[Issue 19861] core.cpuid reports the wrong number of threads

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19861

Rainer Schuetze <r.sagitario at gmx.de> changed:

           What    |Removed                     |Added
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                 CC|                            |r.sagitario at gmx.de

--- Comment #3 from Rainer Schuetze <r.sagitario at gmx.de> ---
I shortly tried it on an AMD Ryzen 8-core, and it failed, too (reported 16
cores, but 1 thread). Debugging it a bit showed that there is probably
incomplete support for CPUID#8000_0008:
https://www.amd.com/system/files/TechDocs/54945_PPR_Family_17h_Models_00h-0Fh.pdf
or
https://wiki.osdev.org/Detecting_CPU_Topology_(80x86)#AMD:_CPUID_eax.3D0x80000008

I didn't try mir-cpuid, but looking at the source code now, I don't see any use
of that CPUID function, so it probably won't work, too.

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