hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
hdr->csum_start = gho.l4_hdr_offset; // 0x22;
if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
hdr->csum_start = gho.l4_hdr_offset; // 0x22;
if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)