where can you place the modified DTB so that the uboot code sees and uses it?
This I don’t know, but if I were to try it out, I’d start by attempting to mount /boot and do a …
find /boot -iname “*.dtb”
… if /boot will mount and I get a result from the above, I’d mount /boot as read/write, then move the old .dtb file aside and move the new .dtb file in and rename it to match the original .dtb file’s name.
-But as uboot may be located in SPI-flash, I’m not sure how to go about this; it might be stored like a file system as well.
You’ll probably have to look in /dev, perhaps lsblk is able to list it.
I’m pretty sure someone else in here knows much more about this than I do. 😉