =====  ==============================================================
+     1  `(P)`  proprietary module was loaded
+     2  `(F)`  module was force loaded
+     4  `(S)`  kernel running on an out of specification system
+     8  `(R)`  module was force unloaded
+    16  `(M)`  processor reported a Machine Check Exception (MCE)
+    32  `(B)`  bad page referenced or some unexpected page flags
+    64  `(U)`  taint requested by userspace application
+   128  `(D)`  kernel died recently, i.e. there was an OOPS or BUG
+   256  `(A)`  an ACPI table was overridden by user
+   512  `(W)`  kernel issued warning
+  1024  `(C)`  staging driver was loaded
+  2048  `(I)`  workaround for bug in platform firmware applied
+  4096  `(O)`  externally-built ("out-of-tree") module was loaded
+  8192  `(E)`  unsigned module was loaded
+ 16384  `(L)`  soft lockup occurred
+ 32768  `(K)`  kernel has been live patched
+ 65536  `(X)`  Auxiliary taint, defined and used by for distros
+131072  `(T)`  The kernel was built with the struct randomization plugin
+======  =====  ==============================================================
+
+See Documentation/admin-guide/tainted-kernels.rst for more information.
+
+Note:
+  writes to this sysctl interface will fail with ``EINVAL`` if the kernel is
+  booted with the command line option ``panic_on_taint=<bitmask>,nousertaint``
+  and any of the ORed together values being written to ``tainted`` match with
+  the bitmask declared on panic_on_taint.
+  See Documentation/admin-guide/kernel-parameters.rst for more details on
+  that particular kernel command line option and its optional
+  ``nousertaint`` switch.
+
+threads-max
+===========
+
+This value controls the maximum number of threads that can be created
+using ``fork()``.
+
+During initialization the kernel sets this value such that even if the
+maximum number of threads is created, the thread structures occupy only
+a part (1/8th) of the available RAM pages.
+
+The minimum value that can be written to ``threads-max`` is 1.
+
+The maximum value that can be written to ``threads-max`` is given by the
+constant ``FUTEX_TID_MASK`` (0x3fffffff).
+
+If a value outside of this range is written to ``threads-max`` an
+``EINVAL`` error occurs.
+
+timer_migration
+===============
+
+When set to a non-zero value, attempt to migrate timers away from idle cpus to
+allow them to remain in low power states longer.
+
+Default is set (1).
+
+traceoff_on_warning
+===================
+
+When set, disables tracing (see Documentation/trace/ftrace.rst) when a
+``WARN()`` is hit.
+
+
+tracepoint_printk
+=================
+
+When tracepoints are sent to printk() (enabled by the ``tp_printk``
+boot parameter), this entry provides runtime control::
+
+    echo 0 > /proc/sys/kernel/tracepoint_printk
+
+will stop tracepoints from being sent to printk(), and::
+
+    echo 1 > /proc/sys/kernel/tracepoint_printk
+
+will send them to printk() again.
+
+This only works if the kernel was booted with ``tp_printk`` enabled.
+
+See Documentation/admin-guide/kernel-parameters.rst and
+Documentation/trace/boottime-trace.rst.
+
+
+unaligned-trap
+==============
+
+On architectures where unaligned accesses cause traps, and where this
+feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW``; currently,
+``arc``, ``parisc`` and ``loongarch``), controls whether unaligned traps
+are caught and emulated (instead of failing).
+
+= ========================================================
+0 Do not emulate unaligned accesses.
+1 Emulate unaligned accesses. This is the default setting.
+= ========================================================
+
+See also `ignore-unaligned-usertrap`_.
+
+
+unknown_nmi_panic
+=================
+
+The value in this file affects behavior of handling NMI. When the
+value is non-zero, unknown NMI is trapped and then panic occurs. At
+that time, kernel debugging information is displayed on console.
+
+NMI switch that most IA32 servers have fires unknown NMI up, for
+example.  If a system hangs up, try pressing the NMI switch.
+
+
+unprivileged_bpf_disabled
+=========================
+
+Writing 1 to this entry will disable unprivileged calls to ``bpf()``;
+once disabled, calling ``bpf()`` without ``CAP_SYS_ADMIN`` or ``CAP_BPF``
+will return ``-EPERM``. Once set to 1, this can't be cleared from the
+running kernel anymore.
+
+Writing 2 to this entry will also disable unprivileged calls to ``bpf()``,
+however, an admin can still change this setting later on, if needed, by
+writing 0 or 1 to this entry.
+
+If ``BPF_UNPRIV_DEFAULT_OFF`` is enabled in the kernel config, then this
+entry will default to 2 instead of 0.
+
+= =============================================================
+0 Unprivileged calls to ``bpf()`` are enabled
+1 Unprivileged calls to ``bpf()`` are disabled without recovery
+2 Unprivileged calls to ``bpf()`` are disabled
+= =============================================================
+
+
+warn_limit
+==========
+
+Number of kernel warnings after which the kernel should panic when
+``panic_on_warn`` is not set. Setting this to 0 disables checking
+the warning count. Setting this to 1 has the same effect as setting
+``panic_on_warn=1``. The default value is 0.
+
+
+watchdog
+========
+
+This parameter can be used to disable or enable the soft lockup detector
+*and* the NMI watchdog (i.e. the hard lockup detector) at the same time.
+
+= ==============================
+0 Disable both lockup detectors.
+1 Enable both lockup detectors.
+= ==============================
+
+The soft lockup detector and the NMI watchdog can also be disabled or
+enabled individually, using the ``soft_watchdog`` and ``nmi_watchdog``
+parameters.
+If the ``watchdog`` parameter is read, for example by executing::
+
+   cat /proc/sys/kernel/watchdog
+
+the output of this command (0 or 1) shows the logical OR of
+``soft_watchdog`` and ``nmi_watchdog``.
+
+
+watchdog_cpumask
+================
+
+This value can be used to control on which cpus the watchdog may run.
+The default cpumask is all possible cores, but if ``NO_HZ_FULL`` is
+enabled in the kernel config, and cores are specified with the
+``nohz_full=`` boot argument, those cores are excluded by default.
+Offline cores can be included in this mask, and if the core is later
+brought online, the watchdog will be started based on the mask value.
+
+Typically this value would only be touched in the ``nohz_full`` case
+to re-enable cores that by default were not running the watchdog,
+if a kernel lockup was suspected on those cores.
+
+The argument value is the standard cpulist format for cpumasks,
+so for example to enable the watchdog on cores 0, 2, 3, and 4 you
+might say::
+
+  echo 0,2-4 > /proc/sys/kernel/watchdog_cpumask
+
+
+watchdog_thresh
+===============
+
+This value can be used to control the frequency of hrtimer and NMI
+events and the soft and hard lockup thresholds. The default threshold
+is 10 seconds.
+
+The softlockup threshold is (``2 * watchdog_thresh``). Setting this
+tunable to zero will disable lockup detection altogether.
diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
new file mode 100644
index 000000000..e586e17fc
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -0,0 +1,587 @@
+================================
+Documentation for /proc/sys/net/
+================================
+
+Copyright
+
+Copyright (c) 1999
+
+	- Terrehon Bowden <terrehon@pacbell.net>
+	- Bodo Bauer <bb@ricochet.net>
+
+Copyright (c) 2000
+
+	- Jorge Nerin <comandante@zaralinux.com>
+
+Copyright (c) 2009
+
+	- Shen Feng <shen@cn.fujitsu.com>
+
+For general info and legal blurb, please look in index.rst.
+
+------------------------------------------------------------------------------
+
+This file contains the documentation for the sysctl files in
+/proc/sys/net
+
+The interface  to  the  networking  parts  of  the  kernel  is  located  in
+/proc/sys/net. The following table shows all possible subdirectories.  You may
+see only some of them, depending on your kernel's configuration.
+
+
+Table : Subdirectories in /proc/sys/net
+
+ ========= =================== = ========== ===================
+ Directory Content               Directory  Content
+ ========= =================== = ========== ===================
+ 802       E802 protocol         mptcp      Multipath TCP
+ appletalk Appletalk protocol    netfilter  Network Filter
+ bridge    Bridging              tipc       TIPC
+ core      General parameter     unix       Unix domain sockets
+ ethernet  Ethernet protocol     vsock      VSOCK sockets
+ ipv4      IP version 4          x25        X.25 protocol
+ ipv6      IP version 6
+ ========= =================== = ========== ===================
+
+1. /proc/sys/net/core - Network core options
+============================================
+
+bpf_jit_enable
+--------------
+
+This enables the BPF Just in Time (JIT) compiler. BPF is a flexible
+and efficient infrastructure allowing to execute bytecode at various
+hook points. It is used in a number of Linux kernel subsystems such
+as networking (e.g. XDP, tc), tracing (e.g. kprobes, uprobes, tracepoints)
+and security (e.g. seccomp). LLVM has a BPF back end that can compile
+restricted C into a sequence of BPF instructions. After program load
+through bpf(2) and passing a verifier in the kernel, a JIT will then
+translate these BPF proglets into native CPU instructions. There are
+two flavors of JITs, the newer eBPF JIT currently supported on:
+
+  - x86_64
+  - x86_32
+  - arm64
+  - arm32
+  - ppc64
+  - ppc32
+  - sparc64
+  - mips64
+  - s390x
+  - riscv64
+  - riscv32
+  - loongarch64
+  - arc
+
+And the older cBPF JIT supported on the following archs:
+
+  - mips
+  - sparc
+
+eBPF JITs are a superset of cBPF JITs, meaning the kernel will
+migrate cBPF instructions into eBPF instructions and then JIT
+compile them transparently. Older cBPF JITs can only translate
+tcpdump filters, seccomp rules, etc, but not mentioned eBPF
+programs loaded through bpf(2).
+
+Values:
+
+	- 0 - disable the JIT (default value)
+	- 1 - enable the JIT
+	- 2 - enable the JIT and ask the compiler to emit traces on kernel log.
+
+bpf_jit_harden
+--------------
+
+This enables hardening for the BPF JIT compiler. Supported are eBPF
+JIT backends. Enabling hardening trades off performance, but can
+mitigate JIT spraying.
+
+Values:
+
+	- 0 - disable JIT hardening (default value)
+	- 1 - enable JIT hardening for unprivileged users only
+	- 2 - enable JIT hardening for all users
+
+where "privileged user" in this context means a process having
+CAP_BPF or CAP_SYS_ADMIN in the root user name space.
+
+bpf_jit_kallsyms
+----------------
+
+When BPF JIT compiler is enabled, then compiled images are unknown
+addresses to the kernel, meaning they neither show up in traces nor
+in /proc/kallsyms. This enables export of these addresses, which can
+be used for debugging/tracing. If bpf_jit_harden is enabled, this
+feature is disabled.
+
+Values :
+
+	- 0 - disable JIT kallsyms export (default value)
+	- 1 - enable JIT kallsyms export for privileged users only
+
+bpf_jit_limit
+-------------
+
+This enforces a global limit for memory allocations to the BPF JIT
+compiler in order to reject unprivileged JIT requests once it has
+been surpassed. bpf_jit_limit contains the value of the global limit
+in bytes.
+
+dev_weight
+----------
+
+The maximum number of packets that kernel can handle on a NAPI interrupt,
+it's a Per-CPU variable. For drivers that support LRO or GRO_HW, a hardware
+aggregated packet is counted as one packet in this context.
+
+Default: 64
+
+dev_weight_rx_bias
+------------------
+
+RPS (e.g. RFS, aRFS) processing is competing with the registered NAPI poll function
+of the driver for the per softirq cycle netdev_budget. This parameter influences
+the proportion of the configured netdev_budget that is spent on RPS based packet
+processing during RX softirq cycles. It is further meant for making current
+dev_weight adaptable for asymmetric CPU needs on RX/TX side of the network stack.
+(see dev_weight_tx_bias) It is effective on a per CPU basis. Determination is based
+on dev_weight and is calculated multiplicative (dev_weight * dev_weight_rx_bias).
+
+Default: 1
+
+dev_weight_tx_bias
+------------------
+
+Scales the maximum number of packets that can be processed during a TX softirq cycle.
+Effective on a per CPU basis. Allows scaling of current dev_weight for asymmetric
+net stack processing needs. Be careful to avoid making TX softirq processing a CPU hog.
+
+Calculation is based on dev_weight (dev_weight * dev_weight_tx_bias).
+
+Default: 1
+
+default_qdisc
+-------------
+
+The default queuing discipline to use for network devices. This allows
+overriding the default of pfifo_fast with an alternative. Since the default
+queuing discipline is created without additional parameters so is best suited
+to queuing disciplines that work well without configuration like stochastic
+fair queue (sfq), CoDel (codel) or fair queue CoDel (fq_codel). Don't use
+queuing disciplines like Hierarchical Token Bucket or Deficit Round Robin
+which require setting up classes and bandwidths. Note that physical multiqueue
+interfaces still use mq as root qdisc, which in turn uses this default for its
+leaves. Virtual devices (like e.g. lo or veth) ignore this setting and instead
+default to noqueue.
+
+Default: pfifo_fast
+
+busy_read
+---------
+
+Low latency busy poll timeout for socket reads. (needs CONFIG_NET_RX_BUSY_POLL)
+Approximate time in us to busy loop waiting for packets on the device queue.
+This sets the default value of the SO_BUSY_POLL socket option.
+Can be set or overridden per socket by setting socket option SO_BUSY_POLL,
+which is the preferred method of enabling. If you need to enable the feature
+globally via sysctl, a value of 50 is recommended.
+
+Will increase power usage.
+
+Default: 0 (off)
+
+busy_poll
+----------------
+Low latency busy poll timeout for poll and select. (needs CONFIG_NET_RX_BUSY_POLL)
+Approximate time in us to busy loop waiting for events.
+Recommended value depends on the number of sockets you poll on.
+For several sockets 50, for several hundreds 100.
+For more than that you probably want to use epoll.
+Note that only sockets with SO_BUSY_POLL set will be busy polled,
+so you want to either selectively set SO_BUSY_POLL on those sockets or set
+sysctl.net.busy_read globally.
+
+Will increase power usage.
+
+Default: 0 (off)
+
+mem_pcpu_rsv
+------------
+
+Per-cpu reserved forward alloc cache size in page units. Default 1MB per CPU.
+
+bypass_prot_mem
+---------------
+
+Skip charging socket buffers to the global per-protocol memory
+accounting controlled by net.ipv4.tcp_mem, net.ipv4.udp_mem, etc.
+
+Default: 0 (off)
+
+rmem_default
+------------
+
+The default setting of the socket receive buffer in bytes.
+
+rmem_max
+--------
+
+The maximum receive socket buffer size in bytes.
+
+Default: 4194304
+
+rps_default_mask
+----------------
+
+The default RPS CPU mask used on newly created network devices. An empty
+mask means RPS disabled by default.
+
+tstamp_allow_data
+-----------------
+Allow processes to receive tx timestamps looped together with the original
+packet contents. If disabled, transmit timestamp requests from unprivileged
+processes are dropped unless socket option SOF_TIMESTAMPING_OPT_TSONLY is set.
+
+Default: 1 (on)
+
+
+wmem_default
+------------
+
+The default setting (in bytes) of the socket send buffer.
+
+wmem_max
+--------
+
+The maximum send socket buffer size in bytes.
+
+Default: 4194304
+
+message_burst and message_cost
+------------------------------
+
+These parameters  are used to limit the warning messages written to the kernel
+log from  the  networking  code.  They  enforce  a  rate  limit  to  make  a
+denial-of-service attack  impossible. A higher message_cost factor, results in
+fewer messages that will be written. Message_burst controls when messages will
+be dropped.  The  default  settings  limit  warning messages to one every five
+seconds.
+
+warnings
+--------
+
+This sysctl is now unused.
+
+This was used to control console messages from the networking stack that
+occur because of problems on the network like duplicate address or bad
+checksums.
+
+These messages are now emitted at KERN_DEBUG and can generally be enabled
+and controlled by the dynamic_debug facility.
+
+netdev_budget
+-------------
+
+Maximum number of packets taken from all interfaces in one polling cycle (NAPI
+poll). In one polling cycle interfaces which are registered to polling are
+probed in a round-robin manner. Also, a polling cycle may not exceed
+netdev_budget_usecs microseconds, even if netdev_budget has not been
+exhausted.
+
+netdev_budget_usecs
+---------------------
+
+Maximum number of microseconds in one NAPI polling cycle. Polling
+will exit when either netdev_budget_usecs have elapsed during the
+poll cycle or the number of packets processed reaches netdev_budget.
+
+netdev_max_backlog
+------------------
+
+Maximum number of packets, queued on the INPUT side, when the interface
+receives packets faster than kernel can process them.
+
+qdisc_max_burst
+------------------
+
+Maximum number of packets that can be temporarily stored before
+reaching qdisc.
+
+Default: 1000
+
+netdev_rss_key
+--------------
+
+RSS (Receive Side Scaling) enabled drivers use a host key that
+is randomly generated.
+Some user space might need to gather its content even if drivers do not
+provide ethtool -x support yet.
+
+::
+
+  myhost:~# cat /proc/sys/net/core/netdev_rss_key
+  84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8: ... (256 bytes total)
+
+File contains all nul bytes if no driver ever called netdev_rss_key_fill()
+function.
+
+Note:
+  /proc/sys/net/core/netdev_rss_key contains 256 bytes of key,
+  but many drivers only use 40 or 52 bytes of it.
+
+::
+
+  myhost:~# ethtool -x eth0
+  RX flow hash indirection table for eth0 with 8 RX ring(s):
+      0:    0     1     2     3     4     5     6     7
+  RSS hash key:
+  84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89
+
+netdev_tstamp_prequeue
+----------------------
+
+If set to 0, RX packet timestamps can be sampled after RPS processing, when
+the target CPU processes packets. It might give some delay on timestamps, but
+permit to distribute the load on several cpus.
+
+If set to 1 (default), timestamps are sampled as soon as possible, before
+queueing.
+
+netdev_unregister_timeout_secs
+------------------------------
+
+Unregister network device timeout in seconds.
+This option controls the timeout (in seconds) used to issue a warning while
+waiting for a network device refcount to drop to 0 during device
+unregistration. A lower value may be useful during bisection to detect
+a leaked reference faster. A larger value may be useful to prevent false
+warnings on slow/loaded systems.
+Default value is 10, minimum 1, maximum 3600.
+
+skb_defer_max
+-------------
+
+Max size (in skbs) of the per-cpu list of skbs being freed
+by the cpu which allocated them.
+
+Default: 128
+
+optmem_max
+----------
+
+Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence
+of struct cmsghdr structures with appended data. TCP tx zerocopy also uses
+optmem_max as a limit for its internal structures.
+
+Default : 128 KB
+
+fb_tunnels_only_for_init_net
+----------------------------
+
+Controls if fallback tunnels (like tunl0, gre0, gretap0, erspan0,
+sit0, ip6tnl0, ip6gre0) are automatically created. There are 3 possibilities
+(a) value = 0; respective fallback tunnels are created when module is
+loaded in every net namespaces (backward compatible behavior).
+(b) value = 1; [kcmd value: initns] respective fallback tunnels are
+created only in init net namespace and every other net namespace will
+not have them.
+(c) value = 2; [kcmd value: none] fallback tunnels are not created
+when a module is loaded in any of the net namespace. Setting value to
+"2" is pointless after boot if these modules are built-in, so there is
+a kernel command-line option that can change this default. Please refer to
+Documentation/admin-guide/kernel-parameters.txt for additional details.
+
+Not creating fallback tunnels gives control to userspace to create
+whatever is needed only and avoid creating devices which are redundant.
+
+Default : 0  (for compatibility reasons)
+
+devconf_inherit_init_net
+------------------------
+
+Controls if a new network namespace should inherit all current
+settings under /proc/sys/net/{ipv4,ipv6}/conf/{all,default}/. By
+default, we keep the current behavior: for IPv4 we inherit all current
+settings from init_net and for IPv6 we reset all settings to default.
+
+If set to 1, both IPv4 and IPv6 settings are forced to inherit from
+current ones in init_net. If set to 2, both IPv4 and IPv6 settings are
+forced to reset to their default values. If set to 3, both IPv4 and IPv6
+settings are forced to inherit from current ones in the netns where this
+new netns has been created.
+
+Default : 0  (for compatibility reasons)
+
+txrehash
+--------
+
+Controls default hash rethink behaviour on socket when SO_TXREHASH option is set
+to SOCK_TXREHASH_DEFAULT (i. e. not overridden by setsockopt).
+
+If set to 1 (default), hash rethink is performed on listening socket.
+If set to 0, hash rethink is not performed.
+
+txq_reselection_ms
+------------------
+
+Controls how often (in ms) a busy connected flow can select another tx queue.
+
+A resection is desirable when/if user thread has migrated and XPS
+would select a different queue. Same can occur without XPS
+if the flow hash has changed.
+
+But switching txq can introduce reorders, especially if the
+old queue is under high pressure. Modern TCP stacks deal
+well with reorders if they happen not too often.
+
+To disable this feature, set the value to 0.
+
+Default : 1000
+
+gro_normal_batch
+----------------
+
+Maximum number of the segments to batch up on output of GRO. When a packet
+exits GRO, either as a coalesced superframe or as an original packet which
+GRO has decided not to coalesce, it is placed on a per-NAPI list. This
+list is then passed to the stack when the number of segments reaches the
+gro_normal_batch limit.
+
+high_order_alloc_disable
+------------------------
+
+By default the allocator for page frags tries to use high order pages (order-3
+on x86). While the default behavior gives good results in most cases, some users
+might have hit a contention in page allocations/freeing. This was especially
+true on older kernels (< 5.14) when high-order pages were not stored on per-cpu
+lists. This allows to opt-in for order-0 allocation instead but is now mostly of
+historical importance.
+
+Default: 0
+
+2. /proc/sys/net/unix - Parameters for Unix domain sockets
+----------------------------------------------------------
+
+There is only one file in this directory.
+unix_dgram_qlen limits the max number of datagrams queued in Unix domain
+socket's buffer. It will not take effect unless PF_UNIX flag is specified.
+
+
+3. /proc/sys/net/ipv4 - IPV4 settings
+-------------------------------------
+Please see: Documentation/networking/ip-sysctl.rst and
+Documentation/admin-guide/sysctl/net.rst for descriptions of these entries.
+
+
+4. TIPC
+-------
+
+tipc_rmem
+---------
+
+The TIPC protocol now has a tunable for the receive memory, similar to the
+tcp_rmem - i.e. a vector of 3 INTEGERs: (min, default, max)
+
+::
+
+    # cat /proc/sys/net/tipc/tipc_rmem
+    4252725 34021800        68043600
+    #
+
+The max value is set to CONN_OVERLOAD_LIMIT, and the default and min values
+are scaled (shifted) versions of that same value.  Note that the min value
+is not at this point in time used in any meaningful way, but the triplet is
+preserved in order to be consistent with things like tcp_rmem.
+
+named_timeout
+-------------
+
+TIPC name table updates are distributed asynchronously in a cluster, without
+any form of transaction handling. This means that different race scenarios are
+possible. One such is that a name withdrawal sent out by one node and received
+by another node may arrive after a second, overlapping name publication already
+has been accepted from a third node, although the conflicting updates
+originally may have been issued in the correct sequential order.
+If named_timeout is nonzero, failed topology updates will be placed on a defer
+queue until another event arrives that clears the error, or until the timeout
+expires. Value is in milliseconds.
+
+6. /proc/sys/net/vsock - VSOCK sockets
+--------------------------------------
+
+VSOCK sockets (AF_VSOCK) provide communication between virtual machines and
+their hosts. The behavior of VSOCK sockets in a network namespace is determined
+by the namespace's mode (``global`` or ``local``), which controls how CIDs
+(Context IDs) are allocated and how sockets interact across namespaces.
+
+ns_mode
+-------
+
+Read-only. Reports the current namespace's mode, set at namespace creation
+and immutable thereafter.
+
+Values:
+
+	- ``global`` - the namespace shares system-wide CID allocation and
+	  its sockets can reach any VM or socket in any global namespace.
+	  Sockets in this namespace cannot reach sockets in local
+	  namespaces.
+	- ``local`` - the namespace has private CID allocation and its
+	  sockets can only connect to VMs or sockets within the same
+	  namespace.
+
+The init_net mode is always ``global``.
+
+child_ns_mode
+-------------
+
+Controls what mode newly created child namespaces will inherit. At namespace
+creation, ``ns_mode`` is inherited from the parent's ``child_ns_mode``. The
+initial value matches the namespace's own ``ns_mode``.
+
+Values:
+
+	- ``global`` - child namespaces will share system-wide CID allocation
+	  and their sockets will be able to reach any VM or socket in any
+	  global namespace.
+	- ``local`` - child namespaces will have private CID allocation and
+	  their sockets will only be able to connect within their own
+	  namespace.
+
+The first write to ``child_ns_mode`` locks its value. Subsequent writes of the
+same value succeed, but writing a different value returns ``-EBUSY``.
+
+Changing ``child_ns_mode`` only affects namespaces created after the change;
+it does not modify the current namespace or any existing children.
+
+A namespace with ``ns_mode`` set to ``local`` cannot change
+``child_ns_mode`` to ``global`` (returns ``-EPERM``).
+
+g2h_fallback
+------------
+
+Controls whether connections to CIDs not owned by the host-to-guest (H2G)
+transport automatically fall back to the guest-to-host (G2H) transport.
+
+When enabled, if a connect targets a CID that the H2G transport (e.g.
+vhost-vsock) does not serve, or if no H2G transport is loaded at all, the
+connection is routed via the G2H transport (e.g. virtio-vsock) instead. This
+allows a host running both nested VMs (via vhost-vsock) and sibling VMs
+reachable through the hypervisor (e.g. Nitro Enclaves) to address both using
+a single CID space, without requiring applications to set
+``VMADDR_FLAG_TO_HOST``.
+
+When the fallback is taken, ``VMADDR_FLAG_TO_HOST`` is automatically set on
+the remote address so that userspace can determine the path via
+``getpeername()``.
+
+Note: With this sysctl enabled, user space that attempts to talk to a guest
+CID which is not implemented by the H2G transport will create host vsock
+traffic. Environments that rely on H2G-only isolation should set it to 0.
+
+Values:
+
+	- 0 - Connections to CIDs <= 2 or with VMADDR_FLAG_TO_HOST use G2H;
+	  all others use H2G (or fail with ENODEV if H2G is not loaded).
+	- 1 - Connections to CIDs not owned by H2G fall back to G2H. (default)
diff --git a/Documentation/admin-guide/sysctl/sunrpc.rst b/Documentation/admin-guide/sysctl/sunrpc.rst
new file mode 100644
index 000000000..09780a682
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/sunrpc.rst
@@ -0,0 +1,25 @@
+===================================
+Documentation for /proc/sys/sunrpc/
+===================================
+
+kernel version 2.2.10
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+For general info and legal blurb, please look in index.rst.
+
+------------------------------------------------------------------------------
+
+This file contains the documentation for the sysctl files in
+/proc/sys/sunrpc and is valid for Linux kernel version 2.2.
+
+The files in this directory can be used to (re)set the debug
+flags of the SUN Remote Procedure Call (RPC) subsystem in
+the Linux kernel. This stuff is used for NFS, KNFSD and
+maybe a few other things as well.
+
+The files in there are used to control the debugging flags:
+rpc_debug, nfs_debug, nfsd_debug and nlm_debug.
+
+These flags are for kernel hackers only. You should read the
+source code in net/sunrpc/ for more information.
diff --git a/Documentation/admin-guide/sysctl/user.rst b/Documentation/admin-guide/sysctl/user.rst
new file mode 100644
index 000000000..c45824589
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/user.rst
@@ -0,0 +1,84 @@
+=================================
+Documentation for /proc/sys/user/
+=================================
+
+kernel version 4.9.0
+
+Copyright (c) 2016		Eric Biederman <ebiederm@xmission.com>
+
+------------------------------------------------------------------------------
+
+This file contains the documentation for the sysctl files in
+/proc/sys/user.
+
+The files in this directory can be used to override the default
+limits on the number of namespaces and other objects that have
+per user per user namespace limits.
+
+The primary purpose of these limits is to stop programs that
+malfunction and attempt to create a ridiculous number of objects,
+before the malfunction becomes a system wide problem.  It is the
+intention that the defaults of these limits are set high enough that
+no program in normal operation should run into these limits.
+
+The creation of per user per user namespace objects are charged to
+the user in the user namespace who created the object and
+verified to be below the per user limit in that user namespace.
+
+The creation of objects is also charged to all of the users
+who created user namespaces the creation of the object happens
+in (user namespaces can be nested) and verified to be below the per user
+limits in the user namespaces of those users.
+
+This recursive counting of created objects ensures that creating a
+user namespace does not allow a user to escape their current limits.
+
+Currently, these files are in /proc/sys/user:
+
+max_cgroup_namespaces
+=====================
+
+  The maximum number of cgroup namespaces that any user in the current
+  user namespace may create.
+
+max_ipc_namespaces
+==================
+
+  The maximum number of ipc namespaces that any user in the current
+  user namespace may create.
+
+max_mnt_namespaces
+==================
+
+  The maximum number of mount namespaces that any user in the current
+  user namespace may create.
+
+max_net_namespaces
+==================
+
+  The maximum number of network namespaces that any user in the
+  current user namespace may create.
+
+max_pid_namespaces
+==================
+
+  The maximum number of pid namespaces that any user in the current
+  user namespace may create.
+
+max_time_namespaces
+===================
+
+  The maximum number of time namespaces that any user in the current
+  user namespace may create.
+
+max_user_namespaces
+===================
+
+  The maximum number of user namespaces that any user in the current
+  user namespace may create.
+
+max_uts_namespaces
+==================
+
+  The maximum number of user namespaces that any user in the current
+  user namespace may create.
diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst
new file mode 100644
index 000000000..5b318d17a
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/vm.rst
@@ -0,0 +1,1230 @@
+===============================
+Documentation for /proc/sys/vm/
+===============================
+
+kernel version 2.6.29
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+Copyright (c) 2008         Peter W. Morreale <pmorreale@novell.com>
+
+For general info and legal blurb, please look in index.rst.
+
+------------------------------------------------------------------------------
+
+This file contains the documentation for the sysctl files in
+/proc/sys/vm and is valid for Linux kernel version 2.6.29.
+
+The files in this directory can be used to tune the operation
+of the virtual memory (VM) subsystem of the Linux kernel and
+the writeout of dirty data to disk.
+
+Currently, these files are in /proc/sys/vm:
+
+- admin_reserve_kbytes
+- compact_memory
+- compaction_proactiveness
+- compact_unevictable_allowed
+- defrag_mode
+- dirty_background_bytes
+- dirty_background_ratio
+- dirty_bytes
+- dirty_expire_centisecs
+- dirty_ratio
+- dirtytime_expire_seconds
+- dirty_writeback_centisecs
+- drop_caches
+- enable_soft_offline
+- extfrag_threshold
+- highmem_is_dirtyable
+- hugetlb_shm_group
+- legacy_va_layout
+- lowmem_reserve_ratio
+- max_map_count
+- mem_profiling         (only if CONFIG_MEM_ALLOC_PROFILING=y)
+- memory_failure_early_kill
+- memory_failure_recovery
+- min_free_kbytes
+- min_slab_ratio
+- min_unmapped_ratio
+- mmap_min_addr
+- mmap_rnd_bits
+- mmap_rnd_compat_bits
+- movable_gigantic_pages
+- nr_hugepages
+- nr_hugepages_mempolicy
+- nr_overcommit_hugepages
+- nr_trim_pages         (only if CONFIG_MMU=n)
+- numa_zonelist_order
+- oom_dump_tasks
+- oom_kill_allocating_task
+- overcommit_kbytes
+- overcommit_memory
+- overcommit_ratio
+- page-cluster
+- page_lock_unfairness
+- panic_on_oom
+- panic_on_unrecoverable_memory_failure
+- percpu_pagelist_high_fraction
+- stat_interval
+- stat_refresh
+- numa_stat
+- swappiness
+- unprivileged_userfaultfd
+- user_reserve_kbytes
+- vfs_cache_pressure
+- vfs_cache_pressure_denom
+- watermark_boost_factor
+- watermark_scale_factor
+- zone_reclaim_mode
+
+
+admin_reserve_kbytes
+====================
+
+The amount of free memory in the system that should be reserved for users
+with the capability cap_sys_admin.
+
+admin_reserve_kbytes defaults to min(3% of free pages, 8MB)
+
+That should provide enough for the admin to log in and kill a process,
+if necessary, under the default overcommit 'guess' mode.
+
+Systems running under overcommit 'never' should increase this to account
+for the full Virtual Memory Size of programs used to recover. Otherwise,
+root may not be able to log in to recover the system.
+
+How do you calculate a minimum useful reserve?
+
+sshd or login + bash (or some other shell) + top (or ps, kill, etc.)
+
+For overcommit 'guess', we can sum resident set sizes (RSS).
+On x86_64 this is about 8MB.
+
+For overcommit 'never', we can take the max of their virtual sizes (VSZ)
+and add the sum of their RSS.
+On x86_64 this is about 128MB.
+
+Changing this takes effect whenever an application requests memory.
+
+
+compact_memory
+==============
+
+Available only when CONFIG_COMPACTION is set. When 1 is written to the file,
+all zones are compacted such that free memory is available in contiguous
+blocks where possible. This can be important for example in the allocation of
+huge pages although processes will also directly compact memory as required.
+
+compaction_proactiveness
+========================
+
+This tunable takes a value in the range [0, 100] with a default value of
+20. This tunable determines how aggressively compaction is done in the
+background. Write of a non zero value to this tunable will immediately
+trigger the proactive compaction. Setting it to 0 disables proactive compaction.
+
+Note that compaction has a non-trivial system-wide impact as pages
+belonging to different processes are moved around, which could also lead
+to latency spikes in unsuspecting applications. The kernel employs
+various heuristics to avoid wasting CPU cycles if it detects that
+proactive compaction is not being effective.
+
+Setting the value above 80 will, in addition to lowering the acceptable level
+of fragmentation, make the compaction code more sensitive to increases in
+fragmentation, i.e. compaction will trigger more often, but reduce
+fragmentation by a smaller amount.
+This makes the fragmentation level more stable over time.
+
+Be careful when setting it to extreme values like 100, as that may
+cause excessive background compaction activity.
+
+compact_unevictable_allowed
+===========================
+
+Available only when CONFIG_COMPACTION is set. When set to 1, compaction is
+allowed to examine the unevictable lru (mlocked pages) for pages to compact.
+This should be used on systems where stalls for minor page faults are an
+acceptable trade for large contiguous free memory.  Set to 0 to prevent
+compaction from moving pages that are unevictable.  Default value is 1.
+On CONFIG_PREEMPT_RT the default value is 0 in order to avoid a page fault, due
+to compaction, which would block the task from becoming active until the fault
+is resolved.
+
+defrag_mode
+===========
+
+When set to 1, the page allocator tries harder to avoid fragmentation
+and maintain the ability to produce huge pages / higher-order pages.
+
+It is recommended to enable this right after boot, as fragmentation,
+once it occurred, can be long-lasting or even permanent.
+
+dirty_background_bytes
+======================
+
+Contains the amount of dirty memory at which the background kernel
+flusher threads will start writeback.
+
+Note:
+  dirty_background_bytes is the counterpart of dirty_background_ratio. Only
+  one of them may be specified at a time. When one sysctl is written it is
+  immediately taken into account to evaluate the dirty memory limits and the
+  other appears as 0 when read.
+
+
+dirty_background_ratio
+======================
+
+Contains, as a percentage of total available memory that contains free pages
+and reclaimable pages, the number of pages at which the background kernel
+flusher threads will start writing out dirty data.
+
+The total available memory is not equal to total system memory.
+
+
+dirty_bytes
+===========
+
+Contains the amount of dirty memory at which a process generating disk writes
+will itself start writeback.
+
+Note: dirty_bytes is the counterpart of dirty_ratio. Only one of them may be
+specified at a time. When one sysctl is written it is immediately taken into
+account to evaluate the dirty memory limits and the other appears as 0 when
+read.
+
+Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any
+value lower than this limit will be ignored and the old configuration will be
+retained.
+
+
+dirty_expire_centisecs
+======================
+
+This tunable is used to define when dirty data is old enough to be eligible
+for writeout by the kernel flusher threads.  It is expressed in 100'ths
+of a second.  Data which has been dirty in-memory for longer than this
+interval will be written out next time a flusher thread wakes up.
+
+
+dirty_ratio
+===========
+
+Contains, as a percentage of total available memory that contains free pages
+and reclaimable pages, the number of pages at which a process which is
+generating disk writes will itself start writing out dirty data.
+
+The total available memory is not equal to total system memory.
+
+
+dirtytime_expire_seconds
+========================
+
+When a lazytime inode is constantly having its pages dirtied, the inode with
+an updated timestamp will never get chance to be written out.  And, if the
+only thing that has happened on the file system is a dirtytime inode caused
+by an atime update, a worker will be scheduled to make sure that inode
+eventually gets pushed out to disk.  This tunable is used to define when dirty
+inode is old enough to be eligible for writeback by the kernel flusher threads.
+And, it is also used as the interval to wakeup dirtytime_writeback thread.
+
+Setting this to zero disables periodic dirtytime writeback.
+
+
+dirty_writeback_centisecs
+=========================
+
+The kernel flusher threads will periodically wake up and write `old` data
+out to disk.  This tunable expresses the interval between those wakeups, in
+100'ths of a second.
+
+Setting this to zero disables periodic writeback altogether.
+
+
+drop_caches
+===========
+
+Writing to this will cause the kernel to drop clean caches, as well as
+reclaimable slab objects like dentries and inodes.  Once dropped, their
+memory becomes free.
+
+To free pagecache::
+
+	echo 1 > /proc/sys/vm/drop_caches
+
+To free reclaimable slab objects (includes dentries and inodes)::
+
+	echo 2 > /proc/sys/vm/drop_caches
+
+To free slab objects and pagecache::
+
+	echo 3 > /proc/sys/vm/drop_caches
+
+This is a non-destructive operation and will not free any dirty objects.
+To increase the number of objects freed by this operation, the user may run
+`sync` prior to writing to /proc/sys/vm/drop_caches.  This will minimize the
+number of dirty objects on the system and create more candidates to be
+dropped.
+
+This file is not a means to control the growth of the various kernel caches
+(inodes, dentries, pagecache, etc...)  These objects are automatically
+reclaimed by the kernel when memory is needed elsewhere on the system.
+
+Use of this file can cause performance problems.  Since it discards cached
+objects, it may cost a significant amount of I/O and CPU to recreate the
+dropped objects, especially if they were under heavy use.  Because of this,
+use outside of a testing or debugging environment is not recommended.
+
+You may see informational messages in your kernel log when this file is
+used::
+
+	cat (1234): drop_caches: 3
+
+These are informational only.  They do not mean that anything is wrong
+with your system.  To disable them, echo 4 (bit 2) into drop_caches.
+
+enable_soft_offline
+===================
+Correctable memory errors are very common on servers. Soft-offline is kernel's
+solution for memory pages having (excessive) corrected memory errors.
+
+For different types of page, soft-offline has different behaviors / costs.
+
+- For a raw error page, soft-offline migrates the in-use page's content to
+  a new raw page.
+
+- For a page that is part of a transparent hugepage, soft-offline splits the
+  transparent hugepage into raw pages, then migrates only the raw error page.
+  As a result, user is transparently backed by 1 less hugepage, impacting
+  memory access performance.
+
+- For a page that is part of a HugeTLB hugepage, soft-offline first migrates
+  the entire HugeTLB hugepage, during which a free hugepage will be consumed
+  as migration target.  Then the original hugepage is dissolved into raw
+  pages without compensation, reducing the capacity of the HugeTLB pool by 1.
+
+It is user's call to choose between reliability (staying away from fragile
+physical memory) vs performance / capacity implications in transparent and
+HugeTLB cases.
+
+For all architectures, enable_soft_offline controls whether to soft offline
+memory pages.  When set to 1, kernel attempts to soft offline the pages
+whenever it thinks needed.  When set to 0, kernel returns EOPNOTSUPP to
+the request to soft offline the pages.  Its default value is 1.
+
+It is worth mentioning that after setting enable_soft_offline to 0, the
+following requests to soft offline pages will not be performed:
+
+- Request to soft offline pages from RAS Correctable Errors Collector.
+
+- On ARM, the request to soft offline pages from GHES driver.
+
+- On PARISC, the request to soft offline pages from Page Deallocation Table.
+
+extfrag_threshold
+=================
+
+This parameter affects whether the kernel will compact memory or direct
+reclaim to satisfy a high-order allocation. The extfrag/extfrag_index file in
+debugfs shows what the fragmentation index for each order is in each zone in
+the system. Values tending towards 0 imply allocations would fail due to lack
+of memory, values towards 1000 imply failures are due to fragmentation and -1
+implies that the allocation will succeed as long as watermarks are met.
+
+The kernel will not compact memory in a zone if the
+fragmentation index is <= extfrag_threshold. The default value is 500.
+
+
+highmem_is_dirtyable
+====================
+
+Available only for systems with CONFIG_HIGHMEM enabled (32b systems).
+
+This parameter controls whether the high memory is considered for dirty
+writers throttling.  This is not the case by default which means that
+only the amount of memory directly visible/usable by the kernel can
+be dirtied. As a result, on systems with a large amount of memory and
+lowmem basically depleted writers might be throttled too early and
+streaming writes can get very slow.
+
+Changing the value to non zero would allow more memory to be dirtied
+and thus allow writers to write more data which can be flushed to the
+storage more effectively. Note this also comes with a risk of pre-mature
+OOM killer because some writers (e.g. direct block device writes) can
+only use the low memory and they can fill it up with dirty data without
+any throttling.
+
+
+hugetlb_shm_group
+=================
+
+hugetlb_shm_group contains group id that is allowed to create SysV
+shared memory segment using hugetlb page.
+
+
+legacy_va_layout
+================
+
+If non-zero, this sysctl disables the new 32-bit mmap layout - the kernel
+will use the legacy (2.4) layout for all processes.
+
+
+lowmem_reserve_ratio
+====================
+
+For some specialised workloads on highmem machines it is dangerous for
+the kernel to allow process memory to be allocated from the "lowmem"
+zone.  This is because that memory could then be pinned via the mlock()
+system call, or by unavailability of swapspace.
+
+And on large highmem machines this lack of reclaimable lowmem memory
+can be fatal.
+
+So the Linux page allocator has a mechanism which prevents allocations
+which *could* use highmem from using too much lowmem.  This means that
+a certain amount of lowmem is defended from the possibility of being
+captured into pinned user memory.
+
+(The same argument applies to the old 16 megabyte ISA DMA region.  This
+mechanism will also defend that region from allocations which could use
+highmem or lowmem).
+
+The `lowmem_reserve_ratio` tunable determines how aggressive the kernel is
+in defending these lower zones.
+
+If you have a machine which uses highmem or ISA DMA and your
+applications are using mlock(), or if you are running with no swap then
+you probably should change the lowmem_reserve_ratio setting.
+
+The lowmem_reserve_ratio is an array. You can see them by reading this file::
+
+	% cat /proc/sys/vm/lowmem_reserve_ratio
+	256     256     32
+
+But, these values are not used directly. The kernel calculates # of protection
+pages for each zones from them. These are shown as array of protection pages
+in /proc/zoneinfo like the following. (This is an example of x86-64 box).
+Each zone has an array of protection pages like this::
+
+  Node 0, zone      DMA
+    pages free     1355
+          min      3
+          low      3
+          high     4
+	:
+	:
+      numa_other   0
+          protection: (0, 2004, 2004, 2004)
+	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    pagesets
+      cpu: 0 pcp: 0
+          :
+
+These protections are added to score to judge whether this zone should be used
+for page allocation or should be reclaimed.
+
+In this example, if normal pages (index=2) are required to this DMA zone and
+watermark[WMARK_HIGH] is used for watermark, the kernel judges this zone should
+not be used because pages_free(1355) is smaller than watermark + protection[2]
+(4 + 2004 = 2008). If this protection value is 0, this zone would be used for
+normal page requirement. If requirement is DMA zone(index=0), protection[0]
+(=0) is used.
+
+zone[i]'s protection[j] is calculated by following expression::
+
+  (i < j):
+    zone[i]->protection[j]
+    = (total sums of managed_pages from zone[i+1] to zone[j] on the node)
+      / lowmem_reserve_ratio[i];
+  (i = j):
+     (should not be protected. = 0;
+  (i > j):
+     (not necessary, but looks 0)
+
+The default values of lowmem_reserve_ratio[i] are
+
+    === ====================================
+    256 (if zone[i] means DMA or DMA32 zone)
+    32  (others)
+    === ====================================
+
+As above expression, they are reciprocal number of ratio.
+256 means 1/256. # of protection pages becomes about "0.39%" of total managed
+pages of higher zones on the node.
+
+If you would like to protect more pages, smaller values are effective.
+The minimum value is 1 (1/1 -> 100%). The value less than 1 completely
+disables protection of the pages.
+
+
+max_map_count
+=============
+
+This file contains the maximum number of memory map areas a process
+may have. Memory map areas are used as a side-effect of calling
+malloc, directly by mmap, mprotect, and madvise, and also when loading
+shared libraries.
+
+While most applications need less than a thousand maps, certain
+programs, particularly malloc debuggers, may consume lots of them,
+e.g., up to one or two maps per allocation.
+
+The default value is 65530.
+
+
+mem_profiling
+==============
+
+Enable memory profiling (when CONFIG_MEM_ALLOC_PROFILING=y)
+
+1: Enable memory profiling.
+
+0: Disable memory profiling.
+
+Enabling memory profiling introduces a small performance overhead for all
+memory allocations.
+
+The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT.
+
+When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, this control is read-only to avoid
+warnings produced by allocations made while profiling is disabled and freed
+when it's enabled.
+
+
+memory_failure_early_kill
+=========================
+
+Control how to kill processes when uncorrected memory error (typically
+a 2bit error in a memory module) is detected in the background by hardware
+that cannot be handled by the kernel. In some cases (like the page
+still having a valid copy on disk) the kernel will handle the failure
+transparently without affecting any applications. But if there is
+no other up-to-date copy of the data it will kill to prevent any data
+corruptions from propagating.
+
+1: Kill all processes that have the corrupted and not reloadable page mapped
+as soon as the corruption is detected.  Note this is not supported
+for a few types of pages, like kernel internally allocated data or
+the swap cache, but works for the majority of user pages.
+
+0: Only unmap the corrupted page from all processes and only kill a process
+who tries to access it.
+
+The kill is done using a catchable SIGBUS with BUS_MCEERR_AO, so processes can
+handle this if they want to.
+
+This is only active on architectures/platforms with advanced machine
+check handling and depends on the hardware capabilities.
+
+Applications can override this setting individually with the PR_MCE_KILL prctl
+
+
+memory_failure_recovery
+=======================
+
+Enable memory failure recovery (when supported by the platform)
+
+1: Attempt recovery.
+
+0: Always panic on a memory failure.
+
+
+min_free_kbytes
+===============
+
+This is used to force the Linux VM to keep a minimum number
+of kilobytes free.  The VM uses this number to compute a
+watermark[WMARK_MIN] value for each lowmem zone in the system.
+Each lowmem zone gets a number of reserved free pages based
+proportionally on its size.
+
+Some minimal amount of memory is needed to satisfy PF_MEMALLOC
+allocations; if you set this to lower than 1024KB, your system will
+become subtly broken, and prone to deadlock under high loads.
+
+Setting this too high will OOM your machine instantly.
+
+
+min_slab_ratio
+==============
+
+This is available only on NUMA kernels.
+
+A percentage of the total pages in each zone.  On Zone reclaim
+(fallback from the local zone occurs) slabs will be reclaimed if more
+than this percentage of pages in a zone are reclaimable slab pages.
+This insures that the slab growth stays under control even in NUMA
+systems that rarely perform global reclaim.
+
+The default is 5 percent.
+
+Note that slab reclaim is triggered in a per zone / node fashion.
+The process of reclaiming slab memory is currently not node specific
+and may not be fast.
+
+
+min_unmapped_ratio
+==================
+
+This is available only on NUMA kernels.
+
+This is a percentage of the total pages in each zone. Zone reclaim will
+only occur if more than this percentage of pages are in a state that
+zone_reclaim_mode allows to be reclaimed.
+
+If zone_reclaim_mode has the value 4 OR'd, then the percentage is compared
+against all file-backed unmapped pages including swapcache pages and tmpfs
+files. Otherwise, only unmapped pages backed by normal files but not tmpfs
+files and similar are considered.
+
+The default is 1 percent.
+
+
+mmap_min_addr
+=============
+
+This file indicates the amount of address space  which a user process will
+be restricted from mmapping.  Since kernel null dereference bugs could
+accidentally operate based on the information in the first couple of pages
+of memory userspace processes should not be allowed to write to them.  By
+default this value is set to 0 and no protections will be enforced by the
+security module.  Setting this value to something like 64k will allow the
+vast majority of applications to work correctly and provide defense in depth
+against future potential kernel bugs.
+
+
+mmap_rnd_bits
+=============
+
+This value can be used to select the number of bits to use to
+determine the random offset to the base address of vma regions
+resulting from mmap allocations on architectures which support
+tuning address space randomization.  This value will be bounded
+by the architecture's minimum and maximum supported values.
+
+This value can be changed after boot using the
+/proc/sys/vm/mmap_rnd_bits tunable
+
+
+mmap_rnd_compat_bits
+====================
+
+This value can be used to select the number of bits to use to
+determine the random offset to the base address of vma regions
+resulting from mmap allocations for applications run in
+compatibility mode on architectures which support tuning address
+space randomization.  This value will be bounded by the
+architecture's minimum and maximum supported values.
+
+This value can be changed after boot using the
+/proc/sys/vm/mmap_rnd_compat_bits tunable
+
+
+movable_gigantic_pages
+======================
+
+This parameter controls whether gigantic pages may be allocated from
+ZONE_MOVABLE. If set to non-zero, gigantic pages can be allocated
+from ZONE_MOVABLE. ZONE_MOVABLE memory may be created via the kernel
+boot parameter `kernelcore` or via memory hotplug as discussed in
+Documentation/admin-guide/mm/memory-hotplug.rst.
+
+Support may depend on specific architecture.
+
+Note that using ZONE_MOVABLE gigantic pages make memory hotremove unreliable.
+
+Memory hot-remove operations will block indefinitely until the admin reserves
+sufficient gigantic pages to service migration requests associated with the
+memory offlining process.  As HugeTLB gigantic page reservation is a manual
+process (via `nodeN/hugepages/.../nr_hugepages` interfaces) this may not be
+obvious when just attempting to offline a block of memory.
+
+Additionally, as multiple gigantic pages may be reserved on a single block,
+it may appear that gigantic pages are available for migration when in reality
+they are in the process of being removed. For example if `memoryN` contains
+two gigantic pages, one reserved and one allocated, and an admin attempts to
+offline that block, this operations may hang indefinitely unless another
+reserved gigantic page is available on another block `memoryM`.
+
+
+nr_hugepages
+============
+
+Change the minimum size of the hugepage pool.
+
+See Documentation/admin-guide/mm/hugetlbpage.rst
+
+
+hugetlb_optimize_vmemmap
+========================
+
+This knob is not available when the size of 'struct page' (a structure defined
+in include/linux/mm_types.h) is not power of two (an unusual system config could
+result in this).
+
+Enable (set to 1) or disable (set to 0) HugeTLB Vmemmap Optimization (HVO).
+
+Once enabled, the vmemmap pages of subsequent allocation of HugeTLB pages from
+buddy allocator will be optimized (7 pages per 2MB HugeTLB page and 4095 pages
+per 1GB HugeTLB page), whereas already allocated HugeTLB pages will not be
+optimized.  When those optimized HugeTLB pages are freed from the HugeTLB pool
+to the buddy allocator, the vmemmap pages representing that range needs to be
+remapped again and the vmemmap pages discarded earlier need to be rellocated
+again.  If your use case is that HugeTLB pages are allocated 'on the fly' (e.g.
+never explicitly allocating HugeTLB pages with 'nr_hugepages' but only set
+'nr_overcommit_hugepages', those overcommitted HugeTLB pages are allocated 'on
+the fly') instead of being pulled from the HugeTLB pool, you should weigh the
+benefits of memory savings against the more overhead (~2x slower than before)
+of allocation or freeing HugeTLB pages between the HugeTLB pool and the buddy
+allocator.  Another behavior to note is that if the system is under heavy memory
+pressure, it could prevent the user from freeing HugeTLB pages from the HugeTLB
+pool to the buddy allocator since the allocation of vmemmap pages could be
+failed, you have to retry later if your system encounter this situation.
+
+Once disabled, the vmemmap pages of subsequent allocation of HugeTLB pages from
+buddy allocator will not be optimized meaning the extra overhead at allocation
+time from buddy allocator disappears, whereas already optimized HugeTLB pages
+will not be affected.  If you want to make sure there are no optimized HugeTLB
+pages, you can set "nr_hugepages" to 0 first and then disable this.  Note that
+writing 0 to nr_hugepages will make any "in use" HugeTLB pages become surplus
+pages.  So, those surplus pages are still optimized until they are no longer
+in use.  You would need to wait for those surplus pages to be released before
+there are no optimized pages in the system.
+
+
+nr_hugepages_mempolicy
+======================
+
+Change the size of the hugepage pool at run-time on a specific
+set of NUMA nodes.
+
+See Documentation/admin-guide/mm/hugetlbpage.rst
+
+
+nr_overcommit_hugepages
+=======================
+
+Change the maximum size of the hugepage pool. The maximum is
+nr_hugepages + nr_overcommit_hugepages.
+
+See Documentation/admin-guide/mm/hugetlbpage.rst
+
+
+nr_trim_pages
+=============
+
+This is available only on NOMMU kernels.
+
+This value adjusts the excess page trimming behaviour of power-of-2 aligned
+NOMMU mmap allocations.
+
+A value of 0 disables trimming of allocations entirely, while a value of 1
+trims excess pages aggressively. Any value >= 1 acts as the watermark where
+trimming of allocations is initiated.
+
+The default value is 1.
+
+See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
+
+
+numa_zonelist_order
+===================
+
+This sysctl is only for NUMA and it is deprecated. Anything but
+Node order will fail!
+
+'where the memory is allocated from' is controlled by zonelists.
+
+(This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation.
+you may be able to read ZONE_DMA as ZONE_DMA32...)
+
+In non-NUMA case, a zonelist for GFP_KERNEL is ordered as following.
+ZONE_NORMAL -> ZONE_DMA
+This means that a memory allocation request for GFP_KERNEL will
+get memory from ZONE_DMA only when ZONE_NORMAL is not available.
+
+In NUMA case, you can think of following 2 types of order.
+Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL::
+
+  (A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL
+  (B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA.
+
+Type(A) offers the best locality for processes on Node(0), but ZONE_DMA
+will be used before ZONE_NORMAL exhaustion. This increases possibility of
+out-of-memory(OOM) of ZONE_DMA because ZONE_DMA is tend to be small.
+
+Type(B) cannot offer the best locality but is more robust against OOM of
+the DMA zone.
+
+Type(A) is called as "Node" order. Type (B) is "Zone" order.
+
+"Node order" orders the zonelists by node, then by zone within each node.
+Specify "[Nn]ode" for node order
+
+"Zone Order" orders the zonelists by zone type, then by node within each
+zone.  Specify "[Zz]one" for zone order.
+
+Specify "[Dd]efault" to request automatic configuration.
+
+On 32-bit, the Normal zone needs to be preserved for allocations accessible
+by the kernel, so "zone" order will be selected.
+
+On 64-bit, devices that require DMA32/DMA are relatively rare, so "node"
+order will be selected.
+
+Default order is recommended unless this is causing problems for your
+system/application.
+
+
+oom_dump_tasks
+==============
+
+Enables a system-wide task dump (excluding kernel threads) to be produced
+when the kernel performs an OOM-killing and includes such information as
+pid, uid, tgid, vm size, rss, pgtables_bytes, swapents, oom_score_adj
+score, and name.  This is helpful to determine why the OOM killer was
+invoked, to identify the rogue task that caused it, and to determine why
+the OOM killer chose the task it did to kill.
+
+If this is set to zero, this information is suppressed.  On very
+large systems with thousands of tasks it may not be feasible to dump
+the memory state information for each one.  Such systems should not
+be forced to incur a performance penalty in OOM conditions when the
+information may not be desired.
+
+If this is set to non-zero, this information is shown whenever the
+OOM killer actually kills a memory-hogging task.
+
+The default value is 1 (enabled).
+
+
+oom_kill_allocating_task
+========================
+
+This enables or disables killing the OOM-triggering task in
+out-of-memory situations.
+
+If this is set to zero, the OOM killer will scan through the entire
+tasklist and select a task based on heuristics to kill.  This normally
+selects a rogue memory-hogging task that frees up a large amount of
+memory when killed.
+
+If this is set to non-zero, the OOM killer simply kills the task that
+triggered the out-of-memory condition.  This avoids the expensive
+tasklist scan.
+
+If panic_on_oom is selected, it takes precedence over whatever value
+is used in oom_kill_allocating_task.
+
+The default value is 0.
+
+
+overcommit_kbytes
+=================
+
+When overcommit_memory is set to 2, the committed address space is not
+permitted to exceed swap plus this amount of physical RAM. See below.
+
+Note: overcommit_kbytes is the counterpart of overcommit_ratio. Only one
+of them may be specified at a time. Setting one disables the other (which
+then appears as 0 when read).
+
+
+overcommit_memory
+=================
+
+This value contains a flag that enables memory overcommitment.
+
+When this flag is 0, the kernel compares the userspace memory request
+size against total memory plus swap and rejects obvious overcommits.
+
+When this flag is 1, the kernel pretends there is always enough
+memory until it actually runs out.
+
+When this flag is 2, the kernel uses a "never overcommit"
+policy that attempts to prevent any overcommit of memory.
+Note that user_reserve_kbytes affects this policy.
+
+This feature can be very useful because there are a lot of
+programs that malloc() huge amounts of memory "just-in-case"
+and don't use much of it.
+
+The default value is 0.
+
+See Documentation/mm/overcommit-accounting.rst and
+mm/util.c::__vm_enough_memory() for more information.
+
+
+overcommit_ratio
+================
+
+When overcommit_memory is set to 2, the committed address
+space is not permitted to exceed swap plus this percentage
+of physical RAM.  See above.
+
+
+page-cluster
+============
+
+page-cluster controls the number of pages up to which consecutive pages
+are read in from swap in a single attempt. This is the swap counterpart
+to page cache readahead.
+The mentioned consecutivity is not in terms of virtual/physical addresses,
+but consecutive on swap space - that means they were swapped out together.
+
+It is a logarithmic value - setting it to zero means "1 page", setting
+it to 1 means "2 pages", setting it to 2 means "4 pages", etc.
+Zero disables swap readahead completely.
+
+The default value is three (eight pages at a time).  There may be some
+small benefits in tuning this to a different value if your workload is
+swap-intensive.
+
+Lower values mean lower latencies for initial faults, but at the same time
+extra faults and I/O delays for following faults if they would have been part of
+that consecutive pages readahead would have brought in.
+
+
+page_lock_unfairness
+====================
+
+This value determines the number of times that the page lock can be
+stolen from under a waiter. After the lock is stolen the number of times
+specified in this file (default is 5), the "fair lock handoff" semantics
+will apply, and the waiter will only be awakened if the lock can be taken.
+
+panic_on_oom
+============
+
+This enables or disables panic on out-of-memory feature.
+
+If this is set to 0, the kernel will kill some rogue process,
+called oom_killer.  Usually, oom_killer can kill rogue processes and
+system will survive.
+
+If this is set to 1, the kernel panics when out-of-memory happens.
+However, if a process limits using nodes by mempolicy/cpusets,
+and those nodes become memory exhaustion status, one process
+may be killed by oom-killer. No panic occurs in this case.
+Because other nodes' memory may be free. This means system total status
+may be not fatal yet.
+
+If this is set to 2, the kernel panics compulsorily even on the
+above-mentioned. Even oom happens under memory cgroup, the whole
+system panics.
+
+The default value is 0.
+
+1 and 2 are for failover of clustering. Please select either
+according to your policy of failover.
+
+panic_on_oom=2+kdump gives you very strong tool to investigate
+why oom happens. You can get snapshot.
+
+
+panic_on_unrecoverable_memory_failure
+======================================
+
+When a hardware memory error (e.g. multi-bit ECC) hits a kernel page
+that cannot be recovered by the memory failure handler, the default
+behaviour is to ignore the error and continue operation.  This is
+dangerous because the corrupted data remains accessible to the kernel,
+risking silent data corruption or a delayed crash when the poisoned
+memory is next accessed.
+
+When enabled, this sysctl triggers a panic on memory failure events
+hitting kernel-owned pages that the handler cannot recover:
+``PageReserved`` (firmware reservations, kernel image, vDSO, zero
+page, and similar memblock-reserved regions), ``PageSlab``,
+``PageTable``, and ``PageLargeKmalloc``.  These are owned by the
+kernel and the memory failure handler cannot reliably evict their
+contents.
+
+Other unrecoverable kernel-owned populations (vmalloc allocations,
+kernel stack pages, ...) are not currently covered because the
+handler has no page-type signal that distinguishes them from a
+userspace folio temporarily off the LRU during migration or
+compaction.  Such pages still go through the standard
+MF_MSG_GET_HWPOISON path: ``PG_hwpoison`` is set on them and a
+delayed crash on the next access remains possible.  Coverage may
+grow as the handler gains stronger kernel-ownership signals.
+
+Recoverable failure paths are also intentionally left out: in-flight
+buddy allocations and other transient races with the page allocator
+can reach the same diagnostic, and panicking on them would risk
+killing the box for a page destined for userspace where the standard
+SIGBUS recovery path applies.  Pages whose state could not be
+classified at all are not covered either, since an unknown state is
+not a sound basis for a panic decision.
+
+For many environments it is preferable to panic immediately with a clean
+crash dump that captures the original error context, rather than to
+continue and face a random crash later whose cause is difficult to
+diagnose.
+
+Use cases
+---------
+
+This option is most useful in environments where unattributed crashes
+are expensive to debug or where data integrity must take precedence
+over availability:
+
+* Large fleets, where multi-bit ECC errors on kernel pages are observed
+  regularly and post-mortem analysis of an unrelated downstream crash
+  (often seconds to minutes after the original error) consumes
+  significant engineering effort.
+
+* Systems configured with kdump, where panicking at the moment of the
+  hardware error produces a vmcore that still contains the faulting
+  address, the affected page state, and the originating MCE/GHES
+  record — context that is typically lost by the time a delayed crash
+  occurs.
+
+* High-availability clusters that rely on fast, deterministic node
+  failure for failover, and prefer an immediate panic over silent data
+  corruption propagating to replicas or persistent storage.
+
+* Kernel and platform developers reproducing hwpoison issues with
+  tools such as ``mce-inject`` or error-injection debugfs interfaces,
+  where panicking on the unrecoverable path makes regressions
+  immediately visible instead of surfacing as later, unrelated
+  failures.
+
+= =====================================================================
+0 Try to continue operation (default).
+1 Panic immediately.  If the ``panic`` sysctl is also non-zero then the
+  machine will be rebooted.
+= =====================================================================
+
+Example::
+
+     echo 1 > /proc/sys/vm/panic_on_unrecoverable_memory_failure
+
+
+percpu_pagelist_high_fraction
+=============================
+
+This is the fraction of pages in each zone that are can be stored to
+per-cpu page lists. It is an upper boundary that is divided depending
+on the number of online CPUs. The min value for this is 8 which means
+that we do not allow more than 1/8th of pages in each zone to be stored
+on per-cpu page lists. This entry only changes the value of hot per-cpu
+page lists. A user can specify a number like 100 to allocate 1/100th of
+each zone between per-cpu lists.
+
+The batch value of each per-cpu page list remains the same regardless of
+the value of the high fraction so allocation latencies are unaffected.
+
+The initial value is zero. Kernel uses this value to set the high pcp->high
+mark based on the low watermark for the zone and the number of local
+online CPUs.  If the user writes '0' to this sysctl, it will revert to
+this default behavior.
+
+
+stat_interval
+=============
+
+The time interval between which vm statistics are updated.  The default
+is 1 second.
+
+
+stat_refresh
+============
+
+Any read or write (by root only) flushes all the per-cpu vm statistics
+into their global totals, for more accurate reports when testing
+e.g. cat /proc/sys/vm/stat_refresh /proc/meminfo
+
+As a side-effect, it also checks for negative totals (elsewhere reported
+as 0) and "fails" with EINVAL if any are found, with a warning in dmesg.
+(At time of writing, a few stats are known sometimes to be found negative,
+with no ill effects: errors and warnings on these stats are suppressed.)
+
+
+numa_stat
+=========
+
+This interface allows runtime configuration of numa statistics.
+
+When page allocation performance becomes a bottleneck and you can tolerate
+some possible tool breakage and decreased numa counter precision, you can
+do::
+
+	echo 0 > /proc/sys/vm/numa_stat
+
+When page allocation performance is not a bottleneck and you want all
+tooling to work, you can do::
+
+	echo 1 > /proc/sys/vm/numa_stat
+
+
+swappiness
+==========
+
+This control is used to define the rough relative IO cost of swapping
+and filesystem paging, as a value between 0 and 200. At 100, the VM
+assumes equal IO cost and will thus apply memory pressure to the page
+cache and swap-backed pages equally; lower values signify more
+expensive swap IO, higher values indicates cheaper.
+
+Keep in mind that filesystem IO patterns under memory pressure tend to
+be more efficient than swap's random IO. An optimal value will require
+experimentation and will also be workload-dependent.
+
+The default value is 60.
+
+For in-memory swap, like zram or zswap, as well as hybrid setups that
+have swap on faster devices than the filesystem, values beyond 100 can
+be considered. For example, if the random IO against the swap device
+is on average 2x faster than IO from the filesystem, swappiness should
+be 133 (x + 2x = 200, 2x = 133.33).
+
+At 0, the kernel will not initiate swap until the amount of free and
+file-backed pages is less than the high watermark in a zone.
+
+
+unprivileged_userfaultfd
+========================
+
+This flag controls the mode in which unprivileged users can use the
+userfaultfd system calls. Set this to 0 to restrict unprivileged users
+to handle page faults in user mode only. In this case, users without
+SYS_CAP_PTRACE must pass UFFD_USER_MODE_ONLY in order for userfaultfd to
+succeed. Prohibiting use of userfaultfd for handling faults from kernel
+mode may make certain vulnerabilities more difficult to exploit.
+
+Set this to 1 to allow unprivileged users to use the userfaultfd system
+calls without any restrictions.
+
+The default value is 0.
+
+Another way to control permissions for userfaultfd is to use
+/dev/userfaultfd instead of userfaultfd(2). See
+Documentation/admin-guide/mm/userfaultfd.rst.
+
+user_reserve_kbytes
+===================
+
+When overcommit_memory is set to 2, "never overcommit" mode, reserve
+min(3% of current process size, user_reserve_kbytes) of free memory.
+This is intended to prevent a user from starting a single memory hogging
+process, such that they cannot recover (kill the hog).
+
+This setting has no effect when overcommit_memory is set to 0 or 1.
+
+user_reserve_kbytes defaults to min(3% of the current process size, 128MB).
+
+If this is reduced to zero, then the user will be allowed to allocate
+all free memory with a single process, minus admin_reserve_kbytes.
+Any subsequent attempts to execute a command will result in
+"fork: Cannot allocate memory".
+
+Changing this takes effect whenever an application requests memory.
+
+
+vfs_cache_pressure
+==================
+
+This percentage value controls the tendency of the kernel to reclaim
+the memory which is used for caching of directory and inode objects.
+
+At the default value of vfs_cache_pressure=vfs_cache_pressure_denom the kernel
+will attempt to reclaim dentries and inodes at a "fair" rate with respect to
+pagecache and swapcache reclaim.  Decreasing vfs_cache_pressure causes the
+kernel to prefer to retain dentry and inode caches. When vfs_cache_pressure=0,
+the kernel will never reclaim dentries and inodes due to memory pressure and
+this can easily lead to out-of-memory conditions. Increasing vfs_cache_pressure
+beyond vfs_cache_pressure_denom causes the kernel to prefer to reclaim dentries
+and inodes.
+
+Increasing vfs_cache_pressure significantly beyond vfs_cache_pressure_denom may
+have negative performance impact. Reclaim code needs to take various locks to
+find freeable directory and inode objects. When vfs_cache_pressure equals
+(10 * vfs_cache_pressure_denom), it will look for ten times more freeable
+objects than there are.
+
+Note: This setting should always be used together with vfs_cache_pressure_denom.
+
+vfs_cache_pressure_denom
+========================
+
+Defaults to 100 (minimum allowed value). Requires corresponding
+vfs_cache_pressure setting to take effect.
+
+watermark_boost_factor
+======================
+
+This factor controls the level of reclaim when memory is being fragmented.
+It defines the percentage of the high watermark of a zone that will be
+reclaimed if pages of different mobility are being mixed within pageblocks.
+The intent is that compaction has less work to do in the future and to
+increase the success rate of future high-order allocations such as SLUB
+allocations, THP and hugetlbfs pages.
+
+To make it sensible with respect to the watermark_scale_factor
+parameter, the unit is in fractions of 10,000. The default value of
+15,000 means that up to 150% of the high watermark will be reclaimed in the
+event of a pageblock being mixed due to fragmentation. The level of reclaim
+is determined by the number of fragmentation events that occurred in the
+recent past. If this value is smaller than a pageblock then a pageblocks
+worth of pages will be reclaimed (e.g.  2MB on 64-bit x86). A boost factor
+of 0 will disable the feature.
+
+
+watermark_scale_factor
+======================
+
+This factor controls the aggressiveness of kswapd. It defines the
+amount of memory left in a node/system before kswapd is woken up and
+how much memory needs to be free before kswapd goes back to sleep.
+
+The unit is in fractions of 10,000. The default value of 10 means the
+distances between watermarks are 0.1% of the available memory in the
+node/system. The maximum value is 3000, or 30% of memory.
+
+A high rate of threads entering direct reclaim (allocstall) or kswapd
+going to sleep prematurely (kswapd_low_wmark_hit_quickly) can indicate
+that the number of free pages kswapd maintains for latency reasons is
+too small for the allocation bursts occurring in the system. This knob
+can then be used to tune kswapd aggressiveness accordingly.
+
+
+zone_reclaim_mode
+=================
+
+Zone_reclaim_mode allows someone to set more or less aggressive approaches to
+reclaim memory when a zone runs out of memory. If it is set to zero then no
+zone reclaim occurs. Allocations will be satisfied from other zones / nodes
+in the system.
+
+This is value OR'ed together of
+
+=	===================================
+1	Zone reclaim on
+2	Zone reclaim writes dirty pages out
+4	Zone reclaim swaps pages
+=	===================================
+
+zone_reclaim_mode is disabled by default.  For file servers or workloads
+that benefit from having their data cached, zone_reclaim_mode should be
+left disabled as the caching effect is likely to be more important than
+data locality.
+
+Consider enabling one or more zone_reclaim mode bits if it's known that the
+workload is partitioned such that each partition fits within a NUMA node
+and that accessing remote memory would cause a measurable performance
+reduction.  The page allocator will take additional actions before
+allocating off node pages.
+
+Allowing zone reclaim to write out pages stops processes that are
+writing large amounts of data from dirtying pages on other nodes. Zone
+reclaim will write out dirty pages if a zone fills up and so effectively
+throttle the process. This may decrease the performance of a single process
+since it cannot use all of system memory to buffer the outgoing writes
+anymore but it preserve the memory on other nodes so that the performance
+of other processes running on other nodes will not be affected.
+
+Allowing regular swap effectively restricts allocations to the local
+node unless explicitly overridden by memory policies or cpuset
+configurations.
diff --git a/Documentation/admin-guide/sysctl/xen.rst b/Documentation/admin-guide/sysctl/xen.rst
new file mode 100644
index 000000000..6c5edc3e5
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/xen.rst
@@ -0,0 +1,31 @@
+===============
+/proc/sys/xen/
+===============
+
+Copyright (c) 2026, Shubham Chakraborty <chakrabortyshubham66@gmail.com>
+
+For general info and legal blurb, please look in
+Documentation/admin-guide/sysctl/index.rst.
+
+------------------------------------------------------------------------------
+
+These files show up in ``/proc/sys/xen/``, depending on the
+kernel configuration:
+
+.. contents:: :local:
+
+balloon/hotplug_unpopulated
+===========================
+
+This flag controls whether unpopulated memory ranges are automatically
+hotplugged as system RAM.
+
+- ``0``: Unpopulated ranges are not hotplugged (default).
+- ``1``: Unpopulated ranges are automatically hotplugged.
+
+When enabled, the Xen balloon driver will add memory regions that are
+marked as unpopulated in the Xen memory map to the system as usable RAM.
+This allows for dynamic memory expansion in Xen guest domains.
+
+This option is only available when the kernel is built with
+``CONFIG_XEN_BALLOON_MEMORY_HOTPLUG`` enabled.
diff --git a/Documentation/admin-guide/sysfs-rules.rst b/Documentation/admin-guide/sysfs-rules.rst
new file mode 100644
index 000000000..abad33526
--- /dev/null
+++ b/Documentation/admin-guide/sysfs-rules.rst
@@ -0,0 +1,192 @@
+Rules on how to access information in sysfs
+===========================================
+
+The kernel-exported sysfs exports internal kernel implementation details
+and depends on internal kernel structures and layout. It is agreed upon
+by the kernel developers that the Linux kernel does not provide a stable
+internal API. Therefore, there are aspects of the sysfs interface that
+may not be stable across kernel releases.
+
+To minimize the risk of breaking users of sysfs, which are in most cases
+low-level userspace applications, with a new kernel release, the users
+of sysfs must follow some rules to use an as-abstract-as-possible way to
+access this filesystem. The current udev and HAL programs already
+implement this and users are encouraged to plug, if possible, into the
+abstractions these programs provide instead of accessing sysfs directly.
+
+But if you really do want or need to access sysfs directly, please follow
+the following rules and then your programs should work with future
+versions of the sysfs interface.
+
+- Do not use libsysfs
+    It makes assumptions about sysfs which are not true. Its API does not
+    offer any abstraction, it exposes all the kernel driver-core
+    implementation details in its own API. Therefore it is not better than
+    reading directories and opening the files yourself.
+    Also, it is not actively maintained, in the sense of reflecting the
+    current kernel development. The goal of providing a stable interface
+    to sysfs has failed; it causes more problems than it solves. It
+    violates many of the rules in this document.
+
+- sysfs is always at ``/sys``
+    Parsing ``/proc/mounts`` is a waste of time. Other mount points are a
+    system configuration bug you should not try to solve. For test cases,
+    possibly support a ``SYSFS_PATH`` environment variable to overwrite the
+    application's behavior, but never try to search for sysfs. Never try
+    to mount it, if you are not an early boot script.
+
+- devices are only "devices"
+    There is no such thing like class-, bus-, physical devices,
+    interfaces, and such that you can rely on in userspace. Everything is
+    just simply a "device". Class-, bus-, physical, ... types are just
+    kernel implementation details which should not be expected by
+    applications that look for devices in sysfs.
+
+    The properties of a device are:
+
+    - devpath (``/devices/pci0000:00/0000:00:1d.1/usb2/2-2/2-2:1.0``)
+
+      - identical to the DEVPATH value in the event sent from the kernel
+        at device creation and removal
+      - the unique key to the device at that point in time
+      - the kernel's path to the device directory without the leading
+        ``/sys``, and always starting with a slash
+      - all elements of a devpath must be real directories. Symlinks
+        pointing to /sys/devices must always be resolved to their real
+        target and the target path must be used to access the device.
+        That way the devpath to the device matches the devpath of the
+        kernel used at event time.
+      - using or exposing symlink values as elements in a devpath string
+        is a bug in the application
+
+    - kernel name (``sda``, ``tty``, ``0000:00:1f.2``, ...)
+
+      - a directory name, identical to the last element of the devpath
+      - applications need to handle spaces and characters like ``!`` in
+        the name
+
+    - subsystem (``block``, ``tty``, ``pci``, ...)
+
+      - simple string, never a path or a link
+      - retrieved by reading the "subsystem"-link and using only the
+        last element of the target path
+
+    - driver (``tg3``, ``ata_piix``, ``uhci_hcd``)
+
+      - a simple string, which may contain spaces, never a path or a
+        link
+      - it is retrieved by reading the "driver"-link and using only the
+        last element of the target path
+      - devices which do not have "driver"-link just do not have a
+        driver; copying the driver value in a child device context is a
+        bug in the application
+
+    - attributes
+
+      - the files in the device directory or files below subdirectories
+        of the same device directory
+      - accessing attributes reached by a symlink pointing to another device,
+        like the "device"-link, is a bug in the application
+
+    Everything else is just a kernel driver-core implementation detail
+    that should not be assumed to be stable across kernel releases.
+
+- Properties of parent devices never belong into a child device.
+    Always look at the parent devices themselves for determining device
+    context properties. If the device ``eth0`` or ``sda`` does not have a
+    "driver"-link, then this device does not have a driver. Its value is empty.
+    Never copy any property of the parent-device into a child-device. Parent
+    device properties may change dynamically without any notice to the
+    child device.
+
+- Hierarchy in a single device tree
+    There is only one valid place in sysfs where hierarchy can be examined
+    and this is below: ``/sys/devices.``
+    It is planned that all device directories will end up in the tree
+    below this directory.
+
+- Classification by subsystem
+    There are currently three places for classification of devices:
+    ``/sys/block,`` ``/sys/class`` and ``/sys/bus.`` It is planned that these will
+    not contain any device directories themselves, but only flat lists of
+    symlinks pointing to the unified ``/sys/devices`` tree.
+    All three places have completely different rules on how to access
+    device information. It is planned to merge all three
+    classification directories into one place at ``/sys/subsystem``,
+    following the layout of the bus directories. All buses and
+    classes, including the converted block subsystem, will show up
+    there.
+    The devices belonging to a subsystem will create a symlink in the
+    "devices" directory at ``/sys/subsystem/<name>/devices``,
+
+    If ``/sys/subsystem`` exists, ``/sys/bus``, ``/sys/class`` and ``/sys/block``
+    can be ignored. If it does not exist, you always have to scan all three
+    places, as the kernel is free to move a subsystem from one place to
+    the other, as long as the devices are still reachable by the same
+    subsystem name.
+
+    Assuming ``/sys/class/<subsystem>`` and ``/sys/bus/<subsystem>``, or
+    ``/sys/block`` and ``/sys/class/block`` are not interchangeable is a bug in
+    the application.
+
+- Block
+    The converted block subsystem at ``/sys/class/block`` or
+    ``/sys/subsystem/block`` will contain the links for disks and partitions
+    at the same level, never in a hierarchy. Assuming the block subsystem to
+    contain only disks and not partition devices in the same flat list is
+    a bug in the application.
+
+- "device"-link and <subsystem>:<kernel name>-links
+    Never depend on the "device"-link. The "device"-link is a workaround
+    for the old layout, where class devices are not created in
+    ``/sys/devices/`` like the bus devices. If the link-resolving of a
+    device directory does not end in ``/sys/devices/``, you can use the
+    "device"-link to find the parent devices in ``/sys/devices/``, That is the
+    single valid use of the "device"-link; it must never appear in any
+    path as an element. Assuming the existence of the "device"-link for
+    a device in ``/sys/devices/`` is a bug in the application.
+    Accessing ``/sys/class/net/eth0/device`` is a bug in the application.
+
+    Never depend on the class-specific links back to the ``/sys/class``
+    directory.  These links are also a workaround for the design mistake
+    that class devices are not created in ``/sys/devices.`` If a device
+    directory does not contain directories for child devices, these links
+    may be used to find the child devices in ``/sys/class.`` That is the single
+    valid use of these links; they must never appear in any path as an
+    element. Assuming the existence of these links for devices which are
+    real child device directories in the ``/sys/devices`` tree is a bug in
+    the application.
+
+    It is planned to remove all these links when all class device
+    directories live in ``/sys/devices.``
+
+- Position of devices along device chain can change.
+    Never depend on a specific parent device position in the devpath,
+    or the chain of parent devices. The kernel is free to insert devices into
+    the chain. You must always request the parent device you are looking for
+    by its subsystem value. You need to walk up the chain until you find
+    the device that matches the expected subsystem. Depending on a specific
+    position of a parent device or exposing relative paths using ``../`` to
+    access the chain of parents is a bug in the application.
+
+- When reading and writing sysfs device attribute files, avoid dependency
+    on specific error codes wherever possible. This minimizes coupling to
+    the error handling implementation within the kernel.
+
+    In general, failures to read or write sysfs device attributes shall
+    propagate errors wherever possible. Common errors include, but are not
+    limited to:
+
+	``-EIO``: The read or store operation is not supported, typically
+	returned by the sysfs system itself if the read or store pointer
+	is ``NULL``.
+
+	``-ENXIO``: The read or store operation failed
+
+    Error codes will not be changed without good reason, and should a change
+    to error codes result in user-space breakage, it will be fixed, or the
+    the offending change will be reverted.
+
+    Userspace applications can, however, expect the format and contents of
+    the attribute files to remain consistent in the absence of a version
+    attribute change in the context of a given attribute.
diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst
new file mode 100644
index 000000000..9c7aa817a
--- /dev/null
+++ b/Documentation/admin-guide/sysrq.rst
@@ -0,0 +1,312 @@
+Linux Magic System Request Key Hacks
+====================================
+
+Documentation for sysrq.c
+
+What is the magic SysRq key?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It is a 'magical' key combo you can hit which the kernel will respond to
+regardless of whatever else it is doing, unless it is completely locked up.
+
+How do I enable the magic SysRq key?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You need to say "yes" to 'Magic SysRq key (CONFIG_MAGIC_SYSRQ)' when
+configuring the kernel. When running a kernel with SysRq compiled in,
+/proc/sys/kernel/sysrq controls the functions allowed to be invoked via
+the SysRq key. The default value in this file is set by the
+CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE config symbol, which itself defaults
+to 1. Here is the list of possible values in /proc/sys/kernel/sysrq:
+
+   -  0 - disable sysrq completely
+   -  1 - enable all functions of sysrq
+   - >1 - bitmask of allowed sysrq functions (see below for detailed function
+     description)::
+
+          2 =   0x2 - enable control of console logging level
+          4 =   0x4 - enable control of keyboard (SAK, unraw)
+          8 =   0x8 - enable debugging dumps of processes etc.
+         16 =  0x10 - enable sync command
+         32 =  0x20 - enable remount read-only
+         64 =  0x40 - enable signalling of processes (term, kill, oom-kill)
+        128 =  0x80 - allow reboot/poweroff
+        256 = 0x100 - allow nicing of all RT tasks
+
+You can set the value in the file by the following command::
+
+    echo "number" >/proc/sys/kernel/sysrq
+
+The number may be written here either as decimal or as hexadecimal
+with the 0x prefix. CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE must always be
+written in hexadecimal.
+
+Note that the value of ``/proc/sys/kernel/sysrq`` influences only the invocation
+via a keyboard. Invocation of any operation via ``/proc/sysrq-trigger`` is
+always allowed (by a user with admin privileges).
+
+How do I use the magic SysRq key?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+On x86
+	You press the key combo `ALT-SysRq-<command key>`.
+
+	.. note::
+	   Some
+           keyboards may not have a key labeled 'SysRq'. The 'SysRq' key is
+           also known as the 'Print Screen' key. Also some keyboards cannot
+	   handle so many keys being pressed at the same time, so you might
+	   have better luck with press `Alt`, press `SysRq`,
+	   release `SysRq`, press `<command key>`, release everything.
+
+On SPARC
+	You press `ALT-STOP-<command key>`, I believe.
+
+On the serial console (PC style standard serial ports only)
+        You send a ``BREAK``, then within 5 seconds a command key. Sending
+        ``BREAK`` twice is interpreted as a normal BREAK.
+
+On PowerPC
+	Press `ALT - Print Screen` (or `F13`) - `<command key>`.
+        `Print Screen` (or `F13`) - `<command key>` may suffice.
+
+On other
+	If you know of the key combos for other architectures, please
+	submit a patch to be included in this section.
+
+On all
+	Write a single character to /proc/sysrq-trigger.
+	Only the first character is processed, the rest of the string is
+	ignored. However, it is not recommended to write any extra characters
+	as the behavior is undefined and might change in the future versions.
+	E.g.::
+
+		echo t > /proc/sysrq-trigger
+
+	Alternatively, write multiple characters prepended by underscore.
+	This way, all characters will be processed. E.g.::
+
+		echo _reisub > /proc/sysrq-trigger
+
+The `<command key>` is case sensitive.
+
+What are the 'command' keys?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+=========== ===================================================================
+Command	    Function
+=========== ===================================================================
+``b``	    Will immediately reboot the system without syncing or unmounting
+            your disks.
+
+``c``	    Will perform a system crash and a crashdump will be taken
+            if configured.
+
+``d``	    Shows all locks that are held.
+
+``e``	    Send a SIGTERM to all processes, except for init.
+
+``f``	    Will call the oom killer to kill a memory hog process, but do not
+	    panic if nothing can be killed.
+
+``g``	    Used by kgdb (kernel debugger)
+
+``h``	    Will display help (actually any other key than those listed
+            here will display help. but ``h`` is easy to remember :-)
+
+``i``	    Send a SIGKILL to all processes, except for init.
+
+``j``	    Forcibly "Just thaw it" - filesystems frozen by the FIFREEZE ioctl.
+
+``k``	    Secure Access Key (SAK) Kills all programs on the current virtual
+            console. NOTE: See important comments below in SAK section.
+
+``l``	    Shows a stack backtrace for all active CPUs.
+
+``m``	    Will dump current memory info to your console.
+
+``n``	    Used to make RT tasks nice-able
+
+``o``	    Will shut your system off (if configured and supported).
+
+``p``	    Will dump the current registers and flags to your console.
+
+``q``	    Will dump per CPU lists of all armed hrtimers (but NOT regular
+            timer_list timers) and detailed information about all
+            clockevent devices.
+
+``r``	    Turns off keyboard raw mode and sets it to XLATE.
+
+``s``	    Will attempt to sync all mounted filesystems.
+
+``t``	    Will dump a list of current tasks and their information to your
+            console.
+
+``u``	    Will attempt to remount all mounted filesystems read-only.
+
+``v``	    Forcefully restores framebuffer console
+``v``	    Causes ETM buffer dump [ARM-specific]
+
+``w``	    Dumps tasks that are in uninterruptible (blocked) state.
+
+``x``	    Used by xmon interface on ppc/powerpc platforms.
+            Show global PMU Registers on sparc64.
+            Dump all TLB entries on MIPS.
+
+``y``	    Show global CPU Registers [SPARC-64 specific]
+
+``z``	    Dump the ftrace buffer
+
+``0``-``9`` Sets the console log level, controlling which kernel messages
+            will be printed to your console. (``0``, for example would make
+            it so that only emergency messages like PANICs or OOPSes would
+            make it to your console.)
+
+``R``	    Replay the kernel log messages on consoles.
+=========== ===================================================================
+
+Okay, so what can I use them for?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Well, unraw(r) is very handy when your X server or a svgalib program crashes.
+
+sak(k) (Secure Access Key) is useful when you want to be sure there is no
+trojan program running at console which could grab your password
+when you would try to login. It will kill all programs on given console,
+thus letting you make sure that the login prompt you see is actually
+the one from init, not some trojan program.
+
+.. important::
+
+   In its true form it is not a true SAK like the one in a
+   c2 compliant system, and it should not be mistaken as
+   such.
+
+It seems others find it useful as (System Attention Key) which is
+useful when you want to exit a program that will not let you switch consoles.
+(For example, X or a svgalib program.)
+
+``reboot(b)`` is good when you're unable to shut down, it is an equivalent
+of pressing the "reset" button.
+
+``crash(c)`` can be used to manually trigger a crashdump when the system is hung.
+Note that this just triggers a crash if there is no dump mechanism available.
+
+``sync(s)`` is handy before yanking removable medium or after using a rescue
+shell that provides no graceful shutdown -- it will ensure your data is
+safely written to the disk. Note that the sync hasn't taken place until you see
+the "OK" and "Done" appear on the screen.
+
+``umount(u)`` can be used to mark filesystems as properly unmounted. From the
+running system's point of view, they will be remounted read-only. The remount
+isn't complete until you see the "OK" and "Done" message appear on the screen.
+
+The loglevels ``0``-``9`` are useful when your console is being flooded with
+kernel messages you do not want to see. Selecting ``0`` will prevent all but
+the most urgent kernel messages from reaching your console. (They will
+still be logged if syslogd/klogd are alive, though.)
+
+``term(e)`` and ``kill(i)`` are useful if you have some sort of runaway process
+you are unable to kill any other way, especially if it's spawning other
+processes.
+
+"just thaw ``it(j)``" is useful if your system becomes unresponsive due to a
+frozen (probably root) filesystem via the FIFREEZE ioctl.
+
+``Replay logs(R)`` is useful to view the kernel log messages when system is hung
+or you are not able to use dmesg command to view the messages in printk buffer.
+User may have to press the key combination multiple times if console system is
+busy. If it is completely locked up, then messages won't be printed. Output
+messages depend on current console loglevel, which can be modified using
+sysrq[0-9] (see above).
+
+Sometimes SysRq seems to get 'stuck' after using it, what can I do?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When this happens, try tapping shift, alt and control on both sides of the
+keyboard, and hitting an invalid sysrq sequence again. (i.e., something like
+`alt-sysrq-z`).
+
+Switching to another virtual console (`ALT+Fn`) and then back again
+should also help.
+
+I hit SysRq, but nothing seems to happen, what's wrong?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There are some keyboards that produce a different keycode for SysRq than the
+pre-defined value of 99
+(see ``KEY_SYSRQ`` in ``include/uapi/linux/input-event-codes.h``), or
+which don't have a SysRq key at all. In these cases, run ``showkey -s`` to find
+an appropriate scancode sequence, and use ``setkeycodes <sequence> 99`` to map
+this sequence to the usual SysRq code (e.g., ``setkeycodes e05b 99``). It's
+probably best to put this command in a boot script. Oh, and by the way, you
+exit ``showkey`` by not typing anything for ten seconds.
+
+I want to add SysRQ key events to a module, how does it work?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In order to register a basic function with the table, you must first include
+the header ``include/linux/sysrq.h``, this will define everything else you need.
+Next, you must create a ``sysrq_key_op`` struct, and populate it with A) the key
+handler function you will use, B) a help_msg string, that will print when SysRQ
+prints help, and C) an action_msg string, that will print right before your
+handler is called. Your handler must conform to the prototype in 'sysrq.h'.
+
+After the ``sysrq_key_op`` is created, you can call the kernel function
+``register_sysrq_key(int key, const struct sysrq_key_op *op_p);`` this will
+register the operation pointed to by ``op_p`` at table key 'key',
+if that slot in the table is blank. At module unload time, you must call
+the function ``unregister_sysrq_key(int key, const struct sysrq_key_op *op_p)``,
+which will remove the key op pointed to by 'op_p' from the key 'key', if and
+only if it is currently registered in that slot. This is in case the slot has
+been overwritten since you registered it.
+
+The Magic SysRQ system works by registering key operations against a key op
+lookup table, which is defined in 'drivers/tty/sysrq.c'. This key table has
+a number of operations registered into it at compile time, but is mutable,
+and 2 functions are exported for interface to it::
+
+	register_sysrq_key and unregister_sysrq_key.
+
+Of course, never ever leave an invalid pointer in the table. I.e., when
+your module that called register_sysrq_key() exits, it must call
+unregister_sysrq_key() to clean up the sysrq key table entry that it used.
+Null pointers in the table are always safe. :)
+
+If for some reason you feel the need to call the handle_sysrq function from
+within a function called by handle_sysrq, you must be aware that you are in
+a lock (you are also in an interrupt handler, which means don't sleep!), so
+you must call ``__handle_sysrq_nolock`` instead.
+
+When I hit a SysRq key combination only the header appears on the console?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sysrq output is subject to the same console loglevel control as all
+other console output.  This means that if the kernel was booted 'quiet'
+as is common on distro kernels the output may not appear on the actual
+console, even though it will appear in the dmesg buffer, and be accessible
+via the dmesg command and to the consumers of ``/proc/kmsg``.  As a specific
+exception the header line from the sysrq command is passed to all console
+consumers as if the current loglevel was maximum.  If only the header
+is emitted it is almost certain that the kernel loglevel is too low.
+Should you require the output on the console channel then you will need
+to temporarily up the console loglevel using `alt-sysrq-8` or::
+
+    echo 8 > /proc/sysrq-trigger
+
+Remember to return the loglevel to normal after triggering the sysrq
+command you are interested in.
+
+I have more questions, who can I ask?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Just ask them on the linux-kernel mailing list:
+	linux-kernel@vger.kernel.org
+
+Credits
+~~~~~~~
+
+- Written by Mydraal <vulpyne@vulpyne.net>
+- Updated by Adam Sulmicki <adam@cfar.umd.edu>
+- Updated by Jeremy M. Dolan <jmd@turbogeek.org> 2001/01/28 10:15:59
+- Added to by Crutcher Dunnavant <crutcher+kernel@datastacks.com>
diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
new file mode 100644
index 000000000..9ead927a3
--- /dev/null
+++ b/Documentation/admin-guide/tainted-kernels.rst
@@ -0,0 +1,191 @@
+Tainted kernels
+---------------
+
+The kernel will mark itself as 'tainted' when something occurs that might be
+relevant later when investigating problems. Don't worry too much about this,
+most of the time it's not a problem to run a tainted kernel; the information is
+mainly of interest once someone wants to investigate some problem, as its real
+cause might be the event that got the kernel tainted. That's why bug reports
+from tainted kernels will often be ignored by developers, hence try to reproduce
+problems with an untainted kernel.
+
+Note the kernel will remain tainted even after you undo what caused the taint
+(i.e. unload a proprietary kernel module), to indicate the kernel remains not
+trustworthy. That's also why the kernel will print the tainted state when it
+notices an internal problem (a 'kernel bug'), a recoverable error
+('kernel oops') or a non-recoverable error ('kernel panic') and writes debug
+information about this to the logs ``dmesg`` outputs. It's also possible to
+check the tainted state at runtime through a file in ``/proc/``.
+
+
+Tainted flag in bugs, oops or panics messages
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You find the tainted state near the top in a line starting with 'CPU:'; if or
+why the kernel was tainted is shown after the Process ID ('PID:') and a shortened
+name of the command ('Comm:') that triggered the event::
+
+	BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
+	Oops: 0002 [#1] SMP PTI
+	CPU: 0 PID: 4424 Comm: insmod Tainted: P        W  O      4.20.0-0.rc6.fc30 #1
+	Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
+	RIP: 0010:my_oops_init+0x13/0x1000 [kpanic]
+	[...]
+
+You'll find a 'Not tainted: ' there if the kernel was not tainted at the
+time of the event; if it was, then it will print 'Tainted: ' and characters
+either letters or blanks. In the example above it looks like this::
+
+	Tainted: P        W  O
+
+The meaning of those characters is explained in the table below. In this case
+the kernel got tainted earlier because a proprietary Module (``P``) was loaded,
+a warning occurred (``W``), and an externally-built module was loaded (``O``).
+To decode other letters use the table below.
+
+
+Decoding tainted state at runtime
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+At runtime, you can query the tainted state by reading
+``cat /proc/sys/kernel/tainted``. If that returns ``0``, the kernel is not
+tainted; any other number indicates the reasons why it is. The easiest way to
+decode that number is the script ``tools/debugging/kernel-chktaint``, which your
+distribution might ship as part of a package called ``linux-tools`` or
+``kernel-tools``; if it doesn't, you can download the script from
+`git.kernel.org <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/tools/debugging/kernel-chktaint>`_
+and execute it with ``sh kernel-chktaint``, which would print something like
+this on the machine that had the statements in the logs that were quoted earlier::
+
+	Kernel is Tainted for following reasons:
+	 * Proprietary module was loaded (#0)
+	 * Kernel issued warning (#9)
+	 * Externally-built ('out-of-tree') module was loaded  (#12)
+	See Documentation/admin-guide/tainted-kernels.rst in the Linux kernel or
+	 https://www.kernel.org/doc/html/latest/admin-guide/tainted-kernels.html for
+	 a more details explanation of the various taint flags.
+	Raw taint value as int/string: 4609/'P        W  O     '
+
+You can try to decode the number yourself. That's easy if there was only one
+reason that got your kernel tainted, as in this case you can find the number
+with the table below. If there were multiple reasons you need to decode the
+number, as it is a bitfield, where each bit indicates the absence or presence of
+a particular type of taint. It's best to leave that to the aforementioned
+script, but if you need something quick you can use this shell command to check
+which bits are set::
+
+	$ for i in $(seq 20); do echo $(($i-1)) $(($(cat /proc/sys/kernel/tainted)>>($i-1)&1));done
+
+Table for decoding tainted state
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+===  ===  ======  ========================================================
+Bit  Log  Number  Reason that got the kernel tainted
+===  ===  ======  ========================================================
+  0  G/P       1  proprietary module was loaded
+  1  _/F       2  module was force loaded
+  2  _/S       4  kernel running on an out of specification system
+  3  _/R       8  module was force unloaded
+  4  _/M      16  processor reported a Machine Check Exception (MCE)
+  5  _/B      32  bad page referenced or some unexpected page flags
+  6  _/U      64  taint requested by userspace application
+  7  _/D     128  kernel died recently, i.e. there was an OOPS or BUG
+  8  _/A     256  ACPI table overridden by user
+  9  _/W     512  kernel issued warning
+ 10  _/C    1024  staging driver was loaded
+ 11  _/I    2048  workaround for bug in platform firmware applied
+ 12  _/O    4096  externally-built ("out-of-tree") module was loaded
+ 13  _/E    8192  unsigned module was loaded
+ 14  _/L   16384  soft lockup occurred
+ 15  _/K   32768  kernel has been live patched
+ 16  _/X   65536  auxiliary taint, defined for and used by distros
+ 17  _/T  131072  kernel was built with the struct randomization plugin
+ 18  _/N  262144  an in-kernel test has been run
+ 19  _/J  524288  userspace used a mutating debug operation in fwctl
+===  ===  ======  ========================================================
+
+Note: The character ``_`` is representing a blank in this table to make reading
+easier.
+
+More detailed explanation for tainting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+ 0)  ``G`` if all modules loaded have a GPL or compatible license, ``P`` if
+     any proprietary module has been loaded.  Modules without a
+     MODULE_LICENSE or with a MODULE_LICENSE that is not recognised by
+     insmod as GPL compatible are assumed to be proprietary.
+
+ 1)  ``F`` if any module was force loaded by ``insmod -f``, ``' '`` if all
+     modules were loaded normally.
+
+ 2)  ``S`` if the kernel is running on a processor or system that is out of
+     specification: hardware has been put into an unsupported configuration,
+     therefore proper execution cannot be guaranteed.
+     Kernel will be tainted if, for example:
+
+     - on x86: PAE is forced through forcepae on intel CPUs (such as Pentium M)
+       which do not report PAE but may have a functional implementation, an SMP
+       kernel is running on non officially capable SMP Athlon CPUs, MSRs are
+       being poked at from userspace.
+     - on arm: kernel running on certain CPUs (such as Keystone 2) without
+       having certain kernel features enabled.
+     - on arm64: there are mismatched hardware features between CPUs, the
+       bootloader has booted CPUs in different modes.
+     - certain drivers are being used on non supported architectures (such as
+       scsi/snic on something else than x86_64, scsi/ips on non
+       x86/x86_64/itanium, have broken firmware settings for the
+       irqchip/irq-gic on arm64 ...).
+     - x86/x86_64: Microcode late loading is dangerous and will result in
+       tainting the kernel. It requires that all CPUs rendezvous to make sure
+       the update happens when the system is as quiescent as possible. However,
+       a higher priority MCE/SMI/NMI can move control flow away from that
+       rendezvous and interrupt the update, which can be detrimental to the
+       machine.
+
+ 3)  ``R`` if a module was force unloaded by ``rmmod -f``, ``' '`` if all
+     modules were unloaded normally.
+
+ 4)  ``M`` if any processor has reported a Machine Check Exception,
+     ``' '`` if no Machine Check Exceptions have occurred.
+
+ 5)  ``B`` If a page-release function has found a bad page reference or some
+     unexpected page flags. This indicates a hardware problem or a kernel bug;
+     there should be other information in the log indicating why this tainting
+     occurred.
+
+ 6)  ``U`` if a user or user application specifically requested that the
+     Tainted flag be set, ``' '`` otherwise.
+
+ 7)  ``D`` if the kernel has died recently, i.e. there was an OOPS or BUG.
+
+ 8)  ``A`` if an ACPI table has been overridden.
+
+ 9)  ``W`` if a warning has previously been issued by the kernel.
+     (Though some warnings may set more specific taint flags.)
+
+ 10) ``C`` if a staging driver has been loaded.
+
+ 11) ``I`` if the kernel is working around a severe bug in the platform
+     firmware (BIOS or similar).
+
+ 12) ``O`` if an externally-built ("out-of-tree") module has been loaded.
+
+ 13) ``E`` if an unsigned module has been loaded in a kernel supporting
+     module signature.
+
+ 14) ``L`` if a soft lockup has previously occurred on the system.
+
+ 15) ``K`` if the kernel has been live patched.
+
+ 16) ``X`` Auxiliary taint, defined for and used by Linux distributors.
+
+ 17) ``T`` Kernel was build with the randstruct plugin, which can intentionally
+     produce extremely unusual kernel structure layouts (even performance
+     pathological ones), which is important to know when debugging. Set at
+     build time.
+
+ 18) ``N`` if an in-kernel test, such as a KUnit test, has been run.
+
+ 19) ``J`` if userspace opened /dev/fwctl/* and performed a FWTCL_RPC_DEBUG_WRITE
+     to use the devices debugging features. Device debugging features could
+     cause the device to malfunction in undefined ways.
diff --git a/Documentation/admin-guide/thermal/index.rst b/Documentation/admin-guide/thermal/index.rst
new file mode 100644
index 000000000..e48bc0a19
--- /dev/null
+++ b/Documentation/admin-guide/thermal/index.rst
@@ -0,0 +1,9 @@
+=================
+Thermal Subsystem
+=================
+
+.. toctree::
+   :maxdepth: 1
+
+   intel_powerclamp
+   intel_thermal_throttle
diff --git a/Documentation/admin-guide/thermal/intel_powerclamp.rst b/Documentation/admin-guide/thermal/intel_powerclamp.rst
new file mode 100644
index 000000000..08509b978
--- /dev/null
+++ b/Documentation/admin-guide/thermal/intel_powerclamp.rst
@@ -0,0 +1,345 @@
+=======================
+Intel Powerclamp Driver
+=======================
+
+By:
+  - Arjan van de Ven <arjan@linux.intel.com>
+  - Jacob Pan <jacob.jun.pan@linux.intel.com>
+
+.. Contents:
+
+	(*) Introduction
+	    - Goals and Objectives
+
+	(*) Theory of Operation
+	    - Idle Injection
+	    - Calibration
+
+	(*) Performance Analysis
+	    - Effectiveness and Limitations
+	    - Power vs Performance
+	    - Scalability
+	    - Calibration
+	    - Comparison with Alternative Techniques
+
+	(*) Usage and Interfaces
+	    - Generic Thermal Layer (sysfs)
+	    - Kernel APIs (TBD)
+
+	(*) Module Parameters
+
+INTRODUCTION
+============
+
+Consider the situation where a system’s power consumption must be
+reduced at runtime, due to power budget, thermal constraint, or noise
+level, and where active cooling is not preferred. Software managed
+passive power reduction must be performed to prevent the hardware
+actions that are designed for catastrophic scenarios.
+
+Currently, P-states, T-states (clock modulation), and CPU offlining
+are used for CPU throttling.
+
+On Intel CPUs, C-states provide effective power reduction, but so far
+they’re only used opportunistically, based on workload. With the
+development of intel_powerclamp driver, the method of synchronizing
+idle injection across all online CPU threads was introduced. The goal
+is to achieve forced and controllable C-state residency.
+
+Test/Analysis has been made in the areas of power, performance,
+scalability, and user experience. In many cases, clear advantage is
+shown over taking the CPU offline or modulating the CPU clock.
+
+
+THEORY OF OPERATION
+===================
+
+Idle Injection
+--------------
+
+On modern Intel processors (Nehalem or later), package level C-state
+residency is available in MSRs, thus also available to the kernel.
+
+These MSRs are::
+
+      #define MSR_PKG_C2_RESIDENCY      0x60D
+      #define MSR_PKG_C3_RESIDENCY      0x3F8
+      #define MSR_PKG_C6_RESIDENCY      0x3F9
+      #define MSR_PKG_C7_RESIDENCY      0x3FA
+
+If the kernel can also inject idle time to the system, then a
+closed-loop control system can be established that manages package
+level C-state. The intel_powerclamp driver is conceived as such a
+control system, where the target set point is a user-selected idle
+ratio (based on power reduction), and the error is the difference
+between the actual package level C-state residency ratio and the target idle
+ratio.
+
+Injection is controlled by high priority kernel threads, spawned for
+each online CPU.
+
+These kernel threads, with SCHED_FIFO class, are created to perform
+clamping actions of controlled duty ratio and duration. Each per-CPU
+thread synchronizes its idle time and duration, based on the rounding
+of jiffies, so accumulated errors can be prevented to avoid a jittery
+effect. Threads are also bound to the CPU such that they cannot be
+migrated, unless the CPU is taken offline. In this case, threads
+belong to the offlined CPUs will be terminated immediately.
+
+Running as SCHED_FIFO and relatively high priority, also allows such
+scheme to work for both preemptible and non-preemptible kernels.
+Alignment of idle time around jiffies ensures scalability for HZ
+values. This effect can be better visualized using a Perf timechart.
+The following diagram shows the behavior of kernel thread
+kidle_inject/cpu. During idle injection, it runs monitor/mwait idle
+for a given "duration", then relinquishes the CPU to other tasks,
+until the next time interval.
+
+The NOHZ schedule tick is disabled during idle time, but interrupts
+are not masked. Tests show that the extra wakeups from scheduler tick
+have a dramatic impact on the effectiveness of the powerclamp driver
+on large scale systems (Westmere system with 80 processors).
+
+::
+
+  CPU0
+		    ____________          ____________
+  kidle_inject/0   |   sleep    |  mwait |  sleep     |
+	  _________|            |________|            |_______
+				 duration
+  CPU1
+		    ____________          ____________
+  kidle_inject/1   |   sleep    |  mwait |  sleep     |
+	  _________|            |________|            |_______
+				^
+				|
+				|
+				roundup(jiffies, interval)
+
+Only one CPU is allowed to collect statistics and update global
+control parameters. This CPU is referred to as the controlling CPU in
+this document. The controlling CPU is elected at runtime, with a
+policy that favors BSP, taking into account the possibility of a CPU
+hot-plug.
+
+In terms of dynamics of the idle control system, package level idle
+time is considered largely as a non-causal system where its behavior
+cannot be based on the past or current input. Therefore, the
+intel_powerclamp driver attempts to enforce the desired idle time
+instantly as given input (target idle ratio). After injection,
+powerclamp monitors the actual idle for a given time window and adjust
+the next injection accordingly to avoid over/under correction.
+
+When used in a causal control system, such as a temperature control,
+it is up to the user of this driver to implement algorithms where
+past samples and outputs are included in the feedback. For example, a
+PID-based thermal controller can use the powerclamp driver to
+maintain a desired target temperature, based on integral and
+derivative gains of the past samples.
+
+
+
+Calibration
+-----------
+During scalability testing, it is observed that synchronized actions
+among CPUs become challenging as the number of cores grows. This is
+also true for the ability of a system to enter package level C-states.
+
+To make sure the intel_powerclamp driver scales well, online
+calibration is implemented. The goals for doing such a calibration
+are:
+
+a) determine the effective range of idle injection ratio
+b) determine the amount of compensation needed at each target ratio
+
+Compensation to each target ratio consists of two parts:
+
+	a) steady state error compensation
+
+	   This is to offset the error occurring when the system can
+	   enter idle without extra wakeups (such as external interrupts).
+
+	b) dynamic error compensation
+
+	   When an excessive amount of wakeups occurs during idle, an
+	   additional idle ratio can be added to quiet interrupts, by
+	   slowing down CPU activities.
+
+A debugfs file is provided for the user to examine compensation
+progress and results, such as on a Westmere system::
+
+  [jacob@nex01 ~]$ cat
+  /sys/kernel/debug/intel_powerclamp/powerclamp_calib
+  controlling cpu: 0
+  pct confidence steady dynamic (compensation)
+  0       0       0       0
+  1       1       0       0
+  2       1       1       0
+  3       3       1       0
+  4       3       1       0
+  5       3       1       0
+  6       3       1       0
+  7       3       1       0
+  8       3       1       0
+  ...
+  30      3       2       0
+  31      3       2       0
+  32      3       1       0
+  33      3       2       0
+  34      3       1       0
+  35      3       2       0
+  36      3       1       0
+  37      3       2       0
+  38      3       1       0
+  39      3       2       0
+  40      3       3       0
+  41      3       1       0
+  42      3       2       0
+  43      3       1       0
+  44      3       1       0
+  45      3       2       0
+  46      3       3       0
+  47      3       0       0
+  48      3       2       0
+  49      3       3       0
+
+Calibration occurs during runtime. No offline method is available.
+Steady state compensation is used only when confidence levels of all
+adjacent ratios have reached satisfactory level. A confidence level
+is accumulated based on clean data collected at runtime. Data
+collected during a period without extra interrupts is considered
+clean.
+
+To compensate for excessive amounts of wakeup during idle, additional
+idle time is injected when such a condition is detected. Currently,
+we have a simple algorithm to double the injection ratio. A possible
+enhancement might be to throttle the offending IRQ, such as delaying
+EOI for level triggered interrupts. But it is a challenge to be
+non-intrusive to the scheduler or the IRQ core code.
+
+
+CPU Online/Offline
+------------------
+Per-CPU kernel threads are started/stopped upon receiving
+notifications of CPU hotplug activities. The intel_powerclamp driver
+keeps track of clamping kernel threads, even after they are migrated
+to other CPUs, after a CPU offline event.
+
+
+Performance Analysis
+====================
+This section describes the general performance data collected on
+multiple systems, including Westmere (80P) and Ivy Bridge (4P, 8P).
+
+Effectiveness and Limitations
+-----------------------------
+The maximum range that idle injection is allowed is capped at 50
+percent. As mentioned earlier, since interrupts are allowed during
+forced idle time, excessive interrupts could result in less
+effectiveness. The extreme case would be doing a ping -f to generated
+flooded network interrupts without much CPU acknowledgement. In this
+case, little can be done from the idle injection threads. In most
+normal cases, such as scp a large file, applications can be throttled
+by the powerclamp driver, since slowing down the CPU also slows down
+network protocol processing, which in turn reduces interrupts.
+
+When control parameters change at runtime by the controlling CPU, it
+may take an additional period for the rest of the CPUs to catch up
+with the changes. During this time, idle injection is out of sync,
+thus not able to enter package C- states at the expected ratio. But
+this effect is minor, in that in most cases change to the target
+ratio is updated much less frequently than the idle injection
+frequency.
+
+Scalability
+-----------
+Tests also show a minor, but measurable, difference between the 4P/8P
+Ivy Bridge system and the 80P Westmere server under 50% idle ratio.
+More compensation is needed on Westmere for the same amount of
+target idle ratio. The compensation also increases as the idle ratio
+gets larger. The above reason constitutes the need for the
+calibration code.
+
+On the IVB 8P system, compared to an offline CPU, powerclamp can
+achieve up to 40% better performance per watt. (measured by a spin
+counter summed over per CPU counting threads spawned for all running
+CPUs).
+
+Usage and Interfaces
+====================
+The powerclamp driver is registered to the generic thermal layer as a
+cooling device. Currently, it’s not bound to any thermal zones::
+
+  jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . *
+  cur_state:0
+  max_state:50
+  type:intel_powerclamp
+
+cur_state allows user to set the desired idle percentage. Writing 0 to
+cur_state will stop idle injection. Writing a value between 1 and
+max_state will start the idle injection. Reading cur_state returns the
+actual and current idle percentage. This may not be the same value
+set by the user in that current idle percentage depends on workload
+and includes natural idle. When idle injection is disabled, reading
+cur_state returns value -1 instead of 0 which is to avoid confusing
+100% busy state with the disabled state.
+
+Example usage:
+
+- To inject 25% idle time::
+
+	$ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state
+
+If the system is not busy and has more than 25% idle time already,
+then the powerclamp driver will not start idle injection. Using Top
+will not show idle injection kernel threads.
+
+If the system is busy (spin test below) and has less than 25% natural
+idle time, powerclamp kernel threads will do idle injection. Forced
+idle time is accounted as normal idle in that common code path is
+taken as the idle task.
+
+In this example, 24.1% idle is shown. This helps the system admin or
+user determine the cause of slowdown, when a powerclamp driver is in action::
+
+
+  Tasks: 197 total,   1 running, 196 sleeping,   0 stopped,   0 zombie
+  Cpu(s): 71.2%us,  4.7%sy,  0.0%ni, 24.1%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
+  Mem:   3943228k total,  1689632k used,  2253596k free,    74960k buffers
+  Swap:  4087804k total,        0k used,  4087804k free,   945336k cached
+
+    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
+   3352 jacob     20   0  262m  644  428 S  286  0.0   0:17.16 spin
+   3341 root     -51   0     0    0    0 D   25  0.0   0:01.62 kidle_inject/0
+   3344 root     -51   0     0    0    0 D   25  0.0   0:01.60 kidle_inject/3
+   3342 root     -51   0     0    0    0 D   25  0.0   0:01.61 kidle_inject/1
+   3343 root     -51   0     0    0    0 D   25  0.0   0:01.60 kidle_inject/2
+   2935 jacob     20   0  696m 125m  35m S    5  3.3   0:31.11 firefox
+   1546 root      20   0  158m  20m 6640 S    3  0.5   0:26.97 Xorg
+   2100 jacob     20   0 1223m  88m  30m S    3  2.3   0:23.68 compiz
+
+Tests have shown that by using the powerclamp driver as a cooling
+device, a PID based userspace thermal controller can manage to
+control CPU temperature effectively, when no other thermal influence
+is added. For example, a UltraBook user can compile the kernel under
+certain temperature (below most active trip points).
+
+Module Parameters
+=================
+
+``cpumask`` (RW)
+	A bit mask of CPUs to inject idle. The format of the bitmask is same as
+	used in other subsystems like in /proc/irq/\*/smp_affinity. The mask is
+	comma separated 32 bit groups. Each CPU is one bit. For example for a 256
+	CPU system the full mask is:
+	ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff
+
+	The rightmost mask is for CPU 0-32.
+
+``max_idle`` (RW)
+	Maximum injected idle time to the total CPU time ratio in percent range
+	from 1 to 100. Even if the cooling device max_state is always 100 (100%),
+	this parameter allows to add a max idle percent limit. The default is 50,
+	to match the current implementation of powerclamp driver. Also doesn't
+	allow value more than 75, if the cpumask includes every CPU present in
+	the system.
diff --git a/Documentation/admin-guide/thermal/intel_thermal_throttle.rst b/Documentation/admin-guide/thermal/intel_thermal_throttle.rst
new file mode 100644
index 000000000..f4fbf9d5a
--- /dev/null
+++ b/Documentation/admin-guide/thermal/intel_thermal_throttle.rst
@@ -0,0 +1,91 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+=======================================
+Intel thermal throttle events reporting
+=======================================
+
+:Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+
+Introduction
+------------
+
+Intel processors have built in automatic and adaptive thermal monitoring
+mechanisms that force the processor to reduce its power consumption in order
+to operate within predetermined temperature limits.
+
+Refer to section "THERMAL MONITORING AND PROTECTION" in the "Intel® 64 and
+IA-32 Architectures Software Developer’s Manual Volume 3 (3A, 3B, 3C, & 3D):
+System Programming Guide" for more details.
+
+In general, there are two mechanisms to control the core temperature of the
+processor. They are called "Thermal Monitor 1 (TM1) and Thermal Monitor 2 (TM2)".
+
+The status of the temperature sensor that triggers the thermal monitor (TM1/TM2)
+is indicated through the "thermal status flag" and "thermal status log flag" in
+MSR_IA32_THERM_STATUS for core level and MSR_IA32_PACKAGE_THERM_STATUS for
+package level.
+
+Thermal Status flag, bit 0 — When set, indicates that the processor core
+temperature is currently at the trip temperature of the thermal monitor and that
+the processor power consumption is being reduced via either TM1 or TM2, depending
+on which is enabled. When clear, the flag indicates that the core temperature is
+below the thermal monitor trip temperature. This flag is read only.
+
+Thermal Status Log flag, bit 1 — When set, indicates that the thermal sensor has
+tripped since the last power-up or reset or since the last time that software
+cleared this flag. This flag is a sticky bit; once set it remains set until
+cleared by software or until a power-up or reset of the processor. The default
+state is clear.
+
+It is possible that when user reads MSR_IA32_THERM_STATUS or
+MSR_IA32_PACKAGE_THERM_STATUS, TM1/TM2 is not active. In this case,
+"Thermal Status flag" will read "0" and the "Thermal Status Log flag" will be set
+to show any previous "TM1/TM2" activation. But since it needs to be cleared by
+the software, it can't show the number of occurrences of "TM1/TM2" activations.
+
+Hence, Linux provides counters of how many times the "Thermal Status flag" was
+set. Also presents how long the "Thermal Status flag" was active in milliseconds.
+Using these counters, users can check if the performance was limited because of
+thermal events. It is recommended to read from sysfs instead of directly reading
+MSRs as the "Thermal Status Log flag" is reset by the driver to implement rate
+control.
+
+Sysfs Interface
+---------------
+
+Thermal throttling events are presented for each CPU under
+"/sys/devices/system/cpu/cpuX/thermal_throttle/", where "X" is the CPU number.
+
+All these counters are read-only. They can't be reset to 0. So, they can potentially
+overflow after reaching the maximum 64 bit unsigned integer.
+
+``core_throttle_count``
+	Shows the number of times "Thermal Status flag" changed from 0 to 1 for this
+	CPU since OS boot and thermal vector is initialized. This is a 64 bit counter.
+
+``package_throttle_count``
+	Shows the number of times "Thermal Status flag" changed from 0 to 1 for the
+	package containing this CPU since OS boot and thermal vector is initialized.
+	Package status is broadcast to all CPUs; all CPUs in the package increment
+	this count. This is a 64-bit counter.
+
+``core_throttle_max_time_ms``
+	Shows the maximum amount of time for which "Thermal Status flag" has been
+	set to 1 for this CPU at the core level since OS boot and thermal vector
+	is initialized.
+
+``package_throttle_max_time_ms``
+	Shows the maximum amount of time for which "Thermal Status flag" has been
+	set to 1 for the package containing this CPU since OS boot and thermal
+	vector is initialized.
+
+``core_throttle_total_time_ms``
+	Shows the cumulative time for which "Thermal Status flag" has been
+	set to 1 for this CPU for core level since OS boot and thermal vector
+	is initialized.
+
+``package_throttle_total_time_ms``
+	Shows the cumulative time for which "Thermal Status flag" has been set
+	to 1 for the package containing this CPU since OS boot and thermal vector
+	is initialized.
diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst
new file mode 100644
index 000000000..ff25fe853
--- /dev/null
+++ b/Documentation/admin-guide/thunderbolt.rst
@@ -0,0 +1,445 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+ USB4 and Thunderbolt
+======================
+USB4 is the public specification based on Thunderbolt 3 protocol with
+some differences at the register level among other things. Connection
+manager is an entity running on the host router (host controller)
+responsible for enumerating routers and establishing tunnels. A
+connection manager can be implemented either in firmware or software.
+Typically PCs come with a firmware connection manager for Thunderbolt 3
+and early USB4 capable systems. Apple systems on the other hand use
+software connection manager and the later USB4 compliant devices follow
+the suit.
+
+The Linux Thunderbolt driver supports both and can detect at runtime which
+connection manager implementation is to be used. To be on the safe side the
+software connection manager in Linux also advertises security level
+``user`` which means PCIe tunneling is disabled by default. The
+documentation below applies to both implementations with the exception that
+the software connection manager only supports ``user`` security level and
+is expected to be accompanied with an IOMMU based DMA protection.
+
+Security levels and how to use them
+-----------------------------------
+The interface presented here is not meant for end users. Instead there
+should be a userspace tool that handles all the low-level details, keeps
+a database of the authorized devices and prompts users for new connections.
+
+More details about the sysfs interface for Thunderbolt devices can be
+found in Documentation/ABI/testing/sysfs-bus-thunderbolt.
+
+Those users who just want to connect any device without any sort of
+manual work can add following line to
+``/etc/udev/rules.d/99-local.rules``::
+
+  ACTION=="add", SUBSYSTEM=="thunderbolt", ATTR{authorized}=="0", ATTR{authorized}="1"
+
+This will authorize all devices automatically when they appear. However,
+keep in mind that this bypasses the security levels and makes the system
+vulnerable to DMA attacks.
+
+Starting with Intel Falcon Ridge Thunderbolt controller there are 4
+security levels available. Intel Titan Ridge added one more security level
+(usbonly). The reason for these is the fact that the connected devices can
+be DMA masters and thus read contents of the host memory without CPU and OS
+knowing about it. There are ways to prevent this by setting up an IOMMU but
+it is not always available for various reasons.
+
+Some USB4 systems have a BIOS setting to disable PCIe tunneling. This is
+treated as another security level (nopcie).
+
+The security levels are as follows:
+
+  none
+    All devices are automatically connected by the firmware. No user
+    approval is needed. In BIOS settings this is typically called
+    *Legacy mode*.
+
+  user
+    User is asked whether the device is allowed to be connected.
+    Based on the device identification information available through
+    ``/sys/bus/thunderbolt/devices``, the user then can make the decision.
+    In BIOS settings this is typically called *Unique ID*.
+
+  secure
+    User is asked whether the device is allowed to be connected. In
+    addition to UUID the device (if it supports secure connect) is sent
+    a challenge that should match the expected one based on a random key
+    written to the ``key`` sysfs attribute. In BIOS settings this is
+    typically called *One time saved key*.
+
+  dponly
+    The firmware automatically creates tunnels for Display Port and
+    USB. No PCIe tunneling is done. In BIOS settings this is
+    typically called *Display Port Only*.
+
+  usbonly
+    The firmware automatically creates tunnels for the USB controller and
+    Display Port in a dock. All PCIe links downstream of the dock are
+    removed.
+
+  nopcie
+    PCIe tunneling is disabled/forbidden from the BIOS. Available in some
+    USB4 systems.
+
+The current security level can be read from
+``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is
+the Thunderbolt domain the host controller manages. There is typically
+one domain per Thunderbolt host controller.
+
+If the security level reads as ``user`` or ``secure`` the connected
+device must be authorized by the user before PCIe tunnels are created
+(e.g the PCIe device appears).
+
+Each Thunderbolt device plugged in will appear in sysfs under
+``/sys/bus/thunderbolt/devices``. The device directory carries
+information that can be used to identify the particular device,
+including its name and UUID.
+
+Authorizing devices when security level is ``user`` or ``secure``
+-----------------------------------------------------------------
+When a device is plugged in it will appear in sysfs as follows::
+
+  /sys/bus/thunderbolt/devices/0-1/authorized	- 0
+  /sys/bus/thunderbolt/devices/0-1/device	- 0x8004
+  /sys/bus/thunderbolt/devices/0-1/device_name	- Thunderbolt to FireWire Adapter
+  /sys/bus/thunderbolt/devices/0-1/vendor	- 0x1
+  /sys/bus/thunderbolt/devices/0-1/vendor_name	- Apple, Inc.
+  /sys/bus/thunderbolt/devices/0-1/unique_id	- e0376f00-0300-0100-ffff-ffffffffffff
+
+The ``authorized`` attribute reads 0 which means no PCIe tunnels are
+created yet. The user can authorize the device by simply entering::
+
+  # echo 1 > /sys/bus/thunderbolt/devices/0-1/authorized
+
+This will create the PCIe tunnels and the device is now connected.
+
+If the device supports secure connect, and the domain security level is
+set to ``secure``, it has an additional attribute ``key`` which can hold
+a random 32-byte value used for authorization and challenging the device in
+future connects::
+
+  /sys/bus/thunderbolt/devices/0-3/authorized	- 0
+  /sys/bus/thunderbolt/devices/0-3/device	- 0x305
+  /sys/bus/thunderbolt/devices/0-3/device_name	- AKiTiO Thunder3 PCIe Box
+  /sys/bus/thunderbolt/devices/0-3/key		-
+  /sys/bus/thunderbolt/devices/0-3/vendor	- 0x41
+  /sys/bus/thunderbolt/devices/0-3/vendor_name	- inXtron
+  /sys/bus/thunderbolt/devices/0-3/unique_id	- dc010000-0000-8508-a22d-32ca6421cb16
+
+Notice the key is empty by default.
+
+If the user does not want to use secure connect they can just ``echo 1``
+to the ``authorized`` attribute and the PCIe tunnels will be created in
+the same way as in the ``user`` security level.
+
+If the user wants to use secure connect, the first time the device is
+plugged a key needs to be created and sent to the device::
+
+  # key=$(openssl rand -hex 32)
+  # echo $key > /sys/bus/thunderbolt/devices/0-3/key
+  # echo 1 > /sys/bus/thunderbolt/devices/0-3/authorized
+
+Now the device is connected (PCIe tunnels are created) and in addition
+the key is stored on the device NVM.
+
+Next time the device is plugged in the user can verify (challenge) the
+device using the same key::
+
+  # echo $key > /sys/bus/thunderbolt/devices/0-3/key
+  # echo 2 > /sys/bus/thunderbolt/devices/0-3/authorized
+
+If the challenge the device returns back matches the one we expect based
+on the key, the device is connected and the PCIe tunnels are created.
+However, if the challenge fails no tunnels are created and error is
+returned to the user.
+
+If the user still wants to connect the device they can either approve
+the device without a key or write a new key and write 1 to the
+``authorized`` file to get the new key stored on the device NVM.
+
+De-authorizing devices
+----------------------
+It is possible to de-authorize devices by writing ``0`` to their
+``authorized`` attribute. This requires support from the connection
+manager implementation and can be checked by reading domain
+``deauthorization`` attribute. If it reads ``1`` then the feature is
+supported.
+
+When a device is de-authorized the PCIe tunnel from the parent device
+PCIe downstream (or root) port to the device PCIe upstream port is torn
+down. This is essentially the same thing as PCIe hot-remove and the PCIe
+toplogy in question will not be accessible anymore until the device is
+authorized again. If there is storage such as NVMe or similar involved,
+there is a risk for data loss if the filesystem on that storage is not
+properly shut down. You have been warned!
+
+DMA protection utilizing IOMMU
+------------------------------
+Recent systems from 2018 and forward with Thunderbolt ports may natively
+support IOMMU. This means that Thunderbolt security is handled by an IOMMU
+so connected devices cannot access memory regions outside of what is
+allocated for them by drivers. When Linux is running on such system it
+automatically enables IOMMU if not enabled by the user already. These
+systems can be identified by reading ``1`` from
+``/sys/bus/thunderbolt/devices/domainX/iommu_dma_protection`` attribute.
+
+The driver does not do anything special in this case but because DMA
+protection is handled by the IOMMU, security levels (if set) are
+redundant. For this reason some systems ship with security level set to
+``none``. Other systems have security level set to ``user`` in order to
+support downgrade to older OS, so users who want to automatically
+authorize devices when IOMMU DMA protection is enabled can use the
+following ``udev`` rule::
+
+  ACTION=="add", SUBSYSTEM=="thunderbolt", ATTRS{iommu_dma_protection}=="1", ATTR{authorized}=="0", ATTR{authorized}="1"
+
+Upgrading NVM on Thunderbolt device, host or retimer
+----------------------------------------------------
+Since most of the functionality is handled in firmware running on a
+host controller or a device, it is important that the firmware can be
+upgraded to the latest where possible bugs in it have been fixed.
+Typically OEMs provide this firmware from their support site.
+
+Currently, recommended method of updating firmware is through "fwupd" tool.
+It uses LVFS (Linux Vendor Firmware Service) portal by default to get the
+latest firmware from hardware vendors and updates connected devices if found
+compatible. For details refer to: https://github.com/fwupd/fwupd.
+
+Before you upgrade firmware on a device, host or retimer, please make
+sure it is a suitable upgrade. Failing to do that may render the device
+in a state where it cannot be used properly anymore without special
+tools!
+
+Host NVM upgrade on Apple Macs is not supported.
+
+Fwupd is installed by default. If you don't have it on your system, simply
+use your distro package manager to get it.
+
+To see possible updates through fwupd, you need to plug in a Thunderbolt
+device so that the host controller appears. It does not matter which
+device is connected (unless you are upgrading NVM on a device - then you
+need to connect that particular device).
+
+Note an OEM-specific method to power the controller up ("force power") may
+be available for your system in which case there is no need to plug in a
+Thunderbolt device.
+
+Updating firmware using fwupd is straightforward - refer to official
+readme on fwupd github.
+
+If firmware image is written successfully, the device shortly disappears.
+Once it comes back, the driver notices it and initiates a full power
+cycle. After a while device appears again and this time it should be
+fully functional.
+
+Device of interest should display new version under "Current version"
+and "Update State: Success" in fwupd's interface.
+
+Upgrading firmware manually
+---------------------------------------------------------------
+If possible, use fwupd to updated the firmware. However, if your device OEM
+has not uploaded the firmware to LVFS, but it is available for download
+from their side, you can use method below to directly upgrade the
+firmware.
+
+Manual firmware update can be done with 'dd' tool. To update firmware
+using this method, you need to write it to the non-active parts of NVM
+of the host or device. Example on how to update Intel NUC6i7KYK
+(Skull Canyon) Thunderbolt controller NVM::
+
+  # dd if=KYK_TBT_FW_0018.bin of=/sys/bus/thunderbolt/devices/0-0/nvm_non_active0/nvmem
+
+Once the operation completes we can trigger NVM authentication and
+upgrade process as follows::
+
+  # echo 1 > /sys/bus/thunderbolt/devices/0-0/nvm_authenticate
+
+If no errors are returned, device should behave as described in previous
+section.
+
+We can verify that the new NVM firmware is active by running the following
+commands::
+
+  # cat /sys/bus/thunderbolt/devices/0-0/nvm_authenticate
+  0x0
+  # cat /sys/bus/thunderbolt/devices/0-0/nvm_version
+  18.0
+
+If ``nvm_authenticate`` contains anything other than 0x0 it is the error
+code from the last authentication cycle, which means the authentication
+of the NVM image failed.
+
+Note names of the NVMem devices ``nvm_activeN`` and ``nvm_non_activeN``
+depend on the order they are registered in the NVMem subsystem. N in
+the name is the identifier added by the NVMem subsystem.
+
+Upgrading on-board retimer NVM when there is no cable connected
+---------------------------------------------------------------
+If the platform supports, it may be possible to upgrade the retimer NVM
+firmware even when there is nothing connected to the USB4
+ports. When this is the case the ``usb4_portX`` devices have two special
+attributes: ``offline`` and ``rescan``. The way to upgrade the firmware
+is to first put the USB4 port into offline mode::
+
+  # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/offline
+
+This step makes sure the port does not respond to any hotplug events,
+and also ensures the retimers are powered on. The next step is to scan
+for the retimers::
+
+  # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/rescan
+
+This enumerates and adds the on-board retimers. Now retimer NVM can be
+upgraded in the same way than with cable connected (see previous
+section). However, the retimer is not disconnected as we are in offline
+mode, so after writing ``1`` to ``nvm_authenticate`` one should wait for
+5 or more seconds before running rescan again::
+
+  # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/rescan
+
+This point if everything went fine, the port can be put back to
+functional state again::
+
+  # echo 0 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/offline
+
+Upgrading NVM when host controller is in safe mode
+--------------------------------------------------
+If the existing NVM is not properly authenticated (or is missing) the
+host controller goes into safe mode which means that the only available
+functionality is flashing a new NVM image. When in this mode, reading
+``nvm_version`` fails with ``ENODATA`` and the device identification
+information is missing.
+
+To recover from this mode, one needs to flash a valid NVM image to the
+host controller in the same way it is done in the previous chapter.
+
+Tunneling events
+----------------
+The driver sends ``KOBJ_CHANGE`` events to userspace when there is a
+tunneling change in the ``thunderbolt_domain``. The notification carries
+following environment variables::
+
+  TUNNEL_EVENT=<EVENT>
+  TUNNEL_DETAILS=0:12 <-> 1:20 (USB3)
+
+Possible values for ``<EVENT>`` are:
+
+  activated
+    The tunnel was activated (created).
+
+  changed
+    There is a change in this tunnel. For example bandwidth allocation was
+    changed.
+
+  deactivated
+    The tunnel was torn down.
+
+  low bandwidth
+    The tunnel is not getting optimal bandwidth.
+
+  insufficient bandwidth
+    There is not enough bandwidth for the current tunnel requirements.
+
+The ``TUNNEL_DETAILS`` is only provided if the tunnel is known. For
+example, in case of Firmware Connection Manager this is missing or does
+not provide full tunnel information. In case of Software Connection Manager
+this includes full tunnel details. The format currently matches what the
+driver uses when logging. This may change over time.
+
+Networking over Thunderbolt cable
+---------------------------------
+Thunderbolt technology allows software communication between two hosts
+connected by a Thunderbolt cable.
+
+It is possible to tunnel any kind of traffic over a Thunderbolt link but
+currently we only support Apple ThunderboltIP protocol.
+
+If the other host is running Windows or macOS, the only thing you need to
+do is to connect a Thunderbolt cable between the two hosts; the
+``thunderbolt-net`` driver is loaded automatically. If the other host is
+also Linux you should load ``thunderbolt-net`` manually on one host (it
+does not matter which one)::
+
+  # modprobe thunderbolt-net
+
+This triggers module load on the other host automatically. If the driver
+is built-in to the kernel image, there is no need to do anything.
+
+The driver will create one virtual ethernet interface per Thunderbolt
+port which are named like ``thunderbolt0`` and so on. From this point
+you can either use standard userspace tools like ``ip`` to
+configure the interface or let your GUI handle it automatically.
+
+Streaming data directly over Thunderbolt cable
+----------------------------------------------
+In addition to Thunderbolt networking (aka. USB4NET) Linux supports
+streaming data directly over a cable as well (aka. USB4STREAM). This is
+possible through ``thunderbolt-stream`` driver.
+
+Similarly to ``thunderbolt-net`` you load the driver first on one end::
+
+  host1 # modprobe thunderbolt-stream
+
+Then you configure it via ``ConfigFS``::
+
+  host1 # cd /sys/kernel/config/thunderbolt/stream
+  host1 # mkdir -p 0-1.0/data
+  host1 # cd 0-1.0
+  host1 # echo -1 > data/in_hopid
+  host1 # echo -1 > data/out_hopid
+
+This information is automatically announced to the other side via
+XDomain properties so if you have cable connected the other side knows
+that there is a stream named ``data`` available and can configure it for
+you automatically::
+
+  host2 # cd /sys/kernel/config/thunderbolt/stream
+  host2 # mkdir -p 0-3.0/data
+
+Here we used auto-configuration but you can configure it manually too.
+In that case you need to fill ``in_hopid`` and ``out_hopid`` accordingly.
+If you set them to ``-1`` the next available HopID is used which is
+typically what we want.
+
+Once they are configured you can use ``/dev/tbstreamX`` on both sides to
+transfer data::
+
+  host2 # cat /dev/tbstream0
+  host1 # dmesg > /dev/tbstream0
+
+Once you are done with the stream you can remove them::
+
+  host2 # cd /sys/kernel/config/thunderbolt/stream
+  host2 # rmdir -p 0-1.0/data
+  host1 # cd /sys/kernel/config/thunderbolt/stream
+  host1 # rmdir -p 0-3.0/data
+
+Since streams are essentially files you can use any existing application
+that supports ``read(2)`` and ``write(2)`` in some form.
+
+It is possible to have more than one stream and you can have both stream
+and ``thunderbolt-net`` in use simultaneously. For example we can create
+two streams with name ``control`` and ``data`` like this::
+
+  host1 # cd /sys/kernel/config/thunderbolt/stream
+  host1 # mkdir 0-1.0
+  host1 # cd 0-1.0
+  host1 # mkdir control
+  host1 # mkdir data
+
+Then you have ``/dev/tbstream0`` for ``control`` and ``/dev/tbstream1``
+for ``data``. Before you can use them you need to configure them as
+shown above for the one stream case.
+
+Forcing power
+-------------
+Many OEMs include a method that can be used to force the power of a
+Thunderbolt controller to an "On" state even if nothing is connected.
+If supported by your machine this will be exposed by the WMI bus with
+a sysfs attribute called "force_power", see
+Documentation/ABI/testing/sysfs-platform-intel-wmi-thunderbolt for details.
+
+Note: it's currently not possible to query the force power state of a platform.
diff --git a/Documentation/admin-guide/ufs.rst b/Documentation/admin-guide/ufs.rst
new file mode 100644
index 000000000..55d15297f
--- /dev/null
+++ b/Documentation/admin-guide/ufs.rst
@@ -0,0 +1,68 @@
+=========
+Using UFS
+=========
+
+mount -t ufs -o ufstype=type_of_ufs device dir
+
+
+UFS Options
+===========
+
+ufstype=type_of_ufs
+	UFS is a file system widely used in different operating systems.
+	The problem are differences among implementations. Features of
+	some implementations are undocumented, so its hard to recognize
+	type of ufs automatically. That's why user must specify type of
+	ufs manually by mount option ufstype. Possible values are:
+
+	old
+                old format of ufs
+		default value, supported as read-only
+
+	44bsd
+                used in FreeBSD, NetBSD, OpenBSD
+		supported as read-write
+
+	ufs2
+                used in FreeBSD 5.x
+		supported as read-write
+
+	5xbsd
+                synonym for ufs2
+
+	sun
+                used in SunOS (Solaris)
+		supported as read-write
+
+	sunx86
+                used in SunOS for Intel (Solarisx86)
+		supported as read-write
+
+	hp
+                used in HP-UX
+		supported as read-only
+
+	nextstep
+		used in NextStep
+		supported as read-only
+
+	nextstep-cd
+		used for NextStep CDROMs (block_size == 2048)
+		supported as read-only
+
+	openstep
+		used in OpenStep
+		supported as read-only
+
+
+Possible Problems
+-----------------
+
+See next section, if you have any.
+
+
+Bug Reports
+-----------
+
+Any ufs bug report you can send to daniel.pirkl@email.cz or
+to dushistov@mail.ru (do not send partition tables bug reports).
diff --git a/Documentation/admin-guide/unicode.rst b/Documentation/admin-guide/unicode.rst
new file mode 100644
index 000000000..cba7e5017
--- /dev/null
+++ b/Documentation/admin-guide/unicode.rst
@@ -0,0 +1,188 @@
+Unicode support
+===============
+
+		 Last update: 2005-01-17, version 1.4
+
+Note: The original version of this document, which was maintained at
+lanana.org as part of the Linux Assigned Names And Numbers Authority
+(LANANA) project, is no longer existent.  So, this version in the
+mainline Linux kernel is now the maintained main document.
+
+Introduction
+------------
+
+The Linux kernel code has been rewritten to use Unicode to map
+characters to fonts.  By downloading a single Unicode-to-font table,
+both the eight-bit character sets and UTF-8 mode are changed to use
+the font as indicated.
+
+This changes the semantics of the eight-bit character tables subtly.
+The four character tables are now:
+
+=============== =============================== ================
+Map symbol	Map name			Escape code (G0)
+=============== =============================== ================
+LAT1_MAP	Latin-1 (ISO 8859-1)		ESC ( B
+GRAF_MAP	DEC VT100 pseudographics	ESC ( 0
+IBMPC_MAP	IBM code page 437		ESC ( U
+USER_MAP	User defined			ESC ( K
+=============== =============================== ================
+
+In particular, ESC ( U is no longer "straight to font", since the font
+might be completely different than the IBM character set.  This
+permits for example the use of block graphics even with a Latin-1 font
+loaded.
+
+Note that although these codes are similar to ISO 2022, neither the
+codes nor their uses match ISO 2022; Linux has two 8-bit codes (G0 and
+G1), whereas ISO 2022 has four 7-bit codes (G0-G3).
+
+In accordance with the Unicode standard/ISO 10646 the range U+F000 to
+U+F8FF has been reserved for OS-wide allocation (the Unicode Standard
+refers to this as a "Corporate Zone", since this is inaccurate for
+Linux we call it the "Linux Zone").  U+F000 was picked as the starting
+point since it lets the direct-mapping area start on a large power of
+two (in case 1024- or 2048-character fonts ever become necessary).
+This leaves U+E000 to U+EFFF as End User Zone.
+
+[v1.2]: The Unicodes range from U+F000 and up to U+F7FF have been
+hard-coded to map directly to the loaded font, bypassing the
+translation table.  The user-defined map now defaults to U+F000 to
+U+F0FF, emulating the previous behaviour.  In practice, this range
+might be shorter; for example, vgacon can only handle 256-character
+(U+F000..U+F0FF) or 512-character (U+F000..U+F1FF) fonts.
+
+
+Actual characters assigned in the Linux Zone
+--------------------------------------------
+
+In addition, the following characters not present in Unicode 1.1.4
+have been defined; these are used by the DEC VT graphics map.  [v1.2]
+THIS USE IS OBSOLETE AND SHOULD NO LONGER BE USED; PLEASE SEE BELOW.
+
+====== ======================================
+U+F800 DEC VT GRAPHICS HORIZONTAL LINE SCAN 1
+U+F801 DEC VT GRAPHICS HORIZONTAL LINE SCAN 3
+U+F803 DEC VT GRAPHICS HORIZONTAL LINE SCAN 7
+U+F804 DEC VT GRAPHICS HORIZONTAL LINE SCAN 9
+====== ======================================
+
+The DEC VT220 uses a 6x10 character matrix, and these characters form
+a smooth progression in the DEC VT graphics character set.  I have
+omitted the scan 5 line, since it is also used as a block-graphics
+character, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.
+
+[v1.3]: These characters have been officially added to Unicode 3.2.0;
+they are added at U+23BA, U+23BB, U+23BC, U+23BD.  Linux now uses the
+new values.
+
+[v1.2]: The following characters have been added to represent common
+keyboard symbols that are unlikely to ever be added to Unicode proper
+since they are horribly vendor-specific.  This, of course, is an
+excellent example of horrible design.
+
+====== ======================================
+U+F810 KEYBOARD SYMBOL FLYING FLAG
+U+F811 KEYBOARD SYMBOL PULLDOWN MENU
+U+F812 KEYBOARD SYMBOL OPEN APPLE
+U+F813 KEYBOARD SYMBOL SOLID APPLE
+====== ======================================
+
+Klingon language support
+------------------------
+
+In 1996, Linux was the first operating system in the world to add
+support for the artificial language Klingon, created by Marc Okrand
+for the "Star Trek" television series.	This encoding was later
+adopted by the ConScript Unicode Registry and proposed (but ultimately
+rejected) for inclusion in Unicode Plane 1.  Thus, it remains as a
+Linux/CSUR private assignment in the Linux Zone.
+
+This encoding has been endorsed by the Klingon Language Institute.
+For more information, contact them at:
+
+	http://www.kli.org/
+
+Since the characters in the beginning of the Linux CZ have been more
+of the dingbats/symbols/forms type and this is a language, I have
+located it at the end, on a 16-cell boundary in keeping with standard
+Unicode practice.
+
+.. note::
+
+  This range is now officially managed by the ConScript Unicode
+  Registry.  The normative reference is at:
+
+	https://www.evertype.com/standards/csur/klingon.html
+
+Klingon has an alphabet of 26 characters, a positional numeric writing
+system with 10 digits, and is written left-to-right, top-to-bottom.
+
+Several glyph forms for the Klingon alphabet have been proposed.
+However, since the set of symbols appear to be consistent throughout,
+with only the actual shapes being different, in keeping with standard
+Unicode practice these differences are considered font variants.
+
+======	=======================================================
+U+F8D0	KLINGON LETTER A
+U+F8D1	KLINGON LETTER B
+U+F8D2	KLINGON LETTER CH
+U+F8D3	KLINGON LETTER D
+U+F8D4	KLINGON LETTER E
+U+F8D5	KLINGON LETTER GH
+U+F8D6	KLINGON LETTER H
+U+F8D7	KLINGON LETTER I
+U+F8D8	KLINGON LETTER J
+U+F8D9	KLINGON LETTER L
+U+F8DA	KLINGON LETTER M
+U+F8DB	KLINGON LETTER N
+U+F8DC	KLINGON LETTER NG
+U+F8DD	KLINGON LETTER O
+U+F8DE	KLINGON LETTER P
+U+F8DF	KLINGON LETTER Q
+	- Written <q> in standard Okrand Latin transliteration
+U+F8E0	KLINGON LETTER QH
+	- Written <Q> in standard Okrand Latin transliteration
+U+F8E1	KLINGON LETTER R
+U+F8E2	KLINGON LETTER S
+U+F8E3	KLINGON LETTER T
+U+F8E4	KLINGON LETTER TLH
+U+F8E5	KLINGON LETTER U
+U+F8E6	KLINGON LETTER V
+U+F8E7	KLINGON LETTER W
+U+F8E8	KLINGON LETTER Y
+U+F8E9	KLINGON LETTER GLOTTAL STOP
+
+U+F8F0	KLINGON DIGIT ZERO
+U+F8F1	KLINGON DIGIT ONE
+U+F8F2	KLINGON DIGIT TWO
+U+F8F3	KLINGON DIGIT THREE
+U+F8F4	KLINGON DIGIT FOUR
+U+F8F5	KLINGON DIGIT FIVE
+U+F8F6	KLINGON DIGIT SIX
+U+F8F7	KLINGON DIGIT SEVEN
+U+F8F8	KLINGON DIGIT EIGHT
+U+F8F9	KLINGON DIGIT NINE
+
+U+F8FD	KLINGON COMMA
+U+F8FE	KLINGON FULL STOP
+U+F8FF	KLINGON SYMBOL FOR EMPIRE
+======	=======================================================
+
+Other Fictional and Artificial Scripts
+--------------------------------------
+
+Since the assignment of the Klingon Linux Unicode block, a registry of
+fictional and artificial scripts has been established by John Cowan
+<jcowan@reutershealth.com> and Michael Everson <everson@evertype.com>.
+The ConScript Unicode Registry is accessible at:
+
+	  https://www.evertype.com/standards/csur/
+
+The ranges used fall at the low end of the End User Zone and can hence
+not be normatively assigned, but it is recommended that people who
+wish to encode fictional scripts use these codes, in the interest of
+interoperability.  For Klingon, CSUR has adopted the Linux encoding.
+The CSUR people are driving adding Tengwar and Cirth into Unicode
+Plane 1; the addition of Klingon to Unicode Plane 1 has been rejected
+and so the above encoding remains official.
diff --git a/Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst b/Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst
new file mode 100644
index 000000000..7d38393f3
--- /dev/null
+++ b/Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst
@@ -0,0 +1,2221 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+.. [see the bottom of this file for redistribution information]
+
+=========================================
+How to verify bugs and bisect regressions
+=========================================
+
+This document describes how to check if some Linux kernel problem occurs in code
+currently supported by developers -- to then explain how to locate the change
+causing the issue, if it is a regression (e.g. did not happen with earlier
+versions).
+
+The text aims at people running kernels from mainstream Linux distributions on
+commodity hardware who want to report a kernel bug to the upstream Linux
+developers. Despite this intent, the instructions work just as well for users
+who are already familiar with building their own kernels: they help avoid
+mistakes occasionally made even by experienced developers.
+
+..
+   Note: if you see this note, you are reading the text's source file. You
+   might want to switch to a rendered version: it makes it a lot easier to
+   read and navigate this document -- especially when you want to look something
+   up in the reference section, then jump back to where you left off.
+..
+   Find the latest rendered version of this text here:
+   https://docs.kernel.org/admin-guide/verify-bugs-and-bisect-regressions.html
+
+The essence of the process (aka 'TL;DR')
+========================================
+
+*[If you are new to building or bisecting Linux, ignore this section and head
+over to the* ':ref:`step-by-step guide <introguide_bissbs>`' *below. It utilizes
+the same commands as this section while describing them in brief fashion. The
+steps are nevertheless easy to follow and together with accompanying entries
+in a reference section mention many alternatives, pitfalls, and additional
+aspects, all of which might be essential in your present case.]*
+
+**In case you want to check if a bug is present in code currently supported by
+developers**, execute just the *preparations* and *segment 1*; while doing so,
+consider the newest Linux kernel you regularly use to be the 'working' kernel.
+In the following example that's assumed to be 6.0, which is why its sources
+will be used to prepare the .config file.
+
+**In case you face a regression**, follow the steps at least till the end of
+*segment 2*. Then you can submit a preliminary report -- or continue with
+*segment 3*, which describes how to perform a bisection needed for a
+full-fledged regression report. In the following example 6.0.13 is assumed to be
+the 'working' kernel and 6.1.5 to be the first 'broken', which is why 6.0
+will be considered the 'good' release and used to prepare the .config file.
+
+* **Preparations**: set up everything to build your own kernels::
+
+    # * Remove any software that depends on externally maintained kernel modules
+    #   or builds any automatically during bootup.
+    # * Ensure Secure Boot permits booting self-compiled Linux kernels.
+    # * If you are not already running the 'working' kernel, reboot into it.
+    # * Install compilers and everything else needed for building Linux.
+    # * Ensure to have 15 Gigabyte free space in your home directory.
+    git clone -o mainline --no-checkout \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ~/linux/
+    cd ~/linux/
+    git remote add -t master stable \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
+    git switch --detach v6.0
+    # * Hint: if you used an existing clone, ensure no stale .config is around.
+    make olddefconfig
+    # * Ensure the former command picked the .config of the 'working' kernel.
+    # * Connect external hardware (USB keys, tokens, ...), start a VM, bring up
+    #   VPNs, mount network shares, and briefly try the feature that is broken.
+    yes '' | make localmodconfig
+    ./scripts/config --set-str CONFIG_LOCALVERSION '-local'
+    ./scripts/config -e CONFIG_LOCALVERSION_AUTO
+    # * Note, when short on storage space, check the guide for an alternative:
+    ./scripts/config -d DEBUG_INFO_NONE -e KALLSYMS_ALL -e DEBUG_KERNEL \
+      -e DEBUG_INFO -e DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT -e KALLSYMS
+    # * Hint: at this point you might want to adjust the build configuration;
+    #   you'll have to, if you are running Debian.
+    make olddefconfig
+    cp .config ~/kernel-config-working
+
+* **Segment 1**: build a kernel from the latest mainline codebase.
+
+  This among others checks if the problem was fixed already and which developers
+  later need to be told about the problem; in case of a regression, this rules
+  out a .config change as root of the problem.
+
+  a) Checking out latest mainline code::
+
+       cd ~/linux/
+       git switch --discard-changes --detach mainline/master
+
+  b) Build, install, and boot a kernel::
+
+       cp ~/kernel-config-working .config
+       make olddefconfig
+       make -j $(nproc --all)
+       # * Make sure there is enough disk space to hold another kernel:
+       df -h /boot/ /lib/modules/
+       # * Note: on Arch Linux, its derivatives and a few other distributions
+       #   the following commands will do nothing at all or only part of the
+       #   job. See the step-by-step guide for further details.
+       sudo make modules_install
+       command -v installkernel && sudo make install
+       # * Check how much space your self-built kernel actually needs, which
+       #   enables you to make better estimates later:
+       du -ch /boot/*$(make -s kernelrelease)* | tail -n 1
+       du -sh /lib/modules/$(make -s kernelrelease)/
+       # * Hint: the output of the following command will help you pick the
+       #   right kernel from the boot menu:
+       make -s kernelrelease | tee -a ~/kernels-built
+       reboot
+       # * Once booted, ensure you are running the kernel you just built by
+       #   checking if the output of the next two commands matches:
+       tail -n 1 ~/kernels-built
+       uname -r
+       cat /proc/sys/kernel/tainted
+
+  c) Check if the problem occurs with this kernel as well.
+
+* **Segment 2**: ensure the 'good' kernel is also a 'working' kernel.
+
+  This among others verifies the trimmed .config file actually works well, as
+  bisecting with it otherwise would be a waste of time:
+
+  a) Start by checking out the sources of the 'good' version::
+
+       cd ~/linux/
+       git switch --discard-changes --detach v6.0
+
+  b) Build, install, and boot a kernel as described earlier in *segment 1,
+     section b* -- just feel free to skip the 'du' commands, as you have a rough
+     estimate already.
+
+  c) Ensure the feature that regressed with the 'broken' kernel actually works
+     with this one.
+
+* **Segment 3**: perform and validate the bisection.
+
+  a) Retrieve the sources for your 'bad' version::
+
+       git remote set-branches --add stable linux-6.1.y
+       git fetch stable
+
+  b) Initialize the bisection::
+
+       cd ~/linux/
+       git bisect start
+       git bisect good v6.0
+       git bisect bad v6.1.5
+
+  c) Build, install, and boot a kernel as described earlier in *segment 1,
+     section b*.
+
+     In case building or booting the kernel fails for unrelated reasons, run
+     ``git bisect skip``. In all other outcomes, check if the regressed feature
+     works with the newly built kernel. If it does, tell Git by executing
+     ``git bisect good``; if it does not, run ``git bisect bad`` instead.
+
+     All three commands will make Git check out another commit; then re-execute
+     this step (e.g. build, install, boot, and test a kernel to then tell Git
+     the outcome). Do so again and again until Git shows which commit broke
+     things. If you run short of disk space during this process, check the
+     section 'Complementary tasks: cleanup during and after the process'
+     below.
+
+  d) Once your finished the bisection, put a few things away::
+
+       cd ~/linux/
+       git bisect log > ~/bisect-log
+       cp .config ~/bisection-config-culprit
+       git bisect reset
+
+  e) Try to verify the bisection result::
+
+       git switch --discard-changes --detach mainline/master
+       git revert --no-edit cafec0cacaca0
+       cp ~/kernel-config-working .config
+       ./scripts/config --set-str CONFIG_LOCALVERSION '-local-cafec0cacaca0-reverted'
+
+    This is optional, as some commits are impossible to revert. But if the
+    second command worked flawlessly, build, install, and boot one more kernel
+    kernel; just this time skip the first command copying the base .config file
+    over, as that already has been taken care off.
+
+* **Complementary tasks**: cleanup during and after the process.
+
+  a) To avoid running out of disk space during a bisection, you might need to
+     remove some kernels you built earlier. You most likely want to keep those
+     you built during segment 1 and 2 around for a while, but you will most
+     likely no longer need kernels tested during the actual bisection
+     (Segment 3 c). You can list them in build order using::
+
+       ls -ltr /lib/modules/*-local*
+
+    To then for example erase a kernel that identifies itself as
+    '6.0-rc1-local-gcafec0cacaca0', use this::
+
+       sudo rm -rf /lib/modules/6.0-rc1-local-gcafec0cacaca0
+       sudo kernel-install -v remove 6.0-rc1-local-gcafec0cacaca0
+       # * Note, on some distributions kernel-install is missing
+       #   or does only part of the job.
+
+  b) If you performed a bisection and successfully validated the result, feel
+     free to remove all kernels built during the actual bisection (Segment 3 c);
+     the kernels you built earlier and later you might want to keep around for
+     a week or two.
+
+* **Optional task**: test a debug patch or a proposed fix later::
+
+    git fetch mainline
+    git switch --discard-changes --detach mainline/master
+    git apply /tmp/foobars-proposed-fix-v1.patch
+    cp ~/kernel-config-working .config
+    ./scripts/config --set-str CONFIG_LOCALVERSION '-local-foobars-fix-v1'
+
+  Build, install, and boot a kernel as described in *segment 1, section b* --
+  but this time omit the first command copying the build configuration over,
+  as that has been taken care of already.
+
+.. _introguide_bissbs:
+
+Step-by-step guide on how to verify bugs and bisect regressions
+===============================================================
+
+This guide describes how to set up your own Linux kernels for investigating bugs
+or regressions you intend to report. How far you want to follow the instructions
+depends on your issue:
+
+Execute all steps till the end of *segment 1* to **verify if your kernel problem
+is present in code supported by Linux kernel developers**. If it is, you are all
+set to report the bug -- unless it did not happen with earlier kernel versions,
+as then your want to at least continue with *segment 2* to **check if the issue
+qualifies as regression** which receive priority treatment. Depending on the
+outcome you then are ready to report a bug or submit a preliminary regression
+report; instead of the latter your could also head straight on and follow
+*segment 3* to **perform a bisection** for a full-fledged regression report
+developers are obliged to act upon.
+
+ :ref:`Preparations: set up everything to build your own kernels <introprep_bissbs>`.
+
+ :ref:`Segment 1: try to reproduce the problem with the latest codebase <introlatestcheck_bissbs>`.
+
+ :ref:`Segment 2: check if the kernels you build work fine <introworkingcheck_bissbs>`.
+
+ :ref:`Segment 3: perform a bisection and validate the result <introbisect_bissbs>`.
+
+ :ref:`Complementary tasks: cleanup during and after following this guide <introclosure_bissbs>`.
+
+ :ref:`Optional tasks: test reverts, patches, or later versions <introoptional_bissbs>`.
+
+The steps in each segment illustrate the important aspects of the process, while
+a comprehensive reference section holds additional details for almost all of the
+steps. The reference section sometimes also outlines alternative approaches,
+pitfalls, as well as problems that might occur at the particular step -- and how
+to get things rolling again.
+
+For further details on how to report Linux kernel issues or regressions check
+out Documentation/admin-guide/reporting-issues.rst, which works in conjunction
+with this document. It among others explains why you need to verify bugs with
+the latest 'mainline' kernel (e.g. versions like 6.0, 6.1-rc1, or 6.1-rc6),
+even if you face a problem with a kernel from a 'stable/longterm' series
+(say 6.0.13).
+
+For users facing a regression that document also explains why sending a
+preliminary report after segment 2 might be wise, as the regression and its
+culprit might be known already. For further details on what actually qualifies
+as a regression check out Documentation/admin-guide/reporting-regressions.rst.
+
+If you run into any problems while following this guide or have ideas how to
+improve it, :ref:`please let the kernel developers know <submit_improvements_vbbr>`.
+
+.. _introprep_bissbs:
+
+Preparations: set up everything to build your own kernels
+---------------------------------------------------------
+
+The following steps lay the groundwork for all further tasks.
+
+Note: the instructions assume you are building and testing on the same
+machine; if you want to compile the kernel on another system, check
+:ref:`Build kernels on a different machine <buildhost_bis>` below.
+
+.. _backup_bissbs:
+
+* Create a fresh backup and put system repair and restore tools at hand, just
+  to be prepared for the unlikely case of something going sideways.
+
+  [:ref:`details <backup_bisref>`]
+
+.. _vanilla_bissbs:
+
+* Remove all software that depends on externally developed kernel drivers or
+  builds them automatically. That includes but is not limited to DKMS, openZFS,
+  VirtualBox, and Nvidia's graphics drivers (including the GPLed kernel module).
+
+  [:ref:`details <vanilla_bisref>`]
+
+.. _secureboot_bissbs:
+
+* On platforms with 'Secure Boot' or similar solutions, prepare everything to
+  ensure the system will permit your self-compiled kernel to boot. The
+  quickest and easiest way to achieve this on commodity x86 systems is to
+  disable such techniques in the BIOS setup utility; alternatively, remove
+  their restrictions through a process initiated by
+  ``mokutil --disable-validation``.
+
+  [:ref:`details <secureboot_bisref>`]
+
+.. _rangecheck_bissbs:
+
+* Determine the kernel versions considered 'good' and 'bad' throughout this
+  guide:
+
+  * Do you follow this guide to verify if a bug is present in the code the
+    primary developers care for? Then consider the version of the newest kernel
+    you regularly use currently as 'good' (e.g. 6.0, 6.0.13, or 6.1-rc2).
+
+  * Do you face a regression, e.g. something broke or works worse after
+    switching to a newer kernel version? In that case it depends on the version
+    range during which the problem appeared:
+
+    * Something regressed when updating from a stable/longterm release
+      (say 6.0.13) to a newer mainline series (like 6.1-rc7 or 6.1) or a
+      stable/longterm version based on one (say 6.1.5)? Then consider the
+      mainline release your working kernel is based on to be the 'good'
+      version (e.g. 6.0) and the first version to be broken as the 'bad' one
+      (e.g. 6.1-rc7, 6.1, or 6.1.5). Note, at this point it is merely assumed
+      that 6.0 is fine; this hypothesis will be checked in segment 2.
+
+    * Something regressed when switching from one mainline version (say 6.0) to
+      a later one (like 6.1-rc1) or a stable/longterm release based on it
+      (say 6.1.5)? Then regard the last working version (e.g. 6.0) as 'good' and
+      the first broken (e.g. 6.1-rc1 or 6.1.5) as 'bad'.
+
+    * Something regressed when updating within a stable/longterm series (say
+      from 6.0.13 to 6.0.15)? Then consider those versions as 'good' and 'bad'
+      (e.g. 6.0.13 and 6.0.15), as you need to bisect within that series.
+
+  *Note, do not confuse 'good' version with 'working' kernel; the latter term
+  throughout this guide will refer to the last kernel that has been working
+  fine.*
+
+  [:ref:`details <rangecheck_bisref>`]
+
+.. _bootworking_bissbs:
+
+* Boot into the 'working' kernel and briefly use the apparently broken feature.
+
+  [:ref:`details <bootworking_bisref>`]
+
+.. _diskspace_bissbs:
+
+* Ensure to have enough free space for building Linux. 15 Gigabyte in your home
+  directory should typically suffice. If you have less available, be sure to pay
+  attention to later steps about retrieving the Linux sources and handling of
+  debug symbols: both explain approaches reducing the amount of space, which
+  should allow you to master these tasks with about 4 Gigabytes free space.
+
+  [:ref:`details <diskspace_bisref>`]
+
+.. _buildrequires_bissbs:
+
+* Install all software required to build a Linux kernel. Often you will need:
+  'bc', 'binutils' ('ld' et al.), 'bison', 'flex', 'gcc', 'git', 'openssl',
+  'pahole', 'perl', and the development headers for 'libelf' and 'openssl'. The
+  reference section shows how to quickly install those on various popular Linux
+  distributions.
+
+  [:ref:`details <buildrequires_bisref>`]
+
+.. _sources_bissbs:
+
+* Retrieve the mainline Linux sources; then change into the directory holding
+  them, as all further commands in this guide are meant to be executed from
+  there.
+
+  *Note, the following describe how to retrieve the sources using a full
+  mainline clone, which downloads about 2,75 GByte as of early 2024. The*
+  :ref:`reference section describes two alternatives <sources_bisref>` *:
+  one downloads less than 500 MByte, the other works better with unreliable
+  internet connections.*
+
+  Execute the following command to retrieve a fresh mainline codebase while
+  preparing things to add branches for stable/longterm series later::
+
+    git clone -o mainline --no-checkout \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ~/linux/
+    cd ~/linux/
+    git remote add -t master stable \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
+
+  [:ref:`details <sources_bisref>`]
+
+.. _stablesources_bissbs:
+
+* Is one of the versions you earlier established as 'good' or 'bad' a stable or
+  longterm release (say 6.1.5)? Then download the code for the series it belongs
+  to ('linux-6.1.y' in this example)::
+
+    git remote set-branches --add stable linux-6.1.y
+    git fetch stable
+
+.. _oldconfig_bissbs:
+
+* Start preparing a kernel build configuration (the '.config' file).
+
+  Before doing so, ensure you are still running the 'working' kernel an earlier
+  step told you to boot; if you are unsure, check the current kernelrelease
+  identifier using ``uname -r``.
+
+  Afterwards check out the source code for the version earlier established as
+  'good'. In the following example command this is assumed to be 6.0; note that
+  the version number in this and all later Git commands needs to be prefixed
+  with a 'v'::
+
+    git switch --discard-changes --detach v6.0
+
+  Now create a build configuration file::
+
+    make olddefconfig
+
+  The kernel build scripts then will try to locate the build configuration file
+  for the running kernel and then adjust it for the needs of the kernel sources
+  you checked out. While doing so, it will print a few lines you need to check.
+
+  Look out for a line starting with '# using defaults found in'. It should be
+  followed by a path to a file in '/boot/' that contains the release identifier
+  of your currently working kernel. If the line instead continues with something
+  like 'arch/x86/configs/x86_64_defconfig', then the build infra failed to find
+  the .config file for your running kernel -- in which case you have to put one
+  there manually, as explained in the reference section.
+
+  In case you can not find such a line, look for one containing '# configuration
+  written to .config'. If that's the case you have a stale build configuration
+  lying around. Unless you intend to use it, delete it; afterwards run
+  'make olddefconfig' again and check if it now picked up the right config file
+  as base.
+
+  [:ref:`details <oldconfig_bisref>`]
+
+.. _localmodconfig_bissbs:
+
+* Disable any kernel modules apparently superfluous for your setup. This is
+  optional, but especially wise for bisections, as it speeds up the build
+  process enormously -- at least unless the .config file picked up in the
+  previous step was already tailored to your and your hardware needs, in which
+  case you should skip this step.
+
+  To prepare the trimming, connect external hardware you occasionally use (USB
+  keys, tokens, ...), quickly start a VM, and bring up VPNs. And if you rebooted
+  since you started that guide, ensure that you tried using the feature causing
+  trouble since you started the system. Only then trim your .config::
+
+     yes '' | make localmodconfig
+
+  There is a catch to this, as the 'apparently' in initial sentence of this step
+  and the preparation instructions already hinted at:
+
+  The 'localmodconfig' target easily disables kernel modules for features only
+  used occasionally -- like modules for external peripherals not yet connected
+  since booting, virtualization software not yet utilized, VPN tunnels, and a
+  few other things. That's because some tasks rely on kernel modules Linux only
+  loads when you execute tasks like the aforementioned ones for the first time.
+
+  This drawback of localmodconfig is nothing you should lose sleep over, but
+  something to keep in mind: if something is misbehaving with the kernels built
+  during this guide, this is most likely the reason. You can reduce or nearly
+  eliminate the risk with tricks outlined in the reference section; but when
+  building a kernel just for quick testing purposes this is usually not worth
+  spending much effort on, as long as it boots and allows to properly test the
+  feature that causes trouble.
+
+  [:ref:`details <localmodconfig_bisref>`]
+
+.. _tagging_bissbs:
+
+* Ensure all the kernels you will build are clearly identifiable using a special
+  tag and a unique version number::
+
+    ./scripts/config --set-str CONFIG_LOCALVERSION '-local'
+    ./scripts/config -e CONFIG_LOCALVERSION_AUTO
+
+  [:ref:`details <tagging_bisref>`]
+
+.. _debugsymbols_bissbs:
+
+* Decide how to handle debug symbols.
+
+  In the context of this document it is often wise to enable them, as there is a
+  decent chance you will need to decode a stack trace from a 'panic', 'Oops',
+  'warning', or 'BUG'::
+
+    ./scripts/config -d DEBUG_INFO_NONE -e KALLSYMS_ALL -e DEBUG_KERNEL \
+      -e DEBUG_INFO -e DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT -e KALLSYMS
+
+  But if you are extremely short on storage space, you might want to disable
+  debug symbols instead::
+
+    ./scripts/config -d DEBUG_INFO -d DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT \
+      -d DEBUG_INFO_DWARF4 -d DEBUG_INFO_DWARF5 -e CONFIG_DEBUG_INFO_NONE
+
+  [:ref:`details <debugsymbols_bisref>`]
+
+.. _configmods_bissbs:
+
+* Check if you may want or need to adjust some other kernel configuration
+  options:
+
+  * Are you running Debian? Then you want to avoid known problems by performing
+    additional adjustments explained in the reference section.
+
+    [:ref:`details <configmods_distros_bisref>`].
+
+  * If you want to influence other aspects of the configuration, do so now using
+    your preferred tool. Note, to use make targets like 'menuconfig' or
+    'nconfig', you will need to install the development files of ncurses; for
+    'xconfig' you likewise need the Qt5 or Qt6 headers.
+
+    [:ref:`details <configmods_individual_bisref>`].
+
+.. _saveconfig_bissbs:
+
+* Reprocess the .config after the latest adjustments and store it in a safe
+  place::
+
+     make olddefconfig
+     cp .config ~/kernel-config-working
+
+  [:ref:`details <saveconfig_bisref>`]
+
+.. _introlatestcheck_bissbs:
+
+Segment 1: try to reproduce the problem with the latest codebase
+----------------------------------------------------------------
+
+The following steps verify if the problem occurs with the code currently
+supported by developers. In case you face a regression, it also checks that the
+problem is not caused by some .config change, as reporting the issue then would
+be a waste of time. [:ref:`details <introlatestcheck_bisref>`]
+
+.. _checkoutmaster_bissbs:
+
+* Check out the latest Linux codebase.
+
+  * Are your 'good' and 'bad' versions from the same stable or longterm series?
+    Then check the `front page of kernel.org <https://kernel.org/>`_: if it
+    lists a release from that series without an '[EOL]' tag, checkout the series
+    latest version ('linux-6.1.y' in the following example)::
+
+      cd ~/linux/
+      git switch --discard-changes --detach stable/linux-6.1.y
+
+    Your series is unsupported, if is not listed or carrying a 'end of life'
+    tag. In that case you might want to check if a successor series (say
+    linux-6.2.y) or mainline (see next point) fix the bug.
+
+  * In all other cases, run::
+
+      cd ~/linux/
+      git switch --discard-changes --detach mainline/master
+
+  [:ref:`details <checkoutmaster_bisref>`]
+
+.. _build_bissbs:
+
+* Build the image and the modules of your first kernel using the config file you
+  prepared::
+
+    cp ~/kernel-config-working .config
+    make olddefconfig
+    make -j $(nproc --all)
+
+  If you want your kernel packaged up as deb, rpm, or tar file, see the
+  reference section for alternatives, which obviously will require other
+  steps to install as well.
+
+  [:ref:`details <build_bisref>`]
+
+.. _install_bissbs:
+
+* Install your newly built kernel.
+
+  Before doing so, consider checking if there is still enough space for it::
+
+    df -h /boot/ /lib/modules/
+
+  For now assume 150 MByte in /boot/ and 200 in /lib/modules/ will suffice; how
+  much your kernels actually require will be determined later during this guide.
+
+  Now install the kernel's modules and its image, which will be stored in
+  parallel to the your Linux distribution's kernels::
+
+    sudo make modules_install
+    command -v installkernel && sudo make install
+
+  The second command ideally will take care of three steps required at this
+  point: copying the kernel's image to /boot/, generating an initramfs, and
+  adding an entry for both to the boot loader's configuration.
+
+  Sadly some distributions (among them Arch Linux, its derivatives, and many
+  immutable Linux distributions) will perform none or only some of those tasks.
+  You therefore want to check if all of them were taken care of and manually
+  perform those that were not. The reference section provides further details on
+  that; your distribution's documentation might help, too.
+
+  Once you figured out the steps needed at this point, consider writing them
+  down: if you will build more kernels as described in segment 2 and 3, you will
+  have to perform those again after executing ``command -v installkernel [...]``.
+
+  [:ref:`details <install_bisref>`]
+
+.. _storagespace_bissbs:
+
+* In case you plan to follow this guide further, check how much storage space
+  the kernel, its modules, and other related files like the initramfs consume::
+
+    du -ch /boot/*$(make -s kernelrelease)* | tail -n 1
+    du -sh /lib/modules/$(make -s kernelrelease)/
+
+  Write down or remember those two values for later: they enable you to prevent
+  running out of disk space accidentally during a bisection.
+
+  [:ref:`details <storagespace_bisref>`]
+
+.. _kernelrelease_bissbs:
+
+* Show and store the kernelrelease identifier of the kernel you just built::
+
+    make -s kernelrelease | tee -a ~/kernels-built
+
+  Remember the identifier momentarily, as it will help you pick the right kernel
+  from the boot menu upon restarting.
+
+* Reboot into your newly built kernel. To ensure your actually started the one
+  you just built, you might want to verify if the output of these commands
+  matches::
+
+    tail -n 1 ~/kernels-built
+    uname -r
+
+.. _tainted_bissbs:
+
+* Check if the kernel marked itself as 'tainted'::
+
+    cat /proc/sys/kernel/tainted
+
+  If that command does not return '0', check the reference section, as the cause
+  for this might interfere with your testing.
+
+  [:ref:`details <tainted_bisref>`]
+
+.. _recheckbroken_bissbs:
+
+* Verify if your bug occurs with the newly built kernel. If it does not, check
+  out the instructions in the reference section to ensure nothing went sideways
+  during your tests.
+
+  [:ref:`details <recheckbroken_bisref>`]
+
+.. _recheckstablebroken_bissbs:
+
+* Did you just built a stable or longterm kernel? And were you able to reproduce
+  the regression with it? Then you should test the latest mainline codebase as
+  well, because the result determines which developers the bug must be submitted
+  to.
+
+  To prepare that test, check out current mainline::
+
+    cd ~/linux/
+    git switch --discard-changes --detach mainline/master
+
+  Now use the checked out code to build and install another kernel using the
+  commands the earlier steps already described in more detail::
+
+    cp ~/kernel-config-working .config
+    make olddefconfig
+    make -j $(nproc --all)
+    # * Check if the free space suffices holding another kernel:
+    df -h /boot/ /lib/modules/
+    sudo make modules_install
+    command -v installkernel && sudo make install
+    make -s kernelrelease | tee -a ~/kernels-built
+    reboot
+
+  Confirm you booted the kernel you intended to start and check its tainted
+  status::
+
+    tail -n 1 ~/kernels-built
+    uname -r
+    cat /proc/sys/kernel/tainted
+
+  Now verify if this kernel is showing the problem. If it does, then you need
+  to report the bug to the primary developers; if it does not, report it to the
+  stable team. See Documentation/admin-guide/reporting-issues.rst for details.
+
+  [:ref:`details <recheckstablebroken_bisref>`]
+
+Do you follow this guide to verify if a problem is present in the code
+currently supported by Linux kernel developers? Then you are done at this
+point. If you later want to remove the kernel you just built, check out
+:ref:`Complementary tasks: cleanup during and after following this guide <introclosure_bissbs>`.
+
+In case you face a regression, move on and execute at least the next segment
+as well.
+
+.. _introworkingcheck_bissbs:
+
+Segment 2: check if the kernels you build work fine
+---------------------------------------------------
+
+In case of a regression, you now want to ensure the trimmed configuration file
+you created earlier works as expected; a bisection with the .config file
+otherwise would be a waste of time. [:ref:`details <introworkingcheck_bisref>`]
+
+.. _recheckworking_bissbs:
+
+* Build your own variant of the 'working' kernel and check if the feature that
+  regressed works as expected with it.
+
+  Start by checking out the sources for the version earlier established as
+  'good' (once again assumed to be 6.0 here)::
+
+    cd ~/linux/
+    git switch --discard-changes --detach v6.0
+
+  Now use the checked out code to configure, build, and install another kernel
+  using the commands the previous subsection explained in more detail::
+
+    cp ~/kernel-config-working .config
+    make olddefconfig
+    make -j $(nproc --all)
+    # * Check if the free space suffices holding another kernel:
+    df -h /boot/ /lib/modules/
+    sudo make modules_install
+    command -v installkernel && sudo make install
+    make -s kernelrelease | tee -a ~/kernels-built
+    reboot
+
+  When the system booted, you may want to verify once again that the
+  kernel you started is the one you just built::
+
+    tail -n 1 ~/kernels-built
+    uname -r
+
+  Now check if this kernel works as expected; if not, consult the reference
+  section for further instructions.
+
+  [:ref:`details <recheckworking_bisref>`]
+
+.. _introbisect_bissbs:
+
+Segment 3: perform the bisection and validate the result
+--------------------------------------------------------
+
+With all the preparations and precaution builds taken care of, you are now ready
+to begin the bisection. This will make you build quite a few kernels -- usually
+about 15 in case you encountered a regression when updating to a newer series
+(say from 6.0.13 to 6.1.5). But do not worry, due to the trimmed build
+configuration created earlier this works a lot faster than many people assume:
+overall on average it will often just take about 10 to 15 minutes to compile
+each kernel on commodity x86 machines.
+
+.. _bisectstart_bissbs:
+
+* Start the bisection and tell Git about the versions earlier established as
+  'good' (6.0 in the following example command) and 'bad' (6.1.5)::
+
+    cd ~/linux/
+    git bisect start
+    git bisect good v6.0
+    git bisect bad v6.1.5
+
+  [:ref:`details <bisectstart_bisref>`]
+
+.. _bisectbuild_bissbs:
+
+* Now use the code Git checked out to build, install, and boot a kernel using
+  the commands introduced earlier::
+
+    cp ~/kernel-config-working .config
+    make olddefconfig
+    make -j $(nproc --all)
+    # * Check if the free space suffices holding another kernel:
+    df -h /boot/ /lib/modules/
+    sudo make modules_install
+    command -v installkernel && sudo make install
+    make -s kernelrelease | tee -a ~/kernels-built
+    reboot
+
+  If compilation fails for some reason, run ``git bisect skip`` and restart
+  executing the stack of commands from the beginning.
+
+  In case you skipped the 'test latest codebase' step in the guide, check its
+  description as for why the 'df [...]' and 'make -s kernelrelease [...]'
+  commands are here.
+
+  Important note: the latter command from this point on will print release
+  identifiers that might look odd or wrong to you -- which they are not, as it's
+  totally normal to see release identifiers like '6.0-rc1-local-gcafec0cacaca0'
+  if you bisect between versions 6.1 and 6.2 for example.
+
+  [:ref:`details <bisectbuild_bisref>`]
+
+.. _bisecttest_bissbs:
+
+* Now check if the feature that regressed works in the kernel you just built.
+
+  You again might want to start by making sure the kernel you booted is the one
+  you just built::
+
+    cd ~/linux/
+    tail -n 1 ~/kernels-built
+    uname -r
+
+  Now verify if the feature that regressed works at this kernel bisection point.
+  If it does, run this::
+
+    git bisect good
+
+  If it does not, run this::
+
+    git bisect bad
+
+  Be sure about what you tell Git, as getting this wrong just once will send the
+  rest of the bisection totally off course.
+
+  While the bisection is ongoing, Git will use the information you provided to
+  find and check out another bisection point for you to test. While doing so, it
+  will print something like 'Bisecting: 675 revisions left to test after this
+  (roughly 10 steps)' to indicate how many further changes it expects to be
+  tested. Now build and install another kernel using the instructions from the
+  previous step; afterwards follow the instructions in this step again.
+
+  Repeat this again and again until you finish the bisection -- that's the case
+  when Git after tagging a change as 'good' or 'bad' prints something like
+  'cafecaca0c0dacafecaca0c0dacafecaca0c0da is the first bad commit'; right
+  afterwards it will show some details about the culprit including the patch
+  description of the change. The latter might fill your terminal screen, so you
+  might need to scroll up to see the message mentioning the culprit;
+  alternatively, run ``git bisect log > ~/bisection-log``.
+
+  [:ref:`details <bisecttest_bisref>`]
+
+.. _bisectlog_bissbs:
+
+* Store Git's bisection log and the current .config file in a safe place before
+  telling Git to reset the sources to the state before the bisection::
+
+    cd ~/linux/
+    git bisect log > ~/bisection-log
+    cp .config ~/bisection-config-culprit
+    git bisect reset
+
+  [:ref:`details <bisectlog_bisref>`]
+
+.. _revert_bissbs:
+
+* Try reverting the culprit on top of latest mainline to see if this fixes your
+  regression.
+
+  This is optional, as it might be impossible or hard to realize. The former is
+  the case, if the bisection determined a merge commit as the culprit; the
+  latter happens if other changes depend on the culprit. But if the revert
+  succeeds, it is worth building another kernel, as it validates the result of
+  a bisection, which can easily deroute; it furthermore will let kernel
+  developers know, if they can resolve the regression with a quick revert.
+
+  Begin by checking out the latest codebase depending on the range you bisected:
+
+  * Did you face a regression within a stable/longterm series (say between
+    6.0.13 and 6.0.15) that does not happen in mainline? Then check out the
+    latest codebase for the affected series like this::
+
+      git fetch stable
+      git switch --discard-changes --detach linux-6.0.y
+
+  * In all other cases check out latest mainline::
+
+      git fetch mainline
+      git switch --discard-changes --detach mainline/master
+
+    If you bisected a regression within a stable/longterm series that also
+    happens in mainline, there is one more thing to do: look up the mainline
+    commit-id. To do so, use a command like ``git show abcdcafecabcd`` to
+    view the patch description of the culprit. There will be a line near
+    the top which looks like 'commit cafec0cacaca0 upstream.' or
+    'Upstream commit cafec0cacaca0'; use that commit-id in the next command
+    and not the one the bisection blamed.
+
+  Now try reverting the culprit by specifying its commit id::
+
+    git revert --no-edit cafec0cacaca0
+
+  If that fails, give up trying and move on to the next step; if it works,
+  adjust the tag to facilitate the identification and prevent accidentally
+  overwriting another kernel::
+
+    cp ~/kernel-config-working .config
+    ./scripts/config --set-str CONFIG_LOCALVERSION '-local-cafec0cacaca0-reverted'
+
+  Build a kernel using the familiar command sequence, just without copying the
+  the base .config over::
+
+    make olddefconfig &&
+    make -j $(nproc --all)
+    # * Check if the free space suffices holding another kernel:
+    df -h /boot/ /lib/modules/
+    sudo make modules_install
+    command -v installkernel && sudo make install
+    make -s kernelrelease | tee -a ~/kernels-built
+    reboot
+
+  Now check one last time if the feature that made you perform a bisection works
+  with that kernel: if everything went well, it should not show the regression.
+
+  [:ref:`details <revert_bisref>`]
+
+.. _introclosure_bissbs:
+
+Complementary tasks: cleanup during and after the bisection
+-----------------------------------------------------------
+
+During and after following this guide you might want or need to remove some of
+the kernels you installed: the boot menu otherwise will become confusing or
+space might run out.
+
+.. _makeroom_bissbs:
+
+* To remove one of the kernels you installed, look up its 'kernelrelease'
+  identifier. This guide stores them in '~/kernels-built', but the following
+  command will print them as well::
+
+    ls -ltr /lib/modules/*-local*
+
+  You in most situations want to remove the oldest kernels built during the
+  actual bisection (e.g. segment 3 of this guide). The two ones you created
+  beforehand (e.g. to test the latest codebase and the version considered
+  'good') might become handy to verify something later -- thus better keep them
+  around, unless you are really short on storage space.
+
+  To remove the modules of a kernel with the kernelrelease identifier
+  '*6.0-rc1-local-gcafec0cacaca0*', start by removing the directory holding its
+  modules::
+
+    sudo rm -rf /lib/modules/6.0-rc1-local-gcafec0cacaca0
+
+  Afterwards try the following command::
+
+    sudo kernel-install -v remove 6.0-rc1-local-gcafec0cacaca0
+
+  On quite a few distributions this will delete all other kernel files installed
+  while also removing the kernel's entry from the boot menu. But on some
+  distributions kernel-install does not exist or leaves boot-loader entries or
+  kernel image and related files behind; in that case remove them as described
+  in the reference section.
+
+  [:ref:`details <makeroom_bisref>`]
+
+.. _finishingtouch_bissbs:
+
+* Once you have finished the bisection, do not immediately remove anything you
+  set up, as you might need a few things again. What is safe to remove depends
+  on the outcome of the bisection:
+
+  * Could you initially reproduce the regression with the latest codebase and
+    after the bisection were able to fix the problem by reverting the culprit on
+    top of the latest codebase? Then you want to keep those two kernels around
+    for a while, but safely remove all others with a '-local' in the release
+    identifier.
+
+  * Did the bisection end on a merge-commit or seems questionable for other
+    reasons? Then you want to keep as many kernels as possible around for a few
+    days: it's pretty likely that you will be asked to recheck something.
+
+  * In other cases it likely is a good idea to keep the following kernels around
+    for some time: the one built from the latest codebase, the one created from
+    the version considered 'good', and the last three or four you compiled
+    during the actual bisection process.
+
+  [:ref:`details <finishingtouch_bisref>`]
+
+.. _introoptional_bissbs:
+
+Optional: test reverts, patches, or later versions
+--------------------------------------------------
+
+While or after reporting a bug, you might want or potentially will be asked to
+test reverts, debug patches, proposed fixes, or other versions. In that case
+follow these instructions.
+
+* Update your Git clone and check out the latest code.
+
+  * In case you want to test mainline, fetch its latest changes before checking
+    its code out::
+
+      git fetch mainline
+      git switch --discard-changes --detach mainline/master
+
+  * In case you want to test a stable or longterm kernel, first add the branch
+    holding the series you are interested in (6.2 in the example), unless you
+    already did so earlier::
+
+      git remote set-branches --add stable linux-6.2.y
+
+    Then fetch the latest changes and check out the latest version from the
+    series::
+
+      git fetch stable
+      git switch --discard-changes --detach stable/linux-6.2.y
+
+* Copy your kernel build configuration over::
+
+    cp ~/kernel-config-working .config
+
+* Your next step depends on what you want to do:
+
+  * In case you just want to test the latest codebase, head to the next step,
+    you are already all set.
+
+  * In case you want to test if a revert fixes an issue, revert one or multiple
+    changes by specifying their commit ids::
+
+      git revert --no-edit cafec0cacaca0
+
+    Now give that kernel a special tag to facilitates its identification and
+    prevent accidentally overwriting another kernel::
+
+      ./scripts/config --set-str CONFIG_LOCALVERSION '-local-cafec0cacaca0-reverted'
+
+  * In case you want to test a patch, store the patch in a file like
+    '/tmp/foobars-proposed-fix-v1.patch' and apply it like this::
+
+      git apply /tmp/foobars-proposed-fix-v1.patch
+
+    In case of multiple patches, repeat this step with the others.
+
+    Now give that kernel a special tag to facilitates its identification and
+    prevent accidentally overwriting another kernel::
+
+    ./scripts/config --set-str CONFIG_LOCALVERSION '-local-foobars-fix-v1'
+
+* Build a kernel using the familiar commands, just without copying the kernel
+  build configuration over, as that has been taken care of already::
+
+    make olddefconfig &&
+    make -j $(nproc --all)
+    # * Check if the free space suffices holding another kernel:
+    df -h /boot/ /lib/modules/
+    sudo make modules_install
+    command -v installkernel && sudo make install
+    make -s kernelrelease | tee -a ~/kernels-built
+    reboot
+
+* Now verify you booted the newly built kernel and check it.
+
+[:ref:`details <introoptional_bisref>`]
+
+.. _submit_improvements_vbbr:
+
+Conclusion
+----------
+
+You have reached the end of the step-by-step guide.
+
+Did you run into trouble following the step-by-step guide not cleared up by the
+reference section below? Did you spot errors? Or do you have ideas on how to
+improve the guide?
+
+If any of that applies, please let the developers know by sending a short note
+or a patch to Thorsten Leemhuis <linux@leemhuis.info> while ideally CCing the
+public Linux docs mailing list <linux-doc@vger.kernel.org>. Such feedback is
+vital to improve this text further, which is in everybody's interest, as it will
+enable more people to master the task described here.
+
+
+Reference section for the step-by-step guide
+============================================
+
+This section holds additional information for almost all the items in the above
+step-by-step guide.
+
+Preparations for building your own kernels
+------------------------------------------
+
+  *The steps in this section lay the groundwork for all further tests.*
+  [:ref:`... <introprep_bissbs>`]
+
+The steps in all later sections of this guide depend on those described here.
+
+[:ref:`back to step-by-step guide <introprep_bissbs>`].
+
+.. _backup_bisref:
+
+Prepare for emergencies
+~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Create a fresh backup and put system repair and restore tools at hand.*
+  [:ref:`... <backup_bissbs>`]
+
+Remember, you are dealing with computers, which sometimes do unexpected things
+-- especially if you fiddle with crucial parts like the kernel of an operating
+system. That's what you are about to do in this process. Hence, better prepare
+for something going sideways, even if that should not happen.
+
+[:ref:`back to step-by-step guide <backup_bissbs>`]
+
+.. _vanilla_bisref:
+
+Remove anything related to externally maintained kernel modules
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Remove all software that depends on externally developed kernel drivers or
+  builds them automatically.* [:ref:`...<vanilla_bissbs>`]
+
+Externally developed kernel modules can easily cause trouble during a bisection.
+
+But there is a more important reason why this guide contains this step: most
+kernel developers will not care about reports about regressions occurring with
+kernels that utilize such modules. That's because such kernels are not
+considered 'vanilla' anymore, as Documentation/admin-guide/reporting-issues.rst
+explains in more detail.
+
+[:ref:`back to step-by-step guide <vanilla_bissbs>`]
+
+.. _secureboot_bisref:
+
+Deal with techniques like Secure Boot
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *On platforms with 'Secure Boot' or similar techniques, prepare everything to
+  ensure the system will permit your self-compiled kernel to boot later.*
+  [:ref:`... <secureboot_bissbs>`]
+
+Many modern systems allow only certain operating systems to start; that's why
+they reject booting self-compiled kernels by default.
+
+You ideally deal with this by making your platform trust your self-built kernels
+with the help of a certificate. How to do that is not described
+here, as it requires various steps that would take the text too far away from
+its purpose; 'Documentation/admin-guide/module-signing.rst' and various web
+sides already explain everything needed in more detail.
+
+Temporarily disabling solutions like Secure Boot is another way to make your own
+Linux boot. On commodity x86 systems it is possible to do this in the BIOS Setup
+utility; the required steps vary a lot between machines and therefore cannot be
+described here.
+
+On mainstream x86 Linux distributions there is a third and universal option:
+disable all Secure Boot restrictions for your Linux environment. You can
+initiate this process by running ``mokutil --disable-validation``; this will
+tell you to create a one-time password, which is safe to write down. Now
+restart; right after your BIOS performed all self-tests the bootloader Shim will
+show a blue box with a message 'Press any key to perform MOK management'. Hit
+some key before the countdown exposes, which will open a menu. Choose 'Change
+Secure Boot state'. Shim's 'MokManager' will now ask you to enter three
+randomly chosen characters from the one-time password specified earlier. Once
+you provided them, confirm you really want to disable the validation.
+Afterwards, permit MokManager to reboot the machine.
+
+[:ref:`back to step-by-step guide <secureboot_bissbs>`]
+
+.. _bootworking_bisref:
+
+Boot the last kernel that was working
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Boot into the last working kernel and briefly recheck if the feature that
+  regressed really works.* [:ref:`...<bootworking_bissbs>`]
+
+This will make later steps that cover creating and trimming the configuration do
+the right thing.
+
+[:ref:`back to step-by-step guide <bootworking_bissbs>`]
+
+.. _diskspace_bisref:
+
+Space requirements
+~~~~~~~~~~~~~~~~~~
+
+  *Ensure to have enough free space for building Linux.*
+  [:ref:`... <diskspace_bissbs>`]
+
+The numbers mentioned are rough estimates with a big extra charge to be on the
+safe side, so often you will need less.
+
+If you have space constraints, be sure to hay attention to the :ref:`step about
+debug symbols' <debugsymbols_bissbs>` and its :ref:`accompanying reference
+section' <debugsymbols_bisref>`, as disabling then will reduce the consumed disk
+space by quite a few gigabytes.
+
+[:ref:`back to step-by-step guide <diskspace_bissbs>`]
+
+.. _rangecheck_bisref:
+
+Bisection range
+~~~~~~~~~~~~~~~
+
+  *Determine the kernel versions considered 'good' and 'bad' throughout this
+  guide.* [:ref:`...<rangecheck_bissbs>`]
+
+Establishing the range of commits to be checked is mostly straightforward,
+except when a regression occurred when switching from a release of one stable
+series to a release of a later series (e.g. from 6.0.13 to 6.1.5). In that case
+Git will need some hand holding, as there is no straight line of descent.
+
+That's because with the release of 6.0 mainline carried on to 6.1 while the
+stable series 6.0.y branched to the side. It's therefore theoretically possible
+that the issue you face with 6.1.5 only worked in 6.0.13, as it was fixed by a
+commit that went into one of the 6.0.y releases, but never hit mainline or the
+6.1.y series. Thankfully that normally should not happen due to the way the
+stable/longterm maintainers maintain the code. It's thus pretty safe to assume
+6.0 as a 'good' kernel. That assumption will be tested anyway, as that kernel
+will be built and tested in the segment '2' of this guide; Git would force you
+to do this as well, if you tried bisecting between 6.0.13 and 6.1.15.
+
+[:ref:`back to step-by-step guide <rangecheck_bissbs>`]
+
+.. _buildrequires_bisref:
+
+Install build requirements
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Install all software required to build a Linux kernel.*
+  [:ref:`...<buildrequires_bissbs>`]
+
+The kernel is pretty stand-alone, but besides tools like the compiler you will
+sometimes need a few libraries to build one. How to install everything needed
+depends on your Linux distribution and the configuration of the kernel you are
+about to build.
+
+Here are a few examples what you typically need on some mainstream
+distributions:
+
+* Arch Linux and derivatives::
+
+    sudo pacman --needed -S bc binutils bison flex gcc git kmod libelf openssl \
+      pahole perl zlib ncurses qt6-base
+
+* Debian, Ubuntu, and derivatives::
+
+    sudo apt install bc binutils bison dwarves flex gcc git kmod libelf-dev \
+      libssl-dev make openssl pahole perl-base pkg-config zlib1g-dev \
+      libncurses-dev qt6-base-dev g++
+
+* Fedora and derivatives::
+
+    sudo dnf install binutils \
+      /usr/bin/{bc,bison,flex,gcc,git,openssl,make,perl,pahole,rpmbuild} \
+      /usr/include/{libelf.h,openssl/pkcs7.h,zlib.h,ncurses.h,qt6/QtGui/QAction}
+
+* openSUSE and derivatives::
+
+    sudo zypper install bc binutils bison dwarves flex gcc git \
+      kernel-install-tools libelf-devel make modutils openssl openssl-devel \
+      perl-base zlib-devel rpm-build ncurses-devel qt6-base-devel
+
+These commands install a few packages that are often, but not always needed. You
+for example might want to skip installing the development headers for ncurses,
+which you will only need in case you later might want to adjust the kernel build
+configuration using make the targets 'menuconfig' or 'nconfig'; likewise omit
+the headers of Qt6 if you do not plan to adjust the .config using 'xconfig'.
+
+You furthermore might need additional libraries and their development headers
+for tasks not covered in this guide -- for example when building utilities from
+the kernel's tools/ directory.
+
+[:ref:`back to step-by-step guide <buildrequires_bissbs>`]
+
+.. _sources_bisref:
+
+Download the sources using Git
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Retrieve the Linux mainline sources.*
+  [:ref:`...<sources_bissbs>`]
+
+The step-by-step guide outlines how to download the Linux sources using a full
+Git clone of Linus' mainline repository. There is nothing more to say about
+that -- but there are two alternatives ways to retrieve the sources that might
+work better for you:
+
+* If you have an unreliable internet connection, consider
+  :ref:`using a 'Git bundle'<sources_bundle_bisref>`.
+
+* If downloading the complete repository would take too long or requires too
+  much storage space, consider :ref:`using a 'shallow
+  clone'<sources_shallow_bisref>`.
+
+.. _sources_bundle_bisref:
+
+Downloading Linux mainline sources using a bundle
+"""""""""""""""""""""""""""""""""""""""""""""""""
+
+Use the following commands to retrieve the Linux mainline sources using a
+bundle::
+
+    wget -c \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/clone.bundle
+    git clone --no-checkout clone.bundle ~/linux/
+    cd ~/linux/
+    git remote remove origin
+    git remote add mainline \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+    git fetch mainline
+    git remote add -t master stable \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
+
+In case the 'wget' command fails, just re-execute it, it will pick up where
+it left off.
+
+[:ref:`back to step-by-step guide <sources_bissbs>`]
+[:ref:`back to section intro <sources_bisref>`]
+
+.. _sources_shallow_bisref:
+
+Downloading Linux mainline sources using a shallow clone
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+First, execute the following command to retrieve the latest mainline codebase::
+
+    git clone -o mainline --no-checkout --depth 1 -b master \
+      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ~/linux/
+    cd ~/linux/
+    git remote add -t master stable \
+      https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
+
+Now deepen your clone's history to the second predecessor of the mainline
+release of your 'good' version. In case the latter are 6.0 or 6.0.13, 5.19 would
+be the first predecessor and 5.18 the second -- hence deepen the history up to
+that version::
+
+    git fetch --shallow-exclude=v5.18 mainline
+
+Afterwards add the stable Git repository as remote and all required stable
+branches as explained in the step-by-step guide.
+
+Note, shallow clones have a few peculiar characteristics:
+
+* For bisections the history needs to be deepened a few mainline versions
+  farther than it seems necessary, as explained above already. That's because
+  Git otherwise will be unable to revert or describe most of the commits within
+  a range (say 6.1..6.2), as they are internally based on earlier kernels
+  releases (like 6.0-rc2 or 5.19-rc3).
+
+* This document in most places uses ``git fetch`` with ``--shallow-exclude=``
+  to specify the earliest version you care about (or to be precise: its git
+  tag). You alternatively can use the parameter ``--shallow-since=`` to specify
+  an absolute (say ``'2023-07-15'``) or relative (``'12 months'``) date to
+  define the depth of the history you want to download. When using them while
+  bisecting mainline, ensure to deepen the history to at least 7 months before
+  the release of the mainline release your 'good' kernel is based on.
+
+* Be warned, when deepening your clone you might encounter an error like
+  'fatal: error in object: unshallow cafecaca0c0dacafecaca0c0dacafecaca0c0da'.
+  In that case run ``git repack -d`` and try again.
+
+[:ref:`back to step-by-step guide <sources_bissbs>`]
+[:ref:`back to section intro <sources_bisref>`]
+
+.. _oldconfig_bisref:
+
+Start defining the build configuration for your kernel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Start preparing a kernel build configuration (the '.config' file).*
+  [:ref:`... <oldconfig_bissbs>`]
+
+*Note, this is the first of multiple steps in this guide that create or modify
+build artifacts. The commands used in this guide store them right in the source
+tree to keep things simple. In case you prefer storing the build artifacts
+separately, create a directory like '~/linux-builddir/' and add the parameter
+``O=~/linux-builddir/`` to all make calls used throughout this guide. You will
+have to point other commands there as well -- among them the ``./scripts/config
+[...]`` commands, which will require ``--file ~/linux-builddir/.config`` to
+locate the right build configuration.*
+
+Two things can easily go wrong when creating a .config file as advised:
+
+* The oldconfig target will use a .config file from your build directory, if
+  one is already present there (e.g. '~/linux/.config'). That's totally fine if
+  that's what you intend (see next step), but in all other cases you want to
+  delete it. This for example is important in case you followed this guide
+  further, but due to problems come back here to redo the configuration from
+  scratch.
+
+* Sometimes olddefconfig is unable to locate the .config file for your running
+  kernel and will use defaults, as briefly outlined in the guide. In that case
+  check if your distribution ships the configuration somewhere and manually put
+  it in the right place (e.g. '~/linux/.config') if it does. On distributions
+  where /proc/config.gz exists this can be achieved using this command::
+
+    zcat /proc/config.gz > .config
+
+  Once you put it there, run ``make olddefconfig`` again to adjust it to the
+  needs of the kernel about to be built.
+
+Note, the olddefconfig target will set any undefined build options to their
+default value. If you prefer to set such configuration options manually, use
+``make oldconfig`` instead. Then for each undefined configuration option you
+will be asked how to proceed; in case you are unsure what to answer, simply hit
+'enter' to apply the default value. Note though that for bisections you normally
+want to go with the defaults, as you otherwise might enable a new feature that
+causes a problem looking like regressions (for example due to security
+restrictions).
+
+Occasionally odd things happen when trying to use a config file prepared for one
+kernel (say 6.1) on an older mainline release -- especially if it is much older
+(say 5.15). That's one of the reasons why the previous step in the guide told
+you to boot the kernel where everything works. If you manually add a .config
+file you thus want to ensure it's from the working kernel and not from a one
+that shows the regression.
+
+In case you want to build kernels for another machine, locate its kernel build
+configuration; usually ``ls /boot/config-$(uname -r)`` will print its name. Copy
+that file to the build machine and store it as ~/linux/.config; afterwards run
+``make olddefconfig`` to adjust it.
+
+[:ref:`back to step-by-step guide <oldconfig_bissbs>`]
+
+.. _localmodconfig_bisref:
+
+Trim the build configuration for your kernel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Disable any kernel modules apparently superfluous for your setup.*
+  [:ref:`... <localmodconfig_bissbs>`]
+
+As explained briefly in the step-by-step guide already: with localmodconfig it
+can easily happen that your self-built kernels will lack modules for tasks you
+did not perform at least once before utilizing this make target. That happens
+when a task requires kernel modules which are only autoloaded when you execute
+it for the first time. So when you never performed that task since starting your
+kernel the modules will not have been loaded -- and from localmodconfig's point
+of view look superfluous, which thus disables them to reduce the amount of code
+to be compiled.
+
+You can try to avoid this by performing typical tasks that often will autoload
+additional kernel modules: start a VM, establish VPN connections, loop-mount a
+CD/DVD ISO, mount network shares (CIFS, NFS, ...), and connect all external
+devices (2FA keys, headsets, webcams, ...) as well as storage devices with file
+systems you otherwise do not utilize (btrfs, ext4, FAT, NTFS, XFS, ...). But it
+is hard to think of everything that might be needed -- even kernel developers
+often forget one thing or another at this point.
+
+Do not let that risk bother you, especially when compiling a kernel only for
+testing purposes: everything typically crucial will be there. And if you forget
+something important you can turn on a missing feature manually later and quickly
+run the commands again to compile and install a kernel that has everything you
+need.
+
+But if you plan to build and use self-built kernels regularly, you might want to
+reduce the risk by recording which modules your system loads over the course of
+a few weeks. You can automate this with `modprobed-db
+<https://github.com/graysky2/modprobed-db>`_. Afterwards use ``LSMOD=<path>`` to
+point localmodconfig to the list of modules modprobed-db noticed being used::
+
+  yes '' | make LSMOD='${HOME}'/.config/modprobed.db localmodconfig
+
+That parameter also allows you to build trimmed kernels for another machine in
+case you copied a suitable .config over to use as base (see previous step). Just
+run ``lsmod > lsmod_foo-machine`` on that system and copy the generated file to
+your build's host home directory. Then run these commands instead of the one the
+step-by-step guide mentions::
+
+  yes '' | make LSMOD=~/lsmod_foo-machine localmodconfig
+
+[:ref:`back to step-by-step guide <localmodconfig_bissbs>`]
+
+.. _tagging_bisref:
+
+Tag the kernels about to be build
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Ensure all the kernels you will build are clearly identifiable using a
+  special tag and a unique version identifier.* [:ref:`... <tagging_bissbs>`]
+
+This allows you to differentiate your distribution's kernels from those created
+during this process, as the file or directories for the latter will contain
+'-local' in the name; it also helps picking the right entry in the boot menu and
+not lose track of you kernels, as their version numbers will look slightly
+confusing during the bisection.
+
+[:ref:`back to step-by-step guide <tagging_bissbs>`]
+
+.. _debugsymbols_bisref:
+
+Decide to enable or disable debug symbols
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Decide how to handle debug symbols.* [:ref:`... <debugsymbols_bissbs>`]
+
+Having debug symbols available can be important when your kernel throws a
+'panic', 'Oops', 'warning', or 'BUG' later when running, as then you will be
+able to find the exact place where the problem occurred in the code. But
+collecting and embedding the needed debug information takes time and consumes
+quite a bit of space: in late 2022 the build artifacts for a typical x86 kernel
+trimmed with localmodconfig consumed around 5 Gigabyte of space with debug
+symbols, but less than 1 when they were disabled. The resulting kernel image and
+modules are bigger as well, which increases storage requirements for /boot/ and
+load times.
+
+In case you want a small kernel and are unlikely to decode a stack trace later,
+you thus might want to disable debug symbols to avoid those downsides. If it
+later turns out that you need them, just enable them as shown and rebuild the
+kernel.
+
+You on the other hand definitely want to enable them for this process, if there
+is a decent chance that you need to decode a stack trace later. The section
+'Decode failure messages' in Documentation/admin-guide/reporting-issues.rst
+explains this process in more detail.
+
+[:ref:`back to step-by-step guide <debugsymbols_bissbs>`]
+
+.. _configmods_bisref:
+
+Adjust build configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Check if you may want or need to adjust some other kernel configuration
+  options:*
+
+Depending on your needs you at this point might want or have to adjust some
+kernel configuration options.
+
+.. _configmods_distros_bisref:
+
+Distro specific adjustments
+"""""""""""""""""""""""""""
+
+  *Are you running* [:ref:`... <configmods_bissbs>`]
+
+The following sections help you to avoid build problems that are known to occur
+when following this guide on a few commodity distributions.
+
+**Debian:**
+
+* Remove a stale reference to a certificate file that would cause your build to
+  fail::
+
+   ./scripts/config --set-str SYSTEM_TRUSTED_KEYS ''
+
+  Alternatively, download the needed certificate and make that configuration
+  option point to it, as `the Debian handbook explains in more detail
+  <https://debian-handbook.info/browse/stable/sect.kernel-compilation.html>`_
+  -- or generate your own, as explained in
+  Documentation/admin-guide/module-signing.rst.
+
+[:ref:`back to step-by-step guide <configmods_bissbs>`]
+
+.. _configmods_individual_bisref:
+
+Individual adjustments
+""""""""""""""""""""""
+
+  *If you want to influence the other aspects of the configuration, do so
+  now.* [:ref:`... <configmods_bissbs>`]
+
+At this point you can use a command like ``make menuconfig`` or ``make nconfig``
+to enable or disable certain features using a text-based user interface; to use
+a graphical configuration utility, run ``make xconfig`` instead. Both of them
+require development libraries from toolkits they are rely on (ncurses
+respectively Qt5 or Qt6); an error message will tell you if something required
+is missing.
+
+[:ref:`back to step-by-step guide <configmods_bissbs>`]
+
+.. _saveconfig_bisref:
+
+Put the .config file aside
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Reprocess the .config after the latest changes and store it in a safe place.*
+  [:ref:`... <saveconfig_bissbs>`]
+
+Put the .config you prepared aside, as you want to copy it back to the build
+directory every time during this guide before you start building another
+kernel. That's because going back and forth between different versions can alter
+.config files in odd ways; those occasionally cause side effects that could
+confuse testing or in some cases render the result of your bisection
+meaningless.
+
+[:ref:`back to step-by-step guide <saveconfig_bissbs>`]
+
+.. _introlatestcheck_bisref:
+
+Try to reproduce the problem with the latest codebase
+-----------------------------------------------------
+
+  *Verify the regression is not caused by some .config change and check if it
+  still occurs with the latest codebase.* [:ref:`... <introlatestcheck_bissbs>`]
+
+For some readers it might seem unnecessary to check the latest codebase at this
+point, especially if you did that already with a kernel prepared by your
+distributor or face a regression within a stable/longterm series. But it's
+highly recommended for these reasons:
+
+* You will run into any problems caused by your setup before you actually begin
+  a bisection. That will make it a lot easier to differentiate between 'this
+  most likely is some problem in my setup' and 'this change needs to be skipped
+  during the bisection, as the kernel sources at that stage contain an unrelated
+  problem that causes building or booting to fail'.
+
+* These steps will rule out if your problem is caused by some change in the
+  build configuration between the 'working' and the 'broken' kernel. This for
+  example can happen when your distributor enabled an additional security
+  feature in the newer kernel which was disabled or not yet supported by the
+  older kernel. That security feature might get into the way of something you
+  do -- in which case your problem from the perspective of the Linux kernel
+  upstream developers is not a regression, as
+  Documentation/admin-guide/reporting-regressions.rst explains in more detail.
+  You thus would waste your time if you'd try to bisect this.
+
+* If the cause for your regression was already fixed in the latest mainline
+  codebase, you'd perform the bisection for nothing. This holds true for a
+  regression you encountered with a stable/longterm release as well, as they are
+  often caused by problems in mainline changes that were backported -- in which
+  case the problem will have to be fixed in mainline first. Maybe it already was
+  fixed there and the fix is already in the process of being backported.
+
+* For regressions within a stable/longterm series it's furthermore crucial to
+  know if the issue is specific to that series or also happens in the mainline
+  kernel, as the report needs to be sent to different people:
+
+  * Regressions specific to a stable/longterm series are the stable team's
+    responsibility; mainline Linux developers might or might not care.
+
+  * Regressions also happening in mainline are something the regular Linux
+    developers and maintainers have to handle; the stable team does not care
+    and does not need to be involved in the report, they just should be told
+    to backport the fix once it's ready.
+
+  Your report might be ignored if you send it to the wrong party -- and even
+  when you get a reply there is a decent chance that developers tell you to
+  evaluate which of the two cases it is before they take a closer look.
+
+[:ref:`back to step-by-step guide <introlatestcheck_bissbs>`]
+
+.. _checkoutmaster_bisref:
+
+Check out the latest Linux codebase
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Check out the latest Linux codebase.*
+  [:ref:`... <checkoutmaster_bissbs>`]
+
+In case you later want to recheck if an ever newer codebase might fix the
+problem, remember to run that ``git fetch --shallow-exclude [...]`` command
+again mentioned earlier to update your local Git repository.
+
+[:ref:`back to step-by-step guide <checkoutmaster_bissbs>`]
+
+.. _build_bisref:
+
+Build your kernel
+~~~~~~~~~~~~~~~~~
+
+  *Build the image and the modules of your first kernel using the config file
+  you prepared.* [:ref:`... <build_bissbs>`]
+
+A lot can go wrong at this stage, but the instructions below will help you help
+yourself. Another subsection explains how to directly package your kernel up as
+deb, rpm or tar file.
+
+Dealing with build errors
+"""""""""""""""""""""""""
+
+When a build error occurs, it might be caused by some aspect of your machine's
+setup that often can be fixed quickly; other times though the problem lies in
+the code and can only be fixed by a developer. A close examination of the
+failure messages coupled with some research on the internet will often tell you
+which of the two it is. To perform such investigation, restart the build
+process like this::
+
+  make V=1
+
+The ``V=1`` activates verbose output, which might be needed to see the actual
+error. To make it easier to spot, this command also omits the ``-j $(nproc
+--all)`` used earlier to utilize every CPU core in the system for the job -- but
+this parallelism also results in some clutter when failures occur.
+
+After a few seconds the build process should run into the error again. Now try
+to find the most crucial line describing the problem. Then search the internet
+for the most important and non-generic section of that line (say 4 to 8 words);
+avoid or remove anything that looks remotely system-specific, like your username
+or local path names like ``/home/username/linux/``. First try your regular
+internet search engine with that string, afterwards search Linux kernel mailing
+lists via `lore.kernel.org/all/ <https://lore.kernel.org/all/>`_.
+
+This most of the time will find something that will explain what is wrong; quite
+often one of the hits will provide a solution for your problem, too. If you
+do not find anything that matches your problem, try again from a different angle
+by modifying your search terms or using another line from the error messages.
+
+In the end, most issues you run into have likely been encountered and
+reported by others already. That includes issues where the cause is not your
+system, but lies in the code. If you run into one of those, you might thus find
+a solution (e.g. a patch) or workaround for your issue, too.
+
+Package your kernel up
+""""""""""""""""""""""
+
+The step-by-step guide uses the default make targets (e.g. 'bzImage' and
+'modules' on x86) to build the image and the modules of your kernel, which later
+steps of the guide then install. You instead can also directly build everything
+and directly package it up by using one of the following targets:
+
+* ``make -j $(nproc --all) bindeb-pkg`` to generate a deb package
+
+* ``make -j $(nproc --all) binrpm-pkg`` to generate a rpm package
+
+* ``make -j $(nproc --all) tarbz2-pkg`` to generate a bz2 compressed tarball
+
+This is just a selection of available make targets for this purpose, see
+``make help`` for others. You can also use these targets after running
+``make -j $(nproc --all)``, as they will pick up everything already built.
+
+If you employ the targets to generate deb or rpm packages, ignore the
+step-by-step guide's instructions on installing and removing your kernel;
+instead install and remove the packages using the package utility for the format
+(e.g. dpkg and rpm) or a package management utility build on top of them (apt,
+aptitude, dnf/yum, zypper, ...). Be aware that the packages generated using
+these two make targets are designed to work on various distributions utilizing
+those formats, they thus will sometimes behave differently than your
+distribution's kernel packages.
+
+[:ref:`back to step-by-step guide <build_bissbs>`]
+
+.. _install_bisref:
+
+Put the kernel in place
+~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Install the kernel you just built.* [:ref:`... <install_bissbs>`]
+
+What you need to do after executing the command in the step-by-step guide
+depends on the existence and the implementation of ``/sbin/installkernel``
+executable on your distribution.
+
+If installkernel is found, the kernel's build system will delegate the actual
+installation of your kernel image to this executable, which then performs some
+or all of these tasks:
+
+* On almost all Linux distributions installkernel will store your kernel's
+  image in /boot/, usually as '/boot/vmlinuz-<kernelrelease_id>'; often it will
+  put a 'System.map-<kernelrelease_id>' alongside it.
+
+* On most distributions installkernel will then generate an 'initramfs'
+  (sometimes also called 'initrd'), which usually are stored as
+  '/boot/initramfs-<kernelrelease_id>.img' or
+  '/boot/initrd-<kernelrelease_id>'. Commodity distributions rely on this file
+  for booting, hence ensure to execute the make target 'modules_install' first,
+  as your distribution's initramfs generator otherwise will be unable to find
+  the modules that go into the image.
+
+* On some distributions installkernel will then add an entry for your kernel
+  to your bootloader's configuration.
+
+You have to take care of some or all of the tasks yourself, if your
+distribution lacks an installkernel script or does only handle part of them.
+Consult the distribution's documentation for details. If in doubt, install the
+kernel manually::
+
+   sudo install -m 0600 $(make -s image_name) /boot/vmlinuz-$(make -s kernelrelease)
+   sudo install -m 0600 System.map /boot/System.map-$(make -s kernelrelease)
+
+Now generate your initramfs using the tools your distribution provides for this
+process. Afterwards add your kernel to your bootloader configuration and reboot.
+
+[:ref:`back to step-by-step guide <install_bissbs>`]
+
+.. _storagespace_bisref:
+
+Storage requirements per kernel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Check how much storage space the kernel, its modules, and other related files
+  like the initramfs consume.* [:ref:`... <storagespace_bissbs>`]
+
+The kernels built during a bisection consume quite a bit of space in /boot/ and
+/lib/modules/, especially if you enabled debug symbols. That makes it easy to
+fill up volumes during a bisection -- and due to that even kernels which used to
+work earlier might fail to boot. To prevent that you will need to know how much
+space each installed kernel typically requires.
+
+Note, most of the time the pattern '/boot/*$(make -s kernelrelease)*' used in
+the guide will match all files needed to boot your kernel -- but neither the
+path nor the naming scheme are mandatory. On some distributions you thus will
+need to look in different places.
+
+[:ref:`back to step-by-step guide <storagespace_bissbs>`]
+
+.. _tainted_bisref:
+
+Check if your newly built kernel considers itself 'tainted'
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Check if the kernel marked itself as 'tainted'.*
+  [:ref:`... <tainted_bissbs>`]
+
+Linux marks itself as tainted when something happens that potentially leads to
+follow-up errors that look totally unrelated. That is why developers might
+ignore or react scantly to reports from tainted kernels -- unless of course the
+kernel set the flag right when the reported bug occurred.
+
+That's why you want check why a kernel is tainted as explained in
+Documentation/admin-guide/tainted-kernels.rst; doing so is also in your own
+interest, as your testing might be flawed otherwise.
+
+[:ref:`back to step-by-step guide <tainted_bissbs>`]
+
+.. _recheckbroken_bisref:
+
+Check the kernel built from a recent mainline codebase
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Verify if your bug occurs with the newly built kernel.*
+  [:ref:`... <recheckbroken_bissbs>`]
+
+There are a couple of reasons why your bug or regression might not show up with
+the kernel you built from the latest codebase. These are the most frequent:
+
+* The bug was fixed meanwhile.
+
+* What you suspected to be a regression was caused by a change in the build
+  configuration the provider of your kernel carried out.
+
+* Your problem might be a race condition that does not show up with your kernel;
+  the trimmed build configuration, a different setting for debug symbols, the
+  compiler used, and various other things can cause this.
+
+* In case you encountered the regression with a stable/longterm kernel it might
+  be a problem that is specific to that series; the next step in this guide will
+  check this.
+
+[:ref:`back to step-by-step guide <recheckbroken_bissbs>`]
+
+.. _recheckstablebroken_bisref:
+
+Check the kernel built from the latest stable/longterm codebase
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Are you facing a regression within a stable/longterm release, but failed to
+  reproduce it with the kernel you just built using the latest mainline sources?
+  Then check if the latest codebase for the particular series might already fix
+  the problem.* [:ref:`... <recheckstablebroken_bissbs>`]
+
+If this kernel does not show the regression either, there most likely is no need
+for a bisection.
+
+[:ref:`back to step-by-step guide <recheckstablebroken_bissbs>`]
+
+.. _introworkingcheck_bisref:
+
+Ensure the 'good' version is really working well
+------------------------------------------------
+
+  *Check if the kernels you build work fine.*
+  [:ref:`... <introworkingcheck_bissbs>`]
+
+This section will reestablish a known working base. Skipping it might be
+appealing, but is usually a bad idea, as it does something important:
+
+It will ensure the .config file you prepared earlier actually works as expected.
+That is in your own interest, as trimming the configuration is not foolproof --
+and you might be building and testing ten or more kernels for nothing before
+starting to suspect something might be wrong with the build configuration.
+
+That alone is reason enough to spend the time on this, but not the only reason.
+
+Many readers of this guide normally run kernels that are patched, use add-on
+modules, or both. Those kernels thus are not considered 'vanilla' -- therefore
+it's possible that the thing that regressed might never have worked in vanilla
+builds of the 'good' version in the first place.
+
+There is a third reason for those that noticed a regression between
+stable/longterm kernels of different series (e.g. 6.0.13..6.1.5): it will
+ensure the kernel version you assumed to be 'good' earlier in the process (e.g.
+6.0) actually is working.
+
+[:ref:`back to step-by-step guide <introworkingcheck_bissbs>`]
+
+.. _recheckworking_bisref:
+
+Build your own version of the 'good' kernel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Build your own variant of the working kernel and check if the feature that
+  regressed works as expected with it.* [:ref:`... <recheckworking_bissbs>`]
+
+In case the feature that broke with newer kernels does not work with your first
+self-built kernel, find and resolve the cause before moving on. There are a
+multitude of reasons why this might happen. Some ideas where to look:
+
+* Check the taint status and the output of ``dmesg``, maybe something unrelated
+  went wrong.
+
+* Maybe localmodconfig did something odd and disabled the module required to
+  test the feature? Then you might want to recreate a .config file based on the
+  one from the last working kernel and skip trimming it down; manually disabling
+  some features in the .config might work as well to reduce the build time.
+
+* Maybe it's not a kernel regression and something that is caused by some fluke,
+  a broken initramfs (also known as initrd), new firmware files, or an updated
+  userland software?
+
+* Maybe it was a feature added to your distributor's kernel which vanilla Linux
+  at that point never supported?
+
+Note, if you found and fixed problems with the .config file, you want to use it
+to build another kernel from the latest codebase, as your earlier tests with
+mainline and the latest version from an affected stable/longterm series were
+most likely flawed.
+
+[:ref:`back to step-by-step guide <recheckworking_bissbs>`]
+
+Perform a bisection and validate the result
+-------------------------------------------
+
+  *With all the preparations and precaution builds taken care of, you are now
+  ready to begin the bisection.* [:ref:`... <introbisect_bissbs>`]
+
+The steps in this segment perform and validate the bisection.
+
+[:ref:`back to step-by-step guide <introbisect_bissbs>`].
+
+.. _bisectstart_bisref:
+
+Start the bisection
+~~~~~~~~~~~~~~~~~~~
+
+  *Start the bisection and tell Git about the versions earlier established as
+  'good' and 'bad'.* [:ref:`... <bisectstart_bissbs>`]
+
+This will start the bisection process; the last of the commands will make Git
+check out a commit round about half-way between the 'good' and the 'bad' changes
+for you to test.
+
+[:ref:`back to step-by-step guide <bisectstart_bissbs>`]
+
+.. _bisectbuild_bisref:
+
+Build a kernel from the bisection point
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Build, install, and boot a kernel from the code Git checked out using the
+  same commands you used earlier.* [:ref:`... <bisectbuild_bissbs>`]
+
+There are two things worth of note here:
+
+* Occasionally building the kernel will fail or it might not boot due some
+  problem in the code at the bisection point. In that case run this command::
+
+    git bisect skip
+
+  Git will then check out another commit nearby which with a bit of luck should
+  work better. Afterwards restart executing this step.
+
+* Those slightly odd looking version identifiers can happen during bisections,
+  because the Linux kernel subsystems prepare their changes for a new mainline
+  release (say 6.2) before its predecessor (e.g. 6.1) is finished. They thus
+  base them on a somewhat earlier point like 6.1-rc1 or even 6.0 -- and then
+  get merged for 6.2 without rebasing nor squashing them once 6.1 is out. This
+  leads to those slightly odd looking version identifiers coming up during
+  bisections.
+
+[:ref:`back to step-by-step guide <bisectbuild_bissbs>`]
+
+.. _bisecttest_bisref:
+
+Bisection checkpoint
+~~~~~~~~~~~~~~~~~~~~
+
+  *Check if the feature that regressed works in the kernel you just built.*
+  [:ref:`... <bisecttest_bissbs>`]
+
+Ensure what you tell Git is accurate: getting it wrong just one time will bring
+the rest of the bisection totally off course, hence all testing after that point
+will be for nothing.
+
+[:ref:`back to step-by-step guide <bisecttest_bissbs>`]
+
+.. _bisectlog_bisref:
+
+Put the bisection log away
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Store Git's bisection log and the current .config file in a safe place.*
+  [:ref:`... <bisectlog_bissbs>`]
+
+As indicated above: declaring just one kernel wrongly as 'good' or 'bad' will
+render the end result of a bisection useless. In that case you'd normally have
+to restart the bisection from scratch. The log can prevent that, as it might
+allow someone to point out where a bisection likely went sideways -- and then
+instead of testing ten or more kernels you might only have to build a few to
+resolve things.
+
+The .config file is put aside, as there is a decent chance that developers might
+ask for it after you report the regression.
+
+[:ref:`back to step-by-step guide <bisectlog_bissbs>`]
+
+.. _revert_bisref:
+
+Try reverting the culprit
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *Try reverting the culprit on top of the latest codebase to see if this fixes
+  your regression.* [:ref:`... <revert_bissbs>`]
+
+This is an optional step, but whenever possible one you should try: there is a
+decent chance that developers will ask you to perform this step when you bring
+the bisection result up. So give it a try, you are in the flow already, building
+one more kernel shouldn't be a big deal at this point.
+
+The step-by-step guide covers everything relevant already except one slightly
+rare thing: did you bisected a regression that also happened with mainline using
+a stable/longterm series, but Git failed to revert the commit in mainline? Then
+try to revert the culprit in the affected stable/longterm series -- and if that
+succeeds, test that kernel version instead.
+
+[:ref:`back to step-by-step guide <revert_bissbs>`]
+
+Cleanup steps during and after following this guide
+---------------------------------------------------
+
+  *During and after following this guide you might want or need to remove some
+  of the kernels you installed.* [:ref:`... <introclosure_bissbs>`]
+
+The steps in this section describe clean-up procedures.
+
+[:ref:`back to step-by-step guide <introclosure_bissbs>`].
+
+.. _makeroom_bisref:
+
+Cleaning up during the bisection
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  *To remove one of the kernels you installed, look up its 'kernelrelease'
+  identifier.* [:ref:`... <makeroom_bissbs>`]
+
+The kernels you install during this process are easy to remove later, as its
+parts are only stored in two places and clearly identifiable. You thus do not
+need to worry to mess up your machine when you install a kernel manually (and
+thus bypass your distribution's packaging system): all parts of your kernels are
+relatively easy to remove later.
+
+One of the two places is a directory in /lib/modules/, which holds the modules
+for each installed kernel. This directory is named after the kernel's release
+identifier; hence, to remove all modules for one of the kernels you built,
+simply remove its modules directory in /lib/modules/.
+
+The other place is /boot/, where typically two up to five files will be placed
+during installation of a kernel. All of them usually contain the release name in
+their file name, but how many files and their exact names depend somewhat on
+your distribution's installkernel executable and its initramfs generator. On
+some distributions the ``kernel-install remove...`` command mentioned in the
+step-by-step guide will delete all of these files for you while also removing
+the menu entry for the kernel from your bootloader configuration. On others you
+have to take care of these two tasks yourself. The following command should
+interactively remove the three main files of a kernel with the release name
+'6.0-rc1-local-gcafec0cacaca0'::
+
+  rm -i /boot/{System.map,vmlinuz,initr}-6.0-rc1-local-gcafec0cacaca0
+
+Afterwards check for other files in /boot/ that have
+'6.0-rc1-local-gcafec0cacaca0' in their name and consider deleting them as well.
+Now remove the boot entry for the kernel from your bootloader's configuration;
+the steps to do that vary quite a bit between Linux distributions.
+
+Note, be careful with wildcards like '*' when deleting files or directories
+for kernels manually: you might accidentally remove files of a 6.0.13 kernel
+when all you want is to remove 6.0 or 6.0.1.
+
+[:ref:`back to step-by-step guide <makeroom_bissbs>`]
+
+Cleaning up after the bisection
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. _finishingtouch_bisref:
+
+  *Once you have finished the bisection, do not immediately remove anything
+  you set up, as you might need a few things again.*
+  [:ref:`... <finishingtouch_bissbs>`]
+
+When you are really short of storage space removing the kernels as described in
+the step-by-step guide might not free as much space as you would like. In that
+case consider running ``rm -rf ~/linux/*`` as well now. This will remove the
+build artifacts and the Linux sources, but will leave the Git repository
+(~/linux/.git/) behind -- a simple ``git reset --hard`` thus will bring the
+sources back.
+
+Removing the repository as well would likely be unwise at this point: there
+is a decent chance developers will ask you to build another kernel to
+perform additional tests -- like testing a debug patch or a proposed fix.
+Details on how to perform those can be found in the section :ref:`Optional
+tasks: test reverts, patches, or later versions <introoptional_bissbs>`.
+
+Additional tests are also the reason why you want to keep the
+~/kernel-config-working file around for a few weeks.
+
+[:ref:`back to step-by-step guide <finishingtouch_bissbs>`]
+
+.. _introoptional_bisref:
+
+Test reverts, patches, or later versions
+----------------------------------------
+
+  *While or after reporting a bug, you might want or potentially will be asked
+  to test reverts, patches, proposed fixes, or other versions.*
+  [:ref:`... <introoptional_bissbs>`]
+
+All the commands used in this section should be pretty straight forward, so
+there is not much to add except one thing: when setting a kernel tag as
+instructed, ensure it is not much longer than the one used in the example, as
+problems will arise if the kernelrelease identifier exceeds 63 characters.
+
+[:ref:`back to step-by-step guide <introoptional_bissbs>`].
+
+
+Additional information
+======================
+
+.. _buildhost_bis:
+
+Build kernels on a different machine
+------------------------------------
+
+To compile kernels on another system, slightly alter the step-by-step guide's
+instructions:
+
+* Start following the guide on the machine where you want to install and test
+  the kernels later.
+
+* After executing ':ref:`Boot into the working kernel and briefly use the
+  apparently broken feature <bootworking_bissbs>`', save the list of loaded
+  modules to a file using ``lsmod > ~/test-machine-lsmod``. Then locate the
+  build configuration for the running kernel (see ':ref:`Start defining the
+  build configuration for your kernel <oldconfig_bisref>`' for hints on where
+  to find it) and store it as '~/test-machine-config-working'. Transfer both
+  files to the home directory of your build host.
+
+* Continue the guide on the build host (e.g. with ':ref:`Ensure to have enough
+  free space for building [...] <diskspace_bissbs>`').
+
+* When you reach ':ref:`Start preparing a kernel build configuration[...]
+  <oldconfig_bissbs>`': before running ``make olddefconfig`` for the first time,
+  execute the following command to base your configuration on the one from the
+  test machine's 'working' kernel::
+
+    cp ~/test-machine-config-working ~/linux/.config
+
+* During the next step to ':ref:`disable any apparently superfluous kernel
+  modules <localmodconfig_bissbs>`' use the following command instead::
+
+    yes '' | make localmodconfig LSMOD=~/lsmod_foo-machine localmodconfig
+
+* Continue the guide, but ignore the instructions outlining how to compile,
+  install, and reboot into a kernel every time they come up. Instead build
+  like this::
+
+    cp ~/kernel-config-working .config
+    make olddefconfig &&
+    make -j $(nproc --all) targz-pkg
+
+  This will generate a gzipped tar file whose name is printed in the last
+  line shown; for example, a kernel with the kernelrelease identifier
+  '6.0.0-rc1-local-g928a87efa423' built for x86 machines usually will
+  be stored as '~/linux/linux-6.0.0-rc1-local-g928a87efa423-x86.tar.gz'.
+
+  Copy that file to your test machine's home directory.
+
+* Switch to the test machine to check if you have enough space to hold another
+  kernel. Then extract the file you transferred::
+
+    sudo tar -xvzf ~/linux-6.0.0-rc1-local-g928a87efa423-x86.tar.gz -C /
+
+  Afterwards :ref:`generate the initramfs and add the kernel to your boot
+  loader's configuration <install_bisref>`; on some distributions the following
+  command will take care of both these tasks::
+
+    sudo /sbin/installkernel 6.0.0-rc1-local-g928a87efa423 /boot/vmlinuz-6.0.0-rc1-local-g928a87efa423
+
+  Now reboot and ensure you started the intended kernel.
+
+This approach even works when building for another architecture: just install
+cross-compilers and add the appropriate parameters to every invocation of make
+(e.g. ``make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- [...]``).
+
+Additional reading material
+---------------------------
+
+* The `man page for 'git bisect' <https://git-scm.com/docs/git-bisect>`_ and
+  `fighting regressions with 'git bisect' <https://git-scm.com/docs/git-bisect-lk2009.html>`_
+  in the Git documentation.
+* `Working with git bisect <https://nathanchance.dev/posts/working-with-git-bisect/>`_
+  from kernel developer Nathan Chancellor.
+* `Using Git bisect to figure out when brokenness was introduced <http://webchick.net/node/99>`_.
+* `Fully automated bisecting with 'git bisect run' <https://lwn.net/Articles/317154>`_.
+
+..
+   end-of-content
+..
+   This document is maintained by Thorsten Leemhuis <linux@leemhuis.info>. If
+   you spot a typo or small mistake, feel free to let him know directly and
+   he'll fix it. You are free to do the same in a mostly informal way if you
+   want to contribute changes to the text -- but for copyright reasons please CC
+   linux-doc@vger.kernel.org and 'sign-off' your contribution as
+   Documentation/process/submitting-patches.rst explains in the section 'Sign
+   your work - the Developer's Certificate of Origin'.
+..
+   This text is available under GPL-2.0+ or CC-BY-4.0, as stated at the top
+   of the file. If you want to distribute this text under CC-BY-4.0 only,
+   please use 'The Linux kernel development community' for author attribution
+   and link this as source:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/admin-guide/verify-bugs-and-bisect-regressions.rst
+
+..
+   Note: Only the content of this RST file as found in the Linux kernel sources
+   is available under CC-BY-4.0, as versions of this text that were processed
+   (for example by the kernel's build system) might contain content taken from
+   files which use a more restrictive license.
diff --git a/Documentation/admin-guide/vga-softcursor.rst b/Documentation/admin-guide/vga-softcursor.rst
new file mode 100644
index 000000000..f52175457
--- /dev/null
+++ b/Documentation/admin-guide/vga-softcursor.rst
@@ -0,0 +1,62 @@
+Software cursor for VGA
+=======================
+
+by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
+and Martin Mares <mj@atrey.karlin.mff.cuni.cz>
+
+Linux now has some ability to manipulate cursor appearance.  Normally,
+you can set the size of hardware cursor.  You can now play a few new
+tricks: you can make your cursor look like a non-blinking red block,
+make it inverse background of the character it's over or to highlight
+that character and still choose whether the original hardware cursor
+should remain visible or not.  There may be other things I have never
+thought of.
+
+The cursor appearance is controlled by a ``<ESC>[?1;2;3c`` escape sequence
+where 1, 2 and 3 are parameters described below. If you omit any of them,
+they will default to zeroes.
+
+first Parameter
+	specifies cursor size::
+
+		0=default
+		1=invisible
+		2=underline,
+		...
+		8=full block
+		+ 16 if you want the software cursor to be applied
+		+ 32 if you want to always change the background color
+		+ 64 if you dislike having the background the same as the
+		     foreground.
+
+	Highlights are ignored for the last two flags.
+
+second parameter
+	selects character attribute bits you want to change
+	(by simply XORing them with the value of this parameter). On standard
+	VGA, the high four bits specify background and the low four the
+	foreground. In both groups, low three bits set color (as in normal
+	color codes used by the console) and the most significant one turns
+	on highlight (or sometimes blinking -- it depends on the configuration
+	of your VGA).
+
+third parameter
+	consists of character attribute bits you want to set.
+
+	Bit setting takes place before bit toggling, so you can simply clear a
+	bit by including it in both the set mask and the toggle mask.
+
+Examples
+--------
+
+To get normal blinking underline, use::
+
+	echo -e '\033[?2c'
+
+To get blinking block, use::
+
+	echo -e '\033[?6c'
+
+To get red non-blinking block, use::
+
+	echo -e '\033[?17;0;64c'
diff --git a/Documentation/admin-guide/video-output.rst b/Documentation/admin-guide/video-output.rst
new file mode 100644
index 000000000..56d6fa2e2
--- /dev/null
+++ b/Documentation/admin-guide/video-output.rst
@@ -0,0 +1,34 @@
+Video Output Switcher Control
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+2006 luming.yu@intel.com
+
+The output sysfs class driver provides an abstract video output layer that
+can be used to hook platform specific methods to enable/disable video output
+device through common sysfs interface. For example, on my IBM ThinkPad T42
+laptop, The ACPI video driver registered its output devices and read/write
+method for 'state' with output sysfs class. The user interface under sysfs is::
+
+  linux:/sys/class/video_output # tree .
+  .
+  |-- CRT0
+  |   |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+  |   |-- state
+  |   |-- subsystem -> ../../../class/video_output
+  |   `-- uevent
+  |-- DVI0
+  |   |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+  |   |-- state
+  |   |-- subsystem -> ../../../class/video_output
+  |   `-- uevent
+  |-- LCD0
+  |   |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+  |   |-- state
+  |   |-- subsystem -> ../../../class/video_output
+  |   `-- uevent
+  `-- TV0
+     |-- device -> ../../../devices/pci0000:00/0000:00:01.0
+     |-- state
+     |-- subsystem -> ../../../class/video_output
+     `-- uevent
+
diff --git a/Documentation/admin-guide/workload-tracing.rst b/Documentation/admin-guide/workload-tracing.rst
new file mode 100644
index 000000000..314e5f034
--- /dev/null
+++ b/Documentation/admin-guide/workload-tracing.rst
@@ -0,0 +1,623 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR CC-BY-4.0)
+
+======================================================
+Discovering Linux kernel subsystems used by a workload
+======================================================
+
+:Authors: - Shuah Khan <skhan@linuxfoundation.org>
+          - Shefali Sharma <sshefali021@gmail.com>
+:maintained-by: Shuah Khan <skhan@linuxfoundation.org>
+
+Key Points
+==========
+
+ * Understanding system resources necessary to build and run a workload
+   is important.
+ * Linux tracing and strace can be used to discover the system resources
+   in use by a workload. The completeness of the system usage information
+   depends on the completeness of coverage of a workload.
+ * Performance and security of the operating system can be analyzed with
+   the help of tools such as:
+   `perf <https://man7.org/linux/man-pages/man1/perf.1.html>`_,
+   `stress-ng <https://www.mankier.com/1/stress-ng>`_,
+   `paxtest <https://github.com/opntr/paxtest-freebsd>`_.
+ * Once we discover and understand the workload needs, we can focus on them
+   to avoid regressions and use it to evaluate safety considerations.
+
+Methodology
+===========
+
+`strace <https://man7.org/linux/man-pages/man1/strace.1.html>`_ is a
+diagnostic, instructional, and debugging tool and can be used to discover
+the system resources in use by a workload. Once we discover and understand
+the workload needs, we can focus on them to avoid regressions and use it
+to evaluate safety considerations. We use strace tool to trace workloads.
+
+This method of tracing using strace tells us the system calls invoked by
+the workload and doesn't include all the system calls that can be invoked
+by it. In addition, this tracing method tells us just the code paths within
+these system calls that are invoked. As an example, if a workload opens a
+file and reads from it successfully, then the success path is the one that
+is traced. Any error paths in that system call will not be traced. If there
+is a workload that provides full coverage of a workload then the method
+outlined here will trace and find all possible code paths. The completeness
+of the system usage information depends on the completeness of coverage of a
+workload.
+
+The goal is tracing a workload on a system running a default kernel without
+requiring custom kernel installs.
+
+How do we gather fine-grained system information?
+=================================================
+
+strace tool can be used to trace system calls made by a process and signals
+it receives. System calls are the fundamental interface between an
+application and the operating system kernel. They enable a program to
+request services from the kernel. For instance, the open() system call in
+Linux is used to provide access to a file in the file system. strace enables
+us to track all the system calls made by an application. It lists all the
+system calls made by a process and their resulting output.
+
+You can generate profiling data combining strace and perf record tools to
+record the events and information associated with a process. This provides
+insight into the process. "perf annotate" tool generates the statistics of
+each instruction of the program. This document goes over the details of how
+to gather fine-grained information on a workload's usage of system resources.
+
+We used strace to trace the perf, stress-ng, paxtest workloads to illustrate
+our methodology to discover resources used by a workload. This process can
+be applied to trace other workloads.
+
+Getting the system ready for tracing
+====================================
+
+Before we can get started we will show you how to get your system ready.
+We assume that you have a Linux distribution running on a physical system
+or a virtual machine. Most distributions will include strace command. Let’s
+install other tools that aren’t usually included to build Linux kernel.
+Please note that the following works on Debian based distributions. You
+might have to find equivalent packages on other Linux distributions.
+
+Install tools to build Linux kernel and tools in kernel repository.
+scripts/ver_linux is a good way to check if your system already has
+the necessary tools::
+
+  sudo apt-get install build-essential flex bison yacc
+  sudo apt install libelf-dev systemtap-sdt-dev libslang2-dev libperl-dev libdw-dev
+
+cscope is a good tool to browse kernel sources. Let's install it now::
+
+  sudo apt-get install cscope
+
+Install stress-ng and paxtest::
+
+  apt-get install stress-ng
+  apt-get install paxtest
+
+Workload overview
+=================
+
+As mentioned earlier, we used strace to trace perf bench, stress-ng and
+paxtest workloads to show how to analyze a workload and identify Linux
+subsystems used by these workloads. Let's start with an overview of these
+three workloads to get a better understanding of what they do and how to
+use them.
+
+perf bench (all) workload
+-------------------------
+
+The perf bench command contains multiple multi-threaded microkernel
+benchmarks for executing different subsystems in the Linux kernel and
+system calls. This allows us to easily measure the impact of changes,
+which can help mitigate performance regressions. It also acts as a common
+benchmarking framework, enabling developers to easily create test cases,
+integrate transparently, and use performance-rich tooling subsystems.
+
+Stress-ng netdev stressor workload
+----------------------------------
+
+stress-ng is used for performing stress testing on the kernel. It allows
+you to exercise various physical subsystems of the computer, as well as
+interfaces of the OS kernel, using "stressor-s". They are available for
+CPU, CPU cache, devices, I/O, interrupts, file system, memory, network,
+operating system, pipelines, schedulers, and virtual machines. Please refer
+to the `stress-ng man-page <https://www.mankier.com/1/stress-ng>`_ to
+find the description of all the available stressor-s. The netdev stressor
+starts specified number (N) of workers that exercise various netdevice
+ioctl commands across all the available network devices.
+
+paxtest kiddie workload
+-----------------------
+
+paxtest is a program that tests buffer overflows in the kernel. It tests
+kernel enforcements over memory usage. Generally, execution in some memory
+segments makes buffer overflows possible. It runs a set of programs that
+attempt to subvert memory usage. It is used as a regression test suite for
+PaX, but might be useful to test other memory protection patches for the
+kernel. We used paxtest kiddie mode which looks for simple vulnerabilities.
+
+What is strace and how do we use it?
+====================================
+
+As mentioned earlier, strace which is a useful diagnostic, instructional,
+and debugging tool and can be used to discover the system resources in use
+by a workload. It can be used:
+
+ * To see how a process interacts with the kernel.
+ * To see why a process is failing or hanging.
+ * For reverse engineering a process.
+ * To find the files on which a program depends.
+ * For analyzing the performance of an application.
+ * For troubleshooting various problems related to the operating system.
+
+In addition, strace can generate run-time statistics on times, calls, and
+errors for each system call and report a summary when program exits,
+suppressing the regular output. This attempts to show system time (CPU time
+spent running in the kernel) independent of wall clock time. We plan to use
+these features to get information on workload system usage.
+
+strace command supports basic, verbose, and stats modes. strace command when
+run in verbose mode gives more detailed information about the system calls
+invoked by a process.
+
+Running strace -c generates a report of the percentage of time spent in each
+system call, the total time in seconds, the microseconds per call, the total
+number of calls, the count of each system call that has failed with an error
+and the type of system call made.
+
+ * Usage: strace <command we want to trace>
+ * Verbose mode usage: strace -v <command>
+ * Gather statistics: strace -c <command>
+
+We used the “-c” option to gather fine-grained run-time statistics in use
+by three workloads we have chose for this analysis.
+
+ * perf
+ * stress-ng
+ * paxtest
+
+What is cscope and how do we use it?
+====================================
+
+Now let’s look at `cscope <https://cscope.sourceforge.net/>`_, a command
+line tool for browsing C, C++ or Java code-bases. We can use it to find
+all the references to a symbol, global definitions, functions called by a
+function, functions calling a function, text strings, regular expression
+patterns, files including a file.
+
+We can use cscope to find which system call belongs to which subsystem.
+This way we can find the kernel subsystems used by a process when it is
+executed.
+
+Let’s checkout the latest Linux repository and build cscope database::
+
+  git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux
+  cd linux
+  cscope -R -p10  # builds cscope.out database before starting browse session
+  cscope -d -p10  # starts browse session on cscope.out database
+
+Note: Run "cscope -R -p10" to build the database and "cscope -d -p10" to
+enter into the browsing session. cscope by default uses the cscope.out
+database. To get out of this mode press ctrl+d. -p option is used to
+specify the number of file path components to display. -p10 is optimal
+for browsing kernel sources.
+
+Alternatively, the kernel build system can generate the cscope database::
+
+  make cscope
+
+To exclude directories from the generated database, pass IGNORE_DIRS to
+the cscope target. For example, to exclude Documentation/, run::
+
+  make IGNORE_DIRS="Documentation" cscope
+
+What is perf and how do we use it?
+==================================
+
+Perf is an analysis tool based on Linux 2.6+ systems, which abstracts the
+CPU hardware difference in performance measurement in Linux, and provides
+a simple command line interface. Perf is based on the perf_events interface
+exported by the kernel. It is very useful for profiling the system and
+finding performance bottlenecks in an application.
+
+If you haven't already checked out the Linux mainline repository, you can do
+so and then build kernel and perf tool::
+
+  git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux
+  cd linux
+  make -j3 all
+  cd tools/perf
+  make
+
+Note: The perf command can be built without building the kernel in the
+repository and can be run on older kernels. However matching the kernel
+and perf revisions gives more accurate information on the subsystem usage.
+
+We used "perf stat" and "perf bench" options. For a detailed information on
+the perf tool, run "perf -h".
+
+perf stat
+---------
+The perf stat command generates a report of various hardware and software
+events. It does so with the help of hardware counter registers found in
+modern CPUs that keep the count of these activities. "perf stat cal" shows
+stats for cal command.
+
+Perf bench
+----------
+The perf bench command contains multiple multi-threaded microkernel
+benchmarks for executing different subsystems in the Linux kernel and
+system calls. This allows us to easily measure the impact of changes,
+which can help mitigate performance regressions. It also acts as a common
+benchmarking framework, enabling developers to easily create test cases,
+integrate transparently, and use performance-rich tooling.
+
+"perf bench all" runs all available benchmarks in the perf bench
+framework. The exact set of benchmarks depends on the perf version and on
+the features enabled when perf was built.
+
+To list the benchmark collections available on the current system, run::
+
+  perf bench
+
+To list benchmarks in a collection, run::
+
+  perf bench <collection>
+
+For example, to list the benchmarks in the mem collection, run::
+
+  perf bench mem
+
+What is stress-ng and how do we use it?
+=======================================
+
+As mentioned earlier, stress-ng is used for performing stress testing on
+the kernel. It allows you to exercise various physical subsystems of the
+computer, as well as interfaces of the OS kernel, using stressor-s. They
+are available for CPU, CPU cache, devices, I/O, interrupts, file system,
+memory, network, operating system, pipelines, schedulers, and virtual
+machines.
+
+The netdev stressor starts N workers that exercise various netdevice ioctl
+commands across all the available network devices. The following ioctls are
+exercised:
+
+ * SIOCGIFCONF, SIOCGIFINDEX, SIOCGIFNAME, SIOCGIFFLAGS
+ * SIOCGIFADDR, SIOCGIFNETMASK, SIOCGIFMETRIC, SIOCGIFMTU
+ * SIOCGIFHWADDR, SIOCGIFMAP, SIOCGIFTXQLEN
+
+The following command runs the stressor::
+
+  stress-ng --netdev 1 -t 60 --metrics
+
+We can use the perf record command to record the events and information
+associated with a process. This command records the profiling data in the
+perf.data file in the same directory.
+
+Using the following commands you can record the events associated with the
+netdev stressor, view the generated report perf.data and annotate the output
+to view the statistics of each instruction of the program::
+
+  perf record -- stress-ng --netdev 1 -t 60 --metrics
+  perf report
+  perf annotate
+
+What is paxtest and how do we use it?
+=====================================
+
+paxtest is a program that tests buffer overflows in the kernel. It tests
+kernel enforcements over memory usage. Generally, execution in some memory
+segments makes buffer overflows possible. It runs a set of programs that
+attempt to subvert memory usage. It is used as a regression test suite for
+PaX, and will be useful to test other memory protection patches for the
+kernel.
+
+paxtest provides kiddie and blackhat modes. The paxtest kiddie mode runs
+in normal mode, whereas the blackhat mode tries to get around the protection
+of the kernel testing for vulnerabilities. We focus on the kiddie mode here
+and combine "paxtest kiddie" run with "perf record" to collect CPU stack
+traces for the paxtest kiddie run to see which function is calling other
+functions in the performance profile. Then the "dwarf" (DWARF's Call Frame
+Information) mode can be used to unwind the stack.
+
+The following command can be used to view resulting report in call-graph
+format::
+
+  perf record --call-graph dwarf paxtest kiddie
+  perf report --stdio
+
+Tracing workloads
+=================
+
+Now that we understand the workloads, let's start tracing them.
+
+Tracing perf bench all workload
+-------------------------------
+
+Run the following command to trace perf bench all workload::
+
+ strace -c perf bench all
+
+**System Calls made by the workload**
+
+The below table shows the system calls invoked by the workload, number of
+times each system call is invoked, and the corresponding Linux subsystem.
+
++-------------------+-----------+-----------------+-------------------------+
+| System Call       | # calls   | Linux Subsystem | System Call (API)       |
++===================+===========+=================+=========================+
+| getppid           | 10000001  | Process Mgmt    | sys_getpid()            |
++-------------------+-----------+-----------------+-------------------------+
+| clone             | 1077      | Process Mgmt.   | sys_clone()             |
++-------------------+-----------+-----------------+-------------------------+
+| prctl             | 23        | Process Mgmt.   | sys_prctl()             |
++-------------------+-----------+-----------------+-------------------------+
+| prlimit64         | 7         | Process Mgmt.   | sys_prlimit64()         |
++-------------------+-----------+-----------------+-------------------------+
+| getpid            | 10        | Process Mgmt.   | sys_getpid()            |
++-------------------+-----------+-----------------+-------------------------+
+| uname             | 3         | Process Mgmt.   | sys_uname()             |
++-------------------+-----------+-----------------+-------------------------+
+| sysinfo           | 1         | Process Mgmt.   | sys_sysinfo()           |
++-------------------+-----------+-----------------+-------------------------+
+| getuid            | 1         | Process Mgmt.   | sys_getuid()            |
++-------------------+-----------+-----------------+-------------------------+
+| getgid            | 1         | Process Mgmt.   | sys_getgid()            |
++-------------------+-----------+-----------------+-------------------------+
+| geteuid           | 1         | Process Mgmt.   | sys_geteuid()           |
++-------------------+-----------+-----------------+-------------------------+
+| getegid           | 1         | Process Mgmt.   | sys_getegid()           |
++-------------------+-----------+-----------------+-------------------------+
+| close             | 49951     | Filesystem      | sys_close()             |
++-------------------+-----------+-----------------+-------------------------+
+| pipe              | 604       | Filesystem      | sys_pipe()              |
++-------------------+-----------+-----------------+-------------------------+
+| openat            | 48560     | Filesystem      | sys_openat()            |
++-------------------+-----------+-----------------+-------------------------+
+| fstat             | 8338      | Filesystem      | sys_fstat()             |
++-------------------+-----------+-----------------+-------------------------+
+| stat              | 1573      | Filesystem      | sys_stat()              |
++-------------------+-----------+-----------------+-------------------------+
+| pread64           | 9646      | Filesystem      | sys_pread64()           |
++-------------------+-----------+-----------------+-------------------------+
+| getdents64        | 1873      | Filesystem      | sys_getdents64()        |
++-------------------+-----------+-----------------+-------------------------+
+| access            | 3         | Filesystem      | sys_access()            |
++-------------------+-----------+-----------------+-------------------------+
+| lstat             | 1880      | Filesystem      | sys_lstat()             |
++-------------------+-----------+-----------------+-------------------------+
+| lseek             | 6         | Filesystem      | sys_lseek()             |
++-------------------+-----------+-----------------+-------------------------+
+| ioctl             | 3         | Filesystem      | sys_ioctl()             |
++-------------------+-----------+-----------------+-------------------------+
+| dup2              | 1         | Filesystem      | sys_dup2()              |
++-------------------+-----------+-----------------+-------------------------+
+| execve            | 2         | Filesystem      | sys_execve()            |
++-------------------+-----------+-----------------+-------------------------+
+| fcntl             | 8779      | Filesystem      | sys_fcntl()             |
++-------------------+-----------+-----------------+-------------------------+
+| statfs            | 1         | Filesystem      | sys_statfs()            |
++-------------------+-----------+-----------------+-------------------------+
+| epoll_create      | 2         | Filesystem      | sys_epoll_create()      |
++-------------------+-----------+-----------------+-------------------------+
+| epoll_ctl         | 64        | Filesystem      | sys_epoll_ctl()         |
++-------------------+-----------+-----------------+-------------------------+
+| newfstatat        | 8318      | Filesystem      | sys_newfstatat()        |
++-------------------+-----------+-----------------+-------------------------+
+| eventfd2          | 192       | Filesystem      | sys_eventfd2()          |
++-------------------+-----------+-----------------+-------------------------+
+| mmap              | 243       | Memory Mgmt.    | sys_mmap()              |
++-------------------+-----------+-----------------+-------------------------+
+| mprotect          | 32        | Memory Mgmt.    | sys_mprotect()          |
++-------------------+-----------+-----------------+-------------------------+
+| brk               | 21        | Memory Mgmt.    | sys_brk()               |
++-------------------+-----------+-----------------+-------------------------+
+| munmap            | 128       | Memory Mgmt.    | sys_munmap()            |
++-------------------+-----------+-----------------+-------------------------+
+| set_mempolicy     | 156       | Memory Mgmt.    | sys_set_mempolicy()     |
++-------------------+-----------+-----------------+-------------------------+
+| set_tid_address   | 1         | Process Mgmt.   | sys_set_tid_address()   |
++-------------------+-----------+-----------------+-------------------------+
+| set_robust_list   | 1         | Futex           | sys_set_robust_list()   |
++-------------------+-----------+-----------------+-------------------------+
+| futex             | 341       | Futex           | sys_futex()             |
++-------------------+-----------+-----------------+-------------------------+
+| sched_getaffinity | 79        | Scheduler       | sys_sched_getaffinity() |
++-------------------+-----------+-----------------+-------------------------+
+| sched_setaffinity | 223       | Scheduler       | sys_sched_setaffinity() |
++-------------------+-----------+-----------------+-------------------------+
+| socketpair        | 202       | Network         | sys_socketpair()        |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigprocmask    | 21        | Signal          | sys_rt_sigprocmask()    |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigaction      | 36        | Signal          | sys_rt_sigaction()      |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigreturn      | 2         | Signal          | sys_rt_sigreturn()      |
++-------------------+-----------+-----------------+-------------------------+
+| wait4             | 889       | Time            | sys_wait4()             |
++-------------------+-----------+-----------------+-------------------------+
+| clock_nanosleep   | 37        | Time            | sys_clock_nanosleep()   |
++-------------------+-----------+-----------------+-------------------------+
+| capget            | 4         | Capability      | sys_capget()            |
++-------------------+-----------+-----------------+-------------------------+
+
+Tracing stress-ng netdev stressor workload
+------------------------------------------
+
+Run the following command to trace stress-ng netdev stressor workload::
+
+  strace -c  stress-ng --netdev 1 -t 60 --metrics
+
+**System Calls made by the workload**
+
+The below table shows the system calls invoked by the workload, number of
+times each system call is invoked, and the corresponding Linux subsystem.
+
++-------------------+-----------+-----------------+-------------------------+
+| System Call       | # calls   | Linux Subsystem | System Call (API)       |
++===================+===========+=================+=========================+
+| openat            | 74        | Filesystem      | sys_openat()            |
++-------------------+-----------+-----------------+-------------------------+
+| close             | 75        | Filesystem      | sys_close()             |
++-------------------+-----------+-----------------+-------------------------+
+| read              | 58        | Filesystem      | sys_read()              |
++-------------------+-----------+-----------------+-------------------------+
+| fstat             | 20        | Filesystem      | sys_fstat()             |
++-------------------+-----------+-----------------+-------------------------+
+| flock             | 10        | Filesystem      | sys_flock()             |
++-------------------+-----------+-----------------+-------------------------+
+| write             | 7         | Filesystem      | sys_write()             |
++-------------------+-----------+-----------------+-------------------------+
+| getdents64        | 8         | Filesystem      | sys_getdents64()        |
++-------------------+-----------+-----------------+-------------------------+
+| pread64           | 8         | Filesystem      | sys_pread64()           |
++-------------------+-----------+-----------------+-------------------------+
+| lseek             | 1         | Filesystem      | sys_lseek()             |
++-------------------+-----------+-----------------+-------------------------+
+| access            | 2         | Filesystem      | sys_access()            |
++-------------------+-----------+-----------------+-------------------------+
+| getcwd            | 1         | Filesystem      | sys_getcwd()            |
++-------------------+-----------+-----------------+-------------------------+
+| execve            | 1         | Filesystem      | sys_execve()            |
++-------------------+-----------+-----------------+-------------------------+
+| mmap              | 61        | Memory Mgmt.    | sys_mmap()              |
++-------------------+-----------+-----------------+-------------------------+
+| munmap            | 3         | Memory Mgmt.    | sys_munmap()            |
++-------------------+-----------+-----------------+-------------------------+
+| mprotect          | 20        | Memory Mgmt.    | sys_mprotect()          |
++-------------------+-----------+-----------------+-------------------------+
+| mlock             | 2         | Memory Mgmt.    | sys_mlock()             |
++-------------------+-----------+-----------------+-------------------------+
+| brk               | 3         | Memory Mgmt.    | sys_brk()               |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigaction      | 21        | Signal          | sys_rt_sigaction()      |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigprocmask    | 1         | Signal          | sys_rt_sigprocmask()    |
++-------------------+-----------+-----------------+-------------------------+
+| sigaltstack       | 1         | Signal          | sys_sigaltstack()       |
++-------------------+-----------+-----------------+-------------------------+
+| rt_sigreturn      | 1         | Signal          | sys_rt_sigreturn()      |
++-------------------+-----------+-----------------+-------------------------+
+| getpid            | 8         | Process Mgmt.   | sys_getpid()            |
++-------------------+-----------+-----------------+-------------------------+
+| prlimit64         | 5         | Process Mgmt.   | sys_prlimit64()         |
++-------------------+-----------+-----------------+-------------------------+
+| arch_prctl        | 2         | Process Mgmt.   | sys_arch_prctl()        |
++-------------------+-----------+-----------------+-------------------------+
+| sysinfo           | 2         | Process Mgmt.   | sys_sysinfo()           |
++-------------------+-----------+-----------------+-------------------------+
+| getuid            | 2         | Process Mgmt.   | sys_getuid()            |
++-------------------+-----------+-----------------+-------------------------+
+| uname             | 1         | Process Mgmt.   | sys_uname()             |
++-------------------+-----------+-----------------+-------------------------+
+| setpgid           | 1         | Process Mgmt.   | sys_setpgid()           |
++-------------------+-----------+-----------------+-------------------------+
+| getrusage         | 1         | Process Mgmt.   | sys_getrusage()         |
++-------------------+-----------+-----------------+-------------------------+
+| geteuid           | 1         | Process Mgmt.   | sys_geteuid()           |
++-------------------+-----------+-----------------+-------------------------+
+| getppid           | 1         | Process Mgmt.   | sys_getppid()           |
++-------------------+-----------+-----------------+-------------------------+
+| sendto            | 3         | Network         | sys_sendto()            |
++-------------------+-----------+-----------------+-------------------------+
+| connect           | 1         | Network         | sys_connect()           |
++-------------------+-----------+-----------------+-------------------------+
+| socket            | 1         | Network         | sys_socket()            |
++-------------------+-----------+-----------------+-------------------------+
+| clone             | 1         | Process Mgmt.   | sys_clone()             |
++-------------------+-----------+-----------------+-------------------------+
+| set_tid_address   | 1         | Process Mgmt.   | sys_set_tid_address()   |
++-------------------+-----------+-----------------+-------------------------+
+| wait4             | 2         | Time            | sys_wait4()             |
++-------------------+-----------+-----------------+-------------------------+
+| alarm             | 1         | Time            | sys_alarm()             |
++-------------------+-----------+-----------------+-------------------------+
+| set_robust_list   | 1         | Futex           | sys_set_robust_list()   |
++-------------------+-----------+-----------------+-------------------------+
+
+Tracing paxtest kiddie workload
+-------------------------------
+
+Run the following command to trace paxtest kiddie workload::
+
+ strace -c paxtest kiddie
+
+**System Calls made by the workload**
+
+The below table shows the system calls invoked by the workload, number of
+times each system call is invoked, and the corresponding Linux subsystem.
+
++-------------------+-----------+-----------------+----------------------+
+| System Call       | # calls   | Linux Subsystem | System Call (API)    |
++===================+===========+=================+======================+
+| read              | 3         | Filesystem      | sys_read()           |
++-------------------+-----------+-----------------+----------------------+
+| write             | 11        | Filesystem      | sys_write()          |
++-------------------+-----------+-----------------+----------------------+
+| close             | 41        | Filesystem      | sys_close()          |
++-------------------+-----------+-----------------+----------------------+
+| stat              | 24        | Filesystem      | sys_stat()           |
++-------------------+-----------+-----------------+----------------------+
+| fstat             | 2         | Filesystem      | sys_fstat()          |
++-------------------+-----------+-----------------+----------------------+
+| pread64           | 6         | Filesystem      | sys_pread64()        |
++-------------------+-----------+-----------------+----------------------+
+| access            | 1         | Filesystem      | sys_access()         |
++-------------------+-----------+-----------------+----------------------+
+| pipe              | 1         | Filesystem      | sys_pipe()           |
++-------------------+-----------+-----------------+----------------------+
+| dup2              | 24        | Filesystem      | sys_dup2()           |
++-------------------+-----------+-----------------+----------------------+
+| execve            | 1         | Filesystem      | sys_execve()         |
++-------------------+-----------+-----------------+----------------------+
+| fcntl             | 26        | Filesystem      | sys_fcntl()          |
++-------------------+-----------+-----------------+----------------------+
+| openat            | 14        | Filesystem      | sys_openat()         |
++-------------------+-----------+-----------------+----------------------+
+| rt_sigaction      | 7         | Signal          | sys_rt_sigaction()   |
++-------------------+-----------+-----------------+----------------------+
+| rt_sigreturn      | 38        | Signal          | sys_rt_sigreturn()   |
++-------------------+-----------+-----------------+----------------------+
+| clone             | 38        | Process Mgmt.   | sys_clone()          |
++-------------------+-----------+-----------------+----------------------+
+| wait4             | 44        | Time            | sys_wait4()          |
++-------------------+-----------+-----------------+----------------------+
+| mmap              | 7         | Memory Mgmt.    | sys_mmap()           |
++-------------------+-----------+-----------------+----------------------+
+| mprotect          | 3         | Memory Mgmt.    | sys_mprotect()       |
++-------------------+-----------+-----------------+----------------------+
+| munmap            | 1         | Memory Mgmt.    | sys_munmap()         |
++-------------------+-----------+-----------------+----------------------+
+| brk               | 3         | Memory Mgmt.    | sys_brk()            |
++-------------------+-----------+-----------------+----------------------+
+| getpid            | 1         | Process Mgmt.   | sys_getpid()         |
++-------------------+-----------+-----------------+----------------------+
+| getuid            | 1         | Process Mgmt.   | sys_getuid()         |
++-------------------+-----------+-----------------+----------------------+
+| getgid            | 1         | Process Mgmt.   | sys_getgid()         |
++-------------------+-----------+-----------------+----------------------+
+| geteuid           | 2         | Process Mgmt.   | sys_geteuid()        |
++-------------------+-----------+-----------------+----------------------+
+| getegid           | 1         | Process Mgmt.   | sys_getegid()        |
++-------------------+-----------+-----------------+----------------------+
+| getppid           | 1         | Process Mgmt.   | sys_getppid()        |
++-------------------+-----------+-----------------+----------------------+
+| arch_prctl        | 2         | Process Mgmt.   | sys_arch_prctl()     |
++-------------------+-----------+-----------------+----------------------+
+
+Conclusion
+==========
+
+This document is intended to be used as a guide on how to gather fine-grained
+information on the resources in use by workloads using strace.
+
+References
+==========
+
+ * `Discovery Linux Kernel Subsystems used by OpenAPS <https://elisa.tech/blog/2022/02/02/discovery-linux-kernel-subsystems-used-by-openaps>`_
+ * `ELISA-White-Papers-Discovering Linux kernel subsystems used by a workload <https://github.com/elisa-tech/ELISA-White-Papers/blob/master/Processes/Discovering_Linux_kernel_subsystems_used_by_a_workload.md>`_
+ * `strace <https://man7.org/linux/man-pages/man1/strace.1.html>`_
+ * `perf <https://man7.org/linux/man-pages/man1/perf.1.html>`_
+ * `paxtest README <https://github.com/opntr/paxtest-freebsd/blob/hardenedbsd/0.9.14-hbsd/README>`_
+ * `stress-ng <https://www.mankier.com/1/stress-ng>`_
+ * `Monitoring and managing system status and performance <https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/monitoring_and_managing_system_status_and_performance/index>`_
diff --git a/Documentation/admin-guide/xfs.rst b/Documentation/admin-guide/xfs.rst
new file mode 100644
index 000000000..acdd4b659
--- /dev/null
+++ b/Documentation/admin-guide/xfs.rst
@@ -0,0 +1,563 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+The SGI XFS Filesystem
+======================
+
+XFS is a high performance journaling filesystem which originated
+on the SGI IRIX platform.  It is completely multi-threaded, can
+support large files and large filesystems, extended attributes,
+variable block sizes, is extent based, and makes extensive use of
+Btrees (directories, extents, free space) to aid both performance
+and scalability.
+
+Refer to the documentation at https://xfs.wiki.kernel.org/
+for further details.  This implementation is on-disk compatible
+with the IRIX version of XFS.
+
+
+Mount Options
+=============
+
+When mounting an XFS filesystem, the following options are accepted.
+
+  allocsize=size
+	Sets the buffered I/O end-of-file preallocation size when
+	doing delayed allocation writeout (default size is 64KiB).
+	Valid values for this option are page size (typically 4KiB)
+	through to 1GiB, inclusive, in power-of-2 increments.
+
+	The default behaviour is for dynamic end-of-file
+	preallocation size, which uses a set of heuristics to
+	optimise the preallocation size based on the current
+	allocation patterns within the file and the access patterns
+	to the file. Specifying a fixed ``allocsize`` value turns off
+	the dynamic behaviour.
+
+  discard or nodiscard (default)
+	Enable/disable the issuing of commands to let the block
+	device reclaim space freed by the filesystem.  This is
+	useful for SSD devices, thinly provisioned LUNs and virtual
+	machine images, but may have a performance impact.
+
+	Note: It is currently recommended that you use the ``fstrim``
+	application to ``discard`` unused blocks rather than the ``discard``
+	mount option because the performance impact of this option
+	is quite severe.
+
+  grpid/bsdgroups or nogrpid/sysvgroups (default)
+	These options define what group ID a newly created file
+	gets.  When ``grpid`` is set, it takes the group ID of the
+	directory in which it is created; otherwise it takes the
+	``fsgid`` of the current process, unless the directory has the
+	``setgid`` bit set, in which case it takes the ``gid`` from the
+	parent directory, and also gets the ``setgid`` bit set if it is
+	a directory itself.
+
+  filestreams
+	Make the data allocator use the filestreams allocation mode
+	across the entire filesystem rather than just on directories
+	configured to use it.
+
+  inode32 or inode64 (default)
+	When ``inode32`` is specified, it indicates that XFS limits
+	inode creation to locations which will not result in inode
+	numbers with more than 32 bits of significance.
+
+	When ``inode64`` is specified, it indicates that XFS is allowed
+	to create inodes at any location in the filesystem,
+	including those which will result in inode numbers occupying
+	more than 32 bits of significance.
+
+	``inode32`` is provided for backwards compatibility with older
+	systems and applications, since 64 bits inode numbers might
+	cause problems for some applications that cannot handle
+	large inode numbers.  If applications are in use which do
+	not handle inode numbers bigger than 32 bits, the ``inode32``
+	option should be specified.
+
+  largeio or nolargeio (default)
+	If ``nolargeio`` is specified, the optimal I/O reported in
+	``st_blksize`` by **stat(2)** will be as small as possible to allow
+	user applications to avoid inefficient read/modify/write
+	I/O.  This is typically the page size of the machine, as
+	this is the granularity of the page cache.
+
+	If ``largeio`` is specified, a filesystem that was created with a
+	``swidth`` specified will return the ``swidth`` value (in bytes)
+	in ``st_blksize``. If the filesystem does not have a ``swidth``
+	specified but does specify an ``allocsize`` then ``allocsize``
+	(in bytes) will be returned instead. Otherwise the behaviour
+	is the same as if ``nolargeio`` was specified.
+
+  logbufs=value
+	Set the number of in-memory log buffers.  Valid numbers
+	range from 2-8 inclusive.
+
+	The default value is 8 buffers.
+
+	If the memory cost of 8 log buffers is too high on small
+	systems, then it may be reduced at some cost to performance
+	on metadata intensive workloads. The ``logbsize`` option below
+	controls the size of each buffer and so is also relevant to
+	this case.
+
+  lifetime (default) or nolifetime
+	Enable data placement based on write life time hints provided
+	by the user. This turns on co-allocation of data of similar
+	life times when statistically favorable to reduce garbage
+	collection cost.
+
+	These options are only available for zoned rt file systems.
+
+  logbsize=value
+	Set the size of each in-memory log buffer.  The size may be
+	specified in bytes, or in kilobytes with a "k" suffix.
+	Valid sizes for version 1 and version 2 logs are 16384 (16k)
+	and 32768 (32k).  Valid sizes for version 2 logs also
+	include 65536 (64k), 131072 (128k) and 262144 (256k). The
+	logbsize must be an integer multiple of the log
+	stripe unit configured at **mkfs(8)** time.
+
+	The default value for version 1 logs is 32768, while the
+	default value for version 2 logs is MAX(32768, log_sunit).
+
+  logdev=device and rtdev=device
+	Use an external log (metadata journal) and/or real-time device.
+	An XFS filesystem has up to three parts: a data section, a log
+	section, and a real-time section.  The real-time section is
+	optional, and the log section can be separate from the data
+	section or contained within it.
+
+  max_atomic_write=value
+	Set the maximum size of an atomic write.  The size may be
+	specified in bytes, in kilobytes with a "k" suffix, in megabytes
+	with a "m" suffix, or in gigabytes with a "g" suffix.  The size
+	cannot be larger than the maximum write size, larger than the
+	size of any allocation group, or larger than the size of a
+	remapping operation that the log can complete atomically.
+
+	The default value is to set the maximum I/O completion size
+	to allow each CPU to handle one at a time.
+
+  max_open_zones=value
+	Specify the max number of zones to keep open for writing on a
+	zoned rt device. Many open zones aids file data separation
+	but may impact performance on HDDs.
+
+	If ``max_open_zones`` is not specified, the value is determined
+	by the capabilities and the size of the zoned rt device.
+
+  noalign
+	Data allocations will not be aligned at stripe unit
+	boundaries. This is only relevant to filesystems created
+	with non-zero data alignment parameters (``sunit``, ``swidth``) by
+	**mkfs(8)**.
+
+  norecovery
+	The filesystem will be mounted without running log recovery.
+	If the filesystem was not cleanly unmounted, it is likely to
+	be inconsistent when mounted in ``norecovery`` mode.
+	Some files or directories may not be accessible because of this.
+	Filesystems mounted ``norecovery`` must be mounted read-only or
+	the mount will fail.
+
+  nouuid
+	Don't check for double mounted file systems using the file
+	system ``uuid``.  This is useful to mount LVM snapshot volumes,
+	and often used in combination with ``norecovery`` for mounting
+	read-only snapshots.
+
+  noquota
+	Forcibly turns off all quota accounting and enforcement
+	within the filesystem.
+
+  uquota/usrquota/uqnoenforce/quota
+	User disk quota accounting enabled, and limits (optionally)
+	enforced.  Refer to **xfs_quota(8)** for further details.
+
+  gquota/grpquota/gqnoenforce
+	Group disk quota accounting enabled and limits (optionally)
+	enforced.  Refer to **xfs_quota(8)** for further details.
+
+  pquota/prjquota/pqnoenforce
+	Project disk quota accounting enabled and limits (optionally)
+	enforced.  Refer to **xfs_quota(8)** for further details.
+
+  sunit=value and swidth=value
+	Used to specify the stripe unit and width for a RAID device
+	or a stripe volume.  "value" must be specified in 512-byte
+	block units. These options are only relevant to filesystems
+	that were created with non-zero data alignment parameters.
+
+	The ``sunit`` and ``swidth`` parameters specified must be compatible
+	with the existing filesystem alignment characteristics.  In
+	general, that means the only valid changes to ``sunit`` are
+	increasing it by a power-of-2 multiple. Valid ``swidth`` values
+	are any integer multiple of a valid ``sunit`` value.
+
+	Typically the only time these mount options are necessary if
+	after an underlying RAID device has had its geometry
+	modified, such as adding a new disk to a RAID5 lun and
+	reshaping it.
+
+  swalloc
+	Data allocations will be rounded up to stripe width boundaries
+	when the current end of file is being extended and the file
+	size is larger than the stripe width size.
+
+  wsync
+	When specified, all filesystem namespace operations are
+	executed synchronously. This ensures that when the namespace
+	operation (create, unlink, etc) completes, the change to the
+	namespace is on stable storage. This is useful in HA setups
+	where failover must not result in clients seeing
+	inconsistent namespace presentation during or after a
+	failover event.
+
+  errortag=tagname
+	When specified, enables the error inject tag named "tagname" with the
+	default frequency.  Can be specified multiple times to enable multiple
+	errortags.  Specifying this option on remount will reset the error tag
+	to the default value if it was set to any other value before.
+	This option is only supported when CONFIG_XFS_DEBUG is enabled, and
+	will not be reflected in /proc/self/mounts.
+
+Deprecation of V4 Format
+========================
+
+The V4 filesystem format lacks certain features that are supported by
+the V5 format, such as metadata checksumming, strengthened metadata
+verification, and the ability to store timestamps past the year 2038.
+Because of this, the V4 format is deprecated.  All users should upgrade
+by backing up their files, reformatting, and restoring from the backup.
+
+Administrators and users can detect a V4 filesystem by running xfs_info
+against a filesystem mountpoint and checking for a string containing
+"crc=".  If no such string is found, please upgrade xfsprogs to the
+latest version and try again.
+
+The deprecation will take place in two parts.  Support for mounting V4
+filesystems can now be disabled at kernel build time via Kconfig option.
+These options were changed to default to no in September 2025.  In
+September 2030, support will be removed from the codebase entirely.
+
+Note: Distributors may choose to withdraw V4 format support earlier than
+the dates listed above.
+
+Deprecated Mount Options
+========================
+
+============================    ================
+  Name				Removal Schedule
+============================    ================
+Mounting with V4 filesystem     September 2030
+Mounting ascii-ci filesystem    September 2030
+============================    ================
+
+
+Removed Mount Options
+=====================
+
+===========================     =======
+  Name				Removed
+===========================	=======
+  delaylog/nodelaylog		v4.0
+  ihashsize			v4.0
+  irixsgid			v4.0
+  osyncisdsync/osyncisosync	v4.0
+  barrier			v4.19
+  nobarrier			v4.19
+  ikeep/noikeep			v6.18
+  attr2/noattr2			v6.18
+===========================     =======
+
+sysctls
+=======
+
+The following sysctls are available for the XFS filesystem:
+
+  fs.xfs.stats_clear		(Min: 0  Default: 0  Max: 1)
+	Setting this to "1" clears accumulated XFS statistics
+	in /proc/fs/xfs/stat.  It then immediately resets to "0".
+
+  fs.xfs.xfssyncd_centisecs	(Min: 100  Default: 3000  Max: 720000)
+	The interval at which the filesystem flushes metadata
+	out to disk and runs internal cache cleanup routines.
+
+  fs.xfs.filestream_centisecs	(Min: 1  Default: 3000  Max: 360000)
+	The interval at which the filesystem ages filestreams cache
+	references and returns timed-out AGs back to the free stream
+	pool.
+
+  fs.xfs.speculative_prealloc_lifetime
+	(Units: seconds   Min: 1  Default: 300  Max: 86400)
+	The interval at which the background scanning for inodes
+	with unused speculative preallocation runs. The scan
+	removes unused preallocation from clean inodes and releases
+	the unused space back to the free pool.
+
+  fs.xfs.error_level		(Min: 0  Default: 3  Max: 11)
+	A volume knob for error reporting when internal errors occur.
+	This will generate detailed messages & backtraces for filesystem
+	shutdowns, for example.  Current threshold values are:
+
+		XFS_ERRLEVEL_OFF:       0
+		XFS_ERRLEVEL_LOW:       1
+		XFS_ERRLEVEL_HIGH:      5
+
+  fs.xfs.panic_mask		(Min: 0  Default: 0  Max: 511)
+	Causes certain error conditions to call BUG(). Value is a bitmask;
+	OR together the tags which represent errors which should cause panics:
+
+		XFS_NO_PTAG                     0
+		XFS_PTAG_IFLUSH                 0x00000001
+		XFS_PTAG_LOGRES                 0x00000002
+		XFS_PTAG_AILDELETE              0x00000004
+		XFS_PTAG_ERROR_REPORT           0x00000008
+		XFS_PTAG_SHUTDOWN_CORRUPT       0x00000010
+		XFS_PTAG_SHUTDOWN_IOERROR       0x00000020
+		XFS_PTAG_SHUTDOWN_LOGERROR      0x00000040
+		XFS_PTAG_FSBLOCK_ZERO           0x00000080
+		XFS_PTAG_VERIFIER_ERROR         0x00000100
+
+	This option is intended for debugging only.
+
+  fs.xfs.inherit_sync		(Min: 0  Default: 1  Max: 1)
+	Setting this to "1" will cause the "sync" flag set
+	by the **xfs_io(8)** chattr command on a directory to be
+	inherited by files in that directory.
+
+  fs.xfs.inherit_nodump		(Min: 0  Default: 1  Max: 1)
+	Setting this to "1" will cause the "nodump" flag set
+	by the **xfs_io(8)** chattr command on a directory to be
+	inherited by files in that directory.
+
+  fs.xfs.inherit_noatime	(Min: 0  Default: 1  Max: 1)
+	Setting this to "1" will cause the "noatime" flag set
+	by the **xfs_io(8)** chattr command on a directory to be
+	inherited by files in that directory.
+
+  fs.xfs.inherit_nosymlinks	(Min: 0  Default: 1  Max: 1)
+	Setting this to "1" will cause the "nosymlinks" flag set
+	by the **xfs_io(8)** chattr command on a directory to be
+	inherited by files in that directory.
+
+  fs.xfs.inherit_nodefrag	(Min: 0  Default: 1  Max: 1)
+	Setting this to "1" will cause the "nodefrag" flag set
+	by the **xfs_io(8)** chattr command on a directory to be
+	inherited by files in that directory.
+
+  fs.xfs.rotorstep		(Min: 1  Default: 1  Max: 256)
+	In "inode32" allocation mode, this option determines how many
+	files the allocator attempts to allocate in the same allocation
+	group before moving to the next allocation group.  The intent
+	is to control the rate at which the allocator moves between
+	allocation groups when allocating extents for new files.
+
+Deprecated Sysctls
+==================
+
+None currently.
+
+Removed Sysctls
+===============
+
+==========================================   =======
+  Name                                       Removed
+==========================================   =======
+  fs.xfs.xfsbufd_centisec                    v4.0
+  fs.xfs.age_buffer_centisecs                v4.0
+  fs.xfs.irix_symlink_mode                   v6.18
+  fs.xfs.irix_sgid_inherit                   v6.18
+  fs.xfs.speculative_cow_prealloc_lifetime   v6.18
+==========================================   =======
+
+Error handling
+==============
+
+XFS can act differently according to the type of error found during its
+operation. The implementation introduces the following concepts to the error
+handler:
+
+ -failure speed:
+	Defines how fast XFS should propagate an error upwards when a specific
+	error is found during the filesystem operation. It can propagate
+	immediately, after a defined number of retries, after a set time period,
+	or simply retry forever.
+
+ -error classes:
+	Specifies the subsystem the error configuration will apply to, such as
+	metadata IO or memory allocation. Different subsystems will have
+	different error handlers for which behaviour can be configured.
+
+ -error handlers:
+	Defines the behavior for a specific error.
+
+The filesystem behavior during an error can be set via ``sysfs`` files. Each
+error handler works independently - the first condition met by an error handler
+for a specific class will cause the error to be propagated rather than reset and
+retried.
+
+The action taken by the filesystem when the error is propagated is context
+dependent - it may cause a shut down in the case of an unrecoverable error,
+it may be reported back to userspace, or it may even be ignored because
+there's nothing useful we can with the error or anyone we can report it to (e.g.
+during unmount).
+
+The configuration files are organized into the following hierarchy for each
+mounted filesystem:
+
+  /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+Where:
+  <dev>
+	The short device name of the mounted filesystem. This is the same device
+	name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
+
+  <class>
+	The subsystem the error configuration belongs to. As of 4.9, the defined
+	classes are:
+
+		- "metadata": applies metadata buffer write IO
+
+  <error>
+	The individual error handler configurations.
+
+
+Each filesystem has "global" error configuration options defined in their top
+level directory:
+
+  /sys/fs/xfs/<dev>/error/
+
+  fail_at_unmount		(Min:  0  Default:  1  Max: 1)
+	Defines the filesystem error behavior at unmount time.
+
+	If set to a value of 1, XFS will override all other error configurations
+	during unmount and replace them with "immediate fail" characteristics.
+	i.e. no retries, no retry timeout. This will always allow unmount to
+	succeed when there are persistent errors present.
+
+	If set to 0, the configured retry behaviour will continue until all
+	retries and/or timeouts have been exhausted. This will delay unmount
+	completion when there are persistent errors, and it may prevent the
+	filesystem from ever unmounting fully in the case of "retry forever"
+	handler configurations.
+
+	Note: there is no guarantee that fail_at_unmount can be set while an
+	unmount is in progress. It is possible that the ``sysfs`` entries are
+	removed by the unmounting filesystem before a "retry forever" error
+	handler configuration causes unmount to hang, and hence the filesystem
+	must be configured appropriately before unmount begins to prevent
+	unmount hangs.
+
+Each filesystem has specific error class handlers that define the error
+propagation behaviour for specific errors. There is also a "default" error
+handler defined, which defines the behaviour for all errors that don't have
+specific handlers defined. Where multiple retry constraints are configured for
+a single error, the first retry configuration that expires will cause the error
+to be propagated. The handler configurations are found in the directory:
+
+  /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+  max_retries			(Min: -1  Default: Varies  Max: INTMAX)
+	Defines the allowed number of retries of a specific error before
+	the filesystem will propagate the error. The retry count for a given
+	error context (e.g. a specific metadata buffer) is reset every time
+	there is a successful completion of the operation.
+
+	Setting the value to "-1" will cause XFS to retry forever for this
+	specific error.
+
+	Setting the value to "0" will cause XFS to fail immediately when the
+	specific error is reported.
+
+	Setting the value to "N" (where 0 < N < Max) will make XFS retry the
+	operation "N" times before propagating the error.
+
+  retry_timeout_seconds		(Min:  -1  Default:  Varies  Max: 1 day)
+	Define the amount of time (in seconds) that the filesystem is
+	allowed to retry its operations when the specific error is
+	found.
+
+	Setting the value to "-1" will allow XFS to retry forever for this
+	specific error.
+
+	Setting the value to "0" will cause XFS to fail immediately when the
+	specific error is reported.
+
+	Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
+	operation for up to "N" seconds before propagating the error.
+
+**Note:** The default behaviour for a specific error handler is dependent on both
+the class and error context. For example, the default values for
+"metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
+to "fail immediately" behaviour. This is done because ENODEV is a fatal,
+unrecoverable error no matter how many times the metadata IO is retried.
+
+Workqueue Concurrency
+=====================
+
+XFS uses kernel workqueues to parallelize metadata update processes.  This
+enables it to take advantage of storage hardware that can service many IO
+operations simultaneously.  This interface exposes internal implementation
+details of XFS, and as such is explicitly not part of any userspace API/ABI
+guarantee the kernel may give userspace.  These are undocumented features of
+the generic workqueue implementation XFS uses for concurrency, and they are
+provided here purely for diagnostic and tuning purposes and may change at any
+time in the future.
+
+The control knobs for a filesystem's workqueues are organized by task at hand
+and the short name of the data device.  They all can be found in:
+
+  /sys/bus/workqueue/devices/${task}!${device}
+
+================  ===========
+  Task            Description
+================  ===========
+  xfs_iwalk-$pid  Inode scans of the entire filesystem. Currently limited to
+                  mount time quotacheck.
+  xfs-gc          Background garbage collection of disk space that have been
+                  speculatively allocated beyond EOF or for staging copy on
+                  write operations.
+================  ===========
+
+For example, the knobs for the quotacheck workqueue for /dev/nvme0n1 would be
+found in /sys/bus/workqueue/devices/xfs_iwalk-1111!nvme0n1/.
+
+The interesting knobs for XFS workqueues are as follows:
+
+============     ===========
+  Knob           Description
+============     ===========
+  max_active     Maximum number of background threads that can be started to
+                 run the work.
+  cpumask        CPUs upon which the threads are allowed to run.
+  nice           Relative priority of scheduling the threads.  These are the
+                 same nice levels that can be applied to userspace processes.
+============     ===========
+
+Zoned Filesystems
+=================
+
+For zoned file systems, the following attributes are exposed in:
+
+  /sys/fs/xfs/<dev>/zoned/
+
+  max_open_zones		(Min:  1  Default:  Varies  Max:  UINTMAX)
+	This read-only attribute exposes the maximum number of open zones
+	available for data placement. The value is determined at mount time and
+	is limited by the capabilities of the backing zoned device, file system
+	size and the max_open_zones mount option.
+
+  nr_open_zones			(Min:  0  Default:  Varies  Max:  UINTMAX)
+	This read-only attribute exposes the current number of open zones
+	used by the file system.
+
+  zonegc_low_space		(Min:  0  Default:  0  Max:  100)
+	Define a percentage for how much of the unused space that GC should keep
+	available for writing. A high value will reclaim more of the space
+	occupied by unused blocks, creating a larger buffer against write
+	bursts at the cost of increased write amplification.  Regardless
+	of this value, garbage collection will always aim to free a minimum
+	amount of blocks to keep max_open_zones open for data placement purposes.
-- 
cgit v1.3.1


From 88a0474d92ba102fff860db3cae9da87a0964fbf Mon Sep 17 00:00:00 2001
From: Niklas Cassel <cassel@kernel.org>
Date: Fri, 18 Sep 2026 14:40:33 +0200
Subject: ata: libata: Correct libata.force parameter documentation

Align the documented libata.force options with their implementation.
The force table accepts PIO modes 0 through 6, not mode 7, and ncqati
controls NCQ generally rather than only queued TRIM.

The max_sec_1024 and max_sec_lba48 options only set transfer size
limits. Remove the misleading claim that they can also clear them.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20260918124030.1962773-6-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

(limited to 'Documentation/admin-guide')

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 33cd30996..24459f7ff 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3491,7 +3491,7 @@ Kernel parameters
 
 			* SATA link speed limit: 1.5Gbps or 3.0Gbps.
 
-			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
+			* Transfer mode: pio[0-6], mwdma[0-4] and udma[0-7].
 			  udma[/][16,25,33,44,66,100,133] notation is also
 			  allowed.
 
@@ -3509,7 +3509,7 @@ Kernel parameters
 
 			* [no]ncqtrim: Enable or disable queued DSM TRIM.
 
-			* [no]ncqati: Enable or disable NCQ trim on ATI chipset.
+			* [no]ncqati: Enable or disable NCQ on ATI chipsets.
 
 			* [no]trim: Enable or disable (unqueued) TRIM.
 
@@ -3540,11 +3540,9 @@ Kernel parameters
 
 			* max_sec_128: Set transfer size limit to 128 sectors.
 
-			* max_sec_1024: Set or clear transfer size limit to
-			  1024 sectors.
+			* max_sec_1024: Set transfer size limit to 1024 sectors.
 
-			* max_sec_lba48: Set or clear transfer size limit to
-			  65535 sectors.
+			* max_sec_lba48: Set transfer size limit to 65535 sectors.
 
 			* external: Mark port as external (hotplug-capable).
 
-- 
cgit v1.3.1