Kernel debugging always has been kind of a dark art. What helps greatly is if you can tap into the CPU using some hardware debugging (JTAG or similar).
Today you can also exploit the busmaster DMA capabilities of IEEE1394 to peek into system memory.
However the still most widely used method is pushing debug messaged directly into a UART output register, bypassing any driver infrastructure, and hooking up a serial terminal on the other end.
Today you can also exploit the busmaster DMA capabilities of IEEE1394 to peek into system memory.
However the still most widely used method is pushing debug messaged directly into a UART output register, bypassing any driver infrastructure, and hooking up a serial terminal on the other end.