Messages in this thread | | | Date | Tue, 03 Aug 2010 11:43:20 -0700 | From | Stepan Moskovchenko <> | Subject | Re: [PATCH 1/2] arm: msm: Add System MMU support. |
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On 8/3/2010 2:23 AM, Roedel, Joerg wrote: > On Mon, Aug 02, 2010 at 04:29:38PM -0400, Zach Pfeffer wrote: >> On Mon, Aug 02, 2010 at 09:58:02AM +0200, Roedel, Joerg wrote: >>> In the means of the IOMMU-API the domain is the abstraction of an >>> address space (in other words a page table). The IOMMU(s) which this domain >>> is later assigned to are determined by the iommu_attach_device calls. >>> I think the right way to go here is to create the concept of a >>> device-context in the IOMMU-API and add functions like >>> >>> iommu_attach_context(struct iommu_domain *domain, >>> struct iommu_context *ctxt); >>> iommu_detach_context(struct iommu_context *ctxt); >>> >>> This would work if you can determine in your iommu-driver which iommu >>> you need to program for which device. What do you think? >>> >> Joerg, I'd like to make sure I understand this. A domain is an address >> space separate from the actual page-tables that may be part of an >> iommu_context, correct? After I iommu_attach_context the ctxt will >> reflect the address space of the domain, correct? > A domain is defined by a single page-table which can be modified using > the iommu_map/iommu_unmap function calls. I am not completly sure what > you mean by an iommu_context. Can you describe what it means in your > context? > > Joerg >
Joerg, I think with some rework, all my use cases can be handled by your existing iommu API. If the domain is treated basically a page table, there will be some changes, but I think it can be done. I will push a new version of my driver in a few days.
One thing that may be helpful for the future, however, is maybe something like adding iommu_tlb_flush to the ops. I suppose this would either have to take a device, or the domain would need to keep a list of devices it had been attached to (so that their TLBs can be invalidated). But I suppose on the other hand, iommu_map/unmap may be able to just implicitly invalidate the TLB also, since TLB invalidation often follows map/unmap. What are your thoughts?
Thanks Steve
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