Running a chunk of Android userspace on top of the Darwin kernel feels like a better idea if you want Android on an iPhone. You'll have to shim Android APIs to iOS ones and implement an ELF loader/linker for apps that use native libraries, but that's it. Should also be portable across all (jailbreakable) devices.

I think you underestimate this quite a bit. Even running android things on desktop linux would be a feat since the android kernel has several significant android-specific additions such as binder IPC. And even the user-space android API surface is vast

> but that's it.

That’s a heck of a lot of APIs and daemons to shim. And then you’ve got to do all of that again if you want to run a newer version of iOS or Android.

Uh, ELF is the least of your concerns. I imagine there are native libraries making Linux syscalls.

I’ve been toying with ideas about similar approaches to get alternative/updated OS’s on iDevices — use stock kernel for all its device drivers for the proprietary HW, then put a VM on top running Linux or whatever. Sadly I don’t think I’ll have the time for such an ambitious project.