Run nested gamescope-session without root access (on vanilla NixOS)

[jefebisou]

Hi :) first of all thanks a lot for your work, it's really useful to be able to replicate and understand various SteamOS layers.

(too much context)

I've been using modules from Jovian-NixOS a lot in the past, on my regular AMD workstation. Now I'm gaming a bit less, and I don't feel comfortable running proprietary software (especially games) outside of a sandbox. I'm not a serious target for anyone but I'm trying to harden my system anyway, for the sake of it. Sooo I'm currently using Flatpak Steam (on top of NixOS), which is not the most sand-boxed thing ever, but still, it goes in the right direction compared to the traditional open-bar Linux desktop. And it works really well .. until you want the Steam Deck experience again. 🤓

I would be super interested in running gamescope-session (nested mode); and also be able to just install it / run it as a regular package with a regular user (as Nix's security model is naturally fine with a non-trusted user building random things and putting it in the store). Currently it's perfectly valid to do this:

$ nix build github:jovian-experiments/jovian-nixos#gamescope-session
$ ./result/lib/steamos/gamescope-session

.. and it does run! however it's obviously missing other global things from Jovian's NixOS modules / other SteamOS things. I would be happy to make this work (or something similar), do you have some hints for things I could do within the scope of a regular package? I was thinking of a bunch of systemd units in regular user mode aka. systemctl --user. 🤔

[K900]

What kind of global things are you looking for, and why?

[jefebisou]

@K900 I'm not looking for those, I'm exploring whether I could make the above 2 commands work on a fresh (graphical) NixOS system without touching /etc/nixos, and without resorting to sudo. 🙂

Basically what I'm describing is: Install GNOME NixOS, login as a regular user, open a terminal, run the above 2 commands, wait ... then "Steam Deck inside a window" pops up.

From what I understand, the above use-case is technically feasible, and I'm wondering if you have some tips or thoughts to help me achieve something similar.

[K900]

Then just running gamescope-session should already mostly work?

[jefebisou]

mmhh ok thanks, I saw a couple errors in gamescope-session's output, related to missing files in /etc for example, but maybe this is already mostly self-contained and I should just try to fill the gaps here and there with a few flags/config files, and maybe systemd/chroot is unnecessary :)

[K900]

It would be significantly easier to help you if you actually described the specific issues you're seeing, from the user perspective.