Hello Dan, or anyone else affected,

Accepted nplan into artful-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/nplan/0.32~17.10.1 in
a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-artful to verification-done-artful. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-artful. In either case, details of your
testing will help us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: nplan (Ubuntu Artful)
       Status: In Progress => Fix Committed

** Tags removed: verification-done
** Tags added: verification-needed verification-needed-artful

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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/1729573

Title:
  netplan breaks Xen VIF driver

Status in linux package in Ubuntu:
  Won't Fix
Status in nplan package in Ubuntu:
  Fix Released
Status in linux source package in Xenial:
  Won't Fix
Status in nplan source package in Xenial:
  Fix Committed
Status in linux source package in Zesty:
  Won't Fix
Status in nplan source package in Zesty:
  Fix Committed
Status in linux source package in Artful:
  Won't Fix
Status in nplan source package in Artful:
  Fix Committed
Status in linux source package in Bionic:
  Won't Fix
Status in nplan source package in Bionic:
  Fix Released

Bug description:
  [Impact]

  Some network interfaces on a Xen guest are broken by new behavior
  introduced by netplan.  On a Xen guest instance, when netplan is run
  to 'apply' its configuration, under certain circumstances netplan will
  try to "reset" the interface by unbinding and then re-binding the
  interface driver from the interface, by using the sysfs "bind" and
  "unbind" functions of the driver.  Normally, this results in the
  interface being released and then fully re-initialized by the driver.

  However the Xen VIF driver breaks when this is done.  The internal Xen
  backend state of the interface remains in 'closed' state after the
  driver re-connects to the interface, and attempts to open and use the
  interface result in a kernel Oops in the Xen VIF driver.

  To users, it appears that the interface is unusable because it has an
  all 0 mac address; but if the mac is manually set and the interface
  brought up the driver Oopses as mentioned above.

  This problem makes booting painful because of very long timeouts
  waiting for all network interfaces to start, and affected Xen VIF
  interfaces will of course never complete startup.

  [Fix]

  No fix yet.  Upstream kernel does not appear fixed.

  [Test Case]

  Create a guest instance under a Xen hypervisor (e.g. an AWS instance)
  that has Ubuntu Artful 17.10 installed.  Use only a single interface
  at first when creating it.  Then once it is ready, attach a second
  network interface to the instance.  From inside the instance,
  configure the new interface in netplan (i.e. add a /etc/netplan/
  config for it).  Make sure the new interface is down (netplan does not
  appear to unbind/bind interfaces that are up), and then run:

  $ sudo netplan apply

  or for debug,

  $ sudo netplan --debug apply

  this will unbind and re-bind the second interface, which will then
  have all-0 mac, and will be unusable, as described above.

  [Regression Potential]

  Changes to the Xen VIF driver can result in unusable network
  interfaces, or problems while using Xen VIF interfaces.

  [Other Info]

  Problem appears to exist upstream also.

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