Linux/m68k is the port of the Linux operating system to the Motorola 680x0 (or m68k) processors. Linux/m68k, the first project to port Linux to a non-Intel processor, was begun in 1993 by Hamish Macdonald and Greg Harp, who ported the kernel to the Amiga. Several Atari users, including Björn Brauel, Roman Hodek, and Andreas Schwab, adapted Hamish's kernel beginning later that year to run on Atari's 32-bit ST series of computers.
Since 1996, Linux/m68k has been adapted to run on a number of other systems, including the pre-PowerPC Apple Macintosh line, several models of VMEbus single-board computers from Motorola and BVM Ltd., Apollo Domain workstations, the HP 9000 series and Sun 3 workstations, and NeXT. Most recently, there has been a port to the Q40 and Q60, two new 680x0-based computers that are being manufactured in Europe. A related project, Linux/APUS, has ported Linux/PPC (discussed in Appendix D, "LinuxPPC: Installing Linux on PowerPC Computers") to Amigas with PowerPC processor cards; it is very much a hybrid of Linux/m68k and Linux/PPC.
As you can see from the diverse list of systems that Linux/m68k runs on, the challenge facing the m68k port was introducing enough flexibility into the kernel to cope with the variety of possible environments. Many of these abstractions--most notably, Martin Schaller and Geert Uytterhoeven's framebuffer and console abstractions--have since been incorporated into the mainstream kernel. These abstractions have meant that virtually every binary ever written for Linux/m68k--including the kernel image itself--can be run on every m68k platform without recompilation.
Linux/m68k has proven its robustness in the real world: several publicly accessible web servers, such as http://shadow.cabi.net and http://amiga.nvg.org, are running on Linux/m68k and one of the developers uses an Amiga running Linux as a web and mail server for his dormitory. Thousands of other users use Linux for myriad tasks from software development to text processing to academic research.
Linux, along with other free Unix clones, continues to provide m68k users with a dynamic, rapidly improving operating system not seen on these platforms since the heyday of the late 1980s and early 1990s.
Apple's choice of the name MkLinux for its microkernel-based Linux for PowerPCs and other platforms has caused no end of confusion; this confusion has been further compounded because an early port of Linux to the m68k Macs (now believed to be vapor as no code has ever been released) was called MacLinux.
The correct name for Linux on 680x0 processors is Linux/m68k; in particular, Linux for the pre-PowerPC Macintoshes should be called Linux/m68k for the Macintosh to avoid confusion with other projects. Neither of these is based on the microkernel or MkLinux.
As of this writing, active development of the 2.0 kernel series has stopped; the focus is now on producing a rock-solid 2.2 kernel in the near future. The latest Linux/m68k kernels can always be downloaded at http://sunsite.auc.dk/ftp/projects/680x0/; precompiled images are provided for stable kernels, and complete source trees and patches (relative to both previous versions and Linus's releases) are available for all versions.
Like other platforms, Linux/m68k has followed the libc roller coaster closely; thanks to the hard work of Andreas Schwab, our resident gcc and libc guru, we've never been left too far behind. At present, both major distributions ship with glibc 2.0 (libc 6); work is underway to prepare for the transition to glibc 2.1 (libc 6.1) in upcoming releases of Linux/m68k distributions. However, the kernel still supports both libc 4 and libc 5 applications, for those users who need them.
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