Bug#1122038: libc6-dev: symbols not covering GLIBC_ABI_GNU_TLS on i386

[Adrian Bunk <bunk@debian.org>]

On Sat, Dec 06, 2025 at 05:51:51PM +0100, Aurelien Jarno wrote:
> Hi,
> 
> On 2025-12-06 14:59, Samuel Thibault wrote:
> > Samuel Thibault, le sam. 06 déc. 2025 14:53:44 +0100, a ecrit:
> > > Adrian Bunk, le sam. 06 déc. 2025 07:22:50 +0200, a ecrit:
> > > > https://ci.debian.net/packages/s/starpu/testing/i386/66851610/
> > > > 
> > > > ...
> > > >  45s starpu_machine_display: /lib/i386-linux-gnu/libc.so.6: version `GLIBC_ABI_GNU_TLS' not found (required by starpu_machine_display)
> > > > ...
> > > > 
> > > > 
> > > > This can be reproduced with starpu-tools/unstable and libc6/forky:
> > > > 
> > > > $ starpu_machine_display
> > > > starpu_machine_display: /lib/i386-linux-gnu/libc.so.6: version `GLIBC_ABI_GNU_TLS' not found (required by starpu_machine_display)
> > > 
> > > And more generally, a mere program int main(void) {} compiled with
> > > unstable gets this error in forky. Libraries are not affected.
> > 
> > (for the background, this symbol is apparently on purpose on i386:
> > https://sourceware.org/git/?p=glibc.git;a=commit;h=ed1b7a5a489ab555a27fad9c101ebe2e1c1ba881
> > https://sourceware.org/bugzilla/show_bug.cgi?id=32996 )
> 
> Yes. And the symbol is actually correctly covered in the symbols file. 
> But it is exported as part of the .gnu.version_r section, which is not 
> checked by dpkg-gensymbols.
> 
> At this stage, I do not have more idea than forcing the minimum version 
> to 2.42 on i386. That will be for all binaries, not the ones actually 
> needing that (e.g. libraries).

Urgent is to get a fixed/workarounded glibc before the chroot rebuilds 
tomorrow evening, package builds updating libc6 are rare and so far only
a dozen packages are affected but staring Monday the binNMU list would
become huge.

Updating trixie to the latest 2.41 git would bring the same issue there.

    Add GLIBC_ABI_GNU_TLS version to indicate that glibc has the working
    GNU TLS run-time.  Linker can add the GLIBC_ABI_GNU_TLS version to
    binaries which depend on the working TLS run-time so that such programs
    and shared libraries will fail to load and run at run-time against
    libc.so without the GLIBC_ABI_GNU_TLS version, instead of fail silently
    at random.

Doesn't this say that it is a bug when every single program picks up a 
dependency on GLIBC_ABI_GNU_TLS?

Unless I misunderstand something all this is about a glibc-internal 
bugfix for a (rare) bug, not any ABI change/addition.

> Regards
> Aurelien

cu
Adrian