On Wed, Nov 22, 2017 at 3:31 PM, Chris Johns <chr...@rtems.org> wrote:
> On 22/11/2017 23:42, Sebastian Huber wrote: > > +Global Construction > > +------------------- > > + > > +The global construction is carried out by the first Classic API > initialization > > +task. If no Classic API initialization task exists, then it is carried > out by > > +the first POSIX API initialization thread. If no initialization task > or thread > > +exists, then no global construction is performed, see for example > > +:ref:`Specify Idle Task Performs Application Initialization`. > > What sort of context do the constructors run in? > They run in the context of the first user thread that runs. This means that technically it varies based on user initialization task/thread configuration. > > What impact does the context have on the configuration of what ever > context is > being used, eg stack size, priority, ...? > They use stack space. So they would have to be accounted for in the usage of the thread they will run in. Which leads to the next issue... priority and which init thread runs them is a bit challenging I think if you constructed an example with like both_hello and gave the Classic API initialization task a lower priority than the POSIX Initialization thread, that you would see the constructors run from the POSIX Initialization thread since it would run first. isn't the rule that these are executed by the first thread to execute? > > What services in RTEMS can be used from global constructors? > Likely everything except services explicitly started like networking, mounted filesystems, etc. There is also the issue that these could perform blocking operations and that could potentially lead to some weird situations. If you only have one initialization task/thread, it would introduce a possibly unexpected delay in the time until the application is really alive. If the constructors create threads/tasks, there are scenarios where they could execute before the entire set of constructors is completed. That could lead to unfortunate situations. All of this needs to be documented. My response is simply based on my understanding of where in the initialization sequence these are executed and what I think could occur. --joel > > Chris > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel >
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