[cmake-developers] Building with Qt for the Raspberry Pi with CMake

[Stephen Kelly]

Stephen Kelly wrote:

> This doesn't affect only Qt, but could affect any CMake user trying to use
> a library which depends on zlib on the Raspberry Pi.

Actually I notice that I have a similar situation on my ubuntu system:

 /lib/x86_64-linux-gnu/libz.so.1
 /lib/x86_64-linux-gnu/libz.so.1.2.7
 /usr/lib/x86_64-linux-gnu/libz.so

When building bar, no -rpath-link is added at all, but it still works:

 Linking CXX executable bar
 /home/stephen/dev/prefix/qtbase/kde/bin/cmake -E cmake_link_script 
CMakeFiles/bar.dir/link.txt --verbose=1
 /usr/lib/icecc/bin/c++       CMakeFiles/bar.dir/hw.cpp.o  -o bar -rdynamic 
libfoo.so -Wl,-rpath,/home/stephen/dev/src/playground/cmake/build 
 make[2]: Leaving directory `/home/stephen/safe/dev/playground/cmake/build'
 /home/stephen/dev/prefix/qtbase/kde/bin/cmake -E cmake_progress_report 
/home/stephen/dev/src/playground/cmake/build/CMakeFiles  1
 [100%] Built target bar
 make[1]: Leaving directory `/home/stephen/safe/dev/playground/cmake/build'
 /home/stephen/dev/prefix/qtbase/kde/bin/cmake -E cmake_progress_start 
/home/stephen/dev/src/playground/cmake/build/CMakeFiles 0
 makeobj[0]: Leaving directory 
`/home/stephen/dev/src/playground/cmake/build'
 $ ldd libfoo.so 
         linux-vdso.so.1 =>  (0x00007fff9f7fe000)
         libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f6229f1f000)
         libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 
(0x00007f6229c1c000)
         libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 
(0x00007f6229a05000)
         libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f622963d000)
         libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f6229338000)
         /lib64/ld-linux-x86-64.so.2 (0x00007f622a362000)


I guess it works because libz.so and libz.so.1 are both in system paths? But 
then why doesn't the same work on the Raspberry Pi cross compile? The 
CMAKE_LIBRARY_ARCHITECTURE is already determined to be arm-linux-gnueabihf 
there.

Thanks,

Steve.