In A/B schemas, it is possible to have multiple rootfs.
Thus, it is necessary to let the B kernel preinitialize either the A
rootfs or the B rootfs failing to mount the A rootfs.
Ideally, we should also try to switch to the B rootfs if we cannot start
up the init on the A rootfs, but that's a FUTUREWORK.
Signed-off-by: Raito Bezarius <masterancpp@gmail.com>
By using the kernel "nolibc" header to avoid requiring a C library, we
can bring the initramfs size to around 4k
This does involve a tiny bit of inline mips assembly which I'm not
sure about. gcc seems unwilling to generate the code to load $gp at
function entry of main(), so we do it by hand - but I'd rather find
out why gcc doesn't.
