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> I’ve experimented with Asahi Linux on my iMac, and while it offers a generally great experience, the ARM Linux ecosystem, especially with 16K pages, doesn’t q

> I’ve experimented with Asahi Linux on my iMac, and while it offers a generally great experience, the ARM Linux ecosystem, especially with 16K pages, doesn’t quite meet my daily needs. I would be interested in hearing more - I was given to believe that most open source software was fine on any of the major architectures[0], and I've not heard of the 16k thing at all (is Asahi doing something nonstandard with memory pages?) [0] Albeit with POWER somewhat weaker and SPARC mostly lost. But I thought ARM was in good shape, and MIPS has been weirdly resilient.

dji4321234 2y ago
The IOMMU on Apple Silicon only supports 16K pages. The page allocator on Linux only supports unified page sizes. Ergo, to make both IOMMU mappings and userland software work, everything needs to have 16K pages (on OSX, this isn't an issue, because XNU supports mapping both 4k and 16k pages). It's not really non-standard so much as it is new-standard or different-standard. Aarch64 officially supports 4K, 16K, and 64K pages. This flexibility in the aarch64 ABI means that most compilers already produce 64K aligned load segments for aarch64, so it's not a huge deal except for software that works at a low level and makes assumptions about mmap (for example). The main software that's truly affected beyond just needing recompilation or tweaks is x86/x86-64 emulation software, since x86 is pretty tightly coupled to 4k pages.