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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Unikernel / Ada
Date: Wed, 1 Mar 2017 23:58:54 +0200
Organization: Tidorum Ltd
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Xref: news.eternal-september.org comp.lang.ada:33449
Date: 2017-03-01T23:58:54+02:00
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On 17-03-01 23:20 , Randy Brukardt wrote:
> That sort of thing was done a lot, especially in the early days of Ada.
>
> Rational, for instance, had a bare-machine version of their compiler (the
> executable ran directly on the hardware with no outside kernel).
>
> Indeed, all of the MS-DOS compilers could have been considered the same, as
> MS-DOS didn't provide much other than I/O support. Everything else (tasking,
> exceptions, storage pools, etc.) was in the Ada runtime. We used to sell an
> embedded kit that included the runtime source and tools for tailoring it to
> run in a bare machine environment.
>
> For the most part, those things have disappeared, because of lack of demand.

They are still the norm in my main domain -- on-board SW for satellites 
-- and I would expect also in any embedded SW on small machines, 
although Linux is making inroads.

AdaCore supplies a range of bare-board Run-Time Systems for GNAT Pro, 
from no-runtime through various levels of Ravenscar.

Having a standard Ada RTS (even if a subset) on the embedded target is 
very nice; it makes much of the SW portable between the target and the 
host workstations, with only a little HW simulation needed in the 
workstation environment.

> That's probably because modern software needs so much more I/O (you can't
> live with just an RS232 serial connection anymore) that some sort of I/O
> kernel is needed at a minimum.

In my domain the I/O is so special (typically MIL-1553 or SpaceWire 
transports, space-specific protocols) that a standard O/S I/O system 
would not be of much use.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .