xref: /freebsd/share/man/man4/vtnet.4 (revision b1f9167f94059fd55c630891d359bcff987bd7eb)
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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 appreciate features, the
53.Nm
54driver supports TCP/UDP checksum offload for both transmit and receive,
55TCP segmentation offload (TSO), TCP large receive offload (LRO), and
56hardware VLAN tag stripping/insertion features, as well as a multicast
57hash filter, as 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 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