APIC support prevents power off

On some UP boards (e.g. ASUS A7A266) enabling support for local APICs keeps the machine from powering off on shutdown. It will just hang instead.

This has been observed by others before [1]. A warning in the respective configuration note seems in order (or a proper fix if anybody has one).

Roger

[1] http://marc.theaimsgroup.com/?l=linux-kernel&m=105561164424871&w=2