Asahi Linux Faces M4 Hurdles: Apple's Silicon Changes Pose New Challenges

The Asahi Linux project is encountering difficulties while attempting to bring the Linux operating system to Apple M4 Macs. After successfully supporting M1 and M2 chips, developers are finding that changes in the M4's architecture have made it significantly more challenging to work with. Specifically, issues arise when trying to run the m1n1 bootloader due to changes in how Apple configures its Secure Page Table Monitor (SPTM). This prevents proper communication from Exception Level 2 (EL2) with the Memory Management Unit (MMU), making it difficult to set up pagetables for Linux and complicating efforts to reverse-engineer Apple's XNU kernel. Despite these challenges, developers are exploring potential solutions, such as hijacking XNU exception handlers and pagetable code, although a clear timetable for M4 support remains uncertain.