VMA of processes and CPU registers

[mindentropy]

On Wednesday 20 Apr 2011 11:00:17 pm Dave Hylands wrote:
 
> I think that this is true for all of the architectures I've worked
> with (ARM, MIPS, x86). Some architectures (like MIPS) have a
> combination of spaces which are linearly mapped between virtual and
> physical, and mapped spaces (which go through an MMU). 

Is this just identity mapping or does it bypass the paging unit for some 
addresses? Just out of curiosity how do you tell the bypassing info?