February, 2007
PCI Express Enhanced Configuration Mechanism
Because the PCI r2.3-Compatible Configuration mechanism is limited to the first 256 bytes of the PCI
Express Configuration Space of the PEX 8532 ports, the PCI Express Enhanced Configuration
mechanism (described in Section 11.4.2) or PLX-Specific Memory-Mapped Configuration mechanism
(described in Section 11.4.3) must be used to access beyond byte FFh. The PCI Express Enhanced
Configuration mechanism can access the registers in the PCI-compatible region, as well as those in the
PCI Express Extended Configuration space that are defined by PCI Express specifications; however, it
generally cannot access the PEX 8532 device-specific registers above 100h. The PLX-Specific
Memory-Mapped Configuration mechanism can access all PEX 8532 registers.
11.4.2
PCI Express Enhanced Configuration Mechanism
The PCI Express Enhanced Configuration mechanism is implemented on all PCI Express PCs and on
systems that do not implement a processor-specific firmware interface to the Configuration space,
providing a Memory-Mapped Address space in the Root Complex through which the Root Complex
translates a Memory access into one or more Configuration requests. Device drivers normally use an
application programming interface (API) provided by the Operating System, to use the PCI Express
Enhanced Configuration mechanism.
The PCI Express Enhanced Configuration mechanism is used to access the PEX 8532 port Type 1
(PCI-to-PCI Bridge) registers that are defined by PCI Express specifications:
• Configuration Header Registers
• Power Management Capability Registers
• Message Signaled Interrupt Capability Registers
• PCI Express Capability Registers
• Device Serial Number Extended Capability Registers
• Power Budgeting Extended Capability Registers
• Virtual Channel Extended Capability Registers
• Advanced Error Reporting Capability Registers
The PEX 8532 device-specific registers that exist in the PCI Express Extended Configuration space
(above 100h) generally cannot be accessed by the PCI Express Enhanced Configuration mechanism.
The PLX-Specific Memory-Mapped Configuration mechanism (described in Section 11.4.3) can access
all PEX 8532 registers.
ExpressLane PEX 8532AA/BA/BB/BC 8-Port/32-Lane Versatile PCI Express Switch Data Book
Copyright © 2007 by PLX Technology, Inc. All Rights Reserved – Version 1.6
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