diff --git a/core/Makefile b/core/Makefile
index 2d7144a98..46920b393 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -162,11 +162,19 @@ endif
 $(call dist-for-goals,sdk,$(API_FINGERPRINT))
 
 INSTALLED_RECOVERYIMAGE_TARGET :=
+# Build recovery image if
+# BUILDING_RECOVERY_IMAGE && !BOARD_USES_RECOVERY_AS_BOOT && !BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT.
+# If BOARD_USES_RECOVERY_AS_BOOT is true, leave empty because INSTALLED_BOOTIMAGE_TARGET is built
+#   with recovery resources.
+# If BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT is true, leave empty to build recovery resources
+#   but not the final recovery image.
 ifdef BUILDING_RECOVERY_IMAGE
 ifneq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
+ifneq ($(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT),true)
 INSTALLED_RECOVERYIMAGE_TARGET := $(PRODUCT_OUT)/recovery.img
 endif
 endif
+endif
 
 include $(BUILD_SYSTEM)/sysprop.mk
 
@@ -746,7 +754,19 @@ endif
 
 INTERNAL_KERNEL_CMDLINE := $(strip $(INTERNAL_KERNEL_CMDLINE) buildvariant=$(TARGET_BUILD_VARIANT) $(VERITY_KEYID))
 
-ifndef BUILDING_VENDOR_BOOT_IMAGE
+boot_uses_generic_kernel_image :=
+ifdef BUILDING_VENDOR_BOOT_IMAGE
+  # building vendor boot image, dtb/base/pagesize go there
+  boot_uses_generic_kernel_image := true
+else ifeq (true,$(BOARD_USES_GENERIC_KERNEL_IMAGE))
+  boot_uses_generic_kernel_image := true
+endif
+
+ifeq (true,$(boot_uses_generic_kernel_image))
+  ifdef GENERIC_KERNEL_CMDLINE
+    INTERNAL_BOOTIMAGE_ARGS += --cmdline "$(GENERIC_KERNEL_CMDLINE)"
+  endif
+else # boot_uses_generic_kernel_image != true
 ifdef BOARD_KERNEL_BASE
   INTERNAL_BOOTIMAGE_ARGS += --base $(BOARD_KERNEL_BASE)
 endif
@@ -756,12 +776,8 @@ endif
 ifdef INTERNAL_KERNEL_CMDLINE
   INTERNAL_BOOTIMAGE_ARGS += --cmdline "$(INTERNAL_KERNEL_CMDLINE)"
 endif
-else
-# building vendor boot image, dtb/base/pagesize go there
-ifdef GENERIC_KERNEL_CMDLINE
-  INTERNAL_BOOTIMAGE_ARGS += --cmdline "$(GENERIC_KERNEL_CMDLINE)"
-endif
-endif
+endif # boot_uses_generic_kernel_image == true
+boot_uses_generic_kernel_image :=
 
 INTERNAL_MKBOOTIMG_VERSION_ARGS := \
     --os_version $(PLATFORM_VERSION_LAST_STABLE) \
@@ -868,6 +884,12 @@ INSTALLED_BOOTIMAGE_TARGET :=
 endif # BOARD_PREBUILT_BOOTIMAGE
 endif # TARGET_NO_KERNEL
 
+# -----------------------------------------------------------------
+# declare recovery ramdisk files
+ifeq ($(BUILDING_RECOVERY_IMAGE),true)
+INTERNAL_RECOVERY_RAMDISK_FILES_TIMESTAMP := $(call intermediates-dir-for,PACKAGING,recovery)/ramdisk_files-timestamp
+endif
+
 # -----------------------------------------------------------------
 # vendor boot image
 ifeq ($(BUILDING_VENDOR_BOOT_IMAGE),true)
@@ -881,8 +903,14 @@ INTERNAL_VENDOR_RAMDISK_FILES := $(filter $(TARGET_VENDOR_RAMDISK_OUT)/%, \
     $(ALL_DEFAULT_INSTALLED_MODULES))
 
 INTERNAL_VENDOR_RAMDISK_TARGET := $(call intermediates-dir-for,PACKAGING,vendor-boot)/vendor-ramdisk.cpio$(RAMDISK_EXT)
+
+ifeq (true,$(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT))
+$(INTERNAL_VENDOR_RAMDISK_TARGET): $(INTERNAL_RECOVERY_RAMDISK_FILES_TIMESTAMP)
+$(INTERNAL_VENDOR_RAMDISK_TARGET): PRIVATE_ADDITIONAL_DIR := $(TARGET_RECOVERY_ROOT_OUT)
+endif
+
 $(INTERNAL_VENDOR_RAMDISK_TARGET): $(MKBOOTFS) $(INTERNAL_VENDOR_RAMDISK_FILES) | $(COMPRESSION_COMMAND_DEPS)
-	$(MKBOOTFS) -d $(TARGET_OUT) $(TARGET_VENDOR_RAMDISK_OUT) | $(COMPRESSION_COMMAND) > $@
+	$(MKBOOTFS) -d $(TARGET_OUT) $(TARGET_VENDOR_RAMDISK_OUT) $(PRIVATE_ADDITIONAL_DIR) | $(COMPRESSION_COMMAND) > $@
 
 ifdef BOARD_INCLUDE_DTB_IN_BOOTIMG
   INTERNAL_VENDOR_BOOTIMAGE_ARGS += --dtb $(INSTALLED_DTBIMAGE_TARGET)
@@ -1863,17 +1891,23 @@ endif
 
 ifeq (truetrue,$(strip $(BUILDING_VENDOR_BOOT_IMAGE))$(strip $(AB_OTA_UPDATER)))
   INTERNAL_RECOVERYIMAGE_ARGS := --ramdisk $(recovery_ramdisk)
+
+ifneq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
 ifdef GENERIC_KERNEL_CMDLINE
   INTERNAL_RECOVERYIMAGE_ARGS += --cmdline "$(GENERIC_KERNEL_CMDLINE)"
-endif
+endif # GENERIC_KERNEL_CMDLINE != ""
+endif # BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE != true
+
 else # not (BUILDING_VENDOR_BOOT_IMAGE and AB_OTA_UPDATER)
   INTERNAL_RECOVERYIMAGE_ARGS := \
       $(addprefix --second ,$(INSTALLED_2NDBOOTLOADER_TARGET)) \
       --ramdisk $(recovery_ramdisk)
 # Assumes this has already been stripped
+ifneq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
 ifdef INTERNAL_KERNEL_CMDLINE
   INTERNAL_RECOVERYIMAGE_ARGS += --cmdline "$(INTERNAL_KERNEL_CMDLINE)"
-endif
+endif # INTERNAL_KERNEL_CMDLINE != ""
+endif # BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE != true
 ifdef BOARD_KERNEL_BASE
   INTERNAL_RECOVERYIMAGE_ARGS += --base $(BOARD_KERNEL_BASE)
 endif
@@ -1898,7 +1932,7 @@ ifndef BOARD_RECOVERY_MKBOOTIMG_ARGS
   BOARD_RECOVERY_MKBOOTIMG_ARGS := $(BOARD_MKBOOTIMG_ARGS)
 endif
 
-$(recovery_ramdisk): $(MKBOOTFS) $(COMPRESSION_COMMAND_DEPS) \
+$(INTERNAL_RECOVERY_RAMDISK_FILES_TIMESTAMP): $(MKBOOTFS) $(COMPRESSION_COMMAND_DEPS) \
 	    $(INTERNAL_ROOT_FILES) \
 	    $(INSTALLED_RAMDISK_TARGET) \
 	    $(INTERNAL_RECOVERYIMAGE_FILES) \
@@ -1934,16 +1968,19 @@ $(recovery_ramdisk): $(MKBOOTFS) $(COMPRESSION_COMMAND_DEPS) \
 	  cp -f $(recovery_wipe) $(TARGET_RECOVERY_ROOT_OUT)/system/etc/recovery.wipe)
 	ln -sf prop.default $(TARGET_RECOVERY_ROOT_OUT)/default.prop
 	$(BOARD_RECOVERY_IMAGE_PREPARE)
+	$(hide) touch $@
+
+$(recovery_ramdisk): $(INTERNAL_RECOVERY_RAMDISK_FILES_TIMESTAMP)
 	$(MKBOOTFS) -d $(TARGET_OUT) $(TARGET_RECOVERY_ROOT_OUT) | $(COMPRESSION_COMMAND) > $(recovery_ramdisk)
 
 # $(1): output file
-# $(2): kernel file
+# $(2): optional kernel file
 define build-recoveryimage-target
   $(if $(filter true,$(PRODUCT_SUPPORTS_VBOOT)), \
-    $(MKBOOTIMG) --kernel $(2) $(INTERNAL_RECOVERYIMAGE_ARGS) \
+    $(MKBOOTIMG) $(if $(strip $(2)),--kernel $(strip $(2))) $(INTERNAL_RECOVERYIMAGE_ARGS) \
                  $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(BOARD_RECOVERY_MKBOOTIMG_ARGS) \
                  --output $(1).unsigned, \
-    $(MKBOOTIMG) --kernel $(2) $(INTERNAL_RECOVERYIMAGE_ARGS) \
+    $(MKBOOTIMG) $(if $(strip $(2)),--kernel $(strip $(2))) $(INTERNAL_RECOVERYIMAGE_ARGS) \
                  $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(BOARD_RECOVERY_MKBOOTIMG_ARGS) \
                  --output $(1))
   $(if $(filter true,$(PRODUCT_SUPPORTS_BOOT_SIGNER)),\
@@ -1995,7 +2032,8 @@ $(INSTALLED_BOOTIMAGE_TARGET): $(recoveryimage-deps)
 endif # BOARD_USES_RECOVERY_AS_BOOT
 
 $(INSTALLED_RECOVERYIMAGE_TARGET): $(recoveryimage-deps)
-	$(call build-recoveryimage-target, $@, $(recovery_kernel))
+	$(call build-recoveryimage-target, $@, \
+	  $(if $(filter true, $(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE)),, $(recovery_kernel)))
 
 ifdef RECOVERY_RESOURCE_ZIP
 $(RECOVERY_RESOURCE_ZIP): $(INSTALLED_RECOVERYIMAGE_TARGET) | $(ZIPTIME)
@@ -2007,7 +2045,8 @@ endif
 .PHONY: recoveryimage-nodeps
 recoveryimage-nodeps:
 	@echo "make $@: ignoring dependencies"
-	$(call build-recoveryimage-target, $(INSTALLED_RECOVERYIMAGE_TARGET), $(recovery_kernel))
+	$(call build-recoveryimage-target, $(INSTALLED_RECOVERYIMAGE_TARGET), \
+	  $(if $(filter true, $(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE)),, $(recovery_kernel)))
 
 else # BUILDING_RECOVERY_IMAGE
 RECOVERY_RESOURCE_ZIP :=
@@ -4153,6 +4192,9 @@ endif
 ifeq ($(BOARD_BOOTLOADER_IN_UPDATE_PACKAGE),true)
 	$(hide) echo "bootloader_in_update_package=true" >> $@
 endif
+ifeq ($(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE),true)
+	$(hide) echo "exclude_kernel_from_recovery_image=true" >> $@
+endif
 
 .PHONY: misc_info
 misc_info: $(INSTALLED_MISC_INFO_TARGET)
@@ -4211,8 +4253,11 @@ endif
 $(BUILT_TARGET_FILES_PACKAGE): $(updater_dep)
 
 # If we are using recovery as boot, output recovery files to BOOT/.
+# If we are moving recovery resources to vendor_boot, output recovery files to VENDOR_BOOT/.
 ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
 $(BUILT_TARGET_FILES_PACKAGE): PRIVATE_RECOVERY_OUT := BOOT
+else ifeq ($(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT),true)
+$(BUILT_TARGET_FILES_PACKAGE): PRIVATE_RECOVERY_OUT := VENDOR_BOOT
 else
 $(BUILT_TARGET_FILES_PACKAGE): PRIVATE_RECOVERY_OUT := RECOVERY
 endif
@@ -4423,7 +4468,7 @@ $(BUILT_TARGET_FILES_PACKAGE): \
 	@echo "Package target files: $@"
 	$(hide) rm -rf $@ $@.list $(zip_root)
 	$(hide) mkdir -p $(dir $@) $(zip_root)
-ifneq (,$(INSTALLED_RECOVERYIMAGE_TARGET)$(filter true,$(BOARD_USES_RECOVERY_AS_BOOT)))
+ifneq (,$(INSTALLED_RECOVERYIMAGE_TARGET)$(filter true,$(BOARD_USES_RECOVERY_AS_BOOT))$(filter true,$(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT)))
 	@# Components of the recovery image
 	$(hide) mkdir -p $(zip_root)/$(PRIVATE_RECOVERY_OUT)
 	$(hide) $(call package_files-copy-root, \
@@ -4431,12 +4476,14 @@ ifneq (,$(INSTALLED_RECOVERYIMAGE_TARGET)$(filter true,$(BOARD_USES_RECOVERY_AS_
 ifdef INSTALLED_KERNEL_TARGET
 ifneq (,$(filter true,$(BOARD_USES_RECOVERY_AS_BOOT)))
 	cp $(INSTALLED_KERNEL_TARGET) $(zip_root)/$(PRIVATE_RECOVERY_OUT)/
-else # BOARD_USES_RECOVERY_AS_BOOT not true
+else ifneq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
 	cp $(firstword $(INSTALLED_KERNEL_TARGET)) $(zip_root)/$(PRIVATE_RECOVERY_OUT)/kernel
 endif
 endif
 ifeq (truetrue,$(strip $(BUILDING_VENDOR_BOOT_IMAGE))$(strip $(AB_OTA_UPDATER)))
+ifneq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
 	echo "$(GENERIC_KERNEL_CMDLINE)" > $(zip_root)/$(PRIVATE_RECOVERY_OUT)/cmdline
+endif # BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE != true
 else # not (BUILDING_VENDOR_BOOT_IMAGE and AB_OTA_UPDATER)
 ifdef INSTALLED_2NDBOOTLOADER_TARGET
 	cp $(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/$(PRIVATE_RECOVERY_OUT)/second
@@ -4454,9 +4501,11 @@ endif
 ifdef INSTALLED_DTBIMAGE_TARGET
 	cp $(INSTALLED_DTBIMAGE_TARGET) $(zip_root)/$(PRIVATE_RECOVERY_OUT)/dtb
 endif
+ifneq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
 ifdef INTERNAL_KERNEL_CMDLINE
 	echo "$(INTERNAL_KERNEL_CMDLINE)" > $(zip_root)/$(PRIVATE_RECOVERY_OUT)/cmdline
-endif
+endif # INTERNAL_KERNEL_CMDLINE != ""
+endif # BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE != true
 ifdef BOARD_KERNEL_BASE
 	echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/$(PRIVATE_RECOVERY_OUT)/base
 endif
@@ -4479,23 +4528,25 @@ endif
 ifdef INSTALLED_KERNEL_TARGET
 	$(hide) cp $(INSTALLED_KERNEL_TARGET) $(zip_root)/BOOT/
 endif
-ifndef INSTALLED_VENDOR_BOOTIMAGE_TARGET
+ifdef INSTALLED_VENDOR_BOOTIMAGE_TARGET
+	echo "$(GENERIC_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
+else ifeq (true,$(BOARD_USES_GENERIC_KERNEL_IMAGE))
+	echo "$(GENERIC_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
+else # INSTALLED_VENDOR_BOOTIMAGE_TARGET == "" && BOARD_USES_GENERIC_KERNEL_IMAGE != true
+	echo "$(INTERNAL_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
 ifdef INSTALLED_2NDBOOTLOADER_TARGET
 	cp $(INSTALLED_2NDBOOTLOADER_TARGET) $(zip_root)/BOOT/second
 endif
 ifdef INSTALLED_DTBIMAGE_TARGET
 	cp $(INSTALLED_DTBIMAGE_TARGET) $(zip_root)/BOOT/dtb
 endif
-	echo "$(INTERNAL_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
 ifdef BOARD_KERNEL_BASE
 	echo "$(BOARD_KERNEL_BASE)" > $(zip_root)/BOOT/base
 endif
 ifdef BOARD_KERNEL_PAGESIZE
 	echo "$(BOARD_KERNEL_PAGESIZE)" > $(zip_root)/BOOT/pagesize
 endif
-else # INSTALLED_VENDOR_BOOTIMAGE_TARGET defined
-	echo "$(GENERIC_KERNEL_CMDLINE)" > $(zip_root)/BOOT/cmdline
-endif # INSTALLED_VENDOR_BOOTIMAGE_TARGET defined
+endif # INSTALLED_VENDOR_BOOTIMAGE_TARGET == "" && BOARD_USES_GENERIC_KERNEL_IMAGE != true
 endif # BOARD_USES_RECOVERY_AS_BOOT not true
 	$(hide) $(foreach t,$(INSTALLED_RADIOIMAGE_TARGET),\
 	            mkdir -p $(zip_root)/RADIO; \
diff --git a/core/board_config.mk b/core/board_config.mk
index 05b6b29c1..03d2b3e78 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -97,6 +97,19 @@ _board_strip_readonly_list += \
   BOARD_KERNEL_BINARIES \
   BOARD_KERNEL_MODULE_INTERFACE_VERSIONS \
 
+# Variables related to generic kernel image (GKI) and generic boot image
+# - BOARD_USES_GENERIC_KERNEL_IMAGE is the global variable that defines if the
+#   board uses GKI and generic boot image.
+#   Update mechanism of the boot image is not enforced by this variable.
+# - BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE controls whether the recovery image
+#   contains a kernel or not.
+# - BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT controls whether ramdisk
+#   recovery resources are built to vendor_boot.
+_board_strip_readonly_list += \
+  BOARD_USES_GENERIC_KERNEL_IMAGE \
+  BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE \
+  BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT \
+
 _build_broken_var_list := \
   BUILD_BROKEN_DUP_RULES \
   BUILD_BROKEN_DUP_SYSPROP \
@@ -364,6 +377,9 @@ BUILDING_RECOVERY_IMAGE :=
 ifeq ($(PRODUCT_BUILD_RECOVERY_IMAGE),)
   ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
     BUILDING_RECOVERY_IMAGE := true
+  else ifeq ($(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT),true)
+    # Set to true to build recovery resources for vendor_boot
+    BUILDING_RECOVERY_IMAGE := true
   else ifdef BOARD_RECOVERYIMAGE_PARTITION_SIZE
     ifeq (,$(filter true, $(TARGET_NO_KERNEL) $(TARGET_NO_RECOVERY)))
       BUILDING_RECOVERY_IMAGE := true
@@ -745,3 +761,25 @@ $(foreach m,$(filter-out BUILD_COPY_HEADERS,$(DEFAULT_ERROR_BUILD_MODULE_TYPES))
   $(if $(filter true,$(BUILD_BROKEN_USES_$(m))),\
     $(KATI_deprecated_var $(m),Please convert to Soong),\
     $(KATI_obsolete_var $(m),Please convert to Soong)))
+
+ifndef BUILDING_RECOVERY_IMAGE
+  ifeq (true,$(BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE))
+    $(error Should not set BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE if not building recovery image)
+  endif
+endif
+
+ifndef BUILDING_VENDOR_BOOT_IMAGE
+  ifeq (true,$(BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT))
+    $(error Should not set BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT if not building vendor_boot image)
+  endif
+endif
+
+# If BOARD_USES_GENERIC_KERNEL_IMAGE is set, BOARD_USES_RECOVERY_AS_BOOT must not be set.
+# Devices without a dedicated recovery partition uses BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT to
+# build recovery into vendor_boot.
+ifeq (true,$(BOARD_USES_GENERIC_KERNEL_IMAGE))
+  ifeq (true,$(BOARD_USES_RECOVERY_AS_BOOT))
+    $(error BOARD_USES_RECOVERY_AS_BOOT cannot be true if BOARD_USES_GENERIC_KERNEL_IMAGE is true. \
+      Use BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT instead)
+  endif
+endif
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 77d2021d8..acf98117d 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1287,23 +1287,27 @@ def _BuildBootableImage(image_name, sourcedir, fs_config_file, info_dict=None,
   for building the requested image.
   """
 
+  if info_dict is None:
+    info_dict = OPTIONS.info_dict
+
   # "boot" or "recovery", without extension.
   partition_name = os.path.basename(sourcedir).lower()
 
+  kernel = None
   if partition_name == "recovery":
-    kernel = "kernel"
+    if info_dict.get("exclude_kernel_from_recovery_image") == "true":
+      logger.info("Excluded kernel binary from recovery image.")
+    else:
+      kernel = "kernel"
   else:
     kernel = image_name.replace("boot", "kernel")
     kernel = kernel.replace(".img", "")
-  if not os.access(os.path.join(sourcedir, kernel), os.F_OK):
+  if kernel and not os.access(os.path.join(sourcedir, kernel), os.F_OK):
     return None
 
   if has_ramdisk and not os.access(os.path.join(sourcedir, "RAMDISK"), os.F_OK):
     return None
 
-  if info_dict is None:
-    info_dict = OPTIONS.info_dict
-
   img = tempfile.NamedTemporaryFile()
 
   if has_ramdisk:
@@ -1313,7 +1317,9 @@ def _BuildBootableImage(image_name, sourcedir, fs_config_file, info_dict=None,
   # 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)]
+  cmd = [mkbootimg]
+  if kernel:
+    cmd += ["--kernel", os.path.join(sourcedir, kernel)]
 
   fn = os.path.join(sourcedir, "second")
   if os.access(fn, os.F_OK):