* GCC question
@ 2013-01-09 9:02 Franck Jullien
2013-01-09 9:09 ` Sascha Hauer
2013-01-10 12:36 ` Jean-Christophe PLAGNIOL-VILLARD
0 siblings, 2 replies; 6+ messages in thread
From: Franck Jullien @ 2013-01-09 9:02 UTC (permalink / raw)
To: barebox
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 ?
Thank you,
Franck.
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: GCC question
2013-01-09 9:02 GCC question Franck Jullien
@ 2013-01-09 9:09 ` Sascha Hauer
2013-01-09 9:13 ` Franck Jullien
2013-01-10 12:36 ` Jean-Christophe PLAGNIOL-VILLARD
1 sibling, 1 reply; 6+ messages in thread
From: Sascha Hauer @ 2013-01-09 9:09 UTC (permalink / raw)
To: Franck Jullien; +Cc: barebox
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
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: GCC question
2013-01-09 9:09 ` Sascha Hauer
@ 2013-01-09 9:13 ` Franck Jullien
2013-01-09 9:28 ` Sascha Hauer
0 siblings, 1 reply; 6+ messages in thread
From: Franck Jullien @ 2013-01-09 9:13 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
2013/1/9 Sascha Hauer <s.hauer@pengutronix.de>:
> 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
>
> --
> Pengutronix e.K. | |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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.
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: GCC question
2013-01-09 9:13 ` Franck Jullien
@ 2013-01-09 9:28 ` Sascha Hauer
0 siblings, 0 replies; 6+ messages in thread
From: Sascha Hauer @ 2013-01-09 9:28 UTC (permalink / raw)
To: Franck Jullien; +Cc: barebox
On Wed, Jan 09, 2013 at 10:13:51AM +0100, Franck Jullien wrote:
> 2013/1/9 Sascha Hauer <s.hauer@pengutronix.de>:
> > 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
> >
> > --
> > Pengutronix e.K. | |
> > Industrial Linux Solutions | http://www.pengutronix.de/ |
> > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
>
> 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.
No, and this wouldn't be enough anyway. You also have to tell the linker
that it shall put all functions matching .initcall.* in a separate
section. Otherwise they would end up in the regular sections.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: GCC question
2013-01-09 9:02 GCC question Franck Jullien
2013-01-09 9:09 ` Sascha Hauer
@ 2013-01-10 12:36 ` Jean-Christophe PLAGNIOL-VILLARD
2013-01-10 12:52 ` Franck Jullien
1 sibling, 1 reply; 6+ messages in thread
From: Jean-Christophe PLAGNIOL-VILLARD @ 2013-01-10 12:36 UTC (permalink / raw)
To: Franck Jullien; +Cc: barebox
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.
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: GCC question
2013-01-10 12:36 ` Jean-Christophe PLAGNIOL-VILLARD
@ 2013-01-10 12:52 ` Franck Jullien
0 siblings, 0 replies; 6+ messages in thread
From: Franck Jullien @ 2013-01-10 12:52 UTC (permalink / raw)
To: Jean-Christophe PLAGNIOL-VILLARD; +Cc: barebox
2013/1/10 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@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.
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-01-10 12:53 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-01-09 9:02 GCC question Franck Jullien
2013-01-09 9:09 ` Sascha Hauer
2013-01-09 9:13 ` Franck Jullien
2013-01-09 9:28 ` Sascha Hauer
2013-01-10 12:36 ` Jean-Christophe PLAGNIOL-VILLARD
2013-01-10 12:52 ` Franck Jullien
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox