image/svg+xml CLI — Clear Interrupt Flag Instruction Operand Encoding Description In most cases, CLI clears the IF flag in the EFLAGS register and no other flags are affected. Clearing the IF flag causes the processor to ignore maskable external interrupts. The IF flag and the CLI and STI instruction have no effect on the generation of exceptions and NMI interrupts. Operation is different in two modes defined as follows: • PVI mode (protected-mode virtual interrupts): CR0.PE= 1, EFLAGS.VM= 0, CPL= 3, and CR4.PVI= 1; • VME mode (virtual-8086 mode extensions): CR0.PE= 1, EFLAGS.VM= 1, and CR4.VME= 1. If IOPL< 3 and either VME mode or PVI mode is active, CLI clears the VIF flag in the EFLAGS register, leaving IF unaffected. Table 3-7 indicates the action of the CLI instruction depending on the processor operating mode, IOPL, and CPL. OpcodeInstructionOp/ En 64-bit Mode Compat/ Leg Mode Description FACLIZOValidValidClear interrupt flag; interrupts disabled when interrupt flag cleared. Op/EnOperand 1Operand 2Operand 3Operand 4 ZONANANANA Table 3-7. Decision Table for CLI Results ModeIOPLCLI Result Real-addressX 1 NOTES: 1. X = This setting has no effect on instruction operation. IF = 0 Protected, not PVI 2 2. For this table, “protected mode” applies whenever CR0.PE= 1 and EFLAGS.VM= 0; it includes compatibility mode and 64-bit mode. ≥ CPLIF = 0 < CPL#GP fault Protected, PVI 3 3. PVI mode and virtual-8086 mode each imply CPL= 3. 3IF = 0 0–2VIF = 0 Virtual-8086, not VME 3 3IF = 0 0–2#GP fault Virtual-8086, VME 3 3IF = 0 0–2VIF = 0 image/svg+xml Operation IF CR0.PE = 0 THEN IF := 0; (* Reset Interrupt Flag *) ELSE IF IOPL ≥ CPL(* CPL = 3 if EFLAGS.VM = 1 *) THEN IF := 0; (* Reset Interrupt Flag *) ELSE IF VME mode OR PVI mode THEN VIF := 0; (* Reset Virtual Interrupt Flag *) ELSE #GP(0); FI; FI; FI; Flags Affected Either the IF flag or the VIF flag is cleared to 0. Other flags are unaffected. Protected Mode Exceptions #GP(0) If CPL is greater than IOPL and PVI mode is not active. If CPL is greater than IOPL and less than 3. #UD If the LOCK prefix is used. Real-Address Mode Exceptions #UD If the LOCK prefix is used. Virtual-8086 Mode Exceptions #GP(0) If IOPL is less than 3 and VME mode is not active. #UD If the LOCK prefix is used. Compatibility Mode Exceptions Same exceptions as in protected mode. 64-Bit Mode Exceptions Same exceptions as in protected mode. This UNOFFICIAL reference was generated from the official Intel® 64 and IA-32 Architectures Software Developer’s Manual by a dumb script. There is no guarantee that some parts aren't mangled or broken and is distributed WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE .