Index: xen-3.1-testing/tools/firmware/vmxassist/vm86.c
===================================================================
--- xen-3.1-testing.orig/tools/firmware/vmxassist/vm86.c
+++ xen-3.1-testing/tools/firmware/vmxassist/vm86.c
@@ -40,7 +40,7 @@ enum vm86_mode mode = 0;
 static struct regs saved_rm_regs;
 
 #ifdef DEBUG
-int traceset = 0;
+int traceset = 0xffffffff;
 
 char *states[] = {
 	"<VM86_REAL>",
@@ -164,6 +164,35 @@ address(struct regs *regs, unsigned seg,
 	return 0;
 }
 
+void
+panic_eip(struct regs *regs, char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vprintf(fmt, ap);
+	printf("\n");
+	va_end(ap);
+#ifdef DEBUG
+	if (regs->eflags & EFLAGS_VM) {
+		unsigned int range = 20;
+		unsigned int eip = address(regs, regs->cs, regs->eip);
+		unsigned int start = (eip < range) ? 0 : eip - range;
+		unsigned int stop = (eip > 0x100000 - range) ? 0x100000 : eip + range;
+		int size = (stop - start);
+		unsigned int i;
+		unsigned char data[size];
+
+		printf("Dumping %x..%x  eip=%x\n", start, stop, eip);
+		for (i = start; i < stop; ++i)
+			data[i-start] = *(unsigned char *) i;
+                hexdump(data, size);
+        }
+#else
+	regs = regs;
+#endif
+	halt();
+}
+
 #ifdef DEBUG
 void
 trace(struct regs *regs, int adjust, char *fmt, ...)
@@ -1636,7 +1665,7 @@ emulate(struct regs *regs)
 	/* detect the case where we are not making progress */
 	if (nemul == 0 && prev_eip == regs->eip) {
 		flteip = address(regs, MASK16(regs->cs), regs->eip);
-		panic("Unknown opcode at %04x:%04x=0x%x",
+		panic_eip(regs, "Unknown opcode at %04x:%04x=0x%x",
 			MASK16(regs->cs), regs->eip, flteip);
 	} else
 		prev_eip = regs->eip;
@@ -1662,7 +1691,7 @@ trap(int trapno, int errno, struct regs 
 			if (mode == VM86_REAL)
 				return;
 			if (mode != VM86_REAL_TO_PROTECTED)
-				panic("not in real-to-protected mode");
+				panic_eip(regs, "not in real-to-protected mode");
 			emulate(regs);
 			return;
 		}
@@ -1672,7 +1701,7 @@ trap(int trapno, int errno, struct regs 
 		if (regs->eflags & EFLAGS_VM) {
 			/* emulate any 8086 instructions  */
 			if (mode == VM86_PROTECTED)
-				panic("unexpected protected mode");
+				panic_eip(regs, "unexpected protected mode");
 			emulate(regs);
 			return;
 		}
Index: xen-3.1-testing/tools/firmware/rombios/rombios.c
===================================================================
--- xen-3.1-testing.orig/tools/firmware/rombios/rombios.c
+++ xen-3.1-testing/tools/firmware/rombios/rombios.c
@@ -131,18 +131,18 @@
 //
 //   BCC Bug: find a generic way to handle the bug of #asm after an "if"  (fixed in 0.16.7)
 
-#define DEBUG_ROMBIOS      0
+#define DEBUG_ROMBIOS      1
 
-#define DEBUG_ATA          0
-#define DEBUG_INT13_HD     0
-#define DEBUG_INT13_CD     0
-#define DEBUG_INT13_ET     0
-#define DEBUG_INT13_FL     0
-#define DEBUG_INT15        0
-#define DEBUG_INT16        0
-#define DEBUG_INT1A        0
-#define DEBUG_INT74        0
-#define DEBUG_APM          0
+#define DEBUG_ATA          1
+#define DEBUG_INT13_HD     1
+#define DEBUG_INT13_CD     1
+#define DEBUG_INT13_ET     1
+#define DEBUG_INT13_FL     1
+#define DEBUG_INT15        1
+#define DEBUG_INT16        1
+#define DEBUG_INT1A        1
+#define DEBUG_INT74        1
+#define DEBUG_APM          1
 
 #define BX_CPU           3
 #define BX_USE_PS2_MOUSE 1