I want to cross compile the Qt libraries (and eventually my application) for a Windows x86_64 target using a Linux x86_64 host machine. I feel like I am close, but I may have a fundamental misunderstanding of some parts of this process.
I began by installing all the mingw packages on my Fedora machine and then modifying the
win32-g++ qmake.conf file to fit my environment. However, I seem to be getting stuck with some seemingly obvious configure options for Qt:
-xplatform. Qt documentation says that
-platform should be the host machine architecture (where you are compiling) and
-xplatform should be the target platform for which you wish to deploy. In my case, I set
-platform linux-g++-64 and
-xplatform linux-win32-g++ where linux-win32-g++ is my modified win32-g++ configuration.
My problem is that, after executing configure with these options, I see that it invokes my system's compiler instead of the cross compiler (x86_64-w64-mingw32-gcc). If I omit the
-xplatform option and set
-platform to my target spec (linux-win32-g++), it invokes the cross compiler but then errors when it finds some Unix related functions aren't defined.
Here is some output from my latest attempt: http://pastebin.com/QCpKSNev.
When cross-compiling something like Qt for Windows from a Linux host, should the native compiler ever be invoked? That is, during a cross compilation process, shouldn't we use only the cross compiler? I don't see why Qt's configure script tries to invoke my system's native compiler when I specify the
If I'm using a mingw cross-compiler, when will I have to deal with a specs file? Spec files for GCC are still sort of a mystery to me, so I am wondering if some background here will help me.
In general, beyond specifying a cross compiler in my qmake.conf, what else might I need to consider?
Just use M cross environment (MXE). It takes the pain out of the whole process:
$ git clone https://github.com/mxe/mxe.git
Install build dependencies
Build Qt for Windows, its dependencies, and the cross-build tools; this will take about an hour on a fast machine with decent internet access; the download is about 500MB:
$ cd mxe && make qt
Go to the directory of your app and add the cross-build tools to the PATH environment variable:
$ export PATH=<mxe root>/usr/bin:$PATH
Run the Qt Makefile generator tool then build:
$ <mxe root>/usr/i686-pc-mingw32/qt/bin/qmake && make
You should find the binary in the ./release directory:
$ wine release/foo.exe
Use the master branch of the MXE repository; it appears to get a lot more love from the development team.
The output is a 32-bit static binary, which will work well on 64-bit Windows.