The
optiide driver supports the OPTi 82c621, 82c568 and 82d568 IDE controllers, and provides the interface with the hardware for the
ata(4) driver.
The 0x0002 flag forces the
optiide driver to disable DMA on chipsets for which DMA would normally be enabled. This can be used as a debugging aid, or to work around problems where the IDE controller is wired up to the system incorrectly.