[Xen-devel] Re: [PATCH 00 of 14] swiotlb/x86: lay groundwork for xen dom0 use of swiotlb

[Ingo Molnar <mingo@xxxxxxx>]

* Becky Bruce <beckyb@xxxxxxxxxxxxxxxxxxx> wrote:

>> Can you be more specific? What architecture is plan to use highmem 
>> support in swiotlb?
>
> 32-bit powerpc needs this support - I was actually about to push a 
> similar set of patches.  We have several processors that support 36 bits 
> of physical address space and do not have any iommu capability.  The 
> rest of the kernel support for those processors is now in place, so 
> swiotlb is the last piece of the puzzle for that to be fully functional.  
> I need to take a closer look at this series to see exactly what it's 
> doing and how it differs from what I've been testing.
>
> So there is another immediate use case, and I'd really hate to see this 
> code duplicated.  It should be entirely possible to remove the 
> assumption that we can save off the VA of the original buffer, which is 
> the thing that precludes HIGHMEM support, and still have nice readable, 
> maintainable code.

you can have a look at Jeremy's current lineup of patches in 
tip/core/iotlb:

   http://people.redhat.com/mingo/tip.git/README

(also integrated into tip/master)

What would be needed to make it suit your usecase too?

        Ingo

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