coreboot works on emulation/qemu-riscv, and the communities have somer (small) overlap. We (at coreboot) intend to support coreboot on real RISC-V hardware as soon as possible.

For the higher software stack, Linux on RISC-V already exists, and from there it's open source, a compiler plus some portability work to get a useful stack.

But that's only the CPU side. Good enough for embedded applications and maybe even servers - but at some point, data has to hit a display. http://www.miaowgpu.org/ or something like that could help there, but I know next to nothing about it.