netmap_get_na
error = netmap_get_na(hdr, &na, &ifp, nmd,
error = netmap_get_na(hdr, &na, &ifp, NULL, 1 /* create */);
error = netmap_get_na(hdr, &na, &ifp, NULL, 0);
error = netmap_get_na(hdr, &na, &ifp, NULL, 1 /* create */);
int netmap_get_na(struct nmreq_header *hdr, struct netmap_adapter **na,
error = netmap_get_na(hdr, &pna, &ifp, nmd, create);
error = netmap_get_na(hdr, &pna, &ifp, nmd, create);