diff --git a/libs/ui/BufferMapper.cpp b/libs/ui/BufferMapper.cpp
index c7e439c..e6ca239 100644
--- a/libs/ui/BufferMapper.cpp
+++ b/libs/ui/BufferMapper.cpp
@@ -36,14 +36,17 @@
 
 // ---------------------------------------------------------------------------
 // enable mapping debugging
-#define DEBUG_MAPPINGS           1
+#define DEBUG_MAPPINGS           0
 // never remove mappings from the list
-#define DEBUG_MAPPINGS_KEEP_ALL  1
+#define DEBUG_MAPPINGS_KEEP_ALL  0
 // ---------------------------------------------------------------------------
 
 namespace android {
 // ---------------------------------------------------------------------------
 
+template<class BufferMapper> Mutex Singleton<BufferMapper>::sLock; 
+template<> BufferMapper* Singleton<BufferMapper>::sInstance(0); 
+
 BufferMapper::BufferMapper()
     : mAllocMod(0)
 {
@@ -55,26 +58,26 @@
     }
 }
 
-status_t BufferMapper::map(buffer_handle_t handle, void** addr)
+status_t BufferMapper::map(buffer_handle_t handle, void** addr, const void* id)
 {
     Mutex::Autolock _l(mLock);
     status_t err = mAllocMod->map(mAllocMod, handle, addr);
     LOGW_IF(err, "map(...) failed %d (%s)", err, strerror(-err));
 #if DEBUG_MAPPINGS
     if (err == NO_ERROR)
-        logMapLocked(handle);
+        logMapLocked(handle, id);
 #endif
     return err;
 }
 
-status_t BufferMapper::unmap(buffer_handle_t handle)
+status_t BufferMapper::unmap(buffer_handle_t handle, const void* id)
 {
     Mutex::Autolock _l(mLock);
     status_t err = mAllocMod->unmap(mAllocMod, handle);
     LOGW_IF(err, "unmap(...) failed %d (%s)", err, strerror(-err));
 #if DEBUG_MAPPINGS
     if (err == NO_ERROR)
-        logUnmapLocked(handle);
+        logUnmapLocked(handle, id);
 #endif
     return err;
 }
@@ -94,49 +97,46 @@
     return err;
 }
 
-void BufferMapper::logMapLocked(buffer_handle_t handle)
+void BufferMapper::logMapLocked(buffer_handle_t handle, const void* id)
 {
     CallStack stack;
     stack.update(2);
     
     map_info_t info;
+    info.id = id;
+    info.stack = stack;
+    
     ssize_t index = mMapInfo.indexOfKey(handle);
     if (index >= 0) {
-        info = mMapInfo.valueAt(index);
-    }
-    
-    ssize_t stackIndex = info.callstacks.indexOfKey(stack);
-    if (stackIndex >= 0) {
-        info.callstacks.editValueAt(stackIndex) += 1;
+        Vector<map_info_t>& infos = mMapInfo.editValueAt(index);
+        infos.add(info);
     } else {
-        info.callstacks.add(stack, 1);
-    }
-    
-    if (index < 0) {
-        info.count = 1;
-        mMapInfo.add(handle, info);
-    } else {
-        info.count++;
-        mMapInfo.replaceValueAt(index, info);
+        Vector<map_info_t> infos;
+        infos.add(info);
+        mMapInfo.add(handle, infos);
     }
 }
 
-void BufferMapper::logUnmapLocked(buffer_handle_t handle)
+void BufferMapper::logUnmapLocked(buffer_handle_t handle, const void* id)
 {    
     ssize_t index = mMapInfo.indexOfKey(handle);
     if (index < 0) {
-        LOGE("unmapping %p which doesn't exist!", handle);
+        LOGE("unmapping %p which doesn't exist in our map!", handle);
         return;
     }
     
-    map_info_t& info = mMapInfo.editValueAt(index);
-    info.count--;
-    if (info.count == 0) {
-#if DEBUG_MAPPINGS_KEEP_ALL
-        info.callstacks.clear();
-#else
+    Vector<map_info_t>& infos = mMapInfo.editValueAt(index);
+    ssize_t count = infos.size();
+    for (int i=0 ; i<count ; ) {
+        if (infos[i].id == id) {
+            infos.removeAt(i);
+            --count;
+        } else {
+            ++i;
+        }
+    }
+    if (count == 0) {
         mMapInfo.removeItemsAt(index, 1);
-#endif
     }
 }
 
@@ -149,11 +149,11 @@
         return;
     }
     
-    const map_info_t& info = mMapInfo.valueAt(index);
-    LOGD("dumping buffer_handle_t %p mappings (count=%d)", handle, info.count);
-    for (size_t i=0 ; i<info.callstacks.size() ; i++) {
-        LOGD("#%d, count=%d", i, info.callstacks.valueAt(i));
-        info.callstacks.keyAt(i).dump();
+    const Vector<map_info_t>& infos = mMapInfo.valueAt(index);
+    ssize_t count = infos.size();
+    for (int i=0 ; i<count ; i++) {
+        LOGD("#%d", i);
+        infos[i].stack.dump();
     }
 }