Hello World in PowerPC64 LE Assembly (Linux)

A simple Hello World implementation in PowerPC64 Little-Endian assembly language for Linux systems. PowerPC64 LE represents the modern evolution of the PowerPC architecture, used in contemporary IBM POWER systems and supported by major Linux distributions.

Installation

On a PowerPC64 LE Linux system, you'll need the standard GNU toolchain:

sudo apt-get update
sudo apt-get install binutils gcc

Running

Assemble and link:

as -o main.o main.s -mlittle -m64
ld -o hello main.o -EL
./hello

Code Explanation

The PowerPC64 LE implementation introduces several modern features that distinguish it from other PowerPC variants. This implementation demonstrates the ELFv2 ABI and the little-endian adaptations of the 64-bit PowerPC architecture.

Key Architectural Features

ELFv2 ABI:

• Specified by .abiversion 2 directive
• Introduces a more efficient function calling convention
• Uses a different approach to position-independent code
• Simplifies the handling of function pointers

Memory Access and TOC:

• Uses little-endian byte ordering
• TOC (Table of Contents) based addressing using register 2
• @toc references for position-independent code
• 8-byte alignment for optimal 64-bit access

Register Usage:

• Register 0: System call number
• Register 2: TOC base register
• Register 3: First argument (file descriptor or return code)
• Register 4: Second argument (message address)
• Register 5: Third argument (message length)

Instructions:

• li (Load Immediate): Loads a 16-bit value
• addis (Add Immediate Shifted): Adds a shifted 16-bit value
• addi (Add Immediate): Adds a 16-bit value
• sc (System Call): Triggers kernel service

Differences from Other PowerPC Variants

Compared to PowerPC64 Big-Endian:

• Uses ELFv2 ABI instead of ELFv1
• Different TOC addressing scheme
• Little-endian byte ordering
• Simpler function prologue/epilogue sequences

Compared to PowerPC32 LE:

• Full 64-bit register width
• Different ABI specification
• More sophisticated TOC-based addressing
• Different alignment requirements

Modern Usage

PowerPC64 LE has become the standard for modern PowerPC systems because:

• Better compatibility with little-endian systems
• More efficient ABI design
• Better performance in modern workloads
• Wider software ecosystem support

The implementation demonstrates how PowerPC has evolved to meet modern computing needs while maintaining backward compatibility where necessary. The ELFv2 ABI and little-endian byte ordering make it easier to port software from other architectures, particularly x86_64.