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.\" $FreeBSD$ 26.\" 27.Dd January 22, 2012 28.Dt VTNET 4 29.Os 30.Sh NAME 31.Nm vtnet 32.Nd VirtIO Ethernet driver 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following lines in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device vtnet" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45if_vtnet_load="YES" 46.Ed 47.Sh DESCRIPTION 48The 49.Nm 50device driver provides support for VirtIO Ethernet devices. 51.Pp 52If the hypervisor advertises the appropriate features, the 53.Nm 54driver supports TCP/UDP checksum offload for both transmit and receive, 55TCP segmentation offload (TSO), TCP large receive offload (LRO), 56hardware VLAN tag stripping/insertion features, a multicast hash filter, 57as well as Jumbo Frames (up to 9216 bytes), which can be 58configured via the interface MTU setting. 59Selecting an MTU larger than 1500 bytes with the 60.Xr ifconfig 8 61utility configures the adapter to receive and transmit Jumbo Frames. 62.Pp 63For more information on configuring this device, see 64.Xr ifconfig 8 . 65.Sh LOADER TUNABLES 66Tunables can be set at the 67.Xr loader 8 68prompt before booting the kernel or stored in 69.Xr loader.conf 5 . 70.Bl -tag -width "xxxxxx" 71.It Va hw.vtnet.csum_disable 72.It Va hw.vtnet. Ns Ar X Ns Va .csum_disable 73This tunable disables receive and send checksum offload. 74The default value is 0. 75.It Va hw.vtnet.tso_disable 76.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable 77This tunable disables TSO. 78The default value is 0. 79.It Va hw.vtnet.lro_disable 80.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable 81This tunable disables LRO. 82The default value is 0. 83.It Va hw.vtnet.mq_disable 84.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable 85This tunable disables multiqueue. 86The default value is 0. 87.It Va hw.vtnet.mq_max_pairs 88.It Va hw.vtnet. Ns Ar X Ns Va .mq_max_pairs 89This tunable sets the maximum number of transmit and receive queue pairs. 90Multiple queues are only supported when the Multiqueue feature is negotiated. 91This driver supports a maximum of 8 queue pairs. 92The number of queue pairs used is the lesser of the maximum supported by the 93driver and the hypervisor, the number of CPUs present in the guest, and this 94tunable if not zero. 95The default value is 0. 96.El 97.Sh SEE ALSO 98.Xr arp 4 , 99.Xr netintro 4 , 100.Xr ng_ether 4 , 101.Xr virtio 4 , 102.Xr vlan 4 , 103.Xr ifconfig 8 104.Sh HISTORY 105The 106.Nm 107driver was written by 108.An Bryan Venteicher Aq Mt bryanv@FreeBSD.org . 109It first appeared in 110.Fx 9.0 . 111.Sh CAVEATS 112The 113.Nm 114driver only supports LRO when the hypervisor advertises the 115mergeable buffer feature. 116