From:	Doug Otis <dotis AT aponet DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Is there a function to convert a pointer to its physical location?
Date:	Mon, 02 Mar 1998 20:32:49 -0800
Organization:	Association for the Prevention of Polar Bears and Kangaroos
Lines:	14
Message-ID:	<34FB87F1.2BD0A6AC@aponet.com>
NNTP-Posting-Host:	192.83.249.18
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I wish to convert pointers to a true physical location within memory.
The PCI bus sees only the physical memory whereas the processor hides
the true location with the MMU.  Unlike DMA, the PCI bus allows access
to more than the DOS memory space.  Does anyone have a DPMI interface
that does not use the MMU so that the translation would be just base +
offset?  Is there a function that has access to the Page Directory and
Page Table to perform the translation under DJGPP?  At first blush, it
seems possible to disable paging if only one program (DOS) uses the VM
mode.  You would save the cycles changing pages and make the translation
duck soup.

TIA,
Doug

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