You need just enough flash ram for 2 firmwares and a proper bootloader, which knows which partition is active/verified. Simple as that. Biggest problem is getting enough flash.
writing the bootloader is trivial.
+1 to the above. And while a works-under-every-failure-case bootloader isn't quite that trivial, it's still absolutely nothing compared to telling the hardware guys that you want twice as much flash as the SoC they're using can manage.
rurban · · focus · HN ↗
pseudohadamard · · focus · HN ↗