Re: [PATCH v4 1/4] x86/cpu/topology: Use initial APIC ID from XTOPOLOGY leaf on AMD/HYGON

On 8/25/2025 1:27 PM, K Prateek Nayak wrote:

AMD64 Architecture Programmer's Manual Volume 2: System Programming Pub. 24593 Rev. 3.42 [2] Section 16.12 "x2APIC_ID" mentions the Extended Enumeration leaf 0x8000001e (which was later superseded by the extended

The above should have been CPUID leaf 0xb (Fn0000_000B_EDX[31:0]) and not 0x8000001e. Sorry for the oversight.

leaf 0x80000026) provides the full x2APIC ID under all circumstances unlike the one reported by CPUID leaf 0x8000001e EAX which depends on the mode in which APIC is configured.