doc: update i40e features list

[dpdk.git] / doc / guides / nics / ena.rst

diff --git a/doc/guides/nics/ena.rst b/doc/guides/nics/ena.rst
index 9f0a650..bbf27f2 100644 (file)
--- a/doc/guides/nics/ena.rst
+++ b/doc/guides/nics/ena.rst
@@ -1,34 +1,7 @@
-.. BSD LICENSE
-
-    Copyright (c) 2015-2018 Amazon.com, Inc. or its affiliates.
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright (c) 2015-2019 Amazon.com, Inc. or its affiliates.
     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 Amazon.com, Inc. 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.
-
 ENA Poll Mode Driver
 ====================
 
@@ -183,10 +156,22 @@ Prerequisites
 #. Prepare the system as recommended by DPDK suite.  This includes environment
    variables, hugepages configuration, tool-chains and configuration.
 
-#. ENA PMD can operate with ``vfio-pci`` or ``igb_uio`` driver.
+#. ENA PMD can operate with ``vfio-pci``(*) or ``igb_uio`` driver.
+
+   (*) ENAv2 hardware supports Low Latency Queue v2 (LLQv2). This feature
+   reduces the latency of the packets by pushing the header directly through
+   the PCI to the device, before the DMA is even triggered. For proper work
+   kernel PCI driver must support write combining (WC). In mainline version of
+   ``igb_uio`` (in DPDK repo) it must be enabled by loading module with
+   ``wc_activate=1`` flag (example below). However, mainline's vfio-pci
+   driver in kernel doesn't have WC support yet (planed to be added).
+   If vfio-pci used user should be either turn off ENAv2 (to avoid performance
+   impact) or recompile vfio-pci driver with patch provided in
+   `amzn-github <https://github.com/amzn/amzn-drivers/tree/master/userspace/dpdk/enav2-vfio-patch>`_.
 
 #. Insert ``vfio-pci`` or ``igb_uio`` kernel module using the command
-   ``modprobe vfio-pci`` or ``modprobe igb_uio`` respectively.
+   ``modprobe vfio-pci`` or ``modprobe uio; insmod igb_uio.ko wc_activate=1``
+   respectively.
 
 #. For ``vfio-pci`` users only:
    Please make sure that ``IOMMU`` is enabled in your system,