[systemd-devel] Implementing resume from hibernation as a systemd unit file

Lennart Poettering lennart at poettering.net
Fri Aug 15 02:32:59 PDT 2014

On Fri, 15.08.14 13:02, Ivan Shapovalov (intelfx100 at gmail.com) wrote:

Ah, well, if the resume= switch is supposed to simply carry the finished
device node path, and nothing we still have to translate into one, then
of course the entire udev rules step is unnecessary, and you can just
write this out directly from the generator.

> > > Actually, the main question is how to order the resume unit. It needs to run
> > > before any real filesystems are mounted (speaking in terms of initrd) AND before
> > > rootfs is remounted read-write (speaking in terms of initrd-less system), but
> > > after whatever is needed to make the device node appear.
> > 
> > You could turn this into a generator, that pulls the switch from the
> > kernel cmdline, and generates a service that orders itself before
> > local-fs-pre.taret and after the device you need. The device you need
> > you give a stable name via an udev rule. 
> So is "Before=local-fs-pre.target" a sufficient ordering for such resume unit?
> Again, the resume unit must be started before any filesystems are (re)mounted
> read-write, either from initrd or not.

Yes. That should be enough.

> Seems like there's at least systemd-remount-fs.service that also needs to be
> taken into account...

That only runs after the transition into the host OS.


Lennart Poettering, Red Hat

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