Intel Xeon Processor LV and ULV Specification Update

Errata
40 Specification Update
the data from external memory or L2 written by another core, while the second load
will get the data straight from the WT Store.
Implication: Software that uses WB to WT memory aliasing may violate proper store ordering.
Workaround: Do not use WB to WT aliasing.
Status: For the steppings affected, see the Summary Tables of Changes.
AF70. Single Step Interrupts with Floating Point Exception Pending May Be
Mishandled
Problem: In certain circumstances, when a floating point exception (#MF) is pending during
single-step execution, processing of the single-step debug exception (#DB) may be
mishandled.
Implication: When this erratum occurs, #DB will be incorrectly handled as follows:
• #DB is signaled before the pending higher priority #MF (Interrupt 16)
• #DB is generated twice on the same instruction
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.
AF71. Non-Temporal Data Store May be Observed in Wrong Program Order
Problem: The ENTER instruction is used to create a procedure stack frame. Due to this erratum,
if execution of the ENTER instruction results in a fault, the dynamic storage area of the
resultant stack frame may contain unexpected values (i.e. residual stack data as a
result of processing the fault).
Implication: Software that uses non-temporal data without proper serialization before accessing
the non-temporal data may observe data in wrong program order.
Workaround: Software that conforms to the Intel
®
64 and IA-32 Architectures Software Developer's
Manual, Volume 3A, section ―Buffering of Write Combining Memory Locations‖ will
operate correctly.
Status: For the steppings affected, see the Summary Tables of Changes.
AF72. Fault on ENTER Instruction May Result in Unexpected Values on Stack
Frame
Problem: The ENTER instruction is used to create a procedure stack frame. Due to this erratum,
if execution of the ENTER instruction results in a fault, the dynamic storage area of the
resultant stack frame may contain unexpected values (i.e. residual stack data as a
result of processing the fault).
Implication: Data in the created stack frame may be altered following a fault on the ENTER
instruction. Please refer to "Procedure Calls For Block-Structured Languages" in IA-32
Intel
®
Architecture Software Developer’s Manual, Vol. 1, Basic Architecture, for
information on the usage of the ENTER instructions. This erratum is not expected to
occur in ring 3. Faults are usually processed in ring 0 and stack switch occurs when