[PATCH rtems 1/2] Add support for CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR

Fri Aug 5 14:14:55 UTC 2022

On Fri, Aug 5, 2022 at 5:45 AM Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> On 05/08/2022 00:08, Joel Sherrill wrote:
> > This adds the configure option CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR
> > which allows the application to choose whether to have the POSIX
> > timer_create() function follow the behavior defined by POSIX or
> > the FACE Technical Standard.
> >
> > Updates #4691.
>
> It would be nice if you could add items for the new option to
> rtems-central so that we can use it for the Doxygen documentation and
> the manual.
>

I'll give it a try. Is there a readme or really good example?

> > ---
> >   cpukit/include/rtems/confdefs.h                    |  1 +
> >   cpukit/include/rtems/confdefs/face.h               | 71
> +++++++++++++++++
> >   cpukit/include/rtems/posix/timerimpl.h             | 11 +++
> >   cpukit/posix/src/psxtimercreate.c                  | 19 ++++-
> >   spec/build/testsuites/psxtests/grp.yml             |  2 +
> >   spec/build/testsuites/psxtests/psxtimer_face01.yml | 20 +++++
> >   testsuites/psxtests/psxtimer_face01/psxtimer.c     | 89
> ++++++++++++++++++++++
> >   .../psxtests/psxtimer_face01/psxtimer_face01.doc   | 39 ++++++++++
> >   .../psxtests/psxtimer_face01/psxtimer_face01.scn   |  4 +
> >   9 files changed, 255 insertions(+), 1 deletion(-)
> >   create mode 100644 cpukit/include/rtems/confdefs/face.h
> >   create mode 100644 spec/build/testsuites/psxtests/psxtimer_face01.yml
> >   create mode 100644 testsuites/psxtests/psxtimer_face01/psxtimer.c
> >   create mode 100644
> testsuites/psxtests/psxtimer_face01/psxtimer_face01.doc
> >   create mode 100644
> testsuites/psxtests/psxtimer_face01/psxtimer_face01.scn
> >
> > diff --git a/cpukit/include/rtems/confdefs.h
> b/cpukit/include/rtems/confdefs.h
> > index e6dd3d7..3927d26 100644
> > --- a/cpukit/include/rtems/confdefs.h
> > +++ b/cpukit/include/rtems/confdefs.h
> > @@ -64,6 +64,7 @@
> >   #include <rtems/confdefs/clock.h>
> >   #include <rtems/confdefs/console.h>
> >   #include <rtems/confdefs/extensions.h>
> > +#include <rtems/confdefs/face.h>
> >   #include <rtems/confdefs/inittask.h>
> >   #include <rtems/confdefs/initthread.h>
> >   #include <rtems/confdefs/iodrivers.h>
> > diff --git a/cpukit/include/rtems/confdefs/face.h
> b/cpukit/include/rtems/confdefs/face.h
> > new file mode 100644
> > index 0000000..07ab62e
> > --- /dev/null
> > +++ b/cpukit/include/rtems/confdefs/face.h
> > @@ -0,0 +1,71 @@
> > +/* SPDX-License-Identifier: BSD-2-Clause */
> > +
> > +/**
> > + * @file
> > + *
> > + * @ingroup RTEMSImplApplConfig
> > + *
> > + * @brief This header file evaluates configuration options related to
> > + *   the FACE Technical Standard.
> > + *
> > + * The FACE Technical Standard (https://opengroup.org/face) is an
> > + * open standard designed for safety critical embedded systems. It
> > + * includes POSIX profiles and requirements that promote safety
> > + * and portability. As a general rules, the profiles place a minimum
> > + * on the services which an operating system must provide. Those
> > + * same profile definitions represent the maximum services which
> > + * an application may use.
> > + */
> > +
> > +/*
> > + * Copyright (C) 2022 On-Line Applications Research Corporation (OAR)
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions
> > + * are met:
> > + * 1. Redistributions of source code must retain the above copyright
> > + *    notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + *    notice, this list of conditions and the following disclaimer in
> the
> > + *    documentation and/or other materials provided with the
> distribution.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS"
> > + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
> TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
> PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
> CONTRIBUTORS BE
> > + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> > + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
> BUSINESS
> > + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
> IN
> > + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
> OTHERWISE)
> > + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
> OF THE
> > + * POSSIBILITY OF SUCH DAMAGE.
> > + */
> > +
> > +#ifndef _RTEMS_CONFDEFS_FACE_H
> > +#define _RTEMS_CONFDEFS_FACE_H
> > +
> > +#ifndef __CONFIGURATION_TEMPLATE_h
> > +#error "Do not include this file directly, use <rtems/confdefs.h>
> instead"
> > +#endif
> > +
> > +#ifdef CONFIGURE_INIT
> > +
> > +#include <rtems/posix/timerimpl.h>
> > +
> > +#ifndef CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR
> > +  bool _POSIX_Timer_Is_allowed_on_CLOCK_REALTIME( void )
> > +  {
> > +    /*
> > +     * Per the FACE Technical Standard, POSIX timers should not be
> > +     * allowed on CLOCK_REALTIME for safety reasons. If the application
> > +     * wants the FACE behavior, then this method is instantiated.
> > +     */
> > +    return false;
> > +  }
>
> I would change this to:
>
> int _POSIX_Timer_Is_clock_valid( clockid_t clock_id )
>
> It returns an error number or zero.
>

Perhaps OK on errno or zero but that name isn't right. CLOCK_REALTIME
is still a valid POSIX clock. There are just strict requirements around its
use for the FACE profiles. That name implies a general validity. The
requirement
is specifically around creating a timer that uses CLOCK_REALTIME.

Previous work has addressed the other restrictions. The TOD Hook
additions do allow a BSP to sync an RTC but the FACE purpose was
to check if the application (e.g. partition/virtual space) has permission
to set the clock.

>
> > +
> > +#endif /* CONFIGURE_POSIX_TIMERS_FACE_BEHAVIOR */
> > +
> > +#endif /* CONFIGURE_INIT */
> > +
> > +#endif /* _RTEMS_CONFDEFS_FACE_H */
> > diff --git a/cpukit/include/rtems/posix/timerimpl.h
> b/cpukit/include/rtems/posix/timerimpl.h
> > index 8f92186..c6e3b64 100644
> > --- a/cpukit/include/rtems/posix/timerimpl.h
> > +++ b/cpukit/include/rtems/posix/timerimpl.h
> > @@ -139,6 +139,17 @@ RTEMS_INLINE_ROUTINE void _POSIX_Timer_Release(
> >     _ISR_lock_ISR_enable( lock_context );
> >   }
> >
> > +/**
> > + * @brief Follow POSIX or FACE Technical Standard on timer_create
> > + *
> > + * POSIX allows for the creation of timers based on CLOCK_REALTIME.
> > + * This is viewed as a safety issue by the FACE Technical Standard
> > + * and required to return an error. These are conflicting behaviors.
> > + * This method is instanced by configuration when FACE conformant
> > + * behavior is desired by the application.
> > + */
> > +RTEMS_WEAK bool _POSIX_Timer_Is_allowed_on_CLOCK_REALTIME( void );
>
> No RTEMS_WEAK in the header file.
>

OK. Need another include file clearly.

>
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> Herr Sebastian HUBER
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