systemd-stage-1: Remove systemd-gpt-auto-generator

[ElvishJerricco]

This doesn't actually work in systemd stage 1 at all right now. It cannot mount / or /usr. It still works as expected in stage 2.

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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.

---

Add a 👍 reaction to pull requests you find important.

[NickCao]

This doesn't actually work in systemd stage 1 at all right now.

What exactly goes wrong?

[arianvp]

Yeh a little bit more context in the commit / PR would be appreciated. I'm kind of confused why we want to disable or enable this

[ElvishJerricco]

@NickCao In stage 1, the only thing it does is create mount units for /sysroot via the /dev/gpt-auto-root device link generated by udev. The problem is that we put /sysroot into the SYSTEMD_SYSROOT_FSTAB file, and fstab-generator makes units for it too. So the two conflict and stage 1 breaks.

To fix this, we would need to put root= on the cmdline, which isn't as trivial as it sounds. The fstab-generator will ignore the root FS when its on cmdline like that, but not if its in fstab. On the other hand, gpt-auto doesn't even know about the fstab file so it can't check there to ignore, so it can only use cmdline.

[YHNdnzj]

The fstab-generator will ignore the root FS when its on cmdline like that, but not if its in fstab. On the other hand, gpt-auto doesn't even know about the fstab file so it can't check there to ignore, so it can only use cmdline.

How? root=fstab works perfectly for the use case you mentioned.

[ElvishJerricco]

@YHNdnzj Ah, that's a good point. Regardless, we would always be using root=fstab, and then systemd-gpt-auto-generator would still be literally never doing anything. So regardless of that, systemd-gpt-auto-generator is never doing anything and we might as well remove it until we actually support it.

[philiptaron]

I like #282022 substantially more than this one, for what it's worth. 🔢

Does this PR also belong on the "Systemd in Stage 1" board?

[ElvishJerricco]

Closed in favor of #282022