JWR66V or JSS15J, what's up with that?
We're getting a lot of requests and people overall seem to be confused by Googles move to release two branches with the same build number.
Trying to make this easy, read if you intent to change your kernel or build roms.
JWR66V is Googles official release branch, this is what the Nexus 4 runs stock. This branch is tested and stable.
JSS15J is an experimental developer branch that officially only runs on the 2013 Nexus 7. This branch is not stable any other device and suffers from severe issues that affect all JSS roms (and as it turns out even the stock Nexus 7.
http://*******/dWIO0g)
These issues weren't clear to developers in the beginning, most teams assumed newer = better and built JSS. XDA was consequently hammered with complaints and bug-reports,mostly dead-locks/freezes.
Now some teams have accepted these issues and wait for Google to fix it. We did not accept it and reverted parts back to JWR while retaining obvious JSS bugfixes, we still cherry-pick aosp/master bugfixes as welll. This is not a downgrade, many users have reported 4.3 runs now stable for them.
What this means if you want to exchange your kernel is that you need to focus on JWR compatible kernels. JSS kernels are not compatible and cause heavy jitter and glitches. The difference between these two kernels is marginal and none of it will matter in terms of speed and performance. Some kernel developers like +Francisco Franco have forseen this right away, that's why his official is JWR, not JSS - so good for us and all other JWR based roms.
One more thing about kernels, we have put a lot of effort into making PA run right out of the box. Everything should work. If you do flash kernels and you experience problems with root, jitter, etc., search XDA first for possible solutions. Since this is up to you and your kernel developer we can't help you there.
We are in an easy position now, should Google or anyone else fix stuff we can pretty much flip a switch and we're back on JSS. This allows us to sit back and start working on our own features again.
Please share this post if you see questions come up.
