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

Brian Gerst
2010-05-02T17:38:43Z

On Sun, May 2, 2010 at 10:53 AM, Avi Kivity <avi@redhat.com> 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.

I think you should either just use cpu_has_xsave, or extend this use
of alternatives to all cpu features. It doesn't make sense to only do
it for xsave.

--
Brian Gerst