Darwin Version

[Brandon Allbery]

On Mon, Oct 5, 2015 at 6:42 PM, Dave Horsfall <dave at horsfall.org> wrote:

> On Sat, 3 Oct 2015, Ryan Schmidt wrote:
> > > Remember: under the bonnet (ObUSA: hood) the Mac runs FreeBSD.
> >
> > OS X is underpinned by Darwin, not FreeBSD. Darwin is based on NeXTSTEP,
> > BSD, XNU and other projects, and of course a great deal of independent
> > work by Apple.
>
> You're saying that Darwin was written from scratch and not evolved from a
> modified FreeBSD 4.1, or am I thinking of an earlier MacOS?
>

It was never derived from FreeBSD 4.1.

CMU Mach was a custom-written microkernel, hosting an OS which was a
heavily modified 4.2BSD (the original Berkeley Source Distribution, long
predating FreeBSD). NeXTStep took this and updated it. OS X took that and
updated it again, including replacing much of the userspace that was not
Darwin-specific with FreeBSD-CURRENT as of that time, and periodically
updates those parts of the userspace from the latest FreeBSD-CURRENT. The
kernel, however, is still largely custom. Some subsystems were originally
borrowed from FreeBSD-CURRENT (the original USB stack, for example), but
Apple later rewrote them (and in the case of USB, that was badly needed;
FreeBSD still has significant USB stack issues). The core of the kernel is
not, however, related to FreeBSD except in being a heavily rewritten
version of FreeBSD's ancestor.
-- 
brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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