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From: Ho-ng Hun-soo <hunsoo@thebard.kci.co.kr>
Message-Id: <199602160208.LAA13194@thebard.kci.co.kr>
Subject: How to get coredump of kernel
To: questions@freebsd.org
Date: Fri, 16 Feb 1996 11:08:08 +0900 (KST)
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Hi, all!

I am currently using FreeBSD2.0.5-RELEASE on my PC with 8 M RAM.
In order to study the kernel source code, I have a plan to debug my kernel.
According to the FAQ/Text/kernel-debug.FAQ, I followed....

1) I inserted a line in my sys/i386/conf/NEW
options DODUMP
/*
 * There are some lines ... of options.. i.e. DDB, KTRACE..
 */
2) I config'ed my NEW, with config -g.
3) I maked new kernel by typing $make depend, $make in the directory /usr/src/
sys/compile/NEW.
4) Then, I copied my new kernel on /kernel.new after stripping off.
5) I booted my system with kernel.new(its size is 862608) as a single mode.
6) then,

# fsck -p <---- no error
# mount -a -t ufs
# savecore -N /kernel.new /var/crash
savecore:no core dump (no dumpdev)   !!!!!!!!!!!!!!
#

7) Obtaining above message, I suspected that the error maybe is due to the
fact that my / file system(6M) has no enough space, so that I tried
# savecore -N /kernel.new /usr/crash ... after $mkdir /usr/crash
But, same result occurs.

My qustions are..
1) What does the "no dumpdev" message mean?
2) What should I follow to get a core of my kernel.new?
3) FAQ says that I should have sufficient swap memory to make it possible
to get a core,.. is 16M swap space is not enough?

Thank you.