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Date: Thu, 18 Jun 2009 21:08:35 +0300
From: Muli Ben-Yehuda <muli@il.ibm.com>
To: Fenghua Yu <fenghua.yu@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
       "'Linus Torvalds'" <torvalds@linux-foundation.org>,
       "'Stephen Rothwell'" <sfr@canb.auug.org.au>,
       "'Andrew Morton'" <akpm@linux-foundation.org>,
       "'Ingo Molnar'" <mingo@elte.hu>,
       "'Christopher Wright'" <chrisw@redhat.com>,
       "'Allen Kay'" <allen.m.kay@intel.com>,
       "'lkml'" <linux-kernel@vger.kernel.org>,
       "'iommu'" <iommu@lists.linux-foundation.org>
Subject: Re: [PATCH 1/2] IOMMU Identity Mapping Support:
	iommu_identity_mapping definition
Message-ID: <20090618180835.GB6838@il.ibm.com>
References: <20090327212241.234500000@intel.com> <20090327212321.070229000@intel.com> <20090416001957.GA1527@linux-os.sc.intel.com> <1240135508.3589.75.camel@macbook.infradead.org> <A6AD88C3F2289247BE726C37303E1EB8A4DF7DB1@orsmsx505.amr.corp.intel.com> <20090513231351.GA22386@linux-os.sc.intel.com> <1242314271.3393.11.camel@macbook.infradead.org> <20090514175944.GA5168@linux-os.sc.intel.com> <20090618180514.GA24082@linux-os.sc.intel.com>
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On Thu, Jun 18, 2009 at 11:05:14AM -0700, Fenghua Yu wrote:

> IOMMU Identity Mapping Support: iommu_identity_mapping definition
> 
> Identity mapping for IOMMU defines a single domain to 1:1 map all
> pci devices to all usable memory.

Why use VT-d at all in this case? Do you have a use-case in mind?

Cheers,
Muli

> This method may lose some of DMA remapping benefits like isolation.

I think you meant s/may/will/.

Cheers,
Muli
-- 
Muli Ben-Yehuda | muli@il.ibm.com | +972-4-8281080
Manager, Virtualization and Systems Architecture
Master Inventor, IBM Haifa Research Laboratory