I don't think -O2 will solve the problem in this case but it does, if a
function is declared as "extern inline". Basically this qualifier tells gcc
to inline the function (strictly). If gcc is not able to inline, then gcc
will produce a non-linkable format of the function and linker will report
undefined reference for the function. When the function (declared as extern
inline) is compiled with -O2, gcc can inline it and produces linkable format
and linker will not complain. You can try compiling this small program with
and without -O2 to see the result.
extern inline int function(int a)
{
return a*a;
}
int main(void)
{
printf("%d\n", function(6));
return 0;
}
Regards
Mohanlal
----- Original Message -----
From: "Christophe Lucas" <c.lucas@ifrance.com>
To: <kernelnewbies@nl.linux.org>
Sent: Thursday, May 06, 2004 3:08 PM
Subject: Re: Unresolved symbol during insmod
> Saifuddin (saif@odysseytec.com) wrote:
> > >
> > > The command that i used to compile the module was:
> > >
> > > ---snip---
> > > gcc -Wall -DMODULE -D__KERNEL__ -DLINUX -c mod.c
> > > -I/lib/modules/`uname -r`/build/include/
> > > ---snap---
> >
> > Try using -O2 while compiling. It should solve your problem.....
>
> I must be wrong, but why -O2 will solve his unresolved symbol problem ?
>
> I can read this in gcc manual :
> -O2 Optimize even more. GCC performs nearly all supported optimizations
> that do not involve a space-speed tradeoff. The compiler does not
> perform loop unrolling or function inlining when you specify -O2. As
> compared to -O, this option increases both compilation time and the
> performance of the generated code.
>
> I would be happy to know the reason if this flag solve his problem.
>
> --
> Regards
>
> Christophe
>
> * GNU/Linux & UNIX developer and network administrator
> * Membre RotomaLUG (http://www.rotomalug.org)
> * Registered User #271267
> * Email: c.lucas@ifrance.com
> * Web Site: http://odie.mcom.fr/~clucas/
>
> --
> Kernelnewbies: Help each other learn about the Linux kernel.
> Archive: http://mail.nl.linux.org/kernelnewbies/
> FAQ: http://kernelnewbies.org/faq/
>
>
--
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