Seems all systems that report this issue have one thing in common...Alps touchpad using Alps version of VoodooPS2Controller.kext (v1.8.9, 1.9.0).
I too, encounter KP after installing 'Recovery' and running 'trimforce enable'. Was able to boot with CPUS=1. Finally decided to remove all versions of VoodooPS2Controller and replace with ApplePS2Controller. No more KP.
I guess we'll have to wait for a new version of Alps touchpad kext or rebuild it with new Xcode could fix it...???
For now I'm sticking with ApplePS2Controller, it works as a regular mouse. No multitouch or scrolling.
Using Karabiner can enable trackstick scrolling which is fine with me since I don't use touchpad as much.
ApplePS2Controller.kext.zip