More data points:

It turns out that mpbios_search() finds a valid MP signature but the
checksum of the `mpbios_fps' structure does not add up to 0 (the computed
checksum is 0x30, the `checksum' field in the mpbios_fps structure is 0).

Ignoring the checksum error (allowing mpbios_scan to proceed) results
in this:

	Intel MP Specification  (COMPAQ   PROLIANT)
	panic: cpu0: running cpu is at apic 255 instead of expected 0