_CRSTE_EMPTY
#define _PMD_EMPTY _CRSTE_EMPTY(TABLE_TYPE_SEGMENT)
union crste oldcrste, empty = _CRSTE_EMPTY(crstep->h.tt);
ok = gmap_crstep_xchg_atomic(priv->gmap, crstep, old, _CRSTE_EMPTY(old.h.tt), gfn);
ok = gmap_crstep_xchg_atomic(priv->gmap, crstep, old, _CRSTE_EMPTY(old.h.tt), gfn);
table = dat_alloc_crst_sleepable(_CRSTE_EMPTY(type).val);
if (oldval.val != _CRSTE_EMPTY(oldval.h.tt).val &&
newcrste = _CRSTE_EMPTY(crste.h.tt);