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Date:      Tue, 22 Oct 2002 15:53:47 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Diego Wentz Antunes <devlware@terra.com.br>
Cc:        hackers@FreeBSD.org
Subject:   Re: Kernel Panic Problems
Message-ID:  <3DB5D6FB.BCE4051A@mindspring.com>
References:  <XFMail.20021022094654.jhb@FreeBSD.org> <3DB5A201.BF8B34C1@mindspring.com> <3DB5BA49.40908@terra.com.br>

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Diego Wentz Antunes wrote:
>     No Terry there are no modifications from me to local files. I realy
> don't know why the information is incomplete
> but I didn't make any modifications.

The incompleteness is because you didn't do a backtrace in ddb at
the time of the crash, and only did it in gdb on the system dump
image; as John explained, gdb sometimes messes up stack frames for
assembly functions, and leaves information out.

The reason I suggested that there would be modifications is totally
different.  The reason is that the line numbers of the source files
for the backtrace do not match the correct function names in 4.4, 4.6,
and -current source code.  This doesn't necessarily mean your code has
local modifications.  But it does mean that you aren't giving us
enough information to be able to properly anayze the backtrace, because
you haven't given us enough information so that the source code we can
look at is the same as your source code.

We don't know if you are running a -RELEASE version, and, if you are,
*which* version you are running.  You never told us.


>     Its possible that a memory problem cause this errors?

It's possible, but unlikely, if the errors didn't happen before, and
they are happening now.  Have you had a lightning storm, are you
overclocking, or has an atomic weapon gone off nearby?  8-).  If the
answer is "no", then the MTBF for solid state devices that have
survived burn-in is pretty much longer than man has been on the
planet.

> Again, last
> night the computer stop running 3 times without
> an apparent cause. This afternoon the first time a turnned on the
> computer it panics again with a fatal trap 12. I'll try
> to change this memory just to eliminate the possibility of hardware
> problem then if it continues i'll do a hard study on
> gdb and try to find some info.
>     Could you provide some good source of information to gdb?

There's an O'Reilly book; most gdb references aren't very useful (IMO).

In practice, it's better to know how the problem *could* happen, then
to try to back track from when it *did* happen.  This means that the
most important thing you can do is get the problem to be repeatable.

It would also help if you were to look at the source code where the
problem starts happening; without your source code, we can only give
you an educated guess as to the problem, based on what we think the
source code should be.

-- Terry

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