pmap_ptpage_alloc
error = pmap_ptpage_alloc(pmap, l1pte, PGU_L2PT);
error = pmap_ptpage_alloc(pmap, l2pte, PGU_L3PT);
static int pmap_ptpage_alloc(pmap_t, pt_entry_t *, int);
newptp = pmap_ptpage_alloc(segtab, nowait);
ppg = pmap_ptpage_alloc(pmap, flags, &pa);