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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
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Newsgroups: comp.lang.ada
Subject: Re: Arbitrary Sandbox
Date: Wed, 15 Feb 2012 23:10:39 +0100
Organization: Ada @ Home
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Date: 2012-02-15T23:10:39+01:00
List-Id: <comp.lang.ada>

Le Wed, 15 Feb 2012 22:07:37 +0100, Randy Brukardt <randy@rrsoftware.com=
>  =

a =C3=A9crit:
> Now, I recognize that DEP was added to Intel hardware to provide some =
of
> this protection, but the problem is that a lot of programs can't use i=
t
> because of the basic architectual mistake (including GNAT programs unt=
il
> recently, which is why I had to leave it off on my computer - boo). Pl=
us
> requiring a new feature to get this protection is annoying as it was  =

> always available in Intel hardware (back to 80286); people just had to=
  =

> use it and they didn't. (I think that was a consequence of Windows NT =
 =

> copying the bad Unix memory model more than an intentional decision
I use to wonder if there a so much clever reason so that I could not  =

understand it. But you are competent enough, and feel the same too about=
  =

the flat memory model. So you confirm something was sadly wasted here (a=
nd  =

yes, since the very old 80286).

Well, beyond segment protection, there is page protection (since 80486 (=
*)  =

). May be this one was precisely added by Intel to afford something to t=
he  =

flat memory model to which segment by segment attributes was not  =

accessible. Otherwise, I don't see why, as this is probably cleaner to  =

apply the same attributes to a whole segment.

(*) And something else again added again later, with a Pentium generatio=
n,  =

but I can't recall the details.

-- =

=E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1]
=E2=80=9CStructured Programming supports the law of the excluded muddle.=
=E2=80=9D [1]
[1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers=
ity