BUGS
 The 
mcd hardware is  difficult to probe accurately. Historically, the 
mcd probe would accept any return values as indicating that an 
mcd drive was present.  Other devices, particularly 
ne(4) or 
we(4), would then be incorrectly claimed by the 
mcd driver.  The driver now only accepts result codes known to indicate Mitsumi-compatible CD controllers, but may reject some 
mcd hardware which  returns other result codes.
options MCD_PROMISC enables the  original promiscuous probe behaviour. Use with extreme caution.