--- old/src/cpu/x86/vm/debug_x86.cpp	2014-11-26 07:18:19.028356000 +0100
+++ new/src/cpu/x86/vm/debug_x86.cpp	2014-11-26 07:18:18.250300000 +0100
@@ -32,3 +32,22 @@
 #include "utilities/top.hpp"
 
 void pd_ps(frame f) {}
+
+
+#ifndef PRODUCT
+// a sequence of bytes which, when used as opcodes, will cause a SIGILL
+const uint8_t illegal_instruction_sequence[8] = { 
+  #if defined(AMD64)
+    // 06 => invalid instruction for x64
+    0x06
+  #elif defined(IA32)
+    // Note: privileged instructions won't work, because they cause a SIGSEGV 
+    // on Linux, not a SIGILL. "0f 0e" and "0f 0f" are invalid opcodes which 
+    // will cause real SIGILL resp. EXCEPTION_ILLEGAL_INSTRUCTION.
+    0x0f, 0x0f,
+    // Note: just in case this does not work, use a HLT which should be privilegued.
+    0xF4
+  #endif
+};
+#endif
+