The module must match your kernel

• The module must match your kernel

• There is a recipe (Makefile) for compiling them

• They need to provide a standard set of interfaces callable by the kernel

• • init_module() -- run via insmod
  • cleanup_module() -- run via rmmod
  • In Unix, everything is a file.
  • A driver that is accessed via the file system must supply a table of functions to call for file operations