On Sun, Aug 25, 2019 at 2:45 AM Thomas Gleixner <[email protected]> wrote:
>
> - Clear the RDRAND CPUID bit on AMD family 15h and 16h CPUs which are
> affected by broken firmware which does not initialize RDRAND correctly
> after resume. Add a command line parameter to override this for machine
> which either do not use suspend/resume or have a fixed
> BIOS. Unfortunately there is no way to detect this on boot, so the only
> safe decision is to turn it off by default.
Not doing the Zen 2 boot-time case? Everybody assumes that all
firmware has been fixed?
That one should be easy to verify since it happens at boot: just do
"rdrand" twice, and if it returns all-ones both times, it's broken.
Linus
