netmap_hw_dtor
static void netmap_hw_dtor(struct netmap_adapter *); /* needed by NM_IS_NATIVE() */
hwna->up.nm_dtor = netmap_hw_dtor;
#define NM_IS_NATIVE(ifp) (NM_NA_VALID(ifp) && NA(ifp)->nm_dtor == netmap_hw_dtor)