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| author |   Fenghua Yu <fenghua.yu@intel.com> | 2019-06-19 18:33:58 -0700 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2019-06-24 01:44:35 +0200 |
| commit | 203dffacf592317e54480704f569a09f8b7ca380 (patch) | |
| tree | ddcda0fb71369c87a2a368cdace4cb88b6a02186 /Documentation/ABI/testing/sysfs-devices-system-cpu | |
| parent | x86/umwait: Add sysfs interface to control umwait maximum time (diff) | |
| download | linux-dev-203dffacf592317e54480704f569a09f8b7ca380.tar.xz linux-dev-203dffacf592317e54480704f569a09f8b7ca380.zip | |
Documentation/ABI: Document umwait control sysfs interfaces
Since two new sysfs interface files are created for umwait control, add
an ABI document entry for the files:
/sys/devices/system/cpu/umwait_control/enable_c02
/sys/devices/system/cpu/umwait_control/max_time
[ tglx: Made the write value instructions readable ]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Cc: "Borislav Petkov" <bp@alien8.de>
Cc: "H Peter Anvin" <hpa@zytor.com>
Cc: "Andy Lutomirski" <luto@kernel.org>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/1560994438-235698-6-git-send-email-fenghua.yu@intel.com
Diffstat (limited to '')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-system-cpu | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 1528239f69b2..923fe2001472 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -538,3 +538,26 @@ Description: Intel Energy and Performance Bias Hint (EPB) This attribute is present for all online CPUs supporting the Intel EPB feature. + +What: /sys/devices/system/cpu/umwait_control + /sys/devices/system/cpu/umwait_control/enable_c02 + /sys/devices/system/cpu/umwait_control/max_time +Date: May 2019 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: Umwait control + + enable_c02: Read/write interface to control umwait C0.2 state + Read returns C0.2 state status: + 0: C0.2 is disabled + 1: C0.2 is enabled + + Write 'y' or '1' or 'on' to enable C0.2 state. + Write 'n' or '0' or 'off' to disable C0.2 state. + + The interface is case insensitive. + + max_time: Read/write interface to control umwait maximum time + in TSC-quanta that the CPU can reside in either C0.1 + or C0.2 state. The time is an unsigned 32-bit number. + Note that a value of zero means there is no limit. + Low order two bits must be zero. |