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AMD Confidential
User Manual September 12
th
, 2008
Appendix A 223
Instruction
Supported
Mnemonic
Opcode
Description
SMSW reg64
0F 01 /4
Store the entire 64 bits of CR0 to a 64-bit
register.
SMSW mem16
0F 01 /4
Store the low 16 bits of CR0 to memory.
STI
FB
Set interrupt flag (IF) to 1.
STR reg16
0F 00 /1
Store the segment selector from the task
register to a 16-bit general-purpose
register.
STR reg32
0F 00 /1
Store the segment selector from the task
register to a 32-bit general-purpose
register.
STR reg64
0F 00 /1
Store the segment selector from the task
register to a 64-bit general-purpose
register.
STR mem16
0F 00 /1
Store the segment selector from the task
register to a 16-bit memory location.
SWAPGS
0F 01 F8
Exchange GS base with KernelGSBase MSR.
SYSCALL
0F 05
Call operating system.
SYSENTER
0F 34
Call operating system.
SYSEXIT
0F 35
Return from operating system.
SYSRET
0F 07
Return from operating system.
UD2
0F 08
Raise an invalid opcode exception.
VERR reg/mem16
0F 00 /4
Set the zero flag (ZF) to 1 if the segment
selected can be read.
VERW
0F 00 /5
Set the zero flag (ZF) to 1 if the segment
selected can be written.
WBINVD
0F 09
Write modified cache lines to main memory,
invalidate internal caches, and trigger
external cache flushes.
WRMSR
0F 30
Write EDX:EAX to the MSR specified by ECX.
Table 15-9: System Instruction Reference
A.6.3.1 INT – Interrupt to Vector
Opcode
Instruction
Description
CD
INT imm8
Interrupt to Vector.
CC
INT 3
Interrupt to Debug Vector.
Interrupt to task-gate is not implemented. An attempt to execute an interrupt to
task-gate results in a „FeatureNotImplemented‟ exception and the simulation will
be stopped.
When delivering an exception in an attempt to deliver a hardware interrupt the
simulation will not push the resume-flag (RF) onto the stack.
Always clears VM, NT, TF, and RF bits in rFLAGS.
A.6.3.2 IRET – Return from Interrupt
Opcode
Instruction
Description
CF
IRET, IRETD,
IRETQ
Return from interrupt
The simulator does not support nested task-switching using the rFLAGS nested-task bit
(NT) and the TSS back-link field. An interrupt return (IRET) to the previous task (nested-
task) will result in a „FeatureNotImplemented‟ exception and the simulation will be
stopped.