Changes you must do before using device trees:

extra.fstab support: You must add in device.mk

PRODUCT_COPY_FILES +=
$(LOCAL_PATH)/rootdir/extra.fstab:recovery/root/etc/extra.fstab

Custom init.rc for recovery: these are the "ini.philz*.rc" files in rootdir/etc.

you must add a flag in BoardConfig.mk:

TARGET_RECOVERY_INITRC := vendor/samsung/common_init/init.philz*.rc

I did not add them because I just patched build/core/Makefile to auto copy them when they are present

It avoids stitching my changes to device tree when I sync to upstream