feedbackd: support cross-compilation

[Mindavi]

Disables introspection for now.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux (cross-compiled)
  • 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/)
• Fits CONTRIBUTING.md.

[Mindavi]

So yeah, this all seems correct, but the wrapGAppsHook produces a binary for x86-64... 😞. See #175045. Guess we can still merge this anyway, but another fix is needed to actually make it fully work.

[tomfitzhenry]

So it looks like cross-compilation and gobject introspection are mutually exclusive, until #72868 is fixed.

The pro case for the status quo of keeping introspection:

• keeps this package simple
• keeps this package aligned with upstream
• allows any clients that rely on introspection to keep working
• puts more emphasis on fixing the root cause: Cross-compiling gir (gobject-introspection) #72868

Cross-compilation is important to have, but is it worth losing the pros of keeping introspection?

FWIW, I think it's common for mobile NixOS users to compile natively (either on an existing aarch64 device, or via binfmt emulation).

[Mindavi]

To me it wouldn't make sense that the option of disabling introspection would be available if it broke everything, but that may be naive.

I agree that keeping simple would be nice. I don't agree that it aligns with upstream if they provide the option.

Some progress is being made on improving the gir situation! #176464

So we may be able to remove the disables in the near future.

Personally I like to be able to cross-compile, even if it reduces functionality a bit. I do try it out from time to time and am aiming to get a full-blown image (with DM) working at some point, just because I like to prove it's possible and to be able to use my own hardware to build the image. But of course it would be nice to have more functionality.

Thanks for keeping the discussion alive btw, it's good that we think about these choices.

[tomfitzhenry]

SGTM. I see low risk of breaking usecases, and since feedbackd is typically used on aarch64, I can see how cross-compilation would be convenient.

Have you tried compilation via binfmt? That should work, even without cross-compilation.

[github-actions]

Successfully created backport PR #176942 for release-22.05.