[PATCH RFC v2 1/1] x86: default to not accepting Xeon Phi insns

[Jiang, Haochen]

> From: Jan Beulich <jbeulich@suse.com>
> Sent: Friday, August 1, 2025 9:34 PM
> 
> Gcc15 has Xeon Phi support removed. While we don't want to remove
> support, require these deprecated insns to be enabled explicitly.
> ---
> RFC: Likely this wants holding back until gcc15 was actually released,
>      to avoid negatively affecting in particular gcc14. Question is
>      whether just the release of gcc15 is enough, or whether we want
>      people to be able to build/use gcc14 with newer binutils as well,
>      e.g. until that branch is retired.
> 

I agree that the time when GCC15 branch retirement is the safest choice.

While at least for now we did not get complaints about removal in GCC,
we could also be more aggressive. Timing like one year after GCC15.2
got released could be ok since most people will use GCC15.2 when
they start to use GCC15. This will ease rebase effort.

Thx,
Haochen