Dear Maintainer,

on a fresh debian 13 install (default gnome desktop), doomsday segfaults on start with the following error message:
***
QSocketNotifier: Can only be used with threads started with QThread
Segmentation fault
***

thanks,
Daniel

Hello,
this crash seems related to using a Wayland desktop.
I get a backtrace as shown in [2] using a Plasma Wayland session.

As a workaround, please check if starting doomsday
with this command line avoids the crash:

   QT_QPA_PLATFORM=xcb doomsday

Using this environment should make Qt use the XWayland server,
and is mentioned in the upstream forum [1].

Because this shouldn't "rendering it completely unusable to everyone",
would severity important be better suited?

Kind regards,
Bernhard


[1]
https://talk.dengine.net/discussion/2972/linux-wayland
https://tracker.dengine.net/issues/2473


[2]
Thread 1 "doomsday" received signal SIGSEGV, Segmentation fault.
0x00007ffff539a1c3 in _XFlush () from /lib/x86_64-linux-gnu/libX11.so.6
(gdb) bt
#0  0x00007ffff539a1c3 in _XFlush () from /lib/x86_64-linux-gnu/libX11.so.6
#1  0x00007ffff539cec5 in _XGetRequest () from /lib/x86_64-linux-gnu/libX11.so.6
#2  0x00007ffff538f905 in XQueryExtension () from /lib/x86_64-linux-gnu/libX11.so.6
#3  0x00007ffff53823f4 in XInitExtension () from /lib/x86_64-linux-gnu/libX11.so.6
#4  0x00007ffff69090ef in XextAddDisplay () from /lib/x86_64-linux-gnu/libXext.so.6
#5  0x00007ffff68c786f in ?? () from /lib/x86_64-linux-gnu/libXrandr.so.2
#6  0x00007ffff68c7f88 in XRRQueryExtension () from /lib/x86_64-linux-gnu/libXrandr.so.2
#7  0x00007ffff7d615c7 in de::internal::RRInfo::RRInfo() () from /lib/x86_64-linux-gnu/libdeng_gui.so.2.3
#8  0x00007ffff7d60bfb in DisplayMode_Native_Init () from /lib/x86_64-linux-gnu/libdeng_gui.so.2.3
#9  0x00007ffff7cefdd9 in DisplayMode_Init () from /lib/x86_64-linux-gnu/libdeng_gui.so.2.3
#10 0x00005555557539e9 in ClientApp::initialize() ()
#11 0x00005555557352af in main ()
(gdb)

Sorry, used a backtrace without debug symbols:

Thread 1 "doomsday" received signal SIGSEGV, Segmentation fault.
0x00007ffff539a1c3 in require_socket (dpy=0x555555fe2ea0) at ../../src/xcb_io.c:70
warning: 70     ../../src/xcb_io.c: Datei oder Verzeichnis nicht gefunden
(gdb) bt
#0  0x00007ffff539a1c3 in require_socket (dpy=0x555555fe2ea0) at ../../src/xcb_io.c:70
#1  _XFlush (dpy=0x555555fe2ea0) at ../../src/xcb_io.c:606
#2  0x00007ffff539cec5 in _XGetRequest (dpy=dpy@entry=0x555555fe2ea0, type=type@entry=98 'b', len=len@entry=8) at ../../src/XlibInt.c:1778
#3  0x00007ffff538f905 in XQueryExtension (dpy=dpy@entry=0x555555fe2ea0, name=name@entry=0x7ffff68d1108 <XRRExtensionName> "RANDR", major_opcode=major_opcode@entry=0x7fffffffd694, first_event=first_event@entry=0x7fffffffd698, first_error=first_error@entry=0x7fffffffd69c) at ../../src/QuExt.c:49
#4  0x00007ffff53823f4 in XInitExtension (dpy=dpy@entry=0x555555fe2ea0, name=name@entry=0x7ffff68d1108 <XRRExtensionName> "RANDR") at ../../src/InitExt.c:59
#5  0x00007ffff69090ef in XextAddDisplay (extinfo=extinfo@entry=0x7ffff68d1190 <XRRExtensionInfo>, dpy=dpy@entry=0x555555fe2ea0, ext_name=ext_name@entry=0x7ffff68d1108 <XRRExtensionName> "RANDR", hooks=hooks@entry=0x7ffff68d1120 <rr_extension_hooks>, nevents=nevents@entry=2, data=data@entry=0x0) at ../../src/extutil.c:110
#6  0x00007ffff68c786f in XRRFindDisplay (dpy=dpy@entry=0x555555fe2ea0) at ../../src/Xrandr.c:295
#7  0x00007ffff68c7f88 in XRRFindDisplay (dpy=0x555555fe2ea0) at ../../src/Xrandr.c:357
#8  XRRQueryExtension (dpy=0x555555fe2ea0, event_base_return=0x7fffffffd7b8, error_base_return=0x7fffffffd7b8) at ../../src/Xrandr.c:348
#9  0x00007ffff7d615c7 in de::internal::RRInfo::RRInfo (this=0x7fffffffd850) at ./doomsday/sdk/libgui/src/displaymode_x11.cpp:63
#10 0x00007ffff7d60bfb in DisplayMode_Native_Init () at ./doomsday/sdk/libgui/src/displaymode_x11.cpp:188
#11 0x00007ffff7cefdd9 in DisplayMode_Init () at ./doomsday/sdk/libgui/src/displaymode.cpp:195
#12 0x00005555557539e9 in ClientApp::initialize (this=0x7fffffffda20) at ./doomsday/apps/client/src/clientapp.cpp:628
#13 0x00005555557352af in main (argc=<optimized out>, argv=0x7fffffffdc48) at ./doomsday/apps/client/src/main_client.cpp:109
(gdb)

control: tags + patch


Hello,
unfortunately upstream had dropped Qt altogether,
but had no release the last years.

I tried what happens if simply avoid all "QX11Info::display()"
by returning early if "QX11Info::isPlatformX11()".
This makes it kind of playable in a short test,
but mouse look is not possible because of following message:
     qt.qpa.wayland: Setting cursor position is not possible on wayland


So I made another attempt to set QT_QPA_PLATFORM=xcb if a Wayland session is detected,
like it is done e.g. in FreeCAD or others [1], see attached patch.

Kind regards,
Bernhard


[1]
https://sources.debian.org/src/freecad/1.0.0+dfsg-8/src/Main/MainGui.cpp?hl=109#L109
https://sources.debian.org/src/audacious/4.4.2-1/src/libaudqt/audqt.cc?hl=131#L131
https://sources.debian.org/src/goldendict-ng/25.06.0-2/src/main.cc?hl=266#L266

tags 1113738 + patch
thanks

Dear maintainer,

I've prepared an NMU for doomsday (versioned as 2.3.1+ds1-1.1) and
uploaded it to DELAYED/2. Please feel free to tell me if I should
cancel it.

cu
Adrian

We believe that the bug you reported is fixed in the latest version of
doomsday, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1113738@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Adrian Bunk <bunk@debian.org> (supplier of updated doomsday package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Thu, 30 Oct 2025 19:32:32 +0200
Source: doomsday
Architecture: source
Version: 2.3.1+ds1-1.1
Distribution: unstable
Urgency: medium
Maintainer: Debian Games Team <pkg-games-devel@lists.alioth.debian.org>
Changed-By: Adrian Bunk <bunk@debian.org>
Closes: 1112854 1113738
Changes:
 doomsday (2.3.1+ds1-1.1) unstable; urgency=medium
 .
   * Non-maintainer upload.
   * Workaround FTBFS with CMake 4. (Closes: #1112854)
   * Add workaround from Bernhard Übelacker for running
     under Wayland. (Closes: #1113738)
Checksums-Sha1:
 39d4f9f73c41fde396487296dfd62b25b492e5fb 2399 doomsday_2.3.1+ds1-1.1.dsc
 11f83d419dbb615bd6eb9edf6b34a2e8e27e05d7 13776 doomsday_2.3.1+ds1-1.1.debian.tar.xz
Checksums-Sha256:
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 284e4da9a3f033592aed340bd73977f207e640026a974dabfb7c657b26828b10 13776 doomsday_2.3.1+ds1-1.1.debian.tar.xz
Files:
 f6e206c475598afdcde22df408c7258d 2399 games optional doomsday_2.3.1+ds1-1.1.dsc
 153279ccd8dbd1c323cdd53cd277a686 13776 games optional doomsday_2.3.1+ds1-1.1.debian.tar.xz
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