I'm experimenting with sharing my notes for dead-end projects like these. Maybe they'll be useful for someone who stumbles on them.
I have a Nexus 4, I'm hoping to run CM and Firefox OS. I want CM auto-updates to work, I'd rather not build my own kernel. It needs to be completely open source, with no dubious binaries to download.
- Ubuntu Phone has a tool for dual-booting with android. The details make it sound quite simple.
- The state of the art seems to be MultiRom which uses kexec.
Interrupts boot process with an OS picker, then uses kexec to run the other OS.