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Incredible story! The DEC Alpha that eventually emerged was ultimately responsible for Linux universality in the mid-1990s. As Linux was originally written to t

Incredible story! The DEC Alpha that eventually emerged was ultimately responsible for Linux universality in the mid-1990s. As Linux was originally written to take advantage of 68k based home PCs like the Atari and Amiga. DEC basically gifted one to the Helsinki CS dept in hopes they would port a free unix to it. The environment back then for workstations was wonderfully heterogeneous: HP Apollo, SGI, Sun, DEC and even the NeXT Color Cube all tried to differentiate and dominate. But were all subsumed by commodity x86 Linux on PCI architecture and the explosion of web servers running apache ;) Linux: A Portable Operating System https://www.cs.helsinki.fi/u/kutvonen/index_files/linus.pdf https://www.cs.helsinki.fi/u/kutvonen/index_files/linus.pdf

InTheArena 6y ago
Being very pedantic, Linux was very much built for 386 architecture. The 68K had a number of features missing that Linux originally leveraged from the x86 world. Atari and amiga were not initial targets for the runtime. The very first port of Linux To a different architecture was 68k, but it was really rough. Linus did then do the port over to the dec alpha as well as fix the aspects that were overly wedded to i386. I would also argue that to a very large degree Linux’s success was driven by the rising of x86 is the dominant compute platform for server architectures. It’s universality was very much a second order effect, and the paying off of technical debt.
relaxing 6y ago
Linus’s thesis contradicts this. The original Linux was not only extremely PC-centric, it wallowed in features available on PC's and was totally unconcerned with most portability issues other than at a user level. The original Intel 80386 architecture that Linux was written for is perhaps the example of current CISC design, and has high-level support for features other current CPU's would not even dream about implementing (see for example [CG87]). Linux did not even try to avoid using the x86 features available to those early versions — quite the opposite. Linux started out as a project to find out exactly what you could do with the CPU, and as such it used just about every feature of the CPU you could find ranging from using segments for inter-process protection to hardware assisted process switching. However, the initial unportable approach was a case of an unportable implementation rather than an inherently unportable design. The goal of being compatible with other UNIX's resulted in a system that had portable interfaces despite the implementation details. That portable design essentially made Linux itself reasonably portable. The first Linux that was based on a architecture different from the Intel 80386 was the port of Linux to the Motorola 680x0 family that actually got started rather early in the development of Linux. However, the original Linux/68k project was not really concerned with portability, but rather with making Linux run on 68k-based Amiga and Atari computers. ... While the Linux/68k project was in itself a huge step forward, the real portability work began when the author was offered an Alpha system by Digital in the hope of making Linux work on the new Alpha architecture. Very early it became clear that in order to be able to maintain both the stable Intel-based platform and support a new and in some respects radically different platform the kernel really needed some major re-engineering to make it fundamentally more portable. The issues and the end result is what is described in this paper.
- ArtWomb 6y ago
  Looks like I got my timeline somewhat backwards! Initial Linux build was the 32-bit x386 version, though 68k amiga portability also started rather early. Ultimately resulting in a variant for the 64-bit dec alpha, after receiving an AlphaStation 500. My recollection of the AlphaStation circa 2000: it was indeed a powerhouse for CAD type apps, though Silicon Graphics would come to dominate in arenas like Hollywood. Thanks for clarifying ;)

InTheArena 6y ago

Being very pedantic, Linux was very much built for 386 architecture. The 68K had a number of features missing that Linux originally leveraged from the x86 world. Atari and amiga were not initial targets for the runtime. The very first port of Linux To a different architecture was 68k, but it was really rough. Linus did then do the port over to the dec alpha as well as fix the aspects that were overly wedded to i386. I would also argue that to a very large degree Linux’s success was driven by the rising of x86 is the dominant compute platform for server architectures. It’s universality was very much a second order effect, and the paying off of technical debt.

relaxing 6y ago

Linus’s thesis contradicts this. The original Linux was not only extremely PC-centric, it wallowed in features available on PC's and was totally unconcerned with most portability issues other than at a user level. The original Intel 80386 architecture that Linux was written for is perhaps the example of current CISC design, and has high-level support for features other current CPU's would not even dream about implementing (see for example [CG87]). Linux did not even try to avoid using the x86 features available to those early versions — quite the opposite. Linux started out as a project to find out exactly what you could do with the CPU, and as such it used just about every feature of the CPU you could find ranging from using segments for inter-process protection to hardware assisted process switching. However, the initial unportable approach was a case of an unportable implementation rather than an inherently unportable design. The goal of being compatible with other UNIX's resulted in a system that had portable interfaces despite the implementation details. That portable design essentially made Linux itself reasonably portable. The first Linux that was based on a architecture different from the Intel 80386 was the port of Linux to the Motorola 680x0 family that actually got started rather early in the development of Linux. However, the original Linux/68k project was not really concerned with portability, but rather with making Linux run on 68k-based Amiga and Atari computers. ... While the Linux/68k project was in itself a huge step forward, the real portability work began when the author was offered an Alpha system by Digital in the hope of making Linux work on the new Alpha architecture. Very early it became clear that in order to be able to maintain both the stable Intel-based platform and support a new and in some respects radically different platform the kernel really needed some major re-engineering to make it fundamentally more portable. The issues and the end result is what is described in this paper.

ArtWomb 6y ago
Looks like I got my timeline somewhat backwards! Initial Linux build was the 32-bit x386 version, though 68k amiga portability also started rather early. Ultimately resulting in a variant for the 64-bit dec alpha, after receiving an AlphaStation 500. My recollection of the AlphaStation circa 2000: it was indeed a powerhouse for CAD type apps, though Silicon Graphics would come to dominate in arenas like Hollywood. Thanks for clarifying ;)