Hyper-V network driver
======================

Compatibility
=============

This driver is compatible with Windows Server 2012 R2, 2016 and
Windows 10.

Features
========

  Checksum offload
  ----------------
  The netvsc driver supports checksum offload as long as the
  Hyper-V host version does. Windows Server 2016 and Azure
  support checksum offload for TCP and UDP for both IPv4 and
  IPv6. Windows Server 2012 only supports checksum offload for TCP.

  Receive Side Scaling
  --------------------
  Hyper-V supports receive side scaling. For TCP, packets are
  distributed among available queues based on IP address and port
  number. Current versions of Hyper-V host, only distribute UDP
  packets based on the IP source and destination address.
  The port number is not used as part of the hash value for UDP.
  Fragmented IP packets are not distributed between queues;
  all fragmented packets arrive on the first channel.

  Generic Receive Offload, aka GRO
  --------------------------------
  The driver supports GRO and it is enabled by default. GRO coalesces
  like packets and significantly reduces CPU usage under heavy Rx
  load.

  SR-IOV support
  --------------
  Hyper-V supports SR-IOV as a hardware acceleration option. If SR-IOV
  is enabled in both the vSwitch and the guest configuration, then the
  Virtual Function (VF) device is passed to the guest as a PCI
  device. In this case, both a synthetic (netvsc) and VF device are
  visible in the guest OS and both NIC's have the same MAC address.

  The VF is enslaved by netvsc device.  The netvsc driver will transparently
  switch the data path to the VF when it is available and up.
  Network state (addresses, firewall, etc) should be applied only to the
  netvsc device; the slave device should not be accessed directly in
  most cases.  The exceptions are if some special queue discipline or
  flow direction is desired, these should be applied directly to the
  VF slave device.

  Receive Buffer
  --------------
  Packets are received into a receive area which is created when device
  is probed. The receive area is broken into MTU sized chunks and each may
  contain one or more packets. The number of receive sections may be changed
  via ethtool Rx ring parameters.

  There is a similar send buffer which is used to aggregate packets for sending.
  The send area is broken into chunks of 6144 bytes, each of section may
  contain one or more packets. The send buffer is an optimization, the driver
  will use slower method to handle very large packets or if the send buffer
  area is exhausted.