Pete,

The attached patch allows my system to boot 2.4.22 successfully.

a. if the read of AC97_EXTENDED_ID fails just leave eid NULL and continue
   to fix??? no codec attached.  Here is my dmesg output for this device:

    ymfpci: YMF724 at 0xffed8000 IRQ 9
    ac97_codec: AC97 Audio codec, id: 0x8384:0x7605 (SigmaTel STAC9704)

b. change references to codec to unit in function ymf_probe_one() based on
   comments in ymfpci.h

  /*
   * Throughout the code Yaroslav names YMF unit pointer "codec"
   * even though it does not correspond to any codec. Must be historic.
   * We replace it with "unit" over time.
   * AC97 parts use "codec" to denote a codec, naturally.
   */

c. fix oops, release memory "unit" not ac97 codec which we haven't
   init'd yet.

Martin