Index: sys/dev/cxgbe/t4_netmap.c
===================================================================
--- sys/dev/cxgbe/t4_netmap.c
+++ sys/dev/cxgbe/t4_netmap.c
@@ -334,6 +334,21 @@
 	return (rc);
 }
 
+static void
+propagate_capenable_to_hwassist(struct ifnet *ifp)
+{
+	uint64_t hwassist = ifp->if_hwassist & ~(CSUM_TCP | CSUM_UDP | CSUM_IP |
+		CSUM_UDP_IPV6 | CSUM_TCP_IPV6);
+
+	if (ifp->if_capenable & IFCAP_TXCSUM) {
+		hwassist |= CSUM_TCP | CSUM_UDP | CSUM_IP;
+	}
+	if (ifp->if_capenable & IFCAP_TXCSUM_IPV6) {
+		hwassist |= CSUM_TCP_IPV6 | CSUM_UDP_IPV6;
+	}
+	ifp->if_hwassist = hwassist;
+}
+
 static int
 cxgbe_netmap_on(struct adapter *sc, struct vi_info *vi, struct ifnet *ifp,
     struct netmap_adapter *na)
@@ -363,6 +378,8 @@
 	}
 	hwidx = i;
 
+	propagate_capenable_to_hwassist(ifp);
+
 	/* Must set caps before calling netmap_reset */
 	nm_set_native_flags(na);
 
@@ -504,6 +521,8 @@
 		if_printf(ifp, "failed to restore RSS hash/defaultq: %d\n", rc);
 	nm_clear_native_flags(na);
 
+	propagate_capenable_to_hwassist(ifp);
+
 	for_each_nm_txq(vi, i, nm_txq) {
 		struct sge_qstat *spg = (void *)&nm_txq->desc[nm_txq->sidx];