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#1 2020-08-22 20:22:08

Potomac
Member
Registered: 2011-12-25
Posts: 507

Segfault for kmixctrl 4.6 at startup

Hello,

Since a recent "pacman -Syu" I noticed in dmesg this output about kmixctrl :

[ 72.047675] kmixctrl[787]: segfault at 0 ip 0000000000000000 sp 00007ffd2a3ff0e8 error 14 in kmixctrl[5628352c9000+2000]
[ 72.047682] Code: Bad RIP value.

kmixctrl is a component from the kmix package (KDE application for the volume control) :
https://www.archlinux.org/packages/extra/x86_64/kmix/

despite this segmentation fault the kmix volume control is still working in the KDE taskbar.

You can trigger the bug by opening a console, then type "kmixctrl", you will see a line with the message "segmentation fault".

I tried to debug, the backtrace :

(gdb) backtrace
#0 0x0000000000000000 in ?? ()
#1 0x00007ffff606b2c1 in ?? () from /usr/lib/pulseaudio/libpulsecommon-13.0.so
#2 0x00007ffff606d860 in pa_socket_client_unref () from /usr/lib/pulseaudio/libpulsecommon-13.0.so
#3 0x00007ffff72c5c58 in ?? () from /usr/lib/libpulse.so.0
#4 0x00007ffff72c5d72 in ?? () from /usr/lib/libpulse.so.0
#5 0x00007ffff7f2b41d in ?? () from /usr/lib/libkmixcore.so.5
#6 0x00007ffff7f2b439 in ?? () from /usr/lib/libkmixcore.so.5
#7 0x00007ffff7f07a15 in Mixer::~Mixer() () from /usr/lib/libkmixcore.so.5
#8 0x00007ffff7f07a2a in Mixer::~Mixer() () from /usr/lib/libkmixcore.so.5
#9 0x00007ffff7f012e7 in MixerToolBox::deinitMixer() () from /usr/lib/libkmixcore.so.5
#10 0x0000555555556796 in ?? ()
#11 0x00007ffff74dc152 in __libc_start_main () from /usr/lib/libc.so.6
#12 0x000055555555683e in ?? ()

Am I alone with this bug ?

Thanks

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#2 2020-08-22 20:33:31

GeorgeJP
Member
From: Czech Republic
Registered: 2020-01-28
Posts: 35

Re: Segfault for kmixctrl 4.6 at startup

+1

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#3 2020-08-22 20:36:29

Potomac
Member
Registered: 2011-12-25
Posts: 507

Re: Segfault for kmixctrl 4.6 at startup

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#4 2020-08-22 20:36:46

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 10,831

Re: Segfault for kmixctrl 4.6 at startup

No I've seen it as well, but I'm not using it actively anymore so I haven't investigated much, I'm using plasma-pa which doesn't share much code with kmix afaik...

However this made me curious enough, so if you actually start kmix, which in and of itself does work properly, you can go into it's settings and there's an option to disable restoring volumes (which I'm assuming is referring to the kmixctrl segfaulting here) and that one is accompanied by a message that it doesn't restore pulseaudio volumes anyway, so this seems to have been a  noop either way.

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#5 2020-08-22 20:43:50

Potomac
Member
Registered: 2011-12-25
Posts: 507

Re: Segfault for kmixctrl 4.6 at startup

Note that I followed the wiki for the sound applet, we have the choice between the plasma-pa package, and kmix package, both do the job without problem for volume sound control (except recently this crash for kmixctrl at startup) :

Sound applet in the system tray

Install plasma-pa or kmix (start Kmix from the Application Launcher). plasma-pa is now installed by default with plasma, no further configuration needed.

https://wiki.archlinux.org/index.php/KD … ystem_tray

Kmix is still not deprecated and it seems to be in active development.
https://invent.kde.org/multimedia/kmix/activity

Last edited by Potomac (2020-08-22 20:47:20)

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#6 2020-08-22 20:58:26

Potomac
Member
Registered: 2011-12-25
Posts: 507

Re: Segfault for kmixctrl 4.6 at startup

V1del wrote:

However this made me curious enough, so if you actually start kmix, which in and of itself does work properly, you can go into it's settings and there's an option to disable restoring volumes (which I'm assuming is referring to the kmixctrl segfaulting here) and that one is accompanied by a message that it doesn't restore pulseaudio volumes anyway, so this seems to have been a  noop either way.

Yes there is a warning message when I go in the option panel of kmix,
the language I use is "french", so I made a translation in english :

The volume of the dynamic controls of “PulseAudio” and “MPRIS2” will not be restored.

So the workaround is to disable "restoring volumes" option, if really the disable of this option will not break other things.

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#7 2020-10-15 21:43:59

MountainX
Member
Registered: 2016-02-08
Posts: 205

Re: Segfault for kmixctrl 4.6 at startup

Potomac wrote:

So the workaround is to disable "restoring volumes" option, if really the disable of this option will not break other things.

I am not able to find this option. Also, I am not able to remove kmix (even though I have plasma-pa 5.20.0-1 installed

error: failed to prepare transaction (could not satisfy dependencies)
:: removing kmix breaks dependency 'kmix' required by kde-multimedia-meta

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#8 2020-10-16 06:39:44

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 10,831

Re: Segfault for kmixctrl 4.6 at startup

A meta package dependency breakage is not "unable to remove", that happens when removing a member of the meta package, use groups instead and run an occasional

pacman -Syu $group --needed

to find out whether there are new interesting members if you don't want to install all members of a group.

That said, what's not clear about my post as to where to find the option? start kmix locate the relevant volume icon in your tray -> right click -> settings -> you should find the relevant checkbox

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