Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
B-2 Vol. 3
MODEL-SPECIFIC REGISTERS (MSRS)
B.1 ARCHITECTURAL MSRS
Many MSRs have carried over from one generation of IA-32 processors to the next
and to Intel 64 processors. A subset of MSRs and associated bit fields, which do not
change on future processor generations, are now considered architectural MSRs. For
historical reasons (beginning with the Pentium 4 processor), these “architectural
MSRs” were given the prefix “IA32_”. Table B-2 lists the architectural MSRs, their
addresses, their current names, their names in previous IA-32 processors, and bit
fields that are considered architectural. MSR addresses outside Table B-2 and certain
bitfields in an MSR address that may overlap with architectural MSR addresses are
model-specific. Code that accesses a machine specified MSR and that is executed on
a processor that does not support that MSR will generate an exception.
Architectural MSR or individual bit fields in an architectural MSR may be introduced or
transitioned at the granularity of certain processor family/model or the presence of
certain CPUID feature flags. The right-most column of Table B-2 provides information
on the introduction of each architectural MSR or its individual fields. This information
is expressed either as signature values of “DF_DM“ (see Table B-1) or via CPUID
flags.
Certain bit field position may be related to the maximum physical address width, the
value of which is expressed as “MAXPHYWID“ in Table B-2. “MAXPHYWID“ is reported by
CPUID.8000_0008H leaf.
0F_0H, 0F_01H Intel Xeon Processor, Intel Xeon Processor MP, Intel Pentium 4
processors
06_7H, 06_08H, 06_0AH,
06_0BH
Intel Pentium III Xeon Processor, Intel Pentium III Processor
06_03H, 06_05H Intel Pentium II Xeon Processor, Intel Pentium II Processor
06_01H Intel Pentium Pro Processor
05_01H, 05_02H, 05_04H Intel Pentium Processor, Intel Pentium Processor with MMX
Technology
Table B-1. CPUID Signature (Contd.)Values of DisplayFamily_DisplayModel (Contd.)
DisplayFamily_DisplayModel Processor Families/Processor Number Series