Re: [PATCH v1 02/26] x86/cpu: Sanitize CPUID(0x80000000) output

[Andrew Cooper]

On 08/05/2025 9:40 pm, H. Peter Anvin wrote:
> On May 7, 2025 1:50:48 AM PDT, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 06/05/2025 6:04 am, Ahmed S. Darwish wrote:
>>> CPUID(0x80000000).EAX returns the max extended CPUID leaf available.  On
>>> x86-32 machines
>> How certain are you that it's all 32bit CPUs?  AIUI, it's an Intel
>> specific behaviour, not shared by other x86 vendors of the same era.
>>
>> ~Andrew
> All 64-bit machines require CPUID leaf 0x80000000.

Yes, but why's that relevant?

What I'm querying is the claim that all 32-bit machines behaved as Intel
did, and returned rubble for out-of-range leaves.

~Andrew