Re: [RFC 0/6] iommu: generic api migration and grouping

Ohad Ben-Cohen
2011-06-06T15:15:55Z

Hi Joerg,

On Mon, Jun 6, 2011 at 1:09 PM, Roedel, Joerg <Joerg.Roedel@amd.com> wrote:
> The IOMMU-API already supports multiple page-sizes. See the
> 'order'-parameter of the map/unmap functions.

This is insufficient; users need somehow to tell what page sizes are
supported by the underlying hardware (we can't assume host page-sizes,
and we want to use bigger pages whenever possible, to relax the TLB
pressure).

>>   Further generalizing of iovmm strongly depends on our broader plans for
>>   providing a generic virtual memory manager and allocation framework
>>   (which, as discussed, should be separated from a specific mapper).
>
> The generic vmm for DMA is called DMA-API :) Any reason for not using
> that (those reasons should be fixed)?

This is definitely something we will look into (dspbridge will need it
too, not only omap3isp).

Thanks,
Ohad.