diff --git a/core/Makefile b/core/Makefile
index f377051..1972dc1 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -944,7 +944,7 @@
   $(hide) mkdir -p $(TARGET_RECOVERY_OUT)
   $(hide) mkdir -p $(TARGET_RECOVERY_ROOT_OUT)/etc $(TARGET_RECOVERY_ROOT_OUT)/sdcard $(TARGET_RECOVERY_ROOT_OUT)/tmp
   @echo Copying baseline ramdisk...
-  $(hide) rsync -a --exclude=etc --exclude=sdcard $(TARGET_ROOT_OUT) $(TARGET_RECOVERY_OUT) # "cp -Rf" fails to overwrite broken symlinks on Mac.
+  $(hide) rsync -a --exclude=etc --exclude=sdcard $(IGNORE_CACHE_LINK) $(TARGET_ROOT_OUT) $(TARGET_RECOVERY_OUT) # "cp -Rf" fails to overwrite broken symlinks on Mac.
   @echo Modifying ramdisk contents...
   $(hide) rm -f $(TARGET_RECOVERY_ROOT_OUT)/init*.rc
   $(hide) cp -f $(recovery_initrc) $(TARGET_RECOVERY_ROOT_OUT)/
@@ -1391,6 +1391,9 @@
 cacheimage-nodeps: | $(INTERNAL_USERIMAGES_DEPS)
 	$(build-cacheimage-target)
 
+else # BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
+# we need to ignore the broken cache link when doing the rsync
+IGNORE_CACHE_LINK := --exclude=cache
 endif # BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE
 
 
diff --git a/core/binary.mk b/core/binary.mk
index 918a28d..7b22903 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -629,57 +629,55 @@
 ## Compile the .proto files to .cc (or .c) and then to .o
 ###########################################################
 proto_sources := $(filter %.proto,$(my_src_files))
-proto_generated_objects :=
-proto_generated_headers :=
 ifneq ($(proto_sources),)
-proto_generated_sources_dir := $(generated_sources_dir)/proto
-proto_generated_obj_dir := $(intermediates)/proto
+proto_gen_dir := $(generated_sources_dir)/proto
 
+my_rename_cpp_ext :=
 ifneq (,$(filter nanopb-c nanopb-c-enable_malloc, $(LOCAL_PROTOC_OPTIMIZE_TYPE)))
 my_proto_source_suffix := .c
 my_proto_c_includes := external/nanopb-c
-my_protoc_flags := --nanopb_out=$(proto_generated_sources_dir) \
+my_protoc_flags := --nanopb_out=$(proto_gen_dir) \
     --plugin=external/nanopb-c/generator/protoc-gen-nanopb
 else
-my_proto_source_suffix := .cc
+my_proto_source_suffix := $(LOCAL_CPP_EXTENSION)
+ifneq ($(my_proto_source_suffix),.cc)
+# aprotoc is hardcoded to write out only .cc file.
+# We need to rename the extension to $(LOCAL_CPP_EXTENSION) if it's not .cc.
+my_rename_cpp_ext := true
+endif
 my_proto_c_includes := external/protobuf/src
 my_cflags += -DGOOGLE_PROTOBUF_NO_RTTI
-my_protoc_flags := --cpp_out=$(proto_generated_sources_dir)
+my_protoc_flags := --cpp_out=$(proto_gen_dir)
 endif
-my_proto_c_includes += $(proto_generated_sources_dir)
+my_proto_c_includes += $(proto_gen_dir)
 
 proto_sources_fullpath := $(addprefix $(LOCAL_PATH)/, $(proto_sources))
-proto_generated_sources := $(addprefix $(proto_generated_sources_dir)/, \
+proto_generated_cpps := $(addprefix $(proto_gen_dir)/, \
     $(patsubst %.proto,%.pb$(my_proto_source_suffix),$(proto_sources_fullpath)))
-proto_generated_headers := $(patsubst %.pb$(my_proto_source_suffix),%.pb.h, $(proto_generated_sources))
-proto_generated_objects := $(addprefix $(proto_generated_obj_dir)/, \
-    $(patsubst %.proto,%.pb.o,$(proto_sources_fullpath)))
-$(call track-src-file-obj,$(proto_sources),$(proto_generated_objects))
 
 # Ensure the transform-proto-to-cc rule is only defined once in multilib build.
-ifndef $(my_prefix)_$(LOCAL_MODULE_CLASS)_$(LOCAL_MODULE)_proto_defined
-$(proto_generated_sources): PRIVATE_PROTO_INCLUDES := $(TOP)
-$(proto_generated_sources): PRIVATE_PROTOC_FLAGS := $(LOCAL_PROTOC_FLAGS) $(my_protoc_flags)
-$(proto_generated_sources): $(proto_generated_sources_dir)/%.pb$(my_proto_source_suffix): %.proto $(PROTOC)
+ifndef $(my_host)$(LOCAL_MODULE_CLASS)_$(LOCAL_MODULE)_proto_defined
+$(proto_generated_cpps): PRIVATE_PROTO_INCLUDES := $(TOP)
+$(proto_generated_cpps): PRIVATE_PROTOC_FLAGS := $(LOCAL_PROTOC_FLAGS) $(my_protoc_flags)
+$(proto_generated_cpps): PRIVATE_RENAME_CPP_EXT := $(my_rename_cpp_ext)
+$(proto_generated_cpps): $(proto_gen_dir)/%.pb$(my_proto_source_suffix): %.proto $(my_protoc_deps) $(PROTOC)
 	$(transform-proto-to-cc)
 
-# This is just a dummy rule to make sure gmake doesn't skip updating the dependents.
-$(proto_generated_headers): $(proto_generated_sources_dir)/%.pb.h: $(proto_generated_sources_dir)/%.pb$(my_proto_source_suffix)
-	@echo "Updated header file $@."
-	$(hide) touch $@
-
-$(my_prefix)_$(LOCAL_MODULE_CLASS)_$(LOCAL_MODULE)_proto_defined := true
-endif  # transform-proto-to-cc rule included only once
-
-$(proto_generated_objects): PRIVATE_ARM_MODE := $(normal_objects_mode)
-$(proto_generated_objects): PRIVATE_ARM_CFLAGS := $(normal_objects_cflags)
-$(proto_generated_objects): $(proto_generated_obj_dir)/%.o: $(proto_generated_sources_dir)/%$(my_proto_source_suffix) $(proto_generated_headers)
-ifeq ($(my_proto_source_suffix),.c)
-	$(transform-$(PRIVATE_HOST)c-to-o)
-else
-	$(transform-$(PRIVATE_HOST)cpp-to-o)
+$(my_host)$(LOCAL_MODULE_CLASS)_$(LOCAL_MODULE)_proto_defined := true
 endif
-$(call include-depfiles-for-objs, $(proto_generated_objects))
+# Ideally we can generate the source directly into $(intermediates).
+# But many Android.mks assume the .pb.hs are in $(generated_sources_dir).
+# As a workaround, we make a copy in the $(intermediates).
+proto_intermediate_dir := $(intermediates)/proto
+proto_intermediate_cpps := $(patsubst $(proto_gen_dir)/%,$(proto_intermediate_dir)/%,\
+    $(proto_generated_cpps))
+$(proto_intermediate_cpps) : $(proto_intermediate_dir)/% : $(proto_gen_dir)/% | $(ACP)
+	@echo "Copy: $@"
+	$(copy-file-to-target)
+	$(hide) cp $(basename $<).h $(basename $@).h
+$(call track-src-file-gen,$(proto_sources),$(proto_intermediate_cpps))
+
+my_generated_sources += $(proto_intermediate_cpps)
 
 my_c_includes += $(my_proto_c_includes)
 # Auto-export the generated proto source dir.
@@ -897,7 +895,7 @@
 dotdot_arm_objects :=
 $(foreach s,$(dotdot_arm_sources),\
   $(eval $(call compile-dotdot-cpp-file,$(s),\
-  $(yacc_cpps) $(proto_generated_headers) $(my_additional_dependencies),\
+  $(my_additional_dependencies),\
   dotdot_arm_objects)))
 $(call track-src-file-obj,$(patsubst %,%.arm,$(dotdot_arm_sources)),$(dotdot_arm_objects))
 
@@ -905,7 +903,7 @@
 dotdot_objects :=
 $(foreach s,$(dotdot_sources),\
   $(eval $(call compile-dotdot-cpp-file,$(s),\
-    $(yacc_cpps) $(proto_generated_headers) $(my_additional_dependencies),\
+    $(my_additional_dependencies),\
     dotdot_objects)))
 $(call track-src-file-obj,$(dotdot_sources),$(dotdot_objects))
 
@@ -923,7 +921,6 @@
 ifneq ($(strip $(cpp_objects)),)
 $(cpp_objects): $(intermediates)/%.o: \
     $(TOPDIR)$(LOCAL_PATH)/%$(LOCAL_CPP_EXTENSION) \
-    $(yacc_cpps) $(proto_generated_headers) \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)cpp-to-o)
 $(call include-depfiles-for-objs, $(cpp_objects))
@@ -945,8 +942,7 @@
 $(gen_cpp_objects): PRIVATE_ARM_MODE := $(normal_objects_mode)
 $(gen_cpp_objects): PRIVATE_ARM_CFLAGS := $(normal_objects_cflags)
 $(gen_cpp_objects): $(intermediates)/%.o: \
-    $(intermediates)/%$(LOCAL_CPP_EXTENSION) $(yacc_cpps) \
-    $(proto_generated_headers) \
+    $(intermediates)/%$(LOCAL_CPP_EXTENSION) \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)cpp-to-o)
 $(call include-depfiles-for-objs, $(gen_cpp_objects))
@@ -1001,7 +997,7 @@
 dotdot_arm_objects :=
 $(foreach s,$(dotdot_arm_sources),\
   $(eval $(call compile-dotdot-c-file,$(s),\
-    $(yacc_cpps) $(proto_generated_headers) $(my_additional_dependencies),\
+    $(my_additional_dependencies),\
     dotdot_arm_objects)))
 $(call track-src-file-obj,$(patsubst %,%.arm,$(dotdot_arm_sources)),$(dotdot_arm_objects))
 
@@ -1009,7 +1005,7 @@
 dotdot_objects :=
 $(foreach s, $(dotdot_sources),\
   $(eval $(call compile-dotdot-c-file,$(s),\
-    $(yacc_cpps) $(proto_generated_headers) $(my_additional_dependencies),\
+    $(my_additional_dependencies),\
     dotdot_objects)))
 $(call track-src-file-obj,$(dotdot_sources),$(dotdot_objects))
 
@@ -1025,7 +1021,7 @@
 c_objects        := $(c_arm_objects) $(c_normal_objects)
 
 ifneq ($(strip $(c_objects)),)
-$(c_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.c $(yacc_cpps) $(proto_generated_headers) \
+$(c_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.c \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)c-to-o)
 $(call include-depfiles-for-objs, $(c_objects))
@@ -1046,7 +1042,7 @@
 # TODO: support compiling certain generated files as arm.
 $(gen_c_objects): PRIVATE_ARM_MODE := $(normal_objects_mode)
 $(gen_c_objects): PRIVATE_ARM_CFLAGS := $(normal_objects_cflags)
-$(gen_c_objects): $(intermediates)/%.o: $(intermediates)/%.c $(yacc_cpps) $(proto_generated_headers) \
+$(gen_c_objects): $(intermediates)/%.o: $(intermediates)/%.c \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)c-to-o)
 $(call include-depfiles-for-objs, $(gen_c_objects))
@@ -1061,7 +1057,7 @@
 $(call track-src-file-obj,$(objc_sources),$(objc_objects))
 
 ifneq ($(strip $(objc_objects)),)
-$(objc_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.m $(yacc_cpps) $(proto_generated_headers) \
+$(objc_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.m \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)m-to-o)
 $(call include-depfiles-for-objs, $(objc_objects))
@@ -1076,7 +1072,7 @@
 $(call track-src-file-obj,$(objcpp_sources),$(objcpp_objects))
 
 ifneq ($(strip $(objcpp_objects)),)
-$(objcpp_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.mm $(yacc_cpps) $(proto_generated_headers) \
+$(objcpp_objects): $(intermediates)/%.o: $(TOPDIR)$(LOCAL_PATH)/%.mm \
     $(my_additional_dependencies)
 	$(transform-$(PRIVATE_HOST)mm-to-o)
 $(call include-depfiles-for-objs, $(objcpp_objects))
@@ -1206,8 +1202,7 @@
     $(c_objects) \
     $(gen_c_objects) \
     $(objc_objects) \
-    $(objcpp_objects) \
-    $(proto_generated_objects)
+    $(objcpp_objects)
 
 new_order_normal_objects := $(foreach f,$(my_src_files),$(my_src_file_obj_$(f)))
 new_order_normal_objects += $(foreach f,$(my_gen_src_files),$(my_src_file_obj_$(f)))
@@ -1420,11 +1415,9 @@
 ###########################################################
 export_includes := $(intermediates)/export_includes
 $(export_includes): PRIVATE_EXPORT_C_INCLUDE_DIRS := $(my_export_c_include_dirs)
-# Make sure .pb.h are already generated before any dependent source files get compiled.
-# Similarly, the generated DBus headers need to exist before we export their location.
-# People are not going to consume the aidl generated cpp file, but the cpp file is
-# generated after the headers, so this is a convenient way to ensure the headers exist.
-$(export_includes) : $(LOCAL_MODULE_MAKEFILE_DEP) $(proto_generated_headers) $(dbus_generated_headers) $(aidl_gen_cpp) $(vts_gen_cpp)
+# By adding $(my_generated_sources) it makes sure the headers get generated
+# before any dependent source files get compiled.
+$(export_includes) : $(my_generated_sources) $(export_include_deps)
 	@echo Export includes file: $< -- $@
 	$(hide) mkdir -p $(dir $@) && rm -f $@.tmp
 ifdef my_export_c_include_dirs
diff --git a/core/definitions.mk b/core/definitions.mk
index e2d5de4..a46dfbc 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1169,6 +1169,9 @@
 	$(addprefix --proto_path=, $(PRIVATE_PROTO_INCLUDES)) \
 	$(PRIVATE_PROTOC_FLAGS) \
 	$<
+@# aprotoc outputs only .cc. Rename it to .cpp if necessary.
+$(if $(PRIVATE_RENAME_CPP_EXT),\
+  $(hide) mv $(basename $@).cc $@)
 endef
 
 
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 363a0d4..2d37850 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -91,7 +91,7 @@
     # assuming the device can only support APIs as of the previous official
     # public release.
     # This value will always be 0 for release builds.
-    PLATFORM_PREVIEW_SDK_VERSION := 4
+    PLATFORM_PREVIEW_SDK_VERSION := 1
   endif
 endif