How to pass a compile flag to cmake initial compiler test?

Question

I'm trying to use CMake for building a project which uses the MSPGCC cross-compiler for a MSP430 microcontroller. To successfully compile any simple program with it, we need to pass a compile flag indicating the target processor, or else it fails like this: ``` $ msp430-gcc -o test test.c In file included from test.c:1:0: /usr/local/lib/gcc/msp430/4.6.3/../../../../msp430/include/msp430.h:813:2: warning: #warning Unable to identify and include MCU header, use -mmcu=MCU [-Wcpp] /usr/local/lib/gcc/msp430/4.6.3/../../../../msp430/bin/ld: cannot open linker script file memory.x: No such file or directory collect2: ld returned 1 exit status ``` Hence, if I indicate the processor using the `-mmcu` switch it works fine. The problem is, although I'm already specifying this in my CMakeLists.txt file: ``` cmake_minimum_required (VERSION 2.6) project (test-project C) set (SOURCES test.c ) add_executable (test-project ${SOURCES}) set (CPU_FLAG "-mmcu=msp430f148") set (CMAKE_C_FLAGS ${CPU_FLAG}) s…

Accepted Answer

According to the Docs:

http://www.cmake.org/Wiki/CMake_Cross_Compiling#The_toolchain_file

you should use the CMakeForceCompiler thing

```
INCLUDE(CMakeForceCompiler)

# this one is important
SET(CMAKE_SYSTEM_NAME eCos)

# specify the cross compiler
CMAKE_FORCE_C_COMPILER(arm-elf-gcc GNU)
CMAKE_FORCE_CXX_COMPILER(arm-elf-g++ GNU)

# where is the target environment 
SET(CMAKE_FIND_ROOT_PATH  /home/alex/src/ecos/install )

# 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)
```

(copy&paste from the docs)

Using it fine here for my MSP430 too

How to pass a compile flag to cmake initial compiler test?

Solution

Problem