Extensible Firmware Interface Specification
338 12/12/00 Version 1.02
The remainder of this appendix describes how to construct a device path for three example devices
from the system in Figure C-1. The following is a list of the examples used:
• Legacy floppy
• IDE Disk
• Secondary root PCI bus with PCI to PCI bridge
Figure C-2 is a partial ACPI name space for the system in Figure C-1. Figure C-2 is based on
Figure 5-3 in the Advanced Configuration and Power Interface Specification.
Root of ACPI Name Space
\_SB - System B us Tree
IDE0 - IDE D evice
_ADR - PCI Device #, Function #
PCI0 - Root PCI Bu s
_HID & _UID - ACP I Device ID and Uniqu e ID
_CRS - Curr ent Res ources (Bus, IO, Mem ory)
PRIM - Primary IDE Channel
_ADR- Primary 0, Secondary 1
ISA0 - ISA Bridge
_ADR - PCI Device #, Function #
FLPY - Legacy Floppy
_HID - A ddres s of Flop py
PCI0 - Secondary Root PCI Bus
_HID & _UID - ACP I Device ID and Uniqu e ID
_CRS - Cu rrent Re sources (Bus, I O, Mem ory)
_HID & _UID - ACP I Devic e ID and Uniqu e ID
1
3
2Key
Device Object
1
Data Object
Example Platform
Reference
MAST - M aster ID E Devi ce
_ADR - M aster 0, Slave 1
Figure C-2. Partial ACPI Name Space for Example System
C.2 Legacy Floppy
The legacy floppy controller is contained in the SIO chip that is connected root PCI bus host bridge
chip. The root PCI host bridge chip produces PCI bus 0, and other resources that appear directly to
the processors in the system.
In ACPI this configuration is represented in the _SB, system bus tree, of the ACPI name space.
PCI0 is a child of _SB and it represents the root PCI host bridge. The SIO appears to the system to
be a set of ISA devices, so it is represented as a child of PCI0 with the name ISA0. The floppy
controller is represented by FLPY as a child of the ISA0 bus.
The EFI Device Path for the legacy floppy would contain entries for the following things:
• Root PCI Bridge. ACPI Device Path _HID PNP0A03, _UID 0. ACPI name space \_SB\PCI0
• PCI to ISA Bridge. PCI Device Path with device and function of the PCI to ISA bridge. ACPI
name space \_SB\PCI0\ISA0
• Floppy Plug and Play ID. ACPI Device Path _HID PNP0303, _UID 0. ACPI name space
\_SB\PCI0\ISA0\FLPY
• End Device Path