This works for me using C-c C-c
Current directory is /src/build/emacs-24.5/src/ GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1 Copyright (C) 2014 Free Software Foundation, Inc. ... (gdb) run Starting program: /src/build/emacs-24.5/src/emacs [Thread debugging using libthread_db enabled] ... [New Thread 0xb4bffb40 (LWP 735)] C-c C-c(gdb) C-c C-c(gdb) break main Breakpoint 1 at 0x815d7b8: file emacs.c, line 707. (gdb) But here are two other things to try. First is without the -i=mi option. The second is to use realgudrealgud (available from MELPA); and in realgud this can be done in one of two ways. After M-x load-library realgud, then M-x realgud:gdb or you can go into a comint"shell" (comint) or term"term" shell and run plain gdbgdb, set"set annotate 11", and then run the program. Run M-x realgud-track-mode and set the debugger to be gdbgdb.