Link with -lm to fix build on arm/mips/risc/ppc

[bluca]

xdp_sample uses floor()/ceil() so every executable that imports that module needs to link with -lm. E.g. on armhf:

gcc -Wall -O2 -g -std=gnu11 -Wextra -Werror -DBPF_DIR_MNT=\"/sys/fs/bpf\" -DBPF_OBJECT_PATH=\"/usr/local/lib/bpf\" -DMAX_DISPATCHER_ACTIONS=10 -DTOOLS_VERSION=\""1.3.0"\" -DLIBBPF_VERSION=\"1.1.0\" -DRUNDIR=\"/run\" -DHAVE_LIBBPF_PERF_BUFFER__CONSUME -DHAVE_LIBBPF_BTF__LOAD_FROM_KERNEL_BY_ID -DHAVE_LIBBPF_BTF__TYPE_CNT -DHAVE_LIBBPF_BPF_OBJECT__NEXT_MAP -DHAVE_LIBBPF_BPF_OBJECT__NEXT_PROGRAM -DHAVE_LIBBPF_BPF_PROGRAM__INSN_CNT -DHAVE_LIBBPF_BPF_MAP_CREATE -DHAVE_LIBBPF_PERF_BUFFER__NEW_RAW -DHAVE_LIBBPF_BPF_XDP_ATTACH -DHAVE_LIBBPF_BPF_MAP__SET_AUTOCREATE -DHAVE_LIBBPF_BPF_PROG_TEST_RUN_OPTS -DHAVE_SECURE_GETENV -DLIBBPF_DYNAMIC -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I../../headers -I../util   -L../libxdp -o test-tool ../util/params.o ../util/logging.o ../util/util.o ../util/stats.o ../util/xpcapng.o ../util/xdp_sample.o \
 test-tool.c  -l:libxdp.a  -lbpf
/usr/bin/ld: ../util/xdp_sample.o: in function `sample_round':
/home/bluca/xdp-tools-1.3.0/lib/util/xdp_sample.c:542: undefined reference to `trunc'
/usr/bin/ld: /home/bluca/xdp-tools-1.3.0/lib/util/xdp_sample.c:544: undefined reference to `ceil'
/usr/bin/ld: /home/bluca/xdp-tools-1.3.0/lib/util/xdp_sample.c:542: undefined reference to `floor'

Signed-off-by: Luca Boccassi bluca@debian.org

[tohojo]

Thanks for the fix! Why is it needed for xdp-loader, xdpdump and xdp-filter, though?

[bluca]

It's included in those executables too by the makefile, so those builds fail too

[tohojo]

So even though no functions from xdp_sample.o is included in the executable, just adding it to the linking step is enough to trigger an error?

In that case I think it's better to just add LDLIBS += -lm in common.mk instead of having to add it to every executable...

[bluca]

ok, updated

[tohojo]

Could you please remove the now-redundant USER_LIBS from xdp-bench and xdp-monitor as well?

[bluca]

done