Re: -fPIC and shared object

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-fPIC and shared object
\ Olivier Delannoy (28 Jun 2007)
. \ Andrew Haley (28 Jun 2007)

Subject:	Re: -fPIC and shared object
Group:	Gcc-help
From:	Andrew Haley
Date:	28 Jun 2007

Olivier Delannoy writes:
> Hello,
>
> I am using linux and I would like to understand the role of -fPIC. I
> understand that it generate code where function address can be
> calculated indirectly after relocation of the .so in applications
> using it. My questions are :
>
> - Is it required to compile with -fPIC every object file packed in a
> dynamic shared object ?

Yes. (Well, kinda: there is a platform that allows relocation to be
performed on shared objects after loading, but it's inefficient and is
purely a backawards compatibility hack.)

> - Is is possible to integrate a static library in a .so safely
> (assuming the static library is not compiled using -fPIC)

No.

> - Is the answer to the previous question the same if the library is
> used only within the boundary of the .so (hidden to the rest of the
> application) ?

Yes.

Andrew.