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SubjectRe: [PATCH bpf-next 10/11] libbpf: makefile: add C/CXX/LDFLAGS to libbpf.so and test_libpf targets
On Fri, Sep 13, 2019 at 09:43:22PM +0000, Yonghong Song wrote:
>
>
>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.
Yes, ofc.
But there is too many patches already, but better a lot of small
changes then couple huge.

>
>>
>> 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)|" \
>>

--
Regards,
Ivan Khoronzhuk

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