Rick Jones [off-list ref] writes:

On 03/15/2016 02:04 PM, Aaron Conole wrote:

quoted

The following series adds the ability for a hypervisor to set an MTU on the
guest during feature negotiation phase. This is useful for VM orchestration
when, for instance, tunneling is involved and the MTU of the various systems
should be homogenous.

The first patch adds the feature bit as described in the proposed VFIO spec
addition found at
https://lists.oasis-open.org/archives/virtio-dev/201603/msg00001.html

The second patch adds a user of the bit, and a warning when the guest changes
the MTU from the hypervisor advised MTU. Future patches may add more thorough
error handling.

How do you see this interacting with VMs getting MTU settings via DHCP?

This is intended for networks where the VMs are not given MTU via
DHCP. I don't think it should negatively interfere with such a
network. Does that make sense?

-Aaron

rick jones

quoted

v2:
* Whitespace and code style cleanups from Sergei Shtylyov and Paolo Abeni
* Additional test before printing a warning

Aaron Conole (2):
   virtio: Start feature MTU support
   virtio_net: Read the advised MTU

  drivers/net/virtio_net.c        | 12 ++++++++++++
  include/uapi/linux/virtio_net.h |  3 +++
  2 files changed, 15 insertions(+)