93 lines
3.1 KiB
Groff
93 lines
3.1 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 VIRTIO 4
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.Os
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.Sh NAME
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.Nm virtio
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.Nd VirtIO Device Support
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.Sh SYNOPSIS
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To compile VirtIO device support into the kernel, place the following lines
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in your kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device virtio"
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.Cd "device virtio_pci"
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.Ed
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.Pp
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Alternatively, to load VirtIO support as modules at boot time, place the
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following lines in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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virtio_load="YES"
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virtio_pci_load="YES"
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.Ed
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.Sh DESCRIPTION
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VirtIO is a specification for para-virtualized I/O in a virtual machine (VM).
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Traditionally, the hypervisor emulated real devices such as an Ethernet
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interface or disk controller to provide the VM with I/O.
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This emulation is often inefficient.
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.Pp
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VirtIO defines an interface for efficient I/O between the hypervisor and VM.
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The
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.Xr virtio 4
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module provides a shared memory transport called a virtqueue.
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The
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.Xr virtio_pci 4
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device driver represents an emulated PCI device that the hypervisor makes
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available to the VM.
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This device provides the probing, configuration, and
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interrupt notifications needed to interact with the hypervisor.
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.Fx
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supports the following VirtIO devices:
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.Bl -hang -offset indent -width xxxxxxxx
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.It Nm Ethernet
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An emulated Ethernet device is provided by the
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.Xr vtnet 4
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device driver.
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.It Nm Block
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An emulated disk controller is provided by the
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.Xr virtio_blk 4
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device driver.
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.It Nm Balloon
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A pseudo-device to allow the VM to release memory back to the hypervisor is
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provided by the
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.Xr virtio_balloon 4
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device driver.
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.El
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.Sh SEE ALSO
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.Xr virtio_balloon 4 ,
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.Xr virtio_blk 4 ,
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.Xr vtnet 4
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.Sh HISTORY
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Support for VirtIO first appeared in
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.Fx 9.0 .
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.Sh AUTHORS
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.An -nosplit
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.Fx
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support for VirtIO was first added by
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.An Bryan Venteicher Aq bryanv@daemoninthecloset.org .
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