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SubjectRe: [PATCH bpf-next 10/11] libbpf: makefile: add C/CXX/LDFLAGS to libbpf.so and test_libpf targets
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On 9/10/19 11:38 AM, Ivan Khoronzhuk wrote:
> In case of LDFLAGS and EXTRA_CC/CXX flags there is no way to pass them
> correctly to build command, for instance when --sysroot is used or
> external libraries are used, like -lelf, wich can be absent in
> toolchain. This is used for samples/bpf cross-compiling allowing to
> get elf lib from sysroot.
>
> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
> ---
> samples/bpf/Makefile | 8 +++++++-
> tools/lib/bpf/Makefile | 11 ++++++++---
> 2 files changed, 15 insertions(+), 4 deletions(-)

Could you separate this patch into two?
One of libbpf and another for samples.

The subject 'libbpf: ...' is not entirely accurate.

>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 79c9aa41832e..4edc5232cfc1 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -186,6 +186,10 @@ ccflags-y += -I$(srctree)/tools/perf
> ccflags-y += $(D_OPTIONS)
> ccflags-y += -Wall
> ccflags-y += -fomit-frame-pointer
> +
> +EXTRA_CXXFLAGS := $(ccflags-y)
> +
> +# options not valid for C++
> ccflags-y += -Wmissing-prototypes
> ccflags-y += -Wstrict-prototypes
>
> @@ -252,7 +256,9 @@ clean:
>
> $(LIBBPF): FORCE
> # Fix up variables inherited from Kbuild that tools/ build system won't like
> - $(MAKE) -C $(dir $@) RM='rm -rf' LDFLAGS= srctree=$(BPF_SAMPLES_PATH)/../../ O=
> + $(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(PROGS_CFLAGS)" \
> + EXTRA_CXXFLAGS="$(EXTRA_CXXFLAGS)" LDFLAGS=$(PROGS_LDFLAGS) \
> + srctree=$(BPF_SAMPLES_PATH)/../../ O=
>
> $(obj)/syscall_nrs.h: $(obj)/syscall_nrs.s FORCE
> $(call filechk,offsets,__SYSCALL_NRS_H__)
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index c6f94cffe06e..bccfa556ef4e 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -94,6 +94,10 @@ else
> CFLAGS := -g -Wall
> endif
>
> +ifdef EXTRA_CXXFLAGS
> + CXXFLAGS := $(EXTRA_CXXFLAGS)
> +endif
> +
> ifeq ($(feature-libelf-mmap), 1)
> override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
> endif
> @@ -176,8 +180,9 @@ $(BPF_IN): force elfdep bpfdep
> $(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)
>
> $(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN)
> - $(QUIET_LINK)$(CC) --shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
> - -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
> + $(QUIET_LINK)$(CC) $(LDFLAGS) \
> + --shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
> + -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
> @ln -sf $(@F) $(OUTPUT)libbpf.so
> @ln -sf $(@F) $(OUTPUT)libbpf.so.$(LIBBPF_MAJOR_VERSION)
>
> @@ -185,7 +190,7 @@ $(OUTPUT)libbpf.a: $(BPF_IN)
> $(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
>
> $(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
> - $(QUIET_LINK)$(CXX) $(INCLUDES) $^ -lelf -o $@
> + $(QUIET_LINK)$(CXX) $(CXXFLAGS) $(LDFLAGS) $(INCLUDES) $^ -lelf -o $@
>
> $(OUTPUT)libbpf.pc:
> $(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \
>
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