[CMake] pkg-config and Cross_compiling

[Wookey]

On 2008-07-02 19:39 +0200, Hendrik Sattler wrote:
> Am Mittwoch, 2. Juli 2008 18:59:37 schrieb Wookey:
> > I tried to fix the FindPkgConfig.cmake file to automaticaly do this,
> > but found that it uses execute_process to call pkg-config and there
> > seems to be no way to set an environment variable with this call. Am I
> > missing something? Fixing this module to look in
> > CMAKE_FIND_ROOT_PATH when cross-compiling seems like the best fix to
> > me, but there may be a better way?
> 
> Yes, that should be fixed. It should work to use SET() to set an environment 
> variable and the child process from EXECUTE_PROCESS should get the copy of 
> that environment. BUT: you must use PKG_CONFIG_LIBDIR instead of 
> PKG_CONFIG_PATH!

Ah, so I do - well done. That will avoid native libs being found. 

I got the impression that SET() only set CMAKE variables, not
environment ones, but maybe they ammount to the same thing?
<fx: reads docs again> Ah, yes there is the ENV{} syntax. Brill. that
means I can now add 

IF (CMAKE_CROSSCOMPILING)                           
  SET(ENV{PKG_CONFIG_LIBDIR} ${CMAKE_FIND_ROOT_PATH}/lib/pkgconfig/)  

to the toolchain file and that works fine. 

Putting that in FindPkgConfig.cmake should do the trick.

> Additionally, I found that the include paths are another source of problems, 
> not fully covered by the cmake cross compiling, yet. You really have to -I 
> any path that is not known and specific to the cross compiler, using 
> INCLUDE_DIRECTORIES(). This is not done automatically for the changed 
> ROOT_PATH, yet. 

Yes. I found that too. I added:
IF (CMAKE_CROSSCOMPILING)
  INCLUDE_DIRECTORIES(BEFORE ${CMAKE_FIND_ROOT_PATH}/include)
  
to my toolchain file, but it would have been nice is cmake did it for
me.

Wookey
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Principal hats:  Balloonz - Toby Churchill - Aleph One - Debian
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