Does ALSA now require dynamic devices (udev) for certain soundcards (specifically, cards handled by the snd-hda-intel driver)?
My problem is that I moved a Slackware installation to new hardware, and the old devices under /dev/snd I originally created back in 2003 don't seem to work correctly with snd-hda-intel. "lspci" shows my new system having two audio devices as follows:
00:1b.0 Audio device: Intel Corporation Cougar Point High Definition Audio Controller (rev 04) 01:00.1 Audio device: ATI Technologies Inc Device aa60
(The ATI entry corresponds to a DisplayPort output on a Radeon graphics card that isn't presently of interest to me: REDWOOD firmware.)
I had an opportunity to boot a modern Linux distro with udev support that accesses the Intel audio device just fine, so I took note of the device entries under /dev/snd and replicated those on the Slackware setup as follows (ignore the "root" group and 666 permissions rather than the more correct "audio" group and 660 permissions):
crw-rw-rw- 1 root root 116, 9 Mar 18 00:24 controlC0 crw-rw-rw- 1 root root 116, 12 Mar 18 00:26 controlC1 crw-rw-rw- 1 root root 116, 8 Mar 18 00:27 hwC0D2 crw-rw-rw- 1 root root 116, 7 Jun 18 2003 hwC0D3 crw-rw-rw- 1 root root 116, 11 Mar 18 00:30 hwC1D0 crw-rw-rw- 1 root root 116, 6 Mar 18 00:34 pcmC0D0c crw-rw-rw- 1 root root 116, 5 Mar 18 20:44 pcmC0D0p crw-rw-rw- 1 root root 116, 4 Mar 18 00:36 pcmC0D1p crw-rw-rw- 1 root root 116, 3 Mar 18 00:39 pcmC0D2c crw-rw-rw- 1 root root 116, 2 Mar 18 00:44 pcmC0D3p crw-rw-rw- 1 root root 116, 10 Mar 18 00:42 pcmC1D3p crw-rw-rw- 1 root root 116, 1 Jun 18 2003 seq crw-rw-rw- 1 root root 116, 33 Jun 18 2003 timer
Not all that surprisingly, the above entries work: "alsamixer" and "aplay" do what I expect and seem to work correctly.
Note that the minor device numbers are NOT the same as what the "snddevices" script in "alsa-driver-1.0.25" creates (and that script creates pretty much exactly what I had in my static /dev tree back in 2003). According to "snddevices", the "controlCn" devices should have minor numbers 0, 32, 64, etc. The "hwC0Dn" minors are 4, 5, etc., "hwC1Dn" minors are 36, 37, etc., "hwC2Dn" minors are 68, 69, etc. Note that "hwC0D3" is at minor 7 where it should be under the old minor device numbering scheme, but "hwC0D2" is at minor 8 where 6 was expected. The various "pcm*" devices were expected to be as follows:
crw-rw-rw- 1 root root 116, 24 Jun 18 2003 pcmC0D0c crw-rw-rw- 1 root root 116, 16 Mar 3 20:50 pcmC0D0p crw-rw-rw- 1 root root 116, 25 Jun 18 2003 pcmC0D1c crw-rw-rw- 1 root root 116, 17 Jun 18 2003 pcmC0D1p crw-rw-rw- 1 root root 116, 26 Jun 18 2003 pcmC0D2c crw-rw-rw- 1 root root 116, 18 Jun 18 2003 pcmC0D2p crw-rw-rw- 1 root root 116, 27 Jun 18 2003 pcmC0D3c crw-rw-rw- 1 root root 116, 19 Jun 18 2003 pcmC0D3p crw-rw-rw- 1 root root 116, 56 Jun 18 2003 pcmC1D0c crw-rw-rw- 1 root root 116, 48 Jun 18 2003 pcmC1D0p crw-rw-rw- 1 root root 116, 57 Jun 18 2003 pcmC1D1c crw-rw-rw- 1 root root 116, 49 Jun 18 2003 pcmC1D1p crw-rw-rw- 1 root root 116, 58 Jun 18 2003 pcmC1D2c crw-rw-rw- 1 root root 116, 50 Jun 18 2003 pcmC1D2p crw-rw-rw- 1 root root 116, 59 Jun 18 2003 pcmC1D3c crw-rw-rw- 1 root root 116, 51 Jun 18 2003 pcmC1D3p
I'm thinking the only reason I'm getting away with using any kind of static device scheme is that my sound devices are getting detected and initialized in a consistent order each time I boot, and the /dev/snd entries I copied from the udev-enabled system just happen to agree with what "udev" would consistently create if I had "udev" installed.
So, just to restate the original question for clarity, is "udev" required for certain soundcards?
Thanks! --Bob