There's a ton of stuff not upstreamed. There's work being done on upsteaming, but the changes are not trivial.
Some of the things I've heard discussed:
* All distros default to 4k pages and that's set at kernel compile time. Asahi (at least for now) is defaulting to 16k pages, which helps minimize page faults and TLB thrashing. For awhile the GPU acceleration required 16k pages. OSX uses 16k pages I believe.
* The apple GPU acceleration is in Rust, and while the Linux kernel is adding rust support, it's not fully functional for something as complicated as a 3D accelerated GPU. The required patches are shrinking, but not zero.
* Various hardware differences, device trees, loading firmware blobs, speaker protection to prevent overdriving, are being upstreamed, etc.
So the goal is any Linux distro running on Apple, but for the short term you are best off using Asahi Linux.
(these are just their most recent reactions to similar events. I didn't bother searching through the last 3 months of their Mastodon posts to find the one where they talk specifically about kernel-upstreamed stuff)
Oh and tangentially, Hector Martin got tired of HN and blocked it:
Some of the things I've heard discussed:
* All distros default to 4k pages and that's set at kernel compile time. Asahi (at least for now) is defaulting to 16k pages, which helps minimize page faults and TLB thrashing. For awhile the GPU acceleration required 16k pages. OSX uses 16k pages I believe.
* The apple GPU acceleration is in Rust, and while the Linux kernel is adding rust support, it's not fully functional for something as complicated as a 3D accelerated GPU. The required patches are shrinking, but not zero.
* Various hardware differences, device trees, loading firmware blobs, speaker protection to prevent overdriving, are being upstreamed, etc.
So the goal is any Linux distro running on Apple, but for the short term you are best off using Asahi Linux.