Specification Update

Errata
Specification Update 89
W137. Invalid Instructions May Lead to Unexpected Behavior
Problem: Invalid instructions due to undefined opcodes or instructions exceeding the
maximum instruction length (due to redundant prefixes placed before
the instruction) may lead, under complex circumstances, to unexpected
behavior.
Implication: The processor may behave unexpectedly due to invalid instructions.
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.
W138. EFLAGS, CR0, CR4 and the EXF4 Signal May Be Incorrect
after Shutdown
Problem: When the processor is going into shutdown due to an RSM inconsistency
failure, EFLAGS, CR0 and CR4 may be incorrect. In addition the EXF4
signal may still be asserted. This may be observed if the processor is
taken out of shutdown by NMI#.
Implication: A processor that has been taken out of shutdown may have an
incorrect EFLAGS, CR0 and CR4. In addition the EXF4 signal may still
be asserted.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.
W139. Performance Monitoring Counter MACRO_INSTS.DECODED
May Not Count Some Decoded Instructions
Problem: MACRO_INSTS.DECODED performance monitoring counter (Event 0AAH,
Umask 01H) counts the number of macro instructions decoded, but not
necessarily retired. The event is undercounted when the decoded
instructions are a complete loop iteration that is decoded in one cycle
and the loop is streamed by the LSD (Loop Stream Detector), as
described in the Optimizing the Front End section of the Intel® 64 and
IA-32 Architecture Software Developer’s Manual
Implication: The count value returned by the performance monitoring counter
MACRO_INST.DECODED may be lower than expected. The degree of
undercounting is dependent on the occurrence of loop iterations that
are decoded in one cycle and whether the loop is streamed by the LSD
while the counter is active.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.