There isn't support for aufs filesystems in kernel version 4.9.0 in the repository

[Seth Forshee]

On Tue, Jan 03, 2017 at 03:06:09PM +0100, oscaretu . wrote:
> Hello, Seth.
> 
> I've not filed a bug because I've seen the errors about i915 chipset appers
> lots of times in Google, and I've seen many anwser to the problem that
> didn't solve it, but it seemed to be a very known problem. With kernel 4.9
> the error message when booting disappeared. The messages that appears in
> dmesg output after booting was:
> 
> 
> [   13.761480] ------------[ cut here ]------------
> [   13.761503] WARNING: CPU: 0 PID: 47 at
> /home/kernel/COD/linux/drivers/gpu/drm/i915/intel_pm.c:3675
> skl_update_other_pipe_wm+0x15d/0x170 [i915]
> [   13.761504] WARN_ON(!wm_changed)

So you must be running xenial then. It looks like this patch series
fixed that warning:

 https://lists.freedesktop.org/archives/intel-gfx/2016-May/095529.html

That may not be so easy to backport. Those patches went into 4.8 though,
so yakkety should not have this issue. Soon it will also be possible to
easily install yakkety 4.8 kernels in xenial using the linux-lts-yakkety
packages.

Seth