Function Power Management
PCI Express devices are required to support power management. Consequently, several registers and related bit fields must be implemented as discussed below.
The PM Capability Register Set
The PCI-PM specification defines the PM Capability register set that is located in PCI-compatible configuration space above the configuration header. The register is one in potentially many Capability registers that are linked together via pointers. The Capability ID of the PM register set is 01h. To determine the location of the PM registers software can perform the following checks. The registers described below must be implemented by PCI Express devices:
Software checks bit 4 (Capabilities List bit) of the function's Configuration ...