[systemd-devel] Provide INIT_VERSION?

[Lennart Poettering]

On Wed, 08.09.10 20:14, Gustavo Sverzut Barbieri (barbieri at profusion.mobi) wrote:

> 
> On Wed, Sep 8, 2010 at 7:16 PM, Lennart Poettering
> <lennart at poettering.net> wrote:
> > On Wed, 08.09.10 11:24, Gustavo Sverzut Barbieri (barbieri at profusion.mobi) wrote:
> >
> >> Hi all,
> >>
> >> Seems that sysvinit provides INIT_VERSION=sysvinit-1234 to its spawned
> >> processes and tools like /sbin/halt check for it to just then check
> >> for $RUNLEVEL so I wonder if we should provide this in systemd
> >> automatically or I should change my .service units to provide them
> >> with Environment=INIT_VERSION=sysvinit-1234
> >
> > I think the latter is nicer. After all we aren't sysvinit, so I'd prefer
> > not to claim we were in the C sources. Also note that at least in the
> > Fedora shutdown scripts we already set RUNLEVEL=0 via the Environment=
> > option, so if INIT_VERSION is necessary it probably makes sense to place
> > it in Environment= too.
> 
> Yeah, I have those in my units, but it will suck as we'll have to do
> replacement of systemd-$PACKAGE_VERSION.... or just stick some random
> variable there, as sysvinit just check for variable existence but not
> actual value.
> 
> Anyway, maybe it's better to just ignore it and go straight with
> systemd-native actions. Would you mind sharing your ideas about them?
> Maybe I can help there as well.

I figure you are aware that symlinking /sbin/reboot and friends to
/bin/systemctl gives you systemd native implementation of these tools?

Our rough plan for the long run for the implementaiton of late shutdown
is to provide /lib/systemd/systemd-halt or so which will be exec'ed by
PID1 in the end. This binary will then kill all remaining processes,
unmount all fs, mount remaining fs r/o and then shutdown or kexec. 

The approach is kinda nice since we then avoid busy mmaps, and PID 1 is
the first and last process of the system.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.