diff --git a/core/Makefile b/core/Makefile
index 26f11a4..46920b3 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -162,11 +162,19 @@
 $(call dist-for-goals,sdk,$(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 @@
 
 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 $(BOARD_KERNEL_BASE)
 endif
@@ -756,12 +776,8 @@
 ifdef INTERNAL_KERNEL_CMDLINE
   INTERNAL_BOOTIMAGE_ARGS += --cmdline "$(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) \
@@ -869,6 +885,12 @@
 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 @@
     $(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)
@@ -1335,6 +1363,7 @@
     $(if $(BOARD_USERDATAIMAGE_PARTITION_SIZE),$(hide) echo "userdata_size=$(BOARD_USERDATAIMAGE_PARTITION_SIZE)" >> $(1))
     $(if $(PRODUCT_FS_CASEFOLD),$(hide) echo "needs_casefold=$(PRODUCT_FS_CASEFOLD)" >> $(1))
     $(if $(PRODUCT_QUOTA_PROJID),$(hide) echo "needs_projid=$(PRODUCT_QUOTA_PROJID)" >> $(1))
+    $(if $(PRODUCT_FS_COMPRESSION),$(hide) echo "needs_compress=$(PRODUCT_FS_COMPRESSION)" >> $(1))
     $(hide) echo "userdata_selinux_fc=$(SELINUX_FC)" >> $(1)
     $(hide) echo "building_userdata_image=$(BUILDING_USERDATA_IMAGE)" >> $(1)
 )
@@ -1862,17 +1891,23 @@
 
 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
@@ -1897,7 +1932,7 @@
   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) \
@@ -1933,16 +1968,19 @@
 	  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)),\
@@ -1994,7 +2032,8 @@
 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 +2045,8 @@
 .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 :=
@@ -3887,6 +3927,7 @@
   signapk \
   simg2img \
   sload_f2fs \
+  toybox \
   tune2fs \
   unpack_bootimg \
   update_host_simulator \
@@ -4151,6 +4192,9 @@
 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)
@@ -4209,8 +4253,11 @@
 $(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
@@ -4393,6 +4440,7 @@
 	    $(INSTALLED_CUSTOMIMAGES_TARGET) \
 	    $(INSTALLED_ANDROID_INFO_TXT_TARGET) \
 	    $(INSTALLED_KERNEL_TARGET) \
+	    $(INSTALLED_RAMDISK_TARGET) \
 	    $(INSTALLED_DTBIMAGE_TARGET) \
 	    $(INSTALLED_2NDBOOTLOADER_TARGET) \
 	    $(BOARD_PREBUILT_DTBOIMAGE) \
@@ -4420,7 +4468,7 @@
 	@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) $(call package_files-copy-root, \
@@ -4428,12 +4476,14 @@
 ifdef INSTALLED_KERNEL_TARGET
 ifneq (,$(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
@@ -4451,9 +4501,11 @@
 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
@@ -4476,23 +4528,25 @@
 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; \
@@ -4560,6 +4614,13 @@
 	@# Extra contents of the OTA package
 	$(hide) mkdir -p $(zip_root)/OTA
 	$(hide) cp $(INSTALLED_ANDROID_INFO_TXT_TARGET) $(zip_root)/OTA/
+ifdef BUILDING_RAMDISK_IMAGE
+ifeq (true,$(BOARD_IMG_USE_RAMDISK))
+	@# Contents of the ramdisk image
+	$(hide) mkdir -p $(zip_root)/IMAGES
+	$(hide) cp $(INSTALLED_RAMDISK_TARGET) $(zip_root)/IMAGES/
+endif
+endif
 ifeq ($(TARGET_OTA_ALLOW_NON_AB),true)
 ifneq ($(built_ota_tools),)
 	$(hide) mkdir -p $(zip_root)/OTA/bin
diff --git a/core/board_config.mk b/core/board_config.mk
index 05b6b29..1ab96ea 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -97,6 +97,22 @@
   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_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT controls whether GSI AVB keys 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 \
+  BOARD_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT \
+
 _build_broken_var_list := \
   BUILD_BROKEN_DUP_RULES \
   BUILD_BROKEN_DUP_SYSPROP \
@@ -364,6 +380,9 @@
 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) $(TARGET_NO_RECOVERY)))
       BUILDING_RECOVERY_IMAGE := true
@@ -378,12 +397,7 @@
 BUILDING_VENDOR_BOOT_IMAGE :=
 ifdef BOARD_BOOT_HEADER_VERSION
   ifneq ($(call math_gt_or_eq,$(BOARD_BOOT_HEADER_VERSION),3),)
-    ifneq ($(TARGET_NO_VENDOR_BOOT),)
-      $(warning TARGET_NO_VENDOR_BOOT has been deprecated. Please use PRODUCT_BUILD_VENDOR_BOOT_IMAGE.)
-      ifneq ($(TARGET_NO_VENDOR_BOOT),true)
-        BUILDING_VENDOR_BOOT_IMAGE := true
-      endif
-    else ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),)
+    ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),)
       BUILDING_VENDOR_BOOT_IMAGE := true
     else ifeq ($(PRODUCT_BUILD_VENDOR_BOOT_IMAGE),true)
       BUILDING_VENDOR_BOOT_IMAGE := true
@@ -745,3 +759,28 @@
   $(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))
+    $(error Should not set BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT if not building vendor_boot image)
+  endif
+  ifeq (true,$(BOARD_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT))
+    $(error Should not set BOARD_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT if not building vendor_boot image)
+  endif
+endif
+
+# If BOARD_USES_GENERIC_KERNEL_IMAGE is set, BOARD_USES_RECOVERY_AS_BOOT must not be set.
+# Devices without a dedicated recovery partition uses BOARD_MOVE_RECOVERY_RESOURCES_TO_VENDOR_BOOT to
+# build recovery into vendor_boot.
+ifeq (true,$(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/core/config.mk b/core/config.mk
index 16fa988..e975214 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -157,6 +157,7 @@
 $(KATI_obsolete_var LOCAL_SANITIZE_BLACKLIST,Use LOCAL_SANITIZE_BLOCKLIST instead.)
 $(KATI_deprecated_var BOARD_PLAT_PUBLIC_SEPOLICY_DIR,Use SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS instead.)
 $(KATI_deprecated_var BOARD_PLAT_PRIVATE_SEPOLICY_DIR,Use SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS instead.)
+$(KATI_obsolete_var TARGET_NO_VENDOR_BOOT,Use PRODUCT_BUILD_VENDOR_BOOT_IMAGE instead)
 
 # Used to force goals to build.  Only use for conditionally defined goals.
 .PHONY: FORCE
diff --git a/core/sysprop.mk b/core/sysprop.mk
index a74ff9f..fdefced 100644
--- a/core/sysprop.mk
+++ b/core/sysprop.mk
@@ -54,7 +54,8 @@
     echo "ro.$(1).build.tags=$(BUILD_VERSION_TAGS)" >> $(2);\
     echo "ro.$(1).build.type=$(TARGET_BUILD_VARIANT)" >> $(2);\
     echo "ro.$(1).build.version.incremental=$(BUILD_NUMBER_FROM_FILE)" >> $(2);\
-    echo "ro.$(1).build.version.release=$(PLATFORM_VERSION)" >> $(2);\
+    echo "ro.$(1).build.version.release=$(PLATFORM_VERSION_LAST_STABLE)" >> $(2);\
+    echo "ro.$(1).build.version.release_or_codename=$(PLATFORM_VERSION)" >> $(2);\
     echo "ro.$(1).build.version.sdk=$(PLATFORM_SDK_VERSION)" >> $(2);\
 
 endef
diff --git a/core/tasks/cts.mk b/core/tasks/cts.mk
index cd5fa8e..c09daeb 100644
--- a/core/tasks/cts.mk
+++ b/core/tasks/cts.mk
@@ -14,8 +14,8 @@
 
 test_suite_name := cts
 test_suite_tradefed := cts-tradefed
-test_suite_dynamic_config := test/suite_harness/tools/cts-tradefed/DynamicConfig.xml
-test_suite_readme := test/suite_harness/tools/cts-tradefed/README
+test_suite_dynamic_config := cts/tools/cts-tradefed/DynamicConfig.xml
+test_suite_readme := cts/tools/cts-tradefed/README
 include_test_suite_notice := true
 
 include $(BUILD_SYSTEM)/tasks/tools/compatibility.mk
diff --git a/target/board/BoardConfigEmuCommon.mk b/target/board/BoardConfigEmuCommon.mk
index e9fb096..07b07ce 100644
--- a/target/board/BoardConfigEmuCommon.mk
+++ b/target/board/BoardConfigEmuCommon.mk
@@ -73,7 +73,6 @@
 endif
 
 #vendor boot
-TARGET_NO_VENDOR_BOOT := false
 BOARD_INCLUDE_DTB_IN_BOOTIMG := false
 BOARD_BOOT_HEADER_VERSION := 3
 BOARD_MKBOOTIMG_ARGS += --header_version $(BOARD_BOOT_HEADER_VERSION)
diff --git a/target/board/emulator_arm64/BoardConfig.mk b/target/board/emulator_arm64/BoardConfig.mk
index a17cb75..95eff4b 100644
--- a/target/board/emulator_arm64/BoardConfig.mk
+++ b/target/board/emulator_arm64/BoardConfig.mk
@@ -56,7 +56,6 @@
 include build/make/target/board/BoardConfigEmuCommon.mk
 
 TARGET_NO_KERNEL := false
-TARGET_NO_VENDOR_BOOT := false
 BOARD_USES_RECOVERY_AS_BOOT := true
 
 BOARD_BOOTIMAGE_PARTITION_SIZE := 0x02000000
diff --git a/target/board/generic_arm64/BoardConfig.mk b/target/board/generic_arm64/BoardConfig.mk
index d5331ad..42660e5 100644
--- a/target/board/generic_arm64/BoardConfig.mk
+++ b/target/board/generic_arm64/BoardConfig.mk
@@ -55,7 +55,6 @@
 include build/make/target/board/BoardConfigGsiCommon.mk
 
 TARGET_NO_KERNEL := false
-TARGET_NO_VENDOR_BOOT := true
 BOARD_USES_RECOVERY_AS_BOOT := true
 
 BOARD_KERNEL-4.19-GZ_BOOTIMAGE_PARTITION_SIZE := 47185920
diff --git a/target/board/generic_arm64/device.mk b/target/board/generic_arm64/device.mk
index 6f1bba0..866d7c7 100644
--- a/target/board/generic_arm64/device.mk
+++ b/target/board/generic_arm64/device.mk
@@ -29,3 +29,5 @@
     kernel/prebuilts/5.4/arm64/kernel-5.4-gz:kernel-5.4-gz-allsyms \
     kernel/prebuilts/5.4/arm64/kernel-5.4-lz4:kernel-5.4-lz4-allsyms
 endif
+
+PRODUCT_BUILD_VENDOR_BOOT_IMAGE := false
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 586c058..1a28cf0 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -38,7 +38,6 @@
     bcc \
     blank_screen \
     blkid \
-    service-blobstore \
     bmgr \
     bootanimation \
     bootstat \
@@ -117,7 +116,6 @@
     iptables \
     ip-up-vpn \
     javax.obex \
-    service-jobscheduler \
     keystore \
     credstore \
     ld.mc \
diff --git a/tools/releasetools/Android.bp b/tools/releasetools/Android.bp
index 45e0514..e1543e7 100644
--- a/tools/releasetools/Android.bp
+++ b/tools/releasetools/Android.bp
@@ -125,6 +125,9 @@
     required: [
         "brillo_update_payload",
         "checkvintf",
+        "lz4",
+        "toybox",
+        "unpack_bootimg"
     ],
     target: {
         darwin: {
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index 9cc072f..169a112 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -250,6 +250,7 @@
   run_e2fsck = False
   needs_projid = prop_dict.get("needs_projid", 0)
   needs_casefold = prop_dict.get("needs_casefold", 0)
+  needs_compress = prop_dict.get("needs_compress", 0)
 
   if fs_type.startswith("ext"):
     build_command = [prop_dict["ext_mkuserimg"]]
@@ -337,6 +338,8 @@
       build_command.append("--prjquota")
     if (needs_casefold):
       build_command.append("--casefold")
+    if (needs_compress):
+      build_command.append("--compression")
   else:
     raise BuildImageError(
         "Error: unknown filesystem type: {}".format(fs_type))
@@ -610,6 +613,7 @@
     copy_prop("userdata_selinux_fc", "selinux_fc")
     copy_prop("needs_casefold", "needs_casefold")
     copy_prop("needs_projid", "needs_projid")
+    copy_prop("needs_compress", "needs_compress")
   elif mount_point == "cache":
     copy_prop("cache_fs_type", "fs_type")
     copy_prop("cache_size", "partition_size")
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index f5dfbec..acf9811 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -527,6 +527,27 @@
         return BuildInfo._RO_PRODUCT_PROPS_DEFAULT_SOURCE_ORDER_LEGACY
     return BuildInfo._RO_PRODUCT_PROPS_DEFAULT_SOURCE_ORDER_CURRENT
 
+  def _GetPlatformVersion(self):
+    version_sdk = self.GetBuildProp("ro.build.version.sdk")
+    # init code switches to version_release_or_codename (see b/158483506). After
+    # API finalization, release_or_codename will be the same as release. This
+    # is the best effort to support pre-S dev stage builds.
+    if int(version_sdk) >= 30:
+      try:
+        return self.GetBuildProp("ro.build.version.release_or_codename")
+      except ExternalError:
+        logger.warning('Failed to find ro.build.version.release_or_codename')
+
+    return self.GetBuildProp("ro.build.version.release")
+
+  def _GetPartitionPlatformVersion(self, partition):
+    try:
+      return self.GetPartitionBuildProp("ro.build.version.release_or_codename",
+                                        partition)
+    except ExternalError:
+      return self.GetPartitionBuildProp("ro.build.version.release",
+                                        partition)
+
   def GetOemProperty(self, key):
     if self.oem_props is not None and key in self.oem_props:
       return self.oem_dicts[0][key]
@@ -543,7 +564,7 @@
           self.GetPartitionBuildProp("ro.product.brand", partition),
           self.GetPartitionBuildProp("ro.product.name", partition),
           self.GetPartitionBuildProp("ro.product.device", partition),
-          self.GetPartitionBuildProp("ro.build.version.release", partition),
+          self._GetPartitionPlatformVersion(partition),
           self.GetPartitionBuildProp("ro.build.id", partition),
           self.GetPartitionBuildProp(
               "ro.build.version.incremental", partition),
@@ -559,7 +580,7 @@
             self.GetBuildProp("ro.product.brand"),
             self.GetBuildProp("ro.product.name"),
             self.GetBuildProp("ro.product.device"),
-            self.GetBuildProp("ro.build.version.release"),
+            self._GetPlatformVersion(),
             self.GetBuildProp("ro.build.id"),
             self.GetBuildProp("ro.build.version.incremental"),
             self.GetBuildProp("ro.build.type"),
@@ -814,6 +835,15 @@
     props._LoadBuildProp(data)
     return props
 
+  @staticmethod
+  def FromBuildPropFile(name, build_prop_file):
+    """Constructs an instance from a build prop file."""
+
+    props = PartitionBuildProps("unknown", name)
+    with open(build_prop_file) as f:
+      props._LoadBuildProp(f.read())
+    return props
+
   def _LoadBuildProp(self, data):
     for line in data.split('\n'):
       line = line.strip()
@@ -1257,23 +1287,27 @@
   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 +1317,9 @@
   # 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):
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 18b2b76..7dc648f 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -202,6 +202,10 @@
       ones. Should only be used if caller knows it's safe to do so (e.g. all the
       postinstall work is to dexopt apps and a data wipe will happen immediately
       after). Only meaningful when generating A/B OTAs.
+
+  --partial "<PARTITION> [<PARTITION>[...]]"
+      Generate partial updates, overriding ab_partitions list with the given
+      list.
 """
 
 from __future__ import print_function
@@ -257,6 +261,7 @@
 OPTIONS.skip_postinstall = False
 OPTIONS.skip_compatibility_check = False
 OPTIONS.disable_fec_computation = False
+OPTIONS.partial = None
 
 
 POSTINSTALL_CONFIG = 'META/postinstall_config.txt'
@@ -593,6 +598,48 @@
     return (payload_offset, metadata_total)
 
 
+def UpdatesInfoForSpecialUpdates(content, partitions_filter,
+                                 delete_keys=None):
+  """ Updates info file for secondary payload generation, partial update, etc.
+
+    Scan each line in the info file, and remove the unwanted partitions from
+    the dynamic partition list in the related properties. e.g.
+    "super_google_dynamic_partitions_partition_list=system vendor product"
+    will become "super_google_dynamic_partitions_partition_list=system".
+
+  Args:
+    content: The content of the input info file. e.g. misc_info.txt.
+    partitions_filter: A function to filter the desired partitions from a given
+      list
+    delete_keys: A list of keys to delete in the info file
+
+  Returns:
+    A string of the updated info content.
+  """
+
+  output_list = []
+  # The suffix in partition_list variables that follows the name of the
+  # partition group.
+  list_suffix = 'partition_list'
+  for line in content.splitlines():
+    if line.startswith('#') or '=' not in line:
+      output_list.append(line)
+      continue
+    key, value = line.strip().split('=', 1)
+
+    if delete_keys and key in delete_keys:
+      pass
+    elif key.endswith(list_suffix):
+      partitions = value.split()
+      # TODO for partial update, partitions in the same group must be all
+      # updated or all omitted
+      partitions = filter(partitions_filter, partitions)
+      output_list.append('{}={}'.format(key, ' '.join(partitions)))
+    else:
+      output_list.append(line)
+  return '\n'.join(output_list)
+
+
 def GetTargetFilesZipForSecondaryImages(input_file, skip_postinstall=False):
   """Returns a target-files.zip file for generating secondary payload.
 
@@ -614,44 +661,15 @@
   """
 
   def GetInfoForSecondaryImages(info_file):
-    """Updates info file for secondary payload generation.
-
-    Scan each line in the info file, and remove the unwanted partitions from
-    the dynamic partition list in the related properties. e.g.
-    "super_google_dynamic_partitions_partition_list=system vendor product"
-    will become "super_google_dynamic_partitions_partition_list=system".
-
-    Args:
-      info_file: The input info file. e.g. misc_info.txt.
-
-    Returns:
-      A string of the updated info content.
-    """
-
-    output_list = []
+    """Updates info file for secondary payload generation."""
     with open(info_file) as f:
-      lines = f.read().splitlines()
-
-    # The suffix in partition_list variables that follows the name of the
-    # partition group.
-    LIST_SUFFIX = 'partition_list'
-    for line in lines:
-      if line.startswith('#') or '=' not in line:
-        output_list.append(line)
-        continue
-      key, value = line.strip().split('=', 1)
-      if key == 'dynamic_partition_list' or key.endswith(LIST_SUFFIX):
-        partitions = value.split()
-        partitions = [partition for partition in partitions if partition
-                      not in SECONDARY_PAYLOAD_SKIPPED_IMAGES]
-        output_list.append('{}={}'.format(key, ' '.join(partitions)))
-      elif key in ['virtual_ab', "virtual_ab_retrofit"]:
-        # Remove virtual_ab flag from secondary payload so that OTA client
-        # don't use snapshots for secondary update
-        pass
-      else:
-        output_list.append(line)
-    return '\n'.join(output_list)
+      content = f.read()
+    # Remove virtual_ab flag from secondary payload so that OTA client
+    # don't use snapshots for secondary update
+    delete_keys = ['virtual_ab', "virtual_ab_retrofit"]
+    return UpdatesInfoForSpecialUpdates(
+        content, lambda p: p not in SECONDARY_PAYLOAD_SKIPPED_IMAGES,
+        delete_keys)
 
   target_file = common.MakeTempFile(prefix="targetfiles-", suffix=".zip")
   target_zip = zipfile.ZipFile(target_file, 'w', allowZip64=True)
@@ -729,6 +747,76 @@
   return target_file
 
 
+def GetTargetFilesZipForPartialUpdates(input_file, ab_partitions):
+  """Returns a target-files.zip for partial ota update package generation.
+
+  This function modifies ab_partitions list with the desired partitions before
+  calling the brillo_update_payload script. It also cleans up the reference to
+  the excluded partitions in the info file, e.g misc_info.txt.
+
+  Args:
+    input_file: The input target-files.zip filename.
+    ab_partitions: A list of partitions to include in the partial update
+
+  Returns:
+    The filename of target-files.zip used for partial ota update.
+  """
+
+  def AddImageForPartition(partition_name):
+    """Add the archive name for a given partition to the copy list."""
+    for prefix in ['IMAGES', 'RADIO']:
+      image_path = '{}/{}.img'.format(prefix, partition_name)
+      if image_path in namelist:
+        copy_entries.append(image_path)
+        map_path = '{}/{}.map'.format(prefix, partition_name)
+        if map_path in namelist:
+          copy_entries.append(map_path)
+        return
+
+    raise ValueError("Cannot find {} in input zipfile".format(partition_name))
+
+  with zipfile.ZipFile(input_file, allowZip64=True) as input_zip:
+    original_ab_partitions = input_zip.read(AB_PARTITIONS).decode().splitlines()
+    namelist = input_zip.namelist()
+
+  unrecognized_partitions = [partition for partition in ab_partitions if
+                             partition not in original_ab_partitions]
+  if unrecognized_partitions:
+    raise ValueError("Unrecognized partitions when generating partial updates",
+                     unrecognized_partitions)
+
+  logger.info("Generating partial updates for %s", ab_partitions)
+
+  copy_entries = ['META/update_engine_config.txt']
+  for partition_name in ab_partitions:
+    AddImageForPartition(partition_name)
+
+  # Use zip2zip to avoid extracting the zipfile.
+  partial_target_file = common.MakeTempFile(suffix='.zip')
+  cmd = ['zip2zip', '-i', input_file, '-o', partial_target_file]
+  cmd.extend(['{}:{}'.format(name, name) for name in copy_entries])
+  common.RunAndCheckOutput(cmd)
+
+  partial_target_zip = zipfile.ZipFile(partial_target_file, 'a',
+                                       allowZip64=True)
+  with zipfile.ZipFile(input_file, allowZip64=True) as input_zip:
+    common.ZipWriteStr(partial_target_zip, 'META/ab_partitions.txt',
+                       '\n'.join(ab_partitions))
+    for info_file in ['META/misc_info.txt', DYNAMIC_PARTITION_INFO]:
+      if info_file not in input_zip.namelist():
+        logger.warning('Cannot find %s in input zipfile', info_file)
+        continue
+      content = input_zip.read(info_file).decode()
+      modified_info = UpdatesInfoForSpecialUpdates(
+          content, lambda p: p in ab_partitions)
+      common.ZipWriteStr(partial_target_zip, info_file, modified_info)
+
+    # TODO(xunchang) handle 'META/care_map.pb', 'META/postinstall_config.txt'
+  common.ZipClose(partial_target_zip)
+
+  return partial_target_file
+
+
 def GetTargetFilesZipForRetrofitDynamicPartitions(input_file,
                                                   super_block_devices,
                                                   dynamic_partition_list):
@@ -837,10 +925,16 @@
     target_info = common.BuildInfo(OPTIONS.info_dict, OPTIONS.oem_dicts)
     source_info = None
 
+  additional_args = []
+
   if OPTIONS.retrofit_dynamic_partitions:
     target_file = GetTargetFilesZipForRetrofitDynamicPartitions(
         target_file, target_info.get("super_block_devices").strip().split(),
         target_info.get("dynamic_partition_list").strip().split())
+  elif OPTIONS.partial:
+    target_file = GetTargetFilesZipForPartialUpdates(target_file,
+                                                     OPTIONS.partial)
+    additional_args += ["--is_partial_update", "true"]
   elif OPTIONS.skip_postinstall:
     target_file = GetTargetFilesZipWithoutPostinstallConfig(target_file)
   # Target_file may have been modified, reparse ab_partitions
@@ -862,7 +956,7 @@
     partition_timestamps = [
         part.partition_name + ":" + part.version
         for part in metadata.postcondition.partition_state]
-  additional_args = ["--max_timestamp", max_timestamp]
+  additional_args += ["--max_timestamp", max_timestamp]
   if partition_timestamps:
     additional_args.extend(
         ["--partition_timestamps", ",".join(
@@ -1006,6 +1100,11 @@
       OPTIONS.force_non_ab = True
     elif o == "--boot_variable_file":
       OPTIONS.boot_variable_file = a
+    elif o == "--partial":
+      partitions = a.split()
+      if not partitions:
+        raise ValueError("Cannot parse partitions in {}".format(a))
+      OPTIONS.partial = partitions
     else:
       return False
     return True
@@ -1044,6 +1143,7 @@
                                  "disable_fec_computation",
                                  "force_non_ab",
                                  "boot_variable_file=",
+                                 "partial=",
                              ], extra_option_handler=option_handler)
 
   if len(args) != 2:
@@ -1058,6 +1158,8 @@
     # OTA package.
     if OPTIONS.incremental_source is None:
       raise ValueError("Cannot generate downgradable full OTAs")
+    if OPTIONS.partial:
+      raise ValueError("Cannot generate downgradable partial OTAs")
 
   # Load the build info dicts from the zip directly or the extracted input
   # directory. We don't need to unzip the entire target-files zips, because they
@@ -1072,6 +1174,10 @@
     with zipfile.ZipFile(args[0], 'r', allowZip64=True) as input_zip:
       OPTIONS.info_dict = common.LoadInfoDict(input_zip)
 
+  # TODO(xunchang) for retrofit and partial updates, maybe we should rebuild the
+  # target-file and reload the info_dict. So the info will be consistent with
+  # the modified target-file.
+
   logger.info("--- target info ---")
   common.DumpInfoDict(OPTIONS.info_dict)
 
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index f0e4fcf..cb0f6e6 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -14,14 +14,17 @@
 
 import copy
 import itertools
+import logging
 import os
 import zipfile
 
 import ota_metadata_pb2
 from common import (ZipDelete, ZipClose, OPTIONS, MakeTempFile,
                     ZipWriteStr, BuildInfo, LoadDictionaryFromFile,
-                    SignFile, PARTITIONS_WITH_CARE_MAP, PartitionBuildProps)
+                    SignFile, PARTITIONS_WITH_CARE_MAP, PartitionBuildProps,
+                    MakeTempDir, RunAndCheckOutput, ExternalError)
 
+logger = logging.getLogger(__name__)
 
 OPTIONS.no_signing = False
 OPTIONS.force_non_ab = False
@@ -38,6 +41,9 @@
 METADATA_PROTO_NAME = 'META-INF/com/android/metadata.pb'
 UNZIP_PATTERN = ['IMAGES/*', 'META/*', 'OTA/*', 'RADIO/*']
 
+# See sysprop.mk. If file is moved, add new search paths here; don't remove
+# existing search paths.
+RAMDISK_BUILD_PROP_REL_PATHS = ['system/etc/ramdisk/build.prop']
 
 def FinalizeMetadata(metadata, input_file, output_file, needed_property_files):
   """Finalizes the metadata and signs an A/B OTA package.
@@ -561,3 +567,55 @@
 
   SignFile(temp_zip_name, output_zip_name, OPTIONS.package_key, pw,
            whole_file=True)
+
+
+def GetBootImageTimestamp(boot_img):
+  """
+  Get timestamp from ramdisk within the boot image
+
+  Args:
+    boot_img: the boot image file. Ramdisk must be compressed with lz4 format.
+
+  Return:
+    An integer that corresponds to the timestamp of the boot image, or None
+    if file has unknown format. Raise exception if an unexpected error has
+    occurred.
+  """
+
+  tmp_dir = MakeTempDir('boot_', suffix='.img')
+  try:
+    RunAndCheckOutput(['unpack_bootimg', '--boot_img', boot_img, '--out', tmp_dir])
+    ramdisk = os.path.join(tmp_dir, 'ramdisk')
+    if not os.path.isfile(ramdisk):
+      logger.warning('Unable to get boot image timestamp: no ramdisk in boot')
+      return None
+    uncompressed_ramdisk = os.path.join(tmp_dir, 'uncompressed_ramdisk')
+    RunAndCheckOutput(['lz4', '-d', ramdisk, uncompressed_ramdisk])
+
+    abs_uncompressed_ramdisk = os.path.abspath(uncompressed_ramdisk)
+    extracted_ramdisk = MakeTempDir('extracted_ramdisk')
+    # Use "toybox cpio" instead of "cpio" because the latter invokes cpio from
+    # the host environment.
+    RunAndCheckOutput(['toybox', 'cpio', '-F', abs_uncompressed_ramdisk, '-i'],
+               cwd=extracted_ramdisk)
+
+    prop_file = None
+    for search_path in RAMDISK_BUILD_PROP_REL_PATHS:
+      prop_file = os.path.join(extracted_ramdisk, search_path)
+      if os.path.isfile(prop_file):
+        break
+      logger.warning('Unable to get boot image timestamp: no %s in ramdisk', search_path)
+
+    if not prop_file:
+      return None
+
+    props = PartitionBuildProps.FromBuildPropFile('boot', prop_file)
+    timestamp = props.GetProp('ro.bootimage.build.date.utc')
+    if timestamp:
+      return int(timestamp)
+    logger.warning('Unable to get boot image timestamp: ro.bootimage.build.date.utc is undefined')
+    return None
+
+  except ExternalError as e:
+    logger.warning('Unable to get boot image timestamp: %s', e)
+    return None
diff --git a/tools/releasetools/test_ota_from_target_files.py b/tools/releasetools/test_ota_from_target_files.py
index f96bc7b..9752c2b 100644
--- a/tools/releasetools/test_ota_from_target_files.py
+++ b/tools/releasetools/test_ota_from_target_files.py
@@ -27,6 +27,7 @@
     FinalizeMetadata, GetPackageMetadata, PropertyFiles)
 from ota_from_target_files import (
     _LoadOemDicts, AbOtaPropertyFiles,
+    GetTargetFilesZipForPartialUpdates,
     GetTargetFilesZipForSecondaryImages,
     GetTargetFilesZipWithoutPostinstallConfig,
     Payload, PayloadSigner, POSTINSTALL_CONFIG,
@@ -450,6 +451,86 @@
                      updated_dynamic_partitions_info)
 
   @test_utils.SkipIfExternalToolsUnavailable()
+  def test_GetTargetFilesZipForPartialUpdates_singlePartition(self):
+    input_file = construct_target_files()
+    with zipfile.ZipFile(input_file, 'a', allowZip64=True) as append_zip:
+      common.ZipWriteStr(append_zip, 'IMAGES/system.map', 'fake map')
+
+    target_file = GetTargetFilesZipForPartialUpdates(input_file, ['system'])
+    with zipfile.ZipFile(target_file) as verify_zip:
+      namelist = verify_zip.namelist()
+      ab_partitions = verify_zip.read('META/ab_partitions.txt').decode()
+
+    self.assertIn('META/ab_partitions.txt', namelist)
+    self.assertIn('META/update_engine_config.txt', namelist)
+    self.assertIn('IMAGES/system.img', namelist)
+    self.assertIn('IMAGES/system.map', namelist)
+
+    self.assertNotIn('IMAGES/boot.img', namelist)
+    self.assertNotIn('IMAGES/system_other.img', namelist)
+    self.assertNotIn('RADIO/bootloader.img', namelist)
+    self.assertNotIn('RADIO/modem.img', namelist)
+
+    self.assertEqual('system', ab_partitions)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_GetTargetFilesZipForPartialUpdates_unrecognizedPartition(self):
+    input_file = construct_target_files()
+    self.assertRaises(ValueError, GetTargetFilesZipForPartialUpdates,
+                      input_file, ['product'])
+
+  @test_utils.SkipIfExternalToolsUnavailable()
+  def test_GetTargetFilesZipForPartialUpdates_dynamicPartitions(self):
+    input_file = construct_target_files(secondary=True)
+    misc_info = '\n'.join([
+        'use_dynamic_partition_size=true',
+        'use_dynamic_partitions=true',
+        'dynamic_partition_list=system vendor product',
+        'super_partition_groups=google_dynamic_partitions',
+        'super_google_dynamic_partitions_group_size=4873781248',
+        'super_google_dynamic_partitions_partition_list=system vendor product',
+    ])
+    dynamic_partitions_info = '\n'.join([
+        'super_partition_groups=google_dynamic_partitions',
+        'super_google_dynamic_partitions_group_size=4873781248',
+        'super_google_dynamic_partitions_partition_list=system vendor product',
+    ])
+
+    with zipfile.ZipFile(input_file, 'a', allowZip64=True) as append_zip:
+      common.ZipWriteStr(append_zip, 'META/misc_info.txt', misc_info)
+      common.ZipWriteStr(append_zip, 'META/dynamic_partitions_info.txt',
+                         dynamic_partitions_info)
+
+    target_file = GetTargetFilesZipForPartialUpdates(input_file,
+                                                     ['boot', 'system'])
+    with zipfile.ZipFile(target_file) as verify_zip:
+      namelist = verify_zip.namelist()
+      ab_partitions = verify_zip.read('META/ab_partitions.txt').decode()
+      updated_misc_info = verify_zip.read('META/misc_info.txt').decode()
+      updated_dynamic_partitions_info = verify_zip.read(
+          'META/dynamic_partitions_info.txt').decode()
+
+    self.assertIn('META/ab_partitions.txt', namelist)
+    self.assertIn('IMAGES/boot.img', namelist)
+    self.assertIn('IMAGES/system.img', namelist)
+    self.assertIn('META/misc_info.txt', namelist)
+    self.assertIn('META/dynamic_partitions_info.txt', namelist)
+
+    self.assertNotIn('IMAGES/system_other.img', namelist)
+    self.assertNotIn('RADIO/bootloader.img', namelist)
+    self.assertNotIn('RADIO/modem.img', namelist)
+
+    # Check the vendor & product are removed from the partitions list.
+    expected_misc_info = misc_info.replace('system vendor product',
+                                           'system')
+    expected_dynamic_partitions_info = dynamic_partitions_info.replace(
+        'system vendor product', 'system')
+    self.assertEqual(expected_misc_info, updated_misc_info)
+    self.assertEqual(expected_dynamic_partitions_info,
+                     updated_dynamic_partitions_info)
+    self.assertEqual('boot\nsystem', ab_partitions)
+
+  @test_utils.SkipIfExternalToolsUnavailable()
   def test_GetTargetFilesZipWithoutPostinstallConfig(self):
     input_file = construct_target_files()
     target_file = GetTargetFilesZipWithoutPostinstallConfig(input_file)
@@ -1205,11 +1286,12 @@
   ]
 
   BUILD_PROP = [
-      'ro.build.version.release=version-release',
       'ro.build.id=build-id',
       'ro.build.version.incremental=version-incremental',
       'ro.build.type=build-type',
       'ro.build.tags=build-tags',
+      'ro.build.version.release=version-release',
+      'ro.build.version.release_or_codename=version-release',
       'ro.build.version.sdk=30',
       'ro.build.version.security_patch=2020',
       'ro.build.date.utc=12345678',