Running cross compiled unit tests with qemu (from yocto SDK)

drebelpai

To build a Qt app within WSL and run it (x86_64), I followed this link, and it went well, it launches, however I'm relying on X, not Wayland. Couldn't find anything explaining what dependencies I need for Wayland.

Then I moved towards cross-compiling. Created this question on StackOverflow

Basically I'm getting

qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
qt.qpa.plugin: Could not find the Qt platform plugin "eglfs" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

qemu: uncaught target signal 6 (Aborted) - core dumped
Aborted

Seems like, as my image/SDK won't have any X, I can't rely on xcb. What dependencies I need to add to my SDK to be able to simply run the Unit Tests under qemu?

SGaist

Hi and welcome to devnet,

You should start your application with the QT_DEBUG_PLUGINS environment variable set to 1 to see exactly why the plugins fail to load.

drebelpai

@SGaist
When I did that (passing to qemu), I still get the same thing, only the first line is new:

qemu-aarch64 -L $SDKTARGETSYSROOT -E QT_DEBUG_PLUGINS=1 install/Debug/bin/appExample
QFactoryLoader::QFactoryLoader() checking directory path "<path-to-app>/install/Debug/bin/platforms" ...
qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
qt.qpa.plugin: Could not find the Qt platform plugin "eglfs" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

qemu: uncaught target signal 6 (Aborted) - core dumped
Aborted

There's nothing installed in /bin/platforms, but also there's not installed on x86_64 as well, and still loads successfully.

SGaist

Might be a silly question but did you deploy Qt in your emulator ?

drebelpai

@SGaist AFAIK my question can be silly as well :)

My main question is, given an SDK generated by Yocto (that is used to compile a Qt application and its UTs) how can I run the Unit Tests using only qemu? (If this was a plain Cpp app, the line I used to run it would suffice)

So, yeah, the sysroot where the qemu lives, and it uses has Qt.

I tried now to copy the platforms/ folder under /opt/sdk-folder/0.0.1/sysroot/.../usr/lib/plugins/platforms/ to the path it says it was trying to reach(where I built it), and it works. Do you know which env variable Qt uses to look for it? Then I might be able to correctly set it up!

drebelpai

For anyone that came here trying to manually run Qemu unit tests (without booting up an image) for Qt:

qemu-aarch64 -L $SDKTARGETSYSROOT -E QT_QPA_PLATFORM_PLUGIN_PATH=$SDKTARGETSYSROOT/usr/lib/plugins <path-to/testing-bin>

Works!
Note: I don't know if that's the best solution, and it might be the case that there's a cleaner solution though :) Please improve it
Note2: This forces you to run it manually, not with ctest. Ideas on how to run it through ctest are welcome.

Take into account that this is also a simple solution. And only works for plain Qt, qmltests are still not working.