Datasheet

Datasheet 21
Interfaces
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.
2.3 Direct Media Interface 2 (DMI2) / PCI Express*
Interface
Direct Media Interface 2 (DMI2) connects the processor to the Platform Controller Hub
(PCH). DMI2 is similar to a four-lane PCI Express* supporting a speed of 5 GT/s per
lane. Refer to Section 6.3 for additional details.
Note: Only DMI2 x4 configuration is supported.
2.3.1 DMI2 Error Flow
DMI2 can only generate SERR in response to errors, never SCI, SMI, MSI, PCI INT, or
GPE. Any DMI2 related SERR activity is associated with Device 0.
2.3.2 Processor / PCH Compatibility Assumptions
The processor is compatible with the PCH and is not compatible with any previous Intel
Memory Controller Hub (MCH) and Integrated Controller Hub (ICH) products.
2.3.3 DMI2 Link Down
The DMI2 link going down is a fatal, unrecoverable error. If the DMI2 data link goes to
data link down, after the link was up, then the DMI2 link hangs the system by not
allowing the link to retrain to prevent data corruption. This is controlled by the PCH.
Downstream transactions that had been successfully transmitted across the link prior
to the link going down may be processed as normal. No completions from downstream,
non-posted transactions are returned upstream over the DMI2 link after a link down
event.
2.4 Platform Environment Control Interface (PECI)
The Platform Environment Control Interface (PECI) uses a single wire for self-clocking
and data transfer. The bus requires no additional control lines. The physical layer is a
self-clocked one-wire bus that begins each bit with a driven, rising edge from an idle
level near zero volts. The duration of the signal driven high depends on whether the bit
value is a logic ‘0’ or logic ‘1’. PECI also includes variable data transfer rate established
with every message. In this way, it is highly flexible even though underlying logic is
simple.