VIRTIO(4)						   BSD Kernel Interfaces Manual 						 VIRTIO(4)

NAME

     virtio -- VirtIO Device Support

SYNOPSIS

     To compile VirtIO device support into the kernel, place the following lines in your kernel configuration file:

	   device virtio
	   device virtio_pci

     Alternatively, to load VirtIO support as modules at boot time, place the following lines in loader.conf(5):

	   virtio_load="YES"
	   virtio_pci_load="YES"

DESCRIPTION

     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 pro-
     vides 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.

	   SCSI      An emulated SCSI HBA is provided by the virtio_scsi(4) device 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.

SEE ALSO

     virtio_balloon(4), virtio_blk(4), virtio_console(4), virtio_scsi(4), vtnet(4)

HISTORY

     Support for VirtIO first appeared in FreeBSD 9.0.

AUTHORS

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

BSD
								 January 22, 2012							       BSD