[Nouveau] [PATCH] drm/nouveau/kms: Implement KDB debug hooks for nouveau KMS.

[Maxim Levitsky]

On Thu, 2010-09-02 at 13:46 +0300, Maxim Levitsky wrote: 
> On Wed, 2010-09-01 at 06:35 -0500, Jason Wessel wrote: 
> > On 09/01/2010 04:56 AM, Maxim Levitsky wrote:
> > > On Thu, 2010-08-19 at 13:55 -0400, Chris Ball wrote: 
> > >   
> > >> Hi,
> > >>
> > >> Here's a patch to add support for KMS debugging to Nouveau, along the
> > >> style of the previous patches for Intel¹ and Radeon².  I'm only able
> > >> to test on nv50 here, so a test on nv04 would be much appreciated,
> > >> and I've published instructions on how to test here³.  Thanks!
> > >>
> > >> - Chris.
> > >>     
> > >
> > > Hi,
> > >
> > > I just tried that patch, but unfortunately nether with nor without it
> > > kdb seems not to work.
> > > It could be id10t error from my side, but I did test the kdb in the past
> > > with few KMS patches, and it seemed to work.
> > >
> > > Now I can't even get its prompt on the console.
> > >
> > > This is what I do:
> > >
> > > echo kbd | sudo tee /sys/module/kgdboc/parameters/kgdboc
> > > (also tried booting with kgdboc=kbd)
> > >   
> > 
> > Try changing it to kgdboc=kms,kbd  or the "echo kms,kbd"
> > 
> > When you use only the kbd, the kms feature is not activated.
> This doesn't help.
> 
> I am afraid that this bug isn't related to kms, but rather is generic.

I turns out that it was the NMI watchdog that I had enabled.
Without it kdb works very well, including the kms support.

It would be better if you were to detect kms instead of adding an
explicit param to kgdboc cmd line.

Also found out that after a debug session with Alt+SysRQ+g and X
running, these keys aren't released. I had to press on all of them to
make them release.
It makes sense as kgdboc in that case reads directly from keyboard port.

Best regards,
Maxim Levitsky