0/5 Fix Summit support

This sequence makes Summit finally work properly - most of the code was originally written by James Cleverdon, and it has been split up and cleaned up by John Stultz and I.

I've tested these on UP, standard SMP, NUMA-Q and Summit, and have test-compiled them for UP+IO-APIC as well. They should change nothing at all for standard machines.

Please apply, thanks,

Martin.