diff --git a/core/Makefile b/core/Makefile
index 641ff30..9a4c543 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1441,7 +1441,7 @@
 	$(hide) echo "use_set_metadata=1" >> $(zip_root)/META/misc_info.txt
 	$(hide) echo "multistage_support=1" >> $(zip_root)/META/misc_info.txt
 	$(hide) echo "update_rename_support=1" >> $(zip_root)/META/misc_info.txt
-	$(hide) echo "blockimgdiff_versions=1,2,3" >> $(zip_root)/META/misc_info.txt
+	$(hide) echo "blockimgdiff_versions=1,2" >> $(zip_root)/META/misc_info.txt
 ifneq ($(OEM_THUMBPRINT_PROPERTIES),)
 	# OTA scripts are only interested in fingerprint related properties
 	$(hide) echo "oem_fingerprint_properties=$(OEM_THUMBPRINT_PROPERTIES)" >> $(zip_root)/META/misc_info.txt
diff --git a/core/base_rules.mk b/core/base_rules.mk
index 38f04f1..99107ab 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -116,6 +116,8 @@
     partition_tag := _VENDOR
   else ifeq (true,$(LOCAL_OEM_MODULE))
     partition_tag := _OEM
+  else ifeq (true,$(LOCAL_ODM_MODULE))
+    partition_tag := _ODM
   else
     # The definition of should-install-to-system will be different depending
     # on which goal (e.g., sdk or just droid) is being built.
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 7837ae3..ed7771d 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -138,6 +138,7 @@
 LOCAL_NO_CRT:=
 LOCAL_PROPRIETARY_MODULE:=
 LOCAL_OEM_MODULE:=
+LOCAL_ODM_MODULE:=
 LOCAL_PRIVILEGED_MODULE:=
 LOCAL_MODULE_OWNER:=
 LOCAL_CTS_TEST_PACKAGE:=
diff --git a/core/envsetup.mk b/core/envsetup.mk
index 43774ea..3dfcfd6 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -107,6 +107,7 @@
 TARGET_COPY_OUT_SYSTEM := system
 TARGET_COPY_OUT_DATA := data
 TARGET_COPY_OUT_OEM := oem
+TARGET_COPY_OUT_ODM := odm
 TARGET_COPY_OUT_ROOT := root
 TARGET_COPY_OUT_RECOVERY := recovery
 ###########################################
@@ -341,7 +342,7 @@
 
 TARGET_OUT_OEM := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_OEM)
 TARGET_OUT_OEM_EXECUTABLES := $(TARGET_OUT_OEM)/bin
-ifneq ($(filter %64,$(TARGET_ARCH)),)
+ifeq ($(TARGET_IS_64_BIT),true)
 TARGET_OUT_OEM_SHARED_LIBRARIES := $(TARGET_OUT_OEM)/lib64
 else
 TARGET_OUT_OEM_SHARED_LIBRARIES := $(TARGET_OUT_OEM)/lib
@@ -355,6 +356,20 @@
 $(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_OEM_SHARED_LIBRARIES := $(TARGET_OUT_OEM)/lib
 $(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_OEM_APPS := $(TARGET_OUT_OEM_APPS)
 
+TARGET_OUT_ODM := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_ODM)
+TARGET_OUT_ODM_EXECUTABLES := $(TARGET_OUT_ODM)/bin
+ifeq ($(TARGET_IS_64_BIT),true)
+TARGET_OUT_ODM_SHARED_LIBRARIES := $(TARGET_OUT_ODM)/lib64
+else
+TARGET_OUT_ODM_SHARED_LIBRARIES := $(TARGET_OUT_ODM)/lib
+endif
+TARGET_OUT_ODM_APPS := $(TARGET_OUT_ODM)/app
+TARGET_OUT_ODM_ETC := $(TARGET_OUT_ODM)/etc
+
+$(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_ODM_EXECUTABLES := $(TARGET_OUT_ODM_EXECUTABLES)
+$(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_ODM_SHARED_LIBRARIES := $(TARGET_OUT_ODM)/lib
+$(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_ODM_APPS := $(TARGET_OUT_ODM_APPS)
+
 TARGET_OUT_UNSTRIPPED := $(PRODUCT_OUT)/symbols
 TARGET_OUT_EXECUTABLES_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/system/bin
 TARGET_OUT_SHARED_LIBRARIES_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)/system/lib
diff --git a/core/tasks/build_custom_images.mk b/core/tasks/build_custom_images.mk
new file mode 100644
index 0000000..263b81a
--- /dev/null
+++ b/core/tasks/build_custom_images.mk
@@ -0,0 +1,58 @@
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Build additional images requested by the product makefile.
+# This script gives the ability to build multiple additional images and you can
+# configure what modules/files to include in each image.
+# 1. Define PRODUCT_CUSTOM_IMAGE_MAKEFILES in your product makefile.
+#    PRODUCT_CUSTOM_IMAGE_MAKEFILES is a list of makefiles.
+#    Each makefile configures an image.
+#    For image configuration makefile foo/bar/xyz.mk, the built image file name
+#    will be xyz.img. So make sure they won't conflict.
+# 2. In each image's configuration makefile, you can define variables:
+#   - CUSTOM_IMAGE_MOUNT_POINT, the mount point, such as "oem", "odm" etc.
+#   - CUSTOM_IMAGE_PARTITION_SIZE
+#   - CUSTOM_IMAGE_FILE_SYSTEM_TYPE
+#   - CUSTOM_IMAGE_DICT_FILE, a text file defines a dictionary accepted by
+#     BuildImage() in tools/releasetools/build_image.py.
+#   - CUSTOM_IMAGE_MODULES, a list of module names you want to include in
+#     the image; Not only the module itself will be installed to proper path in
+#     the image, you can also piggyback additional files/directories with the
+#     module's LOCAL_PICKUP_FILES.
+#   - CUSTOM_IMAGE_COPY_FILES, a list of "<src>:<dest>" to be copied to the
+#     image. <dest> is relativ to the root of the image.
+#
+# To build all those images, run "make custom_images".
+
+ifneq ($(filter $(MAKECMDGOALS),custom_images),)
+
+.PHONY: custom_images
+
+custom_image_parameter_variables := \
+  CUSTOM_IMAGE_MOUNT_POINT \
+  CUSTOM_IMAGE_PARTITION_SIZE \
+  CUSTOM_IMAGE_FILE_SYSTEM_TYPE \
+  CUSTOM_IMAGE_DICT_FILE \
+  CUSTOM_IMAGE_MODULES \
+  CUSTOM_IMAGE_COPY_FILES \
+
+# We don't expect product makefile to inherit/override PRODUCT_CUSTOM_IMAGE_MAKEFILES,
+# so we don't put it in the _product_var_list.
+$(foreach mk, $(PRODUCT_CUSTOM_IMAGE_MAKEFILES),\
+  $(eval my_custom_imag_makefile := $(mk))\
+  $(eval include $(BUILD_SYSTEM)/tasks/tools/build_custom_image.mk))
+
+endif
diff --git a/core/tasks/tools/build_custom_image.mk b/core/tasks/tools/build_custom_image.mk
new file mode 100644
index 0000000..fa9cda2
--- /dev/null
+++ b/core/tasks/tools/build_custom_image.mk
@@ -0,0 +1,105 @@
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+
+# Define rule to build one custom image.
+# Input variables: my_custom_imag_makefile
+
+$(call clear-var-list, $(custom_image_parameter_variables))
+
+include $(my_custom_imag_makefile)
+
+my_custom_image_name := $(basename $(notdir $(my_custom_imag_makefile)))
+
+intermediates := $(call intermediates-dir-for,PACKAGING,$(my_custom_image_name))
+my_built_custom_image := $(intermediates)/$(my_custom_image_name).img
+my_staging_dir := $(intermediates)/$(my_custom_image_name)
+
+# Collect CUSTOM_IMAGE_MODULES's installd files and their PICKUP_FILES.
+my_built_modules :=
+my_copy_pairs :=
+my_pickup_files :=
+
+$(foreach m,$(CUSTOM_IMAGE_MODULES),\
+  $(eval _pickup_files := $(strip $(ALL_MODULES.$(m).PICKUP_FILES)\
+    $(ALL_MODULES.$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX).PICKUP_FILES)))\
+  $(eval _built_files := $(strip $(ALL_MODULES.$(m).BUILT_INSTALLED)\
+    $(ALL_MODULES.$(m)$(TARGET_2ND_ARCH_MODULE_SUFFIX).BUILT_INSTALLED)))\
+  $(if $(_pickup_files)$(_built_files),,\
+    $(warning Unknown installed file for module '$(m)'))\
+  $(eval my_pickup_files += $(_pickup_files))\
+  $(foreach i, $(_built_files),\
+    $(eval bui_ins := $(subst :,$(space),$(i)))\
+    $(eval ins := $(word 2,$(bui_ins)))\
+    $(if $(filter $(TARGET_OUT_ROOT)/%,$(ins)),\
+      $(eval bui := $(word 1,$(bui_ins)))\
+      $(eval my_built_modules += $(bui))\
+      $(eval my_copy_dest := $(patsubst $(PRODUCT_OUT)/%,%,$(ins)))\
+      $(eval my_copy_dest := $(subst /,$(space),$(my_copy_dest)))\
+      $(eval my_copy_dest := $(wordlist 2,999,$(my_copy_dest)))\
+      $(eval my_copy_dest := $(subst $(space),/,$(my_copy_dest)))\
+      $(eval my_copy_pairs += $(bui):$(my_staging_dir)/$(my_copy_dest)))\
+  ))
+
+# Collect CUSTOM_IMAGE_COPY_FILES.
+my_image_copy_files :=
+$(foreach f,$(CUSTOM_IMAGE_COPY_FILES),\
+  $(eval pair := $(subst :,$(space),$(f)))\
+  $(eval src := $(word 1,$(pair)))\
+  $(eval my_image_copy_files += $(src))\
+  $(eval my_copy_pairs += $(src):$(my_staging_dir)/$(word 2,$(pair))))
+
+$(my_built_custom_image): PRIVATE_INTERMEDIATES := $(intermediates)
+$(my_built_custom_image): PRIVATE_MOUNT_POINT := $(CUSTOM_IMAGE_MOUNT_POINT)
+$(my_built_custom_image): PRIVATE_PARTITION_SIZE := $(CUSTOM_IMAGE_PARTITION_SIZE)
+$(my_built_custom_image): PRIVATE_FILE_SYSTEM_TYPE := $(CUSTOM_IMAGE_FILE_SYSTEM_TYPE)
+$(my_built_custom_image): PRIVATE_STAGING_DIR := $(my_staging_dir)
+$(my_built_custom_image): PRIVATE_COPY_PAIRS := $(my_copy_pairs)
+$(my_built_custom_image): PRIVATE_PICKUP_FILES := $(my_pickup_files)
+$(my_built_custom_image): PRIVATE_DICT_FILE := $(CUSTOM_IMAGE_DICT_FILE)
+$(my_built_custom_image): $(INTERNAL_USERIMAGES_DEPS) $(my_built_modules) $(my_image_copy_files) \
+  $(CUSTOM_IMAGE_DICT_FILE)
+	@echo "Build image $@"
+	$(hide) rm -rf $(PRIVATE_INTERMEDIATES) && mkdir -p $(PRIVATE_INTERMEDIATES)
+	$(hide) rm -rf $(PRIVATE_STAGING_DIR) && mkdir -p $(PRIVATE_STAGING_DIR)
+	# Copy all the files.
+	$(hide) $(foreach p,$(PRIVATE_COPY_PAIRS),\
+	          $(eval pair := $(subst :,$(space),$(p)))\
+	          mkdir -p $(dir $(word 2,$(pair)));\
+	          cp -Rf $(word 1,$(pair)) $(word 2,$(pair));)
+	$(if $($(PRIVATE_PICKUP_FILES)),$(hide) cp -Rf $(PRIVATE_PICKUP_FILES) $(PRIVATE_STAGING_DIR))
+	# Generate the dict.
+	$(hide) echo "# For all accepted properties, see BuildImage() in tools/releasetools/build_image.py" > $(PRIVATE_INTERMEDIATES)/image_info.txt
+	$(hide) echo "mount_point=$(PRIVATE_MOUNT_POINT)" >> $(PRIVATE_INTERMEDIATES)/image_info.txt
+	$(hide) echo "fs_type=$(PRIVATE_FILE_SYSTEM_TYPE)" >> $(PRIVATE_INTERMEDIATES)/image_info.txt
+	$(hide) echo "partition_size=$(PRIVATE_PARTITION_SIZE)" >> $(PRIVATE_INTERMEDIATES)/image_info.txt
+	$(if $(PRIVATE_DICT_FILE),\
+	  $(hide) echo "# Properties from $(PRIVATE_DICT_FILE)" >> $(PRIVATE_INTERMEDIATES)/image_info.txt;\
+	  cat $(PRIVATE_DICT_FILE) >> $(PRIVATE_INTERMEDIATES)/image_info.txt)
+	# Generate the image.
+	$(hide) PATH=$(foreach p,$(INTERNAL_USERIMAGES_BINARY_PATHS),$(p):)$$PATH \
+	  ./build/tools/releasetools/build_image.py \
+	  $(PRIVATE_STAGING_DIR) $(PRIVATE_INTERMEDIATES)/image_info.txt $@
+
+my_installed_custom_image := $(PRODUCT_OUT)/$(notdir $(my_built_custom_image))
+$(my_installed_custom_image) : $(my_built_custom_image)
+	$(call copy-file-to-new-target-with-cp)
+
+.PHONY: $(my_custom_image_name)
+custom_images $(my_custom_image_name) : $(my_installed_custom_image)
+
+# Archive the built image.
+$(call dist-for-goals, $(my_custom_image_name) custom_images,$(my_installed_custom_image))
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index f3b2297..d87a032 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -41,7 +41,7 @@
   # which is the version that we reveal to the end user.
   # Update this value when the platform version changes (rather
   # than overriding it somewhere else).  Can be an arbitrary string.
-  PLATFORM_VERSION := 5.1.51
+  PLATFORM_VERSION := 5.1
 endif
 
 ifeq "" "$(PLATFORM_SDK_VERSION)"
diff --git a/tools/droiddoc/templates-sdk/docpage.cs b/tools/droiddoc/templates-sdk/docpage.cs
index d064222..09d48c8 100644
--- a/tools/droiddoc/templates-sdk/docpage.cs
+++ b/tools/droiddoc/templates-sdk/docpage.cs
@@ -195,8 +195,8 @@
 <?cs include:"trailer.cs" ?>
   <script src="https://developer.android.com/ytblogger_lists_unified.js" type="text/javascript"></script>
   <script src="<?cs var:toroot ?>jd_lists_unified.js?v=8" type="text/javascript"></script>
-  <script src="<?cs var:toroot ?>jd_extras.js?v=9" type="text/javascript"></script>
-  <script src="<?cs var:toroot ?>jd_collections.js?v=9" type="text/javascript"></script>
+  <script src="<?cs var:toroot ?>jd_extras.js?v=10" type="text/javascript"></script>
+  <script src="<?cs var:toroot ?>jd_collections.js?v=10" type="text/javascript"></script>
   <script src="<?cs var:toroot ?>jd_tag_helpers.js?v=5" type="text/javascript"></script>
 
 </body>
diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 5cf0f2d..7181475 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -190,14 +190,14 @@
 # original image.
 
 class BlockImageDiff(object):
-  def __init__(self, tgt, src=None, threads=None, version=3):
+  def __init__(self, tgt, src=None, threads=None, version=2):
     if threads is None:
       threads = multiprocessing.cpu_count() // 2
       if threads == 0: threads = 1
     self.threads = threads
     self.version = version
 
-    assert version in (1, 2, 3)
+    assert version in (1, 2)
 
     self.tgt = tgt
     if src is None:
@@ -244,15 +244,6 @@
     self.ComputePatches(prefix)
     self.WriteTransfers(prefix)
 
-  def HashBlocks(self, source, ranges):
-    data = source.ReadRangeSet(ranges)
-    ctx = sha1()
-
-    for p in data:
-      ctx.update(p)
-
-    return ctx.hexdigest()
-
   def WriteTransfers(self, prefix):
     out = []
 
@@ -281,15 +272,7 @@
           next_stash_id += 1
         stashes[s] = sid
         stashed_blocks += sr.size()
-        if self.version == 2:
-          out.append("stash %d %s\n" % (sid, sr.to_string_raw()))
-        else:
-          sh = self.HashBlocks(self.src, sr)
-          if sh in stashes:
-            stashes[sh] += 1
-          else:
-            stashes[sh] = 1
-            out.append("stash %s %s\n" % (sh, sr.to_string_raw()))
+        out.append("stash %d %s\n" % (sid, sr.to_string_raw()))
 
       if stashed_blocks > max_stashed_blocks:
         max_stashed_blocks = stashed_blocks
@@ -298,7 +281,7 @@
 
       if self.version == 1:
         src_string = xf.src_ranges.to_string_raw()
-      elif self.version >= 2:
+      elif self.version == 2:
 
         #   <# blocks> <src ranges>
         #     OR
@@ -315,18 +298,9 @@
           sid = stashes.pop(s)
           stashed_blocks -= sr.size()
           unstashed_src_ranges = unstashed_src_ranges.subtract(sr)
-          sh = self.HashBlocks(self.src, sr)
           sr = xf.src_ranges.map_within(sr)
           mapped_stashes.append(sr)
-          if self.version == 2:
-            src_string.append("%d:%s" % (sid, sr.to_string_raw()))
-          else:
-            assert sh in stashes
-            src_string.append("%s:%s" % (sh, sr.to_string_raw()))
-            stashes[sh] -= 1
-            if stashes[sh] == 0:
-              free_string.append("free %s\n" % (sh))
-              stashes.pop(sh)
+          src_string.append("%d:%s" % (sid, sr.to_string_raw()))
           heapq.heappush(free_stash_ids, sid)
 
         if unstashed_src_ranges:
@@ -342,7 +316,7 @@
 
         src_string = " ".join(src_string)
 
-      # all versions:
+      # both versions:
       #   zero <rangeset>
       #   new <rangeset>
       #   erase <rangeset>
@@ -356,11 +330,6 @@
       #   bsdiff patchstart patchlen <tgt rangeset> <src_string>
       #   imgdiff patchstart patchlen <tgt rangeset> <src_string>
       #   move <tgt rangeset> <src_string>
-      #
-      # version 3:
-      #   bsdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_string>
-      #   imgdiff patchstart patchlen srchash tgthash <tgt rangeset> <src_string>
-      #   move hash <tgt rangeset> <src_string>
 
       tgt_size = xf.tgt_ranges.size()
 
@@ -381,11 +350,6 @@
             out.append("%s %s %s\n" % (
                 xf.style,
                 xf.tgt_ranges.to_string_raw(), src_string))
-          elif self.version >= 3:
-            out.append("%s %s %s %s\n" % (
-                xf.style,
-                self.HashBlocks(self.tgt, xf.tgt_ranges),
-                xf.tgt_ranges.to_string_raw(), src_string))
           total += tgt_size
       elif xf.style in ("bsdiff", "imgdiff"):
         performs_read = True
@@ -399,13 +363,6 @@
           out.append("%s %d %d %s %s\n" % (
               xf.style, xf.patch_start, xf.patch_len,
               xf.tgt_ranges.to_string_raw(), src_string))
-        elif self.version >= 3:
-          out.append("%s %d %d %s %s %s %s\n" % (
-              xf.style,
-              xf.patch_start, xf.patch_len,
-              self.HashBlocks(self.src, xf.src_ranges),
-              self.HashBlocks(self.tgt, xf.tgt_ranges),
-              xf.tgt_ranges.to_string_raw(), src_string))
         total += tgt_size
       elif xf.style == "zero":
         assert xf.tgt_ranges
@@ -416,9 +373,6 @@
       else:
         raise ValueError, "unknown transfer style '%s'\n" % (xf.style,)
 
-      if free_string:
-        out.append("".join(free_string))
-
 
       # sanity check: abort if we're going to need more than 512 MB if
       # stash space
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index 55f0058..692ec93 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -379,23 +379,28 @@
   out_file = argv[2]
 
   glob_dict = LoadGlobalDict(glob_dict_file)
-  image_filename = os.path.basename(out_file)
-  mount_point = ""
-  if image_filename == "system.img":
-    mount_point = "system"
-  elif image_filename == "userdata.img":
-    mount_point = "data"
-  elif image_filename == "cache.img":
-    mount_point = "cache"
-  elif image_filename == "vendor.img":
-    mount_point = "vendor"
-  elif image_filename == "oem.img":
-    mount_point = "oem"
+  if "mount_point" in glob_dict:
+    # The caller knows the mount point and provides a dictionay needed by BuildImage().
+    image_properties = glob_dict
   else:
-    print >> sys.stderr, "error: unknown image file name ", image_filename
-    exit(1)
+    image_filename = os.path.basename(out_file)
+    mount_point = ""
+    if image_filename == "system.img":
+      mount_point = "system"
+    elif image_filename == "userdata.img":
+      mount_point = "data"
+    elif image_filename == "cache.img":
+      mount_point = "cache"
+    elif image_filename == "vendor.img":
+      mount_point = "vendor"
+    elif image_filename == "oem.img":
+      mount_point = "oem"
+    else:
+      print >> sys.stderr, "error: unknown image file name ", image_filename
+      exit(1)
 
-  image_properties = ImagePropFromGlobalDict(glob_dict, mount_point)
+    image_properties = ImagePropFromGlobalDict(glob_dict, mount_point)
+
   if not BuildImage(in_dir, image_properties, out_file):
     print >> sys.stderr, "error: failed to build %s from %s" % (out_file, in_dir)
     exit(1)