X86: Make unrecognized instructions behave better in x86.

src/arch/x86/faults.cc

@@ -269,6 +269,13 @@ namespace X86ISA
 
 #else
 
+    void
+    InvalidOpcode::invoke(ThreadContext * tc, StaticInstPtr inst)
+    {
+        panic("Unrecognized/invalid instruction executed:\n %s",
+                inst->machInst);
+    }
+
     void
     PageFault::invoke(ThreadContext * tc, StaticInstPtr inst)
     {

src/arch/x86/faults.hh

@@ -250,6 +250,11 @@ namespace X86ISA
         InvalidOpcode() :
             X86Fault("Invalid-Opcode", "#UD", 6)
         {}
+
+#if !FULL_SYSTEM
+        void invoke(ThreadContext * tc,
+                StaticInstPtr inst = StaticInst::nullStaticInstPtr);
+#endif
     };
 
     class DeviceNotAvailable : public X86Fault

src/arch/x86/isa/formats/unknown.isa

@@ -77,8 +77,7 @@ output exec {{
         Fault Unknown::execute(%(CPU_exec_context)s *xc,
                 Trace::InstRecord *traceData) const
         {
-            warn("No instructions are implemented for X86!\n");
-            return NoFault;
+            return new InvalidOpcode();
         }
 }};