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Re: emulating no-senders notifications in L4?

From: Jean Wolter
Subject: Re: emulating no-senders notifications in L4?
Date: 20 Dec 2001 18:25:07 +0100
User-agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Civil Service)

nisse@lysator.liu.se (Niels Möller) writes:

> > However, I'm not sure if L4-Hurd needs a central port right server. Is
> > it really necessary?
> My reasoning, in
>   Message-ID: <nnelmybwbf.fsf@sture.lysator.liu.se>
>   Date: 16 Nov 2001 15:54:28 +0100)
> was that an extra level of indirection is necessary for implementing a
> reliable no-senders notification. I'd be delighted to be proved wrong.

If I understand your "reasoning" right you need the extra level of
indirection to implement a reliable "no sender notification" for the
case, that

- a task does suicide
- a task dies violently (with this I assume you mean it raises
  an exception  and is killed by the micro kernel).

As Volkmar already pointed out it is impossible for a task to do
suicide since only the task server is allowed to create and delete

And a task can not die violently since if it raises an exception this
exception is delivered to an exception handler thread which can handle
this situation.

So it should be possible to inform all interested servers about the
death of a task and therefore all server could clean up their
resources if the dying task was the last user.

Did I miss anything?


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