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Xref: | news2.mv.net comp.os.msdos.djgpp:1204 |
From: | Charles Sandmann <sandmann AT clio DOT rice DOT edu> |
Newsgroups: | comp.os.msdos.djgpp |
Subject: | Re: how to allocate DMA pages ? |
Date: | Wed, 14 Feb 1996 23:24:26 CST |
Organization: | Rice University, Houston, Texas |
Lines: | 15 |
Message-ID: | <3122c38a.sandmann@clio.rice.edu> |
References: | <DMrv12 DOT B5G AT granite DOT mv DOT net> <4fu11h$5au AT news DOT manawatu DOT gen DOT nz> |
Reply-To: | sandmann AT clio DOT rice DOT edu |
NNTP-Posting-Host: | clio.rice.edu |
To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
> > Ulf> know of a good strategy for allocating DMA buffers which > > Ulf> works on large memory machines ? (Will take source code...) > >It is actually worse than this - the 8237 DMA controller takes > >physical addresses, malloc returns virtual addresses. There is > >currently no mechanism to translate malloc'ed virtual addresses into > >physical addresses with which to program the DMA controller. There is actually a standard called VDS out there which addresses this. See ftp.oulu.fi someplace in a standard directory for it (that means I don't remember where, and I'm not gonna go find it either). There is a good discussion on this topic in comp.lang.asm.x86 by the author of 386MAX right now. The bad news is that I never bothered to implement it for CWSDPMI (see all the bad things I never tell you about ;-) so you must use the XMS type solution (if you need LOTS of DMA buffers) or DOS memory if you can get by with it, or use something more professional :-)
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