Re: Curiousity: pragma No_Run_Time for Gnat

["chris.danx" <chris.danx@ntlworld.com>]

"M. A. Alves" <maa@liacc.up.pt> wrote in message
news:mailman.1001428823.15394.comp.lang.ada@ada.eu.org...
> The Meanings of "Pure" II
>
> Sergey wrote:
> > Well, GNAT has to generate the object files in *some* format, and
> > unless you have a cross-compiling version, it'll be ELF on Linux and
> > PE (COFF) on Win32.
>
> You mean there is no plain x86 code?  A simple sequence of machine code
> instructions?  "Pure" code?

Pure code being that which does not contain interrupts/os calls?  Or pure in
the sense that it is not in an object file?  Or that which is not protected
mode code?

> Is the good old Van Neuman architecture at risk?

Why would it be?  Von Neuman may die due to something like CA-effectant
computers (which would be ironic) or the RAW architecture but they're
immature.  Object files do not present a threat to Von Neumann machines, in
fact they're part of why it's so popular (they make things easier, hence
aiding popularity).


> (I am no guru with object code formats, but there must be a neutral one,
> with no "brand" on it (except the processor's).  I assume ELF or PE or
> COFF is not such a thing, or else this discussion is meaningless.)

No.  You misunderstand the function of an object file.  It's intended to
provide a structure to a file, and contains information that allows a linker
or loader to locate routines.  All formats are technically neutral, it's
just that on windows COFF is used more than ELF and on Linux the reverse.

> Personally for the hobby OS in Ada I am only interested in a "pure"
> approach.  No fancy loaders, no branded formats, in sum no dependencies:
> pure = truly free.

I suppose you could get a bootstrap to load a plain binary file, but you'd
still need to compile to ELF on Linux, or COFF on windows and link your
modules together into the plain format.  However the problem is that it
removes structure from the file and *could* complicate matters later.


I really don't understand what you mean by "pure" or why Object File Formats
 are so bad.



Chris