SGI
Open Source
kGDB (Remote kernel debugger)

kGDB provides a mechanism to debug the Linux kernel using the popular debugger gdb. kGDB is an extension to the kernel that allows a user running gdb on a remote host to connect to a machine running the kGDB-extended kernel. The user can then "break" into the kernel, set breakpoints, examine data, etc. very similarly to how one would use gdb on an application program. One of the primary features of this patch is that the remote host running gdb connects to the target machine (running the kernel to be debugged) during the boot process. This allows debugging to begin as early as possible.

Read more about or participate in development via the kgdb project at sourceforge.net.