[Software] Asahi's plan for Linux on Apple's new silicon shows Cupertino has gone back to basics with iOS booting.

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The Asahi Linux project has published the first progress report detailing its effort to port Linux to the Apple Silicon platform.

The lengthy blog post describes in extensive detail the challenges faced by the project in understanding how Apple’s home-grown proprietary chippery works on a fundamental level, as well as the circumventing the various non-standard quirks that limit the ability to boot third-party operating systems.

The report, written by kernel hacker and Asahi Linux co-founder Hector Martin, unfortunately doesn’t conclude with a link to a fully working Linux distro. It does, however, illustrate how widely Apple Silicon-based Macs diverge from standards you might typically see.

The boot process, for example, isn’t what you’d expect to see on a conventional ARM64 system, but rather “a bespoke Apple mechanism” originating from the early days of iOS, with design elements derived from the Open Firmware specification as seen with the New World ROM Macs.

This has forced the Asahi Linux project to develop a bespoke bootloader for Apple Silicon machines called m1n1, which aims to take care of as many ‘Apple-isms’ as possible. But it’s a bit more than that.

The origins of m1n1 lie in mini, a project created by Martin as part of his research into jailbreaking the Nintendo Wii. While it supports the booting of third-party code, it also allows researchers to control the machine in real-time from a development computer. By using its interactive shell, or writing simple Python scripts, you can enumerate how the Apple Silicon processor works on a low, bare-metal level.

This has allowed the Asahi Linux team to identify features that are distinct to the Apple Silicon M1 processor, such as configuration bits designed to improve performance when running x86 code in Rosetta.

“Using m1n1, we’ve been hard at work documenting Apple’s custom Arm instructions, Apple-specific system registers, hardware such as the Apple Interrupt Controller, and more,” Martin wrote.