initcall的层次·备忘

   每次都找来找去的不方便，放到这里备忘，查的时候方便。

   在文件：include/linux/init.h 中的定义摘要如下：

/* initcalls are now grouped by functionality into separate 
 * subsections. Ordering inside the subsections is determined
 * by link order. 
 * For backwards compatibility, initcall() puts the call in 
 * the device init subsection.
 *
 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 * can point at the same handler without causing duplicate-symbol build errors.
 */

#define (,,) \
        static  ##fn##id  \
        (((".initcall"  ".init"))) = 

/*
 * A "pure" initcall has no dependencies on anything else, and purely
 * initializes variables that couldn't be statically initialized.
 *
 * This only exists for built-in code, not for modules.
 */
#define ()               ("0",,0)

#define ()               ("1",,1)
#define ()          ("1s",,1s)
#define ()           ("2",,2)
#define ()      ("2s",,2s)
#define ()               ("3",,3)
#define ()          ("3s",,3s)
#define ()             ("4",,4)
#define ()        ("4s",,4s)
#define ()                 ("5",,5)
#define ()            ("5s",,5s)
#define ()             ("rootfs",,)
#define device_initcall()             ("6",,6)
#define device_initcall_sync()        ("6s",,6s)
#define ()               ("7",,7)
#define ()          ("7s",,7s)

#define () device_initcall()

#define () \
        static  ##fn  = 

#define () \
        static  ##fn \
         (..) = 

#define security_initcall() \
        static  ##fn \
         (.security_initcall.) = 

struct  {
        const char *;
        int (*)(char *);
        int ;
};

/*
 * Only for really core code.  See moduleparam.h for the normal way.
 *
 * Force the alignment so the compiler doesn't space elements of the
 * obs_kernel_param "array" too far apart in .init.setup.
 */
#define (, , , )                        \
        static char ##unique_id[]  (1) = ; \
        static struct  ##unique_id      \
                 (..)                   \
                ((((sizeof(long)))))        \
                = { ##unique_id, ,  }

#define (, )                      \
        (, , , 0)

#define (, )                                        \
        (, , , 0)

/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 * returns non-zero. */
#define (, )                                    \
        (, , , 1)

/* Relies on boot_command_line being set */
void  (void);
#endif /* __ASSEMBLY__ */

/**
 * module_init() - driver initialization entry point
 * @x: function to be run at kernel boot time or module insertion
 * 
 * module_init() will either be called during do_initcalls() (if
 * builtin) or at module insertion time (if a module).  There can only
 * be one per module.
 */
#define ()  ();

/**
 * module_exit() - driver exit entry point
 * @x: function to be run when driver is removed
 * 
 * module_exit() will wrap the driver clean-up code
 * with cleanup_module() when used with rmmod when
 * the driver is a module.  If the driver is statically
 * compiled into the kernel, module_exit() has no effect.
 * There can only be one per module.
 */
#define ()  ();

   这些是在非模块化编译的情形下的定义。各个级别很明显了，如果要依赖某个可以驱动模块的话，唯一可选的级别就是late_initcall了。
   嗯。