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From:   Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
To:     ast@kernel.org, daniel@iogearbox.net, yhs@fb.com,
        davem@davemloft.net, jakub.kicinski@netronome.com, hawk@kernel.org,
        john.fastabend@gmail.com
Cc:     linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        bpf@vger.kernel.org, clang-built-linux@googlegroups.com,
        ilias.apalodimas@linaro.org, sergei.shtylyov@cogentembedded.com,
        Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Subject: [PATCH v4 bpf-next 12/15] libbpf: add C/LDFLAGS to libbpf.so and test_libpf targets
Date:   Wed,  9 Oct 2019 23:41:31 +0300
Message-Id: <20191009204134.26960-13-ivan.khoronzhuk@linaro.org>
In-Reply-To: <20191009204134.26960-1-ivan.khoronzhuk@linaro.org>
References: <20191009204134.26960-1-ivan.khoronzhuk@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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 <ivan.khoronzhuk@linaro.org>
---
 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