The attached patch is against 2.6.8-rc1-mm1. Tested on SMP, UP and SMP+HT
here and it seems to be OK.

I have included the cpu_sibling_map for ppc64, although Anton said he did
have an implementation floating around which he would probably prefer, but
I'll let him deal with that.

Anyway, x86-64 is not equivalent before and after this patch. The main
thing is that they've been using SD_CPU_INIT for NUMA nodes, but will now
use SD_NODE_INIT. Probably neither is optimal, but I don't think Andi has
had much time to look at it. I should be able to take a look at it soon.

Nick