Specification Update

Errata
18 Specification Update
AM7 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.
AM8 Pending x87 FPU Exceptions (#MF) Following STI May Be Serviced Before
Higher Priority Interrupts
Problem: Interrupts that are pending prior to the execution of the STI (Set Interrupt Flag)
instruction are normally serviced immediately after the instruction following the STI.
An exception to this is if the following instruction triggers a #MF. In this situation, the
interrupt should be serviced before the #MF. Because of this erratum, if following STI,
an instruction that triggers a #MF is executed while STPCLK#, Enhanced Intel
SpeedStep® Technology transitions or Thermal Monitor 1 events occur, the pending
#MF may be serviced before higher priority interrupts.
Implication: Software may observe #MF being serviced before higher priority interrupts.
Workaround: None Identified.
Status: For the steppings affected, see the Summary Tables of Changes.
AM9 The Processor May Report a #TS Instead of a #GP Fault
Problem: A jump to a busy TSS (Task-State Segment) may cause a #TS (invalid TSS exception)
instead of a #GP fault (general protection exception).
Implication: Operation systems that access a busy TSS may get invalid TSS fault instead of a #GP
fault. Intel has not observed this erratum with any commercially available software.
Workaround: None Identified.
Status: For the steppings affected, see the Summary Tables of Changes.