From: Moulton, Steve (
Date: Tue Sep 14 2010 - 11:03:13 CDT

Hi John,

What I really wanted was a silver bullet. No such luck.

At this point, we are going to ask users to migrate their data from this system when they need to run VMD. If we run into a roadblock, I'll check back about other possible solutions.

   - Steve

-----Original Message-----
From: John Stone []
Sent: Monday, September 13, 2010 5:35 PM
To: Moulton, Steve
Cc: ''
Subject: Re: vmd-l: GLXBadLargeRequest and BadLength messages

  I can't comment on the X/GLX OpenGL remote display issues other
than to say that this has been an issue that crops up somewhat frequently
under different versions of linux as bugs have crept into the X11 server
implementations at various times. I've found this particularly frustrating
as most of the classic unix systems from SGI, Sun, and others never had these
kinds of problems. I suspect that X/GLX OpenGL remote display is simply
one of the features that the maintainers of modern linux distributions
don't test very carefully when they update to a new X11 version.

Regarding potential workarounds:
  In most cases you'll get much better performance running VMD
locally than via a network connection. Can you load files from
your 10.2 system over a network filesystem of some kind?
The molecular structure and trajectory files usually contain
less data than the resulting stream of OpenGL commands and geometry
that get generated from them, so you would get both better display
performance and use far less network bandwidth to transfer your
data to your display machine rather than remote displaying.

If there's some other hardware or security limitation that causes
you to want to remote display, let me know and I may be able to
suggest other alternative strategies.

  John Stone

On Mon, Sep 13, 2010 at 04:43:32PM -0400, Moulton, Steve wrote:
> Greetings,
> While running VMD 1.8.7 on a OpenSuSE 10.2 64 bit system but displaying on
> an OpenSuSE 11.2 64 bit system, I am seeing many messages of the form
> XRequest.135: GLXBadLargeRequest 0x2
> XRequest.135: BadLength (poly request too large or internal Xlib length
> error) 0x2
> For various reasons, it is not possible to update the 10.2 system. VMD
> ran correctly when the display system was OpenSuSE 11.0, but these systems
> are being upgraded. Setting VMDSIMPLEGRAPHICS is a workaround, but is
> not quite satisfactory.
> Anyone have any ideas how to get around this one? I did try throwing a
> VNC to no avail, and the X servers don't have the LBX extension (which use
> to be quite effective at patching up X protocol errors).
> Thanks,
> Steve Moulton

NIH Resource for Macromolecular Modeling and Bioinformatics
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