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#1 2018-05-27 02:57:46

Floft
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Registered: 2009-11-15
Posts: 42
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VirtualBox Segfault with Qt 5.11 in Gnome

I upgraded to Qt 5.11 for all the qt5-{base,declarative,location,script,sensors,...} packages. However, now when running VirtualBox (5.2.12-1) in Gnome (3.28.2-1) with Qt 5.11 I get:

Qt WARNING: QSocketNotifier: Can only be used with threads started with QThread
Segmentation fault

And, in dmesg:

[ 2652.437759] traps: VirtualBox[8898] general protection ip:7f88d2ae125a sp:7fff59b688e0 error:0 in libX11.so.6.3.0[7f88d2ab4000+139000]

However, if I downgrade to 5.10, then launching VirtualBox works fine in Gnome:

sudo pacman -U /var/cache/pacman/pkg/qt5-base-5.10.1-8-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-declarative-5.10.1-4-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-location-5.10.1-2-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-script-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-sensors-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-svg-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-tools-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-wayland-5.10.1-3-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-webchannel-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-webengine-5.10.1-2-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-x11extras-5.10.1-1-x86_64.pkg.tar.xz /var/cache/pacman/pkg/qt5-xmlpatterns-5.10.1-1-x86_64.pkg.tar.xz

Any ideas? I tried it in Openbox and VirtualBox runs just fine with Qt 5.11.

Last edited by Floft (2018-05-27 16:52:27)

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#2 2018-05-27 05:19:07

ooo
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Registered: 2013-04-10
Posts: 1,607

Re: VirtualBox Segfault with Qt 5.11 in Gnome

Gnome on Xorg or wayland?

I couldn't reproduce your issue initially, but after installing qt5-wayland, I get the same error and segfault.
After uninstalling qt5-wayland, virtualbox starts again.

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#3 2018-05-27 05:52:24

Floft
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Registered: 2009-11-15
Posts: 42
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Re: VirtualBox Segfault with Qt 5.11 in Gnome

Wayland, I think -- looking at ps, I see Xwayland running.

Well, that is indeed interesting. I removed 'qt5-wayland' and that appears to work. Cool. Thanks.

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#4 2018-05-27 14:28:36

ooo
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Registered: 2013-04-10
Posts: 1,607

Re: VirtualBox Segfault with Qt 5.11 in Gnome

I wouldn't call this solved. Removing qt5-wayland simply works around the issue by using the xcb backend (I assume) instead of wayland.
If you didn't have this problem before, it's a regression in qt 5.11.

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#5 2018-05-27 15:02:33

Lone_Wolf
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From: Netherlands, Europe
Registered: 2005-10-04
Posts: 7,135

Re: VirtualBox Segfault with Qt 5.11 in Gnome

ooo wrote:

If you didn't have this problem before, it's a regression in qt 5.11.

I'd verify if a rebuild of virtualbox against qt5.11 solves it before calling it a regression.


Multi-init booting with apg Openrc and systemd coexisting
Automounting : not needed, i prefer pmount
Aur helpers : makepkg + my own local repo === rarely need them

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#6 2018-05-27 17:02:59

ooo
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Registered: 2013-04-10
Posts: 1,607

Re: VirtualBox Segfault with Qt 5.11 in Gnome

As a non-native speaker, I thought regression would be an appropriate term even if you could solve the issue by rebuilding.

Nevertheless, I tried rebuilding, and the build failed for some seemingly not-simple cause.
Other qt5 applications (at least qjackctl) seem to work, so my guess is this is something that has to be fixed in virtualbox.

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#7 2018-05-27 17:12:00

arojas
Developer
From: Spain
Registered: 2011-10-09
Posts: 1,628

Re: VirtualBox Segfault with Qt 5.11 in Gnome

Qt 5.11 defaults to the Wayland backend on Wayland sessions. So if the bug, as it seems, is that Virtualbox crashes when run natively on Wayland then it is technically not a regression, it has simply surfaced now that Qt uses Wayland by default.

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#8 2018-05-27 18:24:35

ooo
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Registered: 2013-04-10
Posts: 1,607

Re: VirtualBox Segfault with Qt 5.11 in Gnome

Thanks for the explanation arojas. That would make sense.
I couldn't find any bug reports for virtualbox that would confirm that it can't be started with wayland platform plugin though, but overall it's wayland support seems to be quite incomplete.

I suppose it would be good idea to confirm that virtualbox fails to start with same error using '-platform wayland' and qt 5.10.

For now, either removing qt5-wayland, or starting virtualbox with 'virtualbox -platform xcb' should work.

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#9 2018-05-27 19:05:15

Floft
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Registered: 2009-11-15
Posts: 42
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Re: VirtualBox Segfault with Qt 5.11 in Gnome

With Qt 5.11, 'VirtualBox -platform wayland' gives:

Qt WARNING: QSocketNotifier: Can only be used with threads started with QThread
Segmentation fault

[26795.830690] VirtualBox[24210]: segfault at 0 ip 0000000000000000 sp 00007ffec3d579b8 error 14 in VirtualBox[564c64c53000+25000]

I downgraded to 5.10 (as in initial post), then 'VirtualBox -platform wayland' gives:

Qt WARNING: QSocketNotifier: Can only be used with threads started with QThread
Segmentation fault

[26728.168462] VirtualBox[23467]: segfault at 0 ip 0000000000000000 sp 00007fff453b7828 error 14 in VirtualBox[560834df1000+25000]

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#10 2018-05-29 10:22:39

ArchDoctor_needed
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Registered: 2017-05-31
Posts: 7

Re: VirtualBox Segfault with Qt 5.11 in Gnome

ooo wrote:

Thanks for the explanation arojas. That would make sense.
[...]
For now, either removing qt5-wayland, or starting virtualbox with 'virtualbox -platform xcb' should work.

I can verify that the workaround with 'virtualbox -platform xcb' is working in order to start the virtualbox.

But i can't get any image running

I'm getting the following error

The virtual machine 'Ubuntu1604-Server' has terminated unexpectedly during startup because of signal 11.
Result Code: 
NS_ERROR_FAILURE (0x80004005)
Component: 
MachineWrap
Interface: 
IMachine {85cd948e-a71f-4289-281e-0ca7ad48cd89}
May 29 13:01:14 PC gnome-shell[1231]: TODO: support set_buffer_transform request
May 29 13:01:14 PC gnome-shell[1231]: TODO: support set_buffer_transform request
May 29 13:01:14 PC gnome-shell[1231]: TODO: support set_buffer_transform request
May 29 13:01:14 PC kernel: VirtualBox[5147]: segfault at 2e2f00000001 ip 00007f1faef1125a sp 00007ffe1cda7100 error 4 in libX11.so.6.3.0[7f1faeee4000+139000]

Last edited by ArchDoctor_needed (2018-05-29 11:02:13)

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#11 2018-05-29 14:56:45

ooo
Member
Registered: 2013-04-10
Posts: 1,607

Re: VirtualBox Segfault with Qt 5.11 in Gnome

ArchDoctor_needed, your error has nothing to do with the original issue on this thread.
Please read the CoC, especially this part: https://wiki.archlinux.org/index.php/Co … _hijacking

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#12 2018-05-29 15:32:21

Floft
Member
Registered: 2009-11-15
Posts: 42
Website

Re: VirtualBox Segfault with Qt 5.11 in Gnome

I noticed that as well when I ran 'virtualbox -platform xcb'. I can run the manager but as soon as I try to open a VM, the new window will die. Same when I tried "vboxmanage startvm ..." However, you can manually start the VM by name or ID with the command:

virtualbox -platform xcb --startvm "name or id here"

It's a little inconvenient. The alternative is to remove qt5-wayland, which means it'll default to xcb in both cases.

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#13 2018-05-29 15:40:19

arojas
Developer
From: Spain
Registered: 2011-10-09
Posts: 1,628

Re: VirtualBox Segfault with Qt 5.11 in Gnome

Floft wrote:

It's a little inconvenient. The alternative is to remove qt5-wayland, which means it'll default to xcb in both cases.

Or just export QT_QPA_PLATFORM=xcb

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#14 2018-05-29 16:00:16

ArchDoctor_needed
Member
Registered: 2017-05-31
Posts: 7

Re: VirtualBox Segfault with Qt 5.11 in Gnome

Thanks again, that was the last piece to get the workaround running. I used the solution with

QT_QPA_PLATFORM=xcb

for convenience.

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#15 2018-06-12 05:57:15

mmans0ur
Member
Registered: 2018-06-12
Posts: 1

Re: VirtualBox Segfault with Qt 5.11 in Gnome

I had the same problem for smplayer and wireshark ( all qt5 applications )
after removing qt5-wayland all get solved !
thanks for the topic

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#16 2018-07-23 11:06:09

cornacchia
Member
Registered: 2018-07-23
Posts: 6

Re: VirtualBox Segfault with Qt 5.11 in Gnome

I'm having a similar problem, but running virtualbox with "-platform xcb" doesn't help.

Here are some details:

Command line output (it's the same with "-platform xcb"):

$ virtualbox
Segmentation fault

Dmesg:

VirtualBox[5889]: segfault at 7ffed1196f88 ip 00007f0a9bca85f4 sp 00007ffed1196f50 error 6 in libQt5Gui.so.5.11.1[7f0a9bab3000+574000]

Installed Qt packages:

qt5-base 5.11.1-1
qt5-declarative 5.11.1-1
qt5-location 5.11.1-1
qt5-multimedia 5.11.1-1
qt5-sensors 5.11.1-1
qt5-svg 5.11.1-1
qt5-webchannel 5.11.1-1
qt5-webkit 5.212.0alpha2-18
qt5-x11extras 5.11.1-1
qt5-xmlpatterns 5.11.1-1

Virtualbox packages:

$ pacman -Q | grep virtualbox
virtualbox 5.2.16-1
virtualbox-guest-dkms 5.2.16-1
virtualbox-guest-iso 5.2.16-1
virtualbox-guest-utils 5.2.16-1
virtualbox-host-dkms 5.2.16-1
virtualbox-ext-oracle 5.2.16-1

I'm using wayland:

$ pacman -Q | grep wayland
wayland 1.15.0-1
wayland-protocols 1.14-1
xorg-server-xwayland 1.20.0-9

Any ideas?

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#17 2018-07-23 12:39:13

arojas
Developer
From: Spain
Registered: 2011-10-09
Posts: 1,628

Re: VirtualBox Segfault with Qt 5.11 in Gnome

cornacchia wrote:

Any ideas?

You don't even have qt5-wayland installed, so your issue is not related to this post

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