[U-Boot] printf and R9 in ARM architecture

[Da Shi Cao]

No, I didn't use that option. This option should fix it.

Thanks a lot.
Thomas

On Tue, Jan 20, 2015 at 5:37 PM, Albert ARIBAUD
<albert.u.boot at aribaud.net> wrote:
> Hello Dashi Cao,
>
> On Tue, 20 Jan 2015 14:12:35 +0800, Da Shi Cao <dscao999 at gmail.com>
> wrote:
>> In standalone applications, it seems that the execution of printf
>> function in U-Boot is dependent on the value of register R9, which is
>> setup in app_startup. But r9 can be used by your program at the
>> decision of gcc compilation which is not aware of this dependence.
>> This is especially the case if +O2 is used!
>
> U-Boot follows the ARM EABI, in which ""The role of register r9 is
> platform specific". In U-Boot r9 is specifically used for the global
> data structure, and the standalone programs must follow this EABI.
>
> If your standalone program is built with the same options as U-Boot
> example standalone programs are (see hellow_world), then it should
> have gcc option -ffixed-r9 which will prevent the compiler from ever
> touching r9.
>
> How exactly do you build your standalone application?
>
>> My version is U-Boot 2014.10
>>
>> Regards,
>> Dashi Cao
>
> Amicalement,
> --
> Albert.