So I'm looking into how hard it will be to write our own little boot loader. Its similar to what linaro's spi to sd loader but we wanted to be able to switch to a back up sd card with a uboot on it. We are thinking about doing this because they want field update uboot safely.
With that said, I'm wondering what other peoples thoughts on this are. I already proposed the "don't do that" solution and just said it would be easier to make sure uboot isn't going to need an update. Also what is uboot responsible for configuring and initializing at boot that isn't on the SOC?