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VTNET(4)              DragonFly 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 appreciate features, the vtnet driver
     supports TCP/UDP checksum offload for both transmit and receive, TCP
     segmentation offload (TSO), TCP large receive offload (LRO), and hardware
     VLAN tag stripping/insertion features, as well as 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
             This tunable disables receive and send checksum offload.  The
             default value is 0.

     hw.vtnet.tso_disable
             This tunable disables TSO.  The default value is 1.

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


SEE ALSO

     arp(4), ifmedia(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.  The receive checksum offload feature of the
     vtnet driver is masked for now, because of missing support for receive
     checksum offload in IPv6 packet handling in DragonFly.

DragonFly 4.9                  October 17, 2017                  DragonFly 4.9

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