Specification Update

Errata
94 Specification Update
W147. Performance Monitoring Event MISALIGN_MEM_REF May Over Count
Problem: Performance monitoring event MISALIGN_MEM_REF (05H) is used to
count the number of memory accesses that cross an 8-byte boundary
and are blocked until retirement. Due to this erratum, the performance
monitoring event MISALIGN_MEM_REF also counts other memory
accesses.
Implication: The performance monitoring event MISALIGN_MEM_REF may over
count. The extent of over counting depends on the number of memory
accesses retiring while the counter is active.
Workaround: None Identified.
Status: For the steppings affected, see the Summary Tables of Changes.
W148. A REP STOS/MOVS to a MONITOR/MWAIT Address Range May
Prevent Triggering of the Monitoring Hardware
Problem: The MONITOR instruction is used to arm the address monitoring
hardware for the subsequent MWAIT instruction. The hardware is
triggered on subsequent memory store operations to the monitored
address range. Due to this erratum, REP STOS/MOVS fast string
operations to the monitored address range may prevent the actual
triggering store to be propagated to the monitoring hardware.
Implication: A logical processor executing an MWAIT instruction may prevent
program execution if a REP STOS/MOVS targets the monitored address
range.
Workaround: It is possible for BIOS to contain a workaround for this erratum. Optionally, in order to
have program execution continue immediately, REP STOS/MOVS should be prevented
from targeting the same cache line as the monitored address range.
Status: For the steppings affected, see the Summary Tables of Changes.
W149. False Level One Data Cache Parity Machine-Check Exceptions May Be
Signaled
Problem: Executing an instruction stream containing invalid
instructions/data may generate a false Level One Data Cache
parity machine-check exception
.
Implication:
The false Level One Data Cache parity machine-check exception
is reported as an uncorrected machine-check error. An
uncorrected machine-check error is treated as a fatal exception
by the operating system and may cause a shutdown and/or
reboot.
Workaround:
It is possible for the BIOS to contain a workaround for this erratum.
Status: For the steppings affected, see the Summary Tables of Changes.