New upstream version 18.02

[deb_dpdk.git] / doc / guides / bbdevs / null.rst

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+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) 2017 Intel Corporation
+
+BBDEV null Poll Mode Driver
+============================
+
+The (**bbdev_null**) is a bbdev poll mode driver which provides a minimal
+implementation of a software bbdev device. As a null device it does not modify
+the data in the mbuf on which the bbdev operation is to operate and it only
+works for operation type ``RTE_BBDEV_OP_NONE``.
+
+When a burst of mbufs is submitted to a *bbdev null PMD* for processing then
+each mbuf in the burst will be enqueued in an internal buffer ring to be
+collected on a dequeue call.
+
+
+Limitations
+-----------
+
+* In-place operations for Turbo encode and decode are not supported
+
+Installation
+------------
+
+The *bbdev null PMD* is enabled and built by default in both the Linux and
+FreeBSD builds.
+
+Initialization
+--------------
+
+To use the PMD in an application, user must:
+
+- Call ``rte_vdev_init("bbdev_null")`` within the application.
+
+- Use ``--vdev="bbdev_null"`` in the EAL options, which will call ``rte_vdev_init()`` internally.
+
+The following parameters (all optional) can be provided in the previous two calls:
+
+* ``socket_id``: Specify the socket where the memory for the device is going to be allocated
+  (by default, *socket_id* will be the socket where the core that is creating the PMD is running on).
+
+* ``max_nb_queues``: Specify the maximum number of queues in the device (default is ``RTE_MAX_LCORE``).
+
+Example:
+~~~~~~~~
+
+.. code-block:: console
+
+    ./test-bbdev.py -e="--vdev=bbdev_null,socket_id=0,max_nb_queues=8"