wiki/virt/vm/display.md

title	description	published	date	tags	editor	dateCreated
Display	How to access a virtual machine's display	true	2023-05-20T20:45:37.373Z		markdown	2022-07-31T09:22:05.854Z

Display

A virtual display can be attached to a virtual machine, letting a user see the content of it. It is a must-have for non-headless scenario.

Summary

Official ressource for libvirt-compatible displays, including various XML examples

{.is-info}

• to-be done. Add table here.

Specific displays

VNC

• to-be done

Spice

• to-be done

SDL

The Simple DirectMedia Layer is a local-only low-latency display.

SDL is currently only avalable with virtual machines created using the QEMU/KVM User Session mode {.is-info}

As of now, this method is not compatible with Wayland {.is-info}

Mouse grab does not currently work in SDL {.is-warning}

• The display resolution of your guest display should not exceed that of your physical screen.

SELinux configuration

By default, SELinux will block access to X Windows Server for the virtualization stack. An exception has to be set.

• Set new rule

sudo setsebool -P virt_use_xserver 1

• Do some magic trick

sudo ausearch -c 'qemu-system-x86' --raw | audit2allow -M my-qemusystemx86
k

• And another one

sudo semodule -X 300 -i my-qemusystemx86.pp

XML SDL example

• Example of an XML SDL configuration, with OpenGL enabled. This example requires a 3D-capable graphic card to be attached to the guest computer, such as virtio-gpu or vfio-pci.

<graphics type="sdl" display=":0" xauth="/root/.Xauthority" fullscreen="yes">
  <gl enable="yes"/>
</graphics>

You can identify your display using the following command: echo $DISPLAY {.is-info}

D-Bus

The D-Bus display is only available since version 7.4.0 of libvirt {.is-warning}

D-Bus is a Desktop-oriented middleware that can be used to create a display for a virtual machine.

Detailed presentation on D-Bus {.is-info}

• Export and enable a video backend, add support for OpenGL and peer-to-peer connection:

Does not display at the moment.

SELinux needs to be disabled.

<graphics type="dbus">
  <gl enable="yes"/>
</graphics>

It will look like that when launched:

<graphics type="dbus" address="unix:path=/run/user/1000/libvirt/qemu/run/dbus/8-user-d-bus-dbus.sock">
  <gl enable="yes" rendernode="/dev/dri/renderD128"/>
</graphics>

• Export and enable an audio backend:

<graphics type="dbus">
  <audio id="1">
</graphics>

Xephyr

• to-be done

WebRTC

• to-be done

Looking Glass

• to-be done

virtio-wayland

• to-be done

egl-headless

• to-be done