Le 21/05/2016 23:07, Bruce Dubbs a écrit :
Pierre Bechetoille wrote:
Hi,
Following BLFS dev, I built latest KDE plasma and sddm with QT-5.6.0.
The
build was OK.
However starting sddm or kde plasma failed (segmentation fault).
Using gdb on sddm, I finally found the culprit: the crash occured in
QV4::ExecutionEngine::newArrayObject(int) () from
/usr/lib/libQt5Qml.so.5
Googling the problem, I found this issue in Qt bugreports:
https://bugreports.qt.io/browse/QTBUG-52057
The description explains exactly what happens :
"Upcoming gcc-6 has much more aggressive dead-store elimination.
See: http://gcc.gnu.org/gcc-6/porting_to.html (-flifetime-dse section).
Due to undefined behavior in QV4::ExecutionEngine::newArrayObject(int)
this will lead to segfaults"
There is no patch currently available however, the author suggests
compiling Qt-5.6.0 with gcc-6 adding "-flifetime-dse=1" to
QMAKE_CXXFLAGS
(addition in
qt-everywhere-opensource-src-5.6.0/qtbase/mkspecs/linux-g++/qmake.conf).
And it works ! I now can start sddm / kde plasma without crash.
Hope this can help if anyone encounters the same problem.
Sounds like we need a sed, but I do not see any QMAKE_CXXFLAGS
settings in that qmake.conf file. Do we just need to add
QMAKE_CXXFLAGS += -flifetime-dse=1
to the end of the file?
-- Bruce
Yes, it is what I did. But there are lot of .conf files in mkspecs
directory: maybe there is a more appropriate place (e.g.
qt-everywhere-opensource-src-5.6.0/qtbase/mkspecs/common/linux.conf).
Pierre
--
http://lists.linuxfromscratch.org/listinfo/blfs-support
FAQ: http://www.linuxfromscratch.org/blfs/faq.html
Unsubscribe: See the above information page
