Re: [RFC] elf: Implement filtering of symbols historically defined in libpthread

["H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>]

On Tue, May 4, 2021 at 5:33 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > On Tue, May 4, 2021 at 5:27 AM Florian Weimer <fweimer@redhat.com> wrote:
> >>
> >> * H. J. Lu:
> >>
> >> >> The patch attempts to detect old main programs by looking for the
> >> >> GLIBC_2.34 symbol version.  Since we added __libc_start_main@@GLIBC_2.34
> >> >> (which is called from our version of _start), all standard main programs
> >> >> linked with glibc 2.34 or later will have this symbol version.
> >>
> >> > Can we invent a symbol or version to detect the older binaries?
> >> > If not, can GNU property, ABI note, .... help here?
> >>
> >> I think we have all we need due to __libc_start_main@@GLIBC_2.34.  It
> >> was an unrelated change, but it helps here as well.
> >
> > So your patch isn't required?  Can you add some tests to verify it?
>
> No, the patch uses the absence of GLIBC_2.34 for detecting old binaries.
>
> We cannot use symbol versions in other ways because one key
> characteristic of weak references and underlinking is the lack of
> version information on the symbol itself.

Can we add support for binary testcases like this, even if it can only
run on a single target?  It shouldn't be too hard.

-- 
H.J.