Hi, 

if you have a segfault or another execption in a graphics-app, the System can get frozen.
In my case the dumper try's to dump out the register-space of the sm502-graphics controller.
By default the dumper does not read physical mappings, but in a graphics app, getting  the physical mappings from io-
display, this info seems to get lost.

In my case, it is the 2 MB register space of the sm502, not readable at all offsets:

Mapping of io-display:
# pidin -P io-display map
...
             Mapped Phys Memory @80101000 (81800000)       2048K  S
...
Mapping of faulting graphics app:
# pidin -P gf-t1  map
...
             ture-126f,0501,0:1 @80901000 (       0)       2048K  S
...

You can see it as shared memory under /dev/shmem too:
# ls -l /dev/shmem/
...
nrw-rw----  3 root      root        2097152 Nov 14 11:35 aperture-126f,0501,0:1
...

Is this a known issue ?

Regards
Michael