gcc: Thumb interworking and weakly linked functions

[Aneesh V]

On Thursday 23 February 2012 05:17 PM, Ulrich Weigand wrote:
> Aneesh V<aneesh at ti.com>  wrote on 23.02.2012 11:27:40:
>
>>> The "packed" attribute specifies that all struct elements ought to be
>>> considered to have alignment requirement 1 instead of their default
>>> alignment.  Thus the whole struct ends up having alignment requirement
> 1;
>>> and since the section contains only a single variable of such struct
>>> type, this is then also the alignment requirement of the section.
>>>
>>
>> Hmm.. Thanks. Removing packed seems to help. The following also helped.
>>
>> @@ -34,7 +34,7 @@ struct pad_conf_entry {
>>
>>       u16 val;
>>
>> -} __attribute__ ((packed));
>> +} __attribute__ ((packed)) __attribute__ ((aligned(2)));
>>
>> BTW, just for my understanding:
>> The effect of adding __attribute__ ((packed)) to a structure is
>> equivalent to adding it for each field in the structure, right?
>
> Right.
>
>> And because the first field doesn't have any alignment requirement,
>> the struct also doesn't have any alignment requirement right?
>
> Sort of.  The alignment requirement of the struct is the maximum
> (actually, the least common multiple, but since we're talking only
> powers of two, that amounts to the same) of the alignment requirements
> of all members.  However, attribute packed for a struct applies to
> each element separately, and thus each element has alignment
> requirement 1, which is then also the maximum.

Understand. Thanks for the explanation.

br,
Aneesh