That would be a fun thing to to do.
[1] https://rwmj.wordpress.com/2016/07/25/risc-v-on-an-fpga-pt-1...
[2] https://rwmj.wordpress.com/2016/07/26/risc-v-on-an-fpga-pt-4...
https://forums.sifive.com/t/building-linux-for-custom-u500/2...
I assumed SiFive was waiting for the privileged instructions to be finalized before making real chips. But people have been running Linux on their stuff on FPGA for a while now.
That would be a fun thing to to do.