Systems instructions deal with such functions as:
1. Verification of pointer parameters (refer to Chapter 6):
ARPL -- Adjust RPL
LAR -- Load Access Rights
LSL -- Load Segment Limit
VERR -- Verify for Reading
VERW -- Verify for Writing
2. Addressing descriptor tables (refer to Chaper 5):
LLDT -- Load LDT Register
SLDT -- Store LDT Register
LGDT -- Load GDT Register
SGDT -- Store GDT Register
3. Multitasking (refer to Chapter 7):
LTR -- Load Task Register
STR -- Store Task Register
4. Coprocessing and Multiprocessing (refer to Chapter 11):
CLTS -- Clear Task-Switched Flag
ESC -- Escape instructions
WAIT -- Wait until Coprocessor not Busy
LOCK -- Assert Bus-Lock Signal
5. Input and Output (refer to Chapter 8):
IN -- Input
OUT -- Output
INS -- Input String
OUTS -- Output String
6. Interrupt control (refer to Chapter 9):
CLI -- Clear Interrupt-Enable Flag
STI -- Set Interrupt-Enable Flag
LIDT -- Load IDT Register
SIDT -- Store IDT Register
7. Debugging (refer to Chapter 12):
MOV -- Move to and from debug registers
8. TLB testing (refer to Chapter 10):
MOV -- Move to and from test registers
9. System Control:
SMSW -- Set MSW
LMSW -- Load MSW
HLT -- Halt Processor
MOV -- Move to and from control registers
The instructions SMSW and LMSW are provided for compatibility with the
80286 processor. 80386 programs access the MSW in CR0 via variants of the
MOV instruction. HLT stops the processor until receipt of an INTR or RESET
signal.
In addition to the chapters cited above, detailed information about each of these instructions can be found in the instruction reference chapter, Chapter 17.