From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [OSSTEST PATCH] ts-kernel-build: Enable x86 IOMMU
	options
Date: Tue, 21 Apr 2015 16:44:07 +0100
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To: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: xen-devel@lists.xenproject.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Andrew Cooper <andrew.cooper3@citrix.com>, David Vrabel <david.vrabel@citrix.com>
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On Tue, 2015-04-21 at 16:36 +0100, Ian Jackson wrote:
> This has a variety of beneficial implications:
> 
>  * The kernel becomes more like the kind of distro kernels that Xen
>    users are probably using.
> 
>  * We are more likely to discover any bugs in Linux where Linux
>    running under Xen (eg as dom0) fights with Xen for control of io
>    mediation resources or otherwise mishandles the situation.
> 
>  * A pleasant side effect is that in a kernel which does not yet have
>    "config: Enable NEED_DMA_MAP_STATE when SWIOTLB is selected"
>    (a bugfix), enabling INTEL_IOMMU has the side effect of enabling
>    NEED_DMA_MAP_STATE and thus working around the bug.
> 
> The list of options to enable was derived by eyeballing
> drivers/iommu/Kconfig from 3.14.34.
> 
> I will leave the question of whether to enable any ARM IOMMU options
> for the Xen ARM folks to consider.

I've not got time right now, but lets not block on that:

> Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: David Vrabel <david.vrabel@citrix.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>

Acked-by: Ian Campbell <ian.campbell@citrix.com>

Ian.