• What is an ABI?
• Calling conventions
• Stack frames and prologue/epilogue
• Static vs dynamic linking
• ELF/PE/Mach-O, symbols, and relocations
• PLT/GOT, TLS, and position-independent code
• Versioning, symbol visibility, and compatibility
• Exercises

• Application Binary Interface defines binary contracts between components.
• Includes data layout, endianness, calling conventions, syscalls, and object formats.
• Stable ABIs enable interoperability across toolchains and languages.

• x86-64 System V vs Windows x64: argument registers, callee/caller-saved sets.
• Return values in registers; varargs handling and red zones (SysV).
• Special cases: vector/FP args, struct returns, tail calls.

SysV: rdi,rsi,rdx,rcx,r8,r9  |  Win64: rcx,rdx,r8,r9; 128-byte shadow space

• Prologue sets up stack frame, saves callee-saved regs; epilogue restores and returns.
• Alignment requirements (e.g., 16-byte for SSE on x86-64).
• Exception unwinding metadata and frame pointers vs frame chaining.

push rbp; mov rbp,rsp; sub rsp,N; ... ; leave; ret

• Static: resolves at build time, larger binaries, simpler deployment.
• Dynamic: shared libraries resolved at load/run time; smaller binaries, updatable.
• Loader duties: relocation, symbol resolution, TLS setup.

• Sections and segments; symbol tables; relocation entries and types.
• ELF: .plt, .got, .rela; PE: import table, delay loads; Mach-O: stubs and bind info.
• Position-independent code and relocation models (small/large).

• PLT (procedure linkage table) lazy binds external calls via GOT entries.
• Thread-Local Storage models: local-exec, initial-exec, general-dynamic.
• PIE/PIB: text relocation avoidance and ASLR compatibility.

call foo@PLT → resolver → GOT[foo] patched to direct address

• Symbol versioning (ELF) and DLL exports (PE); hidden vs default visibility.
• ABI breaks: data layout changes, vtable reordering, calling convention shifts.
• Stability strategies: C ABIs for FFI, opaque handles, semver discipline.

1. Disassemble a function compiled for SysV and Win64; compare prologue/epilogue and arg passing.
2. Build a small shared library and inspect its symbols and relocations with objdump/llvm-readobj.
3. Write a minimal PIC function and trace its PLT/GOT resolution at runtime.