i suspect the question might have been: 'why this change'.
If that was the question, the answer would be: to unify apic_32.c and
apic_64.c we first use tiny little changes to bring the two files in
sync. Presumably, each such change is a NOP or at least very safe - and
clearly bisectable in the worst-case.
In this case, something that only makes sense on 32-bit has been added
over to the 64-bit side. The resulting apic.c file will have to have
legacy code as well - but hopefully not too much.
Cyrill, i've applied your series to tip/x86/apic. (i have fixed the
timestamps) Please address Maciej's feedback as well, in subsequent