I'm not sure if this is the most appropriate list to report a 'bug' in the 
-CURRENT sources (please correct me if not) but as the subject says 
INSTALL.MP fails to compile due to a missing declaration of either MPBIOS or 
MPACPI.
For reference:
src/sys/arch/x86/x86/ioapic.c:102
#error "ioapic needs at least one of the MPBIOS or MPACPI options"

Adam