RE: [PATCH] KVM: selftests: x86: Avoid using SSE/AVX instructions

Vitaly Kuznetsov
2024-09-24T12:04:11Z

David Laight <David.Laight@ACULAB.COM> writes:

> From: Vitaly Kuznetsov <vkuznets@redhat.com>
>> Sent: 20 September 2024 16:44
>>
>> Some distros switched gcc to '-march=x86-64-v3' by default and while it's
>> hard to find a CPU which doesn't support it today,
>
> I didn't think that any of the Atom based cpu supported AVX.
> I'm pretty sure one we use that are still in production as
> server motherboards don't support it.
>
> Doesn't -v3 also require support for the VEX encoding.
> Which removes a lot of perfectly reasonable cpu?
>

Well, distros making such decision are obviously not very interested in
running on these CPUs then :-) In this particular case, the distro was
Centos Stream 10 and they are very explicit about the decision:
https://developers.redhat.com/articles/2024/01/02/exploring-x86-64-v3-red-hat-enterprise-linux-10#new_cpu_capabilities_in_x86_64_v3

and 'gcc -v' tells me

Configured with: ../configure ... --with-arch_64=x86-64-v3 ...
...
gcc version 14.2.1 20240801 (Red Hat 14.2.1-1) (GCC)

--
Vitaly