diff -ur qemu-1.0/cpu-defs.h qemu-1.0-CSL373/cpu-defs.h
--- qemu-1.0/cpu-defs.h	2011-12-02 01:37:34.000000000 +0530
+++ qemu-1.0-CSL373/cpu-defs.h	2012-01-03 18:42:28.000000000 +0530
@@ -66,6 +66,7 @@
 #define EXCP_HLT        0x10001 /* hlt instruction reached */
 #define EXCP_DEBUG      0x10002 /* cpu stopped after a breakpoint or singlestep */
 #define EXCP_HALTED     0x10003 /* cpu is halted (waiting for external event) */
+#define EXCP_TRIPLE     0x10004 /* cpu encountered triple fault */
 
 #define TB_JMP_CACHE_BITS 12
 #define TB_JMP_CACHE_SIZE (1 << TB_JMP_CACHE_BITS)
diff -ur qemu-1.0/cpus.c qemu-1.0-CSL373/cpus.c
--- qemu-1.0/cpus.c	2011-12-02 01:37:34.000000000 +0530
+++ qemu-1.0-CSL373/cpus.c	2012-01-03 18:48:28.000000000 +0530
@@ -1037,6 +1037,16 @@
 
         if (cpu_can_run(env)) {
             r = tcg_cpu_exec(env);
+            if (r == EXCP_TRIPLE) {
+              cpu_dump_state(env, stderr, fprintf, 0);
+              fprintf(stderr, "Triple fault. Halting for inspection "
+                  "via QEMU monitor.\n");
+              if (gdbserver_running()) {
+                r = EXCP_DEBUG;
+              } else {
+                vm_stop(0);
+              }
+            }
             if (r == EXCP_DEBUG) {
                 cpu_handle_guest_debug(env);
                 break;
diff -ur qemu-1.0/gdbstub.c qemu-1.0-CSL373/gdbstub.c
--- qemu-1.0/gdbstub.c	2011-12-02 01:37:34.000000000 +0530
+++ qemu-1.0-CSL373/gdbstub.c	2012-01-03 18:42:28.000000000 +0530
@@ -2919,3 +2919,8 @@
     return 0;
 }
 #endif
+
+int gdbserver_running(void)
+{
+    return gdbserver_state != NULL;
+}
diff -ur qemu-1.0/gdbstub.h qemu-1.0-CSL373/gdbstub.h
--- qemu-1.0/gdbstub.h	2011-12-02 01:37:34.000000000 +0530
+++ qemu-1.0-CSL373/gdbstub.h	2012-01-03 18:42:28.000000000 +0530
@@ -24,6 +24,7 @@
 void gdb_signalled(CPUState *, int);
 void gdbserver_fork(CPUState *);
 #endif
+int gdbserver_running(void);
 /* Get or set a register.  Returns the size of the register.  */
 typedef int (*gdb_reg_cb)(CPUState *env, uint8_t *buf, int reg);
 void gdb_register_coprocessor(CPUState *env,
diff -ur qemu-1.0/target-i386/op_helper.c qemu-1.0-CSL373/target-i386/op_helper.c
--- qemu-1.0/target-i386/op_helper.c	2011-12-02 01:37:34.000000000 +0530
+++ qemu-1.0-CSL373/target-i386/op_helper.c	2012-01-03 18:42:28.000000000 +0530
@@ -1443,8 +1443,18 @@
 
         qemu_log_mask(CPU_LOG_RESET, "Triple fault\n");
 
+#if 0
         qemu_system_reset_request();
         return EXCP_HLT;
+#else
+        // QEMU traditionally resets the machine on triple fault
+        // because programs written for 286 protected mode would exit
+        // protected mode by intentionally triple faulting the machine
+        // (after setting the boot vector to point to their code).
+        // This sucks for debugging programs that were written after
+        // 1985, so we instead halt the machine for inspection.
+        return EXCP_TRIPLE;
+#endif
     }
 #endif