linux-kernel - Re: Candidate Linux ABI for Intel AMX and hypothetical new related features

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Message-ID: <20210412143139.GE24283@zn.tnic>
Date:   Mon, 12 Apr 2021 16:31:39 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Florian Weimer <fweimer@...hat.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        "Bae, Chang Seok" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...el.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-abi@...r.kernel.org,
        "libc-alpha@...rceware.org" <libc-alpha@...rceware.org>,
        Rich Felker <dalias@...c.org>, Kyle Huey <me@...ehuey.com>,
        Keno Fischer <keno@...iacomputing.com>
Subject: Re: Candidate Linux ABI for Intel AMX and hypothetical new related
 features

On Mon, Apr 12, 2021 at 04:19:29PM +0200, Florian Weimer wrote:
> Maybe we could have done this in 2016 when I reported this for the first
> time.  Now it is too late, as more and more software is using
> CPUID-based detection for AVX-512.

So as I said on another mail today, I don't think a library should rely
solely on CPUID-based detection of features especially if those features
need kernel support too. IOW, it should ask whether the kernel can
handle those too, first.

And the CPUID-faulting thing would solve stuff like that because then
the kernel can *actually* get involved into answering something where it
has a say in, too.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette