score: Multiprocessor Resource Sharing Protocol

Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).

The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J.  Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013.  It is a
generalization of the Priority Ceiling Protocol to SMP systems.  Each
MrsP semaphore uses a ceiling priority per scheduler instance.  These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object.  Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily.  In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.

The help out feature is not implemented with this patch.

1 files changed, 32 insertions, 0 deletions

diff --git a/doc/user/conf.t b/doc/user/conf.t
index b518176455..d72ff06661 100644
--- a/doc/user/conf.t
+++ b/doc/user/conf.t
@@ -686,6 +686,38 @@ API Semaphores that can be concurrently active.
 This object class can be configured in unlimited allocation mode.
 
 @c
+@c === CONFIGURE_MAXIMUM_MRSP_SEMAPHORES ===
+@c
+@subsection Specify Maximum Classic API Semaphores usable with MrsP
+
+@findex CONFIGURE_MAXIMUM_MRSP_SEMAPHORES
+
+@table @b
+@item CONSTANT:
+@code{CONFIGURE_MAXIMUM_MRSP_SEMAPHORES}
+
+@item DATA TYPE:
+Unsigned integer (@code{uint32_t}).
+
+@item RANGE:
+Zero or positive.
+
+@item DEFAULT VALUE:
+The default value is 0.
+
+@end table
+
+@subheading DESCRIPTION:
+@code{CONFIGURE_MAXIMUM_MRSP_SEMAPHORES} is the
+maximum number of Classic API Semaphores using the Multiprocessor Resource
+Sharing Protocol (MrsP) that can be concurrently active.
+
+@subheading NOTES:
+This configuration option is only used on SMP configurations.  On uni-processor
+configurations the Priority Ceiling Protocol is used for MrsP semaphores and
+thus no extra memory is necessary.
+
+@c
 @c === CONFIGURE_MAXIMUM_MESSAGE_QUEUES ===
 @c
 @subsection Specify Maximum Classic API Message Queues