Intel CM8062101038606, E5-1600, E5-2600, E5-4600 2.5.2 Client Command Suite

Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families 31

Datasheet Volume One

Processor fan speed control is managed by comparing Digital Thermal Sensor (DTS)

thermal readings acquired via PECI against the processor-specific fan speed control

reference point, or TCONTROL. Both TCONTROL and DTS thermal readings are accessible

via the processor PECI client. These variables are referenced to a common

temperature, the TCC activation point, and are both defined as negative offsets from

that reference.

PECI-based access to the processor package configuration space provides a means for

Baseboard Management Controllers (BMCs) or other platform management devices to

actively manage the processor and memory power and thermal features. Details on the

list of available power and thermal optimization services can be found in

Section 2.5.2.6.

PECI allows read access to certain error registers in the processor MSR space and

status monitoring registers in the PCI configuration space within the processor and

downstream devices. Details are covered in subsequent sections.

PECI permits writes to certain Memory Controller RAS-related registers in the processor

PCI configuration space. Details are covered in Section 2.5.2.10.

The processor Intel® Interconnect Built In Self Test (Intel® IBIST) allows for in-field

diagnostic capabilities in the Intel® QPI and memory controller interfaces. PECI

provides a port to execute these diagnostics via its PCI Configuration read and write

capabilities in the BMC INIT mode. Refer to Section 2.5.3.7 for more details.

2.5.2 Client Command Suite

PECI command requires at least one frame check sequence (FCS) byte to ensure

reliable data exchange between originator and client. The PECI message protocol

defines two FCS bytes that are returned by the client to the message originator. The

first FCS byte covers the client address byte, the Read and Write Length bytes, and all

bytes in the write data block. The second FCS byte covers the read response data

returned by the PECI client. The FCS byte is the result of a cyclic redundancy check

(CRC) of each data block.

Ping() is a required message for all PECI devices. This message is used to enumerate

devices or determine if a device has been removed, been powered-off, etc. A Ping()

sent to a device address always returns a non-zero Write FCS if the device at the

targeted address is able to respond.

2.5.2.1.1 Command Format

The Ping() format is as follows:

Write Length: 0x00

Read Length: 0x00