Intel E3-1285L v3 CM8064601466804 User Manual

PCI-PCI 

Bridge 

representing 

root PCI 

Express ports 

(Device 1 and 

Device 6)

PCI 

Compatible 

Host Bridge 

Device

(Device 0)

PCI Express* extends the configuration space to 4096 bytes per-device/function, as

compared to 256 bytes allowed by the conventional PCI specification. PCI Express*

configuration space is divided into a PCI-compatible region (that consists of the first

256 bytes of a logical device's configuration space) and an extended PCI Express*

region (that consists of the remaining configuration space). The PCI-compatible region

can be accessed using either the mechanisms defined in the PCI specification or using

the enhanced PCI Express* configuration access mechanism described in the PCI

Express* Enhanced Configuration Mechanism section.

The PCI Express* Host Bridge is required to translate the memory-mapped PCI

Express* configuration space accesses from the host processor to PCI Express*

configuration cycles. To maintain compatibility with PCI configuration addressing

mechanisms, it is recommended that system software access the enhanced

configuration space using 32-bit operations (32-bit aligned) only. See the PCI Express

Base Specification for details of both the PCI-compatible and PCI Express* Enhanced

configuration mechanisms and transaction rules.

The following figure demonstrates the PCIe* lane mapping.

Intel

®

 Xeon

®

 Processor E3-1200 v3 Product Family

Datasheet – Volume 1 of 2

June 2013

24

Order No.: 328907-001