Intel E7-4850 AT80615007449AA User Manual

Intel

®

 Xeon

®

 Processor E7-8800/4800/2800 Product Families

17

Specification Update

 September 2012

Problem:

The Intel IBIST (Interconnect Built-in Self Test) does not work in the Intel

®

 QuickPath 

Interconnect (Intel

®

 QPI) slow mode and only works at operational speed.

Implication:

The Intel IBIST does not work in Intel

®

 QPI slow mode. 

Workaround:

Do not run the Intel IBIST in slow mode. 

Status:

For the steppings affected, see the 

Problem:

The Intel

®

 QPI specification states that the physical layer initialization process needs to 

negotiate retraining parameters with a remote agent. The protocol is that agents 

should first exchange their respective retraining interval and duration as part of the link 

initialization flow. Then, each agent should compare the local and remote values and 

choose common values by selecting the shortest interval and the longest duration. This 

erratum is conveying that the described negotiation feature is not implemented in the 

processor.

Implication:

The processor does not perform the hardware based retraining parameter negotiation.

Workaround:

BIOS will need to perform the necessary computations to determine the proper 

parameters and program them into the processor.

Status:

For the steppings affected, see the 

Problem:

During Intel IBIST (Interconnect Built-in Self Test) loopback, one agent is the master 

agent while the other is the slave agent on Intel

®

 QPI. The slave should extract an Intel 

IBIST loop count from the training sequence sent by the master, and use this count to 

time its stay in the Loopck.Pattern state before returning to Loopck.Marker state. While 

the processor is operating as a slave, it does not extract this loop count and times its 

stay in the Loopck.Pattern state based on its locally programmed loop count.

Implication:

When operating as an Intel IBIST slave, the processor ignores the loop count values 

sent by the master.

Workaround:

Software needs to program the same loop count into the master and the slave.

Status:

For the steppings affected, see the 

Problem:

Quiesce master skipping the StopReq2 and the StartReq1 Intel

®

 QPI messages in the 

lock sequence will result in a system hang.

Implication:

Due to this erratum, quiesce master lock flows with no StopReq2 and StartReq1 

messages will cause a system hang.

Workaround:

StopReq2 and StartReq1 messages should not be considered optional by quiesce 

master and must be sent to the processor as part of any lock flow.

Status:

For the steppings affected, see the