Re: [PATCH v1 02/26] x86/cpu: Sanitize CPUID(0x80000000) output
Andrew Cooper <[email protected]>
| Newsgroups | dev.linux.lists.x86-cpuid,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On 08/05/2025 9:40 pm, H. Peter Anvin wrote: > On May 7, 2025 1:50:48 AM PDT, Andrew Cooper <[email protected]> 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