i386/i386.reference/s09_01.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Section 9.1</TITLE>
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   8 Chapter 9 -- Exceptions and Interrupts</A><BR>
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  10 <B>next:</B> <A HREF="s09_02.htm">9.2  Enabling and Disabling Interrupts</A>
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  13 <P>
  14 <H1>9.1  Identifying Interrupts</H1>
  15 The processor associates an identifying number with each different type of
  16 interrupt or exception.
  17 <P>
  18 The NMI and the exceptions recognized by the processor are assigned
  19 predetermined identifiers in the range 0 through 31. Not all of these
  20 numbers are currently used by the 80386; unassigned identifiers in this
  21 range are reserved by Intel for possible future expansion.
  22 <P>
  23 The identifiers of the maskable interrupts are determined by external
  24 interrupt controllers (such as Intel's 8259A Programmable Interrupt
  25 Controller) and communicated to the processor during the processor's
  26 interrupt-acknowledge sequence. The numbers assigned by an 8259A PIC can be
  27 specified by software. Any numbers in the range 32 through 255 can be used.
  28 Table 9-1 shows the assignment of interrupt and exception identifiers.
  29 <P>
  30 Exceptions are classified as faults, traps, or aborts depending on the way
  31 they are reported and whether restart of the instruction that caused the
  32 exception is supported.
  33 <DL>
  34 <DT>
  35 Faults
  36 <DD>
  37 Faults are exceptions that are reported "before" the
  38 instruction causingthe exception. Faults are either detected before
  39 the instruction begins to execute, or during execution of the
  40 instruction. If detected during the instruction, the fault is
  41 reported with the machine restored to a state that permits the
  42 instruction to be restarted.
  43 <DT>
  44 Traps
  45 <DD>
  46 A trap is an exception that is reported at the instruction
  47 boundary immediately after the instruction in which the
  48 exception was detected.
  49 <DT>
  50 Aborts
  51 <DD>
  52 An abort is an exception that permits neither precise location
  53 of the instruction causing the exception nor restart of the program
  54 that caused the exception. Aborts are used to report severe errors,
  55 such as hardware errors and inconsistent or illegal values in system
  56 tables.
  57 <PRE>
  58 Table 9-1. Interrupt and Exception ID Assignments
  59
  60 Identifier   Description
  61
  62 0            Divide error
  63 1            Debug exceptions
  64 2            Nonmaskable interrupt
  65 3            Breakpoint (one-byte INT 3 instruction)
  66 4            Overflow (INTO instruction)
  67 5            Bounds check (BOUND instruction)
  68 6            Invalid opcode
  69 7            Coprocessor not available
  70 8            Double fault
  71 9            (reserved)
  72 10           Invalid TSS
  73 11           Segment not present
  74 12           Stack exception
  75 13           General protection
  76 14           Page fault
  77 15           (reserved)
  78 16           Coprecessor error
  79 17-31        (reserved)
  80 32-255       Available for external interrupts via INTR pin
  81 </PRE>
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  84 <P>
  85 <B>up:</B> <A HREF="c09.htm">
  86 Chapter 9 -- Exceptions and Interrupts</A><BR>
  87 <B>prev:</B> <A HREF="c09.htm">Chapter 9 -- Exceptions and Interrupts</A><BR>
  88 <B>next:</B> <A HREF="s09_02.htm">9.2  Enabling and Disabling Interrupts</A>
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