iAPX 286 Operating System Writers Guide 1983

TABLE OF CONTENTSCHAPTER 12PageNUMERICS PROCESSOR EXTENSIONiAPX 286/20 Numerics Processing Features ................................................ 12-1ESCAPE Instructions ................................................................................. 12-1Emulation Mode Flag (EM) ........................................................................ 12-1Math Present Flag (MP). .... .............................................. ........................... 12-2Task Switched Flag (TS) ........................................................................... 12-2WAIT Instruction ........................................................................................ 12-2Summary ................................................................................................... 12-2Initialization ................................................................................................... 12-2Task State .................................................................................................... 12-3Numerics Exceptions .................................................................................... 12-3Interrupt 7-Processor Extension Not Available (NM) ............................... 12-3Interrupt 9-Processor Extension Segment Overrun (MP) ............ ............ 12-4Interrupt 16-Processor Extension Error (MF) .......................................... 12-5CHAPTER 13EXTENDED PROTECTIONExtended Type ..........................................................................,................... 13-1Type Extension Code with Descriptor ................................... ~................... 13-1Type Extension Code in Segment ............................................................. 13-1Indirect Naming ......................................................................................... 13-2Parameter Validation ..................................................................................... 13-2Defensive Use of ARPL ............................................................................. 13-2Point-of-Entry Scrutiny................... ........................................................... 13-3Usage Privilege Level .................................................................................... 13-4Send Privilege Level ...................................................................................... 13-5Constructing Shared Objects ........................................................................ 13-5GLOSSARYINDEXLIST OF TABLESTable Title Page0-1 Prerequisites by Chapter ...................................................................... v2-1 Categories of Control Flow Transfer .................................................... 2-72-2 Control Transfer Mechanisms .............................................................. 2-103-1 Actions for Combining Segments ......................................................... 3-94-1 Task Switching Operations .................................................................. 4-36-1 Interrupt Response Time ...................................................................... 6-57-1 Restart Conditions ................................................................................ 7-812-1 Interpretation of MP and EM Flags .............. ......................................... 12-313-1 Access Checking Instructions .............................................................. 13-2x 121960-001