On Thu, Jan 30, 2020 at 3:14 PM Yulia Kartseva [off-list ref] 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 <redacted>
Acked-by: Andrii Nakryiko <redacted>

Applied. Thanks