31.6.5 GDB Graphical Interface

The command gdb starts GDB in 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.

To run GDB in text command mode, like the other debuggers in Emacs, use M-x gud-gdb. You need to use text command mode to debug multiple programs within one Emacs session.

• GDB-UI Layout: Control the number of displayed buffers.
• Source Buffers: Use the mouse in the fringe/margin to control your program.
• Breakpoints Buffer: A breakpoint control panel.
• Stack Buffer: Select a frame from the call stack.
• Other GDB-UI Buffers: Input/output, locals, registers, assembler, threads and memory buffers.
• Watch Expressions: Monitor variable values in the speedbar.