Installation guide

Chapter 11. KVM Para-virtualized Drivers

Note

To use the network device driver only, load the virtio, virtio_net and virtio_pci

modules. To use the block device driver only, load the virtio, virtio_ring, virtio_blk

and virtio_pci modules.

Modified initrd files

The virtio package modifies the initrd RAM disk file in the /boot directory. The original initrd file

is saved to /boot/initrd- kernel-version .img.virtio.orig. The original initrd file is

replaced with a new initrd RAM disk containing the virtio driver modules. The initrd RAM disk

is modified to allow the guest to boot from a storage device using the para-virtualized drivers.

To use a different initrd file, you must ensure that drivers are loaded with the sysinit script

(Loading the para-virtualized drivers with the sysinit script) or when creating new initrd RAM disk

(Adding the para-virtualized drivers to the initrd RAM disk).

Loading the para-virtualized drivers with the sysinit script

This procedure covers loading the para-virtualized driver modules during the boot sequence on a Red

Hat Enterprise Linux 3.9 or newer guest with the sysinit script. Note that the guest cannot use the

para-virtualized drivers for the default boot disk if the modules are loaded with the sysinit script.

The drivers must be loaded in the following order:

1. virtio

2. virtio_ring

3. virtio_blk

4. virtio_net

5. virtio_pci

Only order of virtio_net and virtio_blk can be change. If the drivers are loaded in a different

order, drivers will not work.

Configure the modules to . Locate the following section of the /etc/rc.d/rc.sysinit file.

if [ -f /etc/rc.modules ]; then

/etc/rc.modules

Append the following lines after that section:

if [ -f /etc/rc.modules ]; then

/etc/rc.modules

modprobe virtio

modprobe virtio_ring # Comment this out if you do not need block driver

modprobe virtio_blk # Comment this out if you do not need block driver

modprobe virtio_net # Comment this out if you do not need net driver