From: Oliver Xymoron <oxymoron@waste.org>
To: Jeff Garzik <jgarzik@mandrakesoft.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Linux Kernel List <linux-kernel@vger.rutgers.edu>,
linux-mm@kvack.org
Subject: Re: Getting big areas of memory, in 2.3.x?
Date: Wed, 8 Dec 1999 23:22:05 -0600 (CST) [thread overview]
Message-ID: <Pine.LNX.4.10.9912082311040.29662-100000@waste.org> (raw)
In-Reply-To: <384F17BA.174B4C6D@mandrakesoft.com>
On Wed, 8 Dec 1999, Jeff Garzik wrote:
> Alan Cox wrote:
> >
> > > What's the best way to get a large region of DMA'able memory for use
> > > with framegrabbers and other greedy drivers?
> >
> > Do you need physically linear memory >
>
> Yes. For the Meteor-II grabber I don't think so, but it looks like the
> older (but mostly compatible) Corona needs it.
Most PCI DMA controllers can send you an end of transfer interrupt, at
which point you can hand it the next contiguous segment to transfer to -
software scatter-gather. Note that the number of segments (fragments)
could very well be far fewer than the number of pages, meaning the
overhead could be pretty minimal, providing the latency doesn't kill you.
If the card has an NT driver, it almost certainly can be made to do this,
as NT has no support for allocating large physically contiguous memory
from drivers and pretty much forces this model.
--
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next prev parent reply other threads:[~1999-12-09 5:22 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-12-09 1:03 Jeff Garzik
1999-12-09 2:28 ` Alan Cox
1999-12-09 2:45 ` Jeff Garzik
1999-12-09 5:22 ` Oliver Xymoron [this message]
1999-12-09 12:25 ` Ingo Molnar
1999-12-09 20:24 ` Jeff Garzik
1999-12-09 20:31 ` Kanoj Sarcar
1999-12-09 20:39 ` Rik van Riel
1999-12-09 20:54 ` Kanoj Sarcar
1999-12-09 23:21 ` Ingo Molnar
1999-12-09 22:27 ` Kanoj Sarcar
1999-12-09 23:16 ` Ingo Molnar
1999-12-09 23:09 ` Benjamin C.R. LaHaise
1999-12-10 0:44 ` Ingo Molnar
1999-12-10 0:18 ` William J. Earl
1999-12-11 19:56 ` Stephen C. Tweedie
1999-12-10 12:21 ` Rik van Riel
1999-12-10 13:42 ` Ingo Molnar
1999-12-10 18:04 ` William J. Earl
1999-12-09 20:50 ` William J. Earl
1999-12-09 23:15 ` Ingo Molnar
1999-12-09 22:13 ` William J. Earl
1999-12-09 22:26 ` Alan Cox
1999-12-09 23:42 ` William J. Earl
1999-12-09 23:50 ` Alan Cox
1999-12-10 0:30 ` William J. Earl
1999-12-10 0:37 ` Alan Cox
1999-12-10 4:19 ` Oliver Xymoron
1999-12-10 10:14 ` Thomas Sailer
1999-12-09 23:24 ` Ingo Molnar
1999-12-09 22:33 ` Jeff Garzik
1999-12-09 23:32 ` Rogier Wolff
1999-12-09 23:44 ` JF Martinez
1999-12-10 0:52 ` Ingo Molnar
1999-12-09 23:46 ` Andi Kleen
1999-12-10 13:52 ` Stephen C. Tweedie
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