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From: J Wunsch <j@uriah.heep.sax.de>
Message-Id: <199508150547.HAA03006@uriah.heep.sax.de>
Subject: Re: kern/688: Page fault: supervisor write, page not present
To: davidg@root.com, root@kaiwan.kaiwan.com
Date: Tue, 15 Aug 1995 07:47:00 +0200 (MET DST)
Cc: freebsd-bugs@freefall.FreeBSD.org
In-Reply-To: <199508150330.UAA19230@freefall.FreeBSD.org> from "David Greenman" at Aug 14, 95 08:30:02 pm
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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As David Greenman wrote:
> 
>  >#4  0xf01920b7 in trap ()
>  >#5  0xf018b571 in calltrap ()
>  >#6  0xf0121831 in allocbuf ()
>  ...
>  
>     Would you mind additionally doing an 'nm /kernel | sort' and fishing out
>  the routines around the 0xf018679c? As you may have noticed above, our gdb
>  screws up the stack decoding at the point of the trap (the panic happend in a
>  routine that allocbuf() called, not in allocbuf. Someone really needs to fix
>  that.

Alternatively, adding a -g to the kernel Makefile, removing a few .o
files (including trap.o), should get you in a state where you are able
to say ``frame frame.tf_ebp frame.tf_eip'' from stack frame #4 (in
trap()), which will also spot you to the right location.

Look into the kernel-debug.FAQ for more explanation (even though the
version delivered with 2.0.5 contains bogus references on how to take
a core dump -- but you've got one, so don't care).

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)