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

Table Of Contents
Vol. 3 B-7
MODEL-SPECIFIC REGISTERS (MSRS)
E7H 231 IA32_MPERF Maximum Qualified
Performance Clock Counter
(R/Write to clear)
If CPUID.06H:
ECX[0] = 1
63:0 C0_MCNT: C0 Maximum
Frequency Clock Count.
Increments at fixed interval
(relative to TSC freq.) when
the logical processor is in C0.
Cleared upon writes to
IA32_MPERF, or
overflow/wrap-around of
IA32_APERF.
E8H 232 IA32_APERF Actual Performance Clock
Counter (R/Write to clear)
If CPUID.06H:
ECX[0] = 1
63:0 C0_ACNT: C0 Actual
Frequency Clock Count.
Accumulates core clock
counts at the coordinated
clock frequency, when the
logical processor is in C0.
Cleared upon writes to
IA32_APERF, or
overflow/wrap-around of
IA32_MPERF.
FEH 254 IA32_MTRRCAP
(MTRRcap)
MTRR Capability (RO)
Section 10.11.2.1,
“IA32_MTRR_DEF_TYPE
MSR.
06_01H
7:0 VCNT: The number of
variable memory type
ranges in the processor
8 Fixed range MTRRs are
supported when set.
9Reserved
10 WC Supported when set
63:11 Reserved
174H 372 IA32_SYSENTER_CS SYSENTER_CS_MSR (R/W) 06_01H
Table B-2. IA-32 Architectural MSRs (Contd.)
Register Address Architectural MSR Name
and bit fields
(Former MSR Name) MSR/Bit Description
Introduced as
Architectural
MSR
Hex Decimal