116 lines
3.9 KiB
Groff
116 lines
3.9 KiB
Groff
.\" Copyright (c) 2011 Bryan Venteicher
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 22, 2012
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.Dt VTNET 4
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.Os
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.Sh NAME
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.Nm vtnet
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.Nd VirtIO Ethernet driver
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following lines in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device vtnet"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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if_vtnet_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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device driver provides support for VirtIO Ethernet devices.
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.Pp
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If the hypervisor advertises the appreciate features, the
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.Nm
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driver supports TCP/UDP checksum offload for both transmit and receive,
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TCP segmentation offload (TSO), TCP large receive offload (LRO), and
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hardware VLAN tag stripping/insertion features, as well as a multicast
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hash filter, as well as Jumbo Frames (up to 9216 bytes), which can be
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configured via the interface MTU setting.
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Selecting an MTU larger than 1500 bytes with the
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.Xr ifconfig 8
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utility configures the adapter to receive and transmit Jumbo Frames.
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.Pp
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For more information on configuring this device, see
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.Xr ifconfig 8 .
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.Sh LOADER TUNABLES
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Tunables can be set at the
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.Xr loader 8
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prompt before booting the kernel or stored in
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.Xr loader.conf 5 .
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.Bl -tag -width "xxxxxx"
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.It Va hw.vtnet.csum_disable
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.It Va hw.vtnet. Ns Ar X Ns Va .csum_disable
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This tunable disables receive and send checksum offload.
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The default value is 0.
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.It Va hw.vtnet.tso_disable
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.It Va hw.vtnet. Ns Ar X Ns Va .tso_disable
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This tunable disables TSO.
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The default value is 0.
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.It Va hw.vtnet.lro_disable
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.It Va hw.vtnet. Ns Ar X Ns Va .lro_disable
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This tunable disables LRO.
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The default value is 0.
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.It Va hw.vtnet.mq_disable
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.It Va hw.vtnet. Ns Ar X Ns Va .mq_disable
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This tunable disables multiqueue.
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The default value is 0.
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.It Va hw.vtnet.mq_max_pairs
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.It Va hw.vtnet. Ns Ar X Ns Va .mq_max_pairs
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This tunable sets the maximum number of transmit and receive queue pairs.
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Multiple queues are only supported when the Multiqueue feature is negotiated.
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This driver supports a maximum of 8 queue pairs.
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The number of queue pairs used is the lesser of the maximum supported by the
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driver and the hypervisor, the number of CPUs present in the guest, and this
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tunable if not zero.
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The default value is 0.
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.El
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.Sh SEE ALSO
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.Xr arp 4 ,
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.Xr netintro 4 ,
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.Xr ng_ether 4 ,
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.Xr virtio 4 ,
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.Xr vlan 4 ,
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.Xr ifconfig 8
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.Sh HISTORY
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The
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.Nm
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driver was written by
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.An Bryan Venteicher Aq bryanv@FreeBSD.org .
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It first appeared in
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.Fx 9.0 .
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.Sh CAVEATS
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The
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.Nm
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driver only supports LRO when the hypervisor advertises the
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mergeable buffer feature.
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