 A hobbyist developer "winocm" took the official Darwin source code and ported it to ARM.The kernel of Darwin is XNU, a hybrid kernel which uses OSFMK 7.3 (Open Software Foundation Mach Kernel) from the OSF, various elements of FreeBSD (including the process model, network stack, and virtual file system), and an object-oriented device driver API called I/O Kit.The hybrid kernel design provides the flexibility of a microkernel and the performance of a monolithic kernel.