Comment 0 for bug 1820868

Impact:

During the Bionic cycle, a decision was made to incorporate the linux-snapdragon
kernel into the master branch, thus reducing the number of topic kernels and the
stable maintenance burden.

But as time passed and new patches were produced by Qualcomm, incorporating them
into master while avoiding to destabilize generic became more and more
problematic, down to the point where it was not a viable approach
anymore.

At that point, the decision was made to fork out linux-snapdragon into its own
topic kernel (e.g. linux-raspi2), giving more room to incorporate new code
coming from the Qualcomm tree and avoiding to destabilize any other target in
generic.

Fix:

This is a three step process:

1) disable building linux-snapdragon from master by applying the attached patch
to bionic/master

2) create a new bionic/linux-snapdragon branch and reset hard to my
lp:snapdragon-topic-kernel branch (see below)

3) update bionic-meta to point to the new bionic/linux-snapdragon kernel

Regression potential

From the point of view of bionic/master, this pull request doesn't introduce any
substantial change, and in the future will let us purge generic from several
external patches.

While from the point of view of linux-snapdragon, with ~900 code commits and ~8k
config changes, this represent a brand new kernel and while great care was used
while putting together this branch, there's clearly a regression potential here
but we can't leave linux-snapdragon stagnate behind the curve, so the sooner we
bite the bullet, the better we can the deal with the eventual fallout.