rocketchip: generate GraphML output

src/main/scala/util/GeneratorUtils.scala

@@ -117,9 +117,17 @@ trait GeneratorApp extends App with HasGeneratorUtilities {
   def generateConfigString {
     ConfigStringOutput.contents.foreach(c => writeOutputFile(td, s"${names.configs}.cfg", c))
   }
+
+  /** Output a global LazyModule topology for documentation purposes. */
+  def generateGraphML {
+    GraphMLOutput.contents.foreach(c => writeOutputFile(td, s"${names.configs}.graphml", c))
+  }
 }
 
 object ConfigStringOutput {
   var contents: Option[String] = None
 }
 
+object GraphMLOutput {
+  var contents: Option[String] = None
+}