DMA for CD-Drive at bootup (error)

[R.L.Reingard]

hello
with DMA enabled for the CD-Drive i always get at boot time an error like,  
this drive /dev/hdc is not known.
what can i change here? something in the bootup procedure or is the  
configuration in hdparm.conf wrong?

configuration in hdparm.conf:

/dev/hdc {
dma = on
}

thanks,
René