I need to use typed memory to define a DMA-safe region (See "Defining a DMA-Safe region" on http://www.qnx.com/
developers/docs/6.4.1/neutrino/sys_arch/ipc.html). Hardware contraints requires that this region be 128MB aligned.

I made the appropriate modifications to main.c and rebuilt the OS image to reserve 128MB on a 128MB boundary 
(0x08000000) for our x86 board that has 2 GB of ram. I found out that mmap doesn't let me map the full 128MB. I can only
 do about 120MB or so. If I cycle power, the maximum amount of memory that I can map changes, but I have not been able 
to get all the memory reserved.

Why is it that mmap doesn't allow me to use all the memory I defined?

From the example in the documentation (see above documentation reference), it seems to imply that the value of the 
variable "size" would be the same in both code snippets.

Thanks,