image/svg+xml SIDT—Store Interrupt Descriptor Table Register Instruction Operand Encoding Description Stores the content the interrupt descriptor table register (IDTR) in the destination operand. The destination operand specifies a 6-byte memory location. In non-64-bit modes, the 16-bit limit field of the register is stored in the low 2 bytes of the memory location and the 32-bit base address is stored in the high 4 bytes. In 64-bit mode, the operand size fixed at 8+2 bytes. The instruction stores 8-byte base and 2-byte limit values. SIDT is only useful in operating-system software; however, it can be used in application programs without causing an exception to be generated if CR4.UMIP= 0. See “LGDT/LIDT—Load Global/Interrupt Descriptor Table Register” in Chapter 3, Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 2A , for information on loading the GDTR and IDTR. IA-32 Architecture Compatibility The 16-bit form of SIDT is compatible with the Intel 286 processor if the upper 8 bits are not referenced. The Intel 286 processor fills these bits with 1s; processor generations later than the Intel 286 processor fill these bits with 0s. Operation IF instruction is SIDT THEN IF OperandSize =16 or OperandSize = 32 (* Legacy or Compatibility Mode *) THEN DEST[0:15] := IDTR(Limit); DEST[16:47] := IDTR(Base); FI; (* Full 32-bit base address stored *) ELSE (* 64-bit Mode *) DEST[0:15] := IDTR(Limit); DEST[16:79] := IDTR(Base); (* Full 64-bit base address stored *) FI; FI; Flags Affected None. Opcode*InstructionOp/ En 64-Bit Mode Compat/ Leg Mode Description 0F 01 /1SIDT m MValidValidStore IDTR to m. Op/EnOperand 1Operand 2Operand 3Operand 4 MModRM:r/m (w)NANANA image/svg+xml Protected Mode Exceptions #GP(0)If the destination is located in a non-writable segment. If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If the DS, ES, FS, or GS register is used to access memory and it contains a NULL segment selector. If CR4.UMIP= 1 and CPL> 0. #SS(0)If a memory operand effective address is outside the SS segment limit. #PF(fault-code)If a page fault occurs. #AC(0)If alignment checking is enabled and an unaligned memory reference is made while CPL= 3. #UD If the LOCK prefix is used. Real-Address Mode Exceptions #GPIf a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. #SSIf a memory operand effective address is outside the SS segment limit. #UD If the LOCK prefix is used. Virtual-8086 Mode Exceptions #GP(0)If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. If CR4.UMIP= 1. #SS(0)If a memory operand effective address is outside the SS segment limit. #PF(fault-code)If a page fault occurs. #AC(0)If alignment checking is enabled and an unaligned memory reference is made. #UD If the LOCK prefix is used. Compatibility Mode Exceptions Same exceptions as in protected mode. 64-Bit Mode Exceptions #SS(0)If a memory address referencing the SS segment is in a non-canonical form. #UDIf the LOCK prefix is used. #GP(0)If the memory address is in a non-canonical form. If CR4.UMIP= 1 and CPL> 0. #PF(fault-code)If a page fault occurs. #AC(0)If alignment checking is enabled and an unaligned memory reference is made while CPL= 3. 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 .