Date:	Tue, 10 Nov 1998 10:27:44 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	KECSKEMÉTI BALÁZS <balazs AT tiszanet DOT hu>
cc:	djgpp AT delorie DOT com
Subject:	Re: a bunch of not so newbie questions ( i think )
In-Reply-To:	<7240rt$bdj$1@pollux.matav.net>
Message-ID:	<Pine.SUN.3.91.981110102722.26796I-100000@is>
MIME-Version:	1.0
X-MIME-Autoconverted:	from QUOTED-PRINTABLE to 8bit by delorie.com id DAA04995
Reply-To:	djgpp AT delorie DOT com

On Sun, 8 Nov 1998, KECSKEMÉTI BALÁZS wrote:

> 1) What's in the segment registers under DJGPP?

Protected-mode selectors.  DS holds the selector for the data segment,
CS holds the selector for the code segment, etc.

> I guess that there is a constant value, because i
> measured that pointers under DJGPP are 32 bits.

They are constant as long as the code produced by GCC runs (interrupts
and exceptions change that), and as long as you don't change them in
your code.  The segmented architecture of x86 is still with you, even
in protected mode, it's just that there's much less reason to change
segments, since they are so large.  But sometimes, like when accessing
DOS memory, you need to use a different selector even in protected
mode.

> 2) If i allocate some (DOS) memory in an external assembly
> function, then how do i access it in the C program?

This is in the FAQ (section 18.4).  You need to use special functions
like _farpeekb or dosmemget/dosmemput.  The FAQ (v2/faq211b.zip from
the same place you get DJGPP) explains a whole lot more details about
this.

> Anyway, what's a page fault _exactly? What are the possible
> causes of it?

This is explained in section 12.2 of the FAQ.

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