Developer cakehonolulu ported Linux to the Atari Jaguar game console from 1993. The console managed to load the Linux kernel 7.2.0-rc1+ along with a minimal user environment based on BusyBox, and this was realized not only in an emulator but also on real hardware through a cartridge.
The task was non-trivial due to the Jaguar's architecture. The console has only 2 MB of RAM, up to 6 MB of ROM on the cartridge, and a Motorola 68000 main processor without an MMU. For such hardware, the usual Linux booting method is not suitable, so the developer used NOMMU mode for m68k/uClinux and a flat memory model.
To fit the kernel within the console's limitations, it was split between memory and the cartridge: unchangeable sections like .text and .rodata were executed directly from ROM using XIP, while the mutable .data and .bss were located in RAM. For early message output, the DSP chip Jerry was used, which has TXD/RXD serial lines and timers, and later the developer added a simple console driver for the Tom chip to ensure output worked on the actual console. These details are described in the section about what is required for Linux to boot on the Jaguar.
The user environment had to be maximally stripped down. Due to the absence of an MMU, FLAT binaries were used instead of ELF files; BusyBox runs directly as a shell without the standard applet symlink installation since that led to memory shortages. Configuration of uClibc through Buildroot was also required, including a simpler malloc-simple memory allocation strategy; more details are covered in the section Userspace.
There is almost no practical benefit to such a port: the Atari Jaguar does not turn into a convenient Linux computer. However, the experiment demonstrates how far support for old hardware can be stretched in Linux and how resilient the m68k architecture remains. The sources of the modified kernel have been published in the repository cakehonolulu/linux_jag.
Source: linux.org.ru
