Comment by torstenvl
2 days ago
> macOS is not BSD
No. This is a common contrarian take, but it's nonsense. macOS is built on Darwin which, along with XNU, traces its lineage through NeXTSTEP to 4.3BSD.
macOS is every bit as much of a BSD derivative as FreeBSD is.
I'm aware of its lineage but there's really precious little left from its BSD origins.
https://github.com/apple-oss-distributions/xnu/tree
You'll find there's a great deal left. Have a look at all the fundamental datastructures (proc, vnode, tty, file to name a few) for a starting point.
"Nonsense" is a strong word ;-)
Here's a contrarian-squared take: in reality, the question "Is macOS a BSD" is malformed. It makes some sens, but is more confusing than it's worth.
Yes, NeXT was built on Mach, which was itself basically an evolution of the Accent microkernel married with BSD, when BSD was a proper noun.
In fact, NextStep 0.8, the first public "pre-release", has left support in for A.OUT executables. The included ex and vi binaries are indeed A.OUT executables taken straight from BSD! In the very next release, support for A.OUT was removed, leaving only the Mach-O loader.
XNU is not derived from the Mach that NeXT was, though, but from the OSF Mach kernel, which was continued at the University of Utah. The BSD "bits" were selectively copied from the extent continuations of BSD, or rewritten from scratch. The XNU kernel doesn't strongly resemble any particular *BSD tree, to my knowledge.
Darwin's origins are messier, since it looks like it was a direct continuation of the existing NeXT packaging (but only Apple would know for sure). NeXT, very much unlike BSD, split its userland into distinct packages, which were versioned independently. This practice has carried on to this day, where e.g. Darwin's libc is packaged and versioned separately from the kernel and other utilities.
For that matter, for a very brief period of history, Darwin used Debian's dpkg for building and installing packages. Evidence of this stayed until OS X 10.4-ish, in the Darwin releases, but they returned to NeXT style BOM files for package management.
All that to say, does NeXT/macOS have a BSD-like userland? Yes, but so does Chimera Linux. Does the kernel resemble BSD? In some ways yes, but in many ways no, it's very semantically different.
And is it descendant from BSD? Again, "yes", but it also doesn't really "come" directly from BSD anymore than, say, OSF/1 did. There's no specific BSD it forked from, and no specific point at which it ever really looked like BSD, in terms of userland, packaging, or kernel semantics.
So I think the question just doesn't make much sense to ask.
It is a BSD. It has always been a BSD.
Saying "It's not like a *BSD" is a category error.
Is a wolf not a dog just because it's different from dog breeds with "Dog" in the name?
More succinctly:
- Darwin has no direct BSD ancestor. Unlike {Net,Free,Open}BSD and the more obscure ones (Bitrig, anyone?) there was never a point in time where it directly "connects" to the BSD lineage. The other BSDs all can trace their repositories back to CSRG's BSD.
- Darwin isn't stored or built like a BSD. The BSDs have massive monorepos containing all of the source, traditionally checked out to /usr/src, while Darwin is split into many independently versioned packages, (usually) compiled with Project Builder/Xcode.
Yes, the C API is derived from and supposed to resemble BSD, and much of the userspace was copied from a BSD-derivative (this has grown over time, as Apple (and the BSDs) replaced GNU utilities).
But that's why I would call macOS/Darwin "BSD-like" or "BSD-derived" rather than "a BSD".
Also, this isn't meant to be taken too seriously. I just like "OS taxonomy", and I think macOS/Darwin is distinct enough to qualify as a separate species ;-)
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