KGDB connection failure - Please help, I'm desparate!

[Peter Craft]

I've been trying for three days to get KGDB to work.

I've followed the instructions here:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug-online-gdb.html

and here:
http://www.lemis.com/grog/Papers/Debug-tutorial/tutorial.pdf

without success.  Specifically, I've rebuilt my kernel with:
makeoptions     DEBUG=-g                # Build kernel with gdb(1) debug symbols
..
options         KDB
options         DDB
options         GDB

My "boot.config" file contains -P and my /boot/loader.conf file contains:
hint.sio.0.flags="0x90"

When I issue the "boot -d" on the target, the system breaks in to the "db" prompt
as expected, at which point I enter "gdb" followed by "s".  All of which seems to
work perfectly.

On the debugger side I enter kgdb with  "kgdb -r /dev/cuad0 -v kernel.debug"
from the build directory and I get:

Ignoring packet error, continuing...
Ignoring packet error, continuing...
Ignoring packet error, continuing...
Couldn't establish connection to remote target
Malformed response to offset query, timeout

If I boot the remote system with "set console=comconsole", I'm able to communicate
across the serial line as a console, so I believe that the serial ports and cable are
functioning properly.  I just can't get gdb to connect.

Can anyone offer any suggestion on what to try next?  Or tips on how to go
about debugging the problem?  This is with FreeBSD 7.1.

Thanks in advance,

Pete