Headless output

[robbins]

Does Niri have the ability to create headless outputs that aren't tied to any physical monitor? e.g. for programs like Moonlight/Sunshine?

e.g. https://wiki.archlinux.org/title/Sway#Create_headless_outputs

[YaLTeR]

Not at the moment.

[djmaze]

Not only for that, it is also needed for virtual desktops in VR / MR (which I am planning to do in the future). People reported successfully using headless outputs in Hyprland for use in the Immersed virtual desktop environment.

I have no deeper knowledge about this topic, but this sounds to me like the used smithay toolkit already somewhat supports these kind of usecases: Smithay/smithay#287

[YaLTeR]

I don't think anything is missing on the Smithay side for headless outputs.

[djmaze]

Talking about immersed, I just tried running it (on NixOS). On sway it works, but on niri it fails to start, outputting this message:

listener function for opcode 2 of wl_output is NULL

What could be the reason? Is this maybe a client problem as similarly reported here?

[djmaze]

Ah yes, client problem, just found this: pop-os/cosmic-epoch#1137

[FlyingWombat]

If you make support for headless output, please consider including a way to detach an existing session from its display and make it headless. A use case for this is starting a VM with VFIO gpu passthrough, without having to kill the user session.

[YaLTeR]

Interesting use case, could you link some more info about it?

[Quackdoc]

I have found a usecase for headless, I have found myself wanting to test niri on all sorts of different interaction methods and one of the more convenient ways of doing this is using streaming solutions such as sunshine + moonlight.

The goal would be to create a headless session at whatever output is desired, then stream that to whatever interface I am testing on. This isn't the nicest solution in the world, but it should work fine.