Specification Update

Errata
Specification Update 43
AN81. Performance Monitoring Event FP_MMX_TRANS_TO_MMX May Not
Count Some Transitions
Problem: Performance Monitor Event FP_MMX_TRANS_TO_MMX (Event CCH, Umask 01H)
counts transitions from x87 Floating Point (FP) to MMX™ instructions. Due to this
erratum, if only a small number of MMX instructions (including EMMS) are executed
immediately after the last FP instruction, a FP to MMX transition may not be counted.
Implication: The count value for Performance Monitoring Event FP_MMX_TRANS_TO_MMX may be
lower than expected. The degree of undercounting is dependent on the occurrences of
the erratum condition while the counter is active. 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
.
AN82. Count Value for Performance-Monitoring Counter PMH_PAGE_WALK
May Be Incorrect
Problem: Performance-Monitoring Counter PMH_PAGE_WALK is used to count the number of
page walks resulting from Data Translation Look-Aside Buffer (DTLB) and Instruction
Translation Look-Aside (ITLB) misses. Under certain conditions, this counter may be
incorrect.
Implication: There may be small errors in the accuracy of the counter.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes
.
AN83. Erratum removed