Re: [PATCH 2/5] iommu/amd: Implement DOMAIN_ATTR_GEOMETRY attribute

[Scott Wood <scottwood@freescale.com>]

On 01/20/2012 10:03 AM, Joerg Roedel wrote:
> On Thu, Jan 19, 2012 at 05:16:48PM +0000, Sethi Varun-B16395 wrote:
>>>  struct iommu_domain {
>>>  	struct iommu_ops *ops;
>>>  	void *priv;
>>>  	iommu_fault_handler_t handler;
>>> +	struct iommu_domain_geometry geometry;
>>>  };
>> In case of our iommu implementation the iommu_domain_geometry would
>> include additional attributes. Why can't we let the geometry be
>> Implementation dependent?
> 
> Because the values in this generic geometry-struct make sense for more
> than one IOMMU (short-term for Tegra GART and Freescale PAMU). If you
> have additional vendor-specific ones you could add them via a
> vendor-specific attribute.

Freescale PAMU is the IOMMU that Varun is talking about, that needs
additional geometry attributes (in particular, subwindow count).

How should a PAMU driver interpret "force_aperture"?  When would DMA
ever be allowed outside the specified range?  What does the range mean
in that case?

-Scott