Created attachment 665197 [details] emerge --info Hi, just updated Qt to 5.15.1 and now my KDE desktop is flipping out - kwin complains that "Compositing is not possible", I get big black rectangles where the menus should be in systemsettings, my panels are gone, and my desktop background isn't being drawn at all (so windows leave trails when I move them). glxinfo | grep direct says Yes, glxgears and vkcube work fine, my web browsers seem to have 3d rendering, mpv quite happily uses gpu rendering, and Steam (and several games) are fine too - it's only Qt things that seem to be affected. I added the following to my package.mask as they were recently updated: >=dev-qt/qtcore-5.15.1 >=dev-qt/qtnetwork-5.15.1 >=dev-qt/qtxml-5.15.1 >=dev-qt/qttest-5.15.1 >=dev-qt/qtconcurrent-5.15.1 >=dev-qt/qtsql-5.15.1 >=dev-qt/qtserialport-5.15.1 >=dev-qt/qtpaths-5.15.1 >=dev-qt/qtdbus-5.15.1 >=dev-qt/qdbus-5.15.1 >=dev-qt/qtgui-5.15.1 >=dev-qt/qtx11extras-5.15.1 >=dev-qt/qtwidgets-5.15.1 >=dev-qt/qtdeclarative-5.15.1 >=dev-qt/qtsvg-5.15.1 >=dev-qt/linguist-tools-5.15.1 >=dev-qt/qtprintsupport-5.15.1 >=dev-qt/qtopengl-5.15.1 >=dev-qt/qtgraphicaleffects-5.15.1 >=dev-qt/qtquickcontrols2-5.15.1 >=dev-qt/qtmultimedia-5.15.1 >=dev-qt/qtquickcontrols-5.15.1 >=dev-qt/qtwayland-5.15.1 >=dev-qt/qtwebchannel-5.15.1 >=dev-qt/qtsensors-5.15.1 >=dev-qt/designer-5.15.1 >=dev-qt/qtbluetooth-5.15.1 >=dev-qt/qtxmlpatterns-5.15.1 >=dev-qt/qtscript-5.15.1 >=dev-qt/qtvirtualkeyboard-5.15.1 >=dev-qt/qtpositioning-5.15.1 >=dev-qt/qtwebsockets-5.15.1 >=dev-qt/qtwebengine-5.15.1 >=dev-qt/qtscxml-5.15.1 and will report back when it's done downgrading. I'm using nvidia-drivers-450.57-r1 and I haven't updated it since August, while this issue appeared today after updating Qt yesterday. It's a little tricky to search for relevant bugs with these symptoms, does anyone have a link to something upstream I can check?
After downgrading the listed packages back to their various qt-5.14.2 versions, everything has returned to normal on my desktop - compositing is working fine, and KDE panels and desktop backgrounds and things are being drawn correctly.
(In reply to Michael Moon from comment #0) > I'm using nvidia-drivers-450.57-r1 and I haven't updated it since August Please use a version that is actually in Gentoo repository, and try with latest 455.23.04-r1 in ~arch as well. This is a clear Nvidia bug suspect.
Nothing to do from KDE proj side. Re trouble with Nvidia 450.xx see bug 747472.
With nvidia-drivers-455.28 and QT-5.15.1 the problem appears to be resolved, so I guess it's confirmed as an nvidia-drivers problem. WRT the linked bugs (thanks for the links btw), this is a desktop with only nVidia graphics, not a system with dual graphics.
Should Gentoo's QT packages add a blocker between QT-5.15 and nvidia-drivers-450 to reduce the chance of others having to search this bug?
After a reboot my plasmashell is crashing on an infinite loop in Qt5Quick, but I guess that's a separate issue which I'll make a separate bug report about
(In reply to Michael Moon from comment #5) > Should Gentoo's QT packages add a blocker between QT-5.15 and > nvidia-drivers-450 No, this strategy would produce an insane amount of blockers.
