Two x86 machines are required for using KGDB. One of the machines runs a kernel to be debugged. The other machine runs gdb. The machine that runs the kernel to be debugged is called the Test machine while the machine that runs gdb is called the Development machine.

A single development machine can be used with several test machines. The architecture of development and test machine can be different. But the architecture of test machine and the architecture of the kernel being debugged should match. The development machine will run a copy of GDB per test machine. The development machine should have at least 128MB RAM so that loading debugging info into gdb does not result into too much of swap space usage.

A serial line is required between the development and the test machine. For the serial line to be established,  machines need one serial port each. A null modem cable is required to connect serial ports of the machines.

Recent versions of KGDB work over ethernet also. If KGDB is run over ethernet, a serial line is not required.

If debugging of modules is needed, the two machines should be connected through a network. The network connection is required by rcp and rsh commands used by module debugging utilities. KGDB itself does not need a network connection. It always needs a serial line only. It's also convenient to have the machines connected through a network for looking into the test machine. The documentation on this site assumes presence of a network.