[PLUG] Debugging APM for 2.6 kernels - ideas?

[Keith Lofstrom]

On Sat, 11 Feb 2006, Keith Lofstrom wrote (and was quoted):
> I am *still* bringing up 2.6.9 on my T30 laptop,

... and ALSO wrote ...

>                                             a version of RHEL4.2
> called Scientific Linux, maintained by Fermilabs.
>
> Unfortunately, like the 2.6 kernel that came with SUSE10,
[ which is 2.6.13-15.7 ]
>                                                     , the pesky
> thing occasionally hangs coming out of suspend (blinking caps-lock
> and scroll-lock, often a sign of kernel panics).  I have not yet
> found a repeatable pattern, and I have tried a few dozen things to
> see if they stop the hangs.  I am using APM 

... and here is MY question ...

> Is there anything I can run, or compile into the kernel, to capture
> some data on what is causing the panics?  There is nothing revealing
> in the logs now.  Return-from-suspend is a particularly nasty time
> for things to go wrong.
> 
> I am not very interested in more suggested frobs, unless you have
> actual experience on a similar laptop with a similar kernel.  I am
> more interested in finding out WHY this is happening, and that
> is best accomplished through observation and information capture.
 
On Sat, Feb 11, 2006 at 03:31:17PM -0800, Rich Shepard wrote:
> Why that version? I have 2.6.13.4 running on my Sony Vaio...

On Sat, Feb 11, 2006 at 03:32:28PM -0800, AthlonRob wrote:
> Why not use a more recent kernel?

I have an out-of-town friend who is obese.  He eats far too much.
He doesn't like doctors, who tell him to eat less and exercise, 
but cannot provide him with a pill that will cause him to lose
weight (while still eating too much).  He wants to fix his eating
problem by ... eating.  A very modern consumer attitude, I
suppose, but not my style.

I would rather have enlightenment than enlargement.  My natural
tendency when encountering a problem is not to consume something
more, but to try to understand the problem.  Frobbing kernels will
not help me understand what is going on with this one - unless
someone has evidence that there is a known problem in 2.6.9 that
causes this hangup which was fixed in later kernels.  I switched
FROM a distro that uses 2.6.13-15.7, which had a somewhat similar
lockup problem (and many other problems), partly because so far
there is little written about these later kernels. 

So I repeat my question -

HOW DO I OBSERVE WHAT IS GOING ON DURING AN APM RETURN-FROM-SUSPEND ???

If 2.6.13+ kernels provide some new feature that increases
observability during return-from-suspend, I am interested. 
Otherwise, trying yet another kernel is not interesting, even if
it does have a small chance of making this particular problem
happen less often.  Without understanding and tools, I am at the
mercy of the next problem that comes along, and unable to help
others.  I will leave the "upgrade and hope the new bugs are
better than the old bugs" approach to the Micro-softheads.  If
I can observe the problem, I can help fix the kernel.

And if you want to question from tools and kernel debugging to
"why newest is best", please change the subject line, OK?

Keith

-- 
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs