Compaq ProLiant 1000 PCI Bus Numbering in a Microsoft Windows NT Environment - Page 21

PCI Bus Numbering in a Microsoft Windows NT Environment 21 Note: Even though PCI bus numbers assign during every boot process, the number remains exactly the same as long as the configuration remains the same. Table 6. PCI BIOS bus detection in a ProLiant ML530-before adding a bridged controller Bus Detection Order/ Controller Discovery 1st 2nd Slot Number Primary Bus (O) Slot 1 PCI Bridge/ Controller Type - Test 1 Bus Number Assignment Description of PCI BIOS Discovery Process Host to PCI Bridge Empty Bus 0 N/A The PCI BIOS discovers the Primary Bus and assigns it bus 0. Discovery process continues to PCI slot 1. No PCI controller detected, no bus number assigned. 3rd Secondary Host to PCI Bus 2 Bus (2) Bridge 4th Slot 7 Empty N/A The PCI BIOS discovers the Secondary Bus and increments the bus number to 2. Discovery process continues to PCI slot 7. No PCI controller detected, no bus number assigned. 5th Slot 8 Empty N/A 6th Tertiary Host to PCI Bus 5 Bus (5) Bridge 7th Slot 6 Empty N/A Discovery process continues to PCI slot 8. No PCI controller detected, no bus number assigned. The PCI BIOS discovers the Tertiary Bus and increments the bus number to 5. Discovery process continues to PCI slots 6, 4, 3, and 2. No PCI controller detected, no bus number assigned. 8th Slot 4 Empty N/A 9th Slot 3 Empty N/A 10th Slot 2 Empty N/A 11th Slot 5 NC3132 (non- Bus 5 bridged) PCI BIOS detects a NIC (no PCI bridge) in slot 5, it is assigned the same bus number as the PCI Bus where it resides, and is the first controller detected by the PCI BIOS. Reviewing the Test 1 Configuration In Test 1, the PCI BIOS begins the discovery process by identifying buses on the Primary PCI Bus, then continues to the Secondary PCI Bus looking for PCI buses and or bridges, and completes after reaching the last slot on the Tertiary PCI bus. As each bus is detected it is assigned a bus number starting at bus 0, the PCI BIOS then assigns bus numbers to 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. Note: Bus numbers (appear in boldface type in Table 6) are assigned during bus initialization according to predefined hardware designators. The bus numbers may not appear to follow a set increment and some numbers may be skipped. However, by this method, these hardware designators prevent overlays in bus numbering from occurring. 13UK-1200A-WWEN