loading kernel in gdb

compile kernel with everything about tracing and kernel hacking (DYNAMIC, FTRACE, OPTIMIZE)

then vmlinux file is copied from remote to host

now start gdb/ddd
    > file vmlinux
    > target remote /dev/pts/X

that's it

Sysrq

echo g > /proc/sysrq-trigger

enable/disable sysrq

echo 0 > /proc/sys/kernel/sysrq

echo 1 > /proc/sys/kernel/sysrq 

Finding a symbol
grep alloc_pages /proc/kallsyms -- more symbols because of the loadable modules
or grep alloc_pages /boot/System.map-XXX -- only built-in symbols


kgdb ref:
http://elinux.org/Debugging_The_Linux_Kernel_Using_Gdb