PG_PROT
#define pmap_pte_prot(pte) (*(pte) & PG_PROT)
*(pte) &= ~PG_PROT; \
npte = (opte & ~PG_PROT) | md_prot;
(~md_prot & opte) & PG_PROT);
npte = (opte & ~(pt_entry_t)PG_PROT) | md_prot;
bits = ptp[l1idx] & (PG_PROT|PG_N|PG_WT);
npte = ap | (opte & ~PG_PROT);