From: Ihor Solodrai <ihor.solodrai@linux.dev>
To: Leo Yan <leo.yan@arm.com>, 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
Subject: Re: [PATCH 3/6] libbpf: Initialize CFLAGS before including Makefile.include
Date: Mon, 23 Mar 2026 15:50:30 -0700 [thread overview]
Message-ID: <11402a16-d675-4957-83fb-703082b070e6@linux.dev> (raw)
In-Reply-To: <20260323-tools_build_fix_zero_init_bpf_only-v1-3-d1cfad2f4cd1@arm.com>
On 3/23/26 8:40 AM, Leo Yan wrote:
> 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 $(CLANG_CROSS_FLAGS) again, remove the
> redundant append.
>
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
> tools/lib/bpf/Makefile | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 168140f8e6461bd06db40e23d21a3fb8847ccbf4..eca584fb061e16013e76827e4203f6be0477a73e 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -49,6 +49,14 @@ man_dir_SQ = '$(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)
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
>
> # flags specific for shared library
> SHLIB_FLAGS := -DSHARED -fPIC
>
next prev parent reply other threads:[~2026-03-23 22:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-23 15:40 [PATCH 0/6] tools build: bpf: Append EXTRA_CFLAGS and HOST_EXTRACFLAGS Leo Yan
2026-03-23 15:40 ` [PATCH 1/6] bpftool: Avoid adding EXTRA_CFLAGS to HOST_CFLAGS Leo Yan
2026-03-31 8:46 ` kernel test robot
2026-03-23 15:40 ` [PATCH 2/6] bpftool: Append extra host flags Leo Yan
2026-03-23 15:40 ` [PATCH 3/6] libbpf: Initialize CFLAGS before including Makefile.include Leo Yan
2026-03-23 22:50 ` Ihor Solodrai [this message]
2026-03-23 15:40 ` [PATCH 4/6] tools/bpf: build: Append extra cflags Leo Yan
2026-03-23 15:40 ` [PATCH 5/6] selftests/bpf: Initialize operation name before use Leo Yan
2026-03-23 22:52 ` Ihor Solodrai
2026-03-24 6:58 ` Leo Yan
2026-03-24 15:55 ` Alexei Starovoitov
2026-03-23 15:40 ` [PATCH 6/6] selftests/bpf: Append extra cflags Leo Yan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=11402a16-d675-4957-83fb-703082b070e6@linux.dev \
--to=ihor.solodrai@linux.dev \
--cc=acme@kernel.org \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=haoluo@google.com \
--cc=irogers@google.com \
--cc=james.clark@linaro.org \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=justinstitt@google.com \
--cc=kees@kernel.org \
--cc=kpsingh@kernel.org \
--cc=leo.yan@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=llvm@lists.linux.dev \
--cc=lmb@isovalent.com \
--cc=martin.lau@linux.dev \
--cc=morbo@google.com \
--cc=namhyung@kernel.org \
--cc=nathan@kernel.org \
--cc=nick.desaulniers+lkml@gmail.com \
--cc=qmo@kernel.org \
--cc=sdf@fomichev.me \
--cc=shuah@kernel.org \
--cc=song@kernel.org \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.