i386/i386.reference/s12_01.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Section 12.1</TITLE>
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   8 Chapter 12 -- Debugging</A><BR>
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  10 <B>next:</B> <A HREF="s12_02.htm">12.2  Debug Registers</A>
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  14 <H1>12.1  Debugging Features of the Architecture</H1>
  15 The features of the 80386 architecture that support debugging include:
  16 <DL>
  17 <DT>
  18 Reserved debug interrupt vector
  19 <DD>
  20 Permits processor to automatically invoke a debugger task or procedure when
  21 an event occurs that is of interest to the debugger.
  22 <DT>
  23 Four debug address registers
  24 <DD>
  25 Permit programmers to specify up to four addresses that the CPU will
  26 automatically monitor.
  27 <DT>
  28 Debug control register
  29 <DD>
  30 Allows programmers to selectively enable various debug conditions
  31 associated with the four debug addresses.
  32 <DT>
  33 Debug status register
  34 <DD>
  35 Helps debugger identify condition that caused debug exception.
  36 <DT>
  37 Trap bit of TSS (T-bit)
  38 <DD>
  39 Permits monitoring of task switches.
  40 <DT>
  41 Resume flag (RF) of flags register
  42 <DD>
  43 Allows an instruction to be restarted after a debug exception without
  44 immediately causing another debug exception due to the same condition.
  45 <DT>
  46 Single-step flag (TF)
  47 <DD>
  48 Allows complete monitoring of program flow by specifying whether the CPU
  49 should cause a debug exception with the execution of every instruction.
  50 <DT>
  51 Breakpoint instruction
  52 <DD>
  53 Permits debugger intervention at any point in program execution and aids
  54 debugging of debugger programs.
  55 <DT>
  56 Reserved interrupt vector for breakpoint exception
  57 <DD>
  58 Permits processor to automatically invoke a handler task or procedure upon
  59 encountering a breakpoint instruction.
  60 </DL>
  61 These features make it possible to invoke a debugger that is either a
  62 separate task or a procedure in the context of the current task. The
  63 debugger can be invoked under any of the following kinds of conditions:
  64 <UL>
  65 <LI> Task switch to a specific task.
  66 <LI> Execution of the breakpoint instruction.
  67 <LI> Execution of every instruction.
  68 <LI> Execution of any instruction at a given address.
  69 <LI> Read or write of a byte, word, or doubleword at any specified address.
  70 <LI> Write to a byte, word, or doubleword at any specified address.
  71 <LI> Attempt to change a debug register.
  72 </UL>
  73 <P>
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  77 Chapter 12 -- Debugging</A><BR>
  78 <B>prev:</B> <A HREF="c12.htm">Chapter 12 -- Debugging</A><BR>
  79 <B>next:</B> <A HREF="s12_02.htm">12.2  Debug Registers</A>
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