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System V AMD64 ABI

OS Interfaces & ABIs·Linux Foundation
WHY YOU NEED THIS

Every C/C++/Rust/Go/Swift program on x86-64 Linux follows this ABI. Understanding it is essential for FFI bindings, inline assembly, debugger step-over logic, and compiler backend development.

What It Defines

Defines the calling conventions, register allocation, stack frame layout, parameter/return value passing, and ELF object file conventions for x86-64 code on Unix/Linux systems. Specifies which registers are caller-saved vs callee-saved (rax, rdi, rsi, rdx, rcx, r8, r9 for integer args), how system calls are made via the syscall instruction, and how dynamic linker PLT/GOT tables work for shared libraries.

Canonical (Normative)

Convenient (Practical)

abix86-64calling-conventionlinuxcompilersyscallpltgot
Standards Body
Linux Foundation

Non-profit hosting Linux kernel development and hundreds of open-source projects. Maintains the Linux Standard Base (LSB) for binary-compatible Linux distributions, hosts the ELF reference specifications and System V ABI documents, and stewards ELISA, OpenEmbedded, Zephyr, and other embedded/safety-critical Linux initiatives.

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