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>,
Ihor Solodrai <ihor.solodrai@linux.dev>
Subject: [PATCH bpf-next v2 4/8] libbpf: Initialize CFLAGS before including Makefile.include
Date: Tue, 02 Jun 2026 15:47:13 +0100 [thread overview]
Message-ID: <20260602-tools_build_fix_zero_init_bpf_only-v2-4-c76e5250ea1c@arm.com> (raw)
In-Reply-To: <20260602-tools_build_fix_zero_init_bpf_only-v2-0-c76e5250ea1c@arm.com>
tools/scripts/Makefile.include may expand EXTRA_CFLAGS in a future
change. This could alter the initialization of CFLAGS, as the default
options "-g -O2" would never be set once EXTRA_CFLAGS is expanded.
Prepare for this by moving the CFLAGS initialization before including
tools/scripts/Makefile.include, so it is not affected by the extended
EXTRA_CFLAGS.
Append EXTRA_CFLAGS to CFLAGS only after including Makefile.include and
place it last so that the extra flags propagate properly and can
override the default options.
tools/scripts/Makefile.include already appends $(CLANG_CROSS_FLAGS) to
CFLAGS, the Makefile appends $(CLANG_CROSS_FLAGS) again, remove the
redundant append.
Signed-off-by: Leo Yan <leo.yan@arm.com>
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
tools/lib/bpf/Makefile | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 168140f8e6461bd06db40e23d21a3fb8847ccbf4..eca584fb061e16013e76827e4203f6be0477a73e 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -49,6 +49,14 @@ man_dir_SQ = '$(subst ','\'',$(man_dir))'
export man_dir man_dir_SQ INSTALL
export DESTDIR DESTDIR_SQ
+# Defer assigning EXTRA_CFLAGS to CFLAGS until after including
+# tools/scripts/Makefile.include, as it may add flags to EXTRA_CFLAGS.
+ifdef EXTRA_CFLAGS
+ CFLAGS :=
+else
+ CFLAGS := -g -O2
+endif
+
include $(srctree)/tools/scripts/Makefile.include
# copy a bit from Linux kbuild
@@ -70,13 +78,6 @@ LIB_TARGET = libbpf.a libbpf.so.$(LIBBPF_VERSION)
LIB_FILE = libbpf.a libbpf.so*
PC_FILE = libbpf.pc
-# Set compile option CFLAGS
-ifdef EXTRA_CFLAGS
- CFLAGS := $(EXTRA_CFLAGS)
-else
- CFLAGS := -g -O2
-endif
-
# Append required CFLAGS
override CFLAGS += -std=gnu89
override CFLAGS += $(EXTRA_WARNINGS) -Wno-switch-enum
@@ -84,7 +85,7 @@ override CFLAGS += -Werror -Wall
override CFLAGS += $(INCLUDES)
override CFLAGS += -fvisibility=hidden
override CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
-override CFLAGS += $(CLANG_CROSS_FLAGS)
+override CFLAGS += $(EXTRA_CFLAGS)
# flags specific for shared library
SHLIB_FLAGS := -DSHARED -fPIC
--
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 ` [PATCH bpf-next v2 1/8] bpftool: Pass host flags to bootstrap libbpf Leo Yan
2026-06-03 9:21 ` 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 ` Leo Yan [this message]
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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