Linux Device Drivers

Quick Reference

This section summarizes the kernel functions, variables, macros, and /proc files that we’ve touched on in this chapter. It is meant to act as a reference. Each item is listed after the relevant header file, if any. A similar section appears at the end of every chapter from here on, summarizing the new symbols introduced in the chapter.

__KERNEL__ , MODULE

Preprocessor symbols, which must both be defined to compile modularized kernel code.

int init_module(void); , void cleanup_module(void);

Module entry points, which must be defined in the module object file.

#include <linux/module.h>

Required header. It must be included by a module source.

MOD_INC_USE_COUNT; , MOD_DEC_USE_COUNT; , MOD_IN_USE

Macros that act on the usage count.

/proc/modules

The list of currently loaded modules. Entries contain the module name, the amount of memory they occupy, and the usage count. Extra strings are appended to each line to specify flags that are currently active for the module.

int register_symtab(struct symbol_table *);

Function used to specify the set of public symbols in the module. This function doesn’t exist any more in Linux 2.1.18 and newer kernels. See Section 17.1 in Chapter 17 for details.

int register_symtab_from(struct symbol_table *, long *);

Version 2.0 exports this function instead of register_symtab, which is a preprocessor macro instead. You’ll see register_symtab_from in /proc/ksyms, but the source code doesn’t need to cope with it.

#include <linux/symtab_begin.h> ...