ABI

self-taught
ABI stands for Application Binary Interface.
An ABI defines the low-level interface between compiled code and the system or other compiled code.

While an API (Application Programming Interface) tells you how to call a function in source code, the ABI tells you how the compiled machine code should interact.

What an ABI specifies

1. Calling conventions
   1. how arguments are passed between functions
   2. who cleans up the stack
   3. return value location
2. data layout/alignment
   1. size of primitive types
   2. how types are aligned in memory
3. name mangling
   1. how function names appear in object files (especially in C++).
4. system-level conventions
   1. how system calls are made
   2. which registers are preserved across calls
5. binary format expectations
   1. for linking and loading object files (ELF, Mach-O, PE)

Examples

• Linux uses the System V Binary Application Interface, like most Unix-like systems.