From 3195a75e543f95ae05a70efa515841f92ac58767 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Sat, 9 Oct 2021 22:03:41 +0100 Subject: [PATCH] bpftool: Turn check on zlib from a phony target into a conditional error One of bpftool's object files depends on zlib. To make sure we do not attempt to build that object when the library is not available, commit 86cded5d7e2f ("tools: bpftool: add feature check for zlib") introduced a feature check to detect whether zlib is present. This check comes as a rule for which the target ("zdep") is a nonexistent file (phony target), which means that the Makefile always attempts to rebuild it. It is mostly harmless. However, one side effect is that, on running again once bpftool is already built, make considers that "something" (the recipe for zdep) was executed, and does not print the usual message "make: Nothing to be done for 'all'", which is a user-friendly indicator that the build went fine. Before, with some level of debugging information: $ make --debug=m [...] Reading makefiles... Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] Updating makefiles.... Updating goal targets.... File 'all' does not exist. File 'zdep' does not exist. Must remake target 'zdep'. File 'all' does not exist. Must remake target 'all'. Successfully remade target file 'all'. After the patch: $ make --debug=m [...] Auto-detecting system features: ... libbfd: [ on ] ... disassembler-four-args: [ on ] ... zlib: [ on ] ... libcap: [ on ] ... clang-bpf-co-re: [ on ] Updating makefiles.... Updating goal targets.... File 'all' does not exist. Must remake target 'all'. Successfully remade target file 'all'. make: Nothing to be done for 'all'. (Note the last line, which is not part of make's debug information.) Signed-off-by: Quentin Monnet Signed-off-by: Andrii Nakryiko Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20211009210341.6291-4-quentin@isovalent.com --- tools/bpf/bpftool/Makefile | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 331019f6d5b16..abcef1f72d65b 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -198,7 +198,10 @@ $(BOOTSTRAP_OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(QUIET_CC)$(CC) $(CFLAGS) -c -MMD -o $@ $< -$(OUTPUT)feature.o: | zdep +$(OUTPUT)feature.o: +ifneq ($(feature-zlib), 1) + $(error "No zlib found") +endif $(BPFTOOL_BOOTSTRAP): $(BOOTSTRAP_OBJS) $(LIBBPF_BOOTSTRAP) $(QUIET_LINK)$(HOSTCC) $(CFLAGS) $(LDFLAGS) -o $@ $(BOOTSTRAP_OBJS) \ @@ -254,10 +257,7 @@ doc-uninstall: FORCE: -zdep: - @if [ "$(feature-zlib)" != "1" ]; then echo "No zlib found"; exit 1 ; fi - .SECONDARY: -.PHONY: all FORCE clean install-bin install uninstall zdep +.PHONY: all FORCE clean install-bin install uninstall .PHONY: doc doc-clean doc-install doc-uninstall .DEFAULT_GOAL := all -- 2.39.5