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THE
80286
INSTRUCTION SET
LSL-Load Segment Limit
Opcode Instruction Clocks
Description
OF
03
/r
LSL rw,ew 14,mem=16 Load:
rw
= Segment Limit, selector
ew
FLAGS MODIFIED
Zero
FLAGS UNDEFINED
None
OPERATION
If
the descriptor denoted by the selector in the second (memory or register) operand
is
visible
at
the
CPL, a word that consists of the limit field of the descriptor
is
loaded into the left operand, which
must be a register. The value
is
the limit field for that segment. The zero flag
is
set if the loading
was
performed (that
is,
if the selector
is
non-null, the selector index
is
within the descriptor table limits,
the descriptor
is
a non-conforming segment descriptor with DPL
;:::
CPL, and the descriptor DPL
;:::
selector RPL); the zero flag
is
cleared otherwise.
The
LSL instruction returns only the limit field of segments,task state segments, and local descriptor
tables. The interpretation of the limit value depends
on
the type of segment. .
The selector.operand's value cannot result in a protection
exce,l?tion
..
PROTECTED MODE EXCEPTIONS
#GP(O)
for an illegal memory operand effective address in the CS, DS, or ES segments;
#SS(O)
for an
illegal address in the
SS segment.
REAL ADDRESS MODE EXCEPTIONS
Interrupt
6;
LSL
is
not recognized
in
Real Address mode.
8-71