linux-kernel - Re: [PATCH v6: 4/4] x86/cpufeature: Add R3MWAIT to CPU features

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Date:   Thu, 27 Oct 2016 16:30:15 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, dave.hansen@...ux.intel.com,
        lukasz.daniluk@...el.com, james.h.cownie@...el.com,
        jacob.jun.pan@...el.com, Piotr.Luc@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6: 4/4] x86/cpufeature: Add R3MWAIT to CPU features

On Thu, Oct 27, 2016 at 04:02:03PM +0200, Grzegorz Andrejczuk wrote:
> Add cpu feature for ring 3 monitor/mwait.
> Set HWCAP2 1st bit during init.
> 
> Signed-off-by: Grzegorz Andrejczuk <grzegorz.andrejczuk@...el.com>
> ---
>  arch/x86/include/asm/cpufeatures.h | 2 ++
>  arch/x86/kernel/cpu/intel.c        | 4 ++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 92a8308..d430200 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -71,6 +71,8 @@
>  #define X86_FEATURE_RECOVERY	( 2*32+ 0) /* CPU in recovery mode */
>  #define X86_FEATURE_LONGRUN	( 2*32+ 1) /* Longrun power control */
>  #define X86_FEATURE_LRTI	( 2*32+ 3) /* LongRun table interface */
> +/* Xeon Phi x200 ring 3 MONITOR/MWAIT enabled */
> +#define X86_FEATURE_PHIR3MWAIT	( 2*32+ 4)

This leaf is for Transmeta CPUs:

/* Transmeta-defined CPU features, CPUID level 0x80860001, word 2 */

is KNL close to some Transmeta design, per chance or so?

I mean, for this to work, it would have to implement CPUID leaf
0x80860001...

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--