On Wed, 23 Aug 2017 11:30:26 +0200 Olivier MATZ <olivier.m...@6wind.com> wrote:
> Hello, > > On Sat, Jul 08, 2017 at 11:12:22AM +0800, Yuanhan Liu wrote: > > On Fri, Jul 07, 2017 at 12:52:48PM -0700, Stephen Hemminger wrote: > > > While doing code for Hyper-V, noticed that the virtio driver was > > > confused about receive versus transmit offloads. The virtio > > > checksum offload is L4 (TCP/UDP) only, not IPv4. Also, TSO > > > and LRO are not the same. > > > > > > This may break some program that was assuming it was getting offloads > > > that it wasn't. > > > > Applied to dpdk-next-virtio. > > > > And I think they should be backported to stable releases, thus, > > > > Cc: sta...@dpdk.org > > > > Thanks. > > > > --yliu > > > > > > Stephen Hemminger (2): > > > virtio: don't falsely claim to do IP checksum > > > virtio: don't claim to support LRO > > > > > > drivers/net/virtio/virtio_ethdev.c | 30 +++++------------------------- > > > 1 file changed, 5 insertions(+), 25 deletions(-) > > > > > > -- > > > 2.11.0 > > I think these 2 commits break the virtio offload, which can be tested as > described in this test plan: > http://dpdk.org/ml/archives/dev/2016-October/048092.html > > First, about checksum: the description of rxmode->hw_ip_checksum is: > > hw_ip_checksum : 1, /**< IP/UDP/TCP checksum offload enable. */ > > So, while I agree the name is not well chosen, it is valid to set it > for virtio to enable L4 checksum. > > Then about LRO: setting rxmode->enable_lro is a way to tell the host that the > guest is ok to receive tso packets. From the guest point of view, it is like > enabling lro on a physical driver. Again, it is valid and useful to do this. > > Before removing these features, it would have been nice to have a quick look > at > the commits that introduced them. I am ok with keeping LRO as long as the documentation changed. And virtio driver did some enforcement. For checksums, the hw_ip_checksum flag either needs to be more fine grain (IP, UDP, TCP) which would be best, or virtio would have to check IP checksum in software.
