Create boottarball just like systemtarball

Change-Id: I97640bc973ab1d115499878a63bff48f80b326ec
Signed-off-by: Bruce Beare <brucex.j.beare@intel.com>
diff --git a/core/Makefile b/core/Makefile
index 142a2c1..628a8de 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -735,6 +735,34 @@
 stnod: systemtarball-nodeps
 
 
+#######
+## boot tarball
+define build-boottarball-target
+    $(hide) echo "Target boot fs tarball: $(INSTALLED_BOOTTARBALL_TARGET)
+    $(hide) mkdir -p $(PRODUCT_OUT)/boot
+    $(hide) cp -f $(INTERNAL_BOOTIMAGE_FILES) $(PRODUCT_OUT)/boot/.
+    $(hide) echo $(BOARD_KERNEL_CMDLINE) > $(PRODUCT_OUT)/boot/cmdline
+    $(hide) $(MKTARBALL) $(FS_GET_STATS) \
+                 $(PRODUCT_OUT) boot $(PRIVATE_BOOT_TAR) \
+                 $(INSTALLED_BOOTTARBALL_TARGET)
+endef
+
+ifndef BOOT_TARBALL_FORMAT
+    BOOT_TARBALL_FORMAT := bz2
+endif
+
+boot_tar := $(PRODUCT_OUT)/boot.tar
+INSTALLED_BOOTTARBALL_TARGET := $(boot_tar).$(BOOT_TARBALL_FORMAT)
+$(INSTALLED_BOOTTARBALL_TARGET): PRIVATE_BOOT_TAR := $(boot_tar)
+$(INSTALLED_BOOTTARBALL_TARGET): $(FS_GET_STATS) $(INTERNAL_BOOTIMAGE_FILES)
+	$(build-boottarball-target)
+
+.PHONY: boottarball-nodeps btnod
+boottarball-nodeps btnod: $(FS_GET_STATS) \
+                      $(filter-out boottarball-nodeps btnod,$(MAKECMDGOALS))
+	$(build-boottarball-target)
+
+
 # -----------------------------------------------------------------
 # data partition image
 INTERNAL_USERDATAIMAGE_FILES := \