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FS#48195 - [qt5-base] SIGFPE when starting any Qt application via Xvfb

Attached to Project: Arch Linux
Opened by Florian Bruhin (The-Compiler) - Monday, 15 February 2016, 16:47 GMT
Last edited by Felix Yan (felixonmars) - Sunday, 27 March 2016, 03:25 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Felix Yan (felixonmars)
Architecture All
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


Since some recent Xvfb update, any Qt application running in Xvfb crashes immediately:

$ xvfb-run python3 -c 'from PyQt5.QtWidgets import QApplication; QApplication([])'
/usr/bin/xvfb-run: line 170: 27927 Floating point exception(core dumped)

The stacktrace looks like this:

#0 0x00007fffe1b4dedb in QXcbScreen::updateRefreshRate(unsigned int) () from /usr/lib/
#1 0x00007fffe1b504dc in QXcbScreen::QXcbScreen(QXcbConnection*, QXcbVirtualDesktop*, unsigned int, xcb_randr_get_output_info_reply_t*, QString) () from /usr/lib/
#2 0x00007fffe1b39f5f in QXcbConnection::createScreen(QXcbVirtualDesktop*, unsigned int, xcb_randr_get_output_info_reply_t*) () from /usr/lib/
#3 0x00007fffe1b3d593 in QXcbConnection::initializeScreens() () from /usr/lib/
#4 0x00007fffe1b3dbec in QXcbConnection::QXcbConnection(QXcbNativeInterface*, bool, unsigned int, char const*) () from /usr/lib/
#5 0x00007fffe1b4383d in QXcbIntegration::QXcbIntegration(QStringList const&, int&, char**) () from /usr/lib/
#6 0x00007ffff7e233ad in ?? () from /usr/lib/qt/plugins/platforms/
#7 0x00007fffed307e62 in QPlatformIntegrationFactory::create(QString const&, QStringList const&, int&, char**, QString const&) () from /usr/lib/
#8 0x00007fffed314052 in QGuiApplicationPrivate::createPlatformIntegration() () from /usr/lib/
#9 0x00007fffed314f8d in QGuiApplicationPrivate::createEventDispatcher() () from /usr/lib/
#10 0x00007ffff1eaf126 in QCoreApplication::init() () from /usr/lib/
#11 0x00007ffff1eaf196 in QCoreApplication::QCoreApplication(QCoreApplicationPrivate&) () from /usr/lib/
#12 0x00007fffed316d79 in QGuiApplication::QGuiApplication(QGuiApplicationPrivate&) () from /usr/lib/
#13 0x00007fffeae1451d in QApplication::QApplication(int&, char**, int) () from /usr/lib/

It seems this was fixed for Qt 5.6:

I tried downgrading Xvfb to find out what change there was the culprit, but I couldn't downgrade it to 1.17.4-2 easily, and with 1.18.0-1 it happens too.

I'd appreciate if this could be backported to Archlinux' Qt 5.5 packages as it'll probably still take a month or so until 5.6 is out.
This task depends upon

Closed by  Felix Yan (felixonmars)
Sunday, 27 March 2016, 03:25 GMT
Reason for closing:  Upstream
Additional comments about closing:  Fixed in qt 5.6 packages.
Comment by Florian Bruhin (The-Compiler) - Monday, 15 February 2016, 19:21 GMT
FWIW the same patch just was backported by Debian as well:
Comment by Felix Yan (felixonmars) - Saturday, 26 March 2016, 16:46 GMT
The Qt 5.6 packages in [testing] fixed this for me, please let me know if they work for you as well.
Comment by Florian Bruhin (The-Compiler) - Saturday, 26 March 2016, 22:25 GMT
Unfortunately I probably won't get to testing them over the next few days - but since it's fixed in 5.6 and it works for you, I'm fine with closing this.