Doing kexec reboot right in systemd

[Marti Raudsepp]

On Mon, Mar 26, 2012 at 21:07, Lennart Poettering
<lennart at poettering.net> wrote:
> Marti, sorry for changing my mind on this: would be great if you could
> prep a patch for this for systemd itself.

D'oh, I already prepared a patch for kexec, although I haven't sent it out yet.

> Hmm, so since this would then belong in the shutdown path of systemd,
> and only be added for the kexec shutdown path I actually think it would
> make more sense to add this into systemd itself instead of kexec-tools,
> to ensure the right ordering.

Um, why is including in systemd necessary for guaranteeing order?
Seems like this should do it...

[Unit]
DefaultDependencies=no
Before=shutdown.target umount.target final.target
[Install]
WantedBy=kexec.target

> I'd like to keep kexec.target different from reboot.target by
> default, so that people have both options available.

Fair enough.

> a) we introduce kexec-load.service which is always in the kexec.target
>   shutdown path, never in reboot.target. Doesn't need to be enabled.
>
> b) kexec-load.service becomes a NOP if a kernel is already loaded
>
> c) "systemctl reboot" continues to check whether a kernel is already
>   loaded, and if so results in kexec.target being started rather than
>   reboot.target
>
> d) If the user wants that the machine is always rebooted via kexec,
>   never with traditional reboot, he can manually create a symlink
>   /etc/systemd/system/reboot.target to
>   /etc/systemd/system/kexec.target.

Yeah, agreed.

Regards,
Marti