Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits

H. Peter Anvin
2025-06-21T00:51:18Z

On 2025-06-20 17:45, H. Peter Anvin wrote:
>>
>> But I simply hate adding a disabled feature that depends on !X86_64;
>> x86_64 has a broad scope, and new CPU features are often intentionally
>> not enabled for 32-bit.
>>
>> (X86_DISABLED_FEATURE_PCID is the only one before LASS)
>
> More importantly, it is wrong.
>
> The 32-bit build can depend on this feature not existing, therefore it SHOULD be listed as a disabled feature.
>

Ok, that was word salad. What I meant was that the original patch is
correct, and we SHOULD have this as a disabled feature.

The reason is that it reduces the need to explicitly test for 32/64 bits
for features that don't exist on 32 bits. When they are flagged as
disabled, they get filtered out *at compile time*.

-hpa