Re: [PATCH] x86/cpu/centaur: Disable X86_FEATURE_FSGSBASE on Zhaoxin C4600

[Tony W Wang-oc]

On 2026/3/6 04:26, Christian Ludloff wrote:
> Tony,
>
> can you confirm whether F=6 M=1F is affected or not?
> (Supposedly that's ZX-D... but the F in the model does
> make me wonder/ask.)
This bug existed only in certain early ucode revisions of the ZX-C/ZX-C+ 
series CPUs, and is not present in the ZX-D.

> Presumably the 6FE and 10690 microcodes which are
> out in the wild do not fix the bug, correct?
>
> 000006fe_00000000_20110809_8f396f73
> 000006fe_00000000_20110809_8f397072
> 000006fe_00000001_20160525_7214d1e1
> 000006fe_00000001_20170109_25646399
> 000006fe_00000001_20180726_6e07329b
> 000006fe_00000001_20180726_6e1e984b
>
> 00010690_00000000_20110809_259878a5
> 00010690_00000001_20160525_3c34fc1a
> 00010690_00000001_20170109_a8b24dc2
> 00010690_00000001_20180726_0c55f25d
> 00010690_00000001_20180726_41faefde
No, The four patches with the display date of 20180726 should not have 
this bug.

> As for making the code conditional for Centaur/Zhaoxin,
> stepping E seems to be when FSGSBASE arrived – and
> while there are CPUID dumps for 6FE that say VIA Eden
> it is possible that they too have the bug.
Sorry, VIA Eden is too old, we haven't been able to find actual hardware 
to confirm this.

> As for making the code conditional for Zhaoxin models in
> the string, that would require more than just C4600 – the
> collection of known dumps includes others.
Yes, ZX-C/ZX-C+ series CPUs have other strings.

Sincerely!
TonyWWang-oc
> --
> C.