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76 Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families
Datasheet Volume One
2.5.6 Originator Responses
The simplest policy that an originator may employ in response to receipt of a failing
completion code is to retry the request. However, certain completion codes or FCS
responses are indicative of an error in command encoding and a retry will not result in
a different response from the client. Furthermore, the message originator must have a
response policy in the event of successive failure responses. Refer to Table 2-22 for
originator response guidelines.
Refer to the definition of each command in Section 2.5.2 for a specific definition of
possible command codes or FCS responses for a given command. The following
response policy definition is generic, and more advanced response policies may be
employed at the discretion of the originator developer.
2.5.7 DTS Temperature Data
2.5.7.1 Format
The temperature is formatted in a 16-bit, 2’s complement value representing a number
of 1/64 degrees centigrade. This format allows temperatures in a range of ±512° C to
be reported to approximately a 0.016° C resolution.
2.5.7.2 Interpretation
The resolution of the processor’s Digital Thermal Sensor (DTS) is approximately 1°C,
which can be confirmed by a RDMSR from the IA32_THERM_STATUS MSR where it is
architecturally defined. The MSR read will return only bits [13:6] of the PECI
temperature sensor data defined in Figure 2-50. PECI temperatures are sent through a
configurable low-pass filter prior to delivery in the GetTemp() response data. The
output of this filter produces temperatures at the full 1/64°C resolution even though
the DTS itself is not this accurate.
Table 2-23. Originator Response Guidelines
Response After 1 Attempt After 3 Attempts
Bad FCS Retry Fail with PECI client device error.
Abort FCS Retry Fail with PECI client device error if command was not illegal or
malformed.
CC: 0x8x Retry The PECI client has failed in its attempts to generate a response.
Notify application layer.
CC: 0x9x Abandon any further
attempts and notify
application layer
N/A
None (all 0’s) Force bus idle (drive
low) for 1 mS and retry
Fail with PECI client device error. Client may not be alive or may be
otherwise unresponsive (for example, it could be in RESET).
CC: 0x4x Pass N/A
Good FCS Pass N/A
Figure 2-50. Temperature Sensor Data Format
MSB
Upper nibble
MSB
Lower nibble
LSB
Upper nibble
LSB
Lower nibble
S x x x x x x x x x x x x x x x
Sign Integer Value (0-511) Fractional Value (~0.016)