Merge db50a2b55c into f6793bbcf0

Note that journal sockets have to be mounted for softreboot surviving units,
as per thread on the ML, otherwise logging does not work afterwards:

https://lists.freedesktop.org/archives/systemd-devel/2024-June/050382.html

Remove the oneshot, as it didn't actually make sense for a sleep infinity.
And run in a separate image, to showcase that the unit should really be
disconnected from the rootfs.

man/systemd-soft-reboot.service.xml

@@ -106,7 +106,10 @@
       normal shutdown, reboot and maintenance mode. Finally, they have to be ordered after
       <constant>basic.target</constant> to ensure correct ordering on boot. Note that in case any new or
       custom units are used to isolate to, or that implement an equivalent shutdown functionality, they will
-      also have to be configured manually for correct ordering and conflicting. For example:</para>
+      also have to be configured manually for correct ordering and conflicting. In addition, to ensure the
+      service is disconnected from the rootfs resources (see next paragraph), it should run from a separate
+      image, but with the journal sockets mounted so that it is still allowed to log to the system journal.
+      For example:</para>
 
       <programlisting>[Unit]
 Description=My Surviving Service
@@ -118,7 +121,9 @@ Conflicts=reboot.target kexec.target poweroff.target halt.target rescue.target e
 Before=shutdown.target rescue.target emergency.target
 
 [Service]
-Type=oneshot
+RootImage=/var/lib/root.raw
+TemporaryFileSystem=/run
+BindReadOnlyPaths=/run/systemd/journal/socket /run/systemd/journal/stdout
 ExecStart=sleep infinity</programlisting>
       </listitem>