On Mon, Dec 21, 2009 at 04:14:54PM -0600, Joel Schopp wrote:

It's a bad interface.  No matter what you choose there will be a
downside.  1) If you choose NR_CPUS, the best case of how many you
could boot without SMT, then when you boot with SMT2 or SMT4 you can
get assigned more cpus than you can boot.  2) If you choose
NR_CPUS/4, the worst case of how many you could boot, and you get a
large machine with SMT2 or SMT1 you might have said you support less
cpus than you actually do and thus not boot all the cpus.  So no
matter what you choose you could be not booting cpus in some
theoretical scenario.

We're far enough through boot to determine the threading model, so you /could/
work out what SMT we're in and divide NR_CPUS by that and give that to firmware.

Yours Tony