Background
==========
Early versions of linux-restricted-modules implemented a strict version clamp
on nvidia-kernel-common-NNN to prevent the kernel modules remaining installed
if the nvidia-graphics-drivers-NNN version was changed.  This was done to
ensure that we did not mix Nvidia driver ABIs; which is strictly forbidden by
Nvidia.

It was later determined that this overly strict version clamp was preventing
the unattended-upgrades from making sensible decisions; leading it to upgrade
the kernel only rendering the default kernel unable to drive the display.

Experimentation confirmed that the userspace component is self-protecting,
refusing to load against a missmatched kernel driver.  This revalation
allowed us to remove this strict version clamp.

With this removed upgrades no longer wanted to remove the old kernel drivers
making downgrading a lot simpler as you only need to downgrade the Nvidia
userspace components.  It also allowed the new kernel and Nvidia components to
install together under unattended-ugrades, leading to a much improved user
experience.

Frozen Media
============
The factory process for various machines preinstalled with Ubuntu freezes very
early versions of Ubuntu onto the machines based unchanging install media.  The
machines then update from there against the live primary archive.

In some cases the frozen Nvidia components contain this strict clamp leading
to terrible upgrade semantics in the face of unattended-upgrades running during
their first session.

Solution
========
The package which contains the strict clamp is an ABI specific package.  This
means that generally it represents an NBS package in the archive.  As later
kernels produce updated ABI packages we are able to update this anchient ABI
package to remove the strict clamp without affecting any current kernel.

This source package carries the affected binary packages directly as downloaded
from the Launchpad librarian.  They are modified at package build time to
remove the strict clamps via debian/fixup-control and then published at a
higher version number.  Thus providing an upgrade path for the anchient ABI as
installed by the factory media.  This upgrade then removes the strict clamping
and allows the APT resolver to upgrade kernel and Nvidia components without
requiring removals.  This allows the kernel and Nvidia to upgrade together
avoiding the default kernel being unable to drive the display.
