KGTP is a realtime and lightweight Linux debugger and tracer.
To use it, you don't need patch or rebuild the Linux kernel. Just build KGTP module and insmod it is OK.

It makes Linux Kernel supply a GDB remote debug interface. Then GDB in current machine or remote machine can debug and trace Linux through GDB tracepoint and some other functions without stopping the Linux Kernel.
And even if the board doesn't have GDB on it and doesn't have interface for remote debug. It can debug the Linux Kernel using offline debug (See HOWTO#/sys/kernel/debug/gtpframe_and_offline_debug).

KGTP supports X86-32, X86-64, MIPS and ARM.
KGTP is tested on Linux kernel 2.6.18 to upstream.
And it can work with Android (See HowToUseKGTPinAndroid).

Please go to HOWTO or HOWTOCN (Chinese) to get more info about howto use KGTP.

Please go to UPDATE to get more info about KGTP update.

http://www.freelists.org/list/kgtp is the maillist of KGTP.