Date: Mon, 6 Oct 2008 18:36:59 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: "Dr. Aharon Friedman" <afriedman@drsns.com> Cc: freebsd-stable@freebsd.org, David Sanders <dsuzukisanders@gmail.com> Subject: Re: Is FreeBSD a suitable choice for a MacBook? --- WHY? Message-ID: <alpine.BSF.1.10.0810061829190.59341@fledge.watson.org> In-Reply-To: <C070B5C3-5EBC-42D6-A194-69AF2CAD7184@drsns.com> References: <363BDDAF-76C7-49AE-A8F5-EE1995C4CCBF@drsns.com> <6228eb140810060825g784d0d1fle6738d3186cc4451@mail.gmail.com> <C070B5C3-5EBC-42D6-A194-69AF2CAD7184@drsns.com>
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On Mon, 6 Oct 2008, Dr. Aharon Friedman wrote: > Sorry, I meant BSD. > > Here is the link: > > http://www.freebsd.org/news/press-rel-3.html > > Aharon Friedman I don't see the origina message you replied to on the list, so am replying to it via your post... >> I'm just a lurker, but even I know that only some of the userland apps in >> OS X are BSD-based. The kernel is mach microkernel based and not even >> slightly similar. This claim regarding the kernel is highly inaccurate. There are significant quantities of FreeBSD, Mach, and Apple-originated code in the Mac OS X kernel, both because Apple pulled in a lot of FreeBSD code early on, but also because code moves between the two kernels fairly easily and fairly frequently, and in both directions. You'll find a FreeBSD-derived VFS, network stack, and countless other kernel parts in Mac OS X from their first open source drop forward. More recently, though, you'll find that the Audit implementation present in FreeBSD 6.x and later is based on the Mac OS X kernel audit code, and the TrustedBSD MAC Framework that appeared in Mac OS X Leopard is straight from FreeBSD. It's certainly true that there's a lot of non-FreeBSD code -- XNU uses the Mach scheduler and Mach IPC, and a quite different driver framework, for example. There's also some convergent evolution: FreeBSD contains a Mach-derived VM that also comes from the original Mach project. Finally, just to be clear: XNU is not a micro-kernel, even though it contains significant amounts of Mach code. The "microkernel" and remainder of the kernel run in a single address space, and although certain separation is (often) maintained in the source code / abstractions, the Mach, FreeBSD, and device driver parts run in a unified and tightly integrated way. Robert N M Watson Computer Laboratory University of Cambridge
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