IBex AST2700
AST2700 integrates an IBex RISC-V 32-bits CPU as the boot MCU to execute the first stage bootlaoder, namely SPL.
Build
Prepare the toolchains and make sure the $PATH to toolchains is correct.
Use make ibex-ast2700_defconfig in u-boot root to build the image
Running U-Boot SPL
The U-Boot SPL will boot in M mode and load the FIT image which includes the 2nd stage bootloaders executed by the main processor Cortex-A35.
Burn U-Boot to SPI Flash
Use SPI flash programmer (e.g. SF100) to program the u-book-spl.bin with the offset 0x80 bytes to the SPI flash beginning.