+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Process a burst of output packets on a transmit queue of an Ethernet device.
+ *
+ * The rte_eth_tx_prepare() function is invoked to prepare output packets to be
+ * transmitted on the output queue *queue_id* of the Ethernet device designated
+ * by its *port_id*.
+ * The *nb_pkts* parameter is the number of packets to be prepared which are
+ * supplied in the *tx_pkts* array of *rte_mbuf* structures, each of them
+ * allocated from a pool created with rte_pktmbuf_pool_create().
+ * For each packet to send, the rte_eth_tx_prepare() function performs
+ * the following operations:
+ *
+ * - Check if packet meets devices requirements for tx offloads.
+ *
+ * - Check limitations about number of segments.
+ *
+ * - Check additional requirements when debug is enabled.
+ *
+ * - Update and/or reset required checksums when tx offload is set for packet.
+ *
+ * Since this function can modify packet data, provided mbufs must be safely
+ * writable (e.g. modified data cannot be in shared segment).
+ *
+ * The rte_eth_tx_prepare() function returns the number of packets ready to be
+ * sent. A return value equal to *nb_pkts* means that all packets are valid and
+ * ready to be sent, otherwise stops processing on the first invalid packet and
+ * leaves the rest packets untouched.
+ *
+ * When this functionality is not implemented in the driver, all packets are
+ * are returned untouched.
+ *
+ * @param port_id
+ * The port identifier of the Ethernet device.
+ * The value must be a valid port id.
+ * @param queue_id
+ * The index of the transmit queue through which output packets must be
+ * sent.
+ * The value must be in the range [0, nb_tx_queue - 1] previously supplied
+ * to rte_eth_dev_configure().
+ * @param tx_pkts
+ * The address of an array of *nb_pkts* pointers to *rte_mbuf* structures
+ * which contain the output packets.
+ * @param nb_pkts
+ * The maximum number of packets to process.
+ * @return
+ * The number of packets correct and ready to be sent. The return value can be
+ * less than the value of the *tx_pkts* parameter when some packet doesn't
+ * meet devices requirements with rte_errno set appropriately:
+ * - -EINVAL: offload flags are not correctly set
+ * - -ENOTSUP: the offload feature is not supported by the hardware
+ *
+ */
+
+#ifndef RTE_ETHDEV_TX_PREPARE_NOOP
+
+static inline uint16_t
+rte_eth_tx_prepare(uint8_t port_id, uint16_t queue_id,
+ struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
+{
+ struct rte_eth_dev *dev;
+
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+ if (!rte_eth_dev_is_valid_port(port_id)) {
+ RTE_PMD_DEBUG_TRACE("Invalid TX port_id=%d\n", port_id);
+ rte_errno = -EINVAL;
+ return 0;
+ }
+#endif
+
+ dev = &rte_eth_devices[port_id];
+
+#ifdef RTE_LIBRTE_ETHDEV_DEBUG
+ if (queue_id >= dev->data->nb_tx_queues) {
+ RTE_PMD_DEBUG_TRACE("Invalid TX queue_id=%d\n", queue_id);
+ rte_errno = -EINVAL;
+ return 0;
+ }
+#endif
+
+ if (!dev->tx_pkt_prepare)
+ return nb_pkts;
+
+ return (*dev->tx_pkt_prepare)(dev->data->tx_queues[queue_id],
+ tx_pkts, nb_pkts);
+}
+
+#else
+
+/*
+ * Native NOOP operation for compilation targets which doesn't require any
+ * preparations steps, and functional NOOP may introduce unnecessary performance
+ * drop.
+ *
+ * Generally this is not a good idea to turn it on globally and didn't should
+ * be used if behavior of tx_preparation can change.
+ */
+
+static inline uint16_t
+rte_eth_tx_prepare(__rte_unused uint8_t port_id, __rte_unused uint16_t queue_id,
+ __rte_unused struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
+{
+ return nb_pkts;
+}
+
+#endif
+
+typedef void (*buffer_tx_error_fn)(struct rte_mbuf **unsent, uint16_t count,
+ void *userdata);
+
+/**
+ * Structure used to buffer packets for future TX
+ * Used by APIs rte_eth_tx_buffer and rte_eth_tx_buffer_flush
+ */
+struct rte_eth_dev_tx_buffer {
+ buffer_tx_error_fn error_callback;
+ void *error_userdata;
+ uint16_t size; /**< Size of buffer for buffered tx */
+ uint16_t length; /**< Number of packets in the array */
+ struct rte_mbuf *pkts[];
+ /**< Pending packets to be sent on explicit flush or when full */
+};
+
+/**
+ * Calculate the size of the tx buffer.
+ *
+ * @param sz
+ * Number of stored packets.
+ */
+#define RTE_ETH_TX_BUFFER_SIZE(sz) \
+ (sizeof(struct rte_eth_dev_tx_buffer) + (sz) * sizeof(struct rte_mbuf *))
+
+/**
+ * Initialize default values for buffered transmitting
+ *
+ * @param buffer
+ * Tx buffer to be initialized.
+ * @param size
+ * Buffer size
+ * @return
+ * 0 if no error
+ */
+int
+rte_eth_tx_buffer_init(struct rte_eth_dev_tx_buffer *buffer, uint16_t size);
+
+/**
+ * Send any packets queued up for transmission on a port and HW queue
+ *
+ * This causes an explicit flush of packets previously buffered via the
+ * rte_eth_tx_buffer() function. It returns the number of packets successfully
+ * sent to the NIC, and calls the error callback for any unsent packets. Unless
+ * explicitly set up otherwise, the default callback simply frees the unsent
+ * packets back to the owning mempool.
+ *
+ * @param port_id
+ * The port identifier of the Ethernet device.
+ * @param queue_id
+ * The index of the transmit queue through which output packets must be
+ * sent.
+ * The value must be in the range [0, nb_tx_queue - 1] previously supplied
+ * to rte_eth_dev_configure().
+ * @param buffer
+ * Buffer of packets to be transmit.
+ * @return
+ * The number of packets successfully sent to the Ethernet device. The error
+ * callback is called for any packets which could not be sent.
+ */
+static inline uint16_t
+rte_eth_tx_buffer_flush(uint8_t port_id, uint16_t queue_id,
+ struct rte_eth_dev_tx_buffer *buffer)
+{
+ uint16_t sent;
+ uint16_t to_send = buffer->length;
+
+ if (to_send == 0)
+ return 0;
+
+ sent = rte_eth_tx_burst(port_id, queue_id, buffer->pkts, to_send);
+
+ buffer->length = 0;
+
+ /* All packets sent, or to be dealt with by callback below */
+ if (unlikely(sent != to_send))
+ buffer->error_callback(&buffer->pkts[sent], to_send - sent,
+ buffer->error_userdata);
+
+ return sent;
+}
+
+/**
+ * Buffer a single packet for future transmission on a port and queue
+ *
+ * This function takes a single mbuf/packet and buffers it for later
+ * transmission on the particular port and queue specified. Once the buffer is
+ * full of packets, an attempt will be made to transmit all the buffered
+ * packets. In case of error, where not all packets can be transmitted, a
+ * callback is called with the unsent packets as a parameter. If no callback
+ * is explicitly set up, the unsent packets are just freed back to the owning
+ * mempool. The function returns the number of packets actually sent i.e.
+ * 0 if no buffer flush occurred, otherwise the number of packets successfully
+ * flushed
+ *
+ * @param port_id
+ * The port identifier of the Ethernet device.
+ * @param queue_id
+ * The index of the transmit queue through which output packets must be
+ * sent.
+ * The value must be in the range [0, nb_tx_queue - 1] previously supplied
+ * to rte_eth_dev_configure().
+ * @param buffer
+ * Buffer used to collect packets to be sent.
+ * @param tx_pkt
+ * Pointer to the packet mbuf to be sent.
+ * @return
+ * 0 = packet has been buffered for later transmission
+ * N > 0 = packet has been buffered, and the buffer was subsequently flushed,
+ * causing N packets to be sent, and the error callback to be called for
+ * the rest.
+ */
+static inline uint16_t __attribute__((always_inline))
+rte_eth_tx_buffer(uint8_t port_id, uint16_t queue_id,
+ struct rte_eth_dev_tx_buffer *buffer, struct rte_mbuf *tx_pkt)
+{
+ buffer->pkts[buffer->length++] = tx_pkt;
+ if (buffer->length < buffer->size)
+ return 0;
+
+ return rte_eth_tx_buffer_flush(port_id, queue_id, buffer);
+}
+
+/**
+ * Configure a callback for buffered packets which cannot be sent
+ *
+ * Register a specific callback to be called when an attempt is made to send
+ * all packets buffered on an ethernet port, but not all packets can
+ * successfully be sent. The callback registered here will be called only
+ * from calls to rte_eth_tx_buffer() and rte_eth_tx_buffer_flush() APIs.
+ * The default callback configured for each queue by default just frees the
+ * packets back to the calling mempool. If additional behaviour is required,
+ * for example, to count dropped packets, or to retry transmission of packets
+ * which cannot be sent, this function should be used to register a suitable
+ * callback function to implement the desired behaviour.
+ * The example callback "rte_eth_count_unsent_packet_callback()" is also
+ * provided as reference.
+ *
+ * @param buffer
+ * The port identifier of the Ethernet device.
+ * @param callback
+ * The function to be used as the callback.
+ * @param userdata
+ * Arbitrary parameter to be passed to the callback function
+ * @return
+ * 0 on success, or -1 on error with rte_errno set appropriately
+ */
+int
+rte_eth_tx_buffer_set_err_callback(struct rte_eth_dev_tx_buffer *buffer,
+ buffer_tx_error_fn callback, void *userdata);
+
+/**
+ * Callback function for silently dropping unsent buffered packets.
+ *
+ * This function can be passed to rte_eth_tx_buffer_set_err_callback() to
+ * adjust the default behavior when buffered packets cannot be sent. This
+ * function drops any unsent packets silently and is used by tx buffered
+ * operations as default behavior.
+ *
+ * NOTE: this function should not be called directly, instead it should be used
+ * as a callback for packet buffering.
+ *
+ * NOTE: when configuring this function as a callback with
+ * rte_eth_tx_buffer_set_err_callback(), the final, userdata parameter
+ * should point to an uint64_t value.
+ *
+ * @param pkts
+ * The previously buffered packets which could not be sent
+ * @param unsent
+ * The number of unsent packets in the pkts array
+ * @param userdata
+ * Not used
+ */
+void
+rte_eth_tx_buffer_drop_callback(struct rte_mbuf **pkts, uint16_t unsent,
+ void *userdata);
+
+/**
+ * Callback function for tracking unsent buffered packets.
+ *
+ * This function can be passed to rte_eth_tx_buffer_set_err_callback() to
+ * adjust the default behavior when buffered packets cannot be sent. This
+ * function drops any unsent packets, but also updates a user-supplied counter
+ * to track the overall number of packets dropped. The counter should be an
+ * uint64_t variable.
+ *
+ * NOTE: this function should not be called directly, instead it should be used
+ * as a callback for packet buffering.
+ *
+ * NOTE: when configuring this function as a callback with
+ * rte_eth_tx_buffer_set_err_callback(), the final, userdata parameter
+ * should point to an uint64_t value.
+ *
+ * @param pkts
+ * The previously buffered packets which could not be sent
+ * @param unsent
+ * The number of unsent packets in the pkts array
+ * @param userdata
+ * Pointer to an uint64_t value, which will be incremented by unsent
+ */
+void
+rte_eth_tx_buffer_count_callback(struct rte_mbuf **pkts, uint16_t unsent,
+ void *userdata);
+
+/**
+ * Request the driver to free mbufs currently cached by the driver. The
+ * driver will only free the mbuf if it is no longer in use. It is the
+ * application's responsibity to ensure rte_eth_tx_buffer_flush(..) is
+ * called if needed.
+ *
+ * @param port_id
+ * The port identifier of the Ethernet device.
+ * @param queue_id
+ * The index of the transmit queue through which output packets must be
+ * sent.
+ * The value must be in the range [0, nb_tx_queue - 1] previously supplied
+ * to rte_eth_dev_configure().
+ * @param free_cnt
+ * Maximum number of packets to free. Use 0 to indicate all possible packets
+ * should be freed. Note that a packet may be using multiple mbufs.
+ * @return
+ * Failure: < 0
+ * -ENODEV: Invalid interface
+ * -ENOTSUP: Driver does not support function
+ * Success: >= 0
+ * 0-n: Number of packets freed. More packets may still remain in ring that
+ * are in use.
+ */
+int
+rte_eth_tx_done_cleanup(uint8_t port_id, uint16_t queue_id, uint32_t free_cnt);
+
+/**
+ * The eth device event type for interrupt, and maybe others in the future.
+ */