Re: Debugging DRM on a laptop?

[coypu%sdf.org@localhost]

On Mon, Aug 06, 2018 at 11:02:45AM +1000, matthew green wrote:
> 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.

It's not reaching a panic. And I'm not sure it's reliable about where it
hangs (if at all).

This is after cndetach so maybe that explains why my keyboard doesn't
work to blindly enter ddb.

I'm gonna try to add a watchdog driver, ichlpcib doesn't work out of the
box on the "Sunrise Point-H LPC controller" or "HM170 chipset LPC" but
it has 1771 pages worth of documents so maybe I can get it to work.