FNOP—No OperationDescriptionPerforms no FPU operation. This instruction takes up space in the instruction stream but does not affect the FPU or machine context, except the EIP register and the FPU Instruction Pointer.This instruction’s operation is the same in non-64-bit modes and 64-bit mode.FPU Flags AffectedC0, C1, C2, C3 undefined.Floating-Point ExceptionsNoneProtected Mode Exceptions#NMCR0.EM[bit 2] or CR0.TS[bit 3] = 1.#MF If there is a pending x87 FPU exception.#UD If the LOCK prefix is used.Real-Address Mode ExceptionsSame exceptions as in protected mode.Virtual-8086 Mode ExceptionsSame exceptions as in protected mode.Compatibility Mode ExceptionsSame exceptions as in protected mode.64-Bit Mode ExceptionsSame exceptions as in protected mode.OpcodeInstruction64-Bit ModeCompat/Leg ModeDescriptionD9 D0FNOPValidValidNo operation is performed.
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.