Kdb on ubuntu 12.10

1. How to config to enter kdb:
Refer to https://www.kernel.org/doc/htmldocs/kgdb.html

Using kgdb, kdb and the kernel debugger internals

2. On ubuntu, more actions to take to enter character mode, or the bash will go to zombie state.
Edit the boot args by replacing the words quiet splash with text.

Refer to http://rolling-ubuntu.blogspot.hk/2012/06/ubuntu-1204-tip-booting-to-text-mode.html

Ubuntu 12.04 tip: booting to text mode (run level 3) and no X