Building the XNU kernel on macOS Sierra

Re:Building the XNU kernel on macOS Sierra by nickpsecurity on Wednesday July 12, 2017 @11:54AM (#14753562)

The merging of Mach with UNIX was a mistake given it was one of the slowest, over-complicated microkernels. Far as I'm aware, they'd prefer to remove Mach but it's a big job at this point that might affect their ecosystem a lot. If you are interested in open microkernels, I encourage you to look into L4 family (eg OCL4 or OKL4) since they're far more advanced than Mach-based designs. Minix 3 does one with NetBSD userland and self-healing capabilities. GenodeOS is turning one into a desktop. IBM's K42 ran on NUMA machines. JX OS mixes one with a JVM to run the OS in Java. For security, GEMSOS was a security kernel w/ MAC. KeyKOS and EROS were examples of those doing capability-based security. Modern ones like Muen and seL4 just do separation w/ apps managing security policy.

EDIT: Windows is also a "semi-microkernel" with a microkernel inside of it on the bottom that seems to be used for consistent way of interfacing components more than anything. I'm not sure if it's still in there.

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Re:Building the XNU kernel on macOS Sierra by pcwalton on Wednesday July 12, 2017 @02:26PM (#14755143)

Mach is fine. The IPC primitives it exposes are a lot more straightforward than Unix sockets. The performance issues everyone talked about in the '80s are not really problems anymore in 2017.

L4's send/recv context switch trick is great until you get to SMP, at which point its performance necessarily moves closer to that of traditional microkernels like Mach.

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Re:Building the XNU kernel on macOS Sierra by mikalv on Wednesday July 12, 2017 @12:58PM (#14754215)

I've been playing a bit around with L4 kernels and some more of Minix 3 from before. Genode seems nice but never had the opportunity to test it yet.

The rest was all new for me, thanks for the information :)

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