Yes, sure.

First, keep in mind that I am a sysadmin, I don't know a thing about graphic 
programming.

It all began, fortunately, as we have one RHEL 6 virtual machine, and a RHEL 6 
physical machine with an NVidia card. So, strangely, this software worked 
perfectly in the virtual machine, not only with the display in X2go, but on the 
console too ! The ESX does NOT have an NVidia card, it is a basic display for 
servers ! I would not have expected this ?
So I began digging, using strace on my machines, reading your pages, searching 
with Google.
An interesting test was the following : I initiated an X2go connection on the 
virtual machine, then from a terminal in this connection, I connected to the 
virtual machine through ssh -X : and from within this connection, I started the 
software on the vm, but with its display redirected on the X2go display of the 
physical machine : and it worked perfectly : this meant that the graphic driver 
on the machine where the software is run is not involved at all ! it would have 
to be some specific library involved in OpenGL.

Then I figured out that on the VM alone, the software uses the stock "mesa" 
libGL.so. I found on some page on the web that a good test to see which 
libGL.so was used was to run 

ldd /usr/bin/glxinfo

Then I looked at the postinstall script of the NVidia driver provided by ELrepo 
: I saw ldconfig ! This is how the NVidia libGL.so is provided to OpenGl 
applications !

And I must have seen somewhere else the tip about LD_LIBRARY_PATH : which 
worked perfectly with 

ldd /usr/bin/glxinfo

But my software was still failing : why ? Actually, this software is complex, 
it starts opening a graphic console, from which the real utilities are started 
: this console is buggy, it does not provide the user's environment to the 
utilities it starts : this is what got me confused in a first time, I did not 
know it was buggy, I had to figure it out : so I dug deeper, found the 
utilities' rc file, figured out how to change LD_LIBRARY_PATH inside the rc 
file, and I was done !

So to us, the fix is "just" to add at the beginning of LD_LIBRARY_PATH : 
/usr/lib64, so that it is libGL.so from mesa-libGL-devel which is used for the 
OpenGL calls, and not the NVidia one, which is registered in the OS by 
ldconfig. And then, fix the other bugs which get in the way ;-)

I hope I have been clear enough ?


Robert Grasso | System engineer
T +33 (0)4 56 38 08 33 | F +33 (0)4 56 38 08 30

[email protected] | www.altair.com 
Altair | Innovation Intelligence ® 





> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf 
> Of Ulrich Sibiller
> Sent: Monday, March 06, 2017 7:00 PM
> To: Robert GRASSO
> Subject: Re: [X2Go-User] High performance OpenGL issues : fixed
> 
> On Mon, Mar 6, 2017 at 5:53 PM, Robert GRASSO <[email protected]> wrote:
> > Apologies, fix found.
> >
> >
> >
> > Please dismiss this question
> 
> 
> Can you please give us information about the fix? It may help others...
> 
> Uli
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