[CMake] [SOLVED] RE: Crosscompilation woes

Tue Oct 11 11:16:51 EDT 2016

Thanks Chuck,

It now actually is a one step automatic build, where the CMake initial pass creates the host tools, sets up CMake cache vars for them, then when the CMake step is finished I can just run make and it all works out fine.

The key issue was unsetting CC and CXX env vars during the creation of the cmake files for the host tools, so that the native build system was being used.

All the best
/Robert

From: Chuck Atkins [mailto:chuck.atkins at kitware.com]
Sent: den 11 oktober 2016 17:10
To: Robert Bielik <Robert.Bielik at dirac.com>
Cc: Cmake at cmake.org
Subject: Re: [CMake] [SOLVED] RE: Crosscompilation woes

In VTK and ParaView we use a manual two-step build.  The first pass configures a host build of the cross-compile utilities and the second pass configures a target build with a toolchain file, which requires you tell it where the host tools are.  So the build process looks like this:
mkdir build_host
cd build_host
cmake -DBUILD_CROSSTOOLS=ON /path/to/source
make
cd ..
mkdir build_target
cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/tolchain.cmake -DFOO_CROSSTOOLS_DIR=/path/to/build_host
make
You should be able to adapt this to a superbuild scenario with two external projects and it seems like that's exactly what you've done.  Just confirming that yes that's a sane approach and that's how we do it to.

----------
Chuck Atkins
Staff R&D Engineer, Scientific Computing
Kitware, Inc.

On Mon, Oct 10, 2016 at 9:56 AM, Robert Bielik <Robert.Bielik at dirac.com<mailto:Robert.Bielik at dirac.com>> wrote:
For reference: I went with Brads suggestion: https://gitlab.kitware.com/cmake/cmake/issues/16356

which seems to be working fine.

Regards
/R

From: CMake [mailto:cmake-bounces at cmake.org<mailto:cmake-bounces at cmake.org>] On Behalf Of Robert Bielik
Sent: den 10 oktober 2016 14:00
To: Craig Scott <craig.scott at crascit.com<mailto:craig.scott at crascit.com>>

Cc: Cmake at cmake.org<mailto:Cmake at cmake.org>
Subject: Re: [CMake] Crosscompilation woes

I am using a toolchain file! The CC and CXX environment variables are set by CMake (I assume, because I haven’t touched them).

I’ll disect the link to see what I’ve missed.

Regards
/R

From: Craig Scott [mailto:craig.scott at crascit.com]
Sent: den 10 oktober 2016 13:56
To: Robert Bielik <Robert.Bielik at dirac.com<mailto:Robert.Bielik at dirac.com>>
Cc: Cmake at cmake.org<mailto:Cmake at cmake.org>
Subject: Re: [CMake] Crosscompilation woes

Don't use environment variables to set the ARM compilers in your situation, use a toolchain file to specify them instead. Your CMake experience will generally be smoother if you specify cross-compile details via toolchain files. If you are following the method in the stackoverflow link I mentioned last time, the host part of the build will then pick up the host compilers and the ARM part of the build will use the compilers from the toolchain file.

On Mon, Oct 10, 2016 at 10:50 PM, Robert Bielik <Robert.Bielik at dirac.com<mailto:Robert.Bielik at dirac.com>> wrote:
I’m trying to do this, but since I setup a cross compiling env. by setting C&C++ compiler, these settings get used when I run execute_process to setup the host build !! Thus I get the ARM version of the build tools anyway! :(

It seems that when execute_process is executed, the CC and CXX environment variables are set, which makes cmake use those when generating the makefiles.

Ideas are most welcome!

Regards
/R

From: Craig Scott [mailto:craig.scott at crascit.com<mailto:craig.scott at crascit.com>]
Sent: den 10 oktober 2016 10:47
To: Robert Bielik <Robert.Bielik at dirac.com<mailto:Robert.Bielik at dirac.com>>
Cc: Cmake at cmake.org<mailto:Cmake at cmake.org>
Subject: Re: [CMake] Crosscompilation woes

Here's one possible solution (not perfect, but has been working in production for us for a while now for a similar scenario to what you describe):

http://stackoverflow.com/q/36084785/1938798

An alternative is a superbuild arrangement which would require a top level project to drive two sub-builds brought in via ExternalProject<https://cmake.org/cmake/help/latest/module/ExternalProject.html>, one for the host and the other for arm. This is both better and worse, depending on your point of view, so you may need to do some research/experimenting to see which is a better fit for your situation.

On Mon, Oct 10, 2016 at 7:29 PM, Robert Bielik <Robert.Bielik at dirac.com<mailto:Robert.Bielik at dirac.com>> wrote:
Hi all,

I am crosscompiling a project for arm (on linux i686), and use codegeneration tools within the project (together with add_custom_command). Of course, this will fail, since the tools are compiled for arm also and thus won't execute on my host system. So the tools need to be compiled for i686 whilst the rest for arm. I'm sure this can be handled by CMake although haven't done it before so would appreciate pointers :)

Regards
/Robert

--

Powered by www.kitware.com<http://www.kitware.com>

Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ

Kitware offers various services to support the CMake community. For more information on each offering, please visit:

CMake Support: http://cmake.org/cmake/help/support.html
CMake Consulting: http://cmake.org/cmake/help/consulting.html
CMake Training Courses: http://cmake.org/cmake/help/training.html

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Follow this link to subscribe/unsubscribe:
http://public.kitware.com/mailman/listinfo/cmake

--
Craig Scott
Melbourne, Australia
https://crascit.com

--
Craig Scott
Melbourne, Australia
https://crascit.com

--

Powered by www.kitware.com<http://www.kitware.com>

Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ

Kitware offers various services to support the CMake community. For more information on each offering, please visit:

CMake Support: http://cmake.org/cmake/help/support.html
CMake Consulting: http://cmake.org/cmake/help/consulting.html
CMake Training Courses: http://cmake.org/cmake/help/training.html

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Follow this link to subscribe/unsubscribe:
http://public.kitware.com/mailman/listinfo/cmake

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/cmake/attachments/20161011/be8be05f/attachment-0001.html>