anchor.diff:          { source = config.system.build.squashfsStore;
             target = "/nix-store.squashfs";
           }
  -        { source = config.isoImage.efiSplashImage;
  -          target = "/EFI/boot/efi-background.png";
  -        }
           { source = config.isoImage.splashImage;
             target = "/isolinux/background.png";
           }
  
positive.code:         { source = "${efiDir}/EFI";
            target = "/EFI";
          }
          { source = pkgs.writeText "loopback.cfg" "source /EFI/boot/grub.cfg";
            target = "/boot/grub/loopback.cfg";
          }
        ] ++ optionals (config.boot.loader.grub.memtest86.enable && canx86BiosBoot) [
          { source = "${pkgs.memtest86plus}/memtest.bin";
  
negative.code:       ] ++ optionals (config.isoImage.grubTheme != null) [
          { source = config.isoImage.grubTheme;
            target = "/EFI/boot/grub-theme";
          }
        ] ++ [
          { source = config.isoImage.efiSplashImage;
            target = "/EFI/boot/efi-background.png";
          }
        ];
  
  