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.Dd August 29, 2026
.Dt VIRTIO 4
.Os
.Sh NAME
.Nm virtio
.Nd Para-virtualized I/O in a virtual machine
.Sh SYNOPSIS
.Ss Virtio Over MMIO
.Cd "virtio* at acpi?"
.Cd "virtio* at fdt?"
.Cd "virtio* at pv?"
.Ss Virtio Over PCI Bus
.Cd "virtio* at pci? dev ? function ?"
.Ss Virtio devices
.Cd "ld* at virtio?"
.Cd "vio9p* at virtio?"
.Cd "viocon* at virtio?"
.Cd "vioif* at virtio?"
.Cd "viogpu* at virtio?"
.Cd "viomb* at virtio?"
.Cd "viornd* at virtio?"
.Cd "vioscsi* at virtio?"
.Sh DESCRIPTION
The
.Nm
driver implements the VirtIO interface for efficient, standard and extensible
I/O between the hypervisor and the virtual machine.
.Pp
It supports VirtIO devices exposed over
.Xr pci 4
or over the MMIO transport.
.Pp
The MMIO transport can be used, for example, in embedded systems and microVMs.
Devices may be discovered via
.Xr acpi 4
or fdt, or specified through kernel command-line parameters using
.Xr pv 4 .
.Pp
The
.Nm
driver provides the core infrastructure to communicate with the hypervisor
and supports the following devices:
.Pp
.Bl -tag -width Xr -compact
.It Xr ld 4
A disk device.
.It Xr vio9p 4
A 9P front-end device.
.It Xr viocon 4
A console device.
.It Xr vioif 4
An Ethernet device.
.It Xr viogpu 4
A GPU device.
.It Xr viomb 4
A pseudo-device to release memory back to the hypervisor.
.It Xr viornd 4
An entropy source.
.It Xr vioscsi 4
A SCSI adapter.
.El
.Sh SEE ALSO
.Xr acpi 4 ,
.Xr ld 4 ,
.Xr pci 4 ,
.Xr pv 4 ,
.Xr vio9p 4 ,
.Xr viocon 4 ,
.Xr viogpu 4 ,
.Xr vioif 4 ,
.Xr viomb 4 ,
.Xr viornd 4 ,
.Xr vioscsi 4
.Pp
.Rs
.%A Rusty Russell, IBM Corporation
.%T Virtio PCI Card Specification
.%U http://ozlabs.org/~rusty/virtio-spec/
.Re
.Rs
.%T Virtual I/O Device (VIRTIO) Version 1.2
.%U https://docs.oasis-open.org/virtio/virtio/v1.2/virtio-v1.2.html
.Re
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 6.0 .
Support for attachment via
.Xr acpi 4
and via fdt was added in
.Nx 9.0 .
Support for attachment via
.Xr pv 4
was added in
.Nx 11.0 .