On 2017年01月05日 02:57, John Fastabend wrote:
[...]
On 2017年01月04日 00:48, John Fastabend wrote:
On 17-01-02 10:14 PM, Jason Wang wrote:
On 2017年01月03日 06:30, John Fastabend wrote:
XDP programs can not consume multiple pages so we cap the MTU to
avoid this case. Virtio-net however only checks the MTU at XDP
program load and does not block MTU changes after the program
has loaded.
This patch sets/clears the max_mtu value at XDP load/unload time.
Signed-off-by: John Fastabend <john.r.fastab...@intel.com>
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[...]
OK so this logic is a bit too simply. When it resets the max_mtu I guess it
needs to read the mtu via
virtio_cread16(vdev, ...)
or we may break the negotiated mtu.
Yes, this is a problem (even use ETH_MAX_MTU). We may need a method to notify
the device about the mtu in this case which is not supported by virtio now.
Note this is not really a XDP specific problem. The guest can change the MTU
after init time even without XDP which I assume should ideally result in a
notification if the MTU is negotiated.
Yes, Michael, do you think we need add some mechanism to notify host
about MTU change in this case?
Thanks
