Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1669

SLDT—Store Local Descriptor Table Register
Opcode
0F 00 /0
0F 00 /0
Description
Stores the segment selector from the local descriptor table register (LDTR) in the
destination operand. The destination operand can be a general-purpose register or a
memory location. The segment selector stored with this instruction points to the LDT.
When the destination operand is a 32-bit register, the 16-bit segment selector is copied
into the lower 16 bits of the register and the upper 16 bits of the register are cleared to
0s. With the destination operand is a memory location, the segment selector is written
to memory as a 16-bit quantity, regardless of the operand size.
The SLDT instruction is only useful in operating-system software; however, it can be
used in application programs. Also, this instruction can only be executed in protected
mode.
Operation
IF Itanium System Environment THEN IA-32_Intercept(INST,SLDT);
DEST  LDTR(SegmentSelector);
Flags Affected
None.
Additional Itanium System Environment Exceptions
IA-32_Intercept
Protected Mode Exceptions
#GP(0)
#SS(0)
#PF(fault-code)
#AC(0)
Volume 4: Base IA-32 Instruction Reference
Instruction Description
SLDT r/m16 Stores segment selector from LDTR in r/m16
SLDT r/m32 Store segment selector from LDTR in low-order 16 bits of r/m32 ;
high-order 16 bits are undefined
SLDT results in an IA-32 Intercept
If the destination is located in a nonwritable 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 a memory operand effective address is outside the SS segment
limit.
If a page fault occurs.
If alignment checking is enabled and an unaligned memory
reference is made while the current privilege level is 3.
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