1.\" Copyright (c) 2011 Bryan Venteicher 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.Dd January 22, 2012 26.Dt VTNET 4 27.Os 28.Sh NAME 29.Nm vtnet 30.Nd VirtIO Ethernet driver 31.Sh SYNOPSIS 32To compile this driver into the kernel, 33place the following lines in your 34kernel configuration file: 35.Bd -ragged -offset indent 36.Cd "device vtnet" 37.Ed 38.Pp 39Alternatively, to load the driver as a 40module at boot time, place the following line in 41.Xr loader.conf 5 : 42.Bd -literal -offset indent 43if_vtnet_load="YES" 44.Ed 45.Sh DESCRIPTION 46The 47.Nm 48device driver provides support for VirtIO Ethernet devices. 49.Pp 50If the hypervisor advertises the appropriate features, the 51.Nm 52driver supports TCP/UDP checksum offload for both transmit and receive, 53TCP segmentation offload (TSO), TCP large receive offload (LRO), 54hardware VLAN tag stripping/insertion features, a multicast hash filter, 55as well as Jumbo Frames (up to 9216 bytes), which can be 56configured via the interface MTU setting. 57Selecting an MTU larger than 1500 bytes with the 58.Xr ifconfig 8 59utility configures the adapter to receive and transmit Jumbo Frames. 60.Pp 61For more information on configuring this device, see 62.Xr ifconfig 8 . 63.Sh LOADER TUNABLES 64Tunables can be set at the 65.Xr loader 8 66prompt before booting the kernel or stored in 67.Xr loader.conf 5 . 68.Bl -tag -width "xxxxxx" 69.It Va hw.vtnet.csum_disable 70.It Va hw.vtnet. Ns Ar X Ns Va .csum_disable 71This tunable disables receive and send checksum offload. 72The default value is 0. 73.It Va hw.vtnet.tso_disable 74.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable 75This tunable disables TSO. 76The default value is 0. 77.It Va hw.vtnet.lro_disable 78.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable 79This tunable disables LRO. 80The default value is 0. 81.It Va hw.vtnet.mq_disable 82.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable 83This tunable disables multiqueue. 84The default value is 0. 85.It Va hw.vtnet.mq_max_pairs 86.It Va hw.vtnet. Ns Ar X Ns Va .mq_max_pairs 87This tunable sets the maximum number of transmit and receive queue pairs. 88Multiple queues are only supported when the Multiqueue feature is negotiated. 89This driver supports a maximum of 8 queue pairs. 90The number of queue pairs used is the lesser of the maximum supported by the 91driver and the hypervisor, the number of CPUs present in the guest, and this 92tunable if not zero. 93The default value is 0. 94.El 95.Sh SEE ALSO 96.Xr arp 4 , 97.Xr netintro 4 , 98.Xr ng_ether 4 , 99.Xr virtio 4 , 100.Xr vlan 4 , 101.Xr ifconfig 8 102.Sh HISTORY 103The 104.Nm 105driver was written by 106.An Bryan Venteicher Aq Mt bryanv@FreeBSD.org . 107It first appeared in 108.Fx 9.0 . 109.Sh CAVEATS 110The 111.Nm 112driver only supports LRO when the hypervisor advertises the 113mergeable buffer feature. 114