KGTP (stands for Kernel GDB Tracepoint Module) is a provision for opening a GDB remote interface to analyze issues in real time on production systems running the Linux kernel or applications (including Android). It can be compiled as a kernel module and inserted into the running kernel to hook into it remotely. It is also possible to debug userspace programs using GDB tracepoint and other functionality. Even if the board doesn’t have GDB pre-installed or a remote debug interface, KGTP can debug it in offline debugging mode. KGTP supports x86, x86_64, MIPS and ARM architectures and Linux kernel versions from and above 2.6.18. To use KGTP, the kernel should be compiled with some specific debugging related options enabled.
Detailed Documentation: HOWTO
A good article on Linux kernel debugging:
How to use kdump for Linux Kernel Crash Analysis