Whoa! Slow down cowboy! Go review, then come back.
- Figure out how to move bootblock and CBFS header to make room for BOOT0 header.
- Figure out the whole MMC/blockdev/NAND shenanigance
There are not many ARM payloads that can do anything useful. One possibly useful payload is sunxi/u***t. Here, we are interested in the payload part, not hwinit part (SPL). Once you have succesfully built sunxi/u***t, add the resulting "u-boot" file as the coreboot payload. This is an elf file that coreboot can easily load.
NOTE: The corect file to use as the payload is "u-boot", not u-boot.bin. The "u-boot" file is the non-SPL part of uboot in elf format.
Counter to the usual way of doing things, the bootable coreboot image resides in build/BOOT0. This image needs to be placed on the SD card at an offset of 8 KiB. This is a limitation on how the CPU loads the bootblock, and there's nothing we can do about it.
# dd if=build/BOOT0 of=/path/to/sdcard/blockdev bs=1024 seek=8
This is enough to get coreboot up and running.