to be interpreted as a superpage. This is because PG_PTE_PAT is at the same
bit position in PTE as PG_PS is in a PDE.
This caused a number of regressions on amd64 systems: panic when starting
X applications, freeze during shutdown etc.
Pointy hat to: me
Tested by: gperez@entel.upc.edu, joel, dumbbell
Reviewed by: kib