Specification Update

Errata
36 Intel
®
Xeon
®
Processor E7 v2 Product Family
Specification Update January 2015
Status: For the affected steppings, see the “Summary Table of Changes”.
CF67 LER MSRs May be Unreliable
Problem: Due to certain internal processor events, updates to the LER (Last Exception Record)
MSRs, MSR_LER_FROM_LIP (1DDH) and MSR_LER_TO_LIP (1DEH), may happen when
no update was expected.
Implication: The values of the LER MSRs may be unreliable.
Workaround: None Identified.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF68 Storage of PEBS Record Delayed Following Execution of MOV SS or STI
Problem: When a performance monitoring counter is configured for PEBS (Precise Event Based
Sampling), overflow of the counter results in storage of a PEBS record in the PEBS
buffer. The information in the PEBS record represents the state of the next instruction
to be executed following the counter overflow. Due to this erratum, if the counter
overflow occurs after execution of either MOV SS or STI, storage of the PEBS record is
delayed by one instruction.
Implication: When this erratum occurs, software may observe storage of the PEBS record being
delayed by one instruction following execution of MOV SS or STI. The state information
in the PEBS record will also reflect the one instruction delay.
Workaround: None identified.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF69 PEBS Record Not Updated When in Probe Mode
Problem: When a performance monitoring counter is configured for PEBS (Precise Event Based
Sampling), overflows of the counter can result in storage of a PEBS record in the PEBS
buffer. Due to this erratum, if the overflow occurs during probe mode, it may be
ignored and a new PEBS record may not be added to the PEBS buffer.
Implication: Due to this erratum, the PEBS buffer may not be updated by overflows that occur
during probe mode.
Workaround: None identified.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF70 Faulting MMX Instruction May Incorrectly Update x87 FPU Tag Word
Problem: Under a specific set of conditions, MMX stores (MOVD, MOVQ, MOVNTQ, MASKMOVQ)
which cause memory access faults (#GP, #SS, #PF, or #AC), may incorrectly update
the x87 FPU tag word register.
Problem: This erratum will occur when the following additional conditions are also met.
• The MMX store instruction must be the first MMX instruction to operate on x87 FPU
state (that is, the x87 FP tag word is not already set to 0x0000).
• For MOVD, MOVQ, MOVNTQ stores, the instruction must use an addressing mode
that uses an index register (this condition does not apply to MASKMOVQ).
Implication: If the erratum conditions are met, the x87 FPU tag word register may be incorrectly set
to a 0x0000 value when it should not have been modified.
Workaround: None identified.
Status: For the affected steppings, see the “Summary Table of Changes”.