After 2 years I've finally traced and fixed a problem which was preventing me from using anything after ALSA 1.0.9b !
In ALSA lib 1.0.9b: pcm/pcm_generic.c: int snd_pcm_generic_channel_info() { snd_pcm_generic_t *generic = pcm->private_data; return snd_pcm_channel_info(generic->slave, info); }
But in ALSA lib 1.0.15: pcm/pcm_generic.c: int snd_pcm_generic_channel_info() { snd_pcm_generic_t *generic = pcm->private_data; if (pcm->mmap_shadow) { /* No own buffer is required - the plugin won't change * the data on the buffer, or do safely on-the-place * conversion */ return snd_pcm_channel_info(generic->slave, info); } else { // Tim: TESTED: This is now called instead of the other one! /* Allocate own buffer */ return snd_pcm_channel_info_shm(pcm, info, -1); } }
My multi PCM consists of a plughw:0,2 and a hw:1,0 In ALSA 1.0.9b, all five PCMs ALSA creates for this arrangement create their areas with mmap(). And it works. But in ALSA 1.0.15 my hw:1,0 and its multi PCM areas are created with mmap(), and my plughw:0,2 and its PCMs areas are created with malloc(). Can't hear/record any sound from the plughw:0,2 part of the multi.
I have verified that ALSA 1.0.15 is copying the plughw:0,2 HW PCM areas to its LINEAR PCM areas, but NOT finally to its multi PCM areas. It just copies all zeros. That's the reason I hear/record no sound from the plughw:0,2 part of the multi PCM. So I reverted the function's code back to 1.0.9b and presto! It works now, the same as in ALSA 1.0.9b
So please tell me, am I missing something? Should I add something more to my .asoundrc ? I see that besides {type multi ... }, there is a {type share ...} defined. *** Does the 'share' have any use here? Can't find any docs on it.
Also: Yes, I can see now, why you made this code change. mmap() has limits, so you switched over to malloc(). Those limits force the user to use small buffers and/or reduce the number of channels created. Otherwise aplay, arecord, and jack etc complain mmap() failed. In ALSA 1.0.9b, and after my change to ALSA 1.0.15, I tried ulimit() -l, and editing /etc/security/limits.conf I quadrupled the available locked memory, but aplay, arecord etc still won't let me increase the buffer size beyond what it was BEFORE I edited limits.conf *** What am I doing wrong?
Thanks Tim.