This directory is used as dependencies installer.
If you does not have clone recursively this repository you must run mktoolchain shell script before build.
Currently handle only the ARM toolchain.
Using make rule: make toolchain.
Using mktoolchain directly: ./mktoolchain/mktoolchain.
Toolchain pre-configured cloned from github.
Curently assume that your host machine is x86/x64.
Clone from here and configure as explained.
By the way, archlinux have a package for the riscv gnu toolchain, lucky we are.