xml-definition-for-domains/README.md
2023-05-20 12:55:21 +02:00

4.0 KiB

Optimized, libvirt-compatible definitions for common OS

Goal

This repository's goal is to maintain definitions that are tuned for running modern, GUI-driven guest operating systems (OS), easing their installation on hosts that leverage KVM, such as Phyllome OS.

Usage

Requirements

It is expected that libvirt and other dependencies such as QEMU or the Cloud Hypervisor are already installed and correctly configured.

  • At least QEMU emulator version 7.0.0
  • At least libvirt 8.6.0

How to use it

  • Clone this repository locally

There are two kinds of definition for QEMU: session-driven virtual machines, and system-driven virtual machines. System-driven virtual machines are running with higher privileges. If one intend to share a physical device with a virtual machine using vfio passthrough, this is the definition to use. More information here.

Session-driven QEMU virtual machines

  • Navigate to the session directory
  • Choose your target OS of choice and, as a normal user, use the following virsh command to define a virtual machine:
$ virsh define linux.xml
Domain 'Linux' defined from linux.xml
  • List the newly-created virtual machine
$ virsh list --all
 Id   Name    State
------------------------
 -    Linux   shut off
  • Destroy it

virsh undefine Linux Domain 'Linux' has been undefined

System-driven virtual machines

  • Navigate to the system directory
  • Choose your target OS of choice and, as a root user, use the following virsh command to define a virtual machine:
# virsh define linux.xml

Status

Linux Windows
Chipset Q35 Q35
Platform Firmware OVMF OVMF
Spice display Yes, with 3D Yes, without 3D
virtio-gpu Yes, with 3D Yes, without 3D
virtio-blk Not applicable Not applicable
virtio-scsi Yes Yes
virtio-fs Yes, for System-driven VM Yes
virtio-net Yes Yes
virtio-keyboard Yes Yes
virtio-tablet Yes Yes

More information here on the status for virtio support on guest operating systems.

Context

Libvirt is the most popular virtualization library on Linux, and it is central to Phyllome OS.

Libvirt uses an XML file to store the definition of a virtual machine, including its firmware (e.g. BIOS or UEFI-based), the size of its memory, the nature of a particular device (e.g. virtio or emulated hardware), etc.

Why

The reference Domain XML format webpage, which is almost 100 pages long, lists most of the accepted parameters that can be used to define a virtual machine.

Picking the most optimized parameters for running a particular guest OS is a complicated task. This project intends to find the best parameters for the most popular OS.

Assomptions

The best parameters are defined as parameters that are:

  • Performance-oriented, providing good out-of-the-box performance.
  • Relatively host-agnostic, so that a virtual machine could be migrated to another host.
  • Modern, leveraging as many paravirtualized devices (a.k.a virtio devices) the target guest OS can support, with the intend to become usable with modern virtualization solution such as the Cloud Hypervisor.

Resources