On Fri, 2012-12-21 at 22:56 +0100, John Crispin wrote: > > So the ATM driver would have to go out of its way to screw you over¹. > John? > > the lantiq atm/dsl drivers use a dma ring to push packets from the atm > layer to the dsl modem core. this ring needs to be 2 packets big as a > minimum to have the hardware work. however, using software we can make > sure that only 1 packet at a tim eis inside the ring. this is what my > current dirty hack does. You shouldn't need that hack any more. With the current core ATM code you should only have two packets in the queue anyway — the one the hardware is *currently* working on, and the next one ready to be sent (which is necessary to avoid introducing too much latency between packets. Your ADSL uplink is *very* limited, and you really want to be sure you're using it *all*). -- dwmw2