On Wed, Sep 14, 2016 at 12:15:37PM +0000, Kavanagh, Mark B wrote:
> >
> >>+{
> >>+?????? struct rte_eth_dev_info dev_info;
> >>+?????? uint32_t ether_hdr_len = ETHER_HDR_LEN + ETHER_CRC_LEN +
> >>+VLAN_TAG_LEN;
> >>+?????? uint32_t frame_size = mtu + ether_hdr_len;
> >>+
> >>+?????? virtio_dev_info_get(dev, &dev_info);
> >>+
> >>+?????? if (mtu < dev_info.min_rx_bufsize || frame_size >
> >>+dev_info.max_rx_pktlen) {
> >
> >It's not clear to me whether 'mtu' in this case should be compared with
> >ETHER_MIN_MTU, as per
> >other DPDK drivers, or alternatively whether 'frame_size' should be compared
> >with
> >dev_info.min_rx_bufsize.
> >Any thoughts?
> >[Dey, Souvik] I am not sure why virtio min_rx_bufsize is less than
> >ETHER_MIN_MTU, i think it
> >will be good to have the compare statement as
> >If(frame_size < ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktlen) , then
> >error. What do
> >you suggest ?
>
> Again, this all depends on what 'mtu' means in this context.
>
> Since you mentioned previously that it relates to the packet (i.e. L3)
> length, and not the frame (i.e. L2) length, I would suggest that the
> comparison should be:
>
> if (mtu < ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktlen)
>
> Yuanhan, any thoughts on this?
I think you are right. At least, that's how the ixgbe PMD driver code
looks like.
--yliu
