(In reply to Andrey Grodzovsky from comment #19)
> No need to recompile, just need to see what is the content of SDMA ring
> buffer when the hang occurs.
> 
> Clone and build our register analyzer from here -
> https://cgit.freedesktop.org/amd/umr/ and once the hang happens just run 
> 
> sudo umr -lb
> sudo umr -R gfx[.]
> sudo umr -R sdma0[.]
> sudo umr -R sdma1[.]
> 
> I will probably need more info later but let's try this first.

How can I run "umr" on a crashed system? I guess those register values are
retained over a press of the reset button / reboot?