do_initcalls

[Tobias Boege]

On Mon, 18 Mar 2013, ishare wrote:
> On Sun, Mar 17, 2013 at 04:11:54PM +0100, Tobias Boege wrote:
> > On Sun, 17 Mar 2013, ishare wrote:
> > > 
> > >  for (call = &__initcall_start; call < &__initcall_end; call++)
> > >    (*call)();
> > > 
> > >  I want to know where are these  function point assigned by specified function ?
> > > 
> > >  thanks!
> > 
> > As per include/asm-generic/vmlinux.lds.h and your arch's vmlinux.lds.S (I
> > actually only looked at x86's), the __initcall_{start,end} variables are the
> > start and end of the __initcall ELF section which contains all the sub-level
> > sections.
> > 
> > Functions can be put into these sections when they are given to one
> > of the *_initcall macros from include/linux/init.h.
> 
>   I have configure kernel  supporting rom filesystem ,and register it  by module_init(init_romfs_fs) ,
>   but why the function : init_romfs_fs not be called from (*call)() ?
> 
>   thanks!
> 

This is strange - *unless* you build romfs as a module. Have again a look at
the aforementioned include/linux/init.h. There's a fairly big comment on the
procedure:

/**
 * 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.
 */

Regards,
Tobi