| Message ID | 20190916105433.11404-12-ivan.khoronzhuk@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | samples: bpf: improve/fix cross-compilation | expand |
On Tue, Sep 17, 2019 at 10:19:22PM -0700, Andrii Nakryiko wrote: >On Mon, Sep 16, 2019 at 4:00 AM Ivan Khoronzhuk ><ivan.khoronzhuk@linaro.org> 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@linaro.org> >> --- >> 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). It's good practice to follow existent style, I've done similar way as for CFLAGS + EXTRACFLAGS here, didn't want to verify it can impact on smth else. And my goal is not to correct everything but embed my functionality, series tool large w/o it. > >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? Seems like, will try in next v. > >> >> $(OUTPUT)libbpf.pc: >> $(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \ >> -- >> 2.17.1 >> -- Regards, Ivan Khoronzhuk
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)|" \
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@linaro.org> --- tools/lib/bpf/Makefile | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) -- 2.17.1