Multi processor safeness of multi threaded OpenGL applicat..

I'm writing a multithreaded Carbon application performing some OpenGL
rendering (the rendering itself occurs in different threads, but it is
protected using a mutex)
This application works fine on a mono-processor G4 but hangs the
system on a dual G5 (both running MacOSX 10.3.4).
When the system has the time to produce some logs, the crash appear to
happen inside the vidéo driver (ATI Radeon 9800).
The context is open using the AGL_MP_SAFE.

AGL documentation states :
"AGL_MP_SAFE If present, only renderers that are multi-processor (MP)
safe are considered. To execute OpenGL commands on a second processor,
an application must use an MP-safe pixel format and also put the
OpenGL library into an MP-safe memory allocation mode with the GLM
interface."

I couldn't manage to find any other information on putting "the OpenGL
library into an MP-safe memory allocation mode with the GLM interface"
What is the GLM interface, is there any documentation about it ?

Thank you for any answer, comment or advice.

renaud