Re: 3.6-rc7 boot crash + bisection

["Roedel, Joerg" <Joerg.Roedel-5C7GfCeVMHo@public.gmane.org>]

On Wed, Sep 26, 2012 at 08:35:59AM -0600, Alex Williamson wrote:
> Hmm, that throws a kink in iommu groups.  So perhaps we need to make an
> alias interface to iommu groups.  Seems like this could just be an extra
> parameter to iommu_group_get and iommu_group_add_device (empty in the
> typical case).  Then we have the problem of what's the type for an
> alias?  For AMI-Vi, it's a u16, but we need to be more generic than
> that.  Maybe iommu groups should just treat it as a void* so iommus can
> use a pointer to some structure or a fixed value like a u16 bus:slot.
> Thoughts?

Good question. The iommu-groups are part of the IOMMU-API, with an
interface to the IOMMU drivers and one to the users of IOMMU-API. So the
alias handling itself should be a function of the interface to the IOMMU
driver. In general the interface should not be bus specific.

So a void pointer seems the only logical choice then. But I would not
limit its scope to alias handling. How about making it a bus-private
pointer where IOMMU driver store bus-specific information. That way we
make sure that there is one struct per bus-type for this pointer, and
not one structure per IOMMU driver.


	Joerg

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