Recently configured a new 2.6.20 kernel and found that sound for Chromium B.S.U. no longer worked. The weird part was I couldn’t find any other applications that were affected. Chromium is the only game I have that uses OpenAL, so the kernel option I missed probably broke it.

ebrake@laptop /boot $ diff -u ./config-2.6.20.3 ./config-2.6.20-gentoo-r4.old |grep SND
CONFIG_SND=y
CONFIG_SND_TIMER=y
-CONFIG_SND_PCM=y
+CONFIG_SND_PCM=m
CONFIG_SND_SEQUENCER=y
# CONFIG_SND_SEQ_DUMMY is not set
CONFIG_SND_OSSEMUL=y
CONFIG_SND_MIXER_OSS=y
-CONFIG_SND_PCM_OSS=y
-CONFIG_SND_PCM_OSS_PLUGINS=y
+# CONFIG_SND_PCM_OSS is not set
CONFIG_SND_SEQUENCER_OSS=y
-CONFIG_SND_RTCTIMER=m
+CONFIG_SND_RTCTIMER=y
CONFIG_SND_SEQ_RTCTIMER_DEFAULT=y
# CONFIG_SND_DYNAMIC_MINORS is not set
CONFIG_SND_SUPPORT_OLD_API=y
-# CONFIG_SND_VERBOSE_PROCFS is not set
+CONFIG_SND_VERBOSE_PROCFS=y

Normally, I compile most of ALSA into the kernel including most options for OSS emulation. Here is the pertinent part of the working config.

CONFIG_SND=y
CONFIG_SND_TIMER=y
CONFIG_SND_PCM=y
CONFIG_SND_SEQUENCER=y
# CONFIG_SND_SEQ_DUMMY is not set
CONFIG_SND_OSSEMUL=y
CONFIG_SND_MIXER_OSS=y
CONFIG_SND_PCM_OSS=y
CONFIG_SND_PCM_OSS_PLUGINS=y
CONFIG_SND_SEQUENCER_OSS=y
CONFIG_SND_RTCTIMER=m
CONFIG_SND_SEQ_RTCTIMER_DEFAULT=y
# CONFIG_SND_DYNAMIC_MINORS is not set
CONFIG_SND_SUPPORT_OLD_API=y
# CONFIG_SND_VERBOSE_PROCFS is not set
# CONFIG_SND_VERBOSE_PRINTK is not set
# CONFIG_SND_DEBUG is not set
CONFIG_SND_AC97_CODEC=m