Re: [Qemu-devel] [PATCH 2/6] PCI DMA API

[Anthony Liguori <aliguori@us.ibm.com>]

Blue Swirl wrote:
> On 3/30/08, Anthony Liguori <aliguori@us.ibm.com> wrote:
>   
>> This patch introduces a PCI DMA API and some generic code to support other DMA
>>  APIs.  Two types are introduced: PhysIOVector and IOVector.  A DMA API
>>  maps a PhysIOVector, which is composed of target_phys_addr_t, into an IOVector,
>>  which is composed of void *.
>>     
>
> This looks like it wouldn't scale to handle the Sparc systems. There
> we want to make more translation steps from DVMA addresses to physical
> in DMA controller and IOMMU and only in the final stage to void *. To
> handle this, probably there should be an opaque parameter and some way
> to register the translation function. Otherwise the API looks OK.
>   

I think having the PCI DMA API translate PhysIOVector => PhysIOVector 
would help.  Then it becomes pretty easy to just call the DMA controller 
for additional translation from the IOMMU.

Does that sound right?  I don't quite understand what role the opaque 
parameter would serve.

Regards,

Anthony Liguori