The information in that chapter is somewhat out of date. Here I give simple (that is, less general) instructions which will work with recent (''%%RELENG_6%%'', ''%%7.0-CURRENT%%'') kernels.

Here we assume that you have a recipe to make the kernel panic in some function of your module (or at least, you find it likely that using your
module will result in a panic), and you want to get an useable backtrace.

  - Create a kernel with debugging enabled. (I don't go into details here, consult with Developers' Handbook.)
  - Compile your module with something similar to ''%%make DEBUG_FLAGS=-g%%''.
  - Load the module (eg., ''%%kldload foo.ko%%'').
  - Compute the relocation address for the module's code as it's written in Developers' Handbook.
  - Do whatever you need to do for panicking your system.
  - Dump the kernel (cf. Developers' Handbook).
  - Start kgdb on your kernel and dump (eg.,

<code>
 kgdb /usr/obj/usr/src/sys/GENERIC/kernel.debug /var/crash/vmcore.2}}}
 recently, there is no separate {{{kernel.debug}}}, so now the above will look like
 {{{
 kgdb /usr/obj/usr/src/sys/GENERIC/kernel /var/crash/vmcore.2}}}
 ) and add the module's symbol table as it's written in Developers' Handbook, using the pre-computed relocation address, and the ''debug version'' of your 
 module (eg., {{{foo.ko.debug}}}).
 1. Get the backtrace with the {{{bt}}} command.

You can automate the computation of the relocation address with the help of the following
[[http://www.freshports.org/lang/ruby18|Ruby]] script:
{{{
#!/usr/bin/env ruby

modpath = $*[0]

txtoffset = open("|objdump --section-headers #{modpath}") { |f|
  f.readlines
}.grep(/\s\.text\s/)[0].split[-2].to_i(16)

memoffset = open("|kldstat"){ |f| f.readlines }.grep(
  /#{Regexp.quote File.basename(modpath)}$/
)[0].split[2].to_i(16)

puts "0x#{(txtoffset + memoffset).to_s(16)}"}}}

(If you save it as {{{modaddr.rb}}}, and make it executable, you can run it like {{{modaddr.rb foo.ko}}}, assuming {{{foo}}} is loaded.)

</code>