PCI Bus Numbering in a Microsoft Windows NT Environment

PCI Bus Numbering in a Microsoft Windows NT Environment 45
13UK-1200A-WWEN
the PCI controllers discovered on each bus. In this example, the controllers do not contain
bridges. Therefore, they are assigned the same bus number as the bus on which they reside.
Configuration A – Test 2 – Adding a Device
The next example in Table 14 illustrates the PCI BIOS discovery and bus number assignment
process in the same dual-peer PCI ProLiant 6500 server. However, the configuration changes
slightly by adding a bridged PCI disk controller on the Primary Bus.
Table 14. PCI BIOS bus detection in a ProLiant 6500 – after adding a bridged controller
Bus
Detection
Order/
Controller
Discovery
Slot
Number
PCI Bridge/
Controller Type
- Test 2
Bus Number
Assignment
Description of PCI BIOS Discovery
Process
1st
Primary
Bus (0)
Host to PCI Bus
Bridge
Bus 0
2nd Slot 1 Netelligent
10/100 TX
Bus 0
3rd
Slot 2
(new device)
SMART-2/P
Drive Array
Bus 1*
4th
Secondary
Bus (1)
Host to PCI Bus
Bridge
Bus 2*
5th Slot 3 Empty N/A
6th
Slot 4
Netelligent
10/100 TX
Bus 2*
7th Slot 5 Empty N/A
8th
Slot 6 Empty N/A
9th
Slot 7
Empty
N/A
10th Slot 8 Empty N/A
The PCI BIOS discovers the Primary
Bus and assigns it bus 0.
PCI BIOS detects a NIC (no PCI
bridge) in slot 1, it is assigned the
same bus number as the PCI Bus
where it resides, and is the first
controller detected by the PCI BIOS.
Discovery process continues to PCI
slot 2. PCI BIOS detects a SMART-2
disk controller (PCI bridge device) in
slot 2, it detects the PCI bridge on the
controller and increments the bus
number to 1.
The PCI BIOS discovers the
Secondary Bus and increments the
bus number to 2. Changing the bus
number assignment from the original
configuration.
Discovery process continues to PCI
slot 3. No PCI controller detected, no
bus number assigned.
PCI BIOS detects a NIC (no PCI
bridge) in slot 4, it takes the same bus
number assignment as the Secondary
PCI Bus where it resides, bus 2.
Changing the bus number
assignment from the original
configuration.
Discovery process continues to PCI
slot 5. No PCI controller detected, no
bus number assigned.
Discovery process continues to PCI
slot 6. No PCI controller detected, no
bus number assigned.
Discovery process continues to PCI
slot 7. No PCI controller detected, no
bus number assigned.
Discovery process continues to PCI
slot 8. No PCI controller detected, no
bus number assigned.
*Bus number is different than previous configuration