Giang Vinh Loc Creates "the World's Worst Linux PC" Using an Arduino UNO R3 and Its ATmega328P

Vietnamese embedded developer Giang Vinh Loc has taken Linux to new lows, by successfully booting to a console session on an Arduino UNO R3's Microchip ATmega328P eight-bit microcontroller — by having it pretend to be a 32-bit RISC-V processor.

"This is a port of mini-rv32ima (a minimum RISC-V emulator, capable of booting Linux) on ATmega328P (the core of Arduino UNO, a eight-bit AVR microcontroller)," Loc explains of the project. "So basically, this code is for booting Linux on [the] Arduino UNO. Yes you are reading it correctly, Arduino UNO can (theoretically, but not practically) boot Linux."

Loc's project builds on the work of Charles Lohr, who wrote mini-rv32ima late last year in just 400 lines of C code — the release of which triggered a race to see who could get it, and the Linux kernel the emulator supports, running on the most resource-constrained hardware. In Loc's case, that was an Arduino UNO R3 — a microcontroller board with an eight-bit 16MHz processor and just 2kB of static RAM (SRAM).

That, then, posed a problem: the Linux kernel may be able to squeeze itself into surprisingly little memory, but not all the way down to 2kB. The solution: convincing the emulator that an SD Card connected over SPI is RAM, vastly increasing the memory available to the kernel.

Performance, as you might expect, is more proof-of-concept than usable: "Complete boot time (from start to shell) is about 15 hours and 44 minutes," Loc admits — though this was later improved through the implementation of an instruction cache and a "lazy write system."

The full project write-up, including source code, is available on Loc's GitHub repository; "If you can run this," he writes, "you probably are running world's worst Linux PC. Enjoy!"