DMA on optical drive

[Michael Klinosky]

I've been trying to trobleshoot a problem with optical disk drives on 3 
computers (all FC6, all different brands of drives) - they won't burn 
CDs. Actually, I had this with FC5 and SUSE 10.0 also.

With a bit of research (on bugzilla), I have the notion that it might be 
due to DMA.

How do I turn off DMA to a particular drive?

Is there a possibility that the drives can't do DMA? Or that they need 
to be configured?