re: Debugging DRM on a laptop?

[matthew green <mrg%eterna.com.au@localhost>]

coypu%sdf.org@localhost writes:
> Hi folks,
> 
> we're working on a drmkms update.
> I'm testing it on a Dell XPS 9550. It's a laptop with a Skylake CPU.
> It has a power button. The power button powers off, not reboot.
> This means the dmesg buffer gets wiped.
> No serial console as far as I know.
> 
> Now it reaches a point where the screen changes, but my DDB_COMMANDENTER
> containing "reboot" won't do the expected thing. It's possible it's
> hanging. I can't seem to blindly enter ddb.
> 
> Any suggestions to make debugging less painful?
> Something like arm a watchdog to panic after some time.
> 
> I'm gonna experiment with sprinkling panic("XXX"); and see if this works
> out.

if you have ddb.onpanic=0 then it will write a crash dump and
reboot.  that should give you something useful.