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Apple locks down Mac OS X for Intel

updated 09:20 am EDT, Wed May 17, 2006

OS X for Intel locked down

Users cannot build a custom kernel for their Intel-based Mac OS X systems. Infoworld reports that Apple has closed down Mac OS X by refusing to release the source code for Intel version of the Darwin open source Mach/Unix core--in part due to the fear of users pirating the operating system for cheaper PC clones. "The Darwin open source Mach/Unix core shared by OS X Tiger client and OS X Tiger Server remains completely open for PowerPC Macs. If you have a G3, G4, or G5 Mac, you can hack your own Darwin kernel and use it to boot OS X. But if you have an Intel-based Mac desktop or notebook, your kernel and device drivers are inviolable. Apple still publishes the source code for OS X's commands and utilities and laudably goes several extra miles by open sourcing internally developed technologies such as QuickTime Streaming Server and Bonjour zero-config networking. The source code required to build a customized OS X kernel, however, is gone. Apple says that the state of an OS X-compatible open source x86 Darwin kernel is 'in flux.'"

The report notes that while only client versions of Mac OS X for Intel-based machines have been released so far, the server version may be affected more by Apple's apparent change in philosophy.

"Apple has only shipped client systems, the users of which care least about openness. Soon, though, Apple will break out Intel variants of the kinds of machines that InfoWorld readers buy and on which I depend; namely, servers and workstations," according to the Infoworld columnist. "I hope that Apple's flux settles into a strategy that favors demanding users and developers."

Performance is one reason users may want a custom kernel--especially with the forthcoming release of server- or workstation-based Macs using 64-bit Intel ships (rather than the 32-bit chips used in current Intel-based Macs).

"Apple's retreat to a proprietary kernel means that all users must accept a fixed level of performance. The default OS X kernels are built for broad compatibility rather than breakneck speed and throughput," according to the report.

by MacNN Staff





  1. chadpengar

    Joined: Dec 1969



    This is old news and only speculation. Apple has stated that there is not (yet) a unified source base, which is supposed to happen in Leopard, and there re lots of possible reasons why the x86 kernel has not (yet) been released, not least of which is that Leopard is closer and packaging it up separately from the PPC takes effort and the intel releases are still new...

    This is non news.

  1. RevEvs

    Joined: Dec 1969


    Did i miss this

    Did i miss something? Are we able to comile, say, a g5 optimized kernel?

    I assume its not easy as someone would have done it by now

  1. Interlard

    Joined: Dec 1969


    New kernel, please!

    I hope this 'flux' means they are working on giving us a new kernel that performs better than Mach.

    I'm sure the performance boost is worth having to wait for new kernel extensions.

  1. ajhoughton

    Joined: Dec 1969


    Why this has happened

    The *user* community's poor behaviour and blatant disregard for copyright have prompted this. Nothing more, nothing less.

    If you crack software, or if you are running OS X on a PC, *you* are personally to blame for Darwin x86 not being Open Source.

  1. ajhoughton

    Joined: Dec 1969



    It's nonsense to suggest that any significant number of people would want to rebuild the Darwin kernel for "performance" reasons.

    That may have been true on Linux, where the drivers can be built in to the kernel, and where there are many options to enable or disable support for specific backwards-compatibility features and specific experimental features of PCs, but Darwin is targetted at a very specific type of machine and its drivers are always packaged separately, with a defined binary interface between them and the kernel.

    No, the real shame is that software developers do not have access to the x86 kernel sources. Having the kernel code available is very useful for some types of development. If we want it now, we will have to license it specially from Apple, signing NDAs in the process, and the cost of certain types of software may rise as a result.

    Incidentally, it will also make running Linux or BSD on the machines that bit harder, since any non-standard architectural features that need to be supported by the kernel will now have to be reverse engineered (as was the case for the old Mac OS).

  1. ajhoughton

    Joined: Dec 1969


    Replacing Mach

    Replacing Mach is very unlikely IMO. It is pretty intimately connected with many parts of Mac OS X, and many Mach features are used to good effect.

    Also, blaming Mach for making OS X slow is missing the point. There is a trade-off between the neat features Mach provides (like the fact that 32-bit processes really have 4GB of address space or the fact that exceptions can easily be handled by other processes) and performance, and Apple have been and still are working on the Darwin kernel to achieve an appropriate balance. The version of Mach in OS X is far from standard, and has a lot of Apple-specific tweaks in it... for example, the external pager interface has pretty much gone, as has support for using Mach ports over a network. Both changes were made to improve performance.

    No, I think you're much more likely to see incremental improvements in Darwin's performance than you are to see a shift away from a Mach-based kernel.

  1. umijin

    Joined: Dec 1969


    Too bad...

    That's too bad, as Apple can't make a decent light notebook computer, and there is no indication that they will any time soon.

    5.2lb bricks like the MacBook are 2 lbs heavier than similar sized offerings from Windoze makers like Sony and Panasonic. And I don't want to tote anything around heavier than my 4.2lb 12" G4 PB.

  1. resuna

    Joined: Dec 1969


    Old news, didn't happen

    This "news" broke MONTHS ago. Apple didn't update several parts of their code base when they did the last open source release, and in particular they didn't release the kernel and drivers for Intel. But that wasn't the only missing code.

    Since then Apple has updated several of the other open source trees... the kernel and drivers are the only part that hasn't been updated... and only on the Intel side.

    So, not only isn't it news, it's not true. They've failed to update one kernel, a tiny part of OSX. The rest of the source code is up-to-date, and even the non-open-source parts are still more open and better documented than the corresponding parts of Windows.

  1. Foe Hammer

    Joined: Dec 1969


    A Light Notebook?

    "And I don't want to tote anything around heavier than my 4.2lb 12" G4 PB."

    Someone needs either a wheelie cart or a Bowflex.

  1. tindrum

    Joined: Dec 1969


    Roll Your Own

    Yes, one can get the Darwin source, change it, and compile one's own. You have definitely missed something. As soon as Apple released the source, I signed up a the ADC and downloaded it. I have no clue what to do with source file, though, so I never made my own. It is not easy, and if someone does it, it's for a specific reason that most of us would not appreciate or get benefits. Also, the higher-level Cocoa routines are not Darwin, and are not available to regular people, so you can't compile the whole Mac OS for, say, an Itanium. You can run the what would be typical in a bare *nix environment, and much other cool stuff, though. If I recall, Darwin arrived around 2001. Don't quote me.

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