Using software OpenGL rendering with X

openglxorg

I want to try the most basic OpenGL driver, in order to find out what's the problem of my X server with OpenGL.

I want then to have X use software rendering for OpenGL, like windows do with opengl.dll with no driver installed.

How can I do that? Didn't find anything when searching for X OpenGL software rendering. I'll be glad for a reference, and for the keywords I had to use in order to find out how to do that.

I'm using Xorg in RHEL 5.3.

Best Answer

Duplicating my answer Force software based opengl rendering - Super User:

sudo apt-get install libgl1-mesa-swx11
will remove the libgl1-mesa-glx hardware-accelerated Mesa libraries and install the software-only renderer.

Alternately, you can set LIBGL_ALWAYS_SOFTWARE=1, which will only affect programs started with that environment variable, not the entire system.

Fedora doesn't package the swrast DRI backend separately from mesa-dri-drivers (and I assume the same is the case in RHEL), so the first isn't an option, but the latter is.

Related Solutions

Xorg – How to Invert Colors of the Active Window

If you are looking for a method universal for any window, then this must be made available by the window manager. Therefore I'm afraid any non-composite WM will not be able to do that on demand. So maybe you previously did this with Compiz?

A method of inverting colors regardless of WM is doing this per-application - as with xpdf that you mentioned. There are some applications that have such functionality, but usually you won't be able to invert the colors at run-time. For apps like xpdf, you can either have an alternative desktop menu entry (or icon) that runs the app with special parameters, or define those in your .Xdefaults. For xpdf note also the use of paperColor, foreground and background resources.

How could running strace be fixing the OpenGL issue

I have observed that Nvidia's libGL.so attempts to detect if the current process is being traced, by opening /proc/self/status and looking for "TracerPid:". Different code paths are taken depending upon if the value of TracerPid is non-zero (i.e., is the current processing being traced or not).

Install sysdig, and capture the a trace for the offending process twice, once while stracing, once withouth strace. For example:

$ sysdig -w glxgears.scap proc.name=glxgears &
$ glxgears &
$ kill -TERM `pidof glxgears`
$ kill -TERM `pidof sysdig`
$ sysdig -w glxgears-strace.scap proc.name=glxgears &
$ strace glxgears &
$ kill -TERM `pidof glxgears`
$ kill -TERM `pidof sysdig`

Compare the textual output of the two different traces to observe the change in execution flow between the straced and non-straced runs of glxgears.

strace "fixes" your OpenGL issue, because libGL is behaving differently depending upon if the process is being traced/debugged.

Best Answer

Related Solutions

Xorg – How to Invert Colors of the Active Window

How could running strace be fixing the OpenGL issue

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