What is the earliest x86 64bit CPU we support?

[Justin M. Forbes]

On Mon, 2012-05-21 at 10:41 -0400, Tom Callaway wrote:
> So... what is it?
> 
> I think the earliest is the AMD Opteron (2003).
> 
> >From a "earliest in each family" perspective, I think the answer is:
> 
> AMD: AMD Opteron (2003).
> Intel: Intel Xeon (Nocona) (2004)
> VIA: VIA Nano (2008)
> 
> Excluding Itanium (thank god), are there any other early x86 64bit CPUs
> that I'm missing or any that we explicitly no longer support?
> 
> ~tom

I still have one of the original Opteron boards here, it is supported
fine (though heats the room).  AFAIK there aren't any true x86_64 CPUs
that we don't support.

Justin