Re: [PATCH v3 3/4] Add hwcap2 for x86

From: Thomas Gleixner
Date: Thu Oct 13 2016 - 12:06:11 EST

On Thu, 13 Oct 2016, Grzegorz Andrejczuk wrote:

> Add hwcap2 attribute for x86.

Great value in repeating the subject line. And the subject line is crap
because this patch does way more than adding hwcap2 ....

> Reserve 1st bit of HWCAP2 for exposing Xeon Phi ring 3 monitor/mwait.
> With this userspace apps can detect Ring 3 MONITOR/MWAIT instructions.

User space cannot detect the instructions. User space can check whether the
instructions are enabled.

> +/* Kernel enabled Ring 3 MWAIT for Xeon Phi*/
> +#define HWCAP2_PHIR3MWAIT (1 << 0)
> +/* upto bit 31 free */

Very useful comment, NOT! Stop documenting the obvious.