Re: [PATCH v10 01/15] x86/cpu: Enumerate the LASS feature bits

Xin Li
2025-10-07T23:18:10Z

On 10/8/2025 4:49 AM, Sohil Mehta wrote:
>>>
>>> +config X86_DISABLED_FEATURE_LASS
>>> + def_bool y
>>> + depends on X86_32
>>> +
>> All the other ones in the file are !X86_64. Why do this one X86_32?
>>
> The double negation (DISABLED and !X86_64) was harder to follow when
> this was initially posted.
>
> https://lore.kernel.org/lkml/73796800-819b-4433-b0ef-db852336d7a4@zytor.com/
> https://lore.kernel.org/lkml/756e93a2-7e42-4323-ae21-
> a5437e71148e@infradead.org/
>
> I don't have a strong preference. I guess the inconsistency makes it
> confusing as well. Will change it back to !X86_64 unless Xin objects.

I prefer to use X86_32, which is more direct.

Now the only disabled feature when !X86_64 is X86_DISABLED_FEATURE_PCID.
And I would expect the disabled features due to lack of 32-bit enabling
will keep growing until we remove 32-bit kernel code. I was also thinking
to move all such disabled features to a dedicated file when the total
reaches 3. But hopefully removing 32-bit will happen first.