Followup for myself...

> When things
> were well ironned out, a small number of files to be added or modified
> to make NetBSD/mips64 possible. 
> - pmap64.c
> - pmap.c
> ...
Add mips_machdep.c as a kitchen sink for dirty matters.

The reason why the two are in parallel is two (incompatible) PTE
managements are planed for them.  For 32bit only kernel, linear
PTE array in KSEG2 range would just work  This arrangement is
expected to reduce TLB refill overhead.
64bit address space would require to traverse traditional-but-very-sparse
multiple level PTE tree, probably similar to NetBSD/alpha, to cover its larger
address space extent.  For N32 process,  PTE tree traverse would not be
worse since our pmap.c in use does two level table-walk anyway.

Toru Nishimura/ALKYL Technology