Re: [PATCH v4 07/30] libbpf: Initialize CFLAGS before including Makefile.include

[Leo Yan]

Hi BPF maintainers,

On Wed, Mar 11, 2026 at 08:29:32AM +0000, 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.
> 
> Signed-off-by: Leo Yan <leo.yan@xxxxxxx>

Before sending a new version, I'd check if you have a chance to review
the libbpf patches.  The libbpf change is crucial for this series.

Another reason for pinging because I received a bpf-ci report about test
failures for this series [1].  The failures looks to be unrelated, as
the tests fail starting from the first patch, which is irrelevant to BPF
code [2].  I tried reaching kernel-ci@xxxxxxxx last week but haven't
received a response yet.

If bpf-ci testing is mandatory for libbpf patches, could you advise me
on the correct workflow (e.g., whether the patches should be based on a
specific branch)?

Thanks.

[1] https://github.com/kernel-patches/bpf/actions/runs/22944268645
[2] https://patchwork.kernel.org/project/netdevbpf/patch/20260311-tools_build_fix_zero_init-v4-1-9e35bdb99cb3@xxxxxxx/

> ---
>  tools/lib/bpf/Makefile | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index b1fbd0211c5edde7be3d98630b16e53e028d9116..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
> @@ -84,6 +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 += $(EXTRA_CFLAGS)
>  
>  # flags specific for shared library
>  SHLIB_FLAGS := -DSHARED -fPIC
> 
> -- 
> 2.34.1
>