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[Launchpad Bug Tracker <1248233@xxxxxxxxxxxxxxxxxx>]

** Branch linked: lp:ubuntu/precise-proposed/linux-lts-saucy

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https://bugs.launchpad.net/bugs/1248233

Title:
  [saucy][armhf] No early printk because there's no defined device tree
  binding for earlyprintk UART

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  SRU Justification:

  Impact: earlyprintk doesn't work in mach-virt (qemu guest target for
  kvm on arm) because at boot time, the clock necessary to make pl011
  serial port running is not added via device tree (and thus the serial
  console is not probed) - also see https://lists.gnu.org/archive/html
  /qemu-devel/2013-10/msg02427.html.

  Fix: apply the attached patches and recompile a kernel.

  Test case: try booting a patched (and an unpatched kernel) in kvm
  guest passing earlyprintk and NO console, and see if it emits any
  output.

  --

  There is no earlyprintk via the PL011 because there's no defined
  device tree binding for earlyprintk UART to get the PL011 to work
  you'll need to tweak the kernel a bit. kernel doesn't ever add the
  clock to its list, and then it refuses to probe for the PL011. This is
  a temporary fix, ideally the call should be done in some generic
  location rather than in every machine's init function.) The
  alternative would be for the kernel to be fixed to follow its own
  device tree binding documentation and not require clocks/clock-names
  properties on the pl011 node.

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