LTR -- Load Task Register

LTR -- Load Task Register Opcode Instruction Clocks Description 0F 00 /3 LTR r/m16 pm=23/27 Load EA word into task register Description LTR loads the task register from the source register or memory location specified by the operand. The loaded task state segment is marked busy. A task switch does not occur. LTR is used only in operating system software; it is not used in application programs. Flags Affected None Protected Mode Exceptions #GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #GP(0) if the current privilege level is not 0; #GP(selector) if the object named by the source selector is not a TSS or is already busy; #NP(selector) if the TSS is marked "not present"; #PF(fault-code) for a page fault Real Address Mode Exceptions Interrupt 6; LTR is not recognized in Real Address Mode Virtual 8086 Mode Exceptions Same exceptions as in Real Address Mode Notes The operand-size attribute has no effect on this instruction.