Systemd 251-rc1 Released With Experimental systemd-sysupdate Tool

Written by Michael Larabel in systemd on 30 March 2022 at 12:00 AM EDT. 59 Comments
The first release candidate of systemd 251 is now available for testing as a rather large update to this Linux init system and service manager.

Systemd 251 has been building up dozens of prominent changes. Some of the key changes to find with systemd 251-rc1 include:

- A new component "systemd-sysupdate" has been added that automatically discovers / downloads / installs A/B style updates for the host installation itself or container images / portable service images. Systemd-sysupdate is currently considered experimental. This OS updating tool has been worked on by Red Hat / systemd developers going back to last summer.

- Like Linux 5.18, systemd 251 changes the default C standard version to C11 with GNU extensions (GNU11) though their public API headers have been limited still to C89.

- All kernels supported by systemd will now mix the RdRand instruction output (or other CPU random ISA extensions) into the entropy pool at early boot. This will mean even if /dev/urandom is not initialized, it will still return bytes that had at least as of high quality as RdRand. In turn, systemd no longer needs to invoke RdRand directly itself. RdRand usage by systemd in the past has been prone to bugs.

- Various improvements to the Boot Loader Specification and various kernel-install improvements.

- A new set of service monitor environment variables are passed to the OnFailure/OnSuccess handlers.

- Units that were killed by systemd-oomd will now have a service result of oom-kill.

- Enabling more service settings to now also work with unprivileged user services.

- bustctl now uses the pcapng format for output rather than pcap.

- New hardware database (HWDB) files for handheld devices annd A/V production devices.

- systemd-networkd .netdev files can now be used to create virtual WLAN devices.

- systemd-resolved will now start earlier in the boot process.

More details on Tuesday's systemd 251-rc1 release via GitHub.
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