[Gcl-devel] Re: relocation overflow

[Geoff Keating]

Daniel Jacobowitz <address@hidden> writes:

> On Wed, Nov 20, 2002 at 12:01:59PM -0500, Camm Maguire wrote:
> > Greetings, and thanks for your reply.
> > 
> > The relocation type is R_PPC_REL24.  I've got the failure up now in
> > gdb and can backtrace into the bfd library if this would help.
> 
> Presumably it won't help - bear in mind, this is a _24-bit_ relocation. 
> You have to load modules close enough that that suffices, or else you
> have to insert trampolines for longer jumps... through a GOT or
> whatever.
> 
> PowerPC GCC doesn't seem to have a long-calls option, so you're just
> out of luck if you can't fit things in 16MB.  Trampolines may be the
> way to go.

The way this is normally done, for programs that load arbitrary
modules, is that each module is a .so file, is built with -fpic, and
is loaded using the dlsym functions.  Then the limit is 32Mb per
module, and you can have as many modules as your address space can
fit; cross-module calls happen through a PLT which can perform long
jumps.

I'm not sure how GCL works, but is it possible that you simply haven't
built the modules with -fpic?

-- 
- Geoffrey Keating <address@hidden>