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

From: Christopher Snowhill
Date: Mon Nov 03 2025 - 05:22:59 EST




On Sun 19 Oct 2025 05:03:25 PM , Jason A. Donenfeld wrote:
> On Sun, Oct 19, 2025 at 05:00:27PM +0200, Borislav Petkov wrote:
> > On Sun, Oct 19, 2025 at 04:46:06PM +0200, Jason A. Donenfeld wrote:
> > > While your team is checking into this, I'd be most interested to know
> > > one way or the other whether this affects RDRAND too.
> >
> > No it doesn't, AFAIK. The only one affected is the 32-bit or 16-bit dest
> > operand version of RDSEED. Again, AFAIK.
>
> Oh good. So on 64-bit kernels, the impact to random.c is zilch.
>
> Jason
>

Although apparently, the patch does break userspace for any distribution
building packages with -march=znver4

- Christopher

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