gcc: Thumb interworking and weakly linked functions

[Ulrich Weigand]

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.


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

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