Commit c68a5bb8 authored by Ivan Trubach's avatar Ivan Trubach
Browse files

nixos/iso-image: enable BIOS boot by default if possible 

The change introduced in commit e5b072ec
breaks backwards compatibility for some users, see
https://github.com/NixOS/nixpkgs/commit/e5b072eca165430efc4d7a179011a42aab4470a2#commitcomment-113775008
https://github.com/NixOS/nixpkgs/pull/219351#discussion_r1139773448

This change updates the implementation to enable BIOS boot if possible
for the build and host platforms, and also assert that BIOS boot is not
enabled for non-x86 host platforms.
parent fd4c3880

nixos/modules/installer/cd-dvd/installation-cd-base.nix

+0 −3
Original line number Diff line number Diff line
@@ -21,9 +21,6 @@ with lib; 
  # ISO naming.

  isoImage.isoName = "${config.isoImage.isoBaseName}-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.iso";



  # BIOS booting

  isoImage.makeBiosBootable = true;



  # EFI booting

  isoImage.makeEfiBootable = true;

nixos/modules/installer/cd-dvd/iso-image.nix

+22 −10
Original line number Diff line number Diff line
@@ -442,9 +442,6 @@ let 
      fsck.vfat -vn "$out"

    ''; # */



  # Syslinux (and isolinux) only supports x86-based architectures.

  canx86BiosBoot = pkgs.stdenv.hostPlatform.isx86;



in



{
@@ -543,7 +540,17 @@ in 
    };



    isoImage.makeBiosBootable = mkOption {

      default = false;

      # Before this option was introduced, images were BIOS-bootable if the

      # hostPlatform was x86-based. This option is enabled by default for

      # backwards compatibility.

      #

      # Also note that syslinux package currently cannot be cross-compiled from

      # non-x86 platforms, so the default is false on non-x86 build platforms.

      default = pkgs.stdenv.buildPlatform.isx86 && pkgs.stdenv.hostPlatform.isx86;

      defaultText = lib.literalMD ''

        `true` if both build and host platforms are x86-based architectures,

        e.g. i686 and x86_64.

      '';

      type = lib.types.bool;

      description = lib.mdDoc ''

        Whether the ISO image should be a BIOS-bootable disk.
@@ -704,6 +711,11 @@ in 


  config = {

    assertions = [

      {

        # Syslinux (and isolinux) only supports x86-based architectures.

        assertion = config.isoImage.makeBiosBootable -> pkgs.stdenv.hostPlatform.isx86;

        message = "BIOS boot is only supported on x86-based architectures.";

      }

      {

        assertion = !(stringLength config.isoImage.volumeID > 32);

        # https://wiki.osdev.org/ISO_9660#The_Primary_Volume_Descriptor
@@ -722,7 +734,7 @@ in 
    boot.loader.grub.enable = false;



    environment.systemPackages =  [ grubPkgs.grub2 grubPkgs.grub2_efi ]

      ++ optional (config.isoImage.makeBiosBootable && canx86BiosBoot) pkgs.syslinux

      ++ optional (config.isoImage.makeBiosBootable) pkgs.syslinux

    ;



    # In stage 1 of the boot, mount the CD as the root FS by label so
@@ -773,7 +785,7 @@ in 
        { source = pkgs.writeText "version" config.system.nixos.label;

          target = "/version.txt";

        }

      ] ++ optionals (config.isoImage.makeBiosBootable && canx86BiosBoot) [

      ] ++ optionals (config.isoImage.makeBiosBootable) [

        { source = config.isoImage.splashImage;

          target = "/isolinux/background.png";

        }
@@ -800,7 +812,7 @@ in 
        { source = config.isoImage.efiSplashImage;

          target = "/EFI/boot/efi-background.png";

        }

      ] ++ optionals (config.boot.loader.grub.memtest86.enable && config.isoImage.makeBiosBootable && canx86BiosBoot) [

      ] ++ optionals (config.boot.loader.grub.memtest86.enable && config.isoImage.makeBiosBootable) [

        { source = "${pkgs.memtest86plus}/memtest.bin";

          target = "/boot/memtest.bin";

        }
@@ -815,10 +827,10 @@ in 
    # Create the ISO image.

    system.build.isoImage = pkgs.callPackage ../../../lib/make-iso9660-image.nix ({

      inherit (config.isoImage) isoName compressImage volumeID contents;

      bootable = config.isoImage.makeBiosBootable && canx86BiosBoot;

      bootable = config.isoImage.makeBiosBootable;

      bootImage = "/isolinux/isolinux.bin";

      syslinux = if config.isoImage.makeBiosBootable && canx86BiosBoot then pkgs.syslinux else null;

    } // optionalAttrs (config.isoImage.makeUsbBootable && config.isoImage.makeBiosBootable && canx86BiosBoot) {

      syslinux = if config.isoImage.makeBiosBootable then pkgs.syslinux else null;

    } // optionalAttrs (config.isoImage.makeUsbBootable && config.isoImage.makeBiosBootable) {

      usbBootable = true;

      isohybridMbrImage = "${pkgs.syslinux}/share/syslinux/isohdpfx.bin";

    } // optionalAttrs config.isoImage.makeEfiBootable {