## ALP Programming Guide and Reference

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### Description

The LLDT instruction loads the Local Descriptor Table register (LDTR). The word operand (memory or register) to the LLDT instruction should contain a selector to the Global Descriptor Table (GDT). The GDT entry should be a Local Descriptor Table. If so, then the LDTR is loaded from the entry. The descriptor registers DS, ES, SS, FS, GS, and CS are not affected. The LDT field in the task state segment does not change.

The selector operand can be 0; if so, the LDTR is marked invalid. All descriptor references (except by the LAR, VERR, VERW or LSL instructions) cause a #GP fault.

The LLDT instruction is used in operating system software; it is not used in application programs.