VMD-L Mailing List

From: Jiri Polach (clarinet_at_atlas.cz)
Date: Tue Sep 17 2013 - 08:02:23 CDT

Hi John,

Thank you for pointing me to glxinfo. After some tests and extensive
googling I found a solution - the easiest initial workaround is to set
an environment variable LIBGL_ALWAYS_INDIRECT on the server that does
not allow to run vmd (and/or other X applications, including glxinfo):

LIBGL_ALWAYS_INDIRECT=yes

The whole problem seems to be somehow connected with Ubuntu and nVidia
drivers and is described in detail in the following thread

https://bugs.launchpad.net/ubuntu/+source/mesa/+bug/384001

I have not studied it into a detail, but I will run more tests to find
out whether it is possible to allow direct rendering even in our situation.

Note: the X connection goes through an ssh tunnel (X11 forwarding).

Best regards,

Jiri Polach

On 9/17/2013 6:56 AM, John Stone wrote:
> Hi,
> Have you tried running "glxinfo" on these machines and comparing
> the results you get when you run locally vs. what you get when
> you display remotely? I would expect that "glxinfo" will tell you
> basically the same thing that VMD does. You didn't indicate what
> you had the "DISPLAY" environment variables set to, whether they
> were communicating directly to X, or if they were going through 'ssh',
> nor whether your X11 server is set to allow network connections.
> Many Linux distributions are now shipping X-windows configured not
> to accept network connections...
>
> Cheers,
> John Stone
> vmd_at_ks.uiuc.edu
>
>
> On Mon, Sep 16, 2013 at 04:40:08PM +0200, Clarinet wrote:
>> Hi all,
>>
>> We have two servers with VMD installed and several workstations that
>> call it remotely, i.e. users start VMD on the server and let it open
>> windows on their workstation using X11 redirection via ssh tunnel.
>>
>> For most combinations of servers and workstations everything is fine,
>> but there are certain pairs that do not allow VMD to start saying:
>>
>> Info) VMD for LINUXAMD64, version 1.9.1 (February 1, 2012)
>> Info) http://www.ks.uiuc.edu/Research/vmd/
>> Info) Email questions and bug reports to vmd_at_ks.uiuc.edu
>> Info) Please include this reference in published work using VMD:
>> Info) Humphrey, W., Dalke, A. and Schulten, K., `VMD - Visual
>> Info) Molecular Dynamics', J. Molec. Graphics 1996, 14.1, 33-38.
>> Info) -------------------------------------------------------------
>> Info) Multithreading available, 4 CPUs detected.
>> Info) Free system memory: 11154MB (92%)
>> Warning) Detected a mismatch between CUDA runtime and GPU driver
>> Warning) Check to make sure that GPU drivers are up to date.
>> Info) No CUDA accelerator devices available.
>> Warning) Detected X11 'Composite' extension: if incorrect display occurs
>> Warning) try disabling this optional X server feature.
>> ERROR) A TrueColor visual is required, but not available.
>> ERROR) The X server is not capable of displaying double-buffered,
>> ERROR) RGB images with a Z buffer. Exiting ...
>> Info) VMD for LINUXAMD64, version 1.9.1 (February 1, 2012)
>> Info) Unable to create OpenGL window.
>>
>> So workstation A is able to run VMD from server X as well as Y, but
>> workstation B can only run VMD from server X, running VMD form Y fails
>> with the above message. Both installations of VMD (on servers X and Y)
>> are identical (version 1.9.1).
>>
>> What can be the problem? Can it be somehow connected to the issue we
>> have been discussing some time ago
>> http://www.ks.uiuc.edu/Research/vmd/mailing_list/vmd-l/21153.html ? Some
>> of the workstations that have the current problem also suffered from the
>> previous one, but we cannot confirm that it is a general rule.
>>
>> Best regards,
>>
>> Jiri Polach