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From: j@bonnie.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: kernel log
Date: 4 Sep 1995 17:06:31 +0200
Organization: Private U**x site, Dresden.
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Message-ID: <42f4ln$rkf@bonnie.tcd-dresden.de>
References: <4284oe$rct@mirv.unsw.edu.au>
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Alex Lam <alexl@vast.unsw.edu.au> wrote:
> I am kinda modifying the kernel, however I really need some
>debug information coming out of it. I noticed there is a special printf
>which I can use, however, that will limit me to only a screen full.
> Can I infact dump the debug information onto a file ?
Of course :), not.
Handling files is better left to userland utilities. Use the printf
family (look into sys/kern/subr_prf.c, there's a bunch of functions,
and plain printf() ain't the most appropriate every time), and gather
the output via syslogd(8). This does also allow you to collect the
information in a file. Normally, kernel messages are collected in
/var/log/messages.
printf() ``debugging'' is sometimes not a very efficient way to go.
There are two debuggers available for kernel debugging (DDB as on-line
debugger and kgdb (actually, ``gdb -k'') as high-level off-line tool).
Look into the kernel-debug.FAQ for more information.
(The subsection about the preparations for kernel core dumping in the
2.0.5 FAQ file is outdated; -current has this corrected.)
--
cheers, J"org private: joerg_wunsch@uriah.heep.sax.de
http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)