On Mon, Sep 16, 2019 at 4:00 AM Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> 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 can be used for samples/bpf cross-compiling allowing > to get elf lib from sysroot. > > Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx> > --- > tools/lib/bpf/Makefile | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > 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 $@ Instead of doing ifdef EXTRA_CXXFLAGS bit above, you can just include both $(CXXFLAGS) and $(EXTRA_CXXFLAGS), which will do the right thing (and is actually recommended my make documentation way to do this). But actually, there is no need to use C++ compiler here, test_libbpf.cpp can just be plain C. Do you mind renaming it to .c and using C compiler instead? > > $(OUTPUT)libbpf.pc: > $(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \ > -- > 2.17.1 >
