[Patch 04/18] include/linux/logfs.h
Segher Boessenkool
segher at kernel.crashing.org
Tue Jun 5 14:49:09 EDT 2007
>>> It would be better if GCC had a 'nopadding' attribute which gave us
>>> what we need without the _extra_ implications about alignment.
>>
>> That's impossible; removing the padding from a struct
>> _will_ make accesses to its members unaligned (think
>> about arrays of that struct).
>
> It _might_ make accesses to _some_ of its members unaligned.
It _will_ make accesses to _at least one_ of the members
unaligned, in the second array element.
> That's why I said 'without the __EXTRA__ implications about alignment'.
>
> Obviously the lack of padding has its own implications, but we don't
> necessarily need to assume that the struct may be at arbitrary
> locations.
The compiler does though, if it can't prove otherwise.
What would "nopadding" buy us, anyway?
Segher
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