NAME
vtnet —
VirtIO Ethernet driver
SYNOPSIS
To compile this driver into the kernel, place the following lines in your kernel configuration file:
device vtnetAlternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):
if_vtnet_load="YES"
DESCRIPTION
Thevtnet 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.