On Tue, 13 Jul 2010 09:20:12 +0100 Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote: > > Why video4linux can't use the DMA API? Doing DMA with vmalloc'ed > > buffers is a thing that we should avoid (there are some exceptions > > like xfs though). > > Vmalloc is about the only API for creating virtually linear memory areas. > The video stuff really needs that to avoid lots of horrible special cases > when doing buffer processing and the like. > > Pretty much each driver using it has a pair of functions 'rvmalloc' and > 'rvfree' so given a proper "vmalloc_for_dma()" type interface can easily > be switched We already have helper functions for DMA with vmap pages, flush_kernel_vmap_range and invalidate_kernel_vmap_range. I think that the current DMA API with the above helper functions should work well drivers that want virtually linear large memory areas (such as xfs). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>