📄 lldt.htm
字号:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode LLDT</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LGS.htm"> LGS/LSS/LDS/LES/LFS Load Full Pointer</A><BR><B>next:</B><A HREF="LMSW.htm"> LMSW Load Machine Status Word</A><P><HR><P><H1>LLDT -- Load Local Descriptor Table Register</H1><PRE>Opcode Instruction Clocks Description0F 00 /2 LLDT r/m16 20 Load selector r/m16 into LDTR</PRE><H2>Operation</H2><PRE>LDTR := SRC;</PRE><H2>Description</H2>LLDT loads the Local Descriptor Table register (LDTR). The wordoperand (memory or register) to LLDT should contain a selector to theGlobal Descriptor Table (GDT). The GDT entry should be a Local DescriptorTable. If so, then the LDTR is loaded from the entry. The descriptorregisters DS, ES, SS, FS, GS, and CS are not affected. The LDT field in thetask state segment does not change.<P>The selector operand can be 0; if so, the LDTR is marked invalid. Alldescriptor references (except by the LAR, VERR, VERW or LSLinstructions) cause a #GP fault.<P>LLDT is used in operating system software; it is not used in applicationprograms.<H2>Flags Affected</H2>None<H2>Protected Mode Exceptions</H2>#GP(0) if the current privilege level is not 0; #GP(selector) if theselector operand does not point into the Global Descriptor Table, or if theentry in the GDT is not a Local Descriptor Table; #NP(selector) if theLDT descriptor is not present; #GP(0) for an illegal memory operandeffective address in the CS, DS, ES, FS, or GS segments; #SS(0) for anillegal address in the SS segment; #PF(fault-code) for a page fault<H2>Real Address Mode Exceptions</H2>Interrupt 6; LLDT is not recognized in Real Address Mode<H2>Virtual 8086 Mode Exceptions</H2>Same exceptions as in Real Address Mode (because the instruction isnot recognized, it will not execute or perform a memory reference)<EM><H3>Note</H3>The operand-size attribute has no effect on this instruction.</EM><P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LGS.htm"> LGS/LSS/LDS/LES/LFS Load Full Pointer</A><BR><B>next:</B><A HREF="LMSW.htm"> LMSW Load Machine Status Word</A></BODY>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -