If you want to see how much different they are, have a look at

"Mac OS X Internals: A Systems Approach"

https://www.amazon.com/Mac-OS-Internals-Systems-Approach-ebo...

Since then, has macOS become even further away from BSD, with its own Network stack, XPC, SIP and many other architecture changes.

> only a small minority of the processes running on an OS X system.

Which are anyway not POSIX.

https://www.amazon.de/MAC-OS-Internals-Amit-Singh/dp/0321278...

I think you can do this on OS X using the Mach vm_XXX family of functions (I've only used them for querying state, though, rather than rearranging the mappings.)

The documentation is pretty terrible, though, so some experimentation may be necessary. It's also even less like the POSIX parts than the NS bits are...

(Apple doesn't seem to tell you much; OK references are https://www.gnu.org/software/hurd/gnumach-doc/Virtual-Memory... http://www.amazon.co.uk/Mac-OS-Internals-Systems-Approach/dp..., and, of course, http://www.opensource.apple.com/source/xnu/. The source has some reference-style documentation in it.

i was expecting something in more detail if you want a full in depth history on the mac os x and how it evolved, i would check out "mac os x internals: a systems approach"

http://www.amazon.com/Mac-OS-Internals-Systems-Approach/dp/0...