RHEL 6 Virtualization - 11.2. Installing the KVM Windows para-virtualized drivers

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11.2. Installing the KVM Windows para-virtualized 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,
using a virtualized CD-ROM device of the driver installation disk .iso file, or
using a virtualized floppy device to install the drivers during boot time (for Windows guests).

This guide describes installation from the para-virtualized installer disk as a virtualized CD-ROM device.

Download the drivers

The virtio-win package contains the para-virtualized block and network drivers for all supported Windows guests.

Download the virtio-win package with the yum command.
```
# yum install virtio-win
```
The drivers are also from Microsoft (windowsservercatalog.com). Note that the Red Hat Enterprise Virtualization Hypervisor and Red Hat Enterprise Linux are created on the same code base so the drivers for the same version (for example, Red Hat Enterprise Virtualization Hypervisor 2.2 and Red Hat Enterprise Linux 5.5) are supported for both environments.

The virtio-win package installs a CD-ROM image, virtio-win.iso, in the /usr/share/virtio-win/ directory.
Install the para-virtualized drivers

It is recommended to install the drivers on the guest before attaching or modifying a device to use the para-virtualized drivers.

For block devices storing root file systems or other block devices required for booting the guest, the drivers must be installed before the device is modified. If the drivers are not installed on the guest and the driver is set to the virtio driver the guest will not boot.

11.2.1. Installing the drivers on an installed Windows guest

This procedure covers installing the para-virtualized drivers with a virtualized CD-ROM after Windows is installed.

Follow Procedure 11.1, “Installing from the driver CD-ROM image with virt-manager” to add a CD-ROM image with virt-manager and then install the drivers.

Procedure 11.1. Installing from the driver CD-ROM image with virt-manager

Open virt-manager and the guest

Open virt-manager, select your virtualized guest from the list by double clicking the guest name.
Open the hardware window

Click the blue Information button at the top to view guest details. Then click the Add Hardware button at the bottom of the window.
Select the device type

This opens a wizard for adding the new device. Select Storage from the dropdown menu.

Click the Forward button to proceed.
Select the ISO file

Select Select managed or other existing storage and set the file location of the para-virtualized drivers .iso image file. The default location for the latest version of the drivers is /usr/share/virtio-win/virtio-win.iso.

Change the Device type to IDE cdrom and click the Forward button to proceed.
Finish adding virtual hardware

Press the Finish button to complete the wizard.
Reboot

Reboot or start the guest to begin using the driver disc. Virtualized IDE devices require a restart to for the guest to recognize the new device.

Once the CD-ROM with the drivers is attached and the guest has started, proceed with Procedure 11.2, “Windows installation”.

Procedure 11.2. Windows installation

Open My Computer

On the Windows guest, open My Computer and select the CD-ROM drive.
Select the correct installation files

There are four files available on the disc. Select the drivers you require for your guest's architecture:
- the para-virtualized block device driver (RHEV-Block.msi for 32-bit guests or RHEV-Block64.msi for 64-bit guests),
- the para-virtualized network device driver (RHEV-Network.msi for 32-bit guests or RHEV-Block64.msi for 64-bit guests),
- or both the block and network device drivers.
Double click the installation files to install the drivers.
Install the block device driver
1. Start the block device driver installation
  
  Double click RHEV-Block.msi or RHEV-Block64.msi.
  
  Press Install to continue.
2. Confirm the exception
  
  Windows may prompt for a security exception.
  
  Press Yes if it is correct.
3. Finish
  
  Press Finish to complete the installation.
Install the network device driver
1. Start the network device driver installation
  
  Double click RHEV-Network.msi or RHEV-Network64.msi.
  
  Press Next to continue.
2. Performance setting
  
  This screen configures advanced TCP settings for the network driver. TCP timestamps and TCP window scaling can be enabled or disabled. The default is, 1, for window scaling to be enabled.
  
  TCP window scaling is covered by IETF RFC 1323. The RFC defines a method of increasing the receive window size to a size greater than the default maximum of 65,535 bytes up to a new maximum of 1 gigabyte (1,073,741,824 bytes). TCP window scaling allows networks to transfer at closer to theoretical network bandwidth limits. Larger receive windows may not be supported by some networking hardware or operating systems.
  
  TCP timestamps are also defined by IETF RFC 1323. TCP timestamps are used to better calculate Return Travel Time estimates by embedding timing information is embedded in packets. TCP timestamps help the system to adapt to changing traffic levels and avoid congestion issues on busy networks.
  
  Value Action
  
  0 Disable TCP timestamps and window scaling.
  
  1 Enable TCP window scaling.
  
  2 Enable TCP timestamps.
  
  3 Enable TCP timestamps and window scaling.
  
  Press Next to continue.
3. Confirm the exception
  
  Windows may prompt for a security exception.
  
  Press Yes if it is correct.
4. Finish
  
  Press Finish to complete the installation.
Reboot

Reboot the guest to complete the driver installation.

Change an existing device to use the para-virtualized drivers (Section 11.3, “Using KVM para-virtualized drivers for existing devices”) or install a new device using the para-virtualized drivers (Section 11.4, “Using KVM para-virtualized drivers for new devices”).