Linux on the Atari Jaguar

What in the tarnation is an Atari Jaguar?

Released in North America in November of 1993, the Atari Jaguar promised to be the new cool kid in the block thanks to it's (Highly debated) 64 bits of pure power.

The Atari Jaguar

The console itself ended up being a commercial disaster, even after the release of the CD addon, the Jaguar CD; which managed to sell even less units in a desperate attempt to try and compete with the Sony Playstation and the Sega Saturn.

The Atari Jaguar CD Add-on

Why in the tarnation Linux of all things?

Interestingly enough, to this day, Linux has architecture code for the 68000-family of processors. 68040, 68030, 68010... and even the original base 68000 processor. All neatly structured under arch/m68k/

.

As a refresher, the Motorola 68000 was a CISC processor with mixed 16-32 bit capabilities (It's usually described as being 32-bit internally due to the register width length and 16-bit because the data bus was 16-bit, so 2-byte transfers at a time).

It had a 24-bit address bus, 2 to the power 24; thereabout a maximum of 16MBs of addressable memory.

It was released on 1979 to compete with the soon-to-be-released 16-bit CPUs of the era.

The Motorola 68000

Overall, it got lots of traction commercially; it ended up being incoporated in lots of popular commercial hardware. Biggest contenders are the original Macintosh (And Apple Lisa), the Commodore Amiga series of computers (With varying generations of the 68000), the Sega Genesis/Megadrive, the Neo-Geo AES, Plexus workstations... and the Jaguar.

Let's now address the elephant in the room, why Linux.

Well, it's easy; because we can

(-ish).

jmp _linux?

Doing a bringup for a new 68000-based Linux port should be easy... right? Well... you're in for a good time.

As you may know (Or not), there's an extended thought that Linux requires an MMU to run (You know, being able to use virtual memory is a good thing if we want to run software w/o having day-long headaches).

Technically you are kind of right, but there's uClinux; which precisely makes this feasible. At some point it stopped being a downstream fork of Linux to become part of it; thankfully it's baked in for m68k

(And well, the flat memory model and the rest of requirements you can imagine that an MMU-less system has).

Okay so, we enable all the required configuration flags on the Linux menuconfig

(To basically tell it not to use an MMU and use the Flat Memory model), we compile and it