How to build factory images:

Do a normal build prep, then in the ANDROID_TOP_DIR run:

$ make -j24  dist
$ cd out/dist/
$ . ../../device/linaro/hikey960/factory-images/generate-factory-images-package.sh

# Package with an existing image
# First download the image to the android build top directory

$ device/linaro/hikey960/factory-images/generate-factory-images-package.sh