Systemd 254 released and now has a new soft-reboot option:

    * A new "soft-reboot" mechanism has been added to the service manager.
      A "soft reboot" is similar to a regular reboot, except that it
      affects userspace only: the service manager shuts down any running
      services and other units, then optionally switches into a new root
      file system (mounted to /run/nextroot/), and then passes control to a
      systemd instance in the new file system which then starts the system
      up again. The kernel is not rebooted and neither is the hardware,
      firmware or boot loader. This provides a fast, lightweight mechanism
      to quickly reset or update userspace, without the latency that a full
      system reset involves. Moreover, open file descriptors may be passed
      across the soft reboot into the new system where they will be passed
      back to the originating services. This allows pinning resources
      across the reboot, thus minimizing grey-out time further. This new
      reboot mechanism is accessible via the new "systemctl soft-reboot"
      command.>
  • throwawayish
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    1 year ago

    Hard-reboots are no longer required on Silverblue when installing or upgrading packages (besides kernel) through rpm-ostree. Arguably one should only sparingly rely on rpm-ostree for installing packages. But it’s great to have access to soft-reboot when setting up a new system.