Re: Problems with latest back and base

[Frederic De Jaeger]

JT> With NVIDIA libGL, just using standard gl* functions and linking with -lGL
JT> brought in a libGLcore dependency.

Well, not on my box, at least.  I have a trivial gl app:

thoran - bourbaki/~/prog/Objective/openGL > ldd glxdemo
        libGLU.so.1 => /usr/X11R6/lib/libGLU.so.1 (0x4001d000)
        libGL.so.1 => /usr/lib/libGL.so.1 (0x4009c000)
        libm.so.6 => /lib/libm.so.6 (0x400e9000)
        libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4010a000)
        libXext.so.6 => /usr/X11R6/lib/libXext.so.6 (0x401e4000)
        libXmu.so.6 => /usr/X11R6/lib/libXmu.so.6 (0x401f1000)
        libXt.so.6 => /usr/X11R6/lib/libXt.so.6 (0x40205000)
        libXi.so.6 => /usr/X11R6/lib/libXi.so.6 (0x40250000)
        libSM.so.6 => /usr/X11R6/lib/libSM.so.6 (0x40258000)
        libICE.so.6 => /usr/X11R6/lib/libICE.so.6 (0x40260000)
        libc.so.6 => /lib/libc.so.6 (0x40276000)
        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 
(0x40389000)
        libGLcore.so.1 => /usr/lib/libGLcore.so.1 (0x403d2000)
        libdl.so.2 => /lib/libdl.so.2 (0x40865000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

I compiled it on my box (with NVidia binary driver, as you can see
with the libGLcore) with just -lGL.
Now I am copying the binary  on another box with just mesa :

dejaeger@smf:~$ ldd glxdemo 
        libGLU.so.1 => /usr/lib/libGLU.so.1 (0x40019000)
        libGL.so.1 => /usr/lib/libGL.so.1 (0x40036000)
        libm.so.6 => /lib/libm.so.6 (0x40180000)
        libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4019d000)
        libXext.so.6 => /usr/X11R6/lib/libXext.so.6 (0x4023e000)
        libXmu.so.6 => /usr/X11R6/lib/libXmu.so.6 (0x4024a000)
        libXt.so.6 => /usr/X11R6/lib/libXt.so.6 (0x4025c000)
        libXi.so.6 => /usr/X11R6/lib/libXi.so.6 (0x402a5000)
        libSM.so.6 => /usr/X11R6/lib/libSM.so.6 (0x402ad000)
        libICE.so.6 => /usr/X11R6/lib/libICE.so.6 (0x402b6000)
        libc.so.6 => /lib/libc.so.6 (0x402cc000)
        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

No more libGLcore, and the application runs perfectly.

JT> Because of this, distributing versions compiled on my machine resulted in
JT> lots of people not being able to run the program. :/

This is a strange and deserves to be investigated.  There may be other
problems.

JT> This issue is underscored by the Linux OpenGL ABI agreement -- as I read
JT> it, you're *never* supposed to link with libGL (either in a library or in
JT> a program), the only symbol "guaranteed" to be findable by dlsym is
JT> glXGetProcAddressARB, and you're supposed to use that to find all the
JT> other functions.

I will modify the backend in this way when I will have some time to
spend on this.

Cheers

   Frederic De Jaeger