Arch Linux

scusack

Member

From: Australia

Registered: 2003-11-24

Posts: 18

some udev questions

Hi all,

I have just upgraded to udev from devfs (finally), after mucking around I got it all working but I have some questions about why it is now working that weren't fully explained in the wiki or in the forums, hopefully somebody here is kind enough to confirm my guesses for me.

I was having a problem with sound, everything looked ok but no sound, so I tried as root, still no sound but at least x and gnome would start as
root.

Starting x as a user would hang on the gnome splash screen, killing x would show the error "Esound failed...".

So I check my permissions and everything was ok, but after trying to track down why /dev/snd wasn't being created I have come to the following conclusions;

1. udev is started first by rs.sysinit, at this point my sound card driver isn't loaded as the modules are loaded later in the script so at this point /sys/class/sound doesn't exist
2. other stuff comes up ok
3. the modules are loaded
4. the sound card is now listed in /sys/class/..etc.. whereas it wasn't before, but udev has already loaded so /dev/snd is not created.
5. then some other stuff happens (apache, mysqld, archstats)
6. then hotplug starts up, it looks at /sys/... finds the sound card and creates /dev/snd
7. alsamixer then resets my sound levels and everything is cool.

If I put hotplug to near the beginning of the modules list I think /sys isn't showing the sound card even tho it is loaded, after the other daemons have started it gives /sys a bit of time to get itself in order ready for hotplug.  This would explain why it was working sometimes but not others.

Does this make sense?

Regards, sim

IceRAM

Member

From: Bucharest, Romania

Registered: 2004-03-04

Posts: 772

Website

Re: some udev questions

Errr... do you usually plug & unplug your soundcard?

If not, why don't you add its module name to /etc/rc.conf and load it normally (by hand)?

P.S. you might need to run alsaconf to create some aliases in /etc/modprobe.conf, and use those aliases in /etc/rc.conf (check the end of the UDev Wiki) - this worked for me

---

:: / my web presence

slyski

Member

From: Cheese Head Land

Registered: 2004-01-11

Posts: 60

Re: some udev questions

are the snd_pcm_oss and snd_mixer_oss modules being loaded?

i had this same issue with kde and arts till those got put in rc.conf.

before i was relying on hotplug to do it for me but those modules weren't automagically being loaded

slyski

---

Joey: If a cow passes away from natural causes can I eat it.
Pheobe: Not if I get there first.

scusack

Member

From: Australia

Registered: 2003-11-24

Posts: 18

Re: some udev questions

Hi,

I don't plug/unplug the soundcard, it is a laptop, it is all working now and I am quite happy with it.  I didn't need to load the snd_pcm_oos or snd_mixer_os in modules just the snd_intel810 (or whatever it is).

My questions where really trying to clarify in my own mind how it was working and at what part of the process the various components interacted.

I guess the main assumption (on my part) that I was trying to verify is that as udev does not create dev entries when a module is probed/loaded then you need hotplug to take care of this for you.  If this is the case then the problems I was having with setting up udev makes senses, otherwise there is still something that I don't understand and I should keep researching.