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-rw-r--r--doc/guides/prog_guide/poll_mode_drv.rst34
1 files changed, 27 insertions, 7 deletions
diff --git a/doc/guides/prog_guide/poll_mode_drv.rst b/doc/guides/prog_guide/poll_mode_drv.rst
index 09a93ba..af82352 100644
--- a/doc/guides/prog_guide/poll_mode_drv.rst
+++ b/doc/guides/prog_guide/poll_mode_drv.rst
@@ -296,17 +296,37 @@ described in the mbuf API documentation and in the in :ref:`Mbuf Library
Per-Port and Per-Queue Offloads
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-In the DPDK offload API, offloads are divided into per-port and per-queue offloads.
+In the DPDK offload API, offloads are divided into per-port and per-queue offloads as follows:
+
+* A per-queue offloading can be enabled on a queue and disabled on another queue at the same time.
+* A pure per-port offload is the one supported by device but not per-queue type.
+* A pure per-port offloading can't be enabled on a queue and disabled on another queue at the same time.
+* A pure per-port offloading must be enabled or disabled on all queues at the same time.
+* Any offloading is per-queue or pure per-port type, but can't be both types at same devices.
+* Port capabilities = per-queue capabilities + pure per-port capabilities.
+* Any supported offloading can be enabled on all queues.
+
The different offloads capabilities can be queried using ``rte_eth_dev_info_get()``.
+The ``dev_info->[rt]x_queue_offload_capa`` returned from ``rte_eth_dev_info_get()`` includes all per-queue offloading capabilities.
+The ``dev_info->[rt]x_offload_capa`` returned from ``rte_eth_dev_info_get()`` includes all pure per-port and per-queue offloading capabilities.
Supported offloads can be either per-port or per-queue.
Offloads are enabled using the existing ``DEV_TX_OFFLOAD_*`` or ``DEV_RX_OFFLOAD_*`` flags.
-Per-port offload configuration is set using ``rte_eth_dev_configure``.
-Per-queue offload configuration is set using ``rte_eth_rx_queue_setup`` and ``rte_eth_tx_queue_setup``.
-To enable per-port offload, the offload should be set on both device configuration and queue setup.
-In case of a mixed configuration the queue setup shall return with an error.
-To enable per-queue offload, the offload can be set only on the queue setup.
-Offloads which are not enabled are disabled by default.
+Any requested offloading by an application must be within the device capabilities.
+Any offloading is disabled by default if it is not set in the parameter
+``dev_conf->[rt]xmode.offloads`` to ``rte_eth_dev_configure()`` and
+``[rt]x_conf->offloads`` to ``rte_eth_[rt]x_queue_setup()``.
+
+If any offloading is enabled in ``rte_eth_dev_configure()`` by an application,
+it is enabled on all queues no matter whether it is per-queue or
+per-port type and no matter whether it is set or cleared in
+``[rt]x_conf->offloads`` to ``rte_eth_[rt]x_queue_setup()``.
+
+If a per-queue offloading hasn't been enabled in ``rte_eth_dev_configure()``,
+it can be enabled or disabled in ``rte_eth_[rt]x_queue_setup()`` for individual queue.
+A newly added offloads in ``[rt]x_conf->offloads`` to ``rte_eth_[rt]x_queue_setup()`` input by application
+is the one which hasn't been enabled in ``rte_eth_dev_configure()`` and is requested to be enabled
+in ``rte_eth_[rt]x_queue_setup()``. It must be per-queue type, otherwise trigger an error log.
For an application to use the Tx offloads API it should set the ``ETH_TXQ_FLAGS_IGNORE`` flag in the ``txq_flags`` field located in ``rte_eth_txconf`` struct.
In such cases it is not required to set other flags in ``txq_flags``.