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Re: How to get debug information?

On 04/06/2016 05:10 PM, Floris wrote:
> Op Wed, 06 Apr 2016 16:50:10 +0200 schreef Floris <jkfloris@dds.nl>:
>> I'm testing the new Nvidia driver module with drm enabled. It is very experimental so I know there are bugs in it. I think I found a problem and I want to get more information about it from the log messages, but the whole system freezes. I can't ssh into the system or change to a tty. After a hard reboot the last lines in journalctl are:
>>     kernel: usb 2-1.7: current rate 0 is different from the runtime rate 48000
>>     Failed to get journal fields
>> Not very useful
>> Is there a way to get more information?
>> Floris
> Some more information
> I think the issue is in vdpau
It depends if you box has completely locked up.
if it has not you can try running a ssh server and logging 
in with putty(windows) or ssh(linux) from another machine. 
then try dmesg or attaching a gdb to the xorg process 
(and hope the problem is in userspace). 
you may want to install the dbg packages to have human-readable
function/variable names etc...

If it's locked up completely, there's not much you can do. The
`experts' will tell you to look at /var/log/messages or ~/.xsession-errors 
to see if it has any hints, and perhaps recompiling the Linux kernel 
with debug flags and sysRq key, but
that takes at least 3 trys until you get a bootable build done... 
Keep a backup kernel+initrd, so you don't end up with a bricked system.

Oh, and if it's the proprietary driver, forget all of the above. 
You likely won't get that one debugged...

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