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. Remember that pages allocated into userspace will be cacheable, so a cache flush is required before they can be DMA'd. Hence the streaming API. -- 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>