Installation guide

Chapter 13. KVM Para-virtualized Drivers
Para-virtualized drivers are available for virtualized Windows guests running on KVM hosts. These
para-virtualized drivers are included in the virtio-win package. The virtio-win package supports block
(storage) devices and network interface controllers.
As with the KVM module, the virtio-win drivers package is only available on hosts running Red Hat
Enterprise Linux 5.4 and newer.
Para-virtualized drivers enhance the performance of fully virtualized guests. With the para-virtualized
drivers guest I/O latency decreases and throughput increases to near bare-metal levels. It is
recommended to use the para-virtualized drivers for fully virtualized guests running I/O heavy tasks
and applications.
The KVM para-virtualized drivers are automatically loaded and installed on the following versions of
Red Hat Enterprise Linux:
Red Hat Enterprise Linux 4.8 and newer
Red Hat Enterprise Linux 5.3 and newer
Red Hat Enterprise Linux 6.
Those Red Hat Enterprise Linux versions detect and install the drivers so additional installation steps
are not required.
Note
PCI devices are limited by the virtualized system architecture. Out of the 32 available PCI
devices for a guest 4 are not removable. This means there are up to 28 PCI slots available for
additional devices per guest. Each PCI device can have up to 8 functions; some PCI devices
have multiple functions and only use one slot. Para-virtualized network, para-virtualized disk
devices, or other PCI devices using VT-d all use slots or functions. The exact number of
devices available is difficult to calculate due to the number of available devices. Each guest
can use up to 32 PCI devices with each device having up to 8 functions.
The following Microsoft Windows versions have supported KVM para-virtualized drivers:
Windows XP (32-bit only)
Windows Server 2003 (32-bit and 64-bit versions)
Windows Server 2008 (32-bit and 64-bit versions)
Windows 7 (32-bit and 64-bit versions)
13.1. Inst alling t he KVM Windows para-virt ualized drivers
This section covers the installation process for the KVM Windows para-virtualized drivers. The KVM
para-virtualized drivers can be loaded during the Windows installation or installed after the guest is
installed.
You can install the para-virtualized drivers on your guest by one of the following methods:
hosting the installation files on a network accessible to the guest,
⁠Chapt er 1 3. KVM Para- virt ualized Drivers
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