wiki/virt/vm/display.md

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Display How to access a virtual machine's display true 2023-05-20T21:29:47.985Z markdown 2022-07-31T09:22:05.854Z

Display

A virtual display can be attached to a virtual machine. It is a must-have for non-headless scenarios.

Display types

SDL display

The Simple DirectMedia Layer (SDL)-powered display is a local-only low-latency display.

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

Mouse grab does not currently work with the SDL display {.is-warning}

The display resolution of your guest display should not exceed that of your physical screen {.is-info}

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

SDL XML configuration

  • The default display can be identified using echo $DISPLAY.
$ echo $DISPLAY
:0

The same applies to xauth. On Wayland, it would look like that.

$ echo $XAUTHORITY
/run/user/1000/.mutter-Xwaylandauth.ARIY51
  • 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.
<graphics type="sdl" display=":0" xauth="/run/user/1000/.mutter-Xwaylandauth.ARIY51" fullscreen="yes">
  <gl enable="yes"/>
</graphics>

The fullscreen attribute is not honored at the moment {.is-warning}

D-Bus display

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

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

Resources


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