How to tell if a ELF library/executable was built with -fpic versus -fPIC

How to tell if a ELF library/executable was built with -fpic versus -fPIC

[Tom Kacvinsky]

Perhaps this belongs on the binutils list, but I'd like to know how if an ELF
library/executable was built with -fpic versus -fPIC.  I know each makes PIC
object code, with the difference being the size of the data model:

-msmall-data (-fpic)
-mlarge-data (-fPIC)

but I have some shared libraries I am linking against such that I don't know
which PIC option was used to build it.  Is there an ELF header I can check?

If this is the wrong list to post this, I will redirect to the binutils list.

Thanks,

Tom

Re: How to tell if a ELF library/executable was built with -fpic versus -fPIC

[Florian Weimer]

* Tom Kacvinsky via Gcc-help:

> Perhaps this belongs on the binutils list, but I'd like to know how if an ELF
> library/executable was built with -fpic versus -fPIC.  I know each makes PIC
> object code, with the difference being the size of the data model:
>
> -msmall-data (-fpic)
> -mlarge-data (-fPIC)
>
> but I have some shared libraries I am linking against such that I don't know
> which PIC option was used to build it.  Is there an ELF header I can check?

It depends on the the concrete target.  For a fully linked executable,
you'd have to disassemble it and check what is used for GOT access.  For
relocatable object files, you can look at the relocations.  There should
be an architecture-specific subset that can only handle a limited range,
and that set corresponds to -fpic.

There might be other options that affect the code model, with similar
consequences as the -fpic/-fPIC distinction.

Thanks,
Florian