Specification Update

Errata
Intel
®
Xeon
®
Processor E7 v2 Product Family 41
Specification Update January 2015
Status: For the affected steppings, see the “Summary Table of Changes”.
CF88 Processor May Livelock During On Demand Clock Modulation
Problem: The processor may livelock when (1) a processor thread has enabled on demand clock
modulation via bit 4 of the IA32_CLOCK_MODULATION MSR (19AH) and the clock
modulation duty cycle is set to 12.5% (02H in bits 3:0 of the same MSR), and (2) the
other processor thread does not have on demand clock modulation enabled and that
thread is executing a stream of instructions with the lock prefix that either split a cache
line or access UC memory.
Implication: Program execution may stall on both threads of the core subject to this erratum.
Workaround: This erratum will not occur if clock modulation is enabled on all threads when using on
demand clock modulation or if the duty cycle programmed in the
IA32_CLOCK_MODULATION MSR is 18.75% or higher.
Status: For the affected steppings, see the Tab le 1, “ Sum m ary Ta bl e o f Cha n ge s”.
CF89 Performance Monitor Counters May Produce Incorrect Results
Problem: When operating with SMT enabled, a memory at-retirement performance monitoring
event (from the list below) may be dropped or may increment an enabled event on the
corresponding counter with the same number on the physical core’s other thread rather
than the thread experiencing the event. Processors with SMT disabled in BIOS are not
affected by this erratum.
The list of affected memory at-retirement events is as follows:
• MEM_UOP_RETIRED.LOADS
• MEM_UOP_RETIRED.STORES
• MEM_UOP_RETIRED.LOCK
• MEM_UOP_RETIRED.SPLIT
• MEM_UOP_RETIRED.STLB_MISS
• MEM_LOAD_UOPS_RETIRED.HIT_LFB
• MEM_LOAD_UOPS_RETIRED.L1_HIT
• MEM_LOAD_UOPS_RETIRED.L2_HIT
• MEM_LOAD_UOPS_RETIRED.LLC_HIT
• MEM_LOAD_UOPS_MISC_RETIRED.LLC_MISS
• MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HIT
• MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_HITM
• MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_MISS
• MEM_LOAD_UOPS_LLC_HIT_RETIRED.XSNP_NONE
• MEM_LOAD_UOPS_RETIRED.LLC_MISS
• MEM_LOAD_UOPS_LLC_MISS_RETIRED.LOCAL_DRAM
• MEM_LOAD_UOPS_LLC_MISS_RETIRED.REMOTE_DRAM
• MEM_LOAD_UOPS_RETIRED.L2_MISS
Implication: Due to this erratum, certain performance monitoring event may produce unreliable
results when SMT is enabled.
Workaround: None Identified.
Status: For the affected steppings, see the “Summary Table of Changes”.