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!standard H.6          12-11-21 AC95-00239/00
!class confirmation 12-11-21
!status received no action 12-11-21
!status received 12-10-12
!subject Ravenscar profile and Partition Elaboration_Policy
!summary
!appendix

From: Tucker Taft
Sent: Friday, October 12, 2012  9:15 AM

We have had some questions at AdaCore whether it was intentional to leave out a
specification of Partition Elaboration Policy from the Ravenscar Profile?
Presumably many users of Ravenscar would prefer the Sequential policy, but it is
not mentioned in the section on the Ravenscar profile in the Ada reference
manual.

Alan?

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From: Robert Dewar
Sent: Friday, October 12, 2012  9:25 AM

> We have had some questions at AdaCore whether it was intentional to
> leave out a specification of Partition Elaboration Policy from the
> Ravenscar Profile?  Presumably many users of Ravenscar would prefer
> the Sequential policy, but it is not mentioned in the section on the
> Ravenscar profile in the Ada reference manual.

Note that the Ravenscar AI has the quote:

> "To satisfy the requirements of the Safety Critical and High-Integrity
> domains, there is a need to define the behavior of program elaboration to be atomic.
> That is to say, that no interrupts are delivered during this period of
> execution. In addition, task activation shall be deferred until the
> completion of all elaboration code."

But this did not make its way into the RM. I distinctly remember this issue
being discussed at Ravenscar 2, and the above quote is in accord with the
conclusions of tht meeting.

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From: Tullio Vardanega
Sent: Saturday, October 13, 2012  8:49 AM

That quote certainly was -- and still is -- the group's view of the requirement.
No memory of why that did not make the RM.

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From: Alan Burns
Sent: Monday, October 15, 2012  4:36 AM

Although the group considers this to be important it could not decide whether
the Sequencial policy should be part of Ravenscar or be an additional policy
that the user could request in addition to Ravenscar. I think the debate we had
(and which was presumable repeated at the ARG) was that:
pragma Partition_Elaboration_Policy(Sequential);
should be defined separately in Annex H, but not be part of Ravenscar.

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From: Tucker Taft
Sent: Monday, October 15, 2012  8:36 AM

Thanks for the insight.  We should add the above as an AARM comment, to capture
this explanation for posterity, and for implementors.

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