| | 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: head/share/man/man4/virtio.4 273515 2014-10-23 04:47:32Z bryanv $ |
| | 26 | .\" |
| | 27 | .Dd October 26, 2018 |
| | 28 | .Dt VIRTIO 4 |
| | 29 | .Os |
| | 30 | .Sh NAME |
| | 31 | .Nm virtio |
| | 32 | .Nd VirtIO Device Support |
| | 33 | .Sh SYNOPSIS |
| | 34 | To compile VirtIO device support into the kernel, place the following lines |
| | 35 | in your kernel configuration file: |
| | 36 | .Bd -ragged -offset indent |
| | 37 | .Cd "device virtio" |
| | 38 | .Ed |
| | 39 | .Pp |
| | 40 | Alternatively, to load VirtIO support as modules at boot time, place the |
| | 41 | following lines in |
| | 42 | .Xr loader.conf 5 : |
| | 43 | .Bd -literal -offset indent |
| | 44 | virtio_pci_load="YES" |
| | 45 | .Ed |
| | 46 | .Sh DESCRIPTION |
| | 47 | VirtIO is a specification for para-virtualized I/O in a virtual machine (VM). |
| | 48 | Traditionally, the hypervisor emulated real devices such as an Ethernet |
| | 49 | interface or disk controller to provide the VM with I/O. |
| | 50 | This emulation is often inefficient. |
| | 51 | .Pp |
| | 52 | VirtIO defines an interface for efficient I/O between the hypervisor and VM. |
| | 53 | The |
| | 54 | .Nm |
| | 55 | module provides a shared memory transport called a virtqueue. |
| | 56 | The |
| | 57 | .Nm virtio_pci |
| | 58 | device driver represents an emulated PCI device that the hypervisor makes |
| | 59 | available to the VM. |
| | 60 | This device provides the probing, configuration, and |
| | 61 | interrupt notifications needed to interact with the hypervisor. |
| | 62 | .Dx |
| | 63 | supports the following VirtIO devices: |
| | 64 | .Bl -hang -offset indent -width xxxxxxxx |
| | 65 | .It Nm Ethernet |
| | 66 | An emulated Ethernet device is provided by the |
| | 67 | .Xr vtnet 4 |
| | 68 | device driver. |
| | 69 | .It Nm Block |
| | 70 | An emulated disk controller is provided by the |
| | 71 | .Xr virtio_blk 4 |
| | 72 | device driver. |
| | 73 | .It Nm SCSI |
| | 74 | An emulated SCSI HBA is provided by the |
| | 75 | .Xr virtio_scsi 4 |
| | 76 | device driver. |
| | 77 | .It Nm Balloon |
| | 78 | A pseudo-device to allow the VM to release memory back to the hypervisor is |
| | 79 | provided by the |
| | 80 | .Xr virtio_balloon 4 |
| | 81 | device driver. |
| | 82 | .El |
| | 83 | .Sh LOADER TUNABLES |
| | 84 | Tunables can be set at the |
| | 85 | .Xr loader 8 |
| | 86 | prompt before booting the kernel or stored in |
| | 87 | .Xr loader.conf 5 . |
| | 88 | .Bl -tag -width "xxxxxx" |
| | 89 | .It Va hw.virtio.pci.disable_msix |
| | 90 | This tunable disables MSI-X interrupt usage. |
| | 91 | The default value is 0 (use MSI-X interrupts if available). |
| | 92 | .El |
| | 93 | .Sh SEE ALSO |
| | 94 | .Xr virtio_balloon 4 , |
| | 95 | .Xr virtio_blk 4 , |
| | 96 | .\".Xr virtio_console 4 , |
| | 97 | .Xr virtio_random 4 , |
| | 98 | .Xr virtio_scsi 4 , |
| | 99 | .Xr vtnet 4 |
| | 100 | .Sh HISTORY |
| | 101 | Support for VirtIO first appeared in |
| | 102 | .Fx 9.0 . |
| | 103 | .Sh AUTHORS |
| | 104 | .An -nosplit |
| | 105 | .Fx |
| | 106 | support for VirtIO was first added by |
| | 107 | .An Bryan Venteicher Aq Mt bryanv@FreeBSD.org . |
| | 108 | .Pp |
| | 109 | .Dx support for Virtio Memory Balloon adapted by |
| | 110 | .An Diederik de Groot Aq Mt info@talon.nl . |
projects / dragonfly.git / blame_incremental