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Add documentation for the new device attribute file ncq_prio_supported, and its SAS HBA equivalent sas_ncq_prio_supported. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20210816014456.2191776-12-damien.lemoal@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
98 lines
3.4 KiB
Plaintext
98 lines
3.4 KiB
Plaintext
What: /sys/block/*/device/sw_activity
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Date: Jun, 2008
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KernelVersion: v2.6.27
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Contact: linux-ide@vger.kernel.org
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Description:
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(RW) Used by drivers which support software controlled activity
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LEDs.
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It has the following valid values:
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== ========================================================
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0 OFF - the LED is not activated on activity
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1 BLINK_ON - the LED blinks on every 10ms when activity is
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detected.
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2 BLINK_OFF - the LED is on when idle, and blinks off
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every 10ms when activity is detected.
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== ========================================================
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Note that the user must turn sw_activity OFF it they wish to
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control the activity LED via the em_message file.
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What: /sys/block/*/device/unload_heads
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Date: Sep, 2008
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KernelVersion: v2.6.28
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Contact: linux-ide@vger.kernel.org
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Description:
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(RW) Hard disk shock protection
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Writing an integer value to this file will take the heads of the
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respective drive off the platter and block all I/O operations
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for the specified number of milliseconds.
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- If the device does not support the unload heads feature,
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access is denied with -EOPNOTSUPP.
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- The maximal value accepted for a timeout is 30000
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milliseconds.
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- A previously set timeout can be cancelled and disk can resume
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normal operation immediately by specifying a timeout of 0.
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- Some hard drives only comply with an earlier version of the
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ATA standard, but support the unload feature nonetheless.
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There is no safe way Linux can detect these devices, so this
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is not enabled by default. If it is known that your device
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does support the unload feature, then you can tell the kernel
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to enable it by writing -1. It can be disabled again by
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writing -2.
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- Values below -2 are rejected with -EINVAL
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For more information, see
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Documentation/admin-guide/laptops/disk-shock-protection.rst
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What: /sys/block/*/device/ncq_prio_enable
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Date: Oct, 2016
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KernelVersion: v4.10
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Contact: linux-ide@vger.kernel.org
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Description:
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(RW) Write to the file to turn on or off the SATA NCQ (native
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command queueing) priority support. By default this feature is
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turned off. If the device does not support the SATA NCQ
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priority feature, writing "1" to this file results in an error
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(see ncq_prio_supported).
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What: /sys/block/*/device/sas_ncq_prio_enable
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Date: Oct, 2016
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KernelVersion: v4.10
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Contact: linux-ide@vger.kernel.org
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Description:
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(RW) This is the equivalent of the ncq_prio_enable attribute
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file for SATA devices connected to a SAS host-bus-adapter
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(HBA) implementing support for the SATA NCQ priority feature.
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This file does not exist if the HBA driver does not implement
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support for the SATA NCQ priority feature, regardless of the
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device support for this feature (see sas_ncq_prio_supported).
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What: /sys/block/*/device/ncq_prio_supported
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Date: Aug, 2021
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KernelVersion: v5.15
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Contact: linux-ide@vger.kernel.org
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Description:
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(RO) Indicates if the device supports the SATA NCQ (native
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command queueing) priority feature.
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What: /sys/block/*/device/sas_ncq_prio_supported
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Date: Aug, 2021
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KernelVersion: v5.15
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Contact: linux-ide@vger.kernel.org
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Description:
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(RO) This is the equivalent of the ncq_prio_supported attribute
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file for SATA devices connected to a SAS host-bus-adapter
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(HBA) implementing support for the SATA NCQ priority feature.
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This file does not exist if the HBA driver does not implement
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support for the SATA NCQ priority feature, regardless of the
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device support for this feature.
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