fvogt accepted this revision. fvogt added a comment. This revision is now accepted and ready to land.
I tried this patch and kwin still crashes in QEMU, but at a different place now at least: #0 KWin::DrmOutput::pixelSize (this=0x0) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_output.cpp:162 #1 0x00007fffdcccfca9 in KWin::DrmCrtc::blank (this=0x555555889a10) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_object_crtc.cpp:85 #2 0x00007fffdccd1398 in KWin::DrmOutput::~DrmOutput (this=0x555555843240, __in_chrg=<optimized out>) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_output.cpp:68 #3 0x00007fffdccd1699 in KWin::DrmOutput::~DrmOutput (this=0x555555843240, __in_chrg=<optimized out>) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_output.cpp:87 #4 0x00007fffdccc9912 in KWin::DrmBackend::updateOutputs (this=this@entry=0x5555557cb500) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_backend.cpp:460 #5 0x00007fffdccca81d in KWin::DrmBackend::openDrm (this=0x5555557cb500) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/plugins/platforms/drm/drm_backend.cpp:326 #6 0x00007ffff5a0ffec in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib64/libQt5Core.so.5 #7 0x00007ffff7b1c9e2 in KWin::LogindIntegration::hasSessionControlChanged (this=<optimized out>, _t1=<optimized out>, _t1@entry=true) at /usr/src/debug/kwin-5.11.90git.20171108T174438~9df174483/build/kwin_autogen/EWIEGA46WW/moc_logind.cpp:188 At this point `export KWIN_DRM_NO_AMS=1` helps though and the session starts up. Unfortunately kwin_wayland gives up just after these messages: kscreen.kwayland: Loading Wayland backend. kscreen.kded: PowerDevil SuspendSession action not available! kscreen.kwayland: Loading Wayland backend. kwin_wayland: Couldn't find current GLX or EGL context. and crashes somewhere in the destructors of Qt's global objects. REPOSITORY R108 KWin BRANCH drm-property-safety REVISION DETAIL https://phabricator.kde.org/D8752 To: graesslin, #kwin, #plasma, fvogt, subdiff Cc: plasma-devel, kwin, bwowk, ZrenBot, progwolff, lesliezhai, ali-mohamed, hardening, jensreuterberg, abetts, sebas, apol, mart