Intel AT80604004884AA User Manual

128

Intel® Xeon® Processor 7500 Datasheet, Volume 1

The GET_UNCORE_TEMP command is used to retrieve the uncore temperature from a 
target PECI address. The temperature can be used by the external thermal 
management system to regulate the temperature on the die. The data is returned as a 
negative value representing the number of degrees centigrade below the Thermal 
Control Circuit Activation temperature of the PECI device. Note that a value of zero 
represents the temperature at which the Thermal Control Circuit activates. The actual 
value that the thermal management system uses as a control set point (Tcontrol) is 
also defined as a negative number below the Thermal Control Circuit Activation 
temperature. TCONTROL may be extracted from the processor by issuing a PECI 
Mailbox MbxGet() (see 

), or using a RDMSR instruction. 

Refer to 

 for details regarding temperature data formatting.

Refer to 

 for details regarding temperature data formatting.

The GET_UNCORE_TEMP() format is as follows:

Write Length: 1

Read Length: 2

Command: 0x22

Multi-Domain Support: Yes (see 

Description: Returns the current uncore temperature for addressed processor PECI 
client.

General Sensor Error (GSE)

Thermal scan did not complete in time. Retry is appropriate.

0x0000

Processor is running at its maximum temperature or is currently being reset.

All other data

Valid temperature reading, reported as a negative offset from the TCC 

activation temperature.

Byte #

Byte 

Definition

0

Client Address

1

Write Length

0x01

2

Read Length

0x02

4

FCS

5

Temp[7:0]

6

Temp[15:8]

7

FCS

3

Cmd Code

0x22