Rtos port on RISC-V

[ninode]

Hello,

I'm doing an rtos port on RISC-V and currently working on the fpga-zynq/rocket-chip directory of Berkeley's.

Could you please provide instruction to how you used Vivado tools to generate another boot.bin which contains another os than linux with the rocket chip ? Did you use this directory at all ? What kind of files are necessary to have both the rocket cores and another os into the same boot.bin ?

Thank you very much

Regards

[sergeykhbr]

Hi,

I think you've a bit misunderstood the difference of projects for ZYNQ (ARM+FPGA) and pure FPGA projects. I do not use ZYNQ in my project and I do not use directory you've pointed to. So, I cannot help you to generate boot.bin file because I don't need to generate image for ARM at all.

Regards, Sergey

[ninode]

Hello,

Actually, is it possible to use your SoC FPGA Rocket sources and push them to a Zedboard to have Rocket cores on the FPGA fabric and not touch the ARM ?

Also, instead of Zephyr, is it possible to use my own sources for a ported RTOS in order to have: RTOS on ARM cores and Rocket cores on FPGA, without the boot.bin, but following your steps ?

Thank you

[sergeykhbr]

I am not experienced with ZYNQ but I see one common difference in FPGA startup process:

• In a case of pure FPGA project (not ZYNQ), FPGA has access to all HW interfaces and IOs including flash ROM. Software (ISE or Vivado) can directly load bit-image into fpga via JTAG interface either.

• In a case of ZYNQ almost all FPGA's IOs connected to MIO interface between ARM and FPGA. And accordingly with this thread https://forums.xilinx.com/t5/Zynq-All-Programmable-SoC/Zynq-newbee-questions-Configure-FPGA-fabric-without-hard-ARM/td-p/568025 "The Zynq PL cannot be configured independent of the PS; the PL can't power on and read a configuration bitstream from a memory chip. The PS must run and program the fabric through a configuration access port...." In my opinion, it means that you has to build and run at least BootLoader on ARM to properly configure MIO interface and load FPGA image into FPGA.

So, I suppose the answers on questions will be (my opinion only):

1. It is possible to use Rocket sources on FPGA but ARM is always touched.
2. You cannot load FPGA without boot.bin