Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

Vol. 2 3-535
INSTRUCTION SET REFERENCE, A-M
Operation
IF Instruction is LIDT
THEN
IF OperandSize
= 16
THEN
IDTR(Limit) ← SRC[0:15];
IDTR(Base) ← SRC[16:47] AND 00FFFFFFH;
ELSE IF 32-bit Operand Size
THEN
IDTR(Limit) ← SRC[0:15];
IDTR(Base) ← SRC[16:47];
FI;
ELSE IF 64-bit Operand Size (* In 64-Bit Mode *)
THEN
IDTR(Limit) ← SRC[0:15];
IDTR(Base) ← SRC[16:79];
FI;
FI;
ELSE (* Instruction is LGDT *)
IF OperandSize
= 16
THEN
GDTR(Limit) ← SRC[0:15];
GDTR(Base) ← SRC[16:47] AND 00FFFFFFH;
ELSE IF 32-bit Operand Size
THEN
GDTR(Limit) ← SRC[0:15];
GDTR(Base) ← SRC[16:47];
FI;
ELSE IF 64-bit Operand Size (* In 64-Bit Mode *)
THEN
GDTR(Limit) ← SRC[0:15];
GDTR(Base) ← SRC[16:79];
FI;
FI;
FI;
Flags Affected
None.
Protected Mode Exceptions
#UD If source operand is not a memory location.
#GP(0) If the current privilege level is not 0.