Re: enable dual rng on VIA C7

From: Udo van den Heuvel
Date: Tue Nov 27 2007 - 11:09:21 EST


Dave Jones wrote:
> On Mon, Nov 26, 2007 at 06:02:39PM +0100, Udo van den Heuvel wrote:
>
> > I did not know we are already that far ;-)
> > I mean: can this patch be aplied without hurting C3/C7 CPU's with just
> > one RNG? Maybe an expert needs to test/answer?
> > Maybe some logic needs to be applied around the extra bit?
>
>>From the padlock spec..
>
> "SRC Bits[9:8] Noise source select (I): These bits control the two noise
> sources on the processor that input bits to the accumulation buffers.
> On Nehemiah processors prior to stepping 8, these bits are reserved
> and undefined. The default RESET state is both bits = 0."
>
> Something like this perhaps ?

Yes, I think that's a big step in the right direction!

But I am no expert and cannot really judge how necessary or correct the
implementation is w.r.t. the 'undefined' function bits for CPU's that
lack a certain feature.
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