On Wed, Aug 20, 2025 at 01:41:28PM +0530, Naveen N Rao wrote:
> That suggests use of leaf 0xb for the initial x2APIC ID especially
> during early init. I'm not sure why leaf 0x8000001e was preferred over
> leaf 0xb in commit c749ce393b8f ("x86/cpu: Use common topology code for
> AMD") though.
Well, I see parse_topology_amd() calling cpu_parse_topology_ext() if you have
TOPOEXT - which all AMD hw does - which then does cpu_parse_topology_ext() and
that one tries 0x80000026 and then falls back to 0xb and *only* *then* to
0x8000001e.
So, it looks like it DTRT to me...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
