Use of RTEMS_GLOBAL in non-multiprocessing configurations?

[Sebastian Huber]

On 15/06/2020 18:28, Sebastian Huber wrote:

> On 15/06/2020 18:24, Sebastian Huber wrote:
>
>> On 15/06/2020 18:13, Joel Sherrill wrote:
>>
>>> On Mon, Jun 15, 2020 at 10:52 AM Sebastian Huber 
>>> <sebastian.huber at embedded-brains.de 
>>> <mailto:sebastian.huber at embedded-brains.de>> wrote:
>>>
>>>     Hello,
>>>
>>>     should the use of RTEMS_GLOBAL be an error in
>>>     rtems_semaphore_create(),
>>>     rtems_task_create(), rtems_message_queue_create(), and
>>>     rtems_partition_create() if RTEMS was configured without
>>>     multiprocessing
>>>     enabled?
>>>
>>>
>>> Based on the original use cases, I would say no. The idea was that 
>>> you could create
>>> objects and attach to them to limit cohesion. The intention was to 
>>> avoid the use of
>>> global variables for sharing object Ids.  If I offer a service via a 
>>> message queue
>>> globally and my library/service is deployed in a non-MP 
>>> configuration, it should still
>>> work. For tasks, that would imply events. For partitions, it just 
>>> means the memory is
>>> available to "the system" which is a single processor.
>>
>> Ok, but I think this is a bit inconsistent to the
>>
>> #if defined(RTEMS_MULTIPROCESSING)
>>   if (
>>     _Attributes_Is_global( attribute_set )
>>       && !_System_state_Is_multiprocessing
>>   ) {
>>     return RTEMS_MP_NOT_CONFIGURED;
>>   }
>> #endif
>>
>> error case. If your system has only one node and is configured for 
>> multiprocessing shouldn't this behave exactly as an uniprocessor 
>> system with multiprocessing disabled? 
>
> The background for this question is that I go though the entire 
> Classic API and write specification items for it. The specification 
> items include the API documentation:
>
> https://devel.rtems.org/ticket/3993
>
> I will probably add some text similar to the one in your e-mail to 
> explain that the use of RTEMS_GLOBAL is all right in 
> non-multiprocessing configurations.

How should I name this property of an object? Is it the scope of the 
object (see 
https://man7.org/linux/man-pages/man3/pthread_attr_setscope.3.html) or 
the visibility of the object?

Is "node in a multiprocessing network" a good phrase? I would like to 
make it a bit easier to separate if from SMP.