[alsa-devel] unable to create IPC shm instance; SND_PCM_DIRECT_MAGIC

[Mike Bjorge]

I was wondering if anyone could explain the point of SND_PCM_DIRECT_MAGIC
and dmix->shmptr->magic?

Specifically, what it's doing in pcm_direct.c from this commit?
http://git.alsa-project.org/?p=alsa-lib.git;a=blobdiff;f=src/pcm/pcm_direct.c;h=4e2f36cd275bfda1bc3453e569cf7fb44c317ef3;hp=46664a13d0a3368527b103ff13a08f3bcfe1ddbb;hb=eafb7ae5d8fa5ee52757ee0ee9137442d2c39326;hpb=194ff97ea68d66dac8e38671cbf73d52b42f3363

I am trying to use pcm_dmix.c, but this is occasionally failing

first_instance = ret = snd_pcm_direct_shm_create_or_connect(dmix);
if (ret < 0) {
SNDERR("unable to create IPC shm instance");
goto _err;
}

because dmix->shmptr->magic is not correctly set to SND_PCM_DIRECT_MAGIC.

Thanks for any information!

-Mike