2013/1/9 Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>:
> On Wed, Jan 09, 2013 at 10:02:32AM +0100, 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 ?
>
> Yes. In nios2 this is:
>
> __barebox_initcalls_start = .;
> .barebox_initcalls : { INITCALLS }
> __barebox_initcalls_end = .;
>
> With INITCALLS being defined as:
>
> #define INITCALLS \
> KEEP(*(.initcall.0)) \
> KEEP(*(.initcall.1)) \
> KEEP(*(.initcall.2)) \
> KEEP(*(.initcall.3)) \
> KEEP(*(.initcall.4)) \
> KEEP(*(.initcall.5)) \
> KEEP(*(.initcall.6)) \
> KEEP(*(.initcall.7)) \
> KEEP(*(.initcall.8)) \
> KEEP(*(.initcall.9)) \
> KEEP(*(.initcall.10)) \
> KEEP(*(.initcall.11))
>
> The 'KEEP' keyword keeps the linker from throwing away these.
>
> Sascha
>
> --
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Thanks Sascha, I missed this one.....
So is there no way I can do what I want without modification to the
default linker script.
I searched for a gcc attibute equivalent to KEEP but it doesn't seems to exist.
Franck.
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