io apic question

[Bharath Bhushan]

I am looking at 4.9 sources.

When the local apic is mapped into SMPpt in
sys/i386/i386/pmap.c:pmap_bootstrap(), it is mapped cache-disabled
(PG_N).

When the IO apics are being mapped into SMPpt in
sys/i386/i386/mp_machdep.c:mptable_pass2(), it is *not* mapped
cache-disabled.

Why is this difference?

In 5.5, I see that ioapic_create() calls pmap_createdev(), which
allocates cache-enabled kind of mapping.

Am I missing something here?

-- 
Thanks
Bharath