virtio — VirtIO Device Support

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

Debian                                          January 22, 2012                                       VIRTIO(4)

       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.

             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.

       Support for VirtIO first appeared in FreeBSD 9.0.

       virtio — VirtIO Device Support

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

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

             devicevirtiodevicevirtio_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"