[PATCH] libio: Properly link in libio functions in static binaries

[H.J. Lu]

On Mon, Aug 25, 2025 at 6:22 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > On Mon, Aug 25, 2025 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
> >>
> >> * H. J. Lu:
> >>
> >> >> Hmm.  The --strip-unneeded option says this:
> >> >>
> >> >>        --strip-unneeded
> >> >>            Remove all symbols that are not needed for relocation processing in
> >> >>            addition to debugging symbols and sections stripped by
> >> >>            --strip-debug.
> >> >>
> >> >> I think it's a user error to use this on libc.a.  What's the benefit of
> >> >
> >> > Why can't --strip-unneeded be used on libc.a? If a symbol isn't used for
> >> > relocation processing, it is unused.
> >>
> >> It's only unused from the individual .o file that the strip command
> >> processes.  It's not unused from a global perspective.  We'll add more
> >
> > An undefined entry in the symbol table without relocation is unneeded
> > for "relocation processing".
> >
> >> references like these once we improve support for static linking.
> >>
> >> Developers should run --strip-unneeded on the output file, not the input
> >
> > The key word is "relocation processing".   Most of the outputs don't need
> > relocation processing.
>
> Fair point.  But that doesn't explain we need to support running
> --strip-unneeded.  The .symtab references are a surprisingly clean way
> to pull in other objects as needed.  I just don't see a good reason to
> break that, and switch to runtime relocations instead.
>

In theory, a linker can ignore undefined entries in the symbol table without
relocation.

-- 
H.J.