XNU
Legacy mirror of Darwin Kernel
...The name XNU stands for X is Not Unix, highlighting its origin as a combination of multiple kernel technologies—primarily the Mach microkernel from Carnegie Mellon University, integrated with substantial components from FreeBSD and Apple’s proprietary IOKit driver framework. This hybrid architecture merges the microkernel model’s message-passing flexibility with the monolithic performance and direct hardware control typical of Unix-like systems. XNU handles essential kernel responsibilities such as memory management, multitasking, interprocess communication (IPC), device I/O, system calls, security enforcement, and scheduling across both single and multi-core architectures.