On Tue, Apr 01, 2014 at 10:49:51PM +0200, Paul Bolle wrote:
> On Mon, 2014-03-31 at 14:05 -0700, H. Peter Anvin wrote:
> > --- a/include/linux/init.h
> > +++ b/include/linux/init.h
> > @@ -163,6 +163,23 @@ extern bool initcall_debug;
> >
> > #ifndef __ASSEMBLY__
> >
> > +#ifdef CONFIG_LTO
>
> I can't find a Kconfig symbol LTO nor a preprocessor define for
> CONFIG_LTO. (I only checked master of Linus's tree and linux-next.)
The patch for LTO is not merged yet, this is all preparation.
>
> Why is this check for CONFIG_LTO needed?
The comment just below describes the problem.
Or is your question what LTO is? Link Time Optimization
>
> > +/* Work around a LTO gcc problem: when there is no reference to a variable
> > + * in a module it will be moved to the end of the program. This causes
> > + * reordering of initcalls which the kernel does not like.
> > + * Add a dummy reference function to avoid this. The function is
> > + * deleted by the linker.
> > + */
> > +#define LTO_REFERENCE_INITCALL(x) \
> > + ; /* yes this is needed */ \
> > + static __used __exit void *reference_##x(void) \
> > + { \
> > + return &x; \
> > + }
> > +#else
> > +#define LTO_REFERENCE_INITCALL(x)
> > +#endif
--
a...@linux.intel.com -- Speaking for myself only
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