MFC r279232: Add native netmap support to ixl

Sponsored by:	Multiplay

3 files changed, 514 insertions, 0 deletions

diff --git a/sys/dev/ixl/if_ixl.c b/sys/dev/ixl/if_ixl.c
index 057b140..7c3b661 100755
--- a/sys/dev/ixl/if_ixl.c
+++ b/sys/dev/ixl/if_ixl.c
@@ -212,6 +212,9 @@ DRIVER_MODULE(ixl, pci, ixl_driver, ixl_devclass, 0, 0);
 
 MODULE_DEPEND(ixl, pci, 1, 1, 1);
 MODULE_DEPEND(ixl, ether, 1, 1, 1);
+#ifdef DEV_NETMAP
+MODULE_DEPEND(ixl, netmap, 1, 1, 1);
+#endif /* DEV_NETMAP */
 
 /*
 ** Global reset mutex
@@ -286,6 +289,10 @@ int ixl_atr_rate = 20;
 TUNABLE_INT("hw.ixl.atr_rate", &ixl_atr_rate);
 #endif
 
+#ifdef DEV_NETMAP
+#define NETMAP_IXL_MAIN /* only bring in one part of the netmap code */
+#include <dev/netmap/if_ixl_netmap.h>
+#endif /* DEV_NETMAP */
 
 static char *ixl_fc_string[6] = {
 	"None",
@@ -646,6 +653,9 @@ ixl_attach(device_t dev)
 	    ixl_unregister_vlan, vsi, EVENTHANDLER_PRI_FIRST);
 
 
+#ifdef DEV_NETMAP
+	ixl_netmap_attach(vsi);
+#endif /* DEV_NETMAP */
 	INIT_DEBUGOUT("ixl_attach: end");
 	return (0);
 
@@ -724,6 +734,9 @@ ixl_detach(device_t dev)
 		EVENTHANDLER_DEREGISTER(vlan_unconfig, vsi->vlan_detach);
 
 	callout_drain(&pf->timer);
+#ifdef DEV_NETMAP
+	netmap_detach(vsi->ifp);
+#endif /* DEV_NETMAP */
 
 
 	ixl_free_pci_resources(pf);
@@ -2661,6 +2674,15 @@ ixl_initialize_vsi(struct ixl_vsi *vsi)
 			break;
 		}
 		wr32(vsi->hw, I40E_QRX_TAIL(que->me), 0);
+#ifdef DEV_NETMAP
+		/* preserve queue */
+		if (vsi->ifp->if_capenable & IFCAP_NETMAP) {
+			struct netmap_adapter *na = NA(vsi->ifp);
+			struct netmap_kring *kring = &na->rx_rings[i];
+			int t = na->num_rx_desc - 1 - nm_kr_rxspace(kring);
+			wr32(vsi->hw, I40E_QRX_TAIL(que->me), t);
+		} else
+#endif /* DEV_NETMAP */
 		wr32(vsi->hw, I40E_QRX_TAIL(que->me), que->num_desc - 1);
 	}
 	return (err);
diff --git a/sys/dev/ixl/ixl_txrx.c b/sys/dev/ixl/ixl_txrx.c
index 3b9f593..77537f3 100755
--- a/sys/dev/ixl/ixl_txrx.c
+++ b/sys/dev/ixl/ixl_txrx.c
@@ -61,6 +61,10 @@ static __inline void ixl_rx_discard(struct rx_ring *, int);
 static __inline void ixl_rx_input(struct rx_ring *, struct ifnet *,
 		    struct mbuf *, u8);
 
+#ifdef DEV_NETMAP
+#include <dev/netmap/if_ixl_netmap.h>
+#endif /* DEV_NETMAP */
+
 /*
 ** Multiqueue Transmit driver
 **
@@ -485,9 +489,21 @@ ixl_init_tx_ring(struct ixl_queue *que)
 {
 	struct tx_ring *txr = &que->txr;
 	struct ixl_tx_buf *buf;
+#ifdef DEV_NETMAP
+	struct netmap_adapter *na = NA(que->vsi->ifp);
+	struct netmap_slot *slot;
+#endif /* DEV_NETMAP */
 
 	/* Clear the old ring contents */
 	IXL_TX_LOCK(txr);
+#ifdef DEV_NETMAP
+	/*
+	 * (under lock): if in netmap mode, do some consistency
+	 * checks and set slot to entry 0 of the netmap ring.
+	 */
+	slot = netmap_reset(na, NR_TX, que->me, 0);
+#endif /* DEV_NETMAP */
+
 	bzero((void *)txr->base,
 	      (sizeof(struct i40e_tx_desc)) * que->num_desc);
 
@@ -511,6 +527,19 @@ ixl_init_tx_ring(struct ixl_queue *que)
 			m_freem(buf->m_head);
 			buf->m_head = NULL;
 		}
+#ifdef DEV_NETMAP
+		/*
+		 * In netmap mode, set the map for the packet buffer.
+		 * NOTE: Some drivers (not this one) also need to set
+		 * the physical buffer address in the NIC ring.
+		 * netmap_idx_n2k() maps a nic index, i, into the corresponding
+		 * netmap slot index, si
+		 */
+		if (slot) {
+			int si = netmap_idx_n2k(&na->tx_rings[que->me], i);
+			netmap_load_map(na, buf->tag, buf->map, NMB(na, slot + si));
+		}
+#endif /* DEV_NETMAP */
 		/* Clear the EOP index */
 		buf->eop_index = -1;
         }
@@ -822,6 +851,11 @@ ixl_txeof(struct ixl_queue *que)
 
 	mtx_assert(&txr->mtx, MA_OWNED);
 
+#ifdef DEV_NETMAP
+	// XXX todo: implement moderation
+	if (netmap_tx_irq(que->vsi->ifp, que->me))
+		return FALSE;
+#endif /* DEF_NETMAP */
 
 	/* These are not the descriptors you seek, move along :) */
 	if (txr->avail == que->num_desc) {
@@ -1123,8 +1157,16 @@ ixl_init_rx_ring(struct ixl_queue *que)
 	struct ixl_rx_buf	*buf;
 	bus_dma_segment_t	pseg[1], hseg[1];
 	int			rsize, nsegs, error = 0;
+#ifdef DEV_NETMAP 
+	struct netmap_adapter *na = NA(que->vsi->ifp);
+	struct netmap_slot *slot;
+#endif /* DEV_NETMAP */
 
 	IXL_RX_LOCK(rxr);
+#ifdef DEV_NETMAP
+	/* same as in ixl_init_tx_ring() */
+	slot = netmap_reset(na, NR_RX, que->me, 0);
+#endif /* DEV_NETMAP */
 	/* Clear the ring contents */
 	rsize = roundup2(que->num_desc *
 	    sizeof(union i40e_rx_desc), DBA_ALIGN);
@@ -1158,6 +1200,28 @@ ixl_init_rx_ring(struct ixl_queue *que)
 		struct mbuf	*mh, *mp;
 
 		buf = &rxr->buffers[j];
+#ifdef DEV_NETMAP
+		/*
+		 * In netmap mode, fill the map and set the buffer
+		 * address in the NIC ring, considering the offset
+		 * between the netmap and NIC rings (see comment in
+		 * ixgbe_setup_transmit_ring() ). No need to allocate
+		 * an mbuf, so end the block with a continue;
+		 */
+		if (slot) {
+			int sj = netmap_idx_n2k(&na->rx_rings[que->me], j);
+			uint64_t paddr;
+			void *addr;
+
+			addr = PNMB(na, slot + sj, &paddr);
+			netmap_load_map(na, rxr->dma.tag, buf->pmap, addr);
+			/* Update descriptor and the cached value */
+			rxr->base[j].read.pkt_addr = htole64(paddr);
+			rxr->base[j].read.hdr_addr = 0;
+			continue;
+		}
+#endif /* DEV_NETMAP */
+
 		/*
 		** Don't allocate mbufs if not
 		** doing header split, its wasteful
@@ -1457,6 +1521,12 @@ ixl_rxeof(struct ixl_queue *que, int count)
 
 	IXL_RX_LOCK(rxr);
 
+#ifdef DEV_NETMAP
+	if (netmap_rx_irq(ifp, que->me, &count)) {
+		IXL_RX_UNLOCK(rxr);
+		return (FALSE);
+	}
+#endif /* DEV_NETMAP */
 
 	for (i = rxr->next_check; count != 0;) {
 		struct mbuf	*sendmp, *mh, *mp;
diff --git a/sys/dev/netmap/if_ixl_netmap.h b/sys/dev/netmap/if_ixl_netmap.h
new file mode 100644
index 0000000..d6aff1f
--- /dev/null
+++ b/sys/dev/netmap/if_ixl_netmap.h
@@ -0,0 +1,422 @@
+/*
+ * Copyright (C) 2015, Luigi Rizzo. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * $FreeBSD$
+ *
+ * netmap support for: ixl
+ *
+ * derived from ixgbe
+ * netmap support for a network driver.
+ * This file contains code but only static or inline functions used
+ * by a single driver. To avoid replication of code we just #include
+ * it near the beginning of the standard driver.
+ * For ixl the file is imported in two places, hence the conditional at the
+ * beginning.
+ */
+
+#include <net/netmap.h>
+#include <sys/selinfo.h>
+
+/*
+ * Some drivers may need the following headers. Others
+ * already include them by default
+
+#include <vm/vm.h>
+#include <vm/pmap.h>
+
+ */
+#include <dev/netmap/netmap_kern.h>
+
+int ixl_netmap_txsync(struct netmap_kring *kring, int flags);
+int ixl_netmap_rxsync(struct netmap_kring *kring, int flags);
+
+extern int ixl_rx_miss, ixl_rx_miss_bufs, ixl_crcstrip;
+
+#ifdef NETMAP_IXL_MAIN
+/*
+ * device-specific sysctl variables:
+ *
+ * ixl_crcstrip: 0: keep CRC in rx frames (default), 1: strip it.
+ *	During regular operations the CRC is stripped, but on some
+ *	hardware reception of frames not multiple of 64 is slower,
+ *	so using crcstrip=0 helps in benchmarks.
+ *
+ * ixl_rx_miss, ixl_rx_miss_bufs:
+ *	count packets that might be missed due to lost interrupts.
+ */
+SYSCTL_DECL(_dev_netmap);
+int ixl_rx_miss, ixl_rx_miss_bufs, ixl_crcstrip;
+SYSCTL_INT(_dev_netmap, OID_AUTO, ixl_crcstrip,
+    CTLFLAG_RW, &ixl_crcstrip, 0, "strip CRC on rx frames");
+SYSCTL_INT(_dev_netmap, OID_AUTO, ixl_rx_miss,
+    CTLFLAG_RW, &ixl_rx_miss, 0, "potentially missed rx intr");
+SYSCTL_INT(_dev_netmap, OID_AUTO, ixl_rx_miss_bufs,
+    CTLFLAG_RW, &ixl_rx_miss_bufs, 0, "potentially missed rx intr bufs");
+
+
+/*
+ * Register/unregister. We are already under netmap lock.
+ * Only called on the first register or the last unregister.
+ */
+static int
+ixl_netmap_reg(struct netmap_adapter *na, int onoff)
+{
+	struct ifnet *ifp = na->ifp;
+        struct ixl_vsi  *vsi = ifp->if_softc;
+        struct ixl_pf   *pf = (struct ixl_pf *)vsi->back;
+
+	IXL_PF_LOCK(pf);
+	ixl_disable_intr(vsi);
+
+	/* Tell the stack that the interface is no longer active */
+	ifp->if_drv_flags &= ~(IFF_DRV_RUNNING | IFF_DRV_OACTIVE);
+
+	//set_crcstrip(&adapter->hw, onoff);
+	/* enable or disable flags and callbacks in na and ifp */
+	if (onoff) {
+		nm_set_native_flags(na);
+	} else {
+		nm_clear_native_flags(na);
+	}
+	ixl_init_locked(pf);	/* also enables intr */
+	//set_crcstrip(&adapter->hw, onoff); // XXX why twice ?
+	IXL_PF_UNLOCK(pf);
+	return (ifp->if_drv_flags & IFF_DRV_RUNNING ? 0 : 1);
+}
+
+
+/*
+ * The attach routine, called near the end of ixl_attach(),
+ * fills the parameters for netmap_attach() and calls it.
+ * It cannot fail, in the worst case (such as no memory)
+ * netmap mode will be disabled and the driver will only
+ * operate in standard mode.
+ */
+static void
+ixl_netmap_attach(struct ixl_vsi *vsi)
+{
+	struct netmap_adapter na;
+
+	bzero(&na, sizeof(na));
+
+	na.ifp = vsi->ifp;
+	na.na_flags = NAF_BDG_MAYSLEEP;
+	// XXX check that queues is set.
+	printf("queues is %p\n", vsi->queues);
+	if (vsi->queues) {
+		na.num_tx_desc = vsi->queues[0].num_desc;
+		na.num_rx_desc = vsi->queues[0].num_desc;
+	}
+	na.nm_txsync = ixl_netmap_txsync;
+	na.nm_rxsync = ixl_netmap_rxsync;
+	na.nm_register = ixl_netmap_reg;
+	na.num_tx_rings = na.num_rx_rings = vsi->num_queues;
+	netmap_attach(&na);
+}
+
+
+#else /* !NETMAP_IXL_MAIN, code for ixl_txrx.c */
+
+/*
+ * Reconcile kernel and user view of the transmit ring.
+ *
+ * All information is in the kring.
+ * Userspace wants to send packets up to the one before kring->rhead,
+ * kernel knows kring->nr_hwcur is the first unsent packet.
+ *
+ * Here we push packets out (as many as possible), and possibly
+ * reclaim buffers from previously completed transmission.
+ *
+ * The caller (netmap) guarantees that there is only one instance
+ * running at any time. Any interference with other driver
+ * methods should be handled by the individual drivers.
+ */
+int
+ixl_netmap_txsync(struct netmap_kring *kring, int flags)
+{
+	struct netmap_adapter *na = kring->na;
+	struct ifnet *ifp = na->ifp;
+	struct netmap_ring *ring = kring->ring;
+	u_int nm_i;	/* index into the netmap ring */
+	u_int nic_i;	/* index into the NIC ring */
+	u_int n;
+	u_int const lim = kring->nkr_num_slots - 1;
+	u_int const head = kring->rhead;
+	/*
+	 * interrupts on every tx packet are expensive so request
+	 * them every half ring, or where NS_REPORT is set
+	 */
+	u_int report_frequency = kring->nkr_num_slots >> 1;
+
+	/* device-specific */
+	struct ixl_vsi *vsi = ifp->if_softc;
+	struct ixl_queue *que = &vsi->queues[kring->ring_id];
+	struct tx_ring *txr = &que->txr;
+
+	bus_dmamap_sync(txr->dma.tag, txr->dma.map,
+			BUS_DMASYNC_POSTREAD);
+
+	/*
+	 * First part: process new packets to send.
+	 * nm_i is the current index in the netmap ring,
+	 * nic_i is the corresponding index in the NIC ring.
+	 *
+	 * If we have packets to send (nm_i != head)
+	 * iterate over the netmap ring, fetch length and update
+	 * the corresponding slot in the NIC ring. Some drivers also
+	 * need to update the buffer's physical address in the NIC slot
+	 * even NS_BUF_CHANGED is not set (PNMB computes the addresses).
+	 *
+	 * The netmap_reload_map() calls is especially expensive,
+	 * even when (as in this case) the tag is 0, so do only
+	 * when the buffer has actually changed.
+	 *
+	 * If possible do not set the report/intr bit on all slots,
+	 * but only a few times per ring or when NS_REPORT is set.
+	 *
+	 * Finally, on 10G and faster drivers, it might be useful
+	 * to prefetch the next slot and txr entry.
+	 */
+
+	nm_i = kring->nr_hwcur;
+	if (nm_i != head) {	/* we have new packets to send */
+		nic_i = netmap_idx_k2n(kring, nm_i);
+
+		__builtin_prefetch(&ring->slot[nm_i]);
+		__builtin_prefetch(&txr->buffers[nic_i]);
+
+		for (n = 0; nm_i != head; n++) {
+			struct netmap_slot *slot = &ring->slot[nm_i];
+			u_int len = slot->len;
+			uint64_t paddr;
+			void *addr = PNMB(na, slot, &paddr);
+
+			/* device-specific */
+			struct i40e_tx_desc *curr = &txr->base[nic_i];
+			struct ixl_tx_buf *txbuf = &txr->buffers[nic_i];
+			u64 flags = (slot->flags & NS_REPORT ||
+				nic_i == 0 || nic_i == report_frequency) ?
+				((u64)I40E_TX_DESC_CMD_RS << I40E_TXD_QW1_CMD_SHIFT) : 0;
+
+			/* prefetch for next round */
+			__builtin_prefetch(&ring->slot[nm_i + 1]);
+			__builtin_prefetch(&txr->buffers[nic_i + 1]);
+
+			NM_CHECK_ADDR_LEN(na, addr, len);
+
+			if (slot->flags & NS_BUF_CHANGED) {
+				/* buffer has changed, reload map */
+				netmap_reload_map(na, txr->dma.tag, txbuf->map, addr);
+			}
+			slot->flags &= ~(NS_REPORT | NS_BUF_CHANGED);
+
+			/* Fill the slot in the NIC ring. */
+			curr->buffer_addr = htole64(paddr);
+			curr->cmd_type_offset_bsz = htole64(
+			    ((u64)len << I40E_TXD_QW1_TX_BUF_SZ_SHIFT) |
+			    flags |
+			    ((u64)I40E_TX_DESC_CMD_EOP << I40E_TXD_QW1_CMD_SHIFT)
+			  ); // XXX more ?
+
+			/* make sure changes to the buffer are synced */
+			bus_dmamap_sync(txr->dma.tag, txbuf->map,
+				BUS_DMASYNC_PREWRITE);
+
+			nm_i = nm_next(nm_i, lim);
+			nic_i = nm_next(nic_i, lim);
+		}
+		kring->nr_hwcur = head;
+
+		/* synchronize the NIC ring */
+		bus_dmamap_sync(txr->dma.tag, txr->dma.map,
+			BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
+
+		/* (re)start the tx unit up to slot nic_i (excluded) */
+		wr32(vsi->hw, txr->tail, nic_i);
+	}
+
+	/*
+	 * Second part: reclaim buffers for completed transmissions.
+	 */
+	nic_i = LE32_TO_CPU(*(volatile __le32 *)&txr->base[que->num_desc]);
+	if (nic_i != txr->next_to_clean) {
+		/* some tx completed, increment avail */
+		txr->next_to_clean = nic_i;
+		kring->nr_hwtail = nm_prev(netmap_idx_n2k(kring, nic_i), lim);
+	}
+
+	nm_txsync_finalize(kring);
+
+	return 0;
+}
+
+
+/*
+ * Reconcile kernel and user view of the receive ring.
+ * Same as for the txsync, this routine must be efficient.
+ * The caller guarantees a single invocations, but races against
+ * the rest of the driver should be handled here.
+ *
+ * On call, kring->rhead is the first packet that userspace wants
+ * to keep, and kring->rcur is the wakeup point.
+ * The kernel has previously reported packets up to kring->rtail.
+ *
+ * If (flags & NAF_FORCE_READ) also check for incoming packets irrespective
+ * of whether or not we received an interrupt.
+ */
+int
+ixl_netmap_rxsync(struct netmap_kring *kring, int flags)
+{
+	struct netmap_adapter *na = kring->na;
+	struct ifnet *ifp = na->ifp;
+	struct netmap_ring *ring = kring->ring;
+	u_int nm_i;	/* index into the netmap ring */
+	u_int nic_i;	/* index into the NIC ring */
+	u_int n;
+	u_int const lim = kring->nkr_num_slots - 1;
+	u_int const head = nm_rxsync_prologue(kring);
+	int force_update = (flags & NAF_FORCE_READ) || kring->nr_kflags & NKR_PENDINTR;
+
+	/* device-specific */
+	struct ixl_vsi *vsi = ifp->if_softc;
+	struct ixl_queue *que = &vsi->queues[kring->ring_id];
+	struct rx_ring *rxr = &que->rxr;
+
+	if (head > lim)
+		return netmap_ring_reinit(kring);
+
+	/* XXX check sync modes */
+	bus_dmamap_sync(rxr->dma.tag, rxr->dma.map,
+			BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE);
+
+	/*
+	 * First part: import newly received packets.
+	 *
+	 * nm_i is the index of the next free slot in the netmap ring,
+	 * nic_i is the index of the next received packet in the NIC ring,
+	 * and they may differ in case if_init() has been called while
+	 * in netmap mode. For the receive ring we have
+	 *
+	 *	nic_i = rxr->next_check;
+	 *	nm_i = kring->nr_hwtail (previous)
+	 * and
+	 *	nm_i == (nic_i + kring->nkr_hwofs) % ring_size
+	 *
+	 * rxr->next_check is set to 0 on a ring reinit
+	 */
+	if (netmap_no_pendintr || force_update) {
+		int crclen = ixl_crcstrip ? 0 : 4;
+		uint16_t slot_flags = kring->nkr_slot_flags;
+
+		nic_i = rxr->next_check; // or also k2n(kring->nr_hwtail)
+		nm_i = netmap_idx_n2k(kring, nic_i);
+
+		for (n = 0; ; n++) {
+			union i40e_32byte_rx_desc *curr = &rxr->base[nic_i];
+			uint64_t qword = le64toh(curr->wb.qword1.status_error_len);
+			uint32_t staterr = (qword & I40E_RXD_QW1_STATUS_MASK)
+				 >> I40E_RXD_QW1_STATUS_SHIFT;
+
+			if ((staterr & (1<<I40E_RX_DESC_STATUS_DD_SHIFT)) == 0)
+				break;
+			ring->slot[nm_i].len = ((qword & I40E_RXD_QW1_LENGTH_PBUF_MASK)
+			    >> I40E_RXD_QW1_LENGTH_PBUF_SHIFT) - crclen;
+			ring->slot[nm_i].flags = slot_flags;
+			bus_dmamap_sync(rxr->ptag,
+			    rxr->buffers[nic_i].pmap, BUS_DMASYNC_POSTREAD);
+			nm_i = nm_next(nm_i, lim);
+			nic_i = nm_next(nic_i, lim);
+		}
+		if (n) { /* update the state variables */
+			if (netmap_no_pendintr && !force_update) {
+				/* diagnostics */
+				ixl_rx_miss ++;
+				ixl_rx_miss_bufs += n;
+			}
+			rxr->next_check = nic_i;
+			kring->nr_hwtail = nm_i;
+		}
+		kring->nr_kflags &= ~NKR_PENDINTR;
+	}
+
+	/*
+	 * Second part: skip past packets that userspace has released.
+	 * (kring->nr_hwcur to head excluded),
+	 * and make the buffers available for reception.
+	 * As usual nm_i is the index in the netmap ring,
+	 * nic_i is the index in the NIC ring, and
+	 * nm_i == (nic_i + kring->nkr_hwofs) % ring_size
+	 */
+	nm_i = kring->nr_hwcur;
+	if (nm_i != head) {
+		nic_i = netmap_idx_k2n(kring, nm_i);
+		for (n = 0; nm_i != head; n++) {
+			struct netmap_slot *slot = &ring->slot[nm_i];
+			uint64_t paddr;
+			void *addr = PNMB(na, slot, &paddr);
+
+			union i40e_32byte_rx_desc *curr = &rxr->base[nic_i];
+			struct ixl_rx_buf *rxbuf = &rxr->buffers[nic_i];
+
+			if (addr == NETMAP_BUF_BASE(na)) /* bad buf */
+				goto ring_reset;
+
+			if (slot->flags & NS_BUF_CHANGED) {
+				/* buffer has changed, reload map */
+				netmap_reload_map(na, rxr->ptag, rxbuf->pmap, addr);
+				slot->flags &= ~NS_BUF_CHANGED;
+			}
+			curr->read.pkt_addr = htole64(paddr);
+			curr->read.hdr_addr = 0; // XXX needed
+			bus_dmamap_sync(rxr->ptag, rxbuf->pmap,
+			    BUS_DMASYNC_PREREAD);
+			nm_i = nm_next(nm_i, lim);
+			nic_i = nm_next(nic_i, lim);
+		}
+		kring->nr_hwcur = head;
+
+		bus_dmamap_sync(rxr->dma.tag, rxr->dma.map,
+		    BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE);
+		/*
+		 * IMPORTANT: we must leave one free slot in the ring,
+		 * so move nic_i back by one unit
+		 */
+		nic_i = nm_prev(nic_i, lim);
+		wr32(vsi->hw, rxr->tail, nic_i);
+	}
+
+	/* tell userspace that there might be new packets */
+	nm_rxsync_finalize(kring);
+
+	return 0;
+
+ring_reset:
+	return netmap_ring_reinit(kring);
+}
+
+#endif /* !NETMAP_IXL_MAIN */
+
+/* end of file */