about -fpic/-fPIC option for gcc

[Lin George]

Thank you Ian,


You have answered most of my question. What materials
are stored in GOT? Any documents describe it in a
simple/clear/brief way? :-)


regards,
George

--- Ian Lance Taylor <iant@google.com> wrote:

> Lin George <george4academic@yahoo.com> writes:
> 
> > Do you mean -fpic and -fPIC will make GOT and PLT
> > different? If yes, what are the differences?
> 
> I quote the documentation about -fPIC:
> 
>     If supported for the target machine, emit
> position-independent
>     code, suitable for dynamic linking and avoiding
> any limit on the
>     size of the global offset table.  This option
> makes a difference
>     on the m68k, PowerPC and SPARC.
> 
> The difference is that with -fPIC there is no limit
> on the size of the
> GOT.  The precise details depend on the platform.
> 
> Ian
> 
> > --- Ian Lance Taylor <iant@google.com> wrote:
> > 
> > > Lin George <george4academic@yahoo.com> writes:
> > > 
> > > > Could you provide a little more information
> > > please? I
> > > > mean what is the different things generated by
> > > -fpic
> > > > and -fPIC in a shared library?
> > > 
> > > To make the code position independent and to
> permit
> > > the executable to
> > > override symbols defined in the shared library,
> all
> > > global variables
> > > are accessed via a table of addresses (the
> Global
> > > Offset Table, or
> > > GOT) and all functions are called via a table of
> > > branches (the
> > > Procedure Linkage Table, or PLT).  The dynamic
> > > linker initializes the
> > > GOT and PLT at runtime.  The precise details
> depend
> > > on the platform.
> > > 
> > > Ian
> > > 
> > 
> > 
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