How to do normal map for edge detail?

[jamesbeswick.nz]

I'm new to the whole normal map thing but I'm still confused on how to do a normal map for something like this:

So I'm wanting to make the top part with the extrusions as a normal map, is this possible? I understand how it works for adding detail but not when it comes to the actual edges of geometry. Or would this have to be done a different way?

[damaggio]

Faster by just using Arnold round corners shader.

[jamesbeswick.nz]

Ok thx, I'll have a look into this see if I can find a tut somewhere.