At Tue, 17 Jun 2014 15:08:31 -0400, Brandon Yates wrote:

Interestingly strace shows the failure occurs on the open call (not dlopen)

open("/usr/lib/i386-linux-gnu/alsa-lib/libasound_module_pcm_adt_dsp.so", O_RDONLY|O_CLOEXEC) = 3

This succeeded and returned the proper fd number 3.

running ldd on my shared library shows undefined symbols that are part of libasound, for example undefined symbol: snd_pcm_ioplug_create

I wonder if I have to build the .so a different way so these can be resolved? Any advice would be greatly appreciated.

Maybe you forgot to link your shared object with -lasound -lm?

Takashi

-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Friday, June 13, 2014 8:42 AM To: Brandon Yates Cc: alsa-devel@alsa-project.org Subject: Re: [alsa-devel] Plug In Creation - aplay can't find existing .so

At Tue, 10 Jun 2014 13:55:39 -0400, Brandon Yates wrote:

...

Hello,

I am working on a new pcm plugin. At this point it is basically just a

...

Hello World plugin, to make sure I have the tools working and understand the workflow. I created a simple file which is just

basically:

...

#include <alsa/asoundlib.h> #include <alsa/pcm_external.h> SND_PCM_PLUGIN_DEFINE_FUNC(my_mod) { printf("hello world\n"); return 0; } SND_PCM_PLUGIN_SYMBOL(my_mod);

I compiled this as a shared lib named

'libasound_module_pcm_my_mod.so'

...

and copied it to '/usr/lib/i386-linux-gnu/alsa-lib/'

I edited my ~/.asoundrc to create a new device that uses this plugin. Then I try to use it with `aplay --device=my_mod_test out.pcm`

I get the error message

ALSA lib dlmisc.c:254:(snd1_dlobj_cache_get) Cannot open shared library /usr/lib/i386-linux-gnu/alsa-lib/libasound_module_pcm_my_mod.so aplay: main:682: audio open error: No such device or address

But this file actually does exist, I just copied it there.

Any idea why this happens?

Try strace to see what happens. If it fails in dlopen(), it's likely because your shared object is invalid.

Takashi