Specification Update

Errata
38 Intel
®
Xeon
®
Processor E7 v2 Product Family
Specification Update January 2015
• Enhanced Intel SpeedStep® Technology
• T-state (Thermal Monitor states)
• S1-state (ACPI package sleep state)
• C1E (Enhanced C1 Low Power state)
• Adaptive Thermal Throttling
Implication: When the LBRs, BTM or BTS are enabled, some records may have incorrect branch
“From” addresses for the first branch after a transition of Enhanced Intel SpeedStep
Technology, T-states, S-states, C1E, or Adaptive Thermal Throttling.
Workaround: None identified.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF76 FP Data Operand Pointer May Be Incorrectly Calculated After an FP
Access Which Wraps a 4-Gbyte Boundary in Code That Uses 32-Bit
Address Size in 64-bit Mode
Problem: The FP (Floating Point) Data Operand Pointer is the effective address of the operand
associated with the last non-control FP instruction executed by the processor. If an
80-bit FP access (load or store) uses a 32-bit address size in 64-bit mode and the
memory access wraps a 4-Gbyte boundary and the FP environment is subsequently
saved, the value contained in the FP Data Operand Pointer may be incorrect.
Implication: Due to this erratum, the FP Data Operand Pointer may be incorrect. Wrapping an 80-bit
FP load around a 4-Gbyte boundary in this way is not a normal programming practice.
Intel has not observed this erratum with any commercially available software.
Workaround: If the FP Data Operand Pointer is used in a 64-bit operating system which may run code
accessing 32-bit addresses, care must be taken to ensure that no 80-bit FP accesses
are wrapped around a 4-Gbyte boundary
Status: For the affected steppings, see the “Summary Table of Changes”.
CF77 VMREAD/VMWRITE Instruction May Not Fail When Accessing an
Unsupported Field in VMCS
Problem: The Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2B states
that execution of VMREAD or VMWRITE should fail if the value of the instruction’s
register source operand corresponds to an unsupported field in the VMCS (Virtual
Machine Control Structure). The correct operation is that the logical processor will set
the ZF (Zero Flag), write 0CH into the VM-instruction error field and for VMREAD leave
the instruction’s destination operand unmodified. Due to this erratum, the instruction
may instead clear the ZF, leave the VM-instruction error field unmodified and for
VMREAD modify the contents of its destination operand.
Implication: Accessing an unsupported field in VMCS will fail to properly report an error. In addition,
VMREAD from an unsupported VMCS field may unexpectedly change its destination
operand. Intel has not observed this erratum with any commercially available software.
Workaround: Software should avoid accessing unsupported fields in a VMCS.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF78 An Unexpected PMI May Occur After Writing a Large Value to
IA32_FIXED_CTR2
Problem: If the fixed-function performance counter IA32_FIXED_CTR2 MSR (30BH) is configured
to generate a performance-monitor interrupt (PMI) on overflow and the counter’s value
is greater than FFFFFFFFFFC0H, then this erratum may incorrectly cause a PMI if
software performs a write to this counter.
Implication: A PMI may be generated unexpectedly when programming IA32_FIXED_CTR2. Other
than the PMI, the counter programming is not affected by this erratum as the
attempted write operation does succeed.