Messages in this thread | | | Date | Tue, 9 Jun 2015 08:58:54 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH v4 9/9] x86: convert dma_map_ops to support mapping a __pfn_t. |
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On Fri, Jun 05, 2015 at 05:19:55PM -0400, Dan Williams wrote: > As long as a dma_map_sg() implementation avoids sg_page() conversions it > can support scatterlists that carry "page-less" __pfn_t entries. > However, a couple implementations require that __pfn_t_has_page() is > always true. The Xen swiotlb implementation's entanglements with ARM and > the Calgary MMUs requirement to have a pre-existing virtual mapping make > them unable to support this conversion (i.e. these now have 'depends on > !HAVE_DMA_PFN').
That's why we really need a whole kernel conversion and not just a piecemail one. Given how trivial this patch is that doesn't look like a too big task ayway.
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