Why does fusion mmap using MAP_FIXED?

[rogerjxperi]

I noticed that fusion mmaps shared memory using MAP_FIXED, like:
heap = mmap( addr_base, size + space, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, fd, 0 );

This seems like a dangerous approach since MAP_FIXED will clear any memory already in that memory range. So unless you call DirectFBCreate very early during startup there is a chance that it will clear already mmap:ed memory, and at best cause a crash.

So, out of curiosity, why does fusion require that shared memory is allocated at a specific address that it gets from the fusion kernel module?