[PATCH v2] c-user: Add scheduler glossary terms

[Sebastian Huber]

Add glossary terms which characterize the relationship of a scheduler to
a task.
---

v2:

Address review comments.  Use "foreign" instead of "alien".

 c-user/glossary.rst | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/c-user/glossary.rst b/c-user/glossary.rst
index 4e375de..0350033 100644
--- a/c-user/glossary.rst
+++ b/c-user/glossary.rst
@@ -240,6 +240,10 @@ Glossary
         This term is an acronym for
         `Executable and Linkable Format <https://en.wikipedia.org/wiki/Executable_and_Linkable_Format>`_.
 
+    eligible scheduler
+        An eligible scheduler of a :term:`task` is a :term:`scheduler` which can be
+        used by the task to allocate a processor for the task.
+
     embedded
         An application that is delivered as a hidden part of a larger system.
         For example, the software in a fuel-injection control system is an
@@ -301,6 +305,10 @@ Glossary
         mathematically intensive situations.  It is typically viewed as a logical
         extension of the primary processor.
 
+    foreign scheduler
+        An foreign scheduler of a :term:`task` is a :term:`scheduler` which is not
+        an :term:`eligible scheduler`.
+
     freed
         A resource that has been released by the application to RTEMS.
 
@@ -340,9 +348,20 @@ Glossary
         dispatch is marked as necessary, then the next thread dispatch will make
         the heir task the executing task.
 
+    helping scheduler
+        A helping scheduler of a :term:`task` is a :term:`scheduler` which is a
+        :term:`eligible scheduler` and which is not the :term:`home scheduler` of
+        the task.
+
     heterogeneous
         A multiprocessor computer system composed of dissimilar processors.
 
+    home scheduler
+        The home scheduler of a :term:`task` is a :term:`scheduler` which is a
+        :term:`eligible scheduler` and which is assigned to the task during the
+        initialization or explicitly via a directive call such as
+        :c:func:`rtems_task_set_scheduler`.
+
     homogeneous
         A multiprocessor computer system composed of a single type of processor.
 
@@ -728,6 +747,11 @@ Glossary
         priority number and assign the tasks with the lowest priority number to
         one processor of the set of processors owned by a scheduler instance.
 
+        A scheduler is either an :term:`eligible scheduler` or a
+        :term:`foreign scheduler` for a task.  An :term:`eligible scheduler` is
+        either the :term:`home scheduler` or a :term:`helping scheduler` for a
+        task.
+
     scheduler instance
         A scheduler instance is a scheduling algorithm with a corresponding
         context to store its internal state.  Each processor in the system is
-- 
2.26.2