Re: rs_init()

> I have been looking at the linux serial driver initialization routine
> rs_init() in drivers/char/serial.c. This routine gets invoked as a
> part of a do-while loop in do_initcalls() in init/main.c.The code
> looks something like this:
> 
> static void __init do_initcalls(void)
> {
>         initcall_t *call;
> 
>         call = &__initcall_start;
>         do {
>                 (*call)();
>                 call++;
>         } while (call < &__initcall_end);
> 
>         /* Make sure there is no pending stuff from the initcall sequence */
>         flush_scheduled_tasks();
> }
> 
> I would like to know where exactly is rs_init() being inserted into
> the chain of routines that gets invoked in the do-while loop.


Welcome to linker magic!



The __initcall directive expands to something like __attribute__

((unused,__section__ (".initcall.init"))), which will instruct the

compiler to but the function pointer in the .initcall.init ELF section

(see gcc info file for more information). The boundaries of this

section are __initcall_start and __initcall_end, also filled in by the

linker at link time.



So the rs_init() function pointer will be put *somewhere* into the

.initcall.init section. At boot, the function do_initcalls() will call

all function pointers in the section, so at a certain point rs_init()

will also be called through its function pointer in the .initcall.init

section.