--- /dev/null
+.. BSD LICENSE
+ Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * 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.
+ * Neither the name of Intel Corporation nor the names of its
+ contributors may be used to endorse or promote products derived
+ from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ OWNER 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.
+
+Libpcap and Ring Based Poll Mode Drivers
+========================================
+
+In addition to Poll Mode Drivers (PMDs) for physical and virtual hardware,
+the DPDK also includes two pure-software PMDs. These two drivers are:
+
+* A libpcap -based PMD (librte_pmd_pcap) that reads and writes packets using libpcap,
+ - both from files on disk, as well as from physical NIC devices using standard Linux kernel drivers.
+
+* A ring-based PMD (librte_pmd_ring) that allows a set of software FIFOs (that is, rte_ring)
+ to be accessed using the PMD APIs, as though they were physical NICs.
+
+.. note::
+
+ The libpcap -based PMD is disabled by default in the build configuration files,
+ owing to an external dependency on the libpcap development files which must be installed on the board.
+ Once the libpcap development files are installed,
+ the library can be enabled by setting CONFIG_RTE_LIBRTE_PMD_PCAP=y and recompiling the DPDK.
+
+Using the Drivers from the EAL Command Line
+-------------------------------------------
+
+For ease of use, the DPDK EAL also has been extended to allow pseudo-Ethernet devices,
+using one or more of these drivers,
+to be created at application startup time during EAL initialization.
+
+To do so, the --vdev= parameter must be passed to the EAL.
+This takes take options to allow ring and pcap-based Ethernet to be allocated and used transparently by the application.
+This can be used, for example, for testing on a virtual machine where there are no Ethernet ports.
+
+Libpcap-based PMD
+~~~~~~~~~~~~~~~~~
+
+Pcap-based devices can be created using the virtual device --vdev option.
+The device name must start with the eth_pcap prefix followed by numbers or letters.
+The name is unique for each device. Each device can have multiple stream options and multiple devices can be used.
+Multiple device definitions can be arranged using multiple --vdev.
+Device name and stream options must be separated by commas as shown below:
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c f -n 4 --vdev 'eth_pcap0,stream_opt0=..,stream_opt1=..' --vdev='eth_pcap1,stream_opt0=..'
+
+Device Streams
+^^^^^^^^^^^^^^
+
+Multiple ways of stream definitions can be assessed and combined as long as the following two rules are respected:
+
+* A device is provided with two different streams - reception and transmission.
+
+* A device is provided with one network interface name used for reading and writing packets.
+
+The different stream types are:
+
+* rx_pcap: Defines a reception stream based on a pcap file.
+ The driver reads each packet within the given pcap file as if it was receiving it from the wire.
+ The value is a path to a valid pcap file.
+
+ rx_pcap=/path/to/file.pcap
+
+* tx_pcap: Defines a transmission stream based on a pcap file.
+ The driver writes each received packet to the given pcap file.
+ The value is a path to a pcap file.
+ The file is overwritten if it already exists and it is created if it does not.
+
+ tx_pcap=/path/to/file.pcap
+
+* rx_iface: Defines a reception stream based on a network interface name.
+ The driver reads packets coming from the given interface using the Linux kernel driver for that interface.
+ The value is an interface name.
+
+ rx_iface=eth0
+
+* tx_iface: Defines a transmission stream based on a network interface name.
+ The driver sends packets to the given interface using the Linux kernel driver for that interface.
+ The value is an interface name.
+
+ tx_iface=eth0
+
+* iface: Defines a device mapping a network interface.
+ The driver both reads and writes packets from and to the given interface.
+ The value is an interface name.
+
+ iface=eth0
+
+Examples of Usage
+^^^^^^^^^^^^^^^^^
+
+Read packets from one pcap file and write them to another:
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c '0xf' -n 4 --vdev 'eth_pcap0,rx_pcap=/path/to/ file_rx.pcap,tx_pcap=/path/to/file_tx.pcap' -- --port-topology=chained
+
+Read packets from a network interface and write them to a pcap file:
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c '0xf' -n 4 --vdev 'eth_pcap0,rx_iface=eth0,tx_pcap=/path/to/file_tx.pcap' -- --port-topology=chained
+
+Read packets from a pcap file and write them to a network interface:
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c '0xf' -n 4 --vdev 'eth_pcap0,rx_pcap=/path/to/ file_rx.pcap,tx_iface=eth1' -- --port-topology=chained
+
+Forward packets through two network interfaces:
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c '0xf' -n 4 --vdev 'eth_pcap0,iface=eth0' --vdev='eth_pcap1;iface=eth1'
+
+Using libpcap-based PMD with the testpmd Application
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+One of the first things that testpmd does before starting to forward packets is to flush the RX streams
+by reading the first 512 packets on every RX stream and discarding them.
+When using a libpcap-based PMD this behavior can be turned off using the following command line option:
+
+.. code-block:: console
+
+ --no-flush-rx
+
+It is also available in the runtime command line:
+
+.. code-block:: console
+
+ set flush_rx on/off
+
+It is useful for the case where the rx_pcap is being used and no packets are meant to be discarded.
+Otherwise, the first 512 packets from the input pcap file will be discarded by the RX flushing operation.
+
+.. code-block:: console
+
+ $RTE_TARGET/app/testpmd -c '0xf' -n 4 --vdev 'eth_pcap0,rx_pcap=/path/to/ file_rx.pcap,tx_pcap=/path/to/file_tx.pcap' -- --port-topology=chained --no-flush-rx
+
+
+Rings-based PMD
+~~~~~~~~~~~~~~~
+
+To run a DPDK application on a machine without any Ethernet devices, a pair of ring-based rte_ethdevs can be used as below.
+The device names passed to the --vdev option must start with eth_ring and take no additional parameters.
+Multiple devices may be specified, separated by commas.
+
+.. code-block:: console
+
+ ./testpmd -c E -n 4 --vdev=eth_ring0 --vdev=eth_ring1 -- -i
+ EAL: Detected lcore 1 as core 1 on socket 0
+ ...
+
+ Interactive-mode selected
+ Configuring Port 0 (socket 0)
+ Configuring Port 1 (socket 0)
+ Checking link statuses...
+ Port 0 Link Up - speed 10000 Mbps - full-duplex
+ Port 1 Link Up - speed 10000 Mbps - full-duplex
+ Done
+
+ testpmd> start tx_first
+ io packet forwarding - CRC stripping disabled - packets/burst=16
+ nb forwarding cores=1 - nb forwarding ports=2
+ RX queues=1 - RX desc=128 - RX free threshold=0
+ RX threshold registers: pthresh=8 hthresh=8 wthresh=4
+ TX queues=1 - TX desc=512 - TX free threshold=0
+ TX threshold registers: pthresh=36 hthresh=0 wthresh=0
+ TX RS bit threshold=0 - TXQ flags=0x0
+
+ testpmd> stop
+ Telling cores to stop...
+ Waiting for lcores to finish...
+
+.. image:: img/forward_stats.*
+
+.. code-block:: console
+
+ +++++++++++++++ Accumulated forward statistics for allports++++++++++
+ RX-packets: 462384736 RX-dropped: 0 RX-total: 462384736
+ TX-packets: 462384768 TX-dropped: 0 TX-total: 462384768
+ +++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+ Done.
+
+
+Using the Poll Mode Driver from an Application
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Both drivers can provide similar APIs to allow the user to create a PMD, that is,
+rte_ethdev structure, instances at run-time in the end-application,
+for example, using rte_eth_from_rings() or rte_eth_from_pcaps() APIs.
+For the rings-based PMD, this functionality could be used, for example,
+to allow data exchange between cores using rings to be done in exactly the
+same way as sending or receiving packets from an Ethernet device.
+For the libpcap-based PMD, it allows an application to open one or more pcap files
+and use these as a source of packet input to the application.
+
+Usage Examples
+^^^^^^^^^^^^^^
+
+To create two pseudo-Ethernet ports where all traffic sent to a port is looped back
+for reception on the same port (error handling omitted for clarity):
+
+.. code-block:: c
+
+ #define RING_SIZE 256
+ #define NUM_RINGS 2
+ #define SOCKET0 0
+
+ struct rte_ring *ring[NUM_RINGS];
+ int port0, port1;
+
+ ring[0] = rte_ring_create("R0", RING_SIZE, SOCKET0, RING_F_SP_ENQ|RING_F_SC_DEQ);
+ ring[1] = rte_ring_create("R1", RING_SIZE, SOCKET0, RING_F_SP_ENQ|RING_F_SC_DEQ);
+
+ /* create two ethdev's */
+
+ port0 = rte_eth_from_rings("eth_ring0", ring, NUM_RINGS, ring, NUM_RINGS, SOCKET0);
+ port1 = rte_eth_from_rings("eth_ring1", ring, NUM_RINGS, ring, NUM_RINGS, SOCKET0);
+
+
+To create two pseudo-Ethernet ports where the traffic is switched between them,
+that is, traffic sent to port 0 is read back from port 1 and vice-versa,
+the final two lines could be changed as below:
+
+.. code-block:: c
+
+ port0 = rte_eth_from_rings("eth_ring0", &ring[0], 1, &ring[1], 1, SOCKET0);
+ port1 = rte_eth_from_rings("eth_ring1", &ring[1], 1, &ring[0], 1, SOCKET0);
+
+This type of configuration could be useful in a pipeline model, for example,
+where one may want to have inter-core communication using pseudo Ethernet devices rather than raw rings,
+for reasons of API consistency.
+
+Enqueuing and dequeuing items from an rte_ring using the rings-based PMD may be slower than using the native rings API.
+This is because DPDK Ethernet drivers make use of function pointers to call the appropriate enqueue or dequeue functions,
+while the rte_ring specific functions are direct function calls in the code and are often inlined by the compiler.
+
+ Once an ethdev has been created, for either a ring or a pcap-based PMD,
+ it should be configured and started in the same way as a regular Ethernet device, that is,
+ by calling rte_eth_dev_configure() to set the number of receive and transmit queues,
+ then calling rte_eth_rx_queue_setup() / tx_queue_setup() for each of those queues and
+ finally calling rte_eth_dev_start() to allow transmission and reception of packets to begin.
Code Review / deb_dpdk.git / blobdiff