nixos/monado: init

[Scrumplex]

Description of changes

Closes #275107

This module ensures that we have a monado.service that has CAP_SYS_NICE to utilize asynchronous reprojection. (See #217119) for details about asynchronous reprojection)

This effectively shadows the unit files packaged in monado. Maybe it is desirable to remove those from the packages.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[Atemu]

Untested but diff looks pretty good to me.

A couple things:

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/3097

[loco-choco]

It would be nice if the service would also set a symlink for ~/.config/openxr/1/active_runtime.json from share/openxr/1/openxr_monado.json. Correct me if I am wrong, but I feel like the setupHook should help with this, but for some reason, if I have the monado pkg in environment.systemPackages, openxr_runtime_list can't find the runtime file.

[Scrumplex]

It would be nice if the service would also set a symlink for ~/.config/openxr/1/active_runtime.json from share/openxr/1/openxr_monado.json. Correct me if I am wrong, but I feel like the setupHook should help with this, but for some reason, if I have the monado pkg in environment.systemPackages, openxr_runtime_list can't find the runtime file.

The setupHook of monado does not affect packages you install using environment.systemPackages. But I could add an option to this module to make Monado the default runtime on the system. Note that that option might not work if for example SteamVR defines a default runtime in ~/.config/openxr

[Scrumplex]

I tried to make the test more precise by querying the active OpenXR runtime using openxr_runtime_list from openxr-loader, but for some reason I couldn't get it to detect Monado's socket properly

Edit: Got it working! :D

[Atemu]

Had to enable the user socket manually after switch (a general NixOS issue I believe) and explicitly declare the XR runtime but was then able to run xrgears:

XR_RUNTIME_JSON=/run/current-system/sw/share/openxr/1/openxr_monado.json xrgears

A few nits, questions and remarks.

[Atemu]

Hold on, just hit this:

Dec 18 20:45:28 HEPHAISTOS systemd[2711]: monado.service: Main process exited, code=exited, status=255/EXCEPTION
Dec 18 20:45:28 HEPHAISTOS systemd[2711]: monado.service: Failed with result 'exit-code'.
Dec 18 20:45:28 HEPHAISTOS systemd[2711]: monado.service: Start request repeated too quickly.
Dec 18 20:45:28 HEPHAISTOS systemd[2711]: monado.service: Failed with result 'exit-code'.
Dec 18 20:45:28 HEPHAISTOS systemd[2711]: Failed to start Monado XR runtime service module.
Dec 18 20:45:28 HEPHAISTOS systemd[2711]: monado.socket: Failed with result 'service-start-limit-hit'.

The socket should probably be configured to get back up in this case.

[Scrumplex]

The security wrapper for CAP_SYS_NICE is now configurable. Someone told me that they had issues running Monado with it enabled on an NVIDIA system

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/3416

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nixpkgs-xr-nightly-packages-for-xr-ar-vr-tools-and-apps/40083/1

[Atemu]

I had intended to test this but had not found the time yet. If I haven't tested in a week, please ping me again and I'll just merge because the diff does LGTM.

[jsw08]

Hey would it be possible for you to add an option to compile monado with basalt for wmr controller tracking? I tried to package it myself and failed.

[Scrumplex]

I could look into it, but it wouldn't be in scope for this PR I think

[jsw08]

I could look into it, but it wouldn't be in scope for this PR I think

Okay, thank you. I'll look into it a bit more myself.

[Atemu]

Amazing work, thank you so much!

[loco-choco]

I could look into it, but it wouldn't be in scope for this PR I think

Okay, thank you. I'll look into it a bit more myself.

I was able to get a build of monado's version of basalt here, it uses an older version of pangolin, and some packages that aren't packaged in nix like Sophus. I just need to test it with monado to see if it is actually working.