On Mon, Feb 2, 2015 at 11:54 AM, Daniel Vetter daniel@ffwll.ch wrote:
My initial thought is for dma-buf to not try to prevent something than an exporter can actually do.. I think the scenario you describe could be handled by two sg-lists, if the exporter was clever enough.
That's already needed, each attachment has it's own sg-list. After all there's no array of dma_addr_t in the sg tables, so you can't use one sg for more than one mapping. And due to different iommu different devices can easily end up with different addresses.
Well, to be fair it may not be explicitly stated, but currently one should assume the dma_addr_t's in the dmabuf sglist are bogus. With gpu's that implement per-process/context page tables, I'm not really sure that there is a sane way to actually do anything else..
BR, -R