| https://wiki.freebsd.org/Myths#FreeBSD_is_Just_macOS_Without... >FreeBSD is Just macOS Without the Good Bits >This is as much a myth about macOS as about FreeBSD; that macOS is just FreeBSD with a pretty GUI. The two operating systems do share a lot of code, for example most userland utilities and the C library on macOS are derived from FreeBSD versions. Some of this code flow works in the other direction, for example FreeBSD 9.1 and later include a C++ stack and compiler that were originally developed for macOS, with major parts of the work done by Apple employees. Other parts are very different. >Darwin - which consists of the XNU kernel, IOkit (a driver model), and POSIX compatibility via a BSD compatibility layer - makes up part of macOS (as well as iOS, tvOS, and others) includes a few subsystems (such as the VFS, process model, and network implementation) from (older versions of) FreeBSD, but is mostly an independent implementation. The similarities in the userland, however, make it much easier to port macOS code to FreeBSD than any other system - partially because a lot of command-line utilities were imported along with the BSD bits from FreeBSD. For example, both libdispatch (Grand Central Dispatch in Apple's marketing) and libc++ were written for macOS and worked on FreeBSD before any other OS. >Apple's kernel programming guide goes into more extensive detail about the similarities and differences. https://developer.apple.com/library/archive/documentation/Da... >The BSD portion of the OS X kernel is derived primarily from FreeBSD, a version of 4.4BSD that offers advanced networking, performance, security, and compatibility features. BSD variants in general are derived (sometimes indirectly) from 4.4BSD-Lite Release 2 from the Computer Systems Research Group (CSRG) at the University of California at Berkeley. |