On Tuesday 15 July 2014 22:20:42 Boris Barbulovski wrote: > On Tue, Jul 15, 2014 at 9:22 PM, Lisandro Damián Nicanor Pérez Meyer < > > perezmeyer@gmail.com> wrote: > > reassign 754894 src:qtbase-opensource-src 5.2.0+dfsg-1 > > severity 754894 important > > thanks > > > > On Tuesday 15 July 2014 19:48:06 Boris Barbulovski wrote: > > > Package: libqt5core5a (actually all qt5 libraries) > > > > > > Version: 5.3.1+dfsg-3(jessie) > > > > > > > >From Qt 5.3 SSE2 is enabled by default crashing every Qt app when run > > > > > > on i386 version with older(non SSE2) processor. > > > > > > > > > Solution: Disable SSE2 when building Qt5 packages for i c386. > > > > Not quite. > > Here is the location when it crashes Thanks, but we know that part ;-) [snip] > > There is a better fix pending someone to step up for doing the job. It's > > not > > that simple as "just disable SSE2" because that would render some parts > > simply > > unusable. > > I don't understand what you mean by 'render some parts simply unusable'. Do > you mean some libraries will not compile? AFAIK SSE2 usage is for > performance reasons only(maybe I'm wrong). > I found this mail from Thiago Macieira( > http://lists.qt-project.org/pipermail/development/2013-November/014085.html) > where he explains the situation in more detail. Performance issues can mean "simply unusable". And right, I'm referring to that same mail, first paragraph: According to Lars and Simon, the new V4's JIT engine generates floating-point math for QML only using SSE registers on x86. That means the JIT code cannot run on CPUs that don't have SSE support. Those CPUs can only run the interpreted bytecode instead. > > The correct fix is to build *some* of the libs twice: one with SSE2 > > support > > and one without it. If properly installed the linker will do the correct > > job > > at runtime. > > Thiago(in the mail thread above) suggest something like two versions of the > library. That's where I learned it from ;) > > Interestingly enough, so far no one has reproduced this bug so far. Can > > you > > reproduce it? It would be good to know so you can tests the packages for > > us. > > yes, I can reproduce the issue, and test the packages. Now this is really cool, because it's what we need here. AFAIK no one of us maintainers have hardware to test this. Kinds regards, Lisandro. -- Either he's dead or my watch has stopped. -- Groucho Marx Lisandro Damián Nicanor Pérez Meyer http://perezmeyer.com.ar/ http://perezmeyer.blogspot.com/
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