[Pkg-alsa-devel] Bug#387171: (snd_pcm_dmix_open) unable to create IPC shm instance

[vitko at post.cz]

Hi, 

I've also encountered "(snd_pcm_dmix_open) unable to create IPC shm instance" problem.

In my case mplayer complained after upgrade:

...
alsa-init: requested format: 48000 Hz, 2 channels, 9
alsa-init: using ALSA 1.0.12
alsa-init: setup for 1/2 channel(s)
alsa-init: using device default
alsa-lib: pcm_dmix.c:846:(snd_pcm_dmix_open) unable to create IPC shm instance
alsa-init: playback open error: Invalid argument
Could not open/initialize audio device -> no sound.

Some detail on hardware

$ lspci | grep -i multi
0000:00:0a.0 Multimedia audio controller: Ensoniq ES1370 [AudioPCI] (rev 01)

and alsa

$ dpkg -l | grep alsa
ii  alsa-base                        1.0.11-2                  ALSA driver configuration files
ii  alsa-firmware-loaders            1.0.11-1                  ALSA software loaders for specific hardware
ii  alsa-oss                         1.0.11-1                  ALSA wrapper for OSS applications
ii  alsa-tools                       1.0.11-1                  Console based ALSA utilities for specific ha
ii  alsa-utils                       1.0.11-4                  ALSA utilities

Then I did 

# apt-get install alsa-base alsa-utils alsa-tools alsa-oss alsa-firmware-loaders

resulting in 

$ dpkg -l | grep alsa
ii  alsa-base                        1.0.12-1                  ALSA driver configuration files
ii  alsa-firmware-loaders            1.0.12-1                  ALSA software loaders for specific hardware
ii  alsa-oss                         1.0.12-1                  ALSA wrapper for OSS applications
ii  alsa-tools                       1.0.12-1                  Console based ALSA utilities for specific ha
ii  alsa-utils                       1.0.12-1                  ALSA utilities

After upgrade I got again

...
alsa-lib: pcm_dmix.c:846:(snd_pcm_dmix_open) unable to create IPC shm instance
...

As a last result I tried to reload alsa

$ sudo /etc/init.d/alsa unload
/etc/init.d/alsa: Warning: Processes using sound devices: 2333(mixer_applet2) 2888(xmms) 3533(xmms).
Unloading ALSA sound driver modules:.

Strange, someone using it? Let's terminate him

$ killall xmms

and now to my astonishment mplayer works fine

...
alsa-init: using device default
alsa: 47040 Hz/2 channels/4 bpf/65536 bytes buffer/Signed 16 bit Little Endian
AO: [alsa] 47040Hz 2ch s16le (2 bytes per sample)
Starting playback...
...

Observed on sporadically upgraded Sid machine (my friend is on slow dialup).

Well, I'm confused, but maybe someone can shed some light on it.