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+@c
+@c  COPYRIGHT (c) 1988-1998.
+@c  On-Line Applications Research Corporation (OAR).
+@c  All rights reserved. 
+@c
+@c  $Id$
+@c
+
+@chapter Stack Bounds Checker
+
+@section Introduction
+
+The stack bounds checker is an RTEMS support component that determines
+if a task has overflowed its run-time stack.  The routines provided
+by the stack bounds checker manager are:
+
+@itemize @bullet
+@item @code{Stack_check_Initialize} - Initialize the Stack Bounds Checker
+@item @code{Stack_check_Dump_usage} - Report Task Stack Usage
+@end itemize
+
+@section Background
+
+@subsection Task Stack
+
+Each task in a system has a fixed size stack associated with it.  This
+stack is allocated when the task is created.  As the task executes, the
+stack is used to contain parameters, return addresses, saved registers,
+and local variables.  The amount of stack space required by a task
+is dependent on the exact set of routines used.  The peak stack usage 
+reflects the worst case of subroutine pushing information on the stack.
+For example, if a subroutine allocates a local buffer of 1024 bytes, then
+this data must be accounted for in the stack of every task that invokes that
+routine.
+
+Recursive routines make calculating peak stack usage difficult, if not
+impossible.  Each call to the recursive routine consumes @i{n} bytes
+of stack space.  If the routine recursives 1000 times, then @code{1000 * @i{n}}
+bytes of stack space are required.
+
+@subsection Execution
+
+The stack bounds checker operates as a set of task extensions.  At
+task creation time, the task's stack is filled with a pattern to
+indicate the stack is unused.  As the task executes, it will overwrite
+this pattern in memory.  At each task switch, the stack bounds checker's
+task switch extension is executed.  This extension checks that the last
+@code{n} bytes of the task's stack have not been overwritten.  If they
+have, then a blown stack error is reported.
+
+The number of bytes checked for an overwrite is processor family dependent.
+The minimum stack frame per subroutine call varies widely between processor
+families.  On CISC families like the Motorola MC68xxx and Intel ix86, all
+that is needed is a return address.  On more complex RISC processors,
+the minimum stack frame per subroutine call may include space to save
+a significant number of registers.
+
+Another processor dependent feature that must be taken into account by
+the stack bounds checker is the direction that the stack grows.  On some
+processor families, the stack grows up or to higher addresses as the
+task executes.  On other families, it grows down to lower addresses.  The
+stack bounds checker implementation uses the stack description definitions
+provided by every RTEMS port to get for this information.
+
+@section Operations
+
+@subsection Initializing the Stack Bounds Checker
+
+The stack checker is initialized automatically when its task
+create extension runs for the first time.  When this occurs,
+the @code{Stack_check_Initialize} is invoked.
+
+The application must include the stack bounds checker extension set
+in its set of Initial Extensions.  This set of extensions is
+defined as @code{STACK_CHECKER_EXTENSION}.  If using @code{<confdefs.h>}
+for Configuration Table generation, then all that is necessary is
+to define the macro @code{STACK_CHECKER_ON} before including 
+@code{<confdefs.h>} as shown below:
+
+@example
+@group
+#define STACK_CHECKER_ON
+  ...
+#include <confdefs.h>
+@end group
+@end example
+
+@subsection Reporting Task Stack Usage
+
+The application may dynamically report the stack usage for every task
+in the system by calling the @code{Stack_check_Dump_usage} routine.
+This routine prints a table with the peak usage and stack size of
+every task in the system.  The following is an example of the
+report generated:
+
+@example
+@group
+    ID      NAME       LOW        HIGH     AVAILABLE      USED
+0x04010001  IDLE  0x003e8a60  0x003e9667       2952        200
+0x08010002  TA1   0x003e5750  0x003e7b57       9096       1168
+0x08010003  TA2   0x003e31c8  0x003e55cf       9096       1168
+0x08010004  TA3   0x003e0c40  0x003e3047       9096       1104
+0xffffffff  INTR  0x003ecfc0  0x003effbf      12160        128
+@end group
+@end example
+
+Notice the last time.  The task id is 0xffffffff and its name is "INTR".
+This is not actually a task, it is the interrupt stack.
+
+@subsection When a Task Overflows the Stack
+
+When the stack bounds checker determines that a stack overflow has occurred,
+it will attempt to print a message identifying the task and then shut the
+system down.  If the stack overflow has caused corruption, then it is 
+possible that the message can not be printed.
+
+The following is an example of the output generated:
+
+@example
+@group
+BLOWN STACK!!! Offending task(0x3eb360): id=0x08010002; name=0x54413120
+  stack covers range 0x003e5750 - 0x003e7b57 (9224 bytes)
+  Damaged pattern begins at 0x003e5758 and is 128 bytes long
+@end group
+@end example
+
+The above includes the task id and a pointer to the task control block as
+well as enough information so one can look at the task's stack and
+see what was happening.
+
+@section Routines
+
+This section details the stack bounds checker's routines.
+A subsection is dedicated to each of routines
+and describes the calling sequence, related constants, usage,
+and status codes.
+
+@page
+@subsection Stack_check_Initialize - Initialize the Stack Bounds Checker
+
+@subheading CALLING SEQUENCE:
+
+@ifset is-C
+@example
+void Stack_check_Initialize( void );
+@end example
+@end ifset
+
+@ifset is-Ada
+@example
+An Ada interface is not currently available.
+@end example
+@end ifset
+
+@subheading STATUS CODES: NONE
+
+@subheading DESCRIPTION:
+
+Initialize the stack bounds checker.
+
+@subheading NOTES:
+
+This is performed automatically the first time the stack bounds checker
+task create extension executes.
+
+@page
+@subsection Stack_check_Dump_usage - Report Task Stack Usage
+
+@subheading CALLING SEQUENCE:
+
+@ifset is-C
+@example
+void Stack_check_Dump_usage( void );
+@end example
+@end ifset
+
+@ifset is-Ada
+@example
+An Ada interface is not currently available.
+@end example
+@end ifset
+
+@subheading STATUS CODES: NONE
+
+@subheading DESCRIPTION:
+
+This routine prints a table with the peak stack usage and stack space
+allocation of every task in the system.
+
+@subheading NOTES:
+
+NONE