Lexicon Entry
XNU Kernel
XNU (X is Not Unix) is the computer operating system kernel developed at Apple. It is a hybrid kernel combining the Mach microkernel for IPC and scheduling with components from FreeBSD for POSIX APIs and networking.
Related Knowledge & Cross-References
Guide
macOS Execution: Mach Tasks vs. BSD Processes
A deep dive into the Darwin/XNU kernel. We explore the architectural divide between Mach Tasks and Threads, and how standard BSD POSIX APIs like fork() are illusions layered over Mach primitives.