Grub: default is signed int. Fixes #42152

[dje4321]

Motivation for this change

grub.default is type signed int but grub supports passing "saved" as the default option to boot the previous os.

Breaks compatibility with exsisting nixos configs but just requires changing the option from int to str.

Things done

set boot.loader.grub.default to type.str and set install-grub.pl to use str

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• 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 against boot.nix boot-stage1.nix
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• [N/A] Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[Mic92]

How about?

type = types.either types.int types.str;
apply = toString;

or

type = types.either types.int (types.enum [ "saved" ]);
apply = toString;

[dje4321]

oh neat. didnt know you could do the either thing

[Mic92]

@GrahamcOfBorg test boot.biosUsb

[GrahamcOfBorg]

No attempt on aarch64-linux (full log)

The following builds were skipped because they don't evaluate on aarch64-linux: tests.boot.biosUsb

Partial log (click to expand)

a) For `nixos-rebuild` you can set
  { nixpkgs.config.allowUnsupportedSystem = true; }
in configuration.nix to override this.

b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
  { allowUnsupportedSystem = true; }
to ~/.config/nixpkgs/config.nix.

[GrahamcOfBorg]

Success on x86_64-linux (full log)

Attempted: tests.boot.biosUsb

Partial log (click to expand)

machine# [  575.313458] [2031]: Failed to unmount /nix/.ro-store: Device or resource busy
machine# [  575.314430] [2032]: Unmounting '/iso'.
machine# [  575.314793] [2032]: Failed to unmount /iso: Device or resource busy
machine# [  575.316568] ACPI: Preparing to enter system sleep state S5
machine# [  575.317072] reboot: Power down
collecting coverage data
syncing
test script finished in 605.13s
cleaning up
/nix/store/p7ljxs6yc50y2cn81m36h3z963g6hdd1-vm-test-run-boot-bios-usb