Then move on. Ah, variable names. A global variable rarely used may deserve a long name, maxphysaddr say. When the variable names are huge, it's harder to see what's going on. Indices are just notation, so treat them as such.
Pointers also require sensible notation.
More on this in the next essay. As in all other aspects of readable programming, con- sistency is important in naming. If you call one variable maxphysaddr, don't call its cousin lowestaddress. Globals, for instance, typically have little context when they are used, so their names need to be relatively evocative. This is largely a matter of taste, but taste is relevant to clarity.