On Thu, Aug 15, 2019 at 01:47:24PM +0000, Lendacky, Thomas wrote:
> Sure, I can do that. Do we want to tie this into the nordrand option and
> add rdrand=off or keep that separate?
Yeah, I was looking at that this morning and I'd say keep 'em separate
because if you have to tie, you need to export functions and then
there's
setup_clear_cpu_cap(X86_FEATURE_RDSEED);
in the nordrand callback but then F15h and F16h don't have RDSEED and
people would wonder, why clear RDSEED on AMD, blabla... so keeping them
separate saves us all that.
> I think this is a clearer indication that the action has taken place.
Yeah, but what does that bring us? You wanna know this now, while
testing. Once that whole effort is done, it is a useless printing of
info which you have in cpuinfo already.
> Not sure what you mean. We can't use the DMI stuff for this. So now, with
> the x86 family checks, if anyone adds some DMI stuff or x86 family stuff
> in the future that matches both the DMI and x86 family checks, this will
> be called more than once and so you need to copy any previous settings and
> add the new ones.
I had a suspicion that it was something like that. Ok, this is not a
big structure currently so I guess it is fine but if it keeps growing,
it would need a proper redesign like making it a list and callbacks
doing list_add_tail() for MSRs which get added. It would avoid that
kmalloc and copying which is silly. Please put a comment ontop why we're
copying.
> Except that X86_FEATURE_RDRAND isn't set anymore. I could create a new
> software feature that is set when the CPUID bit is cleared if that's
> preferred.
Nah, let's leave it like you had it.
Thx.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
