-.. BSD LICENSE
- Copyright(c) 2016 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
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- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-Tun/Tap Poll Mode Driver
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2016 Intel Corporation.
+
+Tun|Tap Poll Mode Driver
========================
-The ``rte_eth_tap.c`` PMD creates a device using TUN/TAP interfaces on the
+The ``rte_eth_tap.c`` PMD creates a device using TAP interfaces on the
local host. The PMD allows for DPDK and the host to communicate using a raw
device interface on the host and in the DPDK application.
These TAP interfaces can be used with Wireshark or tcpdump or Pktgen-DPDK
along with being able to be used as a network connection to the DPDK
application. The method enable one or more interfaces is to use the
-``--vdev=net_tap`` option on the DPDK application command line. Each
-``--vdev=net_tap`` option give will create an interface named dtap0, dtap1,
+``--vdev=net_tap0`` option on the DPDK application command line. Each
+``--vdev=net_tap1`` option given will create an interface named dtap0, dtap1,
and so on.
-The interfaced name can be changed by adding the ``iface=foo0``, for example::
+The interface name can be changed by adding the ``iface=foo0``, for example::
+
+ --vdev=net_tap0,iface=foo0 --vdev=net_tap1,iface=foo1, ...
+
+Normally the PMD will generate a random MAC address, but when testing or with
+a static configuration the developer may need a fixed MAC address style.
+Using the option ``mac=fixed`` you can create a fixed known MAC address::
+
+ --vdev=net_tap0,mac=fixed
+
+The MAC address will have a fixed value with the last octet incrementing by one
+for each interface string containing ``mac=fixed``. The MAC address is formatted
+as 00:'d':'t':'a':'p':[00-FF]. Convert the characters to hex and you get the
+actual MAC address: ``00:64:74:61:70:[00-FF]``.
- --vdev=net_tap,iface=foo0 --vdev=net_tap,iface=foo1, ...
+ --vdev=net_tap0,mac="00:64:74:61:70:11"
-Also the speed of the interface can be changed from 10G to whatever number
-needed, but the interface does not enforce that speed, for example::
+The MAC address will have a user value passed as string. The MAC address is in
+format with delimeter ``:``. The string is byte converted to hex and you get
+the actual MAC address: ``00:64:74:61:70:11``.
- --vdev=net_tap,iface=foo0,speed=25000
+It is possible to specify a remote netdevice to capture packets from by adding
+``remote=foo1``, for example::
+
+ --vdev=net_tap,iface=tap0,remote=foo1
+
+If a ``remote`` is set, the tap MAC address will be set to match the remote one
+just after netdevice creation. Using TC rules, traffic from the remote netdevice
+will be redirected to the tap. If the tap is in promiscuous mode, then all
+packets will be redirected. In allmulti mode, all multicast packets will be
+redirected.
+
+Using the remote feature is especially useful for capturing traffic from a
+netdevice that has no support in the DPDK. It is possible to add explicit
+rte_flow rules on the tap PMD to capture specific traffic (see next section for
+examples).
After the DPDK application is started you can send and receive packets on the
interface using the standard rx_burst/tx_burst APIs in DPDK. From the host
to address the interface using an IP address assigned to the internal
interface.
+The TUN PMD allows user to create a TUN device on host. The PMD allows user
+to transmit and receive packets via DPDK API calls with L3 header and payload.
+The devices in host can be accessed via ``ifconfig`` or ``ip`` command. TUN
+interfaces are passed to DPDK ``rte_eal_init`` arguments as ``--vdev=net_tunX``,
+where X stands for unique id, example::
+
+ --vdev=net_tun0 --vdev=net_tun1,iface=foo1, ...
+
+Unlike TAP PMD, TUN PMD does not support user arguments as ``MAC`` or ``remote`` user
+options. Default interface name is ``dtunX``, where X stands for unique id.
+
+Flow API support
+----------------
+
+The tap PMD supports major flow API pattern items and actions, when running on
+linux kernels above 4.2 ("Flower" classifier required).
+The kernel support can be checked with this command::
+
+ zcat /proc/config.gz | ( grep 'CLS_FLOWER=' || echo 'not supported' ) |
+ tee -a /dev/stderr | grep -q '=m' &&
+ lsmod | ( grep cls_flower || echo 'try modprobe cls_flower' )
+
+Supported items:
+
+- eth: src and dst (with variable masks), and eth_type (0xffff mask).
+- vlan: vid, pcp, but not eid. (requires kernel 4.9)
+- ipv4/6: src and dst (with variable masks), and ip_proto (0xffff mask).
+- udp/tcp: src and dst port (0xffff) mask.
+
+Supported actions:
+
+- DROP
+- QUEUE
+- PASSTHRU
+- RSS (requires kernel 4.9)
+
+It is generally not possible to provide a "last" item. However, if the "last"
+item, once masked, is identical to the masked spec, then it is supported.
+
+Only IPv4/6 and MAC addresses can use a variable mask. All other items need a
+full mask (exact match).
+
+As rules are translated to TC, it is possible to show them with something like::
+
+ tc -s filter show dev tap1 parent 1:
+
+Examples of testpmd flow rules
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Drop packets for destination IP 192.168.0.1::
+
+ testpmd> flow create 0 priority 1 ingress pattern eth / ipv4 dst is 1.1.1.1 \
+ / end actions drop / end
+
+Ensure packets from a given MAC address are received on a queue 2::
+
+ testpmd> flow create 0 priority 2 ingress pattern eth src is 06:05:04:03:02:01 \
+ / end actions queue index 2 / end
+
+Drop UDP packets in vlan 3::
+
+ testpmd> flow create 0 priority 3 ingress pattern eth / vlan vid is 3 / \
+ ipv4 proto is 17 / end actions drop / end
+
+Distribute IPv4 TCP packets using RSS to a given MAC address over queues 0-3::
+
+ testpmd> flow create 0 priority 4 ingress pattern eth dst is 0a:0b:0c:0d:0e:0f \
+ / ipv4 / tcp / end actions rss queues 0 1 2 3 end / end
+
+Multi-process sharing
+---------------------
+
+It is possible to attach an existing TAP device in a secondary process,
+by declaring it as a vdev with the same name as in the primary process,
+and without any parameter.
+
+The port attached in a secondary process will give access to the
+statistics and the queues.
+Therefore it can be used for monitoring or Rx/Tx processing.
+
+The IPC synchronization of Rx/Tx queues is currently limited:
+
+ - Maximum 8 queues shared
+ - Synchronized on probing, but not on later port update
+
Example
-------
-The following is a simple example of using the TUN/TAP PMD with the Pktgen
+The following is a simple example of using the TAP PMD with the Pktgen
packet generator. It requires that the ``socat`` utility is installed on the
test system.
Run pktgen from the pktgen directory in a terminal with a commandline like the
following::
- sudo ./app/app/x86_64-native-linuxapp-gcc/app/pktgen -l 1-5 -n 4 \
- --proc-type auto --log-level 8 --socket-mem 512,512 --file-prefix pg \
- --vdev=net_tap --vdev=net_tap -b 05:00.0 -b 05:00.1 \
+ sudo ./app/app/x86_64-native-linux-gcc/app/pktgen -l 1-5 -n 4 \
+ --proc-type auto --log-level debug --socket-mem 512,512 --file-prefix pg \
+ --vdev=net_tap0 --vdev=net_tap1 -b 05:00.0 -b 05:00.1 \
-b 04:00.0 -b 04:00.1 -b 04:00.2 -b 04:00.3 \
-b 81:00.0 -b 81:00.1 -b 81:00.2 -b 81:00.3 \
-b 82:00.0 -b 83:00.0 -- -T -P -m [2:3].0 -m [4:5].1 \
While running you should see the 64 byte counters increasing to verify the
traffic is being looped back. You can use ``set all size XXX`` to change the
-size of the packets after you stop the traffic. Use the pktgen ``help``
+size of the packets after you stop the traffic. Use pktgen ``help``
command to see a list of all commands. You can also use the ``-f`` option to
-load commands at startup.
+load commands at startup in command line or Lua script in pktgen.
+
+RSS specifics
+-------------
+Packet distribution in TAP is done by the kernel which has a default
+distribution. This feature is adding RSS distribution based on eBPF code.
+The default eBPF code calculates RSS hash based on Toeplitz algorithm for
+a fixed RSS key. It is calculated on fixed packet offsets. For IPv4 and IPv6 it
+is calculated over src/dst addresses (8 or 32 bytes for IPv4 or IPv6
+respectively) and src/dst TCP/UDP ports (4 bytes).
+
+The RSS algorithm is written in file ``tap_bpf_program.c`` which
+does not take part in TAP PMD compilation. Instead this file is compiled
+in advance to eBPF object file. The eBPF object file is then parsed and
+translated into eBPF byte code in the format of C arrays of eBPF
+instructions. The C array of eBPF instructions is part of TAP PMD tree and
+is taking part in TAP PMD compilation. At run time the C arrays are uploaded to
+the kernel via BPF system calls and the RSS hash is calculated by the
+kernel.
+
+It is possible to support different RSS hash algorithms by updating file
+``tap_bpf_program.c`` In order to add a new RSS hash algorithm follow these
+steps:
+
+1. Write the new RSS implementation in file ``tap_bpf_program.c``
+
+BPF programs which are uploaded to the kernel correspond to
+C functions under different ELF sections.
+
+2. Install ``LLVM`` library and ``clang`` compiler versions 3.7 and above
+
+3. Compile ``tap_bpf_program.c`` via ``LLVM`` into an object file::
+
+ clang -O2 -emit-llvm -c tap_bpf_program.c -o - | llc -march=bpf \
+ -filetype=obj -o <tap_bpf_program.o>
+
+
+4. Use a tool that receives two parameters: an eBPF object file and a section
+name, and prints out the section as a C array of eBPF instructions.
+Embed the C array in your TAP PMD tree.
+
+The C arrays are uploaded to the kernel using BPF system calls.
+
+``tc`` (traffic control) is a well known user space utility program used to
+configure the Linux kernel packet scheduler. It is usually packaged as
+part of the ``iproute2`` package.
+Since commit 11c39b5e9 ("tc: add eBPF support to f_bpf") ``tc`` can be used
+to uploads eBPF code to the kernel and can be patched in order to print the
+C arrays of eBPF instructions just before calling the BPF system call.
+Please refer to ``iproute2`` package file ``lib/bpf.c`` function
+``bpf_prog_load()``.
+
+An example utility for eBPF instruction generation in the format of C arrays will
+be added in next releases
+
+TAP reports on supported RSS functions as part of dev_infos_get callback:
+``ETH_RSS_IP``, ``ETH_RSS_UDP`` and ``ETH_RSS_TCP``.
+**Known limitation:** TAP supports all of the above hash functions together
+and not in partial combinations.
+
+Systems supporting flow API
+---------------------------
+
+- "tc flower" classifier requires linux kernel above 4.2
+- eBPF/RSS requires linux kernel above 4.9
+
++--------------------+-----------------------+
+| RH7.3 | No flow rule support |
++--------------------+-----------------------+
+| RH7.4 | No RSS action support |
++--------------------+-----------------------+
+| RH7.5 | No RSS action support |
++--------------------+-----------------------+
+| SLES 15, | No limitation |
+| kernel 4.12 | |
++--------------------+-----------------------+
+| Azure Ubuntu 16.04,| No limitation |
+| kernel 4.13 | |
++--------------------+-----------------------+
+
git.droids-corp.org / dpdk.git / blobdiff