Custom CMake Toolchains

To use a custom toolchain defined in an external CMake file, export the following environment variables:

# Linux and macOS
export ZEPHYR_TOOLCHAIN_VARIANT=<toolchain name>
export TOOLCHAIN_ROOT=<path to toolchain>

# Windows
set ZEPHYR_TOOLCHAIN_VARIANT=<toolchain name>
set TOOLCHAIN_ROOT=<path to toolchain>

You can also set them as CMake variables when generating a build system for a Zephyr application, like so:

cmake -DZEPHYR_TOOLCHAIN_VARIANT=... -DTOOLCHAIN_ROOT=...

Zephyr will then include the toolchain cmake file located in: <path to toolchain>/cmake/toolchain/<toolchain name>.cmake.