Re: shared memory pixmaps
Check the Xorg log file if the drivers recognized the line you added. So how did you add it? The right way would be to add the line: Option "AllowSHMPixmaps" "1" to the right screen or device section.
Do you really need shared memory pixmaps? It is and old feature and should not be used in modern apps as you won't receive much hardware acceleration. If possible use another mechanism. If your app uses OpenGL use pixel buffer objects (PBOs) which offer roughly similar functionality.