New manual. First version to CVS. Just starting to see if it builds.

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+@chapter IDLE Thread
+
+@section Does Idle Thread Have a Floating Point Context?
+
+The setting of the macro CPU_IDLE_TASK_IS_FP is based on the answer to the
+question:  Should the IDLE task have a floating point context?  If the
+answer to this question is TRUE, then the IDLE task has a floating point
+context associated.  This is equivalent to creating a task in the Classic
+API (using rtems_task_create) as a RTEMS_FLOATING_POINT task.  If
+CPU_IDLE_TASK_IS_FP is set to TRUE, then a floating point context switch
+occurs when the IDLE task is switched in and out.  This adds to the
+execution overhead of the system but is necessary on some ports.
+
+If FALSE, then the IDLE task does not have a floating point context.
+
+NOTE: Setting CPU_IDLE_TASK_IS_FP to TRUE negatively impacts the time
+required to preempt the IDLE task from an interrupt because the floating
+point context must be saved as part of the preemption.
+
+The following illustrates how to set this macro:
+
+@example
+#define CPU_IDLE_TASK_IS_FP      FALSE
+@end example
+
+@section CPU Dependent Idle Thread Body
+
+@subsection CPU_PROVIDES_IDLE_THREAD_BODY Macro Setting
+
+The CPU_PROVIDES_IDLE_THREAD_BODY macro setting is based upon the answer
+to the question:  Does this port provide a CPU dependent IDLE task
+implementation?  If the answer to this question is yes, then the
+CPU_PROVIDES_IDLE_THREAD_BODY macro should be set to TRUE, and the routine
+_CPU_Thread_Idle_body must be provided.  This routine overrides the
+default IDLE thread body of _Thread_Idle_body.  If the
+CPU_PROVIDES_IDLE_THREAD_BODY macro is set to FALSE, then the generic
+_Thread_Idle_body is the default IDLE thread body for this port.  
+Regardless of whether or not a CPU dependent IDLE thread implementation is
+provided, the BSP can still override it.
+
+This is intended to allow for supporting processors which have a low power
+or idle mode.  When the IDLE thread is executed, then the CPU can be
+powered down when the processor is idle.
+
+The order of precedence for selecting the IDLE thread body is:
+
+@enumerate
+@item BSP provided
+
+@item CPU dependent (if provided)
+
+@item generic (if no BSP and no CPU dependent)
+
+@end itemize
+
+The following illustrates setting the CPU_PROVIDES_IDLE_THREAD_BODY macro:
+
+@example
+#define CPU_PROVIDES_IDLE_THREAD_BODY    TRUE
+@end example
+
+Implementation details of a CPU model specific IDLE thread body are in the
+next section.
+
+@subsection Idle Thread Body
+
+The _CPU_Thread_Idle_body routine only needs to be provided if the porter
+wishes to include a CPU dependent IDLE thread body.  If the port includes
+a CPU dependent implementation of the IDLE thread body, then the
+CPU_PROVIDES_IDLE_THREAD_BODY macro should be defined to TRUE.  This
+routine is prototyped as follows:
+
+@example
+void _CPU_Thread_Idle_body( void );
+@end example
+
+As mentioned above, RTEMS does not require that a CPU dependent IDLE
+thread body be provided as part of the port.  If
+CPU_PROVIDES_IDLE_THREAD_BODY is defined to FALSE, then the CPU
+independent algorithm is used.  This algorithm consists of a "branch to
+self" which is implemented in the XXX routine as follows.
+
+@example
+XXX check name and exact implementation
+void _Thread_Idle_body( void )
+@{
+  while( 1 ) ;
+@}
+@end example
+
+If the CPU dependent IDLE thread body is implementation centers upon using
+a "halt", "idle", or "shutdown" instruction, then don't forget to put it
+in an infinite loop as the CPU will have to reexecute this instruction
+each time the IDLE thread is dispatched.
+
+@example
+void _CPU_Thread_Idle_body( void )
+@{
+
+  for( ; ; )
+    /* insert your "halt" instruction here */ ;
+@}
+@end example
+
+Be warned. Some processors with onboard DMA have been known to stop the
+DMA if the CPU were put in IDLE mode.  This might also be a problem with
+other on-chip peripherals.  So use this hook with caution.
+