Genode - Operating System Framework
The Genode operating-system framework provides a uniform API for applications on top of 8 existing microkernels/hypervisors: Linux, L4ka::Pistachio, L4/Fiasco, OKL4, NOVA, Fiasco.OC, Codezero, and a custom kernel for ARM SoCs.
Genode allows the kernel to use
device drivers, protocol stacks, libraries, and applications in a uniform way. For developers, the framework provides an easy way to target multiple different kernels instead of tying the development to a particular kernel technology.