Gdb User Interface
This mode acts as a graphical user interface to GDB and was introduced in Emacs 22.1 (04-06-07). You can interact with GDB through the GUD buffer in the usual way, but there are also further buffers which control the execution and describe the state of your program. It separates the input/output of your program from that of GDB, if required, and watches expressions in the speedbar. It also uses features of Emacs 21 such as the fringe/display margin for breakpoints, and the toolbar (see the GDB Graphical Interface section in the EmacsManual).
M-x gdb will start the debugger. M-x gud-gdb will start the old text mode debugger that existed prior to Emacs 22.1.
This file has evolved from gdba.el that was included with GDB 5.0 and written by Tom Lord and Jim Kingdon. It uses GDB’s annotation interface. You don’t need to know about annotations to use this mode as a debugger, but if you are interested developing the mode itself, then see the Annotations section in the GDB info manual.
GDB developers plan to make the annotation interface obsolete. A new interface called GDB/MI (machine interface) has been designed to replace it. The mode in CVS Emacs in the repository at savannah.gnu.org now fully uses GDB/MI. If you are interested in its development please use it and report any bugs you find to firstname.lastname@example.org. This mode will eventually be much better than the current mode but, for someone who just wants to use GDB, the current mode in released Emacs 23.1 is probably a better option.
This screenshot shows what it looks like debugging Emacs.