From:	"Matt" <para AT tampabay DOT rr DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	DPMI problem
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Message-ID:	<bwS_6.65731$_T2.17269145@typhoon.tampabay.rr.com>
Date:	Fri, 29 Jun 2001 03:22:47 GMT
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

I have a game which accesses VGA memory (A000:0000) directly. In 16-bit
mode, that's ok, but to get it to run under DJGPP I either have to rewrite
the thing or map VGA memory to linear memory. There is a function to do
that, but I can only do it with a DPMI 1.0 server.

Is there a way to accomplish the same thing (i.e. direct linear access to
A000:0000 from my ds selector) with a DPMI 0.9 server? Right now I'm looking
at the following options, and neither of them look good:

1. Use __djgpp_nearptr_enable(). The documentation recommends against this,
and considering that I just overhauled a number of asm files and am aware of
a number of bugs already, I'm not so sure I like the thought of being able
to kill my system.
2. Use function 02h to map the segment to a descriptor, use function 06h to
locate the linear base of the descriptor, then use functions 07h and 08h to
modify my ds segment so I can read that linear address.

Is there any way to do it directly, or is there a DPMI 0.9 server which
supports function 0508h (map device -> linear)?

-Matt

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