- plasma-desktop uses a new code path in 4.10, which triggers a Qt bug leading to immediate SIGSEGV.
- The Qt bug only becomes fatal for some compiler options, and only on 64bit systems (amd64).
- The Qt bug may be a fundamental architectural problem that needs proper thought.
- Gentoo bug 450818: "x11-libs/qt-core-4.8.4: QDeclarativeVMEMetaObject::metaCall SIGSEGV when called from QMetaObject::metaCall"
- KDE bug 311751: "QML system tray crashes plasma-desktop on startup"
- Qt bug 29082: "QDeclarativeVMEMetaObject::metaCall SIGSEGV when called from QMetaObject::metaCall"
- Qt code review 46228: "Avoid calling metacall directly from the property animation code"
- Reverting the commit to plasma-workspace that introduced the problem makes the crash go away, but plasma-desktop starts hogging 100% CPU after a while. (This is done in plasma-workspace-4.10.0-r1 as a stopgap measure.) Kinda makes sense since the commit was there to fix a problem - now we hit the original problem.
- The bug seems not to occur if Qt is compiled with CFLAGS="-Os". Cause unknown.
- David E. Narváez aka dmaggot wrote a patch for Qt that fixes this particular codepath but likely does not solve the global problem.
- So far comments from Qt upstream indicate that this is in their opinion not the right way to fix the problem.
- Our Gentoo Qt team understandably only wants to apply a patch if it has been accepted upstream.
Sorry & stay tuned.