KDB is a kernel patch (as TuxOnIce is) that can be used to help debug issues related to Suspend2.
To use KDB, download it from the above URL, and apply to your kernel build tree. KDB support is enabled from the "Kernel hacking" menu. You'll find it near the bottom, named "Built-in Kernel Debugger support". You'll probably only want to enable that option. The "KDB modules" item can cause compilation issues.
Having built and installed your KDB enabled kernel, do whatever is necessary to reproduce the condition you want to debug.
Press the Break key to enter KDB. You should get a kdb> prompt.
KDB sometimes has problems with the keyboard state. If pressing keys gets no response, try pressing and releasing the shift, control and alt keys, then try again.
KDB commands you might want are:
md <address>: Display the contents of an address. Symbol names can be used and tab completion is possible.
- ps: List processes on the system. Output is paged. Press Q to stop the paging, any other key for the next page full. The number of lines per page can be modified with the command set LINES=50 (eg).
btp <pid>: Backtrace a process
- dmesg [n]: Show the whole kernel log buffer or the last n lines. See ps for usage of paging.
- go: Continue running.
- help: Full list of commands.
kdb output doesn't get stored anywhere. You'll need to use a digital camera to capture anything you want to keep.