Out-of-tree modules

The Sub-IoT buildsystem allows compiling modules which are not located in the main source tree. This can be useful if this part contains private IP or if this makes no sense to open source it. The system allows this for:

• platforms
• chips
• applications

For instance, let’s say you have an internal platform which you cannot add to stack/framework/hal/platforms and push upstream. Setting the PLATFORM_EXTRA_PLATFORMS_DIR cmake variable to a directory which contains your custom platform(s) allows you to keep your proprietary platforms in a directory out of the Sub-IoT source tree. In this way the platform’s code can be managed (version controlled) separately from Sub-IoT, and the Sub-IoT source tree remains clean and in sync with upstream. Likewise, you can do the same for chips and applications using the CHIP_EXTRA_CHIPS_DIR and APP_EXTRA_APPS_DIR cmake variables respectively.