--- /dev/null
+.. BSD LICENSE
+ Copyright 2017 6WIND S.A.
+
+ 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 6WIND S.A. 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.
+
+Fail-safe poll mode driver library
+==================================
+
+The Fail-safe poll mode driver library (**librte_pmd_failsafe**) is a virtual
+device that allows using any device supporting hotplug (sudden device removal
+and plugging on its bus), without modifying other components relying on such
+device (application, other PMDs).
+
+Additionally to the Seamless Hotplug feature, the Fail-safe PMD offers the
+ability to redirect operations to secondary devices when the primary has been
+removed from the system.
+
+.. note::
+
+ The library is enabled by default. You can enable it or disable it manually
+ by setting the ``CONFIG_RTE_LIBRTE_PMD_FAILSAFE`` configuration option.
+
+Features
+--------
+
+The Fail-safe PMD only supports a limited set of features. If you plan to use a
+device underneath the Fail-safe PMD with a specific feature, this feature must
+be supported by the Fail-safe PMD to avoid throwing any error.
+
+A notable exception is the device removal feature. The fail-safe PMD being a
+virtual device, it cannot currently be removed in the sense of a specific bus
+hotplug, like for PCI for example. It will however enable this feature for its
+sub-device automatically, detecting those that are capable and register the
+relevant callback for such event.
+
+Check the feature matrix for the complete set of supported features.
+
+Compilation option
+------------------
+
+This option can be modified in the ``$RTE_TARGET/build/.config`` file.
+
+- ``CONFIG_RTE_LIBRTE_PMD_FAILSAFE`` (default **y**)
+
+ Toggle compiling librte_pmd_failsafe.
+
+Using the Fail-safe PMD from the EAL command line
+-------------------------------------------------
+
+The Fail-safe PMD can be used like most other DPDK virtual devices, by passing a
+``--vdev`` parameter to the EAL when starting the application. The device name
+must start with the *net_failsafe* prefix, followed by numbers or letters. This
+name must be unique for each device. Each fail-safe instance must have at least one
+sub-device, up to ``RTE_MAX_ETHPORTS-1``.
+
+A sub-device can be any legal DPDK device, including possibly another fail-safe
+instance.
+
+Fail-safe command line parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- **dev(<iface>)** parameter
+
+ This parameter allows the user to define a sub-device. The ``<iface>`` part of
+ this parameter must be a valid device definition. It could be the argument
+ provided to any ``-w`` device specification or the argument that would be
+ given to a ``--vdev`` parameter (including a fail-safe).
+ Enclosing the device definition within parenthesis here allows using
+ additional sub-device parameters if need be. They will be passed on to the
+ sub-device.
+
+- **exec(<shell command>)** parameter
+
+ This parameter allows the user to provide a command to the fail-safe PMD to
+ execute and define a sub-device.
+ It is done within a regular shell context.
+ The first line of its output is read by the fail-safe PMD and otherwise
+ interpreted as if passed by the regular **dev** parameter.
+ Any other line is discarded.
+ If the command fail or output an incorrect string, the sub-device is not
+ initialized.
+ All commas within the ``shell command`` are replaced by spaces before
+ executing the command. This helps using scripts to specify devices.
+
+- **mac** parameter [MAC address]
+
+ This parameter allows the user to set a default MAC address to the fail-safe
+ and all of its sub-devices.
+ If no default mac address is provided, the fail-safe PMD will read the MAC
+ address of the first of its sub-device to be successfully probed and use it as
+ its default MAC address, trying to set it to all of its other sub-devices.
+ If no sub-device was successfully probed at initialization, then a random MAC
+ address is generated, that will be subsequently applied to all sub-device once
+ they are probed.
+
+- **hotplug_poll** parameter [UINT64] (default **2000**)
+
+ This parameter allows the user to configure the amount of time in milliseconds
+ between two slave upkeep round.
+
+Usage example
+~~~~~~~~~~~~~
+
+This section shows some example of using **testpmd** with a fail-safe PMD.
+
+#. To build a PMD and configure DPDK, refer to the document
+ :ref:`compiling and testing a PMD for a NIC <pmd_build_and_test>`.
+
+#. Start testpmd. The slave device should be blacklisted from normal EAL
+ operations to avoid probing it twice when in PCI blacklist mode.
+
+ .. code-block:: console
+
+ $RTE_TARGET/build/app/testpmd -c 0xff -n 4 \
+ --vdev 'net_failsafe0,mac=de:ad:be:ef:01:02,dev(84:00.0),dev(net_ring0)'
+ -b 84:00.0 -b 00:04.0 -- -i
+
+ If the slave device being used is not blacklisted, it will be probed by the
+ EAL first. When the fail-safe then tries to initialize it the probe operation
+ fails.
+
+ Note that PCI blacklist mode is the default PCI operating mode.
+
+#. Alternatively, it can be used alongside any other device in whitelist mode.
+
+ .. code-block:: console
+
+ $RTE_TARGET/build/app/testpmd -c 0xff -n 4 \
+ --vdev 'net_failsafe0,mac=de:ad:be:ef:01:02,dev(84:00.0),dev(net_ring0)'
+ -w 81:00.0 -- -i
+
+#. Start testpmd using a flexible device definition
+
+ .. code-block:: console
+
+ $RTE_TARGET/build/app/testpmd -c 0xff -n 4 --no-pci \
+ --vdev='net_failsafe0,exec(echo 84:00.0)' -- -i
+
+Using the Fail-safe PMD from an application
+-------------------------------------------
+
+This driver strives to be as seamless as possible to existing applications, in
+order to propose the hotplug functionality in the easiest way possible.
+
+Care must be taken, however, to respect the **ether** API concerning device
+access, and in particular, using the ``RTE_ETH_FOREACH_DEV`` macro to iterate
+over ethernet devices, instead of directly accessing them or by writing one's
+own device iterator.
+
+Plug-in feature
+---------------
+
+A sub-device can be defined without existing on the system when the fail-safe
+PMD is initialized. Upon probing this device, the fail-safe PMD will detect its
+absence and postpone its use. It will then register for a periodic check on any
+missing sub-device.
+
+During this time, the fail-safe PMD can be used normally, configured and told to
+emit and receive packets. It will store any applied configuration, and try to
+apply it upon the probing of its missing sub-device. After this configuration
+pass, the new sub-device will be synchronized with other sub-devices, i.e. be
+started if the fail-safe PMD has been started by the user before.
+
+Plug-out feature
+----------------
+
+A sub-device supporting the device removal event can be removed from its bus at
+any time. The fail-safe PMD will register a callback for such event and react
+accordingly. It will try to safely stop, close and uninit the sub-device having
+emitted this event, allowing it to free its eventual resources.
+
+Fail-safe glossary
+------------------
+
+Fallback device : Secondary device
+ The fail-safe will fail-over onto this device when the preferred device is
+ absent.
+
+Preferred device : Primary device
+ The first declared sub-device in the fail-safe parameters.
+ When this device is plugged, it is always used as emitting device.
+ It is the main sub-device and is used as target for configuration
+ operations if there is any ambiguity.
+
+Upkeep round
+ Periodical process when slaves are serviced. Each devices having a state
+ different to that of the fail-safe device itself, is synchronized with it.
+ Additionally, each slave having the remove flag set are cleaned-up.
+
+Slave
+ In the context of the fail-safe PMD, synonymous to sub-device.
+
+Sub-device
+ A device being utilized by the fail-safe PMD.
+ This is another PMD running underneath the fail-safe PMD.
+ Any sub-device can disappear at any time. The fail-safe will ensure
+ that the device removal happens gracefully.
Code Review / deb_dpdk.git / blobdiff