[PATCH] Fix glibc 2.34 ABI omission (missing GLIBC_2.34 in dynamic loader)

[Florian Weimer]

* Andreas Schwab:

> On Dez 08 2021, Florian Weimer wrote:
>
>> * Andreas Schwab:
>>
>>> On Dez 08 2021, Florian Weimer via Libc-alpha wrote:
>>>
>>>> The glibc 2.34 release really should have added a GLIBC_2.34
>>>> symbol to the dynamic loader.
>>>
>>> Well, the ship has sailed.
>>
>> Has it?  It's just software, we can change it.
>
> ABI is not software, it's a contract.

But sometimes we have to to fix bugs.  Again, what I propose is quite
different from a simple symbol change because distributions and users
can fix this now, well before the symbol is going to be used.

I have considered using a stub DSO and mention that instead of libc.so.6
in the libc.so linker script.  But I'm not sure how we can prevent users
from linking against the moved symbol by bypassing the linker script.
That would produce ABI-incompatible binaries.  We could turn it into a
compat symbol, but as long as it's in the dynamic symbol table, some
people will use it.

Thanks,
Florian