Following the CPUID extensions and APIC-ID setup presented by Richard
Brunner at Kernel Summit.

Without this the kernel's node discovery would assign the wrong nodes on
dual core systems and cause performance degradation.

Only handles power of two cored CPUs, others will be ignored.

/proc/cpuinfo has a new field cpu cores: <number of CPU cores> and also
show the other core as HT sibling (this is needed to make old CPU based
license managers to count one CPU package as only one physical CPU)

FIXME this currently misses the disable code for SMT idle.  That's because
2.6.9rc1-bk6 removed the arch hooks need for that.  Needs to be readded
later.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>