U-Boot as a payload to OpenSBI

U-Boot is an open-source primary boot loader.
It can be used as first and/or second stage boot loader in an embedded
environment. In the context of OpenSBI, U-Boot can be specified as a payload to
the OpenSBI firmware, becoming the boot stage following the OpenSBI firmware
execution.

Building and Generating U-Boot images

Please refer to the U-Boot build documentation for detailed instructions on
how to build U-Boot image and boot high level operating systems from U-Boot
prompt.