The "install_headers" target in libbpf's Makefile would unconditionally export all API headers to the target directory. When those headers are installed to compile another application, this means that make always finds newer dependencies for the source files relying on those headers, and deduces that the targets should be rebuilt. Avoid that by making "install_headers" depend on the source header files, and (re-)install them only when necessary. Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> --- tools/lib/bpf/Makefile | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile index 41e4f78dbad5..a92d3b9692a8 100644 --- a/tools/lib/bpf/Makefile +++ b/tools/lib/bpf/Makefile @@ -241,15 +241,23 @@ install_lib: all_cmd $(call do_install_mkdir,$(libdir_SQ)); \ cp -fpR $(LIB_FILE) $(DESTDIR)$(libdir_SQ) -INSTALL_HEADERS = bpf.h libbpf.h btf.h libbpf_common.h libbpf_legacy.h xsk.h \ - bpf_helpers.h $(BPF_GENERATED) bpf_tracing.h \ - bpf_endian.h bpf_core_read.h skel_internal.h \ - libbpf_version.h +SRC_HDRS := bpf.h libbpf.h btf.h libbpf_common.h libbpf_legacy.h xsk.h \ + bpf_helpers.h bpf_tracing.h bpf_endian.h bpf_core_read.h \ + skel_internal.h libbpf_version.h +GEN_HDRS := $(BPF_GENERATED) +INSTALL_SRC_HDRS := $(addprefix $(DESTDIR)$(prefix)/include/bpf/,$(SRC_HDRS)) +INSTALL_GEN_HDRS := $(addprefix $(DESTDIR)$(prefix)/include/bpf/, \ + $(notdir $(GEN_HDRS))) +$(INSTALL_SRC_HDRS): $(DESTDIR)$(prefix)/include/bpf/%.h: %.h + $(call QUIET_INSTALL, $@) \ + $(call do_install,$<,$(prefix)/include/bpf,644) +$(INSTALL_GEN_HDRS): $(DESTDIR)$(prefix)/include/bpf/%.h: $(OUTPUT)%.h + $(call QUIET_INSTALL, $@) \ + $(call do_install,$<,$(prefix)/include/bpf,644) -install_headers: $(BPF_GENERATED) - $(call QUIET_INSTALL, headers) \ - $(foreach hdr,$(INSTALL_HEADERS), \ - $(call do_install,$(hdr),$(prefix)/include/bpf,644);) +INSTALL_HEADERS := $(INSTALL_SRC_HDRS) $(INSTALL_GEN_HDRS) + +install_headers: $(BPF_GENERATED) $(INSTALL_HEADERS) install_pkgconfig: $(PC_FILE) $(call QUIET_INSTALL, $(PC_FILE)) \ -- 2.30.2
