From: Joerg Roedel <joerg.roedel@amd.com>
To: Scott Wood <scottwood@freescale.com>
Cc: Joerg Roedel <joro@8bytes.org>,
Sethi Varun-B16395 <B16395@freescale.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
Ohad Ben-Cohen <ohad@wizery.com>,
Tony Lindgren <tony@atomide.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Wood Scott-B07421 <B07421@freescale.com>,
David Brown <davidb@codeaurora.org>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH 2/5] iommu/amd: Implement DOMAIN_ATTR_GEOMETRY attribute
Date: Mon, 30 Jan 2012 15:24:24 +0100 [thread overview]
Message-ID: <20120130142424.GR19255@amd.com> (raw)
In-Reply-To: <4F2315A3.80909@freescale.com>
On Fri, Jan 27, 2012 at 03:22:43PM -0600, Scott Wood wrote:
> OK, so there's a geometry that is read-only, and potentially a
> driver-specific geometry that is read/write. The default config for
> PAMU would likely be a 1 MiB aperture in which the dma api can do
> arbitrary 4k mappings -- this fits within the get generic geometry
> operation.
Better: There is a read-only geometry for _all_ IOMMUs. Some IOMMUs may
also allow to write the geometry, like PAMU.
> Should generic get geometry return an error if the driver-specific
> geometry has been set to something that doesn't fit within the generic
> geometry model?
A domain can only have one geometry. So if you set a new geometry
subsequent calls to get_attr will return the new geometry.
> I said a generic attribute (not GART specific) -- but if we're never
> going to use the generic geometry struct for a set operation, bundling
> it should be OK.
The generic struct should be used to set the geometry. But you can read
out the old geometry and set force_aperture to the same value in the new
geometry. Drivers should actually return -EINVAL when the user tries to
set an unsupported value for force_aperture.
> No, at this point I'm just trying to follow the API development while
> tending to other tasks. I think Varun is working on the code for now.
Okay, maybe it is better to follow a 'release early, release often'
model here. So we can work out the issues together.
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
next prev parent reply other threads:[~2012-01-30 14:24 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-19 14:30 [PATCH 0/5] IOMMU: Make IOMMU-API ready for GART-like hardware Joerg Roedel
2012-01-19 14:30 ` [PATCH 1/5] iommu: Add domain-attribute handlers Joerg Roedel
2012-01-19 14:30 ` [PATCH 2/5] iommu/amd: Implement DOMAIN_ATTR_GEOMETRY attribute Joerg Roedel
2012-01-19 15:46 ` Laurent Pinchart
2012-01-19 16:07 ` Joerg Roedel
2012-01-19 16:27 ` Laurent Pinchart
2012-01-20 5:44 ` Hiroshi Doyu
2012-01-20 16:01 ` Joerg Roedel
2012-02-01 9:37 ` Sethi Varun-B16395
2012-01-26 18:26 ` Scott Wood
2012-01-19 17:16 ` Sethi Varun-B16395
2012-01-20 16:03 ` Joerg Roedel
2012-01-26 18:25 ` Scott Wood
2012-01-26 18:31 ` Joerg Roedel
2012-01-26 18:42 ` Scott Wood
2012-01-26 18:51 ` Joerg Roedel
2012-01-26 19:00 ` Scott Wood
2012-01-26 19:44 ` Joerg Roedel
2012-01-26 20:02 ` Scott Wood
2012-01-27 11:01 ` Joerg Roedel
2012-01-27 21:22 ` Scott Wood
2012-01-30 14:24 ` Joerg Roedel [this message]
2012-01-30 20:21 ` Scott Wood
2012-01-30 6:27 ` Sethi Varun-B16395
2012-01-30 14:30 ` Joerg Roedel
2012-01-19 14:30 ` [PATCH 3/5] iommu/vt-d: " Joerg Roedel
2012-01-19 14:30 ` [PATCH 4/5] iommu/omap: " Joerg Roedel
2012-01-19 14:30 ` [PATCH 5/5] iommu/msm: " Joerg Roedel
2012-01-20 6:14 ` [PATCH 0/5] IOMMU: Make IOMMU-API ready for GART-like hardware Hiroshi Doyu
2012-01-20 16:05 ` joerg.roedel
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