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

Table Of Contents
Vol. 3 B-33
MODEL-SPECIFIC REGISTERS (MSRS)
83EH 2110 IA32_EXT_XAPIC_DIV_CO
NF
x2APIC Divide
Configuration Register.
(R/W)
If (
CPUID.01H:ECX.[
bit 21] = 1 )
83FH 2111 IA32_EXT_XAPIC_SELF_IP
I
x2APIC Self IPI Register.
(W/O)
If (
CPUID.01H:ECX.[
bit 21] = 1 )
C000_
0080H
IA32_EFER Extended Feature
Enables.
If (
CPUID.80000001
.EDX.[bit 20] or
CPUID.80000001
.EDX.[bit29])
0 SYSCALL Enable. (R/W)
Enables SYSCALL/SYSRET
instructions in 64-bit mode.
7:1 Reserved.
8 IA-32e Mode Enable. (R/W)
Enables IA-32e mode
operation.
9Reserved.
10 IA-32e Mode Active. (R)
Indicates IA-32e mode is
active when set.
11 Execute Disable Bit Enable.
(R)
63:12 Reserved
C000_
0081H
IA32_STAR System Call Target
Address. (R/W)
If
CPUID.80000001
.EDX.[bit 29] = 1
C000_
0082H
IA32_LSTAR IA-32e Mode System Call
Target Address. (R/W)
If
CPUID.80000001
.EDX.[bit 29] = 1
C000_
0084H
IA32_FMASK System Call Flag Mask.
(R/W)
If
CPUID.80000001
.EDX.[bit 29] = 1
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