Re: GNAT and no runtime

[JCS <SANS.SPAM@MERCI.FR>]

On Wed, 26 May 2004 16:33:55 -0500, sk wrote:

>  > The author use the "pragma Supress (All_Checks)" and don't
>  > raise exception so obviously there is no such problem than
>  > I have.
> 
>  > But a real OS made in Ada should use the builtin checks and
>  > generate exception handling code, at least during the
>  > development stage.
> 
> As the author, I am aware of its limitations :-) But, how can
> you NOT suppress all checks until you have written the code
> to provide the checks.
Checks are builtin (i.e. generated by the compiler). There should be
suppressed only if you assume that you never make mistakes. (wich most 
developers seem to assume! (-: )

> 
> How can you have builtin's before you have the OS ? It seems you are
> arguing the old philisophical conundrum of the chicken and the egg.
No, I'm not willing to have a fully complete sets of tasking, memory
or real-time functionalities at this stage!
I'm just willing to have a basic Ada concept (exceptions) to go further in
the development without passing several days on a small bug because of a
stupid range check I didn't make somewhere in the code (just an exemple).

As for now, I studied a bit how exceptions works in GNAT, and it seems
that the only missing functionality is dynamic
memory allocation/deallocation. 
So now, I will try to make a static version, or maybe I will implement a
very basic dynamic memory allocation.

 
>  From my perspective, the author of the mini/toy/silly kernel,
> you have to build the hardware coordination next and then you build a
> run-time which can interface with the compiler.
Well, Ada exceptions do not involve any hardware support*, it should be
possible to implement them at the lowest level.

*: Well you need a CPU and some small amount of memory plus a basic
screen output function, but if you haven't that, you won't do many things
:-)

> My philosophy was/is based in the Intel architecture (i386 and above)
> which incorporates 4 "rings" of possible kernel security which I would
> arrange loosely as follows ...
> [...]
Even if I disagree with your design, it would be out of topic here.