Re: [PATCH] drm/i915: Add aub debug support for kernel

[Chris Wilson <chris@chris-wilson.co.uk>]

On Sat, 6 Nov 2010 00:43:46 +0800, Liu Aleaxander <aleaxander@gmail.com> wrote:
> Well, what are the steps you excepted to get an aub file? Please tell
> me, then I may know your
> points better.
> 
> 
> >
> > Still requires post-processing to add the aub headers, but this will allow
> > runtime enabling of the capture. How does this sound?
> 
> Yes, runtime enabling of the capture is great. And post-processing
> isn't that bad at all.
> What I concerned is how much hard or easy for user to generate an aub
> file. As Nanhai said,
> if user met some problem, we can ask him for an aub file, then we
> might know what was going
> wrong. This is the biggest advantage of aub file. So, I'm not trying
> to ask you give up the
> tracepoints(it really nice for tracing something down), I just want an
> easy way to get an aub file
> for us, and especially for user.

Right. If we want to ask the user to gather some debug info, it
essentially has to be from within X and be as simple as run
'intel-gpu-trace myapp'. Using ftrace is the simplest way to achieve
that. Having to rmmod i915.ko rules out mmiotrace as a viable candidate.
But we can easy add two tracepoints to I915_READ and I915_WRITE which can
be enabled at runtime, exported via /sys/kernel/debug/tracing and
automated in a little tool.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre