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

Florian Weimer fweimer@redhat.com
Tue Jun 30 09:46:01 GMT 2020

* 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.

Isn't this a bug?  Not that it matters much these days, but how did this
work in the beginning?


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