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SubjectRe: [PATCH] x86-64: Prevent gcc from optimizing away venosys_1()
On Fri, Jun 03, 2011 at 05:32:06PM -0400, Dave Anderson wrote:
>
>
> ----- Original Message -----
> > > return 0;
> > > }
> > >
> > > -static long __vsyscall(3) venosys_1(void)
> > > +long __vsyscall(3) venosys_1(void)
> >
> > Better add a __used too. Otherwise it can be optimized out again
> > in some builds e.g. when someone enables gc-sections for the linker.
>
> Considering that all of the vsyscall prototypes have this attribute:
>
> #define __vsyscall(nr) \
> __attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
>
> How would any of them work?

unused is just to prevent warnings I think. used stops the optimizer
from throwing it away.

It would make more sense to drop the unused and add an used. I think
used prevents the warnings too.

-Andi

--
ak@linux.intel.com -- Speaking for myself only.


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