Unconditionally reset ATAPI-CD devices during boot. Brian's notes on this:

Unconditionally reset ATAPI-CD devices during boot.  Brian's notes on this:

    1. ATAPI devices come up in an inconsistent state sometimes.  Issuing
       an ATAPI reset seems to fix this completely; normally I would see,
       most of the time, these messages:
       acd0: MODE_SENSE_BIG trying to write on read buffer
       acd0: timeout waiting for ATAPI ready
       acd0: unknown transfer phase 0x1:0x50
       acd0: timeout waiting for ATAPI ready
       <lock-up or crash>

Taken-from: Brian Feldman <green@freebsd.org>
Suggested-by: Michel Talon