--- sys/dev/virtio/network/if_vtnetvar.h.ori	2020-01-08 19:57:18.670256000 -0800
+++ sys/dev/virtio/network/if_vtnetvar.h	2020-01-08 19:58:47.614309220 -0800
@@ -82,6 +82,9 @@
 	struct taskqueue	*vtnrx_tq;
 	struct task		 vtnrx_intrtask;
 	struct lro_ctrl		 vtnrx_lro;
+#ifdef DEV_NETMAP
+	struct virtio_net_hdr_mrg_rxbuf vtnrx_shrhdr;
+#endif  /* DEV_NETMAP */
 	char			 vtnrx_name[16];
 } __aligned(CACHE_LINE_SIZE);
 
@@ -118,6 +121,9 @@
 #ifndef VTNET_LEGACY_TX
 	struct task		 vtntx_defrtask;
 #endif
+#ifdef DEV_NETMAP
+	struct virtio_net_hdr_mrg_rxbuf vtntx_shrhdr;
+#endif  /* DEV_NETMAP */
 	char			 vtntx_name[16];
 } __aligned(CACHE_LINE_SIZE);
 
--- sys/dev/netmap/if_vtnet_netmap.h.ori	2020-01-08 20:41:23.318408000 -0800
+++ sys/dev/netmap/if_vtnet_netmap.h	2020-01-08 21:04:04.407345486 -0800
@@ -346,6 +346,52 @@
 	return error < 0 ? ENXIO : 0;
 }
 
+static int
+vtnet_refill_rxq(struct netmap_kring *kring, u_int nm_i, u_int head)
+{
+	struct netmap_adapter *na = kring->na;
+        struct ifnet *ifp = na->ifp;
+	struct netmap_ring *ring = kring->ring;
+	u_int ring_nr = kring->ring_id;
+	u_int const lim = kring->nkr_num_slots - 1;
+	u_int n;
+
+	/* device-specific */
+	struct vtnet_softc *sc = ifp->if_softc;
+	struct vtnet_rxq *rxq = &sc->vtnet_rxqs[ring_nr];
+	struct virtqueue *vq = rxq->vtnrx_vq;
+
+	/* use a local sglist, default might be short */
+	struct sglist_seg ss[2];
+	struct sglist sg = { ss, 0, 0, 2 };
+
+	for (n = 0; nm_i != head; n++) {
+		static struct virtio_net_hdr_mrg_rxbuf hdr;
+		struct netmap_slot *slot = &ring->slot[nm_i];
+		uint64_t paddr;
+		void *addr = PNMB(na, slot, &paddr);
+		int err = 0;
+
+		if (addr == NETMAP_BUF_BASE(na)) { /* bad buf */
+			if (netmap_ring_reinit(kring))
+				return -1;
+		}
+
+		slot->flags &= ~NS_BUF_CHANGED;
+		sglist_reset(&sg); // cheap
+		err = sglist_append(&sg, &hdr, sc->vtnet_hdr_size);
+		err = sglist_append_phys(&sg, paddr, NETMAP_BUF_SIZE(na));
+		/* writable for the host */
+		err = virtqueue_enqueue(vq, rxq, &sg, 0, sg.sg_nseg);
+		if (err < 0) {
+			D("virtqueue_enqueue failed");
+			break;
+		}
+		nm_i = nm_next(nm_i, lim);
+	}
+	return nm_i;
+}
+
 /* Reconcile kernel and user view of the receive ring. */
 static int
 vtnet_netmap_rxsync(struct netmap_kring *kring, int flags)
@@ -510,6 +556,41 @@
 	info->rx_buf_maxsize = NETMAP_BUF_SIZE(na);
 
 	return 0;
+}
+
+/* Make RX virtqueues buffers pointing to netmap buffers. */
+static int
+vtnet_netmap_init_rx_buffers(struct vtnet_softc *sc)
+{
+	struct ifnet *ifp = sc->vtnet_ifp;
+	struct netmap_adapter* na = NA(ifp);
+	unsigned int r;
+
+	if (!nm_native_on(na))
+		return 0;
+	for (r = 0; r < na->num_rx_rings; r++) {
+                struct netmap_kring *kring = na->rx_rings[r];
+		struct vtnet_rxq *rxq = &sc->vtnet_rxqs[r];
+		struct virtqueue *vq = rxq->vtnrx_vq;
+	        struct netmap_slot* slot;
+		int err = 0;
+
+		slot = netmap_reset(na, NR_RX, r, 0);
+		if (!slot) {
+			D("strange, null netmap ring %d", r);
+			return 0;
+		}
+		/* Add up to na>-num_rx_desc-1 buffers to this RX virtqueue.
+		 * It's important to leave one virtqueue slot free, otherwise
+		 * we can run into ring->cur/ring->tail wraparounds.
+		 */
+		err = vtnet_refill_rxq(kring, 0, na->num_rx_desc-1);
+		if (err < 0)
+			return 0;
+		virtqueue_notify(vq);
+	}
+
+	return 1;
 }
 
 static void