Re: [Patch 04/18] include/linux/logfs.h

[Segher Boessenkool]

> > > 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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