From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vmicros1.altlinux.org (vmicros1.altlinux.org [194.107.17.57]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4D24741C315; Mon, 2 Mar 2026 15:28:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.107.17.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772465304; cv=none; b=Pdli/3us2wAo3dpMq9MeOzlTuai9bR2CuxoOCoAcFnGbHThRIAVqXYnNMZCK1mqdr5K620J4aj3jFEUZ6N55kDn1dO9kBetpG3g0ntchvYswbCTG/aTLB3jC8PSus2HRQsch/ioCDDus3B4stNwxBmbRxuOHEIGB0S6icq6Hki0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772465304; c=relaxed/simple; bh=cnXkDmiK4nEkXfkpUw2O+7yQ+cbRQCkc1IuPQRsmliA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MlPy6Pw0dOHk91WzpDZ+aaxfKNjA0R9wIbwe4N0QrjKa5vYjCY6b0Ib9VM0Znm5ZuR3QgLLIWNrmpi6XLSQv77mKaUtQxtUPPtqzkK/5ZtBIfM/u+9zQE3CttIQaG53Px/6gqNS8FlNgOhhHgxCKlcmxBQfP5B/mKXwu1p0+ZbQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org; spf=pass smtp.mailfrom=altlinux.org; arc=none smtp.client-ip=194.107.17.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=altlinux.org Received: from imap.altlinux.org (imap.altlinux.org [194.107.17.38]) by vmicros1.altlinux.org (Postfix) with ESMTP id D85D772C8CC; Mon, 2 Mar 2026 18:22:12 +0300 (MSK) Received: from pony.office.basealt.ru (unknown [193.43.10.9]) by imap.altlinux.org (Postfix) with ESMTPSA id D141436D00D3; Mon, 2 Mar 2026 18:22:12 +0300 (MSK) Received: by pony.office.basealt.ru (Postfix, from userid 500) id A1D68360D75C; Mon, 2 Mar 2026 18:22:12 +0300 (MSK) Date: Mon, 2 Mar 2026 18:22:12 +0300 From: Vitaly Chikunov To: Ihor Solodrai Cc: bot+bpf-ci@kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, olsajiri@gmail.com, yatsenko@meta.com, alexis.lothore@bootlin.com, ameryhung@gmail.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, martin.lau@kernel.org, yonghong.song@linux.dev, clm@meta.com Subject: Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids Message-ID: References: <20260220222604.1155148-2-ihor.solodrai@linux.dev> <789af3df-291c-410d-89d8-ee7b12479798@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <789af3df-291c-410d-89d8-ee7b12479798@linux.dev> Ihor, On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote: > > > On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote: > >> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile > >> index 1733a6e93a07..ef083602b73a 100644 > >> --- a/tools/bpf/resolve_btfids/Makefile > >> +++ b/tools/bpf/resolve_btfids/Makefile > >> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU > >> LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null) > >> LIBELF_LIBS := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf) > >> > >> +ZLIB_LIBS := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz) > >> +ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd) > > > > The "|| echo -lzstd" fallback makes zstd an unconditional link > > dependency. On systems where libzstd-dev is not installed, pkg-config > > fails and the fallback provides -lzstd, but the linker cannot find the > > library and the build fails. > > > > bpftool handles the same transitive dependency conditionally via a > > feature test: > > > > tools/bpf/bpftool/Makefile: > > ifeq ($(feature-libelf-zstd),1) > > LIBS += -lzstd > > LIBS_BOOTSTRAP += -lzstd > > endif > > > > Would it be safer to drop the fallback here so ZSTD_LIBS is empty > > when zstd is not available? > > > > ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null) > > > > This would still link zstd when present (needed for the static linking > > case where libelf.a pulls in ZSTD symbols from elf_compress.o), but > > avoid breaking dynamic builds on systems without libzstd-dev. > > I tried to reproduce the situation like follows: > > $ git remote -v > origin git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (fetch) > origin git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (push) > > $ git log --oneline -n1 > 8bf22c33e7a1 (HEAD -> master, origin/master, origin/HEAD) Merge tag 'net-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net > > $ b4 shazam 20260220182011.802116-1-ihor.solodrai@linux.dev # apply strscpy series > $ b4 shazam 20260220222604.1155148-1-ihor.solodrai@linux.dev # apply ASAN series > > $ podman pull debian:latest > $ podman run -it --rm -v $(pwd):/linux debian:latest /bin/bash > > # in the container > $ apt update -y && apt install -y make gcc python3 libelf-dev > # note: no libzstd-dev > > $ cd /linux/tools/bpf/resolve_btfids/ > $ make -j8 > # build is successful > > $ ldd resolve_btfids > linux-vdso.so.1 (0x00007f3eecc81000) > libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007f3eecbe2000) > libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f3eecbc2000) > libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3eec9cd000) > libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f3eec903000) > /lib64/ld-linux-x86-64.so.2 (0x00007f3eecc83000) > > > So, while AI may be technically correct that the build will fail if > libelf is installed and libzstd is not, it seems a far-fetched > situation, given that libelf depends on libzstd. This is not far-fetched, and we have build failure for v7.0-rc2 due to this. ld: cannot find -lzstd: No such file or directory Even though libelf is linked with libzstd, this does not imply libzstd-devel (with headers and so library) is there when building. Thanks, > > I think we can leave the default -lzstd to have an explicit > dependency in the Makefile. > > > > > > [ ... ] > > > > > > --- > > AI reviewed your patch. Please fix the bug or email reply why it's not a bug. > > See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md > > > > CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22243753316 > > > > AI-authorship-score: low > > AI-authorship-explanation: Human-characteristic typo in commit message, natural lore discussion with incremental debugging, and standard Makefile pattern reuse all indicate human authorship. > > issues-found: 1 > > issue-severity-score: low > > issue-severity-explanation: Unconditional zstd link fallback in resolve_btfids Makefile can break builds on systems without libzstd-dev, but the affected scenario is narrow and limited to the selftests build system. >