Compaq 108164-003 - ProLiant - 800 Integration Notes page 28

PCI Bus Numbering in a Microsoft Windows NT Environment
Reviewing the Test 2 Configuration – Addition of Two Controllers
Configuration B Test 2, illustrated in Table 9, provides an example of how the PCI BIOS
discovers new controller devices not present in the original Test 1 configuration and how it
assigns bus numbers during the discovery process. As in Test 1, the PCI BIOS moves through the
bus detection order looking for controller devices (not slot numbers). In this example, the PCI
BIOS begins at the Host Bus and assigns bus 0 to the Primary Bus. The PCI BIOS continues to
search for the next device downstream on the Primary Bus. One bridged controller was added to
the configuration on the Primary Bus. Upon discovery of each controller, the PCI BIOS assigns a
bus number to the PCI bus on the bridged controller. Slot 2 now contains a NC3131 Fast Ethernet
NIC on bus 1. Since slot 2 contained the last PCI device on the Primary Bus, the discovery
process continues to the Secondary Bus.
The Secondary Bus is assigned a bus number of 6. The NC3131 Fast Ethernet NIC in slot 5, a
bridged device, is discovered next. The PCI BIOS assigns bus 7 to the PCI bus on the controller,
the last PCI controller discovered on the Secondary Bus.
The Tertiary Bus is assigned bus 13. The controllers downstream on the Tertiary Bus in slots 10
and 11 both contain bridges. Bus number assignments are made to the PCI buses on these bridged
controllers. The Smart Array 4250ES Controller in slot 10 is assigned bus 14 and the Smart Array
4250ES Controller in slot 11 incremented to bus 15. Empty slots are ignored, because they do not
contain PCI devices.
Comparison of Test 1 to Test 2 - Configuration B
When you reboot the server and run the System Configuration utility to view the hardware
configuration changes, it displays slot and bus number assignments. Test 2 data was recorded and
compared to Test 1.
A side-by-side comparison of the slot configurations and bus numbers of each device in Test 1 to
the slot configurations and bus numbers of each device in Test 2, illustrates what bus numbers
were changed after modifications took place.
Slot Controller
Slot 1 Empty
Slot 2 NC3131 (bridged)
Slot 3 Empty
Slot 4 Empty
Slot 5 NC3131 (bridged)
Slot 9 Empty
Slot 7 Empty
Slot 9 Empty
Slot 9 Empty
Slot 10 Smart Array 4250ES (bridged)
Slot 10 Smart Array 4250ES (bridged)
13UK-1200A-WWEN
Test 1 Test 2 Bus Assignment
N/A
$
Bus 1 - New
N/A
N/A
$ $
Bus 7 – No Change
N/A
N/A
N/A
N/A
$
Bus 14 – New
$ $
Bus 14 to 15 – Changed
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