Debugging KMS (and thoughts thereof)

Andy Whitcroft apw at
Wed Mar 17 12:20:53 UTC 2010

On Wed, Mar 17, 2010 at 02:12:04AM +0000, Scott James Remnant wrote:
> On Tue, 2010-03-16 at 18:44 -0700, Bryce Harrington wrote:
> > As we move into the new world of KMS, I'm noticing that a lot of our
> > established procedures and tools for debugging modesetting problems no
> > longer work.
> > 
> One thing I did notice from talking with upstream nouveau today and
> debugging the Latitude D620 - our kernels don't have mmiotrace support
> compiled in.
> I'm not sure why, perhaps kernel team could answer that?

This seems to be an oversight.  Looking at the option it seems
completely safe to turn on performance wise if its of use in debugging.
Patches to do this are out on the kernel-team list for review.

> It looks like a tracer like any other, and has to be enabled through
> sysfs before it actually traces - surely this would be a good thing to
> have?
> That then turns all nouveau issues into "fire up nvidia-glx under
> mmiotrace", "send upstream"


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