[U-Boot] [PATCH] display_buffer: fix misaligned buffer

[Detlev Zundel]

Hi Albert,

> Le 30/08/2010 18:47, Detlev Zundel a écrit :
>> Hi Reinhard,
>>
>>> Detlev Zundel schrieb:
>>>
>>>>> Detlev, regarding the discussion I would only point out that we have to
>>>>> be sure that such kind of patch will be merged in the current release.
>>>>> It would be a real pity if a new official realease is published and then
>>>>> even a simple "md" command does not work on ARM.
>>>>
>>>> I don't see a problem here.  All proposed patches (with/without
>>>> attribute and union) surely fix a bug, so they will go into mainline
>>>> when consent is reached on which one to use.  This should well happen
>>>> before the pending release on September 12th[1].
>>>>
>>>> Am I misunderstanding anything here?
>>>
>>> No... but I would require that the "union" approach would be wanted,
>>> BEFORE I put effort into doing it.
>>
>> I'd very much appreciate your effort as I want the solution now that you
>> did whet my appetite.
>
> Besides, re: 'fixing with the side-effect of a different thing': I think 
> the alignment caused by using an union is not actually a side effect of 
> it but an intended effect of it, as the compiler must ensure correct 
> alignment of each union member -- on architectures where alignment of 
> 32-bit ints is unnecessary, the union will not cause undue alignment, 
> whereas the __aligned__ attribute would.

Absolutely and that's why I like the solution.  It clearly states the
intentions of the code.

The 'side effect of another thing' that I was talking about was the
proposed local change of using an uint32_t array for something which
originally was an uint8_t array in order to gain the alignment.

Cheers
  Detlev

-- 
Greenspun's Tenth Rule of Programming: "Any sufficiently complicated C
or Fortran program contains an ad-hoc, informally-specified bug-ridden
slow implementation of half of Common Lisp."
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de