How do you disable bus mastering?

How do you disable bus mastering?

Why exactly would you WANT to disable bus mastering?
The simply bus mastering control I know of is for IDE disk/CD/DVD drives for controlling Direct Memory Access. Usually via Control Panel, System, Hardware, Device Manager, IDE Controllers, Primary and Secondary, Properties, Advance Settings, you can select PIO mode to turn off DMA - but a disk will later be painfully slow.