elogind/NEWS

systemd System and Service Manager

CHANGES WITH 239:

        * NETWORK INTERFACE DEVICE NAMING CHANGES: elogind-udevd's "net_id"
          builtin will name network interfaces differently than in previous
          versions for virtual network interfaces created with SR-IOV and NPAR
          and for devices where the PCI network controller device does not have
          a slot number associated.

          SR-IOV virtual devices are now named based on the name of the parent
          interface, with a suffix of "v<N>", where <N> is the virtual device
          number. Previously those virtual devices were named as if completely
          independent.

          The ninth and later NPAR virtual devices will be named following the
          scheme used for the first eight NPAR partitions. Previously those
          devices were not renamed and the kernel default (eth<n>) was used.

          "net_id" will also generate names for PCI devices where the PCI
          network controller device does not have an associated slot number
          itself, but one of its parents does. Previously those devices were
          not renamed and the kernel default (eth<n>) was used.

        * AF_INET and AF_INET6 are dropped from RestrictAddressFamilies= in
          elogind.service. Since v235, IPAddressDeny=any has been set to
          the unit. So, it is expected that the default behavior of
          elogind is not changed. However, if distribution packagers or
          administrators disabled or modified IPAddressDeny= setting by a
          drop-in config file, then it may be necessary to update the file to
          re-enable AF_INET and AF_INET6 to support network user name services,
          e.g. NIS.

        * When the RestrictNamespaces= unit property is specified multiple
          times, then the specified types are merged now. Previously, only the
          last assignment was used. So, if distribution packagers or
          administrators modified the setting by a drop-in config file, then it
          may be necessary to update the file.

        * When OnFailure= is used in combination with Restart= on a service
          unit, then the specified units will no longer be triggered on
          failures that result in restarting. Previously, the specified units
          would be activated each time the unit failed, even when the unit was
          going to be restarted automatically. This behaviour contradicted the
          documentation. With this release the code is adjusted to match the
          documentation.

        * elogind-tmpfiles will now print a notice whenever it encounters
          tmpfiles.d/ lines referencing the /var/run/ directory. It will
          recommend reworking them to use the /run/ directory instead (for
          which /var/run/ is simply a symlinked compatibility alias). This way
          elogind-tmpfiles can properly detect line conflicts and merge lines
          referencing the same file by two paths, without having to access
          them.

        * systemctl disable/unmask/preset/preset-all cannot be used with
          --runtime. Previously this was allowed, but resulted in unintuitive
          behaviour that wasn't useful. systemctl disable/unmask will now undo
          both runtime and persistent enablement/masking, i.e. it will remove
          any relevant symlinks both in /run and /etc.

        * Note that all long-running system services shipped with elogind will
          now default to a system call whitelist (rather than a blacklist, as
          before). In particular, elogind-udevd will now enforce one too. For
          most cases this should be safe, however downstream distributions
          which disabled sandboxing of elogind-udevd (specifically the
          MountFlags= setting), might want to disable this security feature
          too, as the default whitelisting will prohibit all mount, swap,
          reboot and clock changing operations from udev rules.

        * sd-boot acquired new loader configuration settings to optionally turn
          off Windows and MacOS boot partition discovery as well as
          reboot-into-firmware menu items. It is also able to pick a better
          screen resolution for HiDPI systems, and now provides loader
          configuration settings to change the resolution explicitly.

        * elogind-resolved now supports DNS-over-TLS. It's still
          turned off by default, use DNSOverTLS=opportunistic to turn it on in
          resolved.conf. We intend to make this the default as soon as couple
          of additional techniques for optimizing the initial latency caused by
          establishing a TLS/TCP connection are implemented.

        * elogind-resolved.service and elogind-networkd.service now set
          DynamicUser=yes. The users elogind-resolve and elogind-network are
          not created by elogind-sysusers.

        * The systemd-resolve tool has been renamed to resolvectl (it also
          remains available under the old name, for compatibility), and its
          interface is now verb-based, similar in style to the other <xyz>ctl
          tools, such as systemctl or loginctl.

        * The resolvectl/elogind-resolve tool also provides 'resolvconf'
          compatibility. It may be symlinked under the 'resolvconf' name, in
          which case it will take arguments and input compatible with the
          Debian and FreeBSD resolvconf tool.

        * Support for suspend-then-hibernate has been added, i.e. a sleep mode
          where the system initially suspends, and after a time-out resumes and
          hibernates again.

        * networkd's ClientIdentifier= now accepts a new option "duid-only". If
          set the client will only send a DUID as client identifier.

        * The nss-elogind glibc NSS module will now enumerate dynamic users and
          groups in effect. Previously, it could resolve UIDs/GIDs to user
          names/groups and vice versa, but did not support enumeration.

        * journald's Compress= configuration setting now optionally accepts a
          byte threshold value. All journal objects larger than this threshold
          will be compressed, smaller ones will not. Previously this threshold
          was not configurable and set to 512.

        * A new system.conf setting NoNewPrivileges= is now available which may
          be used to turn off acquisition of new privileges system-wide
          (i.e. set Linux' PR_SET_NO_NEW_PRIVS for PID 1 itself, and thus also
          for all its children). Note that turning this option on means setuid
          binaries and file system capabilities lose their special powers.
          While turning on this option is a big step towards a more secure
          system, doing so is likely to break numerous pre-existing UNIX tools,
          in particular su and sudo.

        * A new service elogind-time-sync-wait.service has been added. If
          enabled it will delay the time-sync.target unit at boot until time
          synchronization has been received from the network. This
          functionality is useful on systems lacking a local RTC or where it is
          acceptable that the boot process shall be delayed by external network
          services.

        * When hibernating, elogind will now inform the kernel of the image
          write offset, on kernels new enough to support this. This means swap
          files should work for hibernation now.

        * When loading unit files, elogind will now look for drop-in unit files
          extensions in additional places. Previously, for a unit file name
          "foo-bar-baz.service" it would look for dropin files in
          "foo-bar-baz.service.d/*.conf". Now, it will also look in
          "foo-bar-.service.d/*.conf" and "foo-.service.d/", i.e. at the
          service name truncated after all inner dashes. This scheme allows
          writing drop-ins easily that apply to a whole set of unit files at
          once. It's particularly useful for mount and slice units (as their
          naming is prefix based), but is also useful for service and other
          units, for packages that install multiple unit files at once,
          following a strict naming regime of beginning the unit file name with
          the package's name. Two new specifiers are now supported in unit
          files to match this: %j and %J are replaced by the part of the unit
          name following the last dash.

        * Unit files and other configuration files that support specifier
          expansion now understand another three new specifiers: %T and %V will
          resolve to /tmp and /var/tmp respectively, or whatever temporary
          directory has been set for the calling user. %E will expand to either
          /etc (for system units) or $XDG_CONFIG_HOME (for user units).

        * The ExecStart= lines of unit files are no longer required to
          reference absolute paths. If non-absolute paths are specified the
          specified binary name is searched within the service manager's
          built-in $PATH, which may be queried with 'elogind-path
          search-binaries-default'. It's generally recommended to continue to
          use absolute paths for all binaries specified in unit files.

        * Units gained a new load state "bad-setting", which is used when a
          unit file was loaded, but contained fatal errors which prevent it
          from being started (for example, a service unit has been defined
          lacking both ExecStart= and ExecStop= lines).

        * coredumpctl's "gdb" verb has been renamed to "debug", in order to
          support alternative debuggers, for example lldb. The old name
          continues to be available however, for compatibility reasons. Use the
          new --debugger= switch or the $SYSTEMD_DEBUGGER environment variable
          to pick an alternative debugger instead of the default gdb.

        * systemctl and the other tools will now output escape sequences that
          generate proper clickable hyperlinks in various terminal emulators
          where useful (for example, in the "systemctl status" output you can
          now click on the unit file name to quickly open it in the
          editor/viewer of your choice). Note that not all terminal emulators
          support this functionality yet, but many do. Unfortunately, the
          "less" pager doesn't support this yet, hence this functionality is
          currently automatically turned off when a pager is started (which
          happens quite often due to auto-paging). We hope to remove this
          limitation as soon as "less" learns these escape sequences. This new
          behaviour may also be turned off explicitly with the $SYSTEMD_URLIFY
          environment variable. For details on these escape sequences see:
          https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda

        * networkd's .network files now support a new IPv6MTUBytes= option for
          setting the MTU used by IPv6 explicitly as well as a new MTUBytes=
          option in the [Route] section to configure the MTU to use for
          specific routes. It also gained support for configuration of the DHCP
          "UserClass" option through the new UserClass= setting. It gained
          three new options in the new [CAN] section for configuring CAN
          networks. The MULTICAST and ALLMULTI interface flags may now be
          controlled explicitly with the new Multicast= and AllMulticast=
          settings.

        * networkd will now automatically make use of the kernel's route
          expiration feature, if it is available.

        * udevd's .link files now support setting the number of receive and
          transmit channels, using the RxChannels=, TxChannels=,
          OtherChannels=, CombinedChannels= settings.

        * Support for UDPSegmentationOffload= has been removed, given its
          limited support in hardware, and waning software support.

        * networkd's .netdev files now support creating "netdevsim" interfaces.

        * PID 1 learnt a new bus call GetUnitByControlGroup() which may be used
          to query the unit belonging to a specific kernel control group.

        * elogind-analyze gained a new verb "cat-config", which may be used to
          dump the contents of any configuration file, with all its matching
          drop-in files added in, and honouring the usual search and masking
          logic applied to elogind configuration files. For example use
          "elogind-analyze cat-config elogind/system.conf" to get the complete
          system configuration file of elogind how it would be loaded by PID 1
          itself. Similar to this, various tools such as elogind-tmpfiles or
          elogind-sysusers, gained a new option "--cat-config", which does the
          corresponding operation for their own configuration settings. For
          example, "elogind-tmpfiles --cat-config" will now output the full
          list of tmpfiles.d/ lines in place.

        * timedatectl gained three new verbs: "show" shows bus properties of
          elogind-timedated, "timesync-status" shows the current NTP
          synchronization state of elogind-timesyncd, and "show-timesync"
          shows bus properties of elogind-timesyncd.

        * elogind-timesyncd gained a bus interface on which it exposes details
          about its state.

        * A new environment variable $SYSTEMD_TIMEDATED_NTP_SERVICES is now
          understood by elogind-timedated. It takes a colon-separated list of
          unit names of NTP client services. The list is used by
          "timedatectl set-ntp".

        * systemd-nspawn gained a new --rlimit= switch for setting initial
          resource limits for the container payload. There's a new switch
          --hostname= to explicitly override the container's hostname. A new
          --no-new-privileges= switch may be used to control the
          PR_SET_NO_NEW_PRIVS flag for the container payload. A new
          --oom-score-adjust= switch controls the OOM scoring adjustment value
          for the payload. The new --cpu-affinity= switch controls the CPU
          affinity of the container payload. The new --resolv-conf= switch
          allows more detailed control of /etc/resolv.conf handling of the
          container. Similarly, the new --timezone= switch allows more detailed
          control of /etc/localtime handling of the container.

        * elogind-detect-virt gained a new --list switch, which will print a
          list of all currently known VM and container environments.

        * Support for "Portable Services" has been added, see
          doc/PORTABLE_SERVICES.md for details. Currently, the support is still
          experimental, but this is expected to change soon. Reflecting this
          experimental state, the "portablectl" binary is not installed into
          /usr/bin yet. The binary has to be called with the full path
          /usr/lib/elogind/portablectl instead.

        * journalctl's and systemctl's -o switch now knows a new log output
          mode "with-unit". The output it generates is very similar to the
          regular "short" mode, but displays the unit name instead of the
          syslog tag for each log line. Also, the date is shown with timezone
          information. This mode is probably more useful than the classic
          "short" output mode for most purposes, except where pixel-perfect
          compatibility with classic /var/log/messages formatting is required.

        * A new --dump-bus-properties switch has been added to the elogind
          binary, which may be used to dump all supported D-Bus properties.
          (Options which are still supported, but are deprecated, are *not*
          shown.)

        * sd-bus gained a set of new calls:
          sd_bus_slot_set_floating()/sd_bus_slot_get_floating() may be used to
          enable/disable the "floating" state of a bus slot object,
          i.e. whether the slot object pins the bus it is allocated for into
          memory or if the bus slot object gets disconnected when the bus goes
          away. sd_bus_open_with_description(),
          sd_bus_open_user_with_description(),
          sd_bus_open_system_with_description() may be used to allocate bus
          objects and set their description string already during allocation.

        * sd-event gained support for watching inotify events from the event
          loop, in an efficient way, sharing inotify handles between multiple
          users. For this a new function sd_event_add_inotify() has been added.

        * sd-event and sd-bus gained support for calling special user-supplied
          destructor functions for userdata pointers associated with
          sd_event_source, sd_bus_slot, and sd_bus_track objects. For this new
          functions sd_bus_slot_set_destroy_callback,
          sd_bus_slot_get_destroy_callback, sd_bus_track_set_destroy_callback,
          sd_bus_track_get_destroy_callback,
          sd_event_source_set_destroy_callback,
          sd_event_source_get_destroy_callback have been added.

        * The "net.ipv4.tcp_ecn" sysctl will now be turned on by default.

        * PID 1 will now automatically reschedule .timer units whenever the
          local timezone changes. (They previously got rescheduled
          automatically when the system clock changed.)

        * New documentation has been added to document cgroups delegation,
          portable services and the various code quality tools we have set up:

          https://github.com/systemd/systemd/blob/master/doc/CGROUP_DELEGATION.md
          https://github.com/systemd/systemd/blob/master/doc/PORTABLE_SERVICES.md
          https://github.com/systemd/systemd/blob/master/doc/CODE_QUALITY.md

        * The Boot Loader Specification has been added to the source tree.

          https://github.com/systemd/systemd/blob/master/doc/BOOT_LOADER_SPECIFICATION.md

          While moving it into our source tree we have updated it and further
          changes are now accepted through the usual github PR workflow.

        * pam_elogind will now look for PAM userdata fields elogind.memory_max,
          elogind.tasks_max, elogind.cpu_weight, elogind.io_weight set by
          earlier PAM modules. The data in these fields is used to initialize
          the session scope's resource properties. Thus external PAM modules
          may now configure per-session limits, for example sourced from
          external user databases.

        * socket units with Accept=yes will now maintain a "refused" counter in
          addition to the existing "accepted" counter, counting connections
          refused due to the enforced limits.

        * The "elogind-path search-binaries-default" command may now be use to
          query the default, built-in $PATH PID 1 will pass to the services it
          manages.

        * A new unit file setting PrivateMounts= has been added. It's a boolean
          option. If enabled the unit's processes are invoked in their own file
          system namespace. Note that this behaviour is also implied if any
          other file system namespacing options (such as PrivateTmp=,
          PrivateDevices=, ProtectSystem=, …) are used. This option is hence
          primarily useful for services that do not use any of the other file
          system namespacing options. One such service is elogind-udevd.service
          wher this is now used by default.

        * ConditionSecurity= gained a new value "uefi-secureboot" that is true
          when the system is booted in UEFI "secure mode".

        * A new unit "system-update-pre.target" is added, which defines an
          optional synchronization point for offline system updates, as
          implemented by the pre-existing "system-update.target" unit. It
          allows ordering services before the service that executes the actual
          update process in a generic way.

        * Systemd now emits warnings whenever .include syntax is used.

        Contributions from: Adam Duskett, Alan Jenkins, Alessandro Casale,
        Alexander Kurtz, Alex Gartrell, Anssi Hannula, Arnaud Rebillout, Brian
        J. Murrell, Bruno Vernay, Chris Lamb, Chris Lesiak, Christian Brauner,
        Christian Hesse, Christian Rebischke, Colin Guthrie, Daniel Dao, Daniel
        Lin, Danylo Korostil, Davide Cavalca, David Tardon, Dimitri John
        Ledkov, Dmitriy Geels, Douglas Christman, Elia Geretto, emelenas, Emil
        Velikov, Evgeny Vereshchagin, Felipe Sateler, Feng Sun, Filipe
        Brandenburger, Franck Bui, futpib, Giuseppe Scrivano, Guillem Jover,
        guixxx, Hannes Reinecke, Hans de Goede, Harald Hoyer, Henrique Dante de
        Almeida, Hiram van Paassen, Ian Miell, Igor Gnatenko, Ivan Shapovalov,
        Iwan Timmer, James Cowgill, Jan Janssen, Jan Synacek, Jared Kazimir,
        Jérémy Rosen, João Paulo Rechi Vita, Joost Heitbrink, Jui-Chi Ricky
        Liang, Jürg Billeter, Kai-Heng Feng, Karol Augustin, Kay Sievers,
        Krzysztof Nowicki, Lauri Tirkkonen, Lennart Poettering, Leonard König,
        Long Li, Luca Boccassi, Lucas Werkmeister, Marcel Hoppe, Marc
        Kleine-Budde, Mario Limonciello, Martin Jansa, Martin Wilck, Mathieu
        Malaterre, Matteo F. Vescovi, Matthew McGinn, Matthias-Christian Ott,
        Michael Biebl, Michael Olbrich, Michael Prokop, Michal Koutný, Michal
        Sekletar, Mike Gilbert, Mikhail Kasimov, Milan Broz, Milan Pässler,
        Mladen Pejaković, Muhammet Kara, Nicolas Boichat, Omer Katz, Paride
        Legovini, Paul Menzel, Paul Milliken, Pavel Hrdina, Peter A. Bigot,
        Peter D'Hoye, Peter Hutterer, Peter Jones, Philip Sequeira, Philip
        Withnall, Piotr Drąg, Radostin Stoyanov, Ricardo Salveti de Araujo,
        Ronny Chevalier, Rosen Penev, Rubén Suárez Alvarez, Ryan Gonzalez,
        Salvo Tomaselli, Sebastian Reichel, Sergey Ptashnick, Sergio Lindo
        Mansilla, Stefan Schweter, Stephen Hemminger, Stuart Hayes, Susant
        Sahani, Sylvain Plantefève, Thomas H. P. Andersen, Tobias Jungel,
        Tomasz Torcz, Vito Caputo, Will Dietz, Will Thompson, Wim van Mourik,
        Yu Watanabe, Zbigniew Jędrzejewski-Szmek

        — Berlin, 2018-06-22

CHANGES WITH 238:

        * The MemoryAccounting= unit property now defaults to on. After
          discussions with the upstream control group maintainers we learnt
          that the negative impact of cgroup memory accounting on current
          kernels is finally relatively minimal, so that it should be safe to
          enable this by default without affecting system performance. Besides
          memory accounting only task accounting is turned on by default, all
          other forms of resource accounting (CPU, IO, IP) remain off for now,
          because it's not clear yet that their impact is small enough to move
          from opt-in to opt-out. We recommend downstreams to leave memory
          accounting on by default if kernel 4.14 or higher is primarily
          used. On very resource constrained systems or when support for old
          kernels is a necessity, -Dmemory-accounting-default=false can be used
          to revert this change.

        * rpm scriptlets to update the udev hwdb and rules (%udev_hwdb_update,
          %udev_rules_update) and the journal catalog (%journal_catalog_update)
          from the upgrade scriptlets of individual packages now do nothing.
          Transfiletriggers have been added which will perform those updates
          once at the end of the transaction.

          Similar transfiletriggers have been added to execute any sysctl.d
          and binfmt.d rules. Thus, it should be unnecessary to provide any
          scriptlets to execute this configuration from package installation
          scripts.

        * elogind-sysusers gained a mode where the configuration to execute is
          specified on the command line, but this configuration is not executed
          directly, but instead it is merged with the configuration on disk,
          and the result is executed. This is useful for package installation
          scripts which want to create the user before installing any files on
          disk (in case some of those files are owned by that user), while
          still allowing local admin overrides.

          This functionality is exposed to rpm scriptlets through a new
          %sysusers_create_package macro. Old %sysusers_create and
          %sysusers_create_inline macros are deprecated.

          A transfiletrigger for sysusers.d configuration is now installed,
          which means that it should be unnecessary to call elogind-sysusers from
          package installation scripts, unless the package installs any files
          owned by those newly-created users, in which case
          %sysusers_create_package should be used.

        * Analogous change has been done for elogind-tmpfiles: it gained a mode
          where the command-line configuration is merged with the configuration
          on disk. This is exposed as the new %tmpfiles_create_package macro,
          and %tmpfiles_create is deprecated. A transfiletrigger is installed
          for tmpfiles.d, hence it should be unnecessary to call elogind-tmpfiles
          from package installation scripts.

        * sysusers.d configuration for a user may now also specify the group
          number, in addition to the user number ("u username 123:456"), or
          without the user number ("u username -:456").

        * Configution items for elogind-sysusers can now be specified as
          positional arguments when the new --inline switch is used.

        * The login shell of users created through sysusers.d may now be
          specified (previously, it was always /bin/sh for root and
          /sbin/nologin for other users).

        * elogind-analyze gained a new --global switch to look at global user
          configuration. It also gained a unit-paths verb to list the unit load
          paths that are compiled into elogind (which can be used with
          --elogind, --user, or --global).

        * udevadm trigger gained a new --settle/-w option to wait for any
          triggered events to finish (but just those, and not any other events
          which are triggered meanwhile).

        * The action that elogind takes when the lid is closed and the
          machine is connected to external power can now be configured using
          HandleLidSwitchExternalPower= in logind.conf. Previously, this action
          was determined by HandleLidSwitch=, and, for backwards compatibility,
          is still is, if HandleLidSwitchExternalPower= is not explicitly set.

        * journalctl will periodically call sd_journal_process() to make it
          resilient against inotify queue overruns when journal files are
          rotated very quickly.

        * Two new functions in libelogind — sd_bus_get_n_queued_read and
          sd_bus_get_n_queued_write — may be used to check the number of
          pending bus messages.

        * elogind gained a new
          org.freedesktop.elogind1.Manager.AttachProcessesToUnit dbus call
          which can be used to migrate foreign processes to scope and service
          units. The primary user for this new API is elogind itself: the
          elogind --user instance uses this call of the elogind --system
          instance to migrate processes if it itself gets the request to
          migrate processes and the kernel refuses this due to access
          restrictions.  Thanks to this "elogind-run --scope --user …" works
          again in pure cgroups v2 environments when invoked from the user
          session scope.

        * A new TemporaryFileSystem= setting can be used to mask out part of
          the real file system tree with tmpfs mounts. This may be combined
          with BindPaths= and BindReadOnlyPaths= to hide files or directories
          not relevant to the unit, while still allowing some paths lower in
          the tree to be accessed.

          ProtectHome=tmpfs may now be used to hide user home and runtime
          directories from units, in a way that is mostly equivalent to
          "TemporaryFileSystem=/home /run/user /root".

        * Non-service units are now started with KeyringMode=shared by default.
          This means that mount and swapon and other mount tools have access
          to keys in the main keyring.

        * /sys/fs/bpf is now mounted automatically.

        * QNX virtualization is now detected by elogind-detect-virt and may
          be used in ConditionVirtualization=.

        * IPAccounting= may now be enabled also for slice units.

        * A new -Dsplit-bin= build configuration switch may be used to specify
          whether bin and sbin directories are merged, or if they should be
          included separately in $PATH and various listings of executable
          directories. The build configuration scripts will try to autodetect
          the proper values of -Dsplit-usr= and -Dsplit-bin= based on build
          system, but distributions are encouraged to configure this
          explicitly.

        * A new -Dok-color= build configuration switch may be used to change
          the colour of "OK" status messages.

        * UPGRADE ISSUE: serialization of units using JoinsNamespaceOf= with
          PrivateNetwork=yes was buggy in previous versions of elogind. This
          means that after the upgrade and daemon-reexec, any such units must
          be restarted.

        * INCOMPATIBILITY: as announced in the NEWS for 237, elogind-tmpfiles
          will not exclude read-only files owned by root from cleanup.

        Contributions from: Alan Jenkins, Alexander F Rødseth, Alexis Jeandet,
        Andika Triwidada, Andrei Gherzan, Ansgar Burchardt, antizealot1337,
        Batuhan Osman Taşkaya, Beniamino Galvani, Bill Yodlowsky, Caio Marcelo
        de Oliveira Filho, CuBiC, Daniele Medri, Daniel Mouritzen, Daniel
        Rusek, Davide Cavalca, Dimitri John Ledkov, Douglas Christman, Evgeny
        Vereshchagin, Faalagorn, Filipe Brandenburger, Franck Bui, futpib,
        Giacomo Longo, Gunnar Hjalmarsson, Hans de Goede, Hermann Gausterer,
        Iago López Galeiras, Jakub Filak, Jan Synacek, Jason A. Donenfeld,
        Javier Martinez Canillas, Jérémy Rosen, Lennart Poettering, Lucas
        Werkmeister, Mao Huang, Marco Gulino, Michael Biebl, Michael Vogt,
        MilhouseVH, Neal Gompa (ニール・ゴンパ), Oleander Reis, Olof Mogren,
        Patrick Uiterwijk, Peter Hutterer, Peter Portante, Piotr Drąg, Robert
        Antoni Buj Gelonch, Sergey Ptashnick, Shawn Landden, Shuang Liu, Simon
        Fowler, SjonHortensius, snorreflorre, Susant Sahani, Sylvain
        Plantefève, Thomas Blume, Thomas Haller, Vito Caputo, Yu Watanabe,
        Zbigniew Jędrzejewski-Szmek, Марко М. Костић (Marko M. Kostić)

        — Warsaw, 2018-03-05

CHANGES WITH 237:

        * Some keyboards come with a zoom see-saw or rocker which until now got
          mapped to the Linux "zoomin/out" keys in hwdb. However, these
          keycodes are not recognized by any major desktop. They now produce
          Up/Down key events so that they can be used for scrolling.

        * INCOMPATIBILITY: elogind-tmpfiles' "f" lines changed behaviour
          slightly: previously, if an argument was specified for lines of this
          type (i.e. the right-most column was set) this string was appended to
          existing files each time elogind-tmpfiles was run. This behaviour was
          different from what the documentation said, and not particularly
          useful, as repeated elogind-tmpfiles invocations would not be
          idempotent and grow such files without bounds. With this release
          behaviour has been altered slightly, to match what the documentation
          says: lines of this type only have an effect if the indicated files
          don't exist yet, and only then the argument string is written to the
          file.

        * FUTURE INCOMPATIBILITY: In elogind v238 we intend to slightly change
          elogind-tmpfiles behaviour: previously, read-only files owned by root
          were always excluded from the file "aging" algorithm (i.e. the
          automatic clean-up of directories like /tmp based on
          atime/mtime/ctime). We intend to drop this restriction, and age files
          by default even when owned by root and read-only. This behaviour was
          inherited from older tools, but there have been requests to remove
          it, and it's not obvious why this restriction was made in the first
          place. Please speak up now, if you are aware of software that reqires
          this behaviour, otherwise we'll remove the restriction in v238.

        * A new environment variable $SYSTEMD_OFFLINE is now understood by
          systemctl. It takes a boolean argument. If on, systemctl assumes it
          operates on an "offline" OS tree, and will not attempt to talk to the
          service manager. Previously, this mode was implicitly enabled if a
          chroot() environment was detected, and this new environment variable
          now provides explicit control.

        * .path and .socket units may now be created transiently, too.
          Previously only service, mount, automount and timer units were
          supported as transient units. The elogind-run tool has been updated
          to expose this new functionality, you may hence use it now to bind
          arbitrary commands to path or socket activation on-the-fly from the
          command line. Moreover, almost all properties are now exposed for the
          unit types that already supported transient operation.

        * The elogind-mount command gained support for a new --owner= parameter
          which takes a user name, which is then resolved and included in uid=
          and gid= mount options string of the file system to mount.

        * A new unit condition ConditionControlGroupController= has been added
          that checks whether a specific cgroup controller is available.

        * Unit files, udev's .link files, and elogind-networkd's .netdev and
          .network files all gained support for a new condition
          ConditionKernelVersion= for checking against specific kernel
          versions.

        * In elogind-networkd, the [IPVLAN] section in .netdev files gained
          support for configuring device flags in the Flags= setting. In the
          same files, the [Tunnel] section gained support for configuring
          AllowLocalRemote=.  The [Route] section in .network files gained
          support for configuring InitialCongestionWindow=,
          InitialAdvertisedReceiveWindow= and QuickAck=. The [DHCP] section now
          understands RapidCommit=.

        * elogind-networkd's DHCPv6 support gained support for Prefix
          Delegation.

        * sd-bus gained support for a new "watch-bind" feature. When this
          feature is enabled, an sd_bus connection may be set up to connect to
          an AF_UNIX socket in the file system as soon as it is created. This
          functionality is useful for writing early-boot services that
          automatically connect to the system bus as soon as it is started,
          without ugly time-based polling. elogind-networkd and
          elogind-resolved have been updated to make use of this
          functionality. busctl exposes this functionality in a new
          --watch-bind= command line switch.

        * sd-bus will now optionally synthesize a local "Connected" signal as
          soon as a D-Bus connection is set up fully. This message mirrors the
          already existing "Disconnected" signal which is synthesized when the
          connection is terminated. This signal is generally useful but
          particularly handy in combination with the "watch-bind" feature
          described above. Synthesizing of this message has to be requested
          explicitly through the new API call sd_bus_set_connected_signal(). In
          addition a new call sd_bus_is_ready() has been added that checks
          whether a connection is fully set up (i.e. between the "Connected" and
          "Disconnected" signals).

        * sd-bus gained two new calls sd_bus_request_name_async() and
          sd_bus_release_name_async() for asynchronously registering bus
          names. Similar, there is now sd_bus_add_match_async() for installing
          a signal match asynchronously. All of elogind's own services have
          been updated to make use of these calls. Doing these operations
          asynchronously has two benefits: it reduces the risk of deadlocks in
          case of cyclic dependencies between bus services, and it speeds up
          service initialization since synchronization points for bus
          round-trips are removed.

        * sd-bus gained two new calls sd_bus_match_signal() and
          sd_bus_match_signal_async(), which are similar to sd_bus_add_match()
          and sd_bus_add_match_async() but instead of taking a D-Bus match
          string take match fields as normal function parameters.

        * sd-bus gained two new calls sd_bus_set_sender() and
          sd_bus_message_set_sender() for setting the sender name of outgoing
          messages (either for all outgoing messages or for just one specific
          one). These calls are only useful in direct connections as on
          brokered connections the broker fills in the sender anyway,
          overwriting whatever the client filled in.

        * sd-event gained a new pseudo-handle that may be specified on all API
          calls where an "sd_event*" object is expected: SD_EVENT_DEFAULT. When
          used this refers to the default event loop object of the calling
          thread. Note however that this does not implicitly allocate one —
          which has to be done prior by using sd_event_default(). Similarly
          sd-bus gained three new pseudo-handles SD_BUS_DEFAULT,
          SD_BUS_DEFAULT_USER, SD_BUS_DEFAULT_SYSTEM that may be used to refer
          to the default bus of the specified type of the calling thread. Here
          too this does not implicitly allocate bus connection objects, this
          has to be done prior with sd_bus_default() and friends.

        * sd-event gained a new call pair
          sd_event_source_{get|set}_io_fd_own(). This may be used to request
          automatic closure of the file descriptor an IO event source watches
          when the event source is destroyed.

        * elogind-networkd gained support for natively configuring WireGuard
          connections.

        * In previous versions elogind synthesized user records both for the
          "nobody" (UID 65534) and "root" (UID 0) users in nss-elogind and
          internally. In order to simplify distribution-wide renames of the
          "nobody" user (like it is planned in Fedora: nfsnobody → nobody), a
          new transitional flag file has been added: if
          /etc/elogind/dont-synthesize-nobody exists synthesizing of the 65534
          user and group record within the elogind codebase is disabled.

        * elogind-notify gained a new --uid= option for selecting the source
          user/UID to use for notification messages sent to the service
          manager.

        * journalctl gained a new --grep= option to list only entries in which
          the message matches a certain pattern. By default matching is case
          insensitive if the pattern is lowercase, and case sensitive
          otherwise. Option --case-sensitive=yes|no can be used to override
          this an specify case sensitivity or case insensitivity.

        * There's now a "elogind-analyze service-watchdogs" command for printing
          the current state of the service runtime watchdog, and optionally
          enabling or disabling the per-service watchdogs system-wide if given a
          boolean argument (i.e. the concept you configure in WatchdogSec=), for
          debugging purposes. There's also a kernel command line option
          elogind.service_watchdogs= for controlling the same.

        * Two new "log-level" and "log-target" options for elogind-analyze were
          added that merge the now deprecated get-log-level, set-log-level and
          get-log-target, set-log-target pairs. The deprecated options are still
          understood for backwards compatibility. The two new options print the
          current value when no arguments are given, and set them when a
          level/target is given as an argument.

        * sysusers.d's "u" lines now optionally accept both a UID and a GID
          specification, separated by a ":" character, in order to create users
          where UID and GID do not match.

        Contributions from: Adam Duskett, Alan Jenkins, Alexander Kuleshov,
        Alexis Deruelle, Andrew Jeddeloh, Armin Widegreen, Batuhan Osman
        Taşkaya, Björn Esser, bleep_blop, Bruce A. Johnson, Chris Down, Clinton
        Roy, Colin Walters, Daniel Rusek, Dimitri John Ledkov, Dmitry Rozhkov,
        Evgeny Vereshchagin, Ewout van Mansom, Felipe Sateler, Franck Bui,
        Frantisek Sumsal, George Gaydarov, Gianluca Boiano, Hans-Christian
        Noren Egtvedt, Hans de Goede, Henrik Grindal Bakken, Jan Alexander
        Steffens, Jan Klötzke, Jason A. Donenfeld, jdkbx, Jérémy Rosen,
        Jerónimo Borque, John Lin, John Paul Herold, Jonathan Rudenberg, Jörg
        Thalheim, Ken (Bitsko) MacLeod, Larry Bernstone, Lennart Poettering,
        Lucas Werkmeister, Maciej S. Szmigiero, Marek Čermák, Martin Pitt,
        Mathieu Malaterre, Matthew Thode, Matthias-Christian Ott, Max Harmathy,
        Michael Biebl, Michael Vogt, Michal Koutný, Michal Sekletar, Michał
        Szczepański, Mike Gilbert, Nathaniel McCallum, Nicolas Chauvet, Olaf
        Hering, Olivier Schwander, Patrik Flykt, Paul Cercueil, Peter Hutterer,
        Piotr Drąg, Raphael Vogelgsang, Reverend Homer, Robert Kolchmeyer,
        Samuel Dionne-Riel, Sergey Ptashnick, Shawn Landden, Susant Sahani,
        Sylvain Plantefève, Thomas H. P. Andersen, Thomas Huth, Tomasz
        Bachorski, Vladislav Vishnyakov, Wieland Hoffmann, Yu Watanabe, Zachary
        Winnerman, Zbigniew Jędrzejewski-Szmek, Дамјан Георгиевски, Дилян
        Палаузов

        — Brno, 2018-01-28

CHANGES WITH 236:

        * The modprobe.d/ drop-in for the bonding.ko kernel module introduced
          in v235 has been extended to also set the dummy.ko module option
          numdummies=0, preventing the kernel from automatically creating
          dummy0. All dummy interfaces must now be explicitly created.

        * Unknown '%' specifiers in configuration files are now rejected. This
          applies to units and tmpfiles.d configuration. Any percent characters
          that are followed by a letter or digit that are not supposed to be
          interpreted as the beginning of a specifier should be escaped by
          doubling ("%%").  (So "size=5%" is still accepted, as well as
          "size=5%,foo=bar", but not "LABEL=x%y%z" since %y and %z are not
          valid specifiers today.)

        * systemd-resolved now maintains a new dynamic
          /run/systemd/resolve/stub-resolv.conf compatibility file. It is
          recommended to make /etc/resolv.conf a symlink to it. This file
          points at the systemd-resolved stub DNS 127.0.0.53 resolver and
          includes dynamically acquired search domains, achieving more correct
          DNS resolution by software that bypasses local DNS APIs such as NSS.

        * The "uaccess" udev tag has been dropped from /dev/kvm and
          /dev/dri/renderD*.  These devices now have the 0666 permissions by
          default (but this may be changed at build-time). /dev/dri/renderD*
          will now be owned by the "render" group along with /dev/kfd.

        * "DynamicUser=yes" has been enabled for systemd-timesyncd.service,
          systemd-journal-gatewayd.service and
          systemd-journal-upload.service. This means "nss-systemd" must be
          enabled in /etc/nsswitch.conf to ensure the UIDs assigned to these
          services are resolved properly.

        * In /etc/fstab two new mount options are now understood:
          x-systemd.makefs and x-systemd.growfs. The former has the effect that
          the configured file system is formatted before it is mounted, the
          latter that the file system is resized to the full block device size
          after it is mounted (i.e. if the file system is smaller than the
          partition it resides on, it's grown). This is similar to the fsck
          logic in /etc/fstab, and pulls in systemd-makefs@.service and
          systemd-growfs@.service as necessary, similar to
          systemd-fsck@.service. Resizing is currently only supported on ext4
          and btrfs.

        * In systemd-networkd, the IPv6 RA logic now optionally may announce
          DNS server and domain information.

        * Support for the LUKS2 on-disk format for encrypted partitions has
          been added. This requires libcryptsetup2 during compilation and
          runtime.

        * The systemd --user instance will now signal "readiness" when its
          basic.target unit has been reached, instead of when the run queue ran
          empty for the first time.

        * Tmpfiles.d with user configuration are now also supported.
          systemd-tmpfiles gained a new --user switch, and snippets placed in
          ~/.config/user-tmpfiles.d/ and corresponding directories will be
          executed by systemd-tmpfiles --user running in the new
          systemd-tmpfiles-setup.service and systemd-tmpfiles-clean.service
          running in the user session.

        * Unit files and tmpfiles.d snippets learnt three new % specifiers:
          %S resolves to the top-level state directory (/var/lib for the system
          instance, $XDG_CONFIG_HOME for the user instance), %C resolves to the
          top-level cache directory (/var/cache for the system instance,
          $XDG_CACHE_HOME for the user instance), %L resolves to the top-level
          logs directory (/var/log for the system instance,
          $XDG_CONFIG_HOME/log/ for the user instance). This matches the
          existing %t specifier, that resolves to the top-level runtime
          directory (/run for the system instance, and $XDG_RUNTIME_DIR for the
          user instance).

        * journalctl learnt a new parameter --output-fields= for limiting the
          set of journal fields to output in verbose and JSON output modes.

        * systemd-timesyncd's configuration file gained a new option
          RootDistanceMaxSec= for setting the maximum root distance of servers
          it'll use, as well as the new options PollIntervalMinSec= and
          PollIntervalMaxSec= to tweak the minimum and maximum poll interval.

        * bootctl gained a new command "list" for listing all available boot
          menu items on systems that follow the boot loader specification.

        * systemctl gained a new --dry-run switch that shows what would be done
          instead of doing it, and is currently supported by the shutdown and
          sleep verbs.

        * ConditionSecurity= can now detect the TOMOYO security module.

        * Unit file [Install] sections are now also respected in unit drop-in
          files. This is intended to be used by drop-ins under /usr/lib/.

        * systemd-firstboot may now also set the initial keyboard mapping.

        * Udev "changed" events for devices which are exposed as systemd
          .device units are now propagated to units specified in
          ReloadPropagatedFrom= as reload requests.

        * If a udev device has a SYSTEMD_WANTS= property containing a systemd
          unit template name (i.e. a name in the form of 'foobar@.service',
          without the instance component between the '@' and - the '.'), then
          the escaped sysfs path of the device is automatically used as the
          instance.

        * SystemCallFilter= in unit files has been extended so that an "errno"
          can be specified individually for each system call. Example:
          SystemCallFilter=~uname:EILSEQ.

        * The cgroup delegation logic has been substantially updated. Delegate=
          now optionally takes a list of controllers (instead of a boolean, as
          before), which lists the controllers to delegate at least.

        * The networkd DHCPv6 client now implements the FQDN option (RFC 4704).

        * A new LogLevelMax= setting configures the maximum log level any
          process of the service may log at (i.e. anything with a lesser
          priority than what is specified is automatically dropped). A new
          LogExtraFields= setting allows configuration of additional journal
          fields to attach to all log records generated by any of the unit's
          processes.

        * New StandardInputData= and StandardInputText= settings along with the
          new option StandardInput=data may be used to configure textual or
          binary data that shall be passed to the executed service process via
          standard input, encoded in-line in the unit file.

        * StandardInput=, StandardOutput= and StandardError= may now be used to
          connect stdin/stdout/stderr of executed processes directly with a
          file or AF_UNIX socket in the file system, using the new "file:" option.

        * A new unit file option CollectMode= has been added, that allows
          tweaking the garbage collection logic for units. It may be used to
          tell systemd to garbage collect units that have failed automatically
          (normally it only GCs units that exited successfully). systemd-run
          and systemd-mount expose this new functionality with a new -G option.

        * "machinectl bind" may now be used to bind mount non-directories
          (i.e. regularfiles, devices, fifos, sockets).

        * systemd-analyze gained a new verb "calendar" for validating and
          testing calendar time specifications to use for OnCalendar= in timer
          units. Besides validating the expression it will calculate the next
          time the specified expression would elapse.

        * In addition to the pre-existing FailureAction= unit file setting
          there's now SuccessAction=, for configuring a shutdown action to
          execute when a unit completes successfully. This is useful in
          particular inside containers that shall terminate after some workload
          has been completed. Also, both options are now supported for all unit
          types, not just services.

        * networkds's IP rule support gained two new options
          IncomingInterface= and OutgoingInterface= for configuring the incoming
          and outgoing interfaces of configured rules. systemd-networkd also
          gained support for "vxcan" network devices.

        * networkd gained a new setting RequiredForOnline=, taking a
          boolean. If set, systemd-wait-online will take it into consideration
          when determining that the system is up, otherwise it will ignore the
          interface for this purpose.

        * The sd_notify() protocol gained support for a new operation: with
          FDSTOREREMOVE=1 file descriptors may be removed from the per-service
          store again, ahead of POLLHUP or POLLERR when they are removed
          anyway.

        * A new document doc/UIDS-GIDS.md has been added to the source tree,
          that documents the UID/GID range and assignment assumptions and
          requirements of systemd.

        * The watchdog device PID 1 will ping may now be configured through the
          WatchdogDevice= configuration file setting, or by setting the
          systemd.watchdog_service= kernel commandline option.

        * systemd-resolved's gained support for registering DNS-SD services on
          the local network using MulticastDNS. Services may either be
          registered by dropping in a .dnssd file in /etc/systemd/dnssd/ (or
          the same dir below /run, /usr/lib), or through its D-Bus API.

        * The sd_notify() protocol can now with EXTEND_TIMEOUT_USEC=microsecond
          extend the effective start, runtime, and stop time. The service must
          continue to send EXTEND_TIMEOUT_USEC within the period specified to
          prevent the service manager from making the service as timedout.

        * elogind-resolved's DNSSEC support gained support for RFC 8080
          (Ed25519 keys and signatures).

        * The elogind-resolve command line tool gained a new set of options
          --set-dns=, --set-domain=, --set-llmnr=, --set-mdns=, --set-dnssec=,
          --set-nta= and --revert to configure per-interface DNS configuration
          dynamically during runtime. It's useful for pushing DNS information
          into elogind-resolved from DNS hook scripts that various interface
          managing software supports (such as pppd).

        * elogind-nspawn gained a new --network-namespace-path= command line
          option, which may be used to make a container join an existing
          network namespace, by specifying a path to a "netns" file.

        Contributions from: Alan Jenkins, Alan Robertson, Alessandro Ghedini,
        Andrew Jeddeloh, Antonio Rojas, Ari, asavah, bleep_blop, Carsten
        Strotmann, Christian Brauner, Christian Hesse, Clinton Roy, Collin
        Eggert, Cong Wang, Daniel Black, Daniel Lockyer, Daniel Rusek, Dimitri
        John Ledkov, Dmitry Rozhkov, Dongsu Park, Edward A. James, Evgeny
        Vereshchagin, Florian Klink, Franck Bui, Gwendal Grignou, Hans de
        Goede, Harald Hoyer, Hristo Venev, Iago López Galeiras, Ikey Doherty,
        Jakub Wilk, Jérémy Rosen, Jiahui Xie, John Lin, José Bollo, Josef
        Andersson, juga0, Krzysztof Nowicki, Kyle Walker, Lars Karlitski, Lars
        Kellogg-Stedman, Lauri Tirkkonen, Lennart Poettering, Lubomir Rintel,
        Luca Bruno, Lucas Werkmeister, Lukáš Nykrýn, Lukáš Říha, Lukasz
        Rubaszewski, Maciej S. Szmigiero, Mantas Mikulėnas, Marcus Folkesson,
        Martin Steuer, Mathieu Trudel-Lapierre, Matija Skala,
        Matthias-Christian Ott, Max Resch, Michael Biebl, Michael Vogt, Michal
        Koutný, Michal Sekletar, Mike Gilbert, Muhammet Kara, Neil Brown, Olaf
        Hering, Ondrej Kozina, Patrik Flykt, Patryk Kocielnik, Peter Hutterer,
        Piotr Drąg, Razvan Cojocaru, Robin McCorkell, Roland Hieber, Saran
        Tunyasuvunakool, Sergey Ptashnick, Shawn Landden, Shuang Liu, Simon
        Arlott, Simon Peeters, Stanislav Angelovič, Stefan Agner, Susant
        Sahani, Sylvain Plantefève, Thomas Blume, Thomas Haller, Tiago Salem
        Herrmann, Tinu Weber, Tom Stellard, Topi Miettinen, Torsten Hilbrich,
        Vito Caputo, Vladislav Vishnyakov, WaLyong Cho, Yu Watanabe, Zbigniew
        Jędrzejewski-Szmek, Zeal Jagannatha

        — Berlin, 2017-12-14

CHANGES WITH 235:

        * INCOMPATIBILITY: systemd-logind.service and other long-running
          services now run inside an IPv4/IPv6 sandbox, prohibiting them any IP
          communication with the outside. This generally improves security of
          the system, and is in almost all cases a safe and good choice, as
          these services do not and should not provide any network-facing
          functionality. However, systemd-logind uses the glibc NSS API to
          query the user database. This creates problems on systems where NSS
          is set up to directly consult network services for user database
          lookups. In particular, this creates incompatibilities with the
          "nss-nis" module, which attempts to directly contact the NIS/YP
          network servers it is configured for, and will now consistently
          fail. In such cases, it is possible to turn off IP sandboxing for
          systemd-logind.service (set IPAddressDeny= in its [Service] section
          to the empty string, via a .d/ unit file drop-in). Downstream
          distributions might want to update their nss-nis packaging to include
          such a drop-in snippet, accordingly, to hide this incompatibility
          from the user. Another option is to make use of glibc's nscd service
          to proxy such network requests through a privilege-separated, minimal
          local caching daemon, or to switch to more modern technologies such
          sssd, whose NSS hook-ups generally do not involve direct network
          access. In general, we think it's definitely time to question the
          implementation choices of nss-nis, i.e. whether it's a good idea
          today to embed a network-facing loadable module into all local
          processes that need to query the user database, including the most
          trivial and benign ones, such as "ls". For more details about
          IPAddressDeny= see below.

        * A new modprobe.d drop-in is now shipped by default that sets the
          bonding module option max_bonds=0. This overrides the kernel default,
          to avoid conflicts and ambiguity as to whether or not bond0 should be
          managed by systemd-networkd or not. This resolves multiple issues
          with bond0 properties not being applied, when bond0 is configured
          with systemd-networkd. Distributors may choose to not package this,
          however in that case users will be prevented from correctly managing
          bond0 interface using systemd-networkd.

        * systemd-analyze gained new verbs "get-log-level" and "get-log-target"
          which print the logging level and target of the system manager. They
          complement the existing "set-log-level" and "set-log-target" verbs
          used to change those values.

        * journald.conf gained a new boolean setting ReadKMsg= which defaults
          to on. If turned off kernel log messages will not be read by
          systemd-journald or included in the logs. It also gained a new
          setting LineMax= for configuring the maximum line length in
          STDOUT/STDERR log streams. The new default for this value is 48K, up
          from the previous hardcoded 2048.

        * A new unit setting RuntimeDirectoryPreserve= has been added, which
          allows more detailed control of what to do with a runtime directory
          configured with RuntimeDirectory= (i.e. a directory below /run or
          $XDG_RUNTIME_DIR) after a unit is stopped.

        * The RuntimeDirectory= setting for units gained support for creating
          deeper subdirectories below /run or $XDG_RUNTIME_DIR, instead of just
          one top-level directory.

        * Units gained new options StateDirectory=, CacheDirectory=,
          LogsDirectory= and ConfigurationDirectory= which are closely related
          to RuntimeDirectory= but manage per-service directories below
          /var/lib, /var/cache, /var/log and /etc. By making use of them it is
          possible to write unit files which when activated automatically gain
          properly owned service specific directories in these locations, thus
          making unit files self-contained and increasing compatibility with
          stateless systems and factory reset where /etc or /var are
          unpopulated at boot. Matching these new settings there's also
          StateDirectoryMode=, CacheDirectoryMode=, LogsDirectoryMode=,
          ConfigurationDirectoryMode= for configuring the access mode of these
          directories. These settings are particularly useful in combination
          with DynamicUser=yes as they provide secure, properly-owned,
          writable, and stateful locations for storage, excluded from the
          sandbox that such services live in otherwise.

        * Automake support has been removed from this release. systemd is now
          Meson-only.

        * systemd-journald will now aggressively cache client metadata during
          runtime, speeding up log write performance under pressure. This comes
          at a small price though: as much of the metadata is read
          asynchronously from /proc/ (and isn't implicitly attached to log
          datagrams by the kernel, like UID/GID/PID/SELinux are) this means the
          metadata stored alongside a log entry might be slightly
          out-of-date. Previously it could only be slightly newer than the log
          message. The time window is small however, and given that the kernel
          is unlikely to be improved anytime soon in this regard, this appears
          acceptable to us.

        * nss-myhostname/systemd-resolved will now by default synthesize an
          A/AAAA resource record for the "_gateway" hostname, pointing to the
          current default IP gateway. Previously it did that for the "gateway"
          name, hampering adoption, as some distributions wanted to leave that
          host name open for local use. The old behaviour may still be
          requested at build time.

        * systemd-networkd's [Address] section in .network files gained a new
          Scope= setting for configuring the IP address scope. The [Network]
          section gained a new boolean setting ConfigureWithoutCarrier= that
          tells systemd-networkd to ignore link sensing when configuring the
          device. The [DHCP] section gained a new Anonymize= boolean option for
          turning on a number of options suggested in RFC 7844. A new
          [RoutingPolicyRule] section has been added for configuring the IP
          routing policy. The [Route] section has gained support for a new
          Type= setting which permits configuring
          blackhole/unreachable/prohibit routes.

        * The [VRF] section in .netdev files gained a new Table= setting for
          configuring the routing table to use. The [Tunnel] section gained a
          new Independent= boolean field for configuring tunnels independent of
          an underlying network interface. The [Bridge] section gained a new
          GroupForwardMask= option for configuration of propagation of link
          local frames between bridge ports.

        * The WakeOnLan= setting in .link files gained support for a number of
          new modes. A new TCP6SegmentationOffload= setting has been added for
          configuring TCP/IPv6 hardware segmentation offload.

        * The IPv6 RA sender implementation may now optionally send out RDNSS
          and RDNSSL records to supply DNS configuration to peers.

        * systemd-nspawn gained support for a new --system-call-filter= command
          line option for adding and removing entries in the default system
          call filter it applies. Moreover systemd-nspawn has been changed to
          implement a system call whitelist instead of a blacklist.

        * systemd-run gained support for a new --pipe command line option. If
          used the STDIN/STDOUT/STDERR file descriptors passed to systemd-run
          are directly passed on to the activated transient service
          executable. This allows invoking arbitrary processes as systemd
          services (for example to take benefit of dependency management,
          accounting management, resource management or log management that is
          done automatically for services) — while still allowing them to be
          integrated in a classic UNIX shell pipeline.

        * When a service sends RELOAD=1 via sd_notify() and reload propagation
          using ReloadPropagationTo= is configured, a reload is now propagated
          to configured units. (Previously this was only done on explicitly
          requested reloads, using "systemctl reload" or an equivalent
          command.)

        * For each service unit a restart counter is now kept: it is increased
          each time the service is restarted due to Restart=, and may be
          queried using "systemctl show -p NRestarts …".

        * New system call filter groups @aio, @sync, @chown, @setuid, @memlock,
          @signal and @timer have been added, for usage with SystemCallFilter=
          in unit files and the new --system-call-filter= command line option
          of systemd-nspawn (see above).

        * ExecStart= lines in unit files gained two new modifiers: when a
          command line is prefixed with "!" the command will be executed as
          configured, except for the credentials applied by
          setuid()/setgid()/setgroups(). It is very similar to the pre-existing
          "+", but does still apply namespacing options unlike "+". There's
          also "!!" now, which is mostly identical, but becomes a NOP on
          systems that support ambient capabilities. This is useful to write
          unit files that work with ambient capabilities where possible but
          automatically fall back to traditional privilege dropping mechanisms
          on systems where this is not supported.

        * ListenNetlink= settings in socket units now support RDMA netlink
          sockets.

        * A new unit file setting LockPersonality= has been added which permits
          locking down the chosen execution domain ("personality") of a service
          during runtime.

        * A new special target "getty-pre.target" has been added, which is
          ordered before all text logins, and may be used to order services
          before textual logins acquire access to the console.

        * systemd will now attempt to load the virtio-rng.ko kernel module very
          early on if a VM environment supporting this is detected. This should
          improve entropy during early boot in virtualized environments.

        * A _netdev option is now supported in /etc/crypttab that operates in a
          similar way as the same option in /etc/fstab: it permits configuring
          encrypted devices that need to be ordered after the network is up.
          Following this logic, two new special targets
          remote-cryptsetup-pre.target and remote-cryptsetup.target have been
          added that are to cryptsetup.target what remote-fs.target and
          remote-fs-pre.target are to local-fs.target.

        * Service units gained a new UnsetEnvironment= setting which permits
          unsetting specific environment variables for services that are
          normally passed to it (for example in order to mask out locale
          settings for specific services that can't deal with it).

        * Units acquired a new boolean option IPAccounting=. When turned on, IP
          traffic accounting (packet count as well as byte count) is done for
          the service, and shown as part of "systemctl status" or "systemd-run
          --wait".

        * Service units acquired two new options IPAddressAllow= and
          IPAddressDeny=, taking a list of IPv4 or IPv6 addresses and masks,
          for configuring a simple IP access control list for all sockets of
          the unit. These options are available also on .slice and .socket
          units, permitting flexible access list configuration for individual
          services as well as groups of services (as defined by a slice unit),
          including system-wide. Note that IP ACLs configured this way are
          enforced on every single IPv4 and IPv6 socket created by any process
          of the service unit, and apply to ingress as well as egress traffic.

        * If CPUAccounting= or IPAccounting= is turned on for a unit a new
          structured log message is generated each time the unit is stopped,
          containing information about the consumed resources of this
          invocation.

        * A new setting KeyringMode= has been added to unit files, which may be
          used to control how the kernel keyring is set up for executed
          processes.

        * "systemctl poweroff", "systemctl reboot", "systemctl halt",
          "systemctl kexec" and "systemctl exit" are now always asynchronous in
          behaviour (that is: these commands return immediately after the
          operation was enqueued instead of waiting for the operation to
          complete). Previously, "systemctl poweroff" and "systemctl reboot"
          were asynchronous on systems using systemd-logind (i.e. almost
          always, and like they were on sysvinit), and the other three commands
          were unconditionally synchronous. With this release this is cleaned
          up, and callers will see the same asynchronous behaviour on all
          systems for all five operations.

        * systemd-logind gained new Halt() and CanHalt() bus calls for halting
          the system.

        * .timer units now accept calendar specifications in other timezones
          than UTC or the local timezone.

        * The tmpfiles snippet var.conf has been changed to create
          /var/log/btmp with access mode 0660 instead of 0600. It was owned by
          the "utmp" group already, and it appears to be generally understood
          that members of "utmp" can modify/flush the utmp/wtmp/lastlog/btmp
          databases. Previously this was implemented correctly for all these
          databases excepts btmp, which has been opened up like this now
          too. Note that while the other databases are world-readable
          (i.e. 0644), btmp is not and remains more restrictive.

        * The systemd-resolve tool gained a new --reset-server-features
          switch. When invoked like this systemd-resolved will forget
          everything it learnt about the features supported by the configured
          upstream DNS servers, and restarts the feature probing logic on the
          next resolver look-up for them at the highest feature level
          again.

        * The status dump systemd-resolved sends to the logs upon receiving
          SIGUSR1 now also includes information about all DNS servers it is
          configured to use, and the features levels it probed for them.

        Contributions from: Abdó Roig-Maranges, Alan Jenkins, Alexander
        Kuleshov, Andreas Rammhold, Andrew Jeddeloh, Andrew Soutar, Ansgar
        Burchardt, Beniamino Galvani, Benjamin Berg, Benjamin Robin, Charles
        Huber, Christian Hesse, Daniel Berrange, Daniel Kahn Gillmor, Daniel
        Mack, Daniel Rusek, Daniel Șerbănescu, Davide Cavalca, Dimitri John
        Ledkov, Diogo Pereira, Djalal Harouni, Dmitriy Geels, Dmitry Torokhov,
        ettavolt, Evgeny Vereshchagin, Fabio Kung, Felipe Sateler, Franck Bui,
        Hans de Goede, Harald Hoyer, Insun Pyo, Ivan Kurnosov, Ivan Shapovalov,
        Jakub Wilk, Jan Synacek, Jason Gunthorpe, Jeremy Bicha, Jérémy Rosen,
        John Lin, jonasBoss, Jonathan Lebon, Jonathan Teh, Jon Ringle, Jörg
        Thalheim, Jouke Witteveen, juga0, Justin Capella, Justin Michaud,
        Kai-Heng Feng, Lennart Poettering, Lion Yang, Luca Bruno, Lucas
        Werkmeister, Lukáš Nykrýn, Marcel Hollerbach, Marcus Lundblad, Martin
        Pitt, Michael Biebl, Michael Grzeschik, Michal Sekletar, Mike Gilbert,
        Neil Brown, Nicolas Iooss, Patrik Flykt, pEJipE, Piotr Drąg, Russell
        Stuart, S. Fan, Shengyao Xue, Stefan Pietsch, Susant Sahani, Tejun Heo,
        Thomas Miller, Thomas Sailer, Tobias Hunger, Tomasz Pala, Tom
        Gundersen, Tommi Rantala, Topi Miettinen, Torstein Husebø, userwithuid,
        Vasilis Liaskovitis, Vito Caputo, WaLyong Cho, William Douglas, Xiang
        Fan, Yu Watanabe, Zbigniew Jędrzejewski-Szmek

        — Berlin, 2017-10-06

CHANGES WITH 234:

        * Meson is now supported as build system in addition to Automake. It is
          our plan to remove Automake in one of our next releases, so that
          Meson becomes our exclusive build system. Hence, please start using
          the Meson build system in your downstream packaging. There's plenty
          of documentation around how to use Meson, the extremely brief
          summary:

              ./autogen.sh && ./configure && make && sudo make install

          becomes:

              meson build && ninja -C build && sudo ninja -C build install

        * Unit files gained support for a new JobRunningTimeoutUSec= setting,
          which permits configuring a timeout on the time a job is
          running. This is particularly useful for setting timeouts on jobs for
          .device units.

        * Unit files gained two new options ConditionUser= and ConditionGroup=
          for conditionalizing units based on the identity of the user/group
          running a systemd user instance.

        * systemd-networkd now understands a new FlowLabel= setting in the
          [VXLAN] section of .network files, as well as a Priority= in
          [Bridge], GVRP= + MVRP= + LooseBinding= + ReorderHeader= in [VLAN]
          and GatewayOnlink= + IPv6Preference= + Protocol= in [Route]. It also
          gained support for configuration of GENEVE links, and IPv6 address
          labels. The [Network] section gained the new IPv6ProxyNDP= setting.

        * .link files now understand a new Port= setting.

        * systemd-networkd's DHCP support gained support for DHCP option 119
          (domain search list).

        * systemd-networkd gained support for serving IPv6 address ranges using
          the Router Advertisement protocol. The new .network configuration
          section [IPv6Prefix] may be used to configure the ranges to
          serve. This is implemented based on a new, minimal, native server
          implementation of RA.

        * journalctl's --output= switch gained support for a new parameter
          "short-iso-precise" for a mode where timestamps are shown as precise
          ISO date values.

        * systemd-udevd's "net_id" builtin may now generate stable network
          interface names from IBM PowerVM VIO devices as well as ACPI platform
          devices.

        * MulticastDNS support in systemd-resolved may now be explicitly
          enabled/disabled using the new MulticastDNS= configuration file
          option.

        * systemd-resolved may now optionally use libidn2 instead of the libidn
          for processing internationalized domain names. Support for libidn2
          should be considered experimental and should not be enabled by
          default yet.

        * "machinectl pull-tar" and related call may now do verification of
          downloaded images using SUSE-style .sha256 checksum files in addition
          to the already existing support for validating using Ubuntu-style
          SHA256SUMS files.

        * sd-bus gained support for a new sd_bus_message_appendv() call which
          is va_list equivalent of sd_bus_message_append().

        * sd-boot gained support for validating images using SHIM/MOK.

        * The SMACK code learnt support for "onlycap".

        * systemd-mount --umount is now much smarter in figuring out how to
          properly unmount a device given its mount or device path.

        * The code to call libnss_dns as a fallback from libnss_resolve when
          the communication with systemd-resolved fails was removed. This
          fallback was redundant and interfered with the [!UNAVAIL=return]
          suffix. See nss-resolve(8) for the recommended configuration.

        * systemd-logind may now be restarted without losing state. It stores
          the file descriptors for devices it manages in the system manager
          using the FDSTORE= mechanism. Please note that further changes in
          other components may be required to make use of this (for example
          Xorg has code to listen for stops of systemd-logind and terminate
          itself when logind is stopped or restarted, in order to avoid using
          stale file descriptors for graphical devices, which is now
          counterproductive and must be reverted in order for restarts of
          systemd-logind to be safe. See
          https://cgit.freedesktop.org/xorg/xserver/commit/?id=dc48bd653c7e101.)

        * All kernel install plugins are called with the environment variable
          KERNEL_INSTALL_MACHINE_ID which is set to the machine ID given by
          /etc/machine-id. If the file is missing or empty, the variable is
          empty and BOOT_DIR_ABS is the path of a temporary directory which is
          removed after all the plugins exit. So, if KERNEL_INSTALL_MACHINE_ID
          is empty, all plugins should not put anything in BOOT_DIR_ABS.

        Contributions from: Adrian Heine né Lang, Aggelos Avgerinos, Alexander
        Kurtz, Alexandros Frantzis, Alexey Brodkin, Alex Lu, Amir Pakdel, Amir
        Yalon, Anchor Cat, Anthony Parsons, Bastien Nocera, Benjamin Gilbert,
        Benjamin Robin, Boucman, Charles Plessy, Chris Chiu, Chris Lamb,
        Christian Brauner, Christian Hesse, Colin Walters, Daniel Drake,
        Danielle Church, Daniel Molkentin, Daniel Rusek, Daniel Wang, Davide
        Cavalca, David Herrmann, David Michael, Dax Kelson, Dimitri John
        Ledkov, Djalal Harouni, Dušan Kazik, Elias Probst, Evgeny Vereshchagin,
        Federico Di Pierro, Felipe Sateler, Felix Zhang, Franck Bui, Gary
        Tierney, George McCollister, Giedrius Statkevičius, Hans de Goede,
        hecke, Hendrik Westerberg, Hristo Venev, Ian Wienand, Insun Pyo, Ivan
        Shapovalov, James Cowgill, James Hemsing, Janne Heß, Jan Synacek, Jason
        Reeder, João Paulo Rechi Vita, John Paul Adrian Glaubitz, Jörg
        Thalheim, Josef Andersson, Josef Gajdusek, Julian Mehne, Kai Krakow,
        Krzysztof Jackiewicz, Lars Karlitski, Lennart Poettering, Lluís Gili,
        Lucas Werkmeister, Lukáš Nykrýn, Łukasz Stelmach, Mantas Mikulėnas,
        Marcin Bachry, Marcus Cooper, Mark Stosberg, Martin Pitt, Matija Skala,
        Matt Clarkson, Matthew Garrett, Matthias Greiner, Matthijs van Duin,
        Max Resch, Michael Biebl, Michal Koutný, Michal Sekletar, Michal
        Soltys, Michal Suchanek, Mike Gilbert, Nate Clark, Nathaniel R. Lewis,
        Neil Brown, Nikolai Kondrashov, Pascal S. de Kloe, Pat Riehecky, Patrik
        Flykt, Paul Kocialkowski, Peter Hutterer, Philip Withnall, Piotr
        Szydełko, Rafael Fontenelle, Ray Strode, Richard Maw, Roelf Wichertjes,
        Ronny Chevalier, Sarang S. Dalal, Sjoerd Simons, slodki, Stefan
        Schweter, Susant Sahani, Ted Wood, Thomas Blume, Thomas Haller, Thomas
        H. P. Andersen, Timothée Ravier, Tobias Jungel, Tobias Stoeckmann, Tom
        Gundersen, Tom Yan, Torstein Husebø, Umut Tezduyar Lindskog,
        userwithuid, Vito Caputo, Waldemar Brodkorb, WaLyong Cho, Yu, Li-Yu,
        Yusuke Nojima, Yu Watanabe, Zbigniew Jędrzejewski-Szmek, Дамјан
        Георгиевски

        — Berlin, 2017-07-12

CHANGES WITH 233:

        * The "hybrid" control group mode has been modified to improve
          compatibility with "legacy" cgroups-v1 setups. Specifically, the
          "hybrid" setup of /sys/fs/cgroup is now pretty much identical to
          "legacy" (including /sys/fs/cgroup/systemd as "name=systemd" named
          cgroups-v1 hierarchy), the only externally visible change being that
          the cgroups-v2 hierarchy is also mounted, to
          /sys/fs/cgroup/unified. This should provide a large degree of
          compatibility with "legacy" cgroups-v1, while taking benefit of the
          better management capabilities of cgroups-v2.

        * The default control group setup mode may be selected both a boot-time
          via a set of kernel command line parameters (specifically:
          systemd.unified_cgroup_hierarchy= and
          systemd.legacy_systemd_cgroup_controller=), as well as a compile-time
          default selected on the configure command line
          (--with-default-hierarchy=). The upstream default is "hybrid"
          (i.e. the cgroups-v1 + cgroups-v2 mixture discussed above) now, but
          this will change in a future systemd version to be "unified" (pure
          cgroups-v2 mode). The third option for the compile time option is
          "legacy", to enter pure cgroups-v1 mode. We recommend downstream
          distributions to default to "hybrid" mode for release distributions,
          starting with v233. We recommend "unified" for development
          distributions (specifically: distributions such as Fedora's rawhide)
          as that's where things are headed in the long run. Use "legacy" for
          greatest stability and compatibility only.

        * Note one current limitation of "unified" and "hybrid" control group
          setup modes: the kernel currently does not permit the systemd --user
          instance (i.e. unprivileged code) to migrate processes between two
          disconnected cgroup subtrees, even if both are managed and owned by
          the user. This effectively means "systemd-run --user --scope" doesn't
          work when invoked from outside of any "systemd --user" service or
          scope. Specifically, it is not supported from session scopes. We are
          working on fixing this in a future systemd version. (See #3388 for
          further details about this.)

        * DBus policy files are now installed into /usr rather than /etc. Make
          sure your system has dbus >= 1.9.18 running before upgrading to this
          version, or override the install path with --with-dbuspolicydir= .

        * All python scripts shipped with systemd (specifically: the various
          tests written in Python) now require Python 3.

        * systemd unit tests can now run standalone (without the source or
          build directories), and can be installed into /usr/lib/systemd/tests/
          with 'make install-tests'.

        * Note that from this version on, CONFIG_CRYPTO_USER_API_HASH,
          CONFIG_CRYPTO_HMAC and CONFIG_CRYPTO_SHA256 need to be enabled in the
          kernel.

        * Support for the %c, %r, %R specifiers in unit files has been
          removed. Specifiers are not supposed to be dependent on configuration
          in the unit file itself (so that they resolve the same regardless
          where used in the unit files), but these specifiers were influenced
          by the Slice= option.

        * The shell invoked by debug-shell.service now defaults to /bin/sh in
          all cases. If distributions want to use a different shell for this
          purpose (for example Fedora's /sbin/sushell) they need to specify
          this explicitly at configure time using --with-debug-shell=.

        * The confirmation spawn prompt has been reworked to offer the
          following choices:

           (c)ontinue, proceed without asking anymore
           (D)ump, show the state of the unit
           (f)ail, don't execute the command and pretend it failed
           (h)elp
           (i)nfo, show a short summary of the unit
           (j)obs, show jobs that are in progress
           (s)kip, don't execute the command and pretend it succeeded
           (y)es, execute the command

          The 'n' choice for the confirmation spawn prompt has been removed,
          because its meaning was confusing.

          The prompt may now also be redirected to an alternative console by
          specifying the console as parameter to systemd.confirm_spawn=.

        * Services of Type=notify require a READY=1 notification to be sent
          during startup. If no such message is sent, the service now fails,
          even if the main process exited with a successful exit code.

        * Services that fail to start up correctly now always have their
          ExecStopPost= commands executed. Previously, they'd enter "failed"
          state directly, without executing these commands.

        * The option MulticastDNS= of network configuration files has acquired
          an actual implementation. With MulticastDNS=yes a host can resolve
          names of remote hosts and reply to mDNS A and AAAA requests.

        * When units are about to be started an additional check is now done to
          ensure that all dependencies of type BindsTo= (when used in
          combination with After=) have been started.

        * systemd-analyze gained a new verb "syscall-filter" which shows which
          system call groups are defined for the SystemCallFilter= unit file
          setting, and which system calls they contain.

        * A new system call filter group "@filesystem" has been added,
          consisting of various file system related system calls. Group
          "@reboot" has been added, covering reboot, kexec and shutdown related
          calls. Finally, group "@swap" has been added covering swap
          configuration related calls.

        * A new unit file option RestrictNamespaces= has been added that may be
          used to restrict access to the various process namespace types the
          Linux kernel provides. Specifically, it may be used to take away the
          right for a service unit to create additional file system, network,
          user, and other namespaces. This sandboxing option is particularly
          relevant due to the high amount of recently discovered namespacing
          related vulnerabilities in the kernel.

        * systemd-udev's .link files gained support for a new AutoNegotiation=
          setting for configuring Ethernet auto-negotiation.

        * systemd-networkd's .network files gained support for a new
          ListenPort= setting in the [DHCP] section to explicitly configure the
          UDP client port the DHCP client shall listen on.

        * .network files gained a new Unmanaged= boolean setting for explicitly
          excluding one or more interfaces from management by systemd-networkd.

        * The systemd-networkd ProxyARP= option has been renamed to
          IPV4ProxyARP=. Similarly, VXLAN-specific option ARPProxy= has been
          renamed to ReduceARPProxy=. The old names continue to be available
          for compatibility.

        * systemd-networkd gained support for configuring IPv6 Proxy NDP
          addresses via the new IPv6ProxyNDPAddress= .network file setting.

        * systemd-networkd's bonding device support gained support for two new
          configuration options ActiveSlave= and PrimarySlave=.

        * The various options in the [Match] section of .network files gained
          support for negative matching.

        * New systemd-specific mount options are now understood in /etc/fstab:

          x-systemd.mount-timeout= may be used to configure the maximum
          permitted runtime of the mount command.

          x-systemd.device-bound may be set to bind a mount point to its
          backing device unit, in order to automatically remove a mount point
          if its backing device is unplugged. This option may also be
          configured through the new SYSTEMD_MOUNT_DEVICE_BOUND udev property
          on the block device, which is now automatically set for all CDROM
          drives, so that mounted CDs are automatically unmounted when they are
          removed from the drive.

          x-systemd.after= and x-systemd.before= may be used to explicitly
          order a mount after or before another unit or mount point.

        * Enqueued start jobs for device units are now automatically garbage
          collected if there are no jobs waiting for them anymore.

        * systemctl list-jobs gained two new switches: with --after, for every
          queued job the jobs it's waiting for are shown; with --before the
          jobs which it's blocking are shown.

        * systemd-nspawn gained support for ephemeral boots from disk images
          (or in other words: --ephemeral and --image= may now be
          combined). Moreover, ephemeral boots are now supported for normal
          directories, even if the backing file system is not btrfs. Of course,
          if the file system does not support file system snapshots or
          reflinks, the initial copy operation will be relatively expensive, but
          this should still be suitable for many use cases.

        * Calendar time specifications in .timer units now support
          specifications relative to the end of a month by using "~" instead of
          "-" as separator between month and day. For example, "*-02~03" means
          "the third last day in February". In addition a new syntax for
          repeated events has been added using the "/" character. For example,
          "9..17/2:00" means "every two hours from 9am to 5pm".

        * systemd-socket-proxyd gained a new parameter --connections-max= for
          configuring the maximum number of concurrent connections.

        * sd-id128 gained a new API for generating unique IDs for the host in a
          way that does not leak the machine ID. Specifically,
          sd_id128_get_machine_app_specific() derives an ID based on the
          machine ID a in well-defined, non-reversible, stable way. This is
          useful whenever an identifier for the host is needed but where the
          identifier shall not be useful to identify the system beyond the
          scope of the application itself. (Internally this uses HMAC-SHA256 as
          keyed hash function using the machine ID as input.)

        * NotifyAccess= gained a new supported value "exec". When set
          notifications are accepted from all processes systemd itself invoked,
          including all control processes.

        * .nspawn files gained support for defining overlay mounts using the
          Overlay= and OverlayReadOnly= options. Previously this functionality
          was only available on the systemd-nspawn command line.

        * systemd-nspawn's --bind= and --overlay= options gained support for
          bind/overlay mounts whose source lies within the container tree by
          prefixing the source path with "+".

        * systemd-nspawn's --bind= and --overlay= options gained support for
          automatically allocating a temporary source directory in /var/tmp
          that is removed when the container dies. Specifically, if the source
          directory is specified as empty string this mechanism is selected. An
          example usage is --overlay=+/var::/var, which creates an overlay
          mount based on the original /var contained in the image, overlayed
          with a temporary directory in the host's /var/tmp. This way changes
          to /var are automatically flushed when the container shuts down.

        * systemd-nspawn --image= option does now permit raw file system block
          devices (in addition to images containing partition tables, as
          before).

        * The disk image dissection logic in systemd-nspawn gained support for
          automatically setting up LUKS encrypted as well as Verity protected
          partitions. When a container is booted from an encrypted image the
          passphrase is queried at start-up time. When a container with Verity
          data is started, the root hash is search in a ".roothash" file
          accompanying the disk image (alternatively, pass the root hash via
          the new --root-hash= command line option).

        * A new tool /usr/lib/systemd/systemd-dissect has been added that may
          be used to dissect disk images the same way as systemd-nspawn does
          it, following the Bootable Partition Specification. It may even be
          used to mount disk images with complex partition setups (including
          LUKS and Verity partitions) to a local host directory, in order to
          inspect them. This tool is not considered public API (yet), and is
          thus not installed into /usr/bin. Please do not rely on its
          existence, since it might go away or be changed in later systemd
          versions.

        * A new generator "systemd-verity-generator" has been added, similar in
          style to "systemd-cryptsetup-generator", permitting automatic setup of
          Verity root partitions when systemd boots up. In order to make use of
          this your partition setup should follow the Discoverable Partitions
          Specification, and the GPT partition ID of the root file system
          partition should be identical to the upper 128bit of the Verity root
          hash. The GPT partition ID of the Verity partition protecting it
          should be the lower 128bit of the Verity root hash. If the partition
          image follows this model it is sufficient to specify a single
          "roothash=" kernel command line argument to both configure which root
          image and verity partition to use as well as the root hash for
          it. Note that systemd-nspawn's Verity support follows the same
          semantics, meaning that disk images with proper Verity data in place
          may be booted in containers with systemd-nspawn as well as on
          physical systems via the verity generator. Also note that the "mkosi"
          tool available at https://github.com/systemd/mkosi has been updated
          to generate Verity protected disk images following this scheme. In
          fact, it has been updated to generate disk images that optionally
          implement a complete UEFI SecureBoot trust chain, involving a signed
          kernel and initrd image that incorporates such a root hash as well as
          a Verity-enabled root partition.

        * The hardware database (hwdb) udev supports has been updated to carry
          accelerometer quirks.

        * All system services are now run with a fresh kernel keyring set up
          for them. The invocation ID is stored by default in it, thus
          providing a safe, non-overridable way to determine the invocation
          ID of each service.

        * Service unit files gained new BindPaths= and BindReadOnlyPaths=
          options for bind mounting arbitrary paths in a service-specific
          way. When these options are used, arbitrary host or service files and
          directories may be mounted to arbitrary locations in the service's
          view.

        * Documentation has been added that lists all of systemd's low-level
          environment variables:

          https://github.com/systemd/systemd/blob/master/doc/ENVIRONMENT.md

        * sd-daemon gained a new API sd_is_socket_sockaddr() for determining
          whether a specific socket file descriptor matches a specified socket
          address.

        * systemd-firstboot has been updated to check for the
          systemd.firstboot= kernel command line option. It accepts a boolean
          and when set to false the first boot questions are skipped.

        * systemd-fstab-generator has been updated to check for the
          systemd.volatile= kernel command line option, which either takes an
          optional boolean parameter or the special value "state". If used the
          system may be booted in a "volatile" boot mode. Specifically,
          "systemd.volatile" is used, the root directory will be mounted as
          tmpfs, and only /usr is mounted from the actual root file system. If
          "systemd.volatile=state" is used, the root directory will be mounted
          as usual, but /var is mounted as tmpfs. This concept provides similar
          functionality as systemd-nspawn's --volatile= option, but provides it
          on physical boots. Use this option for implementing stateless
          systems, or testing systems with all state and/or configuration reset
          to the defaults. (Note though that many distributions are not
          prepared to boot up without a populated /etc or /var, though.)

        * systemd-gpt-auto-generator gained support for LUKS encrypted root
          partitions. Previously it only supported LUKS encrypted partitions
          for all other uses, except for the root partition itself.

        * Socket units gained support for listening on AF_VSOCK sockets for
          communication in virtualized QEMU environments.

        * The "configure" script gained a new option --with-fallback-hostname=
          for specifying the fallback hostname to use if none is configured in
          /etc/hostname. For example, by specifying
          --with-fallback-hostname=fedora it is possible to default to a
          hostname of "fedora" on pristine installations.

        * systemd-cgls gained support for a new --unit= switch for listing only
          the control groups of a specific unit. Similar --user-unit= has been
          added for listing only the control groups of a specific user unit.

        * systemd-mount gained a new --umount switch for unmounting a mount or
          automount point (and all mount/automount points below it).

        * systemd will now refuse full configuration reloads (via systemctl
          daemon-reload and related calls) unless at least 16MiB of free space
          are available in /run. This is a safety precaution in order to ensure
          that generators can safely operate after the reload completed.

        * A new unit file option RootImage= has been added, which has a similar
          effect as RootDirectory= but mounts the service's root directory from
          a disk image instead of plain directory. This logic reuses the same
          image dissection and mount logic that systemd-nspawn already uses,
          and hence supports any disk images systemd-nspawn supports, including
          those following the Discoverable Partition Specification, as well as
          Verity enabled images. This option enables systemd to run system
          services directly off disk images acting as resource bundles,
          possibly even including full integrity data.

        * A new MountAPIVFS= unit file option has been added, taking a boolean
          argument. If enabled /proc, /sys and /dev (collectively called the
          "API VFS") will be mounted for the service. This is only relevant if
          RootDirectory= or RootImage= is used for the service, as these mounts
          are of course in place in the host mount namespace anyway.

        * systemd-nspawn gained support for a new --pivot-root= switch. If
          specified the root directory within the container image is pivoted to
          the specified mount point, while the original root disk is moved to a
          different place. This option enables booting of ostree images
          directly with systemd-nspawn.

        * The systemd build scripts will no longer complain if the NTP server
          addresses are not changed from the defaults. Google now supports
          these NTP servers officially. We still recommend downstreams to
          properly register an NTP pool with the NTP pool project though.

        * coredumpctl gained a new "--reverse" option for printing the list
          of coredumps in reverse order.

        * coredumpctl will now show additional information about truncated and
          inaccessible coredumps, as well as coredumps that are still being
          processed. It also gained a new --quiet switch for suppressing
          additional informational message in its output.

        * coredumpctl gained support for only showing coredumps newer and/or
          older than specific timestamps, using the new --since= and --until=
          options, reminiscent of journalctl's options by the same name.

        * The systemd-coredump logic has been improved so that it may be reused
          to collect backtraces in non-compiled languages, for example in
          scripting languages such as Python.

        * machinectl will now show the UID shift of local containers, if user
          namespacing is enabled for them.

        * systemd will now optionally run "environment generator" binaries at
          configuration load time. They may be used to add environment
          variables to the environment block passed to services invoked. One
          user environment generator is shipped by default that sets up
          environment variables based on files dropped into /etc/environment.d
          and ~/.config/environment.d/.

        * systemd-resolved now includes the new, recently published 2017 DNSSEC
          root key (KSK).

        * hostnamed has been updated to report a new chassis type of
          "convertible" to cover "foldable" laptops that can both act as a
          tablet and as a laptop, such as various Lenovo Yoga devices.

        Contributions from: Adrián López, Alexander Galanin, Alexander
        Kochetkov, Alexandros Frantzis, Andrey Ulanov, Antoine Eiche, Baruch
        Siach, Bastien Nocera, Benjamin Robin, Björn, Brandon Philips, Cédric
        Schieli, Charles (Chas) Williams, Christian Hesse, Daniele Medri,
        Daniel Drake, Daniel Rusek, Daniel Wagner, Dan Streetman, Dave Reisner,
        David Glasser, David Herrmann, David Michael, Djalal Harouni, Dmitry
        Khlebnikov, Dmitry Rozhkov, Dongsu Park, Douglas Christman, Earnestly,
        Emil Soleyman, Eric Cook, Evgeny Vereshchagin, Felipe Sateler, Fionn
        Cleary, Florian Klink, Francesco Brozzu, Franck Bui, Gabriel Rauter,
        Gianluca Boiano, Giedrius Statkevičius, Graeme Lawes, Hans de Goede,
        Harald Hoyer, Ian Kelling, Ivan Shapovalov, Jakub Wilk, Janne Heß, Jan
        Synacek, Jason Reeder, Jonathan Boulle, Jörg Thalheim, Jouke Witteveen,
        Karl Kraus, Kees Cook, Keith Busch, Kieran Colford, kilian-k, Lennart
        Poettering, Lubomir Rintel, Lucas Werkmeister, Lukas Rusak, Maarten de
        Vries, Maks Naumov, Mantas Mikulėnas, Marc-Andre Lureau, Marcin Bachry,
        Mark Stosberg, Martin Ejdestig, Martin Pitt, Mauricio Faria de
        Oliveira, micah, Michael Biebl, Michael Shields, Michal Schmidt, Michal
        Sekletar, Michel Kraus, Mike Gilbert, Mikko Ylinen, Mirza Krak,
        Namhyung Kim, nikolaof, peoronoob, Peter Hutterer, Peter Körner, Philip
        Withnall, Piotr Drąg, Ray Strode, Reverend Homer, Rike-Benjamin
        Schuppner, Robert Kreuzer, Ronny Chevalier, Ruslan Bilovol, sammynx,
        Sergey Ptashnick, Sergiusz Urbaniak, Stefan Berger, Stefan Hajnoczi,
        Stefan Schweter, Stuart McLaren, Susant Sahani, Sylvain Plantefève,
        Taylor Smock, Tejun Heo, Thomas Blume, Thomas H. P. Andersen, Tibor
        Nagy, Tobias Stoeckmann, Tom Gundersen, Torstein Husebø, Viktar
        Vaŭčkievič, Viktor Mihajlovski, Vitaly Sulimov, Waldemar Brodkorb,
        Walter Garcia-Fontes, Wim de With, Yassine Imounachen, Yi EungJun,
        YunQiang Su, Yu Watanabe, Zbigniew Jędrzejewski-Szmek, Александр
        Тихонов

        — Berlin, 2017-03-01

CHANGES WITH 232:

        * udev now runs with MemoryDenyWriteExecute=, RestrictRealtime= and
          RestrictAddressFamilies= enabled. These sandboxing options should
          generally be compatible with the various external udev call-out
          binaries we are aware of, however there may be exceptions, in
          particular when exotic languages for these call-outs are used. In
          this case, consider turning off these settings locally.

        * The new RemoveIPC= option can be used to remove IPC objects owned by
          the user or group of a service when that service exits.

        * The new ProtectKernelModules= option can be used to disable explicit
          load and unload operations of kernel modules by a service. In
          addition access to /usr/lib/modules is removed if this option is set.

        * ProtectSystem= option gained a new value "strict", which causes the
          whole file system tree with the exception of /dev, /proc, and /sys,
          to be remounted read-only for a service.

        * The new ProtectKernelTunables= option can be used to disable
          modification of configuration files in /sys and /proc by a service.
          Various directories and files are remounted read-only, so access is
          restricted even if the file permissions would allow it.

        * The new ProtectControlGroups= option can be used to disable write
          access by a service to /sys/fs/cgroup.

        * Various systemd services have been hardened with
          ProtectKernelTunables=yes, ProtectControlGroups=yes,
          RestrictAddressFamilies=.

        * Support for dynamically creating users for the lifetime of a service
          has been added. If DynamicUser=yes is specified, user and group IDs
          will be allocated from the range 61184..65519 for the lifetime of the
          service. They can be resolved using the new nss-systemd.so NSS
          module. The module must be enabled in /etc/nsswitch.conf. Services
          started in this way have PrivateTmp= and RemoveIPC= enabled, so that
          any resources allocated by the service will be cleaned up when the
          service exits. They also have ProtectHome=read-only and
          ProtectSystem=strict enabled, so they are not able to make any
          permanent modifications to the system.

        * The nss-systemd module also always resolves root and nobody, making
          it possible to have no /etc/passwd or /etc/group files in minimal
          container or chroot environments.

        * Services may be started with their own user namespace using the new
          boolean PrivateUsers= option. Only root, nobody, and the uid/gid
          under which the service is running are mapped. All other users are
          mapped to nobody.

        * Support for the cgroup namespace has been added to systemd-nspawn. If
          supported by kernel, the container system started by systemd-nspawn
          will have its own view of the cgroup hierarchy. This new behaviour
          can be disabled using $SYSTEMD_NSPAWN_USE_CGNS environment variable.

        * The new MemorySwapMax= option can be used to limit the maximum swap
          usage under the unified cgroup hierarchy.

        * Support for the CPU controller in the unified cgroup hierarchy has
          been added, via the CPUWeight=, CPUStartupWeight=, CPUAccounting=
          options. This controller requires out-of-tree patches for the kernel
          and the support is provisional.

        * Mount and automount units may now be created transiently
          (i.e. dynamically at runtime via the bus API, instead of requiring
          unit files in the file system).

        * systemd-mount is a new tool which may mount file systems – much like
          mount(8), optionally pulling in additional dependencies through
          transient .mount and .automount units. For example, this tool
          automatically runs fsck on a backing block device before mounting,
          and allows the automount logic to be used dynamically from the
          command line for establishing mount points. This tool is particularly
          useful when dealing with removable media, as it will ensure fsck is
          run – if necessary – before the first access and that the file system
          is quickly unmounted after each access by utilizing the automount
          logic. This maximizes the chance that the file system on the
          removable media stays in a clean state, and if it isn't in a clean
          state is fixed automatically.

        * LazyUnmount=yes option for mount units has been added to expose the
          umount --lazy option. Similarly, ForceUnmount=yes exposes the --force
          option.

        * /efi will be used as the mount point of the EFI boot partition, if
          the directory is present, and the mount point was not configured
          through other means (e.g. fstab). If /efi directory does not exist,
          /boot will be used as before. This makes it easier to automatically
          mount the EFI partition on systems where /boot is used for something
          else.

        * When operating on GPT disk images for containers, systemd-nspawn will
          now mount the ESP to /boot or /efi according to the same rules as PID
          1 running on a host. This allows tools like "bootctl" to operate
          correctly within such containers, in order to make container images
          bootable on physical systems.

        * disk/by-id and disk/by-path symlinks are now created for NVMe drives.

        * Two new user session targets have been added to support running
          graphical sessions under the systemd --user instance:
          graphical-session.target and graphical-session-pre.target. See
          systemd.special(7) for a description of how those targets should be
          used.

        * The vconsole initialization code has been significantly reworked to
          use KD_FONT_OP_GET/SET ioctls instead of KD_FONT_OP_COPY and better
          support unicode keymaps. Font and keymap configuration will now be
          copied to all allocated virtual consoles.

        * FreeBSD's bhyve virtualization is now detected.

        * Information recorded in the journal for core dumps now includes the
          contents of /proc/mountinfo and the command line of the process at
          the top of the process hierarchy (which is usually the init process
          of the container).

        * systemd-journal-gatewayd learned the --directory= option to serve
          files from the specified location.

        * journalctl --root=… can be used to peruse the journal in the
          /var/log/ directories inside of a container tree. This is similar to
          the existing --machine= option, but does not require the container to
          be active.

        * The hardware database has been extended to support
          ID_INPUT_TRACKBALL, used in addition to ID_INPUT_MOUSE to identify
          trackball devices.

          MOUSE_WHEEL_CLICK_ANGLE_HORIZONTAL hwdb property has been added to
          specify the click rate for mice which include a horizontal wheel with
          a click rate that is different than the one for the vertical wheel.

        * systemd-run gained a new --wait option that makes service execution
          synchronous. (Specifically, the command will not return until the
          specified service binary exited.)

        * systemctl gained a new --wait option that causes the start command to
          wait until the units being started have terminated again.

        * A new journal output mode "short-full" has been added which displays
          timestamps with abbreviated English day names and adds a timezone
          suffix. Those timestamps include more information than the default
          "short" output mode, and can be passed directly to journalctl's
          --since= and --until= options.

        * /etc/resolv.conf will be bind-mounted into containers started by
          systemd-nspawn, if possible, so any changes to resolv.conf contents
          are automatically propagated to the container.

        * The number of instances for socket-activated services originating
          from a single IP address can be limited with
          MaxConnectionsPerSource=, extending the existing setting of
          MaxConnections=.

        * systemd-networkd gained support for vcan ("Virtual CAN") interface
          configuration.

        * .netdev and .network configuration can now be extended through
          drop-ins.

        * UDP Segmentation Offload, TCP Segmentation Offload, Generic
          Segmentation Offload, Generic Receive Offload, Large Receive Offload
          can be enabled and disabled using the new UDPSegmentationOffload=,
          TCPSegmentationOffload=, GenericSegmentationOffload=,
          GenericReceiveOffload=, LargeReceiveOffload= options in the
          [Link] section of .link files.

        * The Spanning Tree Protocol, Priority, Aging Time, and the Default
          Port VLAN ID can be configured for bridge devices using the new STP=,
          Priority=, AgeingTimeSec=, and DefaultPVID= settings in the [Bridge]
          section of .netdev files.

        * The route table to which routes received over DHCP or RA should be
          added can be configured with the new RouteTable= option in the [DHCP]
          and [IPv6AcceptRA] sections of .network files.

        * The Address Resolution Protocol can be disabled on links managed by
          systemd-networkd using the ARP=no setting in the [Link] section of
          .network files.

        * New environment variables $SERVICE_RESULT, $EXIT_CODE and
          $EXIT_STATUS are set for ExecStop= and ExecStopPost= commands, and
          encode information about the result and exit codes of the current
          service runtime cycle.

        * systemd-sysctl will now configure kernel parameters in the order
          they occur in the configuration files. This matches what sysctl
          has been traditionally doing.

        * kernel-install "plugins" that are executed to perform various
          tasks after a new kernel is added and before an old one is removed
          can now return a special value to terminate the procedure and
          prevent any later plugins from running.

        * Journald's SplitMode=login setting has been deprecated. It has been
          removed from documentation, and its use is discouraged. In a future
          release it will be completely removed, and made equivalent to current
          default of SplitMode=uid.

        * Storage=both option setting in /etc/systemd/coredump.conf has been
          removed. With fast LZ4 compression storing the core dump twice is not
          useful.

        * The --share-system systemd-nspawn option has been replaced with an
          (undocumented) variable $SYSTEMD_NSPAWN_SHARE_SYSTEM, but the use of
          this functionality is discouraged. In addition the variables
          $SYSTEMD_NSPAWN_SHARE_NS_IPC, $SYSTEMD_NSPAWN_SHARE_NS_PID,
          $SYSTEMD_NSPAWN_SHARE_NS_UTS may be used to control the unsharing of
          individual namespaces.

        * "machinectl list" now shows the IP address of running containers in
          the output, as well as OS release information.

        * "loginctl list" now shows the TTY of each session in the output.

        * sd-bus gained new API calls sd_bus_track_set_recursive(),
          sd_bus_track_get_recursive(), sd_bus_track_count_name(),
          sd_bus_track_count_sender(). They permit usage of sd_bus_track peer
          tracking objects in a "recursive" mode, where a single client can be
          counted multiple times, if it takes multiple references.

        * sd-bus gained new API calls sd_bus_set_exit_on_disconnect() and
          sd_bus_get_exit_on_disconnect(). They may be used to make a
          process using sd-bus automatically exit if the bus connection is
          severed.

        * Bus clients of the service manager may now "pin" loaded units into
          memory, by taking an explicit reference on them. This is useful to
          ensure the client can retrieve runtime data about the service even
          after the service completed execution. Taking such a reference is
          available only for privileged clients and should be helpful to watch
          running services in a race-free manner, and in particular collect
          information about exit statuses and results.

        * The nss-resolve module has been changed to strictly return UNAVAIL
          when communication via D-Bus with resolved failed, and NOTFOUND when
          a lookup completed but was negative. This means it is now possible to
          neatly configure fallbacks using nsswitch.conf result checking
          expressions. Taking benefit of this, the new recommended
          configuration line for the "hosts" entry in /etc/nsswitch.conf is:

              hosts: files mymachines resolve [!UNAVAIL=return] dns myhostname

        * A new setting CtrlAltDelBurstAction= has been added to
          /etc/systemd/system.conf which may be used to configure the precise
          behaviour if the user on the console presses Ctrl-Alt-Del more often
          than 7 times in 2s. Previously this would unconditionally result in
          an expedited, immediate reboot. With this new setting the precise
          operation may be configured in more detail, and also turned off
          entirely.

        * In .netdev files two new settings RemoteChecksumTx= and
          RemoteChecksumRx= are now understood that permit configuring the
          remote checksumming logic for VXLAN networks.

        * The service manager learnt a new "invocation ID" concept for invoked
          services. Each runtime cycle of a service will get a new invocation
          ID (a 128bit random UUID) assigned that identifies the current
          run of the service uniquely and globally. A new invocation ID
          is generated each time a service starts up. The journal will store
          the invocation ID of a service along with any logged messages, thus
          making the invocation ID useful for matching the online runtime of a
          service with the offline log data it generated in a safe way without
          relying on synchronized timestamps. In many ways this new service
          invocation ID concept is similar to the kernel's boot ID concept that
          uniquely and globally identifies the runtime of each boot. The
          invocation ID of a service is passed to the service itself via an
          environment variable ($INVOCATION_ID). A new bus call
          GetUnitByInvocationID() has been added that is similar to GetUnit()
          but instead of retrieving the bus path for a unit by its name
          retrieves it by its invocation ID. The returned path is valid only as
          long as the passed invocation ID is current.

        * systemd-resolved gained a new "DNSStubListener" setting in
          resolved.conf. It either takes a boolean value or the special values
          "udp" and "tcp", and configures whether to enable the stub DNS
          listener on 127.0.0.53:53.

        * IP addresses configured via networkd may now carry additional
          configuration settings supported by the kernel. New options include:
          HomeAddress=, DuplicateAddressDetection=, ManageTemporaryAddress=,
          PrefixRoute=, AutoJoin=.

        * The PAM configuration fragment file for "user@.service" shipped with
          systemd (i.e. the --user instance of systemd) has been stripped to
          the minimum necessary to make the system boot. Previously, it
          contained Fedora-specific stanzas that did not apply to other
          distributions. It is expected that downstream distributions add
          additional configuration lines, matching their needs to this file,
          using it only as rough template of what systemd itself needs. Note
          that this reduced fragment does not even include an invocation of
          pam_limits which most distributions probably want to add, even though
          systemd itself does not need it. (There's also the new build time
          option --with-pamconfdir=no to disable installation of the PAM
          fragment entirely.)

        * If PrivateDevices=yes is set for a service the CAP_SYS_RAWIO
          capability is now also dropped from its set (in addition to
          CAP_SYS_MKNOD as before).

        * In service unit files it is now possible to connect a specific named
          file descriptor with stdin/stdout/stdout of an executed service. The
          name may be specified in matching .socket units using the
          FileDescriptorName= setting.

        * A number of journal settings may now be configured on the kernel
          command line. Specifically, the following options are now understood:
          systemd.journald.max_level_console=,
          systemd.journald.max_level_store=,
          systemd.journald.max_level_syslog=, systemd.journald.max_level_kmsg=,
          systemd.journald.max_level_wall=.

        * "systemctl is-enabled --full" will now show by which symlinks a unit
          file is enabled in the unit dependency tree.

        * Support for VeraCrypt encrypted partitions has been added to the
          "cryptsetup" logic and /etc/crypttab.

        * systemd-detect-virt gained support for a new --private-users switch
          that checks whether the invoking processes are running inside a user
          namespace. Similar, a new special value "private-users" for the
          existing ConditionVirtualization= setting has been added, permitting
          skipping of specific units in user namespace environments.

        Contributions from: Alban Crequy, Alexander Kuleshov, Alfie John,
        Andreas Henriksson, Andrew Jeddeloh, Balázs Úr, Bart Rulon, Benjamin
        Richter, Ben Gamari, Ben Harris, Brian J. Murrell, Christian Brauner,
        Christian Rebischke, Clinton Roy, Colin Walters, Cristian Rodríguez,
        Daniel Hahler, Daniel Mack, Daniel Maixner, Daniel Rusek, Dan Dedrick,
        Davide Cavalca, David Herrmann, David Michael, Dennis Wassenberg,
        Djalal Harouni, Dongsu Park, Douglas Christman, Elias Probst, Eric
        Cook, Erik Karlsson, Evgeny Vereshchagin, Felipe Sateler, Felix Zhang,
        Franck Bui, George Hilliard, Giuseppe Scrivano, HATAYAMA Daisuke,
        Heikki Kemppainen, Hendrik Brueckner, hi117, Ismo Puustinen, Ivan
        Shapovalov, Jakub Filak, Jakub Wilk, Jan Synacek, Jason Kölker,
        Jean-Sébastien Bour, Jiří Pírko, Jonathan Boulle, Jorge Niedbalski,
        Keith Busch, kristbaum, Kyle Russell, Lans Zhang, Lennart Poettering,
        Leonardo Brondani Schenkel, Lucas Werkmeister, Luca Bruno, Lukáš
        Nykrýn, Maciek Borzecki, Mantas Mikulėnas, Marc-Antoine Perennou,
        Marcel Holtmann, Marcos Mello, Martin Ejdestig, Martin Pitt, Matej
        Habrnal, Maxime de Roucy, Michael Biebl, Michael Chapman, Michael Hoy,
        Michael Olbrich, Michael Pope, Michal Sekletar, Michal Soltys, Mike
        Gilbert, Nick Owens, Patrik Flykt, Paweł Szewczyk, Peter Hutterer,
        Piotr Drąg, Reid Price, Richard W.M. Jones, Roman Stingler, Ronny
        Chevalier, Seraphime Kirkovski, Stefan Schweter, Steve Muir, Susant
        Sahani, Tejun Heo, Thomas Blume, Thomas H. P. Andersen, Tiago Levit,
        Tobias Jungel, Tomáš Janoušek, Topi Miettinen, Torstein Husebø, Umut
        Tezduyar Lindskog, Vito Caputo, WaLyong Cho, Wilhelm Schuster, Yann
        E. MORIN, Yi EungJun, Yuki Inoguchi, Yu Watanabe, Zbigniew
        Jędrzejewski-Szmek, Zeal Jagannatha

        — Santa Fe, 2016-11-03

CHANGES WITH 231:

        * In service units the various ExecXYZ= settings have been extended
          with an additional special character as first argument of the
          assigned value: if the character '+' is used the specified command
          line it will be run with full privileges, regardless of User=,
          Group=, CapabilityBoundingSet= and similar options. The effect is
          similar to the existing PermissionsStartOnly= option, but allows
          configuration of this concept for each executed command line
          independently.

        * Services may now alter the service watchdog timeout at runtime by
          sending a WATCHDOG_USEC= message via sd_notify().

        * MemoryLimit= and related unit settings now optionally take percentage
          specifications. The percentage is taken relative to the amount of
          physical memory in the system (or in case of containers, the assigned
          amount of memory). This allows scaling service resources neatly with
          the amount of RAM available on the system. Similarly, systemd-logind's
          RuntimeDirectorySize= option now also optionally takes percentage
          values.

        * In similar fashion TasksMax= takes percentage values now, too. The
          value is taken relative to the configured maximum number of processes
          on the system. The per-service task maximum has been changed to 15%
          using this functionality. (Effectively this is an increase of 512 →
          4915 for service units, given the kernel's default pid_max setting.)

        * Calendar time specifications in .timer units now understand a ".."
          syntax for time ranges. Example: "4..7:10" may now be used for
          defining a timer that is triggered at 4:10am, 5:10am, 6:10am and
          7:10am every day.

        * The InaccessableDirectories=, ReadOnlyDirectories= and
          ReadWriteDirectories= unit file settings have been renamed to
          InaccessablePaths=, ReadOnlyPaths= and ReadWritePaths= and may now be
          applied to all kinds of file nodes, and not just directories, with
          the exception of symlinks. Specifically these settings may now be
          used on block and character device nodes, UNIX sockets and FIFOS as
          well as regular files. The old names of these settings remain
          available for compatibility.

        * systemd will now log about all service processes it kills forcibly
          (using SIGKILL) because they remained after the clean shutdown phase
          of the service completed. This should help identifying services that
          shut down uncleanly. Moreover if KillUserProcesses= is enabled in
          systemd-logind's configuration a similar log message is generated for
          processes killed at the end of each session due to this setting.

        * systemd will now set the $JOURNAL_STREAM environment variable for all
          services whose stdout/stderr are connected to the Journal (which
          effectively means by default: all services). The variable contains
          the device and inode number of the file descriptor used for
          stdout/stderr. This may be used by invoked programs to detect whether
          their stdout/stderr is connected to the Journal, in which case they
          can switch over to direct Journal communication, thus being able to
          pass extended, structured metadata along with their log messages. As
          one example, this is now used by glib's logging primitives.

        * When using systemd's default tmp.mount unit for /tmp, the mount point
          will now be established with the "nosuid" and "nodev" options. This
          avoids privilege escalation attacks that put traps and exploits into
          /tmp.  However, this might cause problems if you e. g. put container
          images or overlays into /tmp; if you need this, override tmp.mount's
          "Options=" with a drop-in, or mount /tmp from /etc/fstab with your
          desired options.

        * systemd now supports the "memory" cgroup controller also on
          cgroupsv2.

        * The systemd-cgtop tool now optionally takes a control group path as
          command line argument. If specified, the control group list shown is
          limited to subgroups of that group.

        * The SystemCallFilter= unit file setting gained support for
          pre-defined, named system call filter sets. For example
          SystemCallFilter=@clock is now an effective way to make all clock
          changing-related system calls unavailable to a service. A number of
          similar pre-defined groups are defined. Writing system call filters
          for system services is simplified substantially with this new
          concept. Accordingly, all of systemd's own, long-running services now
          enable system call filtering based on this, by default.

        * A new service setting MemoryDenyWriteExecute= has been added, taking
          a boolean value. If turned on, a service may no longer create memory
          mappings that are writable and executable at the same time. This
          enhances security for services where this is enabled as it becomes
          harder to dynamically write and then execute memory in exploited
          service processes. This option has been enabled for all of systemd's
          own long-running services.

        * A new RestrictRealtime= service setting has been added, taking a
          boolean argument. If set the service's processes may no longer
          acquire realtime scheduling. This improves security as realtime
          scheduling may otherwise be used to easily freeze the system.

        * systemd-nspawn gained a new switch --notify-ready= taking a boolean
          value. This may be used for requesting that the system manager inside
          of the container reports start-up completion to nspawn which then
          propagates this notification further to the service manager
          supervising nspawn itself. A related option NotifyReady= in .nspawn
          files has been added too. This functionality allows ordering of the
          start-up of multiple containers using the usual systemd ordering
          primitives.

        * machinectl gained a new command "stop" that is an alias for
          "terminate".

        * systemd-resolved gained support for contacting DNS servers on
          link-local IPv6 addresses.

        * If systemd-resolved receives the SIGUSR2 signal it will now flush all
          its caches. A method call for requesting the same operation has been
          added to the bus API too, and is made available via "systemd-resolve
          --flush-caches".

        * systemd-resolve gained a new --status switch. If passed a brief
          summary of the used DNS configuration with per-interface information
          is shown.

        * resolved.conf gained a new Cache= boolean option, defaulting to
          on. If turned off local DNS caching is disabled. This comes with a
          performance penalty in particular when DNSSEC is enabled. Note that
          resolved disables its internal caching implicitly anyway, when the
          configured DNS server is on a host-local IP address such as ::1 or
          127.0.0.1, thus automatically avoiding double local caching.

        * systemd-resolved now listens on the local IP address 127.0.0.53:53
          for DNS requests. This improves compatibility with local programs
          that do not use the libc NSS or systemd-resolved's bus APIs for name
          resolution. This minimal DNS service is only available to local
          programs and does not implement the full DNS protocol, but enough to
          cover local DNS clients. A new, static resolv.conf file, listing just
          this DNS server is now shipped in /usr/lib/systemd/resolv.conf. It is
          now recommended to make /etc/resolv.conf a symlink to this file in
          order to route all DNS lookups to systemd-resolved, regardless if
          done via NSS, the bus API or raw DNS packets. Note that this local
          DNS service is not as fully featured as the libc NSS or
          systemd-resolved's bus APIs. For example, as unicast DNS cannot be
          used to deliver link-local address information (as this implies
          sending a local interface index along), LLMNR/mDNS support via this
          interface is severely restricted. It is thus strongly recommended for
          all applications to use the libc NSS API or native systemd-resolved
          bus API instead.

        * systemd-networkd's bridge support learned a new setting
          VLANFiltering= for controlling VLAN filtering. Moreover a new section
          in .network files has been added for configuring VLAN bridging in
          more detail: VLAN=, EgressUntagged=, PVID= in [BridgeVLAN].

        * systemd-networkd's IPv6 Router Advertisement code now makes use of
          the DNSSL and RDNSS options. This means IPv6 DNS configuration may
          now be acquired without relying on DHCPv6. Two new options
          UseDomains= and UseDNS= have been added to configure this behaviour.

        * systemd-networkd's IPv6AcceptRouterAdvertisements= option has been
          renamed IPv6AcceptRA=, without altering its behaviour. The old
          setting name remains available for compatibility reasons.

        * The systemd-networkd VTI/VTI6 tunneling support gained new options
          Key=, InputKey= and OutputKey=.

        * systemd-networkd gained support for VRF ("Virtual Routing Function")
          interface configuration.

        * "systemctl edit" may now be used to create new unit files by
          specifying the --force switch.

        * sd-event gained a new function sd_event_get_iteration() for
          requesting the current iteration counter of the event loop. It starts
          at zero and is increased by one with each event loop iteration.

        * A new rpm macro %systemd_ordering is provided by the macros.systemd
          file. It can be used in lieu of %systemd_requires in packages which
          don't use any systemd functionality and are intended to be installed
          in minimal containers without systemd present. This macro provides
          ordering dependencies to ensure that if the package is installed in
          the same rpm transaction as systemd, systemd will be installed before
          the scriptlets for the package are executed, allowing unit presets
          to be handled.

          New macros %_systemdgeneratordir and %_systemdusergeneratordir have
          been added to simplify packaging of generators.

        * The os-release file gained VERSION_CODENAME field for the
          distribution nickname (e.g. VERSION_CODENAME=woody).

        * New udev property UDEV_DISABLE_PERSISTENT_STORAGE_RULES_FLAG=1
          can be set to disable parsing of metadata and the creation
          of persistent symlinks for that device.

        * The v230 change to tag framebuffer devices (/dev/fb*) with "uaccess"
          to make them available to logged-in users has been reverted.

        * Much of the common code of the various systemd components is now
          built into an internal shared library libsystemd-shared-231.so
          (incorporating the systemd version number in the name, to be updated
          with future releases) that the components link to. This should
          decrease systemd footprint both in memory during runtime and on
          disk. Note that the shared library is not for public use, and is
          neither API nor ABI stable, but is likely to change with every new
          released update. Packagers need to make sure that binaries
          linking to libsystemd-shared.so are updated in step with the
          library.

        * Configuration for "mkosi" is now part of the systemd
          repository. mkosi is a tool to easily build legacy-free OS images,
          and is available on github: https://github.com/systemd/mkosi. If
          "mkosi" is invoked in the build tree a new raw OS image is generated
          incorporating the systemd sources currently being worked on and a
          clean, fresh distribution installation. The generated OS image may be
          booted up with "systemd-nspawn -b -i", qemu-kvm or on any physical
          UEFI PC. This functionality is particularly useful to easily test
          local changes made to systemd in a pristine, defined environment. See
          doc/HACKING for details.

        * configure learned the --with-support-url= option to specify the
          distribution's bugtracker.

        Contributions from: Alban Crequy, Alessandro Puccetti, Alessio Igor
        Bogani, Alexander Kuleshov, Alexander Kurtz, Alex Gaynor, Andika
        Triwidada, Andreas Pokorny, Andreas Rammhold, Andrew Jeddeloh, Ansgar
        Burchardt, Atrotors, Benjamin Drung, Brian Boylston, Christian Hesse,
        Christian Rebischke, Daniele Medri, Daniel Mack, Dave Reisner, David
        Herrmann, David Michael, Djalal Harouni, Douglas Christman, Elias
        Probst, Evgeny Vereshchagin, Federico Mena Quintero, Felipe Sateler,
        Franck Bui, Harald Hoyer, Ian Lee, Ivan Shapovalov, Jakub Wilk, Jan
        Janssen, Jean-Sébastien Bour, John Paul Adrian Glaubitz, Jouke
        Witteveen, Kai Ruhnau, kpengboy, Kyle Walker, Lénaïc Huard, Lennart
        Poettering, Luca Bruno, Lukas Lösche, Lukáš Nykrýn, mahkoh, Marcel
        Holtmann, Martin Pitt, Marty Plummer, Matthieu Codron, Max Prokhorov,
        Michael Biebl, Michael Karcher, Michael Olbrich, Michał Bartoszkiewicz,
        Michal Sekletar, Michal Soltys, Minkyung, Muhammet Kara, mulkieran,
        Otto Wallenius, Pablo Lezaeta Reyes, Peter Hutterer, Ronny Chevalier,
        Rusty Bird, Stef Walter, Susant Sahani, Tejun Heo, Thomas Blume, Thomas
        Haller, Thomas H. P. Andersen, Tobias Jungel, Tom Gundersen, Tom Yan,
        Topi Miettinen, Torstein Husebø, Valentin Vidić, Viktar Vaŭčkievič,
        WaLyong Cho, Weng Xuetian, Werner Fink, Zbigniew Jędrzejewski-Szmek

        — Berlin, 2016-07-25

CHANGES WITH 230:

        * DNSSEC is now turned on by default in systemd-resolved (in
          "allow-downgrade" mode), but may be turned off during compile time by
          passing "--with-default-dnssec=no" to "configure" (and of course,
          during runtime with DNSSEC= in resolved.conf). We recommend
          downstreams to leave this on at least during development cycles and
          report any issues with the DNSSEC logic upstream. We are very
          interested in collecting feedback about the DNSSEC validator and its
          limitations in the wild. Note however, that DNSSEC support is
          probably nothing downstreams should turn on in stable distros just
          yet, as it might create incompatibilities with a few DNS servers and
          networks. We tried hard to make sure we downgrade to non-DNSSEC mode
          automatically whenever we detect such incompatible setups, but there
          might be systems we do not cover yet. Hence: please help us testing
          the DNSSEC code, leave this on where you can, report back, but then
          again don't consider turning this on in your stable, LTS or
          production release just yet. (Note that you have to enable
          nss-resolve in /etc/nsswitch.conf, to actually use systemd-resolved
          and its DNSSEC mode for host name resolution from local
          applications.)

        * systemd-resolve conveniently resolves DANE records with the --tlsa
          option and OPENPGPKEY records with the --openpgp option. It also
          supports dumping raw DNS record data via the new --raw= switch.

        * systemd-logind will now by default terminate user processes that are
          part of the user session scope unit (session-XX.scope) when the user
          logs out. This behavior is controlled by the KillUserProcesses=
          setting in logind.conf, and the previous default of "no" is now
          changed to "yes". This means that user sessions will be properly
          cleaned up after, but additional steps are necessary to allow
          intentionally long-running processes to survive logout.

          While the user is logged in at least once, user@.service is running,
          and any service that should survive the end of any individual login
          session can be started at a user service or scope using systemd-run.
          systemd-run(1) man page has been extended with an example which shows
          how to run screen in a scope unit underneath user@.service. The same
          command works for tmux.

          After the user logs out of all sessions, user@.service will be
          terminated too, by default, unless the user has "lingering" enabled.
          To effectively allow users to run long-term tasks even if they are
          logged out, lingering must be enabled for them. See loginctl(1) for
          details. The default polkit policy was modified to allow users to
          set lingering for themselves without authentication.

          Previous defaults can be restored at compile time by the
          --without-kill-user-processes option to "configure".

        * systemd-logind gained new configuration settings SessionsMax= and
          InhibitorsMax=, both with a default of 8192. It will not register new
          user sessions or inhibitors above this limit.

        * systemd-logind will now reload configuration on SIGHUP.

        * The unified cgroup hierarchy added in Linux 4.5 is now supported.
          Use systemd.unified_cgroup_hierarchy=1 on the kernel command line to
          enable. Also, support for the "io" cgroup controller in the unified
          hierarchy has been added, so that the "memory", "pids" and "io" are
          now the controllers that are supported on the unified hierarchy.

          WARNING: it is not possible to use previous systemd versions with
          systemd.unified_cgroup_hierarchy=1 and the new kernel. Therefore it
          is necessary to also update systemd in the initramfs if using the
          unified hierarchy. An updated SELinux policy is also required.

        * LLDP support has been extended, and both passive (receive-only) and
          active (sender) modes are supported. Passive mode ("routers-only") is
          enabled by default in systemd-networkd. Active LLDP mode is enabled
          by default for containers on the internal network. The "networkctl
          lldp" command may be used to list information gathered. "networkctl
          status" will also show basic LLDP information on connected peers now.

        * The IAID and DUID unique identifier sent in DHCP requests may now be
          configured for the system and each .network file managed by
          systemd-networkd using the DUIDType=, DUIDRawData=, IAID= options.

        * systemd-networkd gained support for configuring proxy ARP support for
          each interface, via the ProxyArp= setting in .network files. It also
          gained support for configuring the multicast querier feature of
          bridge devices, via the new MulticastQuerier= setting in .netdev
          files. Similarly, snooping on the IGMP traffic can be controlled
          via the new setting MulticastSnooping=.

          A new setting PreferredLifetime= has been added for addresses
          configured in .network file to configure the lifetime intended for an
          address.

          The systemd-networkd DHCP server gained the option EmitRouter=, which
          defaults to yes, to configure whether the DHCP Option 3 (Router)
          should be emitted.

        * The testing tool /usr/lib/systemd/systemd-activate is renamed to
          systemd-socket-activate and installed into /usr/bin. It is now fully
          supported.

        * systemd-journald now uses separate threads to flush changes to disk
          when closing journal files, thus reducing impact of slow disk I/O on
          logging performance.

        * The sd-journal API gained two new calls
          sd_journal_open_directory_fd() and sd_journal_open_files_fd() which
          can be used to open journal files using file descriptors instead of
          file or directory paths. sd_journal_open_container() has been
          deprecated, sd_journal_open_directory_fd() should be used instead
          with the flag SD_JOURNAL_OS_ROOT.

        * journalctl learned a new output mode "-o short-unix" that outputs log
          lines prefixed by their UNIX time (i.e. seconds since Jan 1st, 1970
          UTC). It also gained support for a new --no-hostname setting to
          suppress the hostname column in the family of "short" output modes.

        * systemd-ask-password now optionally skips printing of the password to
          stdout with --no-output which can be useful in scripts.

        * Framebuffer devices (/dev/fb*) and 3D printers and scanners
          (devices tagged with ID_MAKER_TOOL) are now tagged with
          "uaccess" and are available to logged in users.

        * The DeviceAllow= unit setting now supports specifiers (with "%").

        * "systemctl show" gained a new --value switch, which allows print a
          only the contents of a specific unit property, without also printing
          the property's name. Similar support was added to "show*" verbs
          of loginctl and machinectl that output "key=value" lists.

        * A new unit type "generated" was added for files dynamically generated
          by generator tools. Similarly, a new unit type "transient" is used
          for unit files created using the runtime API. "systemctl enable" will
          refuse to operate on such files.

        * A new command "systemctl revert" has been added that may be used to
          revert to the vendor version of a unit file, in case local changes
          have been made by adding drop-ins or overriding the unit file.

        * "machinectl clean" gained a new verb to automatically remove all or
          just hidden container images.

        * systemd-tmpfiles gained support for a new line type "e" for emptying
          directories, if they exist, without creating them if they don't.

        * systemd-nspawn gained support for automatically patching the UID/GIDs
          of the owners and the ACLs of all files and directories in a
          container tree to match the UID/GID user namespacing range selected
          for the container invocation. This mode is enabled via the new
          --private-users-chown switch. It also gained support for
          automatically choosing a free, previously unused UID/GID range when
          starting a container, via the new --private-users=pick setting (which
          implies --private-users-chown). Together, these options for the first
          time make user namespacing for nspawn containers fully automatic and
          thus deployable. The systemd-nspawn@.service template unit file has
          been changed to use this functionality by default.

        * systemd-nspawn gained a new --network-zone= switch, that allows
          creating ad-hoc virtual Ethernet links between multiple containers,
          that only exist as long as at least one container referencing them is
          running. This allows easy connecting of multiple containers with a
          common link that implements an Ethernet broadcast domain. Each of
          these network "zones" may be named relatively freely by the user, and
          may be referenced by any number of containers, but each container may
          only reference one of these "zones". On the lower level, this is
          implemented by an automatically managed bridge network interface for
          each zone, that is created when the first container referencing its
          zone is created and removed when the last one referencing its zone
          terminates.

        * The default start timeout may now be configured on the kernel command
          line via systemd.default_timeout_start_sec=. It was already
          configurable via the DefaultTimeoutStartSec= option in
          /etc/systemd/system.conf.

        * Socket units gained a new TriggerLimitIntervalSec= and
          TriggerLimitBurst= setting to configure a limit on the activation
          rate of the socket unit.

        * The LimitNICE= setting now optionally takes normal UNIX nice values
          in addition to the raw integer limit value. If the specified
          parameter is prefixed with "+" or "-" and is in the range -20..19 the
          value is understood as UNIX nice value. If not prefixed like this it
          is understood as raw RLIMIT_NICE limit.

        * Note that the effect of the PrivateDevices= unit file setting changed
          slightly with this release: the per-device /dev file system will be
          mounted read-only from this version on, and will have "noexec"
          set. This (minor) change of behavior might cause some (exceptional)
          legacy software to break, when PrivateDevices=yes is set for its
          service. Please leave PrivateDevices= off if you run into problems
          with this.

        * systemd-bootchart has been split out to a separate repository:
          https://github.com/systemd/systemd-bootchart

        * systemd-bus-proxyd has been removed, as kdbus is unlikely to still be
          merged into the kernel in its current form.

        * The compatibility libraries libsystemd-daemon.so,
          libsystemd-journal.so, libsystemd-id128.so, and libsystemd-login.so
          which have been deprecated since systemd-209 have been removed along
          with the corresponding pkg-config files. All symbols provided by
          those libraries are provided by libsystemd.so.

        * The Capabilities= unit file setting has been removed (it is ignored
          for backwards compatibility). AmbientCapabilities= and
          CapabilityBoundingSet= should be used instead.

        * A new special target has been added, initrd-root-device.target,
          which creates a synchronization point for dependencies of the root
          device in early userspace. Initramfs builders must ensure that this
          target is now included in early userspace.

        Contributions from: Alban Crequy, Alexander Kuleshov, Alexander Shopov,
        Alex Crawford, Andre Klärner, Andrew Eikum, Beniamino Galvani, Benjamin
        Robin, Biao Lu, Bjørnar Ness, Calvin Owens, Christian Hesse, Clemens
        Gruber, Colin Guthrie, Daniel Drake, Daniele Medri, Daniel J Walsh,
        Daniel Mack, Dan Nicholson, daurnimator, David Herrmann, David
        R. Hedges, Elias Probst, Emmanuel Gil Peyrot, EMOziko, Evgeny
        Vereshchagin, Federico, Felipe Sateler, Filipe Brandenburger, Franck
        Bui, frankheckenbach, gdamjan, Georgia Brikis, Harald Hoyer, Hendrik
        Brueckner, Hristo Venev, Iago López Galeiras, Ian Kelling, Ismo
        Puustinen, Jakub Wilk, Jaroslav Škarvada, Jeff Huang, Joel Holdsworth,
        John Paul Adrian Glaubitz, Jonathan Boulle, kayrus, Klearchos
        Chaloulos, Kyle Russell, Lars Uebernickel, Lennart Poettering, Lubomir
        Rintel, Lukáš Nykrýn, Mantas Mikulėnas, Marcel Holtmann, Martin Pitt,
        Michael Biebl, michaelolbrich, Michał Bartoszkiewicz, Michal Koutný,
        Michal Sekletar, Mike Frysinger, Mike Gilbert, Mingcong Bai, Ming Lin,
        mulkieran, muzena, Nalin Dahyabhai, Naohiro Aota, Nathan McSween,
        Nicolas Braud-Santoni, Patrik Flykt, Peter Hutterer, Peter Mattern,
        Petr Lautrbach, Petros Angelatos, Piotr Drąg, Rabin Vincent, Robert
        Węcławski, Ronny Chevalier, Samuel Tardieu, Stefan Saraev, Stefan
        Schallenberg aka nafets227, Steven Siloti, Susant Sahani, Sylvain
        Plantefève, Taylor Smock, Tejun Heo, Thomas Blume, Thomas Haller,
        Thomas H. P. Andersen, Tobias Klauser, Tom Gundersen, topimiettinen,
        Torstein Husebø, Umut Tezduyar Lindskog, Uwe Kleine-König, Victor Toso,
        Vinay Kulkarni, Vito Caputo, Vittorio G (VittGam), Vladimir Panteleev,
        Wieland Hoffmann, Wouter Verhelst, Yu Watanabe, Zbigniew
        Jędrzejewski-Szmek

        — Fairfax, 2016-05-21

CHANGES WITH 229:

        * The systemd-resolved DNS resolver service has gained a substantial
          set of new features, most prominently it may now act as a DNSSEC
          validating stub resolver. DNSSEC mode is currently turned off by
          default, but is expected to be turned on by default in one of the
          next releases. For now, we invite everybody to test the DNSSEC logic
          by setting DNSSEC=allow-downgrade in /etc/systemd/resolved.conf. The
          service also gained a full set of D-Bus interfaces, including calls
          to configure DNS and DNSSEC settings per link (for use by external
          network management software). systemd-resolved and systemd-networkd
          now distinguish between "search" and "routing" domains. The former
          are used to qualify single-label names, the latter are used purely
          for routing lookups within certain domains to specific links.
          resolved now also synthesizes RRs for all entries from /etc/hosts.

        * The systemd-resolve tool (which is a client utility for
          systemd-resolved) has been improved considerably and is now fully
          supported and documented. Hence it has moved from /usr/lib/systemd to
          /usr/bin.

        * /dev/disk/by-path/ symlink support has been (re-)added for virtio
          devices.

        * The coredump collection logic has been reworked: when a coredump is
          collected it is now written to disk, compressed and processed
          (including stacktrace extraction) from a new instantiated service
          systemd-coredump@.service, instead of directly from the
          /proc/sys/kernel/core_pattern hook we provide. This is beneficial as
          processing large coredumps can take up a substantial amount of
          resources and time, and this previously happened entirely outside of
          systemd's service supervision. With the new logic the core_pattern
          hook only does minimal metadata collection before passing off control
          to the new instantiated service, which is configured with a time
          limit, a nice level and other settings to minimize negative impact on
          the rest of the system. Also note that the new logic will honour the
          RLIMIT_CORE setting of the crashed process, which now allows users
          and processes to turn off coredumping for their processes by setting
          this limit.

        * The RLIMIT_CORE resource limit now defaults to "unlimited" for PID 1
          and all forked processes by default. Previously, PID 1 would leave
          the setting at "0" for all processes, as set by the kernel. Note that
          the resource limit traditionally has no effect on the generated
          coredumps on the system if the /proc/sys/kernel/core_pattern hook
          logic is used. Since the limit is now honoured (see above) its
          default has been changed so that the coredumping logic is enabled by
          default for all processes, while allowing specific opt-out.

        * When the stacktrace is extracted from processes of system users, this
          is now done as "systemd-coredump" user, in order to sandbox this
          potentially security sensitive parsing operation. (Note that when
          processing coredumps of normal users this is done under the user ID
          of process that crashed, as before.) Packagers should take notice
          that it is now necessary to create the "systemd-coredump" system user
          and group at package installation time.

        * The systemd-activate socket activation testing tool gained support
          for SOCK_DGRAM and SOCK_SEQPACKET sockets using the new --datagram
          and --seqpacket switches. It also has been extended to support both
          new-style and inetd-style file descriptor passing. Use the new
          --inetd switch to request inetd-style file descriptor passing.

        * Most systemd tools now honor a new $SYSTEMD_COLORS environment
          variable, which takes a boolean value. If set to false, ANSI color
          output is disabled in the tools even when run on a terminal that
          supports it.

        * The VXLAN support in networkd now supports two new settings
          DestinationPort= and PortRange=.

        * A new systemd.machine_id= kernel command line switch has been added,
          that may be used to set the machine ID in /etc/machine-id if it is
          not initialized yet. This command line option has no effect if the
          file is already initialized.

        * systemd-nspawn gained a new --as-pid2 switch that invokes any
          specified command line as PID 2 rather than PID 1 in the
          container. In this mode PID 1 is a minimal stub init process that
          implements the special POSIX and Linux semantics of PID 1 regarding
          signal and child process management. Note that this stub init process
          is implemented in nspawn itself and requires no support from the
          container image. This new logic is useful to support running
          arbitrary commands in the container, as normal processes are
          generally not prepared to run as PID 1.

        * systemd-nspawn gained a new --chdir= switch for setting the current
          working directory for the process started in the container.

        * "journalctl /dev/sda" will now output all kernel log messages for
          specified device from the current boot, in addition to all devices
          that are parents of it. This should make log output about devices
          pretty useful, as long as kernel drivers attach enough metadata to
          the log messages. (The usual SATA drivers do.)

        * The sd-journal API gained two new calls
          sd_journal_has_runtime_files() and sd_journal_has_persistent_files()
          that report whether log data from /run or /var has been found.

        * journalctl gained a new switch "--fields" that prints all journal
          record field names currently in use in the journal.  This is backed
          by two new sd-journal API calls sd_journal_enumerate_fields() and
          sd_journal_restart_fields().

        * Most configurable timeouts in systemd now expect an argument of
          "infinity" to turn them off, instead of "0" as before. The semantics
          from now on is that a timeout of "0" means "now", and "infinity"
          means "never". To maintain backwards compatibility, "0" continues to
          turn off previously existing timeout settings.

        * "systemctl reload-or-try-restart" has been renamed to "systemctl
          try-reload-or-restart" to clarify what it actually does: the "try"
          logic applies to both reloading and restarting, not just restarting.
          The old name continues to be accepted for compatibility.

        * On boot-up, when PID 1 detects that the system clock is behind the
          release date of the systemd version in use, the clock is now set
          to the latter. Previously, this was already done in timesyncd, in order
          to avoid running with clocks set to the various clock epochs such as
          1902, 1938 or 1970. With this change the logic is now done in PID 1
          in addition to timesyncd during early boot-up, so that it is enforced
          before the first process is spawned by systemd. Note that the logic
          in timesyncd remains, as it is more comprehensive and ensures
          clock monotonicity by maintaining a persistent timestamp file in
          /var. Since /var is generally not available in earliest boot or the
          initrd, this part of the logic remains in timesyncd, and is not done
          by PID 1.

        * Support for tweaking details in net_cls.class_id through the
          NetClass= configuration directive has been removed, as the kernel
          people have decided to deprecate that controller in cgroup v2.
          Userspace tools such as nftables are moving over to setting rules
          that are specific to the full cgroup path of a task, which obsoletes
          these controllers anyway. The NetClass= directive is kept around for
          legacy compatibility reasons. For a more in-depth description of the
          kernel change, please refer to the respective upstream commit:

            https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=bd1060a1d671

        * A new service setting RuntimeMaxSec= has been added that may be used
          to specify a maximum runtime for a service. If the timeout is hit, the
          service is terminated and put into a failure state.

        * A new service setting AmbientCapabilities= has been added. It allows
          configuration of additional Linux process capabilities that are
          passed to the activated processes. This is only available on very
          recent kernels.

        * The process resource limit settings in service units may now be used
          to configure hard and soft limits individually.

        * The various libsystemd APIs such as sd-bus or sd-event now publicly
          expose support for gcc's __attribute__((cleanup())) C extension.
          Specifically, for many object destructor functions alternative
          versions have been added that have names suffixed with "p" and take a
          pointer to a pointer to the object to destroy, instead of just a
          pointer to the object itself. This is useful because these destructor
          functions may be used directly as parameters to the cleanup
          construct. Internally, systemd has been a heavy user of this GCC
          extension for a long time, and with this change similar support is
          now available to consumers of the library outside of systemd. Note
          that by using this extension in your sources compatibility with old
          and strictly ANSI compatible C compilers is lost. However, all gcc or
          LLVM versions of recent years support this extension.

        * Timer units gained support for a new setting RandomizedDelaySec= that
          allows configuring some additional randomized delay to the configured
          time. This is useful to spread out timer events to avoid load peaks in
          clusters or larger setups.

        * Calendar time specifications now support sub-second accuracy.

        * Socket units now support listening on SCTP and UDP-lite protocol
          sockets.

        * The sd-event API now comes with a full set of man pages.

        * Older versions of systemd contained experimental support for
          compressing journal files and coredumps with the LZ4 compressor that
          was not compatible with the lz4 binary (due to API limitations of the
          lz4 library). This support has been removed; only support for files
          compatible with the lz4 binary remains. This LZ4 logic is now
          officially supported and no longer considered experimental.

        * The dkr image import logic has been removed again from importd. dkr's
          micro-services focus doesn't fit into the machine image focus of
          importd, and quickly got out of date with the upstream dkr API.

        * Creation of the /run/lock/lockdev/ directory was dropped from
          tmpfiles.d/legacy.conf. Better locking mechanisms like flock() have
          been available for many years. If you still need this, you need to
          create your own tmpfiles.d config file with:

                  d /run/lock/lockdev 0775 root lock -

        * The settings StartLimitBurst=, StartLimitInterval=, StartLimitAction=
          and RebootArgument= have been moved from the [Service] section of
          unit files to [Unit], and they are now supported on all unit types,
          not just service units. Of course, elogind will continue to
          understand these settings also at the old location, in order to
          maintain compatibility.

        Contributions from: Abdo Roig-Maranges, Alban Crequy, Aleksander
        Adamowski, Alexander Kuleshov, Andreas Pokorny, Andrei Borzenkov,
        Andrew Wilcox, Arthur Clement, Beniamino Galvani, Casey Schaufler,
        Chris Atkinson, Chris Mayo, Christian Hesse, Damjan Georgievski, Dan
        Dedrick, Daniele Medri, Daniel J Walsh, Daniel Korostil, Daniel Mack,
        David Herrmann, Dimitri John Ledkov, Dominik Hannen, Douglas Christman,
        Evgeny Vereshchagin, Filipe Brandenburger, Franck Bui, Gabor Kelemen,
        Harald Hoyer, Hayden Walles, Helmut Grohne, Henrik Kaare Poulsen,
        Hristo Venev, Hui Wang, Indrajit Raychaudhuri, Ismo Puustinen, Jakub
        Wilk, Jan Alexander Steffens (heftig), Jan Engelhardt, Jan Synacek,
        Joost Bremmer, Jorgen Schaefer, Karel Zak, Klearchos Chaloulos,
        lc85446, Lennart Poettering, Lukas Nykryn, Mantas Mikulėnas, Marcel
        Holtmann, Martin Pitt, Michael Biebl, Michael Olbrich, Michael Scherer,
        Michał Górny, Michal Sekletar, Nicolas Cornu, Nicolas Iooss, Nils
        Carlson, nmartensen, nnz1024, Patrick Ohly, Peter Hutterer, Phillip Sz,
        Ronny Chevalier, Samu Kallio, Shawn Landden, Stef Walter, Susant
        Sahani, Sylvain Plantefève, Tadej Janež, Thomas Hindoe Paaboel
        Andersen, Tom Gundersen, Torstein Husebø, Umut Tezduyar Lindskog, Vito
        Caputo, WaLyong Cho, Yu Watanabe, Zbigniew Jędrzejewski-Szmek

        — Berlin, 2016-02-11

CHANGES WITH 228:

        * A number of properties previously only settable in unit
          files are now also available as properties to set when
          creating transient units programmatically via the bus, as it
          is exposed with systemd-run's --property=
          setting. Specifically, these are: SyslogIdentifier=,
          SyslogLevelPrefix=, TimerSlackNSec=, OOMScoreAdjust=,
          EnvironmentFile=, ReadWriteDirectories=,
          ReadOnlyDirectories=, InaccessibleDirectories=,
          ProtectSystem=, ProtectHome=, RuntimeDirectory=.

        * When creating transient services via the bus API it is now
          possible to pass in a set of file descriptors to use as
          STDIN/STDOUT/STDERR for the invoked process.

        * Slice units may now be created transiently via the bus APIs,
          similar to the way service and scope units may already be
          created transiently.

        * Wherever systemd expects a calendar timestamp specification
          (like in journalctl's --since= and --until= switches) UTC
          timestamps are now supported. Timestamps suffixed with "UTC"
          are now considered to be in Universal Time Coordinated
          instead of the local timezone. Also, timestamps may now
          optionally be specified with sub-second accuracy. Both of
          these additions also apply to recurring calendar event
          specification, such as OnCalendar= in timer units.

        * journalctl gained a new "--sync" switch that asks the
          journal daemon to write all so far unwritten log messages to
          disk and sync the files, before returning.

        * systemd-tmpfiles learned two new line types "q" and "Q" that
          operate like "v", but also set up a basic btrfs quota
          hierarchy when used on a btrfs file system with quota
          enabled.

        * tmpfiles' "v", "q" and "Q" will now create a plain directory
          instead of a subvolume (even on a btrfs file system) if the
          root directory is a plain directory, and not a
          subvolume. This should simplify things with certain chroot()
          environments which are not aware of the concept of btrfs
          subvolumes.

        * systemd-detect-virt gained a new --chroot switch to detect
          whether execution takes place in a chroot() environment.

        * CPUAffinity= now takes CPU index ranges in addition to
          individual indexes.

        * The various memory-related resource limit settings (such as
          LimitAS=) now understand the usual K, M, G, ... suffixes to
          the base of 1024 (IEC). Similar, the time-related resource
          limit settings understand the usual min, h, day, ...
          suffixes now.

        * There's a new system.conf setting DefaultTasksMax= to
          control the default TasksMax= setting for services and
          scopes running on the system. (TasksMax= is the primary
          setting that exposes the "pids" cgroup controller on systemd
          and was introduced in the previous systemd release.) The
          setting now defaults to 512, which means services that are
          not explicitly configured otherwise will only be able to
          create 512 processes or threads at maximum, from this
          version on. Note that this means that thread- or
          process-heavy services might need to be reconfigured to set
          TasksMax= to a higher value. It is sufficient to set
          TasksMax= in these specific unit files to a higher value, or
          even "infinity". Similar, there's now a logind.conf setting
          UserTasksMax= that defaults to 4096 and limits the total
          number of processes or tasks each user may own
          concurrently. nspawn containers also have the TasksMax=
          value set by default now, to 8192. Note that all of this
          only has an effect if the "pids" cgroup controller is
          enabled in the kernel. The general benefit of these changes
          should be a more robust and safer system, that provides a
          certain amount of per-service fork() bomb protection.

        * systemd-nspawn gained the new --network-veth-extra= switch
          to define additional and arbitrarily-named virtual Ethernet
          links between the host and the container.

        * A new service execution setting PassEnvironment= has been
          added that allows importing select environment variables
          from PID1's environment block into the environment block of
          the service.

        * Timer units gained support for a new RemainAfterElapse=
          setting which takes a boolean argument. It defaults to on,
          exposing behaviour unchanged to previous releases. If set to
          off, timer units are unloaded after they elapsed if they
          cannot elapse again. This is particularly useful for
          transient timer units, which shall not stay around longer
          than until they first elapse.

        * systemd will now bump the net.unix.max_dgram_qlen to 512 by
          default now (the kernel default is 16). This is beneficial
          for avoiding blocking on AF_UNIX/SOCK_DGRAM sockets since it
          allows substantially larger numbers of queued
          datagrams. This should increase the capability of systemd to
          parallelize boot-up, as logging and sd_notify() are unlikely
          to stall execution anymore. If you need to change the value
          from the new defaults, use the usual sysctl.d/ snippets.

        * The compression framing format used by the journal or
          coredump processing has changed to be in line with what the
          official LZ4 tools generate. LZ4 compression support in
          systemd was considered unsupported previously, as the format
          was not compatible with the normal tools. With this release
          this has changed now, and it is hence safe for downstream
          distributions to turn it on. While not compressing as well
          as the XZ, LZ4 is substantially faster, which makes
          it a good default choice for the compression logic in the
          journal and in coredump handling.

        * Any reference to /etc/mtab has been dropped from
          systemd. The file has been obsolete since a while, but
          systemd refused to work on systems where it was incorrectly
          set up (it should be a symlink or non-existent). Please make
          sure to update to util-linux 2.27.1 or newer in conjunction
          with this systemd release, which also drops any reference to
          /etc/mtab. If you maintain a distribution make sure that no
          software you package still references it, as this is a
          likely source of bugs. There's also a glibc bug pending,
          asking for removal of any reference to this obsolete file:

          https://sourceware.org/bugzilla/show_bug.cgi?id=19108

          Note that only util-linux versions built with
          --enable-libmount-force-mountinfo are supported.

        * Support for the ".snapshot" unit type has been removed. This
          feature turned out to be little useful and little used, and
          has now been removed from the core and from systemctl.

        * The dependency types RequiresOverridable= and
          RequisiteOverridable= have been removed from systemd. They
          have been used only very sparingly to our knowledge and
          other options that provide a similar effect (such as
          systemctl --mode=ignore-dependencies) are much more useful
          and commonly used. Moreover, they were only half-way
          implemented as the option to control behaviour regarding
          these dependencies was never added to systemctl. By removing
          these dependency types the execution engine becomes a bit
          simpler. Unit files that use these dependencies should be
          changed to use the non-Overridable dependency types
          instead. In fact, when parsing unit files with these
          options, that's what systemd will automatically convert them
          too, but it will also warn, asking users to fix the unit
          files accordingly. Removal of these dependency types should
          only affect a negligible number of unit files in the wild.

        * Behaviour of networkd's IPForward= option changed
          (again). It will no longer maintain a per-interface setting,
          but propagate one way from interfaces where this is enabled
          to the global kernel setting. The global setting will be
          enabled when requested by a network that is set up, but
          never be disabled again. This change was made to make sure
          IPv4 and IPv6 behaviour regarding packet forwarding is
          similar (as the Linux IPv6 stack does not support
          per-interface control of this setting) and to minimize
          surprises.

        * In unit files the behaviour of %u, %U, %h, %s has
          changed. These specifiers will now unconditionally resolve
          to the various user database fields of the user that the
          systemd instance is running as, instead of the user
          configured in the specific unit via User=. Note that this
          effectively doesn't change much, as resolving of these
          specifiers was already turned off in the --system instance
          of systemd, as we cannot do NSS lookups from PID 1. In the
          --user instance of systemd these specifiers where correctly
          resolved, but hardly made any sense, since the user instance
          lacks privileges to do user switches anyway, and User= is
          hence useless. Moreover, even in the --user instance of
          systemd behaviour was awkward as it would only take settings
          from User= assignment placed before the specifier into
          account. In order to unify and simplify the logic around
          this the specifiers will now always resolve to the
          credentials of the user invoking the manager (which in case
          of PID 1 is the root user).

        Contributions from: Andrew Jones, Beniamino Galvani, Boyuan
        Yang, Daniel Machon, Daniel Mack, David Herrmann, David
        Reynolds, David Strauss, Dongsu Park, Evgeny Vereshchagin,
        Felipe Sateler, Filipe Brandenburger, Franck Bui, Hristo
        Venev, Iago López Galeiras, Jan Engelhardt, Jan Janssen, Jan
        Synacek, Jesus Ornelas Aguayo, Karel Zak, kayrus, Kay Sievers,
        Lennart Poettering, Liu Yuan Yuan, Mantas Mikulėnas, Marcel
        Holtmann, Marcin Bachry, Marcos Alano, Marcos Mello, Mark
        Theunissen, Martin Pitt, Michael Marineau, Michael Olbrich,
        Michal Schmidt, Michal Sekletar, Mirco Tischler, Nick Owens,
        Nicolas Cornu, Patrik Flykt, Peter Hutterer, reverendhomer,
        Ronny Chevalier, Sangjung Woo, Seong-ho Cho, Shawn Landden,
        Susant Sahani, Thomas Haller, Thomas Hindoe Paaboel Andersen,
        Tom Gundersen, Torstein Husebø, Vito Caputo, Zbigniew
        Jędrzejewski-Szmek

        — Berlin, 2015-11-18

CHANGES WITH 227:

        * systemd now depends on util-linux v2.27. More specifically,
          the newly added mount monitor feature in libmount now
          replaces systemd's former own implementation.

        * libmount mandates /etc/mtab not to be regular file, and
          systemd now enforces this condition at early boot.
          /etc/mtab has been deprecated and warned about for a very
          long time, so systems running systemd should already have
          stopped having this file around as anything else than a
          symlink to /proc/self/mounts.

        * Support for the "pids" cgroup controller has been added.  It
          allows accounting the number of tasks in a cgroup and
          enforcing limits on it. This adds two new setting
          TasksAccounting= and TasksMax= to each unit, as well as a
          global option DefaultTasksAccounting=.

        * Support for the "net_cls" cgroup controller has been added.
          It allows assigning a net class ID to each task in the
          cgroup, which can then be used in firewall rules and traffic
          shaping configurations. Note that the kernel netfilter net
          class code does not currently work reliably for ingress
          packets on unestablished sockets.

          This adds a new config directive called NetClass= to CGroup
          enabled units. Allowed values are positive numbers for fixed
          assignments and "auto" for picking a free value
          automatically.

        * 'systemctl is-system-running' now returns 'offline' if the
          system is not booted with systemd. This command can now be
          used as a substitute for 'systemd-notify --booted'.

        * Watchdog timeouts have been increased to 3 minutes for all
          in-tree service files. Apparently, disk IO issues are more
          frequent than we hoped, and user reported >1 minute waiting
          for disk IO.

        * 'machine-id-commit' functionality has been merged into
          'machine-id-setup --commit'. The separate binary has been
          removed.

        * The WorkingDirectory= directive in unit files may now be set
          to the special value '~'. In this case, the working
          directory is set to the home directory of the user
          configured in User=.

        * "machinectl shell" will now open the shell in the home
          directory of the selected user by default.

        * The CrashChVT= configuration file setting is renamed to
          CrashChangeVT=, following our usual logic of not
          abbreviating unnecessarily. The old directive is still
          supported for compat reasons. Also, this directive now takes
          an integer value between 1 and 63, or a boolean value. The
          formerly supported '-1' value for disabling stays around for
          compat reasons.

        * The PrivateTmp=, PrivateDevices=, PrivateNetwork=,
          NoNewPrivileges=, TTYPath=, WorkingDirectory= and
          RootDirectory= properties can now be set for transient
          units.

        * The systemd-analyze tool gained a new "set-log-target" verb
          to change the logging target the system manager logs to
          dynamically during runtime. This is similar to how
          "systemd-analyze set-log-level" already changes the log
          level.

        * In nspawn /sys is now mounted as tmpfs, with only a selected
          set of subdirectories mounted in from the real sysfs. This
          enhances security slightly, and is useful for ensuring user
          namespaces work correctly.

        * Support for USB FunctionFS activation has been added. This
          allows implementation of USB gadget services that are
          activated as soon as they are requested, so that they don't
          have to run continuously, similar to classic socket
          activation.

        * The "systemctl exit" command now optionally takes an
          additional parameter that sets the exit code to return from
          the systemd manager when exiting. This is only relevant when
          running the systemd user instance, or when running the
          system instance in a container.

        * sd-bus gained the new API calls sd_bus_path_encode_many()
          and sd_bus_path_decode_many() that allow easy encoding and
          decoding of multiple identifier strings inside a D-Bus
          object path. Another new call sd_bus_default_flush_close()
          has been added to flush and close per-thread default
          connections.

        * systemd-cgtop gained support for a -M/--machine= switch to
          show the control groups within a certain container only.

        * "systemctl kill" gained support for an optional --fail
          switch. If specified the requested operation will fail of no
          processes have been killed, because the unit had no
          processes attached, or similar.

        * A new systemd.crash_reboot=1 kernel command line option has
          been added that triggers a reboot after crashing. This can
          also be set through CrashReboot= in systemd.conf.

        * The RuntimeDirectory= setting now understands unit
          specifiers like %i or %f.

        * A new (still internal) library API sd-ipv4acd has been added,
          that implements address conflict detection for IPv4. It's
          based on code from sd-ipv4ll, and will be useful for
          detecting DHCP address conflicts.

        * File descriptors passed during socket activation may now be
          named. A new API sd_listen_fds_with_names() is added to
          access the names.  The default names may be overridden,
          either in the .socket file using the FileDescriptorName=
          parameter, or by passing FDNAME= when storing the file
          descriptors using sd_notify().

        * systemd-networkd gained support for:

            - Setting the IPv6 Router Advertisement settings via
              IPv6AcceptRouterAdvertisements= in .network files.

            - Configuring the HelloTimeSec=, MaxAgeSec= and
              ForwardDelaySec= bridge parameters in .netdev files.

            - Configuring PreferredSource= for static routes in
              .network files.

        * The "ask-password" framework used to query for LUKS harddisk
          passwords or SSL passwords during boot gained support for
          caching passwords in the kernel keyring, if it is
          available. This makes sure that the user only has to type in
          a passphrase once if there are multiple objects to unlock
          with the same one. Previously, such password caching was
          available only when Plymouth was used; this moves the
          caching logic into the systemd codebase itself. The
          "systemd-ask-password" utility gained a new --keyname=
          switch to control which kernel keyring key to use for
          caching a password in. This functionality is also useful for
          enabling display managers such as gdm to automatically
          unlock the user's GNOME keyring if its passphrase, the
          user's password and the harddisk password are the same, if
          gdm-autologin is used.

        * When downloading tar or raw images using "machinectl
          pull-tar" or "machinectl pull-raw", a matching ".nspawn"
          file is now also downloaded, if it is available and stored
          next to the image file.

        * Units of type ".socket" gained a new boolean setting
          Writable= which is only useful in conjunction with
          ListenSpecial=. If true, enables opening the specified
          special file in O_RDWR mode rather than O_RDONLY mode.

        * systemd-rfkill has been reworked to become a singleton
          service that is activated through /dev/rfkill on each rfkill
          state change and saves the settings to disk. This way,
          systemd-rfkill is now compatible with devices that exist
          only intermittendly, and even restores state if the previous
          system shutdown was abrupt rather than clean.

        * The journal daemon gained support for vacuuming old journal
          files controlled by the number of files that shall remain,
          in addition to the already existing control by size and by
          date. This is useful as journal interleaving performance
          degrades with too many separate journal files, and allows
          putting an effective limit on them. The new setting defaults
          to 100, but this may be changed by setting SystemMaxFiles=
          and RuntimeMaxFiles= in journald.conf. Also, the
          "journalctl" tool gained the new --vacuum-files= switch to
          manually vacuum journal files to leave only the specified
          number of files in place.

        * udev will now create /dev/disk/by-path links for ATA devices
          on kernels where that is supported.

        * Galician, Serbian, Turkish and Korean translations were added.

        Contributions from: Aaro Koskinen, Alban Crequy, Beniamino
        Galvani, Benjamin Robin, Branislav Blaskovic, Chen-Han Hsiao
        (Stanley), Daniel Buch, Daniel Machon, Daniel Mack, David
        Herrmann, David Milburn, doubleodoug, Evgeny Vereshchagin,
        Felipe Franciosi, Filipe Brandenburger, Fran Dieguez, Gabriel
        de Perthuis, Georg Müller, Hans de Goede, Hendrik Brueckner,
        Ivan Shapovalov, Jacob Keller, Jan Engelhardt, Jan Janssen,
        Jan Synacek, Jens Kuske, Karel Zak, Kay Sievers, Krzesimir
        Nowak, Krzysztof Kotlenga, Lars Uebernickel, Lennart
        Poettering, Lukas Nykryn, Łukasz Stelmach, Maciej Wereski,
        Marcel Holtmann, Marius Thesing, Martin Pitt, Michael Biebl,
        Michael Gebetsroither, Michal Schmidt, Michal Sekletar, Mike
        Gilbert, Muhammet Kara, nazgul77, Nicolas Cornu, NoXPhasma,
        Olof Johansson, Patrik Flykt, Pawel Szewczyk, reverendhomer,
        Ronny Chevalier, Sangjung Woo, Seong-ho Cho, Susant Sahani,
        Sylvain Plantefève, Thomas Haller, Thomas Hindoe Paaboel
        Andersen, Tom Gundersen, Tom Lyon, Viktar Vauchkevich,
        Zbigniew Jędrzejewski-Szmek, Марко М. Костић

        — Berlin, 2015-10-07

CHANGES WITH 226:

        * The DHCP implementation of systemd-networkd gained a set of
          new features:

          - The DHCP server now supports emitting DNS and NTP
            information. It may be enabled and configured via
            EmitDNS=, DNS=, EmitNTP=, and NTP=. If transmission of DNS
            and NTP information is enabled, but no servers are
            configured, the corresponding uplink information (if there
            is any) is propagated.

          - Server and client now support transmission and reception
            of timezone information. It can be configured via the
            newly introduced network options UseTimezone=,
            EmitTimezone=, and Timezone=.  Transmission of timezone
            information is enabled between host and containers by
            default now: the container will change its local timezone
            to what the host has set.

          - Lease timeouts can now be configured via
            MaxLeaseTimeSec= and DefaultLeaseTimeSec=.

          - The DHCP server improved on the stability of
            leases. Clients are more likely to get the same lease
            information back, even if the server loses state.

          - The DHCP server supports two new configuration options to
            control the lease address pool metrics, PoolOffset= and
            PoolSize=.

        * The encapsulation limit of tunnels in systemd-networkd may
          now be configured via 'EncapsulationLimit='. It allows
          modifying the maximum additional levels of encapsulation
          that are permitted to be prepended to a packet.

        * systemd now supports the concept of user buses replacing
          session buses, if used with dbus-1.10 (and enabled via dbus
          --enable-user-session). It previously only supported this on
          kdbus-enabled systems, and this release expands this to
          'dbus-daemon' systems.

        * systemd-networkd now supports predictable interface names
          for virtio devices.

        * systemd now optionally supports the new Linux kernel
          "unified" control group hierarchy. If enabled via the kernel
          command-line option 'systemd.unified_cgroup_hierarchy=1',
          systemd will try to mount the unified cgroup hierarchy
          directly on /sys/fs/cgroup. If not enabled, or not
          available, systemd will fall back to the legacy cgroup
          hierarchy setup, as before. Host system and containers can
          mix and match legacy and unified hierarchies as they
          wish. nspawn understands the $UNIFIED_CGROUP_HIERARCHY
          environment variable to individually select the hierarchy to