21
Specification Update
AAU12.
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.
AAU13.
General Protection (#GP) Fault May Not Be Signaled on Data Segment
Limit Violation above 4-G Limit
Problem:
In 32-bit mode, memory accesses to flat data segments (base = 00000000h) that
occur above the 4-G limit (0ffffffffh) may not signal a #GP fault.
Implication:
When such memory accesses occur in 32-bit mode, the system may not issue a #GP
fault.
Workaround:
Software should ensure that memory accesses in 32-bit mode do not occur above the
4-G limit (0ffffffffh).
Status:
For the steppings affected, see the Summary Tables of Changes.
AAU14.
LBR, BTS, BTM May Report a Wrong Address when an Exception/
Interrupt Occurs in 64-bit Mode
Problem:
An exception/interrupt event should be transparent to the LBR (Last Branch Record),
BTS (Branch Trace Store) and BTM (Branch Trace Message) mechanisms. However,
during a specific boundary condition where the exception/interrupt occurs right after
the execution of an instruction at the lower canonical boundary (0x00007FFFFFFFFFFF)
in 64-bit mode, the LBR return registers will save a wrong return address with Bits 63
to 48 incorrectly sign extended to all 1's. Subsequent BTS and BTM operations which
report the LBR will also be incorrect.
Implication:
LBR, BTS and BTM may report incorrect information in the event of an exception/
interrupt.
Workaround:
None identified.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAU15.
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 MCi_Status register. A DTLB error is indicated by MCA 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 MCi_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 steppings affected, see the Summary Tables of Changes.
Содержание G6950
Страница 4: ...Contents 4 Specification Update ...
