These instructions are for Ubuntu
Download and install yosys/nextpnr/icestorm FPGA flow.
Recommend using the binary release by yosysHQ.
MAKE SURE IT IS REALLY UP TO DATE AND YOU DON'T HAVE SOME ANCIENT INSTALL IN YOUR PATH!
Download tarball from: https://github.com/YosysHQ/oss-cad-suite-build/releases