Fix verified in Xenial linux (4.4.0-131.157) and Xenial linux-aws (4.4.0-1063.72).
** Tags removed: verification-needed-xenial ** Tags added: verification-done-xenial -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1781413 Title: Cannot set MTU higher than 1500 in Xen instance Status in linux package in Ubuntu: Incomplete Status in linux source package in Xenial: Fix Committed Status in linux source package in Bionic: Fix Committed Bug description: [Impact] The latest Xenial update 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. This can be worked around by manually using ethtool to set SCATTER/GATHER functionality: - $ sudo ethtool -K $interface_name sg on The issue is caused by the following commit to the xen-netfront driver: "xen-netfront: Fix race between device setup and open" commit f599c64fdf7d9c108e8717fb04bc41c680120da4 Introduced: v4.16-rc1 Reverting the above fix has confirmed that the problem goes away. The following commits fix this issue in the mainline kernel: "xen-netfront: Fix mismatched rtnl_unlock" commit cb257783c2927b73614b20f915a91ff78aa6f3e8 Introduced: v4.18-rc3 "xen-netfront: Update features after registering netdev" commit 45c8184c1bed1ca8a7f02918552063a00b909bf5 Introduced: v4.18-rc3 [Test Case] 1. Launch a Xen instance using the latest kernel version (e.g. 4.4.0-130, or 4.4.0-1062-aws) 2. Change MTU to 9000 or other value > 1500. [Regression Potential] The kernel patch might not be able to set MTU. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1781413/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
