VTNET(4)               FreeBSD Kernel Interfaces Manual               VTNET(4)

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 appropriate 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.

FreeBSD 13.1-RELEASE-p6        January 22, 2012        FreeBSD 13.1-RELEASE-p6