32.6.5 GDB Graphical Interface

By default, the command gdb starts GDB using a graphical interface, using Emacs windows for display program state information. In effect, this makes Emacs into an IDE (interactive development environment). With it, you do not need to use textual GDB commands; you can control the debugging session with the mouse. For example, you can click in the fringe of a source buffer to set a breakpoint there, or on a stack frame in the stack buffer to select that frame.

This mode requires telling GDB that its “screen size” is unlimited, so it sets the height and width accordingly. For correct operation you must not change these values during the GDB session.

You can also run GDB in text command mode, like other debuggers. To do this, replace the GDB "--annotate=3" option with "--fullname" either in the minibuffer for the current Emacs session, or the custom variable gud-gdb-command-name for all future sessions. You need to use text command mode to debug multiple programs within one Emacs session. If you have customized gud-gdb-command-name in this way, you can use M-x gdba to invoke GDB in graphical mode.