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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-24 08:46:03 -0700 |
| commit | cf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch) | |
| tree | 757a3d280760c654767631cab5ad8af2d86d1848 /Documentation/admin-guide/device-mapper/dm-init.rst | |
| download | linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip | |
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij:
"Core changes:
- Use the non-blocking mux_state_try_select() in the generic MUX pin
control back-end
- Free pin maps on pinctrl_generic_to_map() failure in the core
helpers
New hardware pin control:
- Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC
(this is for the low power audio, LPASS = Low Power Audio SubSystem
portions)
- Upboard support on top of the Intel pin controller
- Apple T6030 and T6031 support (just compatible strings)
- Samsung Exynos 8855 SoC
- Mediatek MT6858 SoC
- Rockchip RK3308B and RV1106 SoCs
- Airoha EN7523 and AN7563 SoCs
Improvements:
- Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable
- Qualcomm improvements on top of the Qualcomm PDC (power domain
controller) irqchip improvements from tglx:s tree
- Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups
- The NPCM8xx driver has been put into shape fixing many pin and
group definitions
- Some non-urgent Tegra 264 pin assignments are fixed up
- Some non-urgent fixups to Airoha AN7581 and AN7583 registers and
pin assignments, missing features etc"
* tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits)
dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema
pinctrl: meson: sync some modify from A4
pinctrl: meson: a4: Add input enable pin configuration
pinctrl: realtek: rtd1625: remove unused group name spdif_sel
pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13
dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema
Revert "Merge branch 'ib-rsk7204' into devel"
pinctrl: rockchip: Add RV1106 pinctrl support
dt-bindings: pinctrl: rockchip: Add RV1106 compatible
pinctrl: rockchip: Decode drive strength in the get function
pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable
pinctrl: airoha: add support of an7563 SoC
dt-bindings: pinctrl: airoha: add support of an7563 pin controller
pinctrl: airoha: try to find chip scu node by phandle first
pinctrl: airoha: add support of en7523 SoC
dt-bindings: pinctrl: airoha: add support of en7523 pin controller
pinctrl: airoha: an7583: add support for olt pinmux
pinctrl: airoha: an7583: add support for pon_alt pinmux
pinctrl: airoha: an7583: add support for npu_uart pinmux
dt-bindings: pinctrl: airoha: an7583: add missed features
...
Diffstat (limited to 'Documentation/admin-guide/device-mapper/dm-init.rst')
| -rw-r--r-- | Documentation/admin-guide/device-mapper/dm-init.rst | 133 |
1 files changed, 133 insertions, 0 deletions
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>] |
