PCI Express System Architecture

Support for PCI Buses and Deadlock Avoidance

Because the PCI bus employs delayed transactions, several deadlock scenarios can develop. These deadlock avoidance rules are included in PCI Express ordering to ensure that no deadlocks occur regardless of topology. Adhering to the ordering rules prevent problems when boundary conditions develop due to unanticipated topologies (e.g., two PCI Express to PCI bridges connected across the PCI Express fabric). Refer to the MindShare book entitled PCI System Architecture, Fourth Edition (published by Addison-Wesley) for a detailed explanation of the scenarios that are the basis for the PCI ordering rules related to deadlock avoidance. Table 8-4 on page 327 lists and highlights the deadlock avoidance ordering ...