From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthew Wilcox <matthew@wil.cx>
Date: Wed, 27 Sep 2006 16:15:26 +0000
Subject: Re: __get_free_pages() problem on ia64
Message-Id: <20060927161526.GR5017@parisc-linux.org>
List-Id: <linux-ia64.vger.kernel.org>
References: <1159283801.4407.16.camel@triumph>
In-Reply-To: <1159283801.4407.16.camel@triumph>
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To: linux-ia64@vger.kernel.org

On Wed, Sep 27, 2006 at 09:11:37AM -0700, Luck, Tony wrote:
> > > Ok, thanks, I will look into it. But the question is why do I get
> > > addresses beyond 4G (virt_to_phys() of returned addresses) even when I
> > > use GFP_DMA. Is this a known problem on ia64?
> >
> > All memory is DMAable as we have an IOMMU.  ZONE_DMA doesn't mean what
> > you think it means.
> 
> You have an IOMMU ... but not all ia64 systems do (hence the need for swiotlb).

>From the device driver's point of view, all ia64 systems have an IOMMU,
whether it be implemented in hardware (all sane systems) or software
(Intel ones).