sys/i386/xen/mptable.c:
Set PCPU apic_id and acpi_id fields in a fasion compatible with
both UP and SMP configurations.
Suggested by: jhb
Submitted by: Roger Pau Monné
Sponsored by: Citrix Systems R&D
Reviewed by: gibbs
Approved by: re (blanket Xen)
MFC after: 2 weeks