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Newsgroups: comp.lang.ada
Subject: Re: Ravenscar - program termination
References: <epl7mp$tls$1@cernne03.cern.ch>
 <87zm81txs1.fsf@ludovic-brenta.org>
 <epmuf7$ihm$1@cernne03.cern.ch>
From: Markus E Leypold
 <development-2006-8ecbb5cc8aREMOVETHIS@ANDTHATm-e-leypold.de>
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Date: Tue, 30 Jan 2007 10:37:20 +0100
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Maciej Sobczak <no.spam@no.spam.com> writes:

> Ludovic Brenta wrote:
>
>>> Do I understand correctly that Ravenscar programs are by definition
>>> running forever? What about programs that are expected to finish?
>> Yes, it is my understanding as well, and I'm happy with that.
>>     I remember being impressed with Ada because you could write an
>>     infinite loop without a faked up condition. The idea being that in
>>     Ada the typical infinite loop would normally be terminated by
>>     detonation.  -- Larry Wall
>
> :-)
>
>> The Ravenscar profile is specifically targeted at high-integrity
>> systems, where infinite loops are, I think, the norm.
>
> Sorry, but I don't see anything in the concept of high-integrity
> software that would make it a norm. High-integrity software is a set
> of quality objectives, whereas infinite loops are (or aren't) part of
> system requirements. These should stay independent, even though I
> understand that expectations for both often come in pairs.
>
> OK, just nit-picking. ;-)
> I wanted to be sure that I understand it correctly, thanks.
> Still, it looks like I cannot say:
>
> pragma Profile(Ravenscar);
>
> in my Hello World program even though this program meets the
> objectives of the profile. That's not fair! :-)

Well, it terminates. What does termination mean in a "high integrity"
embedded system -- does the hardware go away? :-). I think if someone
wants to shutdown such a system the thing happening is, that every
task goes into idle mode and the last thing a controlling task does,
is, to display (or otherwise indicate) "you may now shut off power,
the countdown to eject the warp core has been stopped" or something
like this.

:-)

Regards -- Markus