diff --git a/core/Makefile b/core/Makefile
index 8a960b6d90..e8e592a606 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1935,6 +1935,106 @@ ifneq ($(BOARD_NAND_SPARE_SIZE),)
 $(error MTD device is no longer supported and thus BOARD_NAND_SPARE_SIZE is deprecated.)
 endif
 
+# -----------------------------------------------------------------
+# the debug ramdisk, which is the original ramdisk plus additional
+# files: force_debuggable, adb_debug.prop and userdebug sepolicy.
+# When /force_debuggable is present, /init will load userdebug sepolicy
+# and property files to allow adb root, if the device is unlocked.
+
+ifdef BUILDING_RAMDISK_IMAGE
+BUILT_DEBUG_RAMDISK_TARGET := $(PRODUCT_OUT)/ramdisk-debug.img
+INSTALLED_DEBUG_RAMDISK_TARGET := $(BUILT_DEBUG_RAMDISK_TARGET)
+
+INTERNAL_DEBUG_RAMDISK_FILES := $(filter $(TARGET_DEBUG_RAMDISK_OUT)/%, \
+    $(ALL_GENERATED_SOURCES) \
+    $(ALL_DEFAULT_INSTALLED_MODULES))
+
+# Note: TARGET_DEBUG_RAMDISK_OUT will be $(PRODUCT_OUT)/debug_ramdisk/first_stage_ramdisk,
+# if BOARD_USES_RECOVERY_AS_BOOT is true. Otherwise, it will be $(PRODUCT_OUT)/debug_ramdisk.
+# But the root dir of the ramdisk to build is always $(PRODUCT_OUT)/debug_ramdisk.
+my_debug_ramdisk_root_dir := $(PRODUCT_OUT)/debug_ramdisk
+
+INSTALLED_FILES_FILE_DEBUG_RAMDISK := $(PRODUCT_OUT)/installed-files-ramdisk-debug.txt
+INSTALLED_FILES_JSON_DEBUG_RAMDISK := $(INSTALLED_FILES_FILE_DEBUG_RAMDISK:.txt=.json)
+$(INSTALLED_FILES_FILE_DEBUG_RAMDISK): .KATI_IMPLICIT_OUTPUTS := $(INSTALLED_FILES_JSON_DEBUG_RAMDISK)
+$(INSTALLED_FILES_FILE_DEBUG_RAMDISK): DEBUG_RAMDISK_ROOT_DIR := $(my_debug_ramdisk_root_dir)
+
+# Cannot just depend on INTERNAL_DEBUG_RAMDISK_FILES like other INSTALLED_FILES_FILE_* rules.
+# Because ramdisk-debug.img will rsync from either ramdisk.img or ramdisk-recovery.img.
+# Need to depend on the built ramdisk-debug.img, to get a complete list of the installed files.
+$(INSTALLED_FILES_FILE_DEBUG_RAMDISK) : $(INSTALLED_DEBUG_RAMDISK_TARGET)
+$(INSTALLED_FILES_FILE_DEBUG_RAMDISK) : $(INTERNAL_DEBUG_RAMDISK_FILES) $(FILESLIST)
+	echo Installed file list: $@
+	mkdir -p $(dir $@)
+	rm -f $@
+	$(FILESLIST) $(DEBUG_RAMDISK_ROOT_DIR) > $(@:.txt=.json)
+	build/make/tools/fileslist_util.py -c $(@:.txt=.json) > $@
+
+# ramdisk-debug.img will rsync the content from either ramdisk.img or ramdisk-recovery.img,
+# depending on whether BOARD_USES_RECOVERY_AS_BOOT is set or not.
+ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
+my_debug_ramdisk_sync_dir := $(TARGET_RECOVERY_ROOT_OUT)
+else
+my_debug_ramdisk_sync_dir := $(TARGET_RAMDISK_OUT)
+endif # BOARD_USES_RECOVERY_AS_BOOT
+
+$(INSTALLED_DEBUG_RAMDISK_TARGET): DEBUG_RAMDISK_SYNC_DIR := $(my_debug_ramdisk_sync_dir)
+$(INSTALLED_DEBUG_RAMDISK_TARGET): DEBUG_RAMDISK_ROOT_DIR := $(my_debug_ramdisk_root_dir)
+# We should have just depended on ramdisk.img or ramdisk-recovery.img.
+# But ramdisk-recovery.img is not a make target, so let's depend on the boot.img directly.
+$(INSTALLED_DEBUG_RAMDISK_TARGET): $(INSTALLED_BOOTIMAGE_TARGET)
+$(INSTALLED_DEBUG_RAMDISK_TARGET): $(MKBOOTFS) $(INTERNAL_DEBUG_RAMDISK_FILES) | $(MINIGZIP)
+	$(call pretty,"Target debug ram disk: $@")
+	mkdir -p $(TARGET_DEBUG_RAMDISK_OUT)
+	touch $(TARGET_DEBUG_RAMDISK_OUT)/force_debuggable
+	rsync -a $(DEBUG_RAMDISK_SYNC_DIR)/* $(DEBUG_RAMDISK_ROOT_DIR)
+	$(MKBOOTFS) -d $(TARGET_OUT) $(DEBUG_RAMDISK_ROOT_DIR) | $(MINIGZIP) > $@
+
+.PHONY: ramdisk_debug-nodeps
+ramdisk_debug-nodeps: DEBUG_RAMDISK_SYNC_DIR := $(my_debug_ramdisk_sync_dir)
+ramdisk_debug-nodeps: DEBUG_RAMDISK_ROOT_DIR := $(my_debug_ramdisk_root_dir)
+ramdisk_debug-nodeps: $(MKBOOTFS) | $(MINIGZIP)
+	echo "make $@: ignoring dependencies"
+	mkdir -p $(TARGET_DEBUG_RAMDISK_OUT)
+	touch $(TARGET_DEBUG_RAMDISK_OUT)/force_debuggable
+	rsync -a $(DEBUG_RAMDISK_SYNC_DIR)/* $(DEBUG_RAMDISK_ROOT_DIR)
+	$(MKBOOTFS) -d $(TARGET_OUT) $(DEBUG_RAMDISK_ROOT_DIR) | $(MINIGZIP) > $(INSTALLED_DEBUG_RAMDISK_TARGET)
+
+my_debug_ramdisk_sync_dir :=
+my_debug_ramdisk_root_dir :=
+
+endif # BUILDING_RAMDISK_IMAGE
+
+# -----------------------------------------------------------------
+# the boot-debug.img, which is the kernel plus ramdisk-debug.img
+#
+# Note: it's intentional to skip signing for boot-debug.img, because it
+# can only be used if the device is unlocked with verification error.
+ifneq ($(strip $(TARGET_NO_KERNEL)),true)
+
+INSTALLED_DEBUG_BOOTIMAGE_TARGET := $(PRODUCT_OUT)/boot-debug.img
+
+# Replace ramdisk.img in $(MKBOOTIMG) ARGS with ramdisk-debug.img to build boot-debug.img
+ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
+INTERNAL_DEBUG_BOOTIMAGE_ARGS := $(subst $(recovery_ramdisk),$(INSTALLED_DEBUG_RAMDISK_TARGET), $(INTERNAL_RECOVERYIMAGE_ARGS))
+else
+INTERNAL_DEBUG_BOOTIMAGE_ARGS := $(subst $(INSTALLED_RAMDISK_TARGET),$(INSTALLED_DEBUG_RAMDISK_TARGET), $(INTERNAL_BOOTIMAGE_ARGS))
+endif
+
+# Depends on original boot.img and ramdisk-debug.img, to build the new boot-debug.img
+$(INSTALLED_DEBUG_BOOTIMAGE_TARGET): $(MKBOOTIMG) $(INSTALLED_BOOTIMAGE_TARGET) $(INSTALLED_DEBUG_RAMDISK_TARGET)
+	$(call pretty,"Target boot debug image: $@")
+	$(MKBOOTIMG) $(INTERNAL_DEBUG_BOOTIMAGE_ARGS) $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(BOARD_MKBOOTIMG_ARGS) --output $@
+	$(call assert-max-image-size,$@,$(BOARD_BOOTIMAGE_PARTITION_SIZE))
+
+.PHONY: bootimage_debug-nodeps
+bootimage_debug-nodeps: $(MKBOOTIMG)
+	echo "make $@: ignoring dependencies"
+	$(MKBOOTIMG) $(INTERNAL_DEBUG_BOOTIMAGE_ARGS) $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(BOARD_MKBOOTIMG_ARGS) --output $(INSTALLED_DEBUG_BOOTIMAGE_TARGET)
+	$(call assert-max-image-size,$(INSTALLED_DEBUG_BOOTIMAGE_TARGET),$(BOARD_BOOTIMAGE_PARTITION_SIZE))
+
+endif # TARGET_NO_KERNEL
+
 # -----------------------------------------------------------------
 # system image
 #
diff --git a/core/board_config.mk b/core/board_config.mk
index dcfed9d958..2580a33fa9 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -240,6 +240,12 @@ ifeq ($(BOARD_BUILD_SYSTEM_ROOT_IMAGE),true)
 TARGET_COPY_OUT_RAMDISK := $(TARGET_COPY_OUT_ROOT)
 endif
 
+###########################################
+# Now we can substitute with the real value of TARGET_COPY_OUT_DEBUG_RAMDISK
+ifeq ($(BOARD_USES_RECOVERY_AS_BOOT),true)
+TARGET_COPY_OUT_DEBUG_RAMDISK := debug_ramdisk/first_stage_ramdisk
+endif
+
 ###########################################
 # Configure whether we're building the system image
 BUILDING_SYSTEM_IMAGE := true
diff --git a/core/config.mk b/core/config.mk
index 386c64e74d..94928a24ae 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -1178,7 +1178,9 @@ dont_bother_goals := out \
     onod odmimage-nodeps \
     systemotherimage-nodeps \
     ramdisk-nodeps \
+    ramdisk_debug-nodeps \
     bootimage-nodeps \
+    bootimage_debug-nodeps \
     recoveryimage-nodeps \
     vbmetaimage-nodeps \
     product-graph dump-products
diff --git a/core/envsetup.mk b/core/envsetup.mk
index 7b90334223..46edc0ee3d 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -225,6 +225,7 @@ TARGET_COPY_OUT_DATA := data
 TARGET_COPY_OUT_ASAN := $(TARGET_COPY_OUT_DATA)/asan
 TARGET_COPY_OUT_OEM := oem
 TARGET_COPY_OUT_RAMDISK := ramdisk
+TARGET_COPY_OUT_DEBUG_RAMDISK := debug_ramdisk
 TARGET_COPY_OUT_ROOT := root
 TARGET_COPY_OUT_RECOVERY := recovery
 # The directory used for optional partitions depend on the BoardConfig, so
@@ -838,6 +839,7 @@ TARGET_OUT_COVERAGE := $(PRODUCT_OUT)/coverage
 
 TARGET_RAMDISK_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_RAMDISK)
 TARGET_RAMDISK_OUT_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)
+TARGET_DEBUG_RAMDISK_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_DEBUG_RAMDISK)
 
 TARGET_ROOT_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_ROOT)
 TARGET_ROOT_OUT_BIN := $(TARGET_ROOT_OUT)/bin
diff --git a/core/main.mk b/core/main.mk
index 590bfcc7ff..af26705370 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1429,6 +1429,9 @@ endif
 .PHONY: ramdisk
 ramdisk: $(INSTALLED_RAMDISK_TARGET)
 
+.PHONY: ramdisk_debug
+ramdisk_debug: $(INSTALLED_DEBUG_RAMDISK_TARGET)
+
 .PHONY: systemtarball
 systemtarball: $(INSTALLED_SYSTEMTARBALL_TARGET)
 
@@ -1475,6 +1478,9 @@ superimage_empty: $(INSTALLED_SUPERIMAGE_EMPTY_TARGET)
 .PHONY: bootimage
 bootimage: $(INSTALLED_BOOTIMAGE_TARGET)
 
+.PHONY: bootimage_debug
+bootimage_debug: $(INSTALLED_DEBUG_BOOTIMAGE_TARGET)
+
 .PHONY: vbmetaimage
 vbmetaimage: $(INSTALLED_VBMETAIMAGE_TARGET)
 
@@ -1487,6 +1493,8 @@ droidcore: $(filter $(HOST_OUT_ROOT)/%,$(modules_to_install)) \
     $(INSTALLED_SYSTEMIMAGE_TARGET) \
     $(INSTALLED_RAMDISK_TARGET) \
     $(INSTALLED_BOOTIMAGE_TARGET) \
+    $(INSTALLED_DEBUG_RAMDISK_TARGET) \
+    $(INSTALLED_DEBUG_BOOTIMAGE_TARGET) \
     $(INSTALLED_RECOVERYIMAGE_TARGET) \
     $(INSTALLED_VBMETAIMAGE_TARGET) \
     $(INSTALLED_USERDATAIMAGE_TARGET) \
@@ -1511,6 +1519,8 @@ droidcore: $(filter $(HOST_OUT_ROOT)/%,$(modules_to_install)) \
     $(INSTALLED_FILES_JSON_SYSTEMOTHER) \
     $(INSTALLED_FILES_FILE_RAMDISK) \
     $(INSTALLED_FILES_JSON_RAMDISK) \
+    $(INSTALLED_FILES_FILE_DEBUG_RAMDISK) \
+    $(INSTALLED_FILES_JSON_DEBUG_RAMDISK) \
     $(INSTALLED_FILES_FILE_ROOT) \
     $(INSTALLED_FILES_JSON_ROOT) \
     $(INSTALLED_FILES_FILE_RECOVERY) \
@@ -1631,6 +1641,10 @@ else # TARGET_BUILD_APPS
     $(call dist-for-goals, droidcore, \
       $(INSTALLED_FILES_FILE_RAMDISK) \
       $(INSTALLED_FILES_JSON_RAMDISK) \
+      $(INSTALLED_FILES_FILE_DEBUG_RAMDISK) \
+      $(INSTALLED_FILES_JSON_DEBUG_RAMDISK) \
+      $(INSTALLED_DEBUG_RAMDISK_TARGET) \
+      $(INSTALLED_DEBUG_BOOTIMAGE_TARGET) \
     )
   endif