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

[Maxim Levitsky]

On Wed, 2010-09-22 at 16:03 +0200, Maxim Levitsky wrote: 
> On Wed, 2010-09-22 at 03:42 +0200, Maxim Levitsky wrote: 
> > 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.
> Please disregard this. kdb works with nmi watchdog now as well.
> Probably something was fixed, maybe unrelated to it.
> 
> > 
> > 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.
> And I see that kgdb actually has a code that works that around.
> I suspect that what happens is that keys are released before X continues
> running, and therefore it doesn't pick these events up.

However an evtest on input event running on kernel tty, still only picks
release of the alt key.

Best regards,
Maxim Levitsky