diff --git a/agent/src/share/classes/sun/jvm/hotspot/CLHSDB.java b/agent/src/share/classes/sun/jvm/hotspot/CLHSDB.java
index 5071235fa3e978ffaf0b948e07d8ea0c35fb5645..9e8d016dcc2e1f19eecb8b2ea7e7b685d5263610 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/CLHSDB.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/CLHSDB.java
@@ -31,13 +31,19 @@ import java.io.*;
 import java.util.*;
 
 public class CLHSDB {
+
+    public CLHSDB(JVMDebugger d) {
+        jvmDebugger = d;
+    }
+
     public static void main(String[] args) {
         new CLHSDB(args).run();
     }
 
-    private void run() {
-        // At this point, if pidText != null we are supposed to attach to it.
-        // Else, if execPath != null, it is the path of a jdk/bin/java
+    public void run() {
+        // If jvmDebugger is already set, we have been given a JVMDebugger.
+        // Otherwise, if pidText != null we are supposed to attach to it.
+        // Finally, if execPath != null, it is the path of a jdk/bin/java
         // and coreFilename is the pathname of a core file we are
         // supposed to attach to.
 
@@ -49,7 +55,9 @@ public class CLHSDB {
                 }
             });
 
-        if (pidText != null) {
+        if (jvmDebugger != null) {
+            attachDebugger(jvmDebugger);
+        } else if (pidText != null) {
             attachDebugger(pidText);
         } else if (execPath != null) {
             attachDebugger(execPath, coreFilename);
@@ -96,6 +104,7 @@ public class CLHSDB {
     // Internals only below this point
     //
     private HotSpotAgent agent;
+    private JVMDebugger jvmDebugger;
     private boolean      attached;
     // These had to be made data members because they are referenced in inner classes.
     private String pidText;
@@ -120,7 +129,7 @@ public class CLHSDB {
         case (1):
             if (args[0].equals("help") || args[0].equals("-help")) {
                 doUsage();
-                System.exit(0);
+                return;
             }
             // If all numbers, it is a PID to attach to
             // Else, it is a pathname to a .../bin/java for a core file.
@@ -142,10 +151,15 @@ public class CLHSDB {
         default:
             System.out.println("HSDB Error: Too many options specified");
             doUsage();
-            System.exit(1);
+            return;
         }
     }
 
+    private void attachDebugger(JVMDebugger d) {
+        agent.attach(d);
+        attached = true;
+     }
+
     /** NOTE we are in a different thread here than either the main
         thread or the Swing/AWT event handler thread, so we must be very
         careful when creating or removing widgets */
diff --git a/agent/src/share/classes/sun/jvm/hotspot/CommandProcessor.java b/agent/src/share/classes/sun/jvm/hotspot/CommandProcessor.java
index 2233844267c6d6f36127c1ff758943f99bba86e7..1840caf9313dba56a4cb02a5d4be275dcef4c4c2 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/CommandProcessor.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/CommandProcessor.java
@@ -101,6 +101,9 @@ import sun.jvm.hotspot.utilities.soql.JSJavaFactoryImpl;
 import sun.jvm.hotspot.utilities.soql.JSJavaScriptEngine;
 
 public class CommandProcessor {
+
+    volatile boolean quit;
+
     public abstract static class DebuggerInterface {
         public abstract HotSpotAgent getAgent();
         public abstract boolean isAttached();
@@ -1135,7 +1138,7 @@ public class CommandProcessor {
                     usage();
                 } else {
                     debugger.detach();
-                    System.exit(0);
+                    quit = true;
                 }
             }
         },
@@ -1714,7 +1717,7 @@ public class CommandProcessor {
                         }
                         protected void quit() {
                             debugger.detach();
-                            System.exit(0);
+                            quit = true;
                         }
                         protected BufferedReader getInputReader() {
                             return in;
@@ -1781,7 +1784,7 @@ public class CommandProcessor {
 
     public void run(boolean prompt) {
         // Process interactive commands.
-        while (true) {
+        while (!quit) {
             if (prompt) printPrompt();
             String ln = null;
             try {
diff --git a/agent/src/share/classes/sun/jvm/hotspot/HSDB.java b/agent/src/share/classes/sun/jvm/hotspot/HSDB.java
index 5143408c68758e3ae650e69b5f08eb1ebcae48ef..d50cbaa5140bfb4e039984437250f6ab6226227c 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/HSDB.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/HSDB.java
@@ -59,8 +59,11 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
   // Internals only below this point
   //
   private HotSpotAgent agent;
+  private JVMDebugger jvmDebugger;
   private JDesktopPane desktop;
   private boolean      attached;
+  private boolean      argError;
+  private JFrame frame;
   /** List <JMenuItem> */
   private java.util.List attachMenuItems;
   /** List <JMenuItem> */
@@ -85,6 +88,11 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
     System.out.println("           path-to-corefile:        Debug this corefile.  The default is 'core'");
     System.out.println("        If no arguments are specified, you can select what to do from the GUI.\n");
     HotSpotAgent.showUsage();
+    argError = true;
+  }
+
+  public HSDB(JVMDebugger d) {
+    jvmDebugger = d;
   }
 
   private HSDB(String[] args) {
@@ -95,7 +103,6 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
     case (1):
       if (args[0].equals("help") || args[0].equals("-help")) {
         doUsage();
-        System.exit(0);
       }
       // If all numbers, it is a PID to attach to
       // Else, it is a pathname to a .../bin/java for a core file.
@@ -117,24 +124,29 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
     default:
       System.out.println("HSDB Error: Too many options specified");
       doUsage();
-      System.exit(1);
     }
   }
 
-  private void run() {
-    // At this point, if pidText != null we are supposed to attach to it.
-    // Else, if execPath != null, it is the path of a jdk/bin/java
-    // and coreFilename is the pathname of a core file we are
-    // supposed to attach to.
+  // close this tool without calling System.exit
+  protected void closeUI() {
+      workerThread.shutdown();
+      frame.dispose();
+  }
+
+  public void run() {
+    // Don't start the UI if there were bad arguments.
+    if (argError) {
+        return;
+    }
 
     agent = new HotSpotAgent();
     workerThread = new WorkerThread();
     attachMenuItems = new java.util.ArrayList();
     detachMenuItems = new java.util.ArrayList();
 
-    JFrame frame = new JFrame("HSDB - HotSpot Debugger");
+    frame = new JFrame("HSDB - HotSpot Debugger");
     frame.setSize(800, 600);
-    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
+    frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
 
     JMenuBar menuBar = new JMenuBar();
 
@@ -197,7 +209,7 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
     item = createMenuItem("Exit",
                             new ActionListener() {
                                 public void actionPerformed(ActionEvent e) {
-                                  System.exit(0);
+                                  closeUI();
                                 }
                               });
     item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, ActionEvent.ALT_MASK));
@@ -406,7 +418,15 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
         }
       });
 
-    if (pidText != null) {
+    // If jvmDebugger is already set, we have been given a JVMDebugger.
+    // Otherwise, if pidText != null we are supposed to attach to it.
+    // Finally, if execPath != null, it is the path of a jdk/bin/java
+    // and coreFilename is the pathname of a core file we are
+    // supposed to attach to.
+
+    if (jvmDebugger != null) {
+      attach(jvmDebugger);
+    } else if (pidText != null) {
       attach(pidText);
     } else if (execPath != null) {
       attach(execPath, coreFilename);
@@ -1113,6 +1133,12 @@ public class HSDB implements ObjectHistogramPanel.Listener, SAListener {
       });
   }
 
+  // Attach to existing JVMDebugger, which should be already attached to a core/process.
+  private void attach(JVMDebugger d) {
+    attached = true;
+    showThreadsDialog();
+  }
+
   /** NOTE we are in a different thread here than either the main
       thread or the Swing/AWT event handler thread, so we must be very
       careful when creating or removing widgets */
diff --git a/agent/src/share/classes/sun/jvm/hotspot/HotSpotAgent.java b/agent/src/share/classes/sun/jvm/hotspot/HotSpotAgent.java
index bdf9bd369e62c7d2aa85b285129f22001325e1ee..c963350591da2066db6201364eeb1207ded186ab 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/HotSpotAgent.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/HotSpotAgent.java
@@ -25,6 +25,8 @@
 package sun.jvm.hotspot;
 
 import java.rmi.RemoteException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
 
 import sun.jvm.hotspot.debugger.Debugger;
 import sun.jvm.hotspot.debugger.DebuggerException;
@@ -63,7 +65,6 @@ public class HotSpotAgent {
 
     private String os;
     private String cpu;
-    private String fileSep;
 
     // The system can work in several ways:
     //  - Attaching to local process
@@ -155,6 +156,14 @@ public class HotSpotAgent {
         go();
     }
 
+    /** This uses a JVMDebugger that is already attached to the core or process */
+    public synchronized void attach(JVMDebugger d)
+    throws DebuggerException {
+        debugger = d;
+        isServer = false;
+        go();
+    }
+
     /** This attaches to a "debug server" on a remote machine; this
       remote server has already attached to a process or opened a
       core file and is waiting for RMI calls on the Debugger object to
@@ -303,28 +312,37 @@ public class HotSpotAgent {
             // server, but not client attaching to server)
             //
 
-            try {
-                os  = PlatformInfo.getOS();
-                cpu = PlatformInfo.getCPU();
-            }
-            catch (UnsupportedPlatformException e) {
-                throw new DebuggerException(e);
-            }
-            fileSep = System.getProperty("file.separator");
+            // Handle existing or alternate JVMDebugger:
+            // these will set os, cpu independently of our PlatformInfo implementation.
+            String alternateDebugger = System.getProperty("sa.altDebugger");
+            if (debugger != null) {
+                setupDebuggerExisting();
+
+            } else if (alternateDebugger != null) {
+                setupDebuggerAlternate(alternateDebugger);
 
-            if (os.equals("solaris")) {
-                setupDebuggerSolaris();
-            } else if (os.equals("win32")) {
-                setupDebuggerWin32();
-            } else if (os.equals("linux")) {
-                setupDebuggerLinux();
-            } else if (os.equals("bsd")) {
-                setupDebuggerBsd();
-            } else if (os.equals("darwin")) {
-                setupDebuggerDarwin();
             } else {
-                // Add support for more operating systems here
-                throw new DebuggerException("Operating system " + os + " not yet supported");
+                // Otherwise, os, cpu are those of our current platform:
+                try {
+                    os  = PlatformInfo.getOS();
+                    cpu = PlatformInfo.getCPU();
+                } catch (UnsupportedPlatformException e) {
+                   throw new DebuggerException(e);
+                }
+                if (os.equals("solaris")) {
+                    setupDebuggerSolaris();
+                } else if (os.equals("win32")) {
+                    setupDebuggerWin32();
+                } else if (os.equals("linux")) {
+                    setupDebuggerLinux();
+                } else if (os.equals("bsd")) {
+                    setupDebuggerBsd();
+                } else if (os.equals("darwin")) {
+                    setupDebuggerDarwin();
+                } else {
+                    // Add support for more operating systems here
+                    throw new DebuggerException("Operating system " + os + " not yet supported");
+                }
             }
 
             if (isServer) {
@@ -423,6 +441,41 @@ public class HotSpotAgent {
     // OS-specific debugger setup/connect routines
     //
 
+    // Use the existing JVMDebugger, as passed to our constructor.
+    // Retrieve os and cpu from that debugger, not the current platform.
+    private void setupDebuggerExisting() {
+
+        os = debugger.getOS();
+        cpu = debugger.getCPU();
+        setupJVMLibNames(os);
+        machDesc = debugger.getMachineDescription();
+    }
+
+    // Given a classname, load an alternate implementation of JVMDebugger.
+    private void setupDebuggerAlternate(String alternateName) {
+
+        try {
+            Class c = Class.forName(alternateName);
+            Constructor cons = c.getConstructor();
+            debugger = (JVMDebugger) cons.newInstance();
+            attachDebugger();
+            setupDebuggerExisting();
+
+        } catch (ClassNotFoundException cnfe) {
+            throw new DebuggerException("Cannot find alternate SA Debugger: '" + alternateName + "'");
+        } catch (NoSuchMethodException nsme) {
+            throw new DebuggerException("Alternate SA Debugger: '" + alternateName + "' has missing constructor.");
+        } catch (InstantiationException ie) {
+            throw new DebuggerException("Alternate SA Debugger: '" + alternateName + "' fails to initialise: ", ie);
+        } catch (IllegalAccessException iae) {
+            throw new DebuggerException("Alternate SA Debugger: '" + alternateName + "' fails to initialise: ", iae);
+        } catch (InvocationTargetException iae) {
+            throw new DebuggerException("Alternate SA Debugger: '" + alternateName + "' fails to initialise: ", iae);
+        }
+
+        System.err.println("Loaded alternate HotSpot SA Debugger: " + alternateName);
+    }
+
     //
     // Solaris
     //
@@ -466,6 +519,11 @@ public class HotSpotAgent {
         debugger = new RemoteDebuggerClient(remote);
         machDesc = ((RemoteDebuggerClient) debugger).getMachineDescription();
         os = debugger.getOS();
+        setupJVMLibNames(os);
+        cpu = debugger.getCPU();
+    }
+
+    private void setupJVMLibNames(String os) {
         if (os.equals("solaris")) {
             setupJVMLibNamesSolaris();
         } else if (os.equals("win32")) {
@@ -479,8 +537,6 @@ public class HotSpotAgent {
         } else {
             throw new RuntimeException("Unknown OS type");
         }
-
-        cpu = debugger.getCPU();
     }
 
     private void setupJVMLibNamesSolaris() {
diff --git a/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxAddress.java b/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxAddress.java
index 9e85e133b3a537c083a1249a0617ca1ba17e04ed..cff29ce8edc37e3f9ffa9ebe6ab578b4121512e1 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxAddress.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxAddress.java
@@ -26,11 +26,11 @@ package sun.jvm.hotspot.debugger.linux;
 
 import sun.jvm.hotspot.debugger.*;
 
-class LinuxAddress implements Address {
+public class LinuxAddress implements Address {
     protected LinuxDebugger debugger;
     protected long addr;
 
-    LinuxAddress(LinuxDebugger debugger, long addr) {
+    public LinuxAddress(LinuxDebugger debugger, long addr) {
         this.debugger = debugger;
         this.addr = addr;
     }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxOopHandle.java b/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxOopHandle.java
index 310acb88ac768b2fefe8b7c0571954a4a4b6d98a..99291aada294829c54735fd8ee54926f572a873e 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxOopHandle.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxOopHandle.java
@@ -26,8 +26,8 @@ package sun.jvm.hotspot.debugger.linux;
 
 import sun.jvm.hotspot.debugger.*;
 
-class LinuxOopHandle extends LinuxAddress implements OopHandle {
-  LinuxOopHandle(LinuxDebugger debugger, long addr) {
+public class LinuxOopHandle extends LinuxAddress implements OopHandle {
+  public LinuxOopHandle(LinuxDebugger debugger, long addr) {
     super(debugger, addr);
   }
 
diff --git a/agent/src/share/classes/sun/jvm/hotspot/runtime/VM.java b/agent/src/share/classes/sun/jvm/hotspot/runtime/VM.java
index 0a9d94368783a395b70c1d6405e9f66b6e8ff9c2..f84da894ac2de30064b42e4465a21e3678a6053f 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/runtime/VM.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/runtime/VM.java
@@ -246,7 +246,7 @@ public class VM {
      }
   }
 
-  private static final boolean disableDerivedPrinterTableCheck;
+  private static final boolean disableDerivedPointerTableCheck;
   private static final Properties saProps;
 
   static {
@@ -256,12 +256,12 @@ public class VM {
        url = VM.class.getClassLoader().getResource("sa.properties");
        saProps.load(new BufferedInputStream(url.openStream()));
      } catch (Exception e) {
-       throw new RuntimeException("Unable to load properties  " +
+       System.err.println("Unable to load properties  " +
                                   (url == null ? "null" : url.toString()) +
                                   ": " + e.getMessage());
      }
 
-     disableDerivedPrinterTableCheck = System.getProperty("sun.jvm.hotspot.runtime.VM.disableDerivedPointerTableCheck") != null;
+     disableDerivedPointerTableCheck = System.getProperty("sun.jvm.hotspot.runtime.VM.disableDerivedPointerTableCheck") != null;
   }
 
   private VM(TypeDataBase db, JVMDebugger debugger, boolean isBigEndian) {
@@ -371,7 +371,8 @@ public class VM {
   /** This is used by the debugging system */
   public static void initialize(TypeDataBase db, JVMDebugger debugger) {
     if (soleInstance != null) {
-      throw new RuntimeException("Attempt to initialize VM twice");
+      // Using multiple SA Tool classes in the same process creates a call here.
+      return;
     }
     soleInstance = new VM(db, debugger, debugger.getMachineDescription().isBigEndian());
 
@@ -683,7 +684,7 @@ public class VM {
 
   /** Returns true if C2 derived pointer table should be used, false otherwise */
   public boolean useDerivedPointerTable() {
-    return !disableDerivedPrinterTableCheck;
+    return !disableDerivedPointerTableCheck;
   }
 
   /** Returns the code cache; should not be used if is core build */
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/ClassLoaderStats.java b/agent/src/share/classes/sun/jvm/hotspot/tools/ClassLoaderStats.java
index 77f0f800445b8c1260c37905772fef43acc2f7ed..eeda376b1d65d3cc57418b9e62f1db07480064d2 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/ClassLoaderStats.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/ClassLoaderStats.java
@@ -41,6 +41,14 @@ import sun.jvm.hotspot.utilities.*;
 public class ClassLoaderStats extends Tool {
    boolean verbose = true;
 
+   public ClassLoaderStats() {
+      super();
+   }
+
+   public ClassLoaderStats(JVMDebugger d) {
+      super(d);
+   }
+
    public static void main(String[] args) {
       ClassLoaderStats cls = new ClassLoaderStats();
       cls.start(args);
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/FinalizerInfo.java b/agent/src/share/classes/sun/jvm/hotspot/tools/FinalizerInfo.java
index 79e6784a63e6569e7e56b5cc1674f9293ebf86a0..ed707b9ee8a424e996cabc3095259dd1f2215b2d 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/FinalizerInfo.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/FinalizerInfo.java
@@ -24,6 +24,7 @@
 
 package sun.jvm.hotspot.tools;
 
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.tools.*;
 
 import sun.jvm.hotspot.oops.*;
@@ -42,6 +43,15 @@ import java.util.Comparator;
  * summary of these objects in the form of a histogram.
  */
 public class FinalizerInfo extends Tool {
+
+    public FinalizerInfo() {
+        super();
+    }
+
+    public FinalizerInfo(JVMDebugger d) {
+        super(d);
+    }
+
     public static void main(String[] args) {
         FinalizerInfo finfo = new FinalizerInfo();
         finfo.start(args);
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/FlagDumper.java b/agent/src/share/classes/sun/jvm/hotspot/tools/FlagDumper.java
index effeabb582afd0ab169ed6c26987e4127095ec12..c8db6d6b044b7e04ac633e412621aa70acd94ee6 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/FlagDumper.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/FlagDumper.java
@@ -25,10 +25,19 @@
 package sun.jvm.hotspot.tools;
 
 import java.io.PrintStream;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.runtime.*;
 
 public class FlagDumper extends Tool {
 
+    public FlagDumper() {
+        super();
+    }
+
+    public FlagDumper(JVMDebugger d) {
+        super(d);
+    }
+
    public void run() {
       VM.Flag[] flags = VM.getVM().getCommandLineFlags();
       PrintStream out = System.out;
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/HeapDumper.java b/agent/src/share/classes/sun/jvm/hotspot/tools/HeapDumper.java
index 5a7c06618b9644b6813f8c00bfadee32338ea3df..c5af0ed005dae2885b5c087386489d6ee5d704ae 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/HeapDumper.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/HeapDumper.java
@@ -25,6 +25,7 @@
 package sun.jvm.hotspot.tools;
 
 import sun.jvm.hotspot.utilities.HeapHprofBinWriter;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import java.io.IOException;
 
 /*
@@ -42,6 +43,11 @@ public class HeapDumper extends Tool {
         this.dumpFile = dumpFile;
     }
 
+    public HeapDumper(String dumpFile, JVMDebugger d) {
+        super(d);
+        this.dumpFile = dumpFile;
+    }
+
     protected void printFlagsUsage() {
         System.out.println("    <no option>\tto dump heap to " +
             DEFAULT_DUMP_FILE);
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/HeapSummary.java b/agent/src/share/classes/sun/jvm/hotspot/tools/HeapSummary.java
index 8762165526953c539b7022edb85ce9d49ae87551..a0123dd4c999ded177bda02ae5cf82fe2a3c2975 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/HeapSummary.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/HeapSummary.java
@@ -29,12 +29,21 @@ import sun.jvm.hotspot.gc_interface.*;
 import sun.jvm.hotspot.gc_implementation.g1.*;
 import sun.jvm.hotspot.gc_implementation.parallelScavenge.*;
 import sun.jvm.hotspot.gc_implementation.shared.*;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.memory.*;
 import sun.jvm.hotspot.oops.*;
 import sun.jvm.hotspot.runtime.*;
 
 public class HeapSummary extends Tool {
 
+   public HeapSummary() {
+      super();
+   }
+
+   public HeapSummary(JVMDebugger d) {
+      super(d);
+   }
+
    public static void main(String[] args) {
       HeapSummary hs = new HeapSummary();
       hs.start(args);
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/JInfo.java b/agent/src/share/classes/sun/jvm/hotspot/tools/JInfo.java
index a9f6c0e9c90ac04e6cc06d2af8b923263774d4a3..f2452420744d78f530bc5b3d3a06c84681591f85 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/JInfo.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/JInfo.java
@@ -25,12 +25,21 @@
 package sun.jvm.hotspot.tools;
 
 import sun.jvm.hotspot.runtime.*;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 
 public class JInfo extends Tool {
+    public JInfo() {
+        super();
+    }
+
     public JInfo(int m) {
         mode = m;
     }
 
+    public JInfo(JVMDebugger d) {
+        super(d);
+    }
+
     protected boolean needsJavaPrefix() {
         return false;
     }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/JMap.java b/agent/src/share/classes/sun/jvm/hotspot/tools/JMap.java
index d9ea364edaadaf233f0fb12d67373024555224bc..f6f3c0741c04d0a45a940606da3d3468aad8376e 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/JMap.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/JMap.java
@@ -25,6 +25,7 @@
 package sun.jvm.hotspot.tools;
 
 import java.io.*;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.utilities.*;
 
 public class JMap extends Tool {
@@ -36,6 +37,10 @@ public class JMap extends Tool {
         this(MODE_PMAP);
     }
 
+    public JMap(JVMDebugger d) {
+        super(d);
+    }
+
     protected boolean needsJavaPrefix() {
         return false;
     }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/JSnap.java b/agent/src/share/classes/sun/jvm/hotspot/tools/JSnap.java
index 95f46445f8a42cd49097e1971dd9eabed6673800..9301f1059fd3a3819003b2466d5a6f6a6b7e0c8c 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/JSnap.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/JSnap.java
@@ -25,9 +25,19 @@
 package sun.jvm.hotspot.tools;
 
 import java.io.*;
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.runtime.*;
 
 public class JSnap extends Tool {
+
+    public JSnap() {
+        super();
+    }
+
+    public JSnap(JVMDebugger d) {
+        super(d);
+    }
+
     public void run() {
         final PrintStream out = System.out;
         if (PerfMemory.initialized()) {
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/JStack.java b/agent/src/share/classes/sun/jvm/hotspot/tools/JStack.java
index 9e0688cf393239c024b0a568a76a5692b4a98972..7cbe8f4d94540386dbd0cb76327c4e1c56e1779d 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/JStack.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/JStack.java
@@ -24,6 +24,8 @@
 
 package sun.jvm.hotspot.tools;
 
+import sun.jvm.hotspot.debugger.JVMDebugger;
+
 public class JStack extends Tool {
     public JStack(boolean mixedMode, boolean concurrentLocks) {
         this.mixedMode = mixedMode;
@@ -34,6 +36,10 @@ public class JStack extends Tool {
         this(true, true);
     }
 
+    public JStack(JVMDebugger d) {
+        super(d);
+    }
+
     protected boolean needsJavaPrefix() {
         return false;
     }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/ObjectHistogram.java b/agent/src/share/classes/sun/jvm/hotspot/tools/ObjectHistogram.java
index f03469e13f1d6bf1eeba11e27d21acd81c8e21d1..168202eec2cef7a92e309443dd5a753e1dd61ea8 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/ObjectHistogram.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/ObjectHistogram.java
@@ -33,6 +33,14 @@ import java.io.PrintStream;
     an object histogram from a remote or crashed VM. */
 public class ObjectHistogram extends Tool {
 
+    public ObjectHistogram() {
+       super();
+    }
+
+    public ObjectHistogram(JVMDebugger d) {
+       super(d);
+    }
+
    public void run() {
       run(System.out, System.err);
    }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/PMap.java b/agent/src/share/classes/sun/jvm/hotspot/tools/PMap.java
index 70bd55513b9d2d60e1b1407e2cdfe1b10807e25d..2a234130991cf204564c744559056617f17929b7 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/PMap.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/PMap.java
@@ -31,6 +31,15 @@ import sun.jvm.hotspot.debugger.cdbg.*;
 import sun.jvm.hotspot.runtime.*;
 
 public class PMap extends Tool {
+
+   public PMap() {
+       super();
+   }
+
+   public PMap(JVMDebugger d) {
+       super(d);
+   }
+
    public void run() {
       run(System.out);
    }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/PStack.java b/agent/src/share/classes/sun/jvm/hotspot/tools/PStack.java
index 0b3720ff5941e16d3edaade8529091fc6ec93eb0..7f10612b3170fa29e814657e7841d608be04b9db 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/PStack.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/PStack.java
@@ -45,6 +45,10 @@ public class PStack extends Tool {
       this(true, true);
    }
 
+   public PStack(JVMDebugger d) {
+      super(d);
+   }
+
    public void run() {
       run(System.out);
    }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/StackTrace.java b/agent/src/share/classes/sun/jvm/hotspot/tools/StackTrace.java
index 83270bfdeff871cebe99c4eda9a5b444a33c1042..eb0cc88d116a071177ea5e514d967f82e0db6e5e 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/StackTrace.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/StackTrace.java
@@ -45,6 +45,16 @@ public class StackTrace extends Tool {
         run(System.out);
     }
 
+    public StackTrace(JVMDebugger d) {
+        super(d);
+    }
+
+    public StackTrace(JVMDebugger d, boolean v, boolean concurrentLocks) {
+        super(d);
+        this.verbose = v;
+        this.concurrentLocks = concurrentLocks;
+    }
+
     public void run(java.io.PrintStream tty) {
         // Ready to go with the database...
         try {
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/SysPropsDumper.java b/agent/src/share/classes/sun/jvm/hotspot/tools/SysPropsDumper.java
index bb4f703c64bf793975ef9df2bf73c34eab98c0d2..d601fef44010a510261395c799616d318dd9cf17 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/SysPropsDumper.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/SysPropsDumper.java
@@ -27,10 +27,19 @@ package sun.jvm.hotspot.tools;
 import java.io.PrintStream;
 import java.util.*;
 
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.runtime.*;
 
 public class SysPropsDumper extends Tool {
 
+   public SysPropsDumper() {
+      super();
+   }
+
+   public SysPropsDumper(JVMDebugger d) {
+      super(d);
+   }
+
    public void run() {
       Properties sysProps = VM.getVM().getSystemProperties();
       PrintStream out = System.out;
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/Tool.java b/agent/src/share/classes/sun/jvm/hotspot/tools/Tool.java
index 4279c425bd8383d9ecc54718391fd7f0ea50f6d1..3021801c9ddff28a2e36d5868b61b6d97b948a72 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/Tool.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/Tool.java
@@ -35,6 +35,7 @@ import sun.jvm.hotspot.debugger.*;
 
 public abstract class Tool implements Runnable {
    private HotSpotAgent agent;
+   private JVMDebugger jvmDebugger;
    private int debugeeType;
 
    // debugeeType is one of constants below
@@ -42,6 +43,13 @@ public abstract class Tool implements Runnable {
    protected static final int DEBUGEE_CORE   = 1;
    protected static final int DEBUGEE_REMOTE = 2;
 
+   public Tool() {
+   }
+
+   public Tool(JVMDebugger d) {
+      jvmDebugger = d;
+   }
+
    public String getName() {
       return getClass().getName();
    }
@@ -90,7 +98,6 @@ public abstract class Tool implements Runnable {
 
    protected void usage() {
       printUsage();
-      System.exit(1);
    }
 
    /*
@@ -106,13 +113,13 @@ public abstract class Tool implements Runnable {
    protected void stop() {
       if (agent != null) {
          agent.detach();
-         System.exit(0);
       }
    }
 
    protected void start(String[] args) {
       if ((args.length < 1) || (args.length > 2)) {
          usage();
+         return;
       }
 
       // Attempt to handle -h or -help or some invalid flag
@@ -185,13 +192,31 @@ public abstract class Tool implements Runnable {
         }
         if (e.getMessage() != null) {
           err.print(e.getMessage());
+          e.printStackTrace();
         }
         err.println();
-        System.exit(1);
+        return;
       }
 
       err.println("Debugger attached successfully.");
+      startInternal();
+   }
+
+   // When using an existing JVMDebugger.
+   public void start() {
 
+      if (jvmDebugger == null) {
+         throw new RuntimeException("Tool.start() called with no JVMDebugger set.");
+      }
+      agent = new HotSpotAgent();
+      agent.attach(jvmDebugger);
+      startInternal();
+   }
+
+   // Remains of the start mechanism, common to both start methods.
+   private void startInternal() {
+
+      PrintStream err = System.err;
       VM vm = VM.getVM();
       if (vm.isCore()) {
         err.println("Core build detected.");
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/jcore/ClassDump.java b/agent/src/share/classes/sun/jvm/hotspot/tools/jcore/ClassDump.java
index 34ccc102acbb7cdbef8e5d8652b7594866ca68af..96817b262261afd544cd5282642f2a7e337ce3e9 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/jcore/ClassDump.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/jcore/ClassDump.java
@@ -25,6 +25,7 @@
 package sun.jvm.hotspot.tools.jcore;
 
 import java.io.*;
+import java.lang.reflect.Constructor;
 import java.util.jar.JarOutputStream;
 import java.util.jar.JarEntry;
 import java.util.jar.Manifest;
@@ -38,6 +39,16 @@ public class ClassDump extends Tool {
     private ClassFilter classFilter;
     private String      outputDirectory;
     private JarOutputStream jarStream;
+    private String      pkgList;
+
+    public ClassDump() {
+        super();
+    }
+
+    public ClassDump(JVMDebugger d, String pkgList) {
+        super(d);
+        this.pkgList = pkgList;
+    }
 
     public void setClassFilter(ClassFilter cf) {
         classFilter = cf;
@@ -63,6 +74,25 @@ public class ClassDump extends Tool {
     public void run() {
         // Ready to go with the database...
         try {
+            // The name of the filter always comes from a System property.
+            // If we have a pkgList, pass it, otherwise let the filter read
+            // its own System property for the list of classes.
+            String filterClassName = System.getProperty("sun.jvm.hotspot.tools.jcore.filter",
+                                                        "sun.jvm.hotspot.tools.jcore.PackageNameFilter");
+            try {
+                Class filterClass = Class.forName(filterClassName);
+                if (pkgList == null) {
+                    classFilter = (ClassFilter) filterClass.newInstance();
+                } else {
+                    Constructor con = filterClass.getConstructor(String.class);
+                    classFilter = (ClassFilter) con.newInstance(pkgList);
+                }
+            } catch(Exception exp) {
+                System.err.println("Warning: Can not create class filter!");
+            }
+
+            String outputDirectory = System.getProperty("sun.jvm.hotspot.tools.jcore.outputDir", ".");
+            setOutputDirectory(outputDirectory);
 
             // walk through the system dictionary
             SystemDictionary dict = VM.getVM().getSystemDictionary();
@@ -139,26 +169,8 @@ public class ClassDump extends Tool {
     }
 
     public static void main(String[] args) {
-        // load class filters
-        ClassFilter classFilter = null;
-        String filterClassName = System.getProperty("sun.jvm.hotspot.tools.jcore.filter");
-        if (filterClassName != null) {
-            try {
-                Class filterClass = Class.forName(filterClassName);
-                classFilter = (ClassFilter) filterClass.newInstance();
-            } catch(Exception exp) {
-                System.err.println("Warning: Can not create class filter!");
-            }
-        }
-
-        String outputDirectory = System.getProperty("sun.jvm.hotspot.tools.jcore.outputDir");
-        if (outputDirectory == null)
-            outputDirectory = ".";
-
 
         ClassDump cd = new ClassDump();
-        cd.setClassFilter(classFilter);
-        cd.setOutputDirectory(outputDirectory);
         cd.start(args);
         cd.stop();
     }
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/soql/JSDB.java b/agent/src/share/classes/sun/jvm/hotspot/tools/soql/JSDB.java
index e46de0194d79b5b6b9974e024072bab5064dc62d..09874af178ef9c46a6a677fe5e24aa2c92bbdbdc 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/soql/JSDB.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/soql/JSDB.java
@@ -24,12 +24,22 @@
 
 package sun.jvm.hotspot.tools.soql;
 
+import sun.jvm.hotspot.debugger.JVMDebugger;
 import sun.jvm.hotspot.tools.*;
 import sun.jvm.hotspot.utilities.*;
 import sun.jvm.hotspot.utilities.soql.*;
 
 /** This is command line JavaScript debugger console */
 public class JSDB extends Tool {
+
+    public JSDB() {
+        super();
+    }
+
+    public JSDB(JVMDebugger d) {
+        super(d);
+    }
+
     public static void main(String[] args) {
         JSDB jsdb = new JSDB();
         jsdb.start(args);
diff --git a/agent/src/share/classes/sun/jvm/hotspot/tools/soql/SOQL.java b/agent/src/share/classes/sun/jvm/hotspot/tools/soql/SOQL.java
index 3a4c2470b1b5ecbbd48a093bd9e1cbc56e525387..b3054b90bd05ab58f90f0fb89a92ab71d47edf2a 100644
--- a/agent/src/share/classes/sun/jvm/hotspot/tools/soql/SOQL.java
+++ b/agent/src/share/classes/sun/jvm/hotspot/tools/soql/SOQL.java
@@ -44,6 +44,14 @@ public class SOQL extends Tool {
       soql.stop();
    }
 
+   public SOQL() {
+      super();
+   }
+
+   public SOQL(JVMDebugger d) {
+      super(d);
+   }
+
    protected SOQLEngine soqlEngine;
    protected BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    protected PrintStream out       = System.out;