Arch86

Opcode	Encoding	16-bit	32-bit	64-bit	`CPUID` Feature Flag(s)	Description
`NP 0F 01 CA` `CLAC`	`zo`	Valid	Valid	Valid	`smap`	Clear the `AC` flag (alignment checking) in `EFLAGS`.
Opcode: `NP 0F 01 CA` Mnemonic: `CLAC` Encoding: `zo` Validity (16/32/64 bit): valid, valid, valid `CPUID` Feature Flag(s): `smap` Clear the `AC` flag (alignment checking) in `EFLAGS`.

Encoding

Encoding	Operand
`zo`	None

Description

The CLAC instruction clears the AC flag (alignment checking) in the EFLAGS register.

This instruction can only be executed when CPL is 0 (i.e. ring 0). Attempts to execute this instruction in less privileged rings will cause a #UD exception to be raised.

Operation

public void CLAC()
{
    EFLAGS.AC = 0;
}

Flags Affected

CF (carry flag): Unmodified.
PF (parity flag): Unmodified.
AF (auxiliary flag): Unmodified.
ZF (zero flag): Unmodified.
SF (sign flag): Unmodified.
OF (overflow flag): Unmodified.
AC (alignment check flag): Cleared.

Exceptions

Real-Address Mode

#UD

If the
LOCK
prefix is used.

Virtual-8086 Mode

#UD

If in Virtual-8086 Mode.

Protected Mode

#UD

If CPL is greater than 0.
If the LOCK prefix is used.

Compatibility Mode

#UD

If CPL is greater than 0.
If the LOCK prefix is used.

Long Mode

#UD

If CPL is greater than 0.
If the LOCK prefix is used.