Automatic installation of Windows drivers

Summary

The feature simplifies the installation of MS Windows on a VM when virtio disk and network drivers are used. oVirt provides a floppy with file Autounattend.xml which tells the installer where to find the necessary virtio drivers.

Motivation

The process of installing VM with MS Windows is complicated by the lack of virtio drivers on the installation media. If the user wants to use virtio disk and network during installation – which is suggested because of significant speed improvement – he has to perform some preparatory steps. The user has to manually load the virtio storage drivers and possibly also virtio network drivers from the floppy disk in the initial phase of installation. This process puts unnecessary burden on the user.

Automation

The installation process of MS Windows can be automated by providing removable media containing file called Autounattend.xml. The XML file allows automation of many aspects of the installation. From answers to dialog questions to disk partitioning to completely unattended installation.

In case of this feature we use it to tell Windows where it can find the necessary drivers. The installer will then load the drivers automatically and also installs them to the target OS. That way they are available during the installation as well as on the first boot of the new system.

How to use the feature

TBA (UX design is still in progress)

Details

First osinfo database will be modified to contain the directory with the drivers. By default, the directories correspond to the paths as seen on the floppy in virtio-win package.

Second, the auto-install floppy is created on the fly just before the VM is started. The floppy image specified in Run Once dialog is copied to the payload directory on VDSM and Autounattend.xml is injected onto it. The Autounattend.xml is created from the template by replacing the path to the drivers from osinfo. We cannot use single XML file because of bugs in drivers loading code in Windows.