V6: [PATCH] x86: Install <sys/platform/x86.h> [BZ #26124]
Tue Jun 30 00:29:42 GMT 2020
On Mon, Jun 29, 2020 at 9:49 AM Florian Weimer <firstname.lastname@example.org> 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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