mkbootimg: Support custom mkbootimg implementation

Support using custom mkbootimg to allow boards to specify custom
boot image formats. Also export this as the environment variable
MKBOOTIMG to the *_from_target_files releasetools scripts.

Change-Id: I2084273b1175de097fb7da5c4f2264ea8014d74f
Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>

core/Makefile

@@ -1267,7 +1267,8 @@ $(INTERNAL_OTA_PACKAGE_TARGET): KEY_CERT_PAIR := $(DEFAULT_KEY_CERT_PAIR)
 
 $(INTERNAL_OTA_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(DISTTOOLS)
 	@echo "Package OTA: $@"
-	$(hide) ./build/tools/releasetools/ota_from_target_files -v \
+	$(hide) MKBOOTIMG=$(BOARD_CUSTOM_MKBOOTIMG) \
+	   ./build/tools/releasetools/ota_from_target_files -v \
 	   -p $(HOST_OUT) \
 	   -k $(KEY_CERT_PAIR) \
 	   $(BUILT_TARGET_FILES_PACKAGE) $@
@@ -1295,7 +1296,8 @@ endif
 
 $(INTERNAL_UPDATE_PACKAGE_TARGET): $(BUILT_TARGET_FILES_PACKAGE) $(DISTTOOLS)
 	@echo "Package: $@"
-	$(hide) ./build/tools/releasetools/img_from_target_files -v \
+	$(hide) MKBOOTIMG=$(BOARD_CUSTOM_MKBOOTIMG) \
+	   ./build/tools/releasetools/img_from_target_files -v \
 	   -s $(extensions) \
 	   -p $(HOST_OUT) \
 	   $(BUILT_TARGET_FILES_PACKAGE) $@

core/config.mk

@@ -291,7 +291,11 @@ PROTOC := $(HOST_OUT_EXECUTABLES)/aprotoc$(HOST_EXECUTABLE_SUFFIX)
 SIGNAPK_JAR := $(HOST_OUT_JAVA_LIBRARIES)/signapk$(COMMON_JAVA_PACKAGE_SUFFIX)
 MKBOOTFS := $(HOST_OUT_EXECUTABLES)/mkbootfs$(HOST_EXECUTABLE_SUFFIX)
 MINIGZIP := $(HOST_OUT_EXECUTABLES)/minigzip$(HOST_EXECUTABLE_SUFFIX)
+ifeq (,$(strip $(BOARD_CUSTOM_MKBOOTIMG)))
 MKBOOTIMG := $(HOST_OUT_EXECUTABLES)/mkbootimg$(HOST_EXECUTABLE_SUFFIX)
+else
+MKBOOTIMG := $(BOARD_CUSTOM_MKBOOTIMG)
+endif
 MKYAFFS2 := $(HOST_OUT_EXECUTABLES)/mkyaffs2image$(HOST_EXECUTABLE_SUFFIX)
 APICHECK := $(HOST_OUT_EXECUTABLES)/apicheck$(HOST_EXECUTABLE_SUFFIX)
 FS_GET_STATS := $(HOST_OUT_EXECUTABLES)/fs_get_stats$(HOST_EXECUTABLE_SUFFIX)

tools/releasetools/common.py

@@ -287,7 +287,10 @@ def BuildBootableImage(sourcedir, fs_config_file, info_dict=None):
   assert p1.returncode == 0, "mkbootfs of %s ramdisk failed" % (targetname,)
   assert p2.returncode == 0, "minigzip of %s ramdisk failed" % (targetname,)
 
-  cmd = ["mkbootimg", "--kernel", os.path.join(sourcedir, "kernel")]
+  # use MKBOOTIMG from environ, or "mkbootimg" if empty or not set
+  mkbootimg = os.getenv('MKBOOTIMG') or "mkbootimg"
+
+  cmd = [mkbootimg, "--kernel", os.path.join(sourcedir, "kernel")]
 
   fn = os.path.join(sourcedir, "cmdline")
   if os.access(fn, os.F_OK):