However... Even though we *can* support non-X2APIC processors, we *might* want to play it safe and not go back that far; only enabling parallel bringup on machines with X2APIC which roughly correlates with "lots of CPUs" since that's where the benefit is.
I think that this is the right approach, at least on the initial patch series. KISS principle; do all the easy-but-important cases first, get it stable and working and in later series/kernels the range can be expanded.... if it matters.
