c-user: Move CONFIGURE_MAXIMUM_PRIORITY

Move this option to the scheduler configuration options.

Update #3836.

1 files changed, 58 insertions, 0 deletions

diff --git a/c-user/config/scheduler-general.rst b/c-user/config/scheduler-general.rst
index 0436100..438e9a3 100644
--- a/c-user/config/scheduler-general.rst
+++ b/c-user/config/scheduler-general.rst
@@ -65,6 +65,64 @@ NOTES:
     This configuration option is only evaluated if the configuration option
     :ref:`CONFIGURE_SCHEDULER_CBS` is defined.
 
+.. index:: CONFIGURE_MAXIMUM_PRIORITY
+.. index:: maximum priority
+.. index:: number of priority levels
+
+.. _CONFIGURE_MAXIMUM_PRIORITY:
+
+CONFIGURE_MAXIMUM_PRIORITY
+--------------------------
+
+CONSTANT:
+    ``CONFIGURE_MAXIMUM_PRIORITY``
+
+OPTION TYPE:
+    This configuration option is an integer define.
+
+DEFAULT VALUE:
+    The default value is 255.
+
+VALUE CONSTRAINTS:
+    The value of this configuration option shall be
+    an element of {3, 7, 31, 63, 127, 255}.
+
+DESCRIPTION:
+    For the following schedulers
+
+    * :ref:`SchedulerPriority`, which is the default in uniprocessor
+      configurations and can be configured through the
+      :ref:`CONFIGURE_SCHEDULER_PRIORITY` configuration option,
+
+    * :ref:`SchedulerSMPPriority` which can be configured through the
+      :ref:`CONFIGURE_SCHEDULER_PRIORITY_SMP` configuration option, and
+
+    * :ref:`SchedulerSMPPriorityAffinity` which can be configured through the
+      :ref:`CONFIGURE_SCHEDULER_PRIORITY_AFFINITY_SMP` configuration option
+
+    this configuration option specifies the maximum numeric priority of any task
+    for these schedulers and one less that the number of priority levels for
+    these schedulers.  For all other schedulers provided by RTEMS, this
+    configuration option has no effect.
+
+NOTES:
+    The numerically greatest priority is the logically lowest priority in the
+    system and will thus be used by the IDLE task.
+
+    Priority zero is reserved for internal use by RTEMS and is not available to
+    applications.
+
+    Reducing the number of priorities through this configuration option reduces
+    the amount of memory allocated by the schedulers listed above.  These
+    schedulers use a chain control structure per priority and this structure
+    consists of three pointers.  On a 32-bit architecture, the allocated memory
+    is 12 bytes * (``CONFIGURE_MAXIMUM_PRIORITY`` + 1), e.g. 3072 bytes for 256
+    priority levels (default), 48 bytes for 4 priority levels
+    (``CONFIGURE_MAXIMUM_PRIORITY == 3``).
+
+    The default value is 255, because RTEMS shall support 256 priority levels to
+    be compliant with various standards.  These priorities range from 0 to 255.
+
 .. index:: CONFIGURE_SCHEDULER_ASSIGNMENTS
 
 .. _CONFIGURE_SCHEDULER_ASSIGNMENTS: