Dual versions for firmware update

[hh h <jupiter.hce@gmail.com>]

Hi,

I'd like to use remote firmware update via TCP/IP in armhf debian
embedded system. Correct me if I am wrong, it seems me that firmware
dual version files in /sys/block/mmcblk0boot0 and
/sys/block/mmcblk0boot1 are U-Boot images, not really for device
firmware. Both Linux image and device tree blob are in /boot
directory, there is no dual versions to be switched if one fails to
boot.

In my previous embedded system development which is not based on
Linux, I programmed firmware update in low level, directly copied the
firmware to Flash in two areas, one for stable old version, one for
new version, if the new version failed to boot, it switched to old
stable version. How can I do it in Linux boot?

Thank you.

jupiter