Re: [Xen-devel] [PATCH] x86/EFI: meet further spec requirements for runtime calls

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 10/11/16 16:06, Jan Beulich wrote:
> So far we didn't guarantee 16-byte alignment of the stack: While (so
> far) we don't tell the compiler to use smaller alignment, we also don't
> guarantee 16-byte alignment when establishing stack pointers for new
> vCPU-s. Runtime service functions using SSE instructions may end with
> #GP(0) without that.
>
> Note that -mpreferred-stack-boundary=3 is can be used only from gcc 4.8
> onwards, and -mincoming-stack-boundary=3 only from 5.3 onwards. It is
> for that reason that an alternative approach (using higher than
> necessary alignment) is being used when building with such older
> compilers.
>
> Furthermore we should avoid #MF to be raised on the FLDCW we do.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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