diff --git a/util/m5/Makefile.x86 b/util/m5/Makefile.x86
--- a/util/m5/Makefile.x86
+++ b/util/m5/Makefile.x86
@@ -33,6 +33,19 @@
 
 CFLAGS=-O2 -DM5OP_ADDR=0xFFFF0000
 OBJS=m5.o m5op_x86.o
+LIB_OBJS=m5op_x86.o
+JNI_OBJS=m5op_x86.o jni_gem5Op.o
+
+## FIXME: overwrite CFLAGS to get rid of M5OP_ADDR
+CFLAGS=-O2 -I$(JDK_PATH)/include/ -I$(JDK_PATH)/include/linux -fPIC
+LDFLAGS=-L. -lm5
+
+JC=javac
+JH=javah
+JR=jar
+### JDK_PATH must be set to build gem5OpJni
+#JDK_PATH=/path/to/jdk/version_number
+JDK_PATH=/usr/lib/jvm/java-1.6.0-openjdk.x86_64
 
 all: m5
 
@@ -42,8 +55,19 @@
 %.o: %.c
 	$(CC)  $(CFLAGS) -o $@ -c $<
 
-m5: $(OBJS)
-	$(CC) -o $@ $(OBJS)
+m5: $(OBJS) libm5.a
+	$(CC) -o $@ $(OBJS) $(LDFLAGS)
+
+libm5.a: $(LIB_OBJS)
+	$(AR) rcs $@ $<
+
+gem5OpJni: gem5OpJni.jar $(JNI_OBJS)
+	$(CC) -shared -o lib$@.so $(JNI_OBJS)
+
+gem5OpJni.jar:
+	$(JC) jni/gem5Op.java; \
+	$(JH) jni.gem5Op; \
+	$(JR) cvf $@ jni/*.class
 
 clean:
-	rm -f *.o m5
+	rm -f *.o m5 libgemOpJni.so gem5OpJni.jar jni/*.class