--- /dev/null
+.. BSD LICENSE
+ Copyright(c) 2010-2014 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.
+
+
+Netmap Compatibility Sample Application
+=======================================
+
+Introduction
+------------
+
+The Netmap compatibility library provides a minimal set of APIs to give programs written against the Netmap APIs
+the ability to be run, with minimal changes to their source code, using the DPDK to perform the actual packet I/O.
+
+Since Netmap applications use regular system calls, like ``open()``, ``ioctl()`` and
+``mmap()`` to communicate with the Netmap kernel module performing the packet I/O,
+the ``compat_netmap`` library provides a set of similar APIs to use in place of those system calls,
+effectively turning a Netmap application into a DPDK application.
+
+The provided library is currently minimal and doesn't support all the features that Netmap supports,
+but is enough to run simple applications, such as the bridge example detailed below.
+
+Knowledge of Netmap is required to understand the rest of this section.
+Please refer to the Netmap distribution for details about Netmap.
+
+Available APIs
+--------------
+
+The library provides the following drop-in replacements for system calls usually used in Netmap applications:
+
+* ``rte_netmap_close()``
+
+* ``rte_netmap_ioctl()``
+
+* ``rte_netmap_open()``
+
+* ``rte_netmap_mmap()``
+
+* ``rte_netmap_poll()``
+
+They use the same signature as their libc counterparts, and can be used as drop-in replacements in most cases.
+
+Caveats
+-------
+
+Given the difference between the way Netmap and the DPDK approach packet I/O,
+there are caveats and limitations to be aware of when trying to use the ``compat_netmap`` library, the most important of these are listed below.
+These may change as the library is updated:
+
+* Any system call that can potentially affect file descriptors cannot be used with a descriptor returned by the ``rte_netmap_open()`` function.
+
+Note that:
+
+* The ``rte_netmap_mmap()`` function merely returns the address of a DPDK memzone.
+ The address, length, flags, offset, and other arguments are ignored.
+
+* The ``rte_netmap_poll()`` function only supports infinite (negative) or zero time outs.
+ It effectively turns calls to the ``poll()`` system call made in a Netmap application into polling of the DPDK ports,
+ changing the semantics of the usual POSIX defined poll.
+
+* Not all of Netmap's features are supported: host rings,
+ slot flags and so on are not supported or are simply not relevant in the DPDK model.
+
+* The Netmap manual page states that "*a device obtained through /dev/netmap also supports the ioctl supported by network devices*".
+ This is not the case with this compatibility layer.
+
+* The Netmap kernel module exposes a sysfs interface to change some internal parameters, such as the size of the shared memory region.
+ This interface is not available when using this compatibility layer.
+
+Porting Netmap Applications
+---------------------------
+
+Porting Netmap applications typically involves two major steps:
+
+* Changing the system calls to use their ``compat_netmap`` library counterparts.
+
+* Adding further DPDK initialization code.
+
+Since the ``compat_netmap`` functions have the same signature as the usual libc calls, the change is trivial in most cases.
+
+The usual DPDK initialization code involving ``rte_eal_init()`` and ``rte_eal_pci_probe()``
+has to be added to the Netmap application in the same way it is used in all other DPDK sample applications.
+Please refer to the *DPDK Programmer's Guide* and example source code for details about initialization.
+
+In addition of the regular DPDK initialization code,
+the ported application needs to call initialization functions for the ``compat_netmap`` library,
+namely ``rte_netmap_init()`` and ``rte_netmap_init_port()``.
+
+These two initialization functions take ``compat_netmap`` specific data structures as parameters:
+``struct rte_netmap_conf`` and ``struct rte_netmap_port_conf``.
+The structures' fields are Netmap related and are self-explanatory for developers familiar with Netmap.
+They are defined in ``$RTE_SDK/examples/netmap_compat/lib/compat_netmap.h``.
+
+The bridge application is an example largely based on the bridge example shipped with the Netmap distribution.
+It shows how a minimal Netmap application with minimal and straightforward source code changes can be run on top of the DPDK.
+Please refer to ``$RTE_SDK/examples/netmap_compat/bridge/bridge.c`` for an example of a ported application.
+
+Compiling the "bridge" Sample Application
+-----------------------------------------
+
+#. Go to the example directory:
+
+ .. code-block:: console
+
+ export RTE_SDK=/path/to/rte_sdk
+ cd ${RTE_SDK}/examples/netmap_compat
+
+#. Set the target (a default target is used if not specified). For example:
+
+ .. code-block:: console
+
+ export RTE_TARGET=x86_64-native-linuxapp-gcc
+
+ See the *DPDK Getting Started Guide for Linux* for possible ``RTE_TARGET`` values.
+
+#. Build the application:
+
+ .. code-block:: console
+
+ make
+
+Running the "bridge" Sample Application
+---------------------------------------
+
+The application requires a single command line option:
+
+.. code-block:: console
+
+ ./build/bridge [EAL options] -- -i INTERFACE_A [-i INTERFACE_B]
+
+where,
+
+* ``-i INTERFACE``: Interface (DPDK port number) to use.
+
+ If a single ``-i`` parameter is given, the interface will send back all the traffic it receives.
+ If two ``-i`` parameters are given, the two interfaces form a bridge,
+ where traffic received on one interface is replicated and sent to the other interface.
+
+For example, to run the application in a linuxapp environment using port 0 and 2:
+
+.. code-block:: console
+
+ ./build/bridge [EAL options] -- -i 0 -i 2
+
+Refer to the *DPDK Getting Started Guide for Linux* for general information on running applications and
+the Environment Abstraction Layer (EAL) options.
+
+Note that unlike a traditional bridge or the ``l2fwd`` sample application, no MAC address changes are done on the frames.
+Do not forget to take this into account when configuring a traffic generators and testing this sample application.
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