> That doesn't seem right, after my experiences with SuSE. (I'l still in > the process of my first Gentoo install...) > > I have a combo CD-RW/DVD drive that uses SCSI emulation (under SuSE). I > discovered the need to turn DMA on when DVDs/VCDs wouldn't play back > correctly. (Jumpy playback...) I turned it on with their gui, and > everything worked correctly.
This is the sort of story I expected someone would offer up. Thanks for sharing. On the hardware side, of which I am more familiar, the EIDE controller needs to have DMA enabled for DMA transfers to take place across the PCI bus. It is not a given in *any* PC that I know of that this will be done by default. A driver has to be chosen and turned on for things to work this way. Historically SCSI controllers (I've designed a coupe) have *always* been DMA based so it's not an issue there since it's all the drivers know how to do. It sounds to me, from your details, that SuSE has provided a way to do this manually, thus giving you control that you don't get with hdparm when SCSI emulation is turned on. I wonder if that GUI app would be at all portable to Gentoo? > > On the flip side, when playing aroung with Fedora, SCSI emulation simply > wasn't needed. I did have problems with playback on one of the computers, > but that was tied in with the video driver I was using. (I haven't had a > chance to push the limit with Gentoo, so later on I may ask for help with > finding the right driver, but I'm still in the poking around stage.) > > So, DMA can be used, but how it's done under Gentoo is beyond me. But it > might not be needed. (With Fedora, it was a complete non-issue.) > It might not be needed, but we won't know until we can either test that DMA is working, via benchmarking or some other method. Even after we do that presumably we want a way of controlling it, so it seems we are still in search of a method for turning it on or off. Thanks! - Mark -- [EMAIL PROTECTED] mailing list
