BDG_NMB
m_copydata(m, 0, (int)len, BDG_NMB(na, slot));
m = m_devget(BDG_NMB(na, slot), slot->len, 0, na->ifp);
dst = BDG_NMB(&dst_na->up, slot);
void *addr = BDG_NMB(na, slot);
(void *)(uintptr_t)slot->ptr : BDG_NMB(&na->up, slot);