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FreeBSD differs quite substantially from the XNU kernel used by MacOS because XNU is based on Mach, and it was forked (Edit: from 4.3BSD) in 1988 - before Linux

FreeBSD differs quite substantially from the XNU kernel used by MacOS because XNU is based on Mach, and it was forked (Edit: from 4.3BSD) in 1988 - before Linux even existed. 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).

nix23 5y ago
>XNU is based on Mach Partially, XNU is Mach AND the FreeBSD-Kernel: https://www.youtube.com/watch?v=-7GMHB3Plc8 https://www.youtube.com/watch?v=-7GMHB3Plc8
- rjzzleep 5y ago
  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.
  - nix23 5y ago
    Yes sure they do, just look the presentation.
throw0101a 5y ago
> 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 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.