INTEL
®
CELERON® PROCESSOR SPECIFICATION UPDATE
68
C87.
The FXSAVE, STOS, or MOVS Instructions May Cause a Store
Ordering Violation When Data Crosses a Page with a UC
Memory Type
Problem:
If the data from an FXSAVE, STOS, or MOVS instruction crosses a page
boundary from WB to UC memory type and this instruction is immediately
followed by a second instruction that also issues a store to memory, the final data
stores from both instructions may occur in the wrong order
.
Implication:
The impact of this store ordering behavior may vary from normal software
execution to potential software failure
.
Intel has not observed this erratum in
commercially available software.
Workaround:
FXSAVE, STOS, or MOVS data must not cross page boundary from WB to UC
memory type.
Status:
For the steppings affected, see the Summary Tables of Changes.
C88.
POPF and POPFD Instructions that Set the Trap Flag Bit May
Cause Unpredictable Processor Behavior
Problem:
In some rare cases,
POPF and POPFD instructions that set the Trap Flag (TF) bit in the
EFLAGS register (causing the processor to enter Single-Step mode) may cause
unpredictable processor behavior.
Implication:
Single step operation is typically enabled during software debug activities, not during
normal system operation.
Workaround:
There is no workaround for single step operation in commercially available software. For
debug activities on custom software, the POPF and POPFD instructions could be
immediately followed by a NOP instruction to facilitate correct execution
Status:
For the steppings affected, see the Summary Tables of Changes
C89.
Code Segment Limit Violation May Occur on 4 Gigabyte Limit
Check
Problem:
Code Segment limit violation may occur on 4 Gigabyte limit check when the
code stream wraps around in a way that one instruction ends at the last byte of
the segment and the next instruction begins at 0x0.