yasm

Modular x86 and AMD64 assembler

TLDR

Assemble to ELF64 object file

$ yasm -f elf64 -o [output.o] [input.asm]

Assemble for Windows 64-bit

$ yasm -f win64 -o [output.obj] [input.asm]

Assemble 32-bit ELF

$ yasm -f elf32 -o [output.o] [input.asm]

Use GAS syntax

$ yasm -p gas -f elf64 -o [output.o] [input.s]

Generate debug info in DWARF format

$ yasm -g dwarf2 -f elf64 -o [output.o] [input.asm]

Preprocess only

$ yasm -e [input.asm]

Define macro

$ yasm -D [DEBUG=1] -f elf64 -o [output.o] [input.asm]

yasm is a modular assembler supporting x86 and AMD64 instruction sets. It is a complete rewrite of NASM under the BSD license, offering multiple input syntaxes and output formats.Supported syntaxes include NASM (default) and GAS (GNU Assembler). Output formats cover ELF, Win32/Win64 PE, Mach-O, COFF, and raw binary (bin, the default). Debug information can be generated in DWARF 2, STABS, or CodeView 8 formats. Use `yasm -f help` to list all available object formats.The assembler is used for low-level system programming, operating system development, and performance-critical code. It integrates with C/C++ toolchains through standard object file formats.

PARAMETERS

-f format, --oformat=format

Output format (default: bin): bin, elf32, elf64, win32, win64, macho32, macho64, coff.

-o outfile, --objfile=outfile

Output file name.

-a arch, --arch=arch

Target architecture (default: x86).

-m machine, --machine=machine

Machine subtype: x86, amd64.

-p parser, --parser=parser

Syntax parser: nasm (default), gas.

-r preproc, --preproc=preproc

Preprocessor: nasm (default), raw, cpp, gas.

-g debug, --dformat=debug

Debug format: dwarf2, stabs, cv8, null.

-L list, --lformat=list

List file format (default: nasm).

-l file, --list=file

Output list file name.

-D macro[=value]

Define preprocessor macro.

-U macro

Undefine macro.

-I path

Add include search directory.

-P file

Pre-include file before input.

-e, --preproc-only

Preprocess only (no assembly), output to stdout.

-w

Suppress all warning messages.

-Werror

Treat warnings as errors.

-Worphan-labels

Warn on labels lacking trailing colons (NASM mode).

-X style

Error/warning reporting style: gnu or vc.

--force-strict

Treat all sized operands as strict.

--version

Display version.

-h, --help

Display help.

INSTALL

sudo apt install yasm

sudo dnf install yasm

sudo pacman -S yasm

sudo apk add yasm

sudo zypper install yasm

brew install yasm

nix profile install nixpkgs#yasm

CAVEATS

Some NASM syntax extensions may not be fully compatible. GAS syntax support is not complete. AMD64 mode requires explicit selection via -m amd64 or 64-bit object format.

HISTORY

yasm was created by Peter Johnson and Michael Urman as a rewrite of NASM with a modular architecture. It aimed to support multiple architectures and syntaxes while maintaining NASM compatibility. Development began in 2001 with the project remaining actively used in various build systems.