Specification Update

Errata
Intel
®
Xeon
®
Processor E7 v2 Product Family 35
Specification Update January 2015
SAL/SAR/SHL/SHR, SHLD, SHRD, SUB, XOR, and XADD) causes a page fault or an EPT-
induced VM exit, the value saved for EFLAGS may incorrectly contain the arithmetic flag
values that the EFLAGS register would have held had the instruction completed without
fault or VM exit. For page faults, this can occur even if the fault causes a VM exit or if
its delivery causes a nested fault.
Implication: None identified. Although the EFLAGS value saved by an affected event (a page fault or
an EPT-induced VM exit) may contain incorrect arithmetic flag values, Intel has not
identified software that is affected by this erratum. This erratum will have no further
effects once the original instruction is restarted because the instruction will produce the
same results as if it had initially completed without fault or VM exit.
Workaround: If the handler of the affected events inspects the arithmetic portion of the saved
EFLAGS value, then system software should perform a synchronized paging structure
modification and TLB invalidation.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF64 B0-B3 Bits in DR6 For Non-Enabled Breakpoints May be Incorrectly Set
Problem: Some of the B0-B3 bits (breakpoint conditions detect flags, bits [3:0]) in DR6 may be
incorrectly set for non-enabled breakpoints when the following sequence happens:
1. MOV or POP instruction to SS (Stack Segment) selector;
2. Next instruction is FP (Floating Point) that gets FP assist
3. Another instruction after the FP instruction completes successfully
4. A breakpoint occurs due to either a data breakpoint on the preceding instruction or
a code breakpoint on the next instruction.
Due to this erratum a non-enabled breakpoint triggered on step 1 or step 2 may be
reported in B0-B3 after the breakpoint occurs in step 4.
Implication: Due to this erratum, B0-B3 bits in DR6 may be incorrectly set for non-enabled
breakpoints.
Workaround: Software should not execute a floating point instruction directly after a MOV SS or POP
SS instruction.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF65 MCi_Status Overflow Bit May Be Incorrectly Set on a Single Instance
of a DTLB Error
Problem: A single Data Translation Look Aside Buffer (DTLB) error can incorrectly set the
Overflow (bit [62]) in the IA32_MC2_STATUS register. A DTLB error is indicated by M
error code (bits [15:0]) appearing as binary value, 000x 0000 0001 0100, in the
MCi_Status register.
Implication: Due to this erratum, the Overflow bit in the IA32_MC2_STATUS register may not be an
accurate indication of multiple occurrences of DTLB errors. There is no other impact to
normal processor functionality.
Workaround: None identified.
Status: For the affected steppings, see the “Summary Table of Changes”.
CF66 Debug Exception Flags DR6.B0-B3 Flags May be Incorrect for Disabled
Breakpoints
Problem: When a debug exception is signaled on a load that crosses cache lines with data
forwarded from a store and whose corresponding breakpoint enable flags are disabled
(DR7.G0-G3 and DR7.L0-L3), the DR6.B0-B3 flags may be incorrect.
Implication: The debug exception DR6.B0-B3 flags may be incorrect for the load if the
corresponding breakpoint enable flag in DR7 is disabled.
Workaround: None identified.