I've figured out the problem in the MIPS pmap that breaks munmap() of
mapped 64-bit paddr_ts (i.e. high PCI memory space on evbmips.)

It turns out that the code was trying to pmap_remove_pv of unmanaged
(high physical memory) mappings.  Note that pmap_enter already checks
these mappings, and does not enter them, so it is a bad idea to try to
remove them.  :-)

Here's my diff, which seems to fix it.  Please review, and if OK, then I
will commit:

*** pmap.c.~1.166.~    Sat Dec 24 12:07:19 2005
--- pmap.c    Wed Mar 29 12:52:07 2006
***************
*** 730,736 ****
                  pmap->pm_stats.wired_count--;
              pmap->pm_stats.resident_count--;
              pg = PHYS_TO_VM_PAGE(mips_tlbpfn_to_paddr(entry));
!             pmap_remove_pv(pmap, sva, pg);
              if (MIPS_HAS_R4K_MMU)
                  /* See above about G bit */
                  pte->pt_entry = MIPS3_PG_NV | MIPS3_PG_G;
--- 730,737 ----
                  pmap->pm_stats.wired_count--;
              pmap->pm_stats.resident_count--;
              pg = PHYS_TO_VM_PAGE(mips_tlbpfn_to_paddr(entry));
!             if (pg)
!                 pmap_remove_pv(pmap, sva, pg);
              if (MIPS_HAS_R4K_MMU)
                  /* See above about G bit */
                  pte->pt_entry = MIPS3_PG_NV | MIPS3_PG_G;
***************
*** 789,795 ****
                  pmap->pm_stats.wired_count--;
              pmap->pm_stats.resident_count--;
              pg = PHYS_TO_VM_PAGE(mips_tlbpfn_to_paddr(entry));
!             pmap_remove_pv(pmap, sva, pg);
              pte->pt_entry = mips_pg_nv_bit();
              /*
               * Flush the TLB for the given address.
--- 790,797 ----
                  pmap->pm_stats.wired_count--;
              pmap->pm_stats.resident_count--;
              pg = PHYS_TO_VM_PAGE(mips_tlbpfn_to_paddr(entry));
!             if (pg)
!                 pmap_remove_pv(pmap, sva, pg);
              pte->pt_entry = mips_pg_nv_bit();
              /*
               * Flush the TLB for the given address.

-- 
Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
http://www.tadpolecomputer.com/
Phone: 951 325-2134  Fax: 951 325-2191