How to detect target architecture using CMake?

Question

I\'ve done a lot of research and been unable to find an answer to this... how can I reliably find the target architecture I\'m compiling for, using CMake? Basically, the equ

Answer 1

I case your build process involved more than 1 target, I this it is better to let CMake know what ARCH/toolchain it is building against. You can follow the instructions for CMake cross-compilation, that encourages you to create a toolchain CMake file, which lets you pick the toolchain/compiler being used.

I've created one for building my C++ Linux application for the arm processor, and named it toolchain-arm.cmake.

It includes set(CMAKE_SYSTEM_PROCESSOR arm).

I then executed CMake like so:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE={my toolchain cmake path}/toolchain-arm.cmake {my source path}

within my project's CMakeList.txt I can refer to CMAKE_SYSTEM_PROCESSOR any way I wish.

When building for X86, I don't include the reference to -DCMAKE_TOOLCHAIN_FILE, leaving CMAKE_SYSTEM_PROCESSOR undefined, or at least not defined as arm.

Here's my toolchain-arm.cmake

SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_SYSTEM_PROCESSOR arm)

# specify the cross compiler
SET(ENV{TOOLCHAIN_ROOT} /home/user/toolchain/tools-master/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin )
SET(CMAKE_C_COMPILER   $ENV{TOOLCHAIN_ROOT}/arm-linux-gnueabihf-gcc)
SET(CMAKE_CXX_COMPILER $ENV{TOOLCHAIN_ROOT}/arm-linux-gnueabihf-gcc)

# search for programs in the build host directories
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
# for libraries and headers in the target directories
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)