NEWS

systemd System and Service Manager

CHANGES WITH 254 in spe:

        Security relevant changes:

        * pam_systemd will now by default pass the CAP_WAKE_ALARM ambient
          process capability to invoked session processes of regular users on
          local seats (as well as to systemd --user), unless configured
          otherwise via data from JSON user records, or via the PAM module's
          parameter list. This is useful in order allow desktop tools such as
          GNOME's Alarm Clock application to set a timer for
          CLOCK_REALTIME_ALARM that wakes up the system when it elapses. A
          per-user service unit file may thus use AmbientCapability= to pass
          the capability to invoked processes. Note that this capability is
          relatively narrow in focus (in particular compared to other process
          capabilities such as CAP_SYS_ADMIN) and we already — by default —
          permit more impactful operations such as system suspend to local
          users.

CHANGES WITH 253:

        Announcements of Future Feature Removals and Incompatible Changes:

        * We intend to remove cgroup v1 support from systemd release after the
          end of 2023. If you run services that make explicit use of cgroup v1
          features (i.e. the "legacy hierarchy" with separate hierarchies for
          each controller), please implement compatibility with cgroup v2 (i.e.
          the "unified hierarchy") sooner rather than later. Most of Linux
          userspace has been ported over already.

        * We intend to remove support for split-usr (/usr mounted separately
          during boot) and unmerged-usr (parallel directories /bin and
          /usr/bin, /lib and /usr/lib, etc). This will happen in the second
          half of 2023, in the first release that falls into that time window.
          For more details, see:
          https://lists.freedesktop.org/archives/systemd-devel/2022-September/048352.html

        * We intend to change behaviour w.r.t. units of the per-user service
          manager and sandboxing options, so that they work without having to
          manually enable PrivateUsers= as well, which is not required for
          system units. To make this work, we will implicitly enable user
          namespaces (PrivateUsers=yes) when a sandboxing option is enabled in a
          user unit. The drawback is that system users will no longer be visible
          (and appear as 'nobody') to the user unit when a sandboxing option is
          enabled. By definition a sandboxed user unit should run with reduced
          privileges, so impact should be small. This will remove a great source
          of confusion that has been reported by users over the years, due to
          how these options require an extra setting to be manually enabled when
          used in the per-user service manager, as opposed as to the system
          service manager. We plan to enable this change in the next release
          later this year. For more details, see:
          https://lists.freedesktop.org/archives/systemd-devel/2022-December/048682.html

        Deprecations and incompatible changes:

        * systemctl will now warn when invoked without /proc/ mounted
          (e.g. when invoked after chroot() into an directory tree without the
          API mount points like /proc/ being set up.)  Operation in such an
          environment is not fully supported.

        * The return value of 'systemctl is-active|is-enabled|is-failed' for
          unknown units is changed: previously 1 or 3 were returned, but now 4
          (EXIT_PROGRAM_OR_SERVICES_STATUS_UNKNOWN) is used as documented.

        * 'udevadm hwdb' subcommand is deprecated and will emit a warning.
          systemd-hwdb (added in 2014) should be used instead.

        * 'bootctl --json' now outputs a single JSON array, instead of a stream
          of newline-separated JSON objects.

        * Udev rules in 60-evdev.rules have been changed to load hwdb
          properties for all modalias patterns. Previously only the first
          matching pattern was used. This could change what properties are
          assigned if the user has more and less specific patterns that could
          match the same device, but it is expected that the change will have
          no effect for most users.

        * systemd-networkd-wait-online exits successfully when all interfaces
          are ready or unmanaged. Previously, if neither '--any' nor
          '--interface=' options were used, at least one interface had to be in
          configured state. This change allows the case where systemd-networkd
          is enabled, but no interfaces are configured, to be handled
          gracefully. It may occur in particular when a different network
          manager is also enabled and used.

        * Some compatibility helpers were dropped: EmergencyAction= in the user
          manager, as well as measuring kernel command line into PCR 8 in
          systemd-stub, along with the -Defi-tpm-pcr-compat compile-time
          option.

        * The '-Dupdate-helper-user-timeout=' build-time option has been
          renamed to '-Dupdate-helper-user-timeout-sec=', and now takes an
          integer as parameter instead of a string.

        * The DDI image dissection logic (which backs RootImage= in service
          unit files, the --image= switch in various tools such as
          systemd-nspawn, as well as systemd-dissect) will now only mount file
          systems of types btrfs, ext4, xfs, erofs, squashfs, vfat. This list
          can be overridden via the $SYSTEMD_DISSECT_FILE_SYSTEMS environment
          variable. These file systems are fairly well supported and maintained
          in current kernels, while others are usually more niche, exotic or
          legacy and thus typically do not receive the same level of security
          support and fixes.

        * The default per-link multicast DNS mode is changed to "yes"
          (that was previously "no"). As the default global multicast DNS mode
          has been "yes" (but can be changed by the build option), now the
          multicast DNS is enabled on all links by default. You can disable the
          multicast DNS on all links by setting MulticastDNS= in resolved.conf,
          or on an interface by calling "resolvectl mdns INTERFACE no".

        New components:

        * A tool 'ukify' tool to build, measure, and sign Unified Kernel Images
          (UKIs) has been added. This replaces functionality provided by
          'dracut --uefi' and extends it with automatic calculation of PE file
          offsets, insertion of signed PCR policies generated by
          systemd-measure, support for initrd concatenation, signing of the
          embedded Linux image and the combined image with sbsign, and
          heuristics to autodetect the kernel uname and verify the splash
          image.

        Changes in systemd and units:

        * A new service type Type=notify-reload is defined. When such a unit is
          reloaded a UNIX process signal (typically SIGHUP) is sent to the main
          service process. The manager will then wait until it receives a
          "RELOADING=1" followed by a "READY=1" notification from the unit as
          response (via sd_notify()). Otherwise, this type is the same as
          Type=notify. A new setting ReloadSignal= may be used to change the
          signal to send from the default of SIGHUP.

          user@.service, systemd-networkd.service, systemd-udevd.service, and
          systemd-logind have been updated to this type.

        * Initrd environments which are not on a pure memory file system (e.g.
          overlayfs combination as opposed to tmpfs) are now supported. With
          this change, during the initrd → host transition ("switch root")
          systemd will erase all files of the initrd only when the initrd is
          backed by a memory file system such as tmpfs.

        * New per-unit MemoryZSwapMax= option has been added to configure
          memory.zswap.max cgroup properties (the maximum amount of zswap
          used).

        * A new LogFilterPatterns= option has been added for units. It may be
          used to specify accept/deny regular expressions for log messages
          generated by the unit, that shall be enforced by systemd-journald.
          Rejected messages are neither stored in the journal nor forwarded.
          This option may be used to suppress noisy or uninteresting messages
          from units.

        * The manager has a new
          org.freedesktop.systemd1.Manager.GetUnitByPIDFD() D-Bus method to
          query process ownership via a PIDFD, which is more resilient against
          PID recycling issues.

        * Scope units now support OOMPolicy=. Login session scopes default to
          OOMPolicy=continue, allowing login scopes to survive the OOM killer
          terminating some processes in the scope.

        * systemd-fstab-generator now supports x-systemd.makefs option for
          /sysroot/ (in the initrd).

        * The maximum rate at which daemon reloads are executed can now be
          limited with the new ReloadLimitIntervalSec=/ReloadLimitBurst=
          options. (Or the equivalent on the kernel command line:
          systemd.reload_limit_interval_sec=/systemd.reload_limit_burst=). In
          addition, systemd now logs the originating unit and PID when a reload
          request is received over D-Bus.

        * When enabling a swap device systemd will now reinitialize the device
          when the page size of the swap space does not match the page size of
          the running kernel. Note that this requires the 'swapon' utility to
          provide the '--fixpgsz' option, as implemented by util-linux, and it
          is not supported by busybox at the time of writing.

        * systemd now executes generator programs in a mount namespace
          "sandbox" with most of the file system read-only and write access
          restricted to the output directories, and with a temporary /tmp/
          mount provided. This provides a safeguard against programming errors
          in the generators, but also fixes here-docs in shells, which
          previously didn't work in early boot when /tmp/ wasn't available
          yet. (This feature has no security implications, because the code is
          still privileged and can trivially exit the sandbox.)

        * The system manager will now parse a new "vmm.notify_socket"
          system credential, which may be supplied to a VM via SMBIOS. If
          found, the manager will send a "READY=1" notification on the
          specified socket after boot is complete. This allows readiness
          notification to be sent from a VM guest to the VM host over a VSOCK
          socket.

        * The sample PAM configuration file for systemd-user@.service now
          includes a call to pam_namespace. This puts children of user@.service
          in the expected namespace. (Many distributions replace their file
          with something custom, so this change has limited effect.)

        * A new environment variable $SYSTEMD_DEFAULT_MOUNT_RATE_LIMIT_BURST
          can be used to override the mount units burst late limit for
          parsing '/proc/self/mountinfo', which was introduced in v249.
          Defaults to 5.

        * Drop-ins for init.scope changing control group resource limits are
          now applied, while they were previously ignored.

        * New build-time configuration options '-Ddefault-timeout-sec=' and
          '-Ddefault-user-timeout-sec=' have been added, to let distributions
          choose the default timeout for starting/stopping/aborting system and
          user units respectively.

        * Service units gained a new setting OpenFile= which may be used to
          open arbitrary files in the file system (or connect to arbitrary
          AF_UNIX sockets in the file system), and pass the open file
          descriptor to the invoked process via the usual file descriptor
          passing protocol. This is useful to give unprivileged services access
          to select files which have restrictive access modes that would
          normally not allow this. It's also useful in case RootDirectory= or
          RootImage= is used to allow access to files from the host environment
          (which is after all not visible from the service if these two options
          are used.)

        Changes in udev:

        * The new net naming scheme "v253" has been introduced. In the new
          scheme, ID_NET_NAME_PATH is also set for USB devices not connected via
          a PCI bus. This extends the coverage of predictable interface names
          in some embedded systems.

          The "amba" bus path is now included in ID_NET_NAME_PATH, resulting in
          a more informative path on some embedded systems.

        * Partition block devices will now also get symlinks in
          /dev/disk/by-diskseq/<seq>-part<n>, which may be used to reference
          block device nodes via the kernel's "diskseq" value. Previously those
          symlinks were only created for the main block device.

        * A new operator '-=' is supported for SYMLINK variables. This allows
          symlinks to be unconfigured even if an earlier rule added them.

        * 'udevadm --trigger --settle' now also works for network devices
          that are being renamed.

        Changes in sd-boot, bootctl, and the Boot Loader Specification:

        * systemd-boot now passes its random seed directly to the kernel's RNG
          via the LINUX_EFI_RANDOM_SEED_TABLE_GUID configuration table, which
          means the RNG gets seeded very early in boot before userspace has
          started.

        * systemd-boot will pass a disk-backed random seed – even when secure
          boot is enabled – if it can additionally get a random seed from EFI
          itself (via EFI's RNG protocol), or a prior seed in
          LINUX_EFI_RANDOM_SEED_TABLE_GUID from a preceding bootloader.

        * systemd-boot-system-token.service was renamed to
          systemd-boot-random-seed.service and extended to always save a random
          seed to ESP on every boot when a compatible boot loader is used. This
          allows a refreshed random seed to be used in the boot loader.

        * systemd-boot handles various seed inputs using a domain- and
          field-separated hashing scheme.

        * systemd-boot's 'random-seed-mode' option has been removed. A system
          token is now always required to be present for random seeds to be
          used.

        * systemd-boot now supports being loaded from other locations than the
          ESP, for example for direct kernel boot under QEMU or when embedded
          into the firmware.

        * systemd-boot now parses SMBIOS information to detect
          virtualization. This information is used to skip some warnings which
          are not useful in a VM and to conditionalize other aspects of
          behaviour.

        * systemd-boot now supports a new 'if-safe' mode that will perform UEFI
          Secure Boot automated certificate enrollment from the ESP only if it
          is considered 'safe' to do so. At the moment 'safe' means running in
          a virtual machine.

        * systemd-stub now processes random seeds in the same way as
          systemd-boot already does, in case a unified kernel image is being
          used from a different bootloader than systemd-boot, or without any
          boot load at all.

        * bootctl will now generate a system token on all EFI systems, even
          virtualized ones, and is activated in the case that the system token
          is missing from either sd-boot and sd-stub booted systems.

        * bootctl now implements two new verbs: 'kernel-identify' prints the
          type of a kernel image file, and 'kernel-inspect' provides
          information about the embedded command line and kernel version of
          UKIs.

        * bootctl now honours $KERNEL_INSTALL_CONF_ROOT with the same meaning
          as for kernel-install.

        * The JSON output of "bootctl list" will now contain two more fields:
          isDefault and isSelected are boolean fields set to true on the
          default and currently booted boot menu entries.

        * bootctl gained a new verb "unlink" for removing a boot loader entry
          type #1 file from disk in a safe and robust way.

        * bootctl also gained a new verb "cleanup" that automatically removes
          all files from the ESP's and XBOOTLDR's "entry-token" directory, that
          is not referenced anymore by any installed Type #1 boot loader
          specification entry. This is particularly useful in environments where
          a large number of entries reference the same or partly the same
          resources (for example, for snapshot-based setups).

        Changes in kernel-install:

        * A new "installation layout" can be configured as layout=uki. With
          this setting, a Boot Loader Specification Type#1 entry will not be
          created.  Instead, a new kernel-install plugin 90-uki-copy.install
          will copy any .efi files from the staging area into the boot
          partition. A plugin to generate the UKI .efi file must be provided
          separately.

        Changes in systemctl:

        * 'systemctl reboot' has dropped support for accepting a positional
          argument as the argument to the reboot(2) syscall. Please use the
          --reboot-argument= option instead.

        * 'systemctl disable' will now warn when called on units without
          install information. A new --no-warn option has been added that
          silences this warning.

        * New option '--drop-in=' can be used to tell 'systemctl edit' the name
          of the drop-in to edit. (Previously, 'override.conf' was always
          used.)

        * 'systemctl list-dependencies' now respects --type= and --state=.

        * 'systemctl kexec' now supports XEN VMM environments.

        * 'systemctl edit' will now tell the invoked editor to jump into the
          first line with actual unit file data, skipping over synthesized
          comments.

        Changes in systemd-networkd and related tools:

        * The [DHCPv4] section in .network file gained new SocketPriority=
          setting that assigns the Linux socket priority used by the DHCPv4 raw
          socket. This may be used in conjunction with the
          EgressQOSMaps=setting in [VLAN] section of .netdev file to send the
          desired ethernet 802.1Q frame priority for DHCPv4 initial
          packets. This cannot be achieved with netfilter mangle tables because
          of the raw socket bypass.

        * The [DHCPv4] and [IPv6AcceptRA] sections in .network file gained a
          new QuickAck= boolean setting that enables the TCP quick ACK mode for
          the routes configured by the acquired DHCPv4 lease or received router
          advertisements (RAs).

        * The RouteMetric= option (for DHCPv4, DHCPv6, and IPv6 advertised
          routes) now accepts three values, for high, medium, and low preference
          of the router (which can be set with the RouterPreference=) setting.

        * systemd-networkd-wait-online now supports matching via alternative
          interface names.

        * The [DHCPv6] section in .network file gained new SendRelease=
          setting which enables the DHCPv6 client to send release when
          it stops. This is the analog of the [DHCPv4] SendRelease= setting.
          It is enabled by default.

        * If the Address= setting in [Network] or [Address] sections in .network
          specified without its prefix length, then now systemd-networkd assumes
          /32 for IPv4 or /128 for IPv6 addresses.

        * networkctl shows network and link file dropins in status output.

        Changes in systemd-dissect:

        * systemd-dissect gained a new option --list, to print the paths of
          all files and directories in a DDI.

        * systemd-dissect gained a new option --mtree, to generate a file
          manifest compatible with BSD mtree(5) of a DDI

        * systemd-dissect gained a new option --with, to execute a command with
          the specified DDI temporarily mounted and used as working
          directory. This is for example useful to convert a DDI to "tar"
          simply by running it within a "systemd-dissect --with" invocation.

        * systemd-dissect gained a new option --discover, to search for
          Discoverable Disk Images (DDIs) in well-known directories of the
          system. This will list machine, portable service and system extension
          disk images.

        * systemd-dissect now understands 2nd stage initrd images stored as a
          Discoverable Disk Image (DDI).

        * systemd-dissect will now display the main UUID of GPT DDIs (i.e. the
          disk UUID stored in the GPT header) among the other data it can show.

        * systemd-dissect gained a new --in-memory switch to operate on an
          in-memory copy of the specified DDI file. This is useful to access a
          DDI with write access without persisting any changes. It's also
          useful for accessing a DDI without keeping the originating file
          system busy.

        * The DDI dissection logic will now automatically detect the intended
          sector size of disk images stored in files, based on the GPT
          partition table arrangement. Loopback block devices for such DDIs
          will then be configured automatically for the right sector size. This
          is useful to make dealing with modern 4K sector size DDIs fully
          automatic. The systemd-dissect tool will now show the detected sector
          size among the other DDI information in its output.

        Changes in systemd-repart:

        * systemd-repart gained new options --include-partitions= and
          --exclude-partitions= to filter operation on partitions by type UUID.
          This allows systemd-repart to be used to build images in which the
          type of one partition is set based on the contents of another
          partition (for example when the boot partition shall include a verity
          hash of the root partition).

        * systemd-repart also gained a --defer-partitions= option that is
          similar to --exclude-partitions=, but the size of the partition is
          still taken into account when sizing partitions, but without
          populating it.

        * systemd-repart gained a new --sector-size= option to specify what
          sector size should be used when an image is created.

        * systemd-repart now supports generating erofs file systems via
          CopyFiles= (a read-only file system similar to squashfs).

        * The Minimize= option was extended to accept "best" (which means the
          most minimal image possible, but may require multiple attempts) and
          "guess" (which means a reasonably small image).

        * The systemd-growfs binary now comes with a regular unit file template
          systemd-growfs@.service which can be instantiated directly for any
          desired file system. (Previously, the unit was generated dynamically
          by various generators, but no regular unit file template was
          available.)

        Changes in journal tools:

        * Various systemd tools will append extra fields to log messages when
          in debug mode, or when SYSTEMD_ENABLE_LOG_CONTEXT=1 is set. Currently
          this includes information about D-Bus messages when sd-bus is used,
          e.g. DBUS_SENDER=, DBUS_DESTINATION=, and DBUS_PATH=, and information
          about devices when sd-device is used, e.g. DEVNAME= and DRIVER=.
          Details of what is logged and when are subject to change.

        * The systemd-journald-audit.socket can now be disabled via the usual
          "systemctl disable" mechanism to stop collection of audit
          messages. Please note that it is not enabled statically anymore and
          must be handled by the preset/enablement logic in package
          installation scripts.

        * New options MaxUse=, KeepFree=, MaxFileSize=, and MaxFiles= can
          be used to curtail disk use by systemd-journal-remote. This is
          similar to the options supported by systemd-journald.

        Changes in systemd-cryptenroll, systemd-cryptsetup, and related
        components:

        * When enrolling new keys systemd-cryptenroll now supports unlocking
          via FIDO2 tokens (option --unlock-fido2-device=). Previously, a
          password was strictly required to be specified.

        * systemd-cryptsetup now supports pre-flight requests for FIDO2 tokens
          (except for tokens with user verification, UV) to identify tokens
          before authentication. Multiple FIDO2 tokens can now be enrolled at
          the same time, and systemd-cryptsetup will automatically select one
          that corresponds to one of the available LUKS key slots.

        * systemd-cryptsetup now supports new options tpm2-measure-bank= and
          tpm2-measure-pcr= in crypttab(5). These allow specifying the TPM2 PCR
          bank and number into which the volume key should be measured. This is
          automatically enabled for the encrypted root volume discovered and
          activated by systemd-gpt-auto-generator.

        * systemd-gpt-auto-generator mounts the ESP and XBOOTLDR partitions with
          "noexec,nosuid,nodev".

        * systemd-gpt-auto-generator will now honour the rootfstype= and
          rootflags= kernel command line switches for root file systems it
          discovers, to match behaviour in case an explicit root fs is
          specified via root=.

        * systemd-pcrphase gained new options --machine-id and --file-system=
          to measure the machine-id and mount point information into PCR 15. New
          service unit files systemd-pcrmachine.service and
          systemd-pcrfs@.service have been added that invoke the tool with
          these switches during early boot.

        * systemd-pcrphase gained a --graceful switch will make it exit cleanly
          with a success exit code even if no TPM device is detected.

        * systemd-cryptenroll now stores the user-supplied PIN with a salt,
          making it harder to brute-force.

        Changes in other tools:

        * systemd-homed gained support for luksPbkdfForceIterations (the
          intended number of iterations for the PBKDF operation on LUKS).

        * Environment variables $SYSTEMD_HOME_MKFS_OPTIONS_BTRFS,
          $SYSTEMD_HOME_MKFS_OPTIONS_EXT4, and $SYSTEMD_HOME_MKFS_OPTIONS_XFS
          may now be used to specify additional arguments for mkfs when
          systemd-homed formats a file system.

        * systemd-hostnamed now exports the contents of
          /sys/class/dmi/id/bios_vendor and /sys/class/dmi/id/bios_date via two
          new D-Bus properties: FirmwareVendor and FirmwareDate. This allows
          unprivileged code to access those values.

          systemd-hostnamed also exports the SUPPORT_END= field from
          os-release(5) as OperatingSystemSupportEnd. hostnamectl make uses of
          this to show the status of the installed system.

        * systemd-measure gained an --append= option to sign multiple phase
          paths with different signing keys. This allows secrets to be
          accessible only in certain parts of the boot sequence. Note that
          'ukify' provides similar functionality in a more accessible form.

        * systemd-timesyncd will now write a structured log message with
          MESSAGE_ID set to SD_MESSAGE_TIME_BUMP when it bumps the clock based
          on a on-disk timestamp, similarly to what it did when reaching
          synchronization via NTP.

        * systemd-timesyncd will now update the on-disk timestamp file on each
          boot at least once, making it more likely that the system time
          increases in subsequent boots.

        * systemd-vconsole-setup gained support for system/service credentials:
          vconsole.keymap/vconsole.keymap_toggle and
          vconsole.font/vconsole.font_map/vconsole.font_unimap are analogous
          the similarly-named options in vconsole.conf.

        * systemd-localed will now save the XKB keyboard configuration to
          /etc/vconsole.conf, and also read it from there with a higher
          preference than the /etc/X11/xorg.conf.d/00-keyboard.conf config
          file. Previously, this information was stored in the former file in
          converted form, and only in latter file in the original form. Tools
          which want to access keyboard configuration can now do so from a
          standard location.

        * systemd-resolved gained support for configuring the nameservers and
          search domains via kernel command line (nameserver=, domain=) and
          credentials (network.dns, network.search_domains).

        * systemd-resolved will now synthesize host names for the DNS stub
          addresses it supports. Specifically when "_localdnsstub" is resolved,
          127.0.0.53 is returned, and if "_localdnsproxy" is resolved
          127.0.0.54 is returned.

        * systemd-notify will now send a "RELOADING=1" notification when called
          with --reloading, and "STOPPING=1" when called with --stopping. This
          can be used to implement notifications from units where it's easier
          to call a program than to use the sd-daemon library.

        * systemd-analyze's 'plot' command can now output its information in
          JSON, controlled via the --json= switch. Also, new --table, and
          --no-legend options have been added.

        * 'machinectl enable' will now automatically enable machines.target
          unit in addition to adding the machine unit to the target.

          Similarly, 'machinectl start|stop' gained a --now option to enable or
          disable the machine unit when starting or stopping it.

        * systemd-sysusers will now create /etc/ if it is missing.

        * systemd-sleep 'HibernateDelaySec=' setting is changed back to
          pre-v252's behaviour, and a new 'SuspendEstimationSec=' setting is
          added to provide the new initial value for the new automated battery
          estimation functionality. If 'HibernateDelaySec=' is set to any value,
          the automated estimate (and thus the automated hibernation on low
          battery to avoid data loss) functionality will be disabled.

        * Default tmpfiles.d/ configuration will now automatically create
          credentials storage directory '/etc/credstore/' with the appropriate,
          secure permissions. If '/run/credstore/' exists, its permissions will
          be fixed too in case they are not correct.

        Changes in libsystemd and shared code:

        * sd-bus gained new convenience functions sd_bus_emit_signal_to(),
          sd_bus_emit_signal_tov(), and sd_bus_message_new_signal_to().

        * sd-id128 functions now return -EUCLEAN (instead of -EIO) when the
          128bit ID in files such as /etc/machine-id has an invalid
          format. They also accept NULL as output parameter in more places,
          which is useful when the caller only wants to validate the inputs and
          does not need the output value.

        * sd-login gained new functions sd_pidfd_get_session(),
          sd_pidfd_get_owner_uid(), sd_pidfd_get_unit(),
          sd_pidfd_get_user_unit(), sd_pidfd_get_slice(),
          sd_pidfd_get_user_slice(), sd_pidfd_get_machine_name(), and
          sd_pidfd_get_cgroup(), that are analogous to sd_pid_get_*(),
          but accept a PIDFD instead of a PID.

        * sd-path (and systemd-path) now export four new paths:
          SD_PATH_SYSTEMD_SYSTEM_ENVIRONMENT_GENERATOR,
          SD_PATH_SYSTEMD_USER_ENVIRONMENT_GENERATOR,
          SD_PATH_SYSTEMD_SEARCH_SYSTEM_ENVIRONMENT_GENERATOR, and
          SD_PATH_SYSTEMD_SEARCH_USER_ENVIRONMENT_GENERATOR,

        * sd_notify() now supports AF_VSOCK as transport for notification
          messages (in addition to the existing AF_UNIX support). This is
          enabled if $NOTIFY_SOCKET is set in a "vsock:CID:port" format.

        * Detection of chroot() environments now works if /proc/ is not
          mounted.  This affects systemd-detect-virt --chroot, but also means
          that systemd tools will silently skip various operations in such an
          environment.

        * "Lockheed Martin Hardened Security for Intel Processors" (HS SRE)
          virtualization is now detected.

        Changes in the build system:

        * Standalone variants of systemd-repart and systemd-shutdown may now be
          built (if -Dstandalone=true).

        * systemd-ac-power has been moved from /usr/lib/ to /usr/bin/, to, for
          example, allow scripts to conditionalize execution on AC power
          supply.

        * The libp11kit library is now loaded through dlopen(3).

        Changes in the documentation:

        * Specifications that are not closely tied to systemd have moved to
          https://uapi-group.org/specifications/: the Boot Loader Specification
          and the Discoverable Partitions Specification.

        Contributions from: 김인수, 13r0ck, Aidan Dang, Alberto Planas,
        Alvin Šipraga, Andika Triwidada, AndyChi, angus-p, Anita Zhang,
        Antonio Alvarez Feijoo, Arsen Arsenović, asavah, Benjamin Fogle,
        Benjamin Tissoires, berenddeschouwer, BerndAdameit,
        Bernd Steinhauser, blutch112, cake03, Callum Farmer, Carlo Teubner,
        Charles Hardin, chris, Christian Brauner, Christian Göttsche,
        Cristian Rodríguez, Daan De Meyer, Dan Streetman, DaPigGuy,
        Darrell Kavanagh, David Tardon, dependabot[bot], Dirk Su,
        Dmitry V. Levin, drosdeck, Edson Juliano Drosdeck, edupont,
        Eric DeVolder, Erik Moqvist, Evgeny Vereshchagin, Fabian Gurtner,
        Felix Riemann, Franck Bui, Frantisek Sumsal, Geert Lorang,
        Gerd Hoffmann, Gio, Hannoskaj, Hans de Goede, Hugo Carvalho,
        igo95862, Ilya Leoshkevich, Ivan Shapovalov, Jacek Migacz,
        Jade Lovelace, Jan Engelhardt, Jan Janssen, Jan Macku, January,
        Jason A. Donenfeld, jcg, Jean-Tiare Le Bigot, Jelle van der Waa,
        Jeremy Linton, Jian Zhang, Jiayi Chen, Jia Zhang, Joerg Behrmann,
        Jörg Thalheim, Joshua Goins, joshuazivkovic, Joshua Zivkovic,
        Kai-Chuan Hsieh, Khem Raj, Koba Ko, Lennart Poettering, lichao,
        Li kunyu, Luca Boccassi, Luca BRUNO, Ludwig Nussel,
        Łukasz Stelmach, Lycowolf, marcel151, Marcus Schäfer, Marek Vasut,
        Mark Laws, Michael Biebl, Michał Kotyla, Michal Koutný,
        Michal Sekletár, Mike Gilbert, Mike Yuan, MkfsSion, ml,
        msizanoen1, mvzlb, MVZ Ludwigsburg, Neil Moore, Nick Rosbrook,
        noodlejetski, Pasha Vorobyev, Peter Cai, p-fpv, Phaedrus Leeds,
        Philipp Jungkamp, Quentin Deslandes, Raul Tambre, Ray Strode,
        reuben olinsky, Richard E. van der Luit, Richard Phibel,
        Ricky Tigg, Robin Humble, rogg, Rudi Heitbaum, Sam James,
        Samuel Cabrero, Samuel Thibault, Siddhesh Poyarekar, Simon Brand,
        Space Meyer, Spindle Security, Steve Ramage, Takashi Sakamoto,
        Thomas Haller, Tonći Galić, Topi Miettinen, Torsten Hilbrich,
        Tuetuopay, uerdogan, Ulrich Ölmann, Valentin David,
        Vitaly Kuznetsov, Vito Caputo, Waltibaba, Will Fancher,
        William Roberts, wouter bolsterlee, Youfu Zhang, Yu Watanabe,
        Zbigniew Jędrzejewski-Szmek, Дамјан Георгиевски,
        наб

        — Warsaw, 2023-02-15

CHANGES WITH 252 🎃:

        Announcements of Future Feature Removals:

        * We intend to remove cgroup v1 support from systemd release after the
          end of 2023. If you run services that make explicit use of cgroup v1
          features (i.e. the "legacy hierarchy" with separate hierarchies for
          each controller), please implement compatibility with cgroup v2 (i.e.
          the "unified hierarchy") sooner rather than later. Most of Linux
          userspace has been ported over already.

        * We intend to remove support for split-usr (/usr mounted separately
          during boot) and unmerged-usr (parallel directories /bin and
          /usr/bin, /lib and /usr/lib, etc). This will happen in the second
          half of 2023, in the first release that falls into that time window.
          For more details, see:
          https://lists.freedesktop.org/archives/systemd-devel/2022-September/048352.html

        Compatibility Breaks:

        * ConditionKernelVersion= checks that use the '=' or '!=' operators
          will now do simple string comparisons (instead of version comparisons
          à la stverscmp()). Version comparisons are still done for the
          ordering operators '<', '>', '<=', '>='. Moreover, if no operator is
          specified, a shell-style glob match is now done. This creates a minor
          incompatibility compared to older systemd versions when the '*', '?',
          '[', ']' characters are used, as these will now match as shell globs
          instead of literally. Given that kernel version strings typically do
          not include these characters we expect little breakage through this
          change.

        * The service manager will now read the SELinux label used for SELinux
          access checks from the unit file at the time it loads the file.
          Previously, the label would be read at the moment of the access
          check, which was problematic since at that time the unit file might
          already have been updated or removed.

        New Features:

        * systemd-measure is a new tool for calculating and signing expected
          TPM2 PCR values for a given unified kernel image (UKI) booted via
          sd-stub. The public key used for the signature and the signed
          expected PCR information can be embedded inside the UKI. This
          information can be extracted from the UKI by external tools and code
          in the image itself and is made available to userspace in the booted
          kernel.

          systemd-cryptsetup, systemd-cryptenroll, and systemd-creds have been
          updated to make use of this information if available in the booted
          kernel: when locking an encrypted volume/credential to the TPM
          systemd-cryptenroll/systemd-creds will use the public key to bind the
          volume/credential to any kernel that carries PCR information signed
          by the same key pair. When unlocking such volumes/credentials
          systemd-cryptsetup/systemd-creds will use the signature embedded in
          the booted UKI to gain access.

          Binding TPM-based disk encryption to public keys/signatures of PCR
          values — instead of literal PCR values — addresses the inherent
          "brittleness" of traditional PCR-bound TPM disk encryption schemes:
          disks remain accessible even if the UKI is updated, without any TPM
          specific preparation during the OS update — as long as each UKI
          carries the necessary PCR signature information.

          Net effect: if you boot a properly prepared kernel, TPM-bound disk
          encryption now defaults to be locked to kernels which carry PCR
          signatures from the same key pair. Example: if a hypothetical distro
          FooOS prepares its UKIs like this, TPM-based disk encryption is now –
          by default – bound to only FooOS kernels, and encrypted volumes bound
          to the TPM cannot be unlocked on kernels from other sources. (But do
          note this behaviour requires preparation/enabling in the UKI, and of
          course users can always enroll non-TPM ways to unlock the volume.)

        * systemd-pcrphase is a new tool that is invoked at six places during
          system runtime, and measures additional words into TPM2 PCR 11, to
          mark milestones of the boot process. This allows binding access to
          specific TPM2-encrypted secrets to specific phases of the boot
          process. (Example: LUKS2 disk encryption key only accessible in the
          initrd, but not later.)

        Changes in systemd itself, i.e. the manager and units

        * The cpu controller is delegated to user manager units by default, and
          CPUWeight= settings are applied to the top-level user slice units
          (app.slice, background.slice, session.slice). This provides a degree
          of resource isolation between different user services competing for
          the CPU.

        * Systemd can optionally do a full preset in the "first boot" condition
          (instead of just enable-only). This behaviour is controlled by the
          compile-time option -Dfirst-boot-full-preset. Right now it defaults
          to 'false', but the plan is to switch it to 'true' for the subsequent
          release.

        * Drop-ins are now allowed for transient units too.

        * Systemd will set the taint flag 'support-ended' if it detects that
          the OS image is past its end-of-support date. This date is declared
          in a new /etc/os-release field SUPPORT_END= described below.

        * Two new settings ConditionCredential= and AssertCredential= can be
          used to skip or fail units if a certain system credential is not
          provided.

        * ConditionMemory= accepts size suffixes (K, M, G, T, …).

        * DefaultSmackProcessLabel= can be used in system.conf and user.conf to
          specify the SMACK security label to use when not specified in a unit
          file.

        * DefaultDeviceTimeoutSec= can be used in system.conf and user.conf to
          specify the default timeout when waiting for device units to
          activate.

        * C.UTF-8 is used as the default locale if nothing else has been
          configured.

        * [Condition|Assert]Firmware= have been extended to support certain
          SMBIOS fields. For example

            ConditionFirmware=smbios-field(board_name = "Custom Board")

          conditionalizes the unit to run only when
          /sys/class/dmi/id/board_name contains "Custom Board" (without the
          quotes).

        * ConditionFirstBoot= now correctly evaluates as true only during the
          boot phase of the first boot. A unit executed later, after booting
          has completed, will no longer evaluate this condition as true.

        * Socket units will now create sockets in the SELinuxContext= of the
          associated service unit, if any.

        * Boot phase transitions (start initrd → exit initrd → boot complete →
          shutdown) will be measured into TPM2 PCR 11, so that secrets can be
          bound to a specific runtime phase. E.g.: a LUKS encryption key can be
          unsealed only in the initrd.

        * Service credentials (i.e. SetCredential=/LoadCredential=/…) will now
          also be provided to ExecStartPre= processes.

        * Various units are now correctly ordered against
          initrd-switch-root.target where previously a conflict without
          ordering was configured. A stop job for those units would be queued,
          but without the ordering it could be executed only after
          initrd-switch-root.service, leading to units not being restarted in
          the host system as expected.

        * In order to fully support the IPMI watchdog driver, which has not yet
          been ported to the new common watchdog device interface,
          /dev/watchdog0 will be tried first and systemd will silently fallback
          to /dev/watchdog if it is not found.

        * New watchdog-related D-Bus properties are now published by systemd:
          WatchdogDevice, WatchdogLastPingTimestamp,
          WatchdogLastPingTimestampMonotonic.

        * At shutdown, API virtual files systems (proc, sys, etc.) will be
          unmounted lazily.

        * At shutdown, systemd will now log about processes blocking unmounting
          of file systems.

        * A new meson build option 'clock-valid-range-usec-max' was added to
          allow disabling system time correction if RTC returns a timestamp far
          in the future.

        * Propagated restart jobs will no longer be discarded while a unit is
          activating.

        * PID 1 will now import system credentials from SMBIOS Type 11 fields
          ("OEM vendor strings"), in addition to qemu_fwcfg. This provides a
          simple, fast and generic path for supplying credentials to a VM,
          without involving external tools such as cloud-init/ignition.

        * The CPUWeight= setting of unit files now accepts a new special value
          "idle", which configures "idle" level scheduling for the unit.

        * Service processes that are activated due to a .timer or .path unit
          triggering will now receive information about this via environment
          variables. Note that this is information is lossy, as activation
          might be coalesced and only one of the activating triggers will be
          reported. This is hence more suited for debugging or tracing rather
          than for behaviour decisions.

        * The riscv_flush_icache(2) system call has been added to the list of
          system calls allowed by default when SystemCallFilter= is used.

        * The selinux context derived from the target executable, instead of
          'init_t' used for the manager itself, is now used when creating
          listening sockets for units that specify SELinuxContextFromNet=yes.

        Changes in sd-boot, bootctl, and the Boot Loader Specification:

        * The Boot Loader Specification has been cleaned up and clarified.
          Various corner cases in version string comparisons have been fixed
          (e.g. comparisons for empty strings). Boot counting is now part of
          the main specification.

        * New PCRs measurements are performed during boot: PCR 11 for the
          kernel+initrd combo, PCR 13 for any sysext images. If a measurement
          took place this is now reported to userspace via the new
          StubPcrKernelImage and StubPcrInitRDSysExts EFI variables.

        * As before, systemd-stub will measure kernel parameters and system
          credentials into PCR 12. It will now report this fact via the
          StubPcrKernelParameters EFI variable to userspace.

        * The UEFI monotonic boot counter is now included in the updated random
          seed file maintained by sd-boot, providing some additional entropy.

        * sd-stub will use LoadImage/StartImage to execute the kernel, instead
          of arranging the image manually and jumping to the kernel entry
          point. sd-stub also installs a temporary UEFI SecurityOverride to
          allow the (unsigned) nested image to be booted. This is safe because
          the outer (signed) stub+kernel binary must have been verified before
          the stub was executed.

        * Booting in EFI mixed mode (a 64-bit kernel over 32-bit UEFI firmware)
          is now supported by sd-boot.

        * bootctl gained a bunch of new options: --all-architectures to install
          binaries for all supported EFI architectures, --root= and --image=
          options to operate on a directory or disk image, and
          --install-source= to specify the source for binaries to install,
          --efi-boot-option-description= to control the name of the boot entry.

        * The sd-boot stub exports a StubFeatures flag, which is used by
          bootctl to show features supported by the stub that was used to boot.

        * The PE section offsets that are used by tools that assemble unified
          kernel images have historically been hard-coded. This may lead to
          overlapping PE sections which may break on boot. The UKI will now try
          to detect and warn about this.

          Any tools that assemble UKIs must update to calculate these offsets
          dynamically. Future sd-stub versions may use offsets that will not
          work with the currently used set of hard-coded offsets!

        * sd-stub now accepts (and passes to the initrd and then to the full
          OS) new PE sections '.pcrsig' and '.pcrkey' that can be used to embed
          signatures of expected PCR values, to allow sealing secrets via the
          TPM2 against pre-calculated PCR measurements.

        Changes in the hardware database:

        * 'systemd-hwdb query' now supports the --root= option.

        Changes in systemctl:

        * systemctl now supports --state= and --type= options for the 'show'
          and 'status' verbs.

        * systemctl gained a new verb 'list-automounts' to list automount
          points.

        * systemctl gained support for a new --image= switch to be able to
          operate on the specified disk image (similar to the existing --root=
          which operates relative to some directory).

        Changes in systemd-networkd:

        * networkd can set Linux NetLabel labels for integration with the
          network control in security modules via a new NetLabel= option.

        * The RapidCommit= is (re-)introduced to enable faster configuration
          via DHCPv6 (RFC 3315).

        * networkd gained a new option TCPCongestionControlAlgorithm= that
          allows setting a per-route TCP algorithm.

        * networkd gained a new option KeepFileDescriptor= to allow keeping a
          reference (file descriptor) open on TUN/TAP interfaces, which is
          useful to avoid link flaps while the underlying service providing the
          interface is being serviced.

        * RouteTable= now also accepts route table names.

        Changes in systemd-nspawn:

        * The --bind= and --overlay= options now support relative paths.

        * The --bind= option now supports a 'rootidmap' value, which will
          use id-mapped mounts to map the root user inside the container to the
          owner of the mounted directory on the host.

        Changes in systemd-resolved:

        * systemd-resolved now persists DNSOverTLS in its state file too. This
          fixes a problem when used in combination with NetworkManager, which
          sends the setting only once, causing it to be lost if resolved was
          restarted at any point.

        * systemd-resolved now exposes a varlink socket at
          /run/systemd/resolve/io.systemd.Resolve.Monitor, accessible only for
          root. Processed DNS requests in a JSON format will be published to
          any clients connected to this socket.

          resolvectl gained a 'monitor' verb to make use of this.

        * systemd-resolved now treats unsupported DNSSEC algorithms as INSECURE
          instead of returning SERVFAIL, as per RFC:
          https://datatracker.ietf.org/doc/html/rfc6840#section-5.2

        * OpenSSL is the default crypto backend for systemd-resolved. (gnutls
          is still supported.)

        Changes in libsystemd and other libraries:

        * libsystemd now exports sd_bus_error_setfv() (a convenience function
          for setting bus errors), sd_id128_string_equal (a convenience
          function for 128bit ID string comparisons), and
          sd_bus_message_read_strv_extend() (a function to incrementally read
          string arrays).

        * libsystemd now exports sd_device_get_child_first()/_next() as a
          high-level interface for enumerating child devices. It also supports
          sd_device_new_child() for opening a child device given a device
          object.

        * libsystemd now exports sd_device_monitor_set()/get_description()
          which allow setting a custom description that will be used in log
          messages by sd_device_monitor*.

        * Private shared libraries (libsystemd-shared-nnn.so,
          libsystemd-core-nnn.so) are now installed into arch-specific
          directories to allow multi-arch installs.

        * A new sd-gpt.h header is now published, listing GUIDs from the
          Discoverable Partitions specification. For more details see:
          https://systemd.io/DISCOVERABLE_PARTITIONS/

        * A new function sd_hwdb_new_from_path() has been added to open a hwdb
          database given an explicit path to the file.

        * The signal number argument to sd_event_add_signal() now can now be
          ORed with the SD_EVENT_SIGNAL_PROCMASK flag, causing sigprocmask() to
          be automatically invoked to block the specified signal. This is
          useful to simplify invocations as the caller doesn't have to do this
          manually.

        * A new convenience call sd_event_set_signal_exit() has been added to
          sd-event to set up signal handling so that the event loop
          automatically terminates cleanly on SIGTERM/SIGINT.

        Changes in other components:

        * systemd-sysusers, systemd-tmpfiles, and systemd-sysctl configuration
          can now be provided via the credential mechanism.

        * systemd-analyze gained a new verb 'compare-versions' that implements
          comparisons for versions strings (similarly to 'rpmdev-vercmp' and
          'dpkg --compare-versions').

        * 'systemd-analyze dump' is extended to accept glob patterns for unit
          names to limit the output to matching units.

        * tmpfiles.d/ lines can read file contents to write from a credential.
          The new modifier char '^' is used to specify that the argument is a
          credential name. This mechanism is used to automatically populate
          /etc/motd, /etc/issue, and /etc/hosts from credentials.

        * tmpfiles.d/ may now be configured to avoid changing uid/gid/mode of
          an inode if the specification is prefixed with ':' and the inode
          already exists.

        * Default tmpfiles.d/ configuration now carries a line to automatically
          use an 'ssh.authorized_keys.root' credential if provided to set up
          the SSH authorized_keys file for the root user.

        * systemd-tmpfiles will now gracefully handle absent source of "C" copy
          lines.

        * tmpfiles.d/ F/w lines now optionally permit encoding of the payload
          in base64. This is useful to write arbitrary binary data into files.

        * The pkgconfig and rpm macros files now export the directory for user
          units as 'user_tmpfiles_dir' and '%_user_tmpfilesdir'.

        * Detection of Apple Virtualization and detection of Parallels and
          KubeVirt virtualization on non-x86 archs have been added.

        * os-release gained a new field SUPPORT_END=YYYY-MM-DD to inform the
          user when their system will become unsupported.

        * When performing suspend-then-hibernate, the system will estimate the
          discharge rate and use that to set the delay until hibernation and
          hibernate immediately instead of suspending when running from a
          battery and the capacity is below 5%.

        * systemd-sysctl gained a --strict option to fail when a sysctl
          setting is unknown to the kernel.

        * machinectl supports --force for the 'copy-to' and 'copy-from'
          verbs.

        * coredumpctl gained the --root and --image options to look for journal
          files under the specified root directory, image, or block device.

        * 'journalctl -o' and similar commands now implement a new output mode
          "short-delta". It is similar to "short-monotonic", but also shows the
          time delta between subsequent messages.

        * journalctl now respects the --quiet flag when verifying consistency
          of journal files.

        * Journal log messages gained a new implicit field _RUNTIME_SCOPE= that
          will indicate whether a message was logged in the 'initrd' phase or
          in the 'system' phase of the boot process.

        * Journal files gained a new compatibility flag
          'HEADER_INCOMPATIBLE_COMPACT'. Files with this flag implement changes
          to the storage format that allow reducing size on disk. As with other
          compatibility flags, older journalctl versions will not be able to
          read journal files using this new format. The environment variable
          'SYSTEMD_JOURNAL_COMPACT=0' can be passed to systemd-journald to
          disable this functionality. It is enabled by default.

        * systemd-run's --working-directory= switch now works when used in
          combination with --scope.

        * portablectl gained a --force flag to skip certain sanity checks. This
          is implemented using new flags accepted by systemd-portabled for the
          *WithExtensions() D-Bus methods: SD_SYSTEMD_PORTABLE_FORCE_ATTACH
          flag now means that the attach/detach checks whether the units are
          already present and running will be skipped. Similarly,
          SD_SYSTEMD_PORTABLE_FORCE_SYSEXT flag means that the check whether
          image name matches the name declared inside of the image will be
          skipped. Callers must be sure to do those checks themselves if
          appropriate.

        * systemd-portabled will now use the original filename to check
          extension-release.NAME for correctness, in case it is passed a
          symlink.

        * systemd-portabled now uses PrivateTmp=yes in the 'trusted' profile
          too.

        * sysext's extension-release files now support '_any' as a special
          value for the ID= field, to allow distribution-independent extensions
          (e.g.: fully statically compiled binaries, scripts). It also gained
          support for a new ARCHITECTURE= field that may be used to explicitly
          restrict an image to hosts of a specific architecture.

        * systemd-repart now supports creating squashfs partitions. This
          requires mksquashfs from squashfs-tools.

        * systemd-repart gained a --split flag to also generate split
          artifacts, i.e. a separate file for each partition. This is useful in
          conjunction with systemd-sysupdate or other tools, or to generate
          split dm-verity artifacts.

        * systemd-repart is now able to generate dm-verity partitions, including
          signatures.

        * systemd-repart can now set a partition UUID to zero, allowing it to
          be filled in later, such as when using verity partitions.

        * systemd-repart now supports drop-ins for its configuration files.

        * Package metadata logged by systemd-coredump in the system journal is
          now more compact.

        * xdg-autostart-service now expands 'tilde' characters in Exec lines.

        * systemd-oomd now automatically links against libatomic, if available.

        * systemd-oomd now sends out a 'Killed' D-Bus signal when a cgroup is
          killed.

        * scope units now also provide oom-kill status.

        * systemd-pstore will now try to load only the efi_pstore kernel module
          before running, ensuring that pstore can be used.

        * systemd-logind gained a new StopIdleSessionSec= option to stop an idle
          session after a preconfigure timeout.

        * systemd-homed will now wait up to 30 seconds for workers to terminate,
          rather than indefinitely.

        * homectl gained a new '--luks-sector-size=' flag that allows users to
          select the preferred LUKS sector size. Must be a power of 2 between 512
          and 4096. systemd-userdbd records gained a corresponding field.

        * systemd-sysusers will now respect the 'SOURCE_DATE_EPOCH' environment
          variable when generating the 'sp_lstchg' field, to ensure an image
          build can be reproducible.

        * 'udevadm wait' will now listen to kernel uevents too when called with
          --initialized=no.

        * When naming network devices udev will now consult the Devicetree
          "alias" fields for the device.

        * systemd-udev will now create infiniband/by-path and
          infiniband/by-ibdev links for Infiniband verbs devices.

        * systemd-udev-trigger.service will now also prioritize input devices.

        * ConditionACPower= and systemd-ac-power will now assume the system is
          running on AC power if no battery can be found.

        * All features and tools using the TPM2 will now communicate with it
          using a bind key. Beforehand, the tpm2 support used encrypted sessions
          by creating a primary key that was used to encrypt traffic. This
          creates a problem as the key created for encrypting the traffic could
          be faked by an active interposer on the bus. In cases when a pin is
          used, a bind key will be used. The pin is used as the auth value for
          the seal key, aka the disk encryption key, and that auth value will be
          used in the session establishment. An attacker would need the pin
          value to create the secure session and thus an active interposer
          without the pin cannot interpose on TPM2 traffic.

        * systemd-growfs no longer requires udev to run.

        * systemd-backlight now will better support systems with multiple
          graphic cards.

        * systemd-cryptsetup's keyfile-timeout= option now also works when a
          device is used as a keyfile.

        * systemd-cryptenroll gained a new --unlock-key-file= option to get the
          unlocking key from a key file (instead of prompting the user). Note
          that this is the key for unlocking the volume in order to be able to
          enroll a new key, but it is not the key that is enrolled.

        * systemd-dissect gained a new --umount switch that will safely and
          synchronously unmount all partitions of an image previously mounted
          with 'systemd-dissect --mount'.

        * When using gcrypt, all systemd tools and services will now configure
          it to prefer the OS random number generator if present.

        * All example code shipped with documentation has been relicensed from CC0
          to MIT-0.

        * Unit tests will no longer fail when running on a system without
          /etc/machine-id.

        Experimental features:

        * BPF programs can now be compiled with bpf-gcc (requires libbpf >= 1.0
          and bpftool >= 7.0).

        * sd-boot can automatically enroll SecureBoot keys from files found on
          the ESP. This enrollment can be either automatic ('force' mode) or
          controlled by the user ('manual' mode). It is sufficient to place the
          SecureBoot keys in the right place in the ESP and they will be picked
          up by sd-boot and shown in the boot menu.

        * The mkosi config in systemd gained support for automatically
          compiling a kernel with the configuration appropriate for testing
          systemd. This may be useful when developing or testing systemd in
          tandem with the kernel.

        Contributions from: 김인수, Adam Williamson, adrian5, Aidan Dang,
        Akihiko Odaki, Alban Bedel, Albert Mikaelyan, Aleksey Vasenev,
        Alexander Graf, Alexander Shopov, Alexander Wilson,
        Alper Nebi Yasak, anarcat, Anders Jonsson, Andre Kalb,
        Andrew Stone, Andrey Albershteyn, Anita Zhang, Ansgar Burchardt,
        Antonio Alvarez Feijoo, Arnaud Ferraris, Aryan singh, asavah,
        Avamander, Avram Lubkin, Balázs Meskó, Bastien Nocera,
        Benjamin Franzke, BerndAdameit, bin456789, Celeste Liu,
        Chih-Hsuan Yen, Christian Brauner, Christian Göttsche,
        Christian Hesse, Clyde Byrd III, codefiles, Colin Walters,
        Cristian Rodríguez, Daan De Meyer, Daniel Braunwarth,
        Daniel Rusek, Dan Streetman, Darsey Litzenberger, David Edmundson,
        David Jaša, David Rheinsberg, David Seifert, David Tardon,
        dependabot[bot], Devendra Tewari, Dominique Martinet, drosdeck,
        Edson Juliano Drosdeck, Eduard Tolosa, eggfly, Einsler Lee,
        Elias Probst, Eli Schwartz, Evgeny Vereshchagin, exploide, Fei Li,
        Foster Snowhill, Franck Bui, Frank Dana, Frantisek Sumsal,
        Gerd Hoffmann, Gio, Goffredo Baroncelli, gtwang01,
        Guillaume W. Bres, H A, Hans de Goede, Heinrich Schuchardt,
        Hugo Carvalho, i-do-cpp, igo95862, j00512545, Jacek Migacz,
        Jade Bilkey, James Hilliard, Jan B, Janis Goldschmidt,
        Jan Janssen, Jan Kuparinen, Jan Luebbe, Jan Macku,
        Jason A. Donenfeld, Javkhlanbayar Khongorzul, Jeremy Soller,
        JeroenHD, jiangchuangang, João Loureiro,
        Joaquín Ignacio Aramendía, Jochen Sprickerhof,
        Johannes Schauer Marin Rodrigues, Jonas Kümmerlin,
        Jonas Witschel, Jonathan Kang, Jonathan Lebon, Joost Heitbrink,
        Jörg Thalheim, josh-gordon-fb, Joyce, Kai Lueke, lastkrick,
        Lennart Poettering, Leon M. George, licunlong, Li kunyu,
        LockBlock-dev, Loïc Collignon, Lubomir Rintel, Luca Boccassi,
        Luca BRUNO, Ludwig Nussel, Łukasz Stelmach, Maccraft123,
        Marc Kleine-Budde, Marius Vollmer, Martin Wilck, matoro,
        Matthias Lisin, Max Gautier, Maxim Mikityanskiy, Michael Biebl,
        Michal Koutný, Michal Sekletár, Michal Stanke, Mike Gilbert,
        Mitchell Freiderich, msizanoen1, Nick Rosbrook, nl6720, Oğuz Ersen,
        Oleg Solovyov, Olga Smirnova, Pablo Ceballos, Pavel Zhukov,
        Phaedrus Leeds, Philipp Gortan, Piotr Drąg, Pyfisch,
        Quentin Deslandes, Rahil Bhimjiani, Rene Hollander, Richard Huang,
        Richard Phibel, Rudi Heitbaum, Sam James, Sarah Brofeldt,
        Sean Anderson, Sebastian Scheibner, Shreenidhi Shedi,
        Sonali Srivastava, Steve Ramage, Suraj Krishnan, Swapnil Devesh,
        Takashi Sakamoto, Ted X. Toth, Temuri Doghonadze, Thomas Blume,
        Thomas Haller, Thomas Hebb, Tomáš Hnyk, Tomasz Paweł Gajc,
        Topi Miettinen, Ulrich Ölmann, undef, Uriel Corfa,
        Victor Westerhuis, Vincent Dagonneau, Vishal Chillara Srinivas,
        Vito Caputo, Weblate, Wenchao Hao, William Roberts, williamsumendap,
        wineway, xiaoyang, Yuri Chornoivan, Yu Watanabe,
        Zbigniew Jędrzejewski-Szmek, Zhaofeng Li, наб

        – The Great Beyond, 2022-10-31 👻

CHANGES WITH 251:

        Backwards-incompatible changes:

        * The minimum kernel version required has been bumped from 3.13 to 4.15,
          and CLOCK_BOOTTIME is now assumed to always exist.

        * C11 with GNU extensions (aka "gnu11") is now used to build our
          components. Public API headers are still restricted to ISO C89.

        * In v250, a systemd-networkd feature that automatically configures
          routes to addresses specified in AllowedIPs= was added and enabled by
          default. However, this causes network connectivity issues in many
          existing setups. Hence, it has been disabled by default since
          systemd-stable 250.3. The feature can still be used by explicitly
          configuring RouteTable= setting in .netdev files.

        * Jobs started via StartUnitWithFlags() will no longer return 'skipped'
          when a Condition*= check does not succeed, restoring the JobRemoved
          signal to the behaviour it had before v250.

        * The org.freedesktop.portable1 methods GetMetadataWithExtensions() and
          GetImageMetadataWithExtensions() have been fixed to provide an extra
          return parameter, containing the actual extension release metadata.
          The current implementation was judged to be broken and unusable, and
          thus the usual procedure of adding a new set of methods was skipped,
          and backward compatibility broken instead on the assumption that
          nobody can be affected given the current state of this interface.

        * All kernels supported by systemd mix bytes returned by RDRAND (or
          similar) into the entropy pool at early boot. This means that on
          those systems, even if /dev/urandom is not yet initialized, it still
          returns bytes that are of at least RDRAND quality. For that reason,
          we no longer have reason to invoke RDRAND from systemd itself, which
          has historically been a source of bugs. Furthermore, kernels ≥5.6
          provide the getrandom(GRND_INSECURE) interface for returning random
          bytes before the entropy pool is initialized without warning into
          kmsg, which is what we attempt to use if available. systemd's direct
          usage of RDRAND has been removed. x86 systems ≥Broadwell that are
          running an older kernel may experience kmsg warnings that were not
          seen with 250. For newer kernels, non-x86 systems, or older x86
          systems, there should be no visible changes.

        * sd-boot will now measure the kernel command line into TPM PCR 12
          rather than PCR 8. This improves usefulness of the measurements on
          systems where sd-boot is chainloaded from Grub. Grub measures all
          commands its executes into PCR 8, which makes it very hard to use
          reasonably, hence separate ourselves from that and use PCR 12
          instead, which is what certain Ubuntu editions already do. To retain
          compatibility with systems running older systemd systems a new meson
          option 'efi-tpm-pcr-compat' has been added (which defaults to false).
          If enabled, the measurement is done twice: into the new-style PCR 12
          *and* the old-style PCR 8. It's strongly advised to migrate all users
          to PCR 12 for this purpose in the long run, as we intend to remove
          this compatibility feature in two years' time.

        * busctl capture now writes output in the newer pcapng format instead
          of pcap.

        * A udev rule that imported hwdb matches for USB devices with lowercase
          hexadecimal vendor/product ID digits was added in systemd 250. This
          has been reverted, since uppercase hexadecimal digits are supposed to
          be used, and we already had a rule with the appropriate match.

          Users might need to adjust their local hwdb entries.

        * arch_prctl(2) has been moved to the @default set in the syscall filters
          (as exposed via the SystemCallFilter= setting in service unit files).
          It is apparently used by the linker now.

        * The tmpfiles entries that create the /run/systemd/netif directory and
          its subdirectories were moved from tmpfiles.d/systemd.conf to
          tmpfiles.d/systemd-network.conf.

          Users might need to adjust their files that override tmpfiles.d/systemd.conf
          to account for this change.

        * The requirement for Portable Services images to contain a well-formed
          os-release file (i.e.: contain at least an ID field) is now enforced.
          This applies to base images and extensions, and also to systemd-sysext.

        Changes in the Boot Loader Specification, kernel-install and sd-boot:

        * kernel-install's and bootctl's Boot Loader Specification Type #1
          entry generation logic has been reworked. The user may now pick
          explicitly by which "token" string to name the installation's boot
          entries, via the new /etc/kernel/entry-token file or the new
          --entry-token= switch to bootctl. By default — as before — the
          entries are named after the local machine ID. However, in "golden
          image" environments, where the machine ID shall be initialized on
          first boot (as opposed to at installation time before first boot) the
          machine ID will not be available at build time. In this case the
          --entry-token= switch to bootctl (or the /etc/kernel/entry-token
          file) may be used to override the "token" for the entries, for
          example the IMAGE_ID= or ID= fields from /etc/os-release. This will
          make the OS images independent of any machine ID, and ensure that the
          images will not carry any identifiable information before first boot,
          but on the other hand means that multiple parallel installations of
          the very same image on the same disk cannot be supported.

          Summary: if you are building golden images that shall acquire
          identity information exclusively on first boot, make sure to both
          remove /etc/machine-id *and* to write /etc/kernel/entry-token to the
          value of the IMAGE_ID= or ID= field of /etc/os-release or another
          suitable identifier before deploying the image.

        * The Boot Loader Specification has been extended with
          /loader/entries.srel file located in the EFI System Partition (ESP)
          that disambiguates the format of the entries in the /loader/entries/
          directory (in order to discern them from incompatible uses of this
          directory by other projects). For entries that follow the
          Specification, the string "type1" is stored in this file.

          bootctl will now write this file automatically when installing the
          systemd-boot boot loader.

        * kernel-install supports a new initrd_generator= setting in
          /etc/kernel/install.conf, that is exported as
          $KERNEL_INSTALL_INITRD_GENERATOR to kernel-install plugins. This
          allows choosing different initrd generators.

        * kernel-install will now create a "staging area" (an initially-empty
          directory to gather files for a Boot Loader Specification Type #1
          entry). The path to this directory is exported as
          $KERNEL_INSTALL_STAGING_AREA to kernel-install plugins, which should
          drop files there instead of writing them directly to the final
          location. kernel-install will move them when all files have been
          prepared successfully.

        * New option sort-key= has been added to the Boot Loader Specification
          to override the sorting order of the entries in the boot menu. It is
          read by sd-boot and bootctl, and will be written by kernel-install,
          with the default value of IMAGE_ID= or ID= fields from
          os-release. Together, this means that on multiboot installations,
          entries should be grouped and sorted in a predictable way.

        * The sort order of boot entries has been updated: entries which have
          the new field sort-key= are sorted by it first, and all entries
          without it are ordered later. After that, entries are sorted by
          version so that newest entries are towards the beginning of the list.

        * The kernel-install tool gained a new 'inspect' verb which shows the
          paths and other settings used.

        * sd-boot can now optionally beep when the menu is shown and menu
          entries are selected, which can be useful on machines without a
          working display. (Controllable via a loader.conf setting.)

        * The --make-machine-id-directory= switch to bootctl has been replaced
          by --make-entry-directory=, given that the entry directory is not
          necessarily named after the machine ID, but after some other suitable
          ID as selected via --entry-token= described above. The old name of
          the option is still understood to maximize compatibility.

        * 'bootctl list' gained support for a new --json= switch to output boot
          menu entries in JSON format.

        * 'bootctl is-installed' now supports the --graceful, and various verbs
          omit output with the new option --quiet.

        Changes in systemd-homed:

        * Starting with v250 systemd-homed uses UID/GID mapping on the mounts
          of activated home directories it manages (if the kernel and selected
          file systems support it). So far it mapped three UID ranges: the
          range from 0…60000, the user's own UID, and the range 60514…65534,
          leaving everything else unmapped (in other words, the 16bit UID range
          is mapped almost fully, with the exception of the UID subrange used
          for systemd-homed users, with one exception: the user's own UID).
          Unmapped UIDs may not be used for file ownership in the home
          directory — any chown() attempts with them will fail. With this
          release a fourth range is added to these mappings:
          524288…1879048191. This range is the UID range intended for container
          uses, see:

                  https://systemd.io/UIDS-GIDS

          This range may be used for container managers that place container OS
          trees in the home directory (which is a questionable approach, for
          quota, permission, SUID handling and network file system
          compatibility reasons, but nonetheless apparently commonplace). Note
          that this mapping is mapped 1:1 in a pass-through fashion, i.e. the
          UID assignments from the range are not managed or mapped by
          `systemd-homed`, and must be managed with other mechanisms, in the
          context of the local system.

          Typically, a better approach to user namespacing in relevant
          container managers would be to leave container OS trees on disk at
          UID offset 0, but then map them to a dynamically allocated runtime
          UID range via another UID mount map at container invocation
          time. That way user namespace UID ranges become strictly a runtime
          concept, and do not leak into persistent file systems, persistent
          user databases or persistent configuration, thus greatly simplifying
          handling, and improving compatibility with home directories intended
          to be portable like the ones managed by systemd-homed.

        Changes in shared libraries:

        * A new libsystemd-core-<version>.so private shared library is
          installed under /usr/lib/systemd/system, mirroring the existing
          libsystemd-shared-<version>.so library. This allows the total
          installation size to be reduced by binary code reuse.

        * The <version> tag used in the name of libsystemd-shared.so and
          libsystemd-core.so can be configured via the meson option
          'shared-lib-tag'. Distributions may build subsequent versions of the
          systemd package with unique tags (e.g. the full package version),
          thus allowing multiple installations of those shared libraries to be
          available at the same time. This is intended to fix an issue where
          programs that link to those libraries would fail to execute because
          they were installed earlier or later than the appropriate version of
          the library.

        * The sd-id128 API gained a new call sd_id128_to_uuid_string() that is
          similar to sd_id128_to_string() but formats the ID in RFC 4122 UUID
          format instead of as a simple series of hex characters.

        * The sd-device API gained two new calls sd_device_new_from_devname()
          and sd_device_new_from_path() which permit allocating an sd_device
          object from a device node name or file system path.

        * sd-device also gained a new call sd_device_open() which will open the
          device node associated with a device for which an sd_device object
          has been allocated. The call is supposed to address races around
          device nodes being removed/recycled due to hotplug events, or media
          change events: the call checks internally whether the major/minor of
          the device node and the "diskseq" (in case of block devices) match
          with the metadata loaded in the sd_device object, thus ensuring that
          the device once opened really matches the provided sd_device object.

        Changes in PID1, systemctl, and systemd-oomd:

        * A new set of service monitor environment variables will be passed to
          OnFailure=/OnSuccess= handlers, but only if exactly one unit lists the
          handler unit as OnFailure=/OnSuccess=. The variables are:
          $MONITOR_SERVICE_RESULT, $MONITOR_EXIT_CODE, $MONITOR_EXIT_STATUS,
          $MONITOR_INVOCATION_ID and $MONITOR_UNIT. For cases when a single
          handler needs to watch multiple units, use a templated handler.

        * A new ExtensionDirectories= setting in service unit files allows
          system extensions to be loaded from a directory. (It is similar to
          ExtensionImages=, but takes paths to directories, instead of
          disk image files.)

          'portablectl attach --extension=' now also accepts directory paths.

        * The user.delegate and user.invocation_id extended attributes on
          cgroups are used in addition to trusted.delegate and
          trusted.invocation_id. The latter pair requires privileges to set,
          but the former doesn't and can be also set by the unprivileged user
          manager.

          (Only supported on kernels ≥5.6.)

        * Units that were killed by systemd-oomd will now have a service result
          of 'oom-kill'. The number of times a service was killed is tallied
          in the 'user.oomd_ooms' extended attribute.

          The OOMPolicy= unit file setting is now also honoured by
          systemd-oomd.

        * In unit files the new %y/%Y specifiers can be used to refer to
          normalized unit file path, which is particularly useful for symlinked
          unit files.

          The new %q specifier resolves to the pretty hostname
          (i.e. PRETTY_HOSTNAME= from /etc/machine-info).

          The new %d specifier resolves to the credentials directory of a
          service (same as $CREDENTIALS_DIRECTORY).

        * The RootDirectory=, MountAPIVFS=, ExtensionDirectories=,
          *Capabilities*=, ProtectHome=, *Directory=, TemporaryFileSystem=,
          PrivateTmp=, PrivateDevices=, PrivateNetwork=, NetworkNamespacePath=,
          PrivateIPC=, IPCNamespacePath=, PrivateUsers=, ProtectClock=,
          ProtectKernelTunables=, ProtectKernelModules=, ProtectKernelLogs=,
          MountFlags= service settings now also work in unprivileged user
          services, i.e. those run by the user's --user service manager, as long
          as user namespaces are enabled on the system.

        * Services with Restart=always and a failing ExecCondition= will no
          longer be restarted, to bring ExecCondition= behaviour in line with
          Condition*= settings.

        * LoadCredential= now accepts a directory as the argument; all files
          from the directory will be loaded as credentials.

        * A new D-Bus property ControlGroupId is now exposed on service units,
          that encapsulates the service's numeric cgroup ID that newer kernels
          assign to each cgroup.

        * PID 1 gained support for configuring the "pre-timeout" of watchdog
          devices and the associated governor, via the new
          RuntimeWatchdogPreSec= and RuntimeWatchdogPreGovernor= configuration
          options in /etc/systemd/system.conf.

        * systemctl's --timestamp= option gained a new choice "unix", to show
          timestamp as unix times, i.e. seconds since 1970, Jan 1st.

        * A new "taint" flag named "old-kernel" is introduced which is set when
          the kernel systemd runs on is older then the current baseline version
          (see above). The flag is shown in "systemctl status" output.

        * Two additional taint flags "short-uid-range" and "short-gid-range"
          have been added as well, which are set when systemd notices it is run
          within a userns namespace that does not define the full 0…65535 UID
          range

        * A new "unmerged-usr" taint flag has been added that is set whenever
          running on systems where /bin/ + /sbin/ are *not* symlinks to their
          counterparts in /usr/, i.e. on systems where the /usr/-merge has not
          been completed.

        * Generators invoked by PID 1 will now have a couple of useful
          environment variables set describing the execution context a
          bit. $SYSTEMD_SCOPE encodes whether the generator is called from the
          system service manager, or from the per-user service
          manager. $SYSTEMD_IN_INITRD encodes whether the generator is invoked
          in initrd context or on the host. $SYSTEMD_FIRST_BOOT encodes whether
          systemd considers the current boot to be a "first"
          boot. $SYSTEMD_VIRTUALIZATION encode whether virtualization is
          detected and which type of hypervisor/container
          manager. $SYSTEMD_ARCHITECTURE indicates which architecture the
          kernel is built for.

        * PID 1 will now automatically pick up system credentials from qemu's
          fw_cfg interface, thus allowing passing arbitrary data into VM
          systems similar to how this is already supported for passing them
          into `systemd-nspawn` containers. Credentials may now also be passed
          in via the new kernel command line option `systemd.set_credential=`
          (note that kernel command line options are world-readable during
          runtime, and only useful for credentials that require no
          confidentiality). The credentials that can be passed to unified
          kernels that use the `systemd-stub` UEFI stub are now similarly
          picked up automatically. Automatic importing of system credentials
          this way can be turned off via the new
          `systemd.import_credentials=no` kernel command line option.

        * LoadCredential= will now automatically look for credentials in the
          /etc/credstore/, /run/credstore/, /usr/lib/credstore/ directories if
          the argument is not an absolute path. Similarly,
          LoadCredentialEncrypted= will check the same directories plus
          /etc/credstore.encrypted/, /run/credstore.encrypted/ and
          /usr/lib/credstore.encrypted/. The idea is to use those directories
          as the system-wide location for credentials that services should pick
          up automatically.

        * System and service credentials are described in great detail in a new
          document:

          https://systemd.io/CREDENTIALS

        Changes in systemd-journald:

        * The journal JSON export format has been added to listed of stable
          interfaces (https://systemd.io/PORTABILITY_AND_STABILITY/).

        * journalctl --list-boots now supports JSON output and the --reverse option.

        * Under docs/: JOURNAL_EXPORT_FORMATS was imported from the wiki and
          updated, BUILDING_IMAGES is new:

          https://systemd.io/JOURNAL_EXPORT_FORMATS
          https://systemd.io/BUILDING_IMAGES

        Changes in udev:

        * Two new hwdb files have been added. One lists "handhelds" (PDAs,
          calculators, etc.), the other AV production devices (DJ tables,
          keypads, etc.) that should accessible to the seat owner user by
          default.

        * udevadm trigger gained a new --prioritized-subsystem= option to
          process certain subsystems (and all their parent devices) earlier.

          systemd-udev-trigger.service now uses this new option to trigger
          block and TPM devices first, hopefully making the boot a bit faster.

        * udevadm trigger now implements --type=all, --initialized-match,
          --initialized-nomatch to trigger both subsystems and devices, only
          already-initialized devices, and only devices which haven't been
          initialized yet, respectively.

        * udevadm gained a new "wait" command for safely waiting for a specific
          device to show up in the udev device database. This is useful in
          scripts that asynchronously allocate a block device (e.g. through
          repartitioning, or allocating a loopback device or similar) and need
          to synchronize on the creation to complete.

        * udevadm gained a new "lock" command for locking one or more block
          devices while formatting it or writing a partition table to it. It is
          an implementation of https://systemd.io/BLOCK_DEVICE_LOCKING and
          usable in scripts dealing with block devices.

        * udevadm info will show a couple of additional device fields in its
          output, and will not apply a limited set of coloring to line types.

        * udevadm info --tree will now show a tree of objects (i.e. devices and
          suchlike) in the /sys/ hierarchy.

        * Block devices will now get a new set of device symlinks in
          /dev/disk/by-diskseq/<nr>, which may be used to reference block
          device nodes via the kernel's "diskseq" value. Note that this does
          not guarantee that opening a device by a symlink like this will
          guarantee that the opened device actually matches the specified
          diskseq value. To be safe against races, the actual diskseq value of
          the opened device (BLKGETDISKSEQ ioctl()) must still be compred with
          the one in the symlink path.

        * .link files gained support for setting MDI/MID-X on a link.

        * .link files gained support for [Match] Firmware= setting to match on
          the device firmware description string. By mistake, it was previously
          only supported in .network files.

        * .link files gained support for [Link] SR-IOVVirtualFunctions= setting
          and [SR-IOV] section to configure SR-IOV virtual functions.

        Changes in systemd-networkd:

        * The default scope for unicast routes configured through [Route]
          section is changed to "link", to make the behavior consistent with
          "ip route" command. The manual configuration of [Route] Scope= is
          still honored.

        * A new unit systemd-networkd-wait-online@<interface>.service has been
          added that can be used to wait for a specific network interface to be
          up.

        * systemd-networkd gained a new [Bridge] Isolated=true|false setting
          that configures the eponymous kernel attribute on the bridge.

        * .netdev files now can be used to create virtual WLAN devices, and
          configure various settings on them, via the [WLAN] section.

        * .link/.network files gained support for [Match] Kind= setting to match
          on device kind ("bond", "bridge", "gre", "tun", "veth", etc.)

          This value is also shown by 'networkctl status'.

        * The Local= setting in .netdev files for various virtual network
          devices gained support for specifying, in addition to the network
          address, the name of a local interface which must have the specified
          address.

        * systemd-networkd gained a new [Tunnel] External= setting in .netdev
          files, to configure tunnels in external mode (a.k.a. collect metadata
          mode).

        * [Network] L2TP= setting was removed. Please use interface specifier in
          Local= setting in .netdev files of corresponding L2TP interface.

        * New [DHCPServer] BootServerName=, BootServerAddress=, and
          BootFilename= settings can be used to configure the server address,
          server name, and file name sent in the DHCP packet (e.g. to configure
          PXE boot).

        Changes in systemd-resolved:

        * systemd-resolved is started earlier (in sysinit.target), so it
          available earlier and will also be started in the initrd if installed
          there.

        Changes in disk encryption:

        * systemd-cryptenroll can now control whether to require the user to
          enter a PIN when using TPM-based unlocking of a volume via the new
          --tpm2-with-pin= option.

          Option tpm2-pin= can be used in /etc/crypttab.

        * When unlocking devices via TPM, TPM2 parameter encryption is now
          used, to ensure that communication between CPU and discrete TPM chips
          cannot be eavesdropped to acquire disk encryption keys.

        * A new switch --fido2-credential-algorithm= has been added to
          systemd-cryptenroll allowing selection of the credential algorithm to
          use when binding encryption to FIDO2 tokens.

        Changes in systemd-hostnamed:

        * HARDWARE_VENDOR= and HARDWARE_MODEL= can be set in /etc/machine-info
          to override the values gleaned from the hwdb.

        * A ID_CHASSIS property can be set in the hwdb (for the DMI device
          /sys/class/dmi/id) to override the chassis that is reported by
          hostnamed.

        * hostnamed's D-Bus interface gained a new method GetHardwareSerial()
          for reading the hardware serial number, as reportd by DMI. It also
          exposes a new method D-Bus property FirmwareVersion that encode the
          firmware version of the system.

        Changes in other components:

        * /etc/locale.conf is now populated through tmpfiles.d factory /etc/
          handling with the values that were configured during systemd build
          (if /etc/locale.conf has not been created through some other
          mechanism). This means that /etc/locale.conf should always have
          reasonable contents and we avoid a potential mismatch in defaults.

        * The userdbctl tool will now show UID range information as part of the
          list of known users.

        * A new build-time configuration setting default-user-shell= can be
          used to set the default shell for user records and nspawn shell
          invocations (instead of the default /bin/bash).

        * systemd-timesyncd now provides a D-Bus API for receiving NTP server
          information dynamically at runtime via IPC.

        * The systemd-creds tool gained a new "has-tpm2" verb, which reports
          whether a functioning TPM2 infrastructure is available, i.e. if
          firmware, kernel driver and systemd all have TPM2 support enabled and
          a device found.

        * The systemd-creds tool gained support for generating encrypted
          credentials that are using an empty encryption key. While this
          provides no integrity nor confidentiality it's useful to implement
          codeflows that work the same on TPM-ful and TPM2-less systems. The
          service manager will only accept credentials "encrypted" that way if
          a TPM2 device cannot be detected, to ensure that credentials
          "encrypted" like that cannot be used to trick TPM2 systems.

        * When deciding whether to colorize output, all systemd programs now
          also check $COLORTERM (in addition to $NO_COLOR, $SYSTEMD_COLORS, and
          $TERM).

        * Meson's new install_tag feature is now in use for several components,
          allowing to build and install select binaries only: pam, nss, devel
          (pkg-config files), systemd-boot, libsystemd, libudev. Example:
           $ meson build systemd-boot
           $ meson install --tags systemd-boot --no-rebuild
          https://mesonbuild.com/Installing.html#installation-tags

        * A new build configuration option has been added, to allow selecting the
          default compression algorithm used by systemd-journald and systemd-coredump.
          This allows to build-in support for decompressing all supported formats,
          but choose a specific one for compression. E.g.:
           $ meson -Ddefault-compression=xz

        Experimental features:

        * sd-boot gained a new *experimental* setting "reboot-for-bitlocker" in
          loader.conf that implements booting Microsoft Windows from the
          sd-boot in a way that first reboots the system, to reset the TPM
          PCRs. This improves compatibility with BitLocker's TPM use, as the
          PCRs will only record the Windows boot process, and not sd-boot
          itself, thus retaining the PCR measurements not involving sd-boot.
          Note that this feature is experimental for now, and is likely going
          to be generalized and renamed in a future release, without retaining
          compatibility with the current implementation.

        * A new systemd-sysupdate component has been added that automatically
          discovers, downloads, and installs A/B-style updates for the host
          installation itself, or container images, portable service images,
          and other assets. See the new systemd-sysupdate man page for updates.

        Contributions from: 4piu, Adam Williamson, adrian5, Albert Brox,
        AlexCatze, Alex Henrie, Alfonso Sánchez-Beato, Alice S,
        Alvin Šipraga, amarjargal, Amarjargal, Andrea Pappacoda,
        Andreas Rammhold, Andy Chi, Anita Zhang, Antonio Alvarez Feijoo,
        Arfrever Frehtes Taifersar Arahesis, ash, Bastien Nocera, Be,
        bearhoney, Ben Efros, Benjamin Berg, Benjamin Franzke,
        Brett Holman, Christian Brauner, Clyde Byrd III, Curtis Klein,
        Daan De Meyer, Daniele Medri, Daniel Mack, Danilo Krummrich,
        David, David Bond, Davide Cavalca, David Tardon, davijosw,
        dependabot[bot], Donald Chan, Dorian Clay, Eduard Tolosa,
        Elias Probst, Eli Schwartz, Erik Sjölund, Evgeny Vereshchagin,
        Federico Ceratto, Franck Bui, Frantisek Sumsal, Gaël PORTAY,
        Georges Basile Stavracas Neto, Gibeom Gwon, Goffredo Baroncelli,
        Grigori Goronzy, Hans de Goede, Heiko Becker, Hugo Carvalho,
        Jakob Lell, James Hilliard, Jan Janssen, Jason A. Donenfeld,
        Joan Bruguera, Joerie de Gram, Josh Triplett, Julia Kartseva,
        Kazuo Moriwaka, Khem Raj, ksa678491784, Lance, Lan Tian,
        Laura Barcziova, Lennart Poettering, Leviticoh, licunlong,
        Lidong Zhong, lincoln auster, Lubomir Rintel, Luca Boccassi,
        Luca BRUNO, lucagoc, Ludwig Nussel, Marcel Hellwig, march1993,
        Marco Scardovi, Mario Limonciello, Mariusz Tkaczyk,
        Markus Weippert, Martin, Martin Liska, Martin Wilck, Matija Skala,
        Matthew Blythe, Matthias Lisin, Matthijs van Duin, Matt Walton,
        Max Gautier, Michael Biebl, Michael Olbrich, Michal Koutný,
        Michal Sekletár, Mike Gilbert, MkfsSion, Morten Linderud,
        Nick Rosbrook, Nikolai Grigoriev, Nikolai Kostrigin,
        Nishal Kulkarni, Noel Kuntze, Pablo Ceballos, Peter Hutterer,
        Peter Morrow, Pigmy-penguin, Piotr Drąg, prumian, Richard Neill,
        Rike-Benjamin Schuppner, rodin-ia, Romain Naour, Ruben Kerkhof,
        Ryan Hendrickson, Santa Wiryaman, Sebastian Pucilowski, Seth Falco,
        Simon Ellmann, Sonali Srivastava, Stefan Seering,
        Stephen Hemminger, tawefogo, techtino, Temuri Doghonadze,
        Thomas Batten, Thomas Haller, Thomas Weißschuh, Tobias Stoeckmann,
        Tomasz Pala, Tyson Whitehead, Vishal Chillara Srinivas,
        Vivien Didelot, w30023233, wangyuhang, Weblate, Xiaotian Wu,
        yangmingtai, YmrDtnJu, Yonathan Randolph, Yutsuten, Yu Watanabe,
        Zbigniew Jędrzejewski-Szmek, наб

        — Edinburgh, 2022-05-21

CHANGES WITH 250:

        * Support for encrypted and authenticated credentials has been added.
          This extends the credential logic introduced with v247 to support
          non-interactive symmetric encryption and authentication, based on a
          key that is stored on the /var/ file system or in the TPM2 chip (if
          available), or the combination of both (by default if a TPM2 chip
          exists the combination is used, otherwise the /var/ key only). The
          credentials are automatically decrypted at the moment a service is
          started, and are made accessible to the service itself in unencrypted
          form. A new tool 'systemd-creds' encrypts credentials for this
          purpose, and two new service file settings LoadCredentialEncrypted=
          and SetCredentialEncrypted= configure such credentials.

          This feature is useful to store sensitive material such as SSL
          certificates, passwords and similar securely at rest and only decrypt
          them when needed, and in a way that is tied to the local OS
          installation or hardware.

        * systemd-gpt-auto-generator can now automatically set up discoverable
          LUKS2 encrypted swap partitions.

        * The GPT Discoverable Partitions Specification has been substantially
          extended with support for root and /usr/ partitions for the majority
          of architectures systemd supports. This includes platforms that do
          not natively support UEFI, because even though GPT is specified under
          UEFI umbrella, it is useful on other systems too. Specifically,
          systemd-nspawn, systemd-sysext, systemd-gpt-auto-generator and
          Portable Services use the concept without requiring UEFI.

        * The GPT Discoverable Partitions Specifications has been extended with
          a new set of partitions that may carry PKCS#7 signatures for Verity
          partitions, encoded in a simple JSON format. This implements a simple
          mechanism for building disk images that are fully authenticated and
          can be tested against a set of cryptographic certificates. This is
          now implemented for the various systemd tools that can operate with
          disk images, such as systemd-nspawn, systemd-sysext, systemd-dissect,
          Portable services/RootImage=, systemd-tmpfiles, and systemd-sysusers.
          The PKCS#7 signatures are passed to the kernel (where they are
          checked against certificates from the kernel keyring), or can be
          verified against certificates provided in userspace (via a simple
          drop-in file mechanism).

        * systemd-dissect's inspection logic will now report for which uses a
          disk image is intended. Specifically, it will display whether an
          image is suitable for booting on UEFI or in a container (using
          systemd-nspawn's --image= switch), whether it can be used as portable
          service, or attached as system extension.

        * The system-extension.d/ drop-in files now support a new field
          SYSEXT_SCOPE= that may encode which purpose a system extension image
          is for: one of "initrd", "system" or "portable". This is useful to
          make images more self-descriptive, and to ensure system extensions
          cannot be attached in the wrong contexts.

        * The os-release file learnt a new PORTABLE_PREFIXES= field which may
          be used in portable service images to indicate which unit prefixes
          are supported.

        * The GPT image dissection logic in systemd-nspawn/systemd-dissect/…
          now is able to decode images for non-native architectures as well.
          This allows systemd-nspawn to boot images of non-native architectures
          if the corresponding user mode emulator is installed and
          systemd-binfmtd is running.

        * systemd-logind gained new settings HandlePowerKeyLongPress=,
          HandleRebootKeyLongPress=, HandleSuspendKeyLongPress= and
          HandleHibernateKeyLongPress= which may be used to configure actions
          when the relevant keys are pressed for more than 5s. This is useful
          on devices that only have hardware for a subset of these keys. By
          default, if the reboot key is pressed long the poweroff operation is
          now triggered, and when the suspend key is pressed long the hibernate
          operation is triggered. Long pressing the other two keys currently
          does not trigger any operation by default.

        * When showing unit status updates on the console during boot and
          shutdown, and a service is slow to start so that the cylon animation
          is shown, the most recent sd_notify() STATUS= text is now shown as
          well. Services may use this to make the boot/shutdown output easier
          to understand, and to indicate what precisely a service that is slow
          to start or stop is waiting for. In particular, the per-user service
          manager instance now reports what it is doing and which service it is
          waiting for this way to the system service manager.

        * The service manager will now re-execute on reception of the
          SIGRTMIN+25 signal. It previously already did that on SIGTERM — but
          only when running as PID 1. There was no signal to request this when
          running as per-user service manager, i.e. as any other PID than 1.
          SIGRTMIN+25 works for both system and user managers.

        * The hardware watchdog logic in PID 1 gained support for operating
          with the default timeout configured in the hardware, instead of
          insisting on re-configuring it. Set RuntimeWatchdogSec=default to
          request this behavior.

        * A new kernel command line option systemd.watchdog_sec= is now
          understood which may be used to override the hardware watchdog
          time-out for the boot.

        * A new setting DefaultOOMScoreAdjust= is now supported in
          /etc/systemd/system.conf and /etc/systemd/user.conf. It may be used
          to set the default process OOM score adjustment value for processes
          started by the service manager. For per-user service managers this
          now defaults to 100, but for per-system service managers is left as
          is. This means that by default now services forked off the user
          service manager are more likely to be killed by the OOM killer than
          system services or the managers themselves.

        * A new per-service setting RestrictFileSystems= as been added that
          restricts the file systems a service has access to by their type.
          This is based on the new BPF LSM of the Linux kernel. It provides an
          effective way to make certain API file systems unavailable to
          services (and thus minimizing attack surface). A new command
          "systemd-analyze filesystems" has been added that lists all known
          file system types (and how they are grouped together under useful
          group handles).

        * Services now support a new setting RestrictNetworkInterfaces= for
          restricting access to specific network interfaces.

        * Service unit files gained new settings StartupAllowedCPUs= and
          StartupAllowedMemoryNodes=. These are similar to their counterparts
          without the "Startup" prefix and apply during the boot process
          only. This is useful to improve boot-time behavior of the system and
          assign resources differently during boot than during regular
          runtime. This is similar to the preexisting StartupCPUWeight=
          vs. CPUWeight.

        * Related to this: the various StartupXYZ= settings
          (i.e. StartupCPUWeight=, StartupAllowedCPUs=, …) are now also applied
          during shutdown. The settings not prefixed with "Startup" hence apply
          during regular runtime, and those that are prefixed like that apply
          during boot and shutdown.

        * A new per-unit set of conditions/asserts
          [Condition|Assert][Memory|CPU|IO]Pressure= have been added to make a
          unit skip/fail activation if the system's (or a slice's) memory/cpu/io
          pressure is above the configured threshold, using the kernel PSI
          feature. For more details see systemd.unit(5) and
          https://docs.kernel.org/accounting/psi.html

        * The combination of ProcSubset=pid and ProtectKernelTunables=yes and/or
          ProtectKernelLogs=yes can now be used.

        * The default maximum numbers of inodes have been raised from 64k to 1M
          for /dev/, and from 400k to 1M for /tmp/.

        * The per-user service manager learnt support for communicating with
          systemd-oomd to acquire OOM kill information.

        * A new service setting ExecSearchPath= has been added that allows
          changing the search path for executables for services. It affects
          where we look for the binaries specified in ExecStart= and similar,
          and the specified directories are also added the $PATH environment
          variable passed to invoked processes.

        * A new setting RuntimeRandomizedExtraSec= has been added for service
          and scope units that allows extending the runtime time-out as
          configured by RuntimeMaxSec= with a randomized amount.

        * The syntax of the service unit settings RuntimeDirectory=,
          StateDirectory=, CacheDirectory=, LogsDirectory= has been extended:
          if the specified value is now suffixed with a colon, followed by
          another filename, the latter will be created as symbolic link to the
          specified directory. This allows creating these service directories
          together with alias symlinks to make them available under multiple
          names.

        * Service unit files gained two new settings TTYRows=/TTYColumns= for
          configuring rows/columns of the TTY device passed to
          stdin/stdout/stderr of the service. This is useful to propagate TTY
          dimensions to a virtual machine.

        * A new service unit file setting ExitType= has been added that
          specifies when to assume a service has exited. By default systemd
          only watches the main process of a service. By setting
          ExitType=cgroup it can be told to wait for the last process in a
          cgroup instead.

        * Automount unit files gained a new setting ExtraOptions= that can be
          used to configure additional mount options to pass to the kernel when
          mounting the autofs instance.

        * "Urlification" (generation of ESC sequences that generate clickable
          hyperlinks in modern terminals) may now be turned off altogether
          during build-time.

        * Path units gained new TriggerLimitBurst= and TriggerLimitIntervalSec=
          settings that default to 200 and 2 s respectively. The ratelimit
          ensures that a path unit cannot cause PID1 to busy-loop when it is
          trying to trigger a service that is skipped because of a Condition*=
          not being satisfied. This matches the configuration and behaviour of
          socket units.

        * The TPM2/FIDO2/PKCS11 support in systemd-cryptsetup is now also built
          as a plug-in for cryptsetup. This means the plain cryptsetup command
          may now be used to unlock volumes set up this way.

        * The TPM2 logic in cryptsetup will now automatically detect systems
          where the TPM2 chip advertises SHA256 PCR banks but the firmware only
          updates the SHA1 banks. In such a case PCR policies will be
          automatically bound to the latter, not the former. This makes the PCR
          policies reliable, but of course do not provide the same level of
          trust as SHA256 banks.

        * The TPM2 logic in systemd-cryptsetup/systemd-cryptsetup now supports
          RSA primary keys in addition to ECC, improving compatibility with
          TPM2 chips that do not support ECC. RSA keys are much slower to use
          than ECC, and hence are only used if ECC is not available.

        * /etc/crypttab gained support for a new token-timeout= setting for
          encrypted volumes that allows configuration of the maximum time to
          wait for PKCS#11/FIDO2 tokens to be plugged in. If the time elapses
          the logic will query the user for a regular passphrase/recovery key
          instead.

        * Support for activating dm-integrity volumes at boot via a new file
          /etc/integritytab and the tool systemd-integritysetup have been
          added. This is similar to /etc/crypttab and /etc/veritytab, but deals
          with dm-integrity instead of dm-crypt/dm-verity.

        * The systemd-veritysetup-generator now understands a new usrhash=
          kernel command line option for specifying the Verity root hash for
          the partition backing the /usr/ file system. A matching set of
          systemd.verity_usr_* kernel command line options has been added as
          well. These all work similar to the corresponding options for the
          root partition.

        * The sd-device API gained a new API call sd_device_get_diskseq() to
          return the DISKSEQ property of a device structure. The "disk
          sequence" concept is a new feature recently introduced to the Linux
          kernel that allows detecting reuse cycles of block devices, i.e. can
          be used to recognize when loopback block devices are reused for a
          different purpose or CD-ROM drives get their media changed.

        * A new unit systemd-boot-update.service has been added. If enabled
          (the default) and the sd-boot loader is detected to be installed, it
          is automatically updated to the newest version when out of date. This
          is useful to ensure the boot loader remains up-to-date, and updates
          automatically propagate from the OS tree in /usr/.

        * sd-boot will now build with SBAT by default in order to facilitate
          working with recent versions of Shim that require it to be present.

        * sd-boot can now parse Microsoft Windows' Boot Configuration Data.
          This is used to robustly generate boot entry titles for Windows.

        * A new generic target unit factory-reset.target has been added. It is
          hooked into systemd-logind similar in fashion to
          reboot/poweroff/suspend/hibernate, and is supposed to be used to
          initiate a factory reset operation. What precisely this operation
          entails is up for the implementer to decide, the primary goal of the
          new unit is provide a framework where to plug in the implementation
          and how to trigger it.

        * A new meson build-time option 'clock-valid-range-usec-max' has been
          added which takes a time in µs and defaults to 15 years. If the RTC
          time is noticed to be more than the specified time ahead of the
          built-in epoch of systemd (which by default is the release timestamp
          of systemd) it is assumed that the RTC is not working correctly, and
          the RTC is reset to the epoch. (It already is reset to the epoch when
          noticed to be before it.) This should increase the chance that time
          doesn't accidentally jump too far ahead due to faulty hardware or
          batteries.

        * A new setting SaveIntervalSec= has been added to systemd-timesyncd,
          which may be used to automatically save the current system time to
          disk in regular intervals. This is useful to maintain a roughly
          monotonic clock even without RTC hardware and with some robustness
          against abnormal system shutdown.

        * systemd-analyze verify gained support for a pair of new --image= +
          --root= switches for verifying units below a specific root
          directory/image instead of on the host.

        * systemd-analyze verify gained support for verifying unit files under
          an explicitly specified unit name, independently of what the filename
          actually is.

        * systemd-analyze verify gained a new switch --recursive-errors= which
          controls whether to only fail on errors found in the specified units
          or recursively any dependent units.

        * systemd-analyze security now supports a new --offline mode for
          analyzing unit files stored on disk instead of loaded units. It may
          be combined with --root=/--image to analyze unit files under a root
          directory or disk image. It also learnt a new --threshold= parameter
          for specifying an exposure level threshold: if the exposure level
          exceeds the specified value the call will fail. It also gained a new
          --security-policy= switch for configuring security policies to
          enforce on the units. A policy is a JSON file that lists which tests
          shall be weighted how much to determine the overall exposure
          level. Altogether these new features are useful for fully automatic
          analysis and enforcement of security policies on unit files.

        * systemd-analyze security gain a new --json= switch for JSON output.

        * systemd-analyze learnt a new --quiet switch for reducing
          non-essential output. It's honored by the "dot", "syscall-filter",
          "filesystems" commands.

        * systemd-analyze security gained a --profile= option that can be used
          to take into account a portable profile when analyzing portable
          services, since a lot of the security-related settings are enabled
          through them.

        * systemd-analyze learnt a new inspect-elf verb that parses ELF core
          files, binaries and executables and prints metadata information,
          including the build-id and other info described on:
          https://systemd.io/COREDUMP_PACKAGE_METADATA/

        * .network files gained a new UplinkInterface= in the [IPv6SendRA]
          section, for automatically propagating DNS settings from other
          interfaces.

        * The static lease DHCP server logic in systemd-networkd may now serve
          IP addresses outside of the configured IP pool range for the server.

        * CAN support in systemd-networkd gained four new settings Loopback=,
          OneShot=, PresumeAck=, ClassicDataLengthCode= for tweaking CAN
          control modes. It gained a number of further settings for tweaking
          CAN timing quanta.

        * The [CAN] section in .network file gained new TimeQuantaNSec=,
          PropagationSegment=, PhaseBufferSegment1=, PhaseBufferSegment2=,
          SyncJumpWidth=, DataTimeQuantaNSec=, DataPropagationSegment=,
          DataPhaseBufferSegment1=, DataPhaseBufferSegment2=, and
          DataSyncJumpWidth= settings to control bit-timing processed by the
          CAN interface.

        * DHCPv4 client support in systemd-networkd learnt a new Label= option
          for configuring the address label to apply to configure IPv4
          addresses.

        * The [IPv6AcceptRA] section of .network files gained support for a new
          UseMTU= setting that may be used to control whether to apply the
          announced MTU settings to the local interface.

        * The [DHCPv4] section in .network file gained a new Use6RD= boolean
          setting to control whether the DHCPv4 client request and process the
          DHCP 6RD option.

        * The [DHCPv6PrefixDelegation] section in .network file is renamed to
          [DHCPPrefixDelegation], as now the prefix delegation is also supported
          with DHCPv4 protocol by enabling the Use6RD= setting.

        * The [DHCPPrefixDelegation] section in .network file gained a new
          setting UplinkInterface= to specify the upstream interface.

        * The [DHCPv6] section in .network file gained a new setting
          UseDelegatedPrefix= to control whether the delegated prefixes will be
          propagated to the downstream interfaces.

        * The [IPv6AcceptRA] section of .network files now understands two new
          settings UseGateway=/UseRoutePrefix= for explicitly configuring
          whether to use the relevant fields from the IPv6 Router Advertisement
          records.

        * The ForceDHCPv6PDOtherInformation= setting in the [DHCPv6] section
          has been removed. Please use the WithoutRA= and UseDelegatedPrefix=
          settings in the [DHCPv6] section and the DHCPv6Client= setting in the
          [IPv6AcceptRA] section to control when the DHCPv6 client is started
          and how the delegated prefixes are handled by the DHCPv6 client.

        * The IPv6Token= section in the [Network] section is deprecated, and
          the [IPv6AcceptRA] section gained the Token= setting for its
          replacement. The [IPv6Prefix] section also gained the Token= setting.
          The Token= setting gained 'eui64' mode to explicitly configure an
          address with the EUI64 algorithm based on the interface MAC address.
          The 'prefixstable' mode can now optionally take a secret key. The
          Token= setting in the [DHCPPrefixDelegation] section now supports all
          algorithms supported by the same settings in the other sections.

        * The [RoutingPolicyRule] section of .network file gained a new
          SuppressInterfaceGroup= setting.

        * The IgnoreCarrierLoss= setting in the [Network] section of .network
          files now allows a duration to be specified, controlling how long to
          wait before reacting to carrier loss.

        * The [DHCPServer] section of .network file gained a new Router=
          setting to specify the router address.

        * The [CAKE] section of .network files gained various new settings
          AutoRateIngress=, CompensationMode=, FlowIsolationMode=, NAT=,
          MPUBytes=, PriorityQueueingPreset=, FirewallMark=, Wash=, SplitGSO=,
          and UseRawPacketSize= for configuring CAKE.

        * systemd-networkd now ships with new default .network files:
          80-container-vb.network which matches host-side network bridge device
          created by systemd-nspawn's --network-bridge or --network-zone
          switch, and 80-6rd-tunnel.network which matches automatically created
          sit tunnel with 6rd prefix when the DHCP 6RD option is received.

        * systemd-networkd's handling of Endpoint= resolution for WireGuard
          interfaces has been improved.

        * systemd-networkd will now automatically configure routes to addresses
          specified in AllowedIPs=. This feature can be controlled via
          RouteTable= and RouteMetric= settings in [WireGuard] or
          [WireGuardPeer] sections.

        * systemd-networkd will now once again automatically generate persistent
          MAC addresses for batadv and bridge interfaces. Users can disable this
          by using MACAddress=none in .netdev files.

        * systemd-networkd and systemd-udevd now support IP over InfiniBand
          interfaces. The Kind= setting in .netdev file accepts "ipoib". And
          systemd.netdev files gained the [IPoIB] section.

        * systemd-networkd and systemd-udevd now support net.ifname-policy=
          option on the kernel command-line. This is implemented through the
          systemd-network-generator service that automatically generates
          appropriate .link, .network, and .netdev files.

        * The various systemd-udevd "ethtool" buffer settings now understand
          the special value "max" to configure the buffers to the maximum the
          hardware supports.

        * systemd-udevd's .link files may now configure a large variety of
          NIC coalescing settings, plus more hardware offload settings.

        * .link files gained a new WakeOnLanPassword= setting in the [Link]
          section that allows to specify a WoL "SecureOn" password on hardware
          that supports this.

        * systemd-nspawn's --setenv= switch now supports an additional syntax:
          if only a variable name is specified (i.e. without being suffixed by
          a '=' character and a value) the current value of the environment
          variable is propagated to the container. e.g. --setenv=FOO will
          lookup the current value of $FOO in the environment, and pass it down
          to the container. Similar behavior has been added to homectl's,
          machinectl's and systemd-run's --setenv= switch.

        * systemd-nspawn gained a new switch --suppress-sync= which may be used
          to optionally suppress the effect of the sync()/fsync()/fdatasync()
          system calls for the container payload. This is useful for build
          system environments where safety against abnormal system shutdown is
          not essential as all build artifacts can be regenerated any time, but
          the performance win is beneficial.

        * systemd-nspawn will now raise the RLIMIT_NOFILE hard limit to the
          same value that PID 1 uses for most forked off processes.

        * systemd-nspawn's --bind=/--bind-ro= switches now optionally take
          uidmap/nouidmap options as last parameter. If "uidmap" is used the
          bind mounts are created with UID mapping taking place that ensures
          the host's file ownerships are mapped 1:1 to container file
          ownerships, even if user namespacing is used. This way
          files/directories bound into containers will no longer show up as
          owned by the nobody user as they typically did if no special care was
          taken to shift them manually.

        * When discovering Windows installations sd-boot will now attempt to
          show the Windows version.

        * The color scheme to use in sd-boot may now be configured at
          build-time.

        * sd-boot gained the ability to change screen resolution during
          boot-time, by hitting the "r" key. This will cycle through available
          resolutions and save the last selection.

        * sd-boot learnt a new hotkey "f". When pressed the system will enter
          firmware setup. This is useful in environments where it is difficult
          to hit the right keys early enough to enter the firmware, and works
          on any firmware regardless which key it natively uses.

        * sd-boot gained support for automatically booting into the menu item
          selected on the last boot (using the "@saved" identifier for menu
          items).

        * sd-boot gained support for automatically loading all EFI drivers
          placed in the /EFI/systemd/drivers/ subdirectory of the EFI System
          Partition (ESP). These drivers are loaded before the menu entries are
          loaded. This is useful e.g. to load additional file system drivers
          for the XBOOTLDR partition.

        * systemd-boot will now paint the input cursor on its own instead of
          relying on the firmware to do so, increasing compatibility with broken
          firmware that doesn't make the cursor reasonably visible.

        * sd-boot now embeds a .osrel PE section like we expect from Boot
          Loader Specification Type #2 Unified Kernels. This means sd-boot
          itself may be used in place of a Type #2 Unified Kernel. This is
          useful for debugging purposes as it allows chain-loading one a
          (development) sd-boot instance from another.

        * sd-boot now supports a new "devicetree" field in Boot Loader
          Specification Type #1 entries: if configured the specified device
          tree file is installed before the kernel is invoked. This is useful
          for installing/applying new devicetree files without updating the
          kernel image.

        * Similarly, sd-stub now can read devicetree data from a PE section
          ".dtb" and apply it before invoking the kernel.

        * sd-stub (the EFI stub that can be glued in front of a Linux kernel)
          gained the ability to pick up credentials and sysext files, wrap them
          in a cpio archive, and pass as an additional initrd to the invoked
          Linux kernel, in effect placing those files in the /.extra/ directory
          of the initrd environment. This is useful to implement trusted initrd
          environments which are fully authenticated but still can be extended
          (via sysexts) and parameterized (via encrypted/authenticated
          credentials, see above).

          Credentials can be located next to the kernel image file (credentials
          specific to a single boot entry), or in one of the shared directories
          (credentials applicable to multiple boot entries).

        * sd-stub now comes with a full man page, that explains its feature set
          and how to combine a kernel image, an initrd and the stub to build a
          complete EFI unified kernel image, implementing Boot Loader
          Specification Type #2.

        * sd-stub may now provide the initrd to the executed kernel via the
          LINUX_EFI_INITRD_MEDIA_GUID EFI protocol, adding compatibility for
          non-x86 architectures.

        * bootctl learnt new set-timeout and set-timeout-oneshot commands that
          may be used to set the boot menu time-out of the boot loader (for all
          or just the subsequent boot).

        * bootctl and kernel-install will now read variables
          KERNEL_INSTALL_LAYOUT= from /etc/machine-info and layout= from
          /etc/kernel/install.conf. When set, it specifies the layout to use
          for installation directories on the boot partition, so that tools
          don't need to guess it based on the already-existing directories. The
          only value that is defined natively is "bls", corresponding to the
          layout specified in
          https://systemd.io/BOOT_LOADER_SPECIFICATION/. Plugins for
          kernel-install that implement a different layout can declare other
          values for this variable.

          'bootctl install' will now write KERNEL_INSTALL_LAYOUT=bls, on the
          assumption that if the user installed sd-boot to the ESP, they intend
          to use the entry layout understood by sd-boot. It'll also write
          KERNEL_INSTALL_MACHINE_ID= if it creates any directories using the ID
          (and it wasn't specified in the config file yet). Similarly,
          kernel-install will now write KERNEL_INSTALL_MACHINE_ID= (if it
          wasn't specified in the config file yet). Effectively, those changes
          mean that the machine-id used for boot loader entry installation is
          "frozen" upon first use and becomes independent of the actual
          machine-id.

          Configuring KERNEL_INSTALL_MACHINE_ID fixes the following problem:
          images created for distribution ("golden images") are built with no
          machine-id, so that a unique machine-id can be created on the first
          boot. But those images may contain boot loader entries with the
          machine-id used during build included in paths. Using a "frozen"
          value allows unambiguously identifying entries that match the
          specific installation, while still permitting parallel installations
          without conflict.

          Configuring KERNEL_INSTALL_LAYOUT obviates the need for
          kernel-install to guess the installation layout. This fixes the
          problem where a (possibly empty) directory in the boot partition is
          created from a different layout causing kernel-install plugins to
          assume the wrong layout. A particular example of how this may happen
          is the grub2 package in Fedora which includes directories under /boot
          directly in its file list. Various other packages pull in grub2 as a
          dependency, so it may be installed even if unused, breaking
          installations that use the bls layout.

        * bootctl and systemd-bless-boot can now be linked statically.

        * systemd-sysext now optionally doesn't insist on extension-release.d/
          files being placed in the image under the image's file name. If the
          file system xattr user.extension-release.strict is set on the
          extension release file, it is accepted regardless of its name. This
          relaxes security restrictions a bit, as system extension may be
          attached under a wrong name this way.

        * udevadm's test-builtin command learnt a new --action= switch for
          testing the built-in with the specified action (in place of the
          default 'add').

        * udevadm info gained new switches --property=/--value for showing only
          specific udev properties/values instead of all.

        * A new hwdb database has been added that contains matches for various
          types of signal analyzers (protocol analyzers, logic analyzers,
          oscilloscopes, multimeters, bench power supplies, etc.) that should
          be accessible to regular users.

        * A new hwdb database entry has been added that carries information
          about types of cameras (regular or infrared), and in which direction
          they point (front or back).

        * A new rule to allow console users access to rfkill by default has been
          added to hwdb.

        * Device nodes for the Software Guard eXtension enclaves (sgx_vepc) are
          now also owned by the system group "sgx".

        * A new build-time meson option "extra-net-naming-schemes=" has been
          added to define additional naming schemes for udev's network
          interface naming logic. This is useful for enterprise distributions
          and similar which want to pin the schemes of certain distribution
          releases under a specific name and previously had to patch the
          sources to introduce new named schemes.

        * The predictable naming logic for network interfaces has been extended
          to generate stable names from Xen netfront device information.

        * hostnamed's chassis property can now be sourced from chassis-type
          field encoded in devicetree (in addition to the existing DMI
          support).

        * systemd-cgls now optionally displays cgroup IDs and extended
          attributes for each cgroup. (Controllable via the new --xattr= +
          --cgroup-id= switches.)

        * coredumpctl gained a new --all switch for operating on all
          Journal files instead of just the local ones.

        * systemd-coredump will now use libdw/libelf via dlopen() rather than
          directly linking, allowing users to easily opt-out of backtrace/metadata
          analysis of core files, and reduce image sizes when this is not needed.

        * systemd-coredump will now analyze core files with libdw/libelf in a
          forked, sandboxed process.

        * systemd-homed will now try to unmount an activate home area in
          regular intervals once the user logged out fully. Previously this was
          attempted exactly once but if the home directory was busy for some
          reason it was not tried again.

        * systemd-homed's LUKS2 home area backend will now create a BSD file
          system lock on the image file while the home area is active
          (i.e. mounted). If a home area is found to be locked, logins are
          politely refused. This should improve behavior when using home areas
          images that are accessible via the network from multiple clients, and
          reduce the chance of accidental file system corruption in that case.

        * Optionally, systemd-homed will now drop the kernel buffer cache once
          a user has fully logged out, configurable via the new --drop-caches=
          homectl switch.

        * systemd-homed now makes use of UID mapped mounts for the home areas.
          If the kernel and used file system support it, files are now
          internally owned by the "nobody" user (i.e. the user typically used
          for indicating "this ownership is not mapped"), and dynamically
          mapped to the UID used locally on the system via the UID mapping
          mount logic of recent kernels. This makes migrating home areas
          between different systems cheaper because recursively chown()ing file
          system trees is no longer necessary.

        * systemd-homed's CIFS backend now optionally supports CIFS service
          names with a directory suffix, in order to place home directories in
          a subdirectory of a CIFS share, instead of the top-level directory.

        * systemd-homed's CIFS backend gained support for specifying additional
          mount options in the JSON user record (cifsExtraMountOptions field,
          and --cifs-extra-mount-options= homectl switch). This is for example
          useful for configuring mount options such as "noserverino" that some
          SMB3 services require (use that to run a homed home directory from a
          FritzBox SMB3 share this way).

        * systemd-homed will now default to btrfs' zstd compression for home
          areas. This is inspired by Fedora's recent decision to switch to zstd
          by default.

        * Additional mount options to use when mounting the file system of
          LUKS2 volumes in systemd-homed has been added. Via the
          $SYSTEMD_HOME_MOUNT_OPTIONS_BTRFS, $SYSTEMD_HOME_MOUNT_OPTIONS_EXT4,
          $SYSTEMD_HOME_MOUNT_OPTIONS_XFS environment variables to
          systemd-homed or via the luksExtraMountOptions user record JSON
          property. (Exposed via homectl --luks-extra-mount-options)

        * homectl's resize command now takes the special size specifications
          "min" and "max" to shrink/grow the home area to the minimum/maximum
          size possible, taking disk usage/space constraints and file system
          limitations into account. Resizing is now generally graceful: the
          logic will try to get as close to the specified size as possible, but
          not consider it a failure if the request couldn't be fulfilled
          precisely.

        * systemd-homed gained the ability to automatically shrink home areas
          on logout to their minimal size and grow them again on next
          login. This ensures that while inactive, a home area only takes up
          the minimal space necessary, but once activated, it provides
          sufficient space for the user's needs. This behavior is only
          supported if btrfs is used as file system inside the home area
          (because only for btrfs online growing/shrinking is implemented in
          the kernel). This behavior is now enabled by default, but may be
          controlled via the new --auto-resize-mode= setting of homectl.

        * systemd-homed gained support for automatically re-balancing free disk
          space among active home areas, in case the LUKS2 backends are used,
          and no explicit disk size was requested. This way disk space is
          automatically managed and home areas resized in regular intervals and
          manual resizing when disk space becomes scarce should not be
          necessary anymore. This behavior is only supported if btrfs is used
          within the home areas (as only then online shrinking and growing is
          supported), and may be configured via the new rebalanceWeight JSON
          user record field (as exposed via the new --rebalance-weight= homectl
          setting). Re-balancing is mostly automatic, but can also be requested
          explicitly via "homectl rebalance", which is synchronous, and thus
          may be used to wait until the rebalance run is complete.

        * userdbctl gained a --json= switch for configured the JSON formatting
          to use when outputting user or group records.

        * userdbctl gained a new --multiplexer= switch for explicitly
          configuring whether to use the systemd-userdbd server side user
          record resolution logic.

        * userdbctl's ssh-authorized-keys command learnt a new --chain switch,
          for chaining up another command to execute after completing the
          look-up. Since the OpenSSH's AuthorizedKeysCommand only allows
          configuration of a single command to invoke, this maybe used to
          invoke multiple: first userdbctl's own implementation, and then any
          other also configured in the command line.

        * The sd-event API gained a new function sd_event_add_inotify_fd() that
          is similar to sd_event_add_inotify() but accepts a file descriptor
          instead of a path in the file system for referencing the inode to
          watch.

        * The sd-event API gained a new function
          sd_event_source_set_ratelimit_expire_callback() that may be used to
          define a callback function that is called whenever an event source
          leaves the rate limiting phase.

        * New documentation has been added explaining which steps are necessary
          to port systemd to a new architecture:

          https://systemd.io/PORTING_TO_NEW_ARCHITECTURES

        * The x-systemd.makefs option in /etc/fstab now explicitly supports
          ext2, ext3, and f2fs file systems.

        * Mount units and units generated from /etc/fstab entries with 'noauto'
          are now ordered the same as other units. Effectively, they will be
          started earlier (if something actually pulled them in) and stopped
          later, similarly to normal mount units that are part of
          fs-local.target. This change should be invisible to users, but
          should prevent those units from being stopped too early during
          shutdown.

        * The systemd-getty-generator now honors a new kernel command line
          argument systemd.getty_auto= and a new environment variable
          $SYSTEMD_GETTY_AUTO that allows turning it off at boot. This is for
          example useful to turn off gettys inside of containers or similar
          environments.

        * systemd-resolved now listens on a second DNS stub address: 127.0.0.54
          (in addition to 127.0.0.53, as before). If DNS requests are sent to
          this address they are propagated in "bypass" mode only, i.e. are
          almost not processed locally, but mostly forwarded as-is to the
          current upstream DNS servers. This provides a stable DNS server
          address that proxies all requests dynamically to the right upstream
          DNS servers even if these dynamically change. This stub does not do
          mDNS/LLMNR resolution. However, it will translate look-ups to
          DNS-over-TLS if necessary. This new stub is particularly useful in
          container/VM environments, or for tethering setups: use DNAT to
          redirect traffic to any IP address to this stub.

        * systemd-importd now honors new environment variables
          $SYSTEMD_IMPORT_BTRFS_SUBVOL, $SYSTEMD_IMPORT_BTRFS_QUOTA,
          $SYSTEMD_IMPORT_SYNC, which may be used disable btrfs subvolume
          generation, btrfs quota setup and disk synchronization.

        * systemd-importd and systemd-resolved can now be optionally built with
          OpenSSL instead of libgcrypt.

        * systemd-repart no longer requires OpenSSL.

        * systemd-sysusers will no longer create the redundant 'nobody' group
          by default, as the 'nobody' user is already created with an
          appropriate primary group.

        * If a unit uses RuntimeMaxSec, systemctl show will now display it.

        * systemctl show-environment gained support for --output=json.

        * pam_systemd will now first try to use the X11 abstract socket, and
          fallback to the socket file in /tmp/.X11-unix/ only if that does not
          work.

        * systemd-journald will no longer go back to volatile storage
          regardless of configuration when its unit is restarted.

        * Initial support for the LoongArch architecture has been added (system
          call lists, GPT partition table UUIDs, etc).

        * systemd-journald's own logging messages are now also logged to the
          journal itself when systemd-journald logs to /dev/kmsg.

        * systemd-journald now re-enables COW for archived journal files on
          filesystems that support COW. One benefit of this change is that
          archived journal files will now get compressed on btrfs filesystems
          that have compression enabled.

        * systemd-journald now deduplicates fields in a single log message
          before adding it to the journal. In archived journal files, it will
          also punch holes for unused parts and truncate the file as
          appropriate, leading to reductions in disk usage.

        * journalctl --verify was extended with more informative error
          messages.

        * More of sd-journal's functions are now resistant against journal file
          corruption.

        * The shutdown command learnt a new option --show, to display the
          scheduled shutdown.

        * A LICENSES/ directory is now included in the git tree. It contains a
          README.md file that explains the licenses used by source files in
          this repository.  It also contains the text of all applicable
          licenses as they appear on spdx.org.

        Contributions from: Aakash Singh, acsfer, Adolfo Jayme Barrientos,
        Adrian Vovk, Albert Brox, Alberto Mardegan, Alexander Kanavin,
        alexlzhu, Alfonso Sánchez-Beato, Alvin Šipraga, Alyssa Ross,
        Amir Omidi, Anatol Pomozov, Andika Triwidada, Andreas Rammhold,
        Andreas Valder, Andrej Lajovic, Andrew Soutar, Andrew Stone, Andy Chi,
        Anita Zhang, Anssi Hannula, Antonio Alvarez Feijoo,
        Antony Deepak Thomas, Arnaud Ferraris, Arvid E. Picciani,
        Bastien Nocera, Benjamin Berg, Benjamin Herrenschmidt, Ben Stockett,
        Bogdan Seniuc, Boqun Feng, Carl Lei, chlorophyll-zz, Chris Packham,
        Christian Brauner, Christian Göttsche, Christian Wehrli,
        Christoph Anton Mitterer, Cristian Rodríguez, Daan De Meyer,
        Daniel Maixner, Dann Frazier, Dan Streetman, Davide Cavalca,
        David Seifert, David Tardon, dependabot[bot], Dimitri John Ledkov,
        Dimitri Papadopoulos, Dimitry Ishenko, Dmitry Khlebnikov,
        Dominique Martinet, duament, Egor, Egor Ignatov, Emil Renner Berthing,
        Emily Gonyer, Ettore Atalan, Evgeny Vereshchagin, Florian Klink,
        Franck Bui, Frantisek Sumsal, Geass-LL, Gibeom Gwon, GnunuX,
        Gogo Gogsi, gregzuro, Greg Zuro, Gustavo Costa, Hans de Goede,
        Hela Basa, Henri Chain, hikigaya58, Hugo Carvalho,
        Hugo Osvaldo Barrera, Iago Lopez Galeiras, Iago López Galeiras,
        I-dont-need-name, igo95862, Jack Dähn, James Hilliard, Jan Janssen,
        Jan Kuparinen, Jan Macku, Jan Palus, Jarkko Sakkinen, Jayce Fayne,
        jiangchuangang, jlempen, John Lindgren, Jonas Dreßler, Jonas Jelten,
        Jonas Witschel, Joris Hartog, José Expósito, Julia Kartseva,
        Kai-Heng Feng, Kai Wohlfahrt, Kay Siver Bø, KennthStailey,
        Kevin Kuehler, Kevin Orr, Khem Raj, Kristian Klausen, Kyle Laker,
        lainahai, LaserEyess, Lennart Poettering, Lia Lenckowski, longpanda,
        Luca Boccassi, Luca BRUNO, Ludwig Nussel, Lukas Senionis,
        Maanya Goenka, Maciek Borzecki, Marcel Menzel, Marco Scardovi,
        Marcus Harrison, Mark Boudreau, Matthijs van Duin, Mauricio Vásquez,
        Maxime de Roucy, Max Resch, MertsA, Michael Biebl, Michael Catanzaro,
        Michal Koutný, Michal Sekletár, Miika Karanki, Mike Gilbert,
        Milo Turner, ml, monosans, Nacho Barrientos, nassir90, Nishal Kulkarni,
        nl6720, Ondrej Kozina, Paulo Neves, Pavel Březina, pedro martelletto,
        Peter Hutterer, Peter Morrow, Piotr Drąg, Rasmus Villemoes, ratijas,
        Raul Tambre, rene, Riccardo Schirone, Robert-L-Turner, Robert Scheck,
        Ross Jennings, saikat0511, Scott Lamb, Scott Worley,
        Sergei Trofimovich, Sho Iizuka, Slava Bacherikov, Slimane Selyan Amiri,
        StefanBruens, Steven Siloti, svonohr, Taiki Sugawara, Takashi Sakamoto,
        Takuro Onoue, Thomas Blume, Thomas Haller, Thomas Mühlbacher,
        Tianlu Shao, Toke Høiland-Jørgensen, Tom Yan, Tony Asleson,
        Topi Miettinen, Ulrich Ölmann, Urs Ritzmann, Vincent Bernat,
        Vito Caputo, Vladimir Panteleev, WANG Xuerui, Wind/owZ, Wu Xiaotian,
        xdavidwu, Xiaotian Wu, xujing, yangmingtai, Yao Wei, Yao Wei (魏銘廷),
        Yegor Alexeyev, Yu Watanabe, Zbigniew Jędrzejewski-Szmek,
        Дамјан Георгиевски, наб

        — Warsaw, 2021-12-23

CHANGES WITH 249:

        * When operating on disk images via the --image= switch of various
          tools (such as systemd-nspawn or systemd-dissect), or when udev finds
          no 'root=' parameter on the kernel command line, and multiple
          suitable root or /usr/ partitions exist in the image, then a simple
          comparison inspired by strverscmp() is done on the GPT partition
          label, and the newest partition is picked. This permits a simple and
          generic whole-file-system A/B update logic where new operating system
          versions are dropped into partitions whose label is then updated with
          a matching version identifier.

        * systemd-sysusers now supports querying the passwords to set for the
          users it creates via the "credentials" logic introduced in v247: the
          passwd.hashed-password.<user> and passwd.plaintext-password.<user>
          credentials are consulted for the password to use (either in UNIX
          hashed form, or literally). By default these credentials are inherited
          down from PID1 (which in turn imports it from a container manager if
          there is one). This permits easy configuration of user passwords
          during first boot. Example:

          # systemd-nspawn -i foo.raw --volatile=yes --set-credential=passwd.plaintext-password.root:foo

          Note that systemd-sysusers operates in purely additive mode: it
          executes no operation if the declared users already exist, and hence
          doesn't set any passwords as effect of the command line above if the
          specified root user exists already in the image. (Note that
          --volatile=yes ensures it doesn't, though.)

        * systemd-firstboot now also supports querying various system
          parameters via the credential subsystems. Thus, as above this may be
          used to initialize important system parameters on first boot of
          previously unprovisioned images (i.e. images with a mostly empty
          /etc/).

        * PID 1 may now show both the unit name and the unit description
          strings in its status output during boot. This may be configured with
          StatusUnitFormat=combined in system.conf or
          systemd.status-unit-format=combined on the kernel command line.

        * The systemd-machine-id-setup tool now supports a --image= switch for
          provisioning a machine ID file into an OS disk image, similar to how
          --root= operates on an OS file tree. This matches the existing switch
          of the same name for systemd-tmpfiles, systemd-firstboot, and
          systemd-sysusers tools.

        * Similarly, systemd-repart gained support for the --image= switch too.
          In combination with the existing --size= option, this makes the tool
          particularly useful for easily growing disk images in a single
          invocation, following the declarative rules included in the image
          itself.

        * systemd-repart's partition configuration files gained support for a
          new switch MakeDirectories= which may be used to create arbitrary
          directories inside file systems that are created, before registering
          them in the partition table. This is useful in particular for root
          partitions to create mount point directories for other partitions
          included in the image. For example, a disk image that contains a
          root, /home/, and /var/ partitions, may set MakeDirectories=yes to
          create /home/ and /var/ as empty directories in the root file system
          on its creation, so that the resulting image can be mounted
          immediately, even in read-only mode.

        * systemd-repart's CopyBlocks= setting gained support for the special
          value "auto". If used, a suitable matching partition on the booted OS
          is found as source to copy blocks from. This is useful when
          implementing replicating installers, that are booted from one medium
          and then stream their own root partition onto the target medium.

        * systemd-repart's partition configuration files gained support for a
          Flags=, a ReadOnly= and a NoAuto= setting, allowing control of these
          GPT partition flags for the created partitions: this is useful for
          marking newly created partitions as read-only, or as not being
          subject for automatic mounting from creation on.

        * The /etc/os-release file has been extended with two new (optional)
          variables IMAGE_VERSION= and IMAGE_ID=, carrying identity and version
          information for OS images that are updated comprehensively and
          atomically as one image. Two new specifiers %M, %A now resolve to
          these two fields in the various configuration options that resolve
          specifiers.

        * portablectl gained a new switch --extension= for enabling portable
          service images with extensions that follow the extension image
          concept introduced with v248, and thus allows layering multiple
          images when setting up the root filesystem of the service.

        * systemd-coredump will now extract ELF build-id information from
          processes dumping core and include it in the coredump report.
          Moreover, it will look for ELF .note.package sections with
          distribution packaging meta-information about the crashing process.
          This is useful to directly embed the rpm or deb (or any other)
          package name and version in ELF files, making it easy to match
          coredump reports with the specific package for which the software was
          compiled. This is particularly useful on environments with ELF files
          from multiple vendors, different distributions and versions, as is
          common today in our containerized and sand-boxed world. For further
          information, see:

          https://systemd.io/COREDUMP_PACKAGE_METADATA

        * A new udev hardware database has been added for FireWire devices
          (IEEE 1394).

        * The "net_id" built-in of udev has been updated with three
          backwards-incompatible changes:

          - PCI hotplug slot names on s390 systems are now parsed as
            hexadecimal numbers. They were incorrectly parsed as decimal
            previously, or ignored if the name was not a valid decimal
            number.

          - PCI onboard indices up to 65535 are allowed. Previously, numbers
            above 16383 were rejected. This primarily impacts s390 systems,
            where values up to 65535 are used.

          - Invalid characters in interface names are replaced with "_".

          The new version of the net naming scheme is "v249". The previous
          scheme can be selected via the "net.naming-scheme=v247" kernel
          command line parameter.

        * sd-bus' sd_bus_is_ready() and sd_bus_is_open() calls now accept a
          NULL bus object, for which they will return false. Or in other words,
          an unallocated bus connection is neither ready nor open.

        * The sd-device API acquired a new API function
          sd_device_get_usec_initialized() that returns the monotonic time when
          the udev device first appeared in the database.

        * sd-device gained a new APIs sd_device_trigger_with_uuid() and
          sd_device_get_trigger_uuid(). The former is similar to
          sd_device_trigger() but returns a randomly generated UUID that is
          associated with the synthetic uevent generated by the call. This UUID
          may be read from the sd_device object a monitor eventually receives,
          via the sd_device_get_trigger_uuid(). This interface requires kernel
          4.13 or above to work, and allows tracking a synthetic uevent through
          the entire device management stack. The "udevadm trigger --settle"
          logic has been updated to make use of this concept if available to
          wait precisely for the uevents it generates. "udevadm trigger" also
          gained a new parameter --uuid that prints the UUID for each generated
          uevent.

        * sd-device also gained new APIs sd_device_new_from_ifname() and
          sd_device_new_from_ifindex() for allocating an sd-device object for
          the specified network interface. The former accepts an interface name
          (either a primary or an alternative name), the latter an interface
          index.

        * The native Journal protocol has been documented. Clients may talk
          this as alternative to the classic BSD syslog protocol for locally
          delivering log records to the Journal. The protocol has been stable
          for a long time and in fact been implemented already in a variety
          of alternative client libraries. This documentation makes the support
          for that official:

          https://systemd.io/JOURNAL_NATIVE_PROTOCOL

        * A new BPFProgram= setting has been added to service files. It may be
          set to a path to a loaded kernel BPF program, i.e. a path to a bpffs
          file, or a bind mount or symlink to one. This may be used to upload
          and manage BPF programs externally and then hook arbitrary systemd
          services into them.

        * The "home.arpa" domain that has been officially declared as the
          choice for domain for local home networks per RFC 8375 has been added
          to the default NTA list of resolved, since DNSSEC is generally not
          available on private domains.

        * The CPUAffinity= setting of unit files now resolves "%" specifiers.

        * A new ManageForeignRoutingPolicyRules= setting has been added to
          .network files which may be used to exclude foreign-created routing
          policy rules from systemd-networkd management.

        * systemd-network-wait-online gained two new switches -4 and -6 that
          may be used to tweak whether to wait for only IPv4 or only IPv6
          connectivity.

        * .network files gained a new RequiredFamilyForOnline= setting to
          fine-tune whether to require an IPv4 or IPv6 address in order to
          consider an interface "online".

        * networkctl will now show an over-all "online" state in the per-link
          information.

        * In .network files a new OutgoingInterface= setting has been added to
          specify the output interface in bridge FDB setups.

        * In .network files the Multipath group ID may now be configured for
          [NextHop] entries, via the new Group= setting.

        * The DHCP server logic configured in .network files gained a new
          setting RelayTarget= that turns the server into a DHCP server relay.
          The RelayAgentCircuitId= and RelayAgentRemoteId= settings may be used
          to further tweak the DHCP relay behaviour.

        * The DHCP server logic also gained a new ServerAddress= setting in
          .network files that explicitly specifies the server IP address to
          use. If not specified, the address is determined automatically, as
          before.

        * The DHCP server logic in systemd-networkd gained support for static
          DHCP leases, configurable via the [DHCPServerStaticLease]
          section. This allows explicitly mapping specific MAC addresses to
          fixed IP addresses and vice versa.

        * The RestrictAddressFamilies= setting in service files now supports a
          new special value "none". If specified sockets of all address
          families will be made unavailable to services configured that way.

        * systemd-fstab-generator and systemd-repart have been updated to
          support booting from disks that carry only a /usr/ partition but no
          root partition yet, and where systemd-repart can add it in on the
          first boot. This is useful for implementing systems that ship with a
          single /usr/ file system, and whose root file system shall be set up
          and formatted on a LUKS-encrypted volume whose key is generated
          locally (and possibly enrolled in the TPM) during the first boot.

        * The [Address] section of .network files now accepts a new
          RouteMetric= setting that configures the routing metric to use for
          the prefix route created as effect of the address configuration.
          Similarly, the [DHCPv6PrefixDelegation] and [IPv6Prefix] sections
          gained matching settings for their prefix routes. (The option of the
          same name in the [DHCPv6] section is moved to [IPv6AcceptRA], since
          it conceptually belongs there; the old option is still understood for
          compatibility.)

        * The DHCPv6 IAID and DUID are now explicitly configurable in .network
          files.

        * A new udev property ID_NET_DHCP_BROADCAST on network interface
          devices is now honoured by systemd-networkd, controlling whether to
          issue DHCP offers via broadcasting. This is used to ensure that s390
          layer 3 network interfaces work out-of-the-box with systemd-networkd.

        * nss-myhostname and systemd-resolved will now synthesize address
          records for a new special hostname "_outbound". The name will always
          resolve to the local IP addresses most likely used for outbound
          connections towards the default routes. On multi-homed hosts this is
          useful to have a stable handle referring to "the" local IP address
          that matters most, to the point where this is defined.

        * The Discoverable Partition Specification has been updated with a new
          GPT partition flag "grow-file-system" defined for its partition
          types. Whenever partitions with this flag set are automatically
          mounted (i.e. via systemd-gpt-auto-generator or the --image= switch
          of systemd-nspawn or other tools; and as opposed to explicit mounting
          via /etc/fstab), the file system within the partition is
          automatically grown to the full size of the partition. If the file
          system size already matches the partition size this flag has no
          effect. Previously, this functionality has been available via the
          explicit x-systemd.growfs mount option, and this new flag extends
          this to automatically discovered mounts. A new GrowFileSystem=
          setting has been added to systemd-repart drop-in files that allows
          configuring this partition flag. This new flag defaults to on for
          partitions automatically created by systemd-repart, except if they
          are marked read-only. See the specification for further details:

          https://systemd.io/DISCOVERABLE_PARTITIONS

        * .network files gained a new setting RoutesToNTP= in the [DHCPv4]
          section. If enabled (which is the default), and an NTP server address
          is acquired through a DHCP lease on this interface an explicit route
          to this address is created on this interface to ensure that NTP
          traffic to the NTP server acquired on an interface is also routed
          through that interface. The pre-existing RoutesToDNS= setting that
          implements the same for DNS servers is now enabled by default.

        * A pair of service settings SocketBindAllow= + SocketBindDeny= have
          been added that may be used to restrict the network interfaces
          sockets created by the service may be bound to. This is implemented
          via BPF.

        * A new ConditionFirmware= setting has been added to unit files to
          conditionalize on certain firmware features. At the moment it may
          check whether running on an UEFI system, a device.tree system, or if
          the system is compatible with some specified device-tree feature.

        * A new ConditionOSRelease= setting has been added to unit files to
          check os-release(5) fields. The "=", "!=", "<", "<=", ">=", ">"
          operators may be used to check if some field has some specific value
          or do an alphanumerical comparison. Equality comparisons are useful
          for fields like ID, but relative comparisons for fields like
          VERSION_ID or IMAGE_VERSION.

        * hostnamed gained a new Describe() D-Bus method that returns a JSON
          serialization of the host data it exposes. This is exposed via
          "hostnamectl --json=" to acquire a host identity description in JSON.
          It's our intention to add a similar features to most services and
          objects systemd manages, in order to simplify integration with
          program code that can consume JSON.

        * Similarly, networkd gained a Describe() method on its Manager and
          Link bus objects. This is exposed via "networkctl --json=".

        * hostnamectl's various "get-xyz"/"set-xyz" verb pairs
          (e.g. "hostnamectl get-hostname", "hostnamectl "set-hostname") have
          been replaced by a single "xyz" verb (e.g. "hostnamectl hostname")
          that is used both to get the value (when no argument is given), and
          to set the value (when an argument is specified). The old names
          continue to be supported for compatibility.

        * systemd-detect-virt and ConditionVirtualization= are now able to
          correctly identify Amazon EC2 environments.

        * The LogLevelMax= setting of unit files now applies not only to log
          messages generated *by* the service, but also to log messages
          generated *about* the service by PID 1. To suppress logs concerning a
          specific service comprehensively, set this option to a high log
          level.

        * bootctl gained support for a new --make-machine-id-directory= switch
          that allows precise control on whether to create the top-level
          per-machine directory in the boot partition that typically contains
          Type 1 boot loader entries.

        * During build SBAT data to include in the systemd-boot EFI PE binaries
          may be specified now.

        * /etc/crypttab learnt a new option "headless". If specified any
          requests to query the user interactively for passwords or PINs will
          be skipped. This is useful on systems that are headless, i.e. where
          an interactive user is generally not present.

        * /etc/crypttab also learnt a new option "password-echo=" that allows
          configuring whether the encryption password prompt shall echo the
          typed password and if so, do so literally or via asterisks. (The
          default is the same behaviour as before: provide echo feedback via
          asterisks.)

        * FIDO2 support in systemd-cryptenroll/systemd-cryptsetup and
          systemd-homed has been updated to allow explicit configuration of the
          "user presence" and "user verification" checks, as well as whether a
          PIN is required for authentication, via the new switches
          --fido2-with-user-presence=, --fido2-with-user-verification=,
          --fido2-with-client-pin= to systemd-cryptenroll and homectl. Which
          features are available, and may be enabled or disabled depends on the
          used FIDO2 token.

        * systemd-nspawn's --private-user= switch now accepts the special value
          "identity" which configures a user namespacing environment with an
          identity mapping of 65535 UIDs. This means the container UID 0 is
          mapped to the host UID 0, and the UID 1 to host UID 1. On first look
          this doesn't appear to be useful, however it does reduce the attack
          surface a bit, since the resulting container will possess process
          capabilities only within its namespace and not on the host.

        * systemd-nspawn's --private-user-chown switch has been replaced by a
          more generic --private-user-ownership= switch that accepts one of
          three values: "chown" is equivalent to the old --private-user-chown,
          and "off" is equivalent to the absence of the old switch. The value
          "map" uses the new UID mapping mounts of Linux 5.12 to map ownership
          of files and directories of the underlying image to the chosen UID
          range for the container. "auto" is equivalent to "map" if UID mapping
          mount are supported, otherwise it is equivalent to "chown". The short
          -U switch systemd-nspawn now implies --private-user-ownership=auto
          instead of the old --private-user-chown. Effectively this means: if
          the backing file system supports UID mapping mounts the feature is
          now used by default if -U is used. Generally, it's a good idea to use
          UID mapping mounts instead of recursive chown()ing, since it allows
          running containers off immutable images (since no modifications of
          the images need to take place), and share images between multiple
          instances. Moreover, the recursive chown()ing operation is slow and
          can be avoided. Conceptually it's also a good thing if transient UID
          range uses do not leak into persistent file ownership anymore. TLDR:
          finally, the last major drawback of user namespacing has been
          removed, and -U should always be used (unless you use btrfs, where
          UID mapped mounts do not exist; or your container actually needs
          privileges on the host).

        * nss-systemd now synthesizes user and group shadow records in addition
          to the main user and group records. Thus, hashed passwords managed by
          systemd-homed are now accessible via the shadow database.

        * The userdb logic (and thus nss-systemd, and so on) now read
          additional user/group definitions in JSON format from the drop-in
          directories /etc/userdb/, /run/userdb/, /run/host/userdb/ and
          /usr/lib/userdb/. This is a simple and powerful mechanism for making
          additional users available to the system, with full integration into
          NSS including the shadow databases. Since the full JSON user/group
          record format is supported this may also be used to define users with
          resource management settings and other runtime settings that
          pam_systemd and systemd-logind enforce at login.

        * The userdbctl tool gained two new switches --with-dropin= and
          --with-varlink= which can be used to fine-tune the sources used for
          user database lookups.

        * systemd-nspawn gained a new switch --bind-user= for binding a host
          user account into the container. This does three things: the user's
          home directory is bind mounted from the host into the container,
          below the /run/userdb/home/ hierarchy. A free UID is picked in the
          container, and a user namespacing UID mapping to the host user's UID
          installed. And finally, a minimal JSON user and group record (along
          with its hashed password) is dropped into /run/host/userdb/. These
          records are picked up automatically by the userdb drop-in logic
          describe above, and allow the user to login with the same password as
          on the host. Effectively this means: if host and container run new
          enough systemd versions making a host user available to the container
          is trivially simple.

        * systemd-journal-gatewayd now supports the switches --user, --system,
          --merge, --file= that are equivalent to the same switches of
          journalctl, and permit exposing only the specified subset of the
          Journal records.

        * The OnFailure= dependency between units is now augmented with a
          implicit reverse dependency OnFailureOf= (this new dependency cannot
          be configured directly it's only created as effect of an OnFailure=
          dependency in the reverse order — it's visible in "systemctl show"
          however). Similar, Slice= now has an reverse dependency SliceOf=,
          that is also not configurable directly, but useful to determine all
          units that are members of a slice.

        * A pair of new dependency types between units PropagatesStopTo= +
          StopPropagatedFrom= has been added, that allows propagation of unit
          stop events between two units. It operates similar to the existing
          PropagatesReloadTo= + ReloadPropagatedFrom= dependencies.

        * A new dependency type OnSuccess= has been added (plus the reverse
          dependency OnSuccessOf=, which cannot be configured directly, but
          exists only as effect of the reverse OnSuccess=). It is similar to
          OnFailure=, but triggers in the opposite case: when a service exits
          cleanly. This allows "chaining up" of services where one or more
          services are started once another service has successfully completed.

        * A new dependency type Upholds= has been added (plus the reverse
          dependency UpheldBy=, which cannot be configured directly, but exists
          only as effect of Upholds=). This dependency type is a stronger form
          of Wants=: if a unit has an UpHolds= dependency on some other unit
          and the former is active then the latter is started whenever it is
          found inactive (and no job is queued for it). This is an alternative
          to Restart= inside service units, but less configurable, and the
          request to uphold a unit is not encoded in the unit itself but in
          another unit that intends to uphold it.

        * The systemd-ask-password tool now also supports reading passwords
          from the credentials subsystem, via the new --credential= switch.

        * The systemd-ask-password tool learnt a new switch --emoji= which may
          be used to explicit control whether the lock and key emoji (🔐) is
          shown in the password prompt on suitable TTYs.

        * The --echo switch of systemd-ask-password now optionally takes a
          parameter that controls character echo. It may either show asterisks
          (default, as before), turn echo off entirely, or echo the typed
          characters literally.

        * The systemd-ask-password tool also gained a new -n switch for
          suppressing output of a trailing newline character when writing the
          acquired password to standard output, similar to /bin/echo's -n
          switch.

        * New documentation has been added that describes the organization of