..  SPDX-License-Identifier: BSD-3-Clause
    Copyright(c) 2018 Intel Corporation.

Intel(R) QuickAssist (QAT) Compression Poll Mode Driver
=======================================================

The QAT compression PMD provides poll mode compression & decompression driver
support for the following hardware accelerator devices:

* ``Intel QuickAssist Technology C62x``
* ``Intel QuickAssist Technology C3xxx``
* ``Intel QuickAssist Technology DH895x``


Features
--------

QAT compression PMD has support for:

Compression/Decompression algorithm:

    * DEFLATE - using Fixed and Dynamic Huffman encoding

Window size support:

    * 32K

Checksum generation:

    * CRC32, Adler and combined checksum

Stateful operation:

    * Decompression only

Limitations
-----------

* Compressdev level 0, no compression, is not supported.
* Queue-pairs are thread-safe on Intel CPUs but Queues are not (that is, within a single
  queue-pair all enqueues to the TX queue must be done from one thread and all dequeues
  from the RX queue must be done from one thread, but enqueues and dequeues may be done
  in different threads.)
* No BSD support as BSD QAT kernel driver not available.
* When using Deflate dynamic huffman encoding for compression, the input size (op.src.length)
  must be < CONFIG_RTE_PMD_QAT_COMP_IM_BUFFER_SIZE from the config file,
  see :ref:`building_qat_config` for more details.
* Stateful compression is not supported.


Installation
------------

The QAT compression PMD is built by default with a standard DPDK build.

It depends on a QAT kernel driver, see :ref:`building_qat`.