diff --git a/updater/Android.mk b/updater/Android.mk
index 1159d7b..71a9a23 100644
--- a/updater/Android.mk
+++ b/updater/Android.mk
@@ -13,11 +13,47 @@ include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES := $(updater_src_files)
 
-LOCAL_STATIC_LIBRARIES := libapplypatch libedify libmtdutils libminzip libz
+LOCAL_STATIC_LIBRARIES := $(TARGET_RECOVERY_UPDATER_LIBS) $(TARGET_RECOVERY_UPDATER_EXTRA_LIBS)
+LOCAL_STATIC_LIBRARIES += libapplypatch libedify libmtdutils libminzip libz
 LOCAL_STATIC_LIBRARIES += libmincrypt libbz
 LOCAL_STATIC_LIBRARIES += libcutils libstdc++ libc
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/..
 
+# Each library in TARGET_RECOVERY_UPDATER_LIBS should have a function
+# named "Register_<libname>()".  Here we emit a little C function that
+# gets #included by updater.c.  It calls all those registration
+# functions.
+
+# Devices can also add libraries to TARGET_RECOVERY_UPDATER_EXTRA_LIBS.
+# These libs are also linked in with updater, but we don't try to call
+# any sort of registration function for these.  Use this variable for
+# any subsidiary static libraries required for your registered
+# extension libs.
+
+inc := $(call intermediates-dir-for,PACKAGING,updater_extensions)/register.inc
+
+# During the first pass of reading the makefiles, we dump the list of
+# extension libs to a temp file, then copy that to the ".list" file if
+# it is different than the existing .list (if any).  The register.inc
+# file then uses the .list as a prerequisite, so it is only rebuilt
+# (and updater.o recompiled) when the list of extension libs changes.
+
+junk := $(shell mkdir -p $(dir $(inc));\
+	        echo $(TARGET_RECOVERY_UPDATER_LIBS) > $(inc).temp;\
+	        diff -q $(inc).temp $(inc).list || cp -f $(inc).temp $(inc).list)
+
+$(inc) : libs := $(TARGET_RECOVERY_UPDATER_LIBS)
+$(inc) : $(inc).list
+	$(hide) mkdir -p $(dir $@)
+	$(hide) echo "" > $@
+	$(hide) $(foreach lib,$(libs),echo "extern void Register_$(lib)(void);" >> $@)
+	$(hide) echo "void RegisterDeviceExtensions() {" >> $@
+	$(hide) $(foreach lib,$(libs),echo "  Register_$(lib)();" >> $@)
+	$(hide) echo "}" >> $@
+
+$(call intermediates-dir-for,EXECUTABLES,updater)/updater.o : $(inc)
+LOCAL_C_INCLUDES += $(dir $(inc))
+
 LOCAL_MODULE := updater
 
 LOCAL_FORCE_STATIC_EXECUTABLE := true
diff --git a/updater/updater.c b/updater/updater.c
index 31d93ae..1aa277c 100644
--- a/updater/updater.c
+++ b/updater/updater.c
@@ -23,6 +23,11 @@
 #include "install.h"
 #include "minzip/Zip.h"
 
+// Generated by the makefile, this function defines the
+// RegisterDeviceExtensions() function, which calls all the
+// registration functions for device-specific extensions.
+#include "register.inc"
+
 // Where in the package we expect to find the edify script to execute.
 // (Note it's "updateR-script", not the older "update-script".)
 #define SCRIPT_NAME "META-INF/com/google/android/updater-script"
@@ -76,6 +81,7 @@ int main(int argc, char** argv) {
 
     RegisterBuiltins();
     RegisterInstallFunctions();
+    RegisterDeviceExtensions();
     FinishRegistration();
 
     // Parse the script.