This section summarizes PCI controller requirements.
6. System-board bus complies with PCI 2.1
Required
The system-board bus hardware should comply with PCI 2.1. The bus design must fully implement all bus requirements on every expansion card connector.
7. Bus master privileges are supported for all connectors
Required
To ensure full Plug and Play functionality on a PCI bus with expansion cards, all PCI connectors on the system board must be able to allow any PCI expansion card to have bus master privileges.
8. ISA Write Data Port address is propagated to the ISA bus at power up
Required
If the system uses an ISA bus in conjunction with a PCI bridge, the Plug and Play ISA Write Data Port address must be propagated at all times through the bridge to all ISA buses that might contain external ISA Plug and Play cards. The address must be propagated at power up and system reset. This ensures that the system can identify, isolate, and configure external Plug and Play ISA cards plugged into the ISA bus during the boot process.
9. Functions in a multifunction PCI device do not share writable PCI Configuration Space bits
Required
The operating system treats each function of a multifunction PCI device as an independent device. As such, there can be no sharing between functions of writable PCI Configuration Space bits (such as the Command register).
Notice that the PC Card 16-bit Interface Legacy Mode BAR—offset 44h in the Type 2 PCI header—is the only exception to this requirement. This register must be shared between the two functions, just as they must share the same compatibility registers with the Exchangeable Card Architecture (ExCA) programming model, as defined in the PCI to PCMCIA CardBus Bridge Register Description (Yenta specification), by Intel.
For more information about design requirements for CardBus controllers, see the “PC Card” chapter in Part 3 of this guide.