Re: [PATCH v2] elf: Support DT_RELR relative relocation format [BZ #27924]

["H.J. Lu" <hjl.tools@gmail.com>]

On Mon, Oct 18, 2021 at 2:10 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Mon, 18 Oct 2021, Fāng-ruì Sòng via Libc-alpha wrote:
>
> > I know. I have mentioned that the situation is not different from many
> > previous situations where a compatibility check may not catch
> > everything.
>
> That also applies to many changes to glibc functions.
>
> We use symbol versioning when adding new symbols, or when changing a
> symbol in a way incompatible with existing binaries making valid use of
> glibc APIs.  We rarely use it when adding a new feature to an existing
> symbol (for example, a new flag for a function that takes a flags
> argument, or providing stricter guarantees about a return value that
> wasn't fully specified before), even though in fact binaries using the new
> feature would not work correctly when run with older glibc versions.
>
> I don't think a new ELF feature is that different from new features added
> to existing functions.

If a binary requires a new glibc to run, running it with the old glibc will
lead to an ld.so diagnostic message.   DT_RELR shouldn't be different.

-- 
H.J.