Intel E6600 Specification Update - Page 55

Errata Workaround: None identified. Status: For the steppings affected, see the Summary Tables of Changes. AI94. Performance Monitoring Counter MACRO_INSTS.DECODED May Not Count Some Decoded Instructions Problem: MACRO_INSTS.DECODED performance monitoring counter (Event 0AAH, Umask 01H) counts the number of macro instructions decoded, but not necessarily retired. The event is undercounted when the decoded instructions are a complete loop iteration that is decoded in one cycle and the loop is streamed by the LSD (Loop Stream Detector), as described in the Optimizing the Front End section of the Intel® 64 and IA-32 Architectures Optimization Reference Manual. Implication: The count value returned by the performance monitoring counter MACRO_INST.DECODED may be lower than expected. The degree of undercounting is dependent on the occurrence of loop iterations that are decoded in one cycle and whether the loop is streamed by the LSD while the counter is active. Workaround: None identified. Status: For the steppings affected, see the Summary Tables of Changes. AI95. The Stack Size May be Incorrect as a Result of VIP/VIF Check on SYSEXIT and SYSRET Problem: The stack size may be incorrect under the following scenario: • The stack size was changed due to a SYSEXIT or SYSRET • PVI (Protected Mode Virtual Interrupts) mode was enabled (CR4.PVI == 1) • Both the VIF (Virtual Interrupt Flag) and VIP (Virtual Interrupt Pending) flags of the EFLAGS register are set Implication: If this erratum occurs the stack size may be incorrect, consequently this may result in unpredictable system behavior. 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. AI96. Performance Monitoring Event SIMD_UOP_TYPE_EXEC.MUL is Counted Incorrectly for PMULUDQ Instruction Problem: Performance Monitoring Event SIMD_UOP_TYPE_EXEC.MUL (Event select 0B3H, Umask 01H) counts the number of SIMD packed multiply micro-ops executed. The count for PMULUDQ micro-ops may be lower than expected. No other instruction is affected. Implication: The count value returned by the performance monitoring event SIMD_UOP_TYPE_EXEC.MUL may be lower than expected. The degree of Intel® Core™2 Extreme Processor X6800 and Intel® Core™2 Duo Desktop Processor E6000 and E4000 Sequence 55 Specification Update