How to create a 32bit shared library on a 64bit system?

Wed Jun 13 14:21:04 BST 2007

Hi,

I think that this issue isn't a kdevelop or cmake question. You are trying to 
make a cross compiler because you want to make a binary from one system (64 
bits) to another (32 bits).

I think that the most easy way to do this is to create a chroot of 32 bits and 
recompile it.

Regards,

Leo

A Dimecres 13 Juny 2007 14:38, Armin Lambacher va escriure:
> Hello,
>
> I have the problem that I must build a 32bit shared library, that will be
> used with a 3rd party software (which is 32bit).
>
> The system that I have is a Suse 10.2 linux, 64bit version on a Intel Core
> 2 CPU.
>
> Now I tried the shared object template in kdevelopp (version 3.4.1) under
> C++ --> CMakes based projects --> Shared Library.
>
> This compiles and runs well if I don't make any changes.
>
>
> Then I tried to find out at what point I could change the compiler/linker
> flags to produce 32bit code. Googling for the solution gave me either so
> many links that I could not find the correct one there or none at all.
> Maybe I tried the wrong keywords.
>
> I'm am complete newbie to CMake, I must admit.
>
> Then I found the file  CMakeLists.txt, where there seems to be an
> appropriate place to put options. The file reads:
>
> -------------------------
> #this is just a basic CMakeLists.txt, for more information see the cmake
> manpage
>
> #add definitions, compiler switches, etc.
> ADD_DEFINITIONS(-Wall -O2)
>
> #build a shared library
> ADD_LIBRARY(so_test SHARED so_test.cpp)
>
> #for testing the shared library you probably need some test app too
> ADD_EXECUTABLE(so_testtest so_testtest.cpp)
>
> #need to link to some other libraries ? just add them here
> TARGET_LINK_LIBRARIES(so_testtest so_test)
>
> #add an install target here
> #INSTALL_FILES(...)
> #INSTALL_PROGRAMS(...)
> #INSTALL_TARGET(...)
> -------------------------
>
> I tried to add "-m32" to the ADD_DEFINITIONS line, so that the line reads
>
> ADD_DEFINITIONS(-m32 -Wall -O2)
>
> According to the gcc documentation this should produce 32bit code. BTW, I'm
> using the gcc 4.1.2 that comes with the suse distribution.
>
> The I tried to build the project again. The output is:
>
> --------------------------------------------------
>
> cd '/home/lambache/cprog/so_test' && gmake -k -j1
> /usr/bin/cmake -H/home/lambache/cprog/so_test
> -B/home/lambache/cprog/so_test --check-build-system
> CMakeFiles/Makefile.cmake 0
> /usr/bin/cmake -E cmake_progress_start
> /home/lambache/cprog/so_test/CMakeFiles 2
> gmake -f CMakeFiles/Makefile2 all
> gmake -f src/CMakeFiles/so_test.dir/build.make
> src/CMakeFiles/so_test.dir/depend
> Scanning dependencies of target so_test
> cd /home/lambache/cprog/so_test && /usr/bin/cmake -E
> cmake_depends "KDevelop3" /home/lambache/cprog/so_test
> /home/lambache/cprog/so_test/src /home/lambache/cprog/so_test
> /home/lambache/cprog/so_test/src
> /home/lambache/cprog/so_test/src/CMakeFiles/so_test.dir/DependInfo.cmake
> gmake -f src/CMakeFiles/so_test.dir/build.make
> src/CMakeFiles/so_test.dir/build
> /usr/bin/cmake -E
> cmake_progress_report /home/lambache/cprog/so_test/CMakeFiles 1
> [ 50%] Building CXX object src/CMakeFiles/so_test.dir/so_test.o
> /usr/bin/c++ -Dso_test_EXPORTS -fPIC -m32 -Wall -O2 -o
> src/CMakeFiles/so_test.dir/so_test.o -c
> /home/lambache/cprog/so_test/src/so_test.cpp Linking CXX shared library
> libso_test.so
> cd /home/lambache/cprog/so_test/src && /usr/bin/cmake -P
> CMakeFiles/so_test.dir/cmake_clean_target.cmake
> cd /home/lambache/cprog/so_test/src && /usr/bin/cmake -E cmake_link_script
> CMakeFiles/so_test.dir/link.txt --verbose=1
> /usr/bin/c++ -fPIC -shared -Wl,-soname,libso_test.so -o
> libso_test.so "CMakeFiles/so_test.dir/so_test.o"
> /usr/lib64/gcc/x86_64-suse-linux/4.1.2/../../../../x86_64-suse-linux/bin/ld
>: warning: i386 architecture of input file
> `CMakeFiles/so_test.dir/so_test.o' is incompatible with i386:x86-64 output
> /usr/bin/cmake -E
> cmake_progress_report /home/lambache/cprog/so_test/CMakeFiles 1
> [ 50%] Built target so_test
> gmake -f src/CMakeFiles/so_testtest.dir/build.make
> src/CMakeFiles/so_testtest.dir/depend
> gmake[2]: Für das Ziel »src/CMakeFiles/so_testtest.dir/depend« ist nichts
> zu tun.
> gmake -f src/CMakeFiles/so_testtest.dir/build.make
> src/CMakeFiles/so_testtest.dir/build
> Linking CXX executable so_testtest
> cd /home/lambache/cprog/so_test/src && /usr/bin/cmake -P
> CMakeFiles/so_testtest.dir/cmake_clean_target.cmake
> cd /home/lambache/cprog/so_test/src
> && /usr/bin/c++ -fPIC "CMakeFiles/so_testtest.dir/so_testtest.o" -o
> so_testtest -rdynamic -L/home/lambache/cprog/so_test/src -lso_test
> -Wl,-rpath,/home/lambache/cprog/so_test/src
> /usr/lib64/gcc/x86_64-suse-linux/4.1.2/../../../../x86_64-suse-linux/bin/ld
>: warning: i386 architecture of input file
> `CMakeFiles/so_testtest.dir/so_testtest.o' is incompatible with i386:x86-64
> output
> /usr/bin/cmake -E
> cmake_progress_report /home/lambache/cprog/so_test/CMakeFiles 2
> [100%] Built target so_testtest
> /usr/bin/cmake -E cmake_progress_start
> /home/lambache/cprog/so_test/CMakeFiles 0
> *** Erfolg ***
> ---------------------------------------------------------------------------
>--
>
> Interestingly the last line seems to indicate a successful build of the
> project, however, there are some issues with linking, see the lines
>
> /usr/lib64/gcc/x86_64-suse-linux/4.1.2/../../../../x86_64-suse-linux/bin/ld
>: warning: i386 architecture of input file
> `CMakeFiles/so_test.dir/so_test.o' is incompatible with i386:x86-64 output
>
> /usr/lib64/gcc/x86_64-suse-linux/4.1.2/../../../../x86_64-suse-linux/bin/ld
>: warning: i386 architecture of input file
> `CMakeFiles/so_testtest.dir/so_testtest.o' is incompatible with i386:x86-64
> output
>
> The program crashes upon starting it with SIGSEGV.
>
> Can somebody please put me into the right directon on how to solve this
> problem?
>
> Again, I'm a newbie to CMake, so at the moment I don't really know whether
> there is an option in kdevelop where I can solve this or whether I have to
> edit the CMake files.
>
>
> Best regards
>
> Armin Lambacher
>
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