Getting access to the RISCV GNU Toolchain (riscv64-unknown-elf)

[sternenseemann]

@romatthe

Which gives me access to the riscv-unkown-linux-gnu-* tools. However, when I set riscv-toolchain.crossSystem.config to risc64-unknown-elf , I get the error Unknown kernel: unknown , which isn’t very helpful to say the least.

This is because config apparently tries to be smart and understand both system doubles and autotools triples and a “kernel” part is always expected. Because elf is not a kernel part in nixpkgs, it expects the kernel part in the unknown place. nixpkgs does understand none as kernel, so maybe the following works for you (if I guessed correctly what you want):

let
  crossPkgs = 
    import <nixpkgs> {
      # uses GCC and newlib
      crossSystem = { system = "riscv64-none-elf"; }; 
    };
in

# use crossPkgs' mkShell to use the correct stdenv!
crossPkgs.mkShell {}