Intel Extensible Firmware Interface - Manual (Page 328)

Extensible Firmware Interface Specification
10-34 12/01/02 Version 1.10
10.6 Rules for PCI/AGP Devices
In an EFI system that contains PCI or AGP devices each PCI device/function will be abstracted by
a PCI I/O protocol on a handle with its associated device path.
If the PCI device/function contains a single frame buffer the EFI_UGA_DRAW_PROTOCOL must
be placed on the same handle as the PCI I/O Protocol.
If the PCI device/function contains multiple frame buffers the UGA ROM must create child handles
of the PCI I/O protocol that inherit its device path and append a controller device path node. The
UGA ROM is responsible for creating the child handle and placing the device path protocol and
EFI_UGA_DRAW_PROTOCOL .