[vncserver]: kwin_x11 fails to start?

[star-buck]

29/03/15 12:30:40 Xvnc version TightVNC-1.3.10
29/03/15 12:30:40 See http://www.tightvnc.com/ for information on TightVNC
29/03/15 12:30:40 Desktop name 'X' (netrunner-Aspire-X1930:2)
29/03/15 12:30:40 Protocol versions supported: 3.3, 3.7, 3.8, 3.7t, 3.8t
29/03/15 12:30:40 Listening for VNC connections on TCP port 5902
Font directory '/usr/share/fonts/X11/75dpi/' not found - ignoring
Font directory '/usr/share/fonts/X11/100dpi/' not found - ignoring
xrdb: No such file or directory
xrdb: can't open file '/home/netrunner/.Xresources'

[star-buck]

here a screenshot of the remote connection from vncclient:

So the vncserver does start, but then kwin_x11 seems to fail due to the error in the logfile in comment above?
I know this seems likely not directly plasma-related, but stupidity on my side, so any help to get a vnc session into plasma5 would be appreciated :)

[mgraesslin]

I must say that I have no idea. I never tried to VNC into a Plasma session and even for KDE 4 it's probably years ago.

Are you trying to forward the complete session or connecting to an existing session?

[star-buck]

@mgraesslin : best is to try again then, its simple:
http://www.tightvnc.com/vncserver.1.php
vnc especially comes handy with a minicomputer like the Pi acting as a standalone unit without extra mouse+keybaord and display attached, so being functional with plasma/kwin would be nice.

[mgraesslin]

so it's starting an X-Server called Xvnc. I'll try to install it, but my guess right now is that it's missing required extensions.

[mgraesslin]

For the reference the backtrace:
Program received signal SIGSEGV, Segmentation fault.
0x00007fffee874a50 in xcb_setup_vendor_end () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
(gdb) bt
#0 0x00007fffee874a50 in xcb_setup_vendor_end () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#1 0x00007fffee874aa9 in xcb_setup_pixmap_formats_iterator () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2 0x00007fffee874ae9 in xcb_setup_roots_iterator () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3 0x00007fffeffbda4d in NETRootInfo::NETRootInfo (this=0x839620, connection=0x61c3c0, supportWindow=4294967295, wmName=0x7ffff78e696f "KWin", properties=..., windowTypes=..., states=..., properties2=..., actions=..., screen=0,
doActivate=true) at /home/martin/src/kf5/frameworks/kwindowsystem/src/netwm.cpp:669
#4 0x00007ffff775ae65 in KWin::RootInfo::RootInfo (this=0x839620, w=4294967295, name=0x7ffff78e696f "KWin", properties=..., types=..., states=..., properties2=..., actions=..., scr=0)
at /home/martin/src/kf5/kde/workspace/kwin/netinfo.cpp:140
#5 0x00007ffff775ad4d in KWin::RootInfo::create () at /home/martin/src/kf5/kde/workspace/kwin/netinfo.cpp:125
#6 0x00007ffff7714ac4 in KWin::Workspace::init (this=0x7192a0) at /home/martin/src/kf5/kde/workspace/kwin/workspace.cpp:244
#7 0x00007ffff77144e7 in KWin::Workspace::Workspace (this=0x7192a0, restore=false) at /home/martin/src/kf5/kde/workspace/kwin/workspace.cpp:213
#8 0x00007ffff776af59 in KWin::Application::createWorkspace (this=0x7fffffffdcc0) at /home/martin/src/kf5/kde/workspace/kwin/main.cpp:375
#9 0x00007ffff7bd6aef in KWin::ApplicationX11::<lambda()>::operator()(void) const (__closure=0x7fffffffc890) at /home/martin/src/kf5/kde/workspace/kwin/main_x11.cpp:173
#10 0x00007ffff7bd796d in QtPrivate::FunctorCallQtPrivate::IndexesList<, QtPrivate::List<>, void, KWin::ApplicationX11::performStartup()::<lambda()> >::call(KWin::ApplicationX11::<lambda()>, void *) (f=..., arg=0x7fffffffca00)
at /opt/qt5/include/QtCore/qobjectdefs_impl.h:494
#11 0x00007ffff7bd7922 in QtPrivate::FunctorKWin::ApplicationX11::performStartup()::<lambda(), 0>::callQtPrivate::List<, void>(KWin::ApplicationX11::<lambda()> &, void *, void *) (f=..., arg=0x7fffffffca00)
at /opt/qt5/include/QtCore/qobjectdefs_impl.h:551
#12 0x00007ffff7bd78bf in QtPrivate::QFunctorSlotObjectKWin::ApplicationX11::performStartup()::<lambda(), 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase , QObject *, void *, bool *) (which=1, this_=0x678e30,
r=0x6694d0, a=0x7fffffffca00, ret=0x0) at /opt/qt5/include/QtCore/qobject_impl.h:192
#13 0x00007fffeedfc62b in QtPrivate::QSlotObjectBase::call (this=0x678e30, r=0x6694d0, a=0x7fffffffca00) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#14 0x00007fffeedf970c in QMetaObject::activate (sender=0x6694d0, signalOffset=3, local_signal_index=1, argv=0x0) at kernel/qobject.cpp:3702
#15 0x00007fffeedf9024 in QMetaObject::activate (sender=0x6694d0, m=0x7ffff01ed720 KSelectionOwner::staticMetaObject, local_signal_index=1, argv=0x0) at kernel/qobject.cpp:3582
#16 0x00007fffeffd365b in KSelectionOwner::claimedOwnership (this=0x6694d0) at /opt/build/kf5/frameworks/kwindowsystem/src/moc_kselectionowner.cpp:150
#17 0x00007fffeffa82d9 in KSelectionOwner::Private::claimSucceeded (this=0x6841f0) at /home/martin/src/kf5/frameworks/kwindowsystem/src/kselectionowner.cpp:206
#18 0x00007fffeffa83fa in KSelectionOwner::Private::gotTimestamp (this=0x6841f0) at /home/martin/src/kf5/frameworks/kwindowsystem/src/kselectionowner.cpp:240
#19 0x00007fffeffa8a0c in KSelectionOwner::filterEvent (this=0x6694d0, ev_P=0x7fffd8001e80) at /home/martin/src/kf5/frameworks/kwindowsystem/src/kselectionowner.cpp:424
#20 0x00007fffeffa9271 in KSelectionOwner::Private::nativeEventFilter (this=0x6841f0, eventType=..., message=0x7fffd8001e80, result=0x7fffffffcd58) at /home/martin/src/kf5/frameworks/kwindowsystem/src/kselectionowner.cpp:117
#21 0x00007fffeedb1903 in QAbstractEventDispatcher::filterNativeEvent (this=0x639e80, eventType=..., message=0x7fffd8001e80, result=0x7fffffffcd58) at kernel/qabstracteventdispatcher.cpp:460
#22 0x00007fffe0ca46c9 in QXcbConnection::handleXcbEvent (this=0x61ae30, event=0x7fffd8001e80) at qxcbconnection.cpp:854
#23 0x00007fffe0ca6698 in QXcbConnection::processXcbEvents (this=0x61ae30) at qxcbconnection.cpp:1297
#24 0x00007fffe0ce71d6 in QXcbConnection::qt_static_metacall (_o=0x61ae30, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0x7fffd8002cb0) at .moc/moc_qxcbconnection.cpp:185
#25 0x00007fffeedf1d0f in QMetaCallEvent::placeMetaCall (this=0x7fffd8002cd0, object=0x61ae30) at kernel/qobject.cpp:485
#26 0x00007fffeedf2dd8 in QObject::event (this=0x61ae30, e=0x7fffd8002cd0) at kernel/qobject.cpp:1245
#27 0x00007fffe0ca7ab3 in QXcbConnection::event (this=0x61ae30, e=0x7fffd8002cd0) at qxcbconnection.cpp:1910
#28 0x00007fffef8fb5ec in QApplicationPrivate::notify_helper (this=0x612fb0, receiver=0x61ae30, e=0x7fffd8002cd0) at kernel/qapplication.cpp:3720
#29 0x00007fffef8f8d68 in QApplication::notify (this=0x7fffffffdcc0, receiver=0x61ae30, e=0x7fffd8002cd0) at kernel/qapplication.cpp:3164
#30 0x00007ffff7769ddf in KWin::Application::notify (this=0x7fffffffdcc0, o=0x61ae30, e=0x7fffd8002cd0) at /home/martin/src/kf5/kde/workspace/kwin/main.cpp:241
#31 0x00007fffeedb63bc in QCoreApplication::notifyInternal (this=0x7fffffffdcc0, receiver=0x61ae30, event=0x7fffd8002cd0) at kernel/qcoreapplication.cpp:935
#32 0x00007fffeedba01d in QCoreApplication::sendEvent (receiver=0x61ae30, event=0x7fffd8002cd0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#33 0x00007fffeedb76f5 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x6032b0) at kernel/qcoreapplication.cpp:1552
#34 0x00007fffeee2baff in QEventDispatcherUNIX::processEvents (this=0x639e80, flags=...) at kernel/qeventdispatcher_unix.cpp:579
#35 0x00007fffe0d2a30e in QUnixEventDispatcherQPA::processEvents (this=0x639e80, flags=...) at eventdispatchers/qunixeventdispatcher.cpp:62
#36 0x00007fffeedb3060 in QEventLoop::processEvents (this=0x7fffffffdbe0, flags=...) at kernel/qeventloop.cpp:128
#37 0x00007fffeedb3339 in QEventLoop::exec (this=0x7fffffffdbe0, flags=...) at kernel/qeventloop.cpp:204

This looks very similar to https://bugs.kde.org/show_bug.cgi?id=343844 which is related to not having randr and that's also what I see on that fake X:

DISPLAY=:1 xrandr
RandR extension missing

Now RandR is a required extension for KWin and apparently also for Qt - we get "incorrect" information from Qt which is causing the crash. To get this working we would need fixes in multiple areas.

Personally I consider X without RandR extension outside the specification of what KWin requires (and probably also for most other software of the workspace). My suggested action would be to change KWin to not crash but terminate. I can also work on making it work without XrandR but I fear this would end in weeks of running into strange issues.

[star-buck]

would terminate Kwin make vnc work?

[mgraesslin]

Missing randr extension is not the only problem, also fixes, composite and damage are missing. At least fixes is an extension kwin uses unconditionally and render is at least used unconditionally as a fallback for missing composite extension in the outline. This is not new, that has already been the case in 4.x - KWin won't work on that X server, KWin didn't work on that X server.

[mgraesslin]

would terminate Kwin make vnc work?

no, because any qtquick application would just crash, due to missing glx:

DISPLAY=:1 glxinfo
name of display: :1
Error: couldn't find RGB GLX visual or fbconfig

[star-buck]

so whats the preferred method then for accessing plasma5/kwin remotely from another kde or non-kde machine/OS?

[mgraesslin]

What I just want to try is whether krfb is working.

[mgraesslin]

the combination of krfb (server) and krdc (client) still works over the rdp backend.

[star-buck]

so how do i access a plasma-session from a non-kde system, e.g. Windows/Mac?

[mgraesslin]

you need to start krfb on the plasma-session. I'm not familiar with the software and do not know whether it can be started automatically.

On Windows it's just the remote windows viewer (no idea how it's called, but it should be available as rdp comes from Windows). For OSX I do not know how whether there is a rdp viewer pre-installed.

[mgraesslin]

Relevant upstream report for the actual crash condition: https://bugreports.qt.io/browse/QTBUG-31389