Documentation/ABI: Document umwait control sysfs interfaces (203dffac) · Commits · 戴 / test

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

Documentation/ABI/testing/sysfs-devices-system-cpu

+23 −0

Original line number	Diff line number	Diff line
		@@ -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.

Admin message