Specification Update
19
Status:
For the steppings affected, see the Summary Tables of Changes.
BJ13.
FREEZE_WHILE_SMM Does Not Prevent Event From Pending PEBS
During SMM
Problem:
In general, a PEBS record should be generated on the first count of the event after the
counter has overflowed. However, IA32_DEBUGCTL_MSR.FREEZE_WHILE_SMM (MSR
1D9H, bit [14]) prevents performance counters from counting during SMM (System
Management Mode). Due to this erratum, if
1. A performance counter overflowed before an SMI
2. A PEBS record has not yet been generated because another count of the event has
not occurred
3. The monitored event occurs during SMM
then a PEBS record will be saved after the next RSM instruction.
When FREEZE_WHILE_SMM is set, a PEBS should not be generated until the event
occurs outside of SMM.
Implication:
A PEBS record may be saved after an RSM instruction due to the associated
performance counter detecting the monitored event during SMM; even when
FREEZE_WHILE_SMM is set.
Workaround:
None identified
Status:
For the steppings affected, see the Summary Tables of Changes.
BJ14.
General Protection Fault (#GP) for Instructions Greater than 15 Bytes
May be Preempted
Problem:
When the processor encounters an instruction that is greater than 15 bytes in length, a
#GP is signaled when the instruction is decoded. Under some circumstances, the #GP
fault may be preempted by another lower priority fault (e.g. Page Fault (#PF)).
However, if the preempting lower priority faults are resolved by the operating system
and the instruction retried, a #GP fault will occur.
Implication:
Software may observe a lower-priority fault occurring before or in lieu of a #GP fault.
Instructions of greater than 15 bytes in length can only occur if redundant prefixes are
placed before the instruction.
Workaround:
None identified
Status:
For the steppings affected, see the Summary Tables of Changes.
BJ15.
#GP on Segment Selector Descriptor that Straddles Canonical
Boundary May Not Provide Correct Exception Error Code
Problem:
During a #GP (General Protection Exception), the processor pushes an error code on to
the exception handler's stack. If the segment selector descriptor straddles the
canonical boundary, the error code pushed onto the stack may be incorrect.
Implication:
An incorrect error code may be pushed onto the stack. Intel has not observed this
erratum with any commercially available software.
Workaround:
None identified
Status:
For the steppings affected, see the Summary Tables of Changes.
