Android HAL .so not build - android-source

Question

I was following this guide to learn HAL layer and framework layer in AOSP. I've managed to run the whole process. But there's one small issue. When I build the whole ROM/Android, hello.default.so won't be built/shown up in the following,
${output}/system/lib/hw
${output}/system/lib64/hw
${output}/vendor/lib/hw
${output}/vendor/lib64/hw
Only by manually executing mmm hardware/libhardware/modules/hello/, can I get the hello.default.so.
I have remember to append the module into PRODUCT_PACKAGES macro as following. Packages/Modules vim, hello-lkm-client have been successfully integrated. But not the hello.default module.
PRODUCT_PACKAGES += \
vim
PRODUCT_PACKAGES += \
hello-lkm-client
PRODUCT_PACKAGES += \
hello.default
Here's the Android.mk file for the hello HAL
include $(CLEAR_VARS)
LOCAL_MODULE_RELATIVE_PATH := hw
LOCAL_PROPRIETARY_MODULE := true
LOCAL_SHARED_LIBRARIES := liblog
#############
# I'm following $hw/modules/gralloc/Android.mk
#############
LOCAL_MODULE_TAGS := optional
LOCAL_PRELINK_MODULE := false
# LOCAL_C_INCLUDES := hardware/libhardware
LOCAL_SRC_FILES := hello.c
LOCAL_HEADER_LIBRARIES := libhardware_headers
LOCAL_MODULE := hello.default
# LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog
include $(BUILD_SHARED_LIBRARY)
Here's the complete hello HAL module.

Answer 1

OK, found it. I have to add the hello module in Android.mk of Module modules, just like the following.
chang#ryzen:~/bulk2/rockpi4-atv9-chang/hardware/libhardware$ git diff
diff --git a/modules/Android.mk b/modules/Android.mk
index a430a650..7bbeaeb9 100644
--- a/modules/Android.mk
+++ b/modules/Android.mk
## -2,5 +2,6 ## hardware_modules := \
camera \
gralloc \
sensors \
- hw_output
+ hw_output \
+ hello