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

H.J. Lu hjl.tools@gmail.com
Tue Jun 30 00:29:42 GMT 2020

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.


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