Add more information on alternatives of KNI and the cons of KNI against
these alternatives.
Signed-off-by: Ferruh Yigit <ferruh.yi...@intel.com>
---
Cc: Olivier Matz <olivier.m...@6wind.com>
Cc: David Marchand <david.march...@redhat.com>
Cc: Stephen Hemminger <step...@networkplumber.org>
Cc: Elad Nachman <ela...@gmail.com>
Cc: Igor Ryzhov <iryz...@nfware.com>
Cc: Dan Gora <d...@adax.com>
---
doc/guides/nics/tap.rst | 2 ++
.../prog_guide/kernel_nic_interface.rst | 34 +++++++++++++++++--
2 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst
index 681010d9ed7d..2ba98893d564 100644
--- a/doc/guides/nics/tap.rst
+++ b/doc/guides/nics/tap.rst
@@ -1,6 +1,8 @@
.. SPDX-License-Identifier: BSD-3-Clause
Copyright(c) 2016 Intel Corporation.
+.. _TunTap_PMD:
+
Tun|Tap Poll Mode Driver
========================
diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst
b/doc/guides/prog_guide/kernel_nic_interface.rst
index 1ce03ec1a374..70e92687d711 100644
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -6,16 +6,44 @@
Kernel NIC Interface
====================
+.. Note::
+
+ :ref:`virtio_user_as_exceptional_path` alternative is the preferred way for
+ interfacing with the Linux network stack as it is an in-kernel solution and
+ has similar performance expectations.
+
The DPDK Kernel NIC Interface (KNI) allows userspace applications access to
the Linux* control plane.
-The benefits of using the DPDK KNI are:
+KNI provides an interface with the kernel network stack and allows management
of
+DPDK ports using standard Linux net tools such as ``ethtool``, ``ifconfig`` and
+``tcpdump``.
+
+The main use case of KNI is to get/receive exception packets from/to Linux
network
+stack while main datapath IO is done bypassing the networking stack.
+
+There are other alternatives to KNI, all are available in the upstream Linux:
+
+#. :ref:`virtio_user_as_exceptional_path`
+
+#. :ref:`TunTap_PMD` as wrapper to `Linux tun/tap
+ <https://www.kernel.org/doc/Documentation/networking/tuntap.txt>`_
+
+The benefits of using the KNI against alternatives are:
* Faster than existing Linux TUN/TAP interfaces
(by eliminating system calls and copy_to_user()/copy_from_user()
operations.
-* Allows management of DPDK ports using standard Linux net tools such as
ethtool, ifconfig and tcpdump.
+The cons of the KNI are:
+
+* It is out-of-tree Linux kernel module and it can't be distributed as binary
as
+ part of operating system vendor DPDK packages. This makes it harder to
+ consume, although it is always possible to compile it from the source code.
+
+* As it shares memory between userspace and kernelspace, and kernel part
+ directly uses input provided by userspace, it is not safe. This makes hard to
+ upstream the module.
-* Allows an interface with the kernel network stack.
+* Only a subset of net devices control commands are supported by KNI.
The components of an application using the DPDK Kernel NIC Interface are shown
in :numref:`figure_kernel_nic_intf`.
--
2.31.1
