Add BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE.

BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE removes kernel from the
recovery image.

Test: build recovery image and unpack_bootimg
Test: build target files and unpack_bootimg IMAGES/recovery.img
      on device with GKI and dedicated recovery partition.

Bug: 156098440

Change-Id: I5f37d74ed954b26fe3dd778708b6ab9cfdc51f1e

core/Makefile

@@ -1936,13 +1936,13 @@ $(recovery_ramdisk): $(MKBOOTFS) $(COMPRESSION_COMMAND_DEPS) \
 	$(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)),\
@@ -1994,7 +1994,8 @@ $(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)
@@ -2006,7 +2007,8 @@ 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 :=
@@ -4151,6 +4153,9 @@ 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: $(INSTALLED_MISC_INFO_TARGET)
@@ -4428,7 +4433,7 @@ ifneq (,$(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

core/board_config.mk

@@ -101,8 +101,11 @@ _board_strip_readonly_list += \
 # - 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_strip_readonly_list += \
   BOARD_USES_GENERIC_KERNEL_IMAGE \
+  BOARD_EXCLUDE_KERNEL_FROM_RECOVERY_IMAGE \
 
 _build_broken_var_list := \
   BUILD_BROKEN_DUP_RULES \
@@ -752,3 +755,9 @@ $(foreach m,$(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

tools/releasetools/common.py

@@ -1257,23 +1257,27 @@ 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:
@@ -1283,7 +1287,9 @@ 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):