sys/i386/doc/sound.doc

To enable sound card support, you need to add one or more of the following
lines to your kernel configuration file:

device snd5 at isa? port 0x330 irq 6 drq 0 vector mpuintr
device snd4 at isa? port 0x220 irq 15 drq 6 vector gusintr
device snd3 at isa? port 0x388 irq 12 drq 3 vector pasintr
device snd2 at isa? port 0x220 irq 7 drq 1 vector sbintr
device snd1 at isa? port 0x388 irq 0 drq 0 vector sbintr

      Unit numbers are:
                1 for Yamaha FM synth
                2 for SB/SB Pro DSP
                3 for PAS PCM and Midi
                4 for GUS
                5 for MPU-401

      If you have ProAudioSpectrum, uncomment units 3, 2 and 1
      If you have SoundBlaster, uncomment 2 and 1.
      If you have GravisUltrasound, uncomment 4
      If you have MPU-401, uncomment 5

NOTE:  The MPU-401 driver may or may not work, and is unfortunately
unverifiable since no one I know has one.  If you can test this,
please let me know!     - Jordan Hubbard (jkh@freefall.cdrom.com)