On 16 October 2012 09:59, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote: > On Tue, Oct 16, 2012 at 09:04:34AM +0300, Hiroshi Doyu wrote: >> In addition to those contiguous/discontiguous page allocation, is >> there any way to _import_ anonymous pages allocated by a process to be >> used in dma-mapping API later? >> >> I'm considering the following scenario, an user process allocates a >> buffer by malloc() in advance, and then it asks some driver to convert >> that buffer into IOMMU'able/DMA'able ones later. In this case, pages >> are discouguous and even they may not be yet allocated at >> malloc()/mmap(). > > That situation is covered. It's the streaming API you're wanting for that. > dma_map_sg() - but you may need additional cache handling via > flush_dcache_page() to ensure that your code is safe for all CPU cache > architectures. For user-allocated pages you first need get_user_pages() to make sure they are in memory (and will stay there). This function also calls flush_dcache_page(). Then you can build the sg list for dma_map_sg(). -- Catalin -- 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>