07-30-2020 09:33 AM
I have been searching the forum for a thread regarding boards that are based on Xilinx's FPGAs and are suitable for RISC-V implementations, but I couldn't find any besides this link.
So I thought I would open one and hopefully make it helpful for others in the future that might need to find a board suitable for RISC-V implementations.
I would like to implement a simple RISC-V SoC (probably a 64-bit version of a RISC-V) that would be able to run the Linux kernel on it. And by simple I mean that I am interested in a baseline design with a RISC-V core, a RAM, a debugger module, probably a ROM and ideally interfaces for a monitor and a keyboard.
Thus, I am searching for a suitable board that would be able to support such a design. The problem is that, since this is my very first attempt to implement a design of that size, I am not familiar with the minimum requirements that such a board should cover.
Currently the concerns I have are the following:
a) Size of the FPGA in terms of Slices/LUTs/Block RAMs.
b) Size of on board SDRAM. My guess is that it should be in the order of MBs, but what size would be the baseline? Also should it be DDR, DDR2, DDR3 or does this only apply on the desired frequency that the SDRAM should be able to achieve?
c) Is an ROM/EEPROM necessary for such a design? If yes, what size would be suitable?
d) I think UART RS232 and JTAG interfaces would be necessary, especially for debugging purposes. Also VGA and/or PS2 interfaces to be able to connect a monitor and a keyboard would be desired.
So this thread is open for people with suggestions or informations regarding the above concerns (or others that I haven't thought of yet), as well as for people that might already have experience with RISC-V implementations on Xilinx's FPGAs (or SoCs implementations in general). I am really looking forward for your valuable feedback.
P.S. I thought that this section of the forum would be the most suitable for such a post, if any of the Mods think that it should be moved to an other section, feel free to do so.
08-02-2020 06:14 PM
There are quite a few RISC-V suitable boards available to you. It somewhat depends upon 1) what peripherals you want, 2) how much of a CPU you want, 3) how big your cache will be, etc. The reality is that you can fit a RISC-V CPU inside every FPGA Xilinx makes--the difference being which CPU and how expensive each CPU is in terms of resources. Implementing the C library will likely require (SD)RAM resources of some type (> 64kB), again--depending upon how much of a CPU you want.