Date: Wed, 27 Oct 2004 17:31:11 -0400
From: Jeff Garzik <jgarzik@pobox.com>
To: Andrew Morton <akpm@osdl.org>
Cc: mbligh@aracnet.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       bzolnier@gmail.com, rddunlap@osdl.org, wli@holomorphy.com,
       axboe@suse.de
Subject: Re: [PATCH] Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1)
Message-ID: <20041027213111.GA13627@havoc.gtf.org>
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On Wed, Oct 27, 2004 at 02:29:14PM -0700, Andrew Morton wrote:
> spose so.  The scatterlist API is being a bit silly there.

Well, it depends on your perspective :)

Each scatterlist entry is supposed to map to a physical segment to be
passed to h/w.  Hardware S/G tables just want to see a addr/len pair,
and don't care about machine page size.  scatterlist follows a similar
model.

dma_map_sg() and other helpers create a favorable situation, where >90%
of the drivers don't have to care about the VM-size details.
Unfortunately those drivers that need need to do their own data transfer
(like ATA's PIO, instead of DMA) need direct access to each member of an
s/g list.

	Jeff


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