Imported Upstream version 16.04

Change-Id: I77eadcd8538a9122e4773cbe55b24033dc451757
Signed-off-by: C.J. Collier <cjcollier@linuxfoundation.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/doc/guides/sample_app_ug/netmap_compatibility.rst b/doc/guides/sample_app_ug/netmap_compatibility.rst
new file mode 100644
index 00000000..41f05186
--- /dev/null
+++ b/doc/guides/sample_app_ug/netmap_compatibility.rst
@@ -0,0 +1,175 @@
+..  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.