How to use Qt's 'windeployqt' in Linux / Fedora

Question

I'm currently trying to cross-compile my Qt apps on a Fedora 21 machine to Windows (32 bit, for now). Compilation works without problems, but deployment doesn't. Of cours, I could copy all the necessary files out of the directories, but I think that's a waste of time, so I want to use Qt's 'windeployqt' tool. But whenever I invoke it, e.g. in Qt Creator as a build step, it just puts out this message(my test application is called day_404 :D) :

Unable to find dependent libraries of /home/marius/Entwicklung/build-day_404-Windows_32bit-Release/release/day_404.exe :Not implemented.

Does any of you know how to fix this, and use windeployqt without using Windows?

Thanks in advance, Marius

Answer 1

The windeployqt tool doesn't seem to be usable on Fedora 23. It relies on accessing qmake, thus, it doesn't work in the mingw cross-compile environment, where you build with mingw32-qmake-qt5 (or mingw64-qmake-qt5). Even if this issue is patched - it wouldn't work with Qt5 projects using mingw64-cmake.

A relatively simple way to get a list of all DLLs that need to be copied for deployment is to run the application under wine and trace all dll loads.

For example like this:

$ WINEDEBUG=+loaddll wine ./myapp 2> dll.log

The dll paths can be extracted like that:

$ grep Loaded dll.log | grep -v 'system32\|:load_builtin_dll' \
  | awk -F'"' '{print $2}' \
  | sed -e 's@\\\\@/@g' -e 's/^[A-Z]://' \
  | sort > dll.lst

The file dll.lst looks like this for a typical Qt5 project cross-compiled with mingw64:

/path/to/cwd/myapp.exe
/path/to/cwd/project.dll
[..]
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/libpng16-16.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/libstdc++-6.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/libwinpthread-1.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/libxml2-2.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/Qt5Core.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/Qt5Gui.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/Qt5Widgets.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/bin/zlib1.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qgif.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qico.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qjpeg.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/platforms/qwindows.dll

You can then deploy those files like this:

$ mkdir -p "$deploy_dir"/{imageformats,platforms}
$ for i in imageformats platforms ; do
    grep "/plugins/$i" dll.lst | xargs -r cp -t "$deploy_dir"/$i
  done
$ grep -v '/plugins/' dll.lst | xargs -r cp -t "$deploy_dir"

Wine Config

For running a cross-compiled binary under wine, the mingw dll directory has to be added to the wine path, e.g. via:

sed 's/^\("PATH".*\)"$/\1;Z:\\\\usr\\\\x86_64-w64-mingw32\\\\sys-root\\\\mingw\\\\bin"/' \
  -i $HOME/.wine/system.reg

The file ~/.wine/system.reg is automatically created by wine if it is doesn't exist, yet.

PELDD

You can also use the tool peldd to get a list of all DLLs that a windows binary depends on. The tool runs on Linux, e.g.:

$ peldd myapp.exe -a  -p . \
   | sed -e 's@^\./@'"$PWD"'/@' -e 's@^\([^/]\)@'"$PWD"'/\1@' \
   | sort > dll2.lst

The tool transitively walks all dependencies as compiled into the binaries - but - DLLs that are conditionally loaded at runtime (think dlopen(), think Qt plugin) don't leave traces in the binary headers. In contrast to that: when running under wine, those DLLs are recorded, as well. For our example, this could be:

/usr/x86_64-w64-mingw32/sys-root/mingw/bin/libjpeg-62.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qgif.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qico.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/imageformats/qjpeg.dll
/usr/x86_64-w64-mingw32/sys-root/mingw/lib/qt5/plugins/platforms/qwindows.dll