# CMAKE_APPLE_SILICON_PROCESSOR

Added in version 3.19.2.

This is a CMake Environment Variable. Its initial value is taken from the calling process environment.

On Apple Silicon hosts running macOS, set this environment variable to tell CMake what architecture to use for `CMAKE_HOST_SYSTEM_PROCESSOR`. The value must be either `arm64` or `x86_64`.

The `CMAKE_APPLE_SILICON_PROCESSOR` normal variable, if set, overrides this environment variable.