User's Manual

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