hi In netback netif_be_start_xmit() if (!netif->copying_receiver || ((skb_headlen(skb) + offset_in_page(skb->data)) >= PAGE_SIZE)) { struct sk_buff *nskb = netbk_copy_skb(skb); which calls skb_copy_bits() it means when rx-flip, the skb data and frags are copied to another buffer. then the buffer flip with domU''s pages. so before page flip with domU, copying happens in dom0. Does rx-flip make any sense? _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel