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>Unix on top of Mach Didn't Mach start out as a replacement kernel for BSD? Building a Unix on top of Mach is like building a truck over truck chassis.
by bitofhope 9y ago
>Unix on top of Mach
Didn't Mach start out as a replacement kernel for BSD? Building a Unix on top of Mach is like building a truck over truck chassis.
- dfox 9y agoIt did not. Mach is traditional microkernel which provides IPC mechanism, process isolation and (somewhat controversially) memory mapping primitives and not much else. In late 80's/early 90's there were various projects that attemted to build unix on top of that as true micro kernel architecture with separate servers for each system service. Performance of such design was horrible and there are two things that resulted from that that are still somewhat relevant: running whole BSD/SysV kernel as Mach task, which today means OS X and Tru64 (at the time both systems had same origin as both are implementations of OSF Unix) and just ignoring the problem which is approach taken by GNU/Hurd.
- snvzz 9y ago>slowness Worth noting that's because Mach IPC is extremely slow, an order of magnitude slower than L4 family.
- GeekyBear 9y agoCorrect. The Mach research project at Carnegie Mellon aimed to build a replacement kernel for BSD that supported distributed and parallel computing. Next's VP of Software Engineering, Avie Tevanian, was one of the Mach project leads. Richard Rashid, who lead the Mach project ended up running Microsoft Research's worldwide operations. Their work on a virtual memory subsystem got rolled back into BSD. https://en.wikipedia.org/wiki/Mach_(kernel) https://en.wikipedia.org/wiki/Mach_(kernel) The Computer History Museum has an interesting long form interview with Avie: Part 1: https://www.youtube.com/watch?v=vwCdKU9uYnE https://www.youtube.com/watch?v=vwCdKU9uYnE Part 2: https://www.youtube.com/watch?v=NtpIFrOGTHk https://www.youtube.com/watch?v=NtpIFrOGTHk