The target machine can be another computer, or it can be a VMware virtual machine. Cross 7 and 8 from one connector to 8 and 7 on the other one (RTS, CTS).Cross 2 and 3 from one connector to 3 and 2 on the other one (Rx, Tx).On each connector, tie 1, 4 and 6 (DTR, CD, DSR) together.A cable with the following layout works (DB9 connectors): Since we're using the 'remote' capabilities of GDB, we have to make a serial connection from the host (where GDB is running) to the target (where ReactOS is running), using a null modem cable.