03-04-2021, 10:25 AM
The SPI flash is blank from the factory, there is no "stock" bootloader installed. The boot ROM looks for a bootloader in SPI first, but if it's blank, it goes on to look on eMMC and SD card. So it's totally fine to erase SPI if you want to go back to booting everything off eMMC or SD card. I wrote some further details about the boot process here: https://github.com/sigmaris/u-boot/wiki/...t-sequence