Intel E6320 Specification Update - Page 32

BJ38. FP Data Operand Pointer May Be Incorrectly Calculated After an FP Access Which Wraps a 4-Gbyte Boundary in Code That Uses 32-Bit Address Size in 64-bit Mode 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 80bit FP access (load or store) uses a 32-bit address size in 64-bit mode and the memory access wraps a 4-Gbyte 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 4-Gbyte 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 a 64-bit operating system which may run code accessing 32-bit addresses, care must be taken to ensure that no 80-bit FP accesses are wrapped around a 4-Gbyte boundary. Status: For the steppings affected, see the Summary Tables of Changes. BJ39. Problem: FP Data Operand Pointer May Be Incorrectly Calculated After an FP Access Which Wraps a 64-Kbyte Boundary in 16-Bit Code 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 80bit 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 (Intel® 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. 32 Specification Update