* [PATCH v3 bpf] runqslower: fix Makefile
@ 2020-01-30 23:13 Yulia Kartseva
2020-01-31 0:20 ` Alexei Starovoitov
0 siblings, 1 reply; 2+ messages in thread
From: Yulia Kartseva @ 2020-01-30 23:13 UTC (permalink / raw)
To: bpf, hex, ast, daniel, netdev; +Cc: andriin
Fix undefined reference linker errors when building runqslower with
gcc 7.4.0 on Ubuntu 18.04.
The issue is with misplaced -lelf, -lz options in Makefile:
$(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@
-lelf, -lz options should follow the list of target dependencies:
$(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
or after substitution
cc -g -Wall runqslower.o libbpf.a -lelf -lz -o runqslower
The current order of gcc params causes failure in libelf symbols resolution,
e.g. undefined reference to `elf_memory'
Fixes: 9c01546d26d2 ("tools/bpf: Add runqslower tool to tools/bpf")
Signed-off-by: Julia Kartseva <hex@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
---
tools/bpf/runqslower/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
index 0c021352b..87eae5be9 100644
--- a/tools/bpf/runqslower/Makefile
+++ b/tools/bpf/runqslower/Makefile
@@ -41,7 +41,7 @@ clean:
$(OUTPUT)/runqslower: $(OUTPUT)/runqslower.o $(BPFOBJ)
$(call msg,BINARY,$@)
- $(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@
+ $(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
$(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h \
$(OUTPUT)/runqslower.bpf.o
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3 bpf] runqslower: fix Makefile
2020-01-30 23:13 [PATCH v3 bpf] runqslower: fix Makefile Yulia Kartseva
@ 2020-01-31 0:20 ` Alexei Starovoitov
0 siblings, 0 replies; 2+ messages in thread
From: Alexei Starovoitov @ 2020-01-31 0:20 UTC (permalink / raw)
To: Yulia Kartseva
Cc: bpf, Alexei Starovoitov, Daniel Borkmann, Network Development,
Andrii Nakryiko
On Thu, Jan 30, 2020 at 3:14 PM Yulia Kartseva <hex@fb.com> wrote:
>
> Fix undefined reference linker errors when building runqslower with
> gcc 7.4.0 on Ubuntu 18.04.
> The issue is with misplaced -lelf, -lz options in Makefile:
> $(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@
>
> -lelf, -lz options should follow the list of target dependencies:
> $(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
> or after substitution
> cc -g -Wall runqslower.o libbpf.a -lelf -lz -o runqslower
>
> The current order of gcc params causes failure in libelf symbols resolution,
> e.g. undefined reference to `elf_memory'
>
> Fixes: 9c01546d26d2 ("tools/bpf: Add runqslower tool to tools/bpf")
> Signed-off-by: Julia Kartseva <hex@fb.com>
> Acked-by: Andrii Nakryiko <andriin@fb.com>
Applied. Thanks
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