C-3. Secondary Root Pci Bus With Pci To Pci Bridge Device Path; C.4 Secondary Root Pci Bus With Pci To Pci Bridge - Intel Extensible Firmware Interface Specification

C.4 Secondary Root PCI Bus with PCI to PCI Bridge

The secondary PCI host bridge materializes a second set of PCI buses into the system. The PCI
buses on the secondary PCI host bridge are totally independent of the PCI buses on the root PCI
host bridge. The only relationship between the two is they must be configured to not consume the
same resources. The primary PCI bus of the secondary PCI host bridge also contains a PCI to PCI
bridge. There is some arbitrary PCI device plugged in behind the PCI to PCI bridge in a PCI slot.
In ACPI this configuration is represented in the _SB, system bus tree, of the ACPI name space.
PCI1 is a child of _SB and it represents the secondary PCI host bridge. The PCI to PCI bridge and
the device plugged into the slot on its primary bus are not described in the ACPI name space.
These devices can be fully configured by following the applicable PCI specification.
The EFI Device Path for the secondary root PCI bridge with a PCI to PCI bridge would contain
entries for the following things:
•
Root PCI Bridge. ACPI Device Path _HID PNP0A03, _UID 1. ACPI name space \_SB\PCI1
•
PCI to PCI Bridge. PCI Device Path with device and function of the PCI Bridge. ACPI name
space \_SB\PCI1, PCI to PCI bridges are defined by PCI specification and not ACPI.
•
PCI Device. PCI Device Path with the device and function of the PCI device. ACPI name
space \_SB\PCI1, PCI devices are defined by PCI specification and not ACPI.
•
End Device Path.
Table C-3. Secondary Root PCI Bus with PCI to PCI Bridge Device Path
Byte Byte
Offset Length
0 1
1 1
2 2
4 4
8 4
C 1
D 1
E 2
10 1
11 1
12 1
13 1
14 2
16 1
17 1
18 1
19 1
1A 2
Version 1.02
Data Description
0x02 Generic Device Path Header – Type ACPI Device Path
0x01 Sub type – ACPI Device Path
0x0C Length
0x41D0, _HID PNP0A03 – 0x41D0 represents a compressed string 'PNP' and is in
the low order bytes
0x0A03
0x0001 _UID
0x01 Generic Device Path Header – Type Hardware Device Path
0x01 Sub type PCI Device Path
0x06 Length
0x00 PCI Function for PCI to PCI bridge
0x0c PCI Device for PCI to PCI bridge
0x01 Generic Device Path Header – Type Hardware Device Path
0x01 Sub type PCI Device Path
0x08 Length
0x00 PCI Function for PCI Device
0x00 PCI Device for PCI Device
0xFF Generic Device Path Header – Type End Device Path
0xFF Sub type – End Device Path
0x04 Length
12/12/00
Device Path Examples
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