The Forgetful CPU (Linux on M4)
Points and comments are a snapshot, not live.
A Linux developer details booting Linux on M4 Mac mini with SPTM and WFI erratum.
The author booted Linux on an M4 Mac mini, facing challenges with SPTM (Secure Page Table Monitor), locked registers like GXF and RVBAR, and a WFI instruction erratum that zeroes CPU registers. A workaround using debug_putc bisected boot failures to MMU init and interrupt controller writes. The WFI issue was resolved by replacing WFI/WFIT with NOP or a new bootarg, now merged into mainline Linux and m1n1. Secondary cores required a specific smp_start_offset. Work continues on peripherals and the m1n1 hypervisor for macOS tracing.
What commenters are saying
Commenters broadly praised the hacking effort, with some questioning Apple's hostility to open software. A split emerged: some argued Apple's locked ecosystems (iOS) are separate from macOS, which still allows booting custom OSes, while others noted Apple's lack of hardware documentation. One commenter recounted their switch from a buggy Lenovo to a MacBook for reliability. Another noted the M4's efficiency, particularly in single-core performance and battery life, as key reasons to endure macOS frustrations. Some speculated Apple might eventually lock down Macs like iPhones.