Compaq ProLiant 1000 PCI Bus Numbering in a Microsoft Windows NT Environment - Page 48

PCI Bus Numbering in a Microsoft Windows NT Environment 48 Table 15. Test 1 - PCI BIOS bus detection in the ProLiant 6000 and 7000 servers Bus Detection Order/ Controller Discovery 1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th 11th 12th 13th Slot Number Primary Bus (0) Slot 1 (EISA) Slot 2 (EISA) Slot 3 Slot 4 Slot 5 Slot 6 Secondary Bus (2) Slot 7 Slot 8 Slot 9 Slot 10 Slot 11 PCI Bridge/ Controller Type - Test 1 Bus Number Assignment Host to PCI Bus Bridge N/A Bus 0 N/A N/A N/A Netelligent 10/100 TX Empty Empty SMART-2/SL Drive Array Host to PCI Bus bridge Empty SMART-2/SL Drive Array Empty Bus 0 N/A N/A Bus 1 Bus 2 N/A Bus 3 N/A Netelligent Dual 10/100 TX Empty Bus 4 N/A Description of PCI BIOS Discovery Process The PCI BIOS assigns 0 to the Primary Bus and continues downstream with the controller discovery. The NIC in slot 3 does not contain a PCI bridge device, it assumes the bus number of the bus where it resides, which in this case is bus 0. It is the first network controller detected by the PCI BIOS. Intelligent drive array controller with PCI bridge is detected in slot 6. The PCI BIOS increments the PCI number to bus 1 and assigns it to the bridge on the controller. The PCI BIOS discovers the Secondary Bus and assigns it bus number 2. Intelligent drive array controller (a PCI bridge device) detected in slot 8. The PCI BIOS increments the PCI bus number to 3 and assigns the bus number to the bridge on the controller. NIC in slot 10 contains a PCI bridge and the PCI BIOS increments the PCI bus number to 4. Slot 11 is empty, no PCI bus number assignment. Reviewing the Test 1 Configuration - Initial Configuration Configuration B−Test 1, illustrated in Table 15, 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. If the PCI BIOS detects a PCI device and it does not contain a bridge it receives the bus number assignment of the bus on which it resides. In this scenario, the Netelligent 10/100 TX Controller in slot 3 does not contain a bridge so it receives a bus assignment of bus 0. The PCI BIOS continues to search for the next device on the Primary Bus. The SMART-2/SL Drive Array Controller in slot 6, a bridged device, is discovered next. The PCI BIOS assigns bus 1 to the PCI bus on the bridged controller. This is the last PCI controller discovered on the Primary Bus. At this point, the PCI BIOS discovery process continues to the Secondary Bus where it increments the bus assignment to 2. The controllers detected later in the discovery order on the Secondary Bus (slots 8 and 10) both contain PCI bridges. Bus number assignments are made to the PCI buses on these controllers. The SMART-2/SL Drive Array controller in slot 8 is assigned bus 3 and the Netelligent Dual 10/100 TX controller in slot 10 is assigned bus 4. Empty slots are ignored, because they do not contain PCI devices. 13UK-1200A-WWEN