Learning about kernel?
 

What's the way these days to get familiar with the kernel and drivers?

Is 'kernel newbies'-site still used much?
At least the documentation looks pretty old. A lot of "404"-links and documents from 90's. Most of the stuff seems to be about 2.x kernels.

Also LDD3 seems to be somewhat dated, and the 4th ed is (probably) available sometime 2017.

I once (90's) knew a little something, but it looks like I need to re-learn - probably pretty much everything.

LWN has the latest interesting kernel stuff unless you want the fire hose LKML. The /Documentation directory is up to date but spotty in what it covers. LDD3 is best after that.