Hi,
On Tue, May 14, 2013 at 02:38:17PM -0400, [email protected] wrote:
> Date: Tue, 14 May 2013 10:02:56 -0700
> From: Thomas Taranowski <[email protected]>
> I am running into a situation when cross compiling where I cannot get
> cmake to emit the write CFLAGS for my cross-compilation toolchain
> correctly.
>
> If I force the C compiler, via the CMakeForceCompiler mechanism, the
> CMAKE_C_FLAGS do not get passed to gcc during the build.
>
> Example make VERBOSE=true snapshot. Note there are no CFLAGS, only
> include paths:
> /usr/local/msp430/bin/msp430-gcc
> -I/home/tom/src/t3gtb.1/t3_i2c_mm/public
> -I/home/tom/src/t3gtb.1/t3_i2c_mm/src/msp430
> -I/home/tom/src/t3gtb.1/t3_i2c_mm/src -o
> CMakeFiles/t3_i2c_mm_support.dir/src/msp430/t3g_bsp.c.obj -c
> /home/tom/src/t3gtb.1/t3_i2c_mm/src/msp430/t3g_bsp.c
>
>
> Now, I can eliminate the need to force by passing in a -mmcu option
> (required for this processor to find the correct link map), which
> allows the TRY_COMPILE process to pass. So I set:
>
> set(CMAKE_C_COMPILER ${CROSS_COMPILE}gcc ${CMAKE_C_FLAGS})
>
> This works to allow cmake to do it's thing and figure out what it
> needs to about the toolchain. However, it seems as though the cflags
> is now fixed, because the include_directories directive has absolutely
> no effect. It's as if cmake thinks that if I pass in some additional
> flags to the CMAKE_C_COMPILER, that it can no longer append anything
> to cflags.
This is the usual CMAKE_<lang>_FOO per-LANGUAGE mechanism
(for pre-defined "languages" and custom-setup ones), e.g. CMAKE_C_COMPILER,
..._LINKER etc. variables.
I believe you're missing the usual (and usually existing!) *extension* parts
within these expressions, which would be the <...> parts (<FLAGS> etc.).
For details, see all the Platform setup modules within CMake's
pre-installed modules, i.e. INSTALL_PREFIX/share/cmake-VER/Modules/Platform/ ,
since *this* is where the game gets played, i.e. where all the magic
happens, thus that is the authoritative place to start investigating about
custom platform setup questions.
HTH,
Andreas Mohr
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