Intel E5310 Specification Update - Page 19

Implication: The value observed for performance monitoring count for saturating SIMD instructions retired may be too high. The size of the error is dependent on the number of occurrences of the conditions described above, while the counter is active. Workaround: None Identified. Status: For the steppings affected, see the Summary Tables of Changes. AJ6. SYSRET May Incorrectly Clear RF (Resume Flag) in the RFLAGS Register Problem: In normal operation, SYSRET will restore the value of RFLAGS from R11 (the value previously saved upon execution of the SYSCALL instruction). Due to this erratum, the RFLAGS.RF bit will be unconditionally cleared after execution of the SYSRET instruction. Implication: The SYSRET instruction can not be used if the RF flag needs to be set after returning from a system call. Intel has not observed this erratum with any commercially available software. Workaround: Use the IRET instruction to return from a system call, if RF flag has to be set after the return. Status: For the steppings affected, see the Summary Tables of Changes. AJ7. 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. AJ8. 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 serviced immediately after the STI instruction is executed. 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. AJ9. 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. Intel® Xeon® Processor 5300 Series 19 Specification Update, December 2010