[U-Boot] [PATCH RFC] armv7: fixloop: don't fixup if location is NULL

[Minkyu Kang]

Dear Albert ARIBAUD,

On 11 January 2011 02:21, Albert ARIBAUD <albert.aribaud at free.fr> wrote:
> Le 10/01/2011 15:04, Minkyu Kang a écrit :
>
>>>> How about lcd_setmem function?
>>>> panel_info is located at bss area, but lcd_setmem access this structure.
>>>> Is it illegal?
>>>
>>> This must not be done before relocation.
>>
>> No, please see 360 line of arch/arm/lib/board.c
>> This function is called before relocation.
>
> Then it cannot access panel_info, which is "not there yet" at the time
> lcd_setmem() executes.

No, access for reserve the memory for LCD and we got wrong values.
Did you test about it?

>
> You must either move the call to lcd_setmem() to after relocation, or find a
> way not to depend on BSS.

This problem is not belong to my code.
Move after relocation? it's easy.
but, how we can reserve the memory for LCD?

>
>> And how about init_func_i2c()?
>> This function is called twice, before the relocation and after relocation.
>> When we use board_i2c_init function then, there is possibility that
>> use symbols in bss because of this function is called after
>> relocation.
>
> If it is used both before and after relocation, then it has to respect the
> strictest case, which is before relocation, and not access BSS.
>
>> If we ignore this exception, it will be a big constraint.
>>
>> btw, there are any side effects on my patch?
>> I think.. It is just a little safety feature.
>
> Regardless of the patch, if your code writes to panel_info or any other BSS
> variable before relocation it will trash the relocation tables that exist at
> BSS location at this point.
>
> IOW, accessing BSS before relocation is forbidden, not just out of fancy,
> but for a serious reason.

This patch is not for accessing BSS before relocation,
it's for prevent exceptions.

Thanks
Minkyu Kang
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