• Migrated to systemd-repart. Many options are dropped in favor of specifying them directly
  in repart partition definition files:

  • Format=gpt_xxx options are replaced with a single "disk" options. Filesystem to use can now be specified with repart's Format= option
  • Format=plain_squashfs (Can be reproduced by a single repart squashfs
    root partition combined with SplitArtifacts=yes)
  • Verity= (Replaced by repart's Verity= options)
  • Encrypt= (Replaced by repart's Encrypt= option)
  • RootSize=, HomeSize=, VarSize=, TmpSize=, ESPSize=, SwapSize=, SrvSize=
    (Replaced by repart's size options)
  • UsrOnly= (replaced with CopyFiles=/:/usr in a usr partition definition)
  • OutputSplitRoot=, OutputSplitVerity=, (Replaced by repart's SplitName= option)
  • OutputSplitKernel= (UKI is now always written to its own output file)
  • GPTFirstLBA (Removed, no equivalent in repart)
  • ReadOnly= (Replaced by repart's ReadOnly= option per partition)
  • Minimize= (Replaced by repart's Minimize= option per partition)
  • CompressFs= (No equivalent in repart, can be replicated by replacing mkfs.
    in $PATH with a script that adds the necessary command line option)
  • MkSquashfs= (Can be replaced with a script in $PATH that invokes
    the correct binary)

  We also remove the WithoutUnifiedKernelImages= switch as building unified
  kernel images is trivial and fast these days.

• Support for --qemu-boot was dropped

• Support for --use-host-repositories was dropped, use --repository-directory instead

• RepositoryDirectory was removed, use PackageManagerTrees= or SkeletonTrees= instead.

• --repositories is now only usable on Debian/RPM based distros and can only be used to enable additional
  repositories. Specifically, it cannot be used on Arch Linux anymore to add new repositories.

• The _epel distributions were removed. Use --repositories=epel instead to enable
  the EPEL repository.

• Removed -stream from CentOS release specifiers. Instead of specifying 8-stream,
  you know just specify 8.

• Removed default kernel command line arguments rhgb, selinux=0 and audit=0.

• Dropped --all and --all-directory as this functionality is better implemented by
  using a build system.

• mkosi now builds images without needing root privileges.

• Removed --no-chown, --idmap and --nspawn-keep-unit options as they were made obsolete by moving to
  rootless builds.

• Removed --source-file-transfer, --source-file-transfer-final, --source-resolve-symlinks and
  --source-resolve-symlinks-final in favor of always mounting the source directory into the build image.
  --source-file-transfer-final might be reimplemented in the future using virtiofsd.

• Dropped --include-dir option. Usage can be replaced by using --incremental and reading includes from
  the cached build image tree.

• Removed --machine-id in favor of shipping images without a machine ID at all.

• Removed --skip-final-phase as we only have a single phase now.

• The post install script is only called for the final image now and not for the build image anymore. Use the
  prepare script instead.

• --ssh-key, --ssh-agent, --ssh-port and --ssh-timeout options were dropped as the SSH support was
  reimplemented using VSock. mkosi ssh can only be used with images booted with mkosi qemu. Use
  machinectl to access images booted with mkosi boot. Use --extra-tree or --credential with the
  .ssh.authorized_keys.root credentials as alternatives for provisioning the public key inside the image.

• Only configuration files matching *.conf are parsed in dropin directories now.

• Removed --qemu-headless, we now start qemu in the terminal by default and configure the serial console at
  runtime. Use the new --qemu-gui option to start qemu in its graphical interface.

• Removed --netdev. Can be replaced by manually installing systemd-networkd, putting a network file in the
  image and enabling systemd-networkd.

• If mkosi.extra/ or mkosi.skeleton/ exist, they are now always used instead of only when no explicit
  extra/skeleton trees are defined.

• mkosi doesn't install any default packages anymore aside from packages required by the distro or the base
  filesystem layout package if there are no required packages. In practice, this means systemd and other
  basic tools have to be installed explicitly from now on.

• Removed --base-packages as it's not needed anymore since we don't install any packages by default anymore
  aside from the base filesystem layout package.

• Removed --qcow2 option in favor of supporting only raw disk images as the disk image output format.

• Removed --bmap option as it can be trivially added manually by utilizing a finalize script.

• The never value for --with-network was spun of into its own custom option --cache-only.

• --bootable now defaults to auto. When set to auto, mkosi will generate a bootable image only if all
  the necessary packages are installed. Documentation was added in docs/bootable.md on how a bootable image
  can be generated on mainstream distros.

• The RPM db is no longer rebuilt in bdb format on CentOS Stream 8. To be able to install packages on a
  CentOS Stream 8 image with a RPM db in sqlite format, rewrite the db in bdb format using
  rpm --rebuilddb --define _db_backend bdb.

• Repositories are now only written to /etc/apt/sources.list if apt is installed in the image.

• Removed the dependency on debootstrap to build Ubuntu or Debian images.

• Apt now uses the keyring from the host instead of the keyring from the image. This means
  debian-archive-keyring or ubuntu-archive-keyring are now required to be installed to build Debian or
  Ubuntu images respectively.

• --base-image is split into --base-tree and --overlay.

• Removed --cache-initrd, instead, use a prebuilt initrd with Initrds= to avoid rebuilding the initrd all
  the time.

• Disk images are now resized to 8G when booted to give some disk space to play around with in the booted
  image.

• Removed --install-directory= option. This was originally added for caching the installation results, but
  this doesn't work properly as it might result in leftover files in the install directory from a previous
  installation, so we have to empty the directory before reusing it, invalidating the caching, so the option
  was removed.

• Build scripts are now executed on the host. See the SCRIPTS section
  in the manual for more information. Existing build scripts will need
  to be updated to make sure they keep working. Specifically, most paths
  in scripts will need to be prefixed with $BUILDROOT to have them
  operate on the image instead of on the host system. To ensure the host
  system cannot be modified when running a script, most host directories
  are mounted read-only when running a script to ensure a script cannot
  modify the host in any way. Alternatively to making the script run on
  the host, the script can also still be executed in the image itself by
  putting the following snippet at the top of the script:

  if [ "$container" != "mkosi" ]; then
      exec mkosi-chroot "$SCRIPT" "$@"
  fi

• Removed --tar-strip-selinux-context= option. We now label all files
  properly if selinux is enabled and if users don't want the labels,
  they can simply exclude them when extracting the archive.

• Gentoo is now marked as experimental and unsupported and there's no
  guarantee at all that it will work. Issues related to gentoo will
  generally not receive attention from core maintainers. All gentoo
  specific hacks outside of the gentoo implementation module have been
  removed.

• A verb documentation has been added. Calling mkosi with this verb will show
  the documentation. This is useful when running mkosi during development to
  always have the documentation in the correct version available. By default it
  will try several ways to output the documentation, but a specific option can
  be chosen with the --doc-format option. Distro packagers are encouraged to
  add a file mkosi.1 into the mkosi/resources directory of the Python
  package, if it is missing, as well es install it in the appropriate search
  path for man pages. The man page can be generated from the markdown file
  mkosi/resources/mkosi.md e.g via pandoc -t man -s -o mkosi.1 mkosi.md.

• The man page can be generated from the markdown file via
  tools/make-man-page.sh.

• Fixed issue where not all packages and data files where included in
  the generated python package.

• mkosi doesn't try to unshare the network namespace anymore when it
  doesn't have CAP_NET_ADMIN.

• Fixed issue when the workspace was located in /tmp.

• Don't try to run timedatectl or ssh-add when they're not installed.

• Support for Clear Linux was dropped. See #1037 for more information.

• Support for Photon was dropped. See #1048 for more information.

• The Arch kernel/bootloader pacman hooks were removed. For anyone that still wants to use them, they can be found here.

• mkosi now creates distro~release subdirectories inside the build, cache and output directories for each distro~release combination that is built. This allows building for multiple distros without throwing away the results of a previous distro build every time.

• The preferred names for mkosi configuration files and directories are now mkosi.conf and mkosi.conf.d/ respectively. The old names (mkosi.default and mkosi.default.d) have been removed from the docs but are still supported for backwards compatibility.

• plain_squashfs type images will now also be named with a .raw suffix.

• tar type images will now respect the --compress option.

• Pacman's SigLevel option was changed to use the same default value as used on Arch which is SigLevel = Required DatabaseOptional. If this results in keyring errors, you need to update the keyring by running pacman-key --populate archlinux.

• Support for CentOS 7 was dropped. If you still need to support CentOS 7, we recommend using any mkosi version up to 13.

• Support for BIOS/grub was dropped. because EFI hardware is widely available and legacy BIOS systems do not support the feature set to fully verify a boot chain from firmware to userland and it has become bothersome to maintain for little use.

  To generate BIOS images you can use any version of mkosi up to mkosi 13 or the new --bios-size option. This can be used to add a BIOS boot partition of the specified size on which grub (or any other bootloader) can be installed with the help of mkosi's script support (depending on your needs most likely mkosi.postinst or mkosi.finalize). This method can also be used for other EFI bootloaders that mkosi intentionally does not support.

• mkosi now unconditionally copies the kernel, initrd and kernel cmdline from the image that were previously only copied out for Qemu boot.

• mkosi now runs apt and dpkg on the host. As such, we now require apt and dpkg to be installed on the host along with debootstrap in order to be able to build debian/ubuntu images.

• Split dm-verity artifacts default names have been changed to match what systemd and other tools expect: image.root.raw, image.root.verity, image.root.roothash, image.root.roothash.p7s (same for usr variants).

• mkosi will again default to the same OS release as the host system when the host system uses the same distribution as the image that's being built.

• By default, mkosi will now change the owner of newly created directories to SUDO_UID or PKEXEC_UID if defined, unless --no-chown is used.

• If systemd-nspawn v252 or newer is used, bind-mounted directories with systemd-nspawn will use the new rootidmap option so files and directories created from within the container will be owned by the actual directory owner on the host.

• The --network-veth option has been renamed to --netdev. The old name made sense with virtual ethernet devices, but when booting images with qemu a TUN/TAP device is used instead.
• The network config file installed by mkosi when the --netdev (previously --network-veth) option is used (formerly
  /etc/systemd/network/80-mkosi-network-veth.network in the image) now only matches network interfaces using the virtio_net driver. Please make sure you weren't relying on this file to configure any network interfaces other than the tun/tap virtio-net interface created by mkosi when booting the image in QEMU with the --netdev option. If you were relying on this config file
  to configure other interfaces, you'll have to re-create it with the correct match and a lower initial number in the filename to make sure systemd-networkd will keep configuring your interface, e.g. via the mkosi.skeleton or mkosi.extra trees or a mkosi.postinst script.
• The kernel-install script for building unified kernel images has been removed. From v13 onwards, on systems using kernel-install, mkosi won't automatically build new unified kernel images when a kernel is updated or installed. To keep the old behavior, you can install the kernel-install script manually via a skeleton tree; a copy can be found here.
• New QemuKvm option configures whether to use KVM when running mkosi qemu.
• mkosi will not default to the same OS release as the host system anymore when the host system uses the same distribution as the image that's being built. Instead, when no release is specified, mkosi will now always default to the default version embedded in mkosi itself.
• mkosi will now use the pacman keyring from the host when building Arch images. This means that users will, on top of installing archlinux-keyring, also have to run pacman-key --init and pacman-key --populate archlinux on
  the host system to be able to build Arch images. Also, unless the package manager is configured to do it automatically, the host keyring will have to be updated after archlinux-keyring updates by running pacman-key --populate archlinux and pacman-key --updatedb.
• Direct qemu linux boot is now supported with BootProtocols=linux. When enabled, the kernel image, initrd, and cmdline will be extracted from the image and passed to qemu by mkosi qemu to directly boot into the kernel image without a bootloader. This can be used to boot for example s390x images in qemu.
• The initrd will now always be rebuilt after the extra trees and build artifacts have been installed into the image.
• The github action has been migrated to Ubuntu Jammy. To migrate any jobs using the action, add runs-on: ubuntu-22.04 to the job config.
• All images are now configured by default with the C.UTF-8 locale.
• New --repository-directory option can be used to configure a directory with extra repository files to be used by the package manager when building an image. Note that this option is currently only supported for pacman and
  dnf-based distros.
• Option --skeleton-tree is now supported on Debian-based distros.

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