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From: Joerg Roedel <joro@8bytes.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>, Kukjin Kim <kgene@kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Heiko Stuebner <heiko@sntech.de>, Hiroshi Doyu <hdoyu@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Robin Murphy <Robin.Murphy@arm.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	"jroedel@suse.de" <jroedel@suse.de>
Subject: Re: [PATCH 2/5] iommu: Allocate a default domain for iommu groups
Date: Fri, 30 Jan 2015 13:25:30 +0100	[thread overview]
Message-ID: <20150130122530.GB3702@8bytes.org> (raw)
In-Reply-To: <20150128143006.GQ1569@arm.com>

On Wed, Jan 28, 2015 at 02:30:06PM +0000, Will Deacon wrote:
> On Tue, Jan 27, 2015 at 12:08:56AM +0000, Joerg Roedel wrote:
> > +	if (group->default_domain == NULL)
> > +		group->default_domain = __iommu_domain_alloc(dev->bus,
> > +							     IOMMU_DOMAIN_DMA);
> 
> Having a per-group domain is wasteful for IOMMUs that only support a modest
> number of concurrent domains, so in reality I think we need to have one
> domain per IOMMU instance. Is that possible?

Well, you could make sure that there are no more groups behind one IOMMU
than the number of concurent domains it can handle. But that would be
too static. But once we have an per-iommu-descriptor in the IOMMU core I
see no reason to allocate a default domain per iommu only, based on a
policy exported by the driver.


	Joerg


  parent reply	other threads:[~2015-01-30 12:25 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-27  0:08 [RFC PATCH 0/5] iommu: Introduce default domains " Joerg Roedel
2015-01-27  0:08 ` [PATCH 1/5] iommu: Add default domain to iommu-groups Joerg Roedel
2015-01-27  0:08 ` [PATCH 2/5] iommu: Allocate a default domain for iommu groups Joerg Roedel
2015-01-28 14:30   ` Will Deacon
2015-01-28 15:11     ` Robin Murphy
2015-01-30 12:25     ` Joerg Roedel [this message]
2015-01-27  0:08 ` [PATCH 3/5] iommu: Limit iommu_attach/detach_device to devices with their own group Joerg Roedel
2015-01-28 14:35   ` Will Deacon
2015-01-30 12:28     ` Joerg Roedel
2015-02-02 16:45       ` Will Deacon
2015-02-03 12:25   ` Thierry Reding
2015-02-03 12:59     ` Joerg Roedel
2015-01-27  0:08 ` [PATCH 4/5] iommu: Make sure a device is always attached to a domain Joerg Roedel
2015-01-28 14:38   ` Will Deacon
2015-01-30 12:29     ` Joerg Roedel
2015-01-27  0:08 ` [PATCH 5/5] iommu: Add iommu_get_domain_for_dev function Joerg Roedel

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