[alsa-devel] my udev rules are breaking my dmixer setup why?

Jelle de Jong jelledejong at powercraft.nl
Wed Jul 29 12:44:37 CEST 2009

On 11/11/08 18:55, Jaroslav Kysela wrote:
> On Tue, 11 Nov 2008, Jelle de Jong wrote:
>> Jaroslav Kysela wrote:
>>> On Tue, 11 Nov 2008, Takashi Iwai wrote:
>>>>> Almost all devices can be managed with udev rules, that is where the
>>>>> system is designed for, there are also alsa rules in there, if they
>>>>> don't work what is wrong then? is it an alsa issue, or udev, what are
>>>>> the dependencies when alsa uses hardware. How are the /dev/snd/* devices
>>>>> used and what is the /proc/asound/* for ?
>>>> The card index mechanism in ALSA was introduced much before udev
>>>> was born.  It's just a legacy mechanism, but it's hard to kill without
>>>> breaking the running system, unfortunately.
>>> Note that you can identify your card via the text identification (check
>>> /proc/asound/cards to get it in []). You can set this identification in
>>> the module insert time and use for example 'hw:Intel' in your apps without
>>> bothering with indexes.
>>> The missing part is the modification of this text identification using
>>> sysfs at runtime for udev. Some time ago, I was trying to add this setup
>>> to /sys/class/sound, but the sysfs core code was not prepared for this
>>> change. I'll try to check the situation again.
>> As response to:
>> http://mailman.alsa-project.org/pipermail/alsa-devel/2008-November/012366.html
>> I am not sure if it is good practice to repose to an RFC if so please
>> tell me then we will continue the discussion in the RFC thread.
>> Thank you Jaroslav for creating the patch this is really appreciated, if
>> all things work I will send you some dutch stroopwafels :-D
>> I am just curious how you patch can be used with udev? What did you have
>> in mind?
>> Would something like this be possible:
>> SUBSYSTEM=="sound", ACTION="add" KERNELS=="3-1",
>> NAME="snd/by-id/audiodevice0"
>> SUBSYSTEM=="sound", ACTION="add" KERNELS=="3-2",
>> NAME="snd/by-id/audiodevice1"
> No, something like this:
> SUBSYSTEM=="sound", ACTION=="add", KERNEL=="controlC*", KERNELS=="3-2", \
>    ATTR{device/id}="audiodevice1"
>> pcm.!default {
>>     type plug
>>     slave.pcm dmixer
>> }
>> pcm.dmixer {
>>     type dmix
>>     ipc_key 1024
>>     slave.pcm hw:audiodevice0
>> }
> This looks OK.
> 					Jaroslav

Hello everybody,

It has been a while and I have been waiting until the patch made it into 
Debian and now it finally has, so I started testing and it seems to work 
that the patch works and I am very grateful for it.

I still have list of issues, but I will make new treads for them now.

Thanks again,

Best regards,

Jelle de Jong
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