RE: Hopefully Simple Question on Debugging Kernel Modules

From: David Christensen <davidch_at_broadcom.com>
Date: Mon, 23 Feb 2009 12:51:18 -0800
> > > Just use gdb on bce.ko (built with debug symbols):
> > >
> > > gdb /path/to/if_bce.ko
> > > (gdb) l *bce_intr+0x8df
> > >
> > > If you get a crashdump you can run kgdb on it and just walk up to
> the
> relevant
> > > stack frame and use 'l' there to get a listing.
> > >
> >
> > One thing that I've never figured out is how debugging symbols are
> > handled in module builds these days.  If I go to /sys/modules/bce and
> > do 'make', it generates a .ko and explicitly strips it.  I wind up
> > having to re-run the link command by hand so I get symbols.  What is
> > the correct way to do this?  Note that I'm not interested in answers
> > that involve "go to /usr/src and run make buildkernel" =-)
> 
> make DEBUG_FLAGS=-g is what I use.  The same thing works for userland
> tools
> and the kernel (usually we put 'makeoptions DEBUG_FLAGS=-g' in a kernel
> config so it is "automatic" for kernels though).

So is the use of COPTS=-g mentioned in the Developer's Handbook
(http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-kld.html)
deprecated?  I wasn't able to build with symbols until I used DEBUG_FLAGS='g.

Dave
Received on Mon Feb 23 2009 - 20:03:05 UTC

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