* To be straightforward: System behaviour:

sappho # amixer
amixer: Mixer attach default error: No such file or directory
sappho # mpg321 -o alsa 1.Allegro.mp3
High Performance MPEG 1.0/2.0/2.5 Audio Player for Layer 1, 2, and 3.
Version 0.59q (2002/03/23). Written and copyrights by Joe Drew.
Uses code from various people. See 'README' for more!
THIS SOFTWARE COMES WITH ABSOLUTELY NO WARRANTY! USE AT YOUR OWN RISK!
Title  : Horowitz plays Tchaikovsky & B  Artist: Beethoven
Album  : Tchaikovsky: Concerto No.1/Bee  Year  : 1990
Comment: Horowitz/Reiner/Toscanini       Genre : Classical

Playing MPEG stream from 1.Allegro.mp3 ...
MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo
ALSA lib confmisc.c:558:(snd_determine_driver) could not open control for card 0
ALSA lib conf.c:2712:(snd_config_hooks_call) function snd_config_hook_load_for_all_cards returned error: No such file or directory
ALSA lib pcm.c:2014:(snd_pcm_open_conf) Invalid type for PCM default definition (id: default, value: cards.pcm.default)
ALSA snd_pcm_open error: Invalid argument
Can't find a suitable libao driver. (Is device in use?)


What I have tried to get this problem solved:

== check dmesg ==
dmesg shows:
[   26.551490] Advanced Linux Sound Architecture Driver Version
1.0.12rc1 (Thu Jun 22 13:55:50 2006 UTC).
[   26.986597] ALSA device list:
[   27.108836]   #0: Sun CS4231 at 0x1fff1200000, irq 10

Also 
sappho snd # dmesg | grep snd
[ 5250.225152] I7: <snd_pcm_lib_write_transfer+0x9c/0xc8>
[ 5250.225172] Caller[0000000000613078]: snd_pcm_lib_write_transfer+0x9c/0xc8
[ 5250.225204] Caller[00000000006133a4]: snd_pcm_lib_write1+0x300/0x43c
[ 5250.225235] Caller[0000000010026750]: snd_pcm_oss_sync+0x170/0x27c [snd_pcm_oss]
[ 5250.225307] Caller[00000000100271e4]: snd_pcm_oss_release+0x24/0x9c [snd_pcm_oss]


== check /etc/dev ==
No node with major ID = 116 exist in /etc/dev/

Try:
sappho /dev # MAKEDEV
no new node with major ID 116 created;
try
sappho /dev # MAKEDEV update
/usr/sbin/MAKEDEV: don't know what "alsa" is
/usr/sbin/MAKEDEV: don't know what "usb_device" is

My uname -a
sappho dev # uname -a
Linux sappho.realss.com 2.6.18-gentoo-r3 #11 Sun Dec 17 07:14:29 HKT
2006 sparc64 sun4u TI UltraSparc IIi (Sabre) GNU/Linux

Please point out my mistake. Thanks a lot!