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From: Joerg Roedel <joerg.roedel@amd.com>
To: Ohad Ben-Cohen <ohad@wizery.com>
Cc: <iommu@lists.linux-foundation.org>,
	<linux-kernel@vger.kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	David Brown <davidb@codeaurora.org>,
	Tony Lindgren <tony@atomide.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Stuart Yoder <b08248@gmail.com>,
	Scott Wood <scottwood@freescale.com>,
	Hiroshi Doyu <hdoyu@nvidia.com>
Subject: Re: [PATCH 2/6] iommu/amd: Implement DOMAIN_ATTR_GEOMETRY attribute
Date: Mon, 30 Jan 2012 15:49:09 +0100	[thread overview]
Message-ID: <20120130144909.GT19255@amd.com> (raw)
In-Reply-To: <CAK=WgbY+aBwTno4YxGLaxS7Y-R=CS1604+c5j-6EMQSfJeGvTA@mail.gmail.com>

On Sat, Jan 28, 2012 at 10:44:22PM +0200, Ohad Ben-Cohen wrote:
> On Fri, Jan 27, 2012 at 3:03 PM, Joerg Roedel <joerg.roedel@amd.com> wrote:
> > Note that only the read-side is handled by the core. An IOMMU driver may
> > decide to implement a write-side for the geometry which would be not in
> > the core then. Having a dedicated function for the write-side does not
> > make sense because (for now) there is only one upcoming driver requiring
> > this.
> 
> I'd still go with a type-safe interface here, but maybe it's only me.

Well, the idea still stands to replace 'void *data' with something like
'union domain_attr *data'. This isn't as type-safe as dedicated
functions, but still better than void*.

> I'm not so sure how would drivers use these "hardware-specific api
> attr extensions" in general.

Depends on the attribute. For the geometry attribute drivers that
allocate a domain should read out the geometry and only use the range
returned for map/unmap (or fail initialization when the domain geometry
is unexpected).

> Is the intention that only hardware-specific drivers will use them ? I
> guess that generic drivers won't be able to use them, because their
> behavior will not be well-defined across all hardware implementations.

Hardware specific attributes are intended, but not limited to hardware
specific drivers. A generic driver that _may_ run on a given hardware
can use a hardware specific attribute too. If it doesn't run on this
hardware it will just get -EINVAL back.

Regards,

	Joerg

-- 
AMD Operating System Research Center

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632


  reply	other threads:[~2012-01-30 14:49 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-26 18:40 [PATCH 0/6 v2] IOMMU: Make IOMMU-API ready for GART-like hardware Joerg Roedel
2012-01-26 18:40 ` [PATCH 1/6] iommu: Add domain-attribute handlers Joerg Roedel
2012-01-26 18:40 ` [PATCH 2/6] iommu/amd: Implement DOMAIN_ATTR_GEOMETRY attribute Joerg Roedel
2012-01-27  7:08   ` Ohad Ben-Cohen
2012-01-27 10:26     ` Joerg Roedel
2012-01-27 11:00       ` Ohad Ben-Cohen
2012-01-27 13:03         ` Joerg Roedel
2012-01-28 20:44           ` Ohad Ben-Cohen
2012-01-30 14:49             ` Joerg Roedel [this message]
2012-01-30 15:42               ` Ohad Ben-Cohen
2012-01-26 18:40 ` [PATCH 3/6] iommu/vt-d: " Joerg Roedel
2012-01-26 18:40 ` [PATCH 4/6] iommu/omap: " Joerg Roedel
2012-01-26 18:40 ` [PATCH 5/6] iommu/msm: " Joerg Roedel
2012-01-27  0:07   ` David Brown
2012-01-26 18:40 ` [PATCH 6/6] iommu/tegra: " Joerg Roedel

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