In samples/bpf/Makefile, libbpf has a FORCE dependency that force it to be rebuilt. I read this as a way to keep the library up-to-date, given that we do not have, in samples/bpf, a list of the source files for libbpf itself. However, a better approach would be to use the "$(wildcard ...)" function from make, and to have libbpf depend on all the .c and .h files in its directory. This is what samples/bpf/Makefile does for bpftool, and also what the BPF selftests' Makefile does for libbpf. Let's update the Makefile to avoid rebuilding libbpf all the time (and bpftool on top of it). Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> --- samples/bpf/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index cb72198f6b48..c9cee54ce79d 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -276,7 +276,8 @@ clean: @find $(CURDIR) -type f -name '*~' -delete @$(RM) -r $(CURDIR)/libbpf $(CURDIR)/bpftool -$(LIBBPF): FORCE | $(LIBBPF_OUTPUT) +$(LIBBPF): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) \ + | $(LIBBPF_OUTPUT) # Fix up variables inherited from Kbuild that tools/ build system won't like $(MAKE) -C $(LIBBPF_SRC) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \ LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ \ -- 2.30.2
