diff options
Diffstat (limited to 'nixpkgs/nixos/modules/installer/cd-dvd/sd-image.nix')
| -rw-r--r-- | nixpkgs/nixos/modules/installer/cd-dvd/sd-image.nix | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/nixpkgs/nixos/modules/installer/cd-dvd/sd-image.nix b/nixpkgs/nixos/modules/installer/cd-dvd/sd-image.nix new file mode 100644 index 000000000000..69746a8e9799 --- /dev/null +++ b/nixpkgs/nixos/modules/installer/cd-dvd/sd-image.nix @@ -0,0 +1,168 @@ +# This module creates a bootable SD card image containing the given NixOS +# configuration. The generated image is MBR partitioned, with a FAT /boot +# partition, and ext4 root partition. The generated image is sized to fit +# its contents, and a boot script automatically resizes the root partition +# to fit the device on the first boot. +# +# The derivation for the SD image will be placed in +# config.system.build.sdImage + +{ config, lib, pkgs, ... }: + +with lib; + +let + rootfsImage = pkgs.callPackage ../../../lib/make-ext4-fs.nix ({ + inherit (config.sdImage) storePaths; + volumeLabel = "NIXOS_SD"; + } // optionalAttrs (config.sdImage.rootPartitionUUID != null) { + uuid = config.sdImage.rootPartitionUUID; + }); +in +{ + options.sdImage = { + imageName = mkOption { + default = "${config.sdImage.imageBaseName}-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.img"; + description = '' + Name of the generated image file. + ''; + }; + + imageBaseName = mkOption { + default = "nixos-sd-image"; + description = '' + Prefix of the name of the generated image file. + ''; + }; + + storePaths = mkOption { + type = with types; listOf package; + example = literalExample "[ pkgs.stdenv ]"; + description = '' + Derivations to be included in the Nix store in the generated SD image. + ''; + }; + + bootPartitionID = mkOption { + type = types.string; + default = "0x2178694e"; + description = '' + Volume ID for the /boot partition on the SD card. This value must be a + 32-bit hexadecimal number. + ''; + }; + + rootPartitionUUID = mkOption { + type = types.nullOr types.string; + default = null; + example = "14e19a7b-0ae0-484d-9d54-43bd6fdc20c7"; + description = '' + UUID for the main NixOS partition on the SD card. + ''; + }; + + bootSize = mkOption { + type = types.int; + default = 120; + description = '' + Size of the /boot partition, in megabytes. + ''; + }; + + populateBootCommands = mkOption { + example = literalExample "'' cp \${pkgs.myBootLoader}/u-boot.bin boot/ ''"; + description = '' + Shell commands to populate the ./boot directory. + All files in that directory are copied to the + /boot partition on the SD image. + ''; + }; + }; + + config = { + fileSystems = { + "/boot" = { + device = "/dev/disk/by-label/NIXOS_BOOT"; + fsType = "vfat"; + }; + "/" = { + device = "/dev/disk/by-label/NIXOS_SD"; + fsType = "ext4"; + }; + }; + + sdImage.storePaths = [ config.system.build.toplevel ]; + + system.build.sdImage = pkgs.callPackage ({ stdenv, dosfstools, e2fsprogs, mtools, libfaketime, utillinux }: stdenv.mkDerivation { + name = config.sdImage.imageName; + + nativeBuildInputs = [ dosfstools e2fsprogs mtools libfaketime utillinux ]; + + buildCommand = '' + mkdir -p $out/nix-support $out/sd-image + export img=$out/sd-image/${config.sdImage.imageName} + + echo "${pkgs.stdenv.buildPlatform.system}" > $out/nix-support/system + echo "file sd-image $img" >> $out/nix-support/hydra-build-products + + # Create the image file sized to fit /boot and /, plus 20M of slack + rootSizeBlocks=$(du -B 512 --apparent-size ${rootfsImage} | awk '{ print $1 }') + bootSizeBlocks=$((${toString config.sdImage.bootSize} * 1024 * 1024 / 512)) + imageSize=$((rootSizeBlocks * 512 + bootSizeBlocks * 512 + 20 * 1024 * 1024)) + truncate -s $imageSize $img + + # type=b is 'W95 FAT32', type=83 is 'Linux'. + sfdisk $img <<EOF + label: dos + label-id: ${config.sdImage.bootPartitionID} + + start=8M, size=$bootSizeBlocks, type=b, bootable + start=${toString (8 + config.sdImage.bootSize)}M, type=83 + EOF + + # Copy the rootfs into the SD image + eval $(partx $img -o START,SECTORS --nr 2 --pairs) + dd conv=notrunc if=${rootfsImage} of=$img seek=$START count=$SECTORS + + # Create a FAT32 /boot partition of suitable size into bootpart.img + eval $(partx $img -o START,SECTORS --nr 1 --pairs) + truncate -s $((SECTORS * 512)) bootpart.img + faketime "1970-01-01 00:00:00" mkfs.vfat -i ${config.sdImage.bootPartitionID} -n NIXOS_BOOT bootpart.img + + # Populate the files intended for /boot + mkdir boot + ${config.sdImage.populateBootCommands} + + # Copy the populated /boot into the SD image + (cd boot; mcopy -psvm -i ../bootpart.img ./* ::) + # Verify the FAT partition before copying it. + fsck.vfat -vn bootpart.img + dd conv=notrunc if=bootpart.img of=$img seek=$START count=$SECTORS + ''; + }) {}; + + boot.postBootCommands = '' + # On the first boot do some maintenance tasks + if [ -f /nix-path-registration ]; then + # Figure out device names for the boot device and root filesystem. + rootPart=$(readlink -f /dev/disk/by-label/NIXOS_SD) + bootDevice=$(lsblk -npo PKNAME $rootPart) + + # Resize the root partition and the filesystem to fit the disk + echo ",+," | sfdisk -N2 --no-reread $bootDevice + ${pkgs.parted}/bin/partprobe + ${pkgs.e2fsprogs}/bin/resize2fs $rootPart + + # Register the contents of the initial Nix store + ${config.nix.package.out}/bin/nix-store --load-db < /nix-path-registration + + # nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag. + touch /etc/NIXOS + ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/system --set /run/current-system + + # Prevents this from running on later boots. + rm -f /nix-path-registration + fi + ''; + }; +} |