From: Axel Kohlmeyer (
Date: Mon Mar 17 2008 - 13:59:35 CDT

On Mon, 17 Mar 2008, Ignacio Fernández Galván wrote:

IFG> Hi all,
IFG> I have a Mandriva 2008 system, with an nVidia GeForce 8500 GT graphic
IFG> card. When I first installed this, some months ago, I remember I had
IFG> GLSL working in VMD (after some failed trials). Today, however, I
IFG> realize VMD reports GLSL is not available.
IFG> I don't remember having changed anything important in the system. Not
IFG> the nvidia drivers (version 100.14.19), but I update it regularly, so
IFG> maybe the server or some library has changed.


whenever you install updates on linux machines with
manually installed nvidia drivers, you are danger of
losing that functionality. some distributions overwrite/regenerate
the X11 configuration with updates and also for new kernels
you have to rebuild the nvidia kernel module.

the safest way to handle the situation is to: turn off x11
("telinit 3" as superuser), uninstall the nvidia drivers,
run the update, install the nvidia drivers again, check
configuration and reboot into the normal runlevel.

for some distributions people repackage the drivers and offer
specific packages (e.g. fedora via or have
special scripts/flags that trigger the required steps (suse).

IFG> Also, now glxinfo says "direct rendering: No", but 3D apps and games
IFG> seem to work fine, so I'm not sure it said "Yes" before...

well, a lot of applications have alternate display modes.
VMD's performance is quite a bit more affected by lack
of full OpenGL support.


IFG> Do you have any idea of what to try to solve this? Any similar
IFG> experience?
IFG> Thanks,
IFG> Ignacio
IFG> P.S. This is worse than I thought. I've just updated the kernel and
IFG> rebooted the system. Now some volume density files that were working
IFG> fine just a week ago (and with correct transparency with GLSL and
IFG> everything) look plain broken, with triangles all around. What has
IFG> happened? :(
IFG> ___________________________________________________________
IFG> Rise to the challenge for Sport Relief with Yahoo! For Good

Axel Kohlmeyer
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
If you make something idiot-proof, the universe creates a better idiot.