lkml.org 
[lkml]   [2019]   [Sep]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v3 bpf-next 11/14] libbpf: makefile: add C/CXX/LDFLAGS to libbpf.so and test_libpf targets
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).

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
>

\
 
 \ /
  Last update: 2019-09-18 07:20    [W:0.291 / U:2.584 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site