Unraveling the Mac OS X Microkernel Myth

According to proponents of this myth, Mac OS X is in grave danger because it has a microkernel and Linux doesn't. They're wrong; here's why.



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Why the Myth was Woven

This myth is the main thread holding together the Mac OS X Needs a Linux Kernel Myth. According to the Copy/Paste Development Myth, this should all be easy to fix: yank out that Mach stuff, and throw in Linux!



The Myth Weavers

This myth is of the wishful thinking type, making it more of an irritating distraction from reality than devious misinformation, but it's also used in fanboyism that borders on FUD.





What is a Kernel?

The Unix Kernel is the master control program which governs all other programs, schedules access to hardware, and manages the file system and security model. The name kernel differentiates the core system (which runs as the root process with special privileges) from everything else on the system (which runs under restricted user accounts). Everything outside of the kernel space is called the userland.



In the natural development of Unix, the kernel began to grow rapidly. For example, Berkeley's famous contribution to Unix was a fully functional TCP/IP networking stack. A rapid influx of other new functionality in the core kernel space has resulted in modern versions of Unix (and Linux, which is essentially a clean room rewrite of Unix) having 2-3 million lines of code in their kernel alone.

