Linux/PPC is the native port of the Linux operating system to the PowerPC processor. The effort to port Linux to PowerPC began in 1995 by Gary Thomas, and Australian developer Paul Mackerras initiated work on porting Linux to the Power Macintosh hardware. Linux now runs on almost every implementation of the PowerPC processor, including the 60x and 750, and the less-known 840 and 860 processors.
While the Linux port itself is called Linux/PPC (note the slash in the name), the most popular distribution, and the company maintaining the distribution, are called LinuxPPC (no slash). In this appendix, I provide information about the general port as much as possible, but some details will change in the next release (5.0) of LinuxPPC in any case.
Linux on PowerPC has become popular in the past two years as Mac OS users have started to search for alternatives to the Mac OS. For one thing, it's fast. When people install Linux, they're amazed at how fast their Macs really are. Linux can turn an old PowerMac 7500 into a responsive and capable machine, and it really unleashes 604 and 750 (G3) machines. It's also quite stable. When a Linux application crashes, it doesn't crash the OS as well.
And then there's multitasking. Linux can run a lot of programs at the same time and not slow down. When you click on a menu in the Mac OS, everything stops until you release the mouse button. The Mac OS can't do anything but draw that menu. A Mac OS-based web server that I used to administer was disabled overnight because of this. When the mouse button was unstuck the next morning, the server promptly crashed when the listserver tried to process all of the backlogged email messages that had accumulated overnight. All this because of the mouse button being stuck! (Linux has no such problems with the mouse buttons.)
Another excellent example of the benefits of Linux multitasking: Photoshop can run only one filter at a time. And the whole Mac is tied up in running the filter. LinuxPPC ships with a Photoshop-like graphics application called The GIMP. Unlike Photoshop, GIMP can execute several filters simultaneously, and you can switch to other applications and keep working while GIMP runs the filters. (You can even hold down the mouse button.)
The most popular distribution for the PowerPC is called LinuxPPC (without the slash), which is developed and sold by LinuxPPC, Inc. You can order LinuxPPC on CD-ROM from http://www.linuxppc.org.
Another Linux distribution that is popular among very advanced Linux users is called Debian. The Debian for the PowerPC distribution is not as polished as the LinuxPPC Inc. distribution and is not available on CD-ROM. However, users who are familiar with Debian for other platforms may wish to use it. The Debian GNU/Linux web site, http://www.debian.org /ports/powerpc/, should provide up-to-date information about the status of the Debian project. The instructions for installing Debian GNU/Linux on top of a base LinuxPPC are available from:
LinuxPPC Inc. is an active supporter of the Debian project and has contributed hardware to the Debian organization.http://www.dartmouth.edu/cgibin/cgiwrap/jonh/lppc/faq.pl?file=572
LinuxPPC Inc. has developed a demonstration version of LinuxPPC that can be booted straight from the Mac OS. This version, called LinuxPPC Live, is a 105 MB version of LinuxPPC and doesn't require any installation or configuration on the part of the user. To download LinuxPPC Live, see the list of mirror sites at http://www.linuxppc.org /mirrors.shtml.
LinuxPPC runs on any PCI-based Power Macintosh, which includes the iMac, the PowerMac G3, and the PowerBook 3400 and G3 models. As of this writing, the iMac is a little difficult to get Linux running on. Special iMac installation instructions are at http://www.linuxppc.org/iMac/. We hope the upcoming LinuxPPC 5.0 will have better iMac support.
When the AIM (Apple-IBM-Motorola) coalition designed the PowerPC processor, they created two reference designs for future hardware. The first design was called PReP, the PowerPC Reference Platform. PReP machines were intended to be servers and high-end workstations. Apple, Motorola, and IBM all made PReP boxes: the Apple Network Server 500 and 700, the Motorola FirePower and PowerSTACK, and various IBM RS/6000 computers. These machines could run IBM's Unix variant, AIX, and a version of Windows NT for PowerPC. (Very few people knew that NT for PPC existed. Even fewer used it.)
Apple and Motorola abandoned their PReP boxes, and IBM stopped using the PReP design in favor of the newer Common Hardware Reference Platform (CHRP) design. Many Apple Network Servers have been successfully resurrected with LinuxPPC, much to the delight of their owners.
The CHRP platform was going to be the basis of cheap Macintosh cloning. The CHRP boards had both PC and Macintosh serial and keyboard ports and booted the Mac OS from a ROM DIMM chip. When Apple canceled its Mac OS licensing program in 1996, the hope of inexpensive Mac clones evaporated. But CHRP has resurfaced in 1998: the Apple iMac and Blue & White G3s are CHRP-based. IBM's RS/6000 workstations are also CHRP-based. IBM has become very interested in Linux on PowerPC and has been assisting with the port Linux/PPC to their newest RS/6000 models.
The PowerMac 6100, 7100, and 8100; and Workgroup Server 6150, 8150, and 9150 cannot run LinuxPPC. These machines used the NuBus architecture and don't have the PCI or Open Firmware circuitry that LinuxPPC depends on to boot.
There is a variant of Linux that runs on these early machines called MkLinux. MkLinux is really the Mach microkernel (also used in Apple's Mac OS X Server) running the Linux kernel in server mode. For most practical purposes, MkLinux is just another version of Linux, albeit one that runs on the old NuBus PowerMacs. Also, MkLinux is binary compatible with Linux/PPC, which means that applications compiled for Linux/PPC will run on MkLinux, and vice vera. MkLinux is a little bit slower than LinuxPPC, but it's the only option available for the oldest PowerMacs right now. You can find information on MkLinux at http://www.mklinux.org.
The PowerMac/Performa 5200, 5300, 6200 and 6300 series can't run any version of Linux at all. The only exceptions to this are the Performa 6360, a PCI-based machine that is capable of running LinuxPPC and the Performa 61xx-series (relabelled as PowerMac 6100 computers) which can run MkLinux.
There are a few types of hardware that LinuxPPC can't use. Some of them, such as specialized SCSI cards, video cards, and USB expansion cards, can't run on Linux because they lack a driver. LinuxPPC can't use the Apple GeoPort modems that shipped with the Apple Performa series.
The GeoPort modems are "software modems." Software modems are 90 percent software, which the Mac uses to emulate a hardware modem. The tradeoffs are speed, stability, and compatibility. Under the Mac OS, GeoPort modems are very slow and unstable, and they can't function at all under Linux since there aren't any drivers available for them. The only solution for these machines is to remove the modem, which may be an expansion card inside the computer, and replace it with an external modem. Relatively fast 33.6 and 57.6 kbps modems can be picked up for $50 to $100.
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