linux-kernel - Re: [RFC PATCH 00/10] x86: Allocate AVX512 xstate ondemand

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Message-ID: <d7be6ef4-f73e-923e-93b7-ef254bf347c0@intel.com>
Date:   Thu, 2 Dec 2021 16:58:34 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com,
        chang.seok.bae@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 00/10] x86: Allocate AVX512 xstate ondemand

On 12/2/21 4:45 PM, Jiaxun Yang wrote:
> 在2021年12月3日十二月 上午12:40，Dave Hansen写道：
>> On 12/2/21 4:36 PM, Jiaxun Yang wrote:
>>> Also we are going to have heterogeneous processors that
>>> only some cores support AVX512, it can be helpful when
>>> dealing with such processors.
>> Really?  Which x86 vendor is doing that?
> Clear lower two bits of MSR 0xAF on Alder Lake give me some suprise :-)

I honestly don't know what you're talking about.  Does poking that MSR
allowing AVX512 instructions to be executed on cores where it was
otherwise disabled?  That's entertaining, but it's far from "supported"
or even support*able* in Linux.