“The CMAKE_SYSTEM_VERSION should be set on the command line on the first configuration of a new build tree (cmake-gui has options to add it as a cache entry before configuring). It is part of defining the target platform, and should remain constant once a build tree is first configured. Alternatively, it can be set in a toolchain file during cross-compiling, but I don’t thi
nk that is relevant to your use case.”
Thanks to Brad King
posted here :