GCC question

[Franck Jullien]

2013/1/10 Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>:
> On 10:02 Wed 09 Jan     , Franck Jullien wrote:
>> Hi,
>>
>> I have a question not directly related to Barebox but I think I can
>> find some answer here: )
>>
>> I would like to use initcalls in a Linux user's land program on a x86 target.
>>
>> I'm doing something like this:
>>
>> #ifndef _INIT_H
>> #define _INIT_H
>>
>> typedef int (*initcall_t)(void);
>>
>> extern initcall_t __start_target, __stop_target;
>>
>> #define target_initcall(fn)   static initcall_t _##fn \
>>                               __attribute__((used)) \
>>                               __attribute__ ((section("target"))) = fn
>>
>> #endif
>>
>> then:
>>
>>       initcall_t *initcall;
>>
>>       for (initcall = &__start_target;
>>                       initcall < &__stop_target; initcall++) {
>>               printf("initcall-> %p\n", *initcall);
>>               ret = (*initcall)();
>>               if (ret)
>>                       printf("initcall %p failed: %d\n", *initcall, ret);
>>       }
>>
>> Everything looks fine except the linker removes the function
>> "initcalled" because it is not
>> referenced anywhere and this is normal.
>>
>> I have not modified the linker script (I'm using the default one). I'm
>> using auto generated
>> __start_target and __stop_target symbols generated by the linker.
>>
>> My question is: why does it work in barebox ? For example, in
>> nios2/generic.c we have only
>> static function and initcalls. So why the linker does optimize out
>> those functions ? Is it
>> because we have initcall corresponding sections in the linker script ?
> on userspace you can use directly the contructor
>
> Best Regards,
> J.

Thanks, I'll try it.

I need to check if mingw32 and mingw64 also have this attribute.

Franck.