Darwin only half BSD. It uses a Mach kernel and Bash but BSD utilities instead of coreutils. It’s development and administrative utilities along with its init system are custom as well.
Fair enough, but that still means this statement (made by ArgylSound): “iOS’ kernel has almost nothing to do with any current BSD distribution.” is false.
There it clarifies that it is "mostly" FreeBSD. The Mach being used also differs significantly from CMU Mach and what you might find by looking for Mach3/4 source dumps.
One of the biggest challenges in "converting" NeXTSTEP (MacOS's predecessor) to OS X was both updating software to newer versions and eliminating expensive licenses from AT&T and Adobe.
NeXTSTEP was a "capital U" UNIX with AT&T proprietary code, based on 4.3/4.4BSD (encumbered). Every copy needed a UNIX license and royalties to AT&T.
NeXT was based on Mach2, which had 4.3BSD deeply integrated into the kernel source tree. Device drivers were both native BSD ones along with a "DriverKit" interface that used Mach messages to write userland device drivers.
CMU Mach v3 and v4 cut out all the BSD code and put it into a userland "UX Server", a model incompatible with NeXT. So instead, Apple took the OSF/1 Mach kernel, derived from Mach 2.5, and replaced the BSD subsystem code with 4.4BSD-lite, gradually updating its subsystems with FreeBSD ones.
So TLDR, Darwin/XNU has both a BSD userland and essentially a FreeBSD kernel. When you make a "UNIX-y" syscall from C in MacOS, you're "talking" to a "FreeBSD kernel".
Darwin only half BSD. It uses a Mach kernel and Bash but BSD utilities instead of coreutils. It’s development and administrative utilities along with its init system are custom as well.
Fair enough, but that still means this statement (made by ArgylSound): “iOS’ kernel has almost nothing to do with any current BSD distribution.” is false.
XNU, Darwin's kernel, is Mach + FreeBSD[1].
[1] https://github.com/apple/darwin-xnu
For more background, see https://developer.apple.com/library/archive/documentation/Da...
There it clarifies that it is "mostly" FreeBSD. The Mach being used also differs significantly from CMU Mach and what you might find by looking for Mach3/4 source dumps.
One of the biggest challenges in "converting" NeXTSTEP (MacOS's predecessor) to OS X was both updating software to newer versions and eliminating expensive licenses from AT&T and Adobe.
NeXTSTEP was a "capital U" UNIX with AT&T proprietary code, based on 4.3/4.4BSD (encumbered). Every copy needed a UNIX license and royalties to AT&T.
NeXT was based on Mach2, which had 4.3BSD deeply integrated into the kernel source tree. Device drivers were both native BSD ones along with a "DriverKit" interface that used Mach messages to write userland device drivers.
CMU Mach v3 and v4 cut out all the BSD code and put it into a userland "UX Server", a model incompatible with NeXT. So instead, Apple took the OSF/1 Mach kernel, derived from Mach 2.5, and replaced the BSD subsystem code with 4.4BSD-lite, gradually updating its subsystems with FreeBSD ones.
So TLDR, Darwin/XNU has both a BSD userland and essentially a FreeBSD kernel. When you make a "UNIX-y" syscall from C in MacOS, you're "talking" to a "FreeBSD kernel".