From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/sysfs-block-device | 119 +++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-block-device (limited to 'Documentation/ABI/testing/sysfs-block-device') diff --git a/Documentation/ABI/testing/sysfs-block-device b/Documentation/ABI/testing/sysfs-block-device new file mode 100644 index 000000000..2d543cfa4 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-block-device @@ -0,0 +1,119 @@ +What: /sys/block/*/device/sw_activity +Date: Jun, 2008 +KernelVersion: v2.6.27 +Contact: linux-ide@vger.kernel.org +Description: + (RW) Used by drivers which support software controlled activity + LEDs. + + It has the following valid values: + + == ======================================================== + 0 OFF - the LED is not activated on activity + 1 BLINK_ON - the LED blinks on every 10ms when activity is + detected. + 2 BLINK_OFF - the LED is on when idle, and blinks off + every 10ms when activity is detected. + == ======================================================== + + Note that the user must turn sw_activity OFF it they wish to + control the activity LED via the em_message file. + + +What: /sys/block/*/device/unload_heads +Date: Sep, 2008 +KernelVersion: v2.6.28 +Contact: linux-ide@vger.kernel.org +Description: + (RW) Hard disk shock protection + + 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. + + - If the device does not support the unload heads feature, + access is denied with -EOPNOTSUPP. + - The maximal value accepted for a timeout is 30000 + milliseconds. + - A previously set timeout can be cancelled and disk can resume + normal operation immediately by specifying a timeout of 0. + - Some hard drives only comply with an earlier version of the + ATA standard, but support the unload feature nonetheless. + There is no safe way Linux can detect these devices, so this + is not enabled by default. If it is known that your device + does support the unload feature, then you can tell the kernel + to enable it by writing -1. It can be disabled again by + writing -2. + - Values below -2 are rejected with -EINVAL + + For more information, see + Documentation/admin-guide/laptops/disk-shock-protection.rst + + +What: /sys/block/*/device/ncq_prio_enable +Date: Oct, 2016 +KernelVersion: v4.10 +Contact: linux-ide@vger.kernel.org +Description: + (RW) Write to the file to turn on or off the SATA NCQ (native + command queueing) priority support. By default this feature is + turned off. If the device does not support the SATA NCQ + priority feature, writing "1" to this file results in an error + (see ncq_prio_supported). + + +What: /sys/block/*/device/sas_ncq_prio_enable +Date: Oct, 2016 +KernelVersion: v4.10 +Contact: linux-ide@vger.kernel.org +Description: + (RW) This is the equivalent of the ncq_prio_enable attribute + file for SATA devices connected to a SAS host-bus-adapter + (HBA) implementing support for the SATA NCQ priority feature. + This file does not exist if the HBA driver does not implement + support for the SATA NCQ priority feature, regardless of the + device support for this feature (see sas_ncq_prio_supported). + + +What: /sys/block/*/device/ncq_prio_supported +Date: Aug, 2021 +KernelVersion: v5.15 +Contact: linux-ide@vger.kernel.org +Description: + (RO) Indicates if the device supports the SATA NCQ (native + command queueing) priority feature. + + +What: /sys/block/*/device/sas_ncq_prio_supported +Date: Aug, 2021 +KernelVersion: v5.15 +Contact: linux-ide@vger.kernel.org +Description: + (RO) This is the equivalent of the ncq_prio_supported attribute + file for SATA devices connected to a SAS host-bus-adapter + (HBA) implementing support for the SATA NCQ priority feature. + This file does not exist if the HBA driver does not implement + support for the SATA NCQ priority feature, regardless of the + device support for this feature. + + +What: /sys/block/*/device/cdl_supported +Date: May, 2023 +KernelVersion: v6.5 +Contact: linux-scsi@vger.kernel.org +Description: + (RO) Indicates if the device supports the command duration + limits feature found in some ATA and SCSI devices. + + +What: /sys/block/*/device/cdl_enable +Date: May, 2023 +KernelVersion: v6.5 +Contact: linux-scsi@vger.kernel.org +Description: + (RW) For a device supporting the command duration limits + feature, write to the file to turn on or off the feature. + By default this feature is turned off. + Writing "1" to this file enables the use of command duration + limits for read and write commands in the kernel and turns on + the feature on the device. Writing "0" disables the feature. -- cgit v1.3.1