From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3E7A014B953; Thu, 25 Sep 2025 12:43:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758804201; cv=none; b=CvLsAV8VtFLZeAXLIzMGT4tEZpANwi/CYBs1BM/D2EkaFb/7VnMS7AUw4cc6UA4NJICMcVL0i8bfn99ClRNyw+3R3b3kLMW6S7owKofeHz9dr95Ce7NZG5thLF1VvPSbrlRj1pOIUX3hJsOIyheZ9tWDA7c9qE0x0OzWH7Jzw5k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758804201; c=relaxed/simple; bh=gcHZwcDMSIGu3KYmFLAtCFzPUJCXH64+5aDEv1Ci6FY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UET+8kSKiPVrIr4Ut1l+pQEmo82gP29dv9fW5kR6XOsIN5w1JUIYT+RG3p5AGQzQYza+bSGPNg55ndIxUS6TjrOdQcqnc4hgx6q2y477W9PCY8kFRHKbR1Y4339ymbNN6szDfyneb0sQtOof2hvvW3ncYV2JzLfecFcGbm3rGZs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4DAD91692; Thu, 25 Sep 2025 05:43:10 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0841B3F694; Thu, 25 Sep 2025 05:43:18 -0700 (PDT) Date: Thu, 25 Sep 2025 13:43:16 +0100 From: Leo Yan To: Quentin Monnet Cc: Arnaldo Carvalho de Melo , Namhyung Kim , Jiri Olsa , Ian Rogers , Adrian Hunter , Andrii Nakryiko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , James Clark , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, llvm@lists.linux.dev, bpf@vger.kernel.org Subject: Re: [PATCH 3/8] bpftool: Conditionally add -Wformat-signedness flag Message-ID: <20250925124316.GA7985@e132581.arm.com> References: <20250925-perf_build_android_ndk-v1-0-8b35aadde3dc@arm.com> <20250925-perf_build_android_ndk-v1-3-8b35aadde3dc@arm.com> <52fe87ef-0797-4cf1-9e70-dc218f904e77@kernel.org> 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: <52fe87ef-0797-4cf1-9e70-dc218f904e77@kernel.org> On Thu, Sep 25, 2025 at 11:42:39AM +0100, Quentin Monnet wrote: > 2025-09-25 11:26 UTC+0100 ~ Leo Yan > > clang-18.1.3 on Ubuntu 24.04.2 reports warning: > > > > warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] > > > > Conditionally add the option only when it is supported by compiler. > > > > Signed-off-by: Leo Yan > > > Hi, how annoying is this warning? Not too bad, it prints out 5~6 times warnings (see the build log below). Though the warnings are a bit noisy, they does not break the build. > I'm asking because as far as I > understand, the option has been introduced in LLVM 19.1.0 [0] - the > latest being 21.1.0 already - so we won't need this check once distros > have transitioned, and I'm a bit reluctant to add it. I agree the warning likely won't affect distros, as package maintainers will hide it. But it can annoy _paranoid_ developers in day-to-day builds ;) As the warning doesn't block anything, so I am fine with not merging this patch. Thanks, Leo > [0] > https://github.com/llvm/llvm-project/commit/ea92b1f9d0fc31f1fd97ad04eb0412003a37cb0d ---8<--- Auto-detecting system features: ... clang-bpf-co-re: [ on ] ... llvm: [ OFF ] ... libcap: [ on ] ... libbfd: [ OFF ] ... libbfd-liberty: [ OFF ] ... libbfd-liberty-z: [ OFF ] ... disassembler-four-args: [ OFF ] ... disassembler-init-styled: [ OFF ] ... libelf-zstd: [ o MKDIR /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf MKDIR /build/util/bpf_skel/.tmp/bootstrap/libbpf/ MKDIR /build/util/bpf_skel/.tmp/bootstrap/ INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/hashmap.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/relo_core.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_internal.h warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] 1 warning generated. GEN /build/util/bpf_skel/.tmp/bootstrap/libbpf/bpf_helper_defs.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_legacy.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/btf.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helpers.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_common.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_tracing.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_core_read.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_endian.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/libbpf_version.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/skel_internal.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/usdt.bpf.h INSTALL /build/util/bpf_skel/.tmp/bootstrap/libbpf/include/bpf/bpf_helper_defs.h INSTALL libbpf_headers CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/nlattr.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_errno.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/str_error.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/netlink.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/bpf_prog_linfo.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf_probes.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/hashmap.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_dump.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/ringbuf.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/strset.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/gen_loader.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/relo_core.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/linker.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/usdt.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/zip.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/elf.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/features.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_iter.o CC /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/btf_relocate.o LD /build/util/bpf_skel/.tmp/bootstrap/libbpf/staticobjs/libbpf-in.o LINK /build/util/bpf_skel/.tmp/bootstrap/libbpf/libbpf.a CC /build/util/bpf_skel/.tmp/bootstrap/main.o CC /build/util/bpf_skel/.tmp/bootstrap/common.o CC /build/util/bpf_skel/.tmp/bootstrap/json_writer.o CC /build/util/bpf_skel/.tmp/bootstrap/gen.o CC /build/util/bpf_skel/.tmp/bootstrap/btf.o warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option]warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] warning: unknown warning option '-Wformat-signedness' [-Wunknown-warning-option] 1 warning generated. 1 warning generated. 1 warning generated. 1 warning generated. 1 warning generated. LINK /build/util/bpf_skel/.tmp/bootstrap/bpftool