Re: [PATCH 1/2] x86: eliminate TS_XSAVE

From: Suresh Siddha
Date: Tue May 04 2010 - 14:04:45 EST


On Sun, 2010-05-02 at 07:53 -0700, Avi Kivity wrote:
> The fpu code currently uses current->thread_info->status & TS_XSAVE as
> a way to distinguish between XSAVE capable processors and older processors.
> The decision is not really task specific; instead we use the task status to
> avoid a global memory reference - the value should be the same across all
> threads.
>
> Eliminate this tie-in into the task structure by using an alternative
> instruction keyed off the XSAVE cpu feature; this results in shorter and
> faster code, without introducing a global memory reference.
>
> Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>

Acked-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>

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