Beginner's Guide to Linkers (2010)

Best piece on linkers is in my opinion Ian Lance Taylor's (author of the gold linker) write up[1]. It obviously has been written in a hurry and could need some polish but the content is gold. LWN published an overview with links to the different parts, to make it a little more accessible[2]. I always hoped Ian would turn it into the book he mentioned in the post. [1] https://www.airs.com/blog/archives/38 [2] https://lwn.net/Articles/276782/

One thing I found really interesting while playing around with gdb on a program with dynamic linking is that functions are linked lazily when they're first called. So rather than hooking up calls to printf/fopen when the program starts, those calls instead get hooked up through an intermediate table to jump into the dynamic linker's resolution code. The first time each dynamically-linked function is called, it goes through a process of looking up the symbol. Once it finds the actual…

Wherever the code refers to a variable or function, the compiler only allows this if it has previously seen a declaration for that variable or function—the declaration is a promise that a definition exists somewhere else in the whole program. The notable exception here is implicitly declared functions, but they were dropped in C99 anyway.

My humble suggestion: "How to Write Shared Libraries" by Ulrich Drepper http://www.akkadia.org/drepper/dsohowto.pdf