Problem is that I need a architecture specific hook to 
turn off SMT idle for AMD dual core CPUs, which otherwise
look like SMT siblings. I suppose I will do more tunings
in this area in the future anyways, so having it in the 
architecture would be better.

From a ppc64 perspective I liked the merging of the domains code.

We could have the ability to override generic domain setup per
architecture but leave all the default stuff in there.

Anton