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Re: [Qemu-devel] [RISU v2 00/11] Support for i386/x86_64 with vector ext

From: Richard Henderson
Subject: Re: [Qemu-devel] [RISU v2 00/11] Support for i386/x86_64 with vector extensions
Date: Thu, 23 May 2019 14:29:20 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1

On 5/23/19 2:03 PM, Jan Bobek wrote:
> I ran some experiments on my laptop's Intel(R) Core(TM) i5-4210U to
> find out what actually happens. This CPU supports AVX (but not
> AVX-512) and doesn't support XSAVEC, so I only looked at XSAVE and
> XSAVEOPT (XSAVES is kernel-mode only). I found out that:
> 1. both XSAVE and XSAVEOPT do not include the AVX state if it is in
>    the initial configuration (not only XSAVEOPT),
> 2. return to initial configuration is not detected, i.e. the AVX state
>    is included even though it has been set to all zeros via vxorps,
> 3. the AVX state can be brought back to the initial configuration via
>    XRSTOR with the AVX component removed.

Thanks, for doing the tests.  I'm glad what I understood from my reading
matches experimental results.  :-)


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