In the case of these SoCs the drivers and kernel modifications are kept hidden and under NDA. Ironically these same details are "leaked" in Chinese engineering

In the case of these SoCs the drivers and kernel modifications are kept hidden and under NDA. Ironically these same details are "leaked" in Chinese engineering circles because nobody there will put up with it. If release of this code was forced smaller companies would be able to make use of these SoCs. It would greatly expand access to cheap computing. The GPL and derivatives also anticipated people playing tricks wrt to compiling and forces you to release everything needed to build it.