What is an application binary interface (ABI)?

Question

I never clearly understood what an ABI is. Please don\'t point me to a Wikipedia article. If I could understand it, I wouldn\'t be here posting such a lengthy post.

Answer 1

An application binary interface (ABI) is similar to an API, but the function is not accessible to the caller at source code level. Only a binary representation is accessible/available.

ABIs may be defined at the processor-architecture level or at the OS level. The ABIs are standards to be followed by the code-generator phase of the compiler. The standard is fixed either by the OS or by the processor.

Functionality: Define the mechanism/standard to make function calls independent of the implementation language or a specific compiler/linker/toolchain. Provide the mechanism which allows JNI, or a Python-C interface, etc.

Existing entities: Functions in machine code form.

Consumer: Another function (including one in another language, compiled by another compiler, or linked by another linker).