Re: [PATCH v2 2/2] x86/cpuid: Update bitfields to x86-cpuid-db v3.1

[Ahmed S. Darwish]

On Thu, 04 Jun 2026, Ingo Molnar wrote:
>
> * Maciej Wieczor-Retman <m.wieczorretman@xxxxx> wrote:
> >
> > Update leaf_types.h to version 3.1, as generated by x86-cpuid-db.
> >
>
> The following detail from the first submission got lost:
>
> > @@ -246,7 +246,7 @@ struct leaf_0x6_0 {
> > -		thrd_director_nclasses		:  8, // Number of classes, Intel thread director
> > +		hw_feedback_nclasses		:  8, // Number of Intel Thread Director classes
> >
> > Note, for CPUID(0x6) thrd_director_nclasses, it was written this way
> > because the project does not support bitfields names with more letters.
>
> What does this mean exactly, is there a string length limit on the
> field name in 'struct leaf_0x6_0'? What is the limit?
>

Sorry, I should've made that more clear in the x86-cpuid-db release notes.
Yes, there is a limit on field name lenghts so that the C headers formatted
output is aligned and human readable.  It's an implementation detail.

After Maciej's patch:

    https://gitlab.com/x86-cpuid.org/x86-cpuid-db/-/commit/a7af01507814

I searched for more typos, grammatical mistakes, etc. and fixed some:

    https://gitlab.com/x86-cpuid.org/x86-cpuid-db/-/commit/41380ff73e60

Fixing thrd_director_nclasses name would exceed the project's field limit
(23 characters), so I checked the manuals, and hw_feedback_nclasses was a
better name anyway, and thus used it.

That's the whole rationale.

I guess this can be appened to the kernel patch changelog:

  Note, for CPUID(0x6) the "thrd_director_nclasses" field is replaced with
  "hw_feedback_nclasses" in this x86-cpuid-db release.  Fixing the typo of
  the former would exceed the project's bitfield names chracter limit, and
  the latter name is more descriptive.  See [link to x86-cpuid-db commit.]

Thanks,
Ahmed