net/vhost: support queue update
[dpdk.git] / drivers / net / vhost / rte_eth_vhost.c
index 55e51c8..bbf79b2 100644 (file)
@@ -18,7 +18,7 @@
 
 #include "rte_eth_vhost.h"
 
-static int vhost_logtype;
+RTE_LOG_REGISTER(vhost_logtype, pmd.net.vhost, NOTICE);
 
 #define VHOST_LOG(level, ...) \
        rte_log(RTE_LOG_ ## level, vhost_logtype, __VA_ARGS__)
@@ -31,6 +31,9 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
 #define ETH_VHOST_DEQUEUE_ZERO_COPY    "dequeue-zero-copy"
 #define ETH_VHOST_IOMMU_SUPPORT                "iommu-support"
 #define ETH_VHOST_POSTCOPY_SUPPORT     "postcopy-support"
+#define ETH_VHOST_VIRTIO_NET_F_HOST_TSO "tso"
+#define ETH_VHOST_LINEAR_BUF  "linear-buffer"
+#define ETH_VHOST_EXT_BUF  "ext-buffer"
 #define VHOST_MAX_PKT_BURST 32
 
 static const char *valid_arguments[] = {
@@ -40,10 +43,13 @@ static const char *valid_arguments[] = {
        ETH_VHOST_DEQUEUE_ZERO_COPY,
        ETH_VHOST_IOMMU_SUPPORT,
        ETH_VHOST_POSTCOPY_SUPPORT,
+       ETH_VHOST_VIRTIO_NET_F_HOST_TSO,
+       ETH_VHOST_LINEAR_BUF,
+       ETH_VHOST_EXT_BUF,
        NULL
 };
 
-static struct ether_addr base_eth_addr = {
+static struct rte_ether_addr base_eth_addr = {
        .addr_bytes = {
                0x56 /* V */,
                0x48 /* H */,
@@ -88,13 +94,15 @@ struct vhost_queue {
        struct rte_mempool *mb_pool;
        uint16_t port;
        uint16_t virtqueue_id;
+       bool intr_en;
        struct vhost_stats stats;
 };
 
 struct pmd_internal {
        rte_atomic32_t dev_attached;
-       char *dev_name;
        char *iface_name;
+       uint64_t flags;
+       uint64_t disable_flags;
        uint16_t max_queues;
        int vid;
        rte_atomic32_t started;
@@ -216,7 +224,7 @@ static const struct vhost_xstats_name_off vhost_txport_stat_strings[] = {
 #define VHOST_NB_XSTATS_TXPORT (sizeof(vhost_txport_stat_strings) / \
                                sizeof(vhost_txport_stat_strings[0]))
 
-static void
+static int
 vhost_dev_xstats_reset(struct rte_eth_dev *dev)
 {
        struct vhost_queue *vq = NULL;
@@ -234,6 +242,8 @@ vhost_dev_xstats_reset(struct rte_eth_dev *dev)
                        continue;
                memset(&vq->stats, 0, sizeof(vq->stats));
        }
+
+       return 0;
 }
 
 static int
@@ -325,12 +335,12 @@ static inline void
 vhost_count_multicast_broadcast(struct vhost_queue *vq,
                                struct rte_mbuf *mbuf)
 {
-       struct ether_addr *ea = NULL;
+       struct rte_ether_addr *ea = NULL;
        struct vhost_stats *pstats = &vq->stats;
 
-       ea = rte_pktmbuf_mtod(mbuf, struct ether_addr *);
-       if (is_multicast_ether_addr(ea)) {
-               if (is_broadcast_ether_addr(ea))
+       ea = rte_pktmbuf_mtod(mbuf, struct rte_ether_addr *);
+       if (rte_is_multicast_ether_addr(ea)) {
+               if (rte_is_broadcast_ether_addr(ea))
                        pstats->xstats[VHOST_BROADCAST_PKT]++;
                else
                        pstats->xstats[VHOST_MULTICAST_PKT]++;
@@ -487,17 +497,6 @@ out:
        return nb_tx;
 }
 
-static int
-eth_dev_configure(struct rte_eth_dev *dev __rte_unused)
-{
-       struct pmd_internal *internal = dev->data->dev_private;
-       const struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
-
-       internal->vlan_strip = !!(rxmode->offloads & DEV_RX_OFFLOAD_VLAN_STRIP);
-
-       return 0;
-}
-
 static inline struct internal_list *
 find_internal_resource(char *ifname)
 {
@@ -548,6 +547,8 @@ eth_rxq_intr_enable(struct rte_eth_dev *dev, uint16_t qid)
        rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 1);
        rte_wmb();
 
+       vq->intr_en = true;
+
        return ret;
 }
 
@@ -573,6 +574,8 @@ eth_rxq_intr_disable(struct rte_eth_dev *dev, uint16_t qid)
        rte_vhost_enable_guest_notification(vq->vid, (qid << 1) + 1, 0);
        rte_wmb();
 
+       vq->intr_en = false;
+
        return 0;
 }
 
@@ -832,6 +835,45 @@ destroy_device(int vid)
        _rte_eth_dev_callback_process(eth_dev, RTE_ETH_EVENT_INTR_LSC, NULL);
 }
 
+static int
+vring_conf_update(int vid, struct rte_eth_dev *eth_dev, uint16_t vring_id)
+{
+       struct rte_eth_conf *dev_conf = &eth_dev->data->dev_conf;
+       struct pmd_internal *internal = eth_dev->data->dev_private;
+       struct rte_vhost_vring vring;
+       struct vhost_queue *vq;
+       int rx_idx = vring_id % 2 ? (vring_id - 1) >> 1 : -1;
+       int ret = 0;
+
+       /*
+        * The vring kickfd may be changed after the new device notification.
+        * Update it when the vring state is updated.
+        */
+       if (rx_idx >= 0 && rx_idx < eth_dev->data->nb_rx_queues &&
+           rte_atomic32_read(&internal->dev_attached) &&
+           rte_atomic32_read(&internal->started) &&
+           dev_conf->intr_conf.rxq) {
+               vq = eth_dev->data->rx_queues[rx_idx];
+               ret = rte_vhost_get_vhost_vring(vid, vring_id, &vring);
+               if (!ret) {
+                       if (vring.kickfd !=
+                           eth_dev->intr_handle->efds[rx_idx]) {
+                               VHOST_LOG(INFO,
+                                         "kickfd for rxq-%d was changed.\n",
+                                         rx_idx);
+                               eth_dev->intr_handle->efds[rx_idx] =
+                                                                  vring.kickfd;
+                       }
+
+                       rte_vhost_enable_guest_notification(vid, vring_id,
+                                                           vq->intr_en);
+                       rte_wmb();
+               }
+       }
+
+       return ret;
+}
+
 static int
 vring_state_changed(int vid, uint16_t vring, int enable)
 {
@@ -850,7 +892,16 @@ vring_state_changed(int vid, uint16_t vring, int enable)
        eth_dev = list->eth_dev;
        /* won't be NULL */
        state = vring_states[eth_dev->data->port_id];
+
+       if (enable && vring_conf_update(vid, eth_dev, vring))
+               VHOST_LOG(INFO, "Failed to update vring-%d configuration.\n",
+                         (int)vring);
+
        rte_spinlock_lock(&state->lock);
+       if (state->cur[vring] == enable) {
+               rte_spinlock_unlock(&state->lock);
+               return 0;
+       }
        state->cur[vring] = enable;
        state->max_vring = RTE_MAX(vring, state->max_vring);
        rte_spinlock_unlock(&state->lock);
@@ -869,6 +920,74 @@ static struct vhost_device_ops vhost_ops = {
        .vring_state_changed = vring_state_changed,
 };
 
+static int
+vhost_driver_setup(struct rte_eth_dev *eth_dev)
+{
+       struct pmd_internal *internal = eth_dev->data->dev_private;
+       struct internal_list *list = NULL;
+       struct rte_vhost_vring_state *vring_state = NULL;
+       unsigned int numa_node = eth_dev->device->numa_node;
+       const char *name = eth_dev->device->name;
+
+       /* Don't try to setup again if it has already been done. */
+       list = find_internal_resource(internal->iface_name);
+       if (list)
+               return 0;
+
+       list = rte_zmalloc_socket(name, sizeof(*list), 0, numa_node);
+       if (list == NULL)
+               return -1;
+
+       vring_state = rte_zmalloc_socket(name, sizeof(*vring_state),
+                                        0, numa_node);
+       if (vring_state == NULL)
+               goto free_list;
+
+       list->eth_dev = eth_dev;
+       pthread_mutex_lock(&internal_list_lock);
+       TAILQ_INSERT_TAIL(&internal_list, list, next);
+       pthread_mutex_unlock(&internal_list_lock);
+
+       rte_spinlock_init(&vring_state->lock);
+       vring_states[eth_dev->data->port_id] = vring_state;
+
+       if (rte_vhost_driver_register(internal->iface_name, internal->flags))
+               goto list_remove;
+
+       if (internal->disable_flags) {
+               if (rte_vhost_driver_disable_features(internal->iface_name,
+                                                     internal->disable_flags))
+                       goto drv_unreg;
+       }
+
+       if (rte_vhost_driver_callback_register(internal->iface_name,
+                                              &vhost_ops) < 0) {
+               VHOST_LOG(ERR, "Can't register callbacks\n");
+               goto drv_unreg;
+       }
+
+       if (rte_vhost_driver_start(internal->iface_name) < 0) {
+               VHOST_LOG(ERR, "Failed to start driver for %s\n",
+                         internal->iface_name);
+               goto drv_unreg;
+       }
+
+       return 0;
+
+drv_unreg:
+       rte_vhost_driver_unregister(internal->iface_name);
+list_remove:
+       vring_states[eth_dev->data->port_id] = NULL;
+       pthread_mutex_lock(&internal_list_lock);
+       TAILQ_REMOVE(&internal_list, list, next);
+       pthread_mutex_unlock(&internal_list_lock);
+       rte_free(vring_state);
+free_list:
+       rte_free(list);
+
+       return -1;
+}
+
 int
 rte_eth_vhost_get_queue_event(uint16_t port_id,
                struct rte_eth_vhost_queue_event *event)
@@ -935,6 +1054,24 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t port_id)
        return vid;
 }
 
+static int
+eth_dev_configure(struct rte_eth_dev *dev)
+{
+       struct pmd_internal *internal = dev->data->dev_private;
+       const struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
+
+       /* NOTE: the same process has to operate a vhost interface
+        * from beginning to end (from eth_dev configure to eth_dev close).
+        * It is user's responsibility at the moment.
+        */
+       if (vhost_driver_setup(dev) < 0)
+               return -1;
+
+       internal->vlan_strip = !!(rxmode->offloads & DEV_RX_OFFLOAD_VLAN_STRIP);
+
+       return 0;
+}
+
 static int
 eth_dev_start(struct rte_eth_dev *eth_dev)
 {
@@ -981,16 +1118,14 @@ eth_dev_close(struct rte_eth_dev *dev)
 
        eth_dev_stop(dev);
 
-       rte_vhost_driver_unregister(internal->iface_name);
-
        list = find_internal_resource(internal->iface_name);
-       if (!list)
-               return;
-
-       pthread_mutex_lock(&internal_list_lock);
-       TAILQ_REMOVE(&internal_list, list, next);
-       pthread_mutex_unlock(&internal_list_lock);
-       rte_free(list);
+       if (list) {
+               rte_vhost_driver_unregister(internal->iface_name);
+               pthread_mutex_lock(&internal_list_lock);
+               TAILQ_REMOVE(&internal_list, list, next);
+               pthread_mutex_unlock(&internal_list_lock);
+               rte_free(list);
+       }
 
        if (dev->data->rx_queues)
                for (i = 0; i < dev->data->nb_rx_queues; i++)
@@ -1000,12 +1135,13 @@ eth_dev_close(struct rte_eth_dev *dev)
                for (i = 0; i < dev->data->nb_tx_queues; i++)
                        rte_free(dev->data->tx_queues[i]);
 
-       rte_free(dev->data->mac_addrs);
-       free(internal->dev_name);
-       free(internal->iface_name);
+       rte_free(internal->iface_name);
        rte_free(internal);
 
        dev->data->dev_private = NULL;
+
+       rte_free(vring_states[dev->data->port_id]);
+       vring_states[dev->data->port_id] = NULL;
 }
 
 static int
@@ -1052,7 +1188,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
        return 0;
 }
 
-static void
+static int
 eth_dev_info(struct rte_eth_dev *dev,
             struct rte_eth_dev_info *dev_info)
 {
@@ -1061,7 +1197,7 @@ eth_dev_info(struct rte_eth_dev *dev,
        internal = dev->data->dev_private;
        if (internal == NULL) {
                VHOST_LOG(ERR, "Invalid device specified\n");
-               return;
+               return -ENODEV;
        }
 
        dev_info->max_mac_addrs = 1;
@@ -1073,13 +1209,15 @@ eth_dev_info(struct rte_eth_dev *dev,
        dev_info->tx_offload_capa = DEV_TX_OFFLOAD_MULTI_SEGS |
                                DEV_TX_OFFLOAD_VLAN_INSERT;
        dev_info->rx_offload_capa = DEV_RX_OFFLOAD_VLAN_STRIP;
+
+       return 0;
 }
 
 static int
 eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 {
        unsigned i;
-       unsigned long rx_total = 0, tx_total = 0, tx_missed_total = 0;
+       unsigned long rx_total = 0, tx_total = 0;
        unsigned long rx_total_bytes = 0, tx_total_bytes = 0;
        struct vhost_queue *vq;
 
@@ -1101,7 +1239,6 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
                        continue;
                vq = dev->data->tx_queues[i];
                stats->q_opackets[i] = vq->stats.pkts;
-               tx_missed_total += vq->stats.missed_pkts;
                tx_total += stats->q_opackets[i];
 
                stats->q_obytes[i] = vq->stats.bytes;
@@ -1110,14 +1247,13 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 
        stats->ipackets = rx_total;
        stats->opackets = tx_total;
-       stats->oerrors = tx_missed_total;
        stats->ibytes = rx_total_bytes;
        stats->obytes = tx_total_bytes;
 
        return 0;
 }
 
-static void
+static int
 eth_stats_reset(struct rte_eth_dev *dev)
 {
        struct vhost_queue *vq;
@@ -1138,6 +1274,8 @@ eth_stats_reset(struct rte_eth_dev *dev)
                vq->stats.bytes = 0;
                vq->stats.missed_pkts = 0;
        }
+
+       return 0;
 }
 
 static void
@@ -1197,72 +1335,55 @@ static const struct eth_dev_ops ops = {
        .rx_queue_intr_disable = eth_rxq_intr_disable,
 };
 
-static struct rte_vdev_driver pmd_vhost_drv;
-
 static int
 eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
-       int16_t queues, const unsigned int numa_node, uint64_t flags)
+       int16_t queues, const unsigned int numa_node, uint64_t flags,
+       uint64_t disable_flags)
 {
        const char *name = rte_vdev_device_name(dev);
        struct rte_eth_dev_data *data;
        struct pmd_internal *internal = NULL;
        struct rte_eth_dev *eth_dev = NULL;
-       struct ether_addr *eth_addr = NULL;
-       struct rte_vhost_vring_state *vring_state = NULL;
-       struct internal_list *list = NULL;
+       struct rte_ether_addr *eth_addr = NULL;
 
        VHOST_LOG(INFO, "Creating VHOST-USER backend on numa socket %u\n",
                numa_node);
 
-       list = rte_zmalloc_socket(name, sizeof(*list), 0, numa_node);
-       if (list == NULL)
-               goto error;
-
        /* reserve an ethdev entry */
        eth_dev = rte_eth_vdev_allocate(dev, sizeof(*internal));
        if (eth_dev == NULL)
                goto error;
+       data = eth_dev->data;
 
        eth_addr = rte_zmalloc_socket(name, sizeof(*eth_addr), 0, numa_node);
        if (eth_addr == NULL)
                goto error;
+       data->mac_addrs = eth_addr;
        *eth_addr = base_eth_addr;
        eth_addr->addr_bytes[5] = eth_dev->data->port_id;
 
-       vring_state = rte_zmalloc_socket(name,
-                       sizeof(*vring_state), 0, numa_node);
-       if (vring_state == NULL)
-               goto error;
-
        /* now put it all together
         * - store queue data in internal,
         * - point eth_dev_data to internals
         * - and point eth_dev structure to new eth_dev_data structure
         */
        internal = eth_dev->data->dev_private;
-       internal->dev_name = strdup(name);
-       if (internal->dev_name == NULL)
-               goto error;
-       internal->iface_name = strdup(iface_name);
+       internal->iface_name = rte_malloc_socket(name, strlen(iface_name) + 1,
+                                                0, numa_node);
        if (internal->iface_name == NULL)
                goto error;
+       strcpy(internal->iface_name, iface_name);
 
-       list->eth_dev = eth_dev;
-       pthread_mutex_lock(&internal_list_lock);
-       TAILQ_INSERT_TAIL(&internal_list, list, next);
-       pthread_mutex_unlock(&internal_list_lock);
-
-       rte_spinlock_init(&vring_state->lock);
-       vring_states[eth_dev->data->port_id] = vring_state;
-
-       data = eth_dev->data;
        data->nb_rx_queues = queues;
        data->nb_tx_queues = queues;
        internal->max_queues = queues;
        internal->vid = -1;
+       internal->flags = flags;
+       internal->disable_flags = disable_flags;
        data->dev_link = pmd_link;
-       data->mac_addrs = eth_addr;
-       data->dev_flags = RTE_ETH_DEV_INTR_LSC;
+       data->dev_flags = RTE_ETH_DEV_INTR_LSC | RTE_ETH_DEV_CLOSE_REMOVE;
+       data->promiscuous = 1;
+       data->all_multicast = 1;
 
        eth_dev->dev_ops = &ops;
 
@@ -1270,34 +1391,13 @@ eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
        eth_dev->rx_pkt_burst = eth_vhost_rx;
        eth_dev->tx_pkt_burst = eth_vhost_tx;
 
-       if (rte_vhost_driver_register(iface_name, flags))
-               goto error;
-
-       if (rte_vhost_driver_callback_register(iface_name, &vhost_ops) < 0) {
-               VHOST_LOG(ERR, "Can't register callbacks\n");
-               goto error;
-       }
-
-       if (rte_vhost_driver_start(iface_name) < 0) {
-               VHOST_LOG(ERR, "Failed to start driver for %s\n",
-                       iface_name);
-               goto error;
-       }
-
        rte_eth_dev_probing_finish(eth_dev);
-       return data->port_id;
+       return 0;
 
 error:
-       if (internal) {
-               free(internal->iface_name);
-               free(internal->dev_name);
-       }
-       rte_free(vring_state);
-       rte_free(eth_addr);
-       if (eth_dev)
-               rte_eth_dev_release_port(eth_dev);
-       rte_free(internal);
-       rte_free(list);
+       if (internal)
+               rte_free(internal->iface_name);
+       rte_eth_dev_release_port(eth_dev);
 
        return -1;
 }
@@ -1338,10 +1438,14 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
        char *iface_name;
        uint16_t queues;
        uint64_t flags = 0;
+       uint64_t disable_flags = 0;
        int client_mode = 0;
        int dequeue_zero_copy = 0;
        int iommu_support = 0;
        int postcopy_support = 0;
+       int tso = 0;
+       int linear_buf = 0;
+       int ext_buf = 0;
        struct rte_eth_dev *eth_dev;
        const char *name = rte_vdev_device_name(dev);
 
@@ -1353,8 +1457,11 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
                        VHOST_LOG(ERR, "Failed to probe %s\n", name);
                        return -1;
                }
-               /* TODO: request info from primary to set up Rx and Tx */
+               eth_dev->rx_pkt_burst = eth_vhost_rx;
+               eth_dev->tx_pkt_burst = eth_vhost_tx;
                eth_dev->dev_ops = &ops;
+               if (dev->device.numa_node == SOCKET_ID_ANY)
+                       dev->device.numa_node = rte_socket_id();
                eth_dev->device = &dev->device;
                rte_eth_dev_probing_finish(eth_dev);
                return 0;
@@ -1423,11 +1530,48 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
                        flags |= RTE_VHOST_USER_POSTCOPY_SUPPORT;
        }
 
+       if (rte_kvargs_count(kvlist, ETH_VHOST_VIRTIO_NET_F_HOST_TSO) == 1) {
+               ret = rte_kvargs_process(kvlist,
+                               ETH_VHOST_VIRTIO_NET_F_HOST_TSO,
+                               &open_int, &tso);
+               if (ret < 0)
+                       goto out_free;
+
+               if (tso == 0) {
+                       disable_flags |= (1ULL << VIRTIO_NET_F_HOST_TSO4);
+                       disable_flags |= (1ULL << VIRTIO_NET_F_HOST_TSO6);
+               }
+       }
+
+       if (rte_kvargs_count(kvlist, ETH_VHOST_LINEAR_BUF) == 1) {
+               ret = rte_kvargs_process(kvlist,
+                               ETH_VHOST_LINEAR_BUF,
+                               &open_int, &linear_buf);
+               if (ret < 0)
+                       goto out_free;
+
+               if (linear_buf == 1)
+                       flags |= RTE_VHOST_USER_LINEARBUF_SUPPORT;
+       }
+
+       if (rte_kvargs_count(kvlist, ETH_VHOST_EXT_BUF) == 1) {
+               ret = rte_kvargs_process(kvlist,
+                               ETH_VHOST_EXT_BUF,
+                               &open_int, &ext_buf);
+               if (ret < 0)
+                       goto out_free;
+
+               if (ext_buf == 1)
+                       flags |= RTE_VHOST_USER_EXTBUF_SUPPORT;
+       }
+
        if (dev->device.numa_node == SOCKET_ID_ANY)
                dev->device.numa_node = rte_socket_id();
 
-       eth_dev_vhost_create(dev, iface_name, queues, dev->device.numa_node,
-               flags);
+       ret = eth_dev_vhost_create(dev, iface_name, queues,
+                                  dev->device.numa_node, flags, disable_flags);
+       if (ret == -1)
+               VHOST_LOG(ERR, "Failed to create %s\n", name);
 
 out_free:
        rte_kvargs_free(kvlist);
@@ -1446,16 +1590,13 @@ rte_pmd_vhost_remove(struct rte_vdev_device *dev)
        /* find an ethdev entry */
        eth_dev = rte_eth_dev_allocated(name);
        if (eth_dev == NULL)
-               return -ENODEV;
+               return 0;
 
        if (rte_eal_process_type() != RTE_PROC_PRIMARY)
-               return rte_eth_dev_release_port_secondary(eth_dev);
+               return rte_eth_dev_release_port(eth_dev);
 
        eth_dev_close(eth_dev);
 
-       rte_free(vring_states[eth_dev->data->port_id]);
-       vring_states[eth_dev->data->port_id] = NULL;
-
        rte_eth_dev_release_port(eth_dev);
 
        return 0;
@@ -1470,11 +1611,11 @@ RTE_PMD_REGISTER_VDEV(net_vhost, pmd_vhost_drv);
 RTE_PMD_REGISTER_ALIAS(net_vhost, eth_vhost);
 RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
        "iface=<ifc> "
-       "queues=<int>");
-
-RTE_INIT(vhost_init_log)
-{
-       vhost_logtype = rte_log_register("pmd.net.vhost");
-       if (vhost_logtype >= 0)
-               rte_log_set_level(vhost_logtype, RTE_LOG_NOTICE);
-}
+       "queues=<int> "
+       "client=<0|1> "
+       "dequeue-zero-copy=<0|1> "
+       "iommu-support=<0|1> "
+       "postcopy-support=<0|1> "
+       "tso=<0|1> "
+       "linear-buffer=<0|1> "
+       "ext-buffer=<0|1>");