I have an Avnet/Architech Hachiko board without SDRAM. It uses RZ/A1H R7S72100 with 10 MB SRAM SoC in QFP package. I want to run mainline U-Boot and Linux on it.
Vendor documentation on the board: http://architechboards-hachiko-tiny.readthedocs.io/en/latest/ and http://downloads.architechboards.com/doc/Hachiko/download.html
BSP that came with it from the vendor used patches to U-Boot and Linux provided in: https://github.com/bradfa/meta-hachiko
It seems there's some amount of support in mainline Linux for RZ/A1 but I'm not sure how much. It's unclear to me how much support there is in mainline U-Boot. Either way, I want to run mainline on this board as I want to learn and if needed, contribute code upstream.