From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3e1162e604121717007ac5069a@mail.gmail.com> Date: Fri, 17 Dec 2004 17:00:32 -0800 From: David Leimbach To: Jack Johnson Subject: Re: [9fans] Acme mailreader In-Reply-To: <6e35c06204121715206e5ee022@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit References: <3e1162e6041216070874f424e5@mail.gmail.com> <9ccf822edf0a9a77c141ae47312638dd@collyer.net> <3e1162e604121710527abe8fd5@mail.gmail.com> <6e35c06204121715206e5ee022@mail.gmail.com> Cc: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Topicbox-Message-UUID: 1a5eb37a-eace-11e9-9e20-41e7f4b1d025 On Fri, 17 Dec 2004 15:20:54 -0800, Jack Johnson wrote: > On Fri, 17 Dec 2004 10:52:51 -0800, David Leimbach wrote: > > Mac OS X is not a microkernel architecture... but it does "have a > > microkernel" :). > > I wonder how much of this is just NeXT heritage rather than > purposefully to make the actual work of building/upgrading OS X any > easier (or any other potentially valid reason)? > I suspect they liked some of the SMP capabilities Mach was endowed with + the thread scheduling and VM. Even FreeBSD adopted the Mach VM at one point [but not the rest of Mach]. Chances are they have TONS of legacy code that requires a lot of work to get away from Mach. NeXT ran with Mach 2.5 and XNU is a modified OSF Mach 3 if I recall correctly. I don't think Mach is making anything easier for Apple except in possibly some of their real-time scheduling of threads for multimedia streaming and what-have-you. Other than that it's a pretty odd animal at times. It'd be interesting to see what would happen if they ever went with something like L4 [a more current and more successful at being a microkernel microkernel]. But L4 messaging is synchronous by specification and I think Mach has a lot of asynchronous behavior that might be hard to emulate initially. It'd be a bit of work... However NetBSD does now have some level of Darwin compatibility including a Mach layer so who knows!?!? It's pretty danged offtopic for this list though :) Dave > -Jack >