[vox-tech] Apple & Linux

[Rick Moen]

Quoting Bill Broadley (bill at cse.ucdavis.edu):

> In fact OSX just does this and uses a Mach kernel which has no relation to
> any of the Free/Net/OpenBSD kernels.

NeXTStep's kernel, xnu, was initially a fork of Mach 2.5 (if memory
serves) _plus_ 4.3[1] BSD layers on top.  However, they soon got fed up
with microkernel-caused development and performance problems they were
having, and ended those by heavily interconnected the original CMU Mach
core with the BSD layers above it.  (The result was no longer Mach, and
also no longer a microkernel.)

Around the time of NeXTStep's marketing reincarnation as OS X, the
kernel was looking pretty decript, so they started revision work --
including refreshing some of the Mach-derived code from Mach 3.0.
Providentially for them, at the time this work got underway, Wind
River's custody of FreeBSD and employment of many of its core team was
going badly sour, and would soon fall apart entirely.  Therefore, Apple
hired many of them as development staff, the best-known of them being
Jordan Hubbard.  They gradually replaced many parts of the userland code
with modern FreeBSD codebases, and also borrowed from the FreeBSD kernel
for some upper layers of Darwin / OS X's xnu one.

[1] Though I could swear that the original fork was actually from 4.2 BSD.

-- 
Cheers,                               I remember Fred, 1919 - 2005. 
Rick Moen                        http://linuxmafia.com/faq/Essays/fred.html
rick at linuxmafia.com