From: Leo Yan <leo.yan@arm.com>
To: Quentin Monnet <qmo@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>,
Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
Shuah Khan <shuah@kernel.org>, Lorenz Bauer <lmb@isovalent.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
James Clark <james.clark@linaro.org>,
Kees Cook <kees@kernel.org>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, llvm@lists.linux.dev,
Leo Yan <leo.yan@arm.com>
Subject: [PATCH bpf-next v2 1/8] bpftool: Pass host flags to bootstrap libbpf
Date: Tue, 02 Jun 2026 15:47:10 +0100 [thread overview]
Message-ID: <20260602-tools_build_fix_zero_init_bpf_only-v2-1-c76e5250ea1c@arm.com> (raw)
In-Reply-To: <20260602-tools_build_fix_zero_init_bpf_only-v2-0-c76e5250ea1c@arm.com>
bpftool builds a bootstrap libbpf with HOSTCC, but the libbpf submake can
still inherit target build flags through CFLAGS. This can break cross
builds when host objects are compiled with target-only options.
Since HOST_CFLAGS contains warning options that are not suitable for
building libbpf, use LIBBPF_BOOTSTRAP_CFLAGS with the warning options
removed to build the bootstrap libbpf. Clear EXTRA_CFLAGS so target
extra flags are not mixed into the host bootstrap libbpf build.
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
tools/bpf/bpftool/Makefile | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 0febf60e1b64656035dfe93cd15cba090015587a..1f033e578f90a2d6b93168ab41399de758bdf659 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -47,7 +47,8 @@ $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_HDRS_
$(LIBBPF_BOOTSTRAP): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_BOOTSTRAP_OUTPUT)
$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_BOOTSTRAP_OUTPUT) \
DESTDIR=$(LIBBPF_BOOTSTRAP_DESTDIR:/=) prefix= \
- ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" $@ install_headers
+ ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" \
+ CFLAGS="$(LIBBPF_BOOTSTRAP_CFLAGS)" EXTRA_CFLAGS= $@ install_headers
$(LIBBPF_BOOTSTRAP_INTERNAL_HDRS): $(LIBBPF_BOOTSTRAP_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_BOOTSTRAP_HDRS_DIR)
$(call QUIET_INSTALL, $@)
@@ -92,6 +93,9 @@ HOST_CFLAGS := $(subst -I$(LIBBPF_INCLUDE),-I$(LIBBPF_BOOTSTRAP_INCLUDE),\
$(subst $(CLANG_CROSS_FLAGS),,$(CFLAGS)))
HOST_LDFLAGS := $(LDFLAGS)
+# Remove warnings for libbpf bootstrap build
+LIBBPF_BOOTSTRAP_CFLAGS := $(filter-out -W -Wall -Wextra -Wformat -Wformat-signedness,$(HOST_CFLAGS))
+
INSTALL ?= install
RM ?= rm -f
--
2.34.1
next prev parent reply other threads:[~2026-06-02 14:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 14:47 [PATCH bpf-next v2 0/8] tools build: bpf: Append EXTRA_CFLAGS and HOST_EXTRACFLAGS Leo Yan
2026-06-02 14:47 ` Leo Yan [this message]
2026-06-03 9:21 ` [PATCH bpf-next v2 1/8] bpftool: Pass host flags to bootstrap libbpf Quentin Monnet
2026-06-02 14:47 ` [PATCH bpf-next v2 2/8] bpftool: Avoid adding EXTRA_CFLAGS to HOST_CFLAGS Leo Yan
2026-06-02 14:47 ` [PATCH bpf-next v2 3/8] bpftool: Append extra host flags Leo Yan
2026-06-02 14:47 ` [PATCH bpf-next v2 4/8] libbpf: Initialize CFLAGS before including Makefile.include Leo Yan
2026-06-02 14:47 ` [PATCH bpf-next v2 5/8] tools/bpf: build: Append extra cflags Leo Yan
2026-06-13 1:09 ` Ihor Solodrai
2026-06-02 14:47 ` [PATCH bpf-next v2 6/8] selftests/bpf: Initialize operation name before use Leo Yan
2026-06-13 1:11 ` Ihor Solodrai
2026-06-02 14:47 ` [PATCH bpf-next v2 7/8] selftests/bpf: Use common CFLAGS for urandom_read Leo Yan
2026-06-02 15:32 ` bot+bpf-ci
2026-06-02 14:47 ` [PATCH bpf-next v2 8/8] selftests/bpf: Avoid static LLVM linking for cross builds Leo Yan
2026-06-15 0:40 ` [PATCH bpf-next v2 0/8] tools build: bpf: Append EXTRA_CFLAGS and HOST_EXTRACFLAGS patchwork-bot+netdevbpf
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