Hi all, It seems like OpenVZ has had TCP Segmentation Support for veth for quite a while[1], but the mainline kernel doesn't have it. I checked what it takes to add TSO support, and it looks like OpenVZ's veth.c (call it vzeth) has the following: 1. When initialising a virtual net_device "dev", vzeth declares dev->hw_features = ... (other features) | NETIF_F_TSO. 2. The ethtool_ops structure contains two additional handlers: get_tso and set_tso. 3. get_tso points to ethtool_op_get_tso 4. set_tso points to a special function, that invokes ethtool_op_set_tso on both the ends of the vzeth. I took a copy of the mainline veth.c, repeated the above steps and introduced a printk to make sure that the set_tso function gets invoked. Here's the diff: http://pastie.org/2924399 (space indent, sorry) But I see the following: 1. The modified veth driver loads. (good) 2. When I do: ethtool -K <iface> tso on, I don't see an error message. (good) 3. When I query: ethtool -k <iface>, I don't see TSO set on (bad) 4. When I check dmesg, I don't see that the "set_tso" function has not been invoked. (bad) Am I doing something wrong? [1] http://wiki.openvz.org/TSO -- Vimal