2019-10-11 00:31:23

by Ivan Khoronzhuk

Subject: [PATCH v5 bpf-next 12/15] libbpf: add C/LDFLAGS to libbpf.so and test_libpf targets

In case of C/LDFLAGS 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 <[email protected]>
---
tools/lib/bpf/Makefile | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 46280b5ad48d..75b538577c17 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -174,8 +174,9 @@ bpf_helper_defs.h: $(srctree)/include/uapi/linux/bpf.h
$(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)

@@ -183,7 +184,7 @@ $(OUTPUT)libbpf.a: $(BPF_IN)
$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^

$(OUTPUT)test_libbpf: test_libbpf.c $(OUTPUT)libbpf.a
- $(QUIET_LINK)$(CC) $(INCLUDES) $^ -lelf -o $@
+ $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(INCLUDES) $^ -lelf -o $@

$(OUTPUT)libbpf.pc:
$(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \
--
2.17.1

2019-10-12 16:38:49

by Andrii Nakryiko

Subject: Re: [PATCH v5 bpf-next 12/15] libbpf: add C/LDFLAGS to libbpf.so and test_libpf targets

On Thu, Oct 10, 2019 at 5:29 PM Ivan Khoronzhuk
<[email protected]> wrote:
>
> In case of C/LDFLAGS 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 <[email protected]>
> ---

Acked-by: Andrii Nakryiko <[email protected]>

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