Re: Replace systemd

[Christian Seiler <christian@iwakd.de>]

Hi,

On 07/04/2017 02:06 AM, Jason Wittlin-Cohen wrote:
> I assume this will work fine for a server system, but will it work on
> a desktop system using GNOME? From what I've read, GNOME has several
> systemd dependencies, but it's not clear to me whether this requires
> systemd to be used as init, or merely that systemd's packages must be
> installed.

For both Jessie and Stretch, the following holds true:

 - GNOME requires systmed-logind's interfaces to work. (Or any
   alternative that implements the same DBus interface, but none
   exist in Debian at the moment)

 - systemd-logind is part of the 'systemd' package, that must be
   instaled.

 - systemd-logind requires DBus methods of systemd, so you will
   either need systemd running ss init system (the 'systemd-sysv'
   package) _OR_ an alternative implementation of these interfaces
   to make logind work on non-systemd systems

 - the 'systemd-shim' package provides an alternative
   implementation of the interfaces required by systemd-logind
   so that it may be used on non-systemd systems

 - this means that you can indeed run GNOME without systemd as
   the init system (i.e. without the 'systemd-sysv' package) on
   Jessie and Stretch, if you have both the 'systemd' and
   'systemd-shim' packages installed

 - however, there will be some slight degradation in some corner
   cases of functionality

For the future (Buster and onwards), note that this all hinges
on systemd-shim continuing to implement the required interfaces
to make systemd-logind work _or_ someone writing and packaging
and alternative to systemd-logind that provides the same DBus
interfaces. It is currently not completely clear whether either
of these is going to happen: there is no alternative to logind
packaged (I know some people have been working on an alternative
that implements the same DBus interfaces, but I don't know the
status of that) and systemd-shim is currently an orphaned
package (both upstream and in Debian), so it's unclear how well
supported this is going to remain. (Of course, if there are no
significant changes between how systemd and logind talk to each
other, this might not be an issue at all, because stuff that
currently works will continue working.)

Regards,
Christian