Hi Russell, Russell King - ARM Linux <li...@arm.linux.org.uk> wrote @ Tue, 16 Oct 2012 10:59:28 +0200:
> 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. Is the syscall "cacheflush()" supposed to be the knob for that? Or is there any other ones to have more precise control, "clean", "invalidate" and "flush", from userland in generic way? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
