[packagekit] Question about offline update process

[lordofgame]

Hi,

this is a question that has been bothering me for some time, that I
finally wanted to ask. The current process of offline updates goes
something like this:

1) Reboot the system into "offline update mode"
2) Install updates
3) Reboot system into default mode again

But wouldn't it be more efficient if in step 1) it just changes the
runlevel to "offline update mode"? Like, do a "systemctl isolate
offline-update.target" (or whatever the target is named). In this case
systemd would shutdown almost all system services and it would be just
as good as a reboot.
Under certain circumstances you could even omit the second reboot, for
example if the kernel wasn't updated. Systemd itself has the
daemon-reexec command which supposedly reexecs PID 1, so it would be
enough to execute that command.

Maybe there is something I'm missing. It would be greatly appreciated,
if somebody could take the time to explain this to me.

Cheers,
Björn