c-user/config/face.rst: New file -- add CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR

Closes #4691.

c-user/config/face-technical-standard.rst

@@ -0,0 +1,76 @@
+.. SPDX-License-Identifier: CC-BY-SA-4.0
+
+.. Copyright (C) 2022 On-Line Applications Research Corporation (OAR)
+
+.. This file is part of the RTEMS quality process and was automatically
+.. generated.  If you find something that needs to be fixed or
+.. worded better please post a report or patch to an RTEMS mailing list
+.. or raise a bug report:
+..
+.. https://www.rtems.org/bugs.html
+..
+.. For information on updating and regenerating please refer to the How-To
+.. section in the Software Requirements Engineering chapter of the
+.. RTEMS Software Engineering manual.  The manual is provided as a part of
+.. a release.  For development sources please refer to the online
+.. documentation at:
+..
+.. https://docs.rtems.org
+
+.. Generated from spec:/acfg/if/group-face
+
+FACE Technical Standard Related Configuration
+=============================================
+
+This section describes configuration options related to adapting
+RTEMS behavior to be aligned with the FACE Technical Standard.
+The FACE Technical Standard is a product of the FACE Consortium
+which operates under the Open Group. The FACE Consortium was founded
+by avionics organizations to improve the portability of cockpit software
+across various platforms. It addresses technical and business concerns.
+
+Most important from an RTEMS perspective, the FACE Technical Standard
+defines four POSIX profiles: Security, Safety Base, Safety Extended, and
+the General Purpose Profile. Each has an increasingly larger subset of
+POSIX APIs. In the Security and Safety profiles, ARINC 653 is required.
+It is optional in the General Purpose Profile.
+
+The RTEMS Project has been tracking alignment with the FACE POSIX profiles
+and they are included in the "RTEMS POSIX 1003.1 Compliance Guide."
+
+.. Generated from spec:/acfg/if/posix-timer-face-behavior
+
+.. raw:: latex
+
+    \clearpage
+
+.. index:: CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR
+
+.. _CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR:
+
+CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR
+------------------------------------
+
+.. rubric:: CONSTANT:
+
+``CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR``
+
+.. rubric:: OPTION TYPE:
+
+This configuration option is a boolean feature define.
+
+.. rubric:: DEFAULT CONFIGURATION:
+
+If this configuration option is undefined, then the described feature is not
+enabled.
+
+.. rubric:: DESCRIPTION:
+
+If this configuration option is defined, then POSIX timers may not be created
+to use the :term:`CLOCK_REALTIME`.  Per POSIX, this is allowed
+behavior but per the FACE Technical Standard, it is not. Using POSIX timers
+based on CLOCK_REALTIME (e.g., time of day) is unsafe for real-time safety
+systems as setting CLOCK_REALTIME will perturb any active timers.
+
+If this option is not defined, POSIX timers may be created to use the
+CLOCK_REALTIME in compliance with the POSIX specification.

c-user/config/index.rst

@@ -24,6 +24,7 @@ Configuring a System
     idle-task
     scheduler-general
     scheduler-clustered
+    face-technical-standard
     bsp-related
     mpci
     libpci