Date: Thu, 24 May 2007 11:08:27 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Robert Hancock <hancockr@shaw.ca>
Cc: "Salyzyn, Mark" <mark_salyzyn@adaptec.com>,
       James Bottomley <James.Bottomley@SteelEye.com>,
       Aubrey Li <aubreylee@gmail.com>, Christoph Lameter <clameter@sgi.com>,
       Bernhard Walle <bwalle@suse.de>, linux-scsi@vger.kernel.org,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [scsi] Remove __GFP_DMA
Message-ID: <20070524110827.65e49b78@the-village.bc.nu>
In-Reply-To: <46552292.3090207@shaw.ca>
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> > That didn't used to work right on the AMD boards when I tried it last as
> > we ended up with a buffer that was mapped by the IOMMU for some reason
> > and that was not below 2GB.
> 
> The physical address you mean? If that is still happening then it needs 
> to get fixed. The allocation should not succeed if it can't provide 
> memory that's inside the DMA mask for the device..

But the allocation can succeed - using GFP_DMA at least you can do it as
you get memory below 2^24 you don't need to map via the IOMMU
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