KGDB & KDB

http://kernelnewbies.org/Linux_2_6_35#head-01683c6bbfcd2a93c556192e3c9d6734b20da1cd

The key difference between Kgdb and KDB is that using Kgdb requires an additional computer to run a gdb frontend, and you can do source level debugging. KDB, on the other hand, can be run on the local machine and can be used to inspect the system, but it doesn't do source-level debugging.