User's Manual

THE. 80286 INSTRUCTION SET
LAR-Load Access Rights Byte
Opcode
OF 02 Ir
FLAGS MODIFIED
Zero
Instruction
LAR rW,ew
FLAGS UNDEFINED
None
OPERATION
Clocks
Description
14,mem=16 Load: high(rw)= Access Rights byte, selector ew
LAR expects the second operand (memory or register word) to contain a selector. If the associated
descriptor
is visible at the current privilege level and at the selector RPL, then the access rights byte
of the descriptor
is loaded into the high byte of the first (register) operand, and the low byte is set to
zero. The zero flag is set if the loading was performed (i.e., the selector index is within the table limit,
descriptor
DPL :2: CPL, and descriptor DPL :2: selector RPL); the zero flag is cleared otherwise.
Selector operands cannot cause protection exceptions.
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 EXCEPTION
INTERRUPT 6; LAR is unrecognized in Real Address mode.
8-60