CMake Does Not Configure Correctly When Cross Compiling

jonenz

Host: Ubuntu 20.04.3 LTS
Target Sysroot: Raspberry Pi 4 Model B with Raspberry Pi OS Lite
Qt Creator Version: 4.11.0
Qt Version: 5.12.11 LTS
CMake Version: 3.16.3

I'm attempting to follow this guide to setup a development environment for the Raspberry Pi. When creating a project using New Project --> Application --> Qt Quick Application - Empty, the project compiles correctly and I am able to deploy it when building with qmake, but CMake gives me the following error.

Running /usr/bin/cmake /home/jon/TestEmpty '-GCodeBlocks - Unix Makefiles' in /home/jon/build-TestEmpty-RaspberryPi-Debug.
CMake Error at /home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/cmake/Qt5Core/Qt5CoreConfig.cmake:27 (message):
  The imported target "Qt5::Core" references the file

     "/home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/qt5/bin/qmake"

  but this file does not exist.  Possible reasons include:

  * The file was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and contained

     "/home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/cmake/Qt5Core/Qt5CoreConfigExtras.cmake"

  but not all the files it references.

Call Stack (most recent call first):
  /home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/cmake/Qt5Core/Qt5CoreConfigExtras.cmake:6 (_qt5_Core_check_file_exists)
  /home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/cmake/Qt5Core/Qt5CoreConfig.cmake:183 (include)
  /home/jon/raspberrypi/sysroot/usr/lib/arm-linux-gnueabihf/cmake/Qt5/Qt5Config.cmake:28 (find_package)
  CMakeLists.txt:30 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/jon/build-TestEmpty-RaspberryPi-Debug/CMakeFiles/CMakeOutput.log".
CMake process exited with exit code 1.

In the build settings for the Raspberry Pi kit I also see that Invalid codemodel file generated by CMake is displayed and no CMake variables are being set. This is not the case for the Desktop kit which builds and runs correctly. The kit is defined as follows:

The cross compiled Qt seems to be installed correctly, so I don't understand why the configuration is searching the sysroot for qmake instead of /home/jon/raspberrypi/qt5/bin/qmake.

Does anyone know what may be missing from this configuration?

JoeCFD

On Qt Version Tab, you select Qt(RaspbeeryPi) and then click Apply&OK. It will do it. The system one is ahead your Qt one in the system path.

/home/jon/raspbrrypi is a not a good location for installation since it is user dependent and therefore bad for deployment and team work. It is better to install it under /opt/raspbrrypi

jonenz

@JoeCFD

That seemed to do the trick. I'm not completely sure what it or why that mattered since the correct version is specified in the kit, but that issue seems to be resolved. It's correctly generating build settings with CMake variables defined.

Good point regarding the installation location. I will move it once things are working.

jonenz

@JoeCFD 's suggestion seems to clear up the configuration trouble.

Running /usr/bin/cmake /home/jon/TestEmpty '-GCodeBlocks - Unix Makefiles' -DCMAKE_BUILD_TYPE:STRING=Debug -DCMAKE_CXX_COMPILER:STRING=/usr/bin/arm-linux-gnueabihf-g++ '-DCMAKE_CXX_COMPILER_TARGET :STRING=arm-linux-gnueabihf' -DCMAKE_C_COMPILER:STRING=/usr/bin/arm-linux-gnueabihf-gcc -DCMAKE_C_COMPILER_TARGET:STRING=arm-linux-gnueabihf -DCMAKE_PREFIX_PATH:STRING=/home/jon/raspberrypi/qt5pi -DCMAKE_SYSROOT:STRING=/home/jon/raspberrypi/sysroot -DQT_QMAKE_EXECUTABLE:STRING=/home/jon/raspberrypi/qt5/bin/qmake in /home/jon/build-TestEmpty-RaspberryPi-Debug.
-- The CXX compiler identification is GNU 9.3.0
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabihf-g++
-- Check for working CXX compiler: /usr/bin/arm-linux-gnueabihf-g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
CMake Warning:
  Manually-specified variables were not used by the project:

    CMAKE_CXX_COMPILER_TARGET 
    CMAKE_C_COMPILER
    QT_QMAKE_EXECUTABLE


-- Build files have been written to: /home/jon/build-TestEmpty-RaspberryPi-Debug

However, now I'm now getting a linker error.

15:38:08: Running steps for project TestEmpty...
15:38:08: Starting: "/usr/bin/cmake" --build . --target all
Scanning dependencies of target TestEmpty_autogen
[ 16%] Automatic MOC and UIC for target TestEmpty
[ 16%] Built target TestEmpty_autogen
[ 33%] Automatic RCC for qml.qrc
Scanning dependencies of target TestEmpty
[ 50%] Building CXX object CMakeFiles/TestEmpty.dir/TestEmpty_autogen/mocs_compilation.cpp.o
[ 66%] Building CXX object CMakeFiles/TestEmpty.dir/main.cpp.o
[ 83%] Building CXX object CMakeFiles/TestEmpty.dir/TestEmpty_autogen/EWIEGA46WW/qrc_qml.cpp.o
[100%] Linking CXX executable TestEmpty
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/../../../../arm-linux-gnueabihf/bin/ld: /home/jon/raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0: undefined reference to `__nanosleep_nocancel@GLIBC_PRIVATE'
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/../../../../arm-linux-gnueabihf/bin/ld: /home/jon/raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0: undefined reference to `__libc_vfork@GLIBC_PRIVATE'
/usr/lib/gcc-cross/arm-linux-gnueabihf/9/../../../../arm-linux-gnueabihf/bin/ld: /home/jon/raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0: undefined reference to `__pause_nocancel@GLIBC_PRIVATE'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/TestEmpty.dir/build.make:126: TestEmpty] Error 1
make[1]: *** [CMakeFiles/Makefile2:77: CMakeFiles/TestEmpty.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
15:38:10: The process "/usr/bin/cmake" exited with code 2.
Error while building/deploying project TestEmpty (kit: RaspberryPi)
When executing step "CMake Build"
15:38:10: Elapsed time: 00:01.

Looking at the symbols with nm shows that they are undefined and makes me think there is a problem with the sysroot, but I don't understand why the build then works with qmake.

~$ nm -gD raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0 | grep nanosleep
00011adc T __nanosleep
         U __nanosleep_nocancel
00011adc W nanosleep

~$ nm -gD raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0 | grep libc_vfork
         U __libc_vfork

~$ nm -gD raspberrypi/sysroot/lib/arm-linux-gnueabihf/libpthread.so.0 | grep pause_nocancel
         U __pause_nocancel

Please share if you have any ideas.

JoeCFD

https://forums.gentoo.org/viewtopic-t-1118830-start-0.html