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Date: Sat, 27 Sep 2008 19:14:05 -0400
From: "Peter C. Chapin" <pcc482719@gmail.com>
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Subject: Re: Blocking syscalls in Tasks
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Date: 2008-09-27T19:14:05-04:00
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schwering wrote:

> My understanding is the same -- or at least I nowhere found something
> else.
> But I wonder about this, because in my opinion there is a great
> difference between tasks = userspace threads and tasks = kernelspace
> threads.

I think the reason this is probably left implementation defined is so
that Ada can be implemented on systems that don't provide kernel threads
to the applications. On such systems, the Ada runtime can implement user
mode threads and still obey the standard.

User mode threads do have some nice properties on their own however...
specifically, fast context switching times. Thus even when kernel
threads are available an implementation might want to provide some
options in this area.

> Hence, I think there should at least be some way to
> check whether in the given implementation of tasks blocking syscalls
> block only the calling task or everything.

One imagines it would be documented some place. At least you would like
to believe that.

Peter