Something has broken MTU functionality in Xen: specifically,
setting MTUs larger than 1500 fails. This prevents Jumbo Frames and other
features which require larger than 1500 byte MTUs from being used. This can
lead to a failure to sync/connect to other components in the cluster/cloud
which expect higher MTUs and result in unavailable services.
The issue is caused by the following commit to the xen-netfront driver:
"xen-netfront: Fix race between device setup and open"
commit f599c64fdf7d9c108e8717fb04bc41c680120da4
The following commits fix this issue in the mainline kernel:
"xen-netfront: Fix mismatched rtnl_unlock"
commit cb257783c2927b73614b20f915a91ff78aa6f3e8
"xen-netfront: Update features after registering netdev"
commit 45c8184c1bed1ca8a7f02918552063a00b909bf5
