KGDB(7)

NAME
kgdb - remote kernel debugging with gdb

DESCRIPTION
Should a programmer be dissatisfied with the OpenBSD kernel's internal debugger ddb(4), and have appropriate hardware available, a kernel with option KGDB may be built to effect remote debugging with gdb(1) instead.

To prepare for debugging over serial line one would:

•   Obtain a second system and a crossover serial cable.
•   Connect the systems and test the cable.
•   Build a kernel with option KGDB and makeoptions DEBUG="-g".
•   Copy the resultant bsd.gdb to the control system, and boot the corresponding bsd on the target system.
•   On the control system, run gdb on the kernel just copied.
•   Issue the command "target remote /dev/<serial port>" within gdb. The target system should enter kgdb at this point.
•   Debug as normal and detach when done, the target should resume normal operation.

SEE ALSO
gdb(1), ddb(4), options(4)

gdb info documents and online documentation.

CAVEATS
The remote connection will introduce certain latencies a local debugger would not see.

Not available on all architectures.