On Mon, Feb 2, 2015 at 11:54 AM, Daniel Vetter <daniel@xxxxxxxx> 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>