Follow a runnable Linux program from an unresolved call to four final instruction bytes. Distinguish section offsets, file offsets, P, and next RIP before deriving S+A-P; then explore negative displacements, absolute pointers, addends, overflow, and instruction relaxation.

Select global definitions before binding used references, preserving local identity, weak tie order, and COMMON requirements without assigning addresses.

Start with a runnable two-file program, then change only the link inputs to expose missing definitions, duplicate definitions, weak symbols, common storage, archive extraction, and the limits of ordinary type checking.

Decode symbols and explicit-addend relocations, establish table ownership, and preserve information for definition selection and layout.

Follow C through assembly into ELF, decode the actual bytes of sections and symbols, and identify the promises a relocation record leaves for the linker. All examples use a native x86-64 Linux toolchain.

Decode section descriptors, borrow payload bytes, and resolve names so later stages consume named Sections instead of rereading raw fields.

A linker began as a way to move reusable code. Follow the problems that led to object files, shared libraries, unwind tables, security metadata, and modern parallel linkers—then link a small program by hand.

Check byte ranges, the supported ELF64 header, and section-header indexes to establish an input boundary without arithmetic wraparound or out-of-bounds reads.