This series introduces XSK generic zerocopy xmit by adding XSK umem[...]
pages as skb frags instead of copying data to linear space.
The only requirement for this for drivers is to be able to xmit skbs
with skb_headlen(skb) == 0, i.e. all data including hard headers
starts from frag 0.
To indicate whether a particular driver supports this, a new netdev
priv flag, IFF_TX_SKB_NO_LINEAR, is added (and declared in virtio_net
as it's already capable of doing it). So consider implementing this
in your drivers to greatly speed-up generic XSK xmit.