[systemd-devel] howto migrate some things to systemd

[Mirco Tischler]

Hi
2011/4/17 Michael Olbrich <m.olbrich at pengutronix.de>:
> Hi,
>
> I'm trying to migrate some stuff to systemd, but I have some problems
> getting it right.
> The scenario:
> I'm cross-building root file systems. I try to do as much as possible
> on the host system, but there is some stuff that needs to run on the target
> when booting for the first time. I'm not sure how to integrate this with
> systemd.
> Some of the issues I have:
> - With a classic init, the init-script just touches a file to indicate the
>  one-time stuff is complete. Is there a better way for this with systemd?
How about pointing the default.target symlink at your custom unit that
pulls in only
a very basic system and executes your custom setup script.
And when you're done link default.target back to
multi-user.target or whatever unit you want to start as a default and then
reboot, or if you're brave call systemctl isolate default.target.
>
> - The system usually runs with a read-only mounted rootfs. I remount it
>  temporarily for the one-time stuff. However this confuses other services
>  that run at the same time.
>  I'm not sure what's the best solution for this.
>
> - One of the task is prelinking the whole system. This means all programs
>  and libraries are modified, so nothing else should be running. And
>  systemd must be restarted before the rootfs can be mounted read-only.
>  Again I have no idea how to do this.
>
> Any hints on how to do this?
>
> Regards,
> Michael Olbrich
You would end up with only a very basic system so there should be no confused
services or anything that cares if you remount the rootfs rw or
prelink some files.

However, this just popped into my head when reading your mail and I'm probably
missing something...

Mirco