Commit-ID: 203dffacf592317e54480704f569a09f8b7ca380 Gitweb: https://git.kernel.org/tip/203dffacf592317e54480704f569a09f8b7ca380 Author: Fenghua Yu <fenghua...@intel.com> AuthorDate: Wed, 19 Jun 2019 18:33:58 -0700 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Mon, 24 Jun 2019 01:44:35 +0200
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...@intel.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Ashok Raj <ashok....@intel.com> Cc: "Borislav Petkov" <b...@alien8.de> Cc: "H Peter Anvin" <h...@zytor.com> Cc: "Andy Lutomirski" <l...@kernel.org> Cc: "Peter Zijlstra" <pet...@infradead.org> Cc: "Tony Luck" <tony.l...@intel.com> Cc: "Ravi V Shankar" <ravi.v.shan...@intel.com> Link: https://lkml.kernel.org/r/1560994438-235698-6-git-send-email-fenghua...@intel.com --- Documentation/ABI/testing/sysfs-devices-system-cpu | 23 ++++++++++++++++++++++ 1 file changed, 23 insertions(+) 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.
