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Subject: Re:  [RFT][PATCH] generic device DMA implementation
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: "Adam J. Richter" <adam@yggdrasil.com>
Cc: manfred@colorfulllife.com, dvaid-b@pacbell.net,
       James.Bottomley@steeleye.com,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: 30 Dec 2002 00:45:54 +0000
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On Sat, 2002-12-28 at 03:39, Adam J. Richter wrote:
> 	I know Documentation/DMA-mapping.txt says that, and I
> understand that wmb() is necessary with consistent memory, but I
> wonder if rmb() really is, at least if you've declared the data
> structures in question as volatile to prevent reordering of reads by
> the compiler.

Compiler ordering != Processor to memory ordering != PCI device view
ordering

volatile may not be enough.

Alan

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