Specification Update

Errata
Specification Update 75
W103. Sequential Code Fetch to Non-canonical Address May Have
Nondeterministic Results
Problem: If code sequentially executes off the end of the positive canonical address
space (falling through from address 00007fffffffffff to non- canonical
address 0000800000000000), under some circumstances the code
fetch will be converted to a canonical fetch at address
ffff800000000000.
Implication: Due to this erratum, the processor may transfer control to an
unintended address. The result of fetching code at that address is
unpredictable and may include an unexpected trap or fault, or
execution of the instructions found there.
Workaround: If the last page of the positive canonical address space is not allocated for code (4K
page at 00007ffffffff000 or 2M page at 00007fffffe00000) then the problem cannot
occur.
Status: For the steppings affected, see the Summary Tables of Changes.
W104. Power Cycle Generator Bus Transactions Will Not Be
Counted As Local Transactions
Problem: The following Bus Transaction Performance Monitor events are supposed
to count all local transactions:
• BUS_TRANS_ IO (Event: 6Ch)
• BUS_TRANS_ANY (Event: 70h)
Due to this erratum when the BUS_TRANS_IO and BUS_TRANS_ANY events with
Agent Specificity clear (Umask bit [13] =0), Power Cycle Generator events such as
hardware coordination IORead and StopGrant are not counted as local transactions.
Implication: Power cycle generator bus transactions may not be counted as local
transactions when bus transaction performance monitor events are
enabled.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.
W105. EIP May Be Incorrect after Shutdown in IA-32e Mode
Problem: When the processor is going into shutdown state the upper 32 bits of the
instruction pointer may be incorrect. This may be observed if the
processor is taken out of shutdown state by NMI#.
Implication: A processor that has been taken out of the shutdown state may have
an incorrect EIP. The only software which would be affected is
diagnostic software that relies on a valid EIP.
Workaround: None identified.