linux-kernel - Re: [PATCH v8 2/5] x86/cpuid: Add generic table for cpuid dependencies

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Date:   Thu, 5 Oct 2017 16:08:13 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Andi Kleen <andi@...stfloor.org>, x86@...nel.org, hpa@...or.com,
        linux-kernel@...r.kernel.org, Jonathan McDowell <noodles@...th.li>
Subject: Re: [PATCH v8 2/5] x86/cpuid: Add generic table for cpuid
 dependencies

On Fri, Oct 06, 2017 at 12:41:56AM +0200, Thomas Gleixner wrote:
> On Thu, 5 Oct 2017, Andi Kleen wrote:
> > +/*
> > + * Table of CPUID features that depend on others.
> > + *
> > + * This only includes dependencies that can be usefully disabled, not
> > + * features part of the base set (like FPU).
> > + */
> > +const static struct cpuid_dep cpuid_deps[] = {
> > +	{ X86_FEATURE_XSAVEOPT,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_XSAVEC,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_XSAVES,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_AVX,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_AVX512F,		X86_FEATURE_XSAVE     },
> 
> This looks redundant. AVX512F depends on AVX which itself depends on XSAVE.

True.

> 
> > +	{ X86_FEATURE_PKU,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_MPX,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_XGETBV1,		X86_FEATURE_XSAVE     },
> > +	{ X86_FEATURE_XMM2,		X86_FEATURE_XMM       },
> 
> XMM has no dependency?

Only FXSAVE, I'll add that.

Thanks,

-Andi