> Did you remember to make the modification to the Makefile in the
> directory above the one you made for acx, as they describe in their HOWTO?
>
> Just as a refresher, the modification is:
>
> echo 'obj-m += acx/' >> Makefile
>

Yes, I did.

>
> They have a description of how to build the module outside of the kernel
> tree in their HOWTO, did you try that?

Will try.

>
> Does/did anything in the acx directory compile? Any object files (*.o)
> in there after the make?

Nothing compiled so far, but will try the 'outside' version.