nixosTests.limine.bios: init

This patch adds a NixOS test for Limine on BIOS systems. It also fixes
some formatting in `nixos/lib/make-disk-image.nix`.

Signed-off-by: John Titor <[e-mail]>

nixos/lib/make-disk-image.nix

···
         ''}
 
         ${lib.optionalString installBootLoader ''
-            # In this throwaway resource, we only have /dev/vda, but the actual VM may refer to another disk for bootloader, e.g. /dev/vdb
-            # Use this option to create a symlink from vda to any arbitrary device you want.
-            ${lib.optionalString (config.boot.loader.grub.enable) (
-              lib.concatMapStringsSep " " (
-                device:
-                lib.optionalString (device != "/dev/vda") ''
-                  mkdir -p "$(dirname ${device})"
-                  ln -s /dev/vda ${device}
-                ''
-              ) config.boot.loader.grub.devices
-            )}
+          # In this throwaway resource, we only have /dev/vda, but the actual VM may refer to another disk for bootloader, e.g. /dev/vdb
+          # Use this option to create a symlink from vda to any arbitrary device you want.
+          ${lib.optionalString (config.boot.loader.grub.enable) (
+            lib.concatMapStringsSep " " (
+              device:
+              lib.optionalString (device != "/dev/vda") ''
+                mkdir -p "$(dirname ${device})"
+                ln -s /dev/vda ${device}
+              ''
+            ) config.boot.loader.grub.devices
+          )}
+          ${
+            let
+              limine = config.boot.loader.limine;
+            in
+            lib.optionalString (limine.enable && limine.biosSupport && limine.biosDevice != "/dev/vda") ''
+              mkdir -p "$(dirname ${limine.biosDevice})"
+              ln -s /dev/vda ${limine.biosDevice}
+            ''
+          }
 
-            # Set up core system link, bootloader (sd-boot, GRUB, uboot, etc.), etc.
+          # Set up core system link, bootloader (sd-boot, GRUB, uboot, etc.), etc.
 
           # NOTE: systemd-boot-builder.py calls nix-env --list-generations which
           # clobbers $HOME/.nix-defexpr/channels/nixos This would cause a  folder

nixos/modules/virtualisation/qemu-vm.nix

···
       `useBootLoader` useless. You might want to disable one of those options.
     '';
 
+    # Install Limine on the bootloader device
+    boot.loader.limine.biosDevice = cfg.bootLoaderDevice;
+
     # In UEFI boot, we use a EFI-only partition table layout, thus GRUB will fail when trying to install
     # legacy and UEFI. In order to avoid this, we have to put "nodev" to force UEFI-only installs.
     # Otherwise, we set the proper bootloader device for this.

nixos/tests/limine/bios.nix

···
+{ lib, ... }:
+{
+  name = "bios";
+  meta.maintainers = with lib.maintainers; [
+    lzcunt
+    phip1611
+    programmerlexi
+  ];
+  meta.platforms = [
+    "i686-linux"
+    "x86_64-linux"
+  ];
+  nodes.machine =
+    { ... }:
+    {
+      virtualisation.useBootLoader = true;
+      virtualisation.useBootPartition = true;
+      boot.loader.limine.enable = true;
+      boot.loader.limine.efiSupport = false;
+      boot.loader.timeout = 0;
+    };
+
+  testScript = ''
+    machine.start()
+    with subtest('Machine boots correctly'):
+      machine.wait_for_unit('multi-user.target')
+  '';
+}

nixos/tests/limine/default.nix

···
   ...
 }:
 {
+  bios = runTest ./bios.nix;
   checksum = runTest ./checksum.nix;
   secureBoot = runTest ./secure-boot.nix;
   specialisations = runTest ./specialisations.nix;