Ideally you would want to download a prebuilt toolchain from CI/Gitbub releases. But for those who want to modify the GNU toolchain you will need to build with openSDK yourself.
NOTE: openSDK will utilize a linux container if docker is installed on the
build system. If you do not want this, set USE_DOCKER to false
(see below how to). Refer to the container image located
here
for packages needed on the host.
make backend WPI_TARGET=roborio
make frontend WPI_TARGET=roborio WPI_HOST=windows_x86_64