diff --git a/core/Makefile b/core/Makefile
index 7975d3a..d4f662c 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -211,6 +211,40 @@
 	$(hide) mv $@.tmp $@
 
 # -----------------------------------------------------------------
+# Declare vendor ramdisk fragments
+INTERNAL_VENDOR_RAMDISK_FRAGMENTS :=
+
+# Validation check and assign default --ramdisk_type.
+$(foreach vendor_ramdisk_fragment,$(BOARD_VENDOR_RAMDISK_FRAGMENTS), \
+  $(if $(and $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS), \
+             $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).PREBUILT)), \
+    $(error Must not specify KERNEL_MODULE_DIRS for prebuilt vendor ramdisk fragment "$(vendor_ramdisk_fragment)": $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS))) \
+  $(eval VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).STAGING_DIR := $(call intermediates-dir-for,PACKAGING,vendor_ramdisk_fragment-stage-$(vendor_ramdisk_fragment))) \
+  $(eval VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).FILES :=) \
+  $(if $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS), \
+    $(if $(filter --ramdisk_type,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)),, \
+      $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_type DLKM))) \
+)
+
+# Create the "kernel module directory" to "vendor ramdisk fragment" inverse mapping.
+$(foreach vendor_ramdisk_fragment,$(BOARD_VENDOR_RAMDISK_FRAGMENTS), \
+  $(foreach kmd,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS), \
+    $(eval kmd_vrf := KERNEL_MODULE_DIR_VENDOR_RAMDISK_FRAGMENT_$(kmd)) \
+    $(if $($(kmd_vrf)),$(error Kernel module directory "$(kmd)" belongs to multiple vendor ramdisk fragments: "$($(kmd_vrf))" "$(vendor_ramdisk_fragment)", each kernel module directory should belong to exactly one or none vendor ramdisk fragment)) \
+    $(eval $(kmd_vrf) := $(vendor_ramdisk_fragment)) \
+  ) \
+)
+INTERNAL_VENDOR_RAMDISK_FRAGMENTS += $(BOARD_VENDOR_RAMDISK_FRAGMENTS)
+
+# Assign --ramdisk_name for each vendor ramdisk fragment.
+$(foreach vendor_ramdisk_fragment,$(INTERNAL_VENDOR_RAMDISK_FRAGMENTS), \
+  $(if $(filter --ramdisk_name,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)), \
+    $(error Must not specify --ramdisk_name for vendor ramdisk fragment: $(vendor_ramdisk_fragment))) \
+  $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_name $(vendor_ramdisk_fragment)) \
+  $(eval .KATI_READONLY := BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS) \
+)
+
+# -----------------------------------------------------------------
 # kernel modules
 
 # Depmod requires a well-formed kernel version so 0.0 is used as a placeholder.
@@ -415,38 +449,24 @@
   VENDOR_RAMDISK_STRIPPED_MODULE_STAGING_DIR :=
 endif
 
-# Create the "kernel module directory" to "vendor ramdisk fragment" inverse mapping.
-$(foreach vendor_ramdisk_fragment,$(BOARD_VENDOR_RAMDISK_FRAGMENTS), \
-  $(if $(and $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS), \
-             $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).PREBUILT)), \
-    $(error Must not specify KERNEL_MODULE_DIRS for prebuilt vendor ramdisk fragment "$(vendor_ramdisk_fragment)": $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS))) \
-  $(eval VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).STAGING_DIR := $(call intermediates-dir-for,PACKAGING,vendor_ramdisk_fragment-dlkm-$(vendor_ramdisk_fragment))) \
-  $(eval VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).FILES :=) \
-  $(foreach dir,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).KERNEL_MODULE_DIRS), \
-    $(eval kmd_vrf := KERNEL_MODULE_DIR_VENDOR_RAMDISK_FRAGMENT_$(dir)) \
-    $(if $($(kmd_vrf)),$(error Kernel module directory "$(dir)" belongs to multiple vendor ramdisk fragments: "$($(kmd_vrf))" "$(vendor_ramdisk_fragment)", each kernel module directory should belong to exactly one or none vendor ramdisk fragment)) \
-    $(eval $(kmd_vrf) := $(vendor_ramdisk_fragment)) \
-  ) \
-)
-
 BOARD_KERNEL_MODULE_DIRS += top
-$(foreach dir,$(BOARD_KERNEL_MODULE_DIRS), \
-  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,RECOVERY,$(TARGET_RECOVERY_ROOT_OUT),,modules.load.recovery,,$(dir))) \
-  $(eval vendor_ramdisk_fragment := $(KERNEL_MODULE_DIR_VENDOR_RAMDISK_FRAGMENT_$(dir))) \
+$(foreach kmd,$(BOARD_KERNEL_MODULE_DIRS), \
+  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,RECOVERY,$(TARGET_RECOVERY_ROOT_OUT),,modules.load.recovery,,$(kmd))) \
+  $(eval vendor_ramdisk_fragment := $(KERNEL_MODULE_DIR_VENDOR_RAMDISK_FRAGMENT_$(kmd))) \
   $(if $(vendor_ramdisk_fragment), \
     $(eval output_dir := $(VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).STAGING_DIR)) \
     $(eval result_var := VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).FILES) \
     $(eval ### else ###), \
     $(eval output_dir := $(TARGET_VENDOR_RAMDISK_OUT)) \
     $(eval result_var := ALL_DEFAULT_INSTALLED_MODULES)) \
-  $(eval $(result_var) += $(call build-image-kernel-modules-dir,VENDOR_RAMDISK,$(output_dir),,modules.load,$(VENDOR_RAMDISK_STRIPPED_MODULE_STAGING_DIR),$(dir))) \
-  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-vendor-ramdisk-recovery-load,$(dir))) \
-  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,VENDOR,$(if $(filter true,$(BOARD_USES_VENDOR_DLKMIMAGE)),$(TARGET_OUT_VENDOR_DLKM),$(TARGET_OUT_VENDOR)),vendor,modules.load,$(VENDOR_STRIPPED_MODULE_STAGING_DIR),$(dir))) \
-  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-vendor-charger-load,$(dir))) \
-  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,ODM,$(if $(filter true,$(BOARD_USES_ODM_DLKMIMAGE)),$(TARGET_OUT_ODM_DLKM),$(TARGET_OUT_ODM)),odm,modules.load,,$(dir))) \
+  $(eval $(result_var) += $(call build-image-kernel-modules-dir,VENDOR_RAMDISK,$(output_dir),,modules.load,$(VENDOR_RAMDISK_STRIPPED_MODULE_STAGING_DIR),$(kmd))) \
+  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-vendor-ramdisk-recovery-load,$(kmd))) \
+  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,VENDOR,$(if $(filter true,$(BOARD_USES_VENDOR_DLKMIMAGE)),$(TARGET_OUT_VENDOR_DLKM),$(TARGET_OUT_VENDOR)),vendor,modules.load,$(VENDOR_STRIPPED_MODULE_STAGING_DIR),$(kmd))) \
+  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-vendor-charger-load,$(kmd))) \
+  $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,ODM,$(if $(filter true,$(BOARD_USES_ODM_DLKMIMAGE)),$(TARGET_OUT_ODM_DLKM),$(TARGET_OUT_ODM)),odm,modules.load,,$(kmd))) \
   $(if $(filter true,$(BOARD_USES_RECOVERY_AS_BOOT)),\
-    $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-recovery-as-boot-load,$(dir))),\
-    $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,GENERIC_RAMDISK,$(TARGET_RAMDISK_OUT),,modules.load,,$(dir)))))
+    $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-recovery-as-boot-load,$(kmd))),\
+    $(eval ALL_DEFAULT_INSTALLED_MODULES += $(call build-image-kernel-modules-dir,GENERIC_RAMDISK,$(TARGET_RAMDISK_OUT),,modules.load,,$(kmd)))))
 
 # -----------------------------------------------------------------
 # Cert-to-package mapping.  Used by the post-build signing tools.
@@ -1083,17 +1103,12 @@
 INTERNAL_VENDOR_RAMDISK_FRAGMENT_TARGETS :=
 INTERNAL_VENDOR_RAMDISK_FRAGMENT_ARGS :=
 
-$(foreach vendor_ramdisk_fragment,$(BOARD_VENDOR_RAMDISK_FRAGMENTS), \
+$(foreach vendor_ramdisk_fragment,$(INTERNAL_VENDOR_RAMDISK_FRAGMENTS), \
   $(eval prebuilt_vendor_ramdisk_fragment_file := $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).PREBUILT)) \
   $(if $(prebuilt_vendor_ramdisk_fragment_file), \
     $(eval vendor_ramdisk_fragment_target := $(call build-prebuilt-vendor-ramdisk-fragment,$(vendor_ramdisk_fragment),$(prebuilt_vendor_ramdisk_fragment_file))) \
     $(eval ### else ###), \
-    $(eval vendor_ramdisk_fragment_target := $(call build-vendor-ramdisk-fragment,$(vendor_ramdisk_fragment))) \
-    $(if $(filter --ramdisk_type,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)),, \
-      $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_type DLKM))) \
-  $(if $(filter --ramdisk_name,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)), \
-    $(error Must not specify --ramdisk_name for vendor ramdisk fragment: $(vendor_ramdisk_fragment))) \
-  $(eval BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS += --ramdisk_name $(vendor_ramdisk_fragment)) \
+    $(eval vendor_ramdisk_fragment_target := $(call build-vendor-ramdisk-fragment,$(vendor_ramdisk_fragment)))) \
   $(eval INTERNAL_VENDOR_RAMDISK_FRAGMENT_TARGETS += $(vendor_ramdisk_fragment_target)) \
   $(eval INTERNAL_VENDOR_RAMDISK_FRAGMENT_ARGS += $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS) --vendor_ramdisk_fragment $(vendor_ramdisk_fragment_target)) \
 )
@@ -4887,9 +4902,9 @@
 	echo "$(BOARD_KERNEL_PAGESIZE)" > $(zip_root)/VENDOR_BOOT/pagesize
 endif
 	echo "$(INTERNAL_KERNEL_CMDLINE)" > $(zip_root)/VENDOR_BOOT/vendor_cmdline
-ifdef BOARD_VENDOR_RAMDISK_FRAGMENTS
-	echo "$(BOARD_VENDOR_RAMDISK_FRAGMENTS)" > "$(zip_root)/VENDOR_BOOT/vendor_ramdisk_fragments"
-	$(foreach vendor_ramdisk_fragment,$(BOARD_VENDOR_RAMDISK_FRAGMENTS), \
+ifdef INTERNAL_VENDOR_RAMDISK_FRAGMENTS
+	echo "$(INTERNAL_VENDOR_RAMDISK_FRAGMENTS)" > "$(zip_root)/VENDOR_BOOT/vendor_ramdisk_fragments"
+	$(foreach vendor_ramdisk_fragment,$(INTERNAL_VENDOR_RAMDISK_FRAGMENTS), \
 	  mkdir -p $(zip_root)/VENDOR_BOOT/RAMDISK_FRAGMENTS/$(vendor_ramdisk_fragment); \
 	  echo "$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)" > "$(zip_root)/VENDOR_BOOT/RAMDISK_FRAGMENTS/$(vendor_ramdisk_fragment)/mkbootimg_args"; \
 	  $(eval prebuilt_ramdisk := $(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).PREBUILT)) \
@@ -4899,7 +4914,7 @@
 	      $(VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).STAGING_DIR), \
 	      $(zip_root)/VENDOR_BOOT/RAMDISK_FRAGMENTS/$(vendor_ramdisk_fragment)/RAMDISK); \
 	  ))
-endif # BOARD_VENDOR_RAMDISK_FRAGMENTS != ""
+endif # INTERNAL_VENDOR_RAMDISK_FRAGMENTS != ""
 endif # INSTALLED_VENDOR_BOOTIMAGE_TARGET
 ifdef BUILDING_SYSTEM_IMAGE
 	@# Contents of the system image
diff --git a/core/board_config.mk b/core/board_config.mk
index a739784..9ae597e 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -25,6 +25,7 @@
 _board_strip_readonly_list += BOARD_HAVE_BLUETOOTH
 _board_strip_readonly_list += BOARD_INSTALLER_CMDLINE
 _board_strip_readonly_list += BOARD_KERNEL_CMDLINE
+_board_strip_readonly_list += BOARD_BOOT_HEADER_VERSION
 _board_strip_readonly_list += BOARD_BOOTCONFIG
 _board_strip_readonly_list += BOARD_KERNEL_BASE
 _board_strip_readonly_list += BOARD_USES_GENERIC_AUDIO
@@ -828,7 +829,14 @@
   ifdef BOARD_VENDOR_RAMDISK_FRAGMENTS
     $(error Should not set BOARD_VENDOR_RAMDISK_FRAGMENTS if not building vendor_boot image)
   endif
-endif
+else # BUILDING_VENDOR_BOOT_IMAGE
+  ifneq (,$(call math_lt,$(BOARD_BOOT_HEADER_VERSION),4))
+    ifdef BOARD_VENDOR_RAMDISK_FRAGMENTS
+      $(error Should not set BOARD_VENDOR_RAMDISK_FRAGMENTS if \
+        BOARD_BOOT_HEADER_VERSION is less than 4)
+    endif
+  endif
+endif # BUILDING_VENDOR_BOOT_IMAGE
 
 ifneq ($(words $(BOARD_VENDOR_RAMDISK_FRAGMENTS)),$(words $(sort $(BOARD_VENDOR_RAMDISK_FRAGMENTS))))
   $(error BOARD_VENDOR_RAMDISK_FRAGMENTS has duplicate entries: $(BOARD_VENDOR_RAMDISK_FRAGMENTS))