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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Suitability of ada environments for systems development
Date: 1999/07/03
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Date: 1999-07-03T00:00:00+00:00
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In article <7lk09t$rmo$1@usenet01.srv.cis.pitt.edu>,
  "John Duncan" <jddst19+@pitt.edu> wrote:
> Robert-

> What I do not want is some sort of operating-system specific
> solution, even to the extent of the scheduling of tasks.

Again, it is not quite clear what model you have in mind for
an Ada implementation ....

Current Ada compilers are typically ported to many operating
systems (GNAT has been ported to many varieties of Unix and
Linux, DOS, OS/2, NT, Win95, MachTen, VMS, Nextstep, VxWorks,
RTEMS, etc)

So clearly these compilers do NOT have an operating specific
solution!

Most frequently the design is a layered one. In the case of
GNAT, the low level tasking interface is at the level of a
subset of pthreads, and can either be mapped to pthreads, or
to some similar set of facilities in some other operating
system.

If you write your own operating system or executive, the
cleanest thing is to provide a complete implementation of
Posix threads, including ceiling priority support. Porting
Ada to meet that interface should be very straightforward.
Alternatively, you need to provide a think layer to interface
with what ever similar primitives you have.

Regarding vendor input, you simply won't get any serious
vendor input in this forum, but if what you are looking for
is answers to rather general issues such as the above, then
you probably can get some answers here, though not necessarily
from vendors, and not necessarily reliable :-)


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