Intel 2ND GENERATION CORE PROCESSOR FAMILY DESKTOP - SPECIFICATION UPDATE 01-2011 Specification page 27

BJ39. FP Data Operand Pointer May Be Incorrectly Calculated After an FP
Access Which Wraps a 64-Kbyte Boundary in 16-Bit Code
Problem: The FP (Floating Point) Data Operand Pointer is the effective address of the operand
associated with the last non-control FP instruction executed by the processor. If an 80-
bit FP access (load or store) occurs in a 16-bit mode other than protected mode (in
which case the access will produce a segment limit violation), the memory access
wraps a 64-Kbyte boundary, and the FP environment is subsequently saved, the value
contained in the FP Data Operand Pointer may be incorrect.
Implication: Due to this erratum, the FP Data Operand Pointer may be incorrect. Wrapping an 80-bit
FP load around a segment boundary in this way is not a normal programming practice.
Intel has not observed this erratum with any commercially available software.
Workaround: If the FP Data Operand Pointer is used in an operating system which may run 16-bit FP
code, care must be taken to ensure that no 80-bit FP accesses are wrapped around a
64-Kbyte boundary.
Status: For the steppings affected, see the Summary Tables of Changes.
BJ40. Spurious Interrupts May be Generated From the Intel® VT-d Remap
Engine
Problem: If software clears the F (Fault) bit 127 of the Fault Recording Register (FRCD_REG at
offset 0x208 in Remap Engine BAR) by writing 1b through RW1C command (Read Write
1 to Clear) when the F bit is already clear then a spurious interrupt from Intel VT-d
(Virtualization Technology for Directed I/O) Remap Engine may be observed.
Implication: Due to this erratum, spurious interrupts will occur from the Intel VT-d Remap Engine
following RW1C clearing F bit.
Workaround: None identified
Status: For the steppings affected, see the Summary Tables of Changes.
BJ41. Fault Not Reported When Setting Reserved Bits of Intel® VT-d Queued
Invalidation Descriptors
Problem: Reserved bits in the Queued Invalidation descriptors of Intel VT-d (Virtualization
Technology for Directed I/O) are expected to be zero, meaning that software must
program them as zero while the processor checks if they are not zero. Upon detection
of a non-zero bit in a reserved field an Intel VT-d fault should be recorded. Due to this
erratum the processor does not check reserved bit values for Queued Invalidation
descriptors.
Implication: Due to this erratum, faults will not be reported when writing to reserved bits of Intel
VT-d Queued Invalidation Descriptors.
Workaround: None identified
Status: For the steppings affected, see the Summary Tables of Changes.
Specification Update 27