Mach/Darwin Binary Compatibility Hacker Interviewed

chromatic writes "Following up on an earlier story on NetBSD's fledgling Mach and Darwin binary compatibility layer, I've interviewed Emmanuel Dreyfus, who leads the project. The key questions are "what is it?", "what is it not?", and "what does it mean?""

Good...

[CoolVibe]

If you read the previous slashdot stoy, this confused a lot of people. I hope it's all clear now.

So, now I can run Darwin/OS X apps on my mac. Cool.

Re:Good...

[cyb97]

Can't wait 'till we can run Darwin/OS X apps on other platforms...
there's still some nifty tidbits that remain MacOS only...
Give me Final Cut Pro any day!

Re:Good...

[Matthias Wiesmann]

While Apple is certainly the main supplier of PPC based PCs, this emulation layer could make it possible to run Mac OS X on different PPC based machines that have some kind of NetBSD support [netbsd.org]:

• Unsupported Apple machines.
• IBM RS600 machines.
• BeOS machines.
• PowerPC-based evaluation boards.
• Motorola MVME PowerPC SBCs.
• PowerPC-based Amiga boards.

Whenever it makes sense to run Mac OS X on those beasts is another question altogether. Many of them probably don't have the horsepower for the GUI - some of them even don't have displays. The good news is that the lack of new PPC processor forces Apple to continue to optimise their system.

I suppose that if Mac OS X can run acceptably on one of those beasts, it will make sense to port darwin directly to it - in order for instance to use things like IO/Kit, but until then, it means people will be able to experiment and play. Heck! imagine if such a compatibility layer existed for Linux, you could run Mac OS X of an AS/400...

Re:Good...

[ocelotbob]

It's definitely possible. [maconlinux.org] It works pretty much like VMware, but it allows you to run OS X binaries on any PPC machine.

Re:Good...

[Anonymous Coward]

I'm running Jaguar on my unsupported PowerMac right now! Thanks to XPostFacto. My PMac 9600/300 to be exact. Upgraded to a G3-500 and it works fine, a little slow but fine. Installed a Radeon 7000 PCI and turned on Quartz Extreme.

It's not a new PMac, but at least I'm getting life out of a 5+ year old system. I plan to upgrade to a G4-700 and get some more life out of it. All that and 6PCI slots and 1.5GB of ram.

This will be it until the 970 Macs are mature.

Mach

[susehat]

What is so bad about mach? It looks to be very good.

Re:Mach

[RevAaron]

Some people seem to think it is slow. Not just Mach- it's usually a generalization made across all message passing microkernels vs. monolithic kernels. And a lot of times, it probably is a wee bit slower, but the argument that what is gained makes it worth it.

Requires an OS X license?

[gomerbud]

I am a bit sketchy on Dreyfus's comment about NetBSD/Darwin compatibility requiring a Mac OS X user license. Darwin contains most of Mac OS X except the WindowServer and GUI friends. A license should not be required until the WindowServer is functional which would then require the shared libraries for the GUI. If GNUstep ever really takes off, it should be possible to build a WindowServer workalike on a Darwin machine and distribute its libraries allong with the Darwin shared libraries. This would make a rather cool, free replacement for Mac OS X or Darwin on PPC.

Re:Requires an OS X license?

[gomerbud]

Quarts is specific to OS X's WindowServer. Any graphical apps running on NetBSD through Darwin emulation would probably be drawing to an X11 display. By linking to the GNUstep libraries, you would be providing the OpenStep 5 API while drawing using something like X11 shared memory. In any case, i doubt you would be using Quarts to draw stuff on NetBSD.

Only if you run Apple's GUI implementation

[yerricde]

I am a bit sketchy on Dreyfus's comment about NetBSD/Darwin compatibility requiring a Mac OS X user license.

From the article: "Therefore, in order to run a dynamically-linked application, you need the libraries from the emulated OS. The libraries are part of the emulated OS, and if you use them, you need a license for it."

It means you need a Mac OS X license ($0 with your PPC G3 or G4 processor based Macintosh computer unless it came with Mac OS 8.x or 9.x) to run Apple's implementation of the WindowServer libraries. You don't need such a license to run Cocoa binaries if and when somebody writes a WindowServer API compatible wrapper around gnustep.