Qt 5.9.4 OpenGL examples crash

SGaist

Did you compare the sources of this example in both versions of Qt ? Is it he same code ?

fatih.erol

The source code for qtbase/examples/opengl/contextinfo are very similar in 5.3.2 and 5.9.4. The latter has some command line arguments, and minor fixes.

Can the issue be related to existence of /usr/include/drm directory during compilation?
I am asking, because I have seen that, while packaging ArchLinux linux-api-headers , /usr/include/drm is removed:

# use headers from libdrm
rm -r "$pkgdir/usr/include/drm"

During the compilation of contextinfo example, 5.9.4 has an extra /usr/include/libdrm include path, while 5.3.2 does not.

0_1519228748222_2495b3aa-f2a9-4148-b31e-47645878b7a9-image.png

Here is the sorted output of ldd contextinfo for 5.9.4 on the left and 5.3.2 on the right (both link libdrm):

0_1519227115753_a224721b-6f28-4c6b-b43f-02742b03bf42-image.png

SGaist

Do you mean that the cross-compiling environment changed between your 5.3 and 5.9 builds ?

fatih.erol

yes. well, 5.3.2 package is taken off the official site, so, it is most likely not cross-compiled. 5.9.4 is cross-built by me.

sierdzio

Official 5.3.2 are in Qt archive: https://download.qt.io/archive/qt/5.3/5.3.2/

fatih.erol

sorry. i meant Qt 5.3.2 package comes from Arch Linux official site, so, it is built and prepared by someone else using respective tools on a i686 development system or chroot environment.

I downloaded Qt 5.9.4 from download.qt.io, and cross-compiled it myself.

fatih.erol

I wonder whether these are relevant:
https://bugreports.qt.io/browse/QTBUG-64587
https://bugreports.qt.io/browse/QTBUG-59636

SGaist

The first one is not implemented and the second is fixed for 5.9.5. You can already test that by building from git.

fatih.erol

Update on this issue:

Qt 5.3.2 built on the 32-bit system : opengl examples run successfully.
Qt 5.9.3 built on the 32-bit system : legacy opengl examples run successfully. cube/hellogl2/texture crashes.
Qt 5.9.4 cross-compiled for the 32-bit system : legacy opengl examples run successfully. cube/hellogl2/texture crashes.
Qt 5.10.1 cross-compiled for the 32-bit system : legacy opengl examples run successfully. cube/hellogl2/texture crashes.

I haven't managed to cross-compile 5.3.2 yet, to confirm that cross-compilation works properly.
Here is the stack trace from the crashed cube example application for Qt 5.9.4:

(gdb) run
Starting program: /home/root/opengl/cube/cube 
warning: Could not load shared library symbols for linux-gate.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0xb46bab40 (LWP 585)]
pci id for fd 6: 8086:8108, driver (null)

Program received signal SIGSEGV, Segmentation fault.
0xb38ce7df in ?? () from /lib/libEMGDOGL.so
(gdb) thread apply all backtrace

Thread 2 (Thread 0xb46bab40 (LWP 585)):
#0  0xb7ffd428 in __kernel_vsyscall ()
#1  0xb6a963fb in poll () from /usr/lib/libc.so.6
#2  0xb4df8f1d in ?? () from /usr/lib/libxcb.so.1
#3  0xb4dfaf6b in xcb_wait_for_event () from /usr/lib/libxcb.so.1
#4  0xb4993703 in ?? () from /usr/lib/libQt5XcbQpa.so.5
#5  0xb6ddcfb1 in ?? () from /usr/lib/libQt5Core.so.5
#6  0xb6cd61a6 in start_thread () from /usr/lib/libpthread.so.0
#7  0xb6aa0e9e in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0xb4c4c740 (LWP 581)):
#0  0xb38ce7df in ?? () from /lib/libEMGDOGL.so
#1  0xb38cee9f in ?? () from /lib/libEMGDOGL.so
#2  0xb38cdbf1 in ?? () from /lib/libEMGDOGL.so
#3  0xb38cf44b in ?? () from /lib/libEMGDOGL.so
#4  0xb38cf9d8 in ?? () from /lib/libEMGDOGL.so
#5  0xb38d04e8 in ?? () from /lib/libEMGDOGL.so
#6  0xb385cc81 in ?? () from /lib/libEMGDOGL.so
#7  0xb38e7b76 in pvroglDrawArrays () from /lib/libEMGDOGL.so
#8  0xb76ad8b7 in ?? () from /usr/lib/libQt5Gui.so.5
#9  0xb764d379 in ?? () from /usr/lib/libQt5Gui.so.5
#10 0xb764dadc in QPlatformBackingStore::composeAndFlush(QWindow*, QRegion const&, QPoint const&, QPlatformTextureList*, QOpenGLContext*, bool) () from /usr/lib/libQt5Gui.so.5
#11 0xb49b0686 in ?? () from /usr/lib/libQt5XcbQpa.so.5
#12 0xb79ae3c7 in ?? () from /usr/lib/libQt5Widgets.so.5
#13 0xb79afa09 in ?? () from /usr/lib/libQt5Widgets.so.5
#14 0xb79b104d in ?? () from /usr/lib/libQt5Widgets.so.5
#15 0xb79b17f2 in ?? () from /usr/lib/libQt5Widgets.so.5
#16 0xb79cbd37 in QWidgetPrivate::syncBackingStore(QRegion const&) () from /usr/lib/libQt5Widgets.so.5
#17 0xb7a012ea in ?? () from /usr/lib/libQt5Widgets.so.5
#18 0xb7a01e1a in ?? () from /usr/lib/libQt5Widgets.so.5
#19 0xb79a0f4a in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#20 0xb79a8d2c in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
#21 0xb6fa396c in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/libQt5Core.so.5
#22 0xb73690e2 in QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::ExposeEvent*) () from /usr/lib/libQt5Gui.so.5
#23 0xb7369df9 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /usr/lib/libQt5Gui.so.5
#24 0xb7343cec in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Gui.so.5
#25 0xb4a0298e in ?? () from /usr/lib/libQt5XcbQpa.so.5
#26 0xb5019ba4 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#27 0xb5019ec9 in ?? () from /usr/lib/libglib-2.0.so.0
#28 0xb5019f96 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#29 0xb6ff64b4 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#30 0xb4a02b61 in ?? () from /usr/lib/libQt5XcbQpa.so.5
#31 0xb6fa13a6 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#32 0xb6fa17fa in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#33 0xb6faa796 in QCoreApplication::exec() () from /usr/lib/libQt5Core.so.5
#34 0xb735f1f1 in QGuiApplication::exec() () from /usr/lib/libQt5Gui.so.5
#35 0xb79a0ea4 in QApplication::exec() () from /usr/lib/libQt5Widgets.so.5
#36 0x0804ad69 in main ()
(gdb) continue
Continuing.
[Thread 0xb46bab40 (LWP 585) exited]

Program terminated with signal SIGSEGV, Segmentation fault.
The program no longer exists.
(gdb)

SGaist

Do you also have that with 5.9.5/5.11 Beta ?

fatih.erol

I haven't tested with 5.9.5 and 5.11, checked only the official releases under https://download.qt.io.

SGaist

My bad, I'm a bit early for the 5.9.5 release which should happen during March.

The beta can be downloaded from the development_releases subfolder.

fatih.erol

I tried building 5.11.0-beta1, but it fails (I guess, since I have an older mesa-libgl):

qeglfskmsgbmwindow.cpp: In member function ‘virtual void QEglFSKmsGbmWindow::resetSurface()’:
qeglfskmsgbmwindow.cpp:58:5: error: ‘PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC’ was not declared in this scope
     PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC createPlatformWindowSurface = nullptr;
     ^
qeglfskmsgbmwindow.cpp:61:9: error: ‘createPlatformWindowSurface’ was not declared in this scope
         createPlatformWindowSurface = reinterpret_cast<PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC>(
         ^
qeglfskmsgbmwindow.cpp:61:56: error: ‘PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC’ does not name a type
         createPlatformWindowSurface = reinterpret_cast<PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC>(
                                                        ^
qeglfskmsgbmwindow.cpp:65:9: error: ‘createPlatformWindowSurface’ was not declared in this scope
     if (createPlatformWindowSurface) {
         ^
Makefile:2994: recipe for target '.obj/qeglfskmsgbmwindow.o' failed
make[2]: *** [.obj/qeglfskmsgbmwindow.o] Error 1

fatih.erol

well, it looks like this is an EMGD<=>mesa<=>Qt issue.

EMGD + mesa 10.1.0 + Qt 5.3.2: OK
EMGD + mesa 10.1.0 + Qt 5.9.4: openGL examples cube/hellogl2/textures crash
EMGD + mesa 10.3.0 + Qt 5.9.4: openGL examples cube/hellogl2/textures run, but EMGD hardware acceleration fails:

libGL: OpenDriver: trying /usr/lib/xorg/modules/dri/tls/emgd_dri.so
libGL: OpenDriver: trying /usr/lib/xorg/modules/dri/emgd_dri.so
libGL: dlopen /usr/lib/xorg/modules/dri/emgd_dri.so failed (/usr/lib/xorg/modules/dri/emgd_dri.so: undefined symbol: _glapi_Dispatch)
libGL error: unable to load driver: emgd_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: emgd
libGL: OpenDriver: trying /usr/lib/xorg/modules/dri/tls/swrast_dri.so
libGL: OpenDriver: trying /usr/lib/xorg/modules/dri/swrast_dri.so
libGL: Can't open configuration file /root/.drirc: No such file or directory.
libGL: Can't open configuration file /root/.drirc: No such file or directory.

Any idea on how to get EMGD working with mesa 10.3.0?

# ldd -r /usr/lib/xorg/modules/dri/emgd_dri.so 
ldd: warning: you do not have execution permission for `/usr/lib/xorg/modules/dri/emgd_dri.so'
	linux-gate.so.1 (0xb775f000)
	libm.so.6 => /lib/libm.so.6 (0xb74d1000)
	libpthread.so.0 => /lib/libpthread.so.0 (0xb74b5000)
	libexpat.so.1 => /lib/libexpat.so.1 (0xb748c000)
	libdl.so.2 => /lib/libdl.so.2 (0xb7487000)
	libdrm.so.2 => /lib/libdrm.so.2 (0xb7478000)
	libEMGDOGL.so => /lib/libEMGDOGL.so (0xb71c7000)
	libEMGD2d.so => /lib/libEMGD2d.so (0xb71bf000)
	libstdc++.so.6 => /lib/libstdc++.so.6 (0xb70c9000)
	libgcc_s.so.1 => /lib/libgcc_s.so.1 (0xb70ac000)
	libc.so.6 => /lib/libc.so.6 (0xb6ef4000)
	/usr/lib/ld-linux.so.2 (0xb7760000)
	libemgdsrv_um.so => /lib/libemgdsrv_um.so (0xb6ed1000)
undefined symbol: _glapi_Dispatch	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_Context	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_get_dispatch_table_size	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_get_dispatch	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_get_context	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_add_dispatch	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_set_context	(/usr/lib/xorg/modules/dri/emgd_dri.so)
undefined symbol: _glapi_set_dispatch	(/usr/lib/xorg/modules/dri/emgd_dri.so)

# strings -a /usr/lib/libglapi.so | grep _glapi_Dispatch
_glapi_Dispatch

fatih.erol

so, any suggestions on how to make EMGD + mesa 10.1.0 + Qt 5.9.4 work?
Qt 5.3.2 works with the same combination.
When Qt 5.3.2 qtbase/examples/opengl is built against Qt 5.9.4, they work as well, except 'stereo buffers' in contextinfo example.
When Qt 5.9.4 qtbase/examples/opengl is built against Qt 5.9.4, examples such as cube, textures crash, and 'stereo buffers' in contextinfo fails as well.