On 5 January 2015 at 09:05, Luigi Rizzo <[email protected]> wrote: > On Mon, Jan 05, 2015 at 08:33:17AM -0800, Adrian Chadd wrote: >> ... surely virtio should be skipping over those bytes in the netmap rx >> side before handing them up? >> >> (It won't be the only hardware that puts the RX descriptor status in >> the RX frame itself..) > > it is not the rx descriptor, those 12 bytes are also present on the tx side. > Think of them as an encapsulation whose presence is negotiated when KVM > connects > to the TAP port, and after that is present on all packets bidirectionally. > > Now, surely we could add/remove those bytes in the virtio-netmap code > (at the price of an additional data copy).
Right, but I have similar issues with other wifi devices who put RX descriptor completion info in the header of the mbuf you pass to the NIC. So in the driver RX path, I have to += the data pointer /past/ the header. So, maybe for netmap you need to consider adding something that lets you specify how many bytes into the RX buffer the payload starts. -adrian _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[email protected]"
