Re: [PATCH v2] KVM: x86: Remove AMX-TF32 enumeration

[Christian Ludloff]

On Tue, Aug 18, 2026 at 5:55 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> On 7/24/26 08:37, Christian Ludloff wrote:
> >> My understanding is that the revert was considered because TF32 never
> >> reached any implementation. If that's incorrect, I'd certainly welcome a
> >> correction.
> > Both TF32 and TRANSPOSE made it into a product that shipped.
> >
> > Not from Intel... but.
> >
> > So their CPUID feature flags and their opcodes aren't reclaimable
> > and efforts to rip out their software support are counterproductive.
>
> What would folks' preference be on how Intel should document this going
> forward? Just leave it as it as enumerating TF32?
>
> There are notes in the SDM like:
>
>         Intel® MPX has been deprecated and will not be available on any
>         future processors.
>
> There could be a note like that for the TF32, I would imagine.

Yes, that terse sentence works.
  Once for AMX-TRANSPOSE.
  Once for AMX-TF32.

If you want the back references:
  TRANSPOSE got dropped from ISE #059 and APX #007.
  TF32 got dropped from ISE #062.

In terms of the opcodes, it is like MPX too: no recycling for
a long time. Luckily there is plenty of remaining space.

--
C.