Apple Computer ( has had its differences with the freeware community. In particular, the League for Programming Freedom ( strongly disagrees with Apple's support of software patents and look-and-feel copyrights as ways to protect proprietary rights in software.

The GNU Project ( has also made unpleasant noises about these issues from time to time. (If software patents and look-and-feel copyrights are widely adopted, free software projects like GNU could be severely hampered or even driven underground.)

Consequently, it is somewhat surprising that Apple is funding the OSF Research Institute ( to develop MkLinux, a Mach-based version of the copylefted Linux ( operating system. It is even more surprising that Apple is funding both Power Macintosh and Intel versions of the system.

Why Mach?

The Mach microkernel provides an abstract layer onto which other operating systems may be ported. It also provides multiprocessor support, kernel-level thread support, and other interesting features. By porting OSF Mach to the Power Macintosh, Apple opens the way for a variety of research and even commercial operating systems to run on the platform.

Most Mach-based systems, including MkLinux, treat the UNIX kernel as a monolithic server process which fields every system call. This "single server" approach allows a relatively rapid port, but it doesn't make full use of Mach's capabilities.

More aggressive efforts, such as GNU's Hurd OS, divide up the functionality of the UNIX kernel into a large number (hurd? :-) of server processes. Because each of these processes must work through known interfaces, the resulting system should be much more modular, expandable, etc.

Why Linux?

Linux is the overwhelming favorite among users of free UNIX clones. The Linux community has hundreds of thousands of members, promoting very active development and exchange of software. Linux is also covered by the GNU General Public License, ensuring that Apple's contribution will not be used in some other vendor's proprietary product.

Why PowerMac?

A PowerMac-based version of Linux could be far less troublesome to install and maintain than any Intel-based OS. Power Macintoshes use intelligent busses like NuBus and PCI. This allows the OS (whether MacOS or MkLinux) to handle hardware configuration concerns such as DMA addresses and interrupt vectors.

Power Macintoshes are typically delivered as complete systems. Consequently, any operational PowerMac is likely to have most of the parts MkLinux will need. I have heard (and participated in) a number of PC installation horror stories. A reasonable alternative would be very interesting.

Why Intel?

The Linux community is overwhelmingly oriented towards Intel hardware. By porting MkLinux to the Intel platform, Apple opens the way for both Intel and PowerMac users to try out the new system, trade software, etc. And, should the merits of MkLinux justify a switch, it is not inconceivable that many Linux users would be willing to adopt a different kernel.

Actually, Intel is only one of many alternative platforms for MkLinux. Because the Mach microkernel has been widely ported, we could soon see MkLinux running on DEC, HP, IBM, and other machines. I have already heard interest expressed in a BeBox port of MkLinux.

Why Apple?

Apple sells a lot of computers into the higher education and scientific research communities. Many of these folks would like to be able to run Linux on their computers. The addition of Mach's capabilities only makes things better. Ike Nassi, Apple vice president of system software technologies, says:

This is part of Apple's overall effort to embrace more open industry standards, particularly those popular in the Internet community. This software will be particularly popular with Mac users in higher education as well as the scientific research communities who have asked for our support of Linux.


Apple's "MkLinux Developer Release 1" CD-ROM contains a snapshot taken in early May. Several thousand of these were produced; some may still be available. The MkLinux Web site ( has information on obtaining the CD-ROM, as well as recent snapshots, updates, documentation, etc.

Prime Time Freeware ( has been selected to publish Apple's reference release of MkLinux. "MkLinux: Mach/Linux for the Power Macintosh", being edited with the assistance and support of Apple, will contain a variety of reference material about Linux, Mach, MkLinux, and the Power Macintosh.