PCI Bus Numbering in a Microsoft Windows NT Environment

PCI Bus Numbering in a Microsoft Windows NT Environment 25
13UK-1200A-WWEN
Table 8. Test 1 – PCI BIOS bus detection in the ProLiant 8000
Bus
Detection
Order/
Controller
Discovery
Slot
Number
PCI Bridge/
Controller Type
- Test 1
Bus Number
Assignment
Description of PCI BIOS
Discovery Process
1st
Primary
Bus (O)
Host to PCI
Bridge
Bus 0
2nd Slot 1 Empty N/A
3rd Slot 2 Empty N/A
4th Slot 3 Empty N/A
5th Slot 4 Empty N/A
6th
Secondary
Bus (6)
Host to PCI
Bridge
Bus 6
7th
Slot 5
NC3131
Bus 7
8th Slot 6 Empty N/A
9th Slot 7 Empty N/A
10th Slot 8 Empty N/A
11th
Tertiary
Bus (13)
Host to PCI
Bridge
Bus 13
12th Slot 9 Empty N/A
13th Slot 10 Empty N/A
14th
Slot 11
Smart Array
4250ES
Bus 14
The PCI BIOS assigns 0 to
the Primary Bus and
continues downstream with
the controller discovery.
Slots 1-4 are empty, no PCI
bus number assignment.
The PCI BIOS discovers the
Secondary Bus and assigns it
bus number 6.
NIC in slot 5 contains a PCI
bridge and the PCI BIOS
increments the PCI bus
number to 7.
Slots 6-8 are empty, no PCI
bus number assignment.
The PCI BIOS discovers the
Tertiary Bus and assigns it
bus number 13.
Slots 9 and 10 are empty, no
PCI bus number assignment.
Intelligent drive array
controller with PCI bridge is
detected in slot 11. The PCI
BIOS increments the PCI
number to bus 14 and assigns
it to the bridge on the
controller.
Reviewing the Test 1 Configuration – Initial Configuration
Configuration B−Test 1, illustrated in Table 8, provides an example of how the PCI BIOS
discovers controller devices and assigns bus numbers during the discovery process. As the PCI
BIOS moves through the bus detection order it looks for controller devices (not the slot numbers).
In this example, the PCI BIOS begins at the Host Bus and moves downstream assigning bus
numbers starting at bus 0 on the Primary Bus. In this scenario, no PCI devices reside on the
Primary bus, so the discovery process continues to the Secondary Bus by assigning 6 as the bus
number. The NC3131 in slot 5, a bridged device, is discovered next. The PCI BIOS assigns bus 7
to the PCI bus on the bridged controller, the last PCI controller discovered on the Secondary Bus.