NAME

     vtnet — VirtIO Ethernet driver

SYNOPSIS

     To compile this driver into the kernel, place the following lines in your kernel
     configuration file:

           device vtnet

     Alternatively, to load the driver as a module at boot time, place the following line in
     loader.conf(5):

           if_vtnet_load="YES"

DESCRIPTION

     The vtnet device driver provides support for VirtIO Ethernet devices.

     If the hypervisor advertises the appreciate features, the vtnet driver supports TCP/UDP
     checksum offload for both transmit and receive, TCP segmentation offload (TSO), TCP large
     receive offload (LRO), hardware VLAN tag stripping/insertion features, a multicast hash
     filter, as well as Jumbo Frames (up to 9216 bytes), which can be configured via the
     interface MTU setting.  Selecting an MTU larger than 1500 bytes with the ifconfig(8) utility
     configures the adapter to receive and transmit Jumbo Frames.

     For more information on configuring this device, see ifconfig(8).

LOADER TUNABLES

     Tunables can be set at the loader(8) prompt before booting the kernel or stored in
     loader.conf(5).

     hw.vtnet.csum_disable

     hw.vtnet.X.csum_disable
             This tunable disables receive and send checksum offload.  The default value is 0.

     hw.vtnet.tso_disable

     hw.vtnet.X.tso_disable
             This tunable disables TSO.  The default value is 0.

     hw.vtnet.lro_disable

     hw.vtnet.X.lro_disable
             This tunable disables LRO.  The default value is 0.

     hw.vtnet.mq_disable

     hw.vtnet.X.mq_disable
             This tunable disables multiqueue.  The default value is 0.

     hw.vtnet.mq_max_pairs

     hw.vtnet.X.mq_max_pairs
             This tunable sets the maximum number of transmit and receive queue pairs.  Multiple
             queues are only supported when the Multiqueue feature is negotiated.  This driver
             supports a maximum of 8 queue pairs.  The number of queue pairs used is the lesser
             of the maximum supported by the driver and the hypervisor, the number of CPUs
             present in the guest, and this tunable if not zero.  The default value is 0.

SEE ALSO

     arp(4), netintro(4), ng_ether(4), virtio(4), vlan(4), ifconfig(8)

HISTORY

     The vtnet driver was written by Bryan Venteicher <bryanv@FreeBSD.org>.  It first appeared in
     FreeBSD 9.0.

CAVEATS

     The vtnet driver only supports LRO when the hypervisor advertises the mergeable buffer
     feature.