On Mon, 19 Jul 2010 09:22:13 +0100 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote: > > If I want to share the buffer with another device I have to > > make a copy of the entire thing then fix up the virtual mappings for > > the other device I'm sharing with. > > This is something the DMA API doesn't do - probably because there hasn't > been a requirement for it. > > One of the issues for drivers is that by separating the mapped scatterlist > from the input buffer scatterlist, it creates something else for them to > allocate, which causes an additional failure point - and as all users sit > well with the current API, there's little reason to change especially > given the number of drivers which would need to be updated. Agreed. There was the discussion about separating 'dma_addr and dma_len' from scatterlist struct but I don't think that it's worth doing so. > I'm just proving that it's not as hard as you seem to be making out. Agreed again. -- 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>