driver mmap weirdness

[Michael Honeyfield]

Hello,

I am looking for some advise on troubleshooting a issue I am seeing
with mmap() (probably how I am using it).

I have a issue where a driver returns a correct value, but it seem to
get lost when that value is validated by mmap() and returns
MAP_FAILED.

Obviously gdb is not going to be able to set into the kernel and set
through each call, so am I left with using ddb ?

Any points/suggestions on dealing with this would be greatly appreicated. 

Thanks in advance..

Mike