STUI
— Set User Interrupt Flag
| Opcode/Instruction |
Op/En |
64/32 bit Mode Support |
CPUID Feature Flag |
Description |
| F3 0F 01 EF STUI |
ZO |
V/I |
UINTR |
Set user interrupt flag. |
Instruction Operand Encoding
¶
| Op/En |
Tuple |
Operand 1 |
Operand 2 |
Operand 3 |
Operand 4 |
| ZO |
N/A |
N/A |
N/A |
N/A |
N/A |
Description
¶
STUI sets the user interrupt flag (UIF). Its effect takes place immediately; a user interrupt may be delivered on the instruction boundary following STUI. (This is in contrast with STI, whose effect is delayed by one instruction).
An execution of STUI inside a transactional region causes a transactional abort; the abort loads EAX as it would have had it been due to an execution of STI.
Operation
¶
UIF := 1;
Flags Affected
¶
None.
Protected Mode Exceptions
¶
| #UD |
The STUI instruction is not recognized in protected mode. |
Real-Address Mode Exceptions
¶
| #UD |
The STUI instruction is not recognized in real-address mode. |
Virtual-8086 Mode Exceptions
¶
| #UD |
The STUI instruction is not recognized in virtual-8086 mode. |
Compatibility Mode Exceptions
¶
| #UD |
The STUI instruction is not recognized in compatibility mode. |
64-Bit Mode Exceptions
¶
| #UD |
If the LOCK prefix is used. |
| If executed inside an enclave. |
| If CR4.UINTR = 0. |
| If CPUID.07H.0H:EDX.UINTR[bit 5] = 0. |