[U-Boot] ARM: Incorrect ROM protection range?

[Albert ARIBAUD]

Le 24/02/2011 13:58, Po-Yu Chuang a écrit :
> Hi Albert,
>
> On Thu, Feb 24, 2011 at 7:58 PM, Albert ARIBAUD<albert.aribaud at free.fr>  wrote:
>> Le 24/02/2011 10:39, Wolfgang Denk a écrit :
>>>
>>> Dear Albert ARIBAUD,
>>>
>>> In message<4D6611A7.5050802 at free.fr>    you wrote:
>>>>
>>>>>>> In the U-Boot image itself, knowing the image size could be achieved
>>>>>>> in
>>>>>>> ARM by using a general _end symbol that would be set after the last
>>>>>>> image output section, so _end-_start would equal the image size.
>>>>>>
>>>>>> we have such a "_end" in u-boot.lds files.
>>>>
>>>> I *knew* this name did not pop up in my mind without a reason. :)
>>>>
>>>> Apologies for not having checked.
>>>>
>>>>> I guess we need a __dynsym_end in all u-boot.lds files.
>>>>
>>>> I'd rather go for "_end", which does not tie the solution to dynsym
>>>> being the last section in the image -- imagine for some reason we move
>>>> dynsym inside the image rather than at the end, end the image size will
>>>> be wrong again. With _end, and a suitable comment in the LD file... this
>>>> will be averted where-ever dynsym ends up.
>>>>
>>>> After all, the bug you uncovered was due to using the wrong symbol, a
>>>> BSS related one rather than an image-related one, in the first place; so
>>>> let's try and learn from past mistakes.
>>>
>>> I think the location of _end in the linker scripts needs to be changed
>>> - so far it covers the maximum of dynsym and bss, but it should refer
>>> to the end of dynsym only.
>>
>> Po-Yu Chuang, can you verify Wolfgang's suggestion (and make sure no other
>> place depends on _end) and submit a patch? As this is a fix, a quick patch
>> could still be pulled in for the upcoming release.
>
> I think there is a problem in Wolfgang's suggestion.
>
> Those start.S files assume that BSS section is from __bss_start to _end.
> If we change _end to the end of .dynsym, then we will not clear BSS correctly.
>
> I agree with your comment about _end is a better choice than __dynsym_end,
> but if we changed _end, maybe we need __bss_end? Either way, we need to
> modify all the u-boot.lds and/or start.S.
>
> I still don't know what is the best solution.

Thanks for pointing this out: indeed, _end is actually used as BSS's 
end, not as the image's end -- I did not find any other use of it.

However, not only ARM uses _end: how do we want to handle the change 
overall?

> best regards,
> Po-Yu Chuang

Amicalement,
-- 
Albert.