I am on testing repo and just installed the new kernel 4.15 linux and linux-zen both failing to boot. (I thing the reason was because of failing to start LightDM)
Also I have noticed nvidia 390.25-1 but cant update because it cant find nvidia-utils 390.25-1
I got panicked a bit but fortunately I had an LTS kernel installed and boot from there.
Hopefully we will get some updates soon on testing…