Which VIA CPUs have hardware RNG support?

[RW]

On Wed, 9 Jul 2008 11:31:36 -0400
"Joseph Gleason" <fireduck at gmail.com> wrote:

> I am trying to figure out which VIA CPUs support hardware RNG under
> recent FreeBSD.  I've been looking at things on 7.0-RELEASE-p2.  If
> there is something that else I should be looking at, please let me
> know.
> 
> Based on 'man 4 random' I see:
> "The only hardware implementation currently is for the
>      VIA C3 Nehemiah (stepping 3 or greater) CPU.  More will be added
> in the future."
> 
> Poking around in the kernel I see that indeed nehemiah and yarrow seem
> to be the only random sources there.

If you have a need for a lot of entropy, you can also use the kernel RC4
generator via "sysctl kern.arandom".

A couple of other hardware sources are implemented as yarrow entropy
sources rather than using the hardware generator directly. I think the
support for AMD Geode LX, will be of this form. I suspect that this is
more secure than the nehemiah support since it doesn't actually rely on
on the hardware alone.