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Errata
BH39
Writes to Set IA32_MCG_STATUS.MCIP Will Fail
Problem:
An MSR write that attempts to set the IA32_MCG_STATUS MSR (17AH) MCIP (machine
check in progress) bit [2] will fail (e.g. #GP fault on WRMSR) instead of setting the bit. An
MSR write that specifies 0 for the MCIP bit will function correctly.
Due to this erratum, software writes to set this bit will not succeed and may cause an unexpected
General Protection fault.
Workaround: None identified.
Status:
For the steppings affected, see the Summary Tables of Changes.
BH40
IA32_MC2_STATUS [OVERFLOW] Bit is Not Set When Single-Bit
Correctable ECC Error Occurs
Problem:
The OVERFLOW bit should be set if the VAL bit (IA32_MC2_STATUS (409H) bit [63]) is
set when a new error occurs. Due to this erratum, the OVERFLOW bit
(IA32_MC2_STATUS (409H) bit [62]) is only set when a prior uncorrected error (as
indicated by the UC bit (IA32_MC2_STATUS (409H) bit [61])) is present at the time
the second error occurs.
Any L2 correctable error will not set the IA32_MC2_STATUS.OVERFLOW bit when overwriting a prior
L2 correctable error.
Workaround: The frequency of occurrence of this problem is reduced greatly if an operating system
regularly polls and clears the machine check banks as this reduces the likelihood of an
overflow condition.
Status:
For the steppings affected, see the Summary Tables of Changes.
BH41
FP Data Operand Pointer May Be Incorrectly Calculated After an FP
Access Which Wraps a 64-Kbyte Boundary in 16-Bit Code
Problem:
The FP (Floating Point) Data Operand Pointer is the effective address of the operand
associated with the last non-control FP instruction executed by the processor. If an
80-bit FP access (load or store) occurs in a 16-bit mode other than protected mode (in
which case the access will produce a segment limit violation), the memory access
wraps a 64-Kbyte boundary, and the FP environment is subsequently saved, the value
contained in the FP Data Operand Pointer may be incorrect.
Due to this erratum, the FP Data Operand Pointer may be incorrect. Wrapping an 80-bit FP load
around a segment boundary in this way is not a normal programming practice. Intel
has not observed this erratum with any commercially available software.
Workaround: If the FP Data Operand Pointer is used in an operating system which may run 16-bit
FP code, care must be taken to ensure that no 80-bit FP accesses are wrapped around
a 64-Kbyte boundary.
Status:
For the steppings affected, see the Summary Tables of Changes.
BH42
High Temperature Circuit Marginality Issue May Cause the System to
Hang or Auto
Specification Update
29
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