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AAN89.
PECI GetTemp() Reads May Return Invalid Temperature Data in
Package C6 State
Problem:
The PECI (Platform Environment Control Interface) GetTemp() command may
occasionally return incorrect temperature data.
Implication:
The temperature data reported over PECI should always be a negative value and
represents a delta below the onset of TCC (thermal control circuit) activation, as
indicated by PROCHOT#. The PECI GetTemp() command may occasionally return
incorrect temperature data when the processor is in the package C6 state. The error
occurrence rate and returned processor temperature values are random including both
hot and cold readings. Note that this error may cause the processor to return positive
PECI temperature values that may not necessarily be indicative of a thermal event
requiring an immediate shutdown.
Workaround:
Intel recommends discarding processor temperature values less than -100 or greater
than 0, and the use of appropriate temperature smoothing filters in the range -100 to 0
to minimize fan speed fluctuations, if any, due to these errors. Intel does not
recommend initiating system shutdown solely based on PECI readings. For systems
using the PECI temperature data to facilitate system shutdown, Intel recommends
initiating a shutdown only if a PECI value of 0 is returned over three consecutive PECI
temperature reads.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAN90.
PECI PCIConfigRd() Followed by a GetTemp() May Cause System Hang
in Package C6 State
Problem:
The PECI (Platform Environment Control Interface) PCIConfigRd() command
immediately followed by a PECI GetTemp() command may result in a system hang.
Implication:
When the processor is in the package C6 state, a PECI PCIConfigRd() command
immediately followed by a GetTemp() command may result in a system hang. If
PCIConfigRd() is never used, then this erratum will not be observed.
Workaround:
A PCIConfigWr() command should be issued in between PCIConfigRd() and GetTemp()
commands. The PCIConfigWr() command may be issued to any valid PECI writable CSR
address, including a benign CSR address such as 0x23058.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAN91.
PECI Mailbox Commands During Package C6 Idle State Transitions
May Result in Unpredictable Processor Behavior
Problem:
If a PECI (Platform Environment Control Interface) mailbox command is executed at
the same time that the processor is entering or exiting the package C6 idle state,
unpredictable processor behavior or an incorrect mailbox response may result.
Implication:
The PECI mailbox commands are not reliable during processor package C6 idle state
and may result in unpredictable processor behavior or incorrect PECI responses.
Workaround:
It is possible for the BIOS to contain a workaround for this erratum. This workaround
involves disabling PECI mailbox functions during package C6 idle state causing the
processor to miss responding to requests during this time. The workaround may also
result in PECI mailbox completion code responses of 0x85 ("Mailbox is Idle - no data
available") when executed during normal active operating conditions.
Status:
For the steppings affected, see the Summary Tables of Changes.
Specification Update
43
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