Linked by Stuart MacKenzie on Wed 2nd Jul 2003 18:31 UTC
Apple Are you a long time Windows user curious about the Apple Switch campaign? Are you wondering if you should try it? Read below for my experience with the whole thing... twice. Just over a week ago I purchased a new 12" Apple PowerBook G4...
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For the record...
by Bascule on Wed 2nd Jul 2003 23:19 UTC

OS X is not "FreeBSD" underneath. The userspace comes from FreeBSD partially, but many components of the userspace come directly from NeXT (i.e. NetInfo). OS X does not use BSD-style init either.

As for the kernel, OS X's process scheduler and VMM, which I would consider the two most important components of an operating system kernel, come directly from Mach. While FreeBSD's VMM is a descendant of Mach, it has been *heavily* modified over the past decade.

The components of the kernel that do come from FreeBSD are the unified buffer cache, the VFS, and the networking components. I would assume that the asynchronous I/O implementation and kqueue implementation are largely based on FreeBSD as well.

The bottom line is that Darwin is a combination of NeXT and FreeBSD components and XNU is a hybrid Mach/FreeBSD kernel, with the important components of the kernel being Mach, and the FreeBSD components being relatively uninteresting.