Looking for FreeBSD kernel debugging help

Soren Kristensen soren at soekris.com
Wed Jun 11 01:52:32 PDT 2003

Hi Everybody,

First, thanks to everybody offering tips and help. The good news is that 
the problem is solved.

I couldn't wait, so I finally decided to learn a little FreeBSD kernel 
debugging. After reading lots of not very comprehensive man pages and 
other guides, I got a 4.4 kernel compiled with ddb and set up remote 
debugging over the 2nd serial port with gdb. Again, after reading even 
more on using gdb, I set a bunch of breakpoints a did a little tracing 
and got the problem localized to a PCI configuration problem, probably a 
undocumented hardware bug in the Geode SC1100 processor combined with 
not very smart PCI config code in FreeBSD. I have patched FreeBSD to 
boot on the net4801 board, more details after I know exactly what's the 
issue is.

Lesson learned:

Advanced FreeBSD documentation sucks if you're not a kernel hacker, but 
remote kernel debugging works great and are actually kinda fun....


Soren Kristensen

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