Manual Pages  — VIRTIO

virtio – VirtIO Device Support

SYNOPSIS DESCRIPTION SEE ALSO HISTORY AUTHORS

VirtIO is a specification for para-virtualized I/O in a virtual machine (VM). Traditionally, the hypervisor emulated real devices such as an Ethernet interface or disk controller to provide the VM with I/O. This emulation is often inefficient.

VirtIO defines an interface for efficient I/O between the hypervisor and VM. The virtio module provides a shared memory transport called a virtqueue. The virtio_pci device driver represents an emulated PCI device that the hypervisor makes available to the VM. This device provides the probing, configuration, and interrupt notifications needed to interact with the hypervisor. FreeBSD supports the following VirtIO devices:

Ethernet	An emulated Ethernet device is provided by the vtnet(4) device driver.
Block	An emulated disk controller is provided by the virtio_blk(4) device driver.
Console	Provided by the virtio_console(4) driver.
Entropy	Provided by the virtio_random(4) driver.
Balloon	A pseudo-device to allow the VM to release memory back to the hypervisor is provided by the virtio_balloon(4) device driver.
SCSI	An emulated SCSI HBA is provided by the virtio_scsi(4) device driver.

Support for VirtIO first appeared in FreeBSD 9.0 .

FreeBSD support for VirtIO was first added by Bryan Venteicher <Mt bryanv@FreeBSD.org>.