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

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Date:   Fri, 6 Oct 2017 00:41:56 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andi Kleen <andi@...stfloor.org>
cc:     x86@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>,
        Jonathan McDowell <noodles@...th.li>
Subject: Re: [PATCH v8 2/5] x86/cpuid: Add generic table for cpuid
 dependencies

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.

> +	{ 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?

Thanks,

	tglx