=== modified file 'lisp/progmodes/gdb-mi.el'
--- lisp/progmodes/gdb-mi.el	2011-10-06 16:11:38 +0000
+++ lisp/progmodes/gdb-mi.el	2011-10-23 19:30:03 +0000
@@ -599,6 +599,29 @@
     (concat (gdb-gud-context-command ,cmd1 ,noall) " " ,cmd2)
     ,(when (not noarg) 'arg)))
 
+(defun gdb--interpreter-ok ()
+  "Whether the expected interpreter is being used.
+-1: Not checked.
+ 0: Incorrect interpreter.
+ 1: Correct interpreter."
+  (let* ((buffer gud-comint-buffer)
+         (process (get-buffer-process buffer))
+         (res (process-get process 'gdb--interpreter-ok)))
+    (if (equal res nil) -1 res)))
+
+(defun gdb--interpreter-check (string)
+  "Initial filter to check if a correct interpreter is being used."
+  (when (= (gdb--interpreter-ok) -1)
+    (let* ((target "=thread-group-added") ; first line in GDB/MI
+           (buffer gud-comint-buffer)
+           (process (get-buffer-process buffer)))
+      (if (or (> (length target) (length string))
+             (string= (substring string 0 (length target)) target))
+          (process-put process 'gdb--interpreter-ok 1)
+        (process-put process 'gdb--interpreter-ok 0))))
+  (when (= (gdb--interpreter-ok) 1)
+    (gud-gdbmi-marker-filter string)))
+
 ;;;###autoload
 (defun gdb (command-line)
   "Run gdb on program FILE in buffer *gud-FILE*.
@@ -663,8 +686,18 @@
     (gdb-restore-windows)
     (error
      "Multiple debugging requires restarting in text command mode"))
-  ;;
-  (gud-common-init command-line nil 'gud-gdbmi-marker-filter)
+
+  ;; Start gdb and check for the interpreter being used
+  (gud-common-init command-line nil 'gdb--interpreter-check)
+  (while (= (gdb--interpreter-ok) -1)   ; must wait until established
+    (sleep-for 1))
+  (unless (= (gdb--interpreter-ok) 1)
+    (setq-default gud-marker-filter 'gud-gdbmi-marker-filter)
+    (insert "\nerror: You must start gdb with the GDB/MI interface (i.e., \"gdb -i=mi\")\n")
+    (error "You must start gdb with the GDB/MI interface (i.e., \"gdb -i=mi\")"))
+  ;; Change to "standard" filter
+  (setq gud-marker-filter 'gud-gdbmi-marker-filter)
+
   (set (make-local-variable 'gud-minor-mode) 'gdbmi)
   (setq comint-input-sender 'gdb-send)
   (when (ring-empty-p comint-input-ring) ; cf shell-mode