Access permissions of /dev/mem

Question

I have a set of questions regarding /dev/mem:

1. Many articles on the net, seem to refer /dev/mem as the gateway to \"Physical RAM\

Answer 1

What does the follow yield:

cat /dev/mem | wc

I get:

cat: /dev/mem: Operation not permitted
   1908   11791 1048576

So for me it does stop at 1MB.

Note that cat uses open, not mmap so its not an identical test.

Are you sure you're reading beyond 1MB?