Fast kernel switching (chain loading etc) ?

[Chris Stratton]

Would it be possible to make a running kernel for an msm7201 phone
chain load and startup a test kernel? This would be fairly useless on
a phone that can fastboot, but a number of otherwise rooted phones
cant do that, making flash & crash the only current testing option. I
started looking through the reboot code, and it seems like
coordination with the baseband might be a major challenge.

Alternatively, what about adding a grub-like menu very early in the
kernel startup process, to permit choosing an alternate kernel? Is it
possible to display something before the system is irrevocably
started? Or even not display, but simply read keystate to see what is
held down?

I'm not asking someone to do these, more soliciting ideas of
difficulties I might run into trying to do them.

Chris

[Andrew de Quincey]

I suppose there's the linux "kexec" feature which claims to allow rebooting into a new kernel from an existing running kernel without needing a bootloader... I'm guessing the option's probably still in the android source, but disabled; no idea how will it'll work though. Combine that with an initramfs to do the menu maybe?