Bug#589346: xorg: Graphical acceleration only available to one X user

[Alex Dănilă <nuorama@gmail.com>]

Package: xorg
Version: 1:7.5+6
Severity: normal

Some types of acceleration are not availabe to the second simultaneous 
log-in on the machine. I only say some types,
because some things work fast, others slow:
Fast:
-window resizing (both kwin and metacity)
-Opera animations, drawing, javascript
-KDE Plasma animations
-video seems to work decently.

Slow:
-window moving (both kwin and metacity)
-scrolling (Dolphin, Opera)
-3d is much slower (TORCS: 5-15 fps on the first login, 0-1 fps on the 
second)

Additionaly, Kwin compositing cannot be enabled on the second login, 
only on the first. Please ask for any
information I failed to provide.

Reproduce:
-login to an desktop session
-start a new desktop session without closing the first one, and notice 
the problems with this session.

Video driver:
xserver-xorg-video-radeon 1:6.13.1-1

This situation has been the same for a long time in Debian Unstable 
(more than a year), regardless of drm, mesa, kde version, xorg version.

-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.34-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages xorg depends on:
ii            2.30.2-1                       The GNOME terminal emulator 
applic
ii            4:4.4.4-1                      X terminal emulator for KDE 4
ii            7.9.0+git20100608.bcf63dbb-0ub A free implementation of 
the OpenG
ii            7.9.0+git20100610.63834285-0ub A free implementation of 
the OpenG
ii            7.9.0+git20100610.63834285-0ub The OpenGL utility library 
(GLU)
ii            7.5+5                          X applications
ii            7.5+1                          X session utilities
ii            7.5+4                          X11 utilities
ii            7.4+1                          X font server utilities
ii            7.5+5                          X11 XKB utilities
ii            7.5+1                          X server utilities
ii            1:1.0.4-1                      X authentication utility
ii            1:1.0.1                        100 dpi fonts for X
ii            1:1.0.1                        75 dpi fonts for X
ii            1:1.0.1                        standard fonts for X
ii            1:1.0.1-1                      scalable fonts for X
ii            1:7.5+2                        X Window System font 
utility progr
ii            1.2.0-2                        X server initialisation tool
ii            1.8-1                          X Keyboard Extension (XKB) 
configu
ii            1:1.5-1                        Core documentation for the 
X.org X
ii            1:7.5+6                        the X.Org X server
ii            261-1                          X terminal emulator

xorg recommends no packages.

Versions of packages xorg suggests:
pn  xorg-docs <none>     (no description available)

-- no debconf information