Details
-
Bug
-
Resolution: Done
-
P2: Important
-
6.0, 6.2.0
-
Ubuntu 18.04.3 LTS
Yocto Warrior 32-bit b2qt ARMV7
Yocto sha1 b4a090f85268bed076451584cd48e27e17a6ae48
https://download.qt.io/development_releases/prebuilt/boot2qt/warrior/b2qt-x86_64-meta-toolchain-b2qt-embedded-sdk-qemuarmv7-60f80be.sh
GNU ld (GNU Binutils) 2.32.0.20190204
gcc (GCC) 8.3.0
-
Linux/Yocto,
QNX
-
606124c5cceba0dd4a406a9278588b58bb9f9800
Description
Trying to build a non-prefix qtdeclarative build targeting yocto qemu armv7 fails when linking the qtdeclarative cross-compiled apps.
Sample linking failure
$ ninja -v qmleasing [1/1] : && /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++ -march=armv7-a -mthumb -mfpu=neon -mfloat-abi=hard --sysroot=/opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi --sysroot=/opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi -O2 -pipe -g -feliminate-unused-debug-types -g -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed tools/qmleasing/CMakeFiles/qmleasing.dir/qmleasing_autogen/mocs_compilation.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/main.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/mainwindow.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/segmentproperties.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/splineeditor.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/Button_qml.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/preview_qml.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/qmlcache_loader.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qrc_resources_qmlcache.cpp.o -o /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/bin/qmleasing -Wl,-rpath,/home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Quick.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6QmlModels.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Qml.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Network.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6OpenGL.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Widgets.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Core.so.6.0.0 -pthread /opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi/usr/lib/libGLESv2.so /opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi/usr/lib/libxkbcommon.so && : FAILED: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/bin/qmleasing : && /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++ -march=armv7-a -mthumb -mfpu=neon -mfloat-abi=hard --sysroot=/opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi --sysroot=/opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi -O2 -pipe -g -feliminate-unused-debug-types -g -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed tools/qmleasing/CMakeFiles/qmleasing.dir/qmleasing_autogen/mocs_compilation.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/main.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/mainwindow.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/segmentproperties.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/splineeditor.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/Button_qml.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/preview_qml.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qmlcache/resources/qmlcache_loader.cpp.o tools/qmleasing/CMakeFiles/qmleasing.dir/.rcc/qrc_resources_qmlcache.cpp.o -o /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/bin/qmleasing -Wl,-rpath,/home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Quick.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6QmlModels.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Qml.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Network.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6OpenGL.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Widgets.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0 /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Core.so.6.0.0 -pthread /opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi/usr/lib/libGLESv2.so /opt/b2qt/2.7.2/sysroots/armv7at2hf-neon-poky-linux-gnueabi/usr/lib/libxkbcommon.so && : /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: warning: libQt6DBus.so.6, needed by /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0, not found (try using -rpath or -rpath-link) /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusMessage::type() const@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusUnixFileDescriptor::QDBusUnixFileDescriptor(int)@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusPendingCall::error() const@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusAbstractInterface::~QDBusAbstractInterface()@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusError::type() const@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusArgument::operator>>(int&) const@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusArgument::QDBusArgument()@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `typeinfo for QDBusAbstractAdaptor@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusArgument::endStructure()@Qt_6' /opt/b2qt/2.7.2/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/8.3.0/ld: /home/alex/Dev/qt/qt5_cmake/qtbase_built_developer_armv7/lib/libQt6Gui.so.6.0.0: undefined reference to `QDBusMessage::arguments() const@Qt_6' ......
The problem is that the link line is missing an -rpath-link flag pointing to the qtbase ./lib dir, and because libQt6DBus.so is not explicitly mentioned on the link line, dbus symbols referenced from libQt6Gui.so are not found.
As an aside, the equivalent qmake configurations do pass -rpath-link.
As per
https://stackoverflow.com/questions/49138195/whats-the-difference-between-rpath-link-and-l
and the -rpath and -rpath-link documentation at https://sourceware.org/binutils/docs/ld/Options.html#Options
one would think that passing just -rpath should be enough (it kind of implies -rpath-link), and usually it is enough, but not when combined with the --sysroot flag.
As per https://cmake.org/pipermail/cmake-developers/2018-July/030746.html
and the actual source code
https://github.com/bminor/binutils-gdb/blob/5987401fcbc9933808fa0d84d1b01c93356c39a1/ld/ldelf.c#L1236
If a -sysroot is provided in conjunction with -rpath, the sysroot is prepended to all absolute path values specified via -rpath. This will cause the linker not to find the needed libraries. The sysroot is not prepended for values provided via -rpath-link.
Now for some reason CMake doesn't add -rpath-link flags as described in the mailing list post above, and yet the CI CMake qemu builds don't exhibit the problem.
The reason is that CI builds are doing prefix builds. In a prefix build, $ORIGIN is embedded as an rpath directly into the shared libraries via qt_apply_rpaths().
The linker has a separate code path where it tries to use the embedded rpaths here
https://github.com/bminor/binutils-gdb/blob/5987401fcbc9933808fa0d84d1b01c93356c39a1/ld/ldelf.c#L1264
Because $ORIGIN is not an absolute path, the sysroot is not prepended, and the linker successfully finds the libraries it needs.
So prefix builds work by mere coincidence.
Ideally, CMake should be fixed to add -rpath-link like qmake does, but i don't think that's fixed yet up to CMake 3.18 (present stable version).
A possible workaround for non-prefix builds is to change qt_apply_rpaths() to embed an $ORIGIN rpath even in non-prefix builds (I've confirmed this works).
By the way, this is probably also the reason why the qtbase cmake build tests were disabled for qemu, as mentioned in the commit message at
https://codereview.qt-project.org/c/qt/qtbase/+/307774
Here's the list of open -rpath-link issues on CMake's gitlab, but none of them seem relevant to our case
Here's a simplified project that reproduces the problem
https://github.com/neverpanic/cmake-rpath-link-example
Attachments
Issue Links
- is duplicated by
-
-
- Closed
-
- relates to
-
-
- Closed
-
-
-
- Closed
-
-
-
- Closed
-
-
-
- Closed
-
-
-
- Closed
-
-
QTBUG-99298 File issue to CMake bug tracker regarding transitive dependencies not being considered for rpath-link generation
-
- Reported
-
-
-
- Closed
-
- resulted in
-
-
- Closed
-
-
-
- Closed
-
-
-
- Closed
-