Understanding DMA/NoDMA options and fixes

[Alan Cox]

On Llu, 2005-07-18 at 21:02 -0500, John Best wrote:
> Are there jumpers on the IDE devices that should be looked
> at/investigated?   If I hooked up devices using Cable Select vs
> physically jumpering devices to primary/secondary will it make any
> difference?   Can I tell which device or devices are responsible for the
> DMA issues?  Can I tell when buying or looking at a device whether it
> supports the proper dma standards?  Can I go to a web site or other
> location to check for compatible dma devices?

Its almost certainly a Linux problem, especially if it worked before
FC3. There are afaik no devices sold today (or in recent history) with
broken DMA. There are however limitations on some older controllers.
Those limitations haven't mysteriously changed in FC3/4 however.

Please file a bug and assign it to my work incarnation <alan at redhat...>.
Include the controller in question, lspci -v output, the devices
attached and dmesg output.

Alan