Index: head/sys/dev/hyperv/netvsc/hv_net_vsc.h
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_net_vsc.h
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.h
@@ -228,7 +228,8 @@
 	struct vmbus_xact_ctx *hn_xact;
 	uint32_t	hn_nvs_ver;
 
-	uint32_t		hn_flags;
+	uint32_t		hn_caps;	/* HN_CAP_ */
+	uint32_t		hn_flags;	/* HN_FLAG_ */
 	void			*hn_rxbuf;
 	uint32_t		hn_rxbuf_gpadl;
 	struct hyperv_dma	hn_rxbuf_dma;
@@ -245,6 +246,16 @@
 #define HN_FLAG_RXBUF_CONNECTED		0x0001
 #define HN_FLAG_CHIM_CONNECTED		0x0002
 
+#define HN_CAP_VLAN			0x0001
+#define HN_CAP_MTU			0x0002
+#define HN_CAP_IPCS			0x0004
+#define HN_CAP_TCP4CS			0x0008
+#define HN_CAP_TCP6CS			0x0010
+#define HN_CAP_UDP4CS			0x0020
+#define HN_CAP_UDP6CS			0x0040
+#define HN_CAP_TSO4			0x0080
+#define HN_CAP_TSO6			0x0100
+
 /*
  * Externs
  */
Index: head/sys/dev/hyperv/netvsc/hv_net_vsc.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_net_vsc.c
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.c
@@ -467,9 +467,15 @@
 
 	/* NOTE: No response. */
 	error = hn_nvs_req_send(sc, &conf, sizeof(conf));
-	if (error)
+	if (error) {
 		if_printf(sc->hn_ifp, "send nvs ndis conf failed: %d\n", error);
-	return (error);
+		return (error);
+	}
+
+	if (bootverbose)
+		if_printf(sc->hn_ifp, "nvs ndis conf done\n");
+	sc->hn_caps |= HN_CAP_MTU | HN_CAP_VLAN;
+	return (0);
 }
 
 static int
Index: head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
+++ head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
@@ -325,6 +325,7 @@
 static int hn_tx_stat_ulong_sysctl(SYSCTL_HANDLER_ARGS);
 static int hn_tx_conf_int_sysctl(SYSCTL_HANDLER_ARGS);
 static int hn_ndis_version_sysctl(SYSCTL_HANDLER_ARGS);
+static int hn_caps_sysctl(SYSCTL_HANDLER_ARGS);
 static int hn_rss_key_sysctl(SYSCTL_HANDLER_ARGS);
 static int hn_rss_ind_sysctl(SYSCTL_HANDLER_ARGS);
 static int hn_check_iplen(const struct mbuf *, int);
@@ -641,6 +642,9 @@
 	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "ndis_version",
 	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
 	    hn_ndis_version_sysctl, "A", "NDIS version");
+	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "caps",
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
+	    hn_caps_sysctl, "A", "capabilities");
 	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "rss_key",
 	    CTLTYPE_OPAQUE | CTLFLAG_RW | CTLFLAG_MPSAFE, sc, 0,
 	    hn_rss_key_sysctl, "IU", "RSS key");
@@ -2095,6 +2099,30 @@
 }
 
 static int
+hn_caps_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	struct hn_softc *sc = arg1;
+	char caps_str[128];
+	uint32_t caps;
+
+	HN_LOCK(sc);
+	caps = sc->hn_caps;
+	HN_UNLOCK(sc);
+	snprintf(caps_str, sizeof(caps_str), "%b", caps,
+	    "\020"
+	    "\001VLAN"
+	    "\002MTU"
+	    "\003IPCS"
+	    "\004TCP4CS"
+	    "\005TCP6CS"
+	    "\006UDP4CS"
+	    "\007UDP6CS"
+	    "\010TSO4"
+	    "\011TSO6");
+	return sysctl_handle_string(oidp, caps_str, sizeof(caps_str), req);
+}
+
+static int
 hn_rss_key_sysctl(SYSCTL_HANDLER_ARGS)
 {
 	struct hn_softc *sc = arg1;
@@ -3223,6 +3251,11 @@
 {
 	struct ndis_rssprm_toeplitz *rss = &sc->hn_rss;
 	int error, nsubch, nchan, i;
+	uint32_t old_caps;
+
+	/* Save capabilities for later verification. */
+	old_caps = sc->hn_caps;
+	sc->hn_caps = 0;
 
 	/*
 	 * Attach the primary channel _before_ attaching NVS and RNDIS.
@@ -3246,6 +3279,17 @@
 		return (error);
 
 	/*
+	 * Make sure capabilities are not changed.
+	 */
+	if (device_is_attached(sc->hn_dev) && old_caps != sc->hn_caps) {
+		if_printf(sc->hn_ifp, "caps mismatch old 0x%08x, new 0x%08x\n",
+		    old_caps, sc->hn_caps);
+		/* Restore old capabilities and abort. */
+		sc->hn_caps = old_caps;
+		return ENXIO;
+	}
+
+	/*
 	 * Allocate sub-channels for multi-TX/RX rings.
 	 *
 	 * NOTE:
Index: head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
+++ head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
@@ -800,6 +800,7 @@
 hn_rndis_conf_offload(struct hn_softc *sc)
 {
 	struct ndis_offload_params params;
+	uint32_t caps;
 	size_t paramsz;
 	int error;
 
@@ -816,24 +817,29 @@
 	}
 	params.ndis_hdr.ndis_size = paramsz;
 
+	caps = HN_CAP_IPCS | HN_CAP_TCP4CS | HN_CAP_TCP6CS;
 	params.ndis_ip4csum = NDIS_OFFLOAD_PARAM_TXRX;
 	params.ndis_tcp4csum = NDIS_OFFLOAD_PARAM_TXRX;
 	params.ndis_tcp6csum = NDIS_OFFLOAD_PARAM_TXRX;
 	if (sc->hn_ndis_ver >= HN_NDIS_VERSION_6_30) {
+		caps |= HN_CAP_UDP4CS | HN_CAP_UDP6CS;
 		params.ndis_udp4csum = NDIS_OFFLOAD_PARAM_TXRX;
 		params.ndis_udp6csum = NDIS_OFFLOAD_PARAM_TXRX;
 	}
+	caps |= HN_CAP_TSO4;
 	params.ndis_lsov2_ip4 = NDIS_OFFLOAD_LSOV2_ON;
 	/* XXX ndis_lsov2_ip6 = NDIS_OFFLOAD_LSOV2_ON */
 
 	error = hn_rndis_set(sc, OID_TCP_OFFLOAD_PARAMETERS, &params, paramsz);
 	if (error) {
 		if_printf(sc->hn_ifp, "offload config failed: %d\n", error);
-	} else {
-		if (bootverbose)
-			if_printf(sc->hn_ifp, "offload config done\n");
+		return (error);
 	}
-	return (error);
+
+	if (bootverbose)
+		if_printf(sc->hn_ifp, "offload config done\n");
+	sc->hn_caps |= caps;
+	return (0);
 }
 
 int