Re: [virtio-dev] [PATCH v8] virtio-net: add Max MTU configuration field

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 09/04/2016 07:50 PM, Michael S. Tsirkin wrote:
> On Sun, Sep 04, 2016 at 10:31:09AM -0400, Aaron Conole wrote:
> > > It is helpful for a host to indicate an advisory MTU value to be set
> > > on guest's NICs other than the assumed 1500 byte value.
> This part of the description is wrong now.
> It is no longer advisory and it should say "to indicate its MTU value".
>
> > > This helps in
> > > situations where the host network is using Jumbo Frames, or aiding in
> > > PMTU discovery by configuring a homogenous network.
> Maybe add
> ...  It is also helpful for sizing receive buffers correctly.
Agree with Michael, I had this is in mind when looking at the 
implementation.


> > > The change adds a new field to configuration area of network
> > > devices.  It will be used to pass a maximum MTU from the device to
> > > the driver.  This will be used by the driver as a maximum value for
> > > packet sizes during transmission, without segmentation offloading.
> > >
> > > In addition, in order to support backward and forward compatibility,
> > > we introduce a new feature bit called VIRTIO_NET_F_MTU.
> > >
> > > Signed-off-by: Aaron Conole <aconole@redhat.com>
> > > Cc: Victor Kaplansky <victork@redhat.com>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>

FWIW:
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime