Re: [PATCH 1/3] module: deal with alignment issues in built-inmodule versions

[Dmitry Torokhov]

On Mon, Feb 21, 2011 at 06:03:16PM -0800, Linus Torvalds wrote:
> On Mon, Feb 21, 2011 at 5:58 PM, Benjamin Herrenschmidt
> <benh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > The only sane thing I can see is make sure that such structures that
> > we put into sections "arrays" like that are naturally aligned with
> > padding.
> 
> The sad part is, that assuming I read the gcc sources correctly (see
> the earlier emails where David pointed to it), that alignment is:
>  - architecture-specific
>  - depends on the size of the structure
>  - seems to depend on the version of gcc itself.
> 
> The _one_ safe case is likely to be "structure size is a power of
> two". And it does look like using a pointer is going to be safe, not
> only because the gcc auto-alignment only triggers for things like
> structs/unions/arrays, but because at least the x86 code only does it
> if the structure was bigger than the alignment size itself.
> 
> So using pointer indirection is likely to be safe. It's still ugly and
> annoying as heck, though.
> 

Regardless the approach we'll take I think the following patch is also
needed (for cris architecture). I am not sure why __param section is
inly defined for one specific subarch but I they need __param they'll
need __modev as well.

Thanks,

Dmitry