[v2,1/2] oeqa/selftest/rust: pass zlib/zstd link args to test build

From: Peter Tatrai <peter.tatrai.ext@siemens.com>

Pass -lz and -lzstd linker arguments via RUSTFLAGS when running the
bootstrap test suite.

The Rust self-test executes 'python3 src/bootstrap/bootstrap.py test --target'
on the host, which builds and links test binaries for the target architecture
(these binaries are then uploaded to QEMU for execution). The test binaries
use LLVM's compression functionality and require explicit linker flags for
zlib and zstd.

The RUSTFLAGS exported at recipe level (in rust_1.90.0.bb) do not propagate
to this bootstrap test invocation in the selftest harness, so we must set them
explicitly in the test command.

This fixes PowerPC (qemuppc) test failures with undefined references:
  undefined reference to 'compress2'
  undefined reference to 'uncompress'
  undefined reference to 'ZSTD_decompress'
  undefined reference to 'ZSTD_isError'
  undefined reference to 'ZSTD_compress2'
  undefined reference to 'crc32'

Signed-off-by: Peter Tatrai <peter.tatrai.ext@siemens.com>
---
 meta/lib/oeqa/selftest/cases/rust.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On Mon, 3 Nov 2025 at 09:29, Tatrai, Peter via lists.openembedded.org
<peter.tatrai.ext=siemens.com@lists.openembedded.org> wrote:
> This fixes PowerPC (qemuppc) test failures with undefined references:
>   undefined reference to 'compress2'
>   undefined reference to 'uncompress'
>   undefined reference to 'ZSTD_decompress'
>   undefined reference to 'ZSTD_isError'
>   undefined reference to 'ZSTD_compress2'
>   undefined reference to 'crc32'
> -            cmd = cmd + " export RUSTFLAGS='-C strip=debuginfo';"
> +            cmd = cmd + " export RUSTFLAGS='-C strip=debuginfo -Clink-arg=-lz -Clink-arg=-lzstd';"

But this still does not explain why the issue is specific to powerpc.
Can you get to the bottom of it?

Alex

On Mon, Nov 3, 2025 at 3:22 AM Alexander Kanavin via
lists.openembedded.org <alex.kanavin=gmail.com@lists.openembedded.org>
wrote:
>
> On Mon, 3 Nov 2025 at 09:29, Tatrai, Peter via lists.openembedded.org
> <peter.tatrai.ext=siemens.com@lists.openembedded.org> wrote:
> > This fixes PowerPC (qemuppc) test failures with undefined references:
> >   undefined reference to 'compress2'
> >   undefined reference to 'uncompress'
> >   undefined reference to 'ZSTD_decompress'
> >   undefined reference to 'ZSTD_isError'
> >   undefined reference to 'ZSTD_compress2'
> >   undefined reference to 'crc32'
> > -            cmd = cmd + " export RUSTFLAGS='-C strip=debuginfo';"
> > +            cmd = cmd + " export RUSTFLAGS='-C strip=debuginfo -Clink-arg=-lz -Clink-arg=-lzstd';"
>
> But this still does not explain why the issue is specific to powerpc.
> Can you get to the bottom of it?

We have compressed debug info enabled in gcc llvm and binutils so it
needed libctf.so and libbfd.so to deal with these symbols and rust's
linker wrapper calls the system linker
so there is a transitive dependency on zlib and libzstd, for x86_64, I
see them in DT_NEEDED section so transitive dependency is met. Since
we use --as-needed by default
I am guessing on ppc the linker somehow ignores these libs and does
not add them to DT_NEEDED segments and autoloading does not happen.
Please look into these directions

>
> Alex
>
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