[systemd-devel] [ANNOUNCE] systemd v226

David Herrmann dh.herrmann at gmail.com
Tue Sep 8 06:32:44 PDT 2015


Here's the next version of systemd, v226:


As usual, many bug-fixes and cleanups, but also a rather large set of
new features this time, including support for unified cgroups, many
DHCP improvements, extensions to the polkit integration, nspawn
configuration files, and many more.

Thanks to everyone who contributed to this release!


        * 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

        * 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_CROUP_HIERARCHY
          environment variable to individually select the hierarchy to
          use for executed containers. By default, nspawn will use the
          unified hierarchy for the containers if the host uses the
          unified hierarchy, and the legacy hierarchy otherwise.
          Please note that at this point the unified hierarchy is an
          experimental kernel feature and is likely to change in one
          of the next kernel releases.  Therefore, it should not be
          enabled by default in downstream distributions yet. The
          minimum required kernel version for the unified hierarchy to
          work is 4.2. Note that when the unified hierarchy is used
          for the first time delegated access to controllers is
          safe. Because of this systemd-nspawn containers will get
          access to controllers now, as will systemd user
          sessions. This means containers and user sessions may now
          manage their own resources, partitioning up what the system
          grants them.

        * A new special scope unit "init.scope" has been introduced
          that encapsulates PID 1 of the system. It may be used to
          determine resource usage and enforce resource limits on PID
          1 itself. PID 1 hence moved out of the root of the control
          group tree.

        * The cgtop tool gained support for filtering out kernel
          threads when counting tasks in a control group. Also, the
          count of processes is now recursively summed up by
          default. Two options -k and --recursive= have been added to
          revert to old behaviour. The tool has also been updated to
          work correctly in containers now.

        * systemd-nspawn's --bind= and --bind-ro= options have been
          extended to allow creation of non-recursive bind mounts.

        * libsystemd gained two new calls sd_pid_get_cgroup() and
          sd_peer_get_cgroup() which return the control group path of
          a process or peer of a connected AF_UNIX socket. This
          function call is particularly useful when implementing
          delegated subtrees support in the control group hierarchy.

        * The "sd-event" event loop API of libsystemd now supports
          correct dequeuing of real-time signals, without losing
          signal events.

        * When systemd requests a PolicyKit decision when managing
          units it will now add additional fields to the request,
          including unit name and desired operation. This enables more
          powerful PolicyKit policies, that make decisions depending
          on these parameters.

        * nspawn learnt support for .nspawn settings files, that may
          accompany the image files or directories of containers, and
          may contain additional settings for the container. This is
          an alternative to configuring container parameters via the
          nspawn command line.

        Contributions from: Cristian Rodríguez, Daniel Mack, David
        Herrmann, Eugene Yakubovich, Evgeny Vereshchagin, Filipe
        Brandenburger, Hans de Goede, Jan Alexander Steffens, Jan
        Synacek, Kay Sievers, Lennart Poettering, Mangix, Marcel
        Holtmann, Martin Pitt, Michael Biebl, Michael Chapman, Michal
        Sekletar, Peter Hutterer, Piotr Drąg, reverendhomer, Robin
        Hack, Susant Sahani, Sylvain Pasche, Thomas Hindoe Paaboel
        Andersen, Tom Gundersen, Torstein Husebø

        -- Berlin, 2015-09-08

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