On Tuesday 04 March 2008 16:08:00 Max Krasnyansky wrote: > > The problem with this approach is that for what I'm doing, the packets > > aren't nicely arranged somewhere; they're in random process memory. > > That's fine. RX/TX descriptors would not contain the data itself. They'd > contain pointers to actual packets (ie just like the NIC takes physical > memory address and DMAs data in/out). > The allows for sending/receiving packets without syscalls and fits nicely > with the async schemes like GSO.
Yes, yes it does. That would be a very nice extension (it's orthogonal to this patch though, so should we get Dave to take these for 2.6.25?). And as it happens, virtio already has such a structure: virtio_ring. See linux/virtio_ring.h. > > The structure is for virtio, I'm just borrowing it for tap because it's > > already there. We could rename it and move it out to its own header, but > > if so we should do that before 2.6.25 is released. > > If we do the whole enchilada with the RX/TX rings then we probably do not > even need it. I'm thinking that RX/TX descriptor would include everything > you need for the GSO and stuff. > I meant do not need it for the TUN/TAP driver that is. Is it used anywhere > else ? Just for the linux virtio drivers. Reusing it for tun/tap was an afterthought. It just meant I could pass the same structure straight thru, though, which is nice. The userspace->kernel problem is very similar to the guest->host problem, so it doesn't surprise me if we end up with very similar (identical?) interfaces. Take a look at virtio_ring.h, virtio_ring.c and Documentation/lguest/lguest.c to see how we use it... Cheers, Rusty. _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
