nixos/make-disk-image.nix: Support EFI images

- Add a new parameter `imageType` that can specify either "efi" or
  "legacy" (the default which should see no change in behaviour by
  this patch).

- EFI images get a GPT partition table (instead of msdos) with a
  mandatory ESP partition (so we add an assert that `partitioned`
  is true).

- Use the partx tool from util-linux to determine exact start + size
  of the root partition. This is required because GPT stores a secondary
  partition table at the end of the disk, so we can't just have
  mkfs.ext4 create the filesystem until the end of the disk.

- (Unrelated to any EFI changes) Since we're depending on the
  `-E offset=X` option to mkfs which is only supported by e2fsprogs,
  disallow any attempts of creating partitioned disk images where
  the root filesystem is not ext4.
This commit is contained in:
Tuomas Tynkkynen 2017-12-07 02:00:21 +02:00
parent 73695300bc
commit 962e79ef32
3 changed files with 67 additions and 21 deletions

View file

@ -13,10 +13,16 @@
# grafted in the file system at path `target'.
, contents ? []
, # Whether the disk should be partitioned (with a single partition
# containing the root filesystem) or contain the root filesystem
# directly.
partitioned ? true
, # Type of partition table to use; either "legacy", "efi", or "none".
# For "efi" images, the GPT partition table is used and a mandatory ESP
# partition of reasonable size is created in addition to the root partition.
# If `installBootLoader` is true, GRUB will be installed in EFI mode.
# For "legacy", the msdos partition table is used and a single large root
# partition is created. If `installBootLoader` is true, GRUB will be
# installed in legacy mode.
# For "none", no partition table is created. Enabling `installBootLoader`
# most likely fails as GRUB will probably refuse to install.
partitionTableType ? "legacy"
# Whether to invoke switch-to-configuration boot during image creation
, installBootLoader ? true
@ -37,6 +43,10 @@
format ? "raw"
}:
assert partitionTableType == "legacy" || partitionTableType == "efi" || partitionTableType == "none";
# We use -E offset=X below, which is only supported by e2fsprogs
assert partitionTableType != "none" -> fsType == "ext4";
with lib;
let format' = format; in let
@ -51,6 +61,27 @@ let format' = format; in let
raw = "img";
}.${format};
rootPartition = { # switch-case
legacy = "1";
efi = "2";
}.${partitionTableType};
partitionDiskScript = { # switch-case
legacy = ''
parted --script $diskImage -- \
mklabel msdos \
mkpart primary ext4 1MiB -1
'';
efi = ''
parted --script $diskImage -- \
mklabel gpt \
mkpart ESP fat32 8MiB 256MiB \
set 1 boot on \
mkpart primary ext4 256MiB -1
'';
none = "";
}.${partitionTableType};
nixpkgs = cleanSource pkgs.path;
channelSources = pkgs.runCommand "nixos-${config.system.nixosVersion}" {} ''
@ -79,20 +110,31 @@ let format' = format; in let
targets = map (x: x.target) contents;
prepareImage = ''
export PATH=${makeSearchPathOutput "bin" "bin" prepareImageInputs}
export PATH=${makeBinPath prepareImageInputs}
# Yes, mkfs.ext4 takes different units in different contexts. Fun.
sectorsToKilobytes() {
echo $(( ( "$1" * 512 ) / 1024 ))
}
sectorsToBytes() {
echo $(( "$1" * 512 ))
}
mkdir $out
diskImage=nixos.raw
truncate -s ${toString diskSize}M $diskImage
${if partitioned then ''
parted --script $diskImage -- mklabel msdos mkpart primary ext4 1M -1s
offset=$((2048*512))
'' else ''
offset=0
''}
${partitionDiskScript}
mkfs.${fsType} -F -L nixos -E offset=$offset $diskImage
${if partitionTableType != "none" then ''
# Get start & length of the root partition in sectors to $START and $SECTORS.
eval $(partx $diskImage -o START,SECTORS --nr ${rootPartition} --pairs)
mkfs.${fsType} -F -L nixos $diskImage -E offset=$(sectorsToBytes $START) $(sectorsToKilobytes $SECTORS)K
'' else ''
mkfs.${fsType} -F -L nixos $diskImage
''}
root="$PWD/root"
mkdir -p $root
@ -133,12 +175,12 @@ let format' = format; in let
find $root/nix/store -mindepth 1 -maxdepth 1 -type f -o -type d | xargs chmod -R a-w
echo "copying staging root to image..."
cptofs ${optionalString partitioned "-P 1"} -t ${fsType} -i $diskImage $root/* /
cptofs -p ${optionalString (partitionTableType != "none") "-P ${rootPartition}"} -t ${fsType} -i $diskImage $root/* /
'';
in pkgs.vmTools.runInLinuxVM (
pkgs.runCommand name
{ preVM = prepareImage;
buildInputs = with pkgs; [ utillinux e2fsprogs ];
buildInputs = with pkgs; [ utillinux e2fsprogs dosfstools ];
exportReferencesGraph = [ "closure" metaClosure ];
postVM = ''
${if format == "raw" then ''
@ -152,11 +194,7 @@ in pkgs.vmTools.runInLinuxVM (
memSize = 1024;
}
''
${if partitioned then ''
rootDisk=/dev/vda1
'' else ''
rootDisk=/dev/vda
''}
rootDisk=${if partitionTableType != "none" then "/dev/vda${rootPartition}" else "/dev/vda"}
# Some tools assume these exist
ln -s vda /dev/xvda
@ -166,6 +204,14 @@ in pkgs.vmTools.runInLinuxVM (
mkdir $mountPoint
mount $rootDisk $mountPoint
# Create the ESP and mount it. Unlike e2fsprogs, mkfs.vfat doesn't support an
# '-E offset=X' option, so we can't do this outside the VM.
${optionalString (partitionTableType == "efi") ''
mkdir -p /mnt/boot
mkfs.vfat -n ESP /dev/vda1
mount /dev/vda1 /mnt/boot
''}
# Install a configuration.nix
mkdir -p /mnt/etc/nixos
${optionalString (configFile != null) ''

View file

@ -46,7 +46,7 @@ in {
inherit lib config;
inherit (cfg) contents format name;
pkgs = import ../../../.. { inherit (pkgs) system; }; # ensure we use the regular qemu-kvm package
partitioned = config.ec2.hvm;
partitionTableType = if config.ec2.hvm then "legacy" else "none";
diskSize = cfg.sizeMB;
configFile = pkgs.writeText "configuration.nix"
''

View file

@ -25,7 +25,7 @@ in {
name = "nixos-ova-${config.system.nixosLabel}-${pkgs.stdenv.system}";
inherit pkgs lib config;
partitioned = true;
partitionTableType = "legacy";
diskSize = cfg.baseImageSize;
postVM =