Index: traphdlr.c
===================================================================
--- ntoskrnl/ke/i386/traphdlr.c	(revision 74238)
+++ ntoskrnl/ke/i386/traphdlr.c	(working copy)
@@ -419,11 +419,38 @@
                              TrapFrame);
 }
 
+static ULONG vdm_instructions;
+#define HISTORY_SIZE 100
+static USHORT last_cs[HISTORY_SIZE];
+static USHORT last_ip[HISTORY_SIZE];
+static ULONG history_index;
+
 DECLSPEC_NORETURN
 VOID
 FASTCALL
 KiTrap01Handler(IN PKTRAP_FRAME TrapFrame)
 {
+    /* Check for V86 debug event */
+    if (__builtin_expect(KiV86Trap(TrapFrame), 1))
+    {
+        /* Enter V86 trap */
+        KiEnterV86Trap(TrapFrame);
+
+        /* Must be a VDM process */
+        ASSERT(PsGetCurrentProcess()->VdmObjects);
+
+        ++vdm_instructions;
+
+        last_cs[history_index] = TrapFrame->SegCs;
+        last_ip[history_index] = TrapFrame->Eip;
+        history_index = (history_index + 1) % HISTORY_SIZE;
+
+        //DPRINT1("V86: %x:%x\n", TrapFrame->SegCs, TrapFrame->Eip);
+
+        /* Do a quick V86 exit if possible */
+        KiExitV86Trap(TrapFrame);
+    }
+
     /* Save trap frame */
     KiEnterTrap(TrapFrame);
 
@@ -1299,8 +1326,21 @@
     }
 #endif
     /* Check for VDM trap */
-    ASSERT((KiVdmTrap(TrapFrame)) == FALSE);
+    if (KiVdmTrap(TrapFrame))
+    {
+        ULONG i;
 
+        i = history_index;
+        do
+        {
+            DPRINT1("V86: %x:%x\n", last_cs[i], last_ip[i]);
+            i = (i + 1) % HISTORY_SIZE;
+        } while (i != history_index);
+        DPRINT1("Total instructions: %lu\n", vdm_instructions);
+
+        ASSERT((KiVdmTrap(TrapFrame)) == FALSE);
+    }
+
     /* Either kernel or user trap (non VDM) so dispatch exception */
     if (Status == STATUS_ACCESS_VIOLATION)
     {
@@ -1755,7 +1795,7 @@
 FASTCALL
 KiCheckForSListAddress(IN PKTRAP_FRAME TrapFrame)
 {
-    UNIMPLEMENTED;   
+    UNIMPLEMENTED;
 }
 
 /*