SiFive's HiFive1 rev B is an Arduino compatible dev kit featuring the RISC-V Freedom E310-G002 micro-controller.
You can get it at sifive.com.
You can use GNAT FSF riscv64-elf and GPRbuild releases from the Alire project, download here.
A public release of GNAT Studio is also available here.
To build the example, make sure sure you have all the tools in your PATH and run:
$ gprbuild -f -p -P hifive1_rev_B_example.gpr -XPLATFORM_BUILD=Debug
This will create a folder named obj in the same directory with the elf-formated
binary plus some auxiliary files. Inside this folder run the following command
to create the hex file:
$ riscv32-elf-objcopy -O ihex main main.hex
This new revision of the HiFive board allows the hex file to be uploaded
through the USB connection that should appear in your file manager. Just copy
the newly created main.hex into the board and press the restart button.
If you have issues with the board not appearing as a connected device, please go to the SiFive Forum and state your issue.