Hi Roman,

I've noticed an oddity with CONFIG_HOTPLUG_CPU in 2.6.23-rc:
make oldconfig seems to turn it on even when nothing wants it,
increasing kernel size by about 10k; but if you then edit the
line out of .config and make oldconfig again, it correctly
offers the choice and lets it be turned off after all.

(I've not actually tried make anything_else_config.)

Attached is a 2.6.23-rc1 i386 SMP .config, CONFIG_HOTPLUG_CPU
not set, with which it should be easy to reproduce the issue: just
make oldconfig in an -rc2 or current kernel tree (being sure to
choose N for SUSPEND and HIBERNATION: those rightly select it).

I did try to work it out for myself, but didn't get very far:
suspect you'll get there much quicker!

Thanks,
Hugh