Currently, BPF skeleton generation rules (bpf_skel.mak) are evaluated as part of util/Build. However, because LIBPERF_UTIL_IN explicitly depends on the top-level static libbpf archive, Make completely blocked the execution of bpftool bootstrap and skeleton generation until libbpf finished compiling midway through the build. Since bpftool bootstrap compiles its own independent copy of libbpf.a, it does not depend on the top-level libbpf target. Decouple early skeleton tooling generation by attaching bpf-skel-prepare to the umbrella prepare target, exporting CONFIG_PERF_BPF_SKEL to ensure accurate feature propagation. This allows Make to compile bpftool and dump vmlinux.h in the background at build startup, eliminating the initial sub-make startup bottleneck before BPF object compilation while keeping 100% of tooling rules perfectly encapsulated in bpf_skel.mak. Provide an empty fallback target to ensure builds succeed when BPF skeletons are disabled. Tested-by: James Clark Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers --- tools/perf/Makefile.perf | 6 +++++- tools/perf/bpf_skel.mak | 8 ++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index 5af767415c11..df68d29ecab7 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -275,7 +275,7 @@ ifeq ($(PYLINT),1) endif export srctree OUTPUT RM CC CXX RUSTC CLANG LD AR CFLAGS CXXFLAGS RUST_FLAGS V BISON FLEX AWK LIBBPF READELF -export HOSTCC HOSTLD HOSTAR HOSTCFLAGS SHELLCHECK MYPY PYLINT +export HOSTCC HOSTLD HOSTAR HOSTCFLAGS SHELLCHECK MYPY PYLINT CONFIG_PERF_BPF_SKEL include $(srctree)/tools/build/Makefile.include @@ -629,8 +629,12 @@ endif __build-dir = $(subst $(OUTPUT),,$(dir $@)) build-dir = $(or $(__build-dir),.) +bpf-skel-prepare: + $(Q)$(MAKE) -f bpf_skel.mak bpf-skel-prepare + prepare: $(OUTPUT)PERF-VERSION-FILE \ arm64-sysreg-defs \ + bpf-skel-prepare \ $(LIBAPI) \ $(LIBPERF) \ $(LIBSUBCMD) \ diff --git a/tools/perf/bpf_skel.mak b/tools/perf/bpf_skel.mak index ded578b9570c..c4340a218323 100644 --- a/tools/perf/bpf_skel.mak +++ b/tools/perf/bpf_skel.mak @@ -16,6 +16,10 @@ BPFTOOL := $(SKEL_TOOL_TMP_OUT)/bootstrap/bpftool VMLINUX_H := $(SKEL_TOOL_OUT)/vmlinux.h bpf_skel_deps := $(BPFTOOL) $(VMLINUX_H) +.PHONY: bpf-skel-prepare +bpf-skel-prepare: $(bpf_skel_deps) + @: + define get_sys_includes $(shell $(1) $(2) -v -E - &1 \ | sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }') \ @@ -94,6 +98,10 @@ $(SKEL_OUT)/%.skel.h: $(SKEL_TMP_OUT)/%.bpf.o $(BPFTOOL) .PRECIOUS: $(SKEL_TMP_OUT)/%.bpf.o +else # CONFIG_PERF_BPF_SKEL +.PHONY: bpf-skel-prepare +bpf-skel-prepare: + @: endif # CONFIG_PERF_BPF_SKEL clean: -- 2.54.0.563.g4f69b47b94-goog