Date: Sun, 10 Aug 1997 18:09:57 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: "Gurunandan R. Bhat" <grbhat AT unigoa DOT ernet DOT in>
cc: djgpp AT delorie DOT com
Subject: Re: segment limit of _dos_ds
In-Reply-To: <Pine.LNX.3.91.970803132134.2894A-100000@aditya.unigoa.ernet.in>
Message-ID: <Pine.SUN.3.91.970810180922.4651i-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Precedence: bulk


On Sun, 3 Aug 1997, Gurunandan R. Bhat wrote:

> The FAQ that I have (ver 2.10) says that the limit of the segment 
> pointed to by _dos_ds is 1MB and then in a footnote continues:
> 
> ...*Original* version of DJGPP 2.01 makes limit of _dos_ds be 4GB....
> 
> (emphasis mine)
> For my DJGPP setup (most recent, or so I thought), I get
> 
> __dpmi_get_segment_limit(_dos_ds) = ffffffff
> 
> Does this mean that I have the "Original" version as opposed to the "Later"

I have wondered how much time would it take for somebody to pay
attention, and who would that person be.

Here's the story behind this: the fact that `_dos_ds' has a 4GB limit
became known to me shortly before FAQ 2.10 was released.  During a
discussion, DJ Delorie explained that he enlarged it from 1MB because
too many people wanted it be enlarged for all kinds of memory-mapped
devices.  The footnote that you cite was written in the hope that this
limit will be set back to 1MB in a later release.  But since DJGPP was
not updated since then, the latest DJGPP version still has a 4GB-large
limit.  IMHO, this is a Bad Thing, because it allows a program to
corrupt every address in sight, while the benefits are almost none:
most DPMI hosts won't allow accesses to hardware devices mapped
outside the 1MB range without special DPMI calls.

So, to summarize: there is no ``Later'' version of DJGPP v2.01.