According to https://fedoraproject.org/wiki/Features/DisplayManagerRework we should replace the line: enable gdm.service that is already present in /usr/lib/systemd/system-preset/99-default.preset with: enable kdm.service to make kdm the default login manager.
in kde-sig meeting, we hadn't decided where best to put this yet (in spin or in a pkg like kde-settings somewhere)
So, as per https://fedoraproject.org/wiki/Features/PackagePresets systemd DOES accept presets in /etc. I think the spin kickstart should dump the preset to /etc. It won't be owned by a package, so it should be treated as initial site policy to be edited directly by the admin, not written to a read-only file system. Putting it in a package would make sense if it HAD to be in /usr, but packages changing distro defaults is not such a nice idea. I think it's better for the KDE spin kickstart to dump a file in /etc, as it did in the past with /etc/sysconfig/desktop.
Halfline pointed out too that the old default ordering still takes place, so if only kdm is installed, it will get used. I'm tempted to just rely on that, and be done with it.
that would not cover DVD installs. From the blocker meeting today it seems no-one is really entirely sure how systemd guys are expecting this to work, so I'm gonna close this as a dupe of 850775 - which is a more general statement of the problem - and change the component of that bug to systemd, so lennart can tell us how he actually expects this stuff to work. *** This bug has been marked as a duplicate of bug 850775 ***
> that would not cover DVD installs. DVD installs were not covered in the past either, they'd just rely on the then prefdm and now systemd defaults. What we wrote /etc/sysconfig/desktop for was installations from the KDE spin which then got GDM added later, e.g. as a dependency (In particular, gnome-shell drags in GDM now.), so it didn't suddenly become the default.