I'm booting an AM1806 from an AIS-signed copy of U-Boot from NAND.
The bootloader's application report (SPRAB41D) mentions the following change in the latest ROM revision (d800k008):
In the Update to NAND boot modes so that if no valid boot image is found at in current block, next block is tried until image is found (within first 32 blocks).
I placed several AIS-signed U-Boot images in the range of blocks from 1-32. If I intentionally write some garbage over block 1, it jumps to the next U-Boot image on boot as expected. If I i erase block 1 from within U-Boot (nand erase 20000 20000), the processor hangs on the next boot and never tries to access the later images. But, I have empty 'padding' blocks between U-Boot images that are skipped as expected in the first case. The intent is the have as many redundant copies of U-Boot in those first 32 blocks as possible should a block go bad - but it seems, at least in this case, that it stops trying to find a valid boot image prematurely.
Two questions: 1) What stops RBL from trying the next block besides not finding a valid boot image, and 2) Which is considered a valid boot image - a valid AIS section, or a valid U-Boot image?
Thanks,
Eric