[Bug 1631474] Re: No networking with initramfs-tools 0.122ubuntu8.3 and ip=dhcp boot option

[Jason Gerard DeRose]

Attaching a tarbal of everything i have in /var/log, not sure it's
useful (not my "ephemeral" environment is read-only with /var/log on a
tmpfs, so it's mostly empty).

Also here's my exact /proc/cmdline from within the booted ephemeral
environment:

BOOT_IMAGE=vmlinuz-4.4.0-42-generic initrd=initrd.img-4.4.0-42-generic
root=/dev/nfs nfsroot=10.17.76.1:/var/lib/tribble/ephemeral ip=dhcp ro
nomodeset net.ifnames=0 BOOTIF=01-80-fa-5b-36-f5-86

** Attachment added: "log.tgz"
   https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/1631474/+attachment/4760012/+files/log.tgz

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Title:
  No networking with initramfs-tools 0.122ubuntu8.3 and ip=dhcp boot
  option

Status in initramfs-tools package in Ubuntu:
  In Progress
Status in initramfs-tools source package in Xenial:
  Confirmed
Status in initramfs-tools source package in Yakkety:
  In Progress

Bug description:
  [Impact]

   * 0.122ubuntu8.3 of initramfs-tools no longer correctly processed
  ip=dhcp or ip=:::::eth0:dhcp

   * Regression-updates

   * The fix better parses the ip= command line argument.

  [Test Case]

   * Create a machine that boots using an nfsroot.

   * Use ip=:::::eth0:dhcp on the kernel command line.  To set up
     networking.

   * Discover that the device never comes up because, networking is not
  configured correctly.

  [Regression Potential]

   * Regressions potential is limited to machines using
  ip={""|::::*|on|any|dhcp} on the kernel command line.  As this is
  already broken regression potential is minimal.  This is common on
  machines that use nfsroot or otherwise pxe boot.

  [Other Info]

   * There are a number of other issues in this code base that are not solved by this fix. 
     - The ?*:?*:?*:?*: use case falls through to the default case, and likely breaks there.  As such static assignment via ip= appears broken 
     - 
   * The networking configuration does not strictly follow the kernel documentation as described https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt . This should be fixed.

  ====================Original Bug Description Follows==================

  initramfs-tools 0.122ubuntu8.3 introduced a serious regression where
  networking is not initialized when the boot option "ip=dhcp" is
  provided. We are seeing this problem in AWS, but cannot confirm if
  this issue is specific to AWS or will occur with different hardware or
  in different environments.

  Removing "ip=dhcp" from the boot options with 0.122ubuntu8.3 results
  in networking being configured.

  The issue does not occur with 0.122ubuntu8.2 or previous versions when
  "ip=dhcp" is set.

  AWS has no console so debugging is not a trivial task. I do have a
  console log with some output, and will update this bug shortly with
  it.

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