[LightDM] lightdm and running the xserver without root rights

[Hans de Goede]

Hi all,

Quick self intro: I've been a FOSS developer since 1996, recently
I've mostly been working on USB support in the kernel, libusb and qemu.
I've started working for Red Hat 5 years ago and recently I've changed
teams to the Graphics team.

Currently I'm finishing support for systemd-logind's new session-controller
API (TakeControl and friends) for Xorg, with the purpose that the xserver
will use systemd-logind to open and manage input and drm devices for it,
so that it will no longer need root rights.

In order for this to work the X server needs to be started inside the
users (pam) session. This is identical to how things will work between
wayland and systemd-logind, so any work done to support this will
also apply to future wayland support.

For this to work the xserver will also need to be able to access
the vc (/dev/tty#) on which it is being started so this needs to
be setup properly too.

Note I've already had a discussion about this with the gdm maintainer
on the xorg-devel list, see:
http://comments.gmane.org/gmane.comp.freedesktop.xorg.devel/38796

For some more info, all see the slides of my Fosdem talk on this:
https://fosdem.org/2014/schedule/event/rootless_xserver/

Video of the talk is here:
http://video.fosdem.org/2014/H1301_Cornil/Saturday/Making_the_Xserver_run_without_root_rights.webm

I hope you can add support for this to lightdm. If you've any questions
let me know.

Thanks & Regards,

Hans