Quote Originally Posted by ckamin
I'm sure there was a reason for DMA to be turned off by default.
I think that the reason that DMA is off by default is that it either has to be on or off. In early versions of Knoppix it was off by default, but you could turn it on and if your hardware supported it improve performance. In a recent version this changed and the default was made for DMA to be on and one had to use the nodma cheat to disable it. Unfortunately, this caused a lot more problems than it solved, and a lot of people couldn't boot at all until they discovered the nodma cheat. So we are back to the default being nodma. Maybe in a more perfect world there would be a table that Knoppix could consult at hardware detection time and turn on or off DMA as best suited for the hardware, but we are not there. So the default is nodma. We have seen, however, that some CD drives really want DMA to be on for them to work properly, even more so than hard drives.