CONFIG_KGDB=y
CONFIG_KGDB_KDB=y
CONFIG_KGDB_SERIAL_CONSOLE=y
CONFIG_MAGIC_SYSRQ=y
CONFIG_KGDB_KEYBOARD=y
CONFIG_DEBUG_KERNEL=y
Here's a short documentation on how to use the serial port on the rpi with console and gdb:
Build your kernel with debugging symbols and kgdb (over serial) enabled.
Deploy it, boot it.
Change the kernel cmdline and add:
console=ttyAMA0,115200 kgdboc=ttyAMA0,115200
1st is the serial console, 2nd is the gdb connection.
Now we have console on port 5550 and gdb on port 5551. Boot the board and ...
a) telnet 127.0.0.1:5550 -> console
b) gdb:
gdb vmlinux
- set remotebaud 115200
https://sergioprado.org/acessando-a-console-serial-na-raspberry-pi/
http://lists.linuxfoundation.org/pipermail/llvmlinux/2013-January/000122.html
https://www.raspberrypi.org/forums/viewtopic.php?t=69843&p=507579