Bug#814394: xserver-xorg-legacy: Fails to start xserver after upgrade to 1.18.1

[Robert Luberda <robert@debian.org>]

severity 814394 wishlist
retitle 814394 Please detect if systemd-login is available before
dropping root privileges when `needs_root_rights = auto'

Sven Joachim pisze:
> 
> The xserver-xorg-core package recommends libpam-systemd for a reason.

I haven't noticed that recommendation before. I run `apt-rdepends
xserver-xorg' without any other options and noticed that systemd is not
a dependency.

But since it is only a recommendation,  I assume you allow such
configurations when the recommended package is missing. Link you sent
previously contains reference to #814313, which shows that I am not the
only one who have such unusual configuration.

> While this could be changed into a Depends, it would probably not really
> make you happy.

You're right :) I am not really convinced to systemd.

> 
> Now, the bug is that the kms detection did not actually work[1] and so
> the wrapper never dropped root rights, contrary to what the manpage
> says.  This is fixed in xserver 1.18.1, and so you now need
> "needs_root_rights = yes" in /etc/X11/Xwrapper.config if you don't want
> to install libpam-systemd (or a display manager that starts X as root).

I installed xserver-xorg-legacy for its - let me quote the short
description  -   "setuid root Xorg server wrapper". It is really
surprising to hear that the wrapper drops the root privileges is some
situations.  Probably this fact should be better announced - maybe in
the package's description or via README.Debian.
Or maybe would it be possible to add some reference to the
`needs_root_rights' variable into /etc/X11/Xwrapper.config during
initial installation or upgrade of the package?
Finally - as I suggested in the retitle line - maybe the wrapper could
check for working systemd-login before dropping root privileges.

Anyway, with `needs_root_rights=yes' I was able to upgrade the package
to the latest version and it works!

Thanks a lot,
robert