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

[Maxim Levitsky]

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)

Both seems to start kdb, because

maxim at maxim-laptop:~$ cat /sys/module/kgdboc/parameters/kgdboc 
kbd

maxim at maxim-laptop:~$ dmesg | grep kgdb
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-2.6.36-rc3+ root=UUID=52341b68-74f3-4c96-aaf8-7586a06c4b4e ro splash video=nouveau nmi_watchdog=lapic kgdboc=kbd
[    0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-2.6.36-rc3+ root=UUID=52341b68-74f3-4c96-aaf8-7586a06c4b4e ro splash video=nouveau nmi_watchdog=lapic kgdboc=kbd
[    2.671914] kgdb: Registered I/O driver kgdboc.


Now when I first switch to console and then press Alt+SysRQ+G, I just get SYSRQ: DEBUG, and system hangs.
It could be printk level, but that should be ok, no?

maxim at maxim-laptop:~$ cat /proc/sys/kernel/printk
7       4       1       7


Also if I remember correct inputting 'g' then ENTER should resume the system, but it doesn't.

So I think kdb doesn't work at all here

Best regards,
        Maxim Levitsky