Linux Assembler

• Introduction to Linux Intel Assembly Language
• The GNU Assembler
• GNU アセンブラ入門(GAS)
• Linux のアセンブラー: GAS と NASM を比較する

Assembler Command-Line Syntax

• Compiling
  
  1. AT&T-syntax
     

     as -a --gstabs -o x.o x.s
     

     -o option specifies what to call the object file, i.e. machine-code file, which is the primary output of the assembler.
     -a option tells the assembler to display to the screen the source code, machine code and segment offsets side-by-side, for easier correlation.
     -gstabs option tells the assembler to retain in x.o the symbol table, a list of the locations of whatever labels are in x.s, in the object file.
     
  2. Intel syntax
     

     nasm -f elf -o x.o -l x.l x.s
     
     -f option instructs the assembler to set up the x.o file so that the
     executable file constructed from it later on will be of the ELF format,
     which is a common executable format on Linux platforms.
     -l option
     plays a similar role to -a in as, in that a side-by-side
     listing of source and machine code will be written to the file
     x.l.
     

• Linking

  • ld -o x x.o



• see the corresponding assembly language of a C program
  

  • gcc -S y.c