[dpdk-dev] [PATCH v2 3/4] net/netvsc: add documentation

[Stephen Hemminger <stephen@networkplumber.org>]

Matching documentation for new netvsc device.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 doc/guides/nics/index.rst              |  1 +
 doc/guides/nics/netvsc.rst             | 73 ++++++++++++++++++++++++++
 doc/guides/rel_notes/release_18_05.rst |  6 +++
 3 files changed, 80 insertions(+)
 create mode 100644 doc/guides/nics/netvsc.rst

diff --git a/doc/guides/nics/index.rst b/doc/guides/nics/index.rst
index ea9110c81159..97727731375a 100644
--- a/doc/guides/nics/index.rst
+++ b/doc/guides/nics/index.rst
@@ -23,6 +23,7 @@ Network Interface Controller Drivers
     ena
     enic
     fm10k
+    hyperv
     i40e
     igb
     ixgbe
diff --git a/doc/guides/nics/netvsc.rst b/doc/guides/nics/netvsc.rst
new file mode 100644
index 000000000000..db33772fb25b
--- /dev/null
+++ b/doc/guides/nics/netvsc.rst
@@ -0,0 +1,73 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright(c) Microsoft Corporation.
+
+Poll Mode Driver for Hyper-V Network Virtual NIC
+================================================
+
+Hyper-V is a hypervisor integrated into Window Server 2008, Windows 10
+and later versions.  It supports a para-virtualized network interface
+called netvsc that is visible on the virtual machine bus (VMBUS).  In
+the Data Plane Development Kit (DPDK), we provide a Network Virtual
+Service Client (NetVSC) Poll Mode Driver (PMD). The NetVSC PMD
+supports Windows Server 2016 and Microsoft Azure cloud.
+
+NetVSC Implementation in DPDK
+-----------------------------
+
+The Netvsc PMD is a standalone driver. VMBus network devices that are
+being used by DPDK must be unbound from the Linux kernel driver
+(hv_netvsc) and bound to the Userspace IO driver for Hyper-V
+(uio_hv_generic).
+
+This is most conveniently done with the
+`driverctl <https://gitlab.com/driverctl/driverctl>` script.
+The kernel must be version 5.0 or later to allow driver_override
+to work.
+
+To list all vmbus network devices
+  # driverctl -b vmbus -v list-devices | grep netvsc
+
+  # driverctl -b vmbus set-override <device guid> uio_hv_generic
+
+To determine the guid associated with a particular existing Ethernet
+device use:
+  $ basename $(readlink /sys/class/net/ethN/device)
+
+
+Features and Limitations of Hyper-V PMD
+---------------------------------------
+
+In this release, the hyper PMD driver provides the basic functionality of packet reception and transmission.
+
+*   It supports merge-able buffers per packet when receiving packets and scattered buffer per packet
+    when transmitting packets. The packet size supported is from 64 to 65536.
+
+*   It supports multicast packets and promiscuous mode. In order to this to work, the guest network
+    configuration on Hyper-V must be configured to allow this as well.
+
+*   Hyper-V driver does not support MAC or VLAN filtering because the host does not support it.
+    The device has only a single MAC address.
+
+*   VLAN tags are always stripped and presented in mbuf tci field.
+
+*   The Hyper-V driver does not use or support Link State or Rx interrupt.
+
+*   The number of queues is limited by the host (currently 64).
+    When used with 4.16 kernel only a single queue is available.
+
+*   This driver is intended for use with synthetic path only.
+    Accelerated Networking (SR-IOV) acceleration is not supported yet.
+    Use the VDEV_NETVSC device for accelerated networking instead.
+
+
+Prerequisites
+-------------
+
+The following prerequisites apply:
+
+*   Linux kernel support for UIO on vmbus is done with the uio_hv_generic driver.
+    This driver was originally added in 4.14 kernel, but that version lacks necessary
+    features for networking. The 4.16 kernel will work but is limited to a single queue.
+    Supporting multiple queues (subchannels) required additional changes
+    which were added in 5.0.
+
diff --git a/doc/guides/rel_notes/release_18_05.rst b/doc/guides/rel_notes/release_18_05.rst
index bc9cdda6af7a..91e7e8c9551b 100644
--- a/doc/guides/rel_notes/release_18_05.rst
+++ b/doc/guides/rel_notes/release_18_05.rst
@@ -115,6 +115,12 @@ New Features
 
   Linux uevent is supported as backend of this device event notification framework.
 
+* **Added experimental support for Hyper-V netvsc PMD.**
+
+  The new experimntal ``netvsc`` poll mode driver provides native support for
+  networking on Hyper-V. See the :doc:`../nics/netvsce` nic driver guide
+  for more details on this   new driver.
+
 
 API Changes
 -----------
-- 
2.17.0