*BSD News Article 74358


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Kernel debugger
Date: 21 Jul 1996 12:55:02 GMT
Organization: Private BSD site, Dresden
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loewis@cs.tu-berlin.de (Martin v.Loewis) wrote:

> Thanks for the pointer, it solved my problem. Now that I'm getting into
> ddb, I found that it usually displays function names - except when I'm
> in a loadable module. Is that my fault or ddb's?

Neither. ;) It's the fault of nobody handling symbol loading for LKMs.
This is unfortunately a little more complicated than the static symbol
loading from the bootstrap, since you have to recompute the addresses
relative to the load point.

> Also, is there work going on to improve DDB?

Greg Lehey sometimes asked about a wishlist, but i don't think he has
started any additional work.  There are even more basic things missing
like a commandline editor (not necessary such a bloated one as in
/bin/sh).

You can also mix DDB and gdb -k.  The latter knows about all data
structures, typedefs and enums if you compile the kernel with -g.  It
knows about source files if you start it from the kernel compile
directory.  If you run it with -w, you can also manipulate kernel data
structures.  Maybe you can even set breakpoints, but the will drop you
into DDB on the console.  Be careful however, a full -g kernel is
around 8 MB, and if you don't run `strip -d' on it after installing,
all the symbols will eat up as much physical memory at the next system
boot (even though DDB cannot use them).

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)