A new systemd ☠️ pre-release ☠️ has just been tagged. Please download the
tarball here:
https://github.com/systemd/systemd/archive/v255-rc4.tar.gz
NOTE: This is ☠️ pre-release ☠️ software. Do not run this on production
systems, but please test this and report any issues you find to GitHub:
https://github.com/systemd/systemd/issues/new?template=Bug_report.md
Changes since the previous release:
Announcements of Future Feature Removals and Incompatible Changes:
* Support for split-usr (/usr/ mounted separately during late boot,
instead of being mounted by the initrd before switching to the rootfs)
and unmerged-usr (parallel directories /bin/ and /usr/bin/, /lib/ and
/usr/lib/, …) has been removed. For more details, see:
https://lists.freedesktop.org/archives/systemd-devel/2022-September/048352.html
* We intend to remove cgroup v1 support from a systemd release after
the end of 2023. If you run services that make explicit use of
cgroup v1 features (i.e. the "legacy hierarchy" with separate
hierarchies for each controller), please implement compatibility with
cgroup v2 (i.e. the "unified hierarchy") sooner rather than later.
Most of Linux userspace has been ported over already.
* Support for System V service scripts is now deprecated and will be
removed in a future release. Please make sure to update your software
*now* to include a native systemd unit file instead of a legacy
System V script to retain compatibility with future systemd releases.
* Support for the SystemdOptions EFI variable is deprecated.
'bootctl systemd-efi-options' will emit a warning when used. It seems
that this feature is little-used and it is better to use alternative
approaches like credentials and confexts. The plan is to drop support
altogether at a later point, but this might be revisited based on
user feedback.
* systemd-run's switch --expand-environment= which currently is disabled
by default when combined with --scope, will be changed in a future
release to be enabled by default.
* "systemctl switch-root" is now restricted to initrd transitions only.
Transitions between real systems should be done with
"systemctl soft-reboot" instead.
* The "ip=off" and "ip=none" kernel command line options interpreted by
systemd-network-generator will now result in IPv6RA + link-local
addressing being disabled, too. Previously DHCP was turned off, but
IPv6RA and IPv6 link-local addressing was left enabled.
* The NAMING_BRIDGE_MULTIFUNCTION_SLOT naming scheme has been deprecated
and is now disabled.
* SuspendMode=, HibernateState= and HybridSleepState= in the [Sleep]
section of systemd-sleep.conf are now deprecated and have no effect.
They did not (and could not) take any value other than the respective
default. HybridSleepMode= is also deprecated, and will now always use
the 'suspend' disk mode.
Service Manager:
* The way services are spawned has been overhauled. Previously, a
process was forked that shared all of the manager's memory (via
copy-on-write) while doing all the required setup (e.g.: mount
namespaces, CGroup configuration, etc.) before exec'ing the target
executable. This was problematic for various reasons: several glibc
APIs were called that are not supposed to be used after a fork but
before an exec, copy-on-write meant that if either process (the
manager or the child) touched a memory page a copy was triggered, and
also the memory footprint of the child process was that of the
manager, but with the memory limits of the service. From this version
onward, the new process is spawned using CLONE_VM and CLONE_VFORK
semantics via posix_spawn(3), and it immediately execs a new internal
binary, systemd-executor, that receives the configuration to apply
via memfd, and sets up the process before exec'ing the target
executable. The systemd-executor binary is pinned by file descriptor
by each manager instance (system and users), and the reference is
updated on daemon-reexec - it is thus important to reexec all running
manager instances when the systemd-executor and/or libsystemd*
libraries are updated on the filesystem.
* Most of the internal process tracking is being changed to use PIDFDs
instead of PIDs when the kernel supports it, to improve robustness
and reliability.
* A new option SurviveFinalKillSignal= can be used to configure the
unit to be skipped in the final SIGTERM/SIGKILL spree on shutdown.
