[Fwd: Re: feedback requested on proposed new directive]

[Rosimildo da Silva]

From: Joel Sherrill <joel.sherrill at OARcorp.com>
To: Rosimildo da Silva <rdasilva at connecttel.com>
Cc: rtems <rtems-users at oarcorp.com>
Sent: Monday, August 28, 2000 12:56 PM
Subject: Re: [Fwd: Re: feedback requested on proposed new directive]


> Rosimildo da Silva wrote:
>
> > > We are considering adding a new directive to expose functionality
> > > that has long been in the SuperCore.  It is an alternate task
> > > entry style that follows "main".  Your task's argument list would
> > > look like:
> > >
> > > rtems_task MYTASK( int argc, char ** argv )
> >
> > Why not a signature to match main():
> >
> >         int MYTASK( int argc, char ** argv );
>
> This is OK by me... but what to do when MYTASK returns?

Never mind. I thought this API was to start main(), but now I understand,
it is just a call to be used inside the current main() routine.

>
> > > The directive would look something like this (naming suggestions
> > > requested :).
> > >
> > > rtems_status_code rtems_task_start_main_style(
> > >   rtems_id         id,
> > >   rtems_task_entry entry_point,  /* probably need another type? */
> > >   int               argc
> > >   char            **argv
> > > );
> >
> > I guess the idea is to start main() routine from it ?
> >
> > Are you planning to remove the call to main() from boot_card.c ?
>
> Eventually I would like to do so.  It is impossible to support
> all the weird things that a global constructor can do when running
> in a state where you can't block.  This means you can't do IO in
> many (most?) situations?
>

Why not call main() from within the init_task ?
Global Ctor would be called from inside this init task.

start  ---> boot_card() ----> start multi-task --> init_task()  -->
init()/fini()

main()   --> user code.

> >  rtems_status_code rc;
> >  rc = rtems_task_start_main_style( id, main, argc, argv );
> >
> > What happens when exit() &/or assert() are called ?
>
> Same thing that happens now.  The whole application gets shutdown.
> We can discuss the semantics of what happens and modify them
> over time.  Modifying the view of what happens will probably
> be necessary as dynamic loading becomes real.
>

Ok.


> > I guess it is important to know what we are trying to
> > archive here:
> >
> >    + have a stardard way of starting up RTEMS.
> >
> >    + making easier porting 3rd party applications
>
> This is the initial and sole goal of the above.
>
> >    + providing a standard configuration
> >
> > All programmers expects something similar a "C" program
> > as an entry point for any application.
> > A RTEMS newbee would like to have this fisrt application,
> > link it against RTEMS libraries, and get up and running.
> > At this moment, he/she should not be worried about
> > configuration, init task, stack size, prority, etc.
> >
> >   int main( int argc, char**argv )
> >   {
> >       printf( "Hello World\n" );
> >       return 0;
> >   }
>
> I would eventually like to get to this but for now just want
> it to be easier to port UNIX applications.  I think that
> getting better support for main()-style tasks is a big step
> in that direction.
>
> The next logical step (to me) is to remove main from the BSP and
> make it the initial task.
>

Sounds good.

Rosimildo.