Qt5.6: DirectFB segmentation fault on Broadcom BCM7231B2

SGaist

Can you run a DirectFB hello world successfully ?

debian

I think this not should be problem because I change only qt version, now our application use Qt-4.7.3 and work fine.

SGaist

There's been quite some changes in the backend.

Can you test with a more recent version of Qt to see if it's still present ?

debian

You mean 5.6.2, 5.7.0 or 5.8.0?

SGaist

If possible each in that order so you can determine whether it was fixed and at which point.

debian

Unfortunately my current toolchain (gcc-4.5.3) not support c++11, Qt-5.7.0 and above not available.

SGaist

Then yes, try 5.6.2 or even the top of the 5.6 branch.

debian

I think this will be useless, I not see any changes in directfb support.

debian

I add some debug output in sources and found what problem in QBackingStore::QBackingStore.

QBackingStore::QBackingStore(QWindow *window)
    : d_ptr(new QBackingStorePrivate(window))
{
	qDebug() << __func__ << ":" << __LINE__ << "d_ptr" << d_ptr                  /// line 135
		<< "window" << window;
	qDebug() << __func__ << ":" << __LINE__                                                        /// line 137
		<< "platformIntegration" << QGuiApplicationPrivate::platformIntegration();
    d_ptr->platformBackingStore = QGuiApplicationPrivate::platformIntegration()->createPlatformBackingStore(window);
	qDebug() <<  __func__ << ":" << __LINE__;
}

And console output;

RasterWindow : 49 RasterWindow(0x7fc1d408)
QBackingStore : 135 d_ptr true window RasterWindow(0x7fc1d*** 60465:49:48.459 nexus_generic_driver: 408)
QBackingStforcing driver shutdownore : 137 platformIntegration 0x41bea8

I wait get output from *QDirectFbIntegration::createPlatformBackingStore.

SGaist

Then maybe a silly thing but did you try to check whether these instructions were still working with Qt 4 (e.g. 4.8.7) ?

debian

@SGaist now we are use qt-4.7.3, but it very old version and very hard add new future in application

SGaist

That's why I suggest to first try with 4.8.7. That way you ensure that it's still working with that one. Then you can compare the backend with 5.6 to see if you can spot something.

You should also take a look at the bug report system to see if there's anything related.