QEMU on Windows

Tags: qemu, virtualisation, windows

Contents

• Basic Setup
• Acceleration

This post goes through some basics of getting VMs running using QEMU on Windows.

Basic Setup

It’s easy enough to get QEMU running on Windows - simply find the QEMU download page and follow the link! https://www.qemu.org/download/#windows

For convenience, I add the QEMU installation dir to my PATH (search ‘Edit the systemd environment variables’), which is C:\Program Files\qemu for me (this is the directory containing the executables such as qemu-img).

The basic steps are then:

• Download a Linux ISO, e.g. from https://ubuntu.com/download/desktop
• Create a HDD file to install to: qemu-img create -f qcow2 hdd.qcow2 50G
• Run QEMU: qemu-system-x86_64 -cdrom ubuntu-22.04.1-desktop-amd64.iso -drive file=hdd.qcow2

The last step above should open up a window giving a graphical display for the VM, which will guide through steps to install from the ISO to the harddisk (hdd.qcow). Once the installation is completed, the VM can be shut down, and subsequently started without the ISO file, e.g. with qemu-system-x86_64 -drive file=hdd.qcow2.

Acceleration

On Linux KVM (a kernel virtualisation module) is generally used for acceleration. On Windows HAXM must be used, as detailed at https://www.qemu.org/2017/11/22/haxm-usage-windows/. You should see this listed as ‘hax’ if you run qemu-system-x86_64 -accel help. If you run qemu-system-x86_64 -accel hax it should indicate whether HAXM is correctly set up (likely not by default!).

As per https://github.com/intel/haxm/blob/master/docs/manual-windows.md#one-time-setup, Hyper-V must be disabled since it makes exclusive use of the VT-x virtualisation. This can be done by searching for ‘Turn Windows features on or off’, deselecting Hyper-V, and restarting.

Running systeminfo in Command Prompt should show a list of requirements under ‘Hyper-V Requirements’ at the bottom of the output. However, I found that it instead shows “A hypervisor has been detected. Features required for Hyper-V will not be displayed.”, which indicates Hyper-V has not been successfully disabled. As per the HAXM docs linked above, the fix was to run bcdedit /set hypervisorlaunchtype off from Command Prompt run as admin. Restart and check the output of systeminfo to confirm things are correctly set up.

HAXM can then be installed by downloading from their releases page, unzipping, and running the setup executable. This will check everything is set up correctly before installing.

If this all succeeds you can add -accel hax to your QEMU commands for your VMs to run much faster!