Stable ABI. We have done ~Fedora 25 in late 2016 - https://fedoraproject.org/wiki/Architectures/RISC-V and you can even boot that in your browser - https://bellard.org/jslinux/

ABIs have changed after we did this. We get the first long-term stable ABI with 4.15 kernel and glibc 2.27 (hopefully). At that point Fedora, Debian, and others can reboot efforts.