PECI Interface
62 Thermal/Mechanical Specifications and Design Guide
7.1.2.5.2 Supported Responses
The typical client response is a passing FCS, a passing Completion Code and valid data.
Under some conditions, the client’s response will indicate a failure.
7.1.2.6 Package Configuration Capabilities
Tab l e 7 -6 combines both read and write services. Any service listed as a “read” would
use the RdPkgConfig() command and a service listed as a “write” would use the
WrPkgConfig() command. Note that PECI requests for memory temperature or other
data generated outside the processor package do not trigger special polling cycles on
the processor memory or SMBus interfaces to procure the required information.
7.1.2.6.1 DRAM Thermal and Power Optimization Capabilities
DRAM thermal and power optimization services provide a way for platform thermal
management solutions to program and access DRAM power, energy and temperature
parameters. Memory temperature information is typically used to regulate fan speeds,
tune refresh rates and throttle the memory subsystem as appropriate. Memory
temperature data may be derived from a variety of sources including on-die or on-
board DIMM sensors, DRAM activity information or a combination of the two. Though
memory temperature data is a byte long, range of actual temperature values are
determined by the DIMM specifications and operating range.
Note: The DRAM related PECI services described in this section apply only to the memory
connected through the SMBus to the specific processor PECI client in question and not
the overall platform memory in general.
Table 7-5. WrPkgConfig() Response Definition
Response Meaning
Bad Write FCS Electrical error or AW FCS failure
Abort FCS Invalid command formatting (mismatched RL/WL/Command Code)
CC: 0x40 Command passed, data is valid.
CC: 0x80
Response timeout. The processor was not able to generate the required response in a
timely fashion. Retry is appropriate.
CC: 0x81
Response timeout. The processor is not able to allocate resources for servicing this
command at this time. Retry is appropriate.
CC: 0x90 Unknown/Invalid Request
CC: 0x91
PECI control hardware, firmware or associated logic error. The processor is unable to
process the request.
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