linux-kernel - Re: [tip:x86/urgent] x86/cpufeature: Add AVX512_4VNNIW and AVX512

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Message-ID: <EF5DC108-C5D8-4DD6-9BF4-4E02F0826B9E@zytor.com>
Date:   Sun, 16 Oct 2016 11:42:26 -0700
From:   hpa@...or.com
To:     Borislav Petkov <bp@...en8.de>
CC:     Ingo Molnar <mingo@...nel.org>, peterz@...radead.org,
        tglx@...utronix.de, dave.hansen@...el.com,
        torvalds@...ux-foundation.org, piotr.luc@...el.com,
        luto@...nel.org, brgerst@...il.com, linux-kernel@...r.kernel.org,
        dvlasenk@...hat.com, jpoimboe@...hat.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86/cpufeature: Add AVX512_4VNNIW and AVX512_4FMAPS features

On October 16, 2016 9:35:57 AM PDT, Borislav Petkov <bp@...en8.de> wrote:
>On Sun, Oct 16, 2016 at 09:02:51AM -0700, hpa@...or.com wrote:
>> No, please.  That would be worse than the disease.
>
>Why not?
>
>I did that recently with a bunch of leaves and there were no issues:
>
>2ccd71f1b278 ("x86/cpufeature: Move some of the scattered feature bits
>to x86_capability")
>
>There it obviously made sense for 0x00000006 and 0x8000000a to have a
>separate ->x86_capability leaf.

It's needlessly adding complexity for no reason, at least for the leaves that are going to add bits over time.  The x86_capability array is not an expensive resource.
-- 
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