Can we map the whole of a RAM from a thread of one process using the mmap_device_io.

I am trying to implement a self test routine that will check the RAM and the imagevalidity in ROM.
RAM validity is done by writing some RAM locations with predefined value and then reading back. The image validity is 
checked by verifying the checksum of the images.

Can the RAM validity checks be done in one of the QNX process context. We need to map the whole RAM, so this range 
defintely will fall into other process memory as well.Is this allowed. If not, how else this could be acheived.