Re: Arbitrary Sandbox

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Wed, 15 Feb 2012 22:07:37 +0100, Randy Brukardt <randy@rrsoftware.com>  
a écrit:
> 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 it
> because of the basic architectual mistake (including GNAT programs until
> recently, which is why I had to leave it off on my computer - boo). Plus
> 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 (and  
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 the  
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 generation,  
but I can't recall the details.

-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University