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Date: Wed, 25 May 2011 15:51:26 +0100
From: Daniel Haid <d.haid@gogi.tv>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: Question about iommu on =?UTF-8?Q?x=38=36=5F=36=34=20and=20ra?=
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>> I see. Now, maybe this will not work for some reason, but
>> would it be possible to somehow disable both IOMMU and SWIOTLB
>> and tell all drivers only to do DMA with the lower 4GB of memory?
>
> Only if you allow 3GB or less in the machine. So you would have to do
> mem=3G as well.
>
> The reason is that (and you can see that yourself by looking at the
> E820), is that 1GB is actually _above_ the 4GB.

 I see. Is it possible to somehow give "mem=3G" to the kernel and still
 use the memory above 4G for something, like a ramdisk or something?
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