Jeremy, all, this is a followup to bug 466: http://xquartz.macosforge.org/trac/ticket/466 I tried the following to get my implementation working, details below: 1) Use glXCreateNewContext: crash 2) Use glXCreateContextWithConfigSGIX: return 0 I'm running 2.6.0 with the following libraries: dyld: loaded: /Users/eile/Software/eq-git/src/./debug_glx/bin/eqPly.app/Contents/MacOS/eqPly dyld: loaded: /Users/eile/Software/eq-git/src/debug_glx/libs/client/libEqualizer.1.0.0.dylib dyld: loaded: /Users/eile/Software/eq-git/src/debug_glx/libs/admin/libEqualizerAdmin.1.0.0.dylib dyld: loaded: /Users/eile/Software/eq-git/src/debug_glx/libs/collage/libCollage.0.2.0.dylib dyld: loaded: /usr/lib/libSystem.B.dylib dyld: loaded: /opt/local/lib/libboost_system-mt.dylib dyld: loaded: /System/Library/Frameworks/Carbon.framework/Versions/A/Carbon dyld: loaded: /usr/X11/lib/libSM.6.dylib dyld: loaded: /usr/X11/lib/libICE.6.dylib dyld: loaded: /usr/X11/lib/libX11.6.dylib dyld: loaded: /usr/X11/lib/libXext.6.dylib dyld: loaded: /usr/X11/lib/libGL.1.dylib ... What's the proper way to get this working? Cheers, Stefan. 1) Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000 [Switching to process 2161] 0x0000000000000000 in ?? () (gdb) bt #0 0x0000000000000000 in ?? () #1 0x00000001002501eb in eq::GLXWindow::createGLXContext (this=0x10305e4b0, fbConfig=0x10283a200) at /Users/eile/Software/eq-git/src/libs/client/glXWindow.cpp:328 ... (gdb) up #1 0x00000001002501eb in eq::GLXWindow::createGLXContext (this=0x10305e4b0, fbConfig=0x10283a200) at /Users/eile/Software/eq-git/src/libs/client/glXWindow.cpp:328 328 GLXContext context = glXCreateNewContext( _xDisplay, fbConfig[ 0 ], type, shCtx, True ); (gdb) p glXCreateNewContext $1 = {<text variable, no debug info>} 0x100d70426 <glXCreateNewContext> (gdb) p _xDisplay $3 = (Display *) 0x103805800 (gdb) p fbConfig[ 0 ] $4 = (struct __GLXFBConfigRec *) 0x10303a070 (gdb) p type $5 = 32788 (gdb) p shCtx $6 = (struct __GLXcontextRec *) 0x0 2) Breakpoint 2, eq::GLXWindow::createGLXContext (this=0x101a1afc0, fbConfig=0x102060200) at /Users/eile/Software/eq-git/src/libs/client/glXWindow.cpp:328 328 GLXContext context = glXCreateContextWithConfigSGIX( _xDisplay, fbConfig[0], type, shCtx, True ); (gdb) n 364 if( !context ) (gdb) p context $1 = (struct __GLXcontextRec *) 0x0 -- http://www.eyescale.ch http://www.equalizergraphics.com http://www.linkedin.com/in/eilemann