Kernel debugging question

[Greg 'groggy' Lehey]

On Monday, 19 April 2004 at 11:45:37 +0200, Jorn Argelo wrote:
> On Monday 19 April 2004 00:48, you wrote:
>> On Sunday, 18 April 2004 at 20:01:46 +0200, Jorn Argelo wrote:
>>> Hey folks,
>>>
>>> I've been trying to debug my kernel. I've successfully extracted a kernel
>>> dump as described in the development handbook. However, as soon as I come
>>> across this step, I don't know how to continue:
>>>
>>> # cd /usr/obj/usr/src/sys/KERNCONF
>>> # gdb -k /boot/kernel/kernel.debug /var/crash/vmcore.0
>>>
>>> The problem is, kernel.debug doesn't exist at all.
>>
>> This means you didn't build one.
>
> I forgot to add the following kernel option:
>
> makeoptions     DEBUG=-g                #Build kernel with gdb(1) debug symbol

That's about right.

> I did enable the rest though. This is the output of the debugging,

What is the output of the "debugging"?  Your message contained only
the panic message and the gdb prompt:

> #0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240
> (kgdb)

You want at least a backtrace.

> though it seems somewhat different then the output on the FreeBSD
> page. Do you think the folks at current or hackers can do something
> with this?

Yes.

> Or am I forgetting something?

Yes.

Debugging crash dumps is work.  People occasionally do work for free,
but I'd be very surprised if you found somebody to help you with this
one, especially without a debug kernel or even a backtrace.

I'd suggest you catch another dump after you've booted your debug
kernel, then post the backtrace.  That way we'll have something to go
on.  If I have time, I'll reply with a preliminary analysis.

Greg
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