Re: [PATCH v2] x86/amd: Disable RDSEED on AMD Zen5 because of an error.

[Borislav Petkov]

On Mon, Nov 03, 2025 at 03:55:53PM -0800, Christopher Snowhill wrote:
> https://lore.kernel.org/lkml/9a27f2e6-4f62-45a6-a527-c09983b8dce4@xxxxxxxxxxx/

tglx already summed up what the options are:

https://lore.kernel.org/all/878qgnw0vt.ffs@tglx

> Qt is built with -march=znver4, which automatically enables -mrdseed.
> This is building rdseed 64 bit, but then the software is also performing
> kernel feature checks on startup. There is no separate feature flag for
> 16/32/64 variants.

No, there aren't.

And the problem here is that, AFAICT, Qt is not providing a proper fallback
for !RDSEED. Dunno, maybe getrandom(2) or so. It is only a syscall which has
been there since forever. Rather, it would simply throw hands in the air.

Soon there will be client microcode fixes too so all should be well.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette