v4l2loopback: unstable-2020-04-22 -> unstable-2021-07-13, add bin output with utils

[L-as]

Motivation for this change

Now we can use v4l2loopback-ctl

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 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.

[L-as]

@fortuneteller2k

[SuperSandro2000]

This is a semi-automatic executed nixpkgs-review with nixpkgs-review-checks extension. It is checked by a human on a best effort basis and does not build all packages (e.g. lumo, tensorflow or pytorch).

Result of nixpkgs-review pr 134311 run on x86_64-linux 1

4 packages marked as broken and skipped:

• linuxPackages-libre.v4l2loopback
• linuxPackages_hardkernel_4_14.v4l2loopback
• linuxPackages_hardkernel_latest.v4l2loopback
• linuxPackages_latest-libre.v4l2loopback

12 packages built:

• linuxPackages.v4l2loopback (linuxPackages_5_10.v4l2loopback)
• linuxPackages_4_14.v4l2loopback
• linuxPackages_4_19.v4l2loopback
• linuxPackages_4_4.v4l2loopback
• linuxPackages_4_9.v4l2loopback
• linuxPackages_5_13.v4l2loopback (linuxPackages_latest.v4l2loopback)
• linuxPackages_5_4.v4l2loopback
• linuxPackages_hardened.v4l2loopback (linuxPackages_latest_hardened.v4l2loopback)
• linuxPackages_lqx.v4l2loopback
• linuxPackages_testing_bcachefs.v4l2loopback
• linuxPackages_xanmod.v4l2loopback
• linuxPackages_zen.v4l2loopback

[frogamic]

I believe this has broken v4l2loopback, the output folder now only includes a bin folder with the v4l2loopback-ctl binary but no kernel module.

[frogamic]

Suggest instead to not modify outputs and add

postInstall = ''
  make install-utils PREFIX=$out
'';

[L-as]

@frogamic then you will have the executable in /run/current-system/kernel-modules.

[frogamic]

Maybe I am doing something wrong, but when I try to install the v4l2loopback kernel module as shown in the examples I could find, I only have the utils binary in my kernel modules folder and no actual kernel module.

boot = {
  extraModulePackages = [ config.boot.kernelPackages.v4l2loopback ];
  kernelModules = [ "v4l2loopback" ];
  extraModprobeConfig = ''
    options v4l2loopback exclusive_caps=1
  '';
};

[L-as]

Try putting `.out` on the end of it to choose the output explicitly. Very odd. When I in my REPL check the default output it gives me the kernel library. This seems more like a big with the NixOS module for the kernel.

[frogamic]

Ah yes, thanks that fixed it. This is going to be a breaking change for anyone who has googled "Droidcam nixos" though, I was pulling my hair out wondering why no guide was working till I found this change from 3 days ago 🙁

[L-as]

I fixed this.