Comment 0 for bug 585853

Binary package hint: xdm

Bug discovered after upgrading an xdm-using 8.04.2 LTS x86_64-desktop laptop to 10.04 LTS, but now repeated as follows.

Take default gdm-using 10.04 LTS x86_64-desktop laptop
aptitude install xdm
and set xdm as the default window manager
restart

You will now see the ubuntu white/red dots animation, and that's as far as things go.
ctrl-alt f1 gets you a log in prompt
ps ax | grep dm
shows nothing - so this isn't the same as the "both gdm and xdm run" bug.

In fact
ps ax | grep -i x
returns nothing.

Extras: x.org x server v 1.7.6, intel graphics controller. According to kern.log
fb0: inteldrmfb frame buffer device
... drm Initialized i915
vga16fb: not registering due to another framebuffer present

so things should be set for X to start, namely drm Initialized looks hopeful

Yet running xdm -debug 2 from vt1 shows
...
/usr/bin/X :0 vt7 -nolisten tcp -auth /var/lib/xdm/authdir/authfiles/... (all OK)
...
(EE) intel(0): [drm] failed to set drm interface version.
                           Failed to become DRM master.
                           failed to get resources: Bad file descriptor
                           Kernel modesetting setup failed
(EE) Screen(s) found, but none have a useable configuration.
Also surprising as:
drmOpenDevice: node name is /dev/dri/card0
                         open result is 9 (OK)
(Chipset GM45)

So, how come X thinks drm isn't setup, yet the kernel thinks it is?

Work around: put gdm back as default with dpkg-reconfigure {gdm|xdm}

Now comparing Xorg.0.log in broken xdm and working gdm cases, xdm has:

xf86OpenConsole: setpgid failed: Operation not permitted
xf86OpenConsole: setsid failed: Operation not permitted

and later drmOpenByBusid returns nothing as opposed to pci:0000:00:02.0

So, why the permission denied? apparmor not treating xdm as well as it treats gdm?

(no ubuntu-bug -p xdm included, as I am writing this on a working single-boot NetBSD/i386 laptop)