Re:Airyx OS
by throw0101a on Thursday August 05, 2021 @07:03AM
(#28072080)
> MacOS because XNU is based on Mach, and it was forked (Edit: from 4.3BSD) in 1988
As another commenter noted: XNU = Mach + FreeBSD.
What you are referring to is what NeXTSTEP was, Mach + BSD4:
* https://en.wikipedia.org/wiki/NeXTSTEP#Unix
By the time Apple got to them it was a few years later, and so they decided to updated that part of the kernel, and also brought in FreeBSD's userland.
>XNU is based on Mach
Partially, XNU is Mach AND the FreeBSD-Kernel:
If you look at the source of a lot of drivers on MacOS a few years ago, they were heavily based on the FreeBSD drivers.
The XNU kernel does not have a stable syscall ABI so perhaps it doesn't matter if the syscalls are different because the implementation of libSystem can convert as appropriate in userspace (see also: WINE).