This chapter shows how to write UEFI Drivers for ATA host controllers. ATA drivers must follow all of the general design guidelines described in Chapter 4 of this guide. In addition, any ATA host controllers that are PCI controllers must also follow the PCIspecific design guidelines described in Chapter 18. This section covers the guidelines that apply specifically to the management of ATA host controllers. ATA drivers, especially those for RAID controllers, may include HII functionality for ATA subsystem configuration settings. HII functionality is described in Chapter 12 of this guide.