[head tinderbox] failure on arm/arm

[Giorgos Keramidas]

On 2006-11-12 20:14, Ruslan Ermilov <ru at freebsd.org> wrote:
>On Sun, Nov 12, 2006 at 04:59:04PM +0000, Nicholas Clark wrote:
>>On Sun, Nov 12, 2006 at 06:57:23PM +0300, Ruslan Ermilov wrote:
>>> So your sizeof() argument, well...  I don't understand it and it
>>> doesn't make things clearer at least to me.  I still believe this
>>> is bug in GCC that the alignment requirement is so high for a
>>> "struct foo { char x; }" (there's no real reason for this!).
>>
>> It is no bug in GCC. ANSI C gives extreme flexibility for the compiler to
>> align (or pad) structures. The assumptions in the code you presented are not
>> portable. The problem tends to be that ARM is the only common platform that
>> does structure alignment this way, so tends to trip up a lot of code that
>> has worked just fine in many other places.
>>
>> There is a lot more detail in
>> http://netwinder.osuosl.org/users/b/brianbr/public_html/alignment.html
>> including how gcc's __packed__ extention can be used to tell gcc to align
>> structures in different ways.
>
> Thanks!  Item 2 at this URL has an answer to my question.

Perfect!

Now it's obvious why GCC prefers '4-byte accesses' on ARM.
Nicholas, thank you so much :)