V6: [PATCH] x86: Install <sys/platform/x86.h> [BZ #26124]

[H.J. Lu]

On Mon, Jun 29, 2020 at 9:49 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> >> One thing I still dislike (sorry) is the asymmetry between the usable
> >> and feature checks.  For example, why is there are usability check for
> >> VAES, but not for AES?  I believe the reason is that VAES depends on
> >> AVX/AVX2, but AES only depends on SSE2.  But even that suggests to me
> >> that for 32-bit, there should be a usable gate for that (which is false
> >> if SSE2 support has been masked).
> >
> > CPU with AES must have SSE2.  I don't think we need explicit check
> > for SSE2.
>
> But SSE2 needs operating system support, so we get the usable vs
> available distinction this way.  I think.
>

We don't check if OS supports SSE2.


-- 
H.J.