Re: [PATCH bpf-next v4 01/12] libbpf: skip re-installing headers file if source is older than target
From: Andrii Nakryiko <hidden>
Date: 2021-10-08 19:13:36
Also in:
bpf
On Thu, Oct 7, 2021 at 12:44 PM Quentin Monnet [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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)))
I've added INSTALL_PFX := $(DESTDIR)$(prefix)/include/bpf and used it where possible
+$(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)
I felt like INSTALL_HEADERS just adds one more indirection and otherwise is not useful, so I dropped it and inlined $(INSTALL_SRC_HDRS) $(INSTALL_GEN_HDRS) below
+
+install_headers: $(BPF_GENERATED) $(INSTALL_HEADERS)
install_pkgconfig: $(PC_FILE)
$(call QUIET_INSTALL, $(PC_FILE)) \
--
2.30.2